Goodmorning Michael,
     
     I might suggest that u do look at replacement of T/L reflow process, 
     all  good suppliers  are aware of the impact of lead on/in the invir. 
     and are replaceing as quickly as possible.
     
     The Spec u are dealing with at present is nothing out of the norm, as 
     a supplier of BP's to all segments of the industry, we are confronted 
     daily with this question.
     
     The Ni/Au process u refer to is  somewhat normal in applications where 
     no or very few wiping motions are involved (insertion/withdrawel).
     
     Impedance is normally result of board stack up / design layout (u did 
     not mention what your requirement is).
     
     We would like to work with you and resovle your current concerns.
     
     Ron Frye Hadco Value Added Mfg. Div.
     14693 Hwy 17
     Lavonia, Ga 30553
     706 356-3304 office
     706 356-3331 fax
     [log in to unmask]


______________________________ Reply Separator _________________________________
Subject: FAB:Electroless Ni/Immersion Au & press-fit connectors
Author:  [log in to unmask] at SMTPLINK-HADCO
Date:    11/21/96 7:20 PM


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
[log in to unmask]
     
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