There are several treatment processes for the surface of LED circuit board: smooth board (without any treatment on the surface), rosin board, OSP (organic solder protective agent, slightly better than rosin), tin spraying (lead-tin and lead-free tin), gold-plated board, gold-deposited board, etc. These are more noticeable.
Difference between gold deposition process and gold plating process
Gold-plated plate: golden white, with poor welding, skin effect is not conducive to high-frequency signal transmission,
Disadvantages: the gold surface is easy to oxidize, and the gold wire is easy to be short, and the welding bonding force is not strong.
Gold plate: golden yellow, good weldability, skin effect has no influence on signal.
Advantages: it is not easy to oxidize, does not produce gold wire, and has good welding resistance and bonding force.
Gold is deposited by chemical deposition, and a layer of coating is formed by chemical oxidation-reduction reaction, which is generally thick. It is one of the deposition methods of chemical nickel gold layer, which can reach a thick gold layer.
Gold plating is based on the principle of electrolysis, also called electroplating. Most other metal surface treatments are electroplating.
In actual product applications, 90% of gold plates are gold-plated plates, because poor weldability of gold-plated plates is his fatal shortcoming, and it is also the direct cause that many companies give up the gold-plated process!
Gold deposition process deposits nickel-gold coating with stable color, good brightness, smooth coating and good solderability on the surface of printed circuit. It can be basically divided into four stages: pretreatment (degreasing, micro-etching, activation and post-immersion), nickel precipitation, gold precipitation and post-treatment (waste gold washing, DI washing and drying). The thickness of gold deposit is 0.025-0.1um.
Gold for display circuit boards should be used for surface treatment of circuit boards, because gold has strong conductivity, good oxidation resistance and long service life. It is commonly used in key boards, gold finger boards, etc. The fundamental difference between gold-plated boards and gold-plated boards zui is that gold-plated boards are hard gold (wear-resistant), while gold-plated boards are soft gold (not wear-resistant).
1. The crystal structure of gold deposition is different from that of gold plating. The thickness of gold deposition is much thicker than that of gold plating, and gold deposition will be golden yellow and yellower than that of gold plating (this is one of the ways to distinguish gold plating from gold deposition). Gold plating will be slightly white (the color of nickel).
2. The crystal structure of gold deposition is different from that of gold plating. Compared with gold plating, gold deposition is easier to weld and will not cause poor welding. The stress of the gold plate is easier to control, and it is more conducive to bonding processing for bonded products. At the same time, just because gold sinking is softer than gold plating, gold sinking plate is not wear-resistant as a gold finger (the disadvantage of gold sinking plate).
3. Only the pad of the gold-depositing plate has nickel gold, and the signal transmission in the skin effect is in the copper layer, which will not affect the signal.
4. Compared with gold plating, gold deposition has a denser crystal structure and is not easy to produce oxidation.
5. With the increasing requirement of PCB processing accuracy, the line width and spacing have reached below 0.1mm. Gold plating is easy to cause short circuit of gold wire. Only the pad of the gold plate has nickel and gold, so it is not easy to produce gold wire short circuit.
6. Only the pad of the gold sink plate has nickel gold, so the combination of solder resist on the line and copper layer is stronger. Engineering compensation will not affect the spacing.
7. For boards with high requirements, the flatness requirement is better, and gold sinking is generally adopted, which generally does not cause black pad phenomenon after assembly. The flatness and service life of gold-plated plate are better than those of gold-plated plate.
Therefore, at present, most factories have adopted gold sinking technology to produce gold plates. However, the gold deposition process is more expensive (with higher gold content) than the gold plating process, so there are still a large number of low-priced products using the gold plating process.
