Contact Angle
The wetting angle is the angle at which a droplet of molten solder meets the workpiece surface. A small angle means good wetting and strong adhesion.
Physico-chemical mechanism of action
Wetting angle indicates how well the molten solder penetrates the workpiece. A small angle (less than 30°) means the melt spreads well on the surface and forms a strong joint.
Metallurgical relevance & risks in welding
A large wetting angle (greater than 30°) can lead to poor wetting, which means the melt doesn't penetrate the surface properly. This can cause incomplete bonding and weak spots in the weld.
Workshop practice & instructions
To ensure a good wetting angle, use a solder with the right composition for the base material. Make sure the melt is clean and free of impurities. For difficult materials, it can help to reduce the wetting angle by applying liquids like isopropanol.