Laser processing includes cutting, marking, drilling, or structural fabrication. Laser processing not only requires high speed and accuracy but also needs to maintain high output.
Therefore, the application of lasers in industrial manufacturing faces many challenges. The laser industry is continuously innovating to further optimize the processing technology and ensure high-quality processing.
Today, laser separation technology (including laser cutting, drilling, etc.) has greater flexibility and controllability compared to traditional mechanical processing, and most importantly, its processing quality is very high.
As electronic components become smaller and more sophisticated, the demand for machining accuracy is increasing. This is why ensuring machining quality and accuracy is particularly important in laser processing.
The precision machining characteristics of lasers make them superior to traditional machining methods such as sawing, milling, etc. Laser processing systems have high adaptability. With a well-designed program, high-quality processing can be achieved without repeated operations during the production process to meet final requirements.
Another characteristic of laser processing is its wide range of materials that can be processed, including metals (such as aluminum, stainless steel, iron, and titanium) and non-metals (such as plastics, composite materials, ceramics, etc.) (See Figure 1).
Demand for Electronic Components
Due to their excellent electrical, mechanical, and thermodynamic properties, high-performance ceramic materials have become indispensable materials in micro-precision manufacturing processes. They are widely used in various fields. For example, ceramics are used as carrier materials in the production of modern electronic components.
High-performance ceramic components can be used in the drive control of electric vehicles, automotive parts, and power engineering. Typically used is a ceramic thin copper plate, which is a special process that directly bonds the copper box to the surface of the alumina or aluminum nitride ceramic substrate at high temperatures. Alumina or nitride is used as the insulating layer while the copper compound forms the conductive layer.
As the production of electric cars increases, there is also an increasing demand for high-performance batteries. High-energy currents must be transmitted within a very short time and fast switching processes must be implemented. This requires high-quality electrical connections. The more complex the battery pack, the more complex the electronic components.
Laser Micromachining of Ceramic Materials
Traditional machining methods have shown that using ceramics as a processing material has its own disadvantages. This material is inherently brittle, and it is easy to cause cracks or damage due to changes in substrate stress when cutting or drilling with milling or grinding techniques.
Therefore, ceramics can only be processed at lower speeds, and the milling heads and cutter blades wear out quickly, resulting in higher operating costs. In addition, ceramic machining often requires repeated rework to achieve high processing quality.
Laser scribing technology can be successfully applied to the processing of ceramic materials and has unique advantages.
In fact, it is the application of laser processing ceramic materials that makes lasers a reliable processing tool in industrial applications. Even today, laser processing of ceramics is still considered an industrially cost-effective and widely applicable practice.
The commonly used laser scribing method sets new lines on the ceramic substrate at the designated position. Then, the ceramic material is broken along the new line position by machine or manually to achieve precise cutting of the ceramic material (see Figure 2).
For a long time, carbon dioxide (CO2) lasers have been mainly used for laser scribing. CO2 lasers have a wavelength between 9.4~10.6mm and can output up to 250W of continuous power.
Because the thermal effect of CO2 lasers is significant, some side effects will occur during the processing process, such as melting microbeads on the substrate, residual splashing, surface light changes, and micro-cracks. Even using a micro-lighter with a pulse width of several tens of nanoseconds, similar processing side effects will occur.
Ultra-short pulse laser processing belongs to a cold ablation process, which can reduce thermal stress and avoid burrs on the substrate when scribing. Ultra-short pulse lasers with pulse widths from 10ps to 200fs have particularly high peak power. When high-repetition-frequency pulses act on the workpiece, they can directly transform the material from a solid state into a plasma aggregate state.
In addition, ultra-short pulse lasers for industrial applications have multiple wavelengths to choose from, such as 1064nm infrared light, 532nm green light, and 355nm ultraviolet light.
Due to the high precision of the fracture edge produced by ultra-short pulse laser cutting of ceramics, micro-cracks will not be introduced into the substrate, so the material will not break.
By optimizing the process, ultra-short pulse lasers can achieve smooth cuts without burrs with a depth ranging from 20-70μm, ensuring high-quality and precise separation of ceramic circuit boards. With the improvement of the quality of cuts, the fracture strength of ceramic circuit boards also increases, thereby improving production efficiency.
In addition, the amount of residue generated from ultra-short pulse laser processing is much less than that generated from CO2 laser processing, greatly reducing or even eliminating subsequent cleaning steps (see Figure 3).
Ultra-short pulse lasers are also used in other processes, such as drilling, cutting, and manufacturing cavity structures.
In these processes, material ablation occurs layer by layer. Either the substrate is completely cut or burned to a predetermined depth. Laser sources with pulse widths in the picosecond and femtosecond range produce minimal thermal stress, ensuring high-quality surfaces during processing.
Laser cutting of ceramic substrates can achieve cutting of any geometric shape, and the internal and external contours of the geometric shape can be cut with the smallest radius. On the other hand, laser drilling can achieve very small hole diameters. Depending on the diameter of the hole, a reamer or impact drill can be used to obtain the desired geometric shape.
Removing material from the substrate can produce cavity structures in which microchips or resistors can be embedded. Laser processing can accurately control the ablation depth and the geometric shape of the cavity.
In addition to ceramic substrates and ceramic circuit boards, laser cutting, drilling, and scribing processes can also be applied to electronic circuit boards. The process of using lasers to cut an entire circuit board into multiple pieces is called laser depaneling.
Cutting circuit boards
Using lasers to separate an entire circuit board into small pieces, known as laser depaneling, is one of the most advanced processes in the market today.
Compared with traditional mechanical milling and cutting, laser depaneling technology uses lasers to ablate materials layer by layer, without contact with the material. Laser processing is non-contact, has low operating costs, and guarantees high processing quality, making it very advantageous for companies.
During laser cutting, the panels are seamlessly joined together, increasing space utilization by 30%. At the same time, laser processing does not produce any remaining materials, reducing costs (see Figure 4).
Before the emergence of ultra-short pulse laser technology, CO2 lasers have always dominated the cutting and scribing market in the electronics industry. The growing demand for finer and higher-quality electronic components has affected the entire printed circuit board market.
For example, LED lights, smoke detectors, or MP3 players require more precise and higher-quality circuit boards.
In order to meet the higher demands for circuit boards, various laser technologies have been developed and applied in recent years. The continuous development of the flexible electronics market has stimulated the potential of laser processing.
For example, the need to construct thin layers more quickly and conveniently on a flexible substrate provides ample space for innovation in laser manufacturing processes.