Hi all,
I saw something like this before but not quite this bad. The PWB board
vendor was using a UV initiated thermo set LPI solder mask and was skipping
the UV part of the cure. A little temp cycling and add some humidity and
similar results, lifted mask and exposed metal. We discovered the UV part
during a facility audit. Perhaps a check of SM material, SM vendor process
and what the PWB vendor is actually doing.

John Maxwell

At 10:50 AM 5/21/01 -0500, you wrote:
>Hi Steve! Did any of the other 15 assemblies exhibit this "eaten"
>appearance? Condensation (on its own/by itself)  in a thermal cycle chamber
>will not cause the attack you have experienced. Condensation with flux
>residue or fabrication residues can cause the condition on that assembly.
>Could someone have done some hand soldering but forgot to clean?
>
>Dave Hillman
>Rockwell Collins
>[log in to unmask]
>
>
>
>
>"Stephen R. Gregory" <[log in to unmask]>@IPC.ORG> on 05/21/2001 10:22:32 AM
>
>Please respond to "TechNet E-Mail Forum." <[log in to unmask]>; Please respond
>       to [log in to unmask]
>
>Sent by:  TechNet <[log in to unmask]>
>
>
>To:   [log in to unmask]
>cc:
>
>Subject:  [TN] Assembly "ate-up" after temp cycling...
>
>
>Hi ya'll!
>
>Well, I survived all the tornados we had yesterday...almost a dozen of them
>all around my area!
>
>Came in this morning and one of the supervisors showed me a board that came
>out of a temp cycling oven after being in there for 32-hours...the temp
>cycles are from 0-70 degrees C., 14 cycles over 32-hours. There were around
>15 other boards in the oven,
>but one came out looking like there was acid spilled on the backside, mask
>was off all over the back, solder joints had been eaten away, as well as
>pads!! It was the only board that had this...go to:
>http://stevezeva.homestead.com/index.html
>
>I've been asked what may have caused this...it looks to me like there may
>have been some flux left on the board. Some say that it may have happened
>from condensation that may have occured during the temp cycle, I say if
>that
>was the case, all the boards would like this. Something else had to be
>involved for the copper and solder to be eaten away like this...what do you
>guys think?
>
>-Steve Gregory-
>
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