I would just like to get a feel as to how the rest of the industry is currently
designing fine line PC boards.

My company produces military cockpit displays.

We route with .007 mil lines, and call for a .003 Max. processing allowance.
This would mean that the trace could etch down to .004 mils.

Is this a normal allowance? or is it being very generous?
Could I use .006 mil traces with a .002 mil processing allowance?
Would this method make the boards cost more?
Are there any other military contractors out there using simular numbers?


We've had our share of mis-etched boards. If we would be better off reducing
our trace widths to .006 mils and expect the fab shops to hold to a .002 mil
etch allowance, then we could expect to see fewer scraped boards and higher
yields for the fab shops.

Also we route using .004 mils clearence. A slightly smaller trace would also
help increase producibility.