Why you no spill these secrete soldering beans? - Page 1
Forum section: electronics / beginners

author: Paul Price
author_rank: Super Contributor
timestamp: May 14, 2025, 02:42:17 am
content: Applying lead/Sn solder to anything that will be in long contact with human skin is making a repair that poisons the person seemingly benefiting from a repair.

author: coppercone2
author_rank: Super Contributor
timestamp: May 14, 2025, 02:42:51 am
content: where bond wire go??

author: Analog Kid
author_rank: Super Contributor
timestamp: May 14, 2025, 02:47:37 am
content: Quote from: Paul Price on May 14, 2025, 02:42:17 amYes!But what about using silver solder (or other non-lead solder)?

author: Ian.M
author_rank: Super Contributor
timestamp: May 14, 2025, 03:45:46 am
content: The video shows an incorrect method for making 'Killed spirits of salt', which was a commonly used plumbing and tin-smith's flux back in the day. Spirits of salt is the old name for Hydrochloric acid, and you 'kill' it by reacting it with an excess of Zinc, till no more can be dissolved in it. This produces a solution ofZinc Chloridewhich is an excellent flux for soft-soldering metalwork, but is absolutely unsuitable for electronics use as any remaining traces of it will soon corrode through the thin traces common on PCBs, fine stranded wire etc. Modern plumbing fluxes typically contain zinc chloride. It will also f--k up your good electronics soldering iron bits very quickly by corroding through their protective iron plating. Ideally don't use the same iron for metal work as electronics, but if you must, keep a heavy bit just for metalworking, that you are willing to dress with a file as necessary as it gets pitted, and clean the retaining barrel carefully, especially inside, when swapping back to your good bits. Ideally clean the part afterwards with plenty of really hot water and a little soap, as the acid residue is nasty and corrosive.

author: coppercone2
author_rank: Super Contributor
timestamp: May 14, 2025, 03:53:35 am
content: all the pipe fluxes I have are zinc chloride containing. (30%) i.e. oatley fluxThey add ammonium chloride too.Killing it is for storage, the reaction is that when you heat the zinc chloride it makes HCl anyway!I don't think free HCl is any problem if you make it, it is made as soon as you heat the flux up. it decomposes. If there is no HCl it just won't mess up your storage if its in the wrong container, and of course its more corrosive if you let it drip (making it impractical to use for anything but precise benchtop soldering (not electronics)ZnCl2 works great. It probobly works better with free HCl that pickles the metal for a little bit before the heat starts too. But its a 'nasty' chemical to work with.The hard part might be getting the plumber to wait for the joint to cool a little and then wipe it down with clean rags to actually make sure its clean after soldering. The zinc inside should be washed by flushing the pipe, its rather water soluble.I see what plumbers are likely to do, is get a dirty rag that is caked with probobly zinc chloride and dirt (it stands up on its own), wet it a little bit from dirty pipe water that happens to be around, then smack the pipe with it like its in the locker room in a private school and then call it a day. Really you should have a clean box of rags and do a precise job with fresh water to clean the pipe when you are done, and probobly use two rags, one for bulk cleanup and one for fine clean up (like car windows)As for using it on electronics, Theoretically you can if you wash it. Practically there is some business that goes on with clingly chloride ions or something that makes it a near impossibility to use it safely on circuit cards. Maybe with ultrasonic cleaning and some real care (i.e. triple or more wash in fresh deionized water tanks). This is the reason why HCl cleaning of steel is not popular either, its too hard to get it off the steel for some chemical reason, maybe it gets into the grain structure or something.. .then later when there is moisture it comes out and causes more damage, seemingly even if you neutralize it with baking soda or whatever... so we use organic acids for rust removal that are alot better or perhaps just easier to clean off (i.e. citric acid, which also happens to be in some electronic fluxes (rosin type) as an additive )I would love to know from a chemist prospective why chlorine is such a menace for cleaning compared to other acids for deoxidation. Its super water soluble, but for some reason its just no good practically on anything but the most imprecise tasks (pipe).. all the side products it makes like metal chloride are super soluble in water.I thought about experimenting but its kind of a waste of time..zinc chloride dissolves 432 g per 100 g of water at 25°C. You would think that just rinsing it in a sink would leave your board ultra clean