Paul, I don't think you message was too long either ... it was well worth the read. Richard, While I'd like a time/temp rating on a PCB, practically I think we will have to settle for an empirical go/no-go type of coupon. The problem is that the laminates, prepregs, and coppers can combine into too many different "things"; different thicknesses, different area, different expansion even along the same board. We have boards that call for the same material and those boards are extremely different in what they will see when we assembly them - one for instance is all digital while the other is loaded with electro-mechanical devices that just suck up heat ... I agree that delamination will be a big problem to deal with - we are seeing the same things that you describe. We also have seen a material make through assembly one time, but not the second build ... if we establish that a material is "capable" of a time/temperature then that would seem to imply that the material will continue to be capable at that time/temperature however, the reality is that isn't necessarily so. Which would then seem to mean that every PCB would need to be tested (batch by batch) for it's time/temp rating (and we have not as yet established a test to do that), which would then mean that the time/temp rating is a variable by board not by material. Whereas I think for components, every component of that "type" has the same rating so long as the same compounds are used... I don' think that is going to work for PCBs... Valerie "Stadem, Richard" <[log in to unmask]> Sent by: TechNet <[log in to unmask]> 12/13/2005 08:01 AM Please respond to TechNet E-Mail Forum <[log in to unmask]>; Please respond to "Stadem, Richard" <[log in to unmask]> To [log in to unmask] cc Subject Re: [TN] Qualification of the Pb-free capable manufacturers Paul, This is not too long of a message at all. This is an excellent message. I worked in the industry as a consulting engineer prior to coming to work at GD. Many of my clients are currently reporting that PWB delamination is a major problem for them as they go to higher temps to accomodate Pb-free BGAs and flipchips. Repeatedly, the pwb materials are rated for Pb-free processing, and the Tg and Td ratings are purportedly good enough to withstand the higher temps, but the boards delaminate, even after baking to remove moisture. They are delaminating at temperatures as low as 230 C, and that is the chamber temperature, not the board. I brought this up in several postings to the Technet forum last month. There has been much discussion about it. There needs to be a time/temperature rating on pwbs for resistance to delamination, just like there is a moisture classification on components. The other properties of the materials are meaningless if they pop in the reflow oven or during hot-gas rework. --------------------------------------------------- Technet Mail List provided as a service by IPC using LISTSERV 1.8e 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 -----------------------------------------------------