PCB Copper Overlay: The area of a PCB layer that is filled with copper. The layer can be the top, bottom, or any interior of the PCB stack, and the PCB copper overlay can be used as a ground, reference, or to isolate specific components or circuits from the rest of the elements of the layer. With copper cladding, unused space on the PCB is used as a reference surface and then filled with solid copper, these copper areas are also known as copper infusion. The significance of copper lamination is to reduce ground impedance and improve interference immunity; to reduce voltage drop and improve power supply efficiency; and, to connect to ground and reduce loop area.
1. Copper cladding vs. grounding vs. grounding copper cladding
Copper cladding: The area of the PCB layer filled with copper, copper cladding with through holes can be used to help dissipate heat.
Grounding: The internal layer of a circuit board stack that is filled with copper and used as a signal power ground or reference.
Grounded Copper Cladding: Copper cladding that is used for grounding and does not occupy the entire layer. copper clad pcb board
2. The role of the PCB copper cladding
(1) Grounding on double-layer PCBs Both layers are used for signals and have no ground plane. For these boards, grounded copper cladding can be very helpful for efficient wiring by providing a central ground.
(2) EMI Shielding For good multilayer designs, a ground plane between the two signal layers is desired to minimize noise. If there is an internal signal layer next to the surface signal layer, grounded copper cladding can help reduce noise by adding shielding.
(3) Heat Dissipation Grounded copper cladding can also be used to draw heat away from high-power components, and heat sinks can then be used to remove excess heat from the board.
(4) Copper Balancing PCB Grounding Copper Cladding can also be used to achieve Contract Manufacturer (CM) by balancing the amount of copper on both sides of the board during PCB assembly, reducing the likelihood of warpage during reflow. In this case, crossed copper grids may be a better alternative to solid copper grounded overlays.
(5) Large Circuit Paths The addition of surface-grounded copper cladding can provide a shorter return path for high-current devices, such as switching converters, rather than connecting longer alignments to the ground plane.
(6) Ease of PCB Manufacturing Providing uniform copper distribution over a layer allows for better etching and plating processes and reduces the amount of etchant used in PCB manufacturing (cost reduction).
(7) RF and Microwave Design Grounding copper cladding contains localized areas of electromagnetic (EM) radiation, thereby reducing spurious coupling, radiation, and dispersion.
(8) Digital Design Ground plane improves immunity, improves ground uniformity, and improves low inductance current paths.
3. PCB copper cladding key points
(1) Sometimes copper cladding is used incorrectly just to fill unused space on the board.
(2) CAM engineers can add copper steal patterns to balance the copper distribution on the layers.
(3) Floatation (unconnected copper) is a real hazard to signal integrity and all copper overlays must be grounded.
(4) Grounded copper cladding without a grounding perforation can become a conduit for crosstalk between alignments on either side of the grounded shape.
(5) By creating the copper cladding as part of the grounding grid and configuring it as a solid plane, a well-defined return current path can be provided.
(6) Any additional planes must be properly positioned and spaced so that they do not negatively impact the signal integrity of the board.
(7) Grounding on the microstrip layer changes the transmission line from a microstrip line to a grounded coplanar waveguide.
(8) Copper cladding reduces the characteristic and differential impedance of the transmission line.
(9) CPW combines electromagnetic fields in a more localized manner than microstrip lines, thereby reducing spurious coupling, radiation, and dispersion.
(10) Microstrip lines can radiate. However, since the field is confined between ground planes, strip lines do not.
(11) Copper cladding reduces impedance by 2-3 ohms as it approaches critical signal alignments.
(12) Copper cladding may convert differential mode signals to common-mode signals at these points, thus compromising signal integrity.
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