Richard, I concur with Brian. Have seen similar situations arise with high temp co-fired ceramic packages (although greater gold thickness and higher temps). Auger analysis indicated nickel on the surface of the gold. Had the bake been performed in a good nitrogen environment (or stored in a nitrogen glovebox), the nickel may have diffused to the surface, but ideally not oxidized. Could you have used a slightly more activated flux? Steve At 11:07 AM 6/21/00 +0300, you wrote: >Richard > >As the gold is somewhat porous, I'd guess that the underlying Ni has oxidised during 1 >week at 45 deg C (why????). > >Brian > >Richard Tilbrook wrote: > >> NEW MESSAGE: >> >> Hi folks, >> Sorry, I wasn't feeling well yesterday and did not explan myself at all - the >> reason I asked about baking is that we reflowed one side of a surface mount board >> (gold on nickel); we then stored it in a 45'C oven as we were expecting the >> remaining parts to arrive for this very urgent job. They unexpectedly took a week. >> They even more unexpectedly didn't want to reflow properly when we tried reflowing. >> I suggested "passivation" as something for the person who brought me the problem to >> think about, though I must confess that being an industrial placement student, I am >> not best equiped to make that kind of judgement. As I try to follow many of your TN >> discussions, and occasionally add when I feel able, I was sure you'd be able to >> give better reasons as to the cause and suggestions for either prevention or cure. >> >> Thanks and Regards, >> >> Richard Tilbrook >> >> PREVIOUS MESSAGE: >> >> Hi technetters, >> I'm hoping to find out a bit more about the effect of baking (at 45 deg. C) on >> boards with gold on nickel. >> I would be grateful for any info on the sibject, including times, temperatures and >> effects, such as passivation. >> >> Thanks, >> >> Richard TIlbrook >> >> ############################################################## >> 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 Keach Sasamori at [log in to unmask] or >> 847-509-9700 ext.5315 >> ############################################################## > >############################################################## >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 Keach Sasamori at [log in to unmask] or >847-509-9700 ext.5315 >############################################################## > > ############################################################## 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 Keach Sasamori at [log in to unmask] or 847-509-9700 ext.5315 ##############################################################