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| Lead-Free Solder Alloy Properties |
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There has been a perceived need for many years to draw together all of the available property data for lead-free solder alloys for use in research and for modelling. Some databases exist but the data is test dependant, sometimes incomplete and is not compiled in user-friendly form.
Since the conception of lead-free solder alloys for plumbing solders several decades ago, research teams around the world have been measuring alloy properties. Some of this data has been published and much of it has not. A variety of test methods have been used causing variation in results although the test protocols have not always been clear.
European and US projects generating this data include:
- DTI Project
- NCMS Project
- NEMI Lead-Free Assembly Project
- IDEALS
- Lead-Free Solder Alloy by Prediction
- MPP 5.2 - Models and Methods for Lead-Free Reliability
- Solder Research Group
Public-access online databases of physical and mechanical properties have been created by NIST and NPL. The COST 531 Network has an online database of thermodynamic properties, restricted to COST 531 members.
Within the ELFNET 'Issues to Solutions' initiative this area has been defined as a priority Solution M7 - Lead-Free Solder Alloy Properties
The Department of Inorganic Chemistry - Materials Chemistry of the University of Vienna agreed to coordinate the construction of a database on properties of lead-free solder alloys. As this project is also in line with demands of COST Action 531 on Lead-free Solder materials, this database is being jointly developed by ELFNET and COST Action 531.
Already at a very early stage in the process of setting up this database the decision was made not only to include the properties themselves, but also to focus on the experimental techniques that were used to produce these data. This approach tries to avoid one of the major shortcomings of existing databases, which only scarcely feature experimental techniques.
The structure of the new ELFNET / COST 531 database has been developed from the ITRI 'Solder Alloy Properties' Handbook. It is split into separate sections on experimental methods and properties. For each property it is planned to have a description of the respective measurement technique, too. The focus of the database is on physical and mechanical properties of solders and solder joints, as well as on wettability and solderability. Intermetallics formation and growth, however, are not included in this database.
Furthermore, it was decided to exclusively concentrate on the Sn-Ag-Cu (SAC) alloy family at the beginning. The SAC family had been chosen because of its outstanding technological interest.
In September 2005 a first draft version of the database, though still under construction, was presented at the ELFNET meetings in Leuven. Currently the database contains data on 22 SAC alloys from various sources, including the NIST and NPL databases as well as recent literature data.
The first version of the database was published as a pdf-booklet in April 2006. This is now being updated and a revised and expanded version will be made available shortly.
For more information contact Clemens Schmetterer, University of Vienna
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