Stripping Sn/Pb solder from pins

dependsin why you need to but, how about putting the parts in machined gold plated sockets and solder from top inside only?

-Lasse

Although, HCl and H2SO4 are astonishingly slow when it comes to nickel. The stuff is pretty much noble (hence its popularity!).

Acidity alone doesn't determine corrosivity: if a complex is formed, metal will dissolve much faster. Copper dissolves faster in HCl + H2O2 than H2SO4 + H2O2, because it forms a green chloride complex (there is also a reduced form with a deep brown color, which is probably familiar to anyone who's used this brew to etch PCBs), while sulfuric basically does nothing special with copper.

Hydrofluoric acid isn't actually very strong, but because it forms a complex with silicon (hexafluorosilicate), it's one of the few chemicals which dissolves glass.

Oxidation potential is, of course, a big force. Electrolysis can beat the pants off any chemical, for obvious reasons. (There's literally nothing more "acidic" on Earth than the LHC -- one definition of acidity is "proton donator", and a naked proton beam at ~light speed can't really be stopped from "donating" to anything!) Among chemicals, this means zinc dissolves faster than iron faster than nickel, while copper pretty much doesn't at all (in acidic water alone). If you add an oxidizer (nitric acid, H2O2, hypochlorite, etc.), less energy is spent generating hydrogen and more doing the reaction. (Bubbling decreases or stops when an oxidizer is used, unless another gas is produced -- nitric usually gives off NO and NO2 fumes, nasty things.)

There is, of course, no chemical which is a stronger oxidizer than fluorine, which will literally burn through anything on the periodic table besides pure oxygen and the noble gasses (which, except for helium and neon, are all known to form compounds with fluorine anyway, they just take some persuading).

Tim

'Sugar of Lead' (lead acetate) gives a sweetness to wine which had oxidised. Just hang some lead in your wine and banish that vinegary taste!

Cheers

I would try polishing the solder off, first having removed excess with solder wick and flux. Maybe make a tool for a Dremel comprising that thick polishing felt but with

How do you propose he prevent ESD damage?

Connect the pin to ground, I suppose.

If you can't, make sure your polish is a bit conductive, maybe add some water if necessary and ground the Dremel if it's floating.

I actually grew up near a polish club. It was years before I realised that it was in fact a Polish club.

Cheers

Lloyd E. Sponenburgh schrieb:

Hello,

I think the applied voltage is more important than the other electrode material.

Bye

As far as polish clubs go, I am sure it was a shining example.

Yup. Possible. I expect the pins are something like Kovar, can find out.

Best regards, Spehro Pefhany

They are embedded in ceramic insulation and I want to use them as plug pins. They've been soldered to, so they're "ruined".

Best regards, Spehro Pefhany

Sand blast it off with baking soda?

As an electronic lab tech I second all of that. If the assembly is too large or delicate to knock off the liquid solder, wiping it with a wadded-up dry paper towel works well too.

If you hold the pin vertical and heat it from the bottom with an iron, most of the solder will flow down onto the hot tip. Hit the pin with a vacuum solder sucker as you pull the iron away. The tip of the sucker will recoil into the pin when the plunger springs back so whatever supports the work should be fairly substantial. jsw

I can get the pins relatively clean pretty easily. The goal is to have nice shiny gold plated pins again, like new, so they can be used as contact surfaces.

Right now I'm thinking mechanical abrasion to get down to the bare metal (which is relatively hard) then nickel plate, then gold plate.

Solder dissolves gold plating quickly.

jsw

Of course, there is that approach. Dip the pins first into a pot of molten gold to dissolve the Pb/Sn, then in another pot of clean molten gold to re-plate. You'd need a nitrogen atmosphere, I think, so you're already 80% there, and the pots of gold can be supplied by leprechauns.

Sláinte

Cost aside, I think the molten gold might cause the ceramic to crack.

How, and still be able to remove the solder?

Is that your best Polish joke? ;-)

if you put sockets on the pins reheat the solder, the socket pins now become your new gold plated pins

kinda like a crown for a tooth

-Lasse

This is Angels on a pinhead territory, but assuming there's no access to other parts of the circuit and it's, say, an impenetrable DIL module, then we could wrap some thin wire around the pins near the module. No, we couldn't remove the solder right next to the module, but I won't tell if you don't.

We don't really have Polish jokes in the UK, and only really know of them through US TV program(me)s. However, they're just recycled Irish jokes, which don't really happen here any more, because they're usually just boring.

Cheers