Heavy Duty Soldering

[CWatters]

The problem I have is that with the iron I'm using at the moment the
combined heat sinking of the Cu plane and the Cu bus bar is too much

I posted this awhile back but haven't seen it appear so...

If you aren't likely to do much on this scale in the future you could try
what the did years ago - make one from a lump of copper and heat in a gas
ring.

 

[spudnuty]

Hi,
In the past I've used a soldering gun with the tip cut off and a ~1/4 "
gap between the electrodes. Then touched the electrodes across the
workpiece firmly and applied power. Can solder a 1 oz piece of steel
plate in about 15 seconds. Sort of like a mini spot welder. Works great
for rechargable fixes. It might be a bit small for that big copper
plate but there are bigger guns and you get the idea. Unfortunately
those big irons are great for this kind of stuff, thats why roofing
guys still use them.
Richard

 

[spudnuty]

Hi,
In the past I've used a soldering gun with the tip cut off and a ~1/4 "
gap between the electrodes. Then touched the electrodes across the
workpiece firmly and applied power. Can solder a 1 oz piece of steel
plate in about 15 seconds. Sort of like a mini spot welder. Works great
for rechargable fixes. It might be a bit small for that big copper
plate but there are bigger guns and you get the idea. Unfortunately
those big irons are great for this kind of stuff, thats why roofing
guys still use them.
Richard

 

[Glenn Gundlach]

Tim, you would be pleasantly surprised.
GG

 

[spudnuty]

I've used a soldering iron with the tip cut off and a 1/4" gap between
the electrodes. This was originally an attempt at a mini spot welder
but worked well for soldering NiCads for renovating battery packs. It
might be small for your application but maybe you could find a really
big gun. It can't be used on parts that are sensitive to current. BTW
those big irons are still a good bet . Guys putting in copper roofs and
gutters still use them.
Richard

 

[R Adsett]

Did you design in thermal relief on the connections to the Cu plane?

Good question, It's an inherited board so I had to go back to the gerbers
to check. The answer is no (another thing to look at changing on a board
revision). Also there are four 3 oz Cu planes sitting atop one another
in the board stack. Granted FR4 is an insulator but that's going to have
some effect.

Robert

 

[R Adsett]

If you aren't likely to do a lot of this in the future you could try what
they used years ago... eg a block of copper heated in a gas ring. You might
find that some scrap bus bar folded up has sufficient thermal mass.

My bigger problem may be finding a gas ring . My last resort though is
to heat up the bar with a torch.

Robert

 

[R Adsett]

Tim, you would be pleasantly surprised.

By what?

Robert

 

[R Adsett]

I've used a soldering iron with the tip cut off and a 1/4" gap between
the electrodes. This was originally an attempt at a mini spot welder

Hmm, essentially turn the busbar into a soldering tip. I might play with
this just to see what it will do.

BTW Richard, Your replies appear to repeat themselves multiple times.

Robert

 

[Mark]

Weller Tempmatic 150 Watt with thermostatic controlled tip.

the thermostadt contol is the key, it provides feedback, the more
heat you take out the more it puts out to keep the temperature at 700
deg C

on page 17 here

http://www.hollanderglass.com/texas/catalog/g_tools.pdf


and other places


Mark

 

[Sergey Kubushin]

There is no replacement for displacement )

Keeping the tip temperature constant does NOT help soldering big objects.
The problem is a big copper bar not only does conduct heat, it also
dissipates it. There is ambient air and lot of other stuff that makes the
temperature drop along the bar as you go farther from that thermocontrolled
tip. And keeping a point at the bar at a constant temperature does not help,
it makes things worse.

The only way to do such a heavy duty soldering is to use a proper soldering
iron. With a powerful constant heater and massive copper tip. Solder guns
are NOT suitable for such a job. If a job requires a sledgehammer there is
no way to replace it with a small jeweler's hammer no matter how technically
sophisticated it is...

Don't waste your efforts, use a bigger hammer )

 

[Rene Tschaggelar]

I have an assembly that uses Cu bus bars 1.55 mm thick connected to a 3
oz Cu plane on PCB via through hole pins 1.5mm wide. So that gives pins
about 1.5 mm sq.

The problem I have is that with the iron I'm using at the moment the
combined heat sinking of the Cu plane and the Cu bus bar is too much for
the iron to overcome. I'm looking for something that would be
appropriate. I've used American Beauty heavy duty Irons in the past for
similar purposes but I'm wondering if any one has other (perhaps better)
suggestions.

Nuts and bolts ?

Rene

 

[R Adsett]

Nuts and bolts ?

Rene

That's the way I've often done it in the past. In this case though it's
an inherited design and would need an extensive re-design for that to
work.

Robert

 

[Rene Tschaggelar]

That's the way I've often done it in the past. In this case though it's
an inherited design and would need an extensive re-design for that to
work.

There are selfthreading metal screws that can just
be tightened....
Possibly better than heating square inches of copper.

Rene

 

[R Adsett]

There are selfthreading metal screws that can just
be tightened....
Possibly better than heating square inches of copper.

Rene

Still not enough room. I've just got a little more than enough room for
the ~1.5 mm Sq pins of the Bus Bar, think of it as a rather large SIP.

Of course with self threading screws there also comes the worry of metal
fragments shorting out the rest of the circuit. Thread forming rather
than thread cutting helps on that.

For anyone who's still following along at this point I determined that
two irons together (well an iron and a gun) work quite effectively at
flowing the solder without overheating the rest of the board so I expect
that a large iron will as well. Three handed soldering is a bit beyond
my dexterity so if I need to do any before I get the larger iron I'll be
reduced to building up cold solder balls around the joint and then
applying the two heat sources at once.

I quickly tried the Weller with snipped tip forming a gap but without
much effect.

I'll be getting a large iron and keeping my eyes open for a cheap solder
pot/wave.

Robert