How to Distinguish The Quality of LED Lamp Beads

How to distinguish the quality of LED lamp beads? LED lamp gold medal manufacturers to answer for you, if you want to distinguish between LED lamp quality and lamp quality parameters. The led lamp is an electroluminescent semiconductor material chip, which is cured with silver or white glue to the bracket, and then connected to the chip and the circuit board by silver wire or gold wire, and sealed with epoxy resin to protect the inner core wire. Function, and finally install the outer casing, so the LED lamp has good seismic performance.

The quality of led lamp beads is related to; the packaging technology, gold wire, glue, spectroscopic technology, baking technology, and the quality of chip raw materials all affect the quality of led lamp beads. Looking for good quality, I suggest you find some brands of companies, such as, Tonghua, Corey, Osram, etc. in the LED lamp beads do a very good job. Specific information you can search online. The quality of LED lamp beads is as long as the consistency of light decay and effects

The led junction temperature is: the basic structure of the LED is a semiconductor P-N junction. LED light-emitting diodes are solid-state semiconductor devices that convert electrical energy into visible light, which convert 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. Experiments have shown that when current flows through the LED component, the temperature of the P-N junction will rise. In the strict sense, the temperature of the P-N junction region is defined as the junction temperature of the LED. Usually because the component chips (also known as microcircuits) have a small size, we can also consider the temperature of the LED chip as the junction temperature.

2. What is the cause of the LED lamp junction temperature?

When working on the lamp bead, there are five conditions that can cause the junction temperature to rise to varying degrees:

A. The electrode structure with poor components, the material of the window layer substrate or the junction region, and the conductive silver paste all have a certain resistance value, and these resistors are mutually added to form a series resistance of the LED element. When a current flows through the P-N junction, these resistors also flow through, causing Joule heat, which causes an increase in chip temperature or junction temperature.

B. Since the P-N junction cannot be extremely perfect, the injection efficiency of the component will not reach 100%. That is to say, in the operation of the LED, in addition to the injection of charge into the N region, the N region will also be injected into the P region. Human charge, in general, the latter type of charge injection does not produce a photoelectric effect, but is consumed in the form of heat. LED light-emitting diodes are solid-state semiconductor devices that convert electrical energy into visible light, which convert 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. Even if the useful part of the injected charge does not become all of the light, some of it combines with the impurities or defects of the junction and eventually becomes hot.

C. Practice has proved that the limitation of light extraction efficiency is the main reason for the rise of LED junction temperature. At present, advanced material growth and component manufacturing processes have enabled most of the input electrical energy of LEDs to be converted into optical radiant energy, however, because the LED chip material has a much larger refractive index than the surrounding medium (the decisive substance). As a result, a large part of the photons generated inside the chip can not smoothly overflow the interface, and the total reflection is generated in the chip and the dielectric interface, returning to the inside of the chip and being absorbed by the chip material or the substrate through multiple internal reflections, and vibrating in a lattice. The form becomes hot, causing the junction temperature to rise.

D. Obviously, the heat dissipation capability of LED components is another key condition for determining the junction temperature. When the heat dissipation capability is strong, the junction temperature drops. Conversely, when the heat dissipation capability is poor, the junction temperature will rise. Since the epoxy adhesive is a low thermal conductivity material, the heat generated at the P-N junction is difficult to dissipate into the environment through the transparent epoxy, and most of the heat passes through the substrate, the silver paste, the envelope, and the epoxy bonding layer. The PCB and the heat sink diverge downward. Obviously, the thermal conductivity of the relevant material will directly affect the heat dissipation efficiency of the component. A common type of LED, the total thermal resistance from the P-N junction region to ambient temperature is between 300 and 600 ° C / w. For a power LED component with good structure, the total thermal resistance is about 15 to 30 ° C. /w. The large difference in thermal resistance indicates that ordinary LED components can only operate normally with a small input power, while power components can dissipate power up to the watt level or higher.

3. How to reduce the junction temperature of LED lamp beads?

A. Reduce the thermal resistance of the lamp itself;

B. Good secondary heat dissipation mechanism;

C. reducing the thermal resistance between the LED lamp bead and the installation interface of the secondary heat dissipation mechanism;

D. Control the rated input power;

E, reduce the ambient temperature

The input power of the LED lamp bead is the only source of thermal effect of the component. A portion of the energy becomes radiant light energy, and the rest is eventually turned into heat, which raises the temperature of the component. Obviously, the main method to reduce the temperature rise effect of the LED lamp bead is to try to improve the electro-optical conversion efficiency of the component and convert as much input power as possible into light energy. Another important way is to try to improve the heat dissipation capability of the component. The heat generated by the junction temperature is dissipated to the surrounding environment by various means.

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