This ends up as a prototype anyway because I lack components to optimize for production. I am using 4 layers this time because I want better isolation between signals. I can mosly route on a single layer, but I had some bad experience with signal integrity on 2 layers. This is the first time I use more than 2 layers and the cost increases quite a bit as well.
I have plenty of spare pins since I used a 64 pin MCU so I will be adding some extras on the back – I am even considering a SD card – lets see -it don’t cost anything to add PCB layout and I don’t have to mount it – this could be a very interesting module at the end.
One drawback is that the mini module cover the screw holes. This will make it difficult to fix this to the motherboard with the W5500 module soldered on, but it is doable.