Detailed Analysis Of The Five Major Raw Materials Of LED
Detailed Analysis of the Five Major Raw Materials of LED
The five raw materials of LED refer to: chips, brackets, silver glue, gold wires, epoxy resin chips
The composition of the wafer: consists of gold pads, P poles, N poles, PN junctions, and back gold layers (double pad chips have no back gold layers). The wafer is a PN combination composed of P-layer semiconductor elements and N-layer semiconductor elements rearranged by electron movement. It is also this change that enables the wafer to be in a relatively stable state. When a certain voltage is applied to the positive electrode of the wafer, the holes in the positive P region will continuously swim to the N region, and the electrons in the N region will move to the P region relative to the holes. While the electrons and holes move relative to each other, the electrons and holes pair up with each other to excite photons and generate light energy.
Main classification, surface emission type: most of the light is emitted from the surface of the wafer. Five-sided light-emitting type: more light is emitted from the surface and the side according to the light-emitting color, red, orange, yellow-green, pure green, standard green, blue-green, blue.
bracket
The structure of the bracket is 1 layer of iron, 2 layers of copper plating (good conductivity, fast heat dissipation), 3 layers of nickel plating (anti-oxidation), 4 layers of silver plating (good reflective, easy to wire) silver glue (because of many types, Let's take H20E as an example)
Also called white glue, milky white, conduction adhesion (baking temperature: 100°C/1.5H) silver powder (conduction, heat dissipation, fixed chip) + epoxy resin (cured silver powder) + thinner (easy to stir).
Storage conditions: Manufacturers of silver colloids generally store silver colloids at -40°C, and application units generally store silver colloids at -5°C.
The single agent is 25°C/1 year (in a dry place, ventilated place), the mixed agent is 25°C/72 hours (but due to other factors "temperature, humidity, and ventilation conditions" during online operations, in order to ensure the quality of the product, it is general Mixture use time is 4 hours)
Baking conditions: 150°C/1.5H
Stirring conditions: stir evenly in one direction for 15 minutes
Gold wire (take φ1.0mil as an example)
The gold wires used in LEDs are φ10mil, φ12mil, and the material of gold wires. The material of gold wires for LEDs generally has a gold content of 99.9%. The use of gold wires and its high gold content are soft, easy to deform, good electrical conductivity, and heat dissipation. Good characteristics, so that a closed circuit is formed between the chip and the bracket. (Conversion relationship: 1mil=0.0254mm1in=25.4mm)
Epoxy resin (taking EP400 as an example) composition: A and B two groups of ingredients:
A glue: is the main agent, composed of epoxy resin + defoamer + heat-resistant agent + thinner B agent: is a curing agent, composed of acid + release agent + accelerator Conditions of use:
Mixing ratio: A/B=100/100 (weight ratio) mixing viscosity: 500-700CPS/30C
Gel time: 120°C*12 minutes or 110°C*18 minutes
Available conditions: room temperature 25°C for about 6 hours, generally according to the production needs of the production line, we set its use condition as 2 hours.
Hardening conditions: initial hardening 110C-140°C 25--40 minutes
Post-hardening 100°C*6--10 hours (mobility adjustment can be made according to actual needs)
