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Author Topic: Soldering large leads  (Read 634 times)
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Ireland
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I need to solder some Allegro 756 current sensors to PCBs. The current-carrying leads have a fairly hefty rectangular cross-section, and are designed to be soldered to relatively huge solder pads.

The obvious problem I'm facing here is trying to heat the lead and pad up sufficiently to achieve a decent solder joint without damaging the board or IC. Does anyone have any pointers for techniques that might make this job any easier? I'm not a particularly experienced solderer, but I can manage the regular-sized component leads quite well. I have a temperature-controlled soldering station and I'm using lead-free solder.
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Austin, TX
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There are two ways to create a good joint:  1) Increase heat flow and 2) Reduce the melting point of the solder.

By adding Flux, you'll increase overall heat flow which will help to reduce the amount of time you need to keep heat applied.  Switching to lead-based solder means a lower melting point of the solder itself.
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Ireland
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Thanks, James. I have liquid flux in an applicator pen, and I also have some lead solder, so I'll have a go with a different soldering iron (don't want to "contaminate" the lead-free iron) and see how it works out.
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If you have a larger soldering iron tip, use it! If not, get one!

Higher heat is not useful without higher thermal mass that can transfer that heat to the joint: a bigger tip.

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Manchester (England England)
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Quote
don't want to "contaminate" the lead-free iron)
Why not you are not a factory having to conform to stupid regulations. Are you victim of the "lead solder is dangerous" delusion.
Lead solder is perfectly safe and produces more reliable joints, why do you think there is an exception for military and medical use?
The only potential issue with lead solder in mass consumer devices centers on the disposal and rotting in land fill of large amounts of solder and even their the legislators have a lot of muddled thinking. Lead in petrol was several million times more dangerous.
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North Yorkshire, UK
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Yeah I have some of these sensors smiley

I just tinned both connections, put a small amount of solder on my iron, held it to the connection and pushed in loads of solder.

The chisel tip iron is probably the thing that made it easy though.
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You could also try using a hot-plate.

(* jcl *)
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You could also try using a hot-plate.

(* jcl *)
For TH?
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I wasn't sure if the part was TH or SMD.

(* jcl *)
« Last Edit: June 02, 2011, 06:07:00 pm by jluciani » Logged


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Ahh I see smiley

You can get bent ones for PCB TH or straight ones probably intended for simply soldering leads onto (what I have and what I've done)
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