Electronic products are products made of electronic components or semiconductor devices, ranging from an electronic doorbell and a pocket radio to a television or a complete network communication system. The assembly of electronic products is an important type of work in electronic product manufacturing and an important link in the production of electronic products. Technicians engaged in this type of work must use professional equipment and tools to assemble scattered electronic components into electronic products that can achieve a certain function in this production process, and the electronic products must meet the quality requirements of users. . Understanding and mastering the basic skill requirements and process flow of assembly is the basic condition for being qualified to work in electronic product assembly.

    Mission points:

✧ Assembly process and operating skill requirements

✧ Reading of technical documents in the assembly process
 

1. Assembly process and operating skill requirements

1. Assembly process

       Generally speaking, the composition structure of electronic products can be represented by Figure 5-1. Electronic product systems are composed of complete machines, complete machines are composed of components, and components are composed of parts. For example, a closed-circuit television system consists of front-end satellite receivers, program recording equipment, editing and playback equipment, signal mixing and other equipment, transmission parts such as line cables, line amplifiers, distributors, branches and other modules, as well as terminal modules. Receiver, etc. Satellite receivers, amplifiers, etc. are complete machines, and the printed circuit boards, transformers, etc. in the receivers and amplifiers are their components, and the components in the printed circuit boards and the skeleton in the transformers are their parts. The composition of some electronic products is relatively simple, such as a radio, which is composed of printed circuit boards, electronic components, shells, etc. The main work of the system composed of the whole machine is connection and debugging, and there is not much manufacturing work, so here The production and assembly of electronic products mainly refers to the production process of the complete product. Therefore, the assembly process of electronic products is to first assemble parts and components into components, and then assemble the components into a complete machine. The core work is to assemble components into circuit board components or components with certain functions. From the perspective of manufacturing, the entire production process can be divided into preparation processes, installation and welding of components, inspection and repair of unit modules, final assembly (complete machine assembly) and wiring, complete machine debugging and inspection, etc.

 

1) Preparation process

The preparation process mainly includes component preparation and screening, component processing, wire processing, tin dipping and other processes. Different electronic products require different components, and corresponding electronic components should be prepared according to the type of specific electronic products. After preparing the corresponding electronic components, professionals should screen them according to relevant process requirements, such as whether the appearance packaging is good, whether the electrical performance is good, etc. The screened electronic components should also be classified according to the detailed list. The sorted electronic components must also be processed, such as lead forming, tin dipping and other processes, to facilitate subsequent installation and welding.

2) Installation and welding of components

Installation is divided into manual installation and automatic installation. Welding also includes manual welding and automatic welding. Therefore, the corresponding installation method and welding method should be selected according to different product assembly process requirements.

3) Inspection and repair of unit modules

After the printed circuit board is welded, the inspection technician will first observe the quality of the welding. If any welding, desoldering or missing soldering is found, the maintenance technician will need to perform manual repair welding. After the preliminary inspection, the corresponding testing equipment should be used to check whether the function of the unit module circuit board can be realized. Strictly speaking, after each process is completed, there is an inspection link to check whether this process meets the process requirements.

4) Final assembly (complete machine assembly) and wiring

After each unit module has passed the inspection, it should be installed in the corresponding position of the rack according to the design requirements to ensure firmness and reliability. During the assembly process, process requirements should be strictly followed, and special attention should be paid to the leads between each other to avoid short circuits or open circuits.

The final assembly and wiring are often carried out crosswise. The wiring is to connect the units to each other with wires, flexible cables, shielded wires, etc. In order to avoid mutual interference between cables and ensure stable and reliable wiring, sometimes it is necessary to group cables or fix cables, which must be carried out in strict accordance with the process requirements.

5) Complete machine debugging and inspection

Debugging is the adjustment of software or hardware to meet the requirements of the overall machine performance indicators. It is usually carried out in conjunction with the inspection after the final assembly of the complete machine. It is a key inspection to determine whether the entire electronic product installation meets the technical specifications.

2. Assembly operation skill requirements

As an electronic product assembler, possessing the following operational skills is the most basic requirement for engaging in the electronic product assembly industry.

(1) Be able to skillfully plug in electronic components and assemble chassis, racks and related parts.

(2) Master the use and connection methods of various tooling equipment, instruments and tools.

(3) Have skills in identification, screening, assembly and welding of electronic components.

(4) Have skills in assembling and adjusting electronic mechanical components.

(5) Have electronic product testing skills.

2. Reading of technical documents during the assembly process

Personnel engaged in the design, production and use of electronic products always have to deal with various electrical diagrams, text tables, instructions, etc. These diagrams, texts and tables are collectively called technical documents. Understanding the composition, requirements and characteristics of technical documents, accurate identification, correct drawing and flexible use are the basic requirements for engaging in electronic product production.

Technical documents can be divided into two categories: design documents and process documents, which are the basic basis for the production and assembly process of electronic products. Among them, design documents are the text, drawings and technical data gradually formed during the process of electronic products from development to production and assembly. They stipulate the composition form, structural dimensions and principles of the product, as well as the manufacturing, acceptance, use and operation during the assembly and production process. The technical data and instructions necessary for maintenance are the basis for formulating process documents, organizing production and product use and maintenance. Design documents mainly include circuit diagrams, assembly drawings, installation drawings, wiring diagrams, etc. Process documents are technical documents formulated based on design documents and combined with actual conditions such as production outline, production equipment, production layout, and employee skills to guide assembly personnel's operations and apply to production, process management, etc., and stipulate the specific process to achieve the requirements of the design documents. , to embody the principles of high quality, low cost and high efficiency. Process documents are the main basis for enterprise assembly production lines to carry out production preparation, raw material supply, design management, production scheduling, labor deployment, tool and mold management, process management, product economic accounting and quality control.

1. Reading of commonly used design documents

1) Block diagram

A block diagram, also known as a system diagram, is a simplified diagram that uses symbols or annotated boxes to briefly describe the basic components, interrelationships, and main features of a product. A block diagram is an illustrative graphic that is simple and clear. The box represents a group of components, a component or a functional block, and the connections express the path of signals through the circuit or the sequence of circuit actions. Block diagrams provide the basis for the preparation of more detailed technical documentation. The block diagram serves as a reference document for commissioning and repair. Figure 2 is a block diagram of a series regulated power supply, which allows us to see the full picture of the circuit, its main components and functions at all levels at a glance.

 

 

2) Electrical schematic diagram

An electrical schematic diagram is a simple diagram that mainly uses graphical symbols arranged in working order to show in detail the circuits and connection relationships of a complete set of devices, equipment and its components, regardless of the actual size, shape and location. Electrical schematics are usually drawn on the basis of block diagrams. Electrical schematics are mainly used to describe in detail the working principle of a product, also known as circuit diagrams. In electronic technology, electrical schematics are widely used. They provide a large amount of information for us to understand the working principle of the circuit in detail, analyze and calculate the parameters of the circuit, test and find faults, and provide a basis for the preparation of other technical documents. Figure 3 is the electrical schematic diagram of the series regulated power supply.

 

 

3) Parts drawing

Parts drawings are drawings that represent the materials, shapes, dimensions and deviations, surface roughness, coating, heat treatment and other technical requirements of parts used in electronic products. Parts drawings are indispensable technical documents in the manufacturing of parts.

 

4) Assembly drawing

Assembly drawings are drawings that represent product connections and assembly relationships. They are also drawings used to assemble and inspect products. In addition, when using, maintaining and repairing products, you should also use assembly drawings to understand the product's performance, working principle, transmission, connection relationship, etc. Figure 4 is a printed circuit board assembly diagram of a switching power supply.

 

5) Printed circuit board diagram

Printed circuit boards are indispensable components in electronic products. Printed circuit board diagrams can be divided into two types: printed circuit board parts diagrams and printed circuit board assembly diagrams. Figure 5 is a printed circuit board diagram of a series regulated power supply. The printed circuit board parts diagram is a drawing that represents the structural elements, conductive graphics, marking symbols, technical requirements and related instructions of the printed circuit board parts. A printed circuit board assembly diagram is a diagram showing the assembly and connection relationships between components on a printed circuit board and with the printed circuit board. Printed circuit board assembly drawings are mainly used to guide the assembly and production of printed circuit board components, and printed circuit board parts drawings are mainly used for printed circuit board production and maintenance. Using the printed circuit board assembly diagram and parts diagram, combined with the electrical schematic diagram, you can easily inspect and maintain the circuit or find faults.

 

6) Wiring diagram and wiring table

Wiring diagrams and wiring tables are simplified diagrams and tables that represent the internal connection relationships of the product and its components and are used for installation and wiring, line inspection, line maintenance and troubleshooting. They can be used in combination or independently. In practical applications, wiring diagrams and wiring tables are usually used together with electrical schematics and assembly drawings. 

 

 

7) Text and tables

Text design documents mainly include enterprise product standards, technical conditions, technical instructions, instructions for use and debugging instructions, etc. The table category mainly includes various types of detailed tables such as complete item details, complete sets of equipment details, complete sets of details, summary tables, etc.

 

(1) Technical conditions. Technical conditions are technical regulations on product quality, specifications and inspection methods, and are the technical basis for product production and use. Technical conditions are actually a type of enterprise product standards, and they are the guarantee for the implementation of enterprise product standards. In terms of certain technical performance and parameter indicators, technical conditions can be higher, stricter, and more detailed than corporate product standards.

 

The contents of technical conditions generally include: product model and main parameters, technical requirements, acceptance rules, test methods, packaging and marking, transportation and storage requirements, etc.

 

(2) Technical instructions. Technical specifications are explanatory design documents describing the main uses and scope of application, structural characteristics, working principles, technical performance, parameter indicators, installation and debugging, use and maintenance of the product, and are used for the use, maintenance and research of this product.

 

(3) Instructions for use. Product instruction manual is a design document used to convey product information and explain related issues. There are two types of product instruction manuals, one is the instruction manual for industrial products, and the other is the instruction manual for consumer products.

 

(4) Debugging instructions. Debugging instructions are design documents used for debugging during the product production process to ensure that its quality meets product standards or technical conditions.

 

Debugging instructions generally include the following content: overview, debugging environment, debugging equipment, debugging content, debugging procedures, debugging methods, debugging requirements and precautions.

 

(5) Detailed list. Various detailed lists in design documents are basic design documents used to determine product composition and quantity, and are the technical basis for product data matching, production preparation, and acceptance.

 

2. Reading of commonly used process documents

 

Process documents can be divided into two categories: process management documents and process procedure documents. Process management documents are technical documents used by enterprises to organize product assembly production and control process work. Commonly used process documents include process file catalogs, process route tables, material consumption process quota details, key parts details, etc. Process procedure documents are process documents used to specify the manufacturing process and operating methods of products or parts. According to the nature of use, they can be divided into general process procedures, special process procedures, and standard process procedures; according to the processing profession, they can be divided into electrical assembly process cards , machining process cards, wire-tying process cards, coating process cards, etc. Electronic product assembly companies can selectively prepare process documents based on their own actual conditions.

 

There are 9 commonly used formats for process documents in electronic product manufacturing enterprises.

1) cover

As the cover of a complete set of product process documents bound into a volume, "total volume" fills in the number of volumes of the complete set of process documents; "volume" fills in the serial number of the contents of this volume in the complete set of process documents; "total pages" fills in the number of all pages in this volume ; Fill in the model, name, and drawing number of the product; fill in the name of the main process content of this volume in "Contents of this volume"; finally perform the approval procedures and fill in the approval date.

 

2) Process file directory

The process file directory is a directory of process files bound into a volume, reflecting the completeness of the product process files. The "File Code" column can be filled with the abbreviation of the file, and it is not necessary to fill in the name of the file; the remaining columns should be filled in according to the title, and fill in the drawing number, name and page number of the part, component, and entire piece.

 

3) Process route table

The process route table is a concise display of the process route during the processing and preparation of the entire product, components, and parts, and can be used as a basis for the relevant departments of the enterprise to organize production. In the "Loading Relationship" column, the assembly relationships of product parts, components, and whole parts are displayed with direction indicators; in the "Component Usage" and "Whole Part Usage" columns, fill in the quantities corresponding to the product details; "Processing Route and Contents" ” column, fill in the names or codes of each department (workshop) and its process during the processing of the whole piece, components, and parts.

 

4) Wire and wire tie processing table

The wire and tie wire processing table is the basis for cutting, stripping, tin dipping, and assembly and welding of wires and tie wires. In the "Number" column, fill in the number of the wire or the number of the wire in the wiring diagram; in the remaining columns, fill in the name, specification, color, and quantity of the wire material according to the title; in the "Length" column, fill in the stripping size of the wire and the length of the stripping head. , usually end A is the long end and end B is the short end; fill in the direction of wire welding in the "Direction, Welding Place" column; the blank column is for drawing a simplified diagram.

 

5) Supporting details list

The supporting detailed list is a list of parts, components, whole pieces, materials and auxiliary materials required for assembly, which can be used by relevant departments when supporting, receiving and issuing materials. It can also be used as an attachment to the assembly process card. Fill in the "Drawing Number", "Name" and "Quantity" columns with the contents of the corresponding component and complete design document details; fill in the "Where From" column with the source of the material; fill in the auxiliary materials at the end.

 

6) Assembly process card

The assembly process card reflects the entire assembly process and is used for mechanical assembly and electrical assembly. The order of the "Installed Parts and Auxiliary Materials" columnThe number, drawing number, name, specification and quantity should be filled in with the content of the corresponding design document according to the process, and auxiliary materials should be filled in after each process; the "Process (step) content and requirements" column should be filled with the content and requirements of the assembly process; blank columns It is used for drawing processing and assembly process drawings.

 

7) Process description and diagram

Process descriptions and diagrams can be used as continuation cards for any process, for drawings, tables and text descriptions, and can also be used for preparing other process processes other than the prescribed format, such as debugging instructions, inspection requirements, various typical processes Documents etc.

 

8) Material consumption quota table

The material consumption quota table lists the quotas of all raw materials (including purchased parts, outsourced parts, and auxiliary materials) required to produce the product. It is generally based on one thousand sets as a unit, and a certain margin is left as losses in production. . It is the basis for the supply department to purchase raw materials and the financial department to calculate costs.

 

9) Process document change notice

The process file change notice is used when making permanent changes to the content of the process file. The reason for the change, effective date and processing opinions should be filled in; the "change mark" column should be filled in according to the letters of the relevant drawing management system; finally, the countersigning review and approval procedures for the change should be carried out.