8 ways to evaluate the quality of LED lamp beads

1, chip radiation power difference

Take a certain type of SAN ‘an LED chip as an example, the chip size is 23X10mil, this chip has four radiation power levels (I=20mA), the higher the radiation power, the brighter the lamp beads.

D24 — Radiant power 26-28MW

D25 — Radiant power 28-30MW

D26 — Radiant power 30-33MW

D27 — Radiant power 33-36MW

There is a difference of 8mW between the radiant power of D24 and D27, which means that the brightness of the lamp bead made by the same size chip is different, so it is necessary to know the radiant power level of the chip.

2, the difference between the lamp bead support material

At present there is aluminium bracket, brass bracket, red copper bracket on the market. Aluminum bracket is the cheapest, copper bracket is the most expensive, the price difference is more than ten times. Even if it is a copper bracket, the price of silver plating also has high and low points, the market is generally called a good bracket, most of it is made of brass silver plating.

3, chip size difference

Chip size is usually measured in MIL. In general, the larger the chip, the higher the brightness. But it is not easy to tell the difference in chip size without a magnification microscope.

We can compare the chip size by calculating the chip area. For example, a 23X10mil chip has an area of 230 square mil. It is a good method to distinguish the chip size by the chip area.

4. The difference between welding line materials

The chip and bracket are connected by gold wire welding to complete the electrode. At present, alloy wire and pure gold wire are commonly used in the market, and pure gold wire is better.

The gold wire is divided into 0.7, 0.9, 1.0, 1.2, etc. The thicker the gold wire, the lower the heat group, 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 light chip and yellow phosphor, phosphor is mainly divided into aluminate and silicate. Aluminate performance is better than silicate, aluminate is the most representative of YAG. YAG has stable performance and low optical decay. Silicate itself is less chemically stable, but brighter than YAG. Wechat official account: Shenzhen LED network

Two kinds of materials have advantages and disadvantages, which kind of material is a need to consider the problem!

6. The difference between glue

Phosphor powder is to be mixed with glue in the point on the chip, the quality of the glue affects the light decay and color drift of the LED light source, the quality of the glue is easy to vulcanize, increase the light decay, LED light source life reduced!

7, splitting, color separation and pressure specifications

Splitting: brightness division, lumen division or light intensity division. For lighting source, lumen classification is commonly used.

Color separation: color temperature grading, such as 3200K-3350K as a first gear. The formal packing factory will provide the BIN code of color temperature, and the smaller the color temperature classification, the better. The color temperature distribution is small, and the color consistency of the light source is good.

Voltage division: voltage division, such as 3.0V-3.15V, for the light source is series and parallel connection, voltage division is controlled within 0.15V, so that the current distribution of the light source is uniform, which is conducive to improving 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 chip, but after the packaging of white LED chips, the manufacturer of the chip cannot be determined from the appearance, so it is necessary to peel the chip and examine it under a high-power microscope. (Different LED chips have different patterns of conductive electrode arrangement)

This electrode pattern is also called chip electrode pattern. Due to different LED chips, the pattern of conductive electrode arrangement is different. Therefore, we can verify the LED chip brand by examining the chip electrode map.

In the LED lamp supply market, the most common problems are false brightness, inconsistent chip size, counterfeit brand chips, and the use of iron brackets as copper brackets. These problems can be identified by the above 8 methods, but also let a professional LED testing agency for detection.

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