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Fri, 7 Mar 2008 09:13:00 +0000 |
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Hello Technetters,
There has been some comment on this forum recently implying that cleaning or
final rinsing of assemblies with high purity DI water can have a detrimental
effect on solderability. We very occasionally see a solderability issue when
processing second side surface mount after first side population and
cleaning. Because of product build times and the use of paste with an OA
flux that must be cleaned soon after soldering we have to wash the first
side before continuing with the second side.
The surface finish of the PCB concerned is ENIG. We have had various
analyses carried out on the surface finish but have never had any conclusive
evidence that the finish itself contributes to the problems seen.
Can one of the gurus please explain how high purity water could affect
solderability and, if there are any circumstances in which variation in ENIG
could be susceptible to degradation in solderability if cleaned this way.
Best rgds,
-----------------------------------------------------------------------
Peter Barton
Senior Process Engineer
ACW Technology Ltd
Dinas Isaf West
Tonypandy
Mid Glamorgan. CF40 1XX Wales
Tel: 01443 425275 (direct)
Fax: 023 8048 4882
International Tel : +44 1443 425200
International Fax : +44 23 8048 4882
Website/URL: www.acw.co.uk
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