Scribe and break (S & B) is a separation method that utilizes the physical properties of the workpiece material. It is a dry cutting method without the use of water, that can increase the processing speed, and that is significantly affected by the physical properties (esp. crystalline orientation) of the material.
Scribing method (mechanical and laser)
The scribing method proposed by MDI can be adopted in both mechanical scribing with diamond tools and laser scribing by laser irradiation.
For mechanical scribing, we have developed tools with various shapes in accordance with the workpiece materials including SOLID-D® with high-accuracy stationary blade for ultra-thin glasses, Penett® (a scribing wheel) with a groove on its ridgeline that can furnish a highly permeable scribe line (such as a deep vertical crack), APIO® that ensures stable inner cutting, and Ryu that can reduce the cullet. Furthermore, the most suitable scribing method can be achieved by combining the material, angle, number of grooves (number of divisions), and groove depth, among others.
Laser scribing is a scribing method that uses laser abrasion. For laser scribing, the best combination of laser wavelength, output, and repetition frequency, among others, is selected.
Depending on the material of the workpiece and the quality level required for cutting, either mechanical or laser method is selected and accordingly, its optimal process conditions are defined. For some workpiece materials, a break-less method can also be applied depending on the required quality level.
Breaking is a cutting (separation) process that propagates the vertical crack formed by scribing. The break method must be chosen according to the scribe state. For high-quality cutting, the chosen scribe and break method must be in the best-suited conditions for the workpiece material.
Three-point bending (while supporting the panel with a receiving blade and pressing it down with a break blade) and tilting (by tilting the panel) are the common breaking methods. Others include VM SEPARATION® (by pressing the panel that is supported by a special elastic body with a break blade), processing by utilization of ultrasonic vibration, and a robotic method that reproduces manual cutting.
The crack can also be propagated by laser irradiation. Here, we deal with the laser irradiation method using the wavelength suitable for laser scribing. We provide high-quality cutting by various methods.
For the complete separation, expand processing may be added after breaking.
Basic features of scribe and break method
The scribe and break method has been in use for a long time to cut hard and breakable materials (brittle materials) such as glass. In the scribing process, a crack is formed in the plate thickness direction by providing a cutting line (scribe line) on the plate surface. In the breaking process that follows, the plate is separated by further propagating the crack.
Based on the manufacturing knowledge of glass cutters used by artisans, MDI develops technologies to provide high-quality cutting for various brittle materials.
The basic features of this method include the following:
- The method involves dry cutting without using any grinding fluids, such as water.
- The required processing width is extremely small with a scribe line of a few micrometers.
- High speed cutting is possible as it is not a removal machining process, such as dicing.
- Chipping hardly occurs at the cut edge.
Another feature of this method is the high bending strength of panels owing to the high-quality cutting.
The panels of electronic components and devices are getting thinner and products are getting smaller with technological progress.
The scribe and break method is suitable for cutting small tips of the panel. As the vibration during processing is low, there are fewer instances of chips flying off. In addition, the width required for processing (street width) can be reduced and the number of the pieces used as products can be increased.
The scribe and break method enables both curve cutting and linear processing. As an application, it can be adapted to curved surface processing (3D processing). In the case of mechanical scribing using a scribing wheel, the capability of high quality curve cutting is limited to a 3 mm radius, whereas laser scribing can achieve curve cutting of a smaller radius.
When cutting complex shapes, the breaking (separation) method tends to cause problems. When the crack generated by scribing is propagated, it may deviate from the scribe line. To overcome this limitation, a scribe line (cutoff) has to be cut into an unnecessary part of the workpiece to improve the breaking quality.
Both scribing and breaking qualities determine the cutting quality.