I'm connecting two BGAs (0.8mm pitch) which are DDR3 signals. Vendor recommends 40 and 80 ohm for SE and diff traces.
My PCB manufacturer suggests the following specifications for the diff traces:
Width: 10 mils Distance: 7 mils Thickness: 0.67 mils Dielectric: 5.1 mils di.constant:4.2
For single ended, the trace will have to be even wider. Breaking out from the BGAs, this is clearly not possible. I am new to PCB design, but it seems to me that 12 mils traces are rather huge relative to the size of the ICs.
The only information I've found about this width change and the challenges of breaking out/fanning out in this relation is simply "it's complicated".
I'm using Kicad and the number of available simulation tools is limited. How can I make sure that the impedance is controlled within reasonable accuracy?