A study of epoxy composites for high thermal conductivty applications
- Autores: Sasan Moradi
- Directores de la Tesis: John M.C. Hutchinson (dir. tes.), Yolanda Calventus Solé (codir. tes.)
- Lectura: En la Universitat Politècnica de Catalunya (UPC) ( España ) en 2021
- Idioma: español
- Materias:
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- Resumen
Nowadays. both electronic and microelectronic circuits have great relevance and wide application in our daily lives and are increasingly being used with higher powers and frequencies. One of the main problems faced by their manufacturers is the dissipation of heat generated during their operation. since it reduces the useful life of these devices. One of the useful options that can help dissipate the generated heat is the lnsulated Metal Substrate (IMS). The IMS consists of three layers: copper foil, a dielectric layer, and a metallic substrate. The thermal conductivity of the material that constitutes the dielectric layer will be of vital importance when it comes to dissipating the heat generated. The most widely used system as a dielectric layer for IMS is an epoxy resin matrix with a crosslinking agent and a filler. As the thermal conductivity of the epoxy resin is low, it is essential to use a filler with high thermal conductivity that allows efficient dissipation of the generated heat. Therefore, in this thesis, the preparation of samples based on epoxy resins with boron nitride (BN) charges is studied. The effect of the BN particle size, the effect of the crosslinking agent used, the curing kinetics, the shape of the BN particles, the application of pressure on the material during the curing process, and the role of densification are analyzed. lt is found that the thenmal conductivity of epoxy-BN composites increases with increasing BN particle size for a given content of filler, and that BN agglomerates provide a higher thermal conductivity in comparison with the same size platelets, which is attributed to there being fewer interfaces with the epoxy matrix for the agglomerates. The epoxy-thiol system provides a higher thermal conductivity than the epoxy-Jeffamine system, which is attributed to a Lewis acid-base interaction. In the cure kinetics experiments, it was observed that the cure reaction of the epoxy-thiol composites was retarded with increasing the BN content for all particles (platelets or agglomerates). For the epoxy-Jeffamine system, it was observed that the cure reaction is independent of BN particle content, which is also correlated with the thermal conductivity measurements. The heat of reaction (L':.Hee) and the glass transition temperature of the fully cured system, Tgm, are independent of BN particle content, size and shape for both epoxy-thiol and epoxy-Jeffamine. On the other hand, the thermal conductivity increases by applying pressure for both epoxy-thiol and epoxy-Jeffamine systems in comparison with the composites cured at ambient pressure; the enhancement for the epoxy-Jeffamine system is greater. lt is revealed that the mechanisms of the enhancement of the thermal conductivity by application of pressure for each system are different. And finally, densification is shown to be a way of increasing the thermal conductivity; it is also shown to be a reversible effect.
