The method includes: a first step of forming, at a weld site of laminated layers of a metal foil, using a cutter having a longitudinal cross-sectional shape of a substantially V shape, a notch penetrating the laminated metal foil along a lamination direction and having a linear shape in a plan view, to cause the laminated layers of the metal foil closely contact each other in the lamination direction at an end of the notch; a second step of bringing a welding electrode into pressure contact with the weld site and then energizing the weld site via the welding electrode to perform resistance welding, and a forming step, performed between the first and second steps, of crushing the notch and a raised portion around the notch, to form a recess to thereby compress the notch and the raised portion in the lamination direction.

The method includes: a first step of forming, at a weld site of laminated layers of a metal foil, using a cutter having a longitudinal cross-sectional shape of a substantially V shape, a notch penetrating the laminated metal foil along a lamination direction and having a linear shape in a plan view, to cause the laminated layers of the metal foil closely contact each other in the lamination direction at an end of the notch; a second step of bringing a welding electrode into pressure contact with the weld site and then energizing the weld site via the welding electrode to perform resistance welding, and a forming step, performed between the first and second steps, of crushing the notch and a raised portion around the notch, to form a recess to thereby compress the notch and the raised portion in the lamination direction.

An apparatus and method for fastening dissimilar metals like steel and aluminum utilizes a steel rivet and a spot welding machine. The rivet and metals are stacked and the heat from the welder's electric current softens the lower melting point aluminum allowing the rivet to penetrate the aluminum and weld to the steel layer. The fastener may be used to join stacks with several layers of different materials and may be used to apply a threaded socket or stud made from steel or titanium to an aluminum or magnesium alloy structure. Layers of non-conductive materials like plastic and ceramics may also be affixed to a conductive layer using the fastener made from a compatible material that extends through a pilot hole.

An apparatus and method for fastening dissimilar metals like steel and aluminum utilizes a steel rivet and a spot welding machine. The rivet and metals are stacked and the heat from the welder's electric current softens the lower melting point aluminum allowing the rivet to penetrate the aluminum and weld to the steel layer. The fastener may be used to join stacks with several layers of different materials and may be used to apply a threaded socket or stud made from steel or titanium to an aluminum or magnesium alloy structure. Layers of non-conductive materials like plastic and ceramics may also be affixed to a conductive layer using the fastener made from a compatible material that extends through a pilot hole.

A packaged semiconductor device has a plurality of leads. A respective lead is to be welded to an electrical coupling that has a substantially rectangular end section. The end section has a width that is greater than a width of the respective lead. The respective lead is aligned within the width of the end section, such that the respective lead extends in a direction substantially perpendicular to the width of the end section. With the respective lead and the end section aligned, the respective lead is welded to the end section.

An apparatus and method for fastening layers of non-ferrous alloys, like aluminum, magnesium and copper utilizes a steel fastener and a spot welding machine. The fastener and metals are stacked and the heat from the welder's electric current softens the lower melting point aluminum allowing the fastener to penetrate the aluminum. A weld zone between the fastener and the various layers creates an internal weld. The fastener has a rough shaft that is coated by the molten weld zone and is hard to withdraw on solidification. Layers of non-conductive materials like plastics and ceramics may also be affixed to a conductive layer using a fastener made from a compatible material that extends through a pilot hole and welds to or penetrates a conductive layer. The fastener may have projections that initially reduce contact area with the stack.

An apparatus and method for fastening layers of non-ferrous alloys, like aluminum, magnesium and copper utilizes a steel fastener and a spot welding machine. The fastener and metals are stacked and the heat from the welder's electric current softens the lower melting point aluminum allowing the fastener to penetrate the aluminum. A weld zone between the fastener and the various layers creates an internal weld. The fastener has a rough shaft that is coated by the molten weld zone and is hard to withdraw on solidification. Layers of non-conductive materials like plastics and ceramics may also be affixed to a conductive layer using a fastener made from a compatible material that extends through a pilot hole and welds to or penetrates a conductive layer. The fastener may have projections that initially reduce contact area with the stack.

A method for welding multiple workpieces together includes applying a force to the multiple workpieces, generating ultrasonic vibration, transferring the ultrasonic vibration to the multiple workpieces to breakdown an oxide layer, generating an electric current, transmitting the electric current to heat up the workpieces, and synchronizing the ultrasonic and resistance heating operations. A welding system includes an ultrasonic vibration unit that generates an ultrasonic vibration and transfers the ultrasonic vibration to multiple workpieces to breakdown an oxide layer, a resistance heating unit that generates an electric current and transmits the electric current to heat up the workpieces, a workpiece mount that includes electrodes configured to receive the generated current and/or clamp the multiple workpieces during a welding process, and a controller configured to synchronize an operation of the ultrasonic vibration unit and an operation of a resistance heating unit.

A joint structure includes a first metallic material having a first projection, a second metallic material similar in type to the first metallic material and weldable to the first metallic material, and a different type of material having a first penetrating part and sandwiched between the first metallic material and the second metallic material, the different type of material being different in type from the first metallic material and the second metallic material and difficult to be welded to the first metallic material and the second metallic material. The first projection is smaller in diameter or width than the first penetrating part and is spaced from the rim of the first penetrating part by a first gap. The first projection is positioned in the first penetrating part and is spaced from the second metallic material by a second gap in the thickness direction of the first penetrating part. The second gap has a size of a predetermined percentage of the thickness of the first projection of the first metallic material to which arc welding id applied. The first metallic material and the second metallic material are melted and joined together inside the first penetrating part to compress and fix the different type of material, so that the different type of material, the first metallic material, and the second metallic material are fixed together.

A workpiece stack-up that includes at least a steel workpiece and an adjacent and overlapping aluminum workpiece can be resistance spot welded by a multi-stage spot welding method. The multi-stage spot welding method involves initially forming a weld joint between the steel and aluminum workpieces. The weld joint extends into the aluminum workpiece from the faying interface of the two workpieces and includes an interfacial weld bond area adjacent to and joined with the faying surface of the steel workpiece. After the weld joint is initially formed, the multi-stage spot welding method calls for remelting and resolidifying at least a portion of the weld joint that includes some or all of the interfacial weld bond area. At least a portion of the resultant refined weld joint may then be subjected to the same remelting and resolidifying practice, if desired. Multiple additional practices of remelting and resolidifying may be carried out.