Thermally Conductive Plastic - The Preferred Material For Solving The Heat Dissipation Of LED Chips
With the global warming caused by greenhouse gas emissions, people have increased their awareness of energy conservation and environmental protection. The use of new energy-saving electroluminescent diodes has attracted the attention of the international community.
Due to the advantages of small size, high luminous efficiency, low energy consumption, high brightness and environmental protection, countries have increased funding for LED R&D and corresponding policy support. In the past decade, LED technology has developed rapidly. At present, LED has been widely used in media screens, car lights, backlight sources, signage and indicative lighting, landscape lighting, and indoor flood lighting .
Usually 15 to 20 percent of the high power LED input power is converted into light, and the remaining 80 to 85 percent of the electrical energy is converted into heat. If the heat concentrated in the chip with a size of only 1 mm × 1 mm × 0.25 mm cannot be dissipated in time, the temperature of the chip and the stress distribution are uneven. When the junction temperature of the LED exceeds the high temperature that the device can withstand, the light output characteristics of the LED will decay forever. Studies have shown that the operating temperature of LEDs rises from 63 to 74, and the lifetime of LEDs is 3/4 less.
The heat conductive plastic is the preferred material for solving the heat dissipation of the LED chip, and it can derive the heat generated by the LED light emission in time to lower the junction temperature. Therefore, the development and application of thermal plastics is also a key issue for LEDs to develop in the market in the future.
Thermally conductive plastics can be used to make LED components such as housings, heat sinks, substrates, reflectors, inserts, and other components. In recent years, many plastic companies in the world have developed a variety of thermal plastics. Most of them use engineering plastics and general-purpose plastics as the substrate. The thermal conductivity of general plastics is only about 0.2W/mK. If the plastic is filled with thermal conductive filler, its heat. The conductivity can be from 1 W/mK to 20 W/mK, which is 5 to 100 times that of conventional plastics. Thermally conductive fillers can be divided into two categories: thermally conductive inorganic insulating fillers and thermally conductive non-insulating fillers. Non-insulating and thermally conductive plastic fillers have metal powder, graphite, carbon black, carbon fiber, etc., which have high electrical conductivity and thermal conductivity. The former is mixed with a plastic substrate to form a thermally conductive insulating plastic, and the latter is a thermally conductive non-insulating plastic.
Thermally conductive plastics can replace traditional aluminum as a heat sink. The density of the heat-conducting plastic is lighter than that of aluminum, which is almost half that of aluminum, so the quality of the plastic heat sink is only 1/2 of that of the aluminum heat sink. Plastic heat sinks can be injection molded, and the molding cycle can be shortened by 20 to 50 percent. With a thermally conductive plastic heat sink, you can use a non-isolated power supply without worrying about its problems. The disadvantage of the plastic heat sink is that the unit price is relatively expensive, so it is not suitable for the large-sized LED heat sink of the LED street lamp, but only suitable for the indoor small-power LED lamp.