No Problem! Thank you for the clarification Richard Amol Kane M.S (Industrial Eng.) Process Engineer Harvard Custom Manufacturing, Inc. 941 Route 38 Owego, NY 13827 Phone: (607) 687-7669 x349 [log in to unmask] www.harvardgrp.com -----Original Message----- From: TechNet [mailto:[log in to unmask]] On Behalf Of Stadem, Richard D. Sent: Friday, August 18, 2006 8:23 AM To: [log in to unmask] Subject: Re: [TN] LEADFREE BGA ISSUE Amol, Sorry about any confusion I caused, what I meant was that Klein-Wassink's charts describe the rate of dissolution of nickel into molten pure tin, not a tin alloy. -----Original Message----- From: Kane, Amol (349) [mailto:[log in to unmask]] Sent: Friday, August 18, 2006 6:50 AM To: TechNet E-Mail Forum; Stadem, Richard D. Subject: RE: [TN] LEADFREE BGA ISSUE Hi Richard, Not to split hair, but I am a little confused with your statement "the information on the dissolution rate of nickel into a tin alloy from Klein-Wassink's charts are based on pure tin, not a tin/lead alloy", but how can tin be pure if it is in a alloy form with some other metal?? Am I missing something here? Regards, Amol Kane M.S (Industrial Eng.) Process Engineer Harvard Custom Manufacturing, Inc. 941 Route 38 Owego, NY 13827 Phone: (607) 687-7669 x349 [log in to unmask] www.harvardgrp.com -----Original Message----- From: TechNet [mailto:[log in to unmask]] On Behalf Of Stadem, Richard D. Sent: Thursday, August 17, 2006 1:56 PM To: [log in to unmask] Subject: Re: [TN] LEADFREE BGA ISSUE Don't always assume that just because the finish was ENIG, that it was the root cause. It may have contributed to it, but usually there is no one root cause when this happens. Secondly, even when good wetting does take place on ENIG-finished pads, upon removal the pads often appear dull. This is just the nature of the nickel finish. It does not always indicate a solderability problem with the finish. The problem may have been a reflow profile that was not hot enough, with TALT being insufficient to form a good IMF to the nickel base. It is slightly more difficult to achieve this with standard 63/37 solder on nickel than on copper, and appears to be even more difficult with SAC alloy on nickel than on copper. While the temperature is significantly hotter, the SAC alloy does not seem to form a good IMF with nickel as readily as the 63/37 solder does. Werner, the information on the dissolution rate of nickel into a tin alloy from Klein-Wassink's charts are based on pure tin, not a tin/lead alloy. What is the effect on nickel's dissolution rate when the amount of lead in the solder alloy is varied, say from 37% to 0%? -----Original Message----- From: TechNet [mailto:[log in to unmask]] On Behalf Of Colin McVean Sent: Thursday, August 17, 2006 9:34 AM To: [log in to unmask] Subject: Re: [TN] LEADFREE BGA ISSUE <Certain pads were very dull and when solder is applied on it, it seened there was dewetting issue> Sounds like an issue with the solderability of the ENIG rather than the substrate. Check with your PCB fab supplier for their comments. <By the way, such kind of issue happened only to one customer...> It only takes one instance of poor process control on ENIG to see faults occurring. Looks like this is what has happened in this case. Rgds Colin Colin McVean M.Inst.C.T. Production Manager Artetch Circuits Limited Main: 01903 725365 DD: 01903 712926 Email: [log in to unmask] www.artetch.co.uk -----Original Message----- From: TechNet [mailto:[log in to unmask]] On Behalf Of Poh Kong Hui Sent: 17 August 2006 15:24 To: [log in to unmask] Subject: Re: [TN] LEADFREE BGA ISSUE Hi Technetters, Could someone advise me the reasons to following issue. 1. There are total 25 boards for the evaluation purpose. 2. Round 1, we assemble d11 units SAC BGA onto board of ENIG. The result was 10 passed functioonal, 1 piece was not working. There was no signal & power to the BGA unit. 3. Round 2, 4 boards were being assembled, 3 passed, 1 was not working 4. Round 3, 10 boards were biring assembled, 1 was working, 9 not working. The above-stated boards undergo the same temperature profile. At the beginning, we were suspecting the board of ENIG. When 1 BGA was being removed from the failed board, and intend to perform the reballing, we realise the not all BGA substrate pads were able to solder. Certain pads were very dull and when solder is applied on it, it seened there was dewetting issue. My question is, if the failure of the BGA that was due to BGA's substrate or otherwise. By the way, such kind of issue happened only to one customer... Thanks KH Poh --------------------------------------------------- Technet Mail List provided as a service by IPC using LISTSERV 1.8e 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 or (re-start) delivery of Technet send e-mail to [log in to unmask]: SET Technet NOMAIL or (MAIL) To receive ONE mailing per day of all the posts: send e-mail to [log in to unmask]: SET Technet Digest Search the archives of previous posts at: http://listserv.ipc.org/archives Please visit IPC web site http://www.ipc.org/contentpage.asp?Pageid=4.3.16 for additional information, or contact Keach Sasamori at [log in to unmask] or 847-615-7100 ext.2815 ----------------------------------------------------- --------------------------------------------------- Technet Mail List provided as a service by IPC using LISTSERV 1.8e 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 or (re-start) delivery of Technet send e-mail to [log in to unmask]: SET Technet NOMAIL or (MAIL) To receive ONE mailing per day of all the posts: send e-mail to [log in to unmask]: SET Technet Digest Search the archives of previous posts at: http://listserv.ipc.org/archives Please visit IPC web site http://www.ipc.org/contentpage.asp?Pageid=4.3.16 for additional information, or contact Keach Sasamori at [log in to unmask] or 847-615-7100 ext.2815 ----------------------------------------------------- --------------------------------------------------- Technet Mail List provided as a service by IPC using LISTSERV 1.8e 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 or (re-start) delivery of Technet send e-mail to [log in to unmask]: SET Technet NOMAIL or (MAIL) To receive ONE mailing per day of all the posts: send e-mail to [log in to unmask]: SET Technet Digest Search the archives of previous posts at: http://listserv.ipc.org/archives Please visit IPC web site http://www.ipc.org/contentpage.asp?Pageid=4.3.16 for additional information, or contact Keach Sasamori at [log in to unmask] or 847-615-7100 ext.2815 ----------------------------------------------------- CONFIDENTIALITY NOTICE: This e-mail, and any attachments, is for the sole use of the intended recipient(s) and may contain information that is confidential and protected from disclosure under the law. 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