The origin and evolution of printed circuit boards

Printed circuit boards are one of the important components of the electronics industry. Almost every electronic device, from electronic watches and calculators to computers, communication electronics, military weapon systems, as long as there are electronic components such as integrated circuits, in order to electrically interconnect them, use printed circuit boards. So, let's talk about the origin and evolution of printed circuit boards today.

The origin of printed circuit boards

Before the appearance of printed circuit board, the interconnection between electronic components depended on the direct connection of wire to form a complete line.

At the beginning of the 20th century, in order to simplify the manufacture of electronic machines, reduce the wiring between electronic components, and reduce the manufacturing cost and so on, people began to study the method of replacing wiring with printing. For thirty years, engineers have been proposing to use metal conductors as wiring on insulated substrates. The most successful was that in 1925, Charles Ducas of the United States printed a circuit pattern on an insulated substrate, and then successfully established a conductor for wiring by electroplating.

Until 1936, the Austrian Paul Eisler invented foil technology in the UK. Paul Eisler is an electrical engineer, he has studied printing technology. when he manufacturing the circuit board, he first draws the electronic circuit diagram according to the plate making method in the printing industry, and then etches the circuit diagram on the insulating board of a layer of copper foil, and the unnecessary copper foil portion is etched away, leaving only the lines, such that the electronic components are connected by a circuit formed by copper foil. Eisler successfully assembled a radio in this way. In Japan, Miyamoto Hiroyuki successfully applied for a patent by the method of spraying the wiring method (No. 119384). The two methods of Paul Eisler is most similar to today's printed circuit boards. This kind of method is called subtraction method, which is to remove unnecessary metal, so we can call Paul Eisler the father of printed circuit boards. The practice of Charles Ducas and Miyamoto Hiroshi is to add only the wiring required, called the additive method. Even so, because the electronic components at that time generated a large amount of heat, the substrates of the two were difficult to use together, so that they were not officially used, but the printed circuit technology was further improved.

The evolution of printed circuit boards

In 1941, the United States painted copper paste on talc for wiring to make a proximity tube.

In 1943, the technology is widely used in military radio by American.

In 1947, epoxy resin start to be used as a substrate board, the NBS began to research on printed circuit technology to form coils, capacitors, resistors and other manufacturing technology.

In 1948, American officially recognized this invent and use for business.

Since the 1950s, transistors with lower heat generation have largely replaced the status of vacuum tubes, and printed circuit board technology has only begun to be widely adopted. At that time, the etched foil technology was the mainstream.

In 1950, in Japan, silver lacquer was used as a wiring on a glass substrate, and copper foil was used as a wiring on a paper phenolic substrate made of a phenol resin.

In 1951, with the arrival of polyimide, the heat resistance of resin make further, also made the polyurethane amide base board.

In 1953, Motorola developed the plated through hole method. This method is also applied to later multilayer boards.

Printed circuit boards were widely used 10 years later in the 1960s, and their technology is becoming more mature. Since the introduction of Motorola's double-side board, multi-layer printed circuit boards have begun to appear, increasing the ratio of wiring to substrate area.

In 1960, V. Dahlgreen applied a circuit-coated metal foil film to a thermoplastic plastic to create a flexible printed circuit board.

In 1961, the United States the Hazeltine Corporation referred the plating through hole method, making the multilayer PCB.

In 1967, has published one of the build-up method——"Plated - up technology".

In 1969, FD-R made flexible printed circuit boards from polyimide.

In 1979, Pactel published one of the build-up method——"Pactel method".

In 1984, NTT developed method of thin film circuit "Polyimide cooper".

In 1988, the Siemens company developed the 'Microwiring Substrate' method for layer-added printed circuit board.

In 1990, IBM developed 'Surface Laminar Circuit, SLC' method for layer-added printed circuit board.

In 1995, Panasonic developed 'ALIVH' method for layer-added printed circuit board.

In 1996, Toshiba developed 'Bit' method for layer-added printed circuit board.