An electronic device, comprising: a frame structure (118, 300), wherein the frame structure (118, 300) comprises: an outer metallic portion comprising a first metallic material and forming at least a portion of an outer surface of the electronic device; an inner metallic portion comprising a second metallic material different from the first metallic material and laterally surrounded by the outer metallic portion; and a first inner polymeric portion isolated from the inner metallic portion and at least partially laterally surrounded by the outer metallic portion; an organic layer between the outer metallic portion and the first inner polymeric portion; a metallic layer that comprises a third metallic material different from the first and second metallic materials and is interposed between the outer metallic portion and the inner metallic portion; and wherein the outer metallic portion further comprises a portion (321, 322) that is disposed between the inner metallic portion and the first inner polymeric portion and physically isolates the inner metallic portion and the first inner polymeric portion; and wherein the electronic device comprises a wireless communication circuit electrically connected to a portion of the outer metallic portion. a frame structure (118, 300), wherein the frame structure (118, 300) comprises: an outer metallic portion comprising a first metallic material and forming at least a portion of an outer surface of the electronic device; an inner metallic portion comprising a second metallic material different from the first metallic material and laterally surrounded by the outer metallic portion; and a first inner polymeric portion isolated from the inner metallic portion and at least partially laterally surrounded by the outer metallic portion; an organic layer between the outer metallic portion and the first inner polymeric portion; a metallic layer that comprises a third metallic material different from the first and second metallic materials and is interposed between the outer metallic portion and the inner metallic portion; and wherein the outer metallic portion further comprises a portion (321, 322) that is disposed between the inner metallic portion and the first inner polymeric portion and physically isolates the inner metallic portion and the first inner polymeric portion; and wherein the electronic device comprises a wireless communication circuit electrically connected to a portion of the outer metallic portion. an outer metallic portion comprising a first metallic material and forming at least a portion of an outer surface of the electronic device; an inner metallic portion comprising a second metallic material different from the first metallic material and laterally surrounded by the outer metallic portion; and a first inner polymeric portion isolated from the inner metallic portion and at least partially laterally surrounded by the outer metallic portion; an organic layer between the outer metallic portion and the first inner polymeric portion; a metallic layer that comprises a third metallic material different from the first and second metallic materials and is interposed between the outer metallic portion and the inner metallic portion; and wherein the outer metallic portion further comprises a portion (321, 322) that is disposed between the inner metallic portion and the first inner polymeric portion and physically isolates the inner metallic portion and the first inner polymeric portion; and wherein the electronic device comprises a wireless communication circuit electrically connected to a portion of the outer metallic portion.