Before I look to exotic failure mechanisms for semiconductors, I try to exercise good handling techniques and avoid ESD damage modes, which usually can create a tiny puncture wound of the mosfet or other semiconductor. These tiny punctures do not always immediately prevent the device from operating, but degrade operation over time in the circuit leading to catastrophic failure, and usually when operated at a higher voltage. I use these precautions to prevent ESD and other types of damage. 1) Use a grounding wrist strap before handling semiconductors, especially in winter or other low humidity environments. 2) Wrap the leads close to the device with a small strip of aluminum foil, which can be removed after it is soldered into the circuit. 3) For mosfet's, the first device I solder into the circuit is a protection Zener from gate to source BEFORE REMOVING THE FOIL. Alternately, the last device you should solder into your circuit is the mosfet. 4) Be sure to use a grounded soldering iron and disconnect your circuit from any ground paths before soldering. 5) If you use an ungrounded iron that has not been used in a while, the ceramic element can absorb moisture creating a leakage path to the AC line. Be sure to leave it on for a while to bake out the moisture before soldering or ground it. 6) Use an MOV or other clamping device to protect the drain from high peak voltages. 7) Add some current limiting such as an incandescent lamp in the voltage source or use the current limit feature of your power supply. This will not help if you have a large capacitor downstream as the peak current can rapidly take out a semiconductor.  If you must operate a Tesla coil or other such device near your inventory, be sure your stock is totally wrapped in aluminum foil. Best to store devices at some distant location. I have had an extremely low failure of devices when these precautions are used. 
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Topic: ION's Tips, Tricks, and Techniques (Read 1179 times)
