Hi Francois, Thanks for the input. I do have few questions. (1)Do you see any problem with board surface finishes, particularly OSP, HASL, and Nickel-Gold? (2) What should be the minimum Tg of Fab material? Is Tg of >170C is good enough? Re, Ken Patel -----Original Message----- From: Francois Monette [mailto:[log in to unmask]] Sent: Wednesday, June 09, 2004 6:28 AM To: Ken Patel; TechNet E-Mail Forum. Subject: RE: [TN] Mixed assembly of ROHS & Non ROHS components Hi Ken, These are very good questions. Based on my research many component vendors are planning to introduce new part numbers for Pb-free parts. Others are planning to handle this change with a simple date code transition. Many top-tier OEMs and EMS companies in North America and Europe are requesting new part numbers from their vendors but there is no concensus or industry standard on this subject right now. Changing part numbers is safer from a process and reliability standpoint but it creates a major inventory issue during the transition. It is not necessarily a perfect solution either since many components are perfectly compatible with both processes. Some vendor labels even include the information about the two different Moisture Sensitivity Levels (MSL) for both Sn/Pb and Pb-Free reflow temperature. Either way, component and process engineers will probably have to re-classify a large number of parts by taking into account the alloy and reflow compatibility issues. As far as the assembly BOM is concerned it is up to each individual OEM and EMS to decide how they want to handle this. My guess is that it will depend on the capabilities of the current MRP/CIM systems that are in place. As you can imagine the challenges associated with Pb-Free will require the introduction of new systems to better manage the materials on the production floor and specifically address the following issues : 1. Being able to identify and segregate Sn/Pb and Pb-Free materials (PCB, components and chemicals) 2. Validate that the right materials are used at every operation on every board 3. Provide "as-built" material and process traceability to demonstrate compliance with the legislation and customer requirements. If you are interested to understand these issue in more details I invite you to participate in one of our Web-based seminars on Material Control for Lead-Free. Please contact me offline if you would like to sign up. I am not really familiar with any specific issues associated with HASL boards so I will let someone else respond to this one. Regards, Francois Monette Cogiscan Inc. Tel : 450-534-2644 [log in to unmask] www.cogiscan.com -----Original Message----- From: Ken Patel [mailto:[log in to unmask]] Sent: June 8, 2004 4:23 PM To: TechNet E-Mail Forum.; Francois Monette Subject: RE: [TN] Mixed assembly of ROHS & Non ROHS components 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. 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