Advanced Solder Materials for High temperature Application -HISOLD COST MP0602 Start date: 16/05/2007 End date: 16/05/2011 Year: 2

Scientific context and objectives Research area: Basic research in the Materials Science of Environmentally Friendly Materials for Electronic Applications. MoU objectives: The focus of the COST Action is the investigation of Pb-free replacements for solders for high-temperature applications. This comprises a study of the chemical, physical and mechanical properties of prospective alloys. A multiscale approach is used: Meso-scale: The application of thermodynamics and kinetics to the study of alloying behaviour; the development of materials property databases. Macro-scale: The creation of a phenomenological description of corrosion and deformation processes occurring in a solder joint during fabrication and service, Micro- (nano-) scale: The experimental investigation and modelling of the initial stage of the formation of intermetallic phases at the solder/substrate interface. This will involve the consideration of diffusion.

Working groups 1) Materials properties To extend knowledge of potential Pb-free solder alloy systems for high-temperature applications. Materials property databases are being prepared to cover phase equilibria and thermodynamic properties of the most important alloy systems, thermophysical and mechanical properties, including process related information. 2) Properties of solder joints Corrosion behaviour, deformation processes, failure modes and other mechanically related problems occurring in the soldered structure during fabrication and service. Development of analytical and numerical models of the mechanical behaviour of candidate solders, necessary for the life-time prediction of electronic packages and to accelerate the adoption of lead-free replacement solders in industrial applications. 3) Processes at the Interface Reactive phase formation. The formation of intermetallic compounds at solder/substrate interfaces, the development of texture in the reaction products in concentration gradients and the development of defect structures in the vicinity of the reaction interface. To develop an experimental and theoretical approach that can be used to elucidate the role of competitive nucleation and growth of intermediate phases in the genesis of the interdiffusion system.

Action Members +1 (Intention to sign) +2 Non-Cost members

Number of individual participants and early stage researchers

Use of COST instruments YR 1 YR 2 YR 3 YR 4 No. of MC / WG meetings 2 1 No. of STSMs 4 10+4 pl. No. of workshops / conferences 1+2 pl. No. of publications 32/3/34/9 14/1/12/- not yet completed No. of training schools GASG (activities) website

Significant highlights (1/2) The Joint Working Group meeting, Genova, Italy February, 22-24, 2008 First full scale meeting of the Action after starting the Action in the second half of the year 2007, this meeting was crucial in creating ties and cooperation between the Action members. The result of the meeting was the creation of 6 Group Projects cementing networks between different research teams; as many as 14 research teams in some cases Example: There are the first results of the cooperation, the GP working in WG 3 entitled “Complex modelling of microstructural changes in the interdiffusion zone of Pb-free solder joints” has produced the first simulations of the behaviour at the interface between solder and substrate This project is highly dependent on WG1 and GP1 projects aimed at the creation of the Thermodynamic and Materials database (see next slide)

Significant highlights (2/2) The WG 1 meeting organized in Wien (July 2008, approx. 14 participants) and STSM organized in Brno in September 2008 with 5 participants. Both events dealt with the search for new prospective alloy systems for H-T solders and the derivation of consistent thermodynamic database, allowing the calculation of phase diagrams and prediction of higher-order systems This activity will lead to one of the major scientific deliverables of the project; the creation of a consistent thermodynamic database will pave the way for the development of new industrial materials and a clearer understanding of the soldering process. The basis for the database is the database Solders, developed for materials used for “classical” soldering – resulting in the Atlas of Phase Diagrams published in the scope of COST 531 Action. A similar output is expected at the end of this Action. This activity has a crucial impact on the project as this database is used by the members of WG 1 and 3 in their studies of the phase relations of prospective materials and to model interface processes.

Global dimension Institutions from non-COST countries Industrial links Ivan Franko National University, L’viv - (Ukraine) Ural State Pedagogical University, Institute of Metallurgy - (Russian Federation) Institute of Metallurgy of Ural Branch of Russian Academy of Sciences, Ekaterinburg - (Russian Federation) – (Applying) Industrial links Soldertec Global (UK) SWEREA/IVF (Sweden) NXP Semiconductors (founded by Philips) Mat-Tech BV (Netherlands) Cookson Electronics UK

Global dimension Dissemination Website Publications www.cost602.ipm.cz Publications Refereed journals – 32 Conference contributions - 34 Invited lectures – 3 Theses – 9 Atlas of Phase Diagrams for High-Temperature Lead-Free Alloys; (in preparation, completion at the end of the Action).

Challenges Successes and shortcomings: Future challenges: Bringing together scientists from different research fields with industrial partners Mutual feedback between basic science, practical applications and industrial needs. The development of databases continues successfully. Securing local funding to conduct the research work. Many research teams are funded only from the beginning of 2008. Effort during 2007 was concentrated on the preparation of research funding applications. Some research teams have not secured funding and therefore some of the work will start later. Future challenges: To coordinate the effort of the research groups in relation to the most prospective materials and technologies with respect to the inflexibility of scientific programs. Difficulties in securing local financing.