additional comments on Vacrel 8140...

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  From: Joe Kotylo
  Subject:
 Subject: FAB, soldermask lamination

 The problems described are fairly common.  As Rick Day already
 noted these rings, also called craters and fisheyes, can be caused
 apply temps that are too high.  Other causes include insufficient
 freespace above the panel.  This condition causes sealing before
 the air is fully evacuated.  If the problem occurs on the bottom side
 of the panel in a two-sided application, it can be because the
 panel is heavy and has few PTH's which can cause precontact and
 poor air evacuation.  For these situations the panel should be
 placed on the film just before it's put in the vacuum chamber.

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  From the desk of Joseph A. Kotylo
                   EMI Soldermask/Surface Finish
                   Tieline 855-5803  Pager 58888-2810

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 Subject: FAB, soldermask lamination
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 Hello Technet,
 We have been experiencing problems with our soldermask lamination process.  We
 use Dupont's Vacrel 8140 dry film soldermask, and apply with an EH2400 vacuum
 laminator.  Upon removal from the laminator, we frequently see that rings have
 formed in the soldermask.  The rim of the ring is darker green, and the area
 confined by the ring is lighter green than the surrounding soldermask.  We
 have requested help/suggestions from mfg of both laminator and film, but as
 often happens, each says the problem is not with their product.
 Has anyone else experienced this problem while vacuum laminating dry film
 soldermask?  Any suggestions on how to eliminate this problem would be greatly
 appreciated.
 cbh

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ÿÿ

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