Application research of 5 Watt 355 laser source marking on QR code below 1x1mm

As a modern precision machining method, laser marking technology has unparalleled advantages compared with traditional machining methods such as corrosion erosion, electrical discharge machining, mechanical scribing, and printing.

The demand for precision marking in industrial manufacturing has seen positive momentum in recent years. In particular, the production of premium consumer goods is driving this trend to ensure the highest quality, such as the marking of logos and ultra-fine 2D matrix codes for parts tracking, managing supply chain quality, and preventing product piracy. In many cases, such codes are intentionally invisible to consumers, but can be read by sensors in the production process.

The laser marking machine uses a laser beam to permanently mark the surface of various substances. The effect of marking is to expose the deep material through the evaporation of the surface material, so as to engrave exquisite patterns, trademarks and characters. Laser marking machines are mainly divided into CO2 laser marking machines, semiconductor laser marking machines, and fiber laser marking machines. And YAG laser marking machine, laser marking machine is mainly used in some occasions requiring finer and higher precision.

Because of these advantages, precision laser marking is increasingly being used in a variety of industrial manufacturing industries, including microelectronics, semiconductors, and the automotive industry.

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Advantages of laser marking technology:

1. Using laser marking as the processing method, there is no processing force between the workpiece and the workpiece. It has the advantages of no contact, no cutting force, and little thermal influence, which ensures the original accuracy of the workpiece.

2. The spatial controllability and time controllability of the laser are very good, and the degree of freedom for the material quality, shape, size and processing environment of the processing object is very large, and it is especially suitable for automatic processing and special surface processing.

3. The laser marking machine has fine engraving and engraving, and the lines can reach the order of millimeters to microns. It is very difficult to imitate and change the marks made by laser marking technology, which is extremely important for product anti-counterfeiting.

4. The combination of laser processing system (system) and computer numerical control technology can form efficient automatic processing equipment (shèbèi), which can print various characters, symbols and patterns, easy to use software to design marking patterns, change the content of marked websites, and adapt to modern production. High efficiency, fast paced requirements.

To achieve these precision marking results, the choice of laser type is critical. There are two generally accepted principles of laser marking: one is to "thermally process" a laser beam with a higher energy density (it is a concentrated energy flow), which is irradiated on the surface of the material to be processed, and the surface of the material absorbs the laser energy. The thermal excitation process occurs in the area, so that the temperature of the material surface (or coating) rises, resulting in metamorphosis, melting, ablation, evaporation and other phenomena. Another kind of "cold working" is to use (ultraviolet) photons with very high loading energy to break the chemical bonds in the material (especially organic materials) or the surrounding medium, so that the material is destroyed by a thermal process. This cold working is of special significance in laser marking because it is not thermal ablation, but cold peeling that breaks chemical bonds without the side effect of "thermal damage", so it does not affect the inner layer and adjacent areas of the machined surface. Produce heating or thermal deformation and other effects. For example, excimer lasers are used in the electronics industry to deposit thin films of chemical species on substrate materials, creating narrow trenches in semiconductor substrates.

Lower precision, lower quality laser marking mainly uses infrared fiber lasers due to lower cost. At the other extreme, ultrashort-pulse picosecond and femtosecond exciters can generate the highest quality marking results and 2D matrix codes in almost any material, but at a significantly higher cost. The solution to the cost and performance dilemma is a well-designed pulsed UV nanosecond laser.

UV laser marking machine that meets all the key requirements for marking ultra-fine data matrices down to 100 µm in size. Ultraviolet wavelengths produce finer features and markings due to the ability to focus to a tighter spot size and a shallower absorption depth in most materials. Very high beam quality is also available, i.e. a circular beam profile with low astigmatism and M², allowing users to achieve near diffraction-limited focal spots. Typical ellipticity of UV lasers is <1.1, astigmatism <0.1*, and M² is about 1.1.

Since high-quality results also depend on the specific material being processed, we need a broad and flexible range of laser parameters to cover a wide range of materials. UV laser markers are available in high energy models with UV ranges >100 µJ and >200 µJ at 532 nm and higher power versions up to >4 W at 355 nm and >5 W at 532 nm, through high repetition rates. meet these needs.

We also need advanced pulse control capabilities to facilitate high-quality machining. Pulse-on-demand (E-Pulse™) with constant pulse energy enables fast precision marking and provides PSO motion capabilities (Application Focus #44). The closed-loop pulse energy control capability of UV lasers, called E-Track™ (reported in Application Focus #32), enables fine control of each laser pulse, resulting in ultra-fine structures. Using a UV laser, we demonstrate the marking of ultrafine machine-readable barcodes in mobile device applications and ceramics used in soda lime glass. With UV wavelengths, we were able to generate dots smaller than 10 µm in size, resulting in a 200 µm data matrix of 20×20 dots. Due to the excellent beam properties of UV lasers, we achieved these small spots using a galvo mirror containing an f = 100 mm telecentric lens, i.e. with moderate focusing without complex sample positioning requirements. High processing speed and marking time of approx. 100 ms can be achieved for 20×20 barcodes using the galvo mirror.

Another application that requires hyperfine structure is the direct writing of logos. Strict surface quality requirements dictate the use of ultra-fine structures so that the contrast of this logo produces a novel and premium look without sacrificing surface topography. In many cases, the surface must remain smooth, or have some kind of tactile sensation when touched by a human.

In conclusion, a pulsed UV nanosecond laser with attractive cost and performance can efficiently generate ultrafine structures on 2D data matrices as well as various materials used in logo marking. UV laser markers are ideal for these demanding applications.