ROUTING

 

Routing is the most fun part of this entire process. It’s like solving a puzzle! Our job will be turning each of those gold airwires into top or bottom copper traces. At the same time, you also have to make sure not to overlap two different signals.

USING THE ROUTE TOOL

To draw all of our copper traces, we’ll use the ROUTE tool–  — (not the WIRE tool!). After selecting the tool, there are a few options to consider on the toolbar above:

• Layer: On a 2-layer board like this, you’ll have to choose whether you want to start routing on the top (1) or bottom (16) layer.

• Bend Style: Usually you’ll want to use 45° angles for your routes (wire bend styles 1 and 3), but it can be fun to make loopy traces too.

• Width: This defines how wide your copper will be. Usually 0.01″ is a good default size. You shouldn’t go any smaller than 0.007″ . Wider traces can allow for more current to safely pass through. If you need to supply 1A through a trace, it’d need to be much wider .

The worst thing you can do during your routing process is connect nets incorrectly, but Autodesk EAGLE makes this process easy with some handy highlighting. Check out all of the airwires in the image below; they define connection paths between components.

If we go ahead and select the Route  tool in Autodesk EAGLE and then select a green net, you can see what happens in the image. All elements that belong to the net are highlighted in bright green, giving you an easy to follow map of your locations for your routes.

 

MANUALLY ROUTING YOUR NETS

The process for manually routing in Autodesk EAGLE is straightforward. Your job is simply to connect the airwires together that Autodesk EAGLE highlights for you. But the challenge is figuring out how to connect all of them without any overlapping connection points (shorts). Here’s how to connect a trace between two nets:

1. Select the Route  tool on the left-hand side of your interface.

2. Next, press Spacebar to cycle through the available routable layers. You can also select your desired routing layer in the top-left corner of your interface with the Layer Selection dropdown.

3. 

4. Once your layer is selected, left-click on your first net to start your connection. You’ll notice that Autodesk EAGLE will highlight that net and the pads to connect.

5. You can now drag your mouse towards the next net, and your trace will follow your cursor. By default you’ll be using a 90-degree trace, if you right-click, you can change your trace angle to a different angle.

6. Once your trace reaches its net destination, left-click to finalize the connection.

After finalizing your net connection, the airwire that you were following should have disappeared. You can go ahead and repeat the five steps above now and see how far you can get with routing your board.

With those all set, you start a route by left-clicking on a pin where a airwire terminates. The airwire, and connected pins will “glow”, and a red or blue line will start on the pin. You finish the trace by left-clicking again on top of the other pin the airwire connects to. Between the pins, you can left-click as much as you need to “glue” a trace down.

While routing it’s important to avoid two cases of overlap: copper over vias, and copper over copper. Remember that all of these copper traces are basically bare wire. If two signals overlap, they’ll short out.

If traces do cross each other, make sure they do so on opposite sides of the board. It’s perfectly acceptable for a trace on the top side to intersect with one on the bottom. That’s why there are two layers!

If you need more precise control over your routes, you can hold down the ALT key on your keyboard to access the alternate grid. By default, this is set to be a much more fine 0.005″.