[s-cars] Re: Proper Solder Technique?

[Edwin Foo]

Well, I might be able to help on this for once:

> Sorry to add a seemingly trivial question, but I have...uhmmm... been
> working on my iPod install which has required a bit of soldering for an
> in line amp I have chosen to add.  So, soldering is a skill I believe
> could be real usefull.
> As always I can hack my way through it, but what is the right way to do
> it?
> Whats a "good" soldering iron?

MetCal is the best out there. Weller is "good". The real good ones have
temperature controlled, interchangeable tips. Do not get the cheap
$10-20 ones. You probably ought to spend at least $50 to get a decent
iron if you'll be doing work on printed circuit boards.

You want an iron that has a high enough wattage to quickly heat up the
area you are soldering without burning the components around it. Shoot
'n scoot, so to speak.

You can easily spend upwards of $500 though, so don't go nuts in the
online store. :)

> Whats proper electrical solder?

multicore solder. flux content % should be on the roll. flux cleans the
metal and preps it for contact with the actual solder. However, flux is
a bit of a crutch; proper tinning technique (see further down) is better
than using lots of flux.

> Whats a good way to hold the parts together while soldering?

not your fingers. :) use helping hands (basically two alligator clips on
a stand) or tape the wires down on a board with 3M kapton tape
(non-conductive).

> What are the proper soldering techniques?

1) melt some solder on the tip of the iron
2) wipe the iron on a wet sponge and get rid of the excess solder so you
have a thin film on solder on the iron
3) melt a little more solder on the iron. this is what transfers heat to
the parts
4) place solder tip on *both* parts being joined.
5) wait for solder to get shiny, then run into the joint. you should not
need to "help" the solder move. If it is ready, it will move on its own.
6) remove iron and keep parts still while they cool.
7) go to step 1 and repeat

Soldered joints should look shiny when they cool down. If it is dull in
appearance then the joint is probably a "cold" joint and will likely
fail prematurely.

Tin the ends of the wires first. Basically, melt some solder onto them
and coat the exposed ends in solder, then only try to join the two
parts. That works for parts that would otherwise take a long time to
heat up and endanger surrounding components.

Take frequent breaks. The smoke and concentration will get to you after
a while.

Hope that helps.

Edwin