Patent ID: 8023268

Claim:
A printed circuit board unit comprising: a package substrate; a semiconductor element mounted on a front surface of the package substrate; a terminal bump set placed on a back surface of the package substrate, the terminal bump set including an outermost bump row inscribed in a first prism standing upright on the front surface of the package substrate; a heat conductive member contacting with a surface of the semiconductor element, the heat conductive member extending outward beyond a contour of the semiconductor element; a heat dissipating member contacting with a surface of the heat conductive member; a reinforcing member interposed between the heat conductive member and the package substrate at a position outside the contour of the semiconductor element, the reinforcing member bonded to the front surface of the package substrate at a predetermined bonding area and contained inside a second prism, the predetermined bonding area extending inward from an outer periphery of the package substrate over the front surface of the package substrate, the second prism standing upright on the front surface of the package substrate inside the first prism so as to allow the outermost bump row to circumscribe the second prism; an auxiliary reinforcing member interposed between the heat conductive member and the package substrate at a position outside a contour of the reinforcing member, the auxiliary reinforcing member contacting the package substrate without bonding, the auxiliary reinforcing member being placed inside the first prism and outside the second prism; a motherboard having a surface receiving the terminal bump set; and an urging mechanism exhibiting an urging force urging the heat conductive member toward the motherboard, wherein the heat conductive member extends outward beyond a contour of the reinforcing member.