Issue link: https://iconnect007.uberflip.com/i/1493443
82 PCB007 MAGAZINE I FEBRUARY 2023 Desmear and Metallization From a pure materials stand- point, these higher perfor- mance resins are more diffi- cult to desmear and metallize. Because the modulus is higher, the materials are more brit- tle. These materials are also more chemically resistant to chemical processes, including alkaline permanganate chem- istries. One cannot rely on the high surface area and honey- combed texture on the resin that is common with lower Tg materials. However, ensuring that drill smear and other debris are removed, the alkaline permanganate process must also activate both the resin and glass to enable the adhesion of subsequent copper plating. Loose debris and a smooth resin sur- face will not provide the necessary adhesion sufficient to withstand thermal excursions and mechanical shock. In Part 2 of this series, I'll be taking a deeper look at metallization. PCB007 References 1. Getting Started in HDI Fabrication, by Happy Holden and Michael Carano, internal publication, Feb 2021. Michael Carano is VP of quality at Averatek. To read past columns, click here. Figure 3: Honeycomb texture after alkaline permanganate desmear (low Tg material).