PCB Trace Best Practices?

[Holmes34]

Hey all!

Recently I've been getting interested into making my own stand-alone projects based on ATtiny microcontrollers, and in the process of climbing the steep learning curve of Eagle, I've realised that I should probably get some advice on the "best practice" for routing traces and some other basic PCB design questions.

The current board I'm working on is for controlling 2 small servomotors and a cheap laser diode in constant current. I haven't finished adding all of the components and elements I want/need, but I decided I should get help earlier rather than later! Attached is the current state of the board in Eagle.

Is it appropriate to route the traces in-between the pins of the MC (the 8 pins on the right)? Is it appropriate to route a trace through a pad, or should I aim to only connect pads by "branching" off a main "rail"? Is it ok to route traces under a component (e.g. under the MC body)?

Disclaimer: Many things in this post might be laughably silly! I am not liable if you laugh yourself to death!

[Aeternam]

Hey Holmes,

You might want to take a look at Dave's PCB design tutorial, there's a lot of good info there: https://www.eevblog.com/forum/eda/pcb-design-tutorial-by-david-l-jones/

[lem_ix]

If you're going to send the board to a fab, they have a set of design rules you need to follow like 10/10, meaning 10 mils min trace width, 10 mils clearance minimum. Generally it's ok to route between the pads if you can follow the clearance rule for your trace size.  It's also perfectly fine to run a trace under a component, unless there's a specific reason not to, like noise coupling of some sort. For DIY PCBs I guess it depends on your skill, it's fine to do if you can make a pcb with finer traces but most people use wider ones for that. Another point to maybe consider is whether you'll be soldering around that point. Think about when you assemble the board, will it make soldering more difficult etc.

[alexanderbrevig]

You probably want some decoupling caps

[Holmes34]

You probably want some decoupling caps

Definitely!