I was reading the latest issue of circuitree in was a article on the effects of surface finish on high frequency. http://www.circuitree.com/CDA/ArticleInformation/coverstory/BNPCoverStoryIte m/0,2135,26684,00.html I pasted a link to the article as I would butcher it if I tried to summarize the article article. They did state that after a number of tests the results where that immersion silver was better then ENIG in preventing signal loss. Also in this issue was a add for OSP for mixed metal finishes. I am not a assembler just a designer, so I do not know how long they have been on the market or if anyone has tried them. the names where Glicoat SMD E2L, and Glicoat SMD F2. They state that one could reach a thinner coating of there product compared to most on the market. I do not put much faith an add, what looks good on paper does not mean it looks good in the real world. www.electrochemicals.com I would be interested too find out if anyone has tried this product and had better results. Ted -----Original Message----- From: Furrow, Robert Gordon (Bob) [mailto:[log in to unmask]] Sent: Friday, June 29, 2001 8:04 AM To: [log in to unmask] Subject: Re: [TN] **** PCB's - HASL -v- OSP One issue that OSP's can not resolve that HASL can, is confirming the inherent solderability of the copper. We have experienced busts where very thin layers of soldermask residue or else incomplete tin stripping has caused what looks like a nice clean copper surface to be unsolderable. With OSP's you don't realize the problem until after many expensive components have been placed. It is possible to scrape the pads that don't wet and repair, but there is the question of all the other areas on the board being suspect. We end up scrapping this product rather than repairing. An even more prevalent issue is if the product has via in pads, then if the via hole is not sufficiently rinsed and thoroughly dried, the OSP protection on the surface of the pad is degraded over time and can cause soldering issues. Again, this is not seen until after surface mount and is not something we would repair. It doesn't take too many issues such as this to make OSP's less desirable. HASL has its own issues (coplanarity and cleanliness) being the two that most effect the assembler. With all this being said, many Lucent locations have decided upon Immersion Silver as the coating of choice. Thanks, Robert Furrow Printed Wiring Board Engineer Strategic Supply Global Account Manager Supply Chain Networks Lucent Technologies 978-960-3224 [log in to unmask] -----Original Message----- From: Andrew Hoggan [mailto:[log in to unmask]] Sent: Friday, June 29, 2001 3:44 AM To: [log in to unmask] Subject: Re: [TN] **** PCB's - HASL -v- OSP If there are problems soldering to OSP check the quality of the OSP coating, too thick and there'll be soldering problems, too thin and there'll be too much copper oxidation, hence the variability in results. I spent years following the route that OSP coatings had some magical property that interfered with soldering. WRONG! OSP coatings are very simple chemistry that are relatively easily soldered to, however although relatively simple chemistry they are not necessarily easy to lay down, careful process control is required to get the correct thickness of coating. Get it wrong and the above circumstances can occur. If anyone has OSP issues contact me offline and I can perhaps give you a bit more info. I have a background in these and soldering materials, note though that I don't currently work for any suppliers, I am completely independent these days. Andrew Hoggan BBA Associates www.bba-associates.com -----Original Message----- From: TechNet [mailto:[log in to unmask]]On Behalf Of [log in to unmask] Sent: Thursday, June 28, 2001 09:12 To: [log in to unmask] Subject: Re: [TN] **** PCB's - HASL -v- OSP I am an NPI Engineer at Artesyn technologies and I am new to the Surface Mount Technology. Can anyone shed some light on the differences between HASL and OSP. We are currently using HASL but are looking at migrating to OSP. What are the pros and cons of one over the other? What sort of processing issues do we see with OSP on SMT lines? **Cormac, one responder said co-planarity is one factor to consider in a comparison, which is true, but not the ONLY reason. If you believe the marketing literature for OSPs (and if you do, you deserve all the agony you are about to experience), then the OSP is sacrificial and only survives 1 pass in reflow. Sometimes this is true, other times not true. I have seen OSP survive 5-6 exposures to reflow conditions without burning off. Lots of solderability issues if you have multiple passes through reflow. A significant factor is also the aggressiveness of the flux you will be using. I have seen a number of manufacturers go to no clean, for the benefits afforded by a low solids flux, only to find that it was not aggressive enough to overcome the OSP. If you are using a water soluble flux, you should not have this problem. If you are going no-clean, then you have some homework to do. In addition, we all know that HASL is a nasty, dirty, filthy, rotton (fill in the descriptor of your choice) process and often leaves nasty, dirty filthy rotton residues behind. It does nasty things to insulation resistance. If you are going the no-clean route, HASL residues can kill your product and sometimes, users of your product. By comparison, OSP is a much cleaner process and does not impact insulation resistance. Doug Pauls Rockwell Collins ---------------------------------------------------------------------------- ----- 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 the following message: SET Technet NOMAIL 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 the following message: SET Technet NOMAIL 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 the following message: SET Technet NOMAIL 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 the following message: SET Technet NOMAIL 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 ---------------------------------------------------------------------------------