1) we send samples to our chemistry supplier every 3 months to run the SERA 2) tight control of the chemistry on the line - actually not very difficult 3) after 5 years of running this I can look at the finish and tell with probably a 99.9% accuracy if it is acceptable 4) we also do solderability tests 5) 5 years of 0 field returns Regards, Steve Kelly -----Original Message----- From: TechNet [mailto:[log in to unmask]] On Behalf Of tony steinke Sent: Wednesday, June 19, 2002 6:12 PM To: [log in to unmask] Subject: Re: [TN] Immersion Tin Steve, If you do not prefer the SERA testing to measure/evaluate the amount of copper migration, what method/test are you doing to insure that you are giving your customer a good solderable surface. Please explain? Tony Steinke AIT-Atlanta Inc. ----- Original Message ----- From: "Steve Kelly" <[log in to unmask]> To: <[log in to unmask]> Sent: Wednesday, June 19, 2002 11:13 AM Subject: Re: [TN] Immersion Tin > SERA will not help you - it is only a tool to measure tin /copper > concentrations . We have been running immersion tin for 5 years with no > issues but only one thermal excursion is allowed. The tin forms a > copper/tin intermetallic after thermal. We even silkscreen before tin to > eliminate this bake cycle. Regards Steve > > -----Original Message----- > From: TechNet [mailto:[log in to unmask]] On Behalf Of Tempea, Ioan > Sent: Wednesday, June 19, 2002 12:07 PM > To: [log in to unmask] > Subject: Re: [TN] Immersion Tin > > Hi Tony, > > we experienced poor wave soldering after 2 reflows with immersion tin. > So, > please give me a few hints on SERA. Is it a test that the board house > will > do, or it has to be at our incoming? Does it imply additional charges? > Where > can I read more? > > Thanks, > Ioan > > > -----Original Message----- > > From: tony steinke [SMTP:[log in to unmask]] > > Sent: Wednesday, June 19, 2002 11:19 AM > > To: [log in to unmask] > > Subject: Re: [TN] Immersion Tin > > > > Grant, > > Having installed the Cookson(Dexter) FST chemistry a couple of years > > ago at my previous employer, there are concerns that you should be > aware > > of. > > The immersion tin > > process is a beautiful thing if applied and processed properly. Some > of > > the > > major > > issues that I experienced were: > > Solder mask adhesion(you should tape test any incoming product) > > Request that SERA(sequential electromigration reduction analysis) test > be > > performed. > > And the biggest problem was getting acceptable solderability on second > > pass > > wave solder > > or second pass solder paste. The copper migration greatly accelerates > > during > > any thermal > > excursion, but that is what the SERA testing will show you. > > Tony Steinke > > [log in to unmask] > > > > ----- Original Message ----- > > From: "Grant Emandien" <[log in to unmask]> > > To: <[log in to unmask]> > > Sent: Wednesday, June 19, 2002 3:06 AM > > Subject: [TN] Immersion Tin > > > > > > > Members, > > > > > > A PCB supplier has requested us to evaluate immersion tin as a > finish. > > > Immediate concerns raised were shelf life, solderability, whiskers, > etc. > > > Researching the archives has noted similar as well as opposing views > and > > > concerns. In addition to possible problems arising from immersion > tin > > > finish, what PCB fabricator process changes may contribute to > possible > > > reliability and solderability concerns and how this impacts > production > > > processes such as reflow. The proprietary chemistry used is MacStan > HSR > > from > > > Macdermid. > > > > > > Anyone willing to share experiences and guide me towards making an > > informed > > > decision. > > > > > > TIA > > > Grant > > > > > > > > > > ********************************************************************** > > > Notice: > > > > > > This email transmission contains confidential information which is > the > > property of the sender. The information is intended only for the use > of > > the > > addressee. If you are not the intended recipient, you are hereby > notified > > that any disclosure, copying or distribution of the contents of this > > e-mail > > transmission, or the taking of any action in reliance thereon or > pursuant > > thereto, is strictly prohibited. Should you have received this email > in > > error, please immediately notify us by telephone to arrange for return > of > > the documentation comprising this transmission. 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