In terms of connection function, insertion and extraction force is an important mechanical performance. The insertion and extraction forces are divided into insertion force and extraction force (also known as separation force), and their requirements are different. There are provisions for maximum insertion force and minimum separation force in relevant standards, which indicates that from a usage perspective, the insertion force should be small (resulting in structures with low insertion force LIF and no insertion force ZIF), and if the separation force is too small, it will affect the reliability of contact.