Dave A co-op project sounds like a great idea. We had historical data before inerting and had some good data after inert that showed marked changes. Not big changes but slow increases. I had hoped to write it all up after sufficient data collection but the Lucent melt down ended that dream. Greg From: [log in to unmask] [mailto:[log in to unmask]] Sent: Friday, February 08, 2013 8:47 AM To: TechNet E-Mail Forum; Gregory Munie Subject: Re: [TN] solder skimming and contaminants Hi Greg - oh man, what a great paper that data would have made! I think there are many folks who may have not connected the introduction of inert gas wave solder pot blankets with an increase of solder pot contamination levels due to the loss of a de-drossing effect. Your details provide a great example demonstrating that sometimes advantages of one process improvement can have significant domino impact in other areas of the process. Great topic for a focus study - maybe I can have one of our co-ops take that on. Dave From: Gregory Munie <[log in to unmask]> To: <[log in to unmask]> Date: 02/08/2013 08:29 AM Subject: Re: [TN] solder skimming and contaminants Sent by: TechNet <[log in to unmask]> _____ Over ten years ago as Lucent was phasing out its on-shore manufacturing I worked with some wave solder engineers monitoring solder pots. They had recently added N2 inert to several of them and were concerned about some "changes" in the solder joints. Over the space of several months we sampled the pots and found that generally ALL trace elements steadily increased. We never had a chance to finish the study and the data is long gone but it was the general belief that the dross was actually helping keep the solder "clean". I don't remember any numbers but I believe copper was one element slowly increasing. Greg Munie PhD IPC Technical Conference Director 630-209-1683 [log in to unmask] <http://www.ipcapexexpo.org/> http://www.ipcapexexpo.org/ <http://www.ipc.org/> http://www.ipc.org -----Original Message----- From: TechNet [ <mailto:[log in to unmask]> mailto:[log in to unmask]] On Behalf Of Louis Hart Sent: Thursday, February 07, 2013 7:05 PM To: [log in to unmask] Subject: [TN] solder skimming and contaminants Technetters, my apologies for asking this question again. It has been 2 years since I asked, and I remember getting some good responses, but digging through the archives I can't find them. My memory of their content has gotten quite vague. I can only presume that the responses came directly to me, and I lost them. What chemical species are removed from a 63/37 tin-lead molten bath when the film or coating on the top surface is skimmed off? I had the theory that, along with some oxide(s) of tin, oxide(s) of copper would be removed. I'm thinking of wave solder baths. The long-term result would be elemental copper would reach some stable concentration in the bath, which concentration based on my limited data appeared to be about 0.23% by weight. And does gold, as an element, simply sink to the bottom of the bath? Louis Hart Compunetics Monroeville, PA USA [log in to unmask]< <mailto:[log in to unmask]> mailto:[log in to unmask]> 412-858-1232 ______________________________________________________________________ This email has been scanned by the Symantec Email Security.cloud service. For more information please contact helpdesk at x2960 or [log in to unmask] ______________________________________________________________________ ______________________________________________________________________ This email has been scanned by the Symantec Email Security.cloud service. For more information please contact helpdesk at x2960 or [log in to unmask] ______________________________________________________________________ ______________________________________________________________________ This email has been scanned by the Symantec Email Security.cloud service. For more information please contact helpdesk at x2960 or [log in to unmask] ______________________________________________________________________