Research on the heat dissipation of lamps There are two main methods for heat dissipation of LEDs: one is to reduce the internal thermal resistance of the LED by improving the internal package structure and packaging materials; the other is to improve the external heat dissipation efficiency by reducing the external thermal resistance. The package structure and packaging materials are used, and the low thermal resistance package structure and technology are adopted. Firstly, the thermal resistance of the selected substrate, bonding material and packaging material is low; secondly, the structural design should be reasonable, the thermal conductivity between the materials is continuously matched, and the thermal connection between the materials is good, so as to avoid a heat dissipation bottleneck in the heat conduction channel. Ensure that heat is dissipated from the inside to the outside. In order to solve the problem of package heat dissipation of high-power LEDs, various structures have been developed at home and abroad.

In 2001, Lumi-Leds developed the AlGaInN power-type flip-chip structure, in which heat is directly transferred from the solder layer to the Si substrate, and then conducted to the metal substrate via the Si substrate and the bonding material. A thin film encapsulation structure was designed by magnetron sputtering process. The interface electrode heat sink and insulation layer were directly fabricated on the metal heat sink in the form of a thin film, which reduced the thermal resistance of the internal heat sink. Luo et al. proposed a micropump structure. Under the action of the micropump, water enters the small groove of the bottom plate of the LED to absorb heat, and then returns to the micro water container to dissipate heat through the fan. This structure is good in refrigeration but more complicated. After the package structure is determined, the thermal resistance of the system can be further reduced by selecting different materials to improve the thermal conductivity of the system. At present, domestic and foreign materials are often selected for substrate materials, adhesive materials and packaging materials. The LED heat sink substrate material is required to have high electrical insulation, high stability, high thermal conductivity, and thermal expansion coefficient (CTE), flatness, and high strength matched to the chip. Commonly used substrate materials are mainly silicon, metal (aluminum, copper, etc.), ceramic (AlO, AlN, SiC) and composite materials. At present, the main substrates are metal insulating board (IMS), metal core printed circuit board (MCPCB), ceramic substrate and metal matrix composite substrate (MMC). The bonding material has a great influence on the heat dissipation of the LED. Commonly used bonding materials are thermal conductive glue, conductive silver paste and alloy solder.

Cotton Rayon Fabric

Cotton Rayon Fabric,Cotton Rayon Blend,Cotton Rayon Blend Fabric,Polyester Cotton Rayon Blend

SHAOXING HENGHAI TEXTILE CO.LTD. , https://www.henghaitextile.com