I was thinking that perhaps a switch from HASL to Immersion Tin could contribute? If the primary surface is already tin, would the tin depletion in the solder pot be less? But then again, if the PCB finish was switched to tin, why would the process still use solder with lead it in? Going only half lead-free? >>> [log in to unmask] 12/04/03 08:50PM >>> Hi Gary, LTNS! Perhaps some phenomena associated with a "new" PCB Fab/plating process? Any fab or metallurgists out there have a clue? Have a safe and happy holiday! Regards, Ed Popielarski QTA Machine 27291 Jardines Mission Viejo, Ca. 92692 Phone:949-581-6601 Fax: 949-581-2448 Cel: 949-337-2578 www.QTA.NET "Thank God for America... before it's too late!" ----- Original Message ----- From: "Gary Camac" <[log in to unmask]> To: "TechNet E-Mail Forum." <[log in to unmask]>; "Ed Popielarski" <[log in to unmask]> Sent: Thursday, December 04, 2003 2:13 PM Subject: Re: [TN] SnPb Solder pot composition > I would usually agree with Ed's statement on tin content dropping. I have many years of Kester Solder Analysis Reports, option C, that support that statement. But, for the > last four months my tin content has ran 63.16, 63.42, 63.24, and 63.4. No pure tin was added during this period, only virgin solder. Sure has got me scratching my head. > > Gary Camac > > Ed Popielarski wrote: > > > Yordan, > > > > Deviation from 63/37 can cause increased solder shorts in a wave soldering > > machine. At 63/37 (eutectic) the melt point is minimum, and there is no > > plasticus range. As you drift from there the melt point increases and the > > plastic range increases. This is why hand solder is preferred at 60/40... > > there IS plastic range and makes it easier to judge the joint as you solder. > > This is also the main cause of "frosty" joints (I hate to say "cold" since > > it is a very inaccurate term). > > > > Another thought to add to the mix is the accuracy of the lab. I recommend > > using either Alpha Metals or Kester to do the analysis (Type C which is the > > "whole enchilada" variety) and perhaps to rule out other variables discussed > > in other's postings, take a few samples, from the static part of the pot, > > from the wave after running at temperature, etc. If all the samples come > > back relatively the same, then you are good to go, but if one or two stand > > out, there could be something worth looking into. > > > > Additionally, (yes, another variable) the tin is usually the element that > > drops, not the lead. This has me wondering as well. Why? > > > > Have a safe and happy holiday! > > > > Regards, > > > > Ed Popielarski > > QTA Machine > > 27291 Jardines > > Mission Viejo, Ca. 92692 > > > > Phone:949-581-6601 > > Fax: 949-581-2448 > > Cel: 949-337-2578 > > > > www.QTA.NET > > > > "Thank God for America... > > before it's too late!" > > > > --------------------------------------------------- > > 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 ----------------------------------------------------- ********************************************************************** This email and any files transmitted with it are confidential and intended solely for the use of the individual or entity to whom they are addressed. 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