Temperature control system which sprays liquid coolant droplets against an IC-module at a sub-atmospheric pressure

1. A system for maintaining an IC-module under test near a constant set-point temperature while electrical power dissipation in said IC-module is varied; said system being comprised of:

a container having an open end with a seal for pressing against said IC-module while said IC-module is under test, said container being detachable from said IC-module;

at least one nozzle, in said container, for spraying a liquid coolant on said IC-module when said seal is pressed against said IC-module;

a vacuum pump coupled to said container, for producing a sub-atmospheric pressure between said container and said IC-module when said seal is pressed against said IC-module during testing; and

a pressure regulator for maintaining said sub-atmospheric pressure while the temperature of said IC-module is kept near said set-point.

2. A system according to claim 1 wherein said pressure regulator reduces said sub-atmospheric pressure to a point where said liquid coolant from each nozzle rapidly vaporizes when it hits said IC-module.

3. A system according to claim 2 which further includes a circulation subsystem, coupled to each nozzle, that holds said liquid coolant; and wherein said liquid coolant consists essentially of water.

4. A system according to claim 2 which includes multiple nozzles at spaced-apart locations in said container, and each nozzle includes a means for receiving one control signal and a means for ejecting just a single droplet of said liquid coolant when it receives said one control signal.

5. A system according to claim 4 which further includes a closed-loop control means for: a) receiving a sensor signal representing a sensed temperature of said IC-module, and b) sending said control signal to all of said nozzles simultaneously with a frequency that increases as the differences between said sensed temperature and said set-point increases.

6. A system according to claim 4 which further includes a closed-loop control means for: a) receiving a sensor signal representing a sensed temperature of said IC-module, b) sending said control signal to a subset of said nozzles simultaneously, and c) increasing the number of nozzles in said subset as the difference between said sensed temperature and said set-point increase.

7. A system according to claim 4 wherein said means for ejecting in each nozzle ejects said single droplet by squeezing said coolant with a piezoelectric device.

8. A system according to claim 4 wherein said means for ejecting in each nozzle ejects said single droplet by heating said coolant with an electric heater.

9. A system according to claim 2 wherein each nozzle includes a means for receiving one control signal and a means for spraying multiple droplets of said liquid coolant when it receives said one control signal.

10. A system according to claim 9 which further includes a closed-loop control means for: a) receiving a sensor signal representing a sensed temperature of said IC-module, and b) sending said control signal with an ON-OFF ratio that increases as the difference between said sensed temperature and said set-point increases.

11. A system according to claim 2 wherein said seal is shaped to encircle a surface on said IC-module which encloses an IC-chip.

12. A system according to claim 2 wherein said seal is shaped to encircle an exposed surface on an IC-chip in said IC-module.

13. A system according to claim 1 , wherein said pressure regulator maintains said sub-atmospheric pressure such that the boiling point of said liquid coolant is lower by at least 10°C. from its boiling point at atmospheric pressure.

14. A system according to claim 10 , wherein said system maintains said IC-module near a constant set-point temperature while said IC-module is under test.

15. A system for maintaining an IC-module near a set-point temperature while electrical power dissipation in said IC-module is varied; said system being comprised of:

a container having an open end with a seal for pressing against said IC-module;

a closed loop cooling system to remove heat from said IC-module comprising:

at least one nozzle, in said container, for spraying a liquid coolant on said IC-module when said seal is pressed against said IC-module;

a condenser coupled to the container to receive and condense vaporized coolant from the container;

a vacuum pump coupled to said container, for producing a sub-atmospheric pressure between said container and said IC-module when said seal is pressed against said IC-module; and

a pressure regulator for maintaining said sub-atmospheric pressure while the temperature of said IC-module is kept near said set-point;

one or more heating elements to add heat to said IC-module when the power dissipated by said IC-module decreases by an amount that would cool said IC-module below said set point;

a controller configured to control said closed loop cooling system and said one or more heating elements to maintain the temperature of said IC-module at or near said set point.

16. A system according to claim 15 wherein said pressure regulator reduces said sub-atmospheric pressure to a point where said liquid coolant from each nozzle rapidly vaporizes when it hits said IC-module.

17. A system according to claim 16 , wherein said liquid coolant consists essentially of water.

18. A system according to claim 15 , which includes multiple nozzles at spaced-apart locations in said container, and each nozzle includes a means for receiving a control signal from said controller and a means for ejecting just a single droplet of said liquid coolant when it receives said control signal.

19. A system according to claim 18 , wherein said controller is configured to: a) receive a sensor signal representing a sensed temperature of said IC-module, and b) send said control signal to all of said nozzles simultaneously with a frequency that increases as the differences between said sensed temperature and said set-point increases.

20. A system according to claim 18 , wherein said controller is configured to: a) receive a sensor signal representing a sensed temperature of said IC-module, b) send said control signal to a subset of said nozzles simultaneously, and c) increase the number of nozzles in said subset as the difference between said sensed temperature and said set-point increase.

21. A system according to claim 18 wherein said means for ejecting in each nozzle ejects said single droplet by squeezing said coolant with a piezoelectric device.

22. A system according to claim 18 wherein said means for ejecting in each nozzle ejects said single droplet by heating said coolant with an electric heater.

23. A system according to claim 15 wherein each nozzle includes a means for receiving one control signal and a means for spraying multiple droplets of said liquid coolant when it receives said one control signal.

24. A system according to claim 15 wherein said controller is configured to: a) receive a sensor signal representing a sensed temperature of said IC-module, and b) send said control signal with an ON-OFF ratio that increases as the difference between said sensed temperature and said set-point increases.

25. A system according to claim 15 wherein said seal is shaped to encircle a surface on said IC-module which encloses an IC-chip.

26. A system according to claim 15 wherein said seal is shaped to encircle an exposed surface on an IC-chip in said IC-module.

27. A system according to claim 15 , wherein said pressure regulator maintains said sub-atmospheric pressure such that the boiling point of said liquid coolant is lower by at least 10°C. from its boiling point at atmospheric pressure.

28. A system according to claim 15 , wherein said heater comprises one or more infrared heating elements disposed in said container.

29. A system according to claim 15 , wherein said infrared heating elements are interleaved with a plurality of nozzles.

30. A system according to claim 15 , wherein said infrared heating elements surround a cluster of nozzles.

31. A system according to claim 15 , wherein said container is detachable from said IC-module.