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Seeking failure modes of Schottky Diode MBRS1100T3G. We have three failure with no root cause. Failure mode is SHORT what caused it? Over voltage? running to hot? etc. It is used in a buck boost power supply for a motor driven pump. What happens to diode when it avalanches due to high voltage spike? How long before it breaks down? Thanks, John

The MBRS1100 is a clip attached device. This means the electrical connection to the anode is made by a copper clip soldered to the die. These devices almost always fail short. Failures can result from a variety of causes. The device may be running excessively hot or there may be some form of electrical transient inducing failure. Transients inducing failure can occur in both the forward and reverse directions.

When analyzing application level failures, it is important to keep in mind that what is seen is often the result of a combination of events. A low power electrical transient may avalanche the device and induce a short. Energy stored in or made available by the application then enlarges this damage site, potentially masking it. This can make isolating the root cause challenging.

Regarding avalanche events, this is a Schottky rectifier and therefore a majority carrier device. Majority carrier devices react to input waveforms very quickly. If a voltage overstress is applied to the device it will start to avalanche quickly. Once this happens, power dissipation in the device can increase quickly and will not be uniformly distributed across the surface of the device (avalanche starts in the corners where the electrical field intensity is greatest).

Answered by:
ON Semiconductor
2015-04-20 13:55:23.718