Richard H. Posted December 28, 2010 Share Posted December 28, 2010 (edited) Bought a load of chips on EBay, the legs have a sort of oxide on them that won't let solder through. I've tried flux and tinning with the iron turned fully up, but it still won't stick. Scraping sort of works, but it bends the legs (surface mount) Is there some easily available chemical (acid ?) I can use to get it off ? Thanks Edited December 28, 2010 by Richard H. Quote Link to comment Share on other sites More sharing options...
+save2600 Posted December 28, 2010 Share Posted December 28, 2010 (edited) Maybe some CLR and a toothbrush? Doubt it though. Extremely fine sandpaper or a fiberglass brush works best. Lightly sand both sides of the legs until shiny again and yes, this can be done without bending or breaking the legs if you're careful. Edited December 28, 2010 by save2600 1 Quote Link to comment Share on other sites More sharing options...
Richard H. Posted December 30, 2010 Author Share Posted December 30, 2010 I was really hoping for a chemical method as I have about 400 of them to de-oxide Quote Link to comment Share on other sites More sharing options...
+batari Posted December 30, 2010 Share Posted December 30, 2010 I was really hoping for a chemical method as I have about 400 of them to de-oxide Have you tried acids of varying strength, as well as bases? I'd think one or the other would work. Quote Link to comment Share on other sites More sharing options...
Video Posted December 30, 2010 Share Posted December 30, 2010 Chips are sealed in epoxy (or plastic? What is that black shit anyways/) Maybe you could drop them in a jewelry cleaner machine? They use chemicals and vibration to take corrosion off of jewelry, maybe it could take oxide off chips. If you don't mind ruining (or risking ruining) you could try this. If it works, or the caused failure rate is acceptable, I think this would be a good solution. Quote Link to comment Share on other sites More sharing options...
+batari Posted December 31, 2010 Share Posted December 31, 2010 Other suggestions are to use a reducing agent. I am not a chemist, but I think reducing agents remove oxidation. I looked some up and see that hydrogen peroxide can act as a reducing agent. I also see ascorbic acid on the list (which I believe is in vitamin C pills.) I have had the same problem with oxidation but on some through hole pads on PCBs. Fortunately the oxide is just on one side so I can solder the chips to the top, but it would be nice to be able to clean them, so I may try a few things later. Quote Link to comment Share on other sites More sharing options...
Rybags Posted December 31, 2010 Share Posted December 31, 2010 Maybe just try a white vinegar soak... I used to do it on coins. About 8 hours would do the trick. Try one or two testbeds first. Quote Link to comment Share on other sites More sharing options...
Richard H. Posted December 31, 2010 Author Share Posted December 31, 2010 Have you tried acids of varying strength, as well as bases? The only thing I tried was jewellery cleaning fluid. The dip and strip stuff. It had no effect. Quote Link to comment Share on other sites More sharing options...
+5-11under Posted December 31, 2010 Share Posted December 31, 2010 I'm in the same boat, with a bunch of EPROMs. If anyone has any solutions, please reply. I'm trying the hydrogen peroxide right now. It's only 6% solution, and the chips are pretty "dirty", so I've got my doubts. If I had some CLR, I'd try that. I have no idea if it will work, but it'd be a simple solution if it works as well as the commercials. Another thing I've thought of is to put the chips in a container partially filled with dry sand, and shake it up until the pins look clean. Of course the labeling and package and EPROM window, in my case, will also be sanded to some degree. Quote Link to comment Share on other sites More sharing options...
Video Posted December 31, 2010 Share Posted December 31, 2010 A sand box could work, just tape over the windows/labels and you should be OK 1 Quote Link to comment Share on other sites More sharing options...
nathanallan Posted December 31, 2010 Share Posted December 31, 2010 (edited) A sand box could work, just tape over the windows/labels and you should be OK Right, sounds like how to get rust out of a gas tank, and seems like it would work here and you'd need very fine grit sand. LOL sand from Nazca should do it. /edit To clarify, the white sand found at Nazca is finely ground glass. No idea how it got there, but you can definitely make your own for a project like this. Tools: piece of glass to be ground up, one heavy stone with a flat surface and one flat surface, best if it is stone, too. Stone Age electronics Edited December 31, 2010 by nathanallan Quote Link to comment Share on other sites More sharing options...
Dave Neuman Posted December 31, 2010 Share Posted December 31, 2010 This might work Quote Link to comment Share on other sites More sharing options...
A.J. Franzman Posted January 1, 2011 Share Posted January 1, 2011 (edited) I looked some up and see that hydrogen peroxide can act as a reducing agent. I'm trying the hydrogen peroxide right now. It's only 6% solution, and the chips are pretty "dirty", so I've got my doubts.If I had some CLR, I'd try that. I have no idea if it will work, but it'd be a simple solution if it works as well as the commercials. You Fail Chemistry Forever. Hydrogen peroxide is an oxidizer, which is the opposite of a reducing agent. If you want to clean an oxide off a metal, you don't use an oxidizer to do it! Hydrogen peroxide, bleach, and a large number of other chemicals will rapidly create oxides and their chemical relatives on metal surfaces. I have personally used bleach to almost instantly "rust" a length of brand-new shiny metal chain for use as a halloween prop. It was much easier, more authentic looking, and more durable than painting it... CLR, Tarn-X, vinegar, or another acid would be much better alternatives. Edited January 1, 2011 by A.J. Franzman Quote Link to comment Share on other sites More sharing options...
+batari Posted January 1, 2011 Share Posted January 1, 2011 I looked some up and see that hydrogen peroxide can act as a reducing agent. I'm trying the hydrogen peroxide right now. It's only 6% solution, and the chips are pretty "dirty", so I've got my doubts.If I had some CLR, I'd try that. I have no idea if it will work, but it'd be a simple solution if it works as well as the commercials. You Fail Chemistry Forever. Hydrogen peroxide is an oxidizer, which is the opposite of a reducing agent. Nope. Hydrogen peroxide can act as either an oxidizing or reducing agent. Funny link though. Quote Link to comment Share on other sites More sharing options...
Richard H. Posted January 4, 2011 Author Share Posted January 4, 2011 I have one chip soaking in vinegar. Will let you know if it works by tomorrow (it will have had 48 hours by then). Quote Link to comment Share on other sites More sharing options...
+5-11under Posted January 4, 2011 Share Posted January 4, 2011 If the vinegar works, it's an easy solution. I might try it myself starting tonight. Coca Cola might work the same, but is messier. The weak hydrogen peroxide did not work. Quote Link to comment Share on other sites More sharing options...
A.J. Franzman Posted January 4, 2011 Share Posted January 4, 2011 When MythBusters did Coca-Cola myths, they found that it didn't work as an engine degreaser, but it worked at least as well as a leading commercial product (!) for cleaning rust off of chrome bumpers. So it may actually work better than vinegar for de-oxidizing those IC pins. Quote Link to comment Share on other sites More sharing options...
+batari Posted January 5, 2011 Share Posted January 5, 2011 When I used to collect coins, I found that adding a little salt to the vinegar rapidly increased the reaction time. That is, it would clean them in seconds instead of hours. I was also thinking an electrolysis method may also work. Try a weak salt solution with a small current and two metal plates, and rest the chip on one of the plates (or perhaps hold it down) on the plate to make better contact. Alternatively you could try a non electric method like holding it against a plate of galvanized steel in solution. Does anyone know what metal chip pins are made of? Tin maybe? Quote Link to comment Share on other sites More sharing options...
Richard H. Posted January 5, 2011 Author Share Posted January 5, 2011 The vinegar soaking did not work at all Quote Link to comment Share on other sites More sharing options...
Video Posted January 5, 2011 Share Posted January 5, 2011 The vinegar soaking did not work at all How long did it soak? I know, oddly, that if you soak metal in vinegar for a frew hours, it can take rust off...but if it stays in to long, it will actually reverse the effect and cause the metal to rust. Heh, plaiting, that might be cool, if you don't fry the chip. Try jewelry polish, or maybe you can use toothpaste, it takes some scratches off CD's, maybe it can help on metal too? Quote Link to comment Share on other sites More sharing options...
Dave Neuman Posted January 6, 2011 Share Posted January 6, 2011 The vinegar soaking did not work at all Maybe Naval Jelly http://www.ehow.com/how_4465030_remove-rust-naval-jelly.html Quote Link to comment Share on other sites More sharing options...
A.J. Franzman Posted January 6, 2011 Share Posted January 6, 2011 (edited) When I used to collect coins, I found that adding a little salt to the vinegar rapidly increased the reaction time. That is, it would clean them in seconds instead of hours. [snip] Does anyone know what metal chip pins are made of? Tin maybe? Vinegar (acetic acid) is a weak acid. Acetic acid + NaCl (salt) produces hydrochloric acid, a strong acid. But everything I've ever read on coin collecting says don't clean them, if they have any value, because you'll only reduce it. I'm not sure about surface-mount IC leads, but I know older through-hole component leads were typically either copper or mild steel, tinned with either pure tin or the usual 63/37 lead/tin solder. You could tell the steel from the copper because the steel ones are attracted to magnets. Today they're probably all tinned with either pure tin or one of today's 2/98 silver/tin solders or some similar low toxicity stuff, but I don't know if IC pins now are copper (doubtful -- too soft), plain mild steel, or some specific alloy. Edited January 6, 2011 by A.J. Franzman Quote Link to comment Share on other sites More sharing options...
Richard H. Posted January 6, 2011 Author Share Posted January 6, 2011 How long did it soak? About 50 hours. I took a look at 24 and there was no change. Some of the legs appear to have even more oxide on now I'm just wondering if it's worth buying one of those ultrasonic water bath cleaners. Quote Link to comment Share on other sites More sharing options...
A.J. Franzman Posted January 6, 2011 Share Posted January 6, 2011 An ultrasonic cleaner by itself will not remove any oxidation except that which you could just as easily scrub off with a stiff brush, but it will usually speed up most cleaning/chemical baths significantly. First you need to find something that works. Quote Link to comment Share on other sites More sharing options...
albadry27 Posted November 1, 2015 Share Posted November 1, 2015 I have the same issue with an early 90s pcb that would not respond to washing with a toothbrush and liquid soap nor did normal white vinegar soaking have any effect on it, I'm going to try and add salt to it and feedback the results Sent from my Archos 50b Neon using Tapatalk Quote Link to comment Share on other sites More sharing options...
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