Have had cases where soldermask has not adhered well enough to large ENIG surfaces and had it break loose and allow solder under soldermask...

Did tape peel test and all surfaces passed...

Like everything in this environment...It DEPENDS... on design, PCB manufacturing, material storage, materials used, processes used, local environment, climate change, ...., etc.

Paul  

Paul Edwards
Process/Quality Engineering
Surface Art Engineering


-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Matthew Park
Sent: Thursday, August 09, 2012 7:56 AM
To: [log in to unmask]
Subject: Re: [TN] SMOBC process

I used ENIG and electroplated gold as surface finishes before. Your concerns are unfounded. They are more friendlier for the board level manufacturing processes and they are better looking than HASL finish.


>>> Gerald Bogert <[log in to unmask]> 8/9/2012 8:57 AM >>>
August 9, 2012

 

Some of our OEMs manufacture PWBs using the HASL process and they use
solder mask over bare copper (SMOBC) to prevent re-melting of the
tin/lead from the traces during subsequent assembly level soldering
operations.  If SMOBC is not used, the re-melting of the solder causes
blisters under the solder mask coating which can result in peeling or
flaking of some of the solder mask from the traces.

 

We have one OEM who will be manufacturing an ENIG board with solder
mask.  My question is with this finish, will the gold melt during
assembly soldering to cause the same issue as when using HASL?  Also,
does anybody use SMOBC over ENIG?  My understanding that it can be done
but the results are not cosmetically appealing. 


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