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62 PCB007 MAGAZINE I NOVEMBER 2020 Feature by Happy Holden I-CONNECT007 I want to talk to you about a subject that gets little discussion but is essential to running a successful PWB facility: process control. This involves the control of chemical concen- trations in our many PCB processes, especial- ly those that have been mechanized and can change very rapidly. I confess. I am a control nerd and highly an- alytical. My second degree is in EE control the- ory, and I see the world in terms of feedback loops and black boxes. Early in my career, I was volunteered for the technical programs for the California Circuits Association (CCA), which was created by my mentor Clyde Coombs. In discussions with fellow process engineers, it was clear that the chemical process controls that HP could afford and allow me to put in place were not able to be duplicated by much smaller PWB shops. This topic has also been a favorite of mine ever since I started working as a process engi- neer in printed circuit fabrication. Fortunate- ly, I took a graduate course in instrumental an- alytical chemistry taught by a chemical engi- neering professor. In that class, we built over 40 analyzers, spectrometers, and titrators us- ing a Lego-like modular analytical system, in- cluding the electronics. This showed me how simple this problem and its solution really is. Sure, you can buy sophisticated measure- ment tools and lab equipment. For cutting- edge processes, the chemistry lab is an impor- tant part of the process control. But there con- tinues to be room for simple, "back pocket" tools and methods throughout the industry. Thus, I set out to create a program of low- cost, easy process analytics that anyone could implement. These were simple enough for plat- ers to control all the way up to instrumentation that required a chemist but allowed for many more analytical tests each day. Presented at the CCA monthly meeting, with the devices spread out over several tables, everyone could exam- ine these techniques and look at the costs and how to use them. Some of the techniques are not easy to find, such as the use of Clinistix that you can buy at any pharmacy that they use to check babies for phenylketonuria (PKU). These little plastic Happy's DIY Solution to Chemical Control

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