6 Basic Rules of PCB Layout
PCB layout involves designing a circuit with multiple layers. Some of the fundamental rules of PCB design are as follows: Avoid multiple ground planes. Make analog circuit signals direct and short. Avoid using three distinct capacitors on a single PCB. You can also read our articles on multi-layer PCB design and how to design a multi-layer PCB.
Designing a multi-layer PCB
When you are designing a multi-layer PCB, there are a few important things that you should consider. One of these is that the copper traces should maintain signal and power integrity. If they are not, then they could affect the quality of current. This is why it is necessary to use controlled impedance traces. These traces should be thicker than normal to prevent overheating.
Once you are clear on what you want, you can start designing the PCB. The first step in designing a multilayer PCB is to create a schematic. It will serve as the basis for your entire design. Start by opening a schematic editor window. You can then add and rotate details as needed. Make sure that the schematic is accurate.
Creating a single ground plane
Creating a single ground plane on a PCB layout helps reduce the amount of nonuniform voltages across a circuit board. This is accomplished by creating vias or through holes to connect the ground plane with other parts of the board. It also helps reduce noise produced by variations in return current.
While defining a ground plane on a PCB, it is crucial to ensure that the ground plane is not covered with conductive rings because this can lead to electromagnetic interference or even ground loops. Ideally, the ground plane should be located under electronic components. It may be necessary to rearrange the placement of some traces and components to fit the ground plane.
Keeping analog circuit signals direct and short
When implementing a PCB layout for analog circuits, it is important to keep the analog signal traces short and direct. In addition, analog components must be located near each other, which will simplify direct routing. Keeping noisy analog components close to the center of the board will also help reduce noise.
In addition to keeping analog circuit signals direct and short, designers should also avoid obstructing the return paths. Plane splits, vias, slots, and cutouts can cause noise as the analog signal seeks the shortest path back to its origin. As a result, the signal can wander near the ground plane, generating significant noise.
Avoiding three distinct capacitors
When designing a PCB layout, it is best to avoid placing three distinct capacitors on power pins. This arrangement may lead to more problems than it solves. One way to avoid three distinct capacitors is to use traces and coffer fill. Then, place them as close to the device’s pin as possible.
This is not always possible, however, since the distance between traces is not always what was calculated during the design phase. This is a common problem that can lead to problems during the assembly process. When considering placement, remember that the placement of each component is crucial to its functionality.
Using power layer copper
Using power layer copper in PCB layout requires proper planning. In this part of the board, you must allocate a specific area of the board for power network. You can also use inner layer division to allocate this area. To add this layer, you should use the command “PLACE-SPLIT PLANE” and then select the network to be allocated for split. Once you have the power layer area allocated, you can then use the copper paving technique to place the copper in the split area.
In addition to achieving even copper coverage, you must make sure that the thickness of the board is compatible with its core. Using the power plane symmetry alone will not guarantee a perfect copper coverage, as the copper in this part will tear when contour routing. Copper up to the board edge also will not be compatible with scoring (V-cut) techniques. To avoid this issue, it is recommended that you indicate the copper zone on the mechanical layer and that it has a minimum width of 0.5mm.
Using a list of guidelines to place components on a PCB
Using a list of guidelines to place a component on a PCB can help minimize the overall cost of developing a new product while shortening the product development cycle. These guidelines also help ensure a smooth transition from prototype to production. These guidelines are applicable to both analog and digital circuits.
Most board designers follow a set of guidelines when designing a PCB. For example, a typical board design rule is to minimize the length of digital clock traces. However, many designers do not fully understand the rationale behind these guidelines. Among other things, high-speed traces must not cross gaps in the signal return plane.