You know, when it comes to PCB trace need to control impedance as 50 ohm, which is mainly determined by the signal parameters such as line width, line spacing, copper thickness, reference plane and dielectric thickness on the current PCB.
PS: There are virtually six factors affecting impedance:
W------ line width/line spacing; The impedance decreases with the increase of line width, and the impedance increases with the increase of distance;
H------ insulation thickness; As thickness increases, impedance increases;
T------ copper thickness; Copper thickness increases while impedance decreases;
H1----- solder mask thickness; Thickness increases while impedance decreases;
Er----- dielectric constant, reference layer; DK value increases while impedance decreases;
Undercut-----W1 - W2; Undercut increases and impedance increase.
