Hitoshi Suwabe

A study on combined vibration drilling by ultrasonic and low-frequency vibrations for hard and brittle materials

This research aims to improve machining accuracy concerning the method of drilling ceramics and other hard and brittle materials as well as to establish a drilling technology that would ensure high efficiency and longer life of tools. Specifically, the authors contrived a new drilling method that combines ultrasonic vibrations of a diamond core drill and low-frequency vibrations of the workpiece and produced a combined vibration drilling apparatus experimentally. In this paper, the combined vibration drilling apparatus is used for a series of experiments under different vibration conditions to examine the behavior of drilling force, drilled hole accuracy, and edge chipping on the drilled hole surface. In addition, the behavior of tools during combined vibration drilling are theoretically examined. As a result of these considerations, the authors found that combining ultrasonic and low-frequency vibrations is one of the most effective methods for drilling hard and brittle materials.

A Basic Study of the Behavior of Slurry Action at Multi-Wire Saw

The workpiece descent type multi-wire saw uses a slicer to di ce sil con wafers. This slicing method uses a cutting fluid mixed with abrasive grains, which is ca lled s slurry. The slurry is applied on the wire tool to be carried into the processing area. Therefore, t he adhesion conditions and the action of the slurry affect the slicing characteristics. In t his project, the relation between the slurry action and the slicing characteristics was studied. The processing mechanism of a multi-wire saw with a descending workpiece was investigated. Introduction The multi-wire saw is one of the processing methods to slice the larg -sized silicon ingot. This slicing method uses the water as cutting fluid mixed abrasive grains (sl urry). This slurry is supplied on the wire tool and carried in the processing area. The slurry amount whic h enters in the processing area changes owing to each adhesive conditions and actions of slurry. And, these slurry characteristics affect on slicing efficiency. Therefore, the authors mainly paid a ttentions to slurry actions on the wire tool of multiwire saw. This study aims to clear the processing mechanisms of multi-wire saw to descend the workpiece from the relation between slurry actions and sl icing characteristics. In this report, authors observed slurry actions by a high speed camera and slic ed the workpiece by using multi-wire saw. The influence between slurry actions and slicing characteristics (processing efficiency and wafer accuracy) was studied under one series of t he slicing conditions. As the results of slicing, it was clear that the film between the wire tools ha d considerably an influence on slicing efficiency and wafer accuracy. Experimental Apparatus and Method Figure 1 shows the mechanism of multi-wire saw to descend the workpi ece. The piano wire fed from new the wire bobbin is wound on the winder bobbin through the parts of seesaw, f our grooved rollers to guide the wire at the processing area. The wire tool repeats th motion of going and returning at the processing area. The slurry is supplied continuously and uniformly on the w ire of both sides of the workpiece. The supplied slurry at the processing area is collected in he slurry tank and it is re-used. After the processing, the processing efficiency and wafer accuracy are mea sured. Figure 2 shows the observation points of slurry actions. As the slurry actions on the wire change by each supplying conditions of slurry, the slurry actions during the slici ng process are observed by a high speed camera. There are three observation points. The point (A) is he slurry supplying point, the point (B) is the middle point between the slurry supplying point and edge of the workpiece, and the point (C) is the edge of the workpiece. Table 1 shows the main experimental conditions. Key Engineering Materials Online: 2003-04-15 ISSN: 1662-9795, Vols. 238-239, pp 89-92 doi:10.4028/www.scientific.net/KEM.238-239.89

Effects of Thermal Deformation of Multi-Wire Saw’s Wire Guides and Ingot on Slicing Accuracy

Warp accuracy and nanotopography in the silicon wafer slicing process influence the final quality of the wafer. Therefore, methods to improve these factors are important. And this will require the achievement of low costs and high quality processing – conflicting requirements – with larger sized wafers than in previous generations. The present study was performed to assess mechanical factors, such as machine static accuracy and thermal deformation, to improve the accuracy of multi-wire saws. This report deals with the influence of thermal deformation of the ingot and wire guides upon processing accuracy, and describes the assessment results.

Effect of working fluid for reduction of edge chipping on ID-Blade sawing.

At the edge portion of the wafer sliced in ID-Blade sawing, edge-chippings are usually broken out. This has become an important factor which should be improved in the manufacturing process of semiconductor devices. This study aims to reduce the edge chipping size by means of utilizing slurry which mixed a little free abrasive grains into the working fluid. This method brought the buffer effect between diamond grains adhered to the ID-Blade and the edge portion of workpiece. In this paper, reduction of the edge-chipping utilized slurry and influence of engage and disengage angle of ID-Blade to the workpiece are described. Consequently, edge-chipping size at the edge portion of the wafer was reduced compared with the case in which usual working fluid is used and it became small when an engage and disengage angle are shallow.

A study on vibration screw thread tightening by means of pneumatic control.

In the previous report, the vibration screw tightening method using a D. C. motor was discussed. In the results it was clear that the vibration tightening torque coefficient decreased more than the ordinary tightening torque coefficient, and the amount of scatter of the vibration tightening torque coefficient also decreased and then the screw thread tightened by the vibrational method was hard to loosen. In this report the pneumatic method using an air motor is studied. It is a more compact and controllable device in comparison with the vibration tightening which uses the D. C. motor. Also, the low frequency torsional vibration from 0 to 4 Hz is added to the tightening tool. The basic characteristics of the screw tightening method by means of the pneumatic control vibration is compared with the results of the ordinary screw tightening method (i.e. a constant velocity tightening method using the air motor).