This AutoCAD Tutorial will explain how to set up layers in AutoCAD for the electronic industry.
While designing in AutoCAD, the drafting schematics, design PCB artwork, detailed fabrication list and assembly drawings are all drawn on different layers.
Here is an explanation of layers that are typically created for an Electronic PCB design:
1. The silkscreen on the top side of the PCB
The silkscreen contains component outlines and legends etched with white ink on the top side of the PCB. The manufacturing of PCBs needs a legend silkscreen containing the reference designators (components).
2. The circuit traces on the solder side of the PCB
Electronic schematics consisting of symbols that represent the individual electronic parts that are needed to create an AutoCAD drawing. These electronic symbols are interconnected with lines that represent the actual electrical connections and are annotated with text containing the specifications of the components used. The basic schematic symbols are standardized and also available as a library for use in AutoCAD which simplifies the process of generating schematics.
3. The pads for through hole components.
Libraries of endpoint symbols are available which, with various hole types and sizes, need to be incorporated into the drawing.
4. Any special solder mark patterns on the components side of the PCB.
The reference designators are used to determine the location of components on the PCB, and used during manufacturing, as well as troubleshooting the PCB at a late time.
5. Drill symbols and attributes associated with the pads of thro hole components.
The drill attributes in the drawings give the drilling details used by automatic machines for drilling holes.
6. Drawing border, title & other details used in documentation required for manufacturing.
A detailed list of components required for manufacturing the PCBs can be extracted from the AutoCAD drawing. Once the layout is complete the AutoCAD drawing is converted to Gerber and Excellon file formats which is industry standard for photo plotting PCB artwork. These file formats are required for manufacturing PCB's when using third party add-on software.