Vias in PCB Design

Connect traces across layers, and fit dense designs on fewer layers or a smaller board.

Learn how to use the different kinds of vias (blind, buried, micro and through-hole) to connect traces across multiple layers.


Overview

Vias are conductive connections that allow signals to pass between different layers of a PCB. Here's a short overview of the different via types:

  • Through vias: Connect the two outer layers (Top and Bottom), and every layer in between

  • Blind vias: Connect an outer layer to an inner layer without going all the way through to the other outer layer

  • Buried vias: Connect two internal layers without reaching any outer layer

  • Microvias: Very small vias typically used to connect adjacent layers

Via Configuration

Ask Flux to set up the via types for your stackup.

Add a blind via from the top layer to layer 2 and a buried via from layer 2 to layer 3.
Set up an HDI stackup with laser-drilled microvias between the top two layers.
Use 0.3 mm through vias with a 0.6 mm diameter on this board.

To do it in the UI:

To configure the via types that will be available to route the project you'll need to use the stackup editor:

  1. Select the layout object from the object tree on the left-side panel

  2. Locate the "object-specific" rules menu on the "Inspector" panel on the right-side

  3. Add a new Stackup rule

  4. Click on the pencil icon


Configuring Via Types

Ask Flux to add a via type.

Add a microvia from the bottom layer to the layer above it.

To do it in the UI:

By default, only through-hole vias are configured. To add more via types on the stackup editor:

  1. Scroll all the way to the right on the stackup editor

  2. Click on + Via Config at the top-right of the stackup editor

  • A new Via config column will be created

  • You can edit the name of the via type by double-clicking on the column name

  1. Click on + Via at the bottom of the column to add new vias to the type

  • You can click the +Via button as many times as you need to add more vias

  1. Click to select the newly added via and configure it with the via panel on the right

  • Use "Laser Drill" for microvias and "Mechanical Drill" for all the rest of the types

  • Hole Size and Size parameters can be typed directly, or configured as a group as mentioned in the next step


Configuring Via Size

Ask Flux to set the via and hole sizes.

Set the through via to a 0.25 mm hole and a 0.5 mm diameter.

To do it in the UI:

You can configure pre-determined via and via hole sizes for quicker via configuration. To add via size configuration groups:

  1. Navigate to the "Via Hole Configs" tab within the stackup editor

  2. Modify the default "Mechanical Drill" group, or add a new group by clicking the "+Via Hole Config" button on the bottom-left corner of the editor

  3. The configured groups will be visible when configuring a via on the "Stackup and Vias" tab


What's Next

Now that you understand how to configure and use vias in Flux, you might want to explore:


Next to read:
Smart Vias
On This Page
Vias in PCB DesignOverviewVia ConfigurationWhat's NextConfiguring Via TypesConfiguring Via Size