Preparation Of Thermal Conductive Composite Material For LED Radiator

With the rapid development of technology of electronic integration in LED field, LED electronic products tends to miniaturization design. However, it leads to that the problem of heat dissipation for materials becomes the key factor to restricting the service life of the products, because electronic chip will continue to gather heat when it runs normally. At the same tiame more scholars begin to pay attention to the research on thermal conductivity of composite materials. The famous foreign materials companies, such as BASF and DSM, began to do the research on thermal conductivity of composite materials very early, and they have introduced the mature product into the market application at present. The thermal conductive fillers and polymer matrix resin are melt blended and extruded to prepare thermal conductivity of composite materials. With the filler content increasing, the thermal conductivity of the composite gets higher, but the mechanical properties of the composite will become very poor. Which is the biggest problem in the research field of thermal conductive composites. To solve this problem, the paper took thermal plastic resin polyamide PA6 as matrix, rgarded magnesium oxide, graphite, carbon fiber and carbon nanotube(CNT) material as thermal conductive filler system and prepared composite materials with excellent mechanical strength and high thermal conductivity by means of melt blending depending on twin screw extrusion machine. Then the paper analyzed and studied different properties of them, and achievd the effect of the synergistic enhancement of thermal conductivity and mechanical properties of the composites. The main research work is as follows:1. The paper took surface of different conductive fillers modified with different processing method and observed the changes of filler’s microstructure by scanning electron microscopy(SEM). Then it analysed the effect of filler’s surface treatment on th performance of composite materials. It found that, the surface modification of fillers could not only significantly improve the interface combination state between thermal phase and matrix phase, but improve the phase compatibility and interfacial strength. Therefore, the interface thermal resistance of materials was reduced and the thermal conductivity and mechanical strength of composite was increased.2. By preparing thermal conductive composites filled with single phase filler, testing their relative performances, and researching the effects of addition amount, particle size and coupling agent content of thermal conductive fillers on the thermal conductivity and mechanical properties of the composites, we found that, for polyamide resin filled with single-phase inorganic filler, thermal conductivity of composite materials become higher with the bigger particle size, the higher filling amount. The research also drew a conclusion that the composite filled with different particle size fillers was better than the single particle size for the thermal conductivity and the enhancement effect of the composite materials and the coupling modification effect was the best when the content of silane coupling agent KH550 was 0.5%.3. Combining the method of surface plated with nickel with the technology of multiphase mixing and filling, the paper prepared thermal conductive composites of CF/MWCNT/PA6 by extrusion molding and tested their thermal conductivity, mechanical strength and microstructure. The testing results showed that the thermal conductivity of PA6 composites filled with carbon nanotubes coated with nickel and desizing carbon fiber was 1.42 W/(m·K), which increased by 373.33% than pure nylon; and the composite’s tensile strength reached 138 MPa, witch was almost two times of pure nylon.