How to choose 2835 SMD LED?
SMD LEDs are affixed to the surface of the circuit board, suitable for SMT processing, and can be reflowed. SMD LEDs solve the problems of brightness, viewing angle, flatness, reliability, and consistency. Compared with other packaged devices, it It has the advantages of strong vibration resistance, low solder joint defect rate, and good high-frequency characteristics. It encapsulates more LED chips in a smaller area, uses lighter PCB and reflective layer materials, and shows that the reflective layer needs to be filled. There is less epoxy resin. By removing the heavier carbon steel material pins and reducing the size, the weight of the product can be easily reduced by half. The volume and weight are only about 1/10 of the traditional plug-in components. After the use of SMD packaging, The volume of electronic products is reduced by 40% to 60%, and the weight is reduced by 60% to 80%, which ultimately makes the application more perfect.
Let's take a look at the uses of SMD LED lamp beads: LED large-screen displays, traffic lights, decoration, computers, electronic toys and gifts, switches, telephones, advertising, car lights, toy indicator light bars and many other production areas . So how to distinguish the advantages and disadvantages of LED SMD lamp beads?
1. The difference of lamp bead bracket materials: currently there are aluminum brackets, brass brackets, copper brackets, etc. on the market, aluminum brackets are cheap, copper brackets are expensive, and the price difference is more than ten times. Even the copper stents, the price of silver plating is also different. The market generally calls them good stents, and most of them are made of brass and silver plating.
2. The difference of wire bonding materials: The chip and the bracket are connected by gold wire welding method. At present, there are two kinds of alloy wire and pure gold wire on the market. Pure gold wire is good. Lanjin Optoelectronics uses pure gold wires to be 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 service life. All you need to know is the material and diameter of the gold wire.
3. The difference in chip size: The chip size is usually reported in mils. If there is no high-power measuring microscope, it is generally difficult to distinguish. The larger the chip, the brighter it is. We can compare the chip size by calculating the chip area. For example, 23X10, the chip area is 230 square mils. It is a good way to use the chip area to distinguish the chip size.
4. Color separation, partial pressure and spectroscopy specifications:
(1) Color separation: it is color temperature classification, such as 3200K-3350K as the first file, the regular packaging factory will provide the BIN code of the color temperature, the smaller the color temperature classification, the better, the smaller the color temperature classification, the color of the light source Good consistency.
(2) Voltage division: It is the voltage division of the chip, 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 light source life.
(3) Light splitting: the brightness of the lamp bead is divided into bins, there are lumen bins or light intensity bins, for the lighting source, the lumen bins are used. It is recommended to purchase LEDs based on light efficiency. Only products with high light efficiency will save energy and have a long life.
5. The difference of phosphor: The white light lamp 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. The 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 YAG. I want to make products with stable performance. , Don’t be fooled by the so-called high brightness, this is a big problem.
6. The difference of glue: Phosphor is to be mixed with glue and placed on the chip. The quality of glue affects the light decay and color drift. The bad glue will yellow and increase the light decay. Good glue It's jelly gum.
7. LED chip electrode map: Different chip manufacturers have different LED quality. LED suppliers will confess that their LED lamp beads are packaged with branded chips. After white light LEDs are packaged, it is impossible to judge the chip manufacturer from the appearance. , The chip needs to be peeled off and inspected under a high-power microscope.
