Lighting grade aluminum substrate COB module

[Source: "High-tech LED - Technology and Applications" September issue]

As a new type of energy-saving and environmentally-friendly green light source, LED is bound to be the future development trend. It is called the fourth generation of new light source revolution, with the advantages of green and energy saving. However, the high luminous efficiency and low cost restricts the LED light source to replace the traditional lighting; at the same time, for the LED field, consumers should simply replace the traditional lighting, such as energy-saving lamps, incandescent lamps, etc., LED light sources must be modular, integrated, standardization. In this way, the cost will be optimized, the most popular, and standardized throughout the replacement process.

First, the comparison between traditional packaging and COB packaging

The so-called traditional packaging method is the package form of a single LED device, such as 3528, 3014, 5630, 5050, etc. currently used in the market; the COB module package is an integrated packaging method. (As follows: Table 1)

Table I:



Figure 1:


The above-mentioned Figure 1 compares in detail the traditional conduction mode of the LED and the heat conduction channel in the COB module application. It can be clearly seen that the COB structure heat dissipation channel is more direct and the thermal resistance is lower.


Second, the comparison between traditional COB structure and NEO-NEON COB structure

The reason why LEDs heat up is because electrical energy is not completely converted into light energy, and part of it is converted into heat energy. The conversion of electrical energy to light energy is about 30%, which means that some of the electrical energy is converted into heat. Specifically, the LED junction temperature is caused by two factors. One aspect is the internal quantum effect. When electrons and holes recombine, photons cannot be generated 100%, and the recombination rate of carriers in the PN region is reduced. The leakage current multiplied by the voltage is the power of this part, that is, converted into heat energy, but This part does not occupy the main component, because the internal photon efficiency is now close to 90%; the other is the external quantum effect, the internally generated photons can not be effectively emitted to the outside of the chip and finally converted into heat, this part is the main, large Some of them are converted into heat. Although the incandescent lamp has a very low luminous efficiency of only about 15 lm/W, it converts almost all of its electrical energy into light energy and radiates it. Because most of the radiant energy is infrared, the light efficiency is low, but it is exempted. The problem of heat dissipation. The heat dissipation of LEDs is now more and more important to people. This is because the light decay of LEDs or their lifetime is directly related to their junction temperature. The heat dissipation is not good, the junction temperature is high and the lifetime is short. (As follows: Table 2)

Table II:


It is known from the thermal ohm theorem ΔT=QR that the temperature difference = heat flow x thermal resistance, the greater the thermal resistance, the greater the heat is generated in the component, so the NEO-NEON_COB package can eliminate the insulation layer and reduce the series connection of the lighting module. The number of layers is used to enhance the heat dissipation of the LED. The dielectric layer does not have a very good thermal conductivity, which is roughly the same as the FR4 PCB, only 0.3W/mK, which becomes the conduction bottleneck between the chip and the heat sink. In order to improve this situation, NEO-NEON adopts the above substrate structure, removes the insulating layer, and solves the problem of thermal tilt caused by mismatch of thermal expansion coefficients. The Al2O3 material which is equivalent to the Al expansion coefficient and has high thermal conductivity is sintered with the Al substrate. Separate and connect the lines. This structure facilitates the realization of the cup structure, and the chip is fixed in the cup by washing or punching, which improves the light extraction efficiency compared with the conventional one. Therefore, the introduction of this technology is a requirement for LEDs for lighting.

Unfinished

For more information, please refer to the September issue of "High-tech LED-Technology and Applications"

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