Phase-shifting Moire Interferometry Research Articles

Measuring Joule heating and strain induced by electrical current with Moiré interferometry

This study proposes a new method to locate and measure the temperature of the hot spots caused by Joule Heating by measuring the free thermal expansion in-plane strain. It is demonstrated that the hotspot caused by the Joule heating in a thin metal film/plate structure can be measured by Phase shifting Moire interferometry with continuous wavelet transform (PSMI/CWT) at the microscopic scale. A demonstration on a copper film is conducted to verify the theory under different current densities. A correlation between the current density and strain in two orthogonal directions (one in the direction of the current flow) is proposed. The method can also be used for the measurement of the Joule heating in the microscopic solid structures in the electronic packaging devices. It is shown that a linear relationship exists between current density squared and normal strains.

233 マイクロIC複合構造物の熱変形計測(OS4 基調講演VII3)

Moire interferometry technique was adopted to analyze the thermal deformations of four kinds of flip-chip devices mounted on FR-4 substrate and multi-layer substrate, with and without underfill. A thermal loading was applied by heating the devices from room temperature to an elevated temperature. The experimental results showed that the underfill gave similar curvatures of silicon chip and the substrate. In the flip-chip devices mounted on the multi-layer substrate, thermal expansion coefficient mismatch between the chip and substrate was reduced, and bending deformations were decreased. The deformation of solder balls in the underfilled flip-chip device mounted on the multi-layer substrate was the least in the four kinds of flip-chip devices. The thermal deformations of Stacked-MCP (Multi Chip Package) were also measured by phase-shifting moire interferometry. Digital image processing was introduced to determine the deformations with a sensitivity of nanometer scale.

Measurements of Near-Tip Displacement Fields, Separated J Integrals and Separated Energy Release Rates for Interfacial Cracks Using Phase-Shifting Moire Interfrometry.

In this paper, first, the concepts of the separated J integrals and the separated energy release rates, which have the physical significance of the energy release rates from corresponding material sides of a bimaterial are briefly presented. Phase-shifting moire interferometry is used to investigate interfacial crack-tip behavior of a bimaterial specimen, which is fabricated of epoxy and aluminum. The loading angle to the interfacial crack is systematically changed. The inplane displacement fields near the interface crack are recorded by the phase-shifting moire interferometry. Using the measured displacement fields, the stress intensity factors and the separated energy release rates are evaluated. From the theoretical and experimental results, it is found that the compliant material (epoxy) side provides considerably larger fracture energy to the interfacial crack tip.

Process zone of polycrystalline alumina

The fracture process zone of two polycrystalline alumina fracture specimens were analyzed by a hybrid experimental-numerical procedure involving a phase-shifting moire interferometry and a finite element analysis. The dissipated energy, which was obtained through numerical analysis, in the fracture process zone was found to be the major energy dissipation mechanism in the brittle alumina.

Strain Fields and Damage around Notches in Ceramic‐Matrix Composites

Strain development in several notched ceramic‐matrix composites (CMCs) has been monitored over a broad range of load. This was achieved by using phase‐shifting moire interferometry, which provides a map of the surface strains. A sequence of fringe patterns was used to chart the evolution of strain redistribution as a function of load. The ensuing strains were related to the micromechanical damage mechanisms. Stress concentrations were estimated from the strains by using stress/strain curves. Implications for the notch sensitivity of CMCs are discussed.