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The electronics industry is a major employer of drafting technicians. Almost all products use some form of electronic device, or they are made on machines that are controlled by such devices. These devices have led to the creation of a highly specialized area of drafting which has its own drafting rules, symbols, and techniques.
Several types of drawings are used only in the electronics industry. These include: block diagrams, wiring diagrams, schematic diagrams, logic diagrams, and printed circuit board (PCB) drawings. Printed circuit boards have a subgroup of drawings that are unique to their manufacture.
The main difference between electronic and mechanical drawings is that electronic drawings are not drawn to any scale. Schematic, block, and wiring drawings define how electronic devices work together, not what size they are. In PCB drawings, the drawing becomes the "pattern" for the final parts, thus affecting their size.
The electronics industry also uses mechanical drawings for such items as sheet metal parts, cabinets, and molded plastic connectors. These drawings are subject to the same rules and techniques as other mechanical parts.
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BLOCK DIAGRAMS |
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| 23.1 Block diagrams often are used early in the design process. Note the similarities of the types of diagrams listed here to the functional diagrams listed in Section 20.3.5. Types of block diagrams include: organization charts flow charts functional charts |
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SCHEMATIC DIAGRAMS |
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| 23.2 Schematic drawings represent the next stage of designing an electronic circuit. Moving beyond representing the basic functionality of the portion of the circuit, specific components are represented using standard symbols. Though the schematic is more refined than a block diagram, the spatial relations of the electronic components and their connections on a board still have not been defined. |
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WIRING AND CABLING DIAGRAMS |
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| 23.3 For larger electronic assemblies, how multiple circuits and/or boards are wired together has to be represented with a wiring or cabling diagram. The specific type of diagram depends on the degree of complexity of the wiring and how the drawing is to be used. Common types of diagrams include: wiring harness diagrams cabling diagrams highway diagrams |
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PRINTED CIRCUIT BOARDS |
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| 23.4 Whereas the wiring between boards is usually flexible and does not have to be specifically located in the design, connections on a printed circuit board do. For that reason, the specific placement of components on the board and how they will be connected has to be carefully planned out. Once a schematic of the circuit has been worked out, an artwork drawing is done for use in etching the copper board. Keep in mind that the board has two sides and components and the copper connections can be made on both sides. From the artwork drawing, fabrication, silkscreen, and assembly drawings are all made for different stages of manufacture. Specialized CAD software is used both as a drawing tool and as an 'expert system' to help plan the component placement and wiring connections. |
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SUMMARY |
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Electronics drafting is a specialized area of engineering drawing, using its own set of rules, standards, and symbols. There are also several types of electronic drawings, such as block diagrams, schematics, printed circuit board drawings, etc. In all cases, it is necessary to understand the order or pattern of the components and their functions before the drawing can be done. Minimizing or eliminating connecting-line crossovers and doglegs helps make the final drawings easier to understand and use. Virtually all circuit boards made today are designed with CAD software. For relatively simple boards, a standard software package is sufficient. For more complex boards, a specialized electronics drafting software package should be used. Hand layout is only recommended for very simple boards. |