During the process of plug gold plating, avoid plating solution and porosity problems!

With the rapid development of the field of electronic design, the application of printed boards is widely used in people’s lives, and the application range of gold plating is also expanding and the requirements are getting higher and higher.

The electroplating master will be troubled by various failures during the gold plating process of the plug. This article mainly analyzes common faults and formulates corresponding improvement measures for your reference.

1. Leakage of plating and rapid consumption of plating solution

1. Missing plating

The reason for the leakage plating is caused by the current density of the plug part.

(1) Generally, when there is a disconnection between the electrical connection point of the frame wire and the plug, the current will not be applied to the plug and cause leakage of plating.

(2) The large contact resistance at the electrical connection point causes the current density of the plug to be too low, causing underplating and leakage.

Analyze the reasons as follows: 1. The clip is not firmly clamped; 2. There is residue of solder mask at the electrical connection point; 3. The rust of the clip will cause ohmic contact.

2. The plating solution is consumed too fast

(1) Rework of unqualified plating during operation requires more gold consumption, which will consume a large amount of plating solution.

(2) The part of the bare copper other than the plug is easy to absorb gold, and the area of ​​the bare copper is scattered, leading to the possibility of blindness in applying current. This is the main reason for black burn and missing plating.

3. Process improvement of plug gold plating

Change the electrical connection method to ensure that the circuit loop is unobstructed. Cut the corners of the side where the plug of the printed board is located, and paste white tape to isolate the plating solution. This can ensure that there is no current passing through or isolated from the plating solution except for the plug, and it is not easy to be plated with gold.

2. Gold plating porosity is too high or too low

The porosity of gold-plated gold-plated printed circuit board plugs is mainly affected by pretreatment and nickel plating, copper surface and gold plating.

1. The influence of pretreatment and nickel plating

Plugs nickel plating must be chemically treated before gold plating to remove the oxide layer, stains or tiny solder mask on the copper surface. At the same time, the flatness of the copper surface is required Strengthening, this is conducive to the adhesion of the nickel-gold coating and the compactness of the coating.

But when the grinding wheel used is too thick and the grinding pressure is too high, it will affect the coverage of the nickel-gold coating, which will easily lead to deviations in the porosity test.

Under normal circumstances, the quality of nickel plating has a direct impact on the quality of gold plating. When the nickel plating layer has pinhole roughness, the porosity of the plug gold plating layer will have a big problem.

In areas with high current density, nickel deposits faster, the compactness after plating is poor, and the problems of plating pinholes and even rough plating are prone to occur.

Especially some boards with uneven distribution of plugs, and plugs on the edge are more prone to this problem.

In addition, the thickness of the nickel plating layer also affects the porosity of gold plating. The thicker the plating layer, the better the coverage of the copper surface of the substrate, and the better the coverage of the gold plating layer, and vice versa, the more unfavorable the problem of porosity of the plug.

2. The influence of copper surface

In the printed circuit board manufacturing process, many operations will have a certain impact on the flatness of the copper surface.

Under normal circumstances, when scratches occur on the plug or any pits that affect the flatness of the copper surface, it is difficult to completely cover the copper surface with nickel plating and gold plating, which will cause problems in detecting porosity.

The plug of the printed board is generally designed at the place where the current density is higher during electroplating, that is, the edge of the board, which is often the key factor that causes the problem.

Electric copper layer is prone to roughness, pinholes or even scorching and blackening of the plating on the edges. Especially when the copper sinking process is used, in order to make the hole wall copper When a certain thickness is reached, the current density used in electroplating is usually higher, which is more likely to cause poor flatness of the copper plating layer.

In addition, the flatness of the copper plating layer is also affected by factors such as organic impurities and the content and content of additives in the plating solution.

When there is a flatness problem in the copper-plated layer, it is generally impossible to make the surface smooth and flat only by polishing, so the problem of gold-plated porosity in this part is inevitable.

Through the above analysis, we hope to help you quickly and accurately find the cause of the failure, thereby improving the wear resistance of the printed board plug.