Hydrochloric acid may be the right thing for very heavily corroded metal but I would use it as a last resort because the etching action that you describe often leaves the surface of the metal pitted at a microscopic level which greatly increases the surface area and will allow future oxidation to happen much more quickly. In other words, you should tin the metal asap after the acid etch (and rinse with water) to provide a protective coating. On Mon, Mar 4, 2019 at 10:02 PM Ryan O'Connor wrote: > Yep acid is one of those magic bullets for getting crap off metal. It's > just messy.. I use hydrochloric acid for everything, a bath of it eats > thick rust off tools in a few minutes - don't get it on your skin or > breathe it. Also interesting fact: acid doesn't just etch oxide off metal= , > it will etch the metal itself too. So you need to control the period of > time it soaks in the acid depending on the approx. thickness of the oxide > layer and strength of the acid so as not to damage the structure of the > metal. Usually when the reaction has completed enough, washing it in wate= r > dilutes it enough to stop the reaction. But on components it may be bette= r > to just apply plain solder after the reaction dies down, being careful of > spitting, before any oxide has time to form again. Usually if I do this > with tools I will dry them with paper towels and after a few minutes spra= y > them with a rust inhibitor. > > Ryan > > On Tue, 5 Mar 2019 at 13:08, Bob Blick wrote: > > > When I had a huge project that required a LOT of solder(100 pounds) and > > dirty sheet metal, I used dilute swimming pool acid for flux. I think I > > settled on about a 10 to 1 water to acid mix, maybe a little stronger. > Only > > strong enough that it bubbles a little. Rinse with water immediately > after > > soldering, although the soldering process seemed to neutralize the acid > > everwhere it got to soldering temperature. A gallon goes a long way, I > > still have plenty left over! Also good for removing galvanizing from > steel > > prior to welding at about 2 to 1 mix. > > > > Cheerful regards, Bob > > > > ________________________________________ > > From: piclist-bounces@mit.edu on behalf of > > Dwayne Reid > > Sent: Monday, March 4, 2019 3:06 PM > > To: Microcontroller discussion list - Public. > > Subject: Re: [EE] oxidized pins > > > > Hi there, Manu. > > > > I would try tinning the leads with solder and a very active flux. My > > flux of choice is Kester AZ-2331 Water-Soluble flux. This flux is > > extremely active and must be washed off under running warm water when > > you are finished. The flux turns to soap bubbles when hit with warm > > water and it is safe to flush down the drain. > > > > If that flux doesn't work, you can try acid-based flux as used for > > soldering copper plumbing pipe. You would have to find out what > > cleans that flux - most likely is NOT water. > > > > The Kester AZ-2331 flux has worked wonders with oxidized component > > leads and switch solder lugs for me. Your mileage may vary. > > > > dwayne > > > > > > At 11:52 PM 3/2/2019, Manu Abraham wrote: > > >Hi, > > > > > >I have this large bag of through-hole standard crystals, which have > > >their pins oxidized, since the bag was left open for a while and thus > > >solderability is a big issue. > > > > > >The crystals are good, just that time has to be spent scraping the > > >oxide of the pins which is a waste of time. > > > > > >Is there a better way to remove the oxide layer other than scraping, > > >probably by a chemical process or so ? > > > > > >Any thoughts ? > > > > > >Thanks, > > >Manu > > > > > > -- > > Dwayne Reid > > Trinity Electronics Systems Ltd Edmonton, AB, CANADA > > 780-489-3199 voice 780-487-6397 fax 888-489-3199 Toll Free > > www.trinity-electronics.com > > Custom Electronics Design and Manufacturing > > > > -- > > http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive > > View/change your membership options at > > http://mailman.mit.edu/mailman/listinfo/piclist > > > > -- > > http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive > > View/change your membership options at > > http://mailman.mit.edu/mailman/listinfo/piclist > > > -- > http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive > View/change your membership options at > http://mailman.mit.edu/mailman/listinfo/piclist > --=20 http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist .