The Story of the PCB: The Little Green Thing That Makes Electronics Work

By electronics / March 22, 2026

Difficulty: Beginner — Crack open any electronic device — your phone, your TV remote, your car’s dashboard — and you’ll find a green (or sometimes blue, red, or black) board covered in tiny components connected by copper traces. That’s a printed circuit board, or PCB, and it’s arguably the most important invention in the history of electronics that nobody talks about.

Before PCBs: The Wiring Nightmare

In the early days of electronics, every component was connected by individual wires, hand-soldered to metal chassis or terminal strips. If you’ve ever seen the inside of a 1940s radio, it looks like a rat’s nest of wires running in every direction. This point-to-point wiring was slow to assemble, prone to failures (one loose wire and the whole thing stopped working), and nearly impossible to mass-produce.

As electronics got more complex — particularly during World War II, when radar systems and proximity fuses required hundreds of components — the wiring problem became critical. Military devices needed to be reliable, reproducible, and assembled by workers who weren’t necessarily electronics experts. Something had to change.

Paul Eisler’s Revolutionary Idea

Enter Paul Eisler, an Austrian engineer who fled to England in 1936 to escape the Nazis. Eisler had a radical idea: instead of connecting components with individual wires, why not print the connections directly onto a flat board?

Working with almost no resources — he was essentially a refugee with a workshop — Eisler developed a method of etching copper patterns onto an insulating board. The copper traces replaced wires, and components could be soldered directly to the board at predetermined locations. He patented the process in 1943.

The British military initially ignored Eisler’s invention. It was the Americans who recognized its potential, using printed circuits in proximity fuses for anti-aircraft shells during WWII. After the war, the technology was declassified and rapidly adopted by the electronics industry.

How Modern PCBs Are Made

Today’s PCB manufacturing process would astonish Eisler. Modern boards start as sheets of fiberglass (FR-4) laminated with thin copper foil. The process goes roughly like this:

• Design — engineers lay out the circuit using software like KiCad, Eagle, or Altium. Every component placement and every trace route is planned on screen.
• Photolithography — the design is transferred to the copper using UV light and a chemical photoresist, similar to how semiconductor chips are made
• Etching — unwanted copper is dissolved away in an acid bath, leaving only the designed traces
• Drilling — holes for through-hole components and vias (connections between layers) are drilled with precision CNC machines
• Plating and solder mask — the characteristic green (or other color) coating is applied, leaving only the solder pads exposed
• Silkscreen — component labels and reference designators are printed on top

Multi-layer boards sandwich multiple copper layers together — your smartphone’s main board might have 10 or more layers, with traces running in different directions on each layer and connected by tiny plated holes called vias.

Why PCBs Changed Everything

PCBs solved almost every problem with point-to-point wiring:

• Reproducibility — every board from a production run is identical. No more variation from one hand-wired unit to the next.
• Reliability — soldered connections on a PCB are far more durable than hand-wrapped wires
• Miniaturization — traces can be fractions of a millimeter wide, enabling the dense component packing that makes modern electronics possible
• Automation — pick-and-place machines can populate a PCB with thousands of components per hour
• Cost — at scale, PCBs cost pennies per unit

Without PCBs, there would be no smartphones, no laptops, no modern cars, no internet infrastructure. The capacitors, transistors, and ICs that power our world need something to connect them — and that something is the PCB.

PCBs for Hobbyists

The incredible thing about PCBs today is that anyone can design and order them. Services like JLCPCB, PCBWay, and OSH Park will manufacture your custom PCB design for as little as $2 for five boards. The turnaround is typically 5-7 days.

If you’ve been building projects on breadboards, designing a PCB is the natural next step. Your project becomes permanent, professional-looking, and far more reliable. Free design software like KiCad makes it accessible to anyone willing to learn.

Many of the communication protocols you use with Arduino (I2C, SPI, UART) are designed with PCB trace characteristics in mind — signal integrity, impedance matching, and proper grounding all matter more on a PCB than on a breadboard.

Paul Eisler died in 1992, having lived to see his invention become the backbone of a trillion-dollar industry. Every time you pick up a phone, start a car, or flip on a light switch, you’re using his idea — connections printed on a board instead of wired by hand.

Recommended Tools & Parts

Get started with PCB design and prototyping (affiliate links):

• PCB Prototyping Board Assortment
• PCB Etching Kit
• Soldering Iron Station Kit
• Solder Wire (Rosin Core)
• Digital Multimeter