Detailed explanation of the internal structure of LED light-emitting diodes

LED lamps are mainly composed of five materials: brackets, silver glue, chips, gold wires, and epoxy resin.

1. Brackets:

1) Function of brackets: used for conduction and support
2) Composition of brackets: brackets are formed by electroplating bracket materials, and from the inside to the outside, they are composed of five layers: material, copper, nickel, copper, and silver.
3) Types of brackets: brackets with cups are used for focusing type, and flat-head brackets are used for large-angle diffuse light type lamps.
A. 2002 cup/flat head: This type of bracket is generally used for materials that do not have very high requirements for angle and brightness . Its pin length is about 10mm shorter than other brackets. The pin spacing is 2.28mm
B. 2003 cup/flat head: Generally used for lamps above φ5, with exposed pin lengths of +29mm and -27mm. The pin spacing is 2.54mm.
C. 2004 cup/flat head: used for lamps around φ3, with the same pin length and spacing as the 2003 bracket.
D. 2004LD/DD: used to make blue, white, pure green, purple lamps, can be welded with two wires, and the cup is deeper.
E. 2006: Both poles are flat-headed, used to make flashing lamps, fix ICs , and weld multiple wires.
F. 2009: used to make two-color lamps, two chips can be fixed in the cup, and three pins control polarity.
G. 2009-8/3009: used to make three-color lamps, three chips can be fixed in the cup, and four pins.

2. Silver glue

The function of silver glue: fix the chip and conduct electricity.
The main components of silver glue: silver powder accounts for 75-80%, EPOXY (epoxy resin) accounts for 10-15%, and additives account for 5-10%.
Use of silver glue: Refrigerate, thaw and stir thoroughly before use, because the silver powder will precipitate after the silver glue is left for a long time. If it is not stirred evenly, it will affect the performance of the silver glue.

3. Chip: The structure of

light-emitting diodes and LED chips
1) The role of the chip: The chip is the main component of LED Lamp and is a light-emitting semiconductor material.
2) The composition of the chip: The chip is made of materials such as gallium phosphide (GaP), gallium aluminum arsenide (GaAlAs) or gallium arsenide (GaAs), gallium nitride (GaN), and its internal structure has unidirectional conductivity.
3) The structure of the chip:
single-line positive polarity (P/N structure) chip, double-line chip. The size unit of the chip: mil
The chip pad is generally a gold pad or an aluminum pad. The shape of the pad is round, square, cross, etc.
4) The luminous color of the chip:
The luminous color of the chip depends on the wavelength. The classification of common visible light is 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).
White light and pink light are a mixed effect of light. The most common is a mixture of blue light
+ yellow phosphor and blue light + red phosphor. 5) The main technical parameters of the chip:
A. The 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 conduct. 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 conduction current generated by the chip after a certain voltage is applied. The size of IF is related to the size of the forward voltage. The working current of the chip is about 10-20mA.
D. Reverse voltage (VR): reverse voltage applied to the chip.
E. Reverse current (IR): refers to a leakage current generated by the chip after the reverse voltage is applied. The smaller this current is, the better. Because a large current can easily cause the chip to be reversely broken down.
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 have different luminous colors. Unit: nm
H. Light: It is a type of electromagnetic wave. Electromagnetic waves with a wavelength of 0.1mm-10nm are called light.
Light can be divided into: wavelengths greater than 0.1mm are called radio waves; 760nm-0.1nm are called infrared light; 380nm-760nm are called visible light; 10nm-380nm are called ultraviolet light; wavelengths less than 10nm are X-rays.

4. Gold wire:

The role of the gold wire: connect the chip PAD (solder pad) and the bracket, and make it conductive.
The purity of the gold wire is 99.99% Au; the elongation is 2-6%, and the size of the gold wire is: 0.9mil, 1.0mil, 1.1mil, etc.
5. Epoxy resin:
The role of epoxy resin: protect the internal structure of the lamp, slightly change the light color, brightness and angle of the lamp; shape the lamp.
The encapsulation resin includes four parts: A glue (main agent), B glue (hardener), DP (diffuser), and CP (colorant). Its main components are epoxy resin (Epoxy Resin), acid anhydride (acid anhydride), high light diffusion filler (Light diffusion) and thermally stable dye (dye)

6. Mold:

The mold is the mold for lamp forming, generally in round, square, tower, etc. The depth of the bracket is determined by the height of the mold. The mold needs to be stored in a clean environment below room temperature, otherwise it will affect the appearance of the product.