A BOUNDARY-ELEMENT FORMULATION OF THE CONJUGATE HEAT-TRANSFER FROM A CONVECTIVELY COOLED DISCRETE HEAT-SOURCE MOUNTED ON A CONDUCTIVE SUBSTRATE

A novel formulation is presented for solving the conjugate heat transf er problem that arises due to a thin flush heat source mounted on a co nductive substrate. The geometry is a paradigm for direct air cooling of components on conducting boards, PCB thermal algorithms based on th is approach are being developed for rapid estimation of the thermal fi eld in a direct air-cooled board, The algorithms are part of a suite o f tools for integrated electronic packaging design being developed at the Center for Electronic Packaging Research (CEPR), This paper presen ts the formulation of the approach and demonstrates its utilization fo r parametric studies of board level thermal management, in particular for studying the effects of board conductivity, The unique formulation allows one to couple a wide variety of dow models to the solid conduc tion, The solid side is modeled with a Boundary Element Method (BEM), The temperature field in the fluid side is not explicitly solved, rath er, analytical ''step temperature'' solutions, relevant to the particu lar how model, are used to express convective heat Aux as a function o f interface temperatures, A noniterative solution for the conjugate pr oblem is found by matching the temperatures and fluxes at the solid-fl uid interface, Results of a parametric study of the effects of board c onduction on component thermal performance are presented.