a light receiving element is comprised of a light sensitive surface on a semiconductor substrate and a positive electrode , a negative electrode , a mounting precision test mask , a conductive electrode wire , and solder resist on the same substrate surface . a metal thin film , a mounting alignment mark , and a mounting precision mark window are provided on the back side of the substrate . two or more electrode surfaces having either the anode or the cathode used as the common electrode are provided . the light sensitive surface is positioned approximately in the center between these two electrode surfaces . a highly precise mounting can therefore be achieved with the solder bump , even when mounting single light receiving elements . high precision mounting is also obtained when mounting light receiving element arrays . this type of light receiving element can be precisely positioned and bonded by solder bumps to a substrate having an optical fiber fitted in the v groove .