What Is a PCB?
Printed Circuit Board (PCB) is a foundational infrastructure used for connecting electronic components, typically made of insulating materials with conductive pathways printed on its surface. PCBs provide electrical connections and mechanical support. They are widely used in various electronic devices, such as mobile phones, computers, and household appliances. Modern PCBs can achieve multilayer designs, supporting more complex circuit layouts. Many distributors like Heisener offer a wide range of components of PCB to cater to diverse application needs
Features of PCB
High Density
Over the years, the high density of printed circuit boards (PCBs) has evolved with the increasing integration of integrated circuits and advancements in mounting technology.
High Reliability
A series of inspections, tests, and aging experiments ensure the long-term operation of PCBs.
Designability
Various requirements for PCBs can be achieved through standardized and regulated design practices.
Manufacturability
PCBs utilize modern management techniques to enable standardized, scalable, and automated production.
Testability
Various testing devices and instruments can be used to detect and verify the compliance of PCB products.
Assemblability
PCB products facilitate standardized assembly of various components and enable automated, large-scale production.
Maintainability
Since PCB products and their components are designed and produced using standardized methods, these components are also standardized.
Structure of PCB
The structure of a PCB typically includes several main components: the substrate, conductive layers, insulating layers, and surface treatment layers. The substrate serves as the foundation of the PCB, usually made from insulating materials such as fiberglass or epoxy resin. The conductive layers consist of copper traces printed on the surface of the substrate.
In multilayer PCBs, in addition to the surface layers, multiple internal conductive and insulating layers are alternately stacked. This structure supports more complex circuit layouts, increasing circuit density and functionality. Furthermore, the surface treatment layers are often made from various materials to enhance solderability and corrosion resistance.
Benefits of PCB
PCBs offer several advantages to electronic devices:
- They provide mechanical support for fixing and assembling various electronic components, enabling wiring and electrical connections or insulation between integrated circuits and other components.
- PCBs offer solder mask patterns for automated soldering, along with identification characters and graphics for component insertion, inspection, and maintenance.
- The consistency of PCBs reduces errors associated with manual wiring and facilitates automated component insertion, surface mounting, soldering, and testing.
- In high-speed or high-frequency circuits, PCBs provide the necessary electrical characteristics, impedance, and electromagnetic compatibility.
- PCBs with embedded passive components simplify electronic installation procedures by offering certain electrical functions.
- They serve as effective chip carriers for miniaturized electronic components in large-scale and ultra-large-scale packaging.
Types of PCB
Based on the number of circuit layers, PCBs can be classified into three main types: single-sided boards, double-sided boards, and multi-layer boards.
Single-Sided Boards
Single-sided boards are the most basic type of PCB, where all components are concentrated on one side, and the traces are located on the opposite side (when using surface-mount components, traces and components may be on the same side). Since traces only exist on one side, the design is subject to strict limitations, such as not allowing trace crossings. Therefore, this type of board is mainly used in early circuit designs.
Double-Sided Boards
Double-sided boards allow for traces on both sides. To connect the traces between the two sides, vias are used—small holes in the PCB that are filled or coated with metal to connect traces from both sides. The area of a double-sided board is twice that of a single-sided board, which resolves the trace crossing issues found in single-sided designs, making it suitable for more complex circuit designs.
Multi-Layer Boards
Multi-layer boards increase the available routing area by stacking multiple single-sided or double-sided boards. Typical multi-layer boards consist of four or six layers, but they can even reach dozens of layers. The structure usually includes a double-sided board as the inner layer, with several single-sided or double-sided boards as outer layers, connected through insulating materials and positioning systems.
Although the number of layers does not directly indicate the number of independent routing layers, it is generally an even number, including the two outer layers. Most motherboards are designed with 4 to 8 layers, but theoretically, PCBs can be designed with nearly 100 layers. While some supercomputers utilize multi-layer boards, the use of ultra-multi-layer boards has gradually declined with the rise of cluster computing. Upon close inspection of a motherboard, the actual number of layers can still be observed.
How to Install a PCB?
First, clean the surface of the PCB. Choose an appropriate location and align the PCB with the mounting holes on the chassis or base. Use a screwdriver to screw the screws clockwise into the mounting holes.
Next, identify the power and signal connection points based on the markings on the PCB. Align the power and signal wires with the corresponding slots and gently insert them. Finally, perform a power-on test, observe whether the PCB operates normally, and check the indicators and functionality. If any abnormalities are detected, promptly disconnect the power and inspect the connections and components.
