Printed circuit board
PCB is the mechanical foundation in which electronic components can be installed to complete the expected circuit. The PCB itself contains conductive patterns or traces, and a substrate usually made of glass epoxy material. For example, a basic PCB can be divided into 4, 6 or 8 signal layers, of which 4 and 6 layers are the most common. As the name implies, PCB patterns are composed of printed components, printed circuits or a combination of the two. According to the predetermined design, the conductive pattern is printed or engraved on the insulating epoxy glass.
How to use PCB?
PCB can be customized for electronic equipment, such as televisions and radios, mobile phones, cameras and computer components, such as motherboards and graphics cards. PCB is also used to manufacture lighting equipment, medical equipment, automobile industry and most industrial machinery.
PCB is an essential structure in equipment, because it supports electronic components and is used as the electrical connection of components. The unique functions of PCB can be summarized as follows:
High density wiring, light weight and small volume are very suitable for miniaturization of electronic equipment.
Because of the consistency and repeatability of graphics, PBC can save time for equipment maintenance, debugging and inspection.
Its production can be automated to reduce the cost of electronic equipment.
Types of printed circuit boards
The forms of PCBs are as follows:
1. Single layer printed circuit board
Also known as single-sided PCB, it is the simplest and most commonly used PCB in most electronic devices because it is easy to design and produce. A single-layer PCB is coated with a conductive material, usually copper. Solder mask is used to protect PCB from oxidation. PCB components are screen printed. This type of PCB is used in low-cost but mass-produced applications such as printers, radios and calculators.
2. Double-layer printed circuit board
This kind of PCB, also known as double-sided PCB, has a layer of conductive material, usually copper, on the top and bottom of the circuit board. Compared with single-sided PCB, the main advantages of this PCB are improved flexibility, reduced size and compact circuit. It is commonly used in industrial control, UPS systems, converters, telephones, power monitoring units, amplifiers and HVAC applications.
3. Multilayer printed circuit board
This type of PCB has more than two copper conductive layers. The circuit board is fixed by inserting glue between insulating layers to ensure that the circuit will not be damaged by overheating. It is used in complex applications, such as satellite system, GPS technology, file server, data storage equipment and medical equipment.
Other types of PCB include flexible PCB, rigid PCB and flexible rigid PCB.
PCBA printed circuit board assembly
The abbreviation of printed circuit board+components, PCBA is the whole process of making unfilled PCB through PTH and SMT processes. These processes can place and solder all electronic components on a blank PCB, including solder paste printing, component installation, manual, wave soldering or reflow soldering and various forms of QC inspection.
Components of PCBA
In the assembly process, an empty PCB board is filled with electronic components to form a functional printed circuit assembly (PCA) or PCBA. Using through-hole technology, electronic components are mounted in holes surrounded by conductive pads. When using SMT, the components are placed on the PCB to ensure that the pins are aligned with the conductive pads. When electronic components are fixed on either side of the circuit board, the components on one side of the circuit board must be bonded to the circuit board before soldering.
You can use one of the following methods to test the filled PCBA board:
After the power supply is turned off, the circuit board can be inspected visually or using automatic optical inspection tools.
After the power is turned off, analog signal analysis can be performed. This analysis is called "power failure test".
After power-on, conduct online test.
Finally, functional tests can be carried out to determine whether the PCB is carried out according to the design purpose.
From the above description, we can determine whether PCBA refers to the processing flow or the whole circuit board, while PCB refers to an empty printed circuit board without electronic components. Usually, PCB is a bare board, while PCBA is a finished board.