EUROPEAN CONGRESS AND EXHIBITION ON ADVANCED MATERIALS AND PROCESSES - EUROMAT 2021

Since the 1st of June 2006, the RoHS EU directive was implemented in most of the European countries and the use of lead has been dramatically reduced. The commonly applied Sn-Pb solder alloy was restricted for selected applications only, and the Sn-Ag-Cu alloys (SAC) were implemented in production practice.
One of SAC’s implementation issues is associated with the difficulties in quality assessment. The well-known solder joints’ defects, like thick intermetallic layers, micro cracks, inhomogeneity of microstructure or voids are difficult to be detected in production practice. Moreover, one of the important problems of high power components soldering is the heat dissipation out of the component. Mentioned typical defects of SAC solder joints cause the reduction of the heat transfer and decrease of the reliability and mechanical properties of solder interconnection.
As a part of the research work, the tests of SAC alloys, used as a reference material, and new solder compositions, commercially available since 2017 and proposed by leading producers were investigated regarding the thermal conductivity phenomena in the in vivo experiment. As the next step, the obtained results were correlated with the morphology and microstructure characterization of the interconnections’ interfaces together with the chemical composition analysis of the reaction zone performed by scanning electron microscopy technique.
Obtained results revealed that the intermetallic compounds and defects of solder joints microstructure have a major impact for thermal energy transfer and in fact, quality of solder joints.

The research was co-financed by the Polish Ministry of Science and Higher Education in the frame of the project DWD/3/29/2019 “Doktorat Wdrożeniowy” realized at Krakow School of Interdisciplinary PhD Studies and Fideltronik SA Company. The SEM research was conducted in the Accredited Testing Laboratories at the IMMS PAS.