The package components of electronic devices are usually com- posed of regular solids so that the Fourier analysis can be applied. Fourier series expansion is a powerful method to analyze the reg- ular system appears in many engineering systems. Wang et al. [13] used the Fourier series expansion to solve the Laplace equation to investigate the effects of metal lead, electric contact resistance, sili- con doping concentrations, and microcooler size on the cooling performance of the thermoelectric microcooler.