Hello TN, I'm wondering how certain one can be about the root cause of delam. simply by reading its signature. Our experience is similar to Paul Reid's (post attached below). One obvious question: what about when it is both co and adhesive failure? Are there other features to the signature that are important in determining primary root cause? Chris ------------------------------------------------------------------------------------------ My sense is that moisture induced delamination presents as adhesive delamination that is horizontal cracks that resemble blisters and are located at a laminated interface (b-stage to c-stage or copper, or along bundles of glass). It may be that the vapor pressure exerted by trapped moisture induces a mechanical failure at laminated interfaces. Material degradation induced delamination more often presents as cohesive failure that may exhibit cracks with vertical sections, often bifurcating and spanning across b-stage and c-stage material, even through glass bundles, and tend to propagate with sharper angles. This failure mode appears to be more a chemical degradation of the epoxy system. Sincerely, Paul Reid --------------------------------------------------- Technet Mail List provided as a service by IPC using LISTSERV 15.0 To unsubscribe, send a message to [log in to unmask] with following text in the BODY (NOT the subject field): SIGNOFF Technet To temporarily halt or (re-start) delivery of Technet send e-mail to [log in to unmask]: SET Technet NOMAIL or (MAIL) To receive ONE mailing per day of all the posts: send e-mail to [log in to unmask]: SET Technet Digest Search the archives of previous posts at: http://listserv.ipc.org/archives Please visit IPC web site http://www.ipc.org/contentpage.asp?Pageid=4.3.16 for additional information, or contact Keach Sasamori at [log in to unmask] or 847-615-7100 ext.2815 -----------------------------------------------------