Graduation Semester and Year
2016
Language
English
Document Type
Thesis
Degree Name
Master of Science in Mechanical Engineering
Department
Mechanical and Aerospace Engineering
First Advisor
Dereje Agonafer
Abstract
The assessment of board level solder joint reliability during thermal cycling is very important for electronic packages. During thermal cycling, the mismatch in Coefficient of Thermal Expansion (CTE) between the materials used in the package induces stress on the solder interconnects and result in deformation stresses. Finite element tools are widely used for rapid design optimization and also for understanding board level reliability issues. Lumped board properties approach, explicit geometry approach, and ECAD approach are the three widely used approaches for creating models for PCBs. In the lumped board properties approach, orthotropic elastic material properties are assigned to PCBs. However, for temperatures near and beyond the glass transition temperature, materials behave in a viscoelastic manner. In which case, considering viscoelastic properties would result in a more accurate representation than the orthotropic elastic lump model. In this thesis, a comparative study on the linear elastic and viscoelastic modeling of PCB is done and how it affects the board level reliability of Packages under thermal cycling. The viscoelastic material properties of PCBs are characterized using dynamic mechanical analyzer (DMA). The frequency and temperature dependent complex moduli are obtained from the DMA. The obtained results are used to model the PCBs as viscoelastic materials on ANSYS. Thermal cycling is performed in ANSYS and the results obtained are compared to those obtained from the elastic modeling of PCBs for WCSP.
Keywords
Viscoelastic modeling, WCSP, Thermal cycling
Disciplines
Aerospace Engineering | Engineering | Mechanical Engineering
License
This work is licensed under a Creative Commons Attribution-NonCommercial-Share Alike 4.0 International License.
Recommended Citation
Anaskure, Avinash, "EFFECT OF VISCOELASTIC MODELING OF PCB ON THE BOARD LEVEL RELIABILITY OF WAFER CHIP SCALE PACKAGE (WCSP) IN COMPARISON TO ORTHOTROPIC LINEAR ELASTIC MODELING" (2016). Mechanical and Aerospace Engineering Theses. 935.
https://mavmatrix.uta.edu/mechaerospace_theses/935
Comments
Degree granted by The University of Texas at Arlington