Phase diagram investigations in the Au-Ge-X and Au-Sb-X (X = Si, Cu, Ni, Ti) systems

• Research unit: COST
• Project number: C08.0031

Key words (English)

lead free solder; high temperature; CALPHAD; modelling; phase diagrams

Research programs (English)

COST-Action MP0602 - Advanced Solder Materials for High Temperature Application- their nature, design, process and control in a multiscale domain

Short description (English)

The alloying systems Au-Ge and Au-Sb are charcterized by a deep eutectic point with melting temperatures of around 360°C. Thus, these alloys are of interest as possible high temperature lead free solder materials not only for special electronic applications but also in space technology or as corrosion resistant solders for components exposed to agressive media like sensors or biomedical devices. However, the Au content in these alloys needs to be reduced due to the high costs. This can be done by alloying with a third element which only slightly affects the melting temperature, e.g. in case of Au-Ge it was reported that the addition of Ni has only little effect on the eutectic temperature. In addition, these alloys react with base materials like Cu,Si, Ni or Ti during soldering and subsequent service. It was found out that phase diagram data of the relevant systems are very limited, especially for the ternary regions. In order to obtain the best conditions for soldering, a good comprehension of the reactions, which depends on availability of the thermodynamic properties of the related systems, is essential. The proposed project aims at the following points: - verification of phase equilibria in the above mentioned systems - determination of equilibria involving the liquid phase - calculation of respective phase diagrams - investigation of interface reactions between Au-Ge-X and Au-Sb-X solder, respectively, and possible base materials.

Further information (English)

Full name of research-institution/enterprise: Eidg. Materialprüfungs- und Forschungsanstalt EMPA Abteilung Füge und Grenzflächentechnologie

Partners and International Organizations (English)

AT, BE, BG, CH, CZ, DE, DK, FI, FR, HU, IE, IT, NL, PL, PT, RO, RS, SE, SI, SK, TR, UK

Abstract (English)

The alloying systems Au-Ge and Au-Sb are charcterized by a deep eutectic point with melting temperatures of around 360°C. Thus, these alloys are of interest as possible high temperature lead free solder materials not only for special electronic applications but also in space technology or as corrosion resistant solders for components exposed to agressive media like sensors or biomedical devices. However, the Au content in these alloys needs to be reduced due to the high costs. This can be done by alloying with a third element which only slightly affects the melting temperature, e.g. in case of Au-Ge it was reported that the addition of Ni has only little effect on the eutectic temperature. In addition, these alloys react with base materials like Cu,Si, Ni or Ti during soldering and subsequent service. It was found out that phase diagram data of the relevant systems are very limited, especially for the ternary regions. In order to obtain the best conditions for soldering, a good comprehension of the reactions, which depends on availability of the thermodynamic properties of the related systems, is essential. The proposed project aims at the following points: - verification of phase equilibria in the above mentioned systems - determination of equilibria involving the liquid phase - calculation of respective phase diagrams - investigation of interface reactions between Au-Ge-X and Au-Sb-X solder, respectively, and possible base materials

References in databases (English)

Swiss Database: COST-DB of the State Secretariat for Education and Research Hallwylstrasse 4 CH-3003 Berne, Switzerland Tel. [phone] Swiss Project-Number: C08.0031