Date:         Tue, 14 Sep 2004 04:52:30 -0700
Reply-To:     Michael Rule <manikmike@YAHOO.COM>
Sender:       Vanagon Mailing List <vanagon@gerry.vanagon.com>
From:         Michael Rule <manikmike@YAHOO.COM>
Subject:      Soldering Suggestions: General and for LED’s compilation
In-Reply-To:  <000f01c49a4f$027d5a80$6401a8c0@shadygrove>
Content-Type: text/plain; charset=us-ascii

Hi All,

Made a compilation of the suggestions/ help I rec'd for my "soldering
gauge" for soldering the LED's in our Vanagons... thought this might be
helpful for other novices to find in archives... wasn't sure if it's
proper to include peoples names and emails in this sort of thing (open
to suggestion tho).
Thanks to everyone who helped out!
Cheers,
Mike



Soldering Suggestions: General and for LED’s
-------------------------------------------------------------------------------

The gauge of the solder is not at all critical as the right soldering
iron. The spool of solder I use say "44" rosin core. A very wide range
of solder gauge will work just fine. Just be careful not to over heat
the PCB or else you may lift the trace.

As others has mentioned, the wattage and tip size is determined by the
job on hand. That is the heat dissipation and thermal mass of the
component(s) and the circuit board (or wire etc) in question. Too low
of
a wattage or too high a wattage are equally bad. I personally prefer a
slight hotter iron/tip because I can heat it up very fast. This way I
can minimize the dwell time thus least chance of lifting the trace.
Good
soldering take a lot of practice. A common poor soldering is oxidizing
the solder. The rosin is for cleaning the metal being solder as well as
to prevent oxidation so it is important to lift the iron before all the
rosin is vaporized.

The best solder iron for the modern surface mounted electronics is
heated by radio wave. They have incredibly fast respond time to
regulate
the heat regardless of the heat transferred during soldering. They are
however very expensive. I use a magnetically regulated iron with good
old heating element at home. The lowest cost irons are unregulated.

--------------------------------------------------------------------------------

In general, as long as the solder isn't too big for the job, the one
you are comfortable using is the right one. I would suggest a bit of
practice with single strand wire that is the same diameter as the led
leads. Radio Shack should have it.

That being said, for newbie solderers smaller guage is probably easier
to work with. Just remember to try to do the job without spending more
time than necessary to do it well. All semiconductors are heat
sensitive. Solder time vs. temperature is probably available on the
internet for any common part number. The led package may have
recommended solder times printed on it.

---------------------------------------------------------------------------------

If you're talking about printed circuit soldering, the smaller gauge of
solder is better because it's quicker to heat up & melt. Make sure it's
rosin core, NOT acid core. Yes, you want to use a small iron with a
small tip (like 1/8" dia.), but it's relative to the job at hand - it's
just as bad to try to use a wimpy iron because it takes too long to
melt the solder and get the "flow" you need for a clean joint. You need
a hot, well tinned tip which will transfer the heat quickly. If "well
tinned" doesn't mean anything to you, ask & I'll try to describe what I
mean.

One of the secrets is touch time. If you have to hold an iron on a
printed circuit very long, it's likely going to damage it. As someone
already warned, you can destroy the adhesive holding the print to the
board and cause it to lift. The copper will survive but now you have a
mess that's best left to an experienced tech to repair.

I don't have enough time to make more sense, but if the above sounds
complicated, it's really not, but it DOES take experience. If you can,
practice on something to get a good flow of solder and a good joint
without destroying everything in the process. Then you can have the
confidence to do what you need to do.

I certainly don't mean to be insulting but soldering PCBs (or flex
circuits) properly really is something which requires experience.
Fortunately, the VW stuff is relatively crude (ie, not "fine line") so
it's relatively easy to work on. It will survive some mistakes.

“I'm guessing well-tinned means well-covered w/solder?”
Yes.  And clean & shiny.  A good trick is to used a small, wet sponge
to wipe the tip frequently while you're using it to keep it clean of
sludge.

The more expensive soldering setups come with this sponge in a special
tray. Also, use the rosin-core solder to keep the tip well 'wetted'
while you're using it, and occasionally use the sponge to wipe off
charred rosin. The wet tip will provide maximum heat transfer to the
target metals so that the soldering action can occur quickly before the
heat rises in the surrounding areas & materials.  Immediately after
applying the wet tip to the target, also apply the solder to the tip
right at the target. The solder should begin melting immediately.  If
not, the tip may not be hot enough or is dirty.

As the solder melts, the target metals (LED lead and printed circuit?)
should simultaneously reach solder melting temperature and the liquid
solder will flow & wick smoothly into and round the actual joint.  At
this time, you can actually move the solder around in & around the
joint & see it melt & flow. It should not be chalky (temp not high
enough) but should flow as a thick liquid.  Once sufficient solder has
flowed, lift the tip and the solder away.  Again, timing is important.
Don't leave the heat on any longer than necessary.

If you examine pre-soldered joints on other electronics, you can see
what a good joint looks like.  Don't worry about some rosin left around
the finished joint; it's non-corrosive but you can clean it up with
alcohol & a small brush if you like.

In some cases, you may need to clean the target metals before
soldering, especially if they're old.  Like lightly scraping the LED
leads or the mating PCB areas.  Dental picks, exacto knives or similar
tools can be useful.  You want bright metal before trying to solder.
Also, in some more difficult cases, it's advantageous to tin or re-tin
the mating surfaces with solder before actually joining them (being
careful not to fill holes).

Once tinned in this manner, the parts should solder together very
quickly & easily. Note that the word "tin" here refers to solder even
though tin is just a part of the solder alloy.






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