Why does baking the board reduce the reliability and life expectancy of the board? > -----Original Message----- > From: Alain Savard [SMTP:[log in to unmask]] > Sent: Tuesday, October 26, 1999 8:51 AM > To: [log in to unmask] > Subject: Re: [TN] HELP!!! - flow solder problems RT > > Hi Richard, > > Now you know why some assemblers request test coupons. > For the age of the boards, you might have a DATE CODE on > the board. It's usually 4 digits, 2 of them are the week number > and the other 2 are the fabrication year. (example: 99-12 or > 12-99 represent the 12th week of 1999). > > Boards older then 6 months may start to have a substantial > amount of water absorbed into the laminate. They may also > have a fair amount of oxidised tin forming on the surface of > traces and inside the PTH. > > Do NOT bake the boards unless necessary, it slightly reduces > the reliability and life expectancy of the board. > > You might have to sacrifice a board to microsection it and see > any problems with the internal structure (mostly the plating). > > If you are scrapping any boards, use the area affected. > > If the failures are always at the same component, the batch of > components may need to be looked at for solderability. > > Finally check the wave and preheat temperature. (You could do > this first actually). > > Good luck, > > Alain Savard, B.Sc. > Chemical Process Analyst > CAE Electronics Ltd. > e-mail: [log in to unmask] > > -----Original Message----- > > Hello Richard, > > HELLO ALAIN > > A few things to look at: > - Did you perform a solderability test on the test coupons? > NO COUPONS WERE SUPPLIED. > > - How old are these boards? > NOT ENTIRELY SURE - WE GET THEM FROM AN EXTERNAL SUPPLIER. > > - Did you verify plating thickness and voiding in the test coupons? > NO COUPONS SUPPLIED. > > - are your components pre-tinned? > NOT BY US. FITTED AS SUPPLIED. > > 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 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 ##############################################################