Printed Circuit Board Design Tools

Photo tour: how a printed circuit board is made

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Integrated circuits — computer chips — with their micron-scale transistors, gigahertz operating speeds, and buses capable of transferring hundreds of gigabytes per second, are rather wondrous. They're immensely complex — the pinnacle of human engineering — and no one except bespectacled bigwigs at Intel or AMD even pretend to know how they work.

Integrated circuits would be meaningless, however, without the printed circuit board (PCB). If integrated circuits are the brains of computers, PCBs are the skeleton, nervous system, and lifeblood of our silicon age. Not much is said about the PCB, though. They grow in complexity to match the demands of computer chips — and the advanced engineering of a PCB truly is something to behold — but it is a rare sight indeed to see a headline heralding an advance in the realm of those friendly, green bits of plastic-and-copper that can be found in almost every electronic device on Earth.

pcb dunking But this is ExtremeTech, and while macro photos of Intel's latest 50-core processor are fantastically beautiful, we think that PCBs deserve a bit more attention — which leads us neatly onto Base2, a company that sells components to electronic engineering students and tinkerers. Base2 asked the manufacturer of its PCBs, Advanced Circuits, if it could tour its circuit printing plant. Advanced Circuits consented — but more importantly, it allowed the folks at Base2 to take photos.

The process of making PCBs is far more complex and awesome than you would first imagine, and involves the application of layer upon layer of copper, tin, polymer, resin, aluminium, and solder, all interspersed with bath dunks to remove coatings from unwanted areas. The photo tour also demonstrates why they are called printed circuit boards: many of the stages involve printing masks that are then used to create the copper paths, the dielectric, and solder mask — and once the PCB is structurally complete, any text or legends are silk-screened onto the board using "basically a gigantic inkjet printer."

flying probe testing of PCB Finally, there are even two tools that can be used to automatically test PCBs: an automated optical inspection unit, which compares the finished product against the original CAD design, and a flying probe machine, which electrically tests each of the copper channels on the board.