What`s needed on a Fabrication Drawing

What`s needed on a Fabrication Drawing

19/08/2021 murdamon123 Comments Off

Importance of a Fabrication Drawing

A fabrication drawing is to let the manufacturer exactly what quality and specification requirements are needed to create the boards precisely as envisioned by the engineer. A fabrication drawing allows engineers to customize beyond the simple dimensions and layout of their board designs.

What Should a  Fabrication Drawing Contain

The main items included on a fabrication drawing are specifications and tolerances. Specifications include any information that is not readily available from the Gerber data. Tolerances are any requirements that could differ from the manufacturer’s standard tolerances or what is established as the minimum quality tolerances.  Most often, the typical tolerances are standard practice; so, if there are requirements that differ from the standard tolerances, it’s important to make sure it is noted during the quoting process (tighter tolerances may increase costs, as the manufacturer considers risk associated with lower yields).

Key Notes

Below are the key notes that should be on a fabrication drawing:

  • Dimensions
  • Special fabrication notes (cut-outs, unusual shapes, etc.)
  • View of board – Component or Solder Side
  • Layer stack-up
  • Board thickness and tolerance
  • Finish (including thickness for hard gold, soft gold, and gold fingers)
  • Solder mask requirements, colour, type
  • Hole chart with tolerances
  • Part number details with revision #
  • IPC class or other quality standards
  • Copper thickness & Plating
  • Tolerances of conductor widths
  • Material specifications and dielectric thicknesses
  • Detail blown up if needed
  • Markings on the board
  • Bow and twist tolerances
  • Silkscreen, colour, type, tolerances
  • Electrical test tolerances and standards to be used
  • Array requirements
  • Impedance requirements