The color of the connector's gold plating layer is inconsistent with the normal gold layer color, or there is a difference in the gold layer color of different parts in the same supporting product. The reason for this problem is:

1. Impurities in gold-plating raw materials can quickly affect the color and brightness of the gold layer when the impurities brought in by the chemical materials added to the plating solution exceed the tolerance level of the plating solution. If organic impurities affect the gold layer, it may cause darkening and blooming, and the position of darkening and blooming is not fixed during the inspection of the Haoer groove test piece. If metal impurities interfere, it will cause the effective range of current density to narrow, The Hao Er groove test shows that the low end of the current density of the test piece is not bright, or the high end is not bright, and the low end is not plated. This reflects that the coating on the plated part turns red or even black, and the color change in the hole is more obvious.

2. The current density of gold plating is too high. Due to an error in calculating the total area of the plating bath parts, the value is greater than the actual surface area, resulting in an excessive amount of gold plating current. Alternatively, when vibration plating is used, the amplitude is too small, resulting in rough crystallization of all or part of the gold plating layer in the bath and visual redness of the gold layer.

3. If the gold plating solution is aged and used for too long, excessive accumulation of impurities in the plating solution will inevitably cause abnormal color of the gold layer.

4. When the alloy content in the hard gold coating changes, in order to improve the hardness and wear resistance of connectors, the gold plating process is generally used for connectors. Among them, gold cobalt alloy and gold nickel alloy are more commonly used. When the cobalt and nickel content in the plating solution changes, it will cause the color of the gold coating to change. If the cobalt content in the plating solution is too high, the color of the gold coating will turn red; If the nickel content in the plating solution is too high, the metal color will become lighter; If the change in the plating solution is too large and different parts of the same supporting product are not gold-plated in the same tank, it will lead to the phenomenon that the gold layer color of the same batch of products provided to users is not the same.

5. When the plating process for pins or sockets of connectors that cannot be plated with gold is completed, and the outer surface thickness of the plated part reaches or exceeds the specified thickness value, the inner hole coating of the welding wire hole or socket is very thin or even without a gold layer.

6. When plating gold, the plated parts are inserted into each other to ensure that the sockets of the connectors have a certain degree of elasticity during insertion and removal. In product design, most types of sockets are designed with a groove at the mouth. During the plating process, some of the sockets of the plated parts are constantly flipped and inserted together at the opening, causing the power lines of the opposite parts to screen each other, making it difficult to electroplate inside the holes.

7. When plating gold, some types of connectors are designed with pins that are slightly smaller in outer diameter than the aperture size of the welding wire hole. During the plating process, some pins will form a head to tail connection, resulting in no gold plating inside the welding wire hole The above two phenomena are more likely to occur during vibration gold plating (see diagram).

8. The concentration of blind holes exceeds the deep plating capacity of the electroplating process due to the fact that there is still a distance between the bottom of the slot in the socket and the bottom of the hole, which objectively forms a blind hole. Similarly, there is a blind hole in the solder wire holes of the pin and socket, which provides a guiding effect for wire welding. When the aperture of these holes is small (often less than 1mm or even less than 0.5mm) and the blind hole concentration exceeds the aperture, it is difficult for the plating solution to flow into the hole, The plating solution flowing into the hole is difficult to flow out, so the quality of the gold layer inside the hole is difficult to guarantee.

9. When the area of the gold-plated anode is too small, the total surface area of a single slot plated piece is relatively large when the volume of the connector is small. Therefore, if there are more plated pieces in a single slot when plating small pinhole pieces, the original anode area will appear insufficient. Especially when the platinum titanium mesh is used for too long and the platinum loss is too much, the effective area of the anode will decrease, which will affect the deep plating ability of the gold, and the hole of the plated piece will not be able to be plated.

10. Poor adhesion of the plating layer. When inspecting the adhesion of the plating layer of the connector after plating, sometimes there is peeling on the plating layer when the front of the needle end of some pins is bent or when the welding wire hole of the pin hole component is flattened. Sometimes, during high temperature (2000 hours) testing, it is found that there are very small bubbles in the gold layer.

11. Incomplete pre-treatment before plating. For small pinhole parts, if trichloroethylene ultrasonic oil removal and cleaning cannot be immediately used after the machining sequence is completed, then the subsequent conventional pre-treatment before plating is difficult to remove the dry oil stains in the holes, which will greatly reduce the adhesion of the coating inside the holes.

12. Incomplete activation before substrate plating. Various types of copper alloys are widely used in the substrate material of connectors. Trace metals such as iron, lead, tin, and beryllium in these copper alloys are difficult to activate in general activation solutions. If they are not activated with corresponding acids, the oxides of these metals are difficult to combine with the coating during electroplating, resulting in high-temperature foaming of the coating.

13. Low concentration of plating solution. When using ammonia sulfonic acid nickel plating solution for nickel plating, when the nickel content is lower than the process range, the quality of the coating in the hole of small pinhole parts will be affected. If the gold content in the pre plating solution is too low, there is a possibility that gold cannot be plated in the hole during gold plating. When the plating part enters the thickened gold plating solution, the nickel layer in the hole of the hardware layer has been passivated, resulting in poor bonding force of the gold layer in the hole.

14. When electroplating slender pins, the current density is not reduced. When electroplating slender pins, if remote current density electroplating is used as usual, the coating on the needle tip will be much thicker than on the needle rod. When observed under a magnifying glass, the needle tip may sometimes deviate from the shape of the match head (See Figure 3) The plating layer on the head and neck, which is the gold plating layer at the top of the front end of the pin and a point behind it, fails the adhesion test. This phenomenon is prone to occur during vibration plating.

15. Incorrect adjustment of vibration frequency for vibration gold plating. When using vibration electroplating connectors, if the vibration frequency is not adjusted correctly during nickel plating, the plating part may jump too fast, and it is easy to form a double layer of nickel, which has a significant impact on the adhesion of the coating.