Semiconductor device
A semiconductor device comprising a substrate, a semiconductor element mounted on the substrate, an inner annular stiffener provided on the substrate in an outer side of the semiconductor element, and an outer annular stiffener provided on the substrate in an outer side of the inner annular stiffener. The inner annular stiffener and the outer annular stiffener are made of different materials. Particularly, the thermal expansion coefficient of the inner annular stiffener is selected to be smaller than that of the substrate, and the thermal expansion coefficient of the outer annular stiffener is selected to be larger than that of the substrate. The amount of deformation of the substrate is thus decreased.
1. A semiconductor device comprising a substrate, a semiconductor element mounted on said substrate, an inner annular stiffener provided on said substrate in an outer side of said semiconductor element, and an outer annular stiffener provided on said substrate in an outer side of said inner annular stiffener, wherein said inner annular stiffener and said outer annular stiffener are made of different materials.
2. A semiconductor device according to claim 1 , wherein said inner annular stiffener and said outer annular stiffener are made of a metal material.
3. A semiconductor device according to claim 1 , wherein said substrate is made of an organic resin material.
4. A semiconductor device according to claim 1 , wherein said inner annular stiffener and said outer annular stiffener are provided on the substrate on the same side as the semiconductor element.
5. A semiconductor device according to claim 1 , wherein solder balls for connection to the wiring board are provided on the substrate on a side thereof opposite to the side mounting semiconductor element.
6. A semiconductor device according to claim 1 , wherein the thermal expansion coefficient of the inner annular stiffener is smaller than that of the outer annular stiffener.