1. Current-carrying capacity When selecting connectors, it is important to focus on their current-carrying capacity. To ensure the reliability and stability of the connectors, we should apply derating design and also consider the insulation voltage between the pins.   2. Structural dimensions The external dimensions of the connectors are crucial for product connections, especially in situations with limited space, such as connectors on single boards. We must avoid interference with other components. Depending on the available space and installation position, choose appropriate installation methods (front or rear installation) and connector shapes (straight, angled, T-shaped, circular, square). 3. Impedance matching Impedance matching is particularly critical for certain signals, especially RF signals. Strict adherence to impedance matching is necessary, as mismatching can cause signal reflections and affect signal transmission. Generally, signal transmission requirements for connector impedance are relatively lenient.   4. Shielding With the advancement of communication products, electromagnetic compatibility (EMC) is becoming increasingly important. Therefore, when selecting connectors, it is essential to ensure they have metal housings and are equipped with cable shielding layers. The shielding layers must be connected to the connector's metal housing to achieve effective shielding. An alternative method is to use injection molding to wrap the plug area with copper foil and weld the cable's shielding layer to the copper foil. 5. Misconnection prevention Preventing misconnections involves two aspects. Firstly, the connectors themselves should have misconnection prevention features since they can be erroneously connected due to rotation or misalignment. It's preferable to choose connectors with misconnection prevention features or arrange their positions to facilitate unique assembly. Secondly, when multiple signals use the same type of connector to reduce the number of materials, it is crucial to be mindful of the risk of inserting plug A into socket B. To avoid potential serious consequences (not just simple warnings), different types of sockets, such as male and female connectors, must be chosen.   6. Reliability Connectors primarily serve the purpose of signal transmission, so the connection points must be reliable. For instance, surface contact reliability is superior to point contact, and pinhole-type connectors are better than leaf spring-type connectors.   7. Versatility In the process of connector selection, it is preferable to choose materials that are as versatile as possible, especially among products within the same series. This reduces the variety of materials, increases purchase quantities, thus lowering costs and reducing supply risks.   8. Operating environment Connectors used in different environments have specific requirements, such as outdoor, indoor, high-temperature, high-humidity, salt spray, fungus, and cold conditions, each having unique connector demands.   9. Insertion and withdrawal frequency The number of times connectors can be inserted and withdrawn is limited, and when this limit is reached, the performance of the connector may decline. Connectors intended for frequent insertions and withdrawals should be selected with careful attention to their durability. 10. Live conditions Connector types should be chosen based on whether they will be used in live conditions or not. Pin-type and socket-type connectors may be more suitable for different live conditions.   11. Comprehensive consideration In the process of connector selection, different factors often interact with each other. Hence, during the selection process, it is essential to take a comprehensive approach and choose the most suitable connectors. The quality of connector selection will have varying degrees of impact on the product at different stages.