Three basic properties of connectors

The basic performance of the connector can be divided into three categories: mechanical performance, electrical performance and environmental performance.

1. Mechanical properties As far as the connection function is concerned, the insertion and withdrawal force is an important mechanical property.

Inserting and pulling force is divided into inserting force and pulling force, and the requirements of the two are different. In the relevant standards, there are maximum insertion force and minimum separation force provisions, which indicates that the insertion force should be small, and if the separation force is too small, it will affect the reliability of the contact.

Another important mechanical property is the mechanical life of the connector. Mechanical life is actually a durability index, which is called mechanical operation in the national standard GB5095. It takes one insertion and one withdrawal as a cycle, and takes whether the connector can normally complete its connection function after the specified insertion and withdrawal cycle as the basis for evaluation. The insertion force and mechanical life of the connector are related to the quality of the coating on the contact part of the contact structure and the dimensional accuracy of the contact arrangement.

QCT 1067-2017 Requirements and test methods for mechanical properties of connectors

2. The main electrical properties of connectors include contact resistance, insulation resistance and electrical strength.

A high-quality electrical connector should have a low and stable contact resistance. Connectors have contact resistance ranging from a few milliohm to tens of milliohm.

The insulation resistance measures the insulation performance between the contacts of the electrical connector and between the contacts and the housing, and its order of magnitude ranges from hundreds of megaohms to thousands of megaohms.

(3) Electrical strength, or voltage resistance, dielectric voltage resistance, is the ability to withstand the rated test voltage between the connector contacts or between the contacts and the housing.

④ Other electrical properties. Electromagnetic interference leakage attenuation is to evaluate the electromagnetic interference shielding effect of the connector, and electromagnetic interference leakage attenuation is to evaluate the electromagnetic interference shielding effect of the connector, which is generally tested in the frequency range of 100MHz to 10GHz. For RF coaxial connectors, there are electrical indicators such as characteristic impedance, insertion loss, reflection coefficient, and voltage standing wave ratio. Due to the development of digital technology, in order to connect and transmit high-speed digital pulse signals, a new type of connector, that is, high-speed signal connector, correspondingly, in terms of electrical performance, in addition to the characteristic impedance, there are also some new electrical indicators, such as crosstalk lag.

3. Environmental properties Common environmental properties include resistance to temperature, humidity, vibration and shock.

① Temperature resistance

At present, the maximum operating temperature of the connector is 200 ° C and the minimum temperature is -65 ° C. Because when the connector works, the current generates heat at the contact point, resulting in a temperature rise, it is generally believed that the operating temperature should be equal to the sum of the ambient temperature and the temperature rise of the contact. In some specifications, the maximum temperature rise allowed for the connector at the rated operating current is clearly specified.

② Moisture Resistance

The intrusion of moisture will affect the insulation properties of the connection h and rust the metal parts. Constant humid heat test conditions are relative humidity 90%~95%, temperature +40±20℃, test time according to product regulations, at least 96 hours. Alternating heat and humidity tests are more rigorous.

③ Salt spray resistance

When the connector works in an environment containing moisture and salt, the surface treatment layer of the metal structural parts and contact parts may produce electrochemical corrosion, affecting the physical and electrical properties of the connector. In order to evaluate the ability of electrical connectors to withstand this environment, salt spray tests are prescribed. It is to suspend the connector in a temperature-controlled test chamber to form a salt spray atmosphere, and its exposure time is specified by the product specification, at least 48 hours.

④ Resistance to vibration and shock

Vibration and shock resistance is an important performance of the electrical connector, which is an important indicator to test the robustness of the mechanical structure of the electrical connector and the reliability of the electrical contact. There are clear provisions in the relevant test methods. The peak acceleration and the time of interruption of electrical continuity shall be specified in the impact test.

⑤ Other environmental performance

According to the requirements of use, other environmental properties of electrical connectors are tightness, low pressure and so on.