Rick, "Thanks for letting me know I was wrong. I think the mistake was a good one for me because look at all the information I have gotten. So let me say that I'm sorry for miss reading your mail. Then say thanks to all the netters for the very informative replies. May I say that I talk about the technet to others here and how if I need information I know where I can get it. We are the lucky ones. Well I don't what any netters head to exploded. I'm sure I well need to pick their mines later. Have a Great Day and I hope you got your answer. I'm sure I've upset some with my apology. So before you get started I'm going to say S O R R Y Nancy T. >>> "Howieson, Rick" <[log in to unmask]> 02/02/00 01:35PM >>> Nancy, Sorry I was not clear. Measling prior to assembly (bare board). Rick >-----Original Message----- >From: Nancy Trumbull [SMTP:[log in to unmask]] >Sent: Wednesday, February 02, 2000 7:41 AM >To: [log in to unmask] >Subject: Re: [TN] Measling > >Hi Again, > I wish to be enlightened. My understanding of the original problem was >measling during hand soldering process. Sorry if I read it wrong and took >off on soldering process. > >All that I have been reading sounds right and about the same. >Therefore I agree with just about everyone. >But now All of you have me wondering. >So here it is another statement and question from me. >Statement: >From past experience MY understanding of PROCESS MEASLING CAN FROM reflow >soldering, hand soldering or any type of thermal induce process. > >My understanding has always been that measling as an inherent or assembly >condition is acceptable. > >QUESTION: >How done assembly process measling occur. > >Oh by the way I want to thank all of you for putting up with me and to let >you know that I have been a technetter for one year and my knowledge has >grown greatly. >I do off and on put in my two cents and love it went you give me back a dime. > Waiting to hear from any and all. >Have a great day >Nancy T. > >>>> Brian Ellis <[log in to unmask]> 02/02/00 06:58AM >>> >Kelly, > >I'm 100% with you on this. Measling is due essentially to too little resin at >the fibre >"bumps", because either it was squeezed out too much during pressing or there >has been >a chemical attack of the resin, baring the fibres. The real problem with real >measles >is that chemicals can enter the fibre structure by capillary action, after >which >anything can (and does) happen. Overheating pads is not a cause for measles >but, sure >as God made little green apples, it can cause one helluva lot of other >problems. This >is why we put thermal breaks in ground and power planes, just to reduce this >risk. > >Brian > >"Kelly M. Schriver" wrote: > >> Whoops!! Help me with this one, guys!! Measling, by definition, occurs >> only at the intersection of two fiber bundles within the lamina. >> Accordingly, it cannot occur in the same plane as the metal foil of that >> laminate layer. The size of a measle is self limiting by the structure of >> the glass (or fiber) bundles. Further, one measle cannot join with an >> adjacent measle or become a running fault in the laminate. >> >> Crazing and delamination, however, can occur in the same plane as the metal >> foil, and can become large running or bridging faults. I've seen numerous >> cases of crazing which were misdiagnosed as measling. >> >> Many of the publications, such as WS6536, MIL-STD-2000 and others failed to >> recognize this charactaristic about measles vs other internal laminate >> faults, leading to a few misconceptions. I have seen no indication of test >> data, other than some specialized high power applications which suggests >> that real bona fide measles are a reliability problem. >> >> Regards - Kelly >> >> -----Original Message----- >> From: rampinc <[log in to unmask]> >> To: [log in to unmask] <[log in to unmask]> >> Date: Tuesday, February 01, 2000 6:39 PM >> Subject: Re: [TN] Measling >> >> >Rick, >> > >> >Be careful. Measling can be a source of reliability problem when it >>bridges >> two >> >conductors. Measling becomes 'A' type defect ( Critical function -causing >> rejection) >> >when two conductors of different polarity are bridges. If glass fibers >> become visible >> >in a measled spot, that is also a cause for concern. >> > >> >Send pictures of measled board for further discussion if you like. >> > >> >"Howieson, Rick" wrote: >> > >> >> IPC states measling is not cause for rejection. Anyone out there know >> >> where I can get supporting data that documents testing performed to come >> >> to this conclusion? All help is appreciated. >> >> >> >> Rick Howieson >> >> http://www.gt-corp.com >> >> >> >> ############################################################## >> >> TechNet Mail List provided as a free service by IPC using LISTSERV 1.8c >> >> ############################################################## >> >> To subscribe/unsubscribe, send a message to [log in to unmask] with >> following text in >> >> the body: >> >> To subscribe: SUBSCRIBE TECHNET <your full name> >> >> To unsubscribe: SIGNOFF TECHNET >> >> ############################################################## >> >> Please visit IPC web site (http://www.ipc.org/html/forum.htm) for >> additional >> >> information. >> >> If you need assistance - contact Gayatri Sardeshpande at [log in to unmask] >> or >> >> 847-509-9700 ext.5365 >> >> ############################################################## >> > >> >-- >> >____________________________________ >> >Regards, >> >Pratap Singh >> > >> >Tel./Fax: 512-255-6820, >> >e-mail: [log in to unmask] or [log in to unmask] >> > >> >############################################################## >> >TechNet Mail List provided as a free service by IPC using LISTSERV 1.8c >> >############################################################## >> >To subscribe/unsubscribe, send a message to [log in to unmask] with >>following >> text in >> >the body: >> >To subscribe: SUBSCRIBE TECHNET <your full name> >> >To unsubscribe: SIGNOFF TECHNET >> >############################################################## >> >Please visit IPC web site (http://www.ipc.org/html/forum.htm) for >> additional >> >information. >> >If you need assistance - contact Gayatri Sardeshpande at [log in to unmask] or >> >847-509-9700 ext.5365 >> >############################################################## >> >> ############################################################## >> TechNet Mail List provided as a free service by IPC using LISTSERV 1.8c >> ############################################################## >> To subscribe/unsubscribe, send a message to [log in to unmask] with following >>text in >> the body: >> To subscribe: SUBSCRIBE TECHNET <your full name> >> To unsubscribe: SIGNOFF TECHNET >> ############################################################## >> Please visit IPC web site (http://www.ipc.org/html/forum.htm) for >>additional >> information. >> If you need assistance - contact Gayatri Sardeshpande at [log in to unmask] or >> 847-509-9700 ext.5365 >> ############################################################## > >############################################################## >TechNet Mail List provided as a free service by IPC using LISTSERV 1.8c >############################################################## >To subscribe/unsubscribe, send a message to [log in to unmask] with following >text in >the body: >To subscribe: SUBSCRIBE TECHNET <your full name> >To unsubscribe: SIGNOFF TECHNET >############################################################## >Please visit IPC web site (http://www.ipc.org/html/forum.htm) for additional >information. >If you need assistance - contact Gayatri Sardeshpande at [log in to unmask] or >847-509-9700 ext.5365 >############################################################## > >############################################################## >TechNet Mail List provided as a free service by IPC using LISTSERV 1.8c >############################################################## >To subscribe/unsubscribe, send a message to [log in to unmask] with following >text in >the body: >To subscribe: SUBSCRIBE TECHNET <your full name> >To unsubscribe: SIGNOFF TECHNET >############################################################## >Please visit IPC web site (http://www.ipc.org/html/forum.htm) for additional >information. >If you need assistance - contact Gayatri Sardeshpande at [log in to unmask] or >847-509-9700 ext.5365 >############################################################## ############################################################## TechNet Mail List provided as a free service by IPC using LISTSERV 1.8c ############################################################## To subscribe/unsubscribe, send a message to [log in to unmask] with following text in the body: To subscribe: SUBSCRIBE TECHNET <your full name> To unsubscribe: SIGNOFF TECHNET ############################################################## Please visit IPC web site (http://www.ipc.org/html/forum.htm) for additional information. If you need assistance - contact Gayatri Sardeshpande at [log in to unmask] or 847-509-9700 ext.5365 ############################################################## ############################################################## TechNet Mail List provided as a free service by IPC using LISTSERV 1.8c ############################################################## To subscribe/unsubscribe, send a message to [log in to unmask] with following text in the body: To subscribe: SUBSCRIBE TECHNET <your full name> To unsubscribe: SIGNOFF TECHNET ############################################################## Please visit IPC web site (http://www.ipc.org/html/forum.htm) for additional information. If you need assistance - contact Gayatri Sardeshpande at [log in to unmask] or 847-509-9700 ext.5365 ##############################################################