When it's time to move your circuit off the breadboard and into a practical application, you will have to design a printed circuit board, or PCB. PCB layout can be daunting for the beginner because of practical considerations like heat and unintended capacitance and resistance that are not present when designing a circuit on paper. These PCB layout tips outline some of the major factors to consider when designing a circuit board.
Watch Out For Board Capacitors
There will always be a tiny amount of capacitance between circuit traces, but if traces are laid too close together, the effect may become noticeable and disrupt your circuit. If the traces form a capacitor, fast voltage changes on one trace can cause a current signal in the other. To avoid this make sure that digital traces, which are likely to have rapid voltage changes, are kept separate from analog traces.
Keep ICs Facing the Same Direction
Make sure all your integrated circuits, or ICs, are oriented the same way, with the number one pin in the same position on every IC. This will make layout much simpler, and save you headaches when it is time to solder the ICs to the board. Also, keeping a fair amount of spacing between ICs will make laying out traces simpler.
Group Parts Which Are Connected
Components that are connected to each other should be in close proximity on the board, so that traces are as simple as possible. Power supply filtering capacitors should be as close as possible to the IC pins they are connected to. However, components that will generate heat should be kept away from each other and away from parts which are sensitive to temperature.
Orderly Ground and Power Rails
Use wide traces that connect to common power and ground rails, rather than daisy-chaining power supply or ground pins. A solid ground plane will help minimize distortion.
Signal Traces
According to ExpressPCB, traces should be as short and direct as possible to minimize interference and potential problems from inherent resistance and capacitance. A good trace width for low-power digital and analog signal lines is 0.01 inches. Higher power traces should be wider.
Orienting Polarized Parts
Your layout will be much simpler if you orient all polarized parts such as diodes and electrolytic capacitors in the same direction. Your traces will be more orderly, and it will be easier to place components on the board without making a mistake.
