Fast and accurate measurement of thin film thickness across semiconductor wafers is critical for improving production efficiency. Conventional spectral interferometry achieves nanometer-scale precision but requires over an hour for processing due to extensive spectral data acquisition and analysis. This paper proposes a rapid measurement method using only the centroid wavelength (CWL) of the reflected spectrum, eliminating the need to process full spectral distributions. Three CWL images are captured using a λ-Capture^® camera under different illumination spectra, and film thickness is determined via maximum a posteriori estimation. To suppress measurement errors from local instabilities, we introduce a dense CRF-based optimization model based on spatial continuity in the CWL images. Experiments on 8-inch wafers demonstrate that our method reduces processing time from 88 minutes to under 3 seconds while achieving measurement accuracy with error rates below 1%, meeting practical semiconductor manufacturing requirements across film thicknesses of 200-800 nm.

This paper proposes a dynamic angular transmission error (ATE) compensation method in strain wave gearing, aiming to suppress vibrations by a feedforward control approach. In mechanisms incorporating strain wave gearing, significant issues arise when the frequency of the ATE coincides with the resonant frequency of the mechanical system. The proposed method enables the design of a dynamic ATE compensator based on the system's frequency response, using control system structure, control parameters, and ATE characteristics as design inputs. Notice here that it does not require prior knowledge of load inertia or the stiffness of the reduction mechanism, and it is applicable regardless of the control system configuration. The compensator is implemented as a linear interpolation lookup table that adjusts the compensation according to motor velocity. The effectiveness of the proposed method is validated through both numerical simulations and experimental evaluations using a prototype positioning device equipped with strain wave gearing.

This paper presents an adaptive dynamic angular transmission error (ATE) compensation method in strain wave gearing, employing a feedforward control approach to suppress vibrations excited by ATE. In such mechanisms, significant issues can arise when the frequency of the ATE coincides with the mechanical system's resonant frequency. The ATE is caused by manufacturing and assembly errors, and its characteristics are determined during the assembly process, leading to variations among products. The proposed method is particularly suitable for semi-closed loop control systems. It estimates and compensates for ATE characteristics after assembly without requiring additional sensors such as load-side encoders or laser trackers. Specifically, the proposed method comprises: (1) the design of a dynamic ATE compensator using the control system structure, control parameters, and estimated ATE characteristics as design inputs, (2) an ATE estimation mechanism based on a reaction force observer, and (3) an adaptive algorithm for auto-estimation of ATE characteristics. The effectiveness of the proposed method is validated through numerical simulations and experimental evaluations using a prototype positioning device equipped with strain wave gearing.

In this study, we aim to elucidate processing phenomena to establish a novel quality inspection method for laser blind via hole drilling of Printed Wiring Boards (PWBs), which are used in all kinds of electronic devices. First, we investigated how the copper foil, glass cloth, and epoxy resin that make up the PWB contribute to the light emitting phenomenon by creating and drilling samples with different configurations and observing the light emitting phenomenon with a hig h-speed camera and image two-color method. As a result, the light emitting was observed in the form of granular scattered objects and over a wide area. It was found that the granular objects were scattered glass emitting thermal radiation at high temperature and their temperature was over 1100 °C. Next, we quantitatively evaluated the causal relationship between the glass cloth thickness, the surface absorption rate, the drilled hole shape, and the light emitting phenomenon using structural equation modeling. As a result, it was found that the influence of the surface absorption rate on the drilled hole shape is relatively small compared to the thickness of the glass cloth and is negatively correlated with the light emitting time of the copper foil. The thickness of the glass cloth was also found to influence the area where light emitting can be observed. However, it was found that the shorter the drilling time, the more complex the processing phenomena became.

In this study, 1-pass bead-on-plate welding was performed using low-transformation-temperature welding materials under constant voltage and current condition with various shielding gas compositions to investigate stress concentration at the wel d toe. Tensile fatigue tests were also conducted using specimens with the weld bead to examine the effect of shielding gas composition on the fatigue life. The stress intensity factor at the weld toe was lowest when Ar shielding gas was used, extending the fatigue life at the stress amplitude of 140 MPa by approximately 1.7 times, compared with CO2 containing shielding gas. Controlling the weld toe shape require managing the bead width and excess volume. Under constant voltage and current condition, reducing stress intensity factor at the weld toe can be achieved by increasing toe radius and reducing reinforcement contact angle relative to the bead width.