Abstract: A radioactive power source resident in an IC package is provided. The power source is a stand-alone device, fabricated separately from the IC or other device that is eventually attached to the package. The power source may be attached to the packaging substrate or to another portion of the package such as the package's top member or lid. The source can be directly coupled to the mounted IC, for example via package leads, or coupled to package pins. By coupling the source to the package pins, the system provides even greater flexibility. Although the power source can use any of a variety of different cell designs, preferably an icosahdedral boride based beta cell is used.