Color for PCB Process Control Some colors are so standardized that changing them serves no purpose and could indeed be contra productive or even dangerous. Change the stop/caution/go lights from red/amber/green to blue/pink /yellow and you will have mass confusion and injury. If invited to a black tie event you would know what to wear, but an event called “paisley tie” . . . maybe not. Printed circuit boards are always green – except when they are not. In the kaizen process to improve manufacturing quality and reduce cost, one of the five S’s is “seiketsu” – devising color schemes so distinct that one knows at a glance an object’s nature or purpose. This could be applied to printed circuit boards by using a colored solder mask to shout out its nature. Internally one could use green to mean lead solder boards – do not run on the RoHS line. Blue means RoHS – set the temperature profile accordingly. Red means prototypes – do not ship to customers without engineering approval. Black means commercial avionics and gold means DoD equipment requiring special documentation. Externally the board color could be standardized to ensure proper electrical connection in the field. Green could mean low voltage, yellow could indicate 120v line voltage, and violet could indicate multi-phase high voltage. Marketing could color code the boards based on market segment, allowing them to trace returns from one country to sales made to other territories or grey markets. Three really nice features of solder mask color coding are 1.) the color could be seen from a distance without having to search for and read a small label, 2.) the color remains for the life of the board and could not be removed, and 3.) there is no cost! Virtually all PCB vendors already stock a variety of colors and to get your business many would color match anything for free, even your boss’s red Ferrari. If you wishto pursue applications for special colored solder masks or other tips to improve your process – phone USTEK Inc. at 614-538-8000, or e-mail firstname.lastname@example.org. We are here to help and support your needs.