Experimental Investigations On Optimizing Manufacturing Parameters For Electro-Spark Deposition Diamond Wire Saw

The third generation of superhard semiconductor materials, represented by single-crystal SiC, is used widely in microelectronics due to their excellent physical and mechanical properties. However, their high hardness and brittleness become the bottleneck of their development. Diamond wire saw (DWS) has become the mainstream tool for sawing hard and brittle crystal materials. However, the diamond abrasive is consolidated on the core wire through resin or electroplated nickel, and the holding strength is not high. When sawing superhard crystal materials, the efficiency is low. In order to improve the sawing efficiency of superhard crystal materials, it is of great significance to improve the wear resistance of wire saw and the holding strength of abrasive particles. Electro-spark deposition (ESD) can deposit electrode materials on the substrate with low heat input to achieve metallurgical bonding between metal materials. It can effectively improve the gripping strength of the abrasive grains. And the sawing ability of the wire saw to make the consolidated DWS by the ESD process. In this paper, the ESD equipment has been designed according to the characteristics of the ESDDWS process. The discharge gap size and electrode consumption are monitored in real-time by a single-chip microcomputer (SCM). Orthogonal experiments were carried out for the two motion modes. The effects of process parameters, such as (A) Grain size, (B) Abrasive content, (C) Pulse duration time, (D) Compacting pressure, (E) Current, (F) Electrode diameter, (G) Pulse interval time, (H) Reciprocating times, (I) Wire feed speed, on the quality of ESDDWS were analyzed. Through the extremum difference analysis, the optimal parameter combinations of ESDDWS were obtained. The results of the validation experiment are better than the original experimental results.

Prediction And Verification of Wafer Surface Morphology in Ultrasonic Vibration Assisted Wire Saw (UAWS) Slicing Single Crystal Silicon Based On Mixed Material Removal Mode

Monocrystalline silicon is one of the most important semiconductor materials, widely used in chip manufacturing, solar panels. Slicing is the first step in making chips and the surface quality of silicon wafers directly affects the quality of later processing and accounts for a large proportion in the chip manufacturing cost. Ultrasonic vibration assisted wire saw (UAWS) is an effective sawing process for cutting hard and brittle materials such as monocrystalline Si, which can significantly improve the surface quality of silicon wafers. In order to further study the formation mechanism of the surface morphology of single crystal silicon sliced by UAWS, a new model for prediction of wafer surface morphology in UAWS slicing single crystal silicon based on mixed material removal mode is presented and verified in this paper. Firstly, the surface model of diamond wire saw tool is established by equal probability method. Then according to the equation of transverse vibration dynamics about the wire saw with ultrasonic excitation, the trajectory equation of arbitrary abrasive particles on the surface of wire saw is derived and analyzed. Thirdly, a new model for prediction of the wafer surface morphology based on mixed material removal mode is presented, which can be used to predict the wafer surface morphology of single crystal silicon sliced by UAWS. Finally, the prediction model is verified by UAWS slicing experiment, and the effects of slicing parameters such as wire saw speed, feed speed and workpiece rotate speed on the surface quality of silicon wafer were studied. It shows that the predicted wafer surface morphology and the experimental wafer surface morphology are similar in some characteristics, and the average error between the experimental and the theoretical values of the wafer surface roughness is 11.9%, which verifies the validity of the prediction model.

Fluid Flow Analysis of Agitation Pipe in the Electroplated Diamond Wire Saw

Agitation pipe is the important part of the electroplated diamond wire saw in the suspension sanding process. The structure type and the sandblasting configuration in agitation pipe play a role on the flow uniformity. Fluid flow in the different structure forms of agitating pipe was studied and the influence of sandblasting angle and the diameter was also contrasted. Results found that the central water type of agitation pipe has the better performance, generating the flow field distribution in the middle part with high velocity and small velocity on both sides. The order of sandblasting in performance was 30°, 45° and 60°. The better flow uniformity occurred in the configuration of sandblasting with the diameter 7.5 mm, 7 mm and 7.5 mm.

Influence of the Agitation Pipe on the Flow Field of Electroplating Tank in the Electroplated Diamond Wire Saw

In order to solve the problem of diamonds sedimentation in electroplating tank and uneven distribution of diamonds in coatings, the fluid flow in the electroplating tank formed by three structure kinds of agitation pipe was compared and analysed. Results showed that the middle inlet type agitation pipe can significantly improve the fluid uniformity in the electroplating tank, and setting sand blasting ports at both ends of the agitation pipe can avoid the formation of fluid “dead zone”. Along the direction of the agitation pipe, the middle inlet type agitation pipe improves the overall flow of the fluid. In the position of the wire saw passing through, the difference of the speed in the electroplating tank of the middle inlet type is 47.17% and 15.25%, which is significantly lower than that of the water inlet structure of one end by 134.48%. As a result, it can significantly improve the plating effect of the wire saw.