Custom Teensy 4.0 PCB layout Review

[Stewieman01]

Hi All, I wanted to ask here if anyone could critic my PCB layout for a Custom Teensy 4.0? I have had some experience in PCB design but nothing this complex. I tried to route the traces by order of their sensitivity to outside sources and the PJRC guide for custom Teensy 4.x was extremely helpful in providing tips to do the design, however i thought id check with those who know better than me in this field to see if my design needs any changes at all. I'm using the 10x10mm BGA MCU which has meant that i have used 0.15mm traces with 0.1mm spacing for under the MIMXRT1060 to fit around the small pads. Apologies if this design is bad, i appreciate any feedback.

Red = Top, Green = GND plane, Orange = 3rd layer and 3.3v pour, Cyan = 4th layer and GND pours, Pink = 3.3V power plane, Blue = Bottom

Thanks,
Alex

 

[AndyA]

You look to have multiple power / ground pins connected together with a single via to the plane. This isn't ideal, it leads to extra inductance on the power input and shortest possible connections to the ground pins are important for heat sinking as well as power reasons.

You have all the vias in a nice neat row, this creates large slots in the power and ground planes. Where possible stagger them a little so that the plane can flood between them.

Your capacitors should each have their own via to the power plane, this can be shared with the connection to one of the processor power pins. The smaller value parts should normally be scattered directly under the part or as close as possible to the power vias. Having them all lined up off to the side with a single trace and a single via shared between 5 is not good. Also some seem to have vias in their pads, normally this is something you want to avoid. Depending on your manufacturing capability maybe look at smaller footprint parts.

I know some of these are contradictory, mutually exclusive or simply impossible but they are what you should be aiming for. I can see a few traces that could easily be routed out on the surface rather than using vias. That would free up space either for caps on the back or more power / ground vias.


edit - I don't want this to come across as overly critical, it's not ideal but not bad for a first pass. I've seen far worse layouts work. The points above are the things I'd look to improve if I had to pay for or bring up the board.

 

[Stewieman01]

Thankyou so for the help! it was a bit counter intuitive at first removing vias while at the same time adding them and moving them for better plane connections, but once i actually did it i found it made a lot more sense. i moved the caps beneath the processor and found a few traces that didn't need after all, just some rejigging. I did find that there were a few traces I knew were possible to remove vias from, however it would take a vast redesign which i can worry about in the next iteration. I appreciated the critical feedback and how constructive it was, it really helped. Thanks again!

Alex