Retained ratio of reinforcement in SAC305 composite solder joints: effect of reinforcement type, processing and reflow cycle

Abstract

alloys during different processing stages were studied using SEM, XRD and EDS.

The study on reliability of Ni-coated graphene doped SAC305 lead-free composite solders under high current-density stressing

“…In addition, it could be found from the nanoindentation curve of the two types of solder joints, before the EM stressing that the dispersion degree of the data that formulated the nanoindentation curve of the SAC305 solder joint was significantly lower than that of the SAC305/Ni-GNS composite solder joint, indicating that the Ni-GNS was not evenly distributed throughout the solder joints, leading to the uneven distribution of the hardness throughout the composite solder joint. In one of the authors’ previous studies, it was found that the added reinforcing phase (Ni-GNS) was easily excluded by the molten solder during the process of reflow soldering, which not only caused a significant reduction in the content of the reinforced phase that remained in the solder joint but also led to the uneven distribution of the reinforcing phase in the solder joint (Chen et al , 2016a, 2016b). In this case, some areas in the composite solder joint may have had a larger content of the reinforcing phase while other areas may have had a smaller content, which finally caused a larger dispersion of the hardness data of the composite solder joint.…”

“…For example, it has been found that the addition of an appropriate quantity of metallic material such as Co, Ni, Sb and Zn, a non-metallic material such as ZnO and Al 2 O 3 , or a carbon nano-material such as carbon nanotubes into a conventional Sn-based solder, can suppress the EM phenomenon to an extent (Sun et al , 2016; Zhao et al , 2013; Hu et al , 2013; Xu et al , 2011; Wang and Li, 2016; Wang et al , 2017; Bashir et al , 2016; Yang et al , 2013). In the authors’ previous work a new type of lead-free composite solder that was alloyed with nickel-plated graphene (Ni-GNS), was developed (Chen et al , 2016a, 2016b). The results showed that the addition of the Ni-GNS not only changed the morphology of the solder matrix and the interfacial IMC but also improved the stability of the microstructure under thermal aging conditions, and the mechanical properties of the solder joints were also significantly improved.…”

Real-time profiling of reflow process in VPS chamber

“…Vapour condenses on the cooler parts of a printed circuit board (PCB) and releases latent heat energy. Among the main advantages of VPS is the guarantee of an exactly defined temperature, excellent heat distribution, an inert atmosphere, an environmentally friendly process, good universality and homogeneity of working temperature (Chen et al, 2016;Géczy et al, 2014).…”

“…VPS has gone through changes in popularity since the early 1980s. The disadvantage is higher susceptibility of this technology to tombstone effects and the higher price of the inert liquid (Chu et al, 2015;Krammer, 2014;Chu et al, 2015;Chen et al, 2016). VPS was, in the past, declined for two reasons: problems with the VPS process itself and improvements in IR processes.…”

“…The thermal profile setting is a significant variable that affects the quality of joints, because an inappropriate reflow thermal profile can cause problems with reliability and many soldering defects (Koncz-Horváth et al, 2015;Krammer, 2014;Skwarek et al, 2015;Chen et al, 2016). The following paper details the possibility of applying VPS to the reflow of solder alloys in power electronics modules based on direct bonded copper (DBC) substrates.…”