Interesting knowledge about PCB

 There is no doubt that the printed circuit board (PCB) is a milestone tool in human technology. Why? Because it's hidden in every electronic device these days. Just like other great inventions in history, PCB has gradually matured with the progress of the wheel of history. It has a history of 130 years of development, and it is the most beautiful scenery in the wheel of the industrial revolution.

PCB has become a means of optimizing the production process of electronic equipment. Those electronic equipment that used to be hand-made had to be replaced by PCB, because more functions will be integrated on the circuit board.

Here are ten interesting facts about PCBs.

Color

Even for some people who don't know what a PCB is for, they generally know what a PCB looks like. They at least look like they have one traditional touch, and that's it's green color. This green is actually the light-transmitting color of the solder mask glass paint. Although the name of the solder mask is solder mask, its main function is to protect the covered lines from moisture and dust.

As for why the solder mask layer is green, the main reason is that green is the military protection standard. The solder mask layer was first used in military equipment to protect the reliability of the circuit in the field. Green is the natural protective color in the army. Some people think that the color of the epoxy resin used in the original solder resist paint itself is green, so it has been used to this day.

Now the color of the solder mask is various, such as black, red, yellow and so on. After all, green is not an industry standard.

Who first invented the PCB

If you ask who invented printing, this honor should go to Bi Sheng during the Northern Song Dynasty in China. But the earliest printed circuit boards need to be traced back to Austrian engineer Charles Ducas in 1920 who came up with the concept of using ink to conduct electricity (printing brass wires on the bottom plate). He used electroplating technology to directly generate wires on the surface of the insulator, and made a prototype of the PCB.

The metal wires on the original circuit boards were brass, an alloy of copper and zinc. This disruptive invention eliminates the complex wiring process of electronic circuits and ensures the reliability of circuit performance. This process did not enter the practical application stage until the end of World War II.

Mark

There is also a lot of white markings on the green board. For many years, people wondered why these white printed marks were called "silk screen layers". They are mainly used to identify the information of components on the circuit board, as well as other content related to the circuit board.

The information was first printed on the circuit board by screen printing, so it is called the screen layer, and now it is done using a special inkjet printer. This information can help circuit engineers to check for faults in the board.

Components

The function of the circuit board is mainly completed by effectively connecting the components according to the schematic diagram. Each component has its unique function. Even two devices that are in close proximity on a board can be very different. The types of devices basically include resistors, diodes, transistors, capacitors, relays, batteries, transformers, and others (such as fuses, inductors, potentiometers, etc.).

Everywhere

It is no exaggeration to say that PCBs are everywhere. From computers to digital clocks, from microwave ovens to televisions and stereo systems. As long as it is an electronic item and device, there is a probability of more than 99% that it contains a PCB. So we might take it for granted that any electronic device would not be able to function without a PCB.

NASA

Some ground-breaking technologies have been used in many projects of the National Aeronautics and Space Administration (NASA). Among them, in the 1960s, NASA used PCBs on the Apollo 11 rocket, because PCB-based electronics The equipment is light in weight and low in power consumption. That was the greatest moment of mankind, sending astronauts to the moon for the first time. Among them is the credit of the PCB.

Surface mount technology (SMT)

Surface mount soldering technology has brought PCBs into the modern age. Compared with the previous socket installation method, this surface mount soldering technology first uses special glue to paste the device on the PCB, and then electrically connects the device to the circuit board through special reflow soldering.

Rapid Prototyping PCB

Breadboards, perfboards, and other general-purpose circuit boards can be used for testing during partial experimentation with circuits. With the increase of surface-mounted components, there are also new rapid PCB prototyping technologies, such as thermal transfer PCBs, 3D printed multilayer circuit boards, etc.

Flexible PCB

PCBs are not all straight and hard, and there are many soft PCBs that work in many compact electronic devices. They often constitute application circuits in many movable joints, or form multi-layer three-dimensional circuits.

The world's largest PCB

The world's largest PCB comes from the flexible multilayer circuit board used in unmanned solar aircraft by Johnson Electronics of the United Kingdom. It is about 28 meters long. The circuit board made of soft polyimide has better heat dissipation and higher conductivity density. Such a long circuit board is produced by corrosion in sections through a special production process. Longest flex circuit board.

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