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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