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 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
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
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
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
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
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
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
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.
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.
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.
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.
space2000 said:
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.
I've been playing with MOSFET amps and a few other various circuits since about 1980. For the past 8 years or so I've been involved with SMPs. All MOSFET. All that experience except for the last couple years was in Phoenix, Arizona. For those of you who don't know, Phoenix is in the southwest USA desert where the humidity rarely goes above 10%. And, the lab I worked in last was carpeted. Sure death to the gate oxide of a MOSFET without proper handling.
I've seen, or caused, 100's of burned up MOSFETs. Sometimes on purpose. I would guess less than 5% of them where blown by ESD Or, what would be seen as a shorted Gate - Source. And generally when that happens the drain to Source is not shorted. A shorted D-S is ussually caused by excessive D-S current burning the channel permanatly. Of coarse voltage greater than the BVdss of the device would also cause a shorted D-S but we ussually choose a device with a higher breakdown than the circuit would ever be able to put across the MOSFET. An ESD incident however, overcomes the thin oxide (the O in MOSFET) which forms the gate to channel dielectric with greater than 20V typically causing a conductive path to the channel and no more gate capacitor or enhancment action. There are other somewhat typical situations like oscilation, etc. that might cause failures also.
I'll be honest, I don't wear a wrist strap unless I'm working on someone else's equipment, working at home where I use no other ESD controls whatsoever. In the last year or so, I've handled 20V-30V vertical MOSFETs 5 days a week and I still have not noticed much of an increase in G-S shorts that I could'nt attribute to the driver or a failure of the circuit causing it.
I'm not saying precations are not necessary when handleing MOSFETs, just that if you have 21 devices all blown up the same way, with shorted D-S, I would bet, that's not an ESD problem...
I've seen, or caused, 100's of burned up MOSFETs. Sometimes on purpose. I would guess less than 5% of them where blown by ESD
Or, what would be seen as a shorted Gate - Source. And generally when that happens the drain to Source is not shorted. A shorted D-S is ussually caused by excessive D-S current burning the channel permanatly. Of coarse voltage greater than the BVdss of the device would also cause a shorted D-S but we ussually choose a device with a higher breakdown than the circuit would ever be able to put across the MOSFET. An ESD incident however, overcomes the thin oxide (the O in MOSFET) which forms the gate to channel dielectric with greater than 20V typically causing a conductive path to the channel and no more gate capacitor or enhancment action. There are other somewhat typical situations like oscilation, etc. that might cause failures also.I'll be honest, I don't wear a wrist strap unless I'm working on someone else's equipment, working at home where I use no other ESD controls whatsoever. In the last year or so, I've handled 20V-30V vertical MOSFETs 5 days a week and I still have not noticed much of an increase in G-S shorts that I could'nt attribute to the driver or a failure of the circuit causing it.
I'm not saying precations are not necessary when handleing MOSFETs, just that if you have 21 devices all blown up the same way, with shorted D-S, I would bet, that's not an ESD problem...
hi,
After that inc i was alart not to use that soldering iron. also takes some extra prc too. yesterday when i was making aleph-x i didn't blown any one 9610 at all. because i never touched the circuit with hand or to the plate of mosfets while soldering. this way i found it didn't blown anyone. i don't know how and why it was blown. i checked my soldering iron body and the earth connection having 88vac. i checked with meter one side on the soldering iron body and another was on earthing connection. may be its caused the mosfets to short to G-S.
thanks
After that inc i was alart not to use that soldering iron. also takes some extra prc too. yesterday when i was making aleph-x i didn't blown any one 9610 at all. because i never touched the circuit with hand or to the plate of mosfets while soldering. this way i found it didn't blown anyone. i don't know how and why it was blown. i checked my soldering iron body and the earth connection having 88vac. i checked with meter one side on the soldering iron body and another was on earthing connection. may be its caused the mosfets to short to G-S.
thanks
I've been playing with MOSFET amps and a few other various circuits since about 1980. For the past 8 years or so I've been involved with SMPs. All MOSFET. All that experience except for the last couple years was in Phoenix, Arizona. For those of you who don't know, Phoenix is in the southwest USA desert where the humidity rarely goes above 10%. And, the lab I worked in last was carpeted. Sure death to the gate oxide of a MOSFET without proper handling.
I've seen, or caused, 100's of burned up MOSFETs. Sometimes on purpose. I would guess less than 5% of them where blown by ESD
I'll be honest, I don't wear a wrist strap unless I'm working on someone else's equipment, working at home where I use no other ESD controls whatsoever. In the last year or so, I've handled 20V-30V vertical MOSFETs 5 days a week and I still have not noticed much of an increase in G-S shorts that I could'nt attribute to the driver or a failure of the circuit causing it.
I'm not saying precations are not necessary when handleing MOSFETs, just that if you have 21 devices all blown up the same way, with shorted D-S, I would bet, that's not an ESD problem...
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