Hitachi Cable, Ltd. will soon begin marketing a newly developed liquid-cooled module with a cooling capacity of 150 W (0.23degree /W*1) for use in desktop PCs and servers. This newly developed cooling module offers substantially improved heat-radiating efficiency compared to previous products.

As the performance of electronic products such as personal computers (PCs) is continually improved, the amounts of heat generated by the CPUs and other semiconductors mounted in such products rise as well, thus cooling has become an important issue. However, due to heat-radiating limitations and problems with operating noise, the air-cooled fan system adopted by most products cannot provide sufficient cooling performance to cope with the increased heat generation, which imposes certain restrictions on equipment design. Liquid-cooled modules are therefore attracting a great deal of attention for their ability to solve this problem.

A liquid-cooled module consists of a pump for circulating coolant, a heat-receiving part that is connected to a product and transfers heat from the product to the coolant, a heat-radiator section that releases heat into the atmosphere, and flexible tubes that connect these components. The pump circulates the coolant, and the heat-receiving component transfers heat effectively from the product to the coolant. The heat-radiator section then disperses and discharges heat into the atmosphere to reduce the temperature of the coolant. Through technical licensing of the "silent cooling" technology of Hitachi, Ltd., Hitachi Cable has developed a liquid-cooled module; the company is now producing and supplying this module for use in the liquid-cooled notebook PCs of Hitachi, Ltd.

Hitachi Cable has been working to develop a liquid-cooled module with enhanced cooling performance that will permit use of the module with desktop PCs and servers. Recently, the company has achieved significant improvement in heat-radiating performance through the use of our uniquely designed high-efficiency jacket for the heat-receiving component and by installing a compact radiator and cooling fan in the heat-radiator section, and has successfully developed a liquid-cooled module with cooling capacity of 150 W (0.23degree /W).

In a verification test conducted by Hitachi Cable using a full-tower-type desktop PC unit equipped with an off-the-shelf 3.06-GHz (81.8 W) Pentium(R) 4*2 processor, the liquid-cooled module was found to be capable of reducing the temperature increase of the processor by 35% in a 100% drive condition, relative to a conventional cooling-fan system *3.

The liquid-cooled module allows installation and connection of additional jackets to configure multi-element heat-receiving components. The cooling performance can also be adjusted by varying the air flow rate of the cooling fan located in the heat-radiator section. Therefore, it is possible to design a module that emphasizes either cooling performance or quietness *4. Hitachi Cable plans to offer an extensive standard lineup of jackets, radiators, and other main components for added cost-reduction.

Sale of the liquid-cooled module is scheduled to begin in the first half of fiscal 2004, and Hitachi Cable estimates that annual sales will grow to approximately 200 million yen in three years.

As this liquid-cooled module offers high cooling performance and can be connected to multiple heat-generating units, Hitachi Cable expects its application to expand to products in various fields, including audio-visual products and other home appliances, as well as medical equipment. In addition to the liquid-cooled module, the Company develops and supplies other cooling products utilizing the efficient heat-transmission properties of copper, such as copper heat-pipe modules and copper-finned heat sinks, all of which are based on our copper heat-transfer tubes for air conditioners and copper heat-spread materials for semiconductors. To meet diverse customer needs, Hitachi Cable continues to offer total thermal solutions.

Liquid-cooled-module manufacturing site

Hitachi Cable Tsuchiura Works
3550, Kidamari-cho, Tsuchiura-shi, Ibaraki Prefecture 300-0026, Japan

For inquiries regarding the liquid-cooled module, contact the following

Copper Products Group, Copper Products Division	TEL: +81-3-5252-3619
Strategic R&D Office	TEL: +81-29-826-7370

*1	degree /W: Temperature difference required to transfer heat energy of 1 W. The indicated value was verified in a test conducted using a test machine prepared by Hitachi Cable.
*2	Pentium(R) is a registered trademark of Intel Corporation in the United States.
*3	The verification result is a value converted based on an outside air temperature of 35degree. When installed in the desktop PC unit, the liquid-cooled module (with cooling fan) was able to maintain the CPU at a temperature of 53.0degree, whereas an air-cooled module resulted in an increase in the CPU temperature, to 62.7degree. The verification test using the air-cooled module of an off-the-shelf Pentium(R) 4 processor was conducted by Hitachi Cable in its laboratory for the purpose of comparing the liquid-cooled module with an air-cooled module. In the test, the chipset in the PC unit was also cooled together with the CPU processor, and the liquid-cooled module was able to reduce the temperature increase by 35%.
*4	When the liquid-cooled module was installed in a cubic PC unit and the cooling performance was set to 100 W, the drive noise was 33 dB.

Example of system configuration

(1) Standard model	(2) High-performance model
(Fan for power-supply unit is utilized)	(Additional fan installed for cooling coolant)

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Collant jacket