New, Greener Solutions for Etch: Novel Copper Extraction

Estimated reading time: 1 minute

“Novel” is a typical marketing phrase that implies new and unique, but often “novel” actually means an established technology being applied to a new field or application. This, in turn, is often driven by newly relevant external motivation. GreenSource has been working on just such a solution: novel copper extraction, offering a better and greener alternative to traditional LLE control systems for cupric chloride etch.

Dissolved copper concentration is a key parameter for high-resolution circuit formation in cupric chloride etch solutions. Too little dissolved copper will exacerbate isotropic etching and result in poor line shape, while too much copper will render the etch rate too low to be a viable process. This leads to solution sludging and the inevitable formation of crystals on rollers, which can be detrimental to high-end, tight-feature yields. Controlling the copper concentration is essential for a stable operation.

This article presents an overview of an ion exchange process that has been fully developed through testing and will soon be made available to the PCB industry as a method for copper control in cupric chloride etching. Testing has established that a copper-phillic medium is a viable alternative to the predominant solvent extraction method used for copper control in cupric etch solutions, also known as liquid-liquid extraction (LLE) systems. Though well-maintained LLE systems are effective, the risks of using a highly flammable solvent in a PCB environment are obvious. Cost, footprint, potential cross-contamination of the etching process, and end-of-life care considerations are significant motivations for doing this differently.

To continue reading this article, which originally appeared in the March 2026 edition of I-Connect007 Magazine, click here.