Recent research efforts have been devoted to developing technologies for fabricating electronic circuits in three dimensions using ink-jet processes. The management of generated heat in such circuits will require them to incorporate specialized design features for promoting the removal of unwanted heat from key areas and the limiting of component temperatures to safe levels. Hence, effective tools for predicting the heat transfer characteristics of three-dimensional circuits are required to develop optimum designs.This research encompasses a course of investigation including the development of such design tools and their verification using experimental methods. These experimental methods consisted of thermal tests conducted with prototype circuits constructed in three dimensions, with materials appropriate to the overarching design concept. After the verification process, the investigation proceeded with the construction of numerical models to compare a range of design features expected to enhance passive heat rejection in the discrete resistive component. The relative impact of each of these structures as well as the impact of specific material choices is comparatively evaluated using the developed tools.Further research centered on the fabrication and testing of a circuit which more fully incorporated the 3-D architecture by employing a surface-mount technology (SMT) resistor and by embedding the resistor and conductive components within a cast polymer matrix. Experiments with this circuit and corresponding finite-element models showed that for the power dissipation levels investigated, the presence of the embedding medium actually results in lower temperatures at the resistive component.It was shown in the course of this latter investigation that film coefficients calculated by standard methods do not effectively account for interactions between adjacent convective surfaces in these circuit architectures. A numerical model featuring thermal/fluid dynamics capability and simplified geometry compared to the actual circuit was shown to correlate well with live tests. These model results can be used to calculate improved values for the film coefficients to be applied to models not featuring fluid capability. The models with improved film coefficients similarly provided resistor temperature values which correlated well with the live test results.
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