I am replacing some igbt transistors on a circuit board from my Samsung TV. While de-soldering one of the 4 components one of the traces from the gate lead fell off.

I am looking for the best practice to solder the gate of the transistor into the broken trace.

Option 1 would be to sand or use a solvent to remove the remaining insulation from the trace. This would expose enough area for me to solder the transistor gate.

Option 2 would be to use a small wire and solder onto one side of the surface mount resistor to connect the gate.

The black areas around the board are from some insulation that was glued to the board (not heat and burn marks).

I am open to suggestions.

enter image description here


Repaired Board

Update: It took 2 weeks to have the IGBT transistors shipped from China. I used a piece of 26 AWG wire to replace the lost trace.

  • 1
    Indeed going to the resistor will be easiest. But it's not possible to state what is most appropriate without knowledge of the circuit. IGBTs tends to imply fairly high voltage, and things like sharp points that can arc start to need consideration - note that isolation groove routed in the PCB. There's also the question if replacing the transistors is even viable- there may be a reason the existing ones failed. – Chris Stratton Oct 22 '17 at 0:01
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    I recommend next time you desolder a commerical PCB, re-solder it first with SnPb38Cu2 solder. With the "smearing" liquid/solid intermediate of the eutectic, pulling multiple pins at once is much easier than with pure Sn100 solder. – Janka Oct 22 '17 at 0:29
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    As Chris says there is high voltage on those transistors- the slots in the PCB tell us that positively. Make sure you clean all that crud off the board and inspect it properly before you power it up. – Spehro Pefhany Oct 22 '17 at 2:22
up vote 2 down vote accepted

Rework wire to the nearest component on the same signal line is always your best bet, soldering onto traces can be problematic and is not mechanically sound.

The normal solution is option 2

Proper vacuum pumped soldering iron can prevent damage in future.

Respect the board air gap to prevent surface hi voltage breakdown to gate.

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