The military use what is called mil-spec stuff, and virtually all of the components are from the civilian sector. The main goal of mil spec is that things are tested to a common standard per the standards. For example, the capacitor mentioned at the top of this article would not be specified specifically for military use, a rather more common electrolytic would be used. When it comes to satellite and space stuff, there the standards are higher more due to the external condition extremes of temp and bombardment by radiation in space.