A thermal expansion coefficient of a module substrate 8 is different from that of a package substrate. There is not any place where stresses generated in Interfaces between soldering balls 5 and the substrate are released. These stresses are largely applied to soldering bond, the soldering balls are strained, deformed, or cracked, and there has been a problem in long-time reliability. Slits are disposed on opposite sides of each soldering ball in a vertical direction to a side in an outer peripheral side of the package substrate, accordingly the stresses applied to the soldering balls are weakened, and the soldering balls are prevented from being strained, deformed, or cracked. When soldering strains are reduced in this manner, there can be provided a surface mounting type semiconductor package and system module having high reliability, low cost, and satisfactory electric characteristics such as low capacitance and low inductance.