Wetting refers to the formation of a contact area between the liquid solder and the surface to be soldered. If there is good wetting, the contact area increases or remains unchanged in the case of preforms. If the wetting is poor, the contact area is reduced. Measuring the angle between the solder material and the carrier material is one way of quantifying wetting. A contact angle measurement of the solder can be carried out in the liquid state or later in the solidified state.

Poor wetting or non-existent wetting is present at angles >90°C.

Partial wetting refers to angles of 10…90°.

Complete wetting of the solder material on the substrate is achieved at angles of