What is capillary action in relation to soldering?

Capillary action in relation to soldering refers to the ability of solder to flow into tight spaces through narrow gaps or between surfaces. This phenomenon occurs when the adhesive forces between the solder and the surfaces are stronger than the cohesive forces within the solder itself, allowing the solder to fill gaps and create strong connections. This property is crucial during soldering as it ensures that the solder can effectively penetrate joints and adhere well to the components and circuit board, forming reliable electrical connections.

The significance of capillary action is evident in various soldering techniques, such as in surface mount technology, where components are placed on a PCB with minimal spacing. In these applications, the ability of solder to wick into the joint is essential for achieving proper wetting and ensuring the mechanical strength and electrical performance of the assemblies.