What is minimum space and trace?
The answer depends on the starting
copper weight.
This is because we must do an etch comp
on the traces in CAM to compensate for
known etch loss. The space between
traces after compensation will play a role
in whether a board can be manufactured.
The lower the spacing width, the higher
the cost. Designers don't always account
for the proper starting copper weight after
edge compensation.
For accurate starting copper weight, add a
half mil (.0005") to all copper features.
Start with 3/8 or 1/4 oz. foil, reducing
etch comp and less likely to cause a
spacing issue.
Boards that call for full body electrolytic
gold are not comped to avoid gold slivers
occurring during the etching process.
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Design tips:
DESIGN TIPS #124:
ETCH COMPENSATION
After etching
Before etching
During etching, trace
width expands beyond
the width of the resist.
TRACE
WIDTH
