Meniscus
The shape of a solder joint is formed automatically during the time when the solder is still liquefied. The final shape is determined y by the volume of solder present, the surface tension of the solder and the total area of wettable land. A small contact angle (wetting angle) joined by a tangential curve, observed during visual inspection, indicates that the solder joint is of acceptable quality. This concave shape is termed the solder meniscus.