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82 DESIGN007 MAGAZINE I NOVEMBER 2021 I have always been fascinated with chemistry and chemical processes. My first degree was in chemistry and my first job out of college was in the PCB manufacturing shop in the ana- lytical chemistry lab. During my initial tour I was so surprised with just how many chemical processes there were in PCB manufacturing. I discovered that some of the most critical ele- ments of PCB manufacturing involve chemical processes. Chemicals clean the copper in preparation for the coating that prevents oxidation, and again to remove contaminants before solder resist application. e etching itself uses chem- icals to remove excess copper. Chemicals are also used to electroplate metals such as cop- per, nickel, gold, and tin. In addition, there are many electroless and immersion plating chem- icals that are used to protect exposed copper ahead of the soldering process. Keeping all these chemical baths, sprays, rinses, and processes operating in a tight oper- ating window to maintain quality and predict- able results is a key component in PCB manu- facturing. Best Practices for Chemical Process Control ere are enough methods available to test and analyze chemical processes in a factory to make your head spin. Here is a short primer on the most common, effective methods of test- ing chemical processes: Titrations ere are quite a few chemical components that can be measured in a working chemical bath by a titration. Titration is the process of adding one chemical of a known concentration to a small sample of the bath until a target pH is obtained. Diving Into the Chemical Processes of PCB Manufacturing Connect the Dots by Matt Stevenson, SUNSTONE CIRCUITS

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