Study of thermal characteristics on solder and adhesive bonded folded fin heat sink

The rapid advancement in technology of microprocessors has led electronics thermal system designers to pay increased attention to the folded fin heat sink. The advantages of using a folded fin heat sink are light weight, low profile, and small footprint. There are three manufacturing methods for bonding the folded fin to the base of heat sink: adhesive bonding, soldering, and brazing. Brazing is a high temperature process which takes place at around 550°C. The major concern with using the brazing process to manufacture heat sinks is dimensional deformation. The adhesive process, on the other hand, requires only sub 200°C or room temperature curing process. However, its thermal contact resistance at the joint is higher than others. Solder bonding is an alternative solution to above problems. The soldering process requires much lower temperature, less than 200°C, yet it gives excellent thermal contact and bond strength at the joint. This paper presents the theoretical study of thermal contact resistance at the joint between the folded fin base and the spreader plate of heat sink, and also presents the experimental results which support this theory