Electronics Forum | Wed Aug 09 08:06:07 EDT 2006 | davef
See "IPC-4554 Specification for Immersion Tin Plating for Printed Circuit Boards" 3.2.1 Immersion Tin Thickness. The most common reason for solderability issues with the white tin surface coating during multiple thermal excursions is a thin white ti
Electronics Forum | Mon Feb 06 13:00:51 EST 2006 | amol_kane
Hi all, I just wave soldered 40 boards (20 if Imm Sn and 20 of Imm Ag) using SAC 305 (in this case the wave machine manufacturer (electrovert) suggested the alloy too). plan to carry out x-sectioning to see the results. overall, just from the visual
Electronics Forum | Fri Dec 16 08:16:41 EST 2005 | davef
Heat cycles deplete the pure tin layer. Each solder cycle reduces the tin thickness by ~0.1 micron (4 uin). So, if you start with a thin imm tin coating you'll have problems after multiple heat cycles. Steve Wentz says, "In almost every case I've
Electronics Forum | Mon Nov 25 15:55:32 EST 2002 | davef
Sorry, no tricks for you. The good news is: your reflow recipe should be similar for both imm tin and HASL. Imm tin requires more attention to detail by both the fabricator and the assembler than HASL. There is a fair amount of discussion on imm
Electronics Forum | Fri Jun 17 10:47:48 EDT 2005 | davef
Doug: We agree that imm tin can be easily stripped and reapplied. Do you order imm tin as bright/ dull? Is bright/dull a function of who the fabricator lisences the process? Er wha? Electroplate tin can be either matt or bright. It is different
Electronics Forum | Mon Jun 10 22:14:49 EDT 2002 | davef
While they're '50 pitch', you need to think of 0402 as fine pitch parts. So, ENIG, imm silver, and imm tin finishes and probably OSP would be good choices. Stay away from HASL.
Electronics Forum | Sat Dec 10 08:13:53 EST 2005 | davef
We believe imm tin suppliers say that their product does not whiskey, oops whisker, because they use 'white tin' not the 'gray tin' that causes whiskers. But as soon as you alloy their tin with SAC or any other high tin content solder, all bets are
Electronics Forum | Mon Dec 12 09:39:39 EST 2005 | Amol Kane
thank you devef....My point is this....If you solder all the areas that have Imm Sn on them, there wont be any whisker formation DUE TO THE IMM TIN COATING.....whiskers could still potentially form as a result of COMPONENT FINISHES and effective miti
Electronics Forum | Fri Jul 18 11:05:07 EDT 2003 | davef
A highly activated flux will begin to corrode the imm tin coating after 10 minutes. Corroded tin has poor solderability.
Electronics Forum | Fri Aug 08 08:00:46 EDT 2003 | davef
Matt: You're correct. Do not mess with these boards. If the immersion tin [imm tin] is discolored, it will not solder with routine processes. Ask your customer to return the boards to his / her fabricator and have the imm tin replated. The fabri
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