According to an embodiment, an electronic device may include a first printed circuit board (PCB), a second PCB having a shape corresponding to the first PCB, and an interposer surrounding a space between the first PCB and the second PCB and including multiple pads, wherein the interposer may include a first surface in contact with the first PCB, a second surface in contact with the second PCB, a first lateral surface facing the space, and a second lateral surface opposite to the first lateral surface, and a first point exposed through the second lateral surface, a second point exposed through one of the first lateral surface or the second lateral surface, and a heat conduction pattern disposed on the first surface in an area between the multiple pads to connect the first point and the second point.