There are a wide variety of commonly used connectors, such as BNC, F-type and other common connectors, as well as MUX and other connectors. Among so many types, what kind of points should be followed when selecting models, mainly including fourteen standards such as current carrying capacity, impedance matching, shielding, versatility, cost, and availability.
1. Current carrying capacity: When selecting the connector for the power signal, pay more attention to the current carrying capacity of the connector, adopt a derating design, and pay attention to the insulation withstand voltage between the pins.
2. Structural size: The external size of the connector is very important. There are certain space restrictions for the connection in the product, especially the single-board connector, which cannot interfere with other components. Choose the appropriate installation method according to the use space and installation position (installation includes front installation and rear installation, installation and fixing methods include rivets, screws, collars or quick locking of the connector itself, etc.) and shape (straight, curved, T type, round, square).
3. Impedance matching: Some signals have impedance requirements, especially RF signals, which have stricter impedance matching requirements. When the impedance does not match, it will cause signal reflection, which will affect signal transmission. Generally, signal transmission has no special requirements on the impedance of the connector.
4. Shielding: With the development of communication products, EMC has been paid more and more attention. When choosing a connector, it needs to have a metal shell. At the same time, the cable needs to have a shielding layer. The shielding layer should be connected with the metal shell of the connector. To achieve the shielding effect, the injection molding method can also be used to wrap the plug part with copper skin, and the shielding layer of the cable and the copper skin are welded together.
5. Anti-mis-insertion: There are two aspects to prevent mis-insertion: on the one hand, the connector itself, which rotates 180 degrees, and the misaligned connection leads to wrong signal connection. Adjust the relative position relationship of the connectors to make the assembly unique; on the other hand, in order to reduce the types of materials, several signals use the same connector, at this time, it is possible to insert the A plug into the B plug, and you need to pay attention at this time. , if such a situation will cause serious consequences, the A and B interfaces must be selected as different types of sockets.
6. Reliability: The connector is used to connect the signal, so the connection part should be reliable (for example, surface contact is better than point contact, pinhole type is better than leaf spring type, etc.).
7. Versatility: In the selection process of connectors, it is necessary to choose common objects as much as possible, especially among products of the same series, the selection of connectors has strong versatility, reducing the types of materials, increasing the quantity and reducing costs, while reducing supply. cargo risk.
8. Use environment: When the connector is used in outdoor, indoor, high temperature, high humidity, salt spray, mold, cold and other environments, there are special requirements for the connector.
9. Locking function: In order to prevent the connector from falling off when mating and to ensure good contact, the connector needs to have a locking function.
10. Cost: Cost is also an important factor in the selection process. With the increasingly fierce market competition, the appropriate selection of connectors, the cost of the connector itself and the processing cost need to be comprehensively considered.
11. Availability: The supply of connectors will be affected by many factors. General-purpose connectors are better than non-universal connectors, and domestically produced ones are better than foreign ones.
12. Plugging frequency: The plugging and unplugging of the connector has a certain life. After the number of plugging and unplugging reaches the limit, the performance of the connector will decline. When some signal interfaces need to be plugged and unplugged frequently, more attention should be paid to the connection when selecting a connector. The number of times of plugging and unplugging the device.
13. Consideration of electrification: choose a pin-type or female-type connector according to whether it is often electrified or not.
14. Comprehensive consideration: In the process of selecting connectors, various factors are not independent and often interact with each other. Therefore, we must comprehensively consider in the process of connector selection, select the most suitable connector, and choose whether it is good or bad. The product will be affected to different degrees at different stages.