PCB(Printed Circuit Board) is no longer strange to us, which is a core part of electronic devices such as cellphones, computers, radios, and lights. Without the development of PCB, there would be no way that we could enjoy the convenience brought from these electronic devices. Then, a question comes to my mind: What is the development history of PCB? Well, let’s discuss it in this article.

Milestones in the Development Process of PCB History

We can learn the PCB development process by dividing it into several vital stages which are listed below：

Budding Stage(1900s-1920s):

In 1903, a famous German inventor named Albert Hanson applied for a British patent, and he pioneered the concept of using “wires” used in the telephone exchange systems, the metal foil is used to cut line conductors, and then paraffin paper is glued on the top and bottom of the line conductors, and via holes are set at the line intersections to realize the electrical interconnection between different layers. This is different from our modern PCB manufacturing method, because phenol resin has not yet been invented at that time, and the chemical etching technology is not yet mature. The method invented by Albert Hansen can be said to be the prototype of modern PCB manufacturing, which is a base for the following development.

Developing Stage(1920s-1940s):

In 1925, Charles Ducas came from the United States who had an innovative thought to print circuit patterns on a substrate of insulating, and then plating was applied to make conductors for wiring. The term “PCB” emerged at this time. This method makes it easy to manufacture electrical appliances.

In 1936, the Austrian Dr. Paul Eisler, known as “the father of printed circuit”, published foil film technology in the United Kingdom who developed the first printed circuit board for use in a radio set. And the method that Paul Eisler used is very similar to the way that we use for today’s printed circuit boards. This method is called subtraction, it can remove the unnecessary metal parts.

Around 1943, Paul Eisler’s technical invention was used on a large scale by the United States to make proximity fuzes for use in World War II. At the same time, the technology is widely used in military radios.

Turning Point(1948):

The Year 1948 is a turning point in the process of PCB history development, as the United States officially recognized the printed circuit board invention for commercial use. Although there are little electronic equipment using PCB history at that time, this decision promoted the development and application of PCB in a large part.

Flourishing Stage(1950s-1990s):

From the 1950s to the 1990s, the PCB industry was formed and rapidly growing, that is, the early stage of PCB industrialization, at which time PCB has become an industry.
In the 1950s, transistors are used in the electronics market, which helped to reduce the size of electronics effectively and make it much easier to incorporate PCBs, in addition, the electronic reliability was improved significantly.

In 1953, a double-sided board with electroplated vias was developed by Motorola. Around 1955, Toshiba of Japan introduced a technology to generate copper oxide on the surface of copper foil, and copper-clad laminate (CCL) appeared. Thanks to these two technologies, the multi-layer printed circuit boards were invented successfully and have been used on a large scale.
In the 1960s, printed circuit boards were widely used at this time, PCB technology was more and more advanced, and thanks to the wide use of multiple layers printed circuit boards, the ratio of wiring to substrate area was increased efficiently.

In the 1970s, there is a rapid development of multi-layer PCBs, aspiring to higher precision and density, small holes with exquisite lines, high reliability, lower cost, and automatic production. At that period, the PCB design work was still done manually. The PCB Layout engineers used colored pencils and rulers to draw circuits on transparent polyester film. In order to improve drawing efficiency, they made several packaging templates and circuit templates for some common devices.

In the 1980s, surface mounting technology(SMT) began to gradually replace through-hole mounting technology and become the mainstream in that time. It has also entered the digital age.

Mature Stage(1990s-Now):

With the development of electronic devices such as personal computers, CDs, cameras, game consoles, etc., great changes have taken place accordingly. The size of PCBs must be decreased to fit these small electronic devices.

Computerization design achieved automation in many steps in PCB design and made it easier for designs with small and lightweight components. As regards the component suppliers, they need to improve their devices as well by reducing their electrical consumption, but at the same time, they need to consider the cost reduction question.

In the 2000s, PCBs became more complex with more functions while the size became smaller. Especially the multi-layer and flex circuit PCB designs made these electronic devices much more workable and functional, with small size and lower cost PCBs.

Early 21st century, the emergence of smartphones drove the development of HDI PCB technology. While retaining the laser-drilled micro vias, stacked vias began to replace the staggering vias, and combined with “any layer” construction technology, the final line width/line spacing of the HDI board reached 40μm.

This arbitrary layer method is still based on a subtractive process, and it is certain that for mobile electronic products, most high-end HDI still use this technology. However, in 2017, HDI began to enter a new stage of development, beginning to shift from a subtractive process to a process based on pattern plating.