Ultraviolet laser processing applications in the PCB industry

时间2018/10/31 21:17:24

For laser cutting or drilling in the circuit board industry, only a few watts or more than ten watts of UV lasers are needed, and no kilowatt-level laser power is required. It is used in consumer electronics and automotive industries. In manufacturing technology, the use of flexible circuit boards has become particularly important. Because the UV laser processing system has flexible processing methods, high-precision processing effects and flexible and controllable processing, it has become the first choice for laser drilling and cutting of flexible circuit boards and thin PCBs.

Figure 1: Comparison of cutting grooves by CO2 laser (left) and UV laser (right). The UV laser has a small thermal effect, and its cutting edge is clean and tidy.

CO2 laser or UV laser?

When PCB splitting or cutting, you can choose a CO2 laser system with a wavelength of about 10.6μm. The processing cost is relatively low, and the laser power provided can reach several kilowatts. But it will generate a lot of heat energy during the cutting process, which will cause severe carbonization of the edges.

The wavelength of the UV laser is 355 nm. Laser beams of this wavelength are very easy to focus optically. The spot diameter of a focused UV laser with less than 20 watts of laser power is only 20μm – and the energy density it generates is even comparable to that of the sun's surface.

The advantages of UV laser processing

Ultraviolet laser is especially suitable for cutting and marking hard boards, rigid-flex boards, flexible boards and their accessories. So what are the advantages of this laser process?

In the field of circuit board sub-board in the SMT industry and micro-drilling in the PCB industry, UV The laser cutting system shows great technical advantages. Depending on the thickness of the circuit board material, the laser cuts one or more times along the required contour. The thinner the material, the faster the cutting speed. If the accumulated laser pulse is lower than the laser pulse required to penetrate the material, only scratches will appear on the surface of the material; therefore, two-dimensional code or barcode marking can be performed on the material for information tracking in subsequent processes.

The pulse energy of the UV laser only acts on the material for a microsecond level, and there is no obvious thermal effect at a few micrometers next to the cut, so there is no need to consider the heat generated by the component. Damage. The lines and solder joints near the edge are intact and free of burrs. In addition, the INTELASER system integrates CAM The software can directly import the data exported from CAD, edit the laser cutting path, form the laser cutting contour, select the processing parameter library suitable for different materials, and then directly laser processing. The laser system is not only suitable for mass production processing, but also for sample production.

Drilling application

The through holes in the circuit board are used to connect the lines between the front and back of the double-sided board, or to connect any interlayer lines in the multilayer board. In order to conduct electricity, the wall of the hole needs to be plated with a metal layer after drilling. Nowadays, traditional mechanical methods can no longer meet the requirements of smaller and smaller drilling diameters: although the spindle speed is increased, the radial speed of precision drilling tools will be reduced due to the small diameter, and even the required processing results cannot be achieved. In addition, from an economic perspective, tool consumables that are prone to wear are also a limiting factor.

Efficient separation of PCB and FPC

SMT post-boarding is the cutting of circuit boards on which a variety of electronic components have been assembled. This process is already at the end of the production chain. For board splitting, different technologies can be selected: For commonly used PCBs, priority is given to the use of traditional cutting, stamping and contour milling processes. For more complex electronic circuits and thin substrates, especially those that are very sensitive to mechanical stress, dust and dimensional deviations, it is more advantageous to use UV laser cutting to separate the board.

Laser cutting breakpoint splitting board

For complete contour cutting, Yunteng Laser will give priority to safety and quality for certain thicker materials and expensive assembly components according to the different laser sources used. The cutting time is second.

Other application areas

Because the ultraviolet laser has a short wavelength, it is suitable for most material processing. For example, it can be used in the electronics industry to:

Drill holes in flexible or thin materials

Solder mask or cover film opening

Rigid and flexible circuit board sub-board slotting

Rework of assembled or unassembled circuit boards

Cutting sintered ceramics

Precision cutting low temperature co-fired ceramics




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