Gold finger plating quality problems and measures

- Nov 17, 2018-

In connector plating, the contact to have higher electrical performance requirements, gold-plated technology has obvious important position in the connector plating. Now in addition to the part of the pick-up connectors using selective electroplating metalworking YiWai, the remaining amount of pinhole bulk hole still use a barrel plating gold-plated and vibration for plating. In recent years, the connector size to more and more miniaturization, the pinhole parts inside the hole of gold-plated quality problems become increasingly prominent, the user of the gold layer is becoming more and more high quality requirements, some users of the gold layer appearance quality has reached the very picky. Even in order to ensure the quality of connectors gold-plated layer binding force the total several kind of common quality problemIt is the key to improve the gold-plating quality of connectors. The reasons for these quality problems are discussed in the following sections.

Cause of quality problem of 2 gold plating layer

2.1 abnormal gold color

The color of the gold plating layer of the connector is inconsistent with the normal gold layer, or the gold layer color of different parts in the same matching product is different. The reasons for this problem are as follows:

2.1.1 influence of impurities of gold-plated raw materials

When joining plating solution chemical materials into impurities than gold plating liquid after tolerance will soon affect the color of the gold layer and brightness. If it is dark layer of organic impurities affect the cash and the phenomenon of hair flower, Richard slot specimen examination and dark hair flower position are not fixed. If the current density of metal impurity interference can cause narrow range, Richard trough experiments show current density of the specimens is low-end high-end plating not bright or not bright low-end plating. Is reflected in the plating pieces of the coating red or even angry, the more obvious the color change of the hole.

2.1.1 excessive gold-plated current density

As the total area of the plating bath part is larger than the actual surface area, the gold plating flow is too large, or the amplitude is too small when using vibrating electroplating, so that all or part of the gold plating in the bath has rough crystallization and the gold coating is red.

2.1.3 aging of plating liquid

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

2.1.4 changes in alloy content in hard gold deposits

In order to improve the hardness and wear resistance of the connectors, the gold-plating process of the connectors is usually hard gold plating.If the nickel content is too high, the metal color will become lighter.If this change is too large in the plating solution and different parts of the same matching product are not gold-plated in the same slot, the gold layer of the same batch of products provided to the user will be different in color.

2.2 the inner hole cannot be plated with gold

When the plating process of the pins or jacks of the connector is completed and the thickness of the outer surface of the plating part reaches or exceeds the specified thickness value, the inner hole coating of the welding line hole or jacks is very thin or even without gold layer.

2.2.1 during gold plating, the plating parts shall be inserted into each other

In order to ensure connector jack jack has certain elasticity, when plug is used in the product design most variety of jack has is a split groove in the mouth design. In the process of electroplating plating pieces evenly done part of the socket on the opening of each other together the inserted parts electric shielding each other causing hole plating hard.

2.2.2 the plating parts shall meet at the head and tail

In some types of connectors, the outside diameter of the pin rod is slightly smaller than that of the weld hole at the time of design, and the middle part of the plating process is formed by the insertion of the pin so that no gold can be deposited in the weld hole.

2.2.3 the concentration of the blind hole site is greater than the deep plating capacity of the electroplating process

Due to the bottom of the groove of the socket from the bottom of the hole and a distance, the distance objectively formed a blind holes. Also the pin and socket welding line also has such a blind hole in the hole, it is to provide the guiding role of wire welding. When these holes smaller aperture (often less than 1 mm or less than 0.5 mm) and blind hole concentration exceeds the aperture plating solution is very difficult to flow into the hole, flow into the hole of the plating solution and it is hard to flow, so the hole of the gold layer is difficult to guarantee quality.

2.2.4 plating anode area is too small

Connectors when the volume is small relatively single slot plating pieces of the total surface area is larger, in such a small pinhole if single slot when plated on more. The original anode area is not enough. Especially when platinum titanium net use of time is too long too much loss of platinum anode will reduce the effective area, this will affect the gilded deep plating ability, a hole will be plated.

2.3 poor adhesion of the coating

When the plating force of the connector is examined after plating, the front part of the tip of the pin may be encountered at the time of bending or the welding hole of the pin part may be peeled at the time of flattening.

2.3.1 incomplete treatment before plating

For small pinhole parts, if the ultrasonic oil removal of trichloroethylene is not applied immediately after finishing the machining process, it will be difficult to remove the dried oil in the hole during subsequent conventional preplating treatment, and the adhesion of the coating inside the hole will be greatly reduced.

2.3.2 incomplete activation before plating

In the connector substrate material extensive use of various types of copper alloy, the copper alloy of iron trace metals such as lead tin beryllium in general it is difficult to make its activation in the activation of fluid, if we do not adopt the corresponding acid activation, when the plating, these metal oxides with coating combined with very hard, so he created a coating of high temperature foaming phenomenon.

2.2.3 low concentration of plating solution

In the use of ammonia acid nickel plating, nickel plating solution when the nickel content is lower than the process range, small pinhole piece inside the hole of coating quality will be affected. If the gold content in the process of the plating solution is too low, so when gold plated hole could not gold plating, when entered with thick gold plating solution, plating layer hole metal plating nickel layer has a hole passivation as a result, the hole of the gold layer binding force is poor.

2.3.4 current density is not reduced in electroplating of slender pins