I use a 0.4mm spacing between PCB traces (including 0.4mm space between crystal pads and ground) and I believe that's causing stray capacitance.
My circuit board is typical (1 ounce copper on FR4 fiberglass material with height 1.6mm). My ground plane is the largest possible without isolated planes.
I read that the distance between PCB traces has an inverse effect on stray capacitance.
Lets assume the non-ground traces are perfectly straight lines 10mm (1cm) and its thickness is 2.1mm
Given this information, how do I calculate stray capacitance between the traces?