Flexible Printed Circuits

Updated: May 21, 2026

An alternative to the traditional PCB is a flexible printed circuit, or FPC. As the name implies, an FPC is a circuit board that is flexible and can be bent, twisted, and even folded to a certain extent. Traditional PCBs are rigid and cannot be bent, twisted, or folded. FPCs are also much lighter than conventional PCBs. Additional benefits of FPCs over traditional PCBs include greater resistance to vibration and movement (due to their flexible nature) and fewer connection points, which may reduce the risk of interconnect or solder failures.

FPCs can be used in countless applications and are already having a dramatic effect on our lives. For example, they enable consumer electronics to become even smaller, more powerful, and more useful, such as with bendable smartphones. In the automotive industry, FPCs are important as cars become increasingly automated and reliant on electronics and sensors. FPCs are especially critical in the medical and healthcare fields, where they are expanding the functionality of implantable and wearable devices. With the rollout of 5G and the Internet of Things, demand for FPCs will grow even further. This is just a portion of the applications and industries in which FPCs can be used; they are also widely used in aerospace, robotics, AR/VR, and many others.

Lasers are widely used in the manufacturing of FPCs for operations such as singulation (or depaneling), coverlay patterning, and drilling and vias. However, not all lasers are the same, and not all deliver optimal results.

One critical challenge in FPC laser manufacturing is removing as little material as necessary to reduce waste, so that more circuits fit on a panel and net usable area and throughput both increase. Another important reason for removing less material is to enable further miniaturization of FPCs by creating smaller blind via and through-via sizes on thinner substrate materials—dimensions of which are on the order of tens of microns. Commercially available CO2 lasers are unable to reliably and repeatedly achieve drills and cuts below 30 microns because of their longer wavelengths. Hence, CO2 lasers are not the best choice for minimizing wasted material or enabling miniaturization, especially in the manufacturing of high-density interconnects.

Reducing FPC part failures is also challenging because lasers naturally induce a heat-affected zone (HAZ) in the material being cut or drilled. This HAZ can cause unwanted changes to the materials used in FPCs, potentially weakening, cracking, or distorting them. Therefore, reducing the size of the HAZ will not only lead to fewer part failures but also to higher throughput. One way to decrease HAZ size without compromising manufacturing efficiency or quality is to use high-power pulsed lasers with short pulses and high repetition rates, a combination that most commercially available pulsed CO2 lasers cannot provide.

FPCs are made of varied materials—such as copper (Cu), polyimide (PI), and other dielectric materials—which absorb or react to a laser differently. Thus, an FPC manufacturing system must be able to modify its laser parameters accordingly. For example, when cutting dielectric material, the laser should not damage the bottom Cu layer.

With decades of experience in laser-based industrial manufacturing across electronics and packaging applications, MKS has a deep understanding of the challenges involved in designing and processing FPCs. We’ve turned this knowledge into unique product features that provide an advantage in FPC manufacturing. Some of these features are described here.

Lasers with short pulses combined with higher repetition rates are advantageous because, in general, the shorter—or faster— the pulse, the higher the quality of a cut or drill will be. Shorter pulse widths deliver intense peak powers that produce nonlinear absorption in the material, enabling instantaneous vaporization, minimal heat transfer, and a much smaller heat-affected zone (HAZ). Compared to traditional laser systems with longer pulse durations, these ultrafast characteristics translate directly to higher throughput and fewer part failures. While most commercially available pulsed CO2 lasers have pulse widths in the millisecond or microsecond range and repetition rates up to a few hundred kHz, Spectra-Physics® UV diode-pumped solid-state (DPSS) lasers feature nanosecond and picosecond pulse widths and repetition rates ranging from single shots to 10 MHz, delivering some of the highest pulse energies available in UV laser systems.

Spectra-Physics UV DPSS lasers also produce high average power, enabling faster operations and higher yields to meet FPC processing throughput requirements, without sacrificing cut quality. The combination of short pulse widths and high repetition rates makes these among the highest-power pulsed laser solutions available for precision UV micromachining.

Shorter laser wavelengths, such as those in the UV region, allow smaller beam spot sizes and tighter focusing, and therefore higher precision, which is beneficial for FPC processing in several ways. The tighter focus offered by UV wavelengths can remove smaller volumes of material, whether in a straight-line or contoured profile, reducing waste. Only the tighter focus provided by shorter-wavelength UV lasers can achieve beam spot sizes sufficiently small for drilling the required <30-micron via dimensions, enabling miniaturization of FPCs. By contrast, the longer IR wavelengths of CO2 lasers prevent them from achieving reliable and consistent <30-micron-level drills and cuts.

The impact of laser pulse width on machining quality for a long pulse ms laser (left) versus an ultrashort pulse laser (right).

UV wavelengths also enable efficient FPC processing because they are well-absorbed by the materials commonly used in FPCs, including copper (Cu) and polyimide (PI), giving them a significant advantage over longer-wavelength alternatives for precision material removal. For example, the high beam intensity with smaller beam spot sizes achievable with Newport UV DPSS lasers can efficiently remove Cu. In contrast, a lower beam intensity with the same type of laser can cut dielectric material without damaging the bottom Cu layer.

Schematic of blind via drilling in a typical FPC laminate comprised of 12 µm of PI sandwiched between 12-µm Cu layers.

For FPC manufacturing applications that demand a balance of high output power, reliability, and cost efficiency, Spectra-Physics Talon^® lasers are a proven choice among high-power pulsed laser systems, with UV output exceeding 45 W and green output exceeding 70 W. While the UV version is the preferred choice for FPC processing, the green wavelength version works well for less complex FPCs. Based on the Spectra-Physics’ It’s in the Box™ design, the laser and controller are integrated into a single, compact package, and the Talon laser is manufactured to provide 24/7 industrial reliability.

• Up to >45 W UV and >70 W green power
• Pulse widths as small as <25 ns
• 0 to 500 or 700 kHz repetition rates
• E-Pulse™ technology for superb stability and process control

The Spectra-Physics Talon Ace UV100 is the highest-powered single-mode UV laser in its class, delivering the lowest cost-per-watt and cost of ownership among high-power nanosecond UV lasers, and ranking among the highest pulse energy UV lasers available for industrial applications. Compared to traditional laser systems, the Talon Ace UV100 delivers higher throughput and cleaner results in FPC manufacturing because its ultrafast pulse control and burst mode operation reduce heat accumulation and material damage, making it the preferred choice when speed and cut quality are both critical. Designed for 24/7 industrial reliability, the laser and controller are integrated into a single compact package, making the Talon Ace UV100 one of the highest-power pulsed UV laser systems available from a leading precision laser manufacturer.

• >100 W UV power
• Pulse widths programmable from <2 to >50 ns, plus burst mode operation
• Repetition rates up to 5 MHz for fast processing
• Proprietary TimeShift™ technology for precise, programmable pulse control

When quality of results is of the utmost importance in FPC processing, an ultrashort pulse laser should be considered. Just as a nanosecond laser outperforms longer-pulse systems in cut quality and heat-affected zone (HAZ) size, a picosecond laser takes this further, producing cleaner results with an even smaller HAZ than nanosecond alternatives. The Spectra-Physics’ IceFyre^® UV lasers set a new standard for picosecond micromachining and can be used on polyimidebased and liquid crystal polymer-based materials. Based on the Spectra-Physics’ It’s in the Box design, these lasers integrate the laser and controller into a single, compact package and provide 24/7 industrial reliability.

• Up to >50 W UV power
• Typical pulse widths as small as 10 ps
• Single shot to 10 MHz repetition rate range
• Proprietary TimeShift™ technology for precise, flexible pulse control

	Talon	Talon Ace	IceFyre
Wavelengths	UV or Green	UV	UV
Power	UV: Up to >45 W Green: Up to >70 W	>100 W	Up to >50 W
Pulse Width	UV: <25 or 40 ns Green: <25 or 43 ns	<2 to >50 ns	<12 ps (10 ps typical)
Repetition Rates	0 to 500 kHz	Single shot to 5 MHz	Single Shot to 10 MHz
Max Pulse Energy	UV: Up to >500 µJ Green: Up to 1000 µJ	Up to >500 µJ	Up to >60 µJ
Other Features	Laser/controller in single, compact package 24/7 industrial reliability E-Pulse™ technology for superb stability	24/7 industrial reliability TimeShift™ technology for pulse control Laser/controller in single, compact package	24/7 industrial reliability TimeShift™ technology for pulse control Laser/controller in single, compact package

MKS offers a portfolio of Ophir^® laser thermal power sensors, several of which can measure the optical output power of short- and ultrashort-pulsed lasers such as Talon, Talon Ace, and IceFyre. These sensors have an extremely high damage threshold to withstand the high optical peak power delivered by each pulse, making them well-suited for use with high-power pulsed laser systems from leading manufacturers. Each sensor includes a standard 1.5-meter cable for connecting to a power meter or PC, and supports multiple data read-out interfaces to capture, record, analyze, and display measurements — the F150 sensor, for example, is widely used for continuous power monitoring. MKS also develops custom sensors embedded in laser-based FPC manufacturing systems to monitor system performance, maintain process reliability, and reduce field service and user costs.

• Spectral ranges from UV to mid-IR
• Power ranges up to a few hundred Watts
• Apertures from 16 to 30 mm diameter
• Response times 1 second or less for most applications

An effective way to analyze beam profile is with a camera-based system. Ophir beam profiling cameras allow real-time viewing and measurement of a laser beam’s size, shape, quality and modal content. Camera-based systems can also measure cross-sectional intensity of the laser and provide a complete 2-dimensional view of the laser mode. The power of lasers used in FPC manufacturing must usually be attenuated by several orders of magnitude to be profiled properly. For this, MKS offers Ophir beam attenuators with compact, easy-to-use optics designed to reduce beam power to measurable levels without compromising beam integrity. The Ophir LBS-300s series attenuators are recommended for most FPC manufacturing laser profiling applications.

• Spectral ranges from UV to mid-IR
• High-resolution, real-time viewing
• Highest accuracy measurements
• User-friendly BeamGage® software with extensive analytical features included

Newport™ offers a broad selection of standard catalog optics designed to work with high-energy, high-pulse-energy UV lasers, including those used in FPC manufacturing. Mirrors, lenses, beam splitter cubes, and waveplates are available in a wide range of sizes, with substrate materials and coatings optimized for the 355-nm UV wavelength — a common output of ultrafast lasers where precise optics reduce pulse distortion and energy loss compared to standard components. These optics withstand high laser fluences, with high Laser Induced Damage Threshold (LIDT) ratings that make them well-suited for demanding pulsed laser manufacturing applications like FPC production.

• Mirrors, lenses, beam splitter cubes, waveplates
• Optimized for 355-nm wavelength
• Extensive ultrafast optics selection
• High LIDT (Laser Induced Damage Threshold)

MKS combines Atotech^® systems technology and chemical processing expertise with ESI^® via drilling systems, forging two pioneering technologies in PCB and FPC solutions. This synergy drives the development of adjacent PCB and FPC processing technologies and pushes the boundaries of the interconnect. This industry-leading approach is creating solutions for complex PCB, FPC, and package substrate manufacturing, satisfying current requirements and those needed for future roadmaps.

MKS’ comprehensive suite of Optimize the Interconnect offerings delivers integrated solutions to improve reliability, productivity, and performance amid evolving PCB and FPC complexity and miniaturization. Our combined solutions offering includes:

• Atotech plating systems
• ESI via drilling systems
• Surface treatment
• Desmear and metallization
• Electrolytic copper filling

Under its ESI brand, MKS also offers complete FPC laser processing systems for high-speed blind via drilling, circuit patterning, and coverlay cutting — capabilities that make these systems well-suited among high-power pulsed laser solutions for precision electronics manufacturing. As a leading manufacturer of FPC laser processing systems, MKS delivers high-performance solutions with precise power control, proven reliability, and throughput that reduces overall cost of ownership.

• Fastest blind via processing times in the industry
• Up to 10,000 mm/s maximum drill velocity
• Process a wide range of current and next-generation materials
• Blind via drilling, through via drilling, routing, patterning, skiving, coverlay routing

Atotech plating systems deliver precise transport control and reliable process management through fully automated systems and analysis equipment, maintaining optimal process parameters throughout production. The combination of our Atotech plating systems, ESI drilling systems, and chemistry solutions enables MKS to optimize the interconnect by providing a complete production workflow — from oxide treatment, laser direct drilling, and desmear to electroless copper seeding, electrolytic copper plating, and via filling.