Before the widespread application of PCB technology, producing such an electronic device was so troublesome and inefficient. A large number of electronic tubes required manual wiring and soldering between devices using wires coated with insulating resin, which brought some problems:

Manual wiring has low efficiency and cannot achieve large-scale mechanized production

Manual wiring is prone to installation errors and difficult to check

The welding reliability of the terminal is low, and it is easy to loosen, resulting in poor contact

In order to simplify the production of electronic machines, reduce wiring between electronic components, lower production costs, and improve the reliability of electronic machines, people have begun to study the method of replacing wiring with printing to achieve precision large-scale production using machines.

The birth and development of printed circuit boards

After Faraday published the law of electromagnetic induction in 1831, people began to study how to use electromagnetic principles to achieve long-distance communication. Samuel Morse invented the telegraph in 1837, and Bell obtained the invention patent for the telephone in 1876. By 1904, there were 3 million telephones in the United States that required manual telephone exchange connections.

Printed circuit boards have also evolved with the development of electronic connection systems to solve the connection problems of telegraph/telephone systems. Initially, metal bars or rods were used to connect large electronic components installed on wooden bases. Over time, metal bars have been replaced by screw terminals and cables that can be screwed into them, making the connection more flexible, while wooden bases have been replaced by metal baseplates. However, with the development of telegraph/telephone services, the number of telephone exchange gates has increased, and the electronic operations related to telephone systems have become increasingly complex, requiring smaller and more compact designs.

The Cradle Period of Printed Circuit Boards

The earliest time point for invention patents related to PCB should be in 1903, when a famous German inventor named Albert Hanson applied for a British patent. He pioneered the use of the concept of "circuit" in telephone exchange systems, cutting metal foil into circuit conductors, and then sticking wax paper on the top and bottom of the circuit conductors. Through holes were set at the intersection of the circuit to achieve electrical interconnection between different layers. This is clearly different from our modern PCB manufacturing methods, as phenol resin had not yet been invented and chemical etching technology was not yet mature. Albert Hansen's method can be said to be the prototype of modern PCB manufacturing.

In 1907, American chemist Leo Hendrik Baekeland (1863-1944), born in Belgium, improved the production technology of phenolic resin, making it practical and industrialized. This also created necessary conditions for the emergence and development of printed circuit boards.

In the 1920s, early PCB boards were almost ubiquitous, ranging from bakelite (also known as phenolic resin, commonly known as bakelite) and turquoise to ordinary old thin wooden boards. You can drill some holes in the material and then rivet the flat copper wire onto it. The appearance may not look very beautiful, but the concept of printed circuit boards was born from here. At that time, these circuit boards were mainly used for radios and phonographs.

The Invention of Printed Circuit Board

Do you still remember Hertz mentioned above? After Hertz confirmed Maxwell's prediction about electromagnetic waves through experiments in 1887, by the 1920s, radio had attracted worldwide attention, and electronic tube technology had become quite mature, mature enough to start wireless broadcasting. Broadcast radios would soon be introduced to every household, and how to quickly manufacture radios was also promoting the evolution of circuit board related technologies.

In 1925, Charles Ducas of the United States printed circuit patterns on insulated substrates and successfully established conductors for wiring through electroplating. At this point, the term 'PCB' was born. This method makes it easy to manufacture electrical appliances.