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Degradation Monitoring in Thermal Fatigue Life Test of Power Schottky Barrier Diode

IP.com Disclosure Number: IPCOM000087400D
Original Publication Date: 1977-Jan-01
Included in the Prior Art Database: 2005-Mar-03
Document File: 2 page(s) / 22K

Publishing Venue

IBM

Related People

Yu, CC: AUTHOR

Abstract

In a life test for thermal cycling of a Schottky barrier diode, a high operating current (e.g., 50 amperes) is applied to the diode D when the switch S is closed. When S is closed, heated water is supplied to the heat sink (that would otherwise cool D) and D heats up from the combined effects of the operating current and the heated water. After about five minutes, S is opened to interrupt the current and the heat sink is supplied with cooled water for about five minutes so the temperature returns to its original level. This cycle is repeated several thousand times to simulate the thermal cycling that would normally occur over a number of years. At the end of the test, the device is considered to have run through its normal life of operation.

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Degradation Monitoring in Thermal Fatigue Life Test of Power Schottky Barrier Diode

In a life test for thermal cycling of a Schottky barrier diode, a high operating current (e.g., 50 amperes) is applied to the diode D when the switch S is closed. When S is closed, heated water is supplied to the heat sink (that would otherwise cool D) and D heats up from the combined effects of the operating current and the heated water. After about five minutes, S is opened to interrupt the current and the heat sink is supplied with cooled water for about five minutes so the temperature returns to its original level. This cycle is repeated several thousand times to simulate the thermal cycling that would normally occur over a number of years. At the end of the test, the device is considered to have run through its normal life of operation.

By monitoring the voltage across D with a meter M, one can detect either of two kinds of failures, anode contact degradation (due, for example, to lifting of the anode contact) and thermal resistance degradation (due, for example to package cracks in D).

If the anode contact lifts (or some equivalent failure occurs), the voltage across the device will rise because of the increased resistance of D.

If the thermal resistance increases in the path between the cathode terminal and the junction where the voltage drop across D normally occurs, the junction temperature of D will increase and the voltage drop Across D will decrease.

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