TY - THES

T1 - Investigation of the lifetime of sintered interconnects in power electronics

AU - Prutti, Maria Theresa

N1 - embargoed until 23-04-2029

PY - 2024

Y1 - 2024

N2 - This thesis examines the lifetime of sintered silver and copper interconnects in power electronic applications. Therefore, shear test samples were designed and prepared. The sintered samples were thermally aged using a thermal shock test. The analysis included the observation of the microstructure, elastic modulus and hardness of the sintered silver and copper-material as well as their adhesion towards surrounding interface materials after defined thermal cycling sequences. For the evaluation of the microstructure scanning electron microscopy (SEM) images were taken and electron backscatter diffraction was performed. SEM images were used to evaluate the porosity of the sinter materials. The elastic modulus and hardness were analyzed by nanoindentation. The adhesion was measured using the shear test method. The material data of both chosen sinter materials was gathered during the different stages of thermal cycling and evaluated separately. The microstructure and physical properties change considerably in the initial thermal cycling, which points to an incomplete sintering with the chosen sinter parameters. The adhesion of the Ag material to the Cu surfaces is considerably lower than with the Cu material. The average shear test values after thermal cycling in the Cu samples is about 15% higher than in the Ag samples. In the Ag sample a slight thermal degradation in the shear test values is found. No such degradation is apparent in the Cu samples, indicating good long-term reliability.

AB - This thesis examines the lifetime of sintered silver and copper interconnects in power electronic applications. Therefore, shear test samples were designed and prepared. The sintered samples were thermally aged using a thermal shock test. The analysis included the observation of the microstructure, elastic modulus and hardness of the sintered silver and copper-material as well as their adhesion towards surrounding interface materials after defined thermal cycling sequences. For the evaluation of the microstructure scanning electron microscopy (SEM) images were taken and electron backscatter diffraction was performed. SEM images were used to evaluate the porosity of the sinter materials. The elastic modulus and hardness were analyzed by nanoindentation. The adhesion was measured using the shear test method. The material data of both chosen sinter materials was gathered during the different stages of thermal cycling and evaluated separately. The microstructure and physical properties change considerably in the initial thermal cycling, which points to an incomplete sintering with the chosen sinter parameters. The adhesion of the Ag material to the Cu surfaces is considerably lower than with the Cu material. The average shear test values after thermal cycling in the Cu samples is about 15% higher than in the Ag samples. In the Ag sample a slight thermal degradation in the shear test values is found. No such degradation is apparent in the Cu samples, indicating good long-term reliability.

KW - Interconnect techology

KW - lifetime of sintered interconnects

KW - silver sinter

KW - copper sinter

KW - Ag sinter

KW - Cu sinter

KW - die attach

KW - power electronics

KW - Verbindungstechnik

KW - Lebensdauer von gesinterten Verbindungen

KW - Silbersinter

KW - Kupfersinter

KW - Ag-Sinter

KW - Cu-Sinter

KW - Die Attach

KW - Leistungselektronik

M3 - Master's Thesis

ER -