Patent ID: 8441327

Claim:
A printed circuit board comprising: an insulation layer; and a signal layer attached to the insulation layer, the signal layer comprising a pair of differential transmission lines, wherein width W of each of the differential transmission lines is changed according to change of space S between the differential transmission lines, based on the following formula: W = C ⁢ ⁢ 1 × ⁢ H × ( C ⁢ ⁢ 2 × H 0.8 ⁢ W 0 + T ) C ⁢ ⁢ 3 × ⅇ C ⁢ ⁢ 4 × S 0 H - 1 1 - C ⁢ ⁢ 3 × ⅇ C ⁢ ⁢ 4 × S H - 1.25 ⁢ T wherein C1=7.475, C2=5.98, C3=0.48, C4=−0.96, H is a thickness of the insulation layer, W 0 is an original width of each of the differential transmission lines, and S 0 is an original space between the differential transmission lines, and T is a thickness of each of the differential transmission lines.