Laser Engraving: CO2 and Fiber Lasers

The laser marking industry is starting to meet the diverse challenges in packaging and fabrication.

This industry is constantly changing and evolving, which is one reason laser marking for certain products is preferred.

The Basics of Laser Marking

Laser engraving/marking involves creating a visible texture or color change on the desired surface. Less commonly, laser marking is used to generate macroscopic surface changes.

It’s important to understand the most commonly used laser systems and how they differ in marking.

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  • CO2 Lasers – CO2 lasers are used for PCB marking due to the fast process it offers for producing high-contrast features. One the other hand, CO2 laser systems are seldom used at the level of package or die marking because of the issues of diffraction from the focused spot size of CO2 laser beams.
  • Fiber Lasers – The high-powered output of fiber lasers (available from https://www.needham-coding.com/systems/fiber-laser-marking-machines/) has brought it popularity in the high-speed marking sectors. Fiber lasers render a compact footprint and offer space and cost savings. Fiber lasers also have their drawbacks like the Gaussian intensity effect they produce that isn’t ideal for laser marking. They also don’t provide the high-purity marking needed for the marking industry. Flat-top beam profiles in fiber laser systems help resolve this issue.
  • DPSS Lasers – This type of laser emits almost infrared. They are more expensive than fiber systems that use the same power output. The benefits of DPSS is that this laser application can be configured for multi-mode beam, which is basically like the flat-top of fiber laser systems. It’s been used in semiconductor marking because of its efficient ability to generate high-contrast marking you can’t get from a fiber laser. The output for DPSS lasers are also more stable than fiber lasers. However, the cost to buy and use them is still high.

Current Laser Marking

The initial consideration for choosing a laser system for specific applications requires matching the laser wavelength with the absorption capabilities of a substrate being marked. The beam precision is another factor and finally he HAZ constraints.

Most laser marking done today is done on wafer-thin packaging, semiconductors and microchips, metal lids for microprocessors, leadframes, certain ceramics used to package semiconductors, and other IC substrates.

The focused beam, reliability, and high-pulse energy of some laser technology makes it ideal for these kinds of applications, but it still isn’t ready to take over the ink marking industry.

Future of Laser Marking

As packages get smaller and thinner in size, shallower markings with high resolution will be needed. Sub-nanosecond laser systems show the most promise in the future marking sector.

Even with the fine marks and focused technology of laser marking, semiconductor packaging and fabrication still present some challenges in marking because of the delicate nature and how marks need to be produced without significantly affecting the surrounding surface of the materials.

The trend of thinner and smaller devices will continue to drive the demand for high-precision laser equipment like sub-nanosecond lasers, nanosecond lasers. It’s still unsure if prices will go down as the demand for laser marking increases.