1、 Core metal components and working principle of LED beads
The metal components of LED beads mainly include four categories: chip electrodes, bonding wires, bracket pins, and solder pads, each of which undertakes key functions:
- 1. Chip electrode (metallization layer)
The materials are mostly aluminum, gold, etc., directly attached to the surface of the semiconductor chip, which is the first gateway for current to enter the chip. Through the electroluminescent effect, electrical energy is converted into light energy, and its conductivity and oxidation resistance directly affect the forward voltage and luminous efficiency of the lamp bead.
- 2. Bonding wire (gold wire/copper wire/alloy wire)
As the "bridge" between the chip electrodes and the support pins, it is responsible for conducting the current of the chip to the external circuit. The purity of the material and the welding strength directly determine the impact resistance of the lamp bead, which is a high-risk area for open circuit faults of the lamp bead.
- 3. Bracket metal pins/cup body
It is not only the structural carrier that carries the chip, but also the main heat dissipation channel of the lamp bead. The material is mostly copper, iron, nickel plating or aluminum alloy. The thermal expansion coefficient and thermal conductivity directly affect the heat stress resistance and heat dissipation efficiency of the lamp bead.
- 4. Solid crystal solder pads/solder balls
The mechanical fixation and electrical connection between the chip and the bracket are determined by the welding quality, which determines the anti drop and anti temperature cycling ability of the lamp beads. Virtual soldering and oxidation are common causes of poor contact between the lamp beads.
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