ORCID Identifier(s)

0000-0002-2217-5085

Graduation Semester and Year

2022

Language

English

Document Type

Thesis

Degree Name

Master of Science in Mechanical Engineering

Department

Mechanical and Aerospace Engineering

First Advisor

Agonafer Dereje

Abstract

Micro-via are components that are used to form connections from one layer to another in most Multilayered Printed Circuit Boards (PCBs). The failure of Micro-via has always been a concern of the electronic industry. The failures are exaggerated during the reflow process due to the high thermal loading. Electronic components have become ubiquitous in our society. It is important to take some measures to reduce (or) eliminate the failures at interconnects in the Printed Circuit Board to obtain highly reliable Input/Output (I/O). This work is based on a hypothetical belief that the possible cause of failure is an insufficient or limited time for a Micro-via on the top layer to settle the grain structure from the induced internal stresses from reflow and assembly procedures of manufacturing High-Density Interconnect (HDI) Printed Circuit Board (PCB) with multiple layers along with the depth of via. This can be a valid reason for reliability issues related to Micro-vias that tend to cause failures. So, A finite element model of blind micro-via is developed to meet IPC standards and incorporated into a multi-layered PCB. According to IPC 2.6.27(B) test method, the model is tested with thermal cycling. Further models are modified to verify the effects of the hypothesis the model is modified to simulate the heterogeneous grain boundary by changing the modulus of the blind micro-via along with the depth. Since the blind micro-via goes through the minimum pressure and temperature cycle during the fabrication it is assumed that the annealing of the copper is not fully achieved. It is found that the stress distribution in the blind micro-via is higher for the heterogenous micro-via and is 10.4% higher than the homogenous micro-via for the same Thermal loading condition. Moreover, the stress in the micro-via with the modulus increasing along the depth is higher than the modulus decreasing along the depth.

Keywords

Micro via, Axisymmetric, Reliability

Disciplines

Aerospace Engineering | Engineering | Mechanical Engineering

Comments

Degree granted by The University of Texas at Arlington

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