The basic performance of connectors can be divided into three categories: mechanical performance, electrical performance and environmental performance. 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 extraction as a cycle, and takes whether the connector can normally complete its connection function (such as contact resistance value) after the specified insertion and extraction cycle as the judgment basis. 1. Mechanical property As far as the connection function is concerned, the insertion and extraction force is an important mechanical property. Insertion and pull-out force is divided into insertion force and pull-out force (pull-out force is also called separation force), and their requirements are different. There are provisions on maximum insertion force and minimum separation force in the relevant standards, which shows that from the perspective of use, the insertion force is small (so there are structures with low insertion force LIF and no insertion force ZIF), and if the separation force is too small, the contact reliability will be affected. The insertion and withdrawal force and mechanical life of the connector are related to the contact structure (positive pressure), the coating quality of the contact part (sliding friction coefficient) and the dimensional accuracy (alignment) of the contact arrangement.