Music and Lights – the layout

I have finally finished designing the layout of the PCB, and I am very happy with the way it turned out. Everything fitted nicely on a 100 x 150 mm double-sided board. Here are some of my design guidelines before I started:

  • Keep the AC signals separate from the DC signals. Specially the speaker amplifiers.
  • Have a large ground plane and connect GND pins directly to it.
  • Place decoupling capacitors close to the respective device pins of the speaker amplifier and MCU.
  • Place the speaker amps symmetrically on the board to evenly distribute the heat.

And here is the result,

Front side of the Music and Lights PCB layout.

Front side of the Music and Lights PCB layout.

The smallest traces are 0.7 mm wide. The power rails are 1.5 mm wide. All the components are on the front side of the PCB except the speaker amps. The speaker amps will be heat sunk to the ground plane, so I placed them on the bottom side of the PCB.

I tried to line up similar components the best I could. It gives an aesthetic look to the board and actually makes it easier to mount the components and solder them.

Bottom side of the Music and Lights PCB layout

Bottom side of the Music and Lights PCB layout

The bottom side mostly consists of the GND plane. I had to put a few traces on the bottom side because they didn’t fit on the top side. Also this is the first time I am incorporating a filled zone into my PCB, and I am curious what challenges this will bring when I am going to etch the actual PCB.

One advantage of having filled zones, as far as etching is concerned, is that it reduces the amount of Cu needed to etch away. Also it reduces the amount of time needed for etching. But, because there are no filled zones on the front side I don’t think it will save me significant etching time.

One potential problem with having to etch filled zone is that it increases the chance of having unintended connections due to inadequate etching, since all the pads and traces are very close to the filled zone edges. I might increase the clearance a little bit more to reduce the chance of this happening.

Also here’s a 3D view of what the board will look like once its made and populated,

3D rendition of populated Music and Lights PCB. Note that some of the custom footprints do not show up in the 3D view

3D rendition of populated Music and Lights PCB. Note that some of the custom footprints do not show up in the 3D view

So I am onto the next step, making the PCB! I will keep you posted on that as well. Stay tuned and Thanks for reading!