The Hitchhiker's Guide to PCB Design

The Hitchhiker's Guide to PCB Design

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79 C AD/CAM data has taken over the world of electronics. Since design and manufacturing is driven by data, much of what is accomplished on the PCB fabrication PCBA manufacturing floors has been standardized. Gone are the days of tape and mylar layouts in which designers served as artists, manually creating large-scale PCB artwork which would have to be photographically reduced to be used as a "photo-tool" to define the image of the etched copper PCB layer. And gone are the days of drill master artwork which would be used to manually "bomb-site" and program a PCB drill tape. However, the electronic manufacturing service provider's challenge has not only been to create the machinery and processing to manufacture new PCBs and PCBAs using data, but also to keep up with installing the new generation processors which are running at incredible speeds and require special considerations which cannot be defined using data alone. Along with the 'traditional' CAD/CAM data, there is still a need for textual information in the form of notes and special detailing to provide a complete engineering design package and help ensure a smooth manufacturing process "We love it when designers call us with new technology questions. Good designers will admit they don't know what they don't know – and they won't know until they ask. Fabricators need to know up front if an EE has special material requirements, especially if the EE has their mind on a specific dielectric or material to be used in the design, as availability buildup strategy is an issue here." You have spent a lot of time designing your board and getting it 'just right'. It is critical you provide your manufacturing partner the information they need to ensure they can build your board to meet your design intent. Without guidance from you, the designer, the fabricator will either be forced to make assumptions or delay manufacture while they seek to ask you questions they don't have the answers for. Let us look what composes a complete PCB data package and examine the notation and graphic documentation which must accompany it. File Naming Convention Avoid using non-descript or vague names like "TOP.GBR" for files. Without specificity a data file name will surely be confused as to its purpose. As shown in the examples above, incorporating a part number and revision into the file name links the file to a document control system. Adding a clear functional description to the filename will surely help anyone using he data to realize what is its purpose without having to view it. Part Number, revision, and function. Examples: • 424242_B_LAYER_1.PHO • 424242_B_DRILL.DRL • 424242_B_FABDWG.DXF Chapter 9 Fabrication Data & Documentation Pro-TipFrom Mark Thompson

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