In the field of dielectric insulators, thermal management is a major challenge. Polymer matrix composites with fillers make it possible to combine electrical insulation and efficient heat dissipation. An overview of the fundamental principles.<\/p>\n
Definition: composite material.<\/strong> A composite material is a heterogeneous material made up of at least two immiscible constituents, whose combination gives the whole properties that none of the components would have separately. Two main phases are defined: the reinforcements and the matrix.<\/p>\n A composite consists of two main phases whose roles are complementary:<\/p>\n Phase 1 \u2014 Matrix:<\/strong> Ensures material cohesion, gives it its shape and chemical resistance. Can be:<\/p>\n Phase 2 \u2014 Reinforcement (fillers):<\/strong> Thermally conductive particles incorporated to improve heat transfer while preserving electrical insulation:<\/p>\n Polymer matrices inherently have very low thermal conductivities, generally below 0.5 W\/m\u00b7K. For dielectric insulation applications subjected to intense thermal cycles (transformers, electric motors, power modules), this level is increasingly insufficient.<\/p>\n Adding thermally conductive fillers significantly increases this value without compromising the electrical insulating properties. Filler selection depends on several criteria such as their chemical nature, morphology, particle size, incorporation rate and the quality of their interface with the matrix.<\/p>\n In the field of flexible dielectric insulators, thermosetting matrices, and in particular epoxy resins, occupy a predominant position. Their cross-linking provides dimensional stability and excellent mechanical resistance, while offering an ideal medium for the incorporation of thermally conductive fillers.<\/p>\n Fillers of different natures can be combined to obtain synergistic effects, making it possible to achieve effective thermal conductivities greater than 4 W\/m\u00b7K with ceramic fillers at high volume fractions (60-80%).<\/p>\n Market outlook 2025.<\/strong> The global electrical insulation materials market is valued at $11.9 billion in 2024, with a projected annual growth rate of +6.6% through 2034. Electric vehicle and renewable energy applications are the main growth drivers.<\/p>\nKey figures<\/h2>\n
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\n \nValue<\/th>\n Description<\/th>\n<\/tr>\n<\/thead>\n \n ~0.2 W\/m\u00b7K<\/td>\n Typical conductivity of a pure polymer<\/td>\n<\/tr>\n \n > 4 W\/m\u00b7K<\/td>\n Achievable with ceramic fillers<\/td>\n<\/tr>\n \n 300 W\/m\u00b7K<\/td>\n Intrinsic conductivity of boron nitride<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/figure>\n Structure of a composite material<\/h2>\n
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Why add thermal fillers?<\/h2>\n
Thermoset matrices: the reference material<\/h2>\n