# US 2014/0197148 A1 · Structure and method of bonding copper and aluminum > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2014/0197148 A1 - Document ID: US20140197148A1 - Status: Published application - Kind: A1 - Application number: 13/741,454 - Filed: 2013-01-15 - Published: 2014-07-17 - Earliest claimed: 2013-01-15 - Assignees: Fronius International GmbH; GM Global Technology Operations LLC - Applicants: GM Global Technology Operations LLC; Fronius International GmbH - Inventors: Chih-Chang Chen; Corey Simone - Web page: https://patentgrep.com/patent/US20140197148A1 ## CPC - B23K 9/0008: {Welding without shielding means against the influence of the surrounding atmosphere} - B23K 9/232: {of different metals} - B23K 9/235: Preliminary treatment - B23K 35/286: {Al as the principal constituent} - B23K 35/302: {Cu as the principal constituent} - B23K 35/365: Selection of non-metallic compositions of coating materials either alone or conjoint with selection of soldering or welding materials - B32B 15/01: all layers being exclusively metallic {(making layered metal workpieces by pressure cladding B23K20/22; making coatings with a metallic material characterised by its composition C23C30/00)} - B32B 15/017: {one layer being formed of aluminium or an aluminium alloy, another layer being formed of an alloy based on a non ferrous metal other than aluminium} - B23K 2103/10: Aluminium or alloys thereof - B23K 2103/12: Copper or alloys thereof - Y10T 428/12736: Al-base component - B23K: SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM - B32B: LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM - Y10T: TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION ## Abstract A bonded structure of aluminum and copper is formed by bonding a copper workpiece and an aluminum workpiece together along a joint via an arc welding process. The copper workpiece has a first coating, having a lower melting point than copper, applied to at least a portion of it. The first coating allows the copper workpiece to be wetted and brazed, while the aluminum workpiece is melted and fused along the joint. The arc welding process involves the cyclic alternating of a first stage, in which an electric current is supplied to a welding wire as it is moved toward the workpieces, and a second stage, in which the electric current is reduced and the welding wire is moved away from the workpieces, to generate and detach a plurality of molten droplets along the joint. Each molten droplet is formed from the welding wire in the first stage. ## Claims ### Claim 1 A method of bonding a first metallic workpiece and a second metallic workpiece having different melting points and thermal conductivities, the method comprising: applying a first coating to at least a portion of the first metallic workpiece, the first coating being made of a material having a lower melting point than the material of the first metallic workpiece; positioning the first metallic workpiece and the second metallic workpiece with respect to each other to form at least one joint where the two metallic workpieces are to be bonded; and welding the first metallic workpiece to the second metallic workpiece along the at least one joint via an arc welding process including a welding wire such that the first metallic workpiece is wetted and brazed, and the second metallic workpiece is melted and fused along the at least one joint; wherein the arc welding process involves a cyclic alternating of a first stage, in which an electric current is supplied to the welding wire as it is moved toward the workpieces, and a second stage, in which the electric current is reduced and the welding wire is moved away from the workpieces, to generate and detach a plurality of molten droplets along the at least one joint, the molten droplets being formed from the welding wire in the first stage. ### Claim 2 (depends on 1) The method of claim 1 wherein the materials of the first metallic workpiece and the second metallic workpiece are copper and aluminum, respectively. ### Claim 3 (depends on 1) The method of claim 1 wherein the material of the first coating is zinc. ### Claim 4 (depends on 1) The method of claim 1 wherein the material of the welding wire is an aluminum alloy. ### Claim 5 (depends on 1) The method of claim 1 further comprising applying a second coating to the first metallic workpiece at substantially the same location as the first coating, prior to applying the first coating, wherein the second coating is made of a material having a higher melting point than the material of the first metallic workpiece. ### Claim 6 (depends on 5) The method of claim 5 wherein the material of the second coating is nickel. ### Claim 7 (depends on 1) The method of claim 1 wherein the first coating is applied via an electrolytic plating process. ### Claim 8 A method of bonding an aluminum workpiece to a copper workpiece via an arc welding process including a welding wire, the method comprising: applying a first coating to at least a portion of the copper workpiece, the first coating being made of a material having a lower melting point than copper; positioning the copper workpiece and the aluminum workpiece with respect to each other to form at least one joint where the two workpieces are to be bonded; and welding the aluminum workpiece to the copper workpiece along the at least one joint via the arc welding process such that the aluminum workpiece is melted and fused, and the copper workpiece is wetted and brazed along the at least one joint; wherein the arc welding process involves a cyclic alternating of a first stage, in which an electric current is supplied to the welding wire as it is moved toward the workpieces, and a second stage, in which the electric current is reduced and the welding wire is moved away from the workpieces, to generate and detach a plurality of molten droplets along the at least one joint, the molten droplets being formed from the welding wire in the first stage. ### Claim 9 (depends on 8) The method of claim 8 wherein the material of the first coating is zinc. ### Claim 10 (depends on 8) The method of claim 8 wherein the material of the welding wire is an aluminum alloy. ### Claim 11 (depends on 8) The method of claim 8 further comprising applying a second coating to the copper workpiece at the same location as the first coating, prior to applying the first coating, wherein the second coating is made of a material having a higher melting point than copper. ### Claim 12 (depends on 11) The method of claim 11 wherein the material of the second coating is nickel. ### Claim 13 (depends on 8) The method of claim 8 wherein the first coating is applied via an electrolytic plating process. ### Claim 14 A bonded structure of copper and aluminum, the structure comprising: a first metallic workpiece made of copper; a first coating applied to at least a portion of the first metallic workpiece, the first coating being made of a material having a lower melting point than copper; and a second metallic workpiece made of aluminum, the second metallic workpiece being positioned with respect to the first workpiece to form at least one joint where the two metallic workpieces are bonded; wherein the first metallic workpiece and the second metallic workpiece are bonded via an arc welding process including a welding wire such that the first metallic workpiece is wetted and brazed, and the second metallic workpiece is melted and fused along the joint; and wherein the arc welding process involves a cyclic alternating of a first stage, in which an electric current is supplied to the welding wire as it is moved toward the workpieces, and a second stage, in which the electric current is reduced and the welding wire is moved away from the workpieces, to generate and detach a plurality of molten droplets along the at least one joint, the molten droplets being formed from the welding wire in the first stage. ### Claim 15 (depends on 14) The bonded structure of claim 14 wherein the material of the first coating is zinc. ### Claim 16 (depends on 14) The bonded structure of claim 14 wherein the material of the welding wire is an aluminum alloy. ### Claim 17 (depends on 14) The bonded structure of claim 14 further comprising a second coating applied to the first metallic workpiece beneath the first coating, the second coating being made of a material having a higher melting point than copper. ### Claim 18 (depends on 17) The bonded structure of claim 17 wherein the material of the second coating is nickel.