The PCB through-hole mainly consists of three parts: the hole, the pad area around the hole, and the POWER layer isolation area. In high-speed PCB design, it is often necessary to use multi-layer PCBs,

And via is an important factor in multi-layer PCB design. In high-speed PCB multilayer boards, signals need to be connected through vias when transmitted from one layer of interconnects to another layer of interconnects. So, what are the issues to pay attention to when designing high-speed PCB vias?

1. Choose a reasonable through-hole size. For multi-layer general density PCB designs, the ideal through-hole sizes for drilling, solder pads, and POWER isolation areas are 0.25mm, 0.51mm, and 0.91mm; For some high-density PCBs, through holes of 0.20mm, 0.46mm, and 0.86mm can also be used, and non through holes can also be attempted; For via holes in power or ground wires, larger sizes can be considered to reduce impedance.

2. The larger the POWER isolation area, the better.

3. The signal wiring on the PCB should be arranged without changing layers, that is, to minimize through holes as much as possible.

4. Using a thinner PCB is beneficial for reducing the two parasitic parameters of vias.

5. The pins of the power supply and ground should be close to the vias, and the shorter the lead between the vias and pins, the better; At the same time, the leads of the power supply and ground should be as thick as possible to reduce impedance;

6. Place some grounding vias near the vias of the signal switching layer to provide a short distance circuit for the signal.

7. The length of the through hole is also the main factor affecting the through hole inductance. When designing high-speed PCBs, in order to reduce the problems caused by vias, the length of vias is generally controlled within 2.0mm. For vias with a length greater than 2.0 mm, increasing the aperture of the vias can improve the continuity of the impedance to a certain extent. When the through-hole length is 1.0 mm or less, the optimal through-hole diameter is 0.20 mm~0.30 mm.

The above are the issues that need to be noted in high-speed PCB through-hole design. Have you mastered them all?

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