Aging Characteristics of Sn-Ag Eutectic Solder Alloy with the Addition of Cu, In, and Mn

Abstract

In the present investigation, three types of solder alloy, i.e., Sn-Ag-Cu, Sn-Ag-In, and Sn-Ag-Cu-Mn, have been prepared and joined with Cu substrate. In the reflowed condition, the joint interface is decorated with Cu 6 Sn 5 intermetallic in all cases. During aging at 100°C for 50 to 200 hours, Cu 3 Sn formation took place in the diffusion zone of the Sn-Ag-Cu and Sn-Ag-In vs Cu assembly, which was not observed for the Sn-Ag-Cu-Mn vs Cu joint. Aging also leads to enhancement in the width of reaction layers; however, the growth is sluggish (~134 KJ/mol) for the Sn-Ag-Cu-Mn vs Cu transition joint. In the reflowed condition, the highest shear strength is obtained for the Sn-Ag-Cu-Mn vs Cu joint. Increment in aging time results in decrement in shear strength of the assemblies; yet small reduction is observed for the Sn-Ag-Cu-Mn vs Cu joint. The presence of Mn in the solder alloy is responsible for the difference in microstructure of the Sn-Ag-Cu-Mn solder alloy vs Cu assembly in the reflowed condition, which in turn influences the microstructure of the same after aging with respect to others.

Interfacial Reactions of Sn-3.0Ag-0.5Cu Solder with Cu-Mn UBM During Aging

“…Apart from reducing the thickness of the Cu 3 Sn layer, the formation of Kirkendall voids was also suppressed in the SAC305/Cu-2Mn solder joint. Segregation of minor alloying elements at the solder/substrate interface was also observed by Ghosh et al, 21 who reported that the formation of Cu 3 Sn was hindered and the growth of existing Cu 6 Sn 5 became sluggish during aging when Mn was added to Sn-Ag-Cu solder. X-ray elemental mapping in this study revealed that Mn suppressed the growth of Cu 3 Sn directly through segregation in the IMC.…”

A Comparative Study on the Influence of SAC305 Lead‐Free Solder Sandwiched by Sn on the Micromechanical and Electrical Properties of the Joints

“…Analyses of recorded XRD patterns obtained from different zones (layers) across the interface further confirms the presence of different intermetallic phases having a stoichiometry of Cu 3 Sn (ε‐phase orthorhombic) and Cu 6 Sn 5 (η‐phase monoclinic) along with the β‐Sn phase (BCT) for both the solder joints. Kar et al [ 32 ] and Ghosh et al [ 33 ] in their previous studies also found the presence of similar intermetallics phases for other types of solder joints.…”

The effects of Mn powder additions on the microstructures and tensile property of SnAgCu/Cu solder joints

“…During aging process, the growth of IMC layer in SnAgCu/Cu was faster than that of SnAgCuMn/Cu. Mn addition promoted the nucleation of b-Sn and Cu 6 Sn 5 since it provided nucleation sites for b-Sn in alloys matrixes and Cu 6 Sn 5 in reaction layers [14]. The addition of Mn reduced the supercooling degree of solder alloys and coarsened the grain of dendrite Sn and IMCs in the interface significantly.…”

“…Lin et al [13] reported that alloying of Mn and Ti dramatically decreased the under cooling of solder alloys, extended volume fraction of proeutectic Sn, formed heterogeneous IMCs (MnSn 2 and Ti 2 Sn 3 ) and changed the morphology and distribution of eutectic IMCs. Ghosh et al [14,15] explored the effects of Cu, In and Mn additions on the properties of the SnAg eutectic solder alloy. The results showed that the additions of either Cu or Cu-Mn had negligible effects on the melting point of Sn3.5Ag solder alloy.…”