Depends on the cross linking system used in the coating. Older types
using a acetic acid (acetoxy type) cure mechanism do pose some corrosive
risk.  Most manufacturers now also offer products based on Oxime cure
mechanism that do not pose this risk.   The later generally however have
longer tackfree times. 

This is a common issue that comes up with Si coatings. I think is
somewhat also based on silicone hand lotions causing solderability
issues.  As a results, any type of "silicone" products generally tends
to cause concern.


Rich Kraszewski / PLEXUS 


-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Mike Johnson
Sent: Thursday, May 28, 2009 2:38 PM
To: [log in to unmask]
Subject: [TN] Conformal coating process

We are a contract builder that manufactures printed circuit board
assemblies and apply a silicone conformal coating to those assemblies.
Our coating process is not isolated from the assembly and test area.  We
use a Sn63Pb37 solder process in both our smt and wave solder areas.
This has been our process for at least the last 15 years.  We are being
told, by a potential customer, that we are risking silicone
contamination of our solder joints as a result of our coating process
being in close proximity to assembly and test.  
What are the risks to solder joint quality, if any?  Thanks.  

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