Quick PCB design tips for vias

Here are a few quick tips that you can consider while employing vias in your design:

1.Avoid blind and buried vias unless the design absolutely requires them – These require more drilling time and extra laminations. This can increase the cost of the overall PCB.

2.Stacked and staggered vias – Choose staggered instead of stacked vias since the stacked vias need to be filled and planarized. This process is time consuming and expensive as well.

3.Keep the aspect ratio minimum. This provides better electrical performance and signal integrity. Also, this results in lower noise, lower crosstalk, and lower EMI/RFI. Read our post on how to avoid crosstalk in HDI substrate.

4.Implement smaller vias in high-speed designs since the stray capacitance and inductance gets reduced.

5.Always select the simplest option that fulfills your design needs. Lowering the complexity of the via leads to decreased turnaround time and manufacturing costs.

6.Non-conductive fill is typically adequate for signal routing and is more cost-effective. Therefore it is better to use non-conductive epoxy wherever possible.

7.When you are routing high-speed signals such as for high definition multimedia interface (HDMI) it is better to utilize blind or buried vias to eliminate stubs.

8.Always use conductive fill for thermal or high power vias. The higher thermal conductivity will be helpful in heat dissipation required for high power components.

9.When using filled vias, ensure the pad surface after filling is planar, ensuring level component placement to avoid tombstoning defect. A tombstoning defect is where one side of the component detaches from the board during soldering.

10.Using vias on differential pair – differential pair routing requires traces to be equal in length to avoid differential time-delay skew. Differential skew is where one signal reaches earlier than the other at the receiver. As far as possible avoid vias on differential pairs. In case one signal is routed through a via, then the other signal in a differential pair must also be routed through a via. On a differential pair, the number of vias on each trace should be the same.

11.Vias on high-speed signals – Vias tend to introduce inductance and capacitance to the circuit. Such characteristics are often negligible in signals which have lower frequencies. When it comes to high-speed signals, vias may significantly affect signal integrity. Therefore it is better to avoid using vias on high-speed signals.