The present invention relates to a cooling device for cooling heat generated by a driver for a card-type storage medium for use, for example, in a personal computer, a digital camera and the like, and to a method of manufacturing the same. The present invention also relates to electronic apparatuses such as a personal computer, a digital camera, etc., incorporating this cooling device.
Since storage media such as Memory Stick (registered trade mark), Smart Media (registered trade mark), Compact Flash (registered trade mark) are compacter and thinner in size in comparison with conventional ones such as a floppy disk and the like, and in addition, since a storage capacity thereof can be made enormous, it is becoming widely used in electronic apparatuses such as personal computers, digital cameras and the like.
This storage media include such a type which has a flash memory and a driver integral therewith and another type in which the driver is installed separately in the apparatus or in another card or the like. In any case, its storage capacity is becoming considerably large.
By the way, with an increase in the capacity of the storage media along with such a trend of mass storage, a large amount of heat is generated from the above mentioned driver, thereby causing a problem of malfunctioning or the like to occur.
Therefore, provision of a cooling device is considered, for example, on a side of the electronic apparatus, and as such a cooling method, a technique using a heat pipe is referred to.
The heat pipe referred to here is made of a metal pipe having a capillary tube structure in an internal wall of the pipe, wherein the inside thereof is in vacuum and a small amount of water, Hydrochlorofluorocarbon or the like is sealed therein. When one end of the heat pipe is heated by making contact with a heat source, the liquid sealed therein is evaporated and vaporized to a gas, then as a latent heat (vaporization heat), the heat is absorbed. Then, it (vaporized gas) moves to a low temperature section at a high speed (almost at sonic speed), in which it is cooled to return again to the liquid by releasing the heat (latent heat discharge due to condensation). As the liquid returns to its original place passing through the capillary tube structure (or by gravity), it is possible continuously and efficiently to transport the heat.
However, as the conventional heat pipe is of a tube type and becomes spatially a large-scaled device, it is not suitable as a cooling device for use in electronic apparatuses such as the personal computer, digital camera and the like for which a compacter and thinner size is demanded.
Thereby, in order to make the heat pipe compacter, a cooling device has been proposed, wherein grooves are formed in each bonding surface of a silicon substrate and a glass substrate, and by bonding these substrates, a flow channel for constituting a heat pipe is formed between these substrates. In addition, at the time of the above-mentioned bonding thereof, a small amount of water or Hydrochlorofluorocarbon or the like is sealed therein, which, by undergoing phase changes within the heat pipe, acts a role as the heat pipe.
However, if the heat pipe is constructed using the silicon substrate as described above, because of a good heat conductivity of the silicon itself, heat from an object to be cooled is diffused well on the surface of the silicon, thereby causing a problem that evaporation of the liquid inside thereof becomes insufficient or does not evaporate at all, thus the function as the heat pipe is not demonstrated sufficiently.
The present invention has been contemplated to solve the above-mentioned problems associated with the conventional art, and an object thereof is to provide a cooling device of a compacter and thinner type as well as with an improved cooling performance, electronic apparatuses using the same and a method for manufacturing the same.