Surface mount capacitors save valuable space in compact equipment

Murata has launched the DK1 series of surface mount, Y1 safety certified ceramic capacitors for low-profile power supplies. The capacitors are ideal for any AC-DC switching power supply where a low-profile is needed for use in compact AV equipment, LED illumination, or 1U rack mounted equipment. 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. The company’s new capacitors use a structure of plate-shaped terminals on a disc-shaped ceramic dielectric placed within a plastic mold to reduce the terminal thickness that is present with lead type capacitors, resulting in a mounted height of 2.5mm 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 7mm and still the insulation clearance problem on the underside of the PCB exists. Measuring just 11.4mm x 6mm x 2.5mm (L x W x thickness) the capacitors feature a useable temperature range of -40C to 125C. Available capacitance values are in the range 10 to 1500pF, and Y1 rated voltages of 250VAC and 300VAC RMS are available.