FEMTOSECOND LASER PROCESSING Figure 3: Processing of stainless-steel with femtosecond laser.


making it difficult to process them without damage. Femtosecond lasers, due to their minimal heat- affected zone, are ideal for this task. While most femtosecond lasers operate at 1030 nm, switching to shorter wavelengths can further reduce thermal effects. In one case, a customer working with a thermally sensitive polymer was dissatisfied with a 23 µm heat-affected zone at 1030 nm. By switching to the second harmonic (515 nm), absorption improved significantly, reducing the heat-affected zone to just 8 µm— well within the required tolerances (Figure 2).


METAL MICROMACHINING


Femtosecond lasers also excel in metal micromachining, offering burr-free edges and negligible heat- affected zones. This enables the production of intricate metal parts without the need for secondary operations. Ekspla has successfully demonstrated processing on stainless steel, aluminum, copper, brass, and nitinol, as well as multilayer foils used in battery


and energy storage applications (Figure 3).


SELECTIVE SURFACE ACTIVATION INDUCED BY LASER (SSAIL)


Beyond material removal, femtosecond lasers are unlocking new possibilities in additive manufacturing and electronics fabrication. One standout example is Selective Surface Activation Induced by Laser (SSAIL)—a laser-based metallisation method to complement or replace traditional photolithography. While photolithography offers high resolution, it comes with significant cost and complexity. Meanwhile, additive methods like inkjet printing offer flexibility but are often limited in speed and scalability.


SSAIL addresses this gap by enabling the creation of copper traces with resolutions down to 1 µm and throughput comparable to lithography—while maintaining the simplicity and digital control of additive approaches. The process


begins with laser modification, where an ultrashort pulse laser selectively alters the substrate’s surface, introducing microscale structural and chemical changes. These modified regions are then subjected to catalytic activation by immersion in a metal precursor solution, which binds selectively to the laser-processed areas. Finally, an electroless plating process deposits a uniform copper layer only on the activated regions, resulting in precise and conductive traces (Figure 4). With its combination of resolution, speed, and simplicity, SSAIL presents a strong case as a next- generation technology for electronics manufacturing (see cover image).


SUMMARY


Femtosecond lasers are already playing a crucial role in advancing the consumer electronics field by enabling high-precision, high- quality processing of a wide range of materials. As demand grows for tighter tolerances, smaller features, and more efficient production methods, the importance of ultrafast laser technologies will only increase. With ongoing improvements in performance and integration, femtosecond lasers are set to become an even more central tool in developing next-generation electronic devices.


* Deividas Andriukaitis1 Gečys2


, Tadas Kildušis3


1 Ekspla, Vilnius, Lithuania; 2


Technology, Vilnius, Lithuania; 3


Center for Physical Sciences and Akoneer, Vilnius, Lithuania.


, Paulius


d.andriukaitis@ekspla.com ekspla.com


Figure 4: SSAIL process steps for micro trace formation. Courtesy Akoneer.


Deividas Andriukaitis is a Laser OEM Sales Manager for Ekspla, with interests in femtosecond lasers and microfabrication, especially for industrial applications.


LASER USER 118 DECEMBER 2025 | 29


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