Ultraviolet laser used in flexible circuit cutting

by:Caodahai     2021-09-24
Flexible printed circuits (Flexible Printed Circuits, FPC) can achieve a variety of designs that cannot be achieved with traditional rigid circuit boards. For example, making circuits on flexible materials can form new applications that challenge the limits, including various multi-layer functions and solutions for the space, telecommunications, and medical industries.   The current trend in the FPC industry is miniaturization, because designers try to reduce the size of the circuit while eliminating the factors that limit the mounting density or the distance between the circuits on the circuit board. Meeting these requirements usually requires arbitrary shaping, but the basic square circuit is too elastic to meet the requirements of many modern applications.  These design requirements are challenges, including the problem of partitioning or the process of removing the circuit from the board. How can we accurately cut smaller arbitrary circuits with high mounting density without damaging the components or the circuit itself? Flexible circuit materials are very unique, and even small stresses on the circuit during cutting can cause damage. In order to avoid such damage, it will limit the variety of designs. The design must consider the buffer space around each cut, which means that the width of the cut will be wider than necessary, the placement of components cannot be close to the edge of the board or close to each other, and the forming cannot be as complicated as needed. If there is no feasible solution for this type of problem, these limitations will overwhelm innovation, because the unsatisfactory way of dividing the board will become the main design consideration.  Automatic circuit board cutting (Routing) and traditional mechanical splitting methods (such as die punching) will result in larger cutting widths and excessive stress for complex flexible circuits. Even the CO2 laser cutting method is also unsatisfactory in this respect, because this method will produce a larger heat-affected area.   However, when it comes to FPC sub-board cutting, there has been a technology that can meet the challenge: UV laser cutting. This technology can eliminate the physical stress of the mechanical process and greatly reduce the thermal stress of the CO2 ultraviolet laser, which can meet the design trends described above. Exploring various factors can reveal: why ultraviolet laser cutting has become an option when it comes to flexible circuit cutting.  Circuit stress and cutting width  All flexible cutting methods will produce a certain amount of stress on the circuit board, but there are differences in the type of stress introduced and the degree to which the stress affects the circuit. When considering the above-mentioned sub-board method, there may be two types of stress on the flexible printed circuit board: mechanical stress or thermal stress.   When using mechanical splitting methods such as die punching or routing, mechanical stress will occur. The effects of mechanical stress on flexible circuits include: burrs, deformation and damage to circuit components. These effects are very serious for flexible materials. For example, die punching is a high-impact process that will vibrate the circuit and damage the components, and it requires a considerable cutting buffer space. In die punching and routing mode, the typical FPC cutting width is 1 mm, but this width is too large for many complex and arbitrary flexible circuits. Such wide cuts can lead to: reduced mounting density, or reduced circuit mounting on each board. In an era when flexible printed circuits are becoming smaller and more compact, this has risen to technical and cost issues. Because the mechanical cutting method cannot meet the flexible design standards, users turn to laser cutting, but it produces a different type of influence on the circuit: thermal stress. There is a huge difference between thermal stress and mechanical stress. The laser beam has no physical contact with the circuit. For this reason, laser cutting can be more accurately described as laser ablation. The common effects of thermal stress are scorch and incision width inconsistencies. However, these effects are more common when using pulsed CO2 laser systems. These systems are equipped with high-energy-density power supplies and the wavelength of the laser is in the warmer, better-absorbing infrared spectrum. The UV laser system is equipped with a cold UV laser operating at a lower energy level, which can reduce the effect of thermal stress to a lower level. (The above is edited by metal laser cutting machine cutting experts from the Internet, see www.gnlaser.com for details)
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