PCBA Tech - ​Secret knowledge of PCB and equipment knowledge of FPC

1. There are unknown places on the circuit board

1. Capacitance

Capacitors are set up by distributing the voltage of each place on the circuit board. There are generally about 10. The brand is generally Samsung. It is divided into three types: solid, semi-solid, and liquid. The volume is small, and the common ones are cylindrical and elliptical. Type two. According to different circuit boards, there are different capacitors, such as computers. Its main distribution is as follows: electrolytic capacitors, solid capacitors, and ceramic capacitors.

2. Field effect tube

It is a kind of DC semiconductor electron tube, usually in the shape of a square, black super hard material, about the size of a thumb. It usually responds to voltage output, stabilizes the voltage direction, and reduces noise.

3. SMD crystal oscillator

This is also a square, but with special markings, such as the four corners of different colors, can provide high-precision oscillation.

4. Chip resistors

It is also a kind of capacitor, but it looks different. It is a kind of ceramic capacitor. It has a relatively large volume and is not on the periphery of the circuit board.

2. Equipment knowledge of FPC circuit board

Printed circuit board (PCB) will appear in almost every electronic device. If there are electronic parts in a certain device, they are all mounted on PCBs of different sizes. In addition to fixing various small parts, the main function of the PCB is to provide electrical connections between the upper parts. As electronic devices become more and more complex, more and more parts are needed, and the circuits and parts on the PCB are becoming more and more dense. The standard PCB looks like this. The bare board (no parts on it) is often called "PrintedWiringBoard (PWB)".

For more information, please click "What are the characteristics of flexible FPC circuit boards you know? 》

In order to fix the parts on the PCB, we solder their pins directly on the wiring. On the most basic PCB (single panel), the parts are concentrated on one side, and the wires are concentrated on the other side. In this case, we need to make holes in the board so that the pins can pass through the board to the other side, so the pins of the parts are soldered to the other side. Because of this, the front and back sides of the PCB are called Component Side and Solder Side respectively.

If there are some parts on the PCB that need to be removed or installed back after the production is completed, then the socket (Socket) will be used when the part is installed. Since the socket is directly welded to the board, the parts can be disassembled and assembled at will. Seen below is the ZIF (Zero Insertion Force) socket, which allows the parts (here refers to the CPU) to be easily inserted into the socket or removed. The fixing rod next to the socket can be fixed after you insert the part.

If you want to connect two PCBs to each other, we generally use an edge connector commonly known as "golden finger". There are many exposed copper pads on the golden fingers, which are actually part of the PCB wiring. Usually, when connecting, we insert the golden fingers on one PCB into the appropriate slot on the other PCB (generally called the expansion slot Slot). In computers, display cards, sound cards, or other similar interface cards are connected to the motherboard by golden fingers.