What are the factors that affect the transmission performance of the terminal?

Tin plating is a common electroplating process currently used in connectors. This process has the following disadvantages: First, heating the plating tin to a high temperature or storing it for a long time will lead to reduced weldability and increased contact resistance. This phenomenon is mainly due to the maintenance of the metal intermetallic compound between the plating and the base metal.

Secondly, the contact material of the connector plating has greater surface friction than the metal plating, which leads to an increase in the insertion force of the connector. This defect is particularly obvious in the use of multi-wire connectors. Therefore, for the electroplating of multi-wire connectors, try to choose some new electroplating processes. While achieving connection transmission, reduce the insertion force of the connector. For example, the current gold plating process is a relatively good electroplating process.

From the perspective of microscopic physics, any smooth-looking surface is rough and uneven, so the contact surface of the terminal is not actually a surface contact, but a point contact. In addition, the surface of the metal is generally covered with non-conductive oxide film and other types of film layers, so only a small part of the film layer can be crushed or voltage-breakdowned in the actual contact surface. Only these places can achieve true electrical contact, and we call these contact points "conductive spots". Most of the contact is through the film layer. So when the current passes through the interface of the two contacts, the current will flow through those extremely small conductive spots, so the current line near the conductive spot will inevitably shrink. This also causes the current line to shrink near the conductive spot, increasing the path length of the current flow and reducing the effective conductive area, resulting in local attachment resistance, which is called "contraction resistance". Improving the finish of the terminal surface can also improve the transmission performance of the terminal.

At present, the standards for testing the quality of the coating are:
1) Check the thickness of the coating. This method is to judge the quality of the coating by controlling the thickness of the coating.
2) Tested by corresponding salt spray test.

The positive pressure of connector terminal refers to the force generated on the contact surface of the connector plug terminal and the socket terminal and perpendicular to the contact surface. It is an important indicator affecting the performance of the connector. This factor directly affects the insertion force and electrical performance of the terminal.

During the use of the terminal, the main problem is the unstable control of the insertion force between the terminal and the terminal. The reason is that the positive pressure of the terminal spring is unstable, which causes the resistance of the terminal contact surface to increase, resulting in an increase in the temperature rise of the terminal, causing a series of problems such as ablation of the connector and loss of conductive function. In severe cases, it will cause serious consequences such as burning due to the increase in heat.

The crimping quality directly affects the transmission quality of the terminal. The crimping engagement length and crimping height have a great influence on the crimping quality. The mechanical strength and electrical performance of a tighter crimping are better than those of a looser crimping, so the size of the crimping section should be strictly controlled. There are many factors that affect the crimping effect of the terminal and the wire: First, any type of terminal has a certain range of wire diameters that it can adapt to, and the wire diameter is an important factor affecting the crimping quality.

Secondly, the wire itself is also worth studying. Domestic and foreign products have their own characteristics. In actual production, the following principles should be followed:
1) The wire diameter of the wire should be consistent with the tail of the terminal
2) The length of the wire stripping part should be moderate
3) Choose a suitable crimping die
4) After the terminal is crimped, a latrori test should be performed.

The way to inspect the terminal crimping is to inspect the crimping profile of the terminal and the pull-off force of the terminal. The profile can intuitively judge the effect of the crimping. The crimping result must not have defects such as copper wire leakage and bottoming. The pull-off force can judge the reliability of the crimping.