A printed circuit board (120) includes an insulating substrate (120a) on which conductive films (120b) are formed. Semiconductor devices (8) disposed external to the printed circuit board (120) have their leads (24a, 24b, 24c) connected to the conductive films. A flexible portion (30) is formed in the insulating substrate (120a) at a location near the location where the leads (24a, 24b, 24c) are connected to the conductive films (120b).