Al is an expected component of FR-4 since E-glass is about 15% Al2O3. Timothy Reeves ECD Circuit Board Division 13626 South Freeman Road Mulino, OR 97042 [log in to unmask] (503) 829-9108 (800) 228-8198 FAX (503) 829-5482 > ---------- > From: McFaddin, Wade > Sent: Friday, February 4, 2000 6:01 AM > Subject: Re: electrical shorts in RCC (resin coated copper) build up > layer > > Hi Thomas, > > I can't comment on you root problem with the resin coated copper shorts, > but > > I did have a quick thought on the SEM/EDX results you mentioned. The > bromine > signal (peak) is most likely coming from the flame retardants used in the > laminate. > The aluminum signal (peak) that you are seeing is also coming from the > bromine. > Bromine and aluminum signals overlap at 1.48keV on the EDX spectrum and > cannot be separated. However, bromine has additional lines (peaks) at 11.9 > keV > that can be identified. So if bromine is present there is no easy way to > determine > if aluminum is present by EDX. You would need to use another analytical > technique > such as WDX, but that's another story. > > Hope this helps, > Wade McFaddin > NEXTEK Inc. > > > -----Original Message----- > > From: Thomi [SMTP:[log in to unmask]] > > Sent: Thursday, February 03, 2000 7:46 PM > > To: [log in to unmask] > > Subject: [TN] electrical shorts in RCC (resin coated copper) build > up > > layer > > > > Dear Technetters, > > > > has anyone come across a root cause for electric shorts between > > neighboring copper lines of different potential within a layer laminated > > with RCC (resin coated copper)? We have carefully ground away layers 1+2 > > from one side, and layer 4 from the other, to find a (ca.) 1 micrometer > > diameter filament connecting two neighboring lines in layer 3. Cross > > sectioning this further, we could analyse this filament by using SEM/EDX > > and found copper. The surrounding resin shows peaks of Bromium (probably > > from flame retardants) and Aluminum (??Al2O3 filler material??). The > > electric short was not detected during bare board testing, but occured > > within one week of functional testing of the full assembly in an > > environmental chamber operating at 120°C (I wouldn't believe it!). > > > > Is there a certain resin condition under which copper migration is > > enhanced within the RCC-resin (however close to the interface with the > > core to which the RCC is laminated)? There is a recommendation to ensure > > driving/baking out humidity from the multilayer, which makes me somewhat > > suspicious, but I don't know enough about the constituents (resin, > > hardener, flame retardant, maybe filler material) to try and explain > what > > happens electrochemically. > > > > Best regards, > > > > Thomas Ahrens, Memellandstr. 8, D-24598 Boostedt > > Tel. ++(49) (0) 4393 97769 e-mail [log in to unmask] > > <mailto:[log in to unmask]> > > Bitte beachten - please note: > > - Mails groesser als 2 MB werden nicht angenommen > > - messages larger than 2 MB will not be downloaded > ############################################################## 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 ##############################################################