Proper Handling Of Mosfet Devices

Yes, as with all dielectrics, the insulation can be compromised with multiple 'events' over time, none of which cause an immediate fault or failure but may compromise insulation such that its lifetime may be reduced. My experiences are with high voltage cables and other associated equipment and not specifically semiconductors but the physics are fundamentally the same. Others may have more relevant ESD information regarding the gate oxides of MOSFETS.

Now, with that being said, I doubt much of anything bad has happened to those MOSFETS and I would be comfortable using them in any non-safety critical application. Did you check the manufacturer's data sheet to see what ESD precautions are required?

I am waiting for a reply from the component manufacturer, since the data sheet and their website did not list ESD handling precautions.

if they never saw voltage I highly doubt that not being shipped in a static bag has an adverse effect, they are inherently rugged

If the person who handled them did not follow proper antistatic procedures, then they could have been "damaged".

Shirts, underwear or anything with man made fiber or wool can cause problems. With my last company we had to wear special straps around our feet to discharge to ground. After putting them on we had to make a test to prove that it had been electrically correctly fitted.

Anyone who has walked on nylon carpets and then touched a door handle and experienced a shock, probably had between 6-10,000 volts of charge. I do not know what the upper limits are....

This more than enough to cause damage to unprotected devices.

Please note that some devices have protection already built in!!

I would like to draw your attention to the following link, which saves me a lot of writing!:-

http://en.wikipedia.org/wiki/Static_electricity#Electronic_components

How do you know the bag was a non-anti-static bubble wrap bag?

What color was it?

It could be an ESD bag and look like a "normal" bag.

Just sayin'.

you tube has dozens of tutorials on mosfet transistors

I have never personally seen a degraded condition for any MOSFET.

It has always been all or none for me.

We are constantly being told that incremental damage can result from poor handling but I haven't seen it - I guess you wouldn't attribututea failure later on to handling anyway.

It could be that the devices have inbuilt ESD protection on their gates - zeners perhaps. Many IGBTs now ship with zeners inbuilt.

Excellent answer. This TI ESD Report explains in Latent Damage, that these parts can be degraded, and fail later. They call these miss-handled parts "Walking Wounded."We repair Inverting Power Supplies for robotic welders, and even a 1% failure rate would be unacceptable.Thank you all for the help, and I will forward this information to our suppliers.

GA

Good comment...

I have another question you may want to consider, especially if these transistors are considered an obsolete part. Since they were not in the original packaging, I would want to know if they were used or counterfeit parts. Southeast Asia recycles a lot of used components as new parts. Clipped leads are lengthend to look new, surfaces are polished and re-printed, and they may even provide new documentation and packaging.

If they are not obsolete, I would still wonder if these were pieces returned to your supplier from another customer who did not want them for whatever reason. In this case, neither you nor your supplier have any idea how well they were handled before you got them.

I am positive that these are not counterfeit parts. They are not obsolete either. We have addressed the proper handling and packaging with our supplier, and are receiving new ones which are properly packaged. We also addressed the issue of returns, no ESD Sensitive devices will be accepted for return, except to account for inventory before disposing of them.Thank you all again for the great help.