Full analysis of LED lamp bead structure
LED lamp beads are mainly composed of five materials: bracket, silver glue, chip, gold wire, and epoxy resin.
1. LED lamp bead bracket
1. The function of the bracket: conduction and support
2. Composition of the bracket: The bracket is formed by electroplating the bracket material. It is composed of five layers of material, copper, nickel, copper, and silver from the inside to the outside.
3. Types of brackets: Cup brackets are used for concentrating light, and flat-head brackets are used for large-angle astigmatism.
2. LED lamp bead silver glue
1. The function of silver glue: fixing the chip and conducting electricity.
2. The main ingredients of silver glue: silver powder accounts for 75-80%, EPOXY (epoxy resin) accounts for 10-15%, and additives account for 5-10%. Public account: Shenzhen LED Network
3. Use of silver glue: refrigerate, defrost and stir thoroughly before use, because after the silver glue is left for a long time, the silver powder will precipitate, and if it is not stirred evenly, the performance of the silver glue will be affected.
3. LED lamp bead chip
1. The role of the chip: The chip is the main component of the LED Lamp and is a luminescent semiconductor material.
2. Composition of the wafer: The wafer is made of materials such as gallium phosphide (GaP), gallium aluminum arsenide (GaAlAs), gallium arsenide (GaAs), and gallium nitride (GaN). Its internal structure has unidirectional conductivity.
3. Chip structure: solder single-wire positive polarity (P/N structure) wafers and double-wire wafers. The size unit of the chip is mil. The bonding pads of the chip are generally gold pads or aluminum pads. The pad shapes include round, square, cross, etc.
4. Luminous color of the chip: The luminous color of the chip depends on the wavelength. Common visible light categories are roughly: dark red (700nm), deep red (640-660nm), red (615-635nm), amber (600-610nm) , yellow (580-595nm), yellow-green (565-575nm), pure green (500-540nm), blue (450-480nm), purple (380-430nm). Public account: Shenzhen LED Network
White light and pink light are a mixture of light effects. The most common ones are mixed with blue light + yellow phosphor and blue light + red phosphor.
5. Main technical parameters of the chip:
a. Volt-ampere characteristic diagram of the chip;
b. Forward voltage (VF): The voltage applied to both ends of the chip to make the chip forward. This voltage has a corresponding relationship with the chip itself and the test current. If VF is too large, the chip will be broken down.
c. Forward current (IF): The forward current generated by the chip after applying a certain voltage. The size of IF is related to the size of forward voltage. The working current of the chip is around 10-20mA.
d. Reverse voltage (VR): Reverse voltage applied to the wafer. Public account: Shenzhen LED Network
e. Reverse current (IR): refers to a leakage current generated by the chip after applying a reverse voltage. The smaller this current is, the better. Because a large current can easily cause reverse breakdown of the chip.
f. Brightness (IV): refers to the brightness of the light source. Unit conversion: 1cd=1000mcd
g. Wavelength: reflects the luminous color of the chip. Chips with different wavelengths emit different colors. Unit: nm
4. LED lamp bead gold wire
1. The role of the gold wire: to connect the chip PAD (soldering pad) and the bracket and enable it to be conductive.
The purity of the gold wire is 99.99% Au; the elongation rate is 2-6%. The sizes of the gold wire are: 0.9mil, 1.0mil, 1.1mil, etc.
5. LED lamp bead epoxy resin
1. The role of epoxy resin: protects the internal structure of the Lamp, can slightly change the luminous color, brightness and angle of the Lamp; and shapes the Lamp.
2. The encapsulating resin consists of four parts: glue A (main agent), glue B (hardener), DP (diffusion agent), and CP (colorant). Its main ingredients are epoxy resin (Epoxy Resin), acid anhydride (acid anhydride), high light diffusion filler (Light diffusion) and thermally stable dye (dye).