The reason why the gold plating color of USB connector products is different

Whether it is the terminal components or the shell, accessories and other components on the USB connector, they all need to be electroplated, and there are many options for electroplating materials and methods, among which gold plating is one of them. Today, the editor of Taichen Connector Factory will talk about the reasons for the difference in the color of the gold plating layer on the USB connector.

1. The content of alloy in the hard gold plating layer changes. In order to improve the hardness and wear resistance of the USB connector, hard gold plating technology is usually used. Gold-cobalt alloy and gold-nickel alloy are more commonly used. When the content of cobalt and nickel in the solution changes, the color of the gold-plated layer of the USB connector will change. If the cobalt content in the plating solution is too high, the color of the gold-plated layer of the USB connector will be reddish during electroplating; if the cobalt content in the plating solution is too much, the metal with too much nickel will be reddish; if the nickel content is too high, the color of the metal with too much nickel in the plating solution will be reddish; if the metal with more nickel in the plating solution will become lighter; if the content of this metal in the plating solution is too high, then this change will become lighter; in this way, the color of the metal will become lighter when changing in the plating solution. If the cobalt content in the plating solution is too high, then there will be a phenomenon that the color of the gold-plated layer of the same batch of USB connector products supplied to customers is different.

2. Impurities in gold-plated raw materials affect the tolerance of gold-plating liquid. When impurities brought by added chemical substances enter the gold-plating liquid, the color and brightness of the gold-plated layer of the USB connector will be affected soon. If it is affected by organic impurities, the gold-plated layer of the USB connector will become dark and flowery. The Hall slot test piece will be dark and the flowery position is not fixed. If metal impurities interfere, the effective range of current density will be narrowed. The Hall slot test shows that the current density of the test piece is not high or the flowery position is uncertain, while the Hall slot test shows that the current density is not too high or not too bright. The color change in its hole is more obvious.

Type-C Connector

3. When the current density is not reduced during electroplating of the slender pin, if the current density is generally used for electroplating, the coating on the tip of the needle is much thicker than that on the needle shaft. When observing the needle tip with a magnifying glass, it may sometimes appear in the shape of a match head. (See Figure 3) The gold coating at the upper and lower points of the head and neck is not up to standard in terms of bonding strength. This phenomenon is easy to occur during vibration gold plating.

4. Aging of the gold plating solution. If the gold plating solution is used for too long, excessive accumulation of impurities will inevitably lead to abnormal color of the gold layer.

5. When gold-plating, the plated parts are inserted into each other to ensure that the terminals of the USB connector have a certain degree of elasticity when used. In product design, most terminals are designed with a split groove on the mouth.

6. Incomplete pre-plating treatment For small pinhole parts, if trichloroethylene ultrasonic degreasing and cleaning cannot be performed immediately after the machining process is completed, the subsequent conventional pre-plating treatment will find it difficult to remove the dried oil in the hole, thereby greatly reducing the bonding strength of the coating in the hole.

7. When using nickel sulfamate plating solution to electroplating nickel, when the nickel content is less than the process technology range, it will affect the plating quality in the holes of small pinhole parts. If the gold content in the pre-plating solution is too low, the hole may not be plated with gold during gold plating. When the plated part enters the thickened gold plating solution, the nickel layer in the plated part hole becomes blunt, resulting in poor bonding strength of the gold layer in the hole.

8. The concentration of the blind hole is high, which exceeds the deep plating capacity of the electroplating process. Because the bottom of the split groove of the socket is still some distance away from the bottom of the hole, a blind hole will be formed objectively. There is also such a blind hole in the welding wire hole of the pin and the socket, which serves as a guide when welding the wire. When the hole diameter is small (usually less than 1 mm or even less than 0.5 mm) and the blind hole concentration exceeds the hole diameter, it is difficult for the plating solution to flow into the hole. Since the plating solution in the air inlet is not easy to discharge, the quality of the gold layer in the hole is difficult to guarantee.

USB2.0 Connector

9. The gold-plated anode area is too small. When the USB connector is small, the total surface area of ​​the single-slot plated part is relatively large. Therefore, when plating small pinhole parts, if there are many single-slot plated parts, the original anode area is not large enough. Especially when the platinum-titanium mesh is used for too long and wears out too much, the loss is too much, which reduces the effective area of ​​the gold-plated layer, thereby affecting the deep plating ability of the gold-plated layer, so that the plated part cannot be plated out in the hole.