Surface mount Y1 capacitors with 2.5mm height save valuable space

May 15, 2017 // By Nick Flaherty
Murata DK1 Y1 capacitors
Murata has launched a range of surface mount, Y1 safety certified ceramic capacitors for low-profile power supplies.

The DK1 series capacitors are aimed at any AC-DC switching power supply where a low-profile is needed. They 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. This compares to 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.

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 equipment 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 new design also enables reflow surface mounting, and there is no longer a need to provide an insulating distance at the underside of the PCB. This helps reduce the profile of power supply designs in compact AV equipment, LED illumination and 1U rack mounted equipment.

Connected from line to chassis, Y1 capacitors are a subclass of capacitor with the highest performance requirements as classified by insulation type in the standard IEC 60384-14, an international standard that regulates the withstanding pressure and combustion resistance of capacitors connected to commercial power supplies from the standpoint of preventing fires and electric shock from electrical leakage. The capacitors also meet the requirements