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Measuring a Semiconductor Junction Temperature

IP.com Disclosure Number: IPCOM000092000D
Original Publication Date: 1968-Aug-01
Included in the Prior Art Database: 2005-Mar-05
Document File: 2 page(s) / 21K

Publishing Venue

IBM

Related People

Leung, HC: AUTHOR

Abstract

This is a method for measuring the junction temperature of a semiconductor. A single junction measurement is made to determine the temperature t(j)i at an intermediate time Ti of a negative ramp power input, and the desired junction temperature t(jo) is then calculated in the equation t(jo) = ›(t(j)i -t(a))/(1 -Ti/T(s))| + t(a), where t(jo) = junction temperature at T = 0, t(j)i = junction temperature at T = Ti, t(a) = ambient temperature, Ti = time elapsed before measurement, and T(s) = time duration of negative ramp signal.

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Measuring a Semiconductor Junction Temperature

This is a method for measuring the junction temperature of a semiconductor. A single junction measurement is made to determine the temperature t(j)i at an intermediate time Ti of a negative ramp power input, and the desired junction temperature t(jo) is then calculated in the equation t(jo) = >(t(j)i -t(a))/(1 -Ti/T(s))| + t(a), where t(jo) = junction temperature at T = 0, t(j)i = junction temperature at T = Ti, t(a) = ambient temperature, Ti = time elapsed before measurement, and T(s) = time duration of negative ramp signal.

The time duration T(s) is set for a fairly long time, several minutes for example. There is a certain error in measuring temperature t(j)i which is E(o) = (Pi x P(o))/(t(j)i - t(a)) where E(o) = error, Pi = potential at T = Ti, and P(o) = potential at T = 0.

Therefore, the actual junction temperature t(jo) at T = 0 and P = P(o) is t(jo) = >(t(j)i - t(a))/(1 - Ti/T(o))| + t(a) + E(o).

By linearization of the temperature profile by these mathematical equations, the junction temperature at T = 0 and P = P(o) is obtained by the measurement of the actual junction temperature at a known interval of time Ti of the known total time T(s) of the negative ramp signal. Since T(s) is set relatively long, the transient time of measurement, which occurs in terms of microseconds, can be ignored. The time span T(s), as well as the slope of the power function, can be produced by a controlled speed motor drivi...