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Date: | Mon, 16 Oct 95 17:03:10 EST |
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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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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
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