Discussion on high power LED lighting technology

It is worth noting that up to now, the upstream epitaxial chip technology has been basically mature and stereotyped, and the cheap and good LED chip has been able to meet the lighting demand. Now the pricing power is shifting and developing in the midstream packaging and downstream application terminal market. This means that who can apply the chip and manufacture long-life, high-efficiency high-power LED lighting products, who is likely to become the ultimate winner of the LED industry. The problems of high-power LED lighting package and application are highlighted. The most important part is how to solve the heat-dissipation problem of high-power LED lighting. This is not only a technical problem in structural design and engineering applications, but also a thermal management mode. And scientific issues such as fluid mechanics. It is completely different from the existing "chip- aluminum substrate -heat-dissipating three-layer structure" high-power LED series lighting technology. We developed the "chip-heat-distribution integration (two-layer structure) integrated high-power LED lighting series lamps", in the technical route The aspect may be revolutionary and subversive, and will become a new development direction for the high-power LED lighting industry.

1. Status of high-power LED lighting products

At present, the luminous efficiency of LEDs can convert about 30% of electrical energy into light, and the remaining 70% of electrical energy is almost converted into thermal energy, which causes the temperature of the LED to rise. Because of its very small heat, low-power LEDs can be used without any heat-dissipation measures, such as instrument lights, signal lights, and small-size LCD screen backlights. However, for high-power LEDs, when applied to lighting fields such as commercial buildings, roads, tunnels, industrial and mining, etc., heat dissipation is a big problem. If the heat of the LED chip cannot be dissipated, it will accelerate the aging of the chip, light decay, color shift, and shorten the life of the LED. Therefore, the structural mode and thermal management design of high-power LED lighting systems are very important.

Now all high-power LED lighting fixtures on the market use "chip-aluminum substrate-heatsink three-layer structure mode", that is, the chip is first packaged on an aluminum substrate to form an LED light source module, and then the light source module is placed on the heat sink to be manufactured. High-power LED lighting fixtures.

It should be noted that the current thermal management system for high-power LEDs still uses LEDs for early use in indicator lights and display lights, and is a thermal management mode for low-power LEDs. The high-power LED illumination is prepared by using the "chip-aluminum substrate-heatsink three-layer structure mode", and there are obviously unreasonable places in the system structure, such as the contact thermal resistance between the structures, the junction temperature is high, and the heat dissipation efficiency is low, so the chip The released heat cannot be effectively exported and dissipated, resulting in low luminous efficacy, large light decay, and short life of the LED lighting fixture, which cannot meet the lighting demand.

How to improve the heat dissipation capability of the package is one of the key technologies to be solved in the current stage of high-power LED. The development direction and key points of LED lighting products are: high power, low thermal resistance, high light output, low light decay, small size and light weight, which makes the heat dissipation efficiency of LEDs higher and higher.

However, due to many factors such as structure, cost and power consumption, high-power LED lighting is difficult to adopt active heat dissipation mechanism, but only passive heat dissipation mechanism is adopted, but passive heat dissipation has greater limitations; and LED energy conversion efficiency is higher. Low, about 70% of the current conversion to heat, even if the luminous efficiency is doubled, 40% of the energy is converted into heat. In other words, it is difficult to increase the degree of heat dissipation, so in the long run, the heat dissipation problem of high-power LED lighting will be a long-standing problem.

Nowadays, the time for applying high-power LEDs to lighting has matured, and the development of efficient and natural heat-dissipating thermal management system has become a prerequisite and a key factor for the industrialization of high-power LED lighting. Therefore, a new technical route and system structure are needed to completely solve the problem of heat dissipation of high-power LED lighting.

2. New technical route for high-power LED lighting industry

In view of the existing high-power LED lighting and heat dissipation technology, there are many problems of low thermal resistance and low heat dissipation. We try to solve the problem of low light efficiency, serious light decay and cost by high-power LED illumination through the "chip-heat dissipation integration (two-layer structure) mode". Higher series of questions.

2.1 Technical route

"Chip-heat-dissipation integration (two-layer structure) mode" not only removes the aluminum substrate structure, but also places a plurality of chips directly on the heat sink to form a single-source multi-chip module, and prepares an integrated high-power LED. The luminaire and the light source are single, and are a surface light source or a cluster light source.

2.2 Technology key

How to enhance the thermal conductivity of the chip and reduce the thermal resistance interface layer, which involves thermal management system structural mode, fluid mechanics and engineering applications of super-thermal materials; how to effectively control the heat storage of the heat-dissipating matrix, plan the convective heat dissipation path, and establish efficient The natural convection cooling system starts with the design of the luminaire structure.

2.3 Technical solutions

Reduce the thermal resistance layer by changing the LED light source package structure, heat dissipation structure and lamp structure mode; apply super-thermal conductivity material to increase the thermal conductivity of the chip heat source; optimize the thermal management system based on the "chip-heat dissipation integrated two-layer structure", increase The flow of air forms a natural convection heat.

2.4 Design ideas

The high-power LED lamps are prepared in a modular manner. The light source, heat dissipation, and external structure are packaged into one integral module, and the modules are independent of each other. Any one module can be replaced separately. When one part fails, only the faulty module needs to be replaced, without You can continue to work normally by replacing other modules or replacing them as a whole. All module parts of the luminaire can be disassembled by hand to achieve convenient, fast and low-cost maintenance.

2.5 Design Highlights

Modularization of the system, in addition to meeting the heat dissipation and replacement requirements of the luminaire, must also meet the optical (optical efficiency) requirements and modeling (market) requirements of the LED lighting fixture.