Time above liquidus (TAL)

Refers to the period of time during which the solder is liquid. This is referred to as the time above liquidus – TAL or time over liquidus TOL.

This time is extremely important for the soldering process, as a duration of less than 30s that is too short is usually not sufficient to achieve homogeneous wetting on the joining partners.

However, if the time above liquidus is too long, the metallization is deposited. This is called de-alloying or leaching. Due to diffusion processes, thin coatings of the joining partners can completely dissolve in the solder and defects can be created within the underlying material. Therefore, a maximum time in the liquid state of approx. 90-120s is the rule.

Time over liquidus
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