First, the use of environmental conditions:
1. Ambient temperature - refers to the working environment of the product, which should be used within the specified ambient temperature of the product. Even if the external ambient temperature is not high, if the product works in the chassis, the poor heat dissipation conditions and the heat of other components will cause the ambient temperature of the product to be much higher than the external ambient temperature. Exceeding the specified ambient temperature will damage the metal plating or insulator, and too low temperature will also crack the insulator, which will eventually reduce the performance or function of the connector.
2. Moisture or water - Moisture or water will form a water film on the surface of the insulator, which will reduce the insulation performance and even cause miscommunication between adjacent contacts. Generally, connectors that are used in high humidity or under water conditions for a long time should use sealed connectors.
3. Low air pressure: The air pressure will decrease under high-altitude conditions (except in the constant air pressure sealed chamber). When the product is under low air pressure, the dielectric withstand pressure of the product will decrease. If the transmitted voltage is higher than the product technical conditions, there will be Electrical breakdown may occur, resulting in failure.
4. Corrosive environment: refers to the atmosphere around the product, such as the sea with severe salt spray, the storage warehouse of chemical raw materials with severe acid and alkali, etc. These conditions will cause corrosion and erosion on the metal parts and insulators of the connector. Pay attention to special requirements to the manufacturer or choose products that can meet your requirements. At the same time, it should be noted that the plastic parts of individual connectors are not resistant to solvents such as banana water, benzene, acetone, etc. Please pay attention to the regulations in the product samples.
5. Mechanical conditions: refers to mechanical effects such as vibration, impact, collision, acceleration, etc., which are selected according to the parameters in the product sample. Generally speaking, the mechanical parameters of twist needles in similar products are higher and easy to guarantee. Note that in actual use, after the cable is terminated with the contact piece, the cable should be fixed with clips or other methods. The cable that is too long and has no fixing measures will endanger the cable under external effects such as vibration or shock. In severe cases, it will cause connector damage and cable breakage and other faults.
2. Termination method
Termination method refers to the connection method between the cable and the connector. Generally, there are many kinds. The selection should be comprehensively considered according to the actual use conditions, reliability and other requirements and existing conditions.
a. Crimping: it has high mechanical strength, good environmental resistance, good electrical performance, and high reliability, but poor flexibility, suitable for occasions where the cable properties have been determined;
b. Winding: It is necessary to use a special winding gun or special equipment to complete the termination, and the reliability is high;
c. Barbed connection: mainly used for ribbon cables in printed boards, no need to pull wires, low cost, but the specified wire gauge must be used;
D. Welding: It is easy to form virtual welding that is not easy to inspect due to welding methods, weldability and other reasons, but it has the advantages of high flexibility and simple operation. Crimping and wrapping are relatively reliable termination methods and are recommended.
3. Electrical parameters
1. Contact resistance: The main consideration is the loss in line transmission, especially the signal voltage. Since the signal amplitude itself is not high, if the contact resistance is large, the voltage drop on it will be large, and the signal will be attenuated, which is not good for transmission. Because of the multi-point contact, the connector using the twist needle can better ensure its contact reliability, especially for the transmission of low voltage and small current.
2. Rated voltage: also called rated working voltage, refers to the voltage that can be applied for a long time between the components that are insulated from each other. Long-term operation under the condition of higher than rated voltage will make the insulation performance of the insulator deteriorate or damage the insulator and cause the connector to fail.
3. Rated current: It is also called rated working current. The value of rated current has been determined during the thermal design of the product. Excessive current will cause excessive heat generation and damage the insulator or soften the coating of the contacts and cause failure. The use current cannot be increased arbitrarily, and attention should be paid to derating use in order to require high reliability. Generally, it can be considered according to 75% to 85% of the rated current.