Thin-film, metal alloy thermocouple junctions do not rectify, change circuit impedance only slightly, and require very little increase in space. Although they are less efficient cooling devices than semiconductor junctions, they may be applied to assist conventional cooling techniques for electronic devices

Tick, P. A.

Vilcans, J.

English

NASA Technical Reports Server

Metal B 
Thermoc 
Junction 
Me
rmocouple 
ct ion 
tal C 
tal A 
October 1970
	
Brief 70-10495 
S	 NASA TECH BRIEF EJ 
NASA Tech Briefs announce new technology derived from the U .S. space program. They are issued to encourage commercial 
application. Tech Briefs are available on a subscription basis from the Clearinghouse for Federal Scientific and Technical 
Information, Springfield, Virginia 22151. Requests for individual copies or questions relating to the Tech Brief program may 
be directed to the Technology Utilization Division, NASA, Code UT, Washington, D.C. 20546. 
Semiconductor Cooling by Thin-Film Thermocouples 
Semiconductor Device 
to be Cooled 
Thermocouple junctionS made of bimetallic thin 
films have been incorporated into the active region 
of certain solid-state circuit components to improve 
their heat dissipation characteristics. These junctions 
use the Piltier effect to remove heat, with the electric 
current itself providing the heat transfer medium. 
Thermocouple-type cooling devices have previously 
been used as an integral part of a circuit only in the 
case of a semiconductor junction in contact with an 
electroluminescent diode. However, the advantage 
of the efficient cooling produced by such junctions is 
negated by other problems: semiconductor junctions
form rectifiers, they produce a large change in circuit 
impedance, and have relatively large space require-
ments. These problems limit the usefulness of semi-
conductor thermocouples in circuit design. 
Metal alloy junctions, although less efficient cooling 
devices than seniicondj.ictor junctions, have the def-
inite advantages that they do not rectify, they change 
the impedance of the circuit only slightly, and require 
very little increase in space. 
Consider the thin-film, metal-alloy thermocouple 
cooling circuit shown in the figure. Given a dc bias, 
the four alloy junctionswill exhibit the Peltier effect. 
-	 (continued overleaf) 
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Aeronautics and Space Administration. Neither the United States	 information contained in this document, or warrants that such use 
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The amount of heat transferred at a junction is given 
by the equation: Q = (k, - k ) iT where 
Q	 is the heat flux in watts per cm 2 (positive Q 
implies heat absorption) 
k	 is the absolute Seebeck coefficient of the 
alloy on the current input side of the junction 
k,	 is the absolute Seebeck coefficient of the 
output side alloy 
J	 is the current density in amp per cm 2 , and 
T	 is the junction temperature in °K. 
If the three metal alloys A, B, and C are chosen so 
that k 8 > k A >k, heat will be absorbed by both of 
the junctions which surround the device, and rejected 
by both junctions at the heat sink. 
Notes: 
1. This innovation may be applied to assist conven-
tional cooling techniques for many electronic de-
vices, such as Impatt, LSA, and Gunn devices, 
detector diodes, and power transistors. It should
interest engineers and circuit designers who use 
these or other temperature-sensitive devices. 
2. No further documentation is available. Specific 
questions, however, may be directed to: 
Technology Utilization Officer 
Headquarters 
National Aeronautics 
and Space Administration 
Washington, D.C. 20546 
Reference: B70-10495 
Patent status: 
Inquiries about obtaining rights for the commercial 
use of this invention may be made to NASA Code 
GP, Washington, D.C. 20546. 
Source: P. A. Tick and J. Vilcans

Electronics Research Center

(ERC-10 149) 
Brief 70-10495	 Category 01


Semiconductor cooling by thin-film thermocouples

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