The Role of Copper In PCB Design and Its Precautions

PCSPCB for you to talk about the role of copper in pcb design? The role of copper laying in PCB design and its precautions. After all the content of the PCB design is completed, there is usually a key step of the last step - laying copper. Copper paving is to cover the idle space on the PCB with copper surface, all kinds of PCB design software provide intelligent copper laying function, usually the area completed by copper will turn red, representing this part of the area is covered with copper. So why the copper laying? How about no copper?

In fact, copper paving has many positive effects on the performance and reliability of PCB, such as reducing ground impedance, improving anti-interference ability, and helping heat dissipation. PCSPCB will discuss in detail the role of copper laying in PCB design and its considerations.

The role of copper laying in PCB design and its precautions

1. Reduce the ground impedance

There are a lot of peak pulse currents in digital circuits, so it is necessary to reduce the ground impedance. Copper paving is a common method to reduce ground impedance. The resistance of ground wire can be reduced by increasing the conductive cross-sectional area of ground wire. By shortening the length of ground wire, the inductance of ground wire can be reduced and the impedance of ground wire can be reduced. It is also possible to control the capacitance of the ground wire so that it is appropriately increased, thereby improving the electrical conductivity of the ground wire and further reducing the impedance of the ground wire.

Large area of ground or power copper can play a shielding role, reduce electromagnetic interference, improve the anti-interference ability of the circuit, to meet the requirements of EMC. For high-frequency circuits, copper paving can also provide a complete return path for high-frequency digital signals, reducing the wiring of the DC network, thereby improving the stability and reliability of signal transmission.

2. Improve heat dissipation

In addition to reducing the ground impedance, copper can also be used for heat dissipation. Metal is a material that is easy to conduct electricity and heat, so laying copper on the PCB can increase the metal composition of the board and increase the heat dissipation surface area, thus contributing to the overall heat dissipation of the PCB board.

Laying copper can help evenly distribute heat and prevent local areas of high temperature. By evenly distributing the heat to the entire PCB board, the local heat concentration can be reduced, the temperature gradient of the heat source can be reduced, and the heat dissipation efficiency can be improved.

- Design heat dissipation areas: according to the heat source distribution on the PCB board, reasonably design heat dissipation areas, and lay enough copper foil in these areas to increase the heat dissipation surface area and heat conduction path.

- Increase the thickness of copper foil: Increasing the thickness of copper foil in the heat dissipation area can increase the thermal conductivity path and improve the heat dissipation efficiency.

- Design heat dissipation through holes: Design heat dissipation through holes in the heat dissipation area, and transfer heat to the other side of the PCB board through the holes to increase the heat dissipation path and improve heat dissipation efficiency.

- Add heat sink: Add heat sink in the heat dissipation area, transfer heat to the heat sink, and then dissipate heat through natural convection or fan radiator, improve heat dissipation efficiency.

3. Reduce deformation and improve manufacturing quality

Copper paving can help ensure the uniformity of electroplating, reduce the deformation of the plate during the lamination process, especially for double-sided or multi-layer PCB, and improve the manufacturing quality of the PCB. If the copper foil distribution in some areas is too much, and the distribution in some areas is too little, it will lead to the uneven distribution of the entire board, and the copper can effectively reduce this gap.

4. Meet the installation requirements of special components

For some special devices, such as devices that require grounding or special installation requirements, copper laying can provide additional connection points and fixed supports, enhancing the stability and reliability of the device. Despite the many advantages of copper laying, in some cases, copper laying may not be suitable or feasible.

For high frequency signal lines, laying copper may introduce additional capacitors and inductors, affecting the transmission performance of the signal. In high-frequency circuits, it is usually necessary to control the wiring mode of the ground wire and reduce the return path of the ground wire, rather than over-laying copper.

For high density circuit boards, excessive copper placement may lead to short circuits or ground problems between lines, affecting the normal operation of the circuit. When designing high-density circuit boards, it is necessary to carefully design the copper structure to ensure that there is sufficient spacing and insulation between the lines to avoid problems.

If the pin of the component is fully covered with copper, it may cause excessive heat dissipation, making it difficult to remove welding and repair. The thermal conductivity of copper is very high, so the copper surface will conduct heat rapidly during welding, affecting the control of welding temperature. In the design, "cross pattern pad" can be used to reduce heat dissipation and facilitate welding.

In some special environments, such as high temperature, high humidity, corrosive environment, copper foil may be damaged or corroded, thus affecting the performance and reliability of the PCB board. In this case, it is necessary to choose the appropriate material and treatment according to the specific environmental requirements, rather than over-laying copper.

For the flexible circuit board, rigid and flexible combined board and other special layers of the board, it is necessary to lay copper design according to the specific requirements and design specifications, to avoid the problem of flexible layer or rigid and flexible combined layer caused by excessive copper laying.

Copper paving plays an important role in PCB design, with multiple advantages such as reducing ground impedance, improving heat dissipation capacity, reducing deformation, and meeting the installation needs of special devices. In specific applications, appropriate copper paving design is required according to circuit requirements, environmental requirements and special application scenarios to ensure the performance and reliability of the PCB. In certain situations such as high-frequency signal lines, high-density circuit boards, and special environments, copper paving structures should be carefully designed to avoid potential problems. Through reasonable copper laying design, the overall performance and manufacturing quality of the PCB can be significantly improved.