The importance of contact coatings in connectors

Connectors are important components in the electronic component industry. It is not difficult for electronics engineers to find that most connectors are coated with special coatings. Most people have a common problem in mind. What is the special significance of plated connectors? The contact coating of the connector can not only protect the connector from environmental corrosion, improve the durability and abrasion resistance of the connector, but also help to establish and maintain a stable connector impedance from the aspect of electrical performance. The specific performance is as follows:

1. Anticorrosive function of connector coating

The primary consideration for connectors is protection against corrosion. Most contact springs of electrical connectors are made of copper alloys. In the typical working environment of electrical connectors, copper alloys are susceptible to corrosion such as oxidation and sulfuration. In fact, contact plating is used to isolate contact springs from the working environment to prevent copper corrosion. Of course, the coating material must not be damaged (at least to a harmful degree) in its working environment. As an important function of anti-corrosion, optimizing the interface is a consideration in selecting the appropriate contact coating material.

2. Connector plating helps improve mechanical properties

Parameters related to mechanical properties are the main factors affecting the durability or wear of the coating and the matching force. These factors to be considered are two different views under the same basic effect, that is, the multi-point contact interface is a cold welding share during the relative movement. The most important mechanical properties include the hardness, ductility, and coefficient of friction of the coating material. All these characteristics depend on the inherent characteristics of the coating material and the processing technology used.

3. Connector plating helps improve electrical performance

The optimization of electrical performance can be considered from the following aspects: control of existing and upcoming films on the contact plating surface. One of the main requirements for the electrical performance of electrical connectors is to establish and maintain a stable connector impedance. To achieve this, a metal contact interface is required to provide this inherent stability. Establishing such a contact interface requires that the surface film can be avoided or cracked during the contact fit. These two different choices clearly define the difference between precious or rare metals and ordinary metals.

4. Characteristics of precious metal coatings for connectors

To varying degrees, precious metal coatings (such as gold, palladium, and their alloys) are essentially free of surface films. For these coatings, it is relatively simple to make metal contact at the interface, as it only needs to accompany the movement of the contact surface with the object during the mating process. This is usually easy to achieve. In order to maintain the stability of the contact interface impedance, the connector design requires that attention be paid to maintaining the noble metal properties of the contact surface to prevent external factors such as contaminants, base metal diffusion, and contact wear.

5.Characteristics of metal coatings commonly used in connectors

Ordinary metal coatings, especially tin or tin alloys, are naturally covered by an oxide film. The role of the tin contact coating is because the oxide layer is easily damaged during the matching process, so that metal contact can be easily established. The design requirements of electrical connectors are to ensure that the oxide film is broken when the connectors are mated, and that the contact interface is no longer oxidized during the life of the electrical connector bracket. Reoxidative corrosion is the most important degradation mechanism of tin contact coatings in abrasion corrosion. The silver contact coating is preferably regarded as a common metal coating because it is susceptible to corrosion by sulfides and chlorides. Because of the formation of valve warpage, nickel plating is usually considered as a common metal.