Gold wire, silver wire, alloy wire, and copper wire refer to the wires that connect the electrical connection between the LED chip (also known as the chip) and the external pins. Once this wire has a problem, the entire LED product will be scrapped. This can be seen The importance of a wire. So the question is, what is the difference between gold wire, silver wire, copper wire, and alloy wire?
Gold wire: No need to introduce more. It has stable performance and high price. In the high-end packaging field, the main function of LED is to brighten and change color. Gold is generally used to prevent oxidation and ensure stable contact. The number of gold wires (actually the chip electrodes) has little to do with the size of the chip. There are also double-electrodes and single-electrodes for the 24mil. The number of gold wires is mainly related to the process and characteristics of the chip. Generally, single-electrode chips have a vertical structure, and the bottom can be directly energized, so there is one less electrode. The electrode is directly built on the substrate. This kind of chip is usually red and yellow. However, most of the double wires are of horizontal structure, the positive and negative poles are made on the same plane, and the bottom substrate is insulated. Generally, blue and green chips are used for this kind.
Alloy wire (also known as silver alloy wire): Alloy wire is a product that replaces traditional gold wire in the LED industry. In recent years, the price of gold has continued to rise, and the price of gold wire used for LED packaging has also continued to increase. At the same time, the price of LED products has continued to decline. Therefore, cheap alternatives-alloy wires, will come out at the right time. The composition of the alloy wire is mainly single crystal silver, and the general content is 90%-99%. The gold wire is doped with a large amount of silver and palladium and other components to keep the IMC stable are various trace elements.
The price is cheaper, lower than the price of gold wire, and higher than the price of copper wire;
When welding with silver-plated brackets, the weldability is better;
Immature application on old-fashioned wire bonding equipment or nitrogen protection can be used;
There is a certain degree of oxidizing. This is the same shortcoming as copper wire, and shielding gas is used, but it seems that only nitrogen is sufficient.
Silver wire: Silver wire is better stored than copper wire (copper wire must be sealed, and the storage period is short, the silver wire does not need to be sealed, the storage period can reach 6-12 months)
Silver wire:
The hardness is soft, and the adjustment of machine parameters is not great;
The current price is lower than gold wire and higher than copper wire;
No gas protection is required during wire bonding;
The tensile force of silver wire is not as strong as that of gold wire, but the light decay time is better for silver than gold, because silver does not absorb light.
Copper wire: including single crystal copper wire and palladium-plated copper wire
The price of copper wire is low, and the cost of various specifications of copper wire used in wire bonding is only 1/3-1/10 of that of gold wire, which has huge application potential in reducing costs;
The high rigidity of copper wire relative to gold wire makes it more suitable for small wire bonding;
Copper wire is easily oxidized and the bonding process is unstable;
The physical parameters such as hardness and yield strength of copper wire are higher than those of gold and aluminum.
Attachment: The difference between single gold wire and double gold wire (four gold wires) is the number of wires in the LED lamp bead. In the LED lamp bead, you will see that there are gold wires soldered inside, and there are two gold wires ( One on one side) is a single gold wire, and four wires (two on one side) are double gold wires. Regardless of single-line or dual-line, one side is positive and the other is negative. For example, the double gold wire indicates that the chip has four electrodes, the chip size is large, and the thermal resistance is low. Currently on the market there are generally two lamps of 0.5W and 0.75W (also known as lamp beads of less than watt), and four of them are high-power light sources such as 1W, 2W, 3W, and 5W. Two lamp beads that can directly achieve 1W have a large heat dissipation capacity, and poor heat dissipation will definitely affect the life. In fact, only the LED chip product manufacturers know which products use what material leads, which is difficult for ordinary people to distinguish with the naked eye, and even some LED chips are blocked by the phosphor layer outside, and they are not visible at all.
