Effect of Au-Coating on the Laser Spot Cutting on Spring Contact Probe (SCP) for Semi-Conductor Inspection

Spring contact probes (SCPs) are used to make contact with various test points on printed circuit boards (PCBs), wire harnesses, and connectors. Moreover, they can consist of the test interface between the PCBs and the semiconductor devices. For mass production of SCPs, ultra-small precision components have been manufactured by conventional cutting methods. However, these cutting methods adversely affect the performance of components due to tool wear and extreme shear stress at the contact point. To solve this problem, laser spot cutting is applied to Au-coated SCP specimens as an alternative technique. A 20 W nano-second pulsed Ytterbium fiber laser is used, and the experimental variables are different laser parameters including the pulse duration and repetition rate. After the spot cutting experiments, the heat-affected zone (HAZ) and material removal zone (MRZ) formed by different total irradiated energy (Etotal) was observed by using a scanning electron microscope (SEM). Then, the size of HAZ, top and bottom parts of MRZ, and roundness were measured. Furthermore, the change rate of HAZ and MRZ on Au-coated and non-coated specimens was analyzed with regard to different pulse durations. Based on these results, the effect of Au-coating on the SCP was evaluated through the comparison with the non-coated specimen. Consequently, in the Au-coated specimen, hole penetration was observed at a low pulse duration and low total energy due to the higher thermal conductivity of Au. From this study, the applicability of laser spot cutting to Au-coated SCP is investigated.

ORES: a chassis dynamometer for off-road vehicles

Off-Road Environment Simulator (ORES) is a Real-time Hardware-in-the-Loop (RT-HIL) platform to simulate the dynamic response of off-road vehicles. This paper primarily focuses on the vehicle model development and validation using both field and rig testing using the ORES platform. Off-road vehicles are capable of operating on bumpy terrains where they are subjected to different resistive wheel torques due to non-unique ground friction conditions and wheel loads. If the powertrain torque output is not distributed in accordance with the resistive wheel torques, it may lead to transmission windup resulting in premature failure of various driveline components. In this study, the vehicle is driven over discrete bumps both in rig simulation and field trial. Different terrain enveloping models were evaluated namely the single point, radial-spring contact model and two-point follower (using circular and sinusoidal basis). These models were evaluated against the measured wheel acceleration responses. The two-point follower with sinusoidal basis strongly correlates with the measured responses and the ground excitations so obtained were used as inputs to a seven degree-of-freedom vehicle ride model. Ride model calculates the wheel loads and is eventually integrated with longitudinal dynamics, tire, driveline and test-rig models. Vehicle axle acceleration, wheel speed and drive torque responses are measured for validating the simulation results against field and rig trials. The field responses matches fairly well which validates the suitability of the proposed modeling approach.

Dynamic characteristic of partially debonded sandwich of ferry ro-ro’s car deck: a numerical modeling

The dynamic behavior of a partially debonded Ferry Ro-Ro’s sandwich car deck is investigated by using commercial finite element software ABAQUS. Debonding in the car deck model is estimated by comparing the dynamic responses of the fully intact and damaged model of the bonding condition. The influence of the debonding ratio is investigated by free vibration analysis using Lanczos iteration method. The dynamic response of the car deck model is loaded with harmonic excitation and is examined in detail. The transverse displacements, velocities, accelerations, longitudinal strains, and phase portraits are investigated in the central point of the damaged area. To evaluate the effect of inserting the spring contact element during the dynamic analysis, both debonded models with and without spring contact elements are examined. From the report, it can be concluded that the dynamic analysis which relies on the modal analysis can be used to diagnose the possibility of debonding problem in the car deck structure. The natural frequencies of the debonded model decrease due to the presence of discontinuity in the debonded region. Further, the discontinuity also creates locally concentrated deformation and significantly affects the short-term time response.