In the mobile era, almost everyone “does not leave the phone”, and the mobile phone industry is updated and iterated frequently: In addition to the continuous upgrade of system and hardware configuration, the most important appearance and necessary camera functions of mobile phones have also become mobile phone vendors. A contested place.
In the process of innovation of appearance materials, glass materials are favored by mobile phone manufacturers due to their various advantages, such as variable shapes, good impact resistance, and controllable costs, including mobile phone front covers, rear covers, fingerprint recognition sheets, etc.; in the camera On the one hand, with the need for good photography, light sensitivity, depth focus and other photography technologies, three cameras and four cameras have begun to spread rapidly, and the demand for camera covers, filters, prisms and other accessories has increased rapidly.
Although glass materials have many advantages, their fragile characteristics bring many problems to the processing process, such as cracks and rough edges. In addition, the special-shaped cutting of the earpiece, front camera, fingerprint film and other positions also puts forward higher requirements on the processing technology.
Principles and defects of traditional glass cutting process
Traditional glass cutting processes include knife wheel cutting and CNC grinding and cutting. The glass cut by the knife wheel has large edges, rough edges, low yield, low material utilization, and complex post-processing is required after cutting. When performing special-shaped cutting, the speed and accuracy will be greatly reduced, and some are abnormal Because the corner of the full screen is too small, it is impossible to cut with the cutter wheel. CNC has higher precision than the cutter wheel, the accuracy is ≤30μm, and the chipping is smaller than the cutter wheel, about 40μm. The disadvantage is that the speed is slow.
The traditional laser cutting glass is an ablation mechanism. The focused high-energy density laser is used to melt or even vaporize the glass, and the high-pressure auxiliary gas blows away the residual slag. Because the glass is fragile, the high overlap rate spot will accumulate excessive heat on the glass, causing the glass to crack. Therefore, the laser cannot use the high overlap rate spot to perform a cut. Usually a galvanometer is used for high-speed scanning, and the glass is layered layer by layer. For layer removal, the general cutting speed is less than 1mm/s.
Principles and advantages of UV laser cutting glass
In recent years, UV lasers have achieved excellent performance in the application of glass cutting.
The principle is that the ultraviolet laser is focused by the focusing head to obtain a micron-level beam with high peak power density. When acting on glass materials, the light intensity at the center of the beam is lower than that at the edge, so that the refractive index at the center of the material changes more than that at the edge, and the beam center propagation speed Slower than the edge, the beam appears nonlinear optical Kerr effect to generate self-focusing, and continue to increase the power density until a certain energy threshold is reached. The material generates low-density plasma, reduces the refractive index of the material center, and achieves beam defocus. In the actual cutting of glass, optimizing the focusing system and focal length can achieve repetitive focusing/defocusing processes to form stable perforations.