Relatively little solder is actually virgin, that is to say never used before. But there is such a thing as virgin grade. This is metal that has been smelted/refined back to a known high purity standard. Some suppliers also claim to remove non metal impurities - oxides ,sulphides and stuff. The effects of individual impurities are well documented in all soldering text books and in IPC standards. Usually your supplier will have reference data also. If you were in an ideal world your solder would be 100% pure metals exactly on the eutectic composition. In the real world this can not be the case and you have therefore departed from the ideal in someway. Any impurities present will cause the solder to behave in a less than ideal way. In use further impurities will leech from the work and the solder will go further from ideal. The point of a high purity solder is therefore two fold: 1) to reduce unknown variables 2) to keep the solder as close to ideal for as long as possible. This implies that the purest solder is the best solder, and this is true but there is a law of diminishing returns in solders as elsewhere. However your enquiry focussed on tin content. The solder could be virgin grade and still have a low tin content. It is not unusual to have different analyses results from different labs. This may reflect poor technique on sample taking or at the lab. (although most solder suppliers for obvious economic reasons usually know exactly what they are supplying) When evaluating samples like this best practice would be to send two each samples of the same material to each lab. This would enable you to see how accurate the lab is. Best practise on sampling is to run machine up to temp and take sample directly from the wave after it had been running for some time - say mid late morning from 8am start. Use a clean dry stainless steel ladle and decant immediately into a dry mould which will chill the sample solid straight away. This ensures no segregation of constituents to give false lows/highs and that the sample you are sending is representative of the pot contents. Again vendors have instructions on this and some even supply sampling kits. Hope this helps. Regards Mike Fenner Applications Engineer, European Operations Indium Corporation T: + 44 1908 580 400 M: + 44 7810 526 317 F: + 44 1908 580 411 E: [log in to unmask] W: www.indium.com Leadfree: www.Pb-Free.com -----Original Message----- From: TechNet [mailto:[log in to unmask]]On Behalf Of Paul Truit Sent: Friday, March 14, 2003 4:05 PM To: [log in to unmask] Subject: [TN] Solder analysis for 63/37 I have an issue I'd like to hear from this forum. I have recently had a sales call from "solder company B" wanting to sell me solder. When asked which solder company I use "solder company A" I am warned about the possibility of not receiving virgin grade metals. Suggests that I have an analysis performed to verify. I allowed "company B" to perform the analysis but I also sent a sample out to "company A" for the same test. The results came back not agreeing. One said my solder is fine in regard to tin content (62.78%) the other said it was bad (60.8%) The skeptic in me doesn't want to believe either of them right now. Purchasing loves to "shop" for the best price on solder. Can someone tell me about this virgin grade versus reclaimed solder? Is this a marketing idea? What defects would I see from the "inferior" one? How do I know if my solder was from "reclaimed" metal? Isn't tin tin and lead lead? Is there an unbiased source to send a solder sample to so I can really know what is in my solder pot? -- Paul Truit, Mfg. Eng. RBB Systems, Inc. 4265C E. Lincolnway Wooster, OH 44691 Ph. 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