PCB board basic knowledge explanation

PCB board basics

PCB (Printed Circuit Board), the Chinese name is printed circuit board, referred to as printed board, is one of the important components of the electronics industry.

Almost every electronic device, ranging from electronic watches and calculators to computers, communication electronic equipment, and military weapon systems, only has electronic components such as integrated circuits. For the electrical interconnection between them, printed boards are used . In the development of larger electronic products, the most fundamental success factor is the design, documentation and manufacturing of the product's printed boards. The design and manufacturing quality of printed boards directly affect the quality and cost of the entire product, and even lead to the success or failure of business competition.

Printed circuits provide the following functions in electronic devices:

Provide mechanical support for fixing and assembling various electronic components such as integrated circuits. Achieve wiring and electrical connection or electrical insulation between various electronic components such as integrated circuits. Provide the required electrical characteristics, such as characteristic impedance, etc. Provide solder mask graphics for automatic soldering, and identification characters and graphics for component insertion, inspection, and maintenance.

1. Via-connection channel of double-layer board

This was the most confusing part before. When you get a PCB, you will find that there are many small holes as big as pinheads. These are vias, and their structure is as follows.

The main function of the via hole is to connect the copper wires on the front and back boards. Most of the via holes are the red areas in the picture. When the front wires are not well arranged due to interlacing, vias can be used. Just like an "overpass", the two-dimensional plane wiring is transformed into a three-dimensional space. The vias in the blue area are mainly used to connect the copper plates on the front and back sides to achieve the "common ground" effect.

The picture below clearly shows the structure of the via. The copper in the hole is generally obtained by electrolytic restoration.

2. Soldering pad-can actually be used to identify positive and negative poles

The pads are used for soldering component pins. Its size is larger than the via hole. What’s interesting is that the soldering pads are not only round in shape, but also square in shape. Generally, the square pads represent high-voltage pins (I have never paid attention to this detail before)

Another small detail in the picture above is that some of the circular pads are cross-shaped, which connects the pins directly to ground. The ground on the PCB board is actually connected to the negative pole, and the large-area copper plates are connected to the negative pole of the power supply. This ensures that all GND pins are connected to the same ground.

3. Commonly used electronic components

• The most commonly used resistors are not shown in pictures. Nowadays, chip resistors are mainly used, and there are very few in-line resistors.

• Crystal oscillator - the heart of the circuit board, the number above represents the frequency

• Capacitors are available in black cylindrical shapes and flat shapes.

• Digital tube, of course now many people use the display screen directly

• buzzer

• Four-pin switch - pins of the same color in the picture are connected.

4. PCB packaging

The so-called PCB packaging is to express various parameters of real electronic components and chips (such as component size, length and width, pin spacing, etc.) in the form of pictures so that they can be called when drawing PCB drawings.

PCB packaging is divided according to the installation method, which can be divided into patch devices, plug-in devices, and special devices (sunken board devices)

5. Silk screen - let’s engrave your name

After designing a PCB, and finally having my name and studio logo on the finished product, I feel so satisfied. Of course, the main function of silk screen printing is to represent the corresponding component numbers. After the PCB is designed, you can print it out on a piece of A4 paper and put the components on it to see if there are any obstructions and whether the font size is appropriate. Common signs include:

• R(resistance)resistance

• U(unit) unit module/integrated circuit

• C (capacitance) capacitance

• Q tertiary tube

• X crystal oscillator

6. Conclusion

Personally, I think that everyone who uses PCB should learn about PCB manufacturing, including circuit design, AltiumDesign/Protel, soldering circuit boards, etc. Maybe you will never need to make a circuit board yourself, but having this knowledge will help you become familiar with the circuit board faster and prepare you for writing programs.