Are you seeing any signs of 'tin whiskers' or on assemblies in the field? Barbara J. Burcham, C.I.D. Fairfield Industries, Inc 281-275-7687 [log in to unmask] -----Original Message----- From: DesignerCouncil [mailto:[log in to unmask]] On Behalf Of Kowalewski, Andy Sent: Wednesday, June 16, 2004 1:27 PM To: [log in to unmask] Subject: Re: [DC] Lead free processes and the impact to your PCB manufactu ring and assembly Every design we do now is lead free because of international markets, and let me share some of my observations: We haven't changed pad sizes, initially because our designs are so small we couldn't. After a lot of environmental testing, pad sizes the way they are for PbSn is good for lead free also, at least for our boards. Haven't found any differences in lead free RF characteristics. Again our very small designs are swamped by other issues and the very short RF traces are not affected by the small changes caused by lead free solders, if any. One of the biggest factors is that lead free solder doesn't flow anything like leaded solder when reflowed. It stays where its put, and just melts. As a result, we have managed to do away with solder mask altogether under our flip chips for better underfill flow, and we get no short circuits even with 50um (2 mil) traces and spaces pad-to-trace. Solder mask registration was a showstopper for our tight designs with leaded solder, because the solder mask registration tolerance meant we had to keep traces at least 100u (4 mil) away from pad edges, with a 50u (2 mil) pad-to-mask opening. Now we have a lot more room to manouver. As well, the solder doesn't wick down the entry traces at all. Another big issue is the Tg of the laminate because of the higher reflow temperature, usually 260 degrees C. We use BT cores and high Tg RCC foils - that gives us some latitude as our modules get two reflow passes in assembly and another one when mounted on a cutomer's motherboard. So far it's working well. Initially component supply was a problem but that's almost gone away for what we do. In fact some components aren't available in anything but lead free metalization. We did have some problems a while ago with reflow soldering some components with tin/lead solder - component fabricators had changed the metalization to lead free without notice and reflow profiles needed tweaking. Andy K. Sychip Inc Office (972) 202 8852 -----Original Message----- From: DesignerCouncil [mailto:[log in to unmask]] On Behalf Of George Patrick Sent: Wednesday, June 16, 2004 1:05 PM To: [log in to unmask] Subject: Re: [DC] Lead free processes and the impact to your PCB manufactu ring and assembly We are finding real problems with parts procurement, and have found that roadmaps of some of our parts suppliers is to phase out lead terminated parts fairly rapidly. We also don't know the impact yet, but are watching the situation since some of the termination chemistries are not very compatible with the normal PbSn chemistries. The main issue we have found is the higher soldering temperature. We don't have enough data yet to verify reliability problems due to the changes in solder fillets, but it is a possibility pad sizes will have to increase because of it, and because of the centering and tombstoning that is more prevalent. We have also found some differences in electrical characteristics of High-frequency RF boards that have necessitated changes in circuit values and re-layout of critical circuits, mainly in areas free of soldermask. My information is second hand, I am not on the core team so I don't have details. A LOT of designers have their collective heads in the sand about this. When the PNW chapter polled for what members and associates wanted to hear about this year, lead-free was last or second-from-last thing on the list. -- George Patrick Tektronix, Inc. Central Engineering, PCB Design Group P.O. Box 500, M/S 39-512 Beaverton, OR 97077-0001 Phone: 503-627-5272 Fax: 503-627-5587 http://www.tektronix.com http://www.pcb-designer.com It's my opinion, not Tektronix' -----Original Message----- From: Brooks,Bill [mailto:[log in to unmask]] Sent: Wednesday, June 16, 2004 10:11 To: [log in to unmask] Subject: [DC] Lead free processes and the impact to your PCB manufacturing and assembly Yesterday I was reading the cover article in Electronic Design on "Managing Product Obsolescence" page 47 by Ron Schneiderman and it alarmed me so that I fired off an e-mail to my boss in engineering and the heads of the company manufacturing group. It seems we can't ignore the changes in the industry or procrastinate and keep using tin/lead solder if the component manufacturers are going all lead free... (unless the components they make are compatible with both processes.) That I have not looked into as yet, but I can assure you, I will be learning more about the lead free process and what the potential impacts will be on our ability to produce our products. Until now, I have been sitting on the sidelines listening in occasionally to issues on the lead free debate... I didn't think it would affect us directly, but now it looks like I am forced to really pay attention to it because it will most likely affect us all. I would be grateful if you have had experience with the lead free manufacturing process and its impacts at your company and would like to know how you dealt with it... I want to capture a list of potential needed adjustments to our processes and designs that we should be looking into changing and help to get us on that path so we can prevent any potential manufacturing/rework issues in advance. Here's what I wrote: ------------------------------- Greetings - There has been much discussion in the IPC and in the electronics manufacturing news circuit on the 'lead free' mandate that the E.U. authored years back... We will be seeing the effects of it coming to a head in the very near future, if it has not already begun to affect us by now. If electronics parts manufacturers are moving to lead free compatible components at the rates suggested in the news we are in for more parts obsolescence issues and in larger quantities than we have seen before. Ref Electronic Design magazine cover article "Managing Product Obsolescence" June 7,th 2004. We would be prudent to study the impact of lead free technology on our compliment of components and make sure we head off this potential design and manufacturing procurement bottleneck before it rears its ugly head in the middle of production of a large order. (I would suspect that there has already discussion about this at higher levels... ) Even if we say that we might be exempt from using lead free processes in our products as I have heard some military suppliers say, we may find that we cannot get the parts that would work with a tin/lead soldering process after a few years... They are going to decline out of demand and that will drive them into obsolescence. The only people with lead process parts in stock will be the scalpers and higher priced component brokers. I would expect there to be exceptions to the rule but we need to identify the potential problems before they get to be problems. PCNalert, a company that monitors and reports on parts obsolescence issues, is receiving 50 parts obsolescence notices a day now. That trend will most likely get worse before it gets better. If we do decide to go lead free in our processes we will need equipment that can support the soldering temp profiles and higher temp materials will be required for boards. This may also affect the footprint patterns for many parts as well. I'm sure there will be other impacts, supplies of lead free solder for rework, higher temp soldering irons, fluxes with different chemistries, potential safety issues, training to deal with newer technologies... the list may be long... The deadline for compliance with the E.U. hazardous substance mandate is 2006. We will probably see common lead containing components drop off in availability before then as the lead free counterparts are becoming more and more available. I just wanted to bring it to your attention if you had not thought of the potential impacts on your department or specific activities here at Datron. Best regards, Bill Brooks PCB Design Engineer , C.I.D., C.I.I. Tel: (760)597-1500 Ext 3772 Fax: (760)597-1510 http://pcbwizards.com ------------------------------------------------------------------------ ---- ----- DesignerCouncil 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 DesignerCouncil. To set a vacation stop for delivery of DesignerCouncil send: SET DesignerCouncil NOMAIL Search previous postings at: www.ipc.org > On-Line Resources & Databases > E-mail 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 ------------------------------------------------------------------------ ---- ----- ------------------------------------------------------------------------ --------- DesignerCouncil 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 DesignerCouncil. To set a vacation stop for delivery of DesignerCouncil send: SET DesignerCouncil NOMAIL Search previous postings at: www.ipc.org > On-Line Resources & Databases > E-mail 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 ------------------------------------------------------------------------ --------- ------------------------------------------------------------------------ --------- DesignerCouncil 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 DesignerCouncil. To set a vacation stop for delivery of DesignerCouncil send: SET DesignerCouncil NOMAIL Search previous postings at: www.ipc.org > On-Line Resources & Databases > E-mail 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 ------------------------------------------------------------------------ --------- --------------------------------------------------------------------------------- DesignerCouncil 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 DesignerCouncil. To set a vacation stop for delivery of DesignerCouncil send: SET DesignerCouncil NOMAIL Search previous postings at: www.ipc.org > On-Line Resources & Databases > E-mail 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 ---------------------------------------------------------------------------------