PCB fabrication is the process of building a physical PCB from a PCB design according to a set of specifications. Understanding the design specifications is very important because it affects the manufacturability, performance, and production yield of the PCB. PCB refers to printed circuits board, printing wiring board(PWB).
One of the important design specifications to follow is “balanced copper” in PCB manufacturing. Consistent copper coverage must be achieved in each layer of the PCB stack to avoid electrical and mechanical problems that can hinder circuit performance.
PCB balancing copper role
1. Routing: Copper layers are etched to form the routing, and the copper used as the routing carries the heat along with the signals across the board. This reduces damage caused by irregular heating of the board that can lead to internal track breakage.
2. Heatsink: Copper is used as a heat sink for power generation circuits, avoiding the use of additional heat sink components and largely reducing manufacturing costs.
3. Increase the thickness of conductors and surface pads: Copper used as a plating layer on the PCB increases the thickness of conductors and surface pads. In addition, by plating through holes to achieve a strong interlayer copper connection.
4. Reduces the ground impedance and voltage drop: PCB-balanced copper reduces the ground impedance and voltage drop, thereby reducing noise and, at the same time, can also improve the efficiency of the power supply.
In PCB manufacturing, if the copper distribution between the stacked layers is not uniform, problems such as warpage and poor plating of conductive patterns may occur. printed wiring board
PCB balanced copper design specifications
1. During stacked layer design, it is recommended that the center layer be set to the maximum copper thickness and the remaining layers be further balanced to match their mirror image opposite layers. This recommendation is important to avoid the potato chip effect discussed earlier.
2. Where there are wide copper areas on the PCB, it is wise to design them as grids rather than solid planes to avoid copper density mismatches in that layer. This avoids bowing and twisting problems to a large extent.
3. In stacking, power layers should be placed symmetrically and the same weight of copper should be used in each power layer.
4. Copper balance is necessary not only in the signal or power layer but also in the core and prepreg layers of the PCB. Ensuring an even ratio of copper in these layers is a good way to maintain the overall copper balance of the PCB.
5. If there are areas of excess copper in a particular layer, the symmetrical opposite layer should be filled with tiny copper grids to balance it out. These tiny copper grids do not connect to any network and do not interfere with functionality. However, it is necessary to ensure that this copper balancing technique does not affect signal integrity or board impedance. printed wiring board