8 methods for quality evaluation of LED Chips package.
1. The difference of chip radiation power
Take a certain model of Sanan LED chip as an example. The chip size is 23X10mil. This chip has 4 radiation power levels (I=20mA). The higher the radiation power, the brighter the lamp beads made.
D24-radiant power 26-28mW
D25——Radiant power 28-30mW
D26——Radiant power 30-33mW
D27——Radiant power 33-36mW
The difference between the radiation power of D24 and D27 is 8mW, which means that the brightness of the lamp beads made by the same size chip is different, so it is necessary to know the radiation power level of the chip.
2. The difference between the lamp bead bracket material
At present, there are aluminum brackets, brass brackets, copper brackets, etc. on the market. Aluminum brackets are the cheapest, and copper brackets are the most expensive, with a price difference of more than ten times. Even the copper stent, the price of silver plating is also different. The market generally calls it a good stent, most of which are made of brass and silver plating.
3. The difference in chip size
The chip size is usually measured in mils. In general, the larger the chip, the higher the brightness. But without a high-power measuring microscope, it is not easy to distinguish the difference in chip size.
We can compare the chip size by calculating the chip area. For example, a 23X10mil chip has an area of 230 square mils. It is a good way to use the chip area to distinguish the chip size.
4. The difference of wire bonding materials
The chip and the bracket are connected by gold wire welding to complete the electrode connection. At present, there are two kinds of alloy wires and pure gold wires that are commonly used in the market. The pure gold wire is better.
The gold wire is divided into 0.7, 0.9, 1.0, 1.2, etc. according to the thickness. The thicker the gold wire, the lower the heat group and the longer the life, so it is necessary to understand the material and diameter of the gold wire.
5. The difference between phosphors
The white light bead is made of blue chip and yellow phosphor. The phosphor is mainly divided into aluminate and silicate. The performance of aluminate is better than silicate, and the most representative of aluminate is YAG. YAG has stable performance and low light decay. The chemical stability of silicate itself is poor, but the brightness is higher than that of YAG. WeChat public account: Shenzhen LED Network
Both materials have their own advantages and disadvantages. Which material to choose is a question that needs to be considered!
6. The difference between glue
Phosphors are placed on the chip after being stirred with glue. The quality of the glue affects the light decay and color drift of the LED light source. The poor quality glue is easy to vulcanize, the light decay increases, and the life of the LED light source is reduced!
7. Specs of light splitting, color separation and partial pressure
Light splitting: Luminance bins, lumen bins or light intensity bins. Used for illuminating light source, generally use lumen division.
Color separation: color temperature is divided into files, such as 3200K-3350K as the first file. The regular packaging factory will provide the color temperature BIN code, the smaller the color temperature bin, the better. The color temperature is small, and the color consistency of the light source made is good.
Voltage division: Voltage division, such as 3.0V-3.15V. For the light source is connected in series and parallel, the voltage division is controlled within 0.15V, so that the current distribution of the light source is uniform, which is beneficial to improve the life of the light source.
8. LED chip electrode map
Under normal circumstances, LED manufacturers will indicate that their LED lamp beads are packaged with a certain brand of chip, but after the white LED chip is packaged, the manufacturer of the chip cannot be judged from the appearance, and the chip needs to be stripped and inspected under a high-power microscope. (Different LED chips have different patterns of conductive electrode arrangement)
This electrode pattern is also called the chip electrode pattern. Due to different LED chips, the patterns of the conductive electrodes are different. Therefore, the LED chip brand can be verified by checking the chip electrode pattern.
In the LED lamp bead supply market, the most common problems are false brightness, chip size inconsistency, counterfeit brand chips, and iron brackets that pretend to be copper brackets. These problems can be identified by the above 8 methods, or can be detected by a professional LED inspection agency.
