What is your typical values for the grid size and trace

Community PCB Design
1

Hello everybody, I have just started playing with eagle and I have some pretty basic questions to ask.

First, is what is your typical grid size in Eagle when you are editing one board, and what is the via size that you use, and also what trace width, for small signals like adc’s inputs for an atmega328 or atmega8, and some digital outputs to an lcd and some leds?

After having my first board im tempted to try the SeeedStudio Fusion pcb service, and I don’t know how to define my board size, is there some specific layer for that or some special trace?

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I dont use Eagle, I use other software but your questions are pretty much the same no matter what the software.

For thin signal tracks you have to consider the manufacturers requirements and how small you want to go.

Something about 6-8 thou would be average, you can get several hundred milliamps down that so it would do for most signals.

Same theory for via size, get the pcb toolkit (saturn design) to work out the currents for vias, but a drill size of about 0.5mm

would be a minimum before things start to get more expensive (many can go less - down to 0.3mm but it costs more)

I.E. 0.5mm drill/0.8mm land

To define your board size, add some dimensions on the drill drawing layer.

As for what grid - I have not used a grid for the last 10 years - works for me.

3

It depends on the requirements, size, packages, and how packed together your board is. Some things I would personally suggest are to always use a grid unless a certain area requires you to not use it. Grids simply make it a lot more organized and professional looking, and it’s way easier to deal with as far as numbers go. Also, try to avoid going down below 10mil for traces and spacing unless you really have to or you have a good reason to and your manufacturer can easily do it. Generally I use the smallest vias the manufacturer will allow without costing too much extra.

You want some specific numbers so I’ll give you a few. Here’s what I’m using for a larger board with two QFP ATmega328s on it and various other small components:

Traces: 16mil (32mil for power)

Spacing:10mil

Minimum drill: 20mil (vias)

Primary grid: 10mil

Alt grid: 5mil

If it’s a more complex, tight board you might want to use something like this

Traces: 10mil

Spacing: 10mil

Minimum drill: 15mil (IF you can)

Primary grid: 5mil

Alt: 2.5mil

Of course, these are just some of my settings for different projects and what you use is up to you. Hopefully it helps a bit though. As far as SeeedStudio Fusion goes, http://www.seeedstudio.com/depot/fusion … p-396.html has the minimum specs and it says “Board outline must be include at least in one layer.” I would include it on the top copper layer, and perhaps the top silkscreen. Do this with the gerber output rather than drawing them on both layers in eagle.