Multilayered circuit boards sandwich layers of copper and glass reinforced polymers (FR4) together to enable more complex circuitry on smaller boards. To connect the layers of copper, holes are drilled and then plated. However, the mechanical action and heat generated by the drill causes some of the polymer to melt and smear across the copper layers. This smear prevents adhesion of the copper plated through the holes and blocks the electrical connection. To remove it, typical processes treat with alkali permanganate at high temperature.

The Susonence ultrasound based process uses much lower chemical concentration in its formulation and a lower bath temperature. The images below show smear still present on the copper layer with the standard process, but the Susonence process leaves the copper completely clean even though the chemical concentration and temperature is reduced.

Standard process  Smear on copper

Susonence process  Clean copper track

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