My interpretation of a 'Burp' cycle differs from a 'Kiss' cycle, in 
     that with a 'Burp' the lamination press is momentarily opened and then 
     closed prior to going to full pressure. Whereas with a 'Kiss', the 
     pressure is shifted from low to high after a predetermined dwell, 
     which remains our standard process even with vacuum assist.
     
     Dan Buxton       _____                                                
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______________________________ Reply Separator _________________________________
Subject: Re: Burp Cycle!
Author:  [log in to unmask] at INTERNET
Date:    10/16/95 5:03 PM


        I think it's more commonly coined a "bump" cycle. I've ran into 
     this when dealing with acrylic based adhesives such as flex circuitry. 
     When the press initially closes, this cycle would help eliminate any 
     air pockets trapped within the package. It's similar to "kiss" (or 
     double stage) lam cycles for thermoset resin systems. The initial low 
     pressure allowed the package to heat to melting temperatures before 
     applying high pressure stage. This helps with high layer count PCBs 
     that have very thin cores to manufacture them with. The thin cores
     can easily fracture and generally have very fine lines that can be 
     stressed when high pressure is directly applied. (Vacuum assist 
     lamination has virtually replaced all these various techniques)
     
     Hadco Printed Circuits
     Tech Center Two / Watsonville                
     
     
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     Dave Hoover              (408) 728-6677 
     Senior Process Engineer  (408) 728-1728 Fax 
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______________________________ Reply Separator _________________________________
Subject: Burp Cycle!
Author:  [log in to unmask] at SMTPLINK-HADCO 
Date:    10/16/95 4:15 PM
     
     
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