High-quality drilling of brittle materials is considered to be difficult to realize, as various requirements depending on shape, size, and taper level of holes need to be met. Appropriate laser processing conditions and parameter for each requirement have to be provided.
For circular hole drilling, there are requirements such as minimized taper and reverse taper shape. Although the occurrence of a certain amount of taper is inevitable with conventional methods, we fulfill the requirements of customers by controlling it.
In principle, the taper can be controlled by changing the laser irradiation angle. However, simultaneous control of laser oscillation, angular change (prism), and drilling position (outer periphery) is required.
MDI has developed a high-speed controlling unit that can control the taper while drilling.
There is a growing need for hole size miniaturization. Demands for fine drilling in thinner panels are increasing.
The laser wavelength is selected in accordance with the characteristics of the brittle material; in addition, proper setting of the conditions of factors other than laser wavelength is also required for high-quality fine drilling. The process conditions are set so as to minimize cracks in the interior of the hole, to minimize taper, and to reduce chipping on the processed surface and back face.
Since the hole diameter is determined by the condensing size of the laser, its size has to be converged as needed; at the same time, its shape has to be as close to circular as possible. Our in-house optical designing for laser condensing can provide an optical system that enables high-quality drilling.
Laser drilling can be adopted for various materials such as glass, ceramics, resin, and metals. However, an optimal laser wavelength should be selected in accordance with the optical characteristics of the workpiece.
Although MDI mainly deals with drilling of brittle materials, we can also handle resins and metals.
In the case of drilling a hole that is larger than the laser condensing size, the periphery of the hole is usually processed by degrees. However, for brittle materials, crack propagation can be utilized with processing methods such as scribe and break.
A primary crack is generated by laser scanning, and then the unnecessary part is removed by breaking. It is possible to perform high-speed processing and obtain a refined cross-section surface, which characterizes the features of scribe and break.