The purpose of this paper is to find bonding parameters of electrodes between the metal printed circuit board (PCB) and flexible PCB using ultrasonic vibration. The electrodes of FPCB were electroless-plated with electroless Ni/immersion Au (ENIG) and those of metal PCB were also electroless-plated with ENIG. The peel strengths of the joints were investigated with various parameters, such as bonding pressure and time. This study showed that the electrodes between the metal PCB and FPCB were successfully bonded without any adhesive at a low temperature during a short time, compared to other bonding methods: adhesive bonding and thermo-compression bonding.

View full abstract

In this study, the measurement ability of temperature rise in the split TMM by using infrared images are estimated by using the standard ultrasonic source. The simple relation among the radiated acoustic energy, the energy for generating temperature rise in TMM and the diffused energy in TMM and ambient was investigated on the actual infrared image with improved split TMM. Consequently, radiated acoustic energy, E_P and the summation of the energy for generating temperature rise and the diffused energy, E_A + E_B agreed within the variation of repeatability. From these experimental resuls, it is found that the proposed measurement system and method are appropriate for the measurement of temperature rise by ultrasonic irradiation.

View full abstract

In this study, the propagation behaviors of acoustic waves propagating along the wedge tips is investigated. Using laser ultrasound technique (LUT) and finite element method (FEM) to characterize the anti-symmetrical flexural (ASF) modes propagation along wedge tips with a small notch. The mode conversion (MC) will emerge when ASF wave encounting a defect on the wedge tip. Reflection coefficients (RC) and transmission coefficients (TC) are obtained and calculated from the simulation and measurement results with different defect depths on the wedge tip.

View full abstract