By Warren Miller, contributing writer

Capacitors are one of the many electronic devices that don’t get as much respect as they deserve. Without these workhorse devices, your design wouldn’t have power and be able to withstand power-line noise or generate most analog signals. In high-reliability applications, it can be critical to find capacitors with stable and precise characteristics. This roundup looks at a few of the most recent announcements of capacitors with high precision and stability.

Knowles Novacap high-reliability MLCCs

The Novacap multilayer ceramic capacitors (MLCCs) from Knowles are RoHS-compliant, high-capacitance BME MLC chip capacitors manufactured in stable Class II dielectrics X7R and X5R. They have a capacitive range from 6.8 nF up to 100 μF with tolerances of ±10% and ±20%.

Because of the extremely low equivalent series resistance (ESR) characteristics, the MLCCs can be used as replacements for tantalum and low-ESR electrolytic capacitors without polarity concerns, according to the company.

These devices can be used as power supply bypass capacitors, smoothing capacitors, input/output filters in DC/DC converters, and in digital circuits and LCD modules. All parts are available with high-reliability screening.

Nickel barrier termination options include tin, tin/lead, or gold flash. The gold-flash option eliminates the tin “whiskering” issue, which has become prevalent because pure tin-plated terminations, required to comply with the RoHS directive to eliminate lead, “allow tin whiskers to grow from surfaces and can cause electrical short-circuits and failures,” said the company. This type of failure is of special concern in high-reliability applications such as medical implantable devices and military equipment.

Novacap MLCCs from Knowles. Image source: Knowles.

KEMET X7R 250-V MLCCs

KEMET has expanded its X7R 250-V MLCC series to include smaller case sizes and increased capacitance values. Saving PCB space by using compact surface-mount technology footprints, the extended portfolio now offers a capacitance range of 10 pF to 47 μF in case sizes as small as 0603. These characteristics can be critical in achieving higher voltages in automotive applications such as lighting, electric charging, sensors, and electromagnetic interference (EMI) suppression. The 220-V power system and small case sizes make them well-suited for high-power, small-form-factor applications.

KEMET’s X7R dielectric features a 125°C maximum operating temperature. “X7R exhibits a predictable change in capacitance with respect to time and voltage, with a minimal change in capacitance with reference to ambient temperature,” according to KEMET. “Capacitance change is limited to ±15% from −55°C to 125°C.”

TDK soft-termination MLCCs with low ESR

TDK Corp. claims the industry’s first soft-termination MLCCs with low ESR. The new CN series features terminal electrodes with a conductive resin layer that provides high mechanical robustness to protect against board flexure. Specs include capacitance values ranging from 2.2 µF to 22 µF and rated voltages from 16 V to 100 V. The MLCCs are available in commercial-grade and automotive-grade X7R dielectric.

“Soft-termination MLCCs, which can withstand the stress from board flexure, are an effective way to prevent short circuits when used in battery lines,” said TDK. “Conventional designs that coat the electrodes completely with resin, however, lead to higher ESR and losses.”

TDK said that it “has achieved the low terminal resistance values by applying the conductive resin layer only where the terminal electrode contacts the PCB.” Target applications include battery lines in automotive and industrial robot applications, “where they help to improve system reliability”. Other applications include automotive ECUs, advanced driver assistance systems (ADAS), and automated driving systems.