1. Field of the Invention
This invention relates to a method and apparatus for cooling integrated circuit devices. More particularly, it relates to a closed-cycle coolant medium impingement cooling system and method that does not require a refrigeration cycle after the compression stage of the cooling system.
2. Prior Art
Each generation of semiconductor integrated circuits develops smaller and more closely packed devices. This higher integration generates greater component density and permits more circuit functions to be performed on a single semiconductor chip. On the other hand, packing more and more circuit elements closer and closer together generates greater heat and concentrates this heat in a smaller chip area. To ensure proper circuit performance, durability, and reliability, a way must be found to remove this heat to maintain device junction temperatures below some maximum value.
Conventional methods of cooling integrated circuits or a printed circuit board having a number of integrated circuits mounted on them include natural convection, forced convection (fan cooling), liquid cooling, various forms of heat sink, and a combination of two or more of these methods. However, all of these known methods are unsatisfactory because they are ineffective at present heat flux densities, inefficient, and/or expensive to operate. Known methods particularly suffer from a low power-density limitation.
In most known mounted component cooling systems, the heat removal capability of the system is limited by the thermal resistance of the interface of the device and its mounting. By cooling a coolant medium gas with an expansion valve, an interface thermal resistance can be tolerated. Other methods developed to pre-cool impingement air or other coolant medium include an additional refrigeration cycle, where the coolant passes through a refrigeration (cold) heat exchanger. In open-cycle cooling systems, condensation of water can be a major problem. In addition, the integrated circuit chips may be cooled directly, minimizing the interface resistance between the chips and the cooling medium.
It would therefore be advantageous to provide a cooling system to maintain electronic component junction temperatures below a prescribed maximum at high heat flux densities. Further, the present closed cycle system provides high heat transfer by utilizing gases other than air which have high heat transfer properties, such as helium, freon and the like, thus providing very efficient heat transfer. Such a system also eliminates the introduction of impurities, contaminants, or moisture into the cooling system.