The effect of filler-network heterogeneity on thermal resistance of polymeric thermal bondlines

Abstract

How would you……describe the overall significance of this paper? Insight is provided on how to fabricate thermal bondlines so as to maximize thermal conductance, by manipulating filler particles arrangements. Thermal bondlines provide thermal links between heat generating components and heat sinks.…describe this work to a materials science and engineering professional with no experience in your technical specialty? Although it is recognized that the thermal resistance of a thermal bondline is not a material property, little work has been focused on how to vary processing parameters in order to minimize thermal resistance. This works focuses on optimizing such assembly processes for thermal interface bondlines in order to segregate particles into particular regions, and maximize thermal conductance.…describe this work to a layperson? You could fry an egg on the processor of your computer while it is running gaming software for you. Such heat needs to be removed in order to avoid processor malfunction. Bolting on a small radiator does not quite do it; one needs some type of filled, thermal paste between the two in order to fill small gaps and get the heat out. For the most effective solution, the exact speed at which you squeeze such a thermal paste must be controlled.The influence of processing on filledpolymeric bondline microstructure and thermal performance was examined. Cu/thermal interface material/ Cu trilayers were assembled with a viscously applied, adhesive thermal interface material with Ag filler particles. It was found that decreasing the squeeze rate used for bondline formation from 10 to 0.1 µm/s resulted in a change in the microstructure from fairly homogeneous (homogeneous at 50 µm length scales and above) to one with marked segregation of many filler particles into highly compacted structures spanning the bondline thickness. A three-fold increase in effective thermal conductivity was correlated with this microstructure change. Significant changes in microstructure resulted when the compressive force (300N) used to form the bondline was removed before the bondline structure was stabilized by a cure operation and a four fold increase in the thermal resistance of such bondlines was observed.

Heat and fluid flow in high-power LED packaging and applications

“…The modelling results were found to match the experimental data within 14.3% when the applied pressure was 0.1 MPa. [100,128], geometry [145,146], orientation to the thermal gradient [145,[147][148][149], distribution [127,[150][151][152], and interfacial properties [100,128]. Much literature exists regarding the kTIM models of composites.…”

“…Through multi-modal particle mixing, the smaller particles can fill the gaps between the bigger particles and matrix, forming the preferential paths for heat conduction. Rae et al [152] found that thermal conductivity of the heterogeneous composites can be greater than that of composites filled with homogeneously distributed particles. The heterogeneity of composites in that work was driven by squeeze flow during which filler particles become entrapped and compacted, while the polymer matrix continues to flow.…”

Locally reinforced polymer-based composites for efficient heat dissipation of multiple heat sources

“…However, this unique control of microstructure and property for polymer-based composites has less been achieved in practice due to the technical difficulties in controlling the fillers positions. Squeezing [11][12][13] is a process which can make fillers entrapped and compacted in matrix. The heterogeneity of composites occurs when the rate of matrix flow through the fillers is greater than that of composites deformation [12][13].…”

“…Squeezing [11][12][13] is a process which can make fillers entrapped and compacted in matrix. The heterogeneity of composites occurs when the rate of matrix flow through the fillers is greater than that of composites deformation [12][13]. However, this method is limited to the thin films and demands highly accurate control of the squeeze rate [12][13].…”

“…The heterogeneity of composites occurs when the rate of matrix flow through the fillers is greater than that of composites deformation [12][13]. However, this method is limited to the thin films and demands highly accurate control of the squeeze rate [12][13]. Electric field [14] is another approach to achieve the unique microstructure, in which the localization of fillers is induced by electric field concentration.…”