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58 DESIGN007 MAGAZINE I APRIL 2024 Article by Yash Sutariya SATURN ELECTRONICS CORPORATION Editor's note: To read Part 1 of this article, which appeared in the March 2024 issue of Design007 Magazine, click here. Another factor designers must consider is minimum spacing. Often, we run across designs that would work well for 0.5- or 1-ounce base copper but are actually intended for 3- or 4-ounce copper. Failing to account for etch compensation is one of the most frequent mistakes we see in designs. e most common method for etching is using an etchant chemis- try called ammonium hydroxide. As you etch down the unwanted surrounding copper, you also etch against the edges of the desired cop- per, resulting in smaller features. Heavy Copper PCBs: Bridging the Gap Between Design and Fabrication, Part 2 Design issue: Feature-to-feature spacing too small Manufacturing pitfall: Etch factor/compensation For this reason, our front-end CAM opera- tors increase all features proportionally to the finished desired copper weight. Etch factor (etch compensation) predicts the mechanics of etching so it is important that designers assign adequate spacing between features. Figure 7 is a brief pictorial description of the outer layer etching process. A similar mechanism applies to the inner layer etching process. Design Solution To create a universally buildable design, you should account for 0.001"/25 microns of inward Figure 7: A description of the outer layer etching process.