Komarov Artem noted that connecting conductive parts to achieve electrical contact is one of the oldest and most common connection methods. The technologies used in almost every industry depend on cost, connection characteristics and volume requirements.
Joining two materials, at least one of which is less than 0.5 cm thick, requires a technique called microwelding. Copper is generally the material of choice for joining conductive parts using microwelding due to its ability to conduct electrical energy and transmit signals. However, the very high thermal conductivity that makes copper such a good choice as a conductor quickly conducts heat away from the weld joint, making it difficult to maintain thermal balance and weld reliability. This difficulty is further exacerbated by trends toward increased productivity, smaller part sizes, and welding of dissimilar materials and conductor sizes.
The challenge of copper microwelding is to control the thermal balance in these small, highly conductive parts without overheating or underheating. One way to solve this serious problem is to use a wavelength of 532 nanometers (nm). Because 532 nm is in the green wavelength band of the visible light spectrum, it is also called “green.”
Micro welding of copper conductive components can be done using ultrasonic bonding, resistance welding and laser welding. Each has its own advantages and disadvantages, and each address microwelding requirements slightly differently.
Ultrasonic bonding. Ultrasonic bonding, well suited for welding sheet metal, especially conductive materials such as copper and aluminum, uses vibration energy at the joint interface to create a joint.
Contact welding. Resistance welding uses the high resistance of the weld surface to create heat as current passes through the workpiece.
In resistance welding of conductive parts, the electrodes are resistive and therefore serve two functions: they heat up and transfer heat to the workpieces, and they conduct enough current to provide some heating at the joint interface.
Resistance welding is well suited for many applications and materials. However, since the process relies on mechanical contact and the need to create an electrical circuit between two electrodes, it may not work properly under all circumstances, especially if the parts are mechanically fragile.
Laser welding. Laser welding is a non-contact process requiring only one-way access. This technology is useful for working on very small joint areas and can be used for welding parts of various shapes and different joint geometries.
Microwelding of conductive materials such as copper is a complex task, but laser welding offers a useful non-contact joining method that is well suited for automation, Artem Komarov emphasized.