Conjugate heat transfer from a raised isothermal heat source attached to a vertical board

Natural convection cooling of large raised bodies attached to conductive substrates is studied analytically and compared with experimental results to ascertain the significance of conjugate heat transfer in applications related to microelectronic cooling. It is shown that good agreement between experimental data and simulated results, obtained using a model based on the boundary layer equations, is possible when heat transfer from a raised isothermal body is accounted for by reducing the thermal resistance between the heat source and the cooling fluid in proportion to the increase in wetted surface area. The importance of radiative heat transfer between the heated object and the surroundings is shown to be very important, especially in natural convection applications. The importance of using high conductivity copper lands as a means of lowering heat source temperatures is demonstrated for cube-on-board applications