Method of maintaining an IC-module near a set-point
View Patent ↗A system for maintaining an IC-chip near a set-point temperature while electrical power dissipation in the IC-chip is varied includes a container having an open end with a seal ring. Located in the container is at least one nozzle for spraying liquid coolant droplets on a portion of an IC-module which holds the IC-chip. This spraying of the liquid coolant occurs while the seal ring is pressed against the IC-module. Also, a pressure reducing means is coupled to the container for producing a sub-atmospheric pressure in the space between the container and the IC-module while the seal ring is pressed against the IC-module.
1. A method of maintaining an IC-module under test near a constant set-point temperature while electrical power dissipation in said IC-module is varied; said method including the steps of:
pressing an open end of a container against said IC-module such that a leak free seal is formed between said container and said IC-module while said IC-module is under test;
producing a sub-atmospheric pressure in said container;
spraying a liquid coolant onto said IC-module, from at least one nozzle in said container, while maintaining a sub-atmospheric pressure in said container; and,
keeping said IC-module near said constant set-point temperature during testing.
2. A method according to claim 1 wherein the temperature of said IC-module is kept, by said sub-atmospheric pressure, at least 10° C. below the boiling point of said liquid coolant at atmospheric pressure.
3. A method according to claim 2 wherein said sub-atmospheric pressure in said container is reduced to a point where essentially all of said liquid coolant from each nozzle rapidly vaporizes when it hits said IC-module.
4. A method according to claim 2 wherein said liquid coolant circulates through a circulation subsystem which is coupled to each nozzle, and wherein said liquid coolant consists essentially of water.
5. A method according to claim 2 wherein multiple nozzles are spaced-apart in said container, and each nozzle receives one control signal and ejects just a single droplet of said liquid coolant when it receives said one control signal.
6. A method according to claim 5 which further includes the steps of: 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.
7. A method according to claim 5 which further includes the steps of: 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.
8. A method according to claim 5 wherein each nozzle ejects each droplet by squeezing said coolant with a piezoelectric device.
9. A method according to claim 5 wherein each nozzle ejects each droplet by heating said coolant with an electric heater.
10. A method according to claim 2 wherein each nozzle receives one control signal and sprays multiple droplets of said liquid coolant when it receives said one control signal.
11. A method according to claim 10 which further includes the steps of: 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.
12. A method according to claim 2 wherein said seal is formed by encircling a surface on said IC-module which encloses an IC-chip.
13. A method according to claim 2 wherein said seal is formed by encircling an exposed surface on an IC-chip in said IC-module.
14. A method according to claim 1 , further comprising removing said IC-module from said container after testing.
15. A method according to claim 14 , further comprising pressing the open end of a container against a second IC-module and repeating the steps of claim 14 on said second IC-module.
16. A method according to claim 1 , further comprising heating the IC-module with a heater provided within said container when the power of said IC-chip dissipates.
17. A method according to claim 16 , wherein said heater comprises one or more infrared heating elements disposed in said container.
18. A method according to claim 16 , wherein said infrared heating elements are interleaved with a plurality of nozzles.
19. A method according to claim 16 , wherein said infrared heating elements surround a cluster of nozzles.
20. A method according to claim 1 , wherein said set-point temperature is colder than the boiling point of said liquid coolant at atmospheric pressure.