For SMT surface mount boards, especially for BGA and IC mounting, the via plug hole must be flat, 1 mil positive and negative, and there must be no red tin on the via hole; The customer's requirements, through hole plug hole technology can be described as varied, the process is particularly long, difficult to control the process, often in the hot air leveling and green oil resistance soldering test when the oil; after the oil explosion and other issues occurred. According to the actual conditions of production, PCB plug holes are summarized, and some processes and advantages and disadvantages are compared and elaborated:
Note: The working principle of hot air leveling is to use hot air to remove excess solder from the surface of the printed circuit board and holes. The remaining solder is evenly covered on the pads and non-resistive solder lines and surface package points. It is the way of surface treatment of printed circuit boards. one.