Atlas of phase diagrams for solders

Owing to impending European legislation, lead will no longer be used in the fabrication of electrical and electronic materials within Europe. COST 531 was a European action on the study of new lead-free materials suitable for use in the electronics industry. One of the objectives of the action was the provision of a self-consistent thermodynamic database for lead-free solder materials and substrates. Assessed thermodynamic parameters for more than 50 binary systems were collected from the literature or have been provided directly by a programme of experimental and assessment work as part of the COST action. These data were supplemented by parameters for ternary systems to provide a self-consistent thermodynamic database.The database has been tested thoroughly using proprietary software to ensure its portability.

This Atlas has been created using this database in conjunction with commercial software developed for the calculation of phase equilibria from critically assessed data. Three different software packages were used – MTDATA, ThermoCalc and PANDAT. Each package is broadly comparable in scope and can equally be used to exploit this database in order to explore the potential for potential alloys to be used as lead free solders. Various diagrams are presented in this volume calculated with each of these packages. The aim of these diagrams and this volume is firstly to demonstrate the scope and potential of the database, to describe how the database has been developed as a result of collaboration between a large number of European partners and show how it can be used with appropriate software as an aid in the design and use of solders.

The example below shows a typical example of the information given for a binary system i.e. the source of the critically assessed data, a table of calculated invariant reactions, the calculated phase diagram and a table of crystal structures of phases present in the system.