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