Date of Award


Document Type

Master Thesis

Degree Name

Master of Engineering (Research)


Mechanical Engineering

First Advisor

Mr. Sean F. O'Leary


This project investigates the application of finite element and experimental analysis in the design and testing of silicon based semiconductor components. In a thermal inkjet printer the ink cartridge contains a print head (or die), the head fires numerous droplets simultaneously to form pixels and letters. The inkjet cartridge die consists of a thin film layer, containing the integrated circuits that make up the thennal inkjets, mounted on a polysilicon substrate structure.

A number of incremental changes to the design and manufacturing processes related to the manufacture of these inkjet cartridge dies is made. In past instances when changes were implemented (especially any changes to the slot design), failure rates of the dies during manufacture rose significantly.

Service and manufacturing load conditions for inkjet cartridge dies are simulated. The effect of design alterations on die strength is assessed. Critical material properties are determined by experimental means, including hardness and fracture toughness testing. Fragility testing of the dies is undertaken and close correlation is achieved with developed finite element mathematical models. Strength of materials methodology and photoelastic testing are undertaken to validate developed finite element models and slot end shape stress concentration factors.

The mode of failure of the dies is identified as fracture due to crack propagation at flaws induced during the slot manufacturing process. The stress concentration factors (SCF) present within the dies, due to the presence of the slots, are determined and the influence of these on die failure rates is examined. The optimum geometry for the die slots is identified and important parameters, which could influence the design of future products, are assessed. Changes to the manufacturing process to reduce failure rates are suggested and the results of theses initiatives are briefly discussed, with a view to further improvements.

Access Level