This type cylcle is often referred as a "bump" cycle.  Several of the 
     presses manufactured for multilayer lamination are capable of this 
     process.  A bump cycle consists of a rapid reduction of pressure from 
     the lamination pressure to ambient and back again.  This occurrs 
     during the flowable period of the bonding sheet.  Any retained 
     moisture or entrapped gases will volitalize and be expelled by the 
     rapid change in differential pressure.
     
     An article was published by Vince Noto of Tetrahedron in "PC 
     Fabrication" in February 1986 discussing this type process.
     
     If you would like a copy of the article, send me your fax number.
     
     Hal Brown
     Zycon Corporation
     
     [log in to unmask]


______________________________ Reply Separator _________________________________
Subject: Burp Cycle!
Author:  [log in to unmask] at corp
Date:    10/16/95 11:28 AM


I recently heard reference to a lamination press cycle for multilayer PCB's 
as a burp cycle.  This cycle is intended to help with air entrapment I believe.
     
If anybody has any specifics on this cycle and or results of if it works or 
not I would appreciate any and all feedback.
     
Thanx in advance.
     
brian