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Method for Measuring Actual Junction Temperature And Package Thermal Resistance On Lsi And VLSI Devices

IP.com Disclosure Number: IPCOM000041125D
Original Publication Date: 1987-Sep-01
Included in the Prior Art Database: 2005-Feb-02
Document File: 1 page(s) / 12K

IBM

Related People

Ayers, RL: AUTHOR

Abstract

This article describes techniques that use a VLSI tester to measure the actual junction temperature of devices on an integrated circuit chip and for measuring the thermal resistance of the package. The actual junction temperature calculation uses the basic property of a silicon P/N junction that at low current levels, the forward voltage of the junction, decreases according to the following expression: ***** SEE ORIGINAL FOR MATHEMATICAL EQUATIONS IN DOCUMENT ***** -1.8mv/+1~C. The thermal resistance for the package is calculated from the expression: thermal resistance = Tj - Tcase/power consumption where Tj is the actual junction temperature and Tcase is the actual temperature of the module case.

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Method for Measuring Actual Junction Temperature And Package Thermal Resistance On Lsi And VLSI Devices

This article describes techniques that use a VLSI tester to measure the actual junction temperature of devices on an integrated circuit chip and for measuring the thermal resistance of the package. The actual junction temperature calculation uses the basic property of a silicon P/N junction that at low current levels, the forward voltage of the junction, decreases according to the following expression: ***** SEE ORIGINAL FOR MATHEMATICAL EQUATIONS IN DOCUMENT ***** -1.8mv/+1~C. The thermal resistance for the package is calculated from the expression: thermal resistance = Tj - Tcase/power consumption where Tj is the actual junction temperature and Tcase is the actual temperature of the module case.

To practice the techniques, the automatic tester is connected to an open collected substrate junction if the chip is formed from bipolar integrated circuits and to an input protect diode if the chip is formed from FET integrated circuits. The tester is then programmed to follow the below process steps:

A: The voltage at ambient temperature (At) is measured and called (Vfa).

B: A low current (say 1 microamp) is applied to the open collector or input protect diode and a voltage called Vfh is measured.

C: The module is then heated from an external source.

D: The change in voltage (Vfd) is calculated from the expression Vfd = Vfa - Vfh .

E: The temperature (T) is calculat...