PCB Technical - The role of copper paving in PCB design

Laying copper is the idle space on the PCB with copper surface coverage, all kinds of PCB design software provide intelligent copper paving function, usually paving copper after the region will become red,on behalf of this part of the region covered with copper.

Why PCB copper?

1.EMC.For a large area of the ground or power supply paved copper, will play a shielding role, some special ground, such as PGND to play a protective role.

2.PCB process requirements.Generally in order to ensure that the plating effect, or lamination is not deformed, for less wiring PCB board layer paved with copper.

3. Signal integrity requirements,to give high-frequency digital signals a complete return path, and reduce the wiring of the DC network. Of course, there are heat dissipation, special device installation requirements,such as copper.

What is the role of copper paving PCB design?

1.PCB copper can improve the conductivity of the circuit board. Because copper has good electrical conductivity, so the use of copper foil in the manufacturing process of printed circuit boards can greatly improve the conductivity of the circuit board. This will ensure that the connection between the components is more stable and reliable.

2.PCB copper can also enhance the mechanical strength and stability of the printed circuit board. As the copper foil itself has high mechanical strength and stability, so in the process of use can effectively prevent the printed circuit board by the external environment and the impact of damage or deformation and other issues.

3.PCB copper can also protect the board from oxidation or corrosion and other effects. As copper foil has good corrosion resistance, so the surface of the circuit board coated with a layer of copper foil can effectively protect the circuit board from oxidation or corrosion and other effects. This can extend the service life of the circuit board, and to ensure the stability and reliability of the circuit board in the process of use.

In the PCB design,you can use the laying of copper for heat dissipation in the following ways:

Designing the heat dissipation area: According to the distribution of heat sources on the PCB board,reasonably design the heat dissipation area, and lay enough copper foil in these areas to increase the heat dissipation surface area and thermal conductivity path.

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

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

Increase heat sinks: Increase heat sinks in the heat dissipation area to conduct heat to the heat sink, and then emit heat through natural convection or fan heat sinks, etc. to improve heat dissipation efficiency.

However, copper laying is not a mandatory part of PCB design.

In some cases, laying copper may not be suitable or feasible.The following are some of the cases in which it is not appropriate to lay copper:

1.High-frequency signal lines:

For high-frequency signal circuits, laying copper may introduce additional capacitance and inductance, affecting the signal transmission performance. In high-frequency circuits, it is usually necessary to control the alignment of the ground line to minimize the return path of the ground line, rather than overlaying copper.

For example, laying copper can cause the signal of the antenna part to be affected.In the area around the antenna part of the copper easily lead to weak signal acquisition of the signal received a relatively large interference,the antenna signal for the amplifier circuit parameter settings are very strict,the impedance of the copper will affect the performance of the amplifier circuit.So the area around the antenna part of the general will not lay copper.

2.High-density circuit board:

For higher density circuit boards, excessive copper may lead to short circuits between lines or grounding problems, affecting the normal operation of the circuit. In the design of high-density circuit boards, you need to be careful to design the copper-paving structure to ensure that there is enough spacing and insulation between the lines to avoid problems.

3.Excessive heat dissipation and soldering difficulties:

If the pins of the components are fully covered with copper paving, it may lead to excessive heat dissipation, which makes desoldering and rework difficult. We know that the thermal conductivity of copper is very high, so whether it is hand soldering or reflow soldering, copper surface in the soldering will be rapid thermal conductivity, resulting in the loss of temperature such as soldering iron, the impact on the welding, so the design try to use the "crosshatch pads" to reduce the heat dissipation, easy to weld.

4.Special environmental requirements:

In some special environments,such as high temperature, high humidity, corrosive environments, 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 overlaying copper.

5.Special layers of boards:

For flexible circuit boards, rigid-flexible boards and other special levels of the board, you need to lay copper design according to the specific requirements and design specifications, to avoid excessive laying of copper caused by the flexible layer or rigid-flexible layer of the problem.

In PCB design, laying copper is a task that is both important and complex. It not only improves the conductivity, mechanical strength and stability of the board, but also effectively protects the board from oxidation and corrosion. However, laying copper is not a panacea, it may bring negative effects in some specific cases, such as high-frequency signal interference, the risk of short-circuit of high-density circuit boards, soldering difficulties.