LED solution

LED is called the fourth-generation illumination source or green light source. It has the characteristics of energy saving, environmental protection, long life and small size. It can be widely used in various fields such as indication, display, decoration, backlight, general illumination and urban night scene. Various companies around the world have launched a fierce technical competition around the development of LED. But LED cooling has always been an urgent problem to be solved!

The reason why the LED heats up is because the added electric energy is not converted into light energy, but a part is converted into heat energy. The luminous efficacy of LEDs is currently only 100lm/W, and its electro-optical conversion efficiency is only about 20~30%. That is to say, about 70% of the electrical energy becomes heat.

Specifically, the LED junction temperature is caused by two factors.

1. The internal quantum efficiency is not high, that is, when electrons and holes recombine, photons cannot be generated 100%, and it is generally called "current leakage" to lower the recombination rate of carriers in the PN region. Multiplying the leakage current by the voltage is the power of this part, that is, it is converted into heat, but this part is not the main component, because the internal photon efficiency is now close to 90%.

2. The internally generated photons cannot be completely emitted outside the chip and finally converted into heat. This part is mainly because the current external quantum efficiency is only about 30%, and most of it is 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 very 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.

LED chips are characterized by extremely high heat generation in a very small volume. The heat capacity of the LED itself is very small, so it is necessary to conduct this heat out at the fastest speed, otherwise it will produce a high junction temperature. In order to get the heat out of the chip as much as possible, Gao cool has developed targeted products for the LED market. In addition to the huge amount of thermal conductivity, it also gives other properties of the material to customers.

GC-TG thermal grease has the characteristics of fine paste, good brushing, no drying, and high thermal conductivity.

BN-TAPE100 is an acrylic thermal double-sided adhesive. Its thermal conductivity is better than that of 3M similar products, reaching 0.8W/m.k. It has strong adhesiveness and is widely used for bonding between LEDPCB board and heat sink substrate.

GC-3K/10K/19K series products have good fluidity and thermal conductivity and are widely used in potting of LED bulbs.

As a transparent two-component potting compound, BN-SR200 has good light transmittance and long-term anti-yellowing reliability. It can be used for LED lamp bead packaging and waterproof and moisture-proof.

In addition to the elasticity of the thermal pad, BN-FS150SP/GF series thermal pad adds fiberglass cloth or silicone tape as reinforcing carrier, which has high strength and can be designed as single.

The surface is sticky to increase the adhesion between the PCB board and the heat sink substrate.

Therefore, in addition to changing the design of the LED, it is also necessary to select a suitable thermal interface material to improve heat transfer and improve heat transfer efficiency.