Stripping Sn/Pb solder from pins

[Spehro Pefhany]

Would it be an optionto machine off the sn/pb and Nickel, then
replate?

Cheer

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


Best regards,
Spehro Pefhany

 

[Spehro Pefhany]

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

-Lasse

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

 

[Boris Mohar]

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?

 

[Jim Wilkins]

For just a few, without a solder cup for wire ends, I would grip
them in a solder-free area with needle nose pliers or the like, dip
in
rosin flux and then in a solder pot to get it up to the melting
point,
and then strike the hinge part of the pliers against a wood block,
thus
flicking off *most* of the solder (but not all).

With solder cups, what I would do is grip it in some kind of pin
vise, and then heat with a soldering iron and either use a vacuum
solder
removal iron or use small braid soaked in rosin flux to wick up as
much
solder as possible.

DoN.

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

 

[Spehro Pefhany]

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.

 

[Jim Wilkins]

On Tue, 23 Jul 2013 08:48:49 -0400, "Jim Wilkins"


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.

http://www.electrochem.org/dl/ma/203/pdfs/2374.pdf

Solder dissolves gold plating quickly.
http://www.eng-tips.com/viewthread.cfm?qid=7370

jsw

 

[Syd Rumpo]

http://www.electrochem.org/dl/ma/203/pdfs/2374.pdf

Solder dissolves gold plating quickly.
http://www.eng-tips.com/viewthread.cfm?qid=7370

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

 

[Spehro Pefhany]

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.

 

[Lasse Langwadt Christensen]

They are embedded in ceramic insulation and I want to use them as plug

pins. They've been soldered to, so they're "ruined".

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

 

[Syd Rumpo]

How, and still be able to remove the solder?

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.

Is that your best Polish joke? ;-)

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

 

[Tim Williams]

Or, melt the entire pin off the connector. The melting point of
pure gold is over 1000 C! That is REALLY hot. White hot, and you
can't be near it without singing the hair off your arms, using
dark goggles, etc.

But, a small pot of gold would probably be worth several thousand
$ at the very least. One Troy ounce is a tiny little bead.

That said, you might be able to rub on some amalgam...

Don't forget to stick it in the oven for a little while so it doesn't
outgas mercury in the final setting ;-)

Tim

 

[amdx]

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

If you think all that is fun, read this and the comments to continue
the fun.
"How Not to Do It: Tertiary Butyllithium"

 

[Jim Wilkins]

If you think all that is fun, read this and the comments to
continue the fun.
"How Not to Do It: Tertiary Butyllithium"

I had my share of that fun with Lithium Aluminum Hydride. I was a
novice chemical researcher, the only undergrad in the summer research
program, so a wise and kindly grad student offered to chisel off a
chunk of the concrete-like mass for me, and set it all on fire with
the second blow. We just closed the fume hood door and enjoyed the
bright red fireworks display.
jsw

 

[Lasse Langwadt Christensen]

If you think all that is fun, read this and the comments to continue

the fun.

"How Not to Do It: Tertiary Butyllithium"

remember seeing that blog long time ago

this one is a really interesting read

http://pipeline.corante.com/archives/things_i_wont_work_with/

-Lasse

 

[rickman]

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!)

I always hated it when my professors would refer to a hydrogen ion as a
"proton". Sure that's all it is, a naked proton, but there is a world
of difference in terms of how it is considered. The LHC isn't trying to
etch glass or any other chemically mediated reaction. Likewise etching
circuit boards doesn't really demand the calculations performed when
setting up a particle accelerator. Very different worlds... so why make
it sound like they are merged significantly by using the nuclear term
"proton" instead of calling it a hydrogen ion. All the other atoms are
just clumps of protons and neutrons too, but we refer to their ions
as... well, ions.

 

[Spehro Pefhany]

I'd be interested to know how you finally solve this.

Sure, Tom.. it may be one of those things where I make my best
recommendations on how to do a top quality job and it ends up being
done differently for other reasons. There's a lot of $$ at stake.
Caswell has a gold brush plating setup for a quite reasonable price,
but everything involves some risk.