Everything You Need To Know About Vias

By Administrator

Vias are used to create an:

i) electrical connection between layers

ii) a thermal path for heat flow

iii) ground or power connection

THE MOST COMMON VIAS

Through hole – connecting the upper layer with the lower layer.

Blind – connecting an exposed layer with an inner layer

Buried– connecting inner layers

Via types

The following are some simple tips for designing vias on printed circuit boards which will improve performance, increase the stability of the product and help cost efficiency.

GENERAL TIPS

  • Blind & buried vias can increase the cost of your PCB design by up to 12 (thanks to Quick‐teck 2012 PCB cost analysis report)
  • Position Ground & Power vias near power supply pins

When Designing High Speed Circuits Be Mindful That:

  • Vias can cause signal distortion. Do not add them without serious consideration to this factor.
  • Pads on vias create parallel pad capacitance.
  • The length and diameter of the via affects the capacitance & inductance.

When Using Thermal Vias Be Aware That:

  • Thicker plating on the via reduces thermal resistance.
  • Increased pad size helps to improve the thermal spreading.
  • Multiple well-spaced small vias can create better thermal transfer.
  • During solder reflow vias can fill, unless tented or plugged and this can result in reduced thermal transfer.

Blind & Buried vias have higher thermal resistance.

For more information on vias – and there is lots check out these great reads.

https://blog.lamsimenterprises.com/2011/02/15/pcb-vias-an-overview/

https://www.quick-teck.co.uk/TechArticleDoc/19895134801360697091.pdf