Murata’s surface mount Y1 capacitors save in AC/DC switching power supplies
Murata has launched the DK1 series of surface mount, Y1, safety-certified, ceramic capacitors for low-profile power supplies. The capacitors are suitable for any AC/DC switching power supply, where a low-profile is required in compact audio-visual (AV) equipment, light emitting diode (LED) illumination, or 1U rack-mounted equipment.
Safety certified capacitors at the input side of a power supply line suppress noise that builds up primarily in commercial AC power lines, explains Murata. Such capacitors are usually leaded types, however that may be problematic where there is limited height above the printed circuit board (PCB) surface. In addition, says Murata, lead type capacitors are through-hole mounted, therefore 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, which adds to the challenge and complicates the device’s spatial layout.
Murata’s DK1 series Y1 capacitors use a structure of plate-shaped terminals on a disc-shaped ceramic dielectric which is placed within a plastic mould to reduce the terminal thickness found with lead type capacitors. This results in a mounted height of 2.5mm or less for the product, claims Murata, compared with a leaded type Y1 capacitor that would typically stand 11mm high. (Even laid on its side it would be 7mm, says Murata, 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 helps to reduce the profile for power supply devices subject to size limitations in compact AV equipment, LED illumination and 1U rack mounted equipment.
Connected from line to chassis, Y1 capacitors are a sub-class of capacitor with the highest performance requirements as classified by insulation type in the standard IEC 60384-14, which regulates the withstanding pressure and combustion resistance of capacitors connected to commercial power supplies to prevent fires and electric shock from electrical leakage. The capacitors also meet the requirements of certification standards UL (UL 60384-14), ENEC (EN 60384-14), CQC (IEC 60384-14) and KTC (KC 60384-14)
The DK1 series of capacitors measure 11.4 x 6.0 x 2.5mm and have a temperature range of -40 to 125 degree C. Available capacitance values are in the range 10 to 1500pF, and Y1 rated voltages of 250 and 300V AC RMS are available. Mass production of the capacitors begins this month.