With a new expanded range of enhanced safety-certified multilayer ceramic capacitors (MLCCs), Knowles Precision Devices now offers a combination of capability and safety certification for electronic device applications. These new surface-mount MLCCs comply with international UL60384-14 and EN60384-14 specifications and can be used instead of leaded film capacitors in AC-DC power supplies where a lightning strike or other voltage transients represent a threat to the electronic equipment.
In general, there are two classes of capacitors, Class-X and Class-Y that are both used to minimize electromagnetic interference (EMI) and radio frequency interference (RFI) in different applications. Class-X capacitors offer line-to-line protection, which means if there is a failure, a short may occur but there is no risk of shock. Class-Y capacitors offer line-to-ground protection, which generally means that if a failure with the ground occurs, there is a risk for shock. However, since Class-Y safety capacitors have met rigorous specifications, the risk of a component failure that may result in a fatal electric shock hazard is minimized. Knowles has designed both Class-X and Class-Y MLCCs, and the general electrical details of this new safety-certified product line are summarized in the table below.
A Comprehensive Family of Safety-Certified MLCCs
Knowles' new line of safety-certified MLCCs meet class Y2/X1, X1, and X2 requirements. The guidelines for each of these subclasses are determined by the IEC-60384-14 standard by looking at the peak voltages the capacitor can withstand under different conditions as summarized in the table below.
Within these different subclasses, Knowles now offers four separate families of MLCCs with the following specifications for each family:
- SYX/UYX family – Y2 (250Vac)/X1 (305Vac) – Guaranteed 4mm creepage class Y2/X1 safety capacitors that feature a humidity robustness grade III rating and have a 5kV impulse and a 1kVdc rating approved by TUV and UL. All components are 100 percent DWV tested to 4kV and AQL tested to 4kVdc and 3000Vac. Chip sizes include 1808, 1812, 2211, 2215, and 2220. The SYX/UYX family is ideal for use in the high-voltage battery systems used in electric vehicles.
- SYS family – Y2 (250Vac)/X1 (305Vac) – These are class X1/Y2 safety capacitors that have a humidity robustness grade III rating and 5kV impulse and a 1kVdc rating approved by TUV and UL. Chip sizes include 1808 and 1812. This family of MLCCs meets the X1 requirements for all applications and is suitable for use in equipment within the scope of IEC 62368 including audio/video and information and communication technology equipment as a class Y2 component
- S3X family – X2 (305Vac) – Offers class 305Vac X2 safety capacitors including a humidity robustness grade III rating and 2.5kV impulse and a 1kVdc rating approved by TUV, UL, and CQC.
- S2X family – X2 (250Vac) – Class X2 250Vac safety capacitors with a humidity robustness grade III rating and 2.5kV impulse and a 1kVdc rating approved by TUV, UL, and CQC.
All sizes of Knowles’ safety capacitors within each family are also available with a FlexiCap termination. FlexiCap is their proprietary flexible epoxy polymer termination material that is applied to the device under the usual nickel barrier finish. FlexiCap will accommodate a greater degree of board bending than conventional capacitors to reduce the risk of mechanical cracking.
In addition to ensuring safety requirements are met, this new line of safety-certified MLCCs offers additional benefits such as simple pick-and-place assembly, a reduction in required board space and a lower profile. And, with Knowles’ high-voltage capacitor expertise, they offer one of the highest available capacitance range values in certain case sizes.
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