Study on precision dicing process of SiC wafer with diamond dicing blades

An innovative method for high-speed micro-dicing of SiC has been proposed using two types of diamond dicing blades,a resin-bonded dicing blade and a metal-bonded dicing blade.The experimental research investigated the radial wear of the dicing blade,the maximum spindle current,the surface morphology of the SiC die,the number of chips longer than 10μm,and the chipped area,which depend on the dicing process parameters such as spindle speed,feed speed,and cutting depth.The chipping fractures in the SiC had obvious brittle fracture characteristics.The performance of the metal-bonded dicing blade was inferior to that of the resin-bonded dicing blade.The cutting depth has the greatest influence on the radial wear of the dicing blade,the maximum spindle current,and the damage to the SiC wafer.The next most important parameter is the feed speed.The parameter with the least influence is the spindle speed.The main factor affecting the dicing quality is blade vibration caused by spindle vibration.The optimal SiC dicing was for a resin-bonded dicing blade with a spindle speed of 20000 rpm,a feed speed of 4 mm/s,and a cutting depth of 0.1 mm.To improve dicing quality and tool performance,spindle vibrations should be reduced.This approach may enable high-speed dicing of SiC wafers with less dicing damage.

Prediction of the Interface Temperature Rise in Tribochemical Polishing of CVD Diamond

Tribochemcial polishing is one of the most efficient methods for polishing CVD （Chemical Vapor Deposition） diamond film due to the use of catalytic metal. However the difficulty to control the interface temperature during polishing process often results in low material removal because of the unstable contact process. So this research investigates the contact process in the tribo- chemical polishing of CVD diamond film and proposes a dynamic contact model for predicting the actual contact area, the actual contact pressure, and the interface tem- perature in the polishing process. This model has been verified by characterizing surface metrology of the CVD diamond with Talysurf CLI2000 3D Surface Topography and measuring the polishing temperature. The theoretical and experimental results shows that the height distribution of asperities on diamond film surface in the polishing process is well evaluated by combining the height distribution of original and polished asperities. The modeled surface asperity height distribution of diamond film agrees with the actual surface metrology in polishing process. The actual contact pressure is very large due to the small actual contact area. The predicted interface temperature can reach the catalytic reaction temperature between diamond and polishing plate when the lowest rotation speed and load are 10 000 r/min and 50 N, respectively, and diamond material is significantly removed. The model may provide effective process theory for tribochemcial polishing.

Prediction of cutting force in ultra-precision machining of nonferrous metals based on strain energy

The effects of the nonuniform cutting force and elastic recovery of processed materials in ultra-precision machining are too complex to be treated using traditional cutting theories,and it is necessary to take account of factors such as size effects,the undeformed cutting thickness,the tool blunt radius,and the tool rake angle.Therefore,this paper proposes a new theoretical calculation model for accurately predicting the cutting force in ultra-precision machining,taking account of such factors.The model is first used to analyze the material deformation of the workpiece and the cutting force distribution along the cutting edge of a diamond tool.The size of the strain zone in different cutting deformation zones is then determined by using the distribution of strain work per unit volume and considering the characteristics of the stress distribution in these different deformation zones.Finally,the cutting force during ultra-precision machining is predicted precisely by calculating the material strain energy in different zones.A finite element analysis and experimental data on ultra-precision cutting of copper and aluminum are used to verify the predictions of the theoretical model.The results show that the error in the cutting force between the calculation results and predictions of the model is less than 14%.The effects of the rake face stress distribution of the diamond tool,the close contact zone,and material elastic recovery can be fully taken into account by the theoretical model.Thus,the proposed theoretical calculation method can effectively predict the cutting force in ultra-precision machining.