Heterogeneous integration approach based on flip-chip bonding and misalignment self-correction elements for electronics-optics integration applications

This paper presents a high precision bonding approach, capable of submicron alignment accuracy, based on the thermosonic flip-chip bonding technique and misalignment self-correction elements. The precision of the bonding technique is guaranteed by using of misalignment self-correction bump (convex) and hollow (concave) elements. Metal cone bump and conductive sloped hollow bonding pad elements are created using micro-machining techniques, on a chip specimen and substrate, respectively. The chip and substrate are bonded face-to-face using of an ultrasonic-enhanced flip-chip bonder. By introducing of misalignment self-correction elements, repeatable bonding accuracies of less than 500 nm were confirmed through experimental investigation. Bond properties, including electrical and mechanical properties, are also characterized to confirm the success of the bonding approach. With the obtained results, the proposed bonding approach is capable of being use in electronics-optics heterogeneous integration applications

Background Factors Affecting Visual Acuity at Initial Visit in Eyes with Central Retinal Vein Occlusion : Multicenter Study in Japan

Purpose: To determine the baseline characteristics of patients with central retinal vein occlusion (CRVO) that were significantly associated with the best-corrected visual acuity (BCVA) at the initial examination. Methods: This was a retrospective multicenter study using the medical records registered in 17 ophthalmological institutions in Japan. Patients with untreated CRVO (≥20-years-of-age) who were initially examined between January 2013 and December 2017 were studied. The patients’ baseline factors that were significantly associated with the BCVA at the initial examination were determined by univariate and multivariate linear regression analyses. Results: Data from 517 eyes of 517 patients were analyzed. Univariate analyses showed that an older age (r = 0.194, p < 0.001) and the right eye (r = −0.103, p < 0.019) were significantly associated with poorer BCVA at the initial visit. Multivariate analyses also showed that an older age (β = 0.191, p < 0.001) and the right eye (β = −0.089, p = 0.041) were significantly associated with poorer BCVA at the initial visit. Conclusions: The results indicate that an older age, a known strong factor, and the right eye were significantly associated with poorer BCVA at the initial visit to the hospital. These results suggest that functional and/or anatomical differences between the right and left eyes may be involved in these results

Mechanical Property of F82H Steel Doped with Boron and Nitrogen *

Dependence of fracture properties and hardening was examined as a function of helium production in tensile specimens of a martensitic steel F82H (Fe-8Cr-2W-0.1C-0.04Ta) irradiated at 300 C to 2.3 dpa by neutron irradiation in the JMTR (Japan Materials Testing Reactor). The specimens used in this study were F82H, F82H+60 ppm 11 B, F82H+30 ppm ( 11 B+ 10 B) and F82H+60 ppm 10 B. The helium range produced from 10 B (n,) 7 Li reaction was from 5 to 330 appm in the specimens. The tensile testing was performed at 25 C. The radiation hardening due to helium production was detected at 330 appmHe. The degradation of fracture stress due to helium production was approximately evaluated from the fracture strength and the reduction area. Effect of specimen size on tensile and Charpy impact properties in F82H doped with 60 ppm boron and 200 ppm nitrogen was also examined. The JIS 14A and SS-J3 (Small Size-Japanese-3 type) were used for the tensile specimens, and half size (55 mm in length, 10 mm in height and 5 mm in width) and 0.5-1/3CVN (18 mm in length, 3.3 mm in height and 1.65 mm in width) were used for the Charpy impact testing. The tensile properties were a similar to each other. However, the ductile-brittle transition temperature measured in smaller size specimen was somewhat lower than that in the standard size specimen

Original data used in this article are included.

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