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32 PCB007 MAGAZINE I OCTOBER 2022 Feature Article by Christopher Bonsell CHEMCUT When it comes to obtaining high-quality images, many different factors come into play. Typically, most of these factors come down to your imaging equipment and cleanroom; how- ever, there are factors involved in the etch- ing process that can affect the quality of your image. Here are five steps to ensure your etch- ing process is optimized for the best image quality. 1. Be wary of undercut. When you are etching to obtain your cir- cuitry patterns on a PCB, beware of undercut. Due to your solution's etch factor—the ratio of sideways etch to downward etch—your image will need to compensate any change and varia- tion that can arise. Naturally, when you create a line with a photoresist to make a feature, the outcome of that feature will be smaller because of the sideways etching. PCB designs typically account for this, but if you are working with thicker copper layers for your PCBs, you will have to be cautious and ensure that the side- ways etch does not impact the features you desire. 2. Monitor your etchant quality. Maintaining consistency of your etch chem- istry is the key to ensuring your etcher gives a quality image. As you etch panels, your etchant will decline in quality because it loses reac- tion potential (from the depletion of reac- tants), and with that, you will pick up con- taminants. To prevent this from affecting your etching process, you will need to implement process controls to maintain the properties of Optimize Your Etcher for Best Image Quality

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