A layer (1) single free standing copper track (a micro-strip) of 0.40 mm width will have an impedance of 50 ohms with respect to a solid copper ground plane on layer (2).
You may have a top pcb 20mil trace 5 mm long, shorted to bottom's ground plane via a single via, and its impedance could be 80ohm (at few GHz for example).Z = 0.0000001 + j80So the impedance is "inductive" - it means the "via" behaves as a small inductor - that is important when you want to ground a decoupling capacitor though a single via for example, thus you must consider the physical sizes and material properties as well..
Nope, if the resistance or conductance per unit length are non zero
There's a lot of very informative theory being described here. Makes me want to read Heaviside's biography, :-). But what are the practical implications for OP laying out a PCB? When should he worry about the effective impedance of his traces? Probably not of major concern on boards with Arduino chips. ?
Please enter a valid email to subscribe
We need to confirm your email address.
To complete the subscription, please click the link in the
email we just sent you.
Thank you for subscribing!
via Egeo 16