Percussa SSP Layout Update #5 - Footprint checking and ADC/DAC re-routing

via Bert on the Percussa SSP Kickstarter campaign:

"Hi all,

I spent most of the past week going through my TODO / checklist (40 pages long!), checking footprints, double checking small but important details in the documentation of the ICs I’m using in the design of the SSP, and adding pin headers on the back of the PCB to help with development and testing later on when the hardware is done.

One of the items I wanted to go over the past week was double checking the footprints of the QFN ICs i’m using. They require special solder paste apertures and thermal vias, which have an influence on how well they solder to the PCBs later on in production. I also made a few small changes to the BGA256 footprint I have in the design, I reduced the diameter of the ball pads to match the recommendations of the assembly house we work with.


Checking paste aperture for QFN footprints



Adjusting BGA256 ball pad diameter

I also wanted to place the voltage reference caps closer to the ADCs and DAC I’m using in the design. They are pretty important to get the performance I want and I wasn’t 100% satisfied with where they were sitting (a little too far) so I moved them really close now, moving the DAC to the other side of the PCB to make room. Yesterday I started routing the signals again from the input/output stages to the DAC and ADCs. I’ll probably be done with that end of the weekend.


Re-routing signals near ADCs/DAC after placing ref caps closer

We made a lot of progress the past week, and the TODO list is now a lot shorter, which means I can focus most of my time in the next week on re-routing the traces of the digital section of the board and checking / updating the layout of the different power supplies in the design!

Thanks again for your support, and until next week :-)

Bert"