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The following is an excerpt from Chapter 2 of Mark Thompson's I-Connect007 eBook The Printed Circuit Designer’s Guide to... Producing the Perfect Data Package. Mark is in engineering support at Prototron Circuits and a Design007 Magazine columnist.
Contents of the PCB Output Package
This chapter will cover the five “must-haves” for an output package—drawings and README files, image data, NC Drill files, IPC netlists, and assembly array drawings—and conclude with a brief note on manufacturability data edits.
A. DRAWINGS AND README FILES
Since one of the first things a salesperson will do to create a quote is review your drawings and README files, let’s start with what should be included on a fabrication drawing. README files are typically simple text documents (Word or Notepad) that describe the files and provide information to be conveyed to the fabricator that may not be on the drawing, such as known netlist shorts or opens, specifics about controlled impedances, etc. Drawings are typically exported as a PDF, DXF, or Gerber image file.
Note: Any discrepancies or conflicts between drawings or files will require clarification between the salesperson and designer, which will delay the quote process. A frequent issue is inaccurate, confusing, or conflicting notes on drawings. A quick cursory look at all your output documents is advised to make sure you have no troublesome notes.
Drawings should include the following nine fabrication specifications at a minimum:
A1. Board outline with dimensions and tolerances
Many output packages come in with files that use different origins (i.e., not all files are aligned as they should be). This creates issues with layer-to-layer alignment, as well as X and Y board dimensional requirements and tolerances associated with those dimensions. It is always good practice to have a dimensioned hole as the X0Y0 origin. This allows the fabricator to align the NC Drill file with the image data. Ideally, the board outline should also exist on the image data. If an assembly array drawing is being provided for specific panelization needs, make sure there are no conflicts between the board outline in the image data and the array image data, such as showing chamfered corners on the image data but radii on the array drawing.
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