The research of high-quality grinding technology of large-size Al2O3 single-crystal slice
Al<inf>2</inf>O<inf>3</inf> single crystal has the following unique physical properties of high hardness, high toughness, obvious pleochroism and high refractive index Etc. The paper introduced the processing property of Al<inf>2</inf>O<inf>3</inf> single crystal, described its grinding technology. Then analyzed the characteristics and status of grinding technology of the large-sized Al<inf>2</inf>O<inf>3</inf> single crystal, combined with the relational research, discussed the technology of the grinding stage. Finally the paper summarized a set of precise grinding technology of large-sized Al<inf>2</inf>O<inf>3</inf> slice.
The assessment of plastic deformation in metal cutting
Abstract Because plastic deformation is a nuisance in the metal cutting process, its proper account is of high interest. A new meaning for the chip compression ratio is discussed showing that, on the contrary to shear strain, this parameter represents the true plastic deformation in metal cutting. The chip compression ratio can be used to calculate the total work done by the external force applied to the tool and then might be used for optimization of the cutting process. It is demonstrated that the cutting speed influences the energy spent on the deformation of the chip through temperature, dimensions of the deformation zone adjacent to the cutting edge and velocity of deformation. The separate impacts of these factors have been analyzed and the physical background behind the known experimental dependence of the chip compression ratio on the cutting speed is revealed. The influence of the cutting feed, tool cutting edge angle, cutting edge inclination angle and tool rake angle have also been analyzed.
Failure analysis for poor solderability of Au surface of PCB
Nonwetting is one of the common problems and is always rejected in electronic assemblies. ENIG pads of a PCBA exhibited nonwetting after lead-free reflow soldering. With the aid of stereomicroscope, SEM&EDS and XRF, a series of analysis was performed. And after visual inspection, surface and cross section analysis, thickness measurement and solderability test, it can be inferred that oxidation of plating surface was the main reason for nonwetting, and corrosion in Ni plating caused an adverse impact on solderalibity.