Did . Yo're quite right, apart from the cost, it did not beat simple flash as well (say 15umNi, 0.5umAu), on IPC-SM-785. To this day i still owe Dave the report summary (some 7 months of cycling) Did not see any improvement from (challenging) NiAu solderability/wetability . Still, keeping all smt corners and pth top pads wet, never seen the black plague (must be doing something right)on floor . Few outside . But I have good fab fellows on bare cards, all in tight limits and fresh, (reminds me, where's Earl ?). As far as IMT's, the latest trends [LF]of exotics like NiPdAu soldered with Ag alloys (NEMI)do puzzle me . Tough joints , just the plasticity seems to be "bit" dry . Well, Anatech just recalibrated my deep cycle toy, back to cracking caps . cu jk pk -----Original Message----- From: joyce [mailto:[log in to unmask]] Sent: Friday, 10 December 1999 10:02 To: [log in to unmask] Subject: Re: [TN] Ni/Pd/Au Does anyone did reliability test of the joint form with Ni/Pd/Au? If my memory serve me right, Pd and solder do form intermetallics relatively fast. jk At 02:33 PM 12/9/99 -0700, you wrote: >Larry, > > You are absolutely correct. However, in order for solder to make >contact with Ni, it must first dissolve the Pd. > > Several SMT solderability tests have used the technique of depositing >solder and measuring how far it spreads during reflow. How far solder >will spread is a function of the surface energy interface of the liquid, >solid and gas, and the wetting angle. By increasing the surface energy >of the solid, the liquid can more easily wet that surface. Without >referencing a chart, I would guess that the energy interface of liquid >Tin is better for Gold than Palladium because Gold dissolves into Tin >faster. Improving the solderability of Palladium by using flash gold >was suggested by Elizabeth Benedetto in her article in SMT Feb 99 titled >"Evaluation of Palladium Lead Plating". > > Dave Hillman did do solderability testing and wire bonding on Ni/Pd/Au >and found that surface finish has very good wire bondability. (Published >in SMI '96) It is also corroborated by an NCMS consortium published in >SMI '96. And ITRI reported the same results in IPC expo 97. > > From the looks of the above stated articles, I guess I'm wrong about >the Au being used to improve solderability. It sounds like the gold is >for wirebonding. > >Ryan Grant > >>-----Original Message----- >>From: Larry Tawyea [SMTP:[log in to unmask]] >>Sent: Thursday, December 09, 1999 11:16 AM >>To: [log in to unmask] >>Subject: Re: [TN] Ni/Pd/Au >> >>In a message dated 12/8/99 4:02:17 PM Central Standard Time, >>[log in to unmask] writes: >> >><< >> The gold is an attempt to improve the solderability of the >>palladium. >> >>Ryan, >> >>Unless I am totally missing something from your response, the issue is not >>how long the solder is in contact with the Au or Pd but how long is the NI in >>contact with the solder. I'm not trying to take issue with your response, >>but I think the issue is what is the solderability of the Ni and how good of >>a solder joint have you made to the NI. >> >>Larry Tawyea >> >>############################################################## >>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 ##############################################################