Research on soldering AlN ceramics with Cu substrate using Sn-Ag-Ti solder

Abstract

Purpose

This study aims to solder AlN ceramics with a Cu substrate using an active type Sn-Ag-Ti solder. Soldering was performed with power ultrasound. The Sn3.5Ag2Ti alloy was first studied.

Design/methodology/approach

It was found to contain a Sn matrix, where both Ag phase – ɛ-Ag₃Sn – and Ti phases ɛ-Ti₆Sn₅ and Ti₂Sn₃ – were identified. Ti contained in these phases is distributed to the interface with ceramic material. A reaction layer was thus formed. This layer varies in thickness from 0.5 to 3.5 µm and ensures the wettability of an active solder on the surfaces of ceramic materials.

Findings

X-ray diffraction analysis proved the presence of new NTi and AlTi₂ phases on the fractured surface. Sn plays the main role in bond formation when soldering the Cu substrate with Sn-Ag-Ti solder. The Cu₃Sn and Cu₆Sn₅ phases, which grow in direction from the phase interface to solder matrix, were found in all cases within the solder/Cu substrate interface. The combination of AlN ceramics/Cu joint maintained a shear strength of 29.5 MPa, whereas the Cu/Cu joint showed a somewhat higher shear strength of 39.5 MPa.

Originality/value

The present study was oriented towards soldering of AlN ceramics with a Cu substrate by the aid of ultrasound, and the fluxless soldering method was applied. Soldering alloy type Sn-Ag-Ti was analysed, and the interactions between the solder and ceramic and/or Cu substrate were studied. The shear strength of fabricated soldered joints was measured.

Citation

Koleňák, R., Kostolný, I., Drápala, J., Kusý, M. and Pašák, M. (2019), "Research on soldering AlN ceramics with Cu substrate using Sn-Ag-Ti solder", Soldering & Surface Mount Technology, Vol. 31 No. 2, pp. 93-101. https://doi.org/10.1108/SSMT-10-2018-0039