"Benefits outweigh the disadvantages" "Benefits outweigh the benefits" of PCB copper  

Do you know copper as an important part of PCB design? The so-called copper cladding is to use the idle space on the PCB as a reference plane then fill it with solid copper. These copper areas are also called copper filling. The significance of copper clad is that it reduces the impedance of the ground wire improves the anti-interference ability; reduces the voltage drop improves the efficiency of the power supply; connecting to the ground wire can also reduce the loop area so on.

First, the way of copper

There are generally two basic methods of copper clad copper, that is, large-area copper (solid copper) grid copper. Is that a large area of copper grid copper?

1.Solid copper

Advantages: It has the dual functions of increasing current shielding.

Disadvantages: If the wave soldering is performed, the board may rise even blister.

Solution: Generally, several grooves will be opened to ease the copper foil blistering.

2, grid copper

Advantages: the perspective of heat dissipation, the grid is beneficial (it reduces the heating surface of copper) plays a role of electromagnetic shielding.

Disadvantages: Simple grid copper is mainly used for shielding, the effect of increasing current is reduced.

Second, the advantages disadvantages of copper

Pros: Provide additional shielding protection noise suppression for the inner layer signal, improve the heat dissipation ability of the PCB. In the PCB production process, the amount of etchant is saved. Avoid PCB warpage deformation caused by different stresses caused by PCB over-reflow due to uneven copper foil.

Disadvantages: The copper-clad plane on the outer layer must be fragmented broken by the surface components signal lines. If there is poorly grounded copper foil (especially the thin long broken copper), it will become an antenna generate EMI problem. If the copper of the component pins is fully connected, the heat will be dissipated too quickly, which will cause difficulties in desoldering rework soldering. The outer copper-clad plane must be well grounded. It is necessary to punch more vias to connect to the main ground plane. If more vias are punched, it will inevitably affect the wiring channels, unless buried blind holes are used.

Third, the matters needing attention

When engineers are copper-clad, in order to achieve the desired results, they need to pay attention to the following aspects:

1. If there are many "grounds" on the PCB, such as SGND, AGND, GND, etc., it is necessary to independently cover the copper with digital ground It is too much to separate the copper clad the analog ground. At the same time, before the copper clad, the corresponding power supply wiring is thickened: 5.0V, 3.3V, etc. In this way, a number of different shapes multiple deformation structures are formed.

2. For single-point connections to different grounds, the method is to connect through 0 ohm resistors magnetic beads inductors.

3. Copper clad near the crystal, the crystal in the circuit is a high-frequency emission source. The method is to clad the copper around the crystal, then ground the crystal case separately.

4, isolated island (dead zone) problem, if you think it is too big, then it is too much to define a land via to add it.

5. At the beginning of wiring, the ground wire should be treated equally. When the wire is routed, the ground wire should be routed well. You cannot rely on copper through adding vias to eliminate ground pins for connection. This effect is very bad.

6. It is recommended to have sharp corners (<= 180 degrees) on the board, because the perspective of electromagnetics, this constitutes a transmitting antenna! For others that will always have an effect, it is only large small. It is recommended to use arc edges.

7. Do cover copper in the open area of the middle layer of the multilayer board. Because it is difficult for you to make this copper “good ground”.

8. The metal inside the equipment, such as metal radiators, metal reinforcement bars, etc., must achieve "good grounding".

To sum up, if the copper on the PCB is dealt with properly, the advantages are greater than the disadvantages. It can reduce the reflow area of the signal line reduce the external electromagnetic interference of the signal. Circuit board manufacturer