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Monitoring Stud Diode Package Degradation

IP.com Disclosure Number: IPCOM000088677D
Original Publication Date: 1977-Jul-01
Included in the Prior Art Database: 2005-Mar-04
Document File: 2 page(s) / 20K

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Thermal resistance RT is used as one indicator of device package integrity.

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Monitoring Stud Diode Package Degradation

Thermal resistance RT is used as one indicator of device package integrity.

The device under test DUT is mounted on a heat sink (not shown) and put in a circuit, as shown in the figure. Current-limiting resistor R has a much higher resistance than the DUT so I(f) equals approximately V/R. For a typical diode, V(f) is less than 1 volt, V is 100 volts, R is 10 kilohms, and I(f) is 100 ma.

The heat-sink temperature is then brought up from room ambient and, at the same time, both V(f) and case temperature T(c) are recorded. If the device is good, junction temperature T(j) should follow T(c) closely during temperature rise. If there are cracks or voids between the junction and the case, T(j) will increase sluggishly as T(c) increases. Since changes in V(f) at a fixed I(f) are proportional to changes in T(j), correlation of changes in T(c) and V(f) with time will show whether the device package is defective.


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