Soldering Characteristics and Mechanical Properties of Sn-1.0Ag-0.5Cu Solder with Minor Aluminum Addition

Abstract

Driven by the trends towards miniaturization in lead free electronic products, researchers are putting immense efforts to improve the properties and reliabilities of Sn based solders. Recently, much interest has been shown on low silver (Ag) content solder SAC105 (Sn-1.0Ag-0.5Cu) because of economic reasons and improvement of impact resistance as compared to SAC305 (Sn-3.0Ag-0.5Cu. The present work investigates the effect of minor aluminum (Al) addition (0.1–0.5 wt.%) to SAC105 on the interfacial structure between solder and copper substrate during reflow. The addition of minor Al promoted formation of small, equiaxed Cu-Al particle, which are identified as Cu3Al2. Cu3Al2 resided at the near surface/edges of the solder and exhibited higher hardness and modulus. Results show that the minor addition of Al does not alter the morphology of the interfacial intermetallic compounds, but they substantially suppress the growth of the interfacial Cu6Sn5 intermetallic compound (IMC) after reflow. During isothermal aging, minor alloying Al has reduced the thickness of interfacial Cu6Sn5 IMC but has no significant effect on the thickness of Cu3Sn. It is suggested that of atoms of Al exert their influence by hindering the flow of reacting species at the interface.

Morphology transformation on Cu3Sn grains during the formation of full Cu3Sn solder joints in electronic packaging

“…Even, in some cases, the height can be reduced to less than 10 mm which belongs to a micro interconnected height. Under the traditional interconnected height of several hundreds of micrometers, joints with the interfacial structure of substrates/ IMCs/solder/IMCs/substrates are formed after soldering (Chen et al, 2017;Leong and Haseeb, 2016;Mehrabi et al, 2016). Under this case, the interfacial IMCs merely account for quite small proportion in the interfacial region.…”

Effect of Multiple Reflows on the Interfacial Reactions and Mechanical Properties of an Sn-0.5Cu-Al(Si) Solder and a Cu Substrate

“…The hardnesses of the SC-0.01Al(Si) and SC-0.03Al(Si) solders were approximately 4% and 7% higher than those of the SC07 solder. This appears to be because the Al and Al-Cu IMCs dispersed inside the solders blocked the propagation of cracks that occurred during the hardness test [ 28 ].…”

High Entropy Alloys as Filler Metals for Joining

“…Solders are extensively used in the electronics industry, and with the continual miniaturization of electronic devices, there is increasing need for better performing soldered joints. The main current alloys used for this application are the SAC solders (Sn-Ag-Cu), which have generally suitable mechanical and physical properties though the in-service reliability of these joints is generally lower than with the former Sn-Pb series solders [ 96 , 97 , 98 , 99 ]. Improving the reliability of such joints is a current focus for development, and the desired improvements span several aspects:…”