Be careful about IRF9610

[space2000]

Hi all,

This is my own test on IRF9610.

Pls be very careful about this mosfet. It is very much sensitive on soldering iron volt. I had spoiled 21 pcs without knowing that the soldering iron causing it. When you solder this mosfet, do not use cheap soldering iron or btr check the iron is not having any voltage on the body. The mosfets was internally short circuit. I have tested by only touching the new mosfets pin without to holding for long and checked that mosfets was shot circuited internally.

Thank you
michael

[Mooly]

Hello Michael,
Are you sure they are short. Do you mean Drain to Source ? FET's can read strangely if you leave the gate floating as you measure them. Try soldering a bleeder resistor ( 10k etc ) between gate and source and read again.
If they really are short you have been very unlucky --- get a new iron.
If you are soldering on any equipment that is plugged in to mains and earthed, even though it is off this can cause problems with some mains irons with high leakage currents.
Do check them again though

[DigitalJunkie]

I would suggest getting a grounded iron.

[space2000]

hi mooly,

i checked they are really shorted. this is cause by the soldering iron.
when i was making aleph-3, i used to use match pair for irf9610. once i solder them on the board and its gone. i thought my circuit has problem. Gate and source shorted so the voltage drained to the output directly. i couldn't fine any way out. sudden i was thinking, i just solder new pair, why like this? then i takes them off and put a like small ic base solder first, so before i power it, just place the mosfets, wow...its works great, no more problem. then i was thinking why cause this. i must find out. i used my one new IRF9610 and touch by the soldering iron not even one sec then tested and fund its shorted to the gate and source. so i confirmed and i test another one, still the same. so confirmed that soldering iron have problem. now i don't use that soldering iron. though i lost more then 21pcs irf9610 but i learned the lesson that i should.

best regards
michael

[Mooly]

That's a pity Michael -- all those FET's . When you are soldering on ANY equipment, it's worth making sure all the caps are discharged and that there is no other path to mains earth ( through phono leads / CD players etc ) . Bad luck on that one.

[flg]

I have never seen a soldering iron that is not either floating or grounded. However, it would be a simple task to make measurements with a meter, turned off or turned on, to find out the actuall situation.
I would like to suggest though that an ungrouned circuit board might develope an electro-static charge in an unprotected workspace. When you attempt to solder your grounded iron allows for a distructive electro static discharge

[Samuel Jayaraj]

I too have faced the same problem of shorted and distorting mosfets using a GOOT 2 pin soldering iron. Since I found out that a very high floating voltage was present in the body (I used a Line Tester to check), I have earthed the body using a wire wrap.

The safest bet is to use a 3 pin soldering iron and short all pins of the mosfet until soldering is completed. Remove the short soon after soldering is completed. Double check before powering up the circuit. I have rarely powered up amplifiers without removing the shorting wire on the mosfet pins.

[AuroraB]

Back in the 70s, when the first dual gate mosfets for RF arrived, they were a REAL PITA!!! ( no protection diodes )
We used to wrap a piece of thin solid wire around all the legs, or stick them through a pice of tin foil, before soldering...

[coloradosound]

Always try to keep the MOSFETs in a shielded (metalic color)
bag and on the black conductive foam until ready to use (install)
Try to use dissipative ESD mats, wrist straps, and 3 wire
(grounded) ESD safe solder iron. Finally, tie all those grounds to
single point (mat, wristraps, etc.) to same potential as solder
irons ground. Get's expensive to buy all that gear to protect
MOSFETs, but worth it.

[lineup]

Originally posted by space2000
Hi all,

This is my own test on IRF9610.

Pls be very careful about this mosfet.

It is very much sensitive on soldering iron volt. I had spoiled 21 pcs without knowing that the soldering iron causing it. When you solder this mosfet, do not use cheap soldering iron or btr check the iron is not having any voltage on the body.

The mosfets was internally short circuit. I have tested by only touching the new mosfets pin without to holding for long and checked that mosfets was shot circuited internally.

Thank you
michael

This also illustrates the importance of using GATE RESISTORS.
When using a resistor, maybe 1k for IRF610/IRF9610
or 220 Ohm for IRF240/IRF9240
and solder this resistor close to the MOSFET
we get some needed protection for static high voltage spikes.

Before you solder a such a resistor to the GATE terminal of MOSFET
be sure to get yourself unloaded = have same potential as your Solder IRON and the MOSFET.