i ramdomly broke my mosfet by tin some solder on it.

gunoru · May 11, 2024

I got 30 IRH8343 (as recommended in the Picofly manual) MOSFETs on AliExpress.

I decided to use them.
Initially, the D and G were insulated as they should be for MOSFETs.

But after tinning them with some solder, they seemed to begin breaking since the D and G are now short-circuiting with some resistance (25 to 1.25 k ohms).

Now, I've broken 10 out of 15.

Does anyone have an idea of what's going on?

urherenow · May 11, 2024

a MOSFET, no matter how many pins it has, has 3 important things: Source, Drain, and Gate. If it has more than 3 pins, then there are multiple source and/or drain pins. As long as the pins that are shorted are of the same type (but there is usually only 1Gate pin), then the short does no harm at all. Many installers will short the multiples on purpose, even. If you're measuring before tinning, and getting these results after tinning and before trying to solder it to the board, then I have to question the type of solder you're using and how much heat, as well as exactly what you're doing/using to hold them steady. Simply tinning anything shouldn't break it. Even if you shorted it, but never pushed a meaningful amount of current through it. And it's super easy to fix a bridge. But... 25 to 1.25k ohms is definitely NOT a short. Less than 1 ohm is a short.

The first thing you should do before using a meter on a MOSFET, is to short the Gate and Drain pins. THEN you can check continuity between Source (black probe) and Drain (Red probe), and it should give you an OL. If you leave the black probe on source, then touch the GATE pin with the red, and move it back to the Drain pin, you will have some sort of continuity. That means it's good, not broken.

gunoru · May 11, 2024

urherenow said:
a MOSFET, no matter how many pins it has, has 3 important things: Source, Drain, and Gate. If it has more than 3 pins, then there are multiple source and/or drain pins. As long as the pins that are shorted are of the same type (but there is usually only 1Gate pin), then the short does no harm at all. Many installers will short the multiples on purpose, even. If you're measuring before tinning, and getting these results after tinning and before trying to solder it to the board, then I have to question the type of solder you're using and how much heat, as well as exactly what you're doing/using to hold them steady. Simply tinning anything shouldn't break it. Even if you shorted it, but never pushed a meaningful amount of current through it. And it's super easy to fix a bridge. But... 25 to 1.25k ohms is definitely NOT a short. Less than 1 ohm is a short.

The first thing you should do before using a meter on a MOSFET, is to short the Gate and Drain pins. THEN you can check continuity between Source (black probe) and Drain (Red probe), and it should give you an OL. If you leave the black probe on source, then touch the GATE pin with the red, and move it back to the Drain pin, you will have some sort of continuity. That means it's good, not broken.

thakyou sir i will try to understand what you say with a time.

now i have to recheck my mosfet again.
this may issue about charged/discharge.

fyi.
i use 220 degree with normal 60/40 tinlead
solder wire. the real temperature is as small as it can meal.

urherenow · May 11, 2024

That's a fairly low-melt solder, and temp. There's no way you damaged the MOSFET just by tinning it.

i ramdomly broke my mosfet by tin some solder on it.

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