Closing the Loop on PCB Etching Waste

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Editor's note: This article appeared in the August 2025 PCB007 Magazine as part of our spotlight on Schweitzer Engineering Laboratories.

As the PCB industry continues its push toward greener, more cost-efficient operations, Sigma Engineering’s Mecer System offers a comprehensive solution to two of the industry’s most persistent pain points: etchant consumption and rinse water waste.

Designed as a modular, fully automated platform, the Mecer System regenerates spent copper etchants—both alkaline and acidic—and simultaneously recycles rinse water, transforming a traditionally linear chemical process into a closed-loop system. The result is significant cost savings, dramatically reduced environmental impact, and a more stable, predictable etching process.

Regenerating Etchant, Reducing Cost

The Mecer System provides tailored modules for alkaline and acidic etchant recovery. Alkaline etchant recovery virtually eliminates the need for fresh replenisher chemicals, requiring only minor adjustments to replace drag-out losses. For cupric chloride-based etching, the system reduces hydrochloric acid usage by up to 95% while restoring the etchant's oxidizing capacity using an oxygen-based process. This approach sidesteps the safety and regulatory concerns of conventional reoxidizers such as chlorine gas or bleach.

In both cases, dissolved copper is extracted from the etchant through solvent extraction and electro-winning. The recovered metal is produced as anodic-grade copper plates with over 99.9% purity—an economically valuable by-product that can be reclaimed every one to two weeks.

Recycling Rinse Water

Another prominent feature is the Mecer System’s rinse water purification unit. By stripping dissolved copper from rinse streams, the system enables direct reuse of rinse water, drastically reducing freshwater demand and effluent output. This capability not only supports compliance with increasingly strict discharge regulations but also alleviates the burden on downstream wastewater treatment facilities.

Environmental and Economic Payback

The Mecer System isn’t just an environmental upgrade; it’s an economic one. Users can expect reduced chemical purchases, lower water usage, and less hazardous waste handling, all of which contribute to a return on investment typically within six to 18 months. The added benefit of high-purity copper recovery provides an additional revenue stream for facilities processing significant volumes of copper etchant.

Smart Control, Seamless Integration

Automation plays a key role in Mecer’s appeal. The system continuously monitors key parameters such as copper concentration, pH, and chloride levels, adjusting real-time dosing and regeneration cycles. It can be operated by existing line staff, integrates easily into standard etching lines, and is built from corrosion-resistant materials for long-term durability.

A Cleaner Future for PCB Manufacturing

The Sigma Mecer System represents a major step forward in sustainable PCB fabrication by reclaiming etchant, recovering copper, and recycling rinse water. It’s an elegant, high-efficiency solution for manufacturers looking to cut costs, reduce waste, and modernize their wet process lines without sacrificing throughput or yield.

To see all of our SEL coverage, be sure to check out the August 2025 edition of PCB007 Magazine.