> For .035 +.004 -.001 finished holes, we have a pad size of .050
> What pad size is required to meet annular ring requirements
> per MIL-P-55110 ???
>
The easy answer is 0.002 for a type 3 board. But it's really more
detailed than that. I use the following formula to determine the
minimum anular ring.
(Finished hole size +0.005)+(2X min.annular ring)+(a manufacturing
adder of 0.014)=minimum land diameter
So, for your example
0.035+0.005+0.004+.014=0.058 diameter pad minimum required.
I'd say your present pad is a bit undersized using standard
production processes.
Tom Hybiske
General Atronics Corp.
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