Method and apparatus for determination of junction-to-case therm

Details Method and apparatus for determination of junction-to-case therm Method and apparatus for determination of junction-to-case therm

1986-07-14

1987-12-15

Yasich, Daniel M.

Electricity: measuring and testing

Measuring, testing, or sensing electricity, per se

With rotor

364557, 374 44, G01N 2500, G01R 3126

Patent

active

047136120

ABSTRACT:
A method and apparatus for determining the junction-to-case thermal resistance, .theta..sub.jc, of a solid-state hybrid circuit element 38. First, the temperature coefficient, T.sub.c, of the voltage across the junction is determined with a small calibration current flowing through the junction. Digital multimeters 12 and 28 are used to measure the junction voltage and current, respectively. Next, more power is applied and the total power, P.sub.T, dissipated by the hybrid circuit element 38 is determined from values of the applied voltage and current measured with digital multimeters 12 and 14. The case of the hybrid element is kept at a constant temperature by a heat sink arrangement and the junction is allowed to reach thermal equilibrium at the higher power level. Finally, the increase in power to the hybrid element is removed and the change in junction voltage drop, .DELTA.V.sub.BE, between low-power operation and high-power operation is determined using a storage oscilloscope 30. The junction-to-case thermal resistance, .theta..sub.jc, is given by the quotient of .DELTA.V.sub.BE and the product of P.sub.T and T.sub.c.

REFERENCES:
patent: 3745460 (1973-07-01), Belzer et al.
patent: 3842346 (1974-10-01), Bobbitt
patent: 3973198 (1976-08-01), Hunt
patent: 3979671 (1976-09-01), Meeker et al.
patent: 4123938 (1978-11-01), Hamilton
patent: 4604572 (1986-08-01), Horiuchi et al.

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