Control of Ag electro chemical migration is crucial for long-term reliability of electrical components in high-voltage applications. In this work, Cu was bonded onto an AlN substrate at temperatures between 650 °C and 950 °C for 1 h using a Ag Free Cu-P-Sn-Ni brazing filler metal with Ti as an active metal addition. The interfacial structure between the Cu and the AlN and the mechanical properties of the bond were both investigated. Three different phases which contain Ti and O were observed during the growth process of the Cu/AlN interfacial reaction layer: an amorphous P-Ti-O phase, an amorphous Ti-O phase and rutile, TiO2. The most stable Cu/AlN interfacial structure occurred when rutile was present, and where a particular orientation relationship with AlN was observed: TiO2 (101)//AlN (0001), TiO2[010]//AlN [1120 ]. The probability of Cu/AlN interfacial fracture decreased as the bonding temperature was increased. Cu/AlN interfacial fracture was completely suppressed above 850 °C where rutile was the dominant phase at the Cu/AlN interface.

To focus on the interfacial reaction between the Ag–Cu alloy layer and TiN in active metal brazing, the Ag–Cu brazed interfacial structures between Cu and two types of TiN sintered ceramics fabricated by different methods were examined. No grain boundary phase components consisting of the Ni-containing Fe phase or Mo2C were detected on the TiN grain surfaces of the TiN liquid-phase sintered ceramic bonding surfaces before brazing. The brazed specimens were heated at 850 °C for 0.5 h. No Cu/TiN solid-phase sintered ceramic bonding was obtained. The Ag–Cu alloy layer was bonded onto the TiN grains in the TiN liquid-phase sintered ceramic through an Fe- and Ni-containing segregation layer. This segregation layer was formed by an interfacial reaction between the TiN grains and the Ni-containing Fe in the TiN liquid-phase sintered ceramic dissolved in the Ag–Cu liquid phase.

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Eliminating electrochemical migration of Ag is effective for improving the long-term reliability of power modules for high-voltage applications. In this work, a Cu plate was bonded onto an AlN substrate via Mg–Ti co-deposited films with three different compositions as Ag-free bonding materials between 800 and 950 °C for 0.5 h. The interfacial structures and the peel strength between the Cu and AlN were investigated by using the Surface And Interfacial Cutting Analysis System (SAICAS). Cu was bonded onto AlN through a TiN layer consisting of TiN particles and a Cu-containing grain boundary phase. All fractures at the Cu/AlN interface were observed to occur between the TiN layer and AlN after the SAICAS test. The peel strength at the Cu/AlN interface, which was independent of the thickness of the TiN layer, increased exponentially with increasing bonding temperature. Cu-containing phases, such as grain boundary phases and segregation phases between TiN particles and AlN, were present at the TiN layer/AlN interface. Mg and O were segregated at the interface, which had a high peel strength between the Cu-containing phase and AlN, while at the signal peak position of Mg, a plateau was observed in the Al concentration distribution between the Cu-containing phase and TiN particle. The peel strength of the Cu-containing phase/AlN interface, which increased as the O concentration in the Mg-containing segregation layer increased, dominated that of the TiN layer/AlN interface.