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What you didn’t know about EAGLE: Display Via Length



Learn how to display the via information of your design including buried and blind vias in detail. A via is a point of transition in the PCB and its function is to transfer a trace between layers. The Via Lenght function in EAGLE will let you see the depth of the vias on your design. Options for via depth will depend on the layer setup done in your EAGLE Design Rule Checker (DRC).  EAGLE’s default setup for new boards is 2 layers, which satisfies a large percentage of design applications.

Figure 1 shows the default setup of a two layer board within the DRC setting. You can access your DRC by clicking on the pull-down menu Edit/Design Rules.

Figure 1

With this layer setup, all vias placed manually, routed manually or placed by the autorouter will have exposure on both sides of the board (Top and Bottom). EAGLE is able to support multiple layers in a board design. This next example shows a 4 layer setup with vias that have a length from the top layer to the bottom layer as shown in Figure 2. The via length for both examples is referred to as 1-16.

Figure 2

The use of blind and buried vias has become quite common for production runs of PCB designs. This technology allows the designer to save on precious PCB real estate much needed for smaller boards. Blind and buried vias are points of transition of a trace but do not travel the entire length of the board.  A blind via is a point of transition of a trace that begins on an exterior layer and ends on one of the inner layers. A buried via is the transition of a trace that happens only among the inner layers. Figure 3 shows the layer setup for using blind and buried vias.

Figure 3

To display “Via Length”,  got to the Options/Set found on the pull-down menu in the EAGLE board layout editor, and select the Misc tab. There you will find the displaying via length option. Refer to Figure or Click here for video blog

Figure 4

Your comments and questions are welcome.

CadSoft Support Team

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