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

Failure analysis and its effects are major reliability concerns in electronic packaging. More accurate fatigue life prediction can be obtained after the consideration of all affecting loads on the electronic devices. When an electronic device is turned off and then turned on multiple times, it creates a loading condition called power cycling. The die is the only heat source causing non-uniform temperature distribution. The solder joint reliability assessment of Quad Flat no-lead Package (QFN) is done through computational method i.e. Finite element analysis (FEA) under two different loads. In this paper, the power cycling and thermal cycling act as a combined load. The reliability assessment is done to check stress distribution on PCB board and solder joint. The life to failure is determined for QFN package assembly. The mismatch in coefficient of thermal expansion (CTE) between components used in QFN and the non-uniform temperature distribution makes the package deform. Modeling of life prediction is usually conducted for Accelerated Thermal Cycling (ATC) condition, which assumes uniform temperature throughout the assembly. In reality, an assembly is also subjected to Power Cycling (PC) i.e. non-uniform temperature with chip as the only source of heat generation. This work shows performance of QFN package assembly under thermal and power cycle in combine and also the stress distribution and plastic work for the package.

Keywords

Power cycling, Thermal cycling

Disciplines

Aerospace Engineering | Engineering | Mechanical Engineering

Comments

Degree granted by The University of Texas at Arlington

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