Numerical analysis of thermo-mechanical characteristics of solder joint depending on change in solder junction structure of MCP

• This study suggests improved junction structure of solder joint.
• Finite element analysis of existing and suggested solder joint has been carried out.
• Thermo-mechanical reliability of existing and suggested solder joint by numerical analysis has been compared.

This study suggests an improved junction structure of solder joints that enable an increased junction area and enhance the reliability of solder joints. A finite element analysis was carried out to compare the thermo-mechanical characteristics of the solder joints before and after the improvement. In the suggested junction structure, holes were created in the existing Cu pillar bump to increase its junction area, compared to that of the existing junction structure, and to raise the solder quantity of the joint. Drawing from the analysis results of the thermo-mechanical characteristics on the existing junction structure and the newly suggested junction structure, it was confirmed that shear stress was reduced in the solder joint with the suggested junction structure, as it was lower by around 5–20 MPa in the suggested junction structure. It was also found that the final value of the equivalent stress during a thermal cycle was lower by around 30 MPa in the suggested junction structure. Moreover, in terms of its equivalent strain value, the suggested junction structure had a slightly higher value of elastic equivalent strain although it carried a lower value of plastic equivalent strain in the high-temperature range. Therefore, it is considered that the suggested junction structure will be advantageous in terms of its long-term reliability of thermo-mechanical characteristics.