LED Basics: 10 Things You Should Know About LEDs

1. Introduction to LED

LED is the abbreviation for “Light Emitting Diode,” a semiconductor device that can convert electrical energy into light energy. The core part of the LED is a PN junction composed of a P-type semiconductor and an N-type semiconductor joining together. When the injected minority carriers and the majority carriers recombine, the excess energy is released in the form of light, thereby converting electrical energy into light energy. Chips of different materials can emit light of different colors such as red, orange, yellow, green, blue, and purple.

Compared with traditional lighting, LED has obvious advantages in saving energy and is currently one of the most advanced lighting technologies in the world. It is considered to be a great invention of mankind since Edison invented the incandescent light bulb in 1879.

Another major feature of LED is that it is eco-friendly. LED is a solid-state light-emitting device that is mercury-free, which means it will not cause heavy metal pollution as common with the traditional fluorescent or incandescent lighting.

2. Applications of LED

In the context of the global energy crisis, the energy-saving, environmental-friendly, colorful, safe, long-life, and miniaturized semiconductor LED lighting has been recognized as the third lighting revolution in the history of lighting. With technological improvements, the applications of LEDs are constantly expanding and extending, including but not limited to LCD backlighting, general lighting, signal display, signal lamps to automotive lamps.

3. LED Packing Types

LED packaging refers to the process of encapsulating LED chips and brackets with materials such as epoxy resin or silicone. Specifically, it is the process of arranging, fixing, and connecting LED chips and other components on the bracket or substrate, leading out the wiring terminals, and encapsulating and fixing them with a plastic light-transmitting insulator dielectric to form an overall three-dimensional structure, which protects and help dissipate heat for normal operation of the chip.

Currently, there are two main types of LED devices: F5 (common in indicator bulbs)and Surface Mount Devices (SMDs). Compared with F5-type products, SMD-type products have many unique and excellent characteristics, such as high assembly density and electronic products. Small-sized and lightweight, material-efficient (saving energy, equipment, manpower, time, etc.) Specifically embodied as:

(1) The defect rate of solder joints is low, the high-frequency characteristics are good, and the electromagnetic and radio frequency interference are reduced;

(2) High reliability and strong anti-vibration ability;

(3) It is easy to realize automation, improve production efficiency, and reduce costs by 30%-50%;

(4) The volume and weight of patch components are only about 1/10 of traditional plug-in components. Generally, after SMD is adopted, the volume of electronic products is reduced by 40%-60%, and the weight is reduced by 60%-80%.

At present, SMD LEDs are mainly used in backlighting, and general lighting, etc.

In terms of packaging, SMD LED products include Chip, Top, Sideview, and high-power products. Among them, TOP, Sideview, and high-power products are mainly white light and high-brightness products. The main application areas are backlights (such as：Mobile phones, computers, etc.) and lighting (such as indoor lighting, outdoor lighting, etc.). Therefore, the specific products packaged in SMD high-end form are usually TOP products, Sideview products, and high-power products, and the specific performance is white light, high Bright product. The domestic in-line device market has been basically saturated, and profits have been declining year by year; the competition for SMD low-end devices has become increasingly white, the production capacity of SMD mid-to-high-end devices is in a phase of gradual release, and product prices have changed significantly.

4. LED is Classified According to Luminous Color & Applications

LEDs belong to the category of semiconductor optoelectronic devices and are classified into monochromatic LEDs, full-color LEDs, and white LEDs according to their luminous colors. Among them, white LEDs are mainly used in the field of backlighting and lighting, with a wide range of uses.

The classification and application fields of each color light LED are as follows:

With the improvement of the luminous efficiency of white LEDs, semiconductor lighting has been widely used in mobile phones, backlights, special lighting, and other fields, and is advanced to the general lighting field. According to the “U.S. Semiconductor Lighting Development Blueprint (OIDA2002.11)” plan (Source: “China Semiconductor Lighting Industry Development Yearbook” (2008-2009)), the luminous efficacy of lighting LEDs will reach 150 lm/w by 2012, and the lighting will be in 2020 The luminous efficacy of LED should reach 200lm/w, which penetrates into all lighting fields. At present, the luminous efficiency of white light LED is about 120 lm/w, and the continuous improvement of the luminous efficiency of white light LED has become one of the important contents to promote the progress of white light LED technology. So far, white LEDs are the best fit for semiconductor lighting.

5. Overview of LED Development

As early as 1907, humans discovered the phenomenon of energized light emission of semiconductor materials. However, it was not until the 1960s that red LEDs made of compound semiconductor materials GaAsP were truly commercialized. However, due to the very low luminous efficiency, the cost was very low. High, it was only used for signal indicators of various expensive electronic equipment at that time.

In the 1990s, with the gradual improvement of LED luminous efficiency and luminous intensity, and the full coverage of the entire visible spectrum of the luminous color, the energy-saving effect and practicality of LED light sources have been highlighted, and their application fields have also been greatly improved. Expansion, LED has been widely used in LCD backlights, outdoor large screens, optical communication light sources, traffic lights, stage lights, landscape lights, car tail lights, and gradually enters traditional lighting applications such as street lights, indoor lighting, and automobile lighting.

6. Global LED Packaging Industry

The development of the global LED packaging industry is accompanied by the development of LED industry chain technology, which has obvious characteristics of the industrial transfer. Nichia (Japan), ToyodaGosei (Japan), CREE (USA), Lumileds (USA), and Osram (Germany) are the Top 5 largest LED lighting manufacturers in the world.

7. Latest Trends in LED Packaging Industry

(1) SMD packaging has gradually become the main form of LED packaging.

(2) Backlight and lighting products will become the driving force behind the rapid growth of the LED market.

8. Demand for Backlight LEDin the Market

LED backlights include small-sized backlights, medium-sized backlights, and large-sized backlights. Small-sized backlights are mainly used in mobile phones, MP3, MP4, PDA, digital cameras, video cameras, and fitness equipment, etc.; medium-sized backlights are mainly used in notebook computers, netbooks, computer monitors and CCTVs (Closed-Circuit Televisions), etc.; those of large sizes are mainly used in LCD TVs, etc.

9. Demand in the LED Lighting market

Compared with conventional incandescent & fluorescent lighting, the LED lighting has the advantages of being energy-efficient, environmental-friendly, short starting time, and long life, which makes it the ideal light source alternative. At present, LED comes with a relatively high usage cost, which restricts a vigorous promotion. However, as its cost gradually goes down, meanwhile governments promote their energy-saving policies, with the worldwide phase-out of incandescent lamps, the LED lighting sees a bright future ahead. The applications of LED lighting fall into 6 main categories: Outdoor Landscape Lighting (guardrail lights, projection lights, lawn lights, etc.), Indoor General Lighting, Decorative Lighting, Ambient Lighting (street lights, flashlights, headlights, reading lights, etc.), Accent Lighting (military, Medical lighting, biological special lamps, etc.) and Car Lighting.

With the ban on incandescent bulbs, business opportunities for LED bulbs below 10W have emerged. At this stage, lighting accounts for 19% of global electricity consumption, and total energy consumption reaches 2651 TWH. If the existing light source can be replaced with an energy-efficient light source, it is expected to save 30% of energy consumption. If the energy-saving light source is further combined with sensors, smart grid, and other related applications, it is expected that another 30% of energy consumption be saved. If 50% of energy consumption is saved by 2030, it is equivalent to reducing carbon dioxide (CO2) emissions from burning 2 billion barrels of fossil oil.

The average global consumption of incandescent bulbs is 20 billion per year. Each 1% increase in the penetration rate of LEDs in the field of incandescent lighting is expected to bring about 3.2 billion increase in the demand for LED packaging devices.

10. Environmental Conservation

The production process of LED does not pose much risk or pollution as those of the traditional fluorescent and incandescent lights do. The final products are energy-efficient and environmental-friendly too. Main pollution and pollutants include domestic wastewater, waste gases, environmental noise, and solid waste. The noise comes from pieces of process equipment such as cutting machines, wire welding machines, refrigerators, various pumps, cooling towers, and air conditioning units. Leftovers from the production process come into solid waste.