Electronic products of aerospace and navigation, motor vehicles, automobiles, outdoor LED lighting, solar energy and military enterprises with high reliability requirements, solder ball array devices (BGA/CSP/WLP/POP) and special devices on circuit boards are all facing microelectronics. The trend of miniaturization, and thin PCBs with a thickness of less than 1.0mm or flexible high-density assembly substrates, solder joints between devices and substrates become fragile under mechanical and thermal stress.