I would suggest that you contact your board supplier and ask whether they
routinely measure SEC (ionic cleanliness) of their product at various
processing steps. If any significant Chloride residues were present on the
product, it would be detected using this method. It appears from the
original posting that, as a minimum, this test should performed prior to
solder mask application and at final inspection prior to shipment, in order
to ensure 'clean' product. Typically this test is also performed prior to
multilayer lamination and the test methods can be found in IPC-TM-650.

Dave Rooke
Circo Craft - Pointe Claire
>______________________________ Reply Separator
_________________________________
>
>          
>          Really????
>          No catalyst on the PTH line?
>          No alkaline etchant?
>          No reflow/HASL flux?
>          Need I go on?
>          
>          It may be that this is not their fault.  However, they have a VERY 
>          unique board shop if they don't use one or more of these
processes.  I 
>          suggest they could be more cooperative in helping to get to the root 
>          of the problem.
>          
>          Dave Sullivan
>          Rockwell Collins, Inc.
>          
>          [log in to unmask]
>
>______________________________ Reply Separator
_________________________________
>Subject: ASSEM: Copper Choride problem
>Author:  [log in to unmask] at ccmgw1
>Date:    1/8/97 8:02 AM
>
>
>     Hi, 
>     Recently we encountered some assembled PCB returned from the 
>     field where humidity is high and temp is low. Some vias and pads 
>     were found to be corroded with copper chloride after SEM analysis 
>     and when corrosion production were removed from the board, the 
>     affected part of the vias was degraded.  This has greatly 
>     affected the performance of the circuit.
>     The fabrication house claimed that they are not liable as there 
>     was not chloride
>     
>     chemical used in their processes.  
>     Does anyone has any insights to share?  Could the assembly 
>     process contribute to
>     
>     this corrosion?
>     
>     Thanks in advance for any information shared.
>     
>     
>     stella yap
>          

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