Why you should mount your SiC mosfets vertically

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From a DOE 2013 CFP;

As new WBG high voltage semiconductors and transistor topologies are developed, identification of failure modes and the conditions that initiate them are becoming increasingly important to ensure reliable use for space based applications. Issues with performance degradation and failure of Si power devices attributable to cosmic radiation has been observed in the use of these device in both space and high altitude applications. Although fewer and lower energy cosmic rays reach the Earth’s surface, this phenomenon is an increasing concern for terrestrial applications of power devices. Studies have shown that cosmic-ray-induced effects can strongly influence the voltage derating necessary for the safe and long term use of Si MOSFETs and IGBTs, directly affecting their adoption and use in various applications.

Cosmic-ray-induced errors—mainly due to neutrons-
-will only worsen as circuit size continues to shrink. Proposals will need to establish and compare the influence of cosmic radiation on SiC MOSFETs and Si IGBTs under identical conditions in regards to cosmic radiation events. The effects will need to be analyzed to determine the long term reliability and performance of these technologies. Through these results, designers will be able to make better choices in the use of either Si or SiC for different applications. Additionally, semiconductor developers will be better equipped to develop design solutions once their reliabity has been established. Ultimately, the acceptance of WBG devices can result in dramatic energy savings across a broad spectrum of applications including switched-mode power supply, motor control, traction, solar and aerospace industries.


and further down:

Although initial work has demonstrated the ruggedness of SiC power MOSFETs, more in-depth fundamental experiments are needed [5-7]. The typical testing method, designed to quickly obtain information, is to irradiatedevices with high energy neutrons (50-80 MeV, ~104n/cm2). This method accelerates the failures to enable gathering the necessary data within weeks, but it is expensive and requires access to a high energy neutron beam facility. Another method (called the real-time terrestrial method) is easier to implement but requires a substantial number of devices (>100) for testing. The proposal for this subtopic should be to bias a large number of devices at high voltage and room temperature with a series resistance to limit the current and observe failures over a few months. The devices should be mounted flat to increase the flux of cosmic-rays impinging on the devices. The bias across the devices should be varied from 50- 100% of the rated voltage in stepped increments and readings should be taken at each bias point for an established period of time (e.g. 10 weeks). The goal of this subtopic will be to compare commercially available high voltage Si IGBTs and SiC MOSFETs devices to establish their resistance to radiation effects.
 
In the intergalactic and interpersonal sense..;)

ps..that worked well..can barely see it..

jn
 

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