In this study we have attempted to compare the heat transfer performance of various commonly used fm geometries.Realistic, manufacturable geometries are optimized for minimizing thermal resistance at moderate laminar air velocities. The basis of comparison was chosen to be a circular array of lmm diameter pin fms with a 2mm pitch. The pitch-to-width ratio of the other geometries were chosen to provide equal ratios of fin area to base area. CFD simulations were carried out on a two-dimensional computational domain bounded by planes of symmetry parallel to the flow. The air velocity was in the range of 0.5 to 5Ws. A comparison of heat transfer coefficient and pressure drop is presented.

The paper describes a novel approach to solving heat transfer problems in geometrically complex systems. In the present approach, instead of simulating the detailed complex geometry, templates of components and devices are assumed rather than working on actual components. By varying the template dimensions a systematic study on the effects of geometrical configurations on cooling airflow and heat transfer is made possible. The application of the approach is illustrated drawing examples from heat transfer analysis of portable computers. The purpose of the study is to develop a methodology whereby the packaging designer is freed from the task of performing detailed numerical analysis. Currently available numerical analysis tools such as computational fluid dynamics (CFD) codes are given a role in an undertaking to create databases from which fast design codes are developed.

No abstract

The paper describes a novel approach to solving heat transfer problems in geometrically complex systems. In the present approach, instead of simulating the detailed complex geometry, templates of components and devices are assumed rather than working on actual components. By valying the template dimensions a systematic study on the effects of geometrical Configurations on cooling airflow and heat transfer is made possible. The application of the approach is illustrated drawing examples from cases of heat spreader designs and heat transfer analysis of portable computers. The purpose of the study is to develop a methodology whereby the packaging designer is freed from the task of performing detailed numerical analysis. Currently available numerical analysis tools such as computational fluid dynamics (CFD) codes are given a role in an undertaking to create databases from which fast deslgn formulas are developed.KEY WORDS: heat transfer in complex systems, portable computers, heat spreader, CFD simulations 1. INTRODUCTION As electronic systems are diversifying in their function, information processing performance, hardware morphology, and the relevant thermal issues of importance are also diversifying. Cooling of chips, which has been the central issue for thermal management of large systems in the 1910's to 198O's, is now one of the issues that need attention of the packaging designer. Other issues are arising from the system's shrinking physical size and the diversifying usage environment. For example, in portable equipment, different components are crammed in a tight space and they have different thermal criteria for reliable operation. So, in the design of portable equipment, heat flow paths need to be managed to create a desirable temperature distribution in the system box. Similar situations are found in microsystems where electronic circuits and MEMS devices are accommodated in a tight space. Also, the temperature of the system's interface to the human skin needs to be controlled in portable and wearable equipment.