Our principle product uses a 14"x17", .125 thick, 8 layer backplane with 48
press fit connectors. Its currently specified as SM over reflow solder. Our
PCB supplier has performed wonderfully in the past, but we are now receiving
some boards with out of spec finished holes (spec .033 +.002/-.003). Cross
sectioning shows the problem to be extra, irregular solder buildup in the
holes. They are suggesting we should spec SMOBC to help the problem. Another
new vendor we are talking with is recommending a Ni/Au process. My feeling
is the original vendor produced very satisfactory product for 3 yrs, and
should be able to continue to do so. However, I'd like to take this
opportunity to do some investigation. I have a few questions:

1. Is anyone out there using Ni/Au on boards with press-fit connectors?
2. Would anyone venture an opinion on impedance differences that would exist
between the three processes? 
3. Does our current spec seem unreasonable or difficult to manufacture? 
4. What about if the hole was specified as .033 +/- .002?

Thanks!
Michael Branning
Avtec, Inc.
4335 Augusta Hwy
Gilbert, SC 29054
(803) 892-2181
(803) 892-3715 FAX
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