Thanks Steve, Looks like I may have the same problem, I have attached
pictures of my problem here. I am also forwarding this response to our
supplier to see if he will cooperate more and answer me to this point.
Sue



-----Original Message-----
From: Steve Gregory [mailto:[log in to unmask]] 
Sent: Monday, February 09, 2004 1:55 PM
To: [log in to unmask]
Subject: Re: [TN] Solder Mask Flaking


Hi Sue!

I had problems with solder mask a few weeks ago that I posted about. In
my case, I was seeing it after cleaning. Also in my case it wasn't
merely flaking, it was like a snake sheding its skin...mask was coming
off in huge slabs. I still have some pictures of it on my web page at:
http://www.stevezeva.homestead.com/

Look at the "Mask Peel" pictures there...it was ugly! What it turned out
to be was that the pumice scrub before mask application hadn't been done
on one panel hadn't been done, even though the production paperwork at
the fab vendor had been signed off that had been done. This was a dry
film solder mask over bare cooper by the way...

The problem only affected 2 boards because it was built in a 2-up panel.
For some reason, only one panel out of the lot that got built didn't get
scrubbed as it should have been. The boards passed our tape test at
incoming inspection too. It wasn't until the boards got thermally
shocked at wave solder, and then washed, did the poor adhesion because
of the bad surface prep show itself.

-Steve Gregory-



> I know this was up for a discussion a few weeks ago. Can anyone tell 
> me what the root cause was determined to be?
>
> I am experiencing solder mask flaking on a group of boards 
> manufactured by one certain supplier. It is a random occurrence for 
> example 10 out of the 100 boards we had this occurr. Then a different 
> board we ran 8 out of 40 were flaking same supplier as previous one.
>
> Supplier runs samples at his facility and he see's no flaking. We 
> changed our solder temperature from 500 degrees to 450 degrees at the 
> suppliers suggestion and flaking still occurs. He then states maybe 
> were not using enough flux but review shows plenty of flux if anything

> maybe were using to much flux from the way the boards look coming out 
> of the wave and washer.
>
> Thanks
> Sue Foulkes
> QA Manager
> AESCO Mfg.
>


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