Research on joining metal-ceramics composite Al/Al2O3 with Cu substrate using solder type Zn–In–Mg:

The study aimed at direct flux-free soldering of metal-ceramics composite (MMC) with a copper substrate. Soldering was performed with type Zn10In1Mg Zn-solder. The soldered joints were fabricated using power ultrasound. The solder used consists of a zinc matrix, while the solid solution (In) and MgZn2 phase were segregated on the grain boundaries. The soldered MMC joint is formed due to dissolution of the aluminium matrix in zinc solder. A new composite, composed of matrix consisting mainly of solid solution (Al) is thus formed. Moreover, there is also a solid solution present (In) and Cu3.2Zn0.7Al4.2 phase. The bond with copper substrate is formed due to interaction of Zn and Al from the solder at formation of two transient phases, namely Cu3.2Zn0.7Al4.2 and an unstable phase of Al(Cu,Zn)2. The average shear strength of combined joints of MMC/Cu is 16.5 MPa.