A method of electrically joining a first contact on a first wafer with a second contact on a second wafer, the first contact, a rigid material, and the second contact, a material that is malleable relative to the rigid material, such that when brought together the rigid material will penetrate the malleable material, the rigid and malleable materials both being electrically conductive involves bringing the rigid material into contact with the malleable material, applying a force to one of the first contact or the second contact so as to cause the rigid material to penetrate the malleable material, heating the rigid and malleable material so as to cause the malleable material to soften, and constraining the malleable material to within a pre-specified area.