Why bother to use "near to" measurements for laminate I thought laminate measurements were all in English anyway? Or was that when I was a lot younger......8-) John Burke (408) 515 4992 -----Original Message----- From: TechNet [mailto:[log in to unmask]] On Behalf Of Genny Gibbard Sent: Tuesday, May 01, 2007 3:13 PM To: [log in to unmask] Subject: [TN] Laminate damage We are writing an internal laminate damage standard, based on the 600 and the 610, but specifically dealing with only the types of material we use and the class we build to, so it is easier to evaluate our products. I know the IPC standards need to be a bit general or broad in their descriptions because of the need to cover the whole industry, so we are just clarifying the specific areas that apply for our workplace. This includes things like simplifying some of the dimensions. 2.5mm is ~ equal to 0.1", rather than stating 0.0984" (...you know someone would spend 45 minutes trying to measure that...). The 600 seems bad for that - very literal dimension translations between units. 1.25mm has [.04921in] after it. My specific questions are regarding exposed fibres: 1. Exposed or disrupted fibres are acceptable according to the 600, if conductor spacing is not reduced below minimum requirements. However, only unbroken exposed fibres are acceptable in the 610. Why is there a looser spec allowed at the bare board stage than at the assembled board stage? If a bare board was passed based on the 600, it would always fail at assembly based on the 610. 2. Also, we have been told that exposed weave has a propensity for drawing moisture into a board. Just wondering, would this be any worse for broken fibres than for unbroken? 3. Finally, we have been discussing: why are disrupted and/or exposed fibres such a danger, when you could consider the same condition existing on every routed out or scored and cut board edge, or unplated drill hole? Thanks once again, Genny --------------------------------------------------- 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 ----------------------------------------------------- --------------------------------------------------- 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 -----------------------------------------------------