What is the structure and application of SMA connector?

What is the structure and application of an SMA connector? From the structural principle, the connector has three main parts, the contact pair, the insulator, and the shell.

a) Contact pairs of connectors. According to the structural form, it is divided into pinhole type, tuning fork type and curved reed type. Most of them include guide part, contact part, installation part and termination part.

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; to install additional devices for the connector.

c) Connector housing. Its main functions are mechanical and environmental protection and shielding; supporting the installation of insulators; connection and separation of headers; installation and fixed connectors; and fixing the lead-in ends of cables.

RF coaxial connectors are components installed in cables or instruments and are used to electrically connect transmission lines or separate electronic devices. It is a mechatronics series. There are many varieties and complete specifications, relying on the mechanical structure to ensure the electrical characteristics, which is essentially different from other low-frequency connectors. Most of the parts of RF coaxial connectors are processed by turning machines, and assembly is mostly done by hand. Product updates are slow.

The SMA RF connector is often thought of as a component attached to a cable or installed on an instrument as a component for electrical connection or separation of transmission lines. It is a mechatronics product. To put it simply, it mainly serves as a bridge.

SMA radio frequency connectors have many varieties and specifications, including more than 20 international general series, and more varieties and specifications. They rely on mechanical structure to ensure electrical characteristics. They are mechatronic products and are essentially different from other low-frequency connectors. The processing of radio frequency coaxial connector parts is mainly done by turning machines. The assembly requires a lot of manual work, making it difficult to automate assembly, and product updates are slow.

SMA radio frequency connector is an important part of the device and is a labor-intensive product with certain technical content. Reliability, failure modes and failure mechanisms are complex.

SMA connectors are generally a connection between pin and hole contacts. We know that the pins or terminals of components generally have a layer of plating, such as lead-tin alloy plating, pure tin plating, nickel plating, silver plating, silver-palladium alloy plating, gold plating, etc. So the contact between components is actually the contact between these plated metals. Of course, the conductivity of different coating metals is different, and the corresponding contact resistance is also different. Generally, gold has better conductivity, followed by silver. In the welding process, since welding is actually the process of forming an alloy, the alloy itself is a good conductor, so the reliability of the welding itself is relatively high, unless the welding is poor. However, the connection between connectors relies on the contact between surfaces, so it is easy to cause poor contact. The more specific reasons are analyzed below.

Whether the contact between two metal surfaces is good mainly depends on the material (different metals have different conductivities), contact pressure, and the actual contact surface junction. As for the type of materials, it has been mentioned above that the coating materials of general devices are basically made of good conductors. They have little impact on poor contact. At most, they affect the contact resistance (of course, furthermore, it also affects whether they are easily oxidized. ), so will not be discussed in more detail. Regarding the contact pressure of the connector, the connector relies on the elastic force of the hole contact to give a certain pressure to the pin contact. Generally, the greater the pressure, the better the contact.

Of course, generally small and thin hole contacts are unlikely to provide extremely large pressure. And if the elasticity of the hole contact piece itself is not good, the pressure will be small and the contact will not be so good. At the same time, if the hole contacts or pin contacts are deformed, the actual contact area will be small, which may lead to poor contact. At the same time, of course, the hole contacts or pin contacts of the connector are generally connected to plastic. If there are too many pins, it may cause the position of one or several contacts to be installed on the plastic part to be deviated. Therefore, the two When a connector is inserted, those offset contacts may not make good contact. The above is the structure and application of SMA connectors, as long as you continue to accumulate experience in practice.