How to unsolder silver solder from a component legs?

[M Philbrook]

I have been trying to remove a rectifier modual from an AC inverter
(Micro Master 440), for what ever reason, a very high temp solder was
used, Silver Solder.

MY solder rework station set at 900F just sits there on the solder blob
without even making a dent into it.

I have gotten a few legs usng wick and a large mass 120 watt iron.

the iron just barely softens it and thus the wick really does not get
it all.

So today I put my throgh hole heated 60 Watt vaccum pump desoldering
wond on there with a micro torch off the side of the tip to give it a
boost... The temp regularor in the station throdles back to that really
didn't help.

So I got out a old radio shack 40 watt desoldering tool with a hand
bubble on it, placed it on the lead and applied the micro torch to the
side of the tip, it was able to soften the solder enough to move the pin
around but not enough to really blow or suck the solder out, after all
that work, all it did was remove the surface solder but not in the via.

Yes, by all accounts, it is Silver solder, the stuff that normall
requires a torch to apply.

I assume they prepped the board using the silver solder paste and then
hit it with a super hot iron or something close to it.

Btw, I even tried a 300 watt iron which did soften it but the tip is so
large that I just could not do much with it.


Anyone got ideas in removing this rectifier moduale ?

I did think about cutting the the leads to the surface and drilling
them out but I think make cause a via issue because some of the legs do
have voids in them from where I was successful in removing some of the
solder..

Anyone have somke ideas?

[Jon Elson]

M Philbrook wrote:

>
>
>
> So I got out a old radio shack 40 watt desoldering tool with a hand
> bubble on it, placed it on the lead and applied the micro torch to the
> side of the tip, it was able to soften the solder enough to move the pin
> around but not enough to really blow or suck the solder out, after all
> that work, all it did was remove the surface solder but not in the via.
>
>

If you can get the solder to melt, then dilute it with tin/lead solder and
it will lower the melting point. Then, more traditional methods might work.

But, most of the components are likely trashed by the heat.

Jon

[Dave Platt]

In article <MPG.34e54c53b...@news.eternal-september.org>,

M Philbrook <jamie_...@charter.net> wrote:

> Anyone got ideas in removing this rectifier moduale ?
>
> I did think about cutting the the leads to the surface and drilling
>them out but I think make cause a via issue because some of the legs do
>have voids in them from where I was successful in removing some of the
>solder..

Try heating it up and applying some fresh, lower-melting-point
solder... 63/37 comes to mind, or even ChipQuik (which might be
excessively expensive for this). A drop of rosin flux, first, might
be a good idea.

There's a fair chance that the new solder, once liquid, will begin to
dissolve away the high-temperature silver, forming a eutectic whose
melting point will still be within the range of your iron or torch.
Vacuum-bulb away the eutectic, and repeat the operation to dissolve
the next layer of silver.

[pf...@aol.com]

Desperate needs call for desperate measures.

Cut off the unit using either a fine Dremel wheel, or a hand file.
Rinse everything with 99% isopropyl alcohol to remove the scarf.
Then remove the individual legs with a toothpick and enough heat - follow the suggestions using 37/63 solder - and a solder sucker.

And, with patience, there you are.

Peter Wieck
Melrose Park, PA