How to distinguish the quality of smd led chip from good and bad?
SMD LED chip is a kind of LED lamp beads. Compared with low-power LED lamp beads, high-power LED lamp beads have higher power, brighter brightness and higher price. The rated current of low-power LED lamp beads is 20mA, and those with a rated current higher than 20mA can basically be regarded as high-power. General power numbers are: 0.25w, 0.5w, 1w, 3w, 5w, 8w, 10w and so on. The main unit of brightness is lm (lumens), and the unit of brightness of low power is generally mcd (millicandela, 1cd=1000mcd), which is the luminous intensity I.
The good and bad quality of high-power LED lamp beads:
The quality is mainly distinguished from these aspects: light efficiency, color temperature, color rendering index, and light decay.
Light Efficiency: Of course, the most important parameter is the luminous flux (lumens/watt, lm/w) emitted by the LED per watt. The higher the light efficiency, the brighter it is. At present, the mainstream single high-power white LED light efficiency in the industry is 70-100lm/w.
Color temperature: warm white (K27-K35), natural white (K35-K45), pure white (K50-K67). The smaller the color temperature classification, the better, so that when a large number of LEDs are lit together, the color temperature difference will not lead to colorful, some yellowish, some white.
SMD LED chips
The higher the color rendering index, the better of course, so that the color of the object will not be distorted when it is irradiated on the object. Generally Ra reaches 80 and it is very good.
The light decay of high-power LEDs is mainly affected by temperature. Of course, it is not ruled out that some manufacturers' chips and phosphors will have an impact. The better the heat dissipation of the LED, the smaller the light decay, of course, the better the lifespan (although it can be bright after the light decay is reduced by 30%, the light efficiency is already very low, and there is no lighting significance).
High-power LED lighting should be installed on the heat sink, otherwise the light decay is very serious (because the temperature is very high). If we light a 1W high-power LED directly in the air, the temperature of the copper column at the bottom is 110°C after 1 hour. This is an experiment I have done myself. This is not to say that the quality of our LEDs is not good, but the large When the power LED is used, it is necessary to add a heat sink, which is also an important problem for LED lighting.
Precautions for high-power LED lamp beads:
1. During the application process, heat dissipation, electrostatic protection, and welding have a great impact on other functions, and we need to pay attention.
2. The light of LED still needs to be improved and can continue to develop downward, but the electric energy with higher power will be released as heat energy, so we need to do heat dissipation work.
3. Static electricity protection, LED lights are semiconductor devices, which are more sensitive to static electricity, especially white, green, blue, and purple LED lights should do a good job of generating static electricity.
