The heat sources can be generated by passing an electrical current through the package and using the electrical resistance of the package. Concentrated light can also be directed onto the package causing the metal of the package to absorb the light and become heated.
The electrical energy and current can be as high as 10,000 Joules or 50,000 Amps and can be generated by passing a DC or AC current through the parts. The heating time is typically very short, in the range of milliseconds. The current can be “direct energy” from the mains passing in real-time though the power supply. DC currents are used for the most precise process and current control. AC currents have a longer minimal heating time (10 ms or more) and is a simpler technology. AC current can also be buffered in large capacitors (Capacitor Discharge Resistance Welding). This is typically used for larger currents. Amada Miyachi manufacturers and supplies all of these types of Resistance Welding power supplies.
The light energy is typically generated using a laser. The laser has a collimated beam with a single wavelength. Therefore, it can be focused onto a small spot size and a sufficient energy density can be achieved for melting metals. The laser beam is moved over the lid circumference to create a seal. The laser can be continuously switched on (CW lasers) or pulsed with pulses of a few milliseconds length. These types of lasers are Pulsed Nd-YAG lasers, Pulsed Fiber Lasers (Quasi Continuous Wave, or QCW lasers) and Continuous Wave Fiber lasers (CW Fiber lasers).
These lasers have a wavelength that is typically in the 1060 nm-1070 nm range. However, shorter wavelengths are beneficial for certain applications, as produced by the frequency doubled YAG lasers. Miyachi manufacturers and supplies all these types of lasers.