Disclosed is a printed circuit board assembly comprising: a first printed circuit board; a second printed circuit board stacked with the first printed circuit board; and an interposer arranged between the first printed circuit board and the second printed circuit board, wherein the second printed circuit board includes a first part and a second part extending in a first direction from a part of the first part and wherein a length of the second part in a second direction perpendicular to the first direction is less than a length in the second direction of the first part, and wherein the direction of a first conductive pattern formed on the first part and the direction of a second conductive pattern formed on the second part are substantially perpendicular to each other.