The method of obtaining the thermal model of the printing circuit assembly

摘要

Thermal research of printed circuit assemblies (PCA) can be carried out field tests (thermal control in the different operating modes) and numerical simulation. The basic data for numerical calculation are the parameters of the environment and the characteristics of heat sources. For newly designing equipment (or PCA), these data can be calculated using circuit simulation packages or getting from element specifications (typically maximum power). Using the maximum power dissipated in the crystal is possible, but results this thermal research may be far from reality. For the already existing equipment and assemblies can only distribution of thermal field. For research of the different operation modes it is advisable to perform a numerical simulation. This paper proposes a technique to obtain the values of the heat source by thermal picture PCA. The initial data used by the temperatures at several time steps. As a result we obtain the value of heat source at each point of board/assembly (on the base of user defined variable grid). The availability of these data allows make a more detailed analysis of the PCA by computer-aided engineering (CAE) software, and taking into account the individual characteristics of each board. To solve the proposed scheme for solving the problem of determining the power density internal heat sources of PCA. It is based on the numerical solution of the Fourier heat equation by finite differences method.