Date of Graduation

12-2023

Document Type

Thesis

Degree Name

Master of Science in Mechanical Engineering (MSME)

Degree Level

Graduate

Department

Mechanical Engineering

Advisor/Mentor

Huitink, David

Committee Member

Millett, Paul C.

Second Committee Member

Song, Xiaoqing

Keywords

Accelerated Testing; Combined Stresses; Elecromigration; Electronics Packaging; Microelectronics Reliability; Solder Reliability

Abstract

With the densification of power electronics in the pursuit of decreased size and weight and increased efficiency, the need to investigate the properties of solder in packages with higher working temperatures and power densities is becoming apparent. Many research groups have conducted accelerated testing using methods such as thermal aging, shear or tensile stress tests, or electromigration tests, but relatively little research exists that considers the impact of several stresses in a combined study. This work aims to produce a novel method for estimating the lifetime of SAC305 solder joints under a combined stress scenario, which more accurately depicts the stress profile in real-world applications. Samples are fabricated and placed in an oven where constant current and constant shear stress are applied to the sample via power supply and a fabricated shear stress applicator, respectively. The health of the solder joints is monitored via 4-wire Kelvin resistance measurement. After testing, changes in microstructure of the samples can be evaluated via cross-sectioning and optical/scanning electron microscope. By varying the levels of temperature, current, and shear stresses applied to the sample, a regression model will be created to model the lifetime of the solder when all three stresses are taken into consideration. Using ANSYS to extract stress information from FEA analysis, the model is utilized to make an informed estimation of the operating lifetime of a cutting-edge flip chip MOSFET.

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Available for download on Friday, February 06, 2026

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