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Printed circuit board

technology Maturity 9-11 Next article →

A printed circuit board, or PCB, is a fundamental component in modern electronics.

SEG DVD 430 - Printed circuit board-4276
SEG DVD 430 - Printed circuit board-4276

It is a laminated sandwich structure made of conductive and insulating layers. These layers contain patterns of traces, which are conductive paths that act like flat wires on a surface. PCBs serve to connect or "wire" various electronic components to one another within a circuit. Without this technology, the compact and powerful devices we use every day would not be possible.

Mouse printed circuit board both sides IMG 0959a
Mouse printed circuit board both sides IMG 0959a

The manufacturing process of a PCB relies on a method called chemical etching. First, a pattern known as the "artwork" is prepared. A material called photoresist is coated onto the board. This resist is then exposed to light through the artwork pattern. The light-sensitive material protects specific areas of the copper from being dissolved. Next, the board is placed in an etching solution. This solution washes away the unprotected copper, leaving behind precise tracks, pads, and vias.

Hand Etched PCB
Hand Etched PCB

To prevent errors, a coating called solder mask is applied. This solder resist protects the copper from corrosion and prevents electrical shorts between traces.

There are several distinct types of PCB constructions based on their complexity. A single-sided PCB contains only one layer of copper. A double-sided PCB has two copper layers on both sides of a single substrate. Multi-layer PCBs consist of stacked substrate layers with copper plating sandwiched between them.

PCB Spectrum
PCB Spectrum

These multi-layer boards allow for much higher component density. This is because circuit traces can reside on inner layers rather than taking up surface space. To connect these different layers, manufacturers add vias. Vias are metal-lined drilled holes that enable electrical interconnections between conductive layers.

Before the PCB, engineers used point-to-point construction on a chassis. This chassis was often a heavy metal or wooden frame. Components were attached to the frame and connected using loose jumper wires or soldering. These older circuits were bulky, heavy, and quite fragile. The journey toward modern PCBs began in the early 20th century. In 1903, Albert Hanson described multi-layer foil conductors on insulating boards. In 1936, the Austrian engineer Paul Eisler invented the printed circuit while working in the UK.

MK53 fuze
MK53 fuze

By 1943, the United States used this technology on a large scale for proximity fuzes during World War II.

The transition to mass production involved many key developments. In 1948, the United States released the invention for commercial use. The Auto-Sembly process, developed by the US Army in 1949, allowed component leads to be dip soldered. This helped printed circuits become common in consumer electronics by the mid-1950s. Motorola was an early leader, investing $1 million to adopt "plated circuits" in home radios by 1952.

Mark-53-proximity-fuze-1943
Mark-53-proximity-fuze-1943

In the 1980s, surface-mount technology began replacing through-hole construction. This shift allowed for even smaller boards and lower production costs, though it made repairs more difficult.

The economic scale of this industry is massive. In 2014, the world market for bare PCBs exceeded US$60.2 billion. By 2024, the market was estimated at $80.33 billion. It is forecast to reach $96.57 billion by 2029, growing at 4.87% per year.

Breakout board
Breakout board

This growth is driven by the constant need for smaller and more efficient electronics. High-Density Interconnect (HDI) technology is a major part of this modern trend. HDI uses microvias to create much denser designs. A 4-layer HDI board can match the quality of an 8-layer through-hole board, which helps reduce costs.

Today, PCB technology connects to many advanced fields of science and engineering. HDI technology is essential for computer components, mobile phones, and medical equipment.

Surface Mount Components
Surface Mount Components

Recent advances in 3D printing have even introduced 3D printed electronics. This allows items to be printed layer by layer using liquid ink with electronic functions. Some modern PCBs even incorporate optical waveguides, which are similar to optical fibers. As technology advances, the printed circuit board remains the essential foundation for almost every electronic system in existence.

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🖼️ Images & Media (13)
File:SEG DVD 430 - Printed circuit board-4276.jpg
SEG DVD 430 - Printed circuit board-4276.jpg
File:PCB Spectrum.jpg
PCB Spectrum.jpg
File:Mark-53-proximity-fuze-1943.jpg
Mark-53-proximity-fuze-1943.jpg
File:Hand Etched PCB.png
Hand Etched PCB.png
File:Resistors (1).jpg
Resistors (1).jpg
File:MOS6581 chtaube061229.jpg
MOS6581 chtaube061229.jpg
File:Box of 02in pcb bits.jpg
Box of 02in pcb bits.jpg
File:Surface Mount Components.jpg
Surface Mount Components.jpg
File:Mouse printed circuit board both sides IMG 0959a.JPG
Mouse printed circuit board both sides...
File:Breakout board.jpg
Breakout board.jpg
File:SD Card Breakout Board.jpg
SD Card Breakout Board.jpg
File:Cordwoodcircuit.agr.jpg
Cordwoodcircuit.agr.jpg

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