Why do we need to perform fan holes in PCB design first？

There are two purposes of fan holes, to perforate to occupy space and reduce the return path!

For example, the GND hole, the nearby fan hole can achieve the purpose of shortening the path!

The purpose of pre-punching is to prevent the holes cannot be punched when the wiring is very dense after the holes are not punched. A GND line is connected a long distance, which is a very long return path.

This is often encountered when doing high-speed PCB design and multi-layer PCB design. It is very convenient to delete the hole after pre-punching. On the contrary, it is very difficult to add a via after you have finished routing the wire. At this time, your usual idea is to just find a wire to connect it, and you can’t consider the SI of the signal. Too much in line with normative practices.

How to judge those that should be fan holes?

Both can be fan holes. Short lines can be directly connected to the surface layer, and long lines can be unified fan holes. This is of great help to PCB designers in planning and routing, and the lines that come out are neat and beautiful.

Global fan holes before PCB layout

1. Fan holes counterclockwise or clockwise; short wires are directly connected.

2. For example, you can start from the lower left corner and connect directly with a short line. The power cord is directly thickened. VIA-8-16mil.

shift+e to grab the center.

3. For beauty, VIA is aligned up and down or left and right.

4. Crystal oscillator, π-shaped filter. Do not have via processing on the crystal oscillator circuit. Bad for the signal. Then deal with the crystal oscillator circuit.

5. Power supply: vcc and GND have the same number of vias.

6. Pay attention to the integrity of the ground plane when passing through holes. There must be ground between the two vias.