LED chip basics introduction

First, LED history

50 years ago, people already knew the basics of light generated by semiconductor materials. In 1962, General Electric's Nick Holonyak Jr. developed the first practical visible light-emitting diode. LED is the abbreviation of English light emitting diode. Its basic structure is an electroluminescent semiconductor material, placed on a leaded shelf, and then sealed with epoxy resin, that is, solid package, so it can To protect the internal core wire, the LED has good seismic performance.

Originally used as an indicator light source for instrumentation, LEDs of various light colors were widely used in traffic lights and large-area displays, resulting in good economic and social benefits. Take the 12-inch red traffic light as an example. In the United States, a long-life, low-efficiency 140-watt incandescent lamp was used as the light source, which produced 2000 lumens of white light. After passing the red filter, the light loss is 90%, leaving only 200 lumens of red light. In the newly designed lamp, Lumileds used 18 red LED light sources, including circuit losses, to consume 14 watts of electricity, which produced the same light effect. Automotive signal lights are also an important area for LED light source applications.

Second, the principle of LED chip

LED (Light Emitting Diode), a solid-state semiconductor device that converts electricity directly into light. The heart of the LED is a semiconductor wafer. One end of the wafer is attached to a holder, one end is the negative pole, and the other end is connected to the positive pole of the power supply, so that the entire wafer is encapsulated by epoxy resin. The semiconductor wafer consists of two parts, one part is a P-type semiconductor, in which the hole dominates, and the other end is an N-type semiconductor, which is mainly electrons here. But when the two semiconductors are connected, they form a "PN junction" between them. When a current is applied to the wafer through the wire, the electrons are pushed toward the P region. In the P region, the electrons recombine with the holes, and then the energy is emitted in the form of photons. This is the principle of LED illumination. The wavelength of light, also the color of light, is determined by the material that forms the PN junction.

Third, the main chip manufacturers

Osram of Germany, lumens of the United States, CREE, AXT, Taiwan's Guangjia, Guolian (FPD), Dingyuan (TK), Huaying (AOC), Hanguang (HL), Addison, Guanglei (ED), There are Seoul in Japan, Japan, Toshiba in Japan, Dalian Lumei, Fudi, Sanan, Hangzhou Silan Mingxin, and Imitation Japan. They are well-known chip suppliers. under.

Taiwan LED chip maker: Epistar (Epistar) referred to as: ES, (Lianquan, Yuankun, Lianyong, Guolian), Guangga Optoelectronics (Huga), New Century (Genesis Photonics), Arima Optoelectronics: AOC, Tekcore, Kellett, Fuxin, Guanghong, Jingfa, Shichuang, Zhoulei, Liansheng (HPO), Hanguang (HL), Guanglei (ED), Dingyuan (Tyntek) :TK, 曜富洲科技TC, Formosa Epitaxy, Guotong, Lianding, New Optoelectronics (VPEC), etc. Ledtech Electronics, Unity Opto Technology, Para Light Electronics, Everlight Electronics, Bright LED Electronics, Kingbright, Lingsen Precision Industries ), Ligitek Electronics, Lite-On Technology, HARVATEK, etc.

Continental LED chip manufacturers: Sanan Optoelectronics abbreviation (S), Shanghai Blu-ray (Epilight) abbreviation (E), Silan Mingxin (SL), Dalian Lumei (LM), Diyuan Optoelectronics, Huacan Optoelectronics , Nanchang Xinlei Shanghai Jinqiao Dachen, Hebei Lide, Hebei Huineng, Shenzhen Orende, Shenzhen Century Jingyuan, Guangzhou Puguang, Yangzhou Huaxia Integration, Gansu Xintiandian Company, Dongguan Fudi Electronic Materials, Qingxin Optoelectronics, Jingneng Optoelectronics , Medium-light optoelectronics , dry-light photoelectric , Jingda Optoelectronics, Shenzhen Fangda, Shandong Huaguang, Shanghai Lanbao and so on.

Foreign LED chip manufacturers: CREE, Hewlett-Packard (HP), Nichia (Nichia), Toyoda Gosei, the ocean on acid, Toshiba, Showa Denko KK (SDK), Lumileds, Xuming (Smileds), Genelite, Osram (Osram), GeLcore , Seoul Semiconductor, etc., Puri, Korea, Epivalley, etc.

Fourth, the classification of LED chips

1.MB chip definition and characteristics

Definition: Metal Bonding chip; this chip is a patented product of UEC. Features:

(1) Using a material with a high heat dissipation coefficient, Si, as a substrate, heat dissipation is easy.
Thermal Conductivity
GaAs: 46W/mK GaP: 77W/mK
Si: 125 to 150 W/mK
Cupper: 300~400W/mk
SiC: 490W/mK

(2) Wafer bonding the epitaxial layer and the substrate through the metal layer while reflecting the photons to avoid absorption of the substrate.

(3) The conductive Si substrate replaces the GaAs substrate and has good thermal conductivity (the thermal conductivity is 3 to 4 times different), which is more suitable for the high drive current field.

(4) The bottom metal reflective layer is beneficial to the improvement of luminosity and heat dissipation.

(5) The size can be increased and applied to the High power field, eg: 42 mil MB.

2.GB chip definition and features

Definition: Glue Bonding chip; this chip is a patented product of UEC. Features:

(1) A transparent sapphire substrate replaces the light-absorbing GaAs substrate, and its light output power is more than twice that of a conventional AS (Absorbable Structure) chip, and the sapphire substrate is similar to the GaP substrate of the TS chip.

(2) The chip emits light on all sides and has an excellent Pattern.

(3) In terms of brightness, the overall brightness has exceeded the level of the TS chip (8.6 mil).

(4) Two-electrode structure, which is slightly inferior to the TS single-electrode chip in terms of high current resistance.

3.TS chip definition and features

Definition: Transparent structure chip, which is a patented product of HP. Features:

(1) The chip process is complex and much higher than the AS LED.

(2) Excellent reliability.

(3) Transparent GaP substrate, which does not absorb light and has high brightness.

(4) Wide range of applications.

4.AS chip definition and characteristics

Definition: Absorbable structure chip; After nearly 40 years of development efforts, Taiwan's LED optoelectronics industry is at a mature stage for the development, production and sales of this type of chip, and the research and development level of major companies in this area is basically at At the same level, the gap is not big.

The mainland chip manufacturing industry started late, and its brightness and reliability still have a certain gap with the Taiwanese industry. Here we talk about the AS chip, especially the UEC AS chip, eg: 712SOL-VR, 709SOL-VR,
712SYM-VR, 709SYM-VR, etc.

(1) The quaternary chip is prepared by the MOVPE process, and the brightness is brighter than that of the conventional chip.

(2) Excellent reliability.

(3) Wide range of applications.