Issue link: https://iconnect007.uberflip.com/i/1536435
16 PCB007 MAGAZINE I JUNE 2025 Stefan Rung: The laser itself is quite a new tool, relatively speaking. Since its inven- tion in 1960 by Theodore Mayman, there has been a demand for high-throughput tools and lasers. CO 2 lasers, with a wavelength in the infrared region at 9.4 µm, were adapted for high-throughput drilling. This was possible because those lasers had the high energy out- put needed to remove material in a short time. Additionally, the CO 2 laser benefited the PCB industry because it could stop at the copper plane. CO 2 lasers have high copper reflectivity, absorption of just a few percent- age points. The target copper plane reflects all the light from drilling the organic material, so you have a natural process stop making the CO 2 laser process inherently controllable. In mechanical drilling, the longer you drill, the deeper the hole. There is no precise automatic stop that would compensate for variations in the layer thickness. For multilayer build- ups, using a CO 2 laser allowed for lower cop- per weights on the inner layers. You now had a reliable tool to stop on the copper and create the microvia. This contributed to the broader adoption of the CO 2 laser in PCB shops. As laser technology developed, UV nano- second lasers emerged. Instead of microsec- ond-long pulses, they now had hundreds of thousands of nanosecond-long pulses in a typical wavelength of 355 nanometers. These UV lasers showed good absorption of the organic material and copper, allowing us to drill through the copper surface and the organic material. However, that created a challenge to stop on a thin target copper plane. With the more pre- cise laser sources in development over the past decades, it has been easier for process engi- neers to develop processes to stop when they need to stop. There were also some advantages with specially designed prepreg structures that helped make this process more reliable. Both rising laser technologies have had their benefits and drawbacks. Now, with hybrid drilling technology, the UV nanosecond laser can penetrate the top copper layer, and then use the microsecond-long pulse CO 2 laser to penetrate or to remove the dielectric, which then stops at the next copper plane. This drill equipment combined both useful technologies within one machine, and many