Indium solder

Right after posting I looked at the magnified picture. It's tin/lead and Indium is the company name!

Still a good price.

Regards,

Boris Mohar

Got Knock? - see: Viatrack Printed Circuit Designs (among other things)

void _-void-_ in the obvious place

It expires at 3 yrs old, does that mean I shouldn't eat the 28 yr old solder I use? :-)

Mikek

Kester 44 still rules.

And yeah, In solder is expensive. OTOH you don't need much.

Cheers

Phil Hobbs

How much do you need? I've got a foot or two of indium wire, maybe in some other form too. (mostly left over from low temperature 'pressed indium' seals.)

George H.

_READ_ the label; the solder is NOT indium, it is Sn63 Pb37; it is made by Indium corp.

Yes, one can buy their indium solder from Indium.

why does one need indium solder?

It solders at low temperature, doesn't eat gold plating, wets glass and ceramics as well as metal, and stays soft enough at room temperature to stand a lot of thermal cycling while remaining a hermetic seal.

On the minus side, it corrodes easily and is very expensive.

Cheers

Phil Hobbs

I cracked pieces of Si wafers, and made contact to the edges with bits of wire and indium. It's great for low temperature seals. My lab's prescription, called for a clean layer of indium and then a smear of vacuum grease. (grease is not good for UHV.)

George H.

Gallium wets glass too, (I think). I never tried soldering with it.

George H.

Yes, it does. It liquefies in the palm of your hand, though.

Cheers

Phil Hobbs

It also eats aluminium, amongst other metals.

It's fun to play with, however.

Right, I bought a big piece for my daughter and I to play with. I came into the kitchen and found her hands all stained. Pieces then went into a zip lock bag.

I guess a solder that melts at ~30C is not all that useful.

George h.

If it wets glass and ceramic then does it wet bare FR4 or the shellac coating?

After desoldering and re-soldering, does the trace amount remaining create a corrosion issue?

Not in my experience.

Re-soldering with what?

Cheers

Phil Hobbs

Silver or tin/lead. (Probably the latter since melting silver must be a problem if the indium was needed.)

Yes, it easily forms gallium oxide which makes your hands black. It is not poisonous or anything (thus safer than playing with mercury!), but that black stuff spreads /fast/ when the kid touches their clothes, the wall, the bathroom sink, etc. Having discovered this the hard way, we play with gallium outside and have a bucket of warm soapy water at hand (or use disposable gloves).

Below that temperature, gallium is surprisingly strong. You might expect it to be soft near its melting point, but it is entirely solid. So you can make a realistic teaspoon from it to surprise your friends when they try to stir their tea...

Do you stop them before they drink it?