Role of Copper Ions in Low‐Melting Solder Glasses

Controlled melting conditions for Cu‐containing solder glasses yielded a variety of Cu + /Cu 2+ ratios from a single glass starting composition. Measurements of softening point, thermal expansion, chemical durability, plus chemical analysis revealed that the well‐known viscosity effect of adding copper oxide to solder glasses is caused primarily by the Cu + ion; Cu 2+ plays a minor role, if any.