Inge is absolutely right. Unfortunately,  in the majority of
so-called "solderability" cases, people try to tweak the process and
not get to the root cause fo the problem. SEM/EDS is indefensible to
do it.

-- 
Best regards,

Vladimir                          mailto:[log in to unmask]

SENTEC
11 Canadian Road, Unit 7.
Scarborough, ON M1R 5G1
Tel: (416) 899-1882
Fax: (905) 882-8812
Hi Graham,


steam test does not tell you much about underlying platings. Namely, if you 
are using ceramic PGAs, the pins are nickel plated Kovar with some gold 
upon. I have seen something like yours a number of time. It has to do with 
bad pretreatment before nickel plating, or bad nickel plating, which is not 
uncommon these days. Even plastic PGAs can have bad underplate. My advice: 
have a look at some cross sections in SEM/EDAX. Start with a glass fiber 
brush (kind of eraser) stroke. If the nickel is anomalous, you'll see it in 
a ordinary stereo microscope. If you are used to etching, a number of dips 
in  a not to concentrated HCl/H2SO4/H2O (strip gold at first of course) will 
probably reveal a lot even before SEM. I have some pictures on this, if I 
can find them, I'll send a pidgeon.
Ingewww.sentec.ca

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