Research On Heat Dissipation Mechanism And Preparation Of A Coating With Higher-Efficient Capacity

The development of technology,not only promotes the rapid upgrading of electronic components,but also greatly raise their input power; while it should also be pointed out that,high internal temperature arises in these electronic devices featuring with small size,long-lasting working hours and closed working conditions,which severely deteriorates the performance of the devices.The fourth generation illuminant-LED(Light Emitting Diode),for example,owning the advantages of high-efficiency radiating,long operating life and environmental protection,however,has been restricted by its heating problems.And in this paper,the heat dissipating problem of electronic components will be solved by using coating technology.Summarized the present research situation at home and abroad of the thermal coating and material composite theory, in view of the main problems currently existing of thermal coating, this article development a new type of thermal coating, the main contents are as follows:(1) Starting form the angle of heat transfer, this thesis gives an analysis of the feasibility of heat radiating by coating technology, and put forward the idea and basic requirements of heat dissipation by coating. Depending on the heat transfer, a better cooling performance of the coating mainly attributes to a higher thermal conductivity or a higher radiation; and then the coating must have a good adhesion and mechanical properties.(2) According to the ideas and the basic requirements of coating’s cooling technology, this research conducts a formulation design of heat-radiating coating, which centers on the selection of various materials, especially base and filler. This research selects two-component silicone-modified acrylic- amino resin system as the main resin, with carbon fiber, aluminum nitride and mica as the main filler, supplemented by other fillers to prepare a heat–emitting coating, and measures the basic physical and chemical coatings properties such as: adhesion, heat resistance and so on. It focus on the impact of the carbon fiber content of the coating on its cooling performance, the thermal conductivity, and the radiation coefficient. The results show that with the increase of carbon fiber content, the cooling effect of the coating rapidly hovers up, then drop slowly, reaching the lowest with 12.3% of carbon fiber content, 14.1 ℃ lower than the blank sample under the same conditions; the thermal conductivity of coating also grows rapidly at first with the increase of carbon fiber content,then comes a slowly decline,amounting to the highest heat conductivity coefficient 2.1 W/(m·K) with 12.3% carbon fiber powder; and measurement of the radiation coefficient shows that emissivity of coating is proportional to the carbon fiber content.(3) Observation of the microstructure of the coating by FE-SEM shows that with the increase of carbon fiber content, the coating surface become more rough, and structure tends to loose, then comes to the emerge of the accumulation of carbon fiber with the 11.6% of carbon fiber content, the more carbon fiber content is, the severer the accumulation is, and the more disorder the layout is. According to the measurement of the actual cooling effect and thermal conductivity, we can know the effective layout and overlap of filler will form a good “heat passage”, but when there is too much filler, or when the base material can not wrap the filler, arising the simple accumulation phenomenon, which will destroy this "heat passage." In this paper, the coatings overlap better with 11.6% of carbon fiber powder.(4) In this thesis, the cooling mechanism is analyzed theoretically for the cooling effect of coating. A theoretical model of the internal heat coating is set up based on FE-SEM observation. Rapid thermal transfer can only be achieved by a good heat conduction network formed in the internal system;and the development of this network cannot live without contacts and influence thermal conductive particles make with each other; only by forming a good overlap among thermal conductive particles can the “heat passage” be attained; In this research, the heat conductivity coefficient is calculated theoretically. The data shows that actual measurement deviates little from coating’s theoretical heat conductivity coefficient, concluding that the model presented in this thesis is well matched.Research done in this article can provide a reference for the development of its mechanism of heat-emitting coating, with some guidance on the coating technology to solve the LED heat dissipation.