Deformations of a simplified flip chip structure under thermal testing inspected using a real-time Moiré technique

Abstract

Deformations of a Si-epoxy-FR4 (simplified flip chip) structure under thermal testing were inspected with a real-time Moiré technique. Specimens without cracks and specimens with a crack at the silicon-epoxy interface were prepared. The measurement results showed that the maximum deformation appeared at the edge. When the specimen was cooled to 20 • C, there was residual plastic deformation in the specimen. The creep effect was more dominant in the FR4-epoxy interface. Upon cooling to 20 • C, the specimen experienced partial strain recovery. To characterize the behavior of the interfacial crack, stress intensity factors K I and K II , and the strain energy release rate G in the vicinity of the crack tip were calculated using the measured deformations to conduct a quantitative study. It was observed that a sharp strain gradient occurred at the crack tip. K I and K II were dependent on temperature, and G was dominated by K I for the interfacial crack in the specimen.

Recent Applications of Moiré Interferometry

“…They were employed to study the temperature-dependent thermo-mechanical behavior. The schemes were implemented with convectiontype or conduction-type environmental chambers that provide the temperature control required in accelerated thermal cycling (isothermal loading) [35,41,[50][51][52][53][54][55][56][57][58][59][60][61][62][63][64][65]. Park et al…”

Recent advances in wire bonding, flip chip and lead‐free solder for advanced microelectronics packaging

“…However, reports on inspections/measurements of thermal deformations and strains of electronics packages under thermal testing using real‐time moiré interferometry are still scarce. Therefore, deformations of a simplified flip chip structure under thermal testing were inspected with a real‐time moiré technique (Zhong et al , 2006b). The measurement results showed when the specimen was cooled to 20°C, there was residual plastic deformation in the specimen.…”

The influence of creep on precision stability in precision instruments with assembly errors

“…The mathematical expression of the time hardening model under a uniaxial stress state is as follows: Regarding the issue of adhesive creep in precision instruments, scholars both domestically and internationally have conducted certain research. Foreign scholars such as Ansell et al [8] and Zhong et al [9] have conducted experimental and simulation studies on the influence of creep deformation on epoxy resin lap joints, obtaining quantitative influence laws on creep deformation and creep life. Domestic scholars, including Zhang [10], have conducted simulation calculations and experimental research on the creep deformation of metal plate adhesive structures and metal joint parts, obtaining the creep deformation distribution of the structure and the influence laws on structural performance indicators.…”