The packaging technology of the traditional Lamp LED has been developed more maturely, the barriers to entry in the industry are lower, and the products have entered the stage of low-price competition. The key industrial production technology of SMD LED is still only mastered by a few large enterprises. Due to the requirements of miniaturization or power, the packaging technology is fundamentally different from Lamp LED. The barriers to entry in the industry are high, mainly reflected in the following aspects :
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SMD LED technology barrier is higher
1. Product Manufacturing Technology A. Compared with the traditional Lamp LED, the Chip LED in the SMD LED is very small, such as the ultra-thin Chip LED for mobile phones, which is only 0.3mm thick. Chip LED package needs to solve a series of problems caused by miniaturized structure, including: control of circuit board thickness, control of equipment and mold precision, control of gold wire arc during gold wire bonding process, dicing size control, plastic sealing process PCB deformation problem, combination of epoxy resin and PCB
B. Compared with the traditional Lamp LED, the high-power LED package in SMD needs to solve a series of problems caused by large heat dissipation and high light distribution requirements, including: high light extraction efficiency, good heat dissipation effect, and suitable for mass production. Technology, new heat sink design technology brought by thermoelectric separation, precision optical design and precision mold technology corresponding to different light output characteristics, new solid crystal technology, test binning technology in mass production, new multi-layer encapsulation structure design technology, etc.
C. At present, Chip LED white light technology is relatively mature, and the key production technology of high-power white LED needs to be further improved. The main production processes and technical difficulties are as follows:
a. Apply YAG (yttrium aluminum garnet) phosphor to the blue LED chip, use the blue light emitted by the chip to excite the phosphor to emit yellow-green light, and yellow-green light and blue light to synthesize white light. The process requires relatively low preparation, high efficiency and high practicability. However, because the viscosity of the carrier gel is a dynamic parameter, the phosphor will be precipitated due to the specific gravity larger than the carrier gel, and the precision of the dispenser is limited, the control of the uniformity of the coating amount of the phosphor is more difficult.
b. Use RGB (red, green, blue) three primary colors, multiple chips or multiple devices to illuminate and mix into white, or use blue chip to add yellow-green dual-chip complementary color to produce white light. This type of production can obtain white LEDs with high color rendering index and wide color gamut. However, due to differences in optical parameters (such as wavelength and light intensity) and electrical parameters (such as forward voltage) between chips, the light attenuation is inconsistent. Controlling white light parameters is the key to this technical route.
c. Apply RGB phosphor to the UV chip, and use the violet light to excite the phosphor to produce three primary colors to form white light. Since the main problem at present is that the ultraviolet light chip and the RGB phosphor are low in efficiency, the epoxy resin is easily decomposed and degraded under ultraviolet light irradiation.
2. Process Flow Management and Learning Curves SMD LED packages are ultra-fine, mass-produced. Miniaturized packaging requires high manufacturing precision. In the case of mass production, improper handling of a production detail can lead to a large number of products failing, causing significant losses to the enterprise. Therefore, SMD LED packaging not only puts higher requirements on packaging equipment and packaging technology, but also requires strong process management and strict control of each production detail.