The flexible printed circuit (FPC) industry—essential for powering everything from foldable smartphones and wearable health monitors to automotive sensors—stands at a critical crossroads. As global demand for electronics surges, so does scrutiny of its environmental impact: traditional FPC manufacturing relies on a cocktail of toxic chemicals (like ferric chloride for etching and solvent-based cleaners for degreasing) and energy-intensive steps (such as high-temperature substrate curing), which together drive significant waste and carbon emissions. But forward-thinking companies are now rewriting the rulebook with eco-friendly innovations that don’t just reduce harm—they boost efficiency and profitability. Here’s a deep dive into how the sector is redefining sustainability.
Chemicals have long been the backbone of FPC production, but they’re also a major environmental pain point. Etching, the process that carves tiny copper circuits into flexible polyimide substrates, once depended entirely on harsh aqueous solutions. For decades, ferric chloride was the go-to: it dissolves unwanted copper, but it’s corrosive, requires frequent replacement (generating tons of toxic sludge), and needs massive amounts of water for rinsing.
Today, plasma dry etching is revolutionizing this step. Pioneered by firms like South Korea’s LG Innotek and adopted by China’s BOE Technology, this method uses ionized gas (plasma) to blast away excess copper—no chemicals, no rinsing water. LG Innotek’s FPC plant in Gyeonggi-do, which supplies foldable phone makers, switched to plasma etching in 2023. The result? A 92% drop in chemical use for etching, 60% less water consumption, and a 30% reduction in waste disposal costs. “We used to haul away 15 tons of ferric chloride sludge monthly,” says Kim Min-jae, the plant’s sustainability manager. “Now, that waste is zero—we just filter and reuse the plasma gas.”
Cleaning is another area where chemicals are being phased out. After etching, FPCs need to be stripped of residue to ensure reliable component bonding. Traditional solvent-based cleaners (like trichloroethylene) are effective but volatile, toxic, and contribute to air pollution. Enter ultrasonic water-based cleaning, now used by Taiwan’s Unimicron and China’s Shennan Circuits. This tech uses high-frequency sound waves (20–40 kHz) to create tiny bubbles that lift dirt and residue from the FPC surface, paired with biodegradable, pH-neutral detergents. Shennan Circuits, which makes FPCs for medical devices, reported a 70% cut in chemical use for cleaning after adopting the system. “We used 800 liters of solvents monthly before; now it’s just 240 liters of eco-detergent,” says Li Wei, the company’s environmental engineer. “And the FPCs pass all quality checks—no more residue issues.”
Another game-changer is chemical recycling systems. Japan’s Nitto Denko, a leading FPC maker, installed closed-loop recovery for cupric chloride (a less toxic alternative to ferric chloride) in its Osaka plant. The system filters used cupric chloride, removes copper ions, and replenishes the solution for reuse. This cut the plant’s chemical purchase costs by 45% and reduced liquid waste by 85%—a win for both the planet and the bottom line.
FPC production is energy-hungry, especially steps like curing polyimide substrates (which need temperatures up to 300°C) and drying etched boards. These processes once relied on electric ovens or gas heaters that wasted energy by heating the entire chamber, not just the FPCs.
Infrared (IR) heating has solved this. Unlike traditional ovens, IR heaters emit waves that target only the polyimide substrate, heating it directly without warming the surrounding air. Nitto Denko installed IR curing ovens in its 2022 factory upgrade and saw immediate results: energy use for curing dropped by 45%, and carbon emissions from that step fell by 520 tons monthly. “IR heating is faster too—we used to cure a batch in 20 minutes; now it’s 12,” says Takahashi Yuki, Nitto Denko’s production director. “That means higher output alongside lower emissions.”
Renewable energy is also becoming a staple. Unimicron, Taiwan’s largest FPC manufacturer, covered the roofs of its Taichung and Kaohsiung plants with 12,000 solar panels in 2021. The panels generate 4.2 megawatts of power—enough to cover 35% of the plants’ electricity needs. In 2023 alone, this saved 8,700 tons of CO₂ emissions—equivalent to taking 1,890 cars off the road for a year. Meanwhile, LG Innotek’s Vietnam FPC plant now runs on 100% wind power sourced from local farms, cutting its Scope 2 emissions (from purchased energy) to near zero.
Even small tweaks add up. Many FPC makers are switching to LED lighting in factories (cutting electricity use for lighting by 50%) and installing smart energy management systems that shut down idle equipment. Shennan Circuits’ Guangzhou plant, for example, uses AI to monitor energy use in real time—last year, this prevented 320 tons of unnecessary CO₂ emissions by turning off unused etching machines and ovens.
These innovations aren’t just about meeting environmental regulations (though that’s a factor—like the EU’s upcoming Carbon Border Adjustment Mechanism). They’re also about long-term profitability. For one, reducing chemicals and energy cuts operational costs: Shennan Circuits saved $2.3 million in 2023 from lower chemical purchases and energy bills. For another, eco-friendly FPCs are becoming a selling point. Major brands like Apple and Samsung now require suppliers to meet strict sustainability standards—LG Innotek says its plasma-etched FPCs helped it win a $500 million contract with Apple in 2023.
There’s also the matter of waste reduction. Traditional FPC production has a high scrap rate (up to 8%) due to chemical errors (like over-etching). Plasma etching and ultrasonic cleaning have cut that rate to 3% at LG Innotek—meaning less material waste and more usable FPCs. “Sustainability and quality go hand in hand,” Kim Min-jae says. “When you stop using messy chemicals, you get more consistent results.”
The FPC industry still has room to grow—for example, more companies are exploring bio-based polyimide substrates (made from plant oils instead of petroleum) to further cut carbon footprints. But the progress so far shows that green manufacturing isn’t a sacrifice—it’s a transformation. As Nitto Denko’s Takahashi Yuki puts it: “FPCs power the future of electronics. Now, they’re also powering a greener future for our planet.”
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