The development of connectors should be towards miniaturization (as many products have to face smaller and lighter development, there are certain requirements for spacing, appearance size and height, which will make the requirements for products more precise, such as the best choice of small spacing 0.6mm and 0.8mm for wire to board), high-density, high-speed transmission and high-frequency development. Miniaturization refers to the smaller center spacing of connectors, and high-density refers to the digitalization of large cores. The total number of effective contacts of high-density PCB (printed circuit board) connectors can reach 600 cores, and the maximum number of special devices can reach 5000 cores. High speed transmission means that modern computer, information technology and networking technology require the time scale rate of signal transmission to reach the megahertz frequency band, and the pulse time to reach sub millisecond, so high-speed transmission connectors are required. In order to adapt to the development of millimeter wave technology, RF coaxial connectors have entered the millimeter wave working frequency band.