Capillary action in soldering or brazing occurs due to which forces?

Capillary action in soldering or brazing occurs due to which forces?

• A. Magnetic fields
• B. Capillary forces
• C. Gravitational forces
• D. Centrifugal forces

Answer: (B)

Capillary action is driven by capillary forces that come from surface tension at the molten solder–metal interface. The solder wets the surfaces because of adhesive forces between the liquid and solid and cohesive forces within the liquid; this creates a curved meniscus and a net pull along the narrow gap that draws the liquid into the joint, sometimes lifting it against gravity. Good wetting (low contact angle) enhances this effect, while poor wetting reduces it. Magnetic, gravitational alone, or centrifugal forces don’t cause this action.

Capillary action is driven by capillary forces that come from surface tension at the molten solder–metal interface. The solder wets the surfaces because of adhesive forces between the liquid and solid and cohesive forces within the liquid; this creates a curved meniscus and a net pull along the narrow gap that draws the liquid into the joint, sometimes lifting it against gravity. Good wetting (low contact angle) enhances this effect, while poor wetting reduces it. Magnetic, gravitational alone, or centrifugal forces don’t cause this action.