Do you know the advantages of PCB pouring copper on the surface of the PCB? In the whole process of PCB design, engineers want to ignore the link of pouring copper on the bottom of the PCB in order to save time. Is this right? Is it necessary for the PCB to pouring copper on the bottom of the surface? What are the advantages of copper on the bottom of the PCB?
First of all, we need to be clear: the copper on the bottom of the surface is beneficial and necessary for the 5G antenna PCB, but the copper on the whole board needs to comply with some conditions.
Advantages of pouring copper on the bottom of the PCB:
From the EMC point of view, the whole board is covered with copper on the bottom of the surface, which provides additional shielding protection and noise suppression for the inner signal and also has a certain shielding protection for the components and signals on the bottom of the surface.
- From the perspective of heat dissipation, as the current PCB boards are getting denser and smaller, the BGA main chip also needs to consider thermal issues more and more. The copper on the whole board improves the heat dissipation capacity of the PCB board.
- From the perspective of process analysis, the entire board is covered with copper, so that the 5G antenna PCB board is evenly distributed, avoiding the bending and warping of the board during PCB processing and pressing and avoiding the different stresses caused by the PCB over reflow due to the unbalanced copper foil. The PCB is warped and deformed.
Reminder: For two-layer boards, copper pouring is necessary
- On the one hand, since the two-layer board does not have a complete reference plane, the pouring copper can provide a return path and can also be used as a coplanar reference to achieve the purpose of impedance control. We can generally pour copper on the bottom layer as the ground plane, put the main components on the top layer and use power lines and signal lines. For high-impedance loops, analog circuits (analog-to-digital conversion circuits, switch-mode power conversion circuits), copper plating is a good practice.
The condition of copper pouring on the bottom surface.
Although pouring copper on the surface and bottom layer is good for a 5G antenna PCB, it also needs to follow some conditions:
1. Pour copper by hand at the same time as much as possible, do not cover it all at once, avoid broken copper skin, and properly add via holes in the copper paving area to the ground plane.
Reason: The surface copper-clad plane must be separated by the surface components and signal lines. If there is a poorly grounded copper foil (especially thin and long copper), it will become an antenna and cause EMI problems. .
2. Consider the small footprint, such as 0402 0603 and other small packages, to avoid the tombstone effect.
Reason: If the whole board is covered with copper, if the component pins are fully connected with copper, the heat will be lost too quickly, and it will be difficult to desolder and rework.
3. It is best to pour copper into the whole board continuously. The distance from the ground to the signal needs to be controlled to avoid discontinuity in the impedance of the transmission line.
Reason: The copper skin that is too close when laying the ground will change the impedance of the microstrip transmission line, and the discontinuous copper skin will also cause a negative impact on the impedance discontinuity of the transmission line.
4. Some special situations depend on the application scenario. PCB design should not be an absolute design. It should be weighed and used in conjunction with the theories of all parties.
Reason: In addition to sensitive signals that need to be grounded, if there are many high-speed signal lines and components, a lot of small and long copper fragments are generated, and the wiring channels are tight, it is necessary to try to avoid the surface copper skin to be connected to the ground plane through holes. Then not to pour copper on the surface
The above are the advantages of pouring copper on the surface of the PCB board; I hope to help you.