A PCB assembly includes a second PCB disposed adjacent to a first PCB and have a second hole facing a first hole, an upper plate disposed at an upper of the first and second hole and have a third hole disposed at the upper of the first hole and a fourth hole disposed at the upper of the second hole, a holder disposed at a lower of the first and second hole and have a lower plate having a fifth hole disposed at the lower of the first hole and a sixth hole disposed at the lower of the second hole, a first fixing screw penetrating through the third first, and fifth hole, and a second fixing screw penetrating through the fourth, second and sixth hole, and the lower plate includes a protrusion penetrating through the second PCB coupling the first PCB and the second PCB.