Describes soldering with formic acid or hydrogen or with plasma activation of argon-hydrogen mixtures in vacuum chambers. The acid or H2 both act as reducing agents. In low-pressure plasma soldering, the hydrogen is activated at room temperature, whereas in pure hydrogen soldering, the temperature of >250°C serves as the activator.

Preforms can be used instead of solder paste for flux-free soldering. This process enables void rates in the solder layer of