Why Are Printed Circuit Boards Green and Other Facts About the Manufacturing and Repair of PCBs
Printed circuit boards have become ubiquitous. They are literally just about everywhere from the cheapest little toys to the latest DOD weapon system. Case in point: tear open one of those cute but annoying musical greeting cards and what do you find at its heart? A tiny electronic circuit.
We like to think of circuit boards as being a very modern invention, but in reality they are anything but. He might have ridden a horse to the laboratory, but in 1903 German inventor Albert Hanson was already describing flat foil conductors laminated to an insulating board. A year later in 1904 Thomas Edison was experimenting with chemical methods of plating conductors onto linen paper. By 1927 Charles Durcase had patented a method of electroplating circuit patterns and we were well on our way to the modern printed circuit board.
Fast Facts About Printed Circuit Boards
- PCBs became common in the mid-1950s after the Auto-Sembly process was developed by the United States Army
- Most printed circuit boards are green primarily because many are made from a glass-epoxy which is naturally green. Early boards made of Bakelite were brownish. Ultimately, however, the finishing color of a board is usually a solder mask applied to the board and could be any color.
- PWB – printed wiring board – the correct term for a board with only copper tracks and features and no circuit elements such as capacitors or resistors
- Typical PCB materials include: conductive ink; BT-epoxy; composite epoxy material CEM-1,5; cyanate ester; FR-2; FR-4 (the most common PCB material); polyimide; and PTFE (Teflon).
- PCA – a PCB populated with electronic components is called a printed circuit assembly (PCA)
- CT Scans – You aren’t the only one getting CT Scans; industrial CT scanning is used for board testing and can generate a 3D rendering of the board along with 2D image slices showing details such as soldered paths and connections.
- PCBs intended for extreme environments have conformal coatings applied by dipping or spraying after the components have been soldered. Although this protects the board from corrosion and leakage or shorting from condensation, it also makes circuit board repairs extremely difficult or impossible.
- Static electricity can damage components on PCBs and today’s traces have become so fine that it is possible to blow an etch off the board with a static charge so remember to use antistatic bags during transport.
- Before the advent of Integrated Circuits, “cordwood” construction was used in electronics where space was at a premium such as in missile guidance systems.
- Surface mount technology emerged in the 1960s but didn’t become popular until the 1980s lending itself to automation resulting in reduced labor costs and increased production rates.
- Today rigid PCBs are being replaced by flexible circuit boards or combinations of rigid and flexible pcbs.
We are surrounded by and dependent on a great number of these circuit boards whether in our homes, our cars, or our workplaces. They are workhorses to be sure, but they are also fairly sensitive to age, abuse, and environmental conditions. The more costly the board, the more sense it makes to repair rather than replace.
If your damaged circuit board is still under warranty, you should contact the OEM to get repair or replacement. If it is no longer under warranty, look for an experienced third-party industrial electronic repair shop that offers no-cost evaluations, good customer service, and a good warranty.
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