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JULY 2024 I PCB007 MAGAZINE 75 ity, pH, and chloride levels. For longer peri- ods between running, it would be wise to con- sider putting the etchant back into the original drums and sealing them tight. Final Tip Alkaline etchant is notoriously hard on pH probes. Its viscosity is so low that it will inevi- tably backflow into the probe. When this starts happening, it is best to recalibrate the probe before the first run of the day at a minimum and, even better, twice per shi. PCB007 Don Ball is a process engineer at Chemcut. To read past columns or contact Ball, click here. Prepping for More If you've finished one lot but plan to do oth- ers that day, leave the heat on, but shut off all sprays, including water rinses and the dryer if the system has one. Close the vent valves to minimize ammonia loss. e butterfly valves provided by most equipment suppliers for venting do not close 100% so there will still be enough vent to control fumes if the spray is off. When you are done for the day but plan to run the next day, follow the same procedure as above but turn off the heat. Also, remove the pH probe and put it into some 6M KCl storage solution overnight. It's probably okay to leave the etchant in the etcher for up to a week if the venting is com- pletely closed or shut off and the solution is up to specifications in terms of the specific grav- Chapter 3: Introduction to PCB Manufacturing PCB manufacturing combines mechanical func- tions like drill and rout, chemical processes such as electroplating and copper etch- ing, and hybrid processes like lamination that use both chem- ical and mechanical produc- tion methods. These processes are arranged to convert the raw materials and your CAD design into a fully functional circuit board that will transmit electrical signals as designed. This chapter will lay out the pro- duction process at a high level. The first step in PCB produc- tion should be to check the board design requirements and print notes before submitting a request for quote (RFQ) or online order. A thorough double-check of your order form will ensure that the right specifications—such as pan- elization method, finish type, and solder mask color—are quoted properly. Any extraneous infor- mation provided at this stage could lead to con- fusion, delays, or extra costs in the quote. If your prototype doesn't need all of the specifications on the prints, do not provide them. Best practice is to only provide what is needed for the build at hand. From there, it's critical for the designer to confirm that the quote or order form specs are aligned with the design. It would be great if the manufac- turer could read minds, but all they can read is the order form and the information provided in the files. The manufacturer will build to the specifications on the order, so if they are not accurate, the board might not be manufac- tured as the designer intended. If a manufacturer offers a CAD tool with DFM rule check module, it would be wise to use it. This will help avoid tooling holds and pro- duction delays. Continue reading... BOOK EXCERPT: The Printed Circuit Designer's Guide to... Designing for Reality