Degradation of high reliability lead-free solder joints under harsh thermal cycling test

• Published in: Microelectronics and reliability Vol. 173; p. 115868
• Main Authors: Yeom, Jeyun, Elsener, Hans Rudolf, Burgdorf, Tobias, Bischoff, Regina, Jeurgens, Lars P.H., Janczak-Rusch, Jolanta
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01.10.2025
• Subjects: Crack length; Lead-free solders; Maximum shear force; Reliability; Thermal cycling; Void area; Crack length; Lead-free solders; Void area; Reliability; Maximum shear force; Thermal cycling
• ISSN: 0026-2714
• DOI: 10.1016/j.microrel.2025.115868

In this study, the degradation behavior of solder joints made using pre-selected, highly reliable lead-free solder alloys was investigated under thermal cycling conditions. Innolot (Sn 3.8Ag 0.7Cu 3.0Bi 1.5Sb 0.2Ni) and SB6NX (Sn 3.5Ag 0.8Cu 0.5Bi 6.0In) as well as reference solders: SAC305 (Sn 3Ag 0.5Cu) and SnPb solder were selected for this study, and solder joints of R1812 ceramic chip resistors on a printed circuit board were prepared by reflow soldering. The mechanical and microstructural degradation of the solder joints was investigated after thermal cycles (3000 cycles) from −55 to +100 °C with extended dwell times of 30 min. The crack length and void area were determined by optical microscopy from joint cross-sections and correlated with maximum shear force degradation obtained in mechanical shear tests. The results of the study support the development of highly reliable surface-mounted components for aerospace applications. •Investigated solder joint behavior under thermal cycling.•Used Innolot, SB6NX, SAC305, and SnPb solders for R1812 resistors.•Void area is largest in Innolot, then SnPb, SAC305, SB6NX after thermal cycling.•Crack propagation prominence: SB6NX > Innolot > SnPb > SAC305•Performance order: Innolot, SB6NX, SnPb, SAC305 based on shear force