From: Gary Coffman <ke4zv@bellsouth.net>
Newsgroups: rec.crafts.metalworking
Subject: Re: soldering
Date: Thu, 21 Oct 1999 11:00:27 -0400

On Wed, 20 Oct 1999 21:57:57 -0700, Eastburn <oldtree@pacbell.net> wrote:
>One thing people forget about - you want to get on - melt solder - get off now.
>You don't want to sit and wait for the iron to recover.
>The physical mass of the iron must be up to the task.

Or it must be a Metcal. :-)

(Microwave heated iron for those who don't know. It can
maintain tip temperature on a tiny tip to within a couple of
degrees, pretty much regardless of the sink to which the
tip is touched. The "cord" is really a waveguide, and the
power supply is ludicrously expensive.)

>The Am. Beauty - wonderful cloth wrapped with a stile yellow thread - the big
>ones have heads about the size of your fist.  The tip might be smaller but the
>massive copper heat sink is ready to dump heat.

Yep, about as good as a copper heated on the stove, and you don't need the
stove. Mine is 300 watts, and about 4 pounds of thermal mass.

>For fine work - 0.04 mm between center IC's - use hot air.  but then you know
>that if you had them. :-)

Right. Static hot air is the way to go. (Well you don't actually want to use
*air*, hot oxygen is incredibly corrosive.) Static hot air sources either use
an inert gas, or the diluted exhaust from a combustion torch, which is
naturally depleted of free oxygen. I use the Weller Pyropen Jr. It fits in
your shirt pocket, is relatively cheap, and makes a wonderful SMD
rework station when coupled with a jeweler's loupe and some bits of
modeling clay to form heat dams (yes, a tinker's dam).

You don't need a $3,000 tool to do quality SMD work, in fact its often easier
if you don't have one. (When you have a rework station, the tendency is to tear
the equipment down so you can put the board on the stage. With the Pyropen,
you can often do the repair without bothering to disassemble the unit. Saves
time and money.)

Gary
Gary Coffman KE4ZV  | You make it  |mail to ke4zv@bellsouth.net
534 Shannon Way     | We break it  |
Lawrenceville, GA   | Guaranteed   |

From: Gary Coffman <ke4zv@bellsouth.net>
Newsgroups: rec.crafts.metalworking
Subject: Re: soldering
Date: Fri, 22 Oct 1999 12:04:58 -0400

On Fri, 22 Oct 1999 04:35:40 GMT, mulligan@advinc.com wrote:
>In article <vyYPOJwJFdEH8nK+o0L8lm6T=1j=@4ax.com>,
>  Gary Coffman <ke4zv@bellsouth.net> wrote:
>
>> You don't need a $3,000 tool to do quality SMD work, in fact its often
>> easier
>> if you don't have one.
>
>What's the big deal with surface mount stuff?  I just use a weller
>magnastat iron.  We've tried all the fancy temperature controlled
>irons, but they just don't last.  A half year at best then something
>goes wrong.  I have a 5-year old magnastat iron on my office bench
>and aside from a new tip every once and a while it just won't die.

I have a couple of WTCPN units myself. Great irons for thru-hole
work. But I won't even bother to turn one on for surface mount.
The advantages of static hot air are just too great. The problem
with any iron is that you have to align the part precisely, the part
tends to stick to the tip, and you *do* need good magnification to
make sure you're only soldering one pad, and not bridging several.
With static hot air, the parts stay put, and self-align on the pads
due to the surface tension of the solder (I use silver bearing solder
paste applied *sparingly* to the pads with a toothpick) when you hit
them with the static hot air. It's a beautiful thing.

>I do all my surface mount stuff freehand, under a microscope.  Not
>really high volume producion, but it gets done.  I do have one of hte
>larger Pyropens and its a real fun tool for field work.  Never
>tried the jr one - is it as good?

Jr is great. The big Pyropen is fine for putting PL259s on outside
in the wind, but it is too big for most SMD work. Jr is just the right
size. It can handle the little grain of salt size parts and the bigger
PLCC parts (though the really big ones, 168 pads or bigger, do
need a bit more whomp than Jr can supply). You can put a tip on it
and do thru-hole work with it too, but mine normally sports an air
shroud because it is my primary SMD tool. For the 168 pin chips,
I use a regular Bernz-O-Matic torch (very quickly). Trying to solder
one pad at a time with SMD is an exercise in futility.

Gary
Gary Coffman KE4ZV  | You make it  |mail to ke4zv@bellsouth.net
534 Shannon Way     | We break it  |
Lawrenceville, GA   | Guaranteed   |