Dave and all, From what I have seen, you are certainly correct that the plating process contributed to the growth of whiskers. What I do have concern for is the inability to accelerate the growth of whiskers beyond the environment that very closely parallels operation for electronics. Soo how do you test for whisker growth tendency beyond plating and waiting for four or five years to see if it grows whiskers. Standard cycling and temperature environments only contribute to delay whisker formation. I think that the jury is still out on slightly elevated humidity impact. There are some very high end tests that can compare surface tensions for compressive stresses which cause whisker formation but I doubt if the plating shops are doing that. I guess that I'm hoping that someone has a way to predict the tendency to grow whiskers beyond what I've seen so far. Our committees looking at this haven't found one yet. Any revelations would be appreciated. Mel Parrish Soldering Technology International 102 Tribble Drive Madison, AL 35758 256 705 5530 256 705 5538 Fax [log in to unmask] www.solderingtech.com -----Original Message----- From: TechNet [mailto:[log in to unmask]]On Behalf Of Dave Hillman Sent: Thursday, April 04, 2002 10:16 AM To: [log in to unmask] Subject: Re: [TN] Tin whiskers and immersion tin coatings Hi Bev! We have been using immersion tin surface finish for about 1 year and have had no issues with whisker growth. During our qualification testing the whisker issue was a very important test matrix question and we requested the all of the immersion tin suppliers furnish their tin whisker data. The immersion tin chemistry suppliers (well, at least one for certain!) appear to have successfully engineered chemistries which do not permit whisker growth. My recommendation would be to work closely with the pwb fabricator and/or the chemistry supplier to understand what they are doing to eliminate whisker growth. Now if you want to really get nervous just think about the component fabricators who are choosing to use matte tin as a component lead finish - let's hope they have done their homework/testing. Dave Hillman Rockwell Collins [log in to unmask] Bev Christian <[log in to unmask]>@ipc.org> on 04/02/2002 05:40:04 PM Please respond to "TechNet E-Mail Forum." <[log in to unmask]>; Please respond to Bev Christian <[log in to unmask]> Sent by: TechNet <[log in to unmask]> To: [log in to unmask] cc: Subject: [TN] Tin whiskers and immersion tin coatings Technetters, To a certain extent I am aware of the work the NEMI tin whisker task force and various connector/component manufacturers are doing about 100% tin coatings. But I am still left with several questions whose answers I have missed or questions that have not been addressed. So... here goes - the immersion tin coating are for SMT pads that are going to be soldered. What are people doing about test points? Are there stencil openings to put solder on these pads as well? Or are these pads left unsoldered? Has anyone carried out any testing with regards to the tendency of these materials to grow/not grow whiskers? Or do the organics in the coating completely kill that possibility? regards, Bev Christian Research in Motion ---------------------------------------------------------------------------- ----- Technet Mail List provided as a free service by IPC using LISTSERV 1.8d To unsubscribe, send a message to [log in to unmask] with following text in the BODY (NOT the subject field): SIGNOFF Technet To temporarily halt delivery of Technet send e-mail to [log in to unmask]: SET Technet NOMAIL To receive ONE mailing per day of all the posts: send e-mail to [log in to unmask]: SET Technet Digest Search previous postings at: www.ipc.org > On-Line Resources & Databases > E-mail Archives Please visit IPC web site http://www.ipc.org/html/forum.htm for additional information, or 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 1.8d To unsubscribe, send a message to [log in to unmask] with following text in the BODY (NOT the subject field): SIGNOFF Technet To temporarily halt delivery of Technet send e-mail to [log in to unmask]: SET Technet NOMAIL To receive ONE mailing per day of all the posts: send e-mail to [log in to unmask]: SET Technet Digest Search previous postings at: www.ipc.org > On-Line Resources & Databases > E-mail Archives Please visit IPC web site http://www.ipc.org/html/forum.htm for additional information, or 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 1.8d To unsubscribe, send a message to [log in to unmask] with following text in the BODY (NOT the subject field): SIGNOFF Technet To temporarily halt delivery of Technet send e-mail to [log in to unmask]: SET Technet NOMAIL To receive ONE mailing per day of all the posts: send e-mail to [log in to unmask]: SET Technet Digest Search previous postings at: www.ipc.org > On-Line Resources & Databases > E-mail Archives Please visit IPC web site http://www.ipc.org/html/forum.htm for additional information, or contact Keach Sasamori at [log in to unmask] or 847-509-9700 ext.5315 ---------------------------------------------------------------------------------