Hi Francois, So, do you recommend the following? 1) new part numbers for lead free components 2) No problem with HASL processed boards? 3) separate assy BOM for lead free components Re, Ken Patel -----Original Message----- From: TechNet [mailto:[log in to unmask]] On Behalf Of Francois Monette Sent: Tuesday, June 08, 2004 10:32 AM To: [log in to unmask] Subject: Re: [TN] Mixed assembly of ROHS & Non ROHS components Hi Daan, I am currently in the process of writing a paper on Material Control for Lead-Free and here is some relevant information that I found on the subject of alloy compatibility : Backward Compatibility (i.e. using Pb-Free components in Sn/Pb process): BGAs with Pb-Free solder balls are not recommended for Sn/Pb assembly using temperatures below 220C because the solder joints are poorly formed if the balls do not melt. As a result 2nd level reliability may be adversely affected. There is also a potential for increased Sn-whisker growth if the finish does not melt. Forward Compatibility (i.e. using Sn/Pb components in Pb-free process): Less of an issue, some reports of increased voiding in PBGA solder ball joints due to flux trapping. Another issue that was already pointed out is the resulting Lead-Contamination that may affect the solder joint structure and decrease its reliability. As a result of the above issues, some component vendors, including Intel do not recommend using their components in forward or backward compatible assemblies. References : - Pb-free IC Component Issues & IPC/JEDEC Specification Update - Rick Shook, Agere Systems http://www.turi.org/messages/Rick_Shook-Dec3-03.pdf - Lead Contamination in Lead-Free Electronics Assembly - Karl Seelig and David Suraski, AIM http://www.aimsolder.com/techarticles/Lead%20Contamination%20in%20Lead-Free% 20Electronics%20Assembly.pdf - Lead-Free Program Overview - Intel Web Site http://www.intel.com/design/flcomp/packdata/wccp/download/chpt8.pdf I hope this information is helpful. Feel free to use it for your web site if you wish. Francois Monette Cogiscan Inc. [log in to unmask] www.cogiscan.com Date: Mon, 7 Jun 2004 15:38:34 +0200 From: Daan Terstegge <[log in to unmask]> Subject: Re: Mixed assembly of ROHS & Non ROHS components Hi Blair, Out of the many articles that I have read about this subject not a single one clearly states that leaded parts in leadfree solder is a big "NO". The researchers seem to limit their conclusions to statements like "combination A fails after 3000 cycles, combination B after 2930 cycles" or "combination A is stronger than combination B". I welcome all papers that support other opinions, and I'm willing to add them to my leadfree webpage for everyone's benefit. To my opinion the issue of thermal detoriation of components that were not designed for the higher leadfree soldering temperatures is a much more viable concern. Daan Terstegge Thales Communications Unclassified mail Personal Website: http://www.smtinfo.net >>> [log in to unmask] 06/04/04 03:25pm >>> I have no actual experience with this, however, from what I have learned in following this list and the LeadFree list is that if you use components with Pb (lead) based finishes on the leads in a lead-free process, the reliability of the solder joints is questionable. If you use lead-free finishes in a tin-lead soldering process effect is minimal. Others on this list can explain why, and you may be able to find that information in a search of the archives. Bottom line is if you are using a lead-free soldering process, it is highly recommended that all components used are also lead-free. If you still have a tin-lead process, you can mix. Blair Hogg QA Manager GAI-Tronics Corp. --------------------------------------------------- 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 847-509-9700 ext.5315 ----------------------------------------------------- --------------------------------------------------- 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 847-509-9700 ext.5315 -----------------------------------------------------