The History of Printed Circuit Boards
Responsible for the function of medical devices, aeronautical engineering applications, military hardware, and hundreds of other electronics, the printed circuit board is one of the most important inventions of the 20th century.
But many don’t know that its fascinating origin story is even greater than its vital importance in just about every industry on the planet. With a storied history that includes everything from early pioneers and wartime ingenuity to modern-day miniaturization, it’s safe to say that PCBs have come a long way since their beginnings in the early 1900s.
The Foundations of PCBs Are Created: 1925–1941
Printed circuit board history begins with the 1927 patent of Charles Ducas, who filed for his “Printed Circuit for Electrical Apparatus and Method of Manufacturing the Same.” This archaic PCB design used print wires on an electrical board with conductive ink acting as a connection between them.
It would be nearly a decade until this design was revisited and improved upon by Paul Eisler. Eisler created an innovative, more efficient circuit board design that replaced hand-soldered wires with printed pathways. This design not only saved time and money but also improved the reliability of connections.
After escaping Austria during the Second World War, Eisler found himself in a British prison through a series of unfortunate events. After being released, he was recruited by the British government to work on top-secret projects, one of which included using his PCB design for military purposes.
With the British government funding his research, Eisler optimized his design, paving the way for pioneers to continue his work and build upon his legacy in the years to come.
Government Development of PCBs: 1943–1947
By 1943, the US government had taken quite an interest in the potential wartime applications of PCBs. They were particularly eager to use this new technology in:
- Proximity fuses
- Anti-aircraft shells
- Communication equipment
While some sources claim the British Ministry of Defense was reluctant to share Eisler’s design with the Americans, they eventually agreed to lend a hand in furthering the development of this critical technology.
For the next few years and with the help of British intelligence, the US Government worked to improve upon Eisler’s design in secret. With both governments now working to harness the power of the PCB, it wouldn’t be long before this technology was ready for the commercial market.
Reaching Consumers: 1948–1970
By 1948, the United States government was feeling confident in their work on PCB technology but craved faster development of the perfect PCB design. So, they declassified the technology and released it to the public, encouraging private businesses to help with the refinement of the technology.
And, boy, did businesses answer the call.
By 1950, major advancements were made in the manufacturing process of printed circuit boards. These advancements included the development of:
- Smaller and more reliable components
- Automated machines for drilling and cutting
- New methods of circuit board patterning
With the help of these advancements, the commercial market for PCBs rapidly expanded throughout the 1950s, creating smaller transistors, diodes, and other components. This, in turn, allowed for the development of smaller and more portable electronics, like the first pocket radios.
The 1960s saw even more advances in printed circuit board manufacturing with the introduction of new materials like FR-4 glass epoxy, which replaced less reliable PCB substrates such as Bakelite. With the FR-4 substrate, circuits could now be printed on both sides of the board, further increasing the efficiency of PCBs.
The 1970s also brought forth the development of the integrated circuit. By combining numerous transistors and other components onto a single chip, businesses could now create incredibly small and powerful electronic devices.
The PCB craze took every industry by storm until the 1970s, when the history of PCB was met with its first significant setback. With its abbreviation matching a toxic substance called polychlorinated biphenyl, PCB was temporarily rebranded to PWB (printed wire boards) in an attempt to salvage its public image and distance it from the toxic chemical.
Fortunately, polychlorinated biphenyl was banned shortly after being released, and the PCB name was picked up once again. Today, both PCB and PWB are used interchangeably.
Advancements in PCB Technology: 1970–1990
With the decade starting off on a bit of a sour note, the 1970s ended up being a time of great advancement for printed circuit boards. In fact, it was during this time that many of the PCB processes and methods we use today were developed, including:
- The introduction of computer-aided design (CAD), which provided greater precision in board design and layout
- The development of multilayer boards, which provided the ability to handle more complex circuitry
- The perfection of surface-mount devices, which allowed for smaller, more efficient components
But out of the many other advancements made in PCB technology during the 1970s and 1980s, surface-mount technology (SMT) had the most significant impact on the future of electronics.
Surface-mount technology allowed components to be placed directly onto the PCB rather than through unnecessary holes. This resulted in a much denser circuitry and an even smaller end product.
PCB Today: 2000s to Present Day
In the Digital Age, PCB technology can be found in almost every electronic device imaginable. From the device you’re reading this on to the streetlights outside your home, almost everything contains a printed circuit board.
This demand for PCBs has seen the rise of many new businesses as well as the refinement of existing methods and technologies. Advancements in the 21st century include:
- Flexible and stretchable PCBs, which are used in wearable electronics
- Rigid-flex boards, which offer a combination of flexibility and durability
- High-density interconnect boards, which add more circuitry in a smaller space
As technology continues to evolve, so too will the PCB. But one thing is sure — the history of the printed circuit board hasn’t seen its end. With the innovations like the Internet of Things (IoT), 5G technology, and advanced artificial intelligence on the horizon, we can only imagine what new PCBs will be capable of in the years to come.
If you are interested in being part of PCB history with your own electronic invention, learn more about surface-mount technology and how to get started with PCB design and layout.