Surface mount Y1 capacitors save space in confined designs
Safety certified capacitors are deployed at the input side of a power supply line in order to suppress noise that builds up primarily in commercial AC power lines. Such capacitors are usually of the leaded type, however that configuration can be problematic where there is limited height above the PCB surface, hindering efforts to make low-profile equipments and limiting component layout. In addition, because lead type capacitors are through-hole mounted, the lead wires are exposed on the underside of the circuit board. A fixed amount of insulating distance between the exposed lead wires and the metal components of the device is required by safety standards, compounding the problem and complicating the spatial layout within a device.
DK1 series Y1 capacitors use a structure of plate-shaped terminals on a disc-shaped ceramic dielectric placed within a plastic mould to reduce the terminal thickness that is present with lead type capacitors, resulting in a mounted height of 2.5 mm or less for the product. Compare this with a leaded type Y1 capacitor that would typically stand 11 mm high, and even laid on its side it would be 7 mm and still the insulation clearance problem on the underside of the PCB exists.
The component format enables reflow surface mounting, and there is no longer a need to provide an insulating distance at the underside of the PCB. This advances profile reduction for power supply devices subject to size limitations in compact AV equipment, LED illumination and 1U rack mounted equipment, for which spatial design has been difficult in the past.
Murata; www.murata.com
