The effect of slurries on lapping performance of fixed abrasive pad for Si3N4 ceramics

In this paper, a series of experiments were carried out to explore the effect of slurry pH on materials removal rate (MRR) and surface quality in lapping of Si3N4 ceramics wafers with fixed abrasive pad (FAP) using different slurries with different pH. Then, the scanning electron microscope was employed to detect the microtopography and abrade smooth of FAP for exploring the effect of slurries pH on self-conditioning of pad. Experimental results demonstrated that the roughness of wafers increase with the increasing of slurry pH value. The surface of wafers is the best when the pH = 1 and the worst When the pH = 13. The MRR decreases firstly and then decreases with the increasing of the pH. The MRR reaches the lowest when slurry pH = 7, and reaches the highest when slurry pH = 13. These results further suggest that the soften layer of SiO2 could be formed due to the reactions between water and materials on wafer surface, which facilitates increasing material remove rate and improving the surface quality. The hydrogen ion and triethanolamine in slurry could react with the copper in fixed abrasive pad, which also could enhance the materials remove rate and affect the surface quality.

The Fuzzy Comprehensive Evaluation of the Self-Conditioning of Hydrophilic Fixed-Abrasive Pad

The self-conditioning of hydrophilic fixed abrasive lapping based on the principle of two-body (pad-wafer) abrasion has great importance on the MRR (material removal rate) of wafer. The physical and mechanical properties of pad were taken as set of available alternatives. Fuzzy comprehensive evaluation principle was applied to establish a model for the self-conditioning of FAP. The swelling ratio, the slurry abrasive ratio and pendulum hardness were selected to be the set of alternatives for self-conditioning evaluations in this paper .The five types of matrix formations of fixed-abrasive pad were prepared, and the matrix were ranked in order of comprehensive evaluation index. The results show that the fuzzy evaluation is rational. The tests of MRR verified the self-conditioning of FAP. The machining of pad can be evaluated in advance of lapping processes. Moreover, the self-conditioning evaluation will be important reference for determination of FAP during choosing the matrix formations.

Effect of Abrasive Particle Size on Lapping of Sapphire Wafer by Fixed Abrasive Pad

The choice of abrasive particle size is crucial to improve the lapping efficiency and surface quality in lapping of sapphire wafer by fixed abrasive (FA) pad. A model for the penetration depth of a single abrasive is developed with fixed abrasive pad. A serious of lapping tests were carried out using FA pads embedded with different size of diamond particles to verify the validity of the developed model. Results show that the penetration depth of abrasive is related not only to the particle size, but to the hardness ratio of the work-piece to the pad as well. The material removal rate of sapphire is proportional to the square of abrasive particle size, while the average surface roughness is proportional to the abrasive particle size.

The Optimization of Process Parameters by Fixed Abrasive Pad for Lapping Magnesium Aluminate Spinel

The process parameters affect the lapping efficiency and the surface quality of work pieces. The fixed abrasive pad of w3-5 diamond abrasive was used for lapping magnesium aluminate spinel wafers in orthogonal experiment. The affection of lapping pressure, plate speed and slurry type on material removal rate (MRR) and surface roughness Ra were investigated. Finally, the process parameters were optimized. The results showed that lapping efficiencies were higher and the surface quality was better on the conditions of Zhongjing slurry, lapping pressure 10.37Kpa and plate speed 100rpm.

Process Optimization of Lapping Sapphire Substrate with Fixed Diamond Abrasive Pad

The production cost of the sapphire substrate was restricted by the efficiency of processing and the surface quality. A proposed level orthogonal experiment was conducted to reveal the effect of workbench speed, lapping pressure, the Concentration of triethanolamine and abrasive pad types on the material removal rate and surface roughness and morphology of sapphire substrate when lapped with a diamond fixed-abrasive pad. The results showed that the average material removal rate of sapphire is about 24μm/min, and the surface roughness Ra achieves 0.36μm when the 200/230 mesh diamond fixed-abrasive pad was used. The material removal rate and the surface roughness as the optimization goal, the optimal lapping parameters were as follows: the lapping pad with raised, lapping pressure 0.075MPa, workbench speed 120rpm and the Concentration of triethanolamine 1%. Under these optimal machining parameters, the material removal rate reached 42μm /min and the surface roughness Ra reached 0.37μm.