Papers by Keyword: Ductile Mode Grinding

Abstract: The machining technology of ultrasonic assisted ductile mode grinding for the silicon carbide (SiC) wafer carrier. The machining tool is designed and analyzed by ANASYS 14.0 and the machining technology is studied for the 6-inch SiC wafer carrier. The ultrasonic tool holder with the resonance frequency 26 kHz is designed and fabricated. The advantageous machining parameters are proposed that spindle rotation rate is 3000 rpm, feed speed is 200 mm/min, and ultrasonic output power is 250 W. The measurement results show that the average roughness (Ra) of the SiC is 0.18 μm, the MRR is over 2.4 mm³/min, the tool tips are only minor abrasion, and the cutting temperature are reduced. Obvious, the machining technology has the advantage of high surface quality, high machining efficiency and long tool life.

Abstract: Under optimum grinding conditions, a constant grinding force is exerted on a workpiece during ductile-mode grinding of BK7 glass. Based on the results, the cutting force, specific grinding energy, and depth of cut for a single grain were calculated. It was found that a single grain was easily removed from the material. However, grinding is impossible because surface burning occurs on the workpiece. In order to avoid burning, a single-crystal silicon wafer (1,0,0) surface was ground with thrust force directional vibration-assisted grinding. The normal grinding force with vibration was comparatively low, but was quite stable. The removal rate was approximately three times greater than that without vibration. The results indicate that the successive abrasive grains of the grinding wheel remove the material intermittently.

Abstract: This paper proposed a new approach to control the micro-quality of sapphire substrate, in order to grow GaN on substrate. The main factors that influence macro-quality are the method of slicing, grinding and polishing. Thread speed of slicing is less than 0.5m/s. Ductile mode grinding of substrate is achieved by #3000 diamond wheel and feed of 1μm/r. The suitable polishing conditions are that the SiO2 grain size is less than 10nm, the concentration SiO2 is 3％, pH value of polishing liquid is 10.5 and polishing stress is 190Pa. The undamaged substrates have been obtained steadily. The surface roughness RMS is less than 0.4 nm.

Abstract: The effect of cutting-edge truncation on the grinding mechanism of quartz glass as a hard and brittle material was investigated. From computer-aided grinding simulations and experiments on surface plunge grinding it was found that cutting-edge truncation decreases the ground-surface roughness and the maximum grain depth of cut; however, the maximum grain depth of cut approaches a constant value depending on the grinding wheel specifications. The alternative means of making the maximum grain depth of cut much smaller than this constant value is to increase the speed ratio. Cutting-edge truncation should be terminated at the optimum truncation depth to avoid the high grinding forces resulting from the flattening of cutting edges.

Abstract: A new non-destructive method was developed to identify the grinding mode of silicon wafers, which is based on the information of subsurface cracks extracted from the surface topography of the ground silicon wafers measured with a 3D surface profiler. We examined extensive measurement data of the surface topography of silicon wafers processed by single grain grinding or real grinding operation, and our results show that the information about median cracks could be captured if the lateral sampling interval of the 3D surface profiler is small enough, even if the grain depth of cut is below 20nm. If the maximum valley of the measured surface topography is approximately equal to the grain depth of cut, surface formation will be under ductile mode, whereas, if the maximum valley is several times larger than the grain depth of cut, surface formation will be under brittle mode. According to this criterion, silicon wafers ground by ductile mode or brittle mode could be identified rapidly and conveniently. Experimental validation shows that this method is accurate.

Abstract: For the purpose of investigating the effect of cutting edge truncation on ground surface morphology, several kinds of hard and brittle materials used for optical devices, borosilicate glass, glass quartz, crystal quartz and sapphire, are plunge ground with a SD600 metal-bonded grinding wheel, the cutting edges of which are truncated so as to be aligned with the height level of the grinding wheel working surface, after electrocontact discharge truing and dressing. It is found that an improvement of roughness can be obtained for every material investigated, although the degree of roughness improvement depends on the kind of material. Ductile-mode grinding is most likely to be realized in the case of crystal quartz.