In a case where the first component and the third component are mountable on the first circuit board pattern of the first individual board and the second component is mountable on the second circuit board pattern of the first individual board, or in a case where the first component is mountable on the first circuit board pattern of the second individual board, and the second component and the third component are mountable on the second circuit board pattern of the second individual board, in the first and second individual boards, traces for the third component are provided so that electrical connections between the third component and the other components are identical between the case where the third component is mounted on the first circuit board pattern, and the case where the third component is mounted on the second circuit board pattern.