Thermal Analysis And Measurement Of Micro And Small Scale Objects

In this paper, some topics on thermal analysis and measurement of microelectronics and thermal wave imaging were studied with emphases on the heat transfer characteristics of small scale objects. The solid state relay and ceramic PGA were investigated through infra-red thermal imaging and finite element modeling. It is suggest that the average temperature of main cooling surface of the case is preferable to be chosen as reference temperature. Because of delaminations, voids and defects, the quality of bonding layer between chip and substrate is key to thermal reliability of the component. The convective heat transfer of upper surface of PGA is enhanced due to flow separation and reattachment caused by mounting obstacle. Numerical modeling and measurement methods were examined in the area of thermal wave imaging. A static numerical method was deduced and applied to simulate the amplitude and phase distribution of quasi-static temperature wave directly. It was found that one dimensional theory has notable error compared with two dimensional numerical modeling when the depth of the defect is comparable to its lateral dimension. An infrared thermal wave imaging technique was developed to measure thermal diffusivity of thin materials. A combined method using both amplitude and phase information was deduced and proved its high accuracy. Two non-Fourier heat conduction models: heat wave model and two step model were also summarized and discussed in this paper. It is suggest that the heat wave equation may have some problems compared with mechanical wave. Experimental results of sand and chalk specimen have not shown the effects of large scale relaxation time reported in some literature.