Assembly of electronic blocks on printed circuit boards. Assembly of electronic equipment Designs of sealed terminals of electronic assemblies
The technology of surface mounting is not new, but, unfortunately, it is not fully covered in Russian literature. The proposed series of articles devoted to this topic will help readers more deeply understand the features of electronic module installation technologies. This article describes a number of designs of typical electronic modules and features of the assembly process of each type.
Modern electronic components
The type of installation of the modules is determined primarily by the number of parties on which the installation is carried out (single or double-sided), and the range of components used. Therefore, a description of the types of installation is logical to precede with a brief overview of the components and housings. The main, most important criterion for the technologist to divide electronic components into groups is the method of mounting them on a board - in holes or on the surface. It is he who basically determines the technological processes that must be used during installation.
The table provides information on the most common components cases: names, images, dimensions, step of conclusions. All dimensions, unless otherwise stated, are given in miles (1 mil \u003d 0.0254 mm).
| Fig. 1. TNT components |
 |
| Fig. 2. SMD components |
Table
| Hole Mounted Components | ||||
| Group | Types of Enclosures in a Group | Enclosure Dimensions | Conclusion Step | Fig. |
| With one row of conclusions - SIL | TO-92TO-202, TO-220, etc. | 380x190, 1120x135,420x185 ... | 100 mil | Fig. 1 a |
| With two rows of pins - DIL | MDIP, CerDIP | 250x381 ... 577x2050 | 100 mil | Fig. 1 b |
| With radial pins | TO-3, TO-5, TO-18 | - | - | Fig. 1 in |
| With axial terminals | - | - | Fig. 1 g | |
| Lattices - Grid | CPGA, PPGA | 286x286 ... 2180x2180 mil | 20 ... 100 mil | Fig. 1, d |
| Surface Mount Components | ||||
| With two rows of pins - DIL | "SOT-23, SSOP, TSOP, SOIC" | 55x120 ... 724x315 mil | 25 ... 30 mil | Fig. 2, a-b |
| With pins on the sides of the square case - Quad Package | LCC, CQJB, CQFP, CerQuad, PLCC, PQFP | 350x350 mil ... 20x20 mm | 50 mil ... 0.5 mm | Fig. 2 in |
| Lattices - Grid | BGA, uBGA | - | 0.75 mm (uBGA) | Fig. 3, a-b |
The most interesting from a practical point of view, according to the author, is the BGA case, or rather mBGA, which have 672 outputs with a pitch of 0.75 mm. The upper part of the BGA case is not of particular interest, more notable are its lower part and the internal structure of this package of components. In fig. 3a shows the lower surface of the BGA housing, on which the ball leads are visible, and in Fig. 3, b is a sectional view of this body.
Fig. 3. BGA housing
The above brief overview of modern components gives an idea of \u200b\u200bhow large the number of possible options for implementing the installation of modules with different locations on the board. In addition, another group was not represented in the review - the group of non-standard components (odd form components).
Mounting types can be divided according to various parameters: by the number of board sides used for mounting (single or double-sided), by the types of components used (surface, output or mixed), by their location on a double-sided module (mixed-spaced or mixed). Consider the most common of them, as well as the sequence of technological operations for each type of installation.
Types of installation
Surface mount
Surface mounting on the board can be one-sided and two-sided. The number of technological operations with this type of installation is minimal.
For one-sided mounting (Fig. 4, a), solder paste is applied to the dielectric base of the board by screen printing. The amount of solder applied to the board should provide the required electrophysical characteristics of the switched elements, which requires appropriate control. After positioning and fixing the components, a soldering operation is performed by reflowing the dosed solder. At the end of the technological cycle, the control of soldered joints is carried out, as well as functional and in-circuit control. In fig. 4a, surface-mounted components of various types are depicted: relatively difficult-to-mount components in PLCC and SOIC housings and easy-to-mount chip components.
Fig. 4. a, b
For two-sided surface mounting (Fig. 4, b), various implementation options are possible. One of them involves starting the process with the operation of applying solder paste to the underside of the board. Then, at the installation sites of the components, the calculated dose of glue is applied and the components are installed. After that, the glue is polymerized in the furnace and the solder paste is melted. The board is turned over, solder paste is applied and the components are installed on the upper side of the board, after which the upper side is melted. In this case, one-sided furnaces are used to solder the components.
In another embodiment of the double-sided surface mounting, double-sided heating furnaces are used.
An interesting question is the need to apply glue to the board. This operation is performed to prevent separation of components from the board when it is turned over. Existing calculations show that most components will not fall off the board even when it is turned over, because they will be held at the expense of the surface tension forces of the solder paste. For this reason, the operation of applying glue can not be attributed to mandatory.
Mixed installation
For mixed-spaced mounting, components installed in holes (THT components) are located on the top side of the board, and components for surface mounting are located on the bottom. In this case, a double-wave soldering operation is mandatory. Mixed-spaced component mounting is shown in fig. 5.
Fig. 5. Mixed installation
The implementation of this type of installation involves the following sequence of operations: glue is applied to the board surface onto which the SMD components are installed, the glue is polymerized in the furnace, after which the components are installed in the holes, the module is flushed, and control operations are performed.
An alternative option is possible, in which the assembly is started by installing the components in the holes of the board, after which the surface-mounted components are placed. It is used when the forming and cutting of the leads of ordinary components is carried out using special devices in advance, otherwise the components mounted on the surface will make it difficult to trim the leads passing through the holes of the board. Components for surface mounting with increased density of their placement, it is advisable to mount in the first place, which requires a minimum number of turns of the board in the manufacturing process of the product.
Mixed mounting
An example of mixed mounting is the installation on the upper side of the board and SMD- and TNT-components (mounted in the holes), and on the lower side - only SMD-components. This is the most difficult type of installation (Fig. 6).
Fig. 6. Mixed mounting
Various options for its implementation are possible. With one of them, glue is first applied to the lower side of the printed circuit board by dosing, and SMD components are installed on the applied glue. After checking the installation of the components, glue is cured in the furnace. Solder paste is applied to the upper side of the board, and then SMD components are installed on it. Application of solder paste is possible both by screen printing and by dosing. In the latter case, the operation of applying glue and solder paste can be carried out on the same equipment, which reduces costs. However, the application of solder pastes by the dosing method is unsuitable for industrial production because of the low speed and stability of the process compared to screen printing and is justified only in the absence of a screen on the product or the inappropriateness of its manufacture. Such a situation may arise, for example, in the pilot production of a large range of electronic modules, when due to the large number of processed constructs and small series, the cost of stencil production is significant.
After the SMD components are installed on the upper side of the board, they are group-soldered by reflowing solder paste deposited on a screen printer or by dosing. After this operation, the technological cycle associated with the installation of surface-mounted components is considered completed.
Further, after manual installation of the components in the holes of the board, a joint soldering of all SMD components that were previously held on the underside of the board using cured adhesive and already installed output components is performed.
At the end of the technological cycle, operations of visual inspection of soldering and control are performed.
In another embodiment, the implementation of mixed installation assumes a different sequence of operations. The first step is the application of solder paste through a stencil, the installation on the upper side of the board of complex components for surface mounting (SO, PLCC, BGA) and the soldering by melting of the dosed solder. Then, after installing the components in the holes of the board (with the appropriate trimming and fixing of the leads), the board is turned over, adhesive is applied to it and components of simple forms for surface mounting are installed (chip components, components in the SOT case). They and the conclusions of the components installed in the holes are simultaneously soldered by a double wave of solder. It is also possible to use equipment in one line that provides effective soldering of components (on the upper side of the board) by melting the dosed solder and soldering (on the bottom side of the board) with a wave of solder.
It should be noted that in the technological process that implements mixed installation, the number of control operations increases due to the complexity of assembly with components on both sides of the board. The number of soldered joints and the difficulty in ensuring their quality also inevitably increase.
Single side output and surface mounting
This technology is known in the world as the technology for reflowing solder pastes (reflow) and is one of the standard technologies for surface mounting (Fig. 7).
Fig. 7. One-way installation of SMD and TNT
The assembly of modules of this type is carried out as follows: solder paste is applied to the surface of the board, on which SMD components are installed; then the paste is melted in the furnace, THT components are installed, wave soldering is carried out, after which the assembled module is washed and controlled.
Single side output mounting
The assembly technology of such printed circuit boards (Fig. 8) is a standard assembly cycle using wave soldering. This cycle consists of the operations of installing the output components, their soldering on the installation of wave soldering and control operations. The installation of components can be either manual or semi-automatic. The choice of equipment is determined by the required performance. Automation of this type of installation is minimal, and the implementation itself is extremely simple.
Fig. 8. One-way installation of TNT
This publication is the first article in the series on surface mounting. Its logical continuation will be the coverage of the issue of the composition of the production line on which this type of installation is implemented: the need for each type of equipment, its technical characteristics and role in the technological process, the required staff and qualifications, as well as other issues that arise during the creation of assembly and installation production .
Literature
- Schmits J., Heiser G., Kukovski J. Looking to the future. Technological trends in the development of electronic components and the assembly of electronic modules on printed circuit boards. Translation and adaptation of A. Kalmykov. Components and Technologies, No. 4, 2001.
- www.pcbfab.ru.
Send your good work in the knowledge base is simple. Use the form below
Students, graduate students, young scientists who use the knowledge base in their studies and work will be very grateful to you.
Posted on http://www.allbest.ru/
annotation
The work presents the technological process (technological documentation) of assembly and installation “Devices for measuring parameters and tuning piezoelectric resonators and monolithic filters in the frequency range from 1 to 330 MHz” CPNA-330 for small-scale production, developed according to the analysis of design documentation and assembly composition, calculation manufacturability of the design, calculation and analysis of the output stroke; and a device has been developed for performing operations and cutting conclusions to size.
List of conventions, abbreviations and terms
zig-lock - type of forming pins
IET - electronic product
KD - design documentation
KMO - hole-mounted components
KMP - surface mount components
MTP - route technological process
PP - PCB
TK - terms of reference
TP - technological process
ERE - electro radio element
Introduction
The aim of the thesis is to develop a technological process for the assembly and installation of the CPNA-330 device and equipment for performing technological operations.
To achieve this goal, the following tasks were solved:
The analysis of TK;
Conducted design - technological analysis of design documentation;
The calculation and analysis of the manufacturability of the electronic cell;
The assembly scheme of the device for mass production (for a given release program) is developed, on the basis of which a route TP is developed;
The technological process of assembly and installation of a device for mass production has been developed;
To solve the tasks used a systematic approach; methods of analysis and synthesis; assembly method of electronic equipment with a base part; tabulation methods and formular data visualization; design of the assembly and installation process based on the synthesis of typical operations; acquisition of technological documentation by typical technological operations; tooling design using modern CAD systems.
1. DEVELOPMENT OF THE TECHNOLOGICAL PROCESS OF ASSEMBLY AND INSTALLATION OF THE CPNA-330
1.1 Description of the device
Purpose "Devices for measuring parameters and tuning piezoelectric resonators and monolithic filters in the frequency range from 1 to 330 MHz" CPNA-330:
Measurement of frequency and equivalent dynamic parameters of piezoelectric resonators;
Continuous visual control of the parameters of piezoelectric resonators in the process of tuning them;
Continuous visual control of the parameters of monolithic piezoelectric filters in the process of tuning them;
Measurement and plotting of the dependence of changes in the parameters of the resonators (Fs, R1, Q) on time;
Measurement of frequency response and phase response of piezoelectric resonators and monolithic piezoelectric filters.
1.2 Analysis of design documentation
The installation for measuring parameters and tuning piezoelectric resonators and monolithic filters is a block with overall dimensions of 130x256x300 mm. The device includes the following assembly units: the base of the case, the cover of the case, the front panel, the rear panel, as well as a set of electronic cells in the amount of 15 pieces.
The supporting structure of the device is the metal base of the housing. The design of the case provides reliable fastening of nodes.
On the base of the case are installed and fastened with screws several cells, including the motherboard. The remaining cells are installed in the motherboard. Some cells connect to the rear panel. The connection to the connectors on the front panel and the connection between some cells is done using wires.
The cover, front and rear panels are fixed to the base with screws.
For switching with external devices, a detachable connection using wires is used.
The base of the body. The base of the case has a U-shaped symmetrical shape with a wall thickness of 2mm. On the bottom side on the case there are rubber racks.
Case cover. The housing cover also has a U-shape. She attaches it with screws to the rail, to which the base is attached.
The front and rear panels are made of the same material as the cover with the base. They are also attached to the connection rail with screws. The panels have holes for attaching connectors and buttons.
Electronic cells. The device includes 15 electronic cells on which EREs of various types are installed. The boards are made in the second accuracy class and are covered with a green protective mask. All holes in the boards are metallized. Some boards have mounting holes for mounting into the chassis.
The reference generator board at 1000 MHz has metallized holes for mounting output components, a connector, and a microassembly. The remaining components are mounted on the surface.
ERE can be divided into groups:
1. Output elements that do not require molding: a 32-pin connector, an LED (the leads are preformed), a microassembly with an ADF4360-7 microcircuit;
2. Output elements requiring molding:
A 10 MHz crystal oscillator has 15 leads; it is mounted on a gasket; for single and small-scale production, it is recommended to fix it by springing the leads; in large-scale and mass production, fixing is recommended to be carried out due to the conclusions formed in the ZIG-lock;
The resistor assembly, the tuning resistor are fixed either by springing the terminals, or using a ZIG lock.
3. Non-lead elements are installed on the surface of the board.
Installation of elements on the board is one-sided. With single and small batch production it is possible to carry out manual soldering of ERE; for large-scale and mass production, it is recommended to solder a group billet in a furnace with subsequent soldering by a wave of output elements.
The spatial layout has 2 levels:
1st level - leadless resistors, capacitors, inductors, transistors, diodes and microcircuits;
2nd level - transformers and output components.
Components are installed from the lowest level for easy soldering.
Based on the analysis of the design documentation for the development of TP assembly and installation of the device, it is necessary to provide for subassembly:
1. Assembly of electronic cells.
2. Assembly of the base of the housing and installation of electronic cells.
3. Assembly of the front and rear panels with the preliminary formation of seats for switching elements.
4. Assembly of the housing cover.
5. Checking the device for operability.
The following operations should also be provided for assembling the electronic cell and assembling the device:
2. Forming and cutting of conclusions of ERE.
3. Installation and soldering of the ILC.
4. Installation and soldering of KMO.
5. Washing the board.
6. Drying the board.
7. The separation of the group board.
8. The output control of the electronic cell.
9. Trimming and stripping wires.
10. Marking of the device.
11. Packaging the device.
1.3 analysis of the assembly
The design of the electronic cell includes a large number of attachments of various sizes and ratings. Elements are grouped by the method of installation on the board. The IET designations according to the specification, the number of outputs of the elements and the number of elements on the board, installation options for the elements for a single production are given in table 1.3.1.
Table 1.3.1 - Installation of elements on the software prototype
|
Name |
Installation option sketch |
Notes |
|||
|
R1, R2, R4 ... R15, R17 ... R22, C1 ... C20, L1 ... L3 |
|||||
|
Installation without clearance, fixing by soldering of diagonal conclusions |
|||||
|
U3, D1, D2, D3, Q1 |
Installation without clearance, fixing by soldering one output |
||||
|
Installation with gasket, spring loaded fixing |
|||||
|
Installation without clearance, spring-loaded clamping |
|||||
|
Installation without clearance, spring-loaded clamping |
|||||
|
Installation with clearance, fixing by soldering of output |
Clearance provided by terminal design |
||||
|
Installation with clearance, fixing due to terminal design |
Clearance provided by terminal design |
ERE installation options for a given output volume N \u003d 1700 (small-scale production) are presented in table 1.3.2.
Table 1.3.2 - Options for installing elements on the PP for a given volume of output (small-scale production)
|
Name |
Installation option sketch |
Characteristics of the installation option and fixing method |
Notes |
||
|
R1, R2, R4 ... R15, R17 ... R22, C1 ... C20, L1 ... L3 |
|||||
|
U2, U4, U3, T1, D1, D2, D3, Q1 |
Installation without clearance, fixing with solder paste |
||||
|
Installation with a gap, fixing with spring-loaded terminals |
Clearance provided by terminal design |
||||
|
Installation with gasket, fixing by soldering of the output |
|||||
|
Installation without clearance, spring-loaded clamping |
|||||
|
Installation without clearance, spring-loaded clamping |
|||||
|
Installation without clearance, fixing by soldering of the output |
Clearance provided by terminal design |
||||
|
Clearance installation, tight fit |
Clearance provided by terminal design |
1.4 Calculation and analysis of the coefficient of manufacturability of electronic means
assembly electronic cell wire
The assessment of the manufacturability of cells is carried out according to a comprehensive indicator of manufacturability, which is calculated by the basic indicators of manufacturability according to the formula
where and _ basic indicators of manufacturability, and their weights.
Calculation of cell technology for a given release program.
The coefficients for the calculation and analysis of manufacturability for small-scale production of the reference generator at 1000 MHz are presented in table 1.4.1.
Table 1.4.1. - Odds for calculating and analyzing the manufacturability of the cell for a given output
|
Name |
Designation |
Value |
|
|
IC number |
|||
|
The number of contact compounds obtained by mechanized means |
|||
|
Total number of connections |
|||
|
The number of elements prepared mechanized |
|||
|
The number of operations of mechanized control and adjustment |
|||
|
Total number of monitoring and tuning operations |
|||
|
Number of types of IET ratings |
|||
|
The number of types of denominations of the original IET |
Basic indicators of the manufacturability of the reference generator at 1000 MHz for a given output volume are presented in table 1.4.2.
Table 1.4.2 - Basic indicators of cell manufacturability for a given output
|
The name of the base indicator |
Calculation formula |
Significance coefficient, i |
Notes |
||
|
IC utilization rate |
HIMS QMS Niet \u003d Niems + Nere Design indicator |
||||
|
Installation Automation Coefficient |
The number of mounting connections obtained in an automated or mechanized way. Hm is the total number of soldered joints Technological indicator |
||||
|
Coefficient of mechanization of preparation for installation |
Hmp.iet-number of elements automatically prepared for installation Niet-total number of IET Technological indicator |
||||
|
Coefficient of mechanization of control and adjustment |
Hmkm number of operations of mechanized control and tuning Hkm is the total number of monitoring and tuning operations Technological indicator |
||||
|
IET Repeatability |
Ht. Iet is the number of typical IETominals. Niet-total number of IET Design indicator |
||||
|
IET applicability coefficient |
Ht.or.iet - the number of original IET. NT.-number of typical IET Design indicator |
||||
|
The utilization rate of progressive forms |
Dpr is the number of parts of the spatial layout of the progressive form. D-total number of spatial arrangement details Design and technological indicator |
A comprehensive indicator of the manufacturability of the reference generator at 1000 MHz for a given output volume is determined on the basis of basic indicators by the formula:
The obtained value of a comprehensive indicator of manufacturability corresponds to the normative integrated indicator for small-scale production. In small-scale production, special and specialized equipment is used, while the qualifications of workers must be high.
1.5 the development of the assembly scheme of the prototype
For assembly and installation of the device, a general assembly scheme with a base part is used. As the base part, an assembly unit is selected - the base of the housing on which the electronic cell is installed. For each assembly unit, intermediate assembly schemes are developed that are combined into a common assembly scheme. At the first stage, the front panel of the device is assembled. The assembly diagram of the front panel of the prototype is shown in Figure 1.5.1.
Figure 1.5.1 - Front panel assembly diagram
At the next stage, the back panel is assembled on which the connectors are installed. The rear panel assembly diagram is shown in Figure 1.5.2.
Figure 1.5.2 - Rear panel assembly diagram
The assembly diagram of the electronic cell is shown in Figure 1.5.3.
Figure 1.5.3 - Assembly diagram of the cell electronic
3 cells are attached to the base of the device. The remaining cells are inserted into the main board. The assembly diagram of the entire device is shown in Figure 1.5.4.
Figure 1.5.4 - Assembly diagram of the prototype
1.6 the Development of the route technological process of assembly of a prototype electronic cell
The route technological process (MTP) of the assembly of the installation for measuring parameters and tuning piezoelectric resonators and monolithic filters reflects the sequence of technological operations, contains information about the equipment and the time of each operation. ICC is developed on the basis of analysis of design documentation and assembly diagram of the device.
At the first stage, preparatory operations are performed: assembling the front and rear panels of the device, unpacking, picking ERE, packaged in containers for convenient and quick search; incoming quality control, forming and trimming of findings of elements.
The prepared ERE is installed on the board in the order indicated on the assembly diagram.
After installing the ERE, soldering the terminals with a soldering iron, soldering quality control, washing and drying the board is carried out.
The assembled cells are installed on the base of the case, after which the device is closed with a lid.
The assembled device passes functional control.
A suitable appliance is marked and packaged.
The sequence of assembly operations of the prototype device is presented in table 1.6.1.
Table 1.6.1 - Initial data for filling out a route map for assembling a prototype converter
|
Operation number |
the name of the operation |
Equipment |
Time, sec |
|
|
Base assembly |
||||
|
Assembly table |
||||
|
Assembly table |
||||
|
Front panel assembly |
||||
|
Assembly table |
||||
|
Assembly table |
||||
|
Assembly table |
||||
|
Rear panel assembly |
Assembly table |
|||
|
Assembly table |
||||
|
Assembly table |
||||
|
Assembly table |
||||
|
Cell assembly electronic |
||||
|
Unpacking and picking ERE |
Assembly table |
|||
|
Installation of ERE on a printed circuit board |
Assembly table |
|||
|
Soldering with a soldering iron |
Assembly table |
|||
|
Pin cropping |
Assembly table |
|||
|
Board flushing |
Flushing unit |
|||
|
Board Drying |
Drying unit |
|||
|
Control stand |
||||
|
Instrument assembly |
||||
|
Instrument acquisition |
Assembly table |
|||
|
Front panel installation |
Assembly table |
|||
|
Rear Panel Installation |
Assembly table |
|||
|
Assembly table |
||||
|
Assembly table |
||||
|
Assembly table |
||||
|
Wiring |
Assembly table |
|||
|
Installing the instrument cover |
Assembly table |
|||
|
Functional control |
Control stand |
|||
|
Marking |
Assembly table |
|||
|
Packaging |
Assembly table |
The total unit assembly time of the prototype cell Tsht \u003d 5030 sec \u003d 84 min.
1.7 Calculation and analysis of the measure of release
The analysis of the output volume of the product is carried out in order to determine the possibility of releasing products at a given TP in a predetermined volume by the established time by comparing the unit assembly time of the product with a given output cycle. Based on the results of the analysis of the output stroke, decisions are made about the need to change the technological process, and recommendations are given on choosing more productive equipment and accessories, using group processing methods, and the volume of a batch of products.
The set output volume Nvyp \u003d 1700 pcs./year.
For a given volume of output, the output cycle is determined:
Tv \u003d f * 60 / nvyp,
where TV is the measure of release; F - the annual fund of working time (F? 2070 hours) for single-shift work; where Nzap is the startup program.
TV \u003d 2070 * 60/1700 \u003d 73 min / pc
Therefore, performance:
Q \u003d 60 / Tv \u003d 60/73 \u003d 0.82 pcs / hour
From a comparison of the piece assembly time of the cell assembly Tшт (Тшт \u003d 84 min) and the output cycle of the TV (Tw \u003d 73 min), it follows that the assembly and installation process in which manual assembly methods are used requires a change in order to reduce the piece time. For this, it is recommended to use automated installation of components on the board; selective soldering of elements installed in holes; soldering surface mounted components in an oven; equipment for group washing of printed circuit boards after soldering; carry out group drying of printed circuit boards after washing.
1.8 the development of the assembly circuit of the electronic cell in mass production
The assembly scheme is necessary to describe the sequence of basic assembly operations and serves as a data source for the development of route TP.
For assembly and installation of the device, a general assembly scheme with a base part is used. As the base part, an assembly unit is chosen - the base of the housing on which the electronic cell is mounted. For each assembly unit, intermediate assembly schemes are developed that are combined into a common assembly scheme.
At the first stage, the front panel of the device is assembled. The assembly diagram of the front panel of the prototype is shown in Figure 1.8.1.
Figure 1.8.1 - Front panel assembly diagram
At the next stage, the back panel is assembled on which the connectors are installed.
The rear panel assembly diagram is shown in Figure 1.8.2.
Figure 1.8.2- Rear panel assembly diagram
The cell assembly diagram is shown in Figure 1.8.3.
Figure 1.8.3- the Assembly diagram of the cell electronic
3 cells are attached to the base of the device. The remaining cells are inserted into the main board. The assembly diagram of the entire device is shown in Figure 1.8.4.
Figure 1.8.4- Assembly diagram of the prototype
1.9 the Development of the route technological process of assembly of the electronic cell in serial production
Considering the recommendations on improving the technological process in order to reduce piece time, the automated installation of components and the soldering of components in the furnace are selected to assemble the device in serial production; a device for winding wire cuts is being developed.
The initial data for filling out the route map for assembling the device in mass production are presented in table 1.9.1.
Table 1.9.1- Input data for filling out a route map for assembling a device in mass production
|
Operation number |
the name of the operation |
Equipment |
Time, sec |
|
|
Base assembly |
||||
|
Completion of the base of the housing |
Assembly table |
|||
|
Preparing the housing base for assembly (drilling holes) |
||||
|
Mounting plates to the base of the housing |
Assembly table |
|||
|
Front panel assembly |
||||
|
Front Panel Parts |
Assembly table |
|||
|
Preparing the front panel for assembly (drilling holes) |
Assembly table |
|||
|
Mounting elements on the front panel |
Assembly table |
|||
|
Rear panel assembly |
||||
|
Rear Panel Parts |
Assembly table |
|||
|
Preparing the rear panel for assembly (drilling holes) |
Assembly table |
|||
|
Mounting elements on the rear panel |
Assembly table |
|||
|
Cell assembly electronic |
||||
|
Unpacking and picking ERE |
Assembly table |
|||
|
Application of solder paste |
||||
|
Installing the ILC on the board |
KMP installation machine |
|||
|
Multi-zone soldering |
Multi-zone oven |
|||
|
Assembly table |
||||
|
Soldering with a soldering iron |
Assembly table |
|||
|
Pin cropping |
Assembly table |
|||
|
Board flushing |
Flushing unit |
|||
|
Board Drying |
Drying unit |
|||
|
Functional Cell Control |
Control stand |
|||
|
Instrument assembly |
||||
|
Instrument acquisition |
Assembly table |
|||
|
Front panel installation |
Assembly table |
|||
|
Rear Panel Installation |
Assembly table |
|||
|
Installation of electronic cells on the base of the housing |
Assembly table |
|||
|
Installation of electronic cells on the main board |
Assembly table |
|||
|
Fixing the cells installed on the main board |
Assembly table |
|||
|
Wiring |
Assembly table |
|||
|
Installing the instrument cover |
Assembly table |
|||
|
Functional control |
Control stand |
|||
|
Marking |
Assembly table |
|||
|
Packaging |
Assembly table |
The total unit assembly time of the cell in mass production Tpc \u003d 73 min. The obtained value of the unit time of assembly of the voltage converter is equal to the cycle for a given volume of output (TV \u003d 73 min / pc), which ensures the assembly of the device in serial production in accordance with the production program of release.
1.10 Development of a route-operational technological process
Based on the route technological process, a route-operational technological process is developed. The source data for the route-operational TP are presented in table 1.10.1.
Table 1.10.1. Initial data for filling out the route-operational card for assembling the device in mass production
|
Operation number |
the name of the operation |
Equipment and rigging |
Materials and modes |
||
|
Base assembly |
|||||
|
Completion of the base of the housing |
Assembly table |
||||
|
Unpack the container |
Packaging packaging, scissors |
||||
|
Remove the housing part from the container, visually check and put into the technological container |
|||||
|
Repeat step 02 for all housing base parts |
|||||
|
Preparing the housing base for assembly (drilling holes) |
Assembly table |
||||
|
Remove the base from the technological container |
Technological packaging |
||||
|
Install the base in the drilling fixture |
|||||
|
Remove the base in the container |
Technological packaging |
||||
|
Mounting plates to the base of the housing |
Assembly table |
||||
|
Remove housing base, plates and the required number of screws from the container |
Technological packaging |
||||
|
Fasten the plate to the housing base with screws and put the housing base into the container |
Hand screwdriver |
||||
|
Repeat transitions 01 - 02 for the second plate |
|||||
|
Front panel assembly |
|||||
|
Front Panel Parts |
Assembly table |
||||
|
Unpack the container |
Packaging |
||||
|
Remove the front panel part from the container, visually check and put into the technological container |
The packaging is technological |
||||
|
Technological packaging |
|||||
|
Preparing the front panel for assembly (drilling holes) |
Assembly table |
||||
|
Remove the front panel from the technological container |
Technological packaging |
||||
|
Drill a hole according to the drawing |
|||||
|
Repeat step 03 for all holes |
|||||
|
Remove the front panel in a container |
Technological packaging |
||||
|
Mounting elements on the front panel |
Assembly table |
||||
|
Remove front panel elements from containers |
Technological packaging |
||||
|
Install the element on the front panel and fasten if necessary with screws |
Hand screwdriver |
||||
|
Repeat step 02 for all front panel elements |
|||||
|
Rear panel assembly |
|||||
|
Rear Panel Parts |
Assembly table |
||||
|
Unpack the container |
Packaging |
||||
|
Remove the rear panel part from the container, visually check and put into the technological container |
The packaging is technological |
||||
|
Repeat step 02 for all parts of the front panel |
|||||
|
Collect the required number of screws and put in a technological container |
Technological packaging |
||||
|
Preparing the rear panel for assembly (drilling holes) |
Assembly table |
||||
|
Remove the back panel from the technological container |
Technological packaging |
||||
|
Install the panel in the drilling tool |
|||||
|
Drill a hole according to the drawing |
|||||
|
Repeat step 03 for all holes |
|||||
|
Remove the back panel in a container |
Technological packaging |
||||
|
Mounting elements on the rear panel |
Assembly table |
||||
|
Remove rear panel items from packaging |
Technological packaging |
||||
|
Install the element on the rear panel and fasten if necessary with screws |
Hand screwdriver |
||||
|
Repeat transition 02 for all elements of the rear panel |
|||||
|
Cell assembly electronic |
|||||
|
Unpacking and picking ERE |
Assembly table |
||||
|
Remove the printed circuit board from the packaging container and put the technological |
The packaging is technological |
||||
|
Remove the ERE from the packaging container, visually check for external defects and put the technological container in the container according to the drawing and the picking list |
The packaging is technological |
||||
|
Repeat transition 01 for all ERE |
|||||
|
Application of solder paste |
Solder Paste Applier |
||||
|
Remove printed circuit board from packaging |
Technological packaging |
||||
|
Install circuit board in installation |
|||||
|
Apply solder paste |
Stencil, squeegee |
||||
|
Remove circuit board from installation |
|||||
|
Installing the ILC on the board |
KMP installation machine |
||||
|
Fasten the circuit board to the installation |
|||||
|
Install items |
|||||
|
Remove the printed circuit board from the installation and put it in a container |
Technological packaging |
||||
|
Multi-zone soldering |
Multi-zone oven |
||||
|
Remove printed circuit board from container |
Technological packaging |
||||
|
Install the board on the conveyor |
|||||
|
Solder |
|||||
|
Remove the printed circuit board and put in a container |
Technological packaging |
||||
|
Visually check the quality of soldering |
Technological packaging |
||||
|
Installing CMOs on a PCB |
Assembly table |
||||
|
Remove component from container and install on printed circuit board according to drawing |
Technological packaging |
||||
|
Bend component pins |
Pliers |
||||
|
Repeat transitions 01-02 for all EREs installed on the PCB |
|||||
|
Soldering with a soldering iron |
Assembly table |
||||
|
Install the board in the board solder |
|||||
|
Solder the findings of the element to the pads |
Soldering Station |
POS-61 solder GOST 21931-76. T ° \u003d 260 + 200С |
|||
|
Repeat step 02 for all CMOs |
|||||
|
Visually check the quality of soldering |
|||||
|
Remove the circuit board from the solder and place in the container |
Technological packaging |
||||
|
Pin cropping |
Assembly table |
||||
|
Remove the board from the container |
Technological packaging |
||||
|
Trim ERE conclusions |
Side cutters |
||||
|
Repeat transition 02 for all ERE |
|||||
|
Put the board in a technological container |
Technological packaging |
||||
|
Board flushing |
Flushing unit |
||||
|
Transfer the board from container to flushing container |
|||||
|
Place the container with the boards in the washing unit and keep in the mixture under the established mode |
Flushing container |
Alcohol-gasoline mixture (1: 1) The temperature of the mixture is To \u003d 70 ± 5 ° C, time t \u003d 10-15 |
|||
|
Remove the circuit board from the washing container, visually check the quality of the washing and put in the container |
Technological packaging, washing containers |
||||
|
Board Drying |
Drying unit |
||||
|
Transfer board from packaging to drying tray |
Technological packaging, drying tray |
||||
|
Repeat step 01 for all boards |
|||||
|
Place the tray with the boards in the oven and stand in the set mode |
Drying tray |
Temperature Т ° \u003d 60 ± 50С, time t \u003d 10 min |
|||
|
Remove the tray with the boards from the oven, put on the table and stand at room temperature |
Drying tray |
Room temperature, time t \u003d 10-15 min |
|||
|
Transfer the circuit board from the drying tray to the technological container |
Drying tray, technological container |
||||
|
Functional Cell Control |
Control stand |
||||
|
To take out a cell from a container and to establish in the stand for control |
Technological packaging |
||||
|
Check the functioning of the cell according to the control instructions |
|||||
|
Remove the cell from the stand and put in a container |
Technological packaging |
||||
|
Instrument assembly |
|||||
|
Instrument acquisition |
Assembly table |
||||
|
Remove the component of the device from the packaging container and place it in the technological container |
The packaging is technological |
||||
|
Repeat step 01 for all instrument components |
|||||
|
Front panel installation |
Assembly table |
||||
|
Remove the front panel and housing base from the container and install on the housing base, aligning with the holes in the base |
Technological packaging |
||||
|
Lock the front panel with screws |
Hand screwdriver |
||||
|
Put the appliance in a container |
Technological packaging |
||||
|
Rear Panel Installation |
Assembly table |
||||
|
Remove the back panel from the container and install on the base of the housing, aligning with the holes in the base |
Technological packaging |
||||
|
Secure the rear panel with screws |
Hand screwdriver |
||||
|
Put the appliance in a container |
Technological packaging |
||||
|
Installation of electronic cells on the base of the housing |
Assembly table |
||||
|
Remove the device from the container |
Technological packaging |
||||
|
Remove the electronic cell from the container, aligning with the holes in the base |
|||||
|
Fasten cell with screws |
Hand screwdriver |
||||
|
Repeat transitions 02-03 for the remaining cells mounted on the base |
|||||
|
Installation of electronic cells on the main board |
Assembly table |
||||
|
Remove the electronic cell from the container and insert it into the main board |
Technological packaging |
||||
|
Repeat step 01 for all cells mounted on the main board |
|||||
|
Fixing the cells installed on the main board |
Assembly table |
||||
|
Remove locking components from the container |
Technological packaging |
||||
|
Lock cells with screws |
Hand screwdriver |
||||
|
Wiring |
Assembly table |
||||
|
Unwind and cut the wire with the length indicated in the drawing |
Technological packaging, range, device for cutting wires |
||||
|
Remove insulation and strip wire ends on both sides. |
Nippers |
||||
|
Tinning the ends of the wire on both sides |
Tinning bath |
POS-61 solder GOST 21931-76, bath temperature T ° \u003d 260 + 200С |
|||
|
Install the wires according to the electrical drawing |
|||||
|
Repeat steps 1-4 for all connector wires |
|||||
|
Installing the instrument cover |
Assembly table |
||||
|
Remove the instrument cover from the container and install on the base of the housing, aligning with the holes in the base |
Technological packaging |
||||
|
Fasten the appliance cover with screws |
Hand screwdriver |
||||
|
Functional control |
Control stand |
||||
|
Check the operation of the device according to the control instructions |
|||||
|
Marking |
Assembly table |
||||
|
Remove plate from container |
Technological packaging |
||||
|
Apply glue to the plate and glue on the cover of the device |
Glue PU-2 OST 4GO.029.204 |
||||
|
Keep the device in air at room temperature |
Room temperature, time t \u003d 30 min |
||||
|
Packaging |
Assembly table |
||||
|
Remove the device from the container and pack the device in a plastic bag |
Scissors, technological packaging |
Duct tape |
|||
|
Place the plastic bag with the appliance in the packing box |
|||||
|
Insert the accompanying documentation in the packaging box. |
|||||
|
Close the lid of the packaging box and secure with adhesive tape |
Duct tape |
1.11 Draft technical process
50 Installing items on the front panel
70 Mounting elements on the rear panel
90 Installing the ILC on the board
110 Installing CMOs on a printed circuit board
120 Soldering
210 Installing electronic cells on the main board
230 Wiring
240 Installing the instrument cover
Part 2 DEVELOPING EQUIPMENT
2.1 Terms of reference for the design of devices for cutting wires
2.1.1 Purpose
The device is designed for cutting wires of a given length in the aisles from 1cm to 10cm.
2.1.2. Design requirements
To develop the design of a device for cutting wires in a size that meets the following requirements:
- the device must provide the necessary range of wire lengths;
- the performance of the device must correspond to a given volume of release;
- the device must have a design that makes it easy to refuel coils with wires;
- the device for cutting wires should be designed for manual cutting;
- the design of the device for cutting wires should be easy to use, have a low cost with high performance.
2.1.3 Kinematics
The working movement of the knife occurs in a vertical plane.
2.1.4 Placement and installation
The fixture should be placed on the installer's table.
2.1.5 Operating conditions
The equipment is designed to work in the air of the production room: ambient temperature from -20 to + 600 ° C, relative humidity up to 98% at temperatures up to 350 ° C. The room must be ventilated, sharp temperature fluctuations are unacceptable during operation.
The equipment must be protected from the ingress of large particles of dust, sand on the working surface.
During storage, equipment should be packaged in oiled paper.
2.1.6 Indication of safety measures
To avoid accidents, trained personnel are allowed to work with the device.
2.1.7 Setup
Perform a test run of the device to check the efforts and direction of the knife after assembly and lubrication of moving parts. If necessary, reconfigure the device.
2.1.8 Reliability
The design of the tooling elements and the materials of the elements must provide the reliability necessary for small-scale production. In the design of the device to the maximum use standard, unified and interchangeable products.
2.1.9 Data Sources
When designing, use prototypes of tooling developed at the Department of Design and Production Technology of Electric Power Plants, the base enterprise where the technological practice took place, standard parts from the catalog - the reference book "Tooling for Cold Sheet Stamping", atlases of typical parts designs.
2.2 Design calculations snap
Calculation of the installation effort.
Since the round wire is cut with a straight knife, the calculation is carried out according to the following formula
where - the number of simultaneously trimmed conclusions, in this case.
- clamping force.
- wire cross-sectional area
.
where is the temporary tensile strength of the material.
For ordinary carbon steel.
- the number of places of application of the clamping force, in this case.
where, is the area under pressure,.
.
The value of the required force obtained as a result of the calculation satisfies the cutting efforts using auxiliary mechanisms.
2.3 Description of the sequence of assembly snap
The assembly of the device is carried out in the following sequence: assembly of the coil, assembly of the cutting knife, assembly of the limiter; general assembly of assembly units, casing, ruler and clamp obtained. The basis of the assembly is the platform; other assembly units are installed on it. The bushings are pressed into the holes.
2.4 Description of the snap
Wire cutting operation:
1. Set the stopper to the required wire length using a ruler 4.
2. Unwind the wire of the required length from the reel.
3. Secure the wire with the clamp.
4. Press the handle of the knife 2 all the way (a piece of wire will occur).
5. Release the knife (it will come to its original position due to the spring).
6. Put the cut wire in a technological container.
1. The developed technological process of assembly and installation of the CPNA-330 device ensures the production of products in serial production.
2. A device for cutting wires allows you to reduce the complexity of the preparatory operation and reduce the piece time of assembly of the product.
List of sources used
1. Design and technological design of electronic equipment / Ed. Shakhnova V.A., M .: Publishing house of MGTU named after N.E. Bauman, 2012.
2. Gridnev V.N. Lectures on the course "Technology EMU" 2007.
3. Zhuravleva L.V. Lectures on the course "Technology EMU" 2009.
Posted on Allbest.ur
Similar documents
Analysis of manufacturability of the product design, calculation of manufacturability indicators, development of the assembly technological scheme. Analysis of route technology options, selection of technological equipment and tooling, process design.
term paper, added 12.06.2010
Development of a set of technological documentation for the manufacture of a stroboscope: analysis of the manufacturability of the product design, preparation of the technological scheme of assembly of the product. Analysis of options for route technology of assembly and installation of the part.
term paper, added 10/14/2010
Determination of the type of production. The formation of the technological code of the product. Calculation of technological design and ways to increase it. Development of the technological scheme of the timer assembly. Selection and description of equipment and accessories for assembly and installation works.
term paper added 03/04/2015
Development of technology for the assembly and installation of shapers low-frequency amplifier. Analysis of route technology, justification of technological equipment, selection of the optimal process option. Design of the assembly and installation site.
term paper, added 06/19/2010
Purpose of the power supply control device, its technical characteristics. Development of a structural diagram. Calculation of the reliability of the device. The route of manufacture and the stages of the technological process of assembly of the product. Analysis of the manufacturability of the design.
thesis, added on 11/22/2016
Description of the structural diagram and the principle of operation of the USB-ionizer. The choice of radio elements and their technical parameters. Design and manufacture of printed circuit boards. The technical process of assembly and installation of nodes of computer equipment. Appearance of the device.
term paper added 04/29/2011
The development of technological processes, respectively, to a unified system for the preparation of the production of the H21e transistor meter. Analysis of the type, conditions and annual program of release. The route of the assembly design scheme, equipment selection, installation optimization.
term paper, added 10.01.2011
Definition of indicators of technological design of devices. Rules for the construction of assembly technological schemes. Development of the assembly process. Design of technological equipment and specialized equipment of all varieties.
abstract, added 07.11.2008
The technological process (TP) as the basis of the production process. Development of TP assembly and installation of shapers low-frequency amplifier. Analysis of product design. Design of the assembly and installation site, equipment for assembly and installation works.
term paper, added 06/21/2010
Consideration of the manufacturability of the design of the current amplifier. Studying the development of an assembly scheme with a base part. Carrying out a feasibility comparison of route technology options. Basic safety rules for the operation of equipment.
The structure of the assembly process.
Assembly and installation operations are the most important in the manufacturing process of manufacturing electronic components, since they have a decisive influence on the technical characteristics of products and are highly labor intensive (up to 50-60% of the total manufacturing complexity). At the same time, the share of preparing the IET for installation is about
10%, installations - more than 20%, rations - 30%. Automation and mechanization of these groups of operations gives the greatest effect in reducing the complexity of manufacturing products. The main ways to increase efficiency are: the use of automated equipment, group processing of IET, the introduction of a new element base, for example surface-mounted elements.
The automated assembly process consists of feeding components and parts to the installation site, pin orientation relative to mounting holes or pads, fixing elements on the board. Depending on the nature of the production, assembly can be carried out:
- manually with indexing and without indexing the address;
- mechanized on the pantograph;
- Automated in parallel on auto-pavers and sequentially on automatic machines or automatic lines with computer control.
The supply of elements to the installation site during automated assembly takes place by loading cassettes with IET and boards into the stores and drives of the machine, capturing the IET by the installation head and positioning. As a rule, loading cassettes is carried out manually, and only in the HAP this operation is performed using automatic vehicles. The remaining operations on the assembly machine are carried out without operator intervention. Boards with mounted IET are removed from the machine manually or automatically and sent to the polymerization of glue.
Next, the board goes to a light-mounting or conventional assembly table, where IET of low applicability are installed. After soldering, washing flux residues and fixing defects, the assembled board undergoes visual and functional control. The final operation of the assembly process is the application of a moisture-proof coating.
Figure 5.1. Scheme of a typical process for assembling blocks on a software unit.
The use of manual assembly is economically advantageous in the manufacture of products no more than 15-20 thousand pieces. per year in batches of 100 pcs. At the same time, no more than 100 elements can be located on each board, including up to 20 ICs. The advantages of manual assembly are: high flexibility when changing production facilities, the possibility of constant visual control, which allows timely detection of defects in boards or components and eliminate the causes of marriage. Disadvantages - low productivity, significant complexity of the process, the use of highly qualified working personnel.
With output volumes of the order of 100-500 thousand units. per year with the number of elements located on the board up to 500, it is economically feasible to use a mechanized assembly with a pantograph. At the same time, high flexibility is combined with greater productivity than manual assembly. In the conditions of mass production of similar products of household EA (0.5-5 million units per year), it is advisable to use automated equipment (automatic machines) or automatic lines controlled by computers.
The structure of a typical assembly process of blocks of electronic equipment on printed circuit boards is shown in Fig. 5.1.
Preparing ERE and IC for installation.
Preparation of the mounted elements for installation includes the following operations: unpacking the elements, incoming inspection, control of the solderability of the leads, straightening, forming, trimming, tinning of the terminals, placing the elements in a technological container.
The manufacturer of ERE must ensure that solderability is maintained for a specified period. However, in practice, only in Japan with its short distances and high delivery discipline, no more than 70% ERE is subject to on-site installation; in our country, delivery and storage periods may overlap the warranty.
ERE is supplied from the manufacturer in a variety of containers. Most of it is designed for loading nodes of assembly machines, however, some of the elements, including ICs, are supplied in individual satellite containers made of antistatic heat-resistant material.
For unpacking ICs in type 4 cases, machine guns of models 141-411 or AD-901 and AD-902 are used, the technical data of which are given in Table. 5.1. Unpacking the container consists in removing a thin plastic cover from the case by means of its transverse compression with the help of two rods that come into contact with the edges of the cover and, approaching each other, bend it and disengage from the case. The released cover is carried into the collection tank by a stream of compressed air, and the IC slides along the guide into the receiving cassette. The 141-411 submachine gun loads the ICs in the bookcase cartridges, and the AD-901 and AD-902 submachine guns are loaded into the direct-flow cartridges.
Table 5.1. Characteristics of automatic unpacking ICs.
Shelf and direct-flow cartridges are used for in-plant transportation of ICs with planar leads. In the first ICs lie perpendicular to the longitudinal axis of the cartridge, each in its compartment, holding on to the findings. The issuance of ICs is carried out using a pusher assembly machine. Secondly, the ICs lie longitudinally to the axis, one after another. Cassettes are mounted vertically on the assembly machine, and the unloading of the integrated circuit occurs under the action of gravity and the electromagnetic shut-off mechanism for piece-wise dispensing.
Resistors and capacitors with axial terminals are supplied glued into a double-row adhesive tape on a fabric basis. Pasting into the tape is carried out on special machines in compliance with the polarity of the elements. The coil with a diameter of 245-400 mm and a width of 70-90 mm contains up to 1-5 thousand ERE. To avoid adhesion of adjacent turns, winding is carried out with an interlayer cushion strip of cable paper. With the advent of “lead-free” IEs, tape carriers with internal slots have been proposed. The width of the media is 8, 12 and 16 mm. The nests are sealed with polyester film with a pre-heated tool.
The options for forming the terminals of the ERE and installation on the boards must comply with OST 4010.030 - 81 (Fig. 5.2).
Fig 5.2. IET Installation Options on Boards
Option I is used to install elements on single-sided boards with significant mechanical loads. In this case, a U-shaped formation of the terminals of the elements is used. Option II is used for DPP and MPP. It corresponds to the "zig" -forming conclusions. For pins with a diameter of up to 0.5 mm R min \u003d 0.5 mm, for conclusions
0.5-1.1 mm R min \u003d 1mm. Option III is recommended for a dense arrangement of elements on the board, IV - for the inter-circuit design of the block, V - for transistors with significant mechanical loads and preservation during dismantling, VI - for ICs with planar leads. To fix the ERE on the board, a “zig” formation is used on one of the ERE terminals for installation options III and IV.
The installation size should be a multiple of the grid step (2.5 mm or 1.25 mm) and provided by the tool. Limit deviations of the dimensions of the tool, holes along H12, H13, shafts h12; bending radii +0.3 mm, the rest IT14/2.
The forming-bending force of planar leads is calculated by the equation:
where k -coefficient determining the state of the surfaces of the punch
and matrices (1.0 - 1.2);
b -output width, mm;
δ is the thickness of the output, mm;
σ b - ultimate strength of the output, MPa;
P ol -pin clamping force, which is (0.25-0.3) R;
For installation option IIa, the “zig” -forming of conclusions is carried out according to the scheme shown in Fig. 5.3.
Fig. 5.3. Scheme for "zig" -forming conclusions of radio elements:
a - bending output b- education "ridge".
In feed discs 1 there are grooves into which the elements are fed by stationary forming 2. Feeding discs receive continuous rotation. Spring-loaded punches integrated in discs 3, which, when running onto the levers, acquire translational motion and form a “zig” on the conclusions. Cam 4 pushes an element 5 from the grooves of the disc into the container.
Zig size FROMcalculated by the formula:
where d 0, d -diameters of the hole and output, respectively.
The mechanization of the process of preparing conclusions for installation is carried out by the use of technological devices, semiautomatic devices and automatic machines, selected depending on the design of the ERE and the type of production. Semiautomatic device (Fig. 5.4), intended for the preparation of ERE leads with axial wire leads and cylindrical
Fig. 5.4. Semiautomatic device for preparing radioelements for tinning of conclusions.
the shape of the case, performs the following operations:
- straightening conclusions
- control of electrical energy parameters by electrical parameters with the classification “suitable” - “not suitable”,
- stripping and trimming of conclusions,
- laying ERE in technological cartridges.
Radio elements 7 are loaded manually in the guides 2, by which using a cutter 3 fed to the straightening mechanism 4 one at a time, then into the clamps 6 control mechanism 5. The leveling of the terminals is carried out using spring-loaded punches. Monitoring and sorting by electrical parameters is carried out by a device connected to the terminals 6. If there is a defective element, the device sends a signal to the reject cut-off mechanism 7 and the part is discarded from the rotor. Qualitative EREs enter the stripping mechanism 8, where various brushes are removed with metal brushes. Next ERE are fed to the trimmer 9, then loaded into the process cassette 10.
Leveling of conclusionsin small-scale production, they are carried out either manually with tweezers and pliers, or in a straightening device (simultaneously
20 - 50 conclusions of ERE of model GG 1422-4101 with a productivity of 500 pieces / h). To prepare the ERE and IMS for assembly, various equipment is used (Table 5.2).
Table 5.2. Equipment for the preparation of ERE and IMS.
| Name, type | Type of ERE, IC | Productivity, pcs / h | Drive, power, W | Dimensions, mm |
| Semi-automatic preparation of resistors and diodes, GG-2420 Installation of straightening and trimming the leads of transistors GG-2293 Automatic machine of the U-shaped form of leads ERE, GG-1611 Automatic machine for forming the conclusions of microcircuits, GG-2629 Semiautomatic device, АРСМ2.230.000 Semi-automatic, GG-2125 | MLT-0.195; 0.25; 0.5; 1.0; 2D503; 509. MP42, MP416, GT309 MLT-0.125, 0.25, 0.5 1-1MS 14-1404. 14-3 KM options III, IV Case 301.12-1; 401.143 | Electromechanical, 50 Electromagnetic, 80 Electromechanical, 180 Electromechanical, non-pneumatic, 500 Electromechanical, pneumatic, 800 Electromechanical, 180 | 600 × 500 × 800 295 × 215 × 275 330 × 380 × 405 900 × 400 × 1500 2200 × 1000 × 1500 335 × 300 × 305 |
Tinning of conclusions can be carried out both before and after molding by immersion in molten solder. For flux hot tinning of the terminals of the integrated circuit (case 401.14-3), an automatic machine of the GG-2630 model is used. The productivity of the machine is 900 pcs / h, the limits for regulating the temperature of solder are 200-280 ° C with an accuracy of ± 5 ° C. The tinning of the ERE conclusions in a group way is carried out on a mechanized installation GGM2.339.002. Its productivity is 400 cassettes / h, the exposure time of the cassettes in flux and solder is 1.5 -3 s.
Brazing the solder -one of the ways to fix a strictly dosed amount of wire solder to the terminals of the IC by means of its deep plastic deformation. The solder is held at the terminals due to mechanical jamming of the protrusions extruded into the space between adjacent terminals. Typically, for leads with a cross section of 0.3 × 0.1 mm (housing 401.14, etc.), a solder wire with a diameter of 0.3-0.4 mm or a tubular solder with a flux core 0.5 mm in diameter is used.
The placement of discrete ERE in the technological container allows to increase the assembly performance and to mechanize the installation of elements on the boards. Adhesive tape is also used as a container, into which ERE is mainly glued with axial leads according to the program. Pasting is carried out on the installation of the GG-1740. ERE in technological cassettes are loaded into drives, from where, according to the program, they are fed to a transport device, moving along which they fall into the gluing zone. The productivity of the machine is 2400 pcs / h, the number of elements in one program is 2-12 pcs, the gluing step Sa multiple of 5 mm, the width of the tape is 6 or 9 mm. Polar IETs are glued to the tape in a uniquely oriented position (Fig. 5.5, a).
Fig. 5.5. Packing the IET in a single-row tape (a) and in a cartridge (b)
Elements with unidirectional leads are glued into a single row perforated tape 18 mm wide. The spacing of the insert is 15 mm, the distance between the terminals is 2.5 or 5 mm. KG and IC type transistors are delivered in special direct-flow single-strand process cassettes (Fig.5.5, b)
Approved by the University’s Editorial Board
UDC.621.396.6.001.63
Vinnikov, V.V. Basics of designing electronic tools: a tutorial: in 2 books. Prince 2 / V.V. Vinnikov. - St. Petersburg: Publishing House of SZTU, 2009 .-- 223 p.
The manual was developed in accordance with the requirements of state educational standards of higher education.
The second book of the manual addresses issues related to design engineering; protection of electrical structures; designing ES taking into account the requirements of ergonomics and design.
The manual is intended for students of specialty 210201.65 - "Design and technology of electronic devices" and the direction of preparation of the bachelor 210200.62 - "Design and technology of electronic tools", studying the discipline "Fundamentals of design of electronic tools."
Resentants: V.I.Sokolov - Doctor of Phys.-Math. sciences, prof., scientific consultant lab. Physical-Technical Institute of the Russian Academy of Sciences; A.E. Kalmykov, Ph.D. Phys.-Math. Sciences, Art. scientific al. Physical-Technical Institute of the Russian Academy of Sciences.
Ó North-West State Correspondence Technical University, 2009
Ó Vinnikov V.V., 2009
FOREWORD
This tutorial is intended for students of specialty 210201.65 - "Design and technology of electronic devices" and the direction of preparation of the bachelor 210200.62 - "Design and technology of electronic tools." It should help them in studying the discipline "Fundamentals of Designing Electronic Tools" of the cycle of general professional disciplines (federal component). In addition, the manual can be used by students of specialty 210302.65 - "Radio Engineering" and 230101.65 - "Computers, complexes, systems and networks" when studying the disciplines "Fundamentals of design and production technology of RES" and "Design and technological support for the production of computers", respectively.
The purpose of the manual is to provide students with material for the following sections of the discipline work program: design engineering (design of elements of supporting structures of ES; information technology of ES design); protection of electrical structures; design of ES taking into account the requirements of ergonomics and design. The discipline "Fundamentals of Designing Electronic Tools" is a logical continuation of the discipline "Fundamentals of Design and Reliability of ES" and is associated with the disciplines "Fundamentals of Designing RES" and "Modern Design Methods and Technologies of RES".
INTRODUCTION
The discipline "Fundamentals of Designing Electronic Tools" is a logical continuation of the discipline "Fundamentals of Design and Reliability of ES", and, therefore, all the material studied in this discipline should be used to study it and deepen knowledge on the design of ES (RES). On the other hand, the discipline under study is the basis for a deeper study of a number of design methods, and first of all, verification methods for calculating RES designs for the admissibility of thermal, electromagnetic, mechanical and other modes of their functioning, which will be studied in the fifth and sixth courses in the discipline "Design Basics RES ". In this regard, the consideration of these methods in the studied discipline is not carried out, and the main attention is paid to the design design of functional units and modules that are printed.
This manual (book 2) is a logical continuation of the training manual "Fundamentals of the design of electronic tools", book 1. Therefore, when studying discipline, one should start with it.
This manual has a subject index, a bibliographic list of used literature, as well as questions for self-control.
1. The design of modules es
1.1. Design of sealed cells and blocks
General principles for the arrangement of structural elements in sealed units are similar to unpressurized structures. A significant difference is the provision of the necessary tightness, as well as the specificity in heat removal to create normal thermal conditions in the unit. The method of conductive heat sinks has found widespread use for cooling hermetic blocks, which provides the most rational heat removal from used open-circuit integrated circuits (ICs), integrated circuits (ICs) and microassemblies (MSBs).
All open-circuit ICs and MSBs in sealed units are installed on individual or group heat-dissipating buses, the latter, in turn, in contact with the block body, which allows heat to be transferred from the elements to the case. Heat removal from the block body occurs by natural convection, for which the surface of the block is increased due to its finning or forced air blowing over the block body. To increase the power dissipation of the unit, air ducts are introduced into the unit that do not violate the tightness of the unit casing. To equalize the thermal fields of the elements inside the block body, a fan is installed in the block, which carries out internal mixing of the gas filling the block. Individual and group thermal buses provide smoothing of the thermal field on the substrates of housingless ICs and MSBs. Considering the foregoing and the fact that the use of open-packed NS and MSB increases the packing density of elements and, accordingly, the dissipation power in the block, the specific designs of sealed blocks and their cells differ significantly from the designs of leaky blocks, although the general principle of layout and design options for blocks (detachable and book) saved.
The calculation of the number of open-circuit ICs and SMEs on the cell printed circuit board is carried out according to the method for determining the number of case elements. Chassis-free SME installation is shown in Fig. 1 . It is recommended that you select the steps for installing unpackaged SMEs in Table. 1.
Installation steps for unpackaged SMEs depending on the average number of outputs involved, in which it is possible to use double-sided printed circuit boards with one-sided installation of single-chip MSBs and multi-layer printed circuit boards (MPP) with two-sided installation of unpacked microassemblies with at least four layers (for the manual design method) are given in table. 2. Recommended steps are given for the case when the output contacts of the unpackaged SMB are located on both sides of the SMB substrate.
Fig. 1. Installation of a frameless MSB on a metal base: 1 and 2 - boards; 3 - metal base; 4 - conductor; 5 - contact area
In fig. Figure 2 shows the layout of the seats for unpackaged SMEs. By analogy with cells made using housing elements, we introduce the concept of the sizes of edge fields on a printed circuit board. Under the size of the marginal fields x1, x2, at1 and at2 ;, we mean the distances from the edge of the printed circuit board along the axes X and Y up to the first row of contact pads for external terminals of unpackaged SMEs. Edge field at2 for all standard sizes of film boards (substrates) of open-frame MSBs is 12.5 mm when using test pads with pin seals in metallized holes or using printed contact pads and 10 mm when using single pistons and contacts as control elements.
The minimum technological dimensions of the marginal fields of printed circuit boards when installing open-frame MSBs, rounded to values \u200b\u200bthat are multiple of 2.5 mm, without taking into account the tracing of printed conductors, are given in table. 3. When mechanized assembly of cells on printed circuit boards provides edge fields with a width of at least 5 mm. In fig. 3 ... 6 presents typical designs of cells of sealed blocks of detachable and book design options.
Table 1
Steps for installing frameless microassemblies on cell circuit boards
|
Installation step of the axle-free microassembly along the axes, mm |
Sizes of a film payment of a caseless MSB, mm |
|||||||||
Note: 1- plus sign (+) corresponds to the recommended installation steps;
table 2
Installation Steps for Unpackaged SMEs (BSMB) depending on the average number of pins involved
|
film |
Average number involved conclusions in one BSMB, mm no more |
Installation step BSMB on the axes, mm |
|
Fig. 2. Marking of seats for unpackaged SMEs
Table 3
Marginal fieldsx 1, x 2 on software when installing BSMB
Fig. 3. The cell of the sealed unit is detachable design: 1 - printed circuit board; 2 - unassembled microassembly; 3 - metal tire; 4 - contact electrical connector
Fig. 4. The cell of the sealed block book design: 1 metal base; 2 - unassembled microassembly; 3 - duct: 4 - electrical contact; 5 - printed circuit board
R 
ex. 5. Cell of a sealed block of book design with a frame: 1
- printed circuit board; 2
- metal tire; 3
- case microassembly; 4
- printed contact
Fig. 6. The cell of the sealed block book design:
1 - printed circuit board; 2 - metal tire; 3 - micro assembly
The cell shown in Fig. 3, consists of metal tires to which a printed circuit board is attached with hollow rivets. Frameless SMBs are directly mounted on metal buses on both sides of the circuit board. A clamping bar is mounted to the end of one of the sides of the printed circuit board through metal tires, which has tides for attaching the cell in the unit with captive screws. On the opposite side, contacts are established by flaring and soldering into the holes of the printed circuit board, designed to electrically connect the cell to the backplane of the unit.
To remove heat from the cell, the clamping bar has good thermal contact with the metal tires of the cell. The cell shown in Fig. 4, consists of a U-shaped metal base to which a rectangular duct is connected by welding. The duct has tides for mounting and swiveling the cells in the block. The circuit board of the cell is attached to the base with hollow rivets. Shellless SMEs are directly installed on the base from two sides. The electrical connection of the cell with the unit backplane is made using a flexible printed cable. To remove heat from the cell, the base has good thermal contact along the entire length with the air duct.
The cell shown in Fig. 5, consists of a cast frame, to which a printed circuit board is mounted with hollow rivets with metal buses mounted on it from two sides.
Chipless microassemblies are placed directly on the metal busbars. Tides are provided on the frame for articulating the cells in the block. To mount the cell in the block, adapter sleeves are made through which the fixing screws pass. The electrical connection to the unit backplane is made using a flexible printed cable. To remove heat from the cell, the frame has good thermal contact with the cell tires.
The cell shown in Fig. 6, consists of a printed circuit board with housing without MSB mounted on its two sides on individual metal busbars. The cells have loops for articulating the cells in the block. On the printed circuit board, holes are provided for attaching the cell to the unit with screws. The electrical connection of the cell is made using volumetric wires, which are stitched through two rows of non-metallic holes located on the printed circuit board to protect against breaking.
In fig. Figure 7 shows the design of a sealed cell with switching elements and unpacked MSBs. The design consists of a rectangular case, on the bottom of which a film is glued or a patch board is installed. Two flexible cables of foil-coated polyimide are pressed into the holes on the rear side of the housing with plastic, on which connecting conductors and contact pads are formed by chemical etching. The terminals of the electrical connector SNP34 are fixed in the contact pads. A flexible cable is placed between two plastic gaskets worn on the terminals of the electrical connector. On top of the case is closed by a lid, which is sealed by soldering with the cell body. On the sides of the case there are tides used to install the cell in standard BNK2 guides; the cells are fixed with screws. On the underside of the cell body there is a recess for installing pin radiators made of titanium tape.
R 
ex. 7. Airtight cell with housing without MSB
In fig. Figures 8 and 9 show typical designs of sealed units with microassemblies. The hermetic detachable design block (Fig. 9) consists of a set of cells on unpacked MSBs (see Fig. 3) installed parallel to the front panel. The cast block body is made of Al9 aluminum alloy. The block is sealed with rubber gaskets installed in the slots of the block body and bolted to the side covers of the block. The body and side removable block covers are ribbed. To mount the cells in the block on the upper and lower walls of the housing, group guides and tides with threaded bushings are provided. On the front panel there is a connector that is sealed through a gasket, and a tube for pumping air and filling with dry nitrogen. On the rear panel of the unit housing are pin catchers. The inter-unit electrical connection between the cells is carried out with the help of jumper jumpers installed on the pins of the backplane.
To improve thermal contact between the clamping strips of the cells and the ribbed side cover of the block, a corrugated aluminum gasket is laid.
Fig. 8. Block of sealed detachable design: 1 - cell; 2 - front panel; 3 - wall; 4 - back panel; 5 - side cover
Fig. 9. Sealed book block with air duct: 1 - cell; 2 - front panel; 3 - casing; 4 - fee; 5 - flexible printed cable; 6 - duct
A sealed book block with a vertical cell opening axis, shown in Fig. 9, consists of a set of cells on unpacked MSBs (see Fig. 4), which are installed perpendicular to the front panel of the unit. The front and rear panels are die-cast from Al9 aluminum alloy and are coated. The casing of the welded block is made of a titanium alloy with a coating followed by hot tinning with POS-61 solder. The side walls of the casing have stiffeners.
The unit is sealed by soldering the casing with the front and rear panels of the unit. On the front panel of the unit are a connector that is sealed through a gasket, a tube for pumping air and filling the unit with dry nitrogen, as well as holes for supplying and discharging air into the air manifold. On the front panel of the unit are pin catchers.
Intra-block electrical connections are made using flexible printed cables and a backplane. Heat is removed from the unit with the help of forced air through sealed ducts.
Fig. 10. Sealed book block with fan: 1 - fan; 2 - front panel; 3 - cell; 4 - motherboard; 5 - flexible printed cable; 6 - back panel; 7 - wall
An airtight block of book design with a vertical axis of cell opening (Fig. 10) consists of a set of cells on unpacked MSBs (see Fig. 5), which are installed perpendicular to the front panel of the block. Block body welded. The details of the block body are made of AMg material, the front and rear panels of the block are die-cast from Al9 aluminum alloy.
All body parts and panels are coated. Block sealing is carried out by soldering the case and the front panel of the block.
The pressurized block of a book design with a horizontal axis of cell opening, shown in Fig. 11, consists of two cells (see Fig. 6) on open-frame MSB installed perpendicular to the block panel. The frame of the block is made by injection molding of aluminum alloy Al9. The panel and the casing of the block are made of titanium alloy and have a coating followed by hot tinning with solder. The unit is sealed by soldering the casing with the panel. In the case for fixing the frame with cells there are stops, and for fastening the cells in the panel and frame there are tides. The panel contains electrical connectors obtained using multi-pin eye connections, a tube for pumping air and filling with dry nitrogen, and threaded catcher pins. Intra-block electrical connections are made using volumetric wires.
The set of considered NC blocks allows us to solve design problems for a wide range of hardware developments. It should be borne in mind that blocks with general sealing are characterized by a high packing density of elements.
Fig. 11. Block tight book design: 1 - cell; 2 - frame; 3 - panel; 4 - volumetric wire; 5 - casing
Sealing blockscontaining ICs and MSBs, is carried out in order to prevent the impact of external climatic factors on the shells that are part of the ICs and MSBs, i.e., they are sealed to establish the permissible relative humidity and composition of the gas filler inside the unit, which is determined by the technical conditions for incoming in the composition of the block unpacked elements.
To create the most favorable microclimate inside the block case, the internal volume of the block through the pumping tube is filled with an inert medium in the form of various gases or gas mixtures. In order to increase the life or storage of sealed units before preventive maintenance, the internal volume of the unit is filled with an inert medium with an overpressure of not more than 12 10 4 Pa \u200b\u200bthrough pumping tubes (Fig. 12, hell).
Fig. 12. Designs of pumping tubes: 1 - housing; 2 - a tube; 3 - sleeve; 4 - compound; 5 - a glass; 6 - rubber compressor; 7 -ball; 8 - pin
To create an inert atmosphere, dry nitrogen is used, which in its thermal characteristics is equal to air. Work is also underway to use as an inert medium various liquid non-toxic solutions with thermal conductivity an order of magnitude higher than that of dry nitrogen. However, the influence of these liquids on the electrical parameters of open-frame elements and, accordingly, on their reliability, has not always been fully studied.
The tightness of the blocks is ensured by sealing their housings and external electrical connectors, which are installed on the front or rear panels of the housing. Given the specifics of sealing the enclosures of blocks and electrical connectors, these issues must be considered separately.
Sealing of block bodies can be carried out in the following ways: by welding the base and block body; soldered dismantled connection of the housing (base) with the cover (casing) of the block; sealing gasket. The choice of sealing method is determined by the requirements for the blocks depending on the operating conditions, the size (volume) of the block, as well as the materials used in the housing and in the base of the block.
Sealing by welding. The opening of such blocks is possible only with the help of mechanical removal of the weld, which entails the mandatory hit of metal dust on the housing elements and, accordingly, their failure.
Sealing with a soldered dismountable joint. The following requirements are imposed on the elements of the solder joint of the block design: to eliminate overheating of the block at the time of soldering, it is necessary to provide a thermal groove in the structural elements of the lid body (near the solder joint); laying should be performed with a rectangular cross-section of heat-resistant rubber; the diameter of the wire should be less than the gap width between the cover and the body by 0.1 ... 0.2 mm.
In a soldered connection, the wire above the gasket is laid around the entire perimeter of the connection. One of the ends of the wire is led out through the groove in the lid from the connection zone and is usually laid in a thermal groove. The distance along the entire perimeter of the joint is filled with fusible solder. This soldered connection allows you to dismantle (open the case) of the unit up to three times.
In order to prevent violation of the tightness of the block, the outer surface of the solder joint should not be the mounting surface of the block and all fastening elements of the blocks should be located at the maximum possible distance from the solder joint.
Sealing with gaskets. Structural elements of sealing the enclosures with gaskets are shown in Fig. thirteen.
Sealing and design of special electrical connectors, the tightness of which is carried out using metal-glass joints, have a number of specific aspects, so this issue should be considered in more detail. All metal-glass joints that are used in the design of microcircuits, microassemblies and sealed units of microelectronic equipment can be divided into the following types: eye, disk, window and flat.
Eye connectionsare used in the manufacture of relay bases, bases of IP and MSB housings, pressure leads, metal legs of electric vacuum devices, plugs for electrical connectors and similar products.
Disk connectionsused in the manufacture of multi-contact current inputs, plugs of electrical connectors, components of vacuum equipment, housing bases.
Perioperative connectionsthey are used in the manufacture of resonator windows, high-pass filters and inspection windows of devices necessary for visual inspection.
Flat jointsare used in the manufacture of bases for metal-glass cases of IP and MSB with a rectangular section of the terminals.
Fig. 13. Sealing the case of blocks with a sealing gasket: 1 - the base of the block; 2 - gasket sealing; 3 - block body; 4 - a bolt; 5 - nut
Metal-glass compounds, depending on the materials used, are divided into agreed and inconsistent (compressed) junctions. Coordinated junctions are understood to mean compounds in which the coefficients of thermal expansion (KTR) of the materials being soldered (glass-metal cages) are equal to or slightly different from each other. In turn, inconsistent junctions are understood to mean compounds in which the KTR of the materials being soldered (glass - metal cages) sharply differ from each other in the temperature range from room temperature to the glass softening temperature. Therefore, when designing individual components of microelectronic equipment, great attention must be paid to the choice of materials and, accordingly, to their mutual combination.
Ocular connections should be understood as compounds in which one or more of the terminals are soldered (fused) into a metal ring through an individual insulator for each terminal. Such designs of eye connectors are shown in Fig. 14 and 15.
Disk connections are made in the form of coordinated and inconsistent junctions (Figs. 16 and 17). In the disk connection (Fig. 16), the glass insulator is arranged symmetrically in height 
.
Minimum lead spacing 
and between the terminal and the wall 
clips should be at least 0.8 of the diameter of the output.
Fig. 14. Ophthalmic single-ended connections:
a- design with a flange (or hood) of the eye in the sheet metal; band in- structures with punching (or drilling) of an eye in thick-walled metal; 1 - metal clip; 2 - output (rod or tube); 3 - glass insulator
Fig. 15. Eye multi-terminal connections: a - a design with a flange of the eye in sheet metal: b- punching or drilling design in thick-walled metal; 1 - metal clip; 2 - output (rod or tube); 3 - glass insulator
Window connections can be made by directly soldering glass with metal or using low-melting enamel.
Flat joints are understood to mean joints in which metal parts are soldered to glass on a flat surface.
Fig. 16. Disk connections. Fig. 17. Disk connections.
Agreed Junction: 1 - Inconsistent junction: 1 –
metal clip; 2 - conclusion; 2 - metal clip;
conclusion; 3 - glass insulator 3 - glass insulator
In the manufacture of electronic equipment based on microelectronics, specific requirements are imposed on the implementation of microelement connections inside microcircuits, as well as the installation of microcircuits in nodes and blocks.
The methods of installation, soldering and welding used in the manufacture of microchips differ from the methods used in the production of functional units and micromodules. This is due to the fact that most semiconductor materials and dielectric substrates of ceramics and glass have low thermal conductivity, a narrow ductility zone and low resistance to thermal and mechanical stresses.
Semiconductor integrated circuits, unlike thin-film ones, have an order of magnitude higher resolution of the pattern, which allows to increase the density of microelements (i.e., increase the degree of integration). Compared to thick-film integrated circuits, the degree of integration is increased more than a hundred times.
The internal installation of any microcircuit includes technological operations for the installation and fastening of one or more microcircuits in the case and making intra-microcircuit connections. For the assembly and installation of microcircuits, various installations are used. So, for the assembly of crystals of semiconductor integrated circuits from 0.6 x 0.6 to 1.8 x 1.8 mm in size, the EM-438A installation is used, and for the installation of several crystals in one housing, the EM-445 installation. The chip is mounted by soldering or gluing.
Intra-microcircuit connections between the contact pads of the microcircuit sprayed onto the crystals and the terminals of its housing are performed using wire jumpers, which are used as copper, aluminum and gold microwires with a thickness of 8 to 60 microns.
Depending on the combination of the materials used and the design of the terminals, the microcircuit (thermocompression, ultrasonic, contact, electron beam, laser) or micropaque is used for the connection when assembling microcircuits.
The most widely used are thermocompression and ultrasonic microwelding and microwelding.
Thermocompression microweldinglies in the simultaneous impact on the welded metals of pressure and elevated temperature. The metals to be joined are heated to a certain temperature (the beginning of recrystallization), at which the adhesion (diffusion) of metal surfaces cleaned from oxides begins when even a small load is applied. This method allows you to connect electrical leads with a thickness of not more than a few tens of microns to the contact pads of crystals whose sizes do not exceed 20 ... 50 microns. In the process of joining, a microwire of aluminum or gold is applied to the semiconductor crystal and pressed with a heated rod.
The main parameters that determine the mode of thermocompression microwelding are specific pressure, heating temperature and welding time.
When thermocompression microwelding requires careful monitoring of these parameters.
The scope of thermocompression microwelding is very wide. It is the main method of attaching leads to semiconductor crystals; it is also used to attach wire microconductors to sprayed contact pads of microcircuits, for mounting LSIs and microassemblies. Using thermocompression microwelding, group welding of microcircuits with planar leads is performed, as well as precision microwelding of elements with a minimum thickness of conductors (up to 5 microns).
Ultrasonic microweldingallows you to get a reliable connection of metals with oxide surfaces of crystals with minimal thermal impact on the structure of heat-sensitive chip elements. This type of microwelding is used to connect metals with different electrical and thermal conductivity, as well as to connect metals with ceramics and glass.
The domestic industry produces ultrasonic devices for connecting a microwire or microtape (with a diameter of up to 60 microns) of aluminum and gold to crystals of semiconductor microcircuits, for carrying out intracase mounting of microcircuits, and also for assembling LSIs and microassemblies.
Equipment for the installation of semiconductor devices and microcircuits by the method of ultrasonic microwelding consists of an ultrasonic welding machine, the principle of which is based on the excitation of mechanical vibrations of the ultrasonic frequency by the transducer in the place of the parts being welded, and a device for fixing the microcircuit.
Magnetostrictive and piezoelectric devices are used as converters of electrical energy into mechanical vibrations.
In ultrasonic welding, an inseparable connection of metals is formed as a result of the combined action of mechanical vibrations on parts with a frequency of 15 ... 60 kHz, relatively small compressive forces and the thermal effect accompanying welding. As a result, a small plastic deformation appears in the welded zone, which provides a reliable connection of parts.
In recent years, a combined method based on thermal compression with indirect pulse heating and the application of ultrasonic vibrations has been widely used for mounting microcircuits.
Micro solderingcan be carried out by soft and hard solders. The main advantages of microwelding are its relative simplicity and the ability to connect parts of complex configuration, which is difficult to accomplish with microwelding.
TO soft soldersalloys of tin and lead, indium and gallium, tin and bismuth, which have a low melting point (usually 140 ... 210 ° C). These solders are most often used when soldering in integrated circuits.
When micro-soldering microcircuits with soft solders, the metals to be joined should be metallurgically and chemically compatible, should not form alloys with high resistance and intermetallic brittle joints at the contact point; solders should be inert at the operating temperature of the circuit and completely removed from the joint and from the surrounding surface.
To solid (high temperature) soldersalloys based on silver ПСр45 and ПСр50, having a melting point up to 450 ... 600 ° C. These solders are used to seal the cases of microcircuits, to connect silver or silver-plated parts (since solders based on tin - lead dissolve a significant amount of silver, changing the characteristics of the contact), etc.
Currently developed high-tech micropaque methods. One of such methods is microwelding in an atmosphere of hot (up to 400 ° C) inert gas or hydrogen, in which a pre-tinned section is blown from miniature nozzles by a hot gas stream. This method provides high performance, in addition, eliminates the use of flux.
The soldering process is simplified by using dosed solder in the form of tablets or pastes, which are previously applied to the joints. This method provides precise control of the amount of heat at the weld site, and when using automation tools, it allows you to adjust the current flow time and its value.
For mechanized microfusion, step-by-step movements of the soldering tool, usually carried out according to the program, and pressing by the tool of the soldered connection during soldering are characteristic. Automation of soldering processes when connecting integrated circuits to a circuit board along with increased labor productivity provides an increase in the quality of connections.
It might be useful to read:
- Summary: Analysis of the methods of the effectiveness of the quality management system processes;
- Contract for the provision of paid educational services (training contract): we draw up the right places for education contracts;
- Hardware Diagnostics;
- Automation of the technological process of collecting wastewater treatment;
- Classification and types of innovations;
- Assembly of electronic equipment Designs of sealed terminals of electronic assemblies;
- Methodological foundations of commercial activity;
- Selection and calculation of welding modes;