In electronic apparatus such as desktop computers, notebook computers, and mobile communication device, plural electronic components, such as a CPU, coil elements, and capacitors, are provided on a printed circuit board. As electronic apparatus operates faster and becomes more powerful and more sophisticated in functionality, there is a tendency for the calorific values of these electronic components in operation to increase in recent years. To maintain the stable operation of electronic apparatus, there is a need to improve their heat-release properties by quickly releasing heat generated at the electronic components to the outside.
Such being the case, electronic apparatus is generally provided with an air cooling device that cools these electronic components. Such a cooling device is provided with a heat sink that absorbs heat from the electronic components and then dissipates it and a cooling fan that sends cooling air to the heat sink. Since the calorific values of electronic apparatus are forecast to also continue to increase hereafter as described above, it is desired that measures be taken against the increase in the calorific value.
In air cooling devices, measures, such as upsizing of heat sinks and improvement in the performance of cooling fans, and so on, are taken to improve their cooling capability. However, in a case where large heat sinks are used, there is a problem that electronic apparatus also increases in size because of their incorporation. On the other hand, to improve the performance of cooling fans, there is a need to upsize them or increase their number of revolutions; however, such a method causes the problem that it is inevitable that electronic apparatus becomes large or their noise increases. In notebook computers in particular, portability, that is, their size and weight, as well as cooling capability, are important factors and silentness, that is, being silent during their operation is also an important factor; however, the above measures to improve cooling capability and these factors are mutually contradictory.
Therefore a liquid cooling system has been proposed that uses a liquid, such as water, having a specific heat that is higher by far than that of air as a cooling medium (see, for example, Patent Document 1).
In the cooling device for an electronic apparatus (notebook computer) disclosed in Patent Document 1, by connecting an electronic component provided to a main body, a radiator unit provided to a display unit, and a pump provided to the main body one after the other through the use of a pipe and circulating a cooling medium through the pipe, heat from the electronic component is transmitted to the radiator unit. In such a case, a method is generally used in which a plate-shaped heat-absorbing member is provided on the top surface of the electronic component and heat absorbed by the heat-absorbing member is dissipated into the cooling medium flowing through the pipe formed in the heat-absorbing member so that the heat can be efficiently released from the electronic component to the cooling medium.
[Patent Document 1] Japanese Patent Application Laid-Open No. 2001-24372