Soldering Technique

[rymac]

I'm trying to fix cold solder joints on a fender Blues deluxe circuit board.
I have a 35 watt weller iron. I heat the trace and resistor lead. Apply solder.
Solder flows. I remove iron. Solder is shiny. It cools in a few seconds and turns grey. What I'm i doing wrong?? Solder is Kester "44".

This amp has been a pain to work on and has had so many problems. I'd love to set the chassis and it's circuit board guts on fire.
The tweed cabinet looks nice but other wise flame on.

[Mark Black]

I've run into that before - I think it's probably the lead-free solders & different fluxes manufacturers are using these days. In my experience the best solution is to suck all (or at least the majority) of the old solder off first, then retouch with new solder.

Kind of a pain, to be sure...

[olddawg]

Wick it clean. Scrub the area clean with solvent. Apply liquid flux with a small brush. Then solder.

[jrfrond]

The lead-free RoHs-compliant solder is what is doing that. This solder looks like shit right out of the factory, and looks do not lie. It is brittle and crappy, but it's the law. It is mainly tin.

You can wick it off and resolder with you Kester 44 stuff, but as long as you are alloying some lead into the mix, the joint will be fine once touched up.

For the record, we've seen an acute rise in solder failures since RoHs compliance took root.

In case you don't know what RoHs compliance is, here is an article I wrote for the 300Guitars website:

http://300guitars.com/index.php/arti...-to-musicians/

[Enzo]

I bought a fresh pound of real solder just a week before the prices all doubled or tripled. YAY.

[gbono]

Lead free

Lead was added to solder to prevent tin (Sn) dendrites from forming over time. If you have ever used silver (Ag) solder in a humid climate you get the picture. I'm guessing that the consumer will be the one to pick up the cost of all the failures that are coming in the future.

BTW the EU ROHS directive excludes fluorescent lights from the requirements. I guess a little mercury is okay.

[jrfrond]

Lead was added to solder to prevent tin (Sn) dendrites from forming over time.

aka "Tin Whiskers". Google it. It's pretty cool and frightening at the same time.

Medical, Defense and Aviation industries are exempt from RoHs specs due to reliability issues.

[drewl]

Yes I've found that new stuff to be a pain to work on.
So, will they stop making the "good stuff"?
I sure hope not!
At least we have dozens of spools at work.

[tubeswell]

Yes I've found that new stuff to be a pain to work on.
So, will they stop making the "good stuff"?
I sure hope not!
At least we have dozens of spools at work.

As long as critical sectors require the good stuff I don't think they'll stop making it (in fact if its got 'military grade' stamped on it, it might even improve over time - if you can improve on leaded solder that is ;-)

[jrfrond]

As long as critical sectors require the good stuff I don't think they'll stop making it (in fact if its got 'military grade' stamped on it, it might even improve over time - if you can improve on leaded solder that is ;-)

Improvement + Mil-Spec = $$$!!!

Rework by non ISO-certified shops does not require the use of RoHs-compliant solder and parts.