What is SMA connector?

In terms of structural principles, connectors have three main parts: contact pairs, insulators, and shells.

a) Contact pairs of connectors. Divided into pinhole type, tuning fork type, and curved spring type according to structural form. Most of them include guiding parts, contact parts, installation parts, and termination parts.

b) The main function of the insulator of the connector is to support and fix the contact pairs, so that the contact pairs are insulated from each other; Install additional devices for connectors.

c) The casing of the connector. Its main function is to protect and shield machinery and the environment; Support the installation of insulators; Connection and separation of headrests; Install fixed connectors; Fixed cable entry end.

SMA connectors are generally used to connect pin contacts and hole contacts. We know that the pins or terminals of electronic components usually have a coating layer, such as lead tin alloy plating, pure tin plating, nickel plating, silver plating, silver palladium alloy plating, gold plating, and so on. So the contact between components is actually the contact between these coated metals. Of course, the conductivity of different coated metals varies, and the corresponding contact resistance also varies. Generally, gold has better conductivity, followed by silver. In the welding process, as welding is actually the process of forming an alloy, which is a good conductor in itself, the reliability of welding itself is relatively high, unless it is a poor welding. However, the connection between connectors relies on surface contact, which can easily lead to poor contact. The specific reasons for this are analyzed as follows.

The good contact between two metal surfaces mainly depends on the material (different metals have different conductivity), contact pressure, and actual contact surface structure. As for the types of materials, as mentioned above, the coating materials for general devices are basically made of good conductors, which have little effect on poor contact, at most affecting contact resistance (of course, it also affects whether it is easily oxidized), so we will not discuss them in more detail. Regarding the contact pressure of connectors, connectors rely on the elastic force of the hole contacts to apply a certain amount of pressure to the pin contacts. Generally, the greater the pressure, the better the contact. Of course, small and thin hole contacts are unlikely to provide excessive pressure. And if the elasticity of the contact piece itself is not good, the pressure will be small and the contact will not be as good. Meanwhile, if the hole contact or needle contact is deformed, it may also result in a smaller actual contact area, which may lead to poor contact. At the same time, the hole contacts or pin contacts of the connector are usually connected to plastic. If there are too many pins, it may cause one or several contacts to be misaligned on the plastic part. Therefore, when two connectors are inserted, those misaligned contacts may not make good contact.