Teckies, need a little help hear!

I have recently experienced a problem whilst cleaning double sided FR4
dual technology multi-layer boards that had been wave soldered.
The boards (4 off) were put into a fully automatic batch cleaner end of
day shift which uses a Brominated solvent 'ENSOLV ionic' .and removed
the following morning first thing.
The cleaning m/c is a vapour degrease system which has a refrigerated
coil at the top of the bath, this provides a free board zone above the
vapour which forms part of the cycle (draining).  =20
The cycle time is usually 30 minutes.

The problem is that the boards appear to show weave / pre-preg
separation across all of the boards leaving the weave visible but not
through to the top layer.  Around thru' hole terminations the board has
clearly delaminated.

I performed 100% inspection on another one of the wave soldered batch
which appeared fine.  I repeated the cleaning exercise and the post
cleaning result was the same.  =20

Two things to note, firstly, when the board was removed after the
second=

cleaning operation the m/c had malfunctioned as the cooling coil had
not=

worked so the free board zone was hot with vapour.  What I cannot
guarantee is that this did not happen during the first cleaning
operation (4 off), I can't say I noticed the boards being hot but I
suppose the m/c could possibly have malfunctioned part of the time.
Secondly, these boards have been cleaned previously in the m/c but
during a shift and removed after the cycle.

Has anyone experienced this type of occurrence?

CIA,
      Iain.




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