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Specialty Manufacturer of Heat Sink Products
Unique Application of Thermal Analysis Tool

MIZUTANI ELECTRIC IND. (hereinafter Mizutani Electric), a specialty manufacturer of heat sinks and radiators for electronic devices, has been using Cradle scSTREAM for thermal analysis. Computational simulation has enabled the company to decrease the amount of experimental testing needed and substantially reduce their product development lead-time. Now they want to take another step to advance their simulation capabilities by drawing on their past experiences. To learn more about how Mizutani Electric is advancing the use of simulation, we interviewed Yousuke Watanabe, assistant manager of the Mizutani Electric Technology Center.

Yousuke Watanabe
Assistant manager of technology center

Fig. 1 Heat sink products of Mizutani Electric

 Mizutani Electric, a top specialty provider of heat sinks and radiators for electronic devices since 1967, is involved in all aspects of the electronics cooling business. This includes design, thermal analysis, manufacturing, and sales. Their products are highly trusted by manufacturers of industrial equipment requiring high performance radiators. In 1996, Mizutani Electric opened a plant in Malaysia to meet growing demand in the overseas market. The Development Technology group in Japan is responsible for product development and analysis.

 Semiconductors are used in almost all electronic devices and industrial equipment. Stable operation of these electronic devices and equipment is critical. The heat sinks and radiators protect the equipment by dissipating excess heat from around the heat source (Fig. 1).

 A heat sink usually consists of blocks with fins attached to the blocks. The blocks receive heat by contact with the heat dissipater. Fins are thin at surfaces attached to the block that release heat into the surrounding air. To further improve heat dissipation efficiency, an external fan can provide forced air cooling, a pump can provide water cooling, or heat pipes can be used. A peltier device can also be used to lower the temperature below normally expected values if necessary. The design requirements determine the cooling methods that can be used.

 A conventional heat sink is produced by extruding semi-solid aluminum through a die. The performance of a heat sink basically depends on the amount of its surface area. Because of this, most design engineers try to increase the effective surface area to improve cooling performance. In recent years, however, customers have demanded smaller, lighter, and more efficient heat sinks because their devices have become smaller. This has caused major design challenges as the amount of space between the heat sink fins also becomes narrower to the point where they reach their performance limit. 


 To break through this constraint, Mizutani Electric introduced a method called calking. With calking, the heat-receiving block and the fins are created separately. The fins are pressed into grooves in the block. The fins are held in the grooves in the block by bending the base of the fins with a lock seaming method (this is called "Hazeori" in Japanese). The fins are bent in half to make them stick closely to the grooves. At the same time, only the base of the fins are bent to make the heat sink lighter. In addition, the fins must be the appropriate thickness to avoid "hollows" which will decrease heat transfer performance.

 The introduction of the new calked heat sinks satisfied customer demands by overcoming the limitations of the extrusion method. As a result, Mizutani Electric has shipped more than 100,000 "J-Fin (Registered utility model)" heat sinks to their customers.

 ​While the usage and production method used for a heat sink depends on the customer specifications, Mr. Watanabe says their first priority in product development is "optimum design". Both economics and environmental considerations are driving the company to work hard to design smaller and lighter heat sinks using less secondary materials while meeting surface area requirements.

One Engineer for One Product

 At Mizutani Electric one engineer is basically responsible for one product. Each engineer designs the product and executes the thermal analysis. Typically the engineer performs dozens of thermal analyses each year. Usually they work on several different custom products and, at times, also on the standard products. They will iterate on a design shape using thermal simulation and perform the evaluation assessment after production tests. Often to meet both economic and environmental constraints, they will assess a matrix of design options to determine the optimum product design for each customer.

Keys to Success: High Operability and a Multitude of Case Studies

 Mizutani Electric chose scSTREAM for thermal simulation because of its high operability. Operability was a critical criterion when evaluating the variety of thermal-fluid simulation software available in the marketplace because the engineers using the software were not experts in computational simulation. Mizutani Electric was also impressed by the abundant number of heat sink related user case studies discussed at the Cradle user conference. Mr. Watanabe says, "Such informative user case studies gave us much needed information because we were newly getting started."

*All product and service names mentioned are registered trademarks or trademarks of their respective companies.
*Contents and specifications of products are as of April 31, 2013 and subject to change without notice. We shall not be held liable for any errors in figures and pictures, or any typographical errors.

Company Details


Established 1967
Business Production and sales of radiators for semiconductors
President & CEO Kazuo Mizutani
Head Office Chiyoda-Ku Tokyo
Employees 80 employees as of March 31, 2009
Capital 90,000,000 JPY



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