PCB Tech - PCB circuit board design: parasitic effects of vias

PCB circuit board design: parasitic effects of vias

Printed circuit boards {Printed circuit boards}, also known as printed circuit boards, are providers of electrical connections for electronic components.
Printed circuit boards are often represented by "PCB", but cannot be called "PCB boards".

In the process of designing the PCB circuit board, seemingly simple vias, if you do not leave a sound, it is likely to bring great negative effects to the circuit board. Today, I will tell you how to reduce the adverse effects of the parasitic effects of the vias in the via design of the PCB circuit board:

How to reduce the adverse effects caused by the parasitic effects of the vias in the via design of the PCB circuit board
1. The power and ground pins should be drilled nearby, and the lead between the via and the pin should be as short as possible, because they will increase the inductance. At the same time, the power and ground leads should be as thick as possible to reduce impedance.

2. The signal traces on the PCB circuit board should not be changed as much as possible, that is to say, try not to use unnecessary vias.

3. The use of a thinner PCB circuit board is conducive to reducing the two parasitic parameters of the via.

4. Considering the cost and signal quality, choose a reasonable size of the via hole. For example, for the 6-10 layer memory module PCB circuit board design, it is better to use 10/20Mil (drilled/pad) vias. For some high-density small-size boards, you can also try to use 8/18Mil Of vias. Under current technical conditions, it is difficult to use smaller vias. For power or ground vias, you can consider using a larger size to reduce impedance.

5. Place some grounded vias near the vias of the signal layer to provide the nearest loop for the signal. It is even possible to place a large number of redundant ground vias on the PCB circuit board. Of course, the design needs to be flexible.

The via model discussed earlier is the case where there are pads on each layer. Sometimes, we can reduce or even remove the pads of some layers. Especially when the density of vias is very high, it may lead to the formation of a break groove that separates the loop in the copper layer. To solve this problem, in addition to moving the position of the via, we can also consider placing the via on the copper layer. The pad size is reduced.

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