source: Electronic Specifier article
20th November 2015
News Release from: Syfer Technology Limited
Written by : Jordan Mulcare
Design engineers looking for capacitors to have a more defined change of capacitance with applied with voltage can now specify the VC1 range from Knowles Capacitors brand, Syfer Technology. This residual capacitance range of X7R MLCCs are designed to not drop more than 50% of their cap value from the 1Vrms 1kHz value, all the way up to full rated DC voltage at room temperature.
In ceramic capacitors, generally speaking, the more stable the dielectric the lower the available capacitance value. There is often a trade-off to be made with the most stable, lowest loss, zero ageing Class 1 dielectric materials only producing low capacitance values. However, developments in materials and processing technology, plus an increased understanding of capacitor design and failure modes over time, has led to Syfer making vast improvements in MLC volumetric efficiency. The ceiling of, say, 56nF for a 1kV 1812 case size part 10 years ago has increased to 180nF today.
The VC1 range can be operated continuously at full rated voltage, but if de-rated will maintain a larger percentage of their original capacitance value. For example, if operated at 80% of the rated voltage the capacitance value will reduce to something near 60%. Defined capacitance value in case sizes from 0805 to 3640, with voltage rating up to 3kV.