An electronic component unit is provided with two electronic components which are disposed in parallel with each other and each of which has an internal electric circuit therein. Electrode pads are provided on the opposed surfaces of the two electronic components and are electrically connected to the internal electric circuits. The pads on one of the electronic components are respectively electrically and mechanically connected to the corresponding pads on the other electronic component by solder bumps. The areas of the pads increase or decrease stepwise in the direction from the central portions toward the outer peripheral edges of the two electronic components, while the volumes of the solder bumps are constant. Alternatively, the volumes of the solder bumps decrease or increase in the direction from the central portions toward the outer peripheral edges of the two electronic components, while the areas of all pads are constant. Each of the pads of the two electronic components is bonded to an associated solder bump over the whole area of the pad, whereby the shapes of the solder bumps respectively connected to the pads of the two electronic components change in the direction from the central portions toward the outer peripheral edges of the two electronic components to provide the solder bumps with different durabilities to stress, thereby assuring high reliability of the connection between the two electronic components.