比田井 洋史

The effects of the ambient temperature and relative humidity on crack propagation behavior during wheel scribing were investigated. A chamber was built to allow dynamic observation of crack propagation behavior in a controlled atmosphere. A developed miniature scriber was installed in the chamber, and the crack propagation behavior was observed from lateral and back sides during wheel scribing under various atmospheric conditions. As a result, the median crack propagation rate increased with relative humidity. We speculated that this was caused by the stress corrosion of glass. Although stress corrosion is considered to be more reactive at higher temperatures, the results of scribing at different temperatures showed that higher temperatures did not necessarily increase median crack propagation. This is due to the formation of lateral cracks before the median cracks have fully propagated. These results suggest that the interaction between multiple cracks should be considered when discussing the effects of temperature and humidity in wheel scribing.

固体イオン交換法によって銀イオン添加された試料に対し，電圧を印加することでガラス内に銀を析出させることができる．本手法は，ガラス内部に微細な導電路を形成する技術として期待されているが，析出物の形状制御手法が確立されていない．ここで，銀析出はき裂の生成をともなって進行することが確認されている．そこで本研究では，ホイール操作，レーザ照射を用いたき裂作成による析出物の誘導を行い，その原因を考察した．

Abstract Internal and local modifications via ultrashort pulsed laser illumination to diamond are promising for manufacturing diamond electronic devices. The relationship between the diameter/electrical conductivity of modified regions and the laser fluence distribution was investigated. Picosecond laser illumination without scanning the laser focus fabricated short modified regions in diamond. As a result, the calculated laser fluence distribution matches the distribution of the modified regions. Wire-shaped modified regions were fabricated via laser illumination with scanning of the laser focus, and the corresponding diameter and electrical conductivity were investigated by controlling the laser focus movement distance per pulse (V_f). The modified regions fabricated with varying V_f were divided into three categories depending on the trend of the relationship between the diameter and electrical conductivity. The diameters of the modified regions were constant at the maximum values when V_f was sufficiently small, decreased with increasing V_f, and reached a minimum when V_f was sufficiently large. The modified regions became more electrically conductive with increasing V_f, even when the deposited energy per unit length decreased. Moreover, the electrical conductivity decreased significantly when the diameter became constant at the minimum value. Finally, the relationship between the diameter/electrical conductivity of the modified regions and the laser fluence distribution was elucidated.

In laser cleaving, the thermal stress caused by laser heating and water-jet cooling propagates previously induced cracks in the workpiece material. The laser-cleaving conditions affect the quality of the fracture surface, and therefore, elucidating the relationship between the cleaved surface, cleaving conditions, and crack propagation is essential. Against this backdrop, in this study, we investigated the morphology of the cleaved surface and visualized the crack propagation and stress <italic>in situ</italic> using a high-speed polarization camera. The distance between the glass edge and cleaved surface was varied. When the laser-cleavage line was close to the glass edge, twist hackles were formed on the cleaved surface. The area in which the twist hackles formed on the cleaved surface coincided with the lagging section of the crack front. Furthermore, the twist hackle reached the specimen surface, and the edge of the surface exhibited a sawtooth shape. Observations with the high-speed polarization camera revealed that the internal stress was asymmetric with respect to the crack when the twist hackles were formed.

<p>The authors have reported the laser-induced metal sphere migration in the glass. The metal sphere migrated toward the light source along the optical axis. In this paper, we describe the metal sphere separation by two laser beam illumination from the opposite direction. A stainless-steel sphere in borosilicate glass was heated by two continuous-wave green laser illumination. The laser beam diameter influenced the separation result. One metal sphere was separated to two spheres, when the beam diameter was 60 and 80 µm. When the beam diameter was 100 µm, the one metal sphere was not separated and maintained the shape and migrated toward one direction. When the beam diameter was 20 and 40 µm, laser illumination separate two small sphere from the metal sphere and one metal sphere was left. Hence the one metal sphere separated to three metal spheres. In-situ observation with a high-speed camera and numeral temperature calculation clarified the separation process. Finally, the size control of the metal sphere was demonstrated by changing the beam diameter.</p>

ガラスに添加された銀イオンを還元することで，ガラス内部に樹状の銀析出物を形成する手法がある．この銀析出物はガラス内に直径約200 nmの微細な亀裂を形成することから，銀析出したガラス内の表面積は増加する．この銀析出ガラスをフッ酸によって湿式エッチングを行ったところ，析出領域のエッチングレートが1.9 μm/minとなり，母材ガラスよりも3.3倍大きくなった．この手法を利用しガラスに直径1.16 mm，深さ0.095 mmの貫通穴を形成した．

At the joints of the mechanical systems, it is well known that the parameters such as contact stiffness, static friction coefficient, kinetic friction coefficient and attenuation coefficient affect static, kinetic, thermal and motion characteristic of them strongly. In these parameters, the static friction coefficient reigns the character of maximum fixing resistance. However, there’s difficulties for measure the precise static friction coefficient on the coupling surfaces due to tiny contact surface, unstable loading method and moment force acts on the contact surface of the former device. Therefore, we developed novel measurement device and evaluated influence of the surface parameters given to static friction coefficient. Through the validity evaluation, it was confirmed that the new measurement device enables face contact and uniform surface pressure. In addition, there's no moment force by optimizing the loading position of the tangential force. Furthermore, validity of the static friction coefficient was checked and verified that frequency of the sampling rate is fine enough. Finally, we proceeded to applied test with this new measurement device for evaluate the influence of the surface roughness and grinding direction given to static friction coefficient. A pair of die steels and cemented carbides was selected for specimen and static friction coefficient was measured under 60 MPa of contact pressure. Regarding influence of surface roughness, the result showed tendency that rougher surface generates lower value of the static friction coefficient. Now for grinding direction, combination of the specimen ground in orthogonal direction against tangential force showed maximum value and the specimen ground in parallel direction against tangential force showed minimum.

The authors reported that laser illumination to a metal sphere in glass migrated the metal sphere toward the light source. The migration was caused by interfacial tension gradient. In this presentation, we demonstrate the metal sphere separation by the two laser beam illumination from opposite direction. The metal sphere separation was not explained by the interfacial gradient and suggested the existence of pulling force to the light source side.

<p>端面に金属箔を密着させたガラスへ，反対面からレーザを照射すると，金属球がガラス内部へ導入される．導入効率の向上，直径の制御を目的に，新たな導入手法の提案およびスポット径，出力，スキャン速度を変数とした導入現象の観察を行った．その結果，スポット径の増大により，金属球の直径は12μm～65μmで単調増加した．また，出力の増大により，金属球の直径は減少した．適切なスキャン速度は，導入効率を向上させた．</p>

© Optics & Photonics International Congress 2019. The authors have been proposed metal sphere manipulation in glass. Laser illumination to a metal sphere in glass heated the sphere, and surrounding glass was also heated by the thermal conduction and softened. In this paper, we report a nickel sphere migrated in a crystallized glass. After the migration, the composition of the migration trajectory and nickel sphere was measured with electron probe microanalyzer. As a result, the amount of phosphorous in the trajectory of glass decreased, and the nickel sphere contained phosphorous.

ホイール割断はガラス基板の分断に広く用いられているが，割断面形成挙動の理解は完全ではない．そこで，本研究では割断面形成メカニズムの解明を目的とし，亀裂伸展挙動の動的観察および割断面の3次元的観察を行った．その結果，特徴的な2種類の亀裂伸展挙動とそれらに対応する割断面形態が観察された．また，亀裂伸展挙動は工具形状に応じて変化しており，工具形状の工夫により割断面形態が向上する可能性を示した．

The tensile thermal stress generated by laser irradiation with forced cooling is critical in the cleavage processing of thin plate glass. In this study, we predicted the conditions for generating tensile thermal stress in laser-induced cleavage of thin plate glass using numerical models from the viewpoint of the cooling and heating areas. An unsteady two-dimensional model was used to predict the temperature distribution and an unsteady plane stress model was used to predict the thermal stress. To generate tensile thermal stress, a cooling area is required behind the heating area. A specific scanning speed is required to yield the maximum tensile stress between the heating and cooling areas. A weak heat transfer coefficient in the cooling area generates tensile thermal stress only in the direction perpendicular to (y direction) the scanning direction of the heat source (x direction). A strong heat transfer coefficient generates tensile thermal stress in both the x and y directions. These tensile thermal stresses are surrounded by horseshoe-shaped compressive thermal stress. The tensile thermal stress can be controlled by selecting an appropriate cooling method for the cooling area.