Heavy Duty Soldering

Those will work, but I prefer the pistol-trigger Weller soldering guns for heavy-duty stuff. The gotcha with these is that it's real easy to overheat a PCB and cause the foil to pull off. That's also a problem with underheating too, if you've got skinny traces in particular.

Tim.

Everbody tells me that the skinny metcal tips can pump out that much heat, but I never believe them :-).

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. Robert

For heavy soldering, I use a 60 Watt, and a 100 Watt iron. For general circuit board use, I have a proper soldering station.

If the soldering job is demanding more than what I can accomplish with an iron, I then use a soldering gas torch.

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Jerry G. ======

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.

Robert

Maybe a solder pot (or a wave if you can pick one up for a reasonable price). The latter have almost infinite ability to transfer heat to the material. I picked up a small wave (without conveyor, preheater or fluxer) for a couple of hundred dollars including a thermocouple temperature controller. Well, I didn't actually pick it up, it weighs about 80kg/175 lbs.

Best regards, Spehro Pefhany

I've done similar with a broad tip on my metcal.

If you are not talking about production, but just one or two, you might try using an oven to preheat the whole thing before soldering. I think I would flux the joints before preheating to prevent oxidation. Even working on an insulated (wooden) surface under an infrared heat lamp may help a bit. Let the assembly sit there under the lamp until it is too warm to touch and then try soldering. Just using a bigger iron is more likely to damage the board with hot spots.

And fast enough not to heat up the rest of the board too much.

I actually tried that, I've an old tip and it needs replacing but even with a new tip I think it would be marginal at best. It can heat up solder to the melting point at the tip but not enough to flow it around the pin. The bus bar and the Cu plane appear to be enough to draw the heat away on the larger bus bars. The smaller bars I can just do.

The bigger Bus bars have more pins and an larger associated area for both the Cu bar and the Cu Plane they connect to.

Robert

That's an interesting thought. The production units will probably be wave soldered in any case. Anyone have any pointers as to where I might find one (either commercially or local to Ontario, CA)?

I'll probably keep my eyes open for one even if I don't use it for this project.

Thanks Spehro

Robert

Well remember it's more than just the pins (they just run from the bus bar to the PCB), there is a fairly extensive Cu plane to connect to and the Cu bus bar itself has a fair amount of thermal mass and radiant area.

I can almost do it with either a Weller Pistol type or my smaller pencil soldering iron. In fact I can solder power pole connectors on the Cu bars, but once I add the extra load of the Cu plane on the PCB...

Thanks Tim.

Robert

Robert, I've used a soldering gun with 2 electrodes made out of solid wire. Flatten the business ends into sort of a squared off chisel, ~1/4" gap. Then make an electric contact in the area you need to solder, sparks a lot but heats the area you need nicely. I've used this for rechargeable battery pack reconstruction. Faster and you don't have to wait for those large irons to heat up. Richard

I use an Ungar 45W 1050F pencil with 3/8" tip. Lots of theremal mass. If that don't do it, I preheat the opposite side with a heat gun. I've had poor luck with soldering "guns" on items with lots of thermal mass. mike

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I use a hot air gun to preheat the assembly. You can also place the assembly on a hot plate (commercial unit for surface mount rework or a portable single burner stove with an aluminum plate to act as a heat spreader). If you get the parts up to 150 to 180 deg C, that will help alot. A pair of irons is always helpful in stubborn cases.

Mark

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

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.

I've used an "open circuit" solder gun for stuff like this. I replace the normal tip with two solid copper #10? flattened to two chisel points with about a 1/4" gap. When contact is made, sparks and the area contacted heats up nicely. I've used this to repair NiCad packs. Does that "cold" soldering thing on TV work like this? Of course you wouldn't want to use it around sensitive components. Richard

I use an soldering gun with 2 solid copper #10? flattened chisel points and a 1/4" gap. I discovered this trying to make a mini spot welder. Works well on reattaching NiCad tabs. Not good around sensitive electronics. Richard

Robert,

Did you try preheating the assembly with a board preheater or a hot air gun? The larger Weller D650 (300W/200W) might also do the trick.

I wonder why wouldn't you guys just use a bigger iron? Not a soldering gun, their Watts are of that Chinese variety that they manage to squeeze 2x1000W into a tiny boombox...

Just use a normal 100 Watt soldering pencil. Works miracles on big jobs...

I personally use MCM Electronics 100 Watt iron, their item # 21-4350. Works like a charm, no problems soldering even a box made of 1/16" thick copper...