edfas.org ELECTRONIC DEVICE FAILURE ANALYSIS | VOLUME 27 NO. 2 16 STUDY ABOUT THE CORROSION OF SAC SOLDER JOINTS UNDER VARIOUS CONDITIONS OF TEMPERATURE AND SALINITY A. Guédon-Gracia, K.E. Akoda, J.-Y. Delétage, and H. Frémont IMS lab, Université de Bordeaux, CNRS, Talence, France alexandrine.gracia@u-bordeaux.fr EDFAAO (2025) 2:16-23 1537-0755/$19.00 ©ASM International® INTRODUCTION The durability of electronic assemblies is determined by the mechanical reliability of the solder joints against different degradation factors. A harsh marine environment associated with mechanical and electrical stresses is one of the environmental effects responsible for degrading the fatigue life of lead-free solder joints made of tin, silver, and copper (Sn-Ag-Cu), called SAC solder joints, in real-life applications.[1] These solder joints make the junction between the printed circuit and the component. Hence, they are one of the significant structures in electronic devices, which not only serve as physical connections but also transfer electricity and dissipate Joule heat.[2] Wang et al.,[3] in a comparative study of the corrosion behavior of SAC305 solder material and solder joints using a salt spray test according to ASTM B117-09 standard (5% NaCl at 35°C)[4] revealed that the corrosion risk in solder joints on a copper pad increased compared to that of lead-free solder alloys due to the galvanic corrosion process. Previous studies on SAC305 solder material alloy demonstrated that temperature has a significant effect on the dynamics of the corrosion mechanism of SAC305 solder alloy under salt spray test conditions.[5-7] In this paper, the influence of the salinity rate is studied. Moreover, a failure criterion on the corroded area is determined. EXPERIMENTAL PROCEDURE VEHICLE TEST The test vehicle comprises identical size chip resistors (1210) soldered with SAC305 lead-free solder on an FR4 board (Fig. 1). A copper defined pad is used with electroless nickel/immersion gold (ENIG) finish. SALT SPRAY CONDITIONS The electronic assemblies are exposed to a salt spray environment in a salt spray chamber, Ascott CC450Ip for 96 hr and then for 192 hr. The advantages of the salt spray chamber are the homogeneity of the temperature and the salt spray in the chamber and therefore the reproducibility of the test conditions. Three exposure temperatures (25°C, 35°C, 45°C) for three salinity rates (3.5%, 5%, 6.5% of NaCl) are studied. Fig. 1 Printed circuit board with ceramic resistors.
RkJQdWJsaXNoZXIy MTYyMzk3NQ==