A Research on Drying Performance of Vertical Type Equipment for PCB Wet Process

An etching equipment for a printed circuit board (PCB) sprays chemical and DI water through nozzles on the surface of a substrate. The horizontal type equipment moves the substrate between the upper and lower rollers and they cause the damage on the patterns and sagging of the substrate. The flow rate difference between the upper and lower air knives also causes the damage on the substrates when drying them after the end of etching and washing process. To prevent this problem, the forces of the upper and lower air knives should be compensated. The drying rates of the upper and lower sides of the substrate could still be different for the horizontal type because of difficult control of drying flow rates. The vertical type equipment that the rollers don’t contact to the circuits has recently been developed as an alternative to solve the problems. This equipment has advantages that the DI water flows on the both sides of the substrate in the direction of the gravity and the flow rate of the air from the knives can be balanced because of its structural distinction. They lead to the better drying performance without damage on the substrate. The drying process of the substrate consists of two stages which are removing the extra water by wind from the air knives and evaporating the remained moisture by the high temperature of the chamber. In this research, we selected two parameters to optimize the drying capability to the angles of air knives and the temperature in the chamber. We also investigated about the removal capability of the extra drop of water and the remained moisture by using CFD. The design conditions for the process the refore have been founded by analyzing the velocity vector of wind and the time to get the target temperature.