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Toyama-shi, Japan

Ishizuka M.,Toyama Prefectural University | Hatakeyama T.,Toyama Prefectural University | Funawatashi Y.,Toyama Prefectural University | Koizumi K.,COSEL Co.
Active and Passive Electronic Components | Year: 2011

In recent years, there is a growing demand to have smaller and lighter electronic circuits which have greater complexity, multifunctionality, and reliability. High-density multichip packaging technology has been used in order to meet these requirements. The higher the density scale is, the larger the power dissipation per unit area becomes. Therefore, in the designing process, it has become very important to carry out the thermal analysis. However, the heat transport model in multichip modules is very complex, and its treatment is tedious and time consuming. This paper describes an application of the thermal network method to the transient thermal analysis of multichip modules and proposes a simple model for the thermal analysis of multichip modules as a preliminary thermal design tool. On the basis of the result of transient thermal analysis, the validity of the thermal network method and the simple thermal analysis model is confirmed. © 2011 Masaru Ishizuka et al. Source


Koizumi K.,COSEL Co. | Hatakeyama T.,Toyama Prefectural University | Fukue T.,Iwate University | Ishizuka M.,Toyama Prefectural University
2014 International Conference on Electronics Packaging, ICEP 2014 | Year: 2014

Thermal flow simulation based on computational fluid dynamics (CFD) is applied to the thermal design of electronic equipment. This paper discusses the applicability of the multiple reference frame (MRF) approach, which is a new method for modeling an axial cooling fan, to the thermal flow simulation of electronic equipment. In this study, we performed flow visualization of the exhaust air flow pattern of the fan plane and then we compared the flow visualization results with the MRF fan model simulation results. Finally, comparing the P-Q characteristic which obtained by MRF fan model simulation with measured P-Q characteristic was conducted to validate the applicability of the MRF approach to the thermal flow simulation of electronic equipment. Source


Sayama T.,Machinery and Electronics Research Institute | Tsuritani H.,Machinery and Electronics Research Institute | Okamoto Y.,COSEL Co. | Kinoshita M.,Toyama Prefectural University | Mori T.,Toyama Prefectural University
ASME 2015 International Technical Conference and Exhibition on Packaging and Integration of Electronic and Photonic Microsystems, InterPACK 2015, collocated with the ASME 2015 13th International Conference on Nanochannels, Microchannels, and Minichannels | Year: 2015

Fatigue damage in solder joints is one of the most significant factors in the failure of electronic components. Accordingly, many research studies on the fatigue lifetime evaluation of solder joints have been undertaken to improve the reliability of the components. The authors have devised a lapjoint specimen with high stiffness fixtures in order to carry out shear fatigue testing on thin solder joints, which have thickness of a few hundred μm and are manufactured via a reflow process similar to that used in actual printed circuit boards (PCBs). In this work, using the developed lap-joint specimen, the fatigue properties, including crack initiation and propagation of Sn- 3.0Ag-0.5Cu solder joints were evaluated under low cycle shear loading conditions with creep deformation. The lap-joint specimen was fabricated by the reflow soldering of two copper adherend, and was assembled with high stiffness loading fixtures. The dimensions of the solder joint are 4 mm (length) × 2 mm (width), with a thickness ranging from 100 to 400 μm. In the shear fatigue test, under the assumption of thermal loading conditions of actual PCBs, the inelastic strain amplitude and total strain rate were set to from 0.5 to 1.2 % and 1×10-4 s-1, respectively. In addition, the fatigue crack initiation lifetime is defined as the number of cycles N20% at which the load amplitude has decreased by 20 % from the initial value. As the first study result, the experimental relations between the fatigue crack initiation lifetime and the inelastic strain range were obtained. Next, in order to apply the experimental data to the evaluation of fatigue crack initiation in actual solder joints via finite element analyses, the lifetime data were related to the calculated inelastic strain at the interface corners of the solder joint of the specimen, where fatigue cracks initiate due to strain concentration. Finally, assuming that the reduction of the load amplitude corresponds linearly to the fatigue crack length, the experimental relations between the fatigue crack propagation rate and J-integral range were also obtained. The experimental data are regarded to be valid, given a comparison to other crack propagation curves for solder obtained by tensile cyclic loading of a flat specimen with a center crack. Consequently, the developed lap-joint specimen with high rigidity is effective for acquiring the material properties regarding fatigue crack initiation and propagation in actual thin solder joints. © Copyright 2015 by ASME. Source


Fukue T.,Iwate University | Hirose K.,Iwate University | Hatakeyama T.,Toyama Prefectural University | Ishizuka M.,Toyama Prefectural University | Koizumi K.,COSEL Co.
2016 International Conference on Electronics Packaging, ICEP 2016 | Year: 2016

This paper describes the details of pressure drop characteristics around axial cooling fans mounted in high-density packaging electronic equipment in order to improve prediction accuracy of supply flow rate of the fans in thermal design. Forced air convection cooling driven by cooling fans is the commonest strategy for dissipating heat from electrical devices. Cooling performance of the fans is mainly decided by supply airflow rate. The supply flow rate is strongly affected by pressure drop characteristics in electronic equipment. Especially in the case of high-density packaging electronic equipment, the airflow around the fan generally becomes complex and an accurate prediction of pressure drop characteristics around the fans become significantly difficult. In addition, due to the change of the airflow pattern around the fans by the electrical components mounted near the fans, a deterioration of fan performance itself is sometimes caused. Hence the accurate prediction of supply flow rate of the fans in high-density packaging electronic equipment is generally difficult. However, in order to shorten the period of thermal design, more detailed investigation about airflow characteristics around the fans mounted in high-density packing electronic equipment should be done in order to achieve the accurate prediction of fan's supply flow rate easily. We are trying to develop a prediction model of accurate supply flow rate of the fans mounted in high-density packaging electronic equipment. In this report, the pressure drop characteristic near the axial fan when an obstruction, which simulates electrical components mounted near the fans, is mounted in front of the fan was evaluated while changing the type of the obstruction. The pressure drop around the fan with the obstruction is mainly composed of three factors; the pressure drop around the obstruction, the inlet pressure drop at the fan and the outlet pressure drop from the fan. A level of these pressure drop factors were evaluated quantitatively by comparing experimental results with the conventional pressure drop database. In order to evaluate the accurate supply flow rate of the fan in high-density packaging electronic equipment, an important factor was clarified from the viewpoint of the pressure drop characteristics around the fans. © 2016 The Japan Institute of Electronics Packaging. Source


Eco

Trademark
COSEL Co. | Date: 2011-10-21

High-frequency switching power supplies; apparatus for power factor correction; power supply converters; switching regulators; power line filters; apparatus and instruments for regulating or controlling electric current.

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