subject: Led Thermal Substrate Technology Trend Analysis 2 [print this page] 3, LED heat dissipation substrate 3, LED heat dissipation substrate
LED heat dissipation substrate is to use its thermal substrate material itself has better thermal conductivity, the heat derived from the LED die. Therefore, we describe the way heat from the LED, LED heat dissipation substrate can be broken down two categories, namely (1) LED die substrate, (2) system circuit board, the two different substrates were heat by carrying the LED Grain and grain LED LED LED chip to the heat produced when, through the LED die to the cooling system circuit board substrate, and then absorbed by the atmosphere in order to achieve the effect of thermal dispersion.
3.1 System board
System mainly as a LED circuit board cooling system, finally leading to fin heat, shell or the atmosphere of the material. In recent years, printed circuit board (PCB) manufacturing technology has been very skillful, the early products of the system LED to PCB-based circuit boards and more, but with the increased demand for high-power LED, PCB material heat capacity is limited, so that it can not be applied The high-power products, to improve the high-power LED thermal problems, recently developed a high thermal conductivity coefficient of aluminum plate (MCPCB), using thermal properties of metal materials with better characteristics, has reached the purpose of cooling high-power products. However, LED brightness and efficacy with the requirements of sustainable development, even though the system board LED chip can effectively cooling the heat generated into the atmosphere, but the heat generated LED die can not effectively transfer from grains to the system circuit board, dissenting word of when the LED power to promote more efficient, the entire LED cooling bottleneck will appear in the LED die thermal substrate, the lower the article will do more for the LED die depth of the substrate.
3.2LED grain substrate
LED as the LED die substrate is mainly grain and energy between the system board to export the media, by wire bonding, eutectic, or flip the integration process and the LED die. The thermal considerations based on the current LED market grain-based substrate ceramic substrate mainly to different methods of line systems are broadly divided into: thick film ceramic substrate, low temperature co-fired ceramic, and thin film ceramic substrate of three, in Traditional high-power LED components, mostly thick film or LTCC substrate as a thermal substrate grain, then hit gold way combination of LED die and ceramic substrate. Such as the preamble, this gold link limits the loss of heat along the electrode contact effectiveness. Therefore, in recent years, domestic manufacturers are all efforts towards a settlement of this issue. The solution is either to find a high thermal coefficient of substrate material to replace alumina, contains the silicon substrate, SiC substrate, anodized aluminum plate or aluminum nitride plate, in which the materials silicon and silicon carbide semiconductor substrate features make it a more stringent test of current experience, and anodized aluminum plate, for his strength of anodic oxidation layer of fragmentation caused by lack of easy to turn, it is limited in practical application, which, at this stage more mature and higher general acceptance shall be to AlN substrate as heat; However, there is limited nitride thick aluminum plate does not apply the traditional process (materials printed in silver plastic air after the heat treatment is subject to 850 , it defects in materials reliability problems), therefore, Aluminum nitride circuit board manufacturing process required to prepare thin film system. Preparation of the thin film process system of aluminum nitride plate greatly accelerated by heat from the LED die to the system circuit board substrate material performance, thus greatly reducing heat from the LED die through the wire to the burden on the system board, and then to heat dispersion effect.
Another heat dissipation solutions for the LED die to its substrate or flip chip eutectic way links this way, a substantial increase in the system through the electrode wire to the circuit board of the cooling efficiency. This process, however, the wiring for the accuracy of the substrate and the substrate surface roughness is highly demanding circuit, which makes the thick film and LTCC substrate restricted range precision sheet mesh network problems and sintering shrinkage ratio and inadequate. More to import the film at this stage ceramic substrate, to solve this problem. Film ceramic substrates prepared by photolithography system circuit approach, combined with plating or chemical plating methods to increase line thickness, making its product line with high precision and high flatness characteristics. Eutectic / film ceramic flip chip process supported by the substrate is bound to greatly improve heat LED light-emitting power and life of the product.
