purple HCl

[Geo]

keep in mind that the silver in solder has already been acted on chemically while melting. and too, when the bond between the tin and silver occurs your not going to have a big honking chunk of silver. the silver will be so finely divided that the particles may only be the size of colloidal powder to start with. silver will not displace hydrogen in hcl, and this is the reason theres no reaction. i have read that silver will react with hcl in the presence of certain other metals. one of them is lead. ill try to dig up the reference to it. when people say that hcl will not react to silver, it is very true. but solder isnt just silver, theres acids involved and other metals. i may be barking up the totally wrong tree here, but electronic solder is often referred to as "acid core" solder.

 

[NobleMetalWorks]

keep in mind that the silver in solder has already been acted on chemically while melting. and too, when the bond between the tin and silver occurs your not going to have a big honking chunk of silver. the silver will be so finely divided that the particles may only be the size of colloidal powder to start with. silver will not displace hydrogen in hcl, and this is the reason theres no reaction. i have read that silver will react with hcl in the presence of certain other metals. one of them is lead. ill try to dig up the reference to it. when people say that hcl will not react to silver, it is very true. but solder isnt just silver, theres acids involved and other metals. i may be barking up the totally wrong tree here, but electronic solder is often referred to as "acid core" solder.

Acid core solder is used for fitting pipes together, plumbing, fusing pieces of metal together, etc. It's usually made up of tin/zinc but can have silver, lead etc in it. I don't think it's used for electronics at all. You use a regular flux core for electronics solder. In manufacturing electronics, solder is extruded through a head that is heated to high temperature, this negates the need for flux to melt the solder quicker. Acid core solder isn't used in the manufacture of modern electronics because it could have a corrosive affect on the component and/or the PCB.

There may be a tiny amount of silver in solder used for electronics, but the color purple I am seeing in the bucket, doesn't really look like the color that you see when silver nitrate is exposed to sunlight. That is generally, per my experience, a darker more deep purplish grey than the color you are seeing in the stratified layers in the picture. Because the boards were not depopulated beforehand, there is probably no telling what the purple layer is, but I don't feel like it would be silver.

Scott

 

[goldenchild]

The issue isn't the color or its hue. It's the fact that it's in aqueous form that has me convinced that tin is making the solution purple. Silver chloride can be anywhere from the lightest purple to almost black when exposed to the sun. It just depends on how long it is exposed. I think we are overlooking the fact that if silver chloride (aqueous form) was exposed to HCl then it would be converted into a solid chloride (cottage cheese like). It would also quickly settle and not stay in a stratified layer. Is there any of this material on the bottom of the bucket mjgraham?

 

[mjgraham]

No there was nothing like that just the normal sludge from solder removal. Here is some more info, I had already processed maybe 120 sticks of ram over a couple of weeks (removed solder only). One the last batch I noticed that some sticks had loose fingers so I guessed that open air exposure and maybe the H2O that I used started a weak AP. Like I said this last time I just threw the whole sticks in and all was well for a day or so, then I decided to heat the stuff up. Got it to about 80C then when I opened it up there was the color. I have done a couple of tests with the caps in HCl and HCl / water, and heating and no color change, so I am guessing in AP we got something else. Also when I did notice this it was at night, as far I know it only started after heating, the bucket had been in the sun before that but no color. When I was referring to the silver I guess I should have said the super thin silvery looking sheets that are floating around in the solution. They’re pretty big (well for capacitors 1812 size), I am guessing when the end caps went away on the capacitors the layers came apart. I don't have any nitric yet, I am still early on in my experience so a small amount of it is all I need that that means it costs a lot for a little. I guess what I am going to do is go back to my original plan to keep everything separate and process them like I should do anyway.

 

[mjgraham]

Just to finish this off, the test I did after 3 days with the caps in HCl and in HCl and H2O, the HCL had a yellow layer at the top that went clear when I stirred it up, the HCl/H2O was slight purple, and i mean slight. My bucket of purple of HCl is now a milky green like you get when you wash solder mask away the memory sticks do look like the soldermask was attacked slightly.
Thanks everyone
Jarrid