Lapping Method Research Articles

Comparative Study on Surfaces of Single-Crystalline Substrates. From Dielectric Substance to Semiconductor and Metal. Machining and Processing Technologies and Quality of Silicon Wafer Surfaces.

The current state of the technologies of machining and processing of silicon wafers is described. The 8 inches diameter wafer process is just shifting to the process for 12 inches wafers. Actually, in wafer plants it is necessary to reconsider the wafer making methods which have been used so far. For instance, the method of wafer slicing is changing to multi-wire lapping from grinding with inner type thin diamond wheels, since the preparation of thinner and wider wheel metal plates becomes impossible for prospective large diameter silicon wafers. In wafer surface finishing, the present lapping and polishing methods will be replaced with a kind of grinding method using abrasive wheels as in glass lens manufacturing. However it might not become realistic soon, and, for the time being, the current conditions of lapping and chem-mechanical polishing will be utilized. The stock removing mechanism and the damaged layer in lapping or polishing are given an account.

Spin Angle Controlled Lapping of Steel Ball with Grain Size Degradation.

Spin angle controlled ball lapping method developed recently, is to have an excellent performance to lap the ball, in which V-groove lapping plates are separated into two parts and three plates are able to rotate independently. Present paper focuses on an effect of degradation of grain size on finishing characteristics of a steel ball. It is found that degradation of grain size has yielded greater stock removal and has brought smaller sphericity of the ball. Experiments show that the stock removal is dependent upon spin angle θ which is closely related to slipping distance of the ball. Measurements of the sphericity of lapped ball indicate that geometry of lapping plate has small effect with respect to improvement of it, but causes larger stock removal rate and very smooth surface.

A comparative study: surface characteristics of CVD-SiC ground with cast iron bond diamond wheel

Efficient precision machining of CVD-SiC (chemical vapor deposited silicon carbide) reflection mirrors in extremely low surface roughness and high form accuracy is greatly demanded by advanced industrial fields. The existing lapping methods have a great difficulty in satisfying these demands. Some researchers proposed ductile mode grinding technology, but it inevitably required a very expensive grinding machine, and its grinding process with such fine abrasive wheel was usually unstable. Dr. H. Ohmori put forward a new idea of application of ELID-grinding to ultraprecision grinding of CVD-SiC mirrors. The method had a potential to solve the above problem. In this paper, the precision grinding of CVD-SiC was performed by two kinds of methods. One is the ELID grinding; the other is the ordinary grinding with the saw-like-abrasive-stone-dressed cast iron bond diamond wheel. A comparative study of surface characteristics of ground CVD-SiC has been carried out. The following conclusions have been drawn below. (1) The surface characteristics of wheels dressed by these two methods are different. (2) The surface roughness ground by ELID grinding was only slightly better than the one produced by the ordinary grinding method. (3) The microscopic characteristics of CVD-SiC ground by these two methods differed largely. (4) ELID grinding is greatly recommendable in precision grinding of hard-brittle materials on ordinary machines of low rigidity.

鋼球の回転スピン制御研磨 θ角強制回転の効果

Steel balls set into the bearings are finished with conventional ball lapping machine which uses a couple of flat and V-groove lapping plate. Conventional lapping method, however, needs so long machining time. Present study focuses on efficient lapping method using spin control lapping macine which V-groove lapping plate is separated into two parts and three plates are able to rotate independently. Spin angle θ of steel ball is rotated by force during lapping to promote finishing efficiency. Experiments show that spin angle rotation have great effect on finishing characteristics such as a stock removal, decrease of deviated diameter and surface roughness of ball. Lapping carried out at fixed angle of θ indicates that finishing modes change drastically at 45 degree, which is responsible for efficiency of machining of ball.

Terahertz-wave antireflection coating on Ge and GaAs with fused quartz

In the terahertz-wave region, fabrication of an antireflection (AR) coating is difficult because it must be as thick as several tens of micrometers, which is far thicker than that used in the optical region. We discuss a lapping method for fabricating an AR layer with a desired thickness for terahertz-wave optical devices. To demonstrate this method, we glued a thin fused-quartz plate to a surface of an undoped Ge or GaAs wafer and polished it to a thickness of one-quarter wavelength. This reduced the reflectivity of the AR surface to 1/720 of the reflection of an uncoated surface, as expected from optical theory.

粉体塗布レーザクラッディング法によるＮｉＣｒＡｌＹ皮膜の形成

Cladding techniques have been used in many areas. Recently laser cladding techniques have been developed and applied to the automobile parts fabrication and to the repair of pipes inside installed in the Nuclear Power Plants.As for the laser cladding, there are the following three methods of supplying the cladding material ; (1) Wire feed, (2) Powder feed and (3) Preplaced powder. The third method was selected for having higher flexibility in selecting the chemical composition of cladding material and cladding position. The investigation was carried out to produce a NiCrAlY cladding layer.Cladding parameters such as laser power, traveling speed, diameter of powder and cladding atmosphere were changed systematically to select the best condition for a single bead with a low power (1200 W) CO2 laser. A SUS304 plate with a 12 mm thickness was used as a substrate, and mixed powders were bedded with a 1 mm thickness with an organic binder. The dilution ratio and the cross sectional area of the cladded layer were measured and the best cladding conditions were selected on the basis of these data.To get a large cladded area a weaving method and a half lapping method were tried based on the best cladding conditions for the single bead.The results obtained are as follows ;1. The NiCrAIY laser cladded layer with good characteristic can be obtained by mixing commercial powders of Ni-Cr, Al and Y-Ni and a commercial organic binder.2. With the weaving method, a broad area can be cladded with a low power (1200w) CO2 laser.3. The uniform distribution of chemical composition throughout the cladded layer thickness can be obtained.4. An atmospheric chamber replaced inside with Ar can make the layer's contour better.5. Fine powder was preferred from the points of view of the dilution ratio and the cross sectional area of cladded layer.6. Carbon content of the cladded layer was not so high although the organic binder was used as the binder, and this shows the high possibility of this method to prepare corrosion resistant cladded layer.

Fabrication, characteristics, and performance of diamond mirrors for vacuum ultraviolet excimer lasers

We have deposited crystalline diamond films on sintered Si 3 N 4 substrates with a conventional hot-filament method and further finished the surfaces with a diamond lapping method. The diamond mirrors fabricated are proposed and demonstrated as among the most promising mirrors for vacuum ultraviolet rare-gas excimer lasers. We have obtained pulses with 15-mJ energy, 2.7-MW peak power, and 6-ns duration at 126 nm from an argon excimer laser, and with 70 mJ, 5.5 MW, and 5 ns at 146 nm from a krypton excimer laser without any surface damage. The latter values are the highest so far obtained

Proposal of New Lapping Method for Ceramic Balls

This paper treats the relation among lapping pressure, wear-distance-ratio, mesh number of abrasive sheet and sphericity of bails in the lapping circumstances of ceramic balls, and the new lapping method for ceramic balls are presented. Obtained results are as follows: (1) For balls formed by CIP the optimum lapping conditions such as lapping pressure, the mesh number of abrasive sheet and others are found. (2) New lapping method for sintered ball based on “the three-point measuring method of roundness measuring method” is proposed, and the sphericity of balls can be considerably improved by this method. (3) The optimum share ratio of normal loads in combined tools is found for the rapid improvement of the sphericity of balls.

High precision lapping for polygonal holes

Lapping has been used as a finishing method to improve the roundness of shafts and holes. This paper introduces two methods for the finishing of polygonal holes whose shapes are ellipsoidal, three-lobed, four-lobed, and so on. One method is the “regular polygonal lap” in which the amplitude of the desired Fourier component of the out-of-roundness is kept constant and the other components are decreased. The other is the “tripod lap,” which can increase the amplitude of any Fourier component using special types of lapping tools produced by applying the “tripod roundness measuring method.” Based on a theoretical analysis, this study shows that any component of the out-of-roundness can be increased by using the new tripod lap method.

セラミックスボールの新しいラッピング方法の提案

This paper treats the relation among lapping pressure, wear-distance-ratio, mesh number of abrasive sheet and sphericity of balls in the lapping circumstances of ceramic balls, and the new lapping method for ceramic balls are presented. Obtained results are as follows : 1) For green balls formed by CIP the optimum lapping conditions such as lapping pressure, the mesh number of abrasive sheet and others are found. 2) New lapping method for sintered balls using combined lapping tools is proposed, and the sphericity of balls can be considerably improved by this method. 3) The optimum share ratio of normal loads in combined tools is found for the rapid improvement of the sphericity of balls.

非真円断面穴のラップ仕上

Lapping has been used as a finishing method to improve roundness accuracy of cylindrical shafts and holes. However, little has been published on the theoretical analysis of the finishing mechanism for high precision polygonal cross sections. This paper offers two methods for finishing polygonal holes, whose shapes are ellipsoidal. triangular, four-protrusion and so on. By one method, the amplitude of the interest Fourier component of out-of-roundness keeps constant. while the other components are decreased. using “regular polygonal lap”. By the other method, the amplitude can be increased for any Fourier component using special types of lapping tools produced by applying the “Tripod” roundness measuring method, using one of the tripod lapping tools. the magnitude for the four-protrusion component was increased from 7.64 μm to 8.27μm. while the other components were decreased. Out-of-roundness improved from about 40 μm to about 30 μm. This study shows that any component of the out-of-roundness can be increased, based on a theoretical analysis, as a result many improvements on the new lapping methods. called “tripod lap”.

合成アーチ巻立て工法によるコンクリートアーチ橋の施工

本稿は, 合成アーチ巻立て工法 (CLCA工法) という新しい施工法で建設された, 新潟県佐渡島の城址橋 (スパン82m) の工事記録である。本工法は合成柱の構造をコンクリートアーチ橋のアーチリブの構築方法に適用したもので, 従来のセントル工法やメラン工法に比較して, 軸方向力に優れた性質を生かし, 鋼材量を大幅に減少させることができる。本工法の採用により, 経済性および施工性に優れたアーチ橋を建設することができた。ここでは, アーチリブの架設に焦点をあてて報告している。

磁性流体利用の作用砥粒数制御研磨

Need for the controllable finishing of materials such as semiconductors and ceramics, has remarkably increased in the fields of electronics and precision machinary. A new lapping method has been developed by utilizing functional magnetic fluid which has the ability to move in the magnetic field. The magnetic fluid is a suspension of fine magnetite Fe3O4(smaller than 150A) in liquid. This lapping method is based on the floatation of nonmagnetic grains suspended into the magnetic fluid in the magnetic field. Lapping experiments were conducted on soda lime glass. It was found from the experiments that the new lapping method is able to control the stock removal rate through varying the current to the electromagnet. The present method may be usefully employed in finishing such parts as aspherical lenses.

ダイヤモンド工具の研磨に関する研究 Ｉ 鋳鉄円板による基礎的研磨実験

In order to obtain the single crystal diamond tools which have clear crystallographical orientation of the tool faces, the lapping method with identifying technique by the X-ray diffraction is studied. The lapping temperature is measured as well as the lapping forces and the total lapping depth to consider a lapping mechanism of the diamond tool. The addition of oscillation to the lapping operation lowers all the tangential lapping force, the lapping temperature and the total lapping depth, which have more effect on so called card to lap direction on {110} plane than on easy to lap direction on {110} plane. It is also found that the lapping temperature increases with the normal force to the lap, but the lapping force ratio (tangential force/normal force) decreases, and that the lapping surface roughness of diamond by the oscillatory lapping is superior to one by the non-oscillatory lapping.

Study on precision cylindrical lapping. 3rd report On the rounding condition in internal lapping.

This paper discusses analytically on the machining condition for modification of work roundness error by a simple conventional cylindrical lapping method, in which the internal surface of the cylindrical workpiece is machined with the lapping tool supported with two free rotating rollers. The analysis points out that there is a suitable machining condition for modification of roundness error by which the effect of the random and periodic deflections of the supporting roller surface and its rotating axis on the word roundness can be decreased.

Study on Precision Cylindrical Lapping : on the Condition for Modification of Roundness Error

This paper discusses analytically on the condition for modification of the work roundness error and improvement to the value of about 0.1 μm by a simple conventional cylindrical lapping method, considering that it has been very difficult to machine a cylindrical workpiece at its top position supported with two free rotating rollers. The analysis points out that there is a suitable machining condition for modification of roundness error by which the effect of the random and periodic deflections of the supporting roller surface and its rotating axis on the work roundness can be decreased. The paper describes the analytical result and a few experiments carried out for confirmation yielding an out-of-roundness value of 0.2 μm.

Applications of Diamond Turning to Infrared Optical Systems

Diamond turning is immediately applicable to the fabrication of infrared optical components because presently available machines can meet the reduced absolute accuracies required at 10 micrometers. An initial survey of infrared sensor programs at the Honeywell Radiation Center has been conducted to predict the near term and future demand for diamond-turned optical components. Not only does the fabrication process promise significant cost savings as compared to conventional lapping and polishing methods, but, as in the case of aspheric lenses, wider applications are also sought to reduce weight and space requirements. In addition, broader usage of diamond-turned aspherics reduces total parts count and assembly and alignment time, provided proper tools and test equipment are employed. The potential cost savings of diamond-turned vs conventionally fabricated optics are summarized for contracts at the Radiation Center. The savings were calculated by subtracting the difference in fabrication costs and multiplying by the number of items expected to be produced into the mid-1980s. Technical fallout potential of the diamond-turning process is also noted in the apparent ability of a coated sample to pass a 24-hour salt fog test.

三面ラッピングにおける形状生成過程

Principal characteristics are investigated which govern the changing process of the surface forms of upper and lower workpieces in the lapping. It is shown that the process simulated on a digital computer coincides qualitatively to a good extent with the one obtained experimentally and also shown that the factors governing the process are divided into the following two characteristics:(1) The inherent property in the lapping method.(2) The property due to interaction between the surface forms of upper and lower workpieces.Moreover, based on the above factors, it is proposed that the process can be satisfactorily described by a linear vector differential equation.

Diffusion of some impurities in zinc sulphide single crystals

Using a lapping and surface-counting method, the diffusion of Mn and Au are studied and compared with the self-diffusion of S in ZnSc. In all three cases diffusion constants exhibit a distribution over the samples used; however, by considering a large number of sample batches, average activation energies of 3.15, 2.46 and 1.16 eV have been obtained, respectively, for sulphur, manganese and gold.

超音波振動を利用した鋼球のラッピング(第1報)

In order to improve the lapping efficiency of steel balls, has been developed a new lapping method. Instead of the upper lap plate being floating supported, as in the conventional lapping, it is used a supersonically vibrating plate.In this paper, the results obtained from the fundamental experiments are described.The major findings are as follow :(1) Supersonic lapping under the optimum lapping conditions is superior to ability of conventional lapping caused by vibration.(2) The lapped quantity has been affected not only by the impact energy but the lapping pressure, and in the case of lower amplitude was proportional to the lapping pressure, and vice versa to higher amplitude in the extent of this experimental conditions. (frequency 22 kc, amplitude 10-14.5 μ, lapping pressure 40-120 g per piece, ball dia. 2 mm)(3) The increasing rate of sphericity per unit lapped quantity is generally related in inverse proportion to the impact energy, and has been affected by the impact energy rather than the lapping pressure.(4) The physical and mechanical properties of the finished surface varied considerably according to the magnitude of impact energy and lapping pressure, and become better in the case with smaller the magnitude.