Graduation Semester and Year

2017

Language

English

Document Type

Thesis

Degree Name

Master of Science in Mechanical Engineering

Department

Mechanical and Aerospace Engineering

First Advisor

Dereje Agonafer

Second Advisor

Seiichi Nomura

Abstract

Solder joint interconnects are the second level assembly in surface mount interconnection technology. Mismatch in the coefficient of thermal expansion (CTE) between package and substrate or PCB creates failure in solder joints such as excessive warpage, low-k dielectric cracking, solder mask cracking and bump cracking. Conventional accelerated thermal cycling tests are performed to evaluate the Solder Joint Reliability (SJR). But, in everyday application, the package is subjected to Power cycling. Power cycling is the phenomenon where the package experiences non-uniform temperature distribution in the package with the chip as an internal heat generating source when an electronic device is turned on and off several times. This induces thermal stresses and deforms the package. High frequency laminates offer better fatigue life when compared with the traditional FR-4 material. In addition to the fatigue life they also possess properties like good impedance control, low moisture absorption capacity and improved thermal management. In this study, maximum accumulated plastic work per cycle is used as a parameter to estimate the life of the package in number of cycles it takes for failure at the solder joint interconnects. The reliability of the solder joint interconnects of a BGA package on various Megtron series boards is assessed and compared with FR-4 board under power cycling.

Keywords

Solder Joint Reliability (SJR), Coefficient of thermal expansion (CTE), Power cycling, High frequency laminates, Plastic work

Disciplines

Aerospace Engineering | Engineering | Mechanical Engineering

Comments

Degree granted by The University of Texas at Arlington

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