Page 124 - Make Your Own PCBs with EAGLE from Schematic Designs to Finished Boards

FIGURE 5-6 Pin-Swapping in the Board Editor.

Lock

The Lock command allows you to protect a part so that it cannot be moved or modified without first
unlocking it. To unlock it, hold down the “Shift” key while using the Lock command. Or you could
just be careful and use Undo if you make a mistake.

Smash

This is the same Smash command that lets you separate the labels for a part from the part itself in the
Schematic Editor. This can be useful if you want to move, say, a part value away from the outline of

the part to prevent overlaps of text and the part.

Split

Split allows you to add an extra bend on the segment of a track without having to reroute the section.

Meander

Meanders are used in high-frequency projects where the track length can affect when signals arrive at
a component. A Meander zigzags to lengthen the track. This is something of a professional feature
needed for boards operating at very high frequencies and unlikely to be needed by us hobbyists.

Shapes and Text

There are various different shapes and text that you can use to draw on your board. This can be in
copper if you select top or bottom as the layer or can appear in the final silk screen if you select the
layer that will eventually be used for silk screen—often tPlace and bPlace.
Remember that parts will come with their own text and placement guides, so you do not usually
need to draw much in the way of annotation. The Polygon shape, when drawn in copper, can be used

to create a ground plane, something we will discuss in the example section.

Via

Vias are used to allow a track from one layer to continue on another layer, that is, from top to bottom
or vice versa. Physically, they are small holes with a connection between the layers. It is better to
create vias automatically as you route simply by switching layers than to add them explicitly. In other
words, avoid the Via command.

An exception to this is if you have two ground planes (see later in this chapter), one on the top
layer and one on the bottom, and you want a good connection between them. You might then add a
number of vias to achieve this.

Hole

It is quite common to add a hole to a PCB so that it can be fixed into an enclosure. The Hole
command lets you do this. When adding a hole, be careful that no tracks will be cut by the hole.

Dimensions