• Vizureanu, Petrica
• Salleh, Mohd Arif Anuar Mohd
• Ramli, Mohd Izrul Izwan
• Chaiprapa, Jitrin
• Abdullah, Mohd Mustafa Al Bakri
• Saud, Norainiza
• Said, Rita Mohd
• Amli, Siti Farahnabilah Muhd
• Sandu, Andrei Victor
• Nabiałek, Marcin
• Rylski, Adam

Abstract

<jats:p>This manuscript reports the isothermal annealing effect on the mechanical and microstructure characteristics of Sn-0.7Cu-1.5Bi solder joints. A detailed microstructure observation was carried out, including measuring the activation energy of the intermetallic compound (IMC) layer of the solder joints. Additionally, the synchrotron µX-ray fluorescence (XRF) method was adopted to precisely explore the elemental distribution in the joints. Results indicated that the Cu6Sn5 and Cu3Sn intermetallic layers thickness at the solder/Cu interface rises with annealing time at a rate of 0.042 µm/h for Sn-0.7Cu and 0.037 µm/h for Sn-0.7Cu-1.5Bi. The IMC growth’s activation energy during annealing is 48.96 kJ mol-1 for Sn-0.7Cu, while adding Bi into Sn-0.7Cu solder increased the activation energy to 55.76 kJ mol−1. The µ-XRF shows a lower Cu concentration level in Sn-0.7Cu-1.5Bi, where the Bi element was well dispersed in the β-Sn area as a result of the solid solution mechanism. The shape of the IMC layer also reconstructs from a scallop shape to a planar shape after the annealing process. The Sn-0.7Cu hardness and shear strength increased significantly with 1.5 wt.% Bi addition in reflowed and after isothermal annealing conditions.</jats:p>

Topics

• impedance spectroscopy
• compound
• strength
• hardness
• annealing
• activation
• intermetallic
• X-ray fluorescence spectroscopy