Electronic connectors (hereinafter referred to as connectors) can also be called plug plugs, which are widely used in various electrical circuits and play the role of connecting or disconnecting circuits. There are many types of connectors and a wide range of applications. However, if you ask what the main technical parameters of the connector are, many users may not be familiar with it, so we also need to understand the main technical parameters of the connector itself.
1. Safety parameters
Insulation resistance refers to the resistance value that occurs when a voltage is applied to the insulating part of the connector, causing leakage current to be generated on or on the surface of the insulating part. It is mainly affected by factors such as insulation material, temperature, humidity, fouling, etc. The insulation resistance value provided on the connector sample is generally an index value under standard atmospheric conditions, and under some environmental conditions, the insulation resistance value will not decrease to a different degree. In addition, pay attention to the test voltage value of the insulation resistance. Different voltages are applied depending on the insulation resistance (MΩ) = voltage applied to the insulator (V) / leakage current (μA), and there are different results. In the test of the connector, the applied voltage is generally 10V, 100V, 500V three gears.
Second, withstand pressure
Withstand voltage is a critical voltage that can withstand a higher than the rated voltage without breakdown phenomenon between the mutual insulating parts of the contact pair or between the insulated parts and the ground within a specified time. It is mainly affected by contact to spacing and creepage distance and geometry, insulator material as well as ambient temperature and humidity, atmospheric pressure.
Third, flammability
Any connector is inseparable from the current when working, which is the risk of fire. Therefore, the connector is not only required to prevent ignition, but also to be able to extinguish itself in a short time once ignited and fired. When selecting, pay attention to the selection of electrical connectors that use flame-retardant and self-extinguishing insulation materials.
4. Mechanical parameters
Single foot separation force and total separation force
The contact pressure in the connector is an important indicator, which directly affects the size of the contact resistance and the amount of wear of the contact pair. In most structures, direct measurement of contact pressure is quite difficult. Therefore, the contact pressure is often measured indirectly by separating the force on one foot. For round pinhole contact pairs, the ability of the negative contact to hold the weight is usually tested with a standard pin with a specified weight weight, and the diameter of the standard pin is generally -5μm at the lower limit of the male contact diameter. The total separation force is generally twice the sum of the separation forces on one foot. When the total separation force exceeds 50N, it is already quite difficult to insert and unplug manually. Of course, for some test equipment or some special requirements, zero plugging force connectors, automatic detachment connectors and so on can be selected.
5. Environmental parameters
Environmental parameters mainly include ambient temperature, humidity, temperature sudden changes, atmospheric pressure and corrosive environment. The environment in which the connector is used and stored and transported has a significant impact on its performance, so the corresponding connector must be selected according to the actual environmental conditions.
6. Ambient temperature
The metal material and insulation material of the connector determine the operating environment temperature of the connector. High temperature will damage the edge material, causing the insulation resistance and withstand voltage performance to decrease; For metals, high temperatures can cause the contact pair to lose elasticity, accelerate oxidation and deteriorate the coating. The usual ambient temperature is -55~100 °C, and special occasions may be more demanding.
7. Dampness
Relative humidity greater than 80% is the main cause of electrical breakdown. The humid environment causes the absorption and diffusion of water vapor on the surface of the insulator, which is easy to reduce the insulation resistance below the MΩ level, and long-term exposure to high humidity environment will cause physical deformation, decomposition, escape of products, respiratory effects and electrolysis, corrosion and cracks. Especially for connectors outside the equipment, moisture, water infiltration and contamination environmental conditions are often considered, in which case sealed connectors should be selected. For watertight and dusttight connectors, the shell protection level of GB4208 is generally used to indicate.
8. Rapid temperature changes
The humidity blast test simulates the actual use of using connector equipment to switch from a cold environment to a warm environment, or simulates a sharp change in the ambient temperature of a space vehicle or probe. Sudden temperature changes can crack or ply up the insulating material.
9. Atmospheric pressure
At high altitudes where the air is thin, the plastic releases gas pollution contact pairs, and the trend of corona generation increases, the withstand voltage performance decreases, and the circuit produces a short-circuit fault. When a certain value is reached at high altitude, the plastic performance deteriorates. Therefore, when using non-sealed connectors at height, it must be derated. The recommended voltage derating factors at low air pressure are shown in Table 2.
10. Corrosive environment
According to the different use of the connector corrosion environment, the selection of the corresponding metal, plastic, plating structure of the connector, like the connector used in the salt spray environment, if there is no anti-corrosion metal surface, will make the performance deteriorate rapidly. In environments containing a considerable concentration of SO2, silver-plated contact pair connectors should not be used. In hot flashy areas, mold is also an important problem.
I hope this article will help users and friends better understand the connector, for practitioners in the connector industry, some general parameters of the connector should be very familiar. Improving the reliability of the connector is first and foremost the responsibility of the manufacturer, and only through the joint efforts of both the manufacturer and the user can the connector maximize the function that the connector should have.