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Subject:	Re: chemical clean prior to soldermask
From:	[log in to unmask] (John E Nelson)
Date:	Fri, 9 Aug 1996 17:44:49 PST
Content-Type:	text/plain
Parts/Attachments:	text/plain (47 lines)

In a previous life I tested several chemical pre-cleans for Vacrel and 
never was able to achieve the same adhesion as with mechanical scrub.  

The best comparison is done using a scratch test.  (works for LPI too).
Take a  sharp knife and cut  a cross-hatch pattern  into the mask of\ver 
a ground plane  area.  The mask should not chip back from the cut 
more than a few thousandths.  The test is subjective so run samples
of each of several cleaning processes and scratch them similarly 
and compare the relative amount of chipping.   You'll readily decide 
which process is best.

On Fri, 9 Aug 1996 10:23:53 -0500 "Todd Rogers" <[log in to unmask]>
writes:
>We are attempting to switch our pre-clean process prior to soldermask 
>from
>chem-clean followed by a mechanical scrub to chem-clean only.  We have
>experienced problems with poor soldermask adhesion at the nickel/gold 
>tab
>area.  We are using a reverse current tin/lead strip prior to 
>nickel/gold
>and the HCL seems to be getting under the mask causing it to peel.  
>Has
>anyone else had experience with a chem-clean process prior to 
>soldermask
>and reverse current plate prior to nickel/gold.
>
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