| 摘要 |
A method of applying a uniform thickness layer of hot solder resist on printed circuit board (PP) containing a raised pattern of conductive paths of predetermined thickness having edge surfaces disposed perpendicular to the upper surfaces of the raised conductive paths. The method includes emitting the hot solder resist in a dovetail flat fan liquid film (Fd) pattern from an airless spray gun (2), and locating the printed circuit board below the emitted dovetail liquid film pattern at a distance such that the upper surface of the printed circuit board intersects the dovetail liquid film above the point at which the liquid film starts to brake-up into liquid particles. The hot solder resist has a moderate viscosity and contains both high and low boiling point solvents to allow the coating to even out without unnecessarily thinning at points above the upper edges of the raised printed circuit conductive paths. |
