Learning how to design a PCB layout , you will learn 12 most basic but working PCB design rules and tips to make the PCB layout easier. The basic PCB layout rules will help you to avoid potential mistakes. Also be beneficial to improve your PCB layout skill.
Charter 1 PCB Layout
What are the most important parts?
Those matters to the circuit configuration are the most important, and you can call them “core parts”. They include connectors, switches, power sockets, etc. In your PCB layout, place these most components first.
Core components are the parts that achieve vital functions of the circuit design. Make it or them the center(s) of your PCB layout.
If a part is large in size, make it a center in the layout as well.
Then place other electrical components surrounding the core/large component(s).
Your PCB layout should meet the following six requirements as much as possible.
The total wiring should be short. The key signal should be short.
High voltage and high current signals are completely separated from the low voltage and low current signals.
The analog signals and digital signals are separated in the circuit design.
High-frequency signals and low-frequency signals are separated.
High-frequency components should be separated and the distance between them should be as far as possible.
A standard circuit board is uniform, balanced in gravity, and aesthetic.
Being uniform means the distribution of components and wiring is uniform in the PCB layout.
If the layout is uniform, it should also be balanced in gravity. This is important because a balanced PCB leads to a stable electronic product.
A PCB transmits various signals, and different parts on it transmit their own signals. So you should protect the signal of each part and prevent signal interference first, and then consider filtering undesired waves for the electronic part.
The layers and stack-up directly affect the wiring and impedance of printed-circuit lines. And if you decide the board size, you determine the stack-up and width of the printed-circuit lines to achieve the expected PCB design effect. It is best to apply as more as possible circuit layers and make the copper evenly distributed.
For successful routing, you need to carefully consider design requirements and have the routing tool work under correct rules and constraints, which affect the performance of the routing tool greatly.
Classify all signal lines that have special requirements in the order of priority. The higher the priority is, set up stricter rules to the signal line.
The rules involve the width of the printed-circuit lines, the maximum number of vias, parallelism, the mutual influence between signal lines, and layer restrictions.
DFM is the short form of “design for manufacturability” and “design for manufacturing”. The DFM rules have a huge impact on the component layout, especially the optimization of the automobile assembly process. If the assembly department or PCB assembly company allows moving components, the circuit can be optimized to make automatic routing easier. If you are not sure about the DFM rules, you can get free DFM service from LingtechPCB.
During the fan-out design, there should be at least one via for each surface mount equivalent of the component. In this way, when you want more connections, you can deal with internal connections, on-line testing, and circuit reprocessing on the circuit board.
Manual routing was, is, and always will be a necessary process of printed circuit board design.
Why? Without manual wiring, the automatic wiring tool won’t be able to complete the wiring successfully. Through manual wiring, you create a path that is the basis for automatic wiring.
Nowadays the automatic routing tools are very powerful and, if you set up constraints and rules appropriately, they can complete almost 100% of the routing.
To route the signal wires, you should adopt the general rule, namely, deciding the layers and via the number that the signal pass by setting up constraints and not allowed routing areas. Following this rule, the automatic routing tool can work as you wish.
If the wires for signals with few constraints are very long, find out which are reasonable and which are not, and shorten the wiring as much as possible and reduce the via quantity.
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