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From [log in to unmask] Wed Feb 5 09: |
41:22 1997 |
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Good Morning:
I would like to take a quick survey of designers/fab shops about thru
hole vias for comparison with our internal practices.
1) For a via DRILLED with a .0135" drill in a .062 MLB:
A) How is the hole defined?
B) What Pad sizes would you typically use/expect for Inners and
Outers?
2) What size via holes do you typically use/expect for .062 MLB?
Any comments like: I would be OK for my Gateway 2000, but not in the
Boeing 737 I fly on?
Based on my understand, I would answer the survey as follows:
1A) Define hole as .012 - .007. (if you care about a minimum size)
1B) From IPC-D-275 Class 3 Level B, (Para 5.3.2.1)
30 inner and 32 outer. ( a+2b+c = 12+2*1+16 = 30.. )
I think designs typically use smaller pads, hence the survey.
Thanks for your input!
--
George Franck Jr
Raytheon E-Systems
Falls Church Va.
"The opinions expressed are those of the author, and are not necessarily those of the Raytheon Corporation."
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