COB Packaging Technology Of LED Chip

The power and the light intensity of LED are getting much higher, resulting in the cost, lightcolor and heat dissipation are the three main challenges in front of us. And LED packaging islocated in the middle of the LED industry chain, involving electrical, optical, thermal, materials,mechanics, mechanical, and other disciplines cross technology. Therefore, the main purpose of thispaper is the LED chip COB(chip on board) packaging technology process design andimplementation. The present situation and the existing problems of the COB packaging technologyare discussed deeply. Besides, a research is done about COB packaging structure and processparameters for the optimum LED light color performance and heat dissipation performance. Finally,LEDs with COB packaging are analyzed by optical and thermal simulation and the LED lights andits driver are implemented and tested. The results are as follows:1. The thermal design and simulation of COB packaging LED chips is conducted. Through thefinite element thermal analysis software-ANSYS, the correlations between the COB packagingLED chip cooling performance and circuit board insulation material, thickness, LED chipconfiguration or the distance are obtained. The simulation results show that when the insulatinglayer of the coefficient of thermal conductivity is2.5W/m·K, thickness of30μm, LED chip singleconfiguration and spacing is4mm, the temperature are distributed uniformly, and the overallthermal resistance is the minimum.2. The optical design and simulation of COB packaging LED chips is also conducted. Throughray tracing optical simulation software-the Tracepro, the correlations between the COB packagingLED chip optical performance and reflective glass structure, the refractive index packagingmaterials are also obtained. The simulation results indicate that when the reflective cup primarilyradius is1mm cylindrical, light Angle is the largest and the light intensity distribution is the mostuniformly. When packaging material index is1.40~1.42, the highest luminous efficiency isachieved with normal maximum intensity of light above110CD.3. A novel type of the COB packaging technology LED lamp is developed. According to thetheory simulation, meticulous and comprehensive standards and design of the LED chip COBpackaging technology are made. And then the packaging PCB preparation, LED chip solid crystaland wire welding, phosphor powder selection, fluorescent glue coating and LED drive powersupply are implemented step by step. And a production with the plane and reflective concave cupCOB packaging LED lighting device is eventually accomplished.4. The characteristics of COB packaging LED lamp such as light color performance, aging resistance, base plate thermal resistance and thermal infrared figure are tested. The measured resultsare that the power is, plane:4.59W/concave cup:4.55W, base plate thermal resistance0.43°C/W,luminous efficiency plane:98.70lm/W/concave cup:106.22lm/W, withstand voltage1080V, colortemperature plane:5584K/concave cup:6674K with color rendering index plane:80.2/concave cup:81.5.5. Compared with different packaging LED chips, the COB packaging LED achieves at least15%brightness ascension than the existing packaging LED with luminous efficiency increased by12%, the base plate thermal resistance reduced by60%. And also COB packaging LED light fluxremains88%~95%, luminous efficiency increased by7%~12%.In conclusion, the fabricated COB packaging LEDs are durable and efficient, which can becustom-designed and applied to bar and surface lighting applications.