KEMET capacitor families span ceramic, tantalum, polymer, film, aluminum electrolytic and specialty technologies. The brand name alone does not identify a capacitor's behavior or suitability. Select the exact ordering code from the required capacitance, voltage, tolerance, temperature, frequency, lifetime, package and qualification criteria.
Start with the capacitor technology
KEMET capacitor families cover multiple technologies and applications. Each technology has different strengths and limits. Multilayer ceramic capacitors can offer low impedance and compact size. Film capacitors are used where pulse capability, stability or low loss is important. Aluminum electrolytic and polymer families can provide higher capacitance, with different ESR, ripple-current and lifetime behavior. Tantalum products require careful review of surge, derating and fault conditions.
Do not substitute one technology solely because capacitance and rated voltage match. Verify polarity, failure mode, frequency response, environmental limits and assembly process.
Read the complete ordering code
Manufacturer part numbers often encode series, case size, dielectric or technology, capacitance, tolerance, voltage and packaging. Similar-looking codes can have different termination finishes, reliability levels or reel quantities. Use the current manufacturer datasheet and ordering guide for the complete code.
Confirm whether a product is active, not recommended for new design or discontinued. Record the approved manufacturer part number in the bill of materials and control alternates through engineering review. Distributor descriptions are helpful for search, but they are not a substitute for the manufacturer's specification.
Capacitance changes with real conditions
Nominal capacitance is measured under specified conditions. For some ceramic dielectrics, effective capacitance can fall with applied DC voltage and can also change with temperature, frequency and aging. Review the manufacturer's characteristic curves for the selected case size and voltage rating, then calculate the minimum effective capacitance needed by the circuit.
For electrolytic and polymer capacitors, include tolerance, temperature and lifetime changes. In timing, filtering, hold-up and resonant circuits, the worst-case value can matter more than the number printed on the label.
Voltage rating needs margin
Check steady-state voltage, startup, ripple and credible transients. Apply the manufacturer's derating guidance for the technology and application. A voltage rating is not a promise that every repetitive surge or reverse-voltage event is acceptable.
For mains-connected, isolation or suppression applications, use capacitors with the required safety approval and class. A general high-voltage capacitor is not automatically an X or Y safety capacitor. Confirm approval markings and current certification for the exact part.
ESR, ripple current and temperature are linked
Capacitor loss produces heat. Review ESR or dissipation factor at the relevant frequency and temperature, along with ripple-current limits and thermal conditions. PCB copper, airflow, nearby heat sources and mounting affect operating temperature.
For aluminum electrolytic capacitors, lifetime is strongly related to temperature and applied stress. Use the series lifetime model and application guidance rather than assuming a universal doubling rule. Validate the calculated margin with measured ripple current and case temperature on representative hardware.
Mechanical and assembly details matter
Confirm dimensions, land pattern, height, polarity, lead spacing and packaging. For MLCCs, board flex and depanelization can create cracks; review placement, orientation and handling guidance. For moisture-sensitive or reflow-limited parts, follow the documented storage and soldering profile.
Automotive or other qualified products must be identified by the exact qualified series and ordering code. A component made by a supplier that offers automotive products is not necessarily automotive qualified.
Practical review checklist
- Choose the technology from the circuit and fault requirements.
- Calculate worst-case effective capacitance.
- Check voltage, ripple current, ESR and thermal margin.
- Verify package, polarity and assembly constraints.
- Confirm qualification, lifecycle and traceability requirements.
- Test the selected part in production-intent hardware.
- Approve substitutes only after technical comparison.
For procurement, provide the complete KEMET ordering code, quantity, packaging, date-code and documentation requirements. See our passive component sourcing page or send the bill of materials through our contact page.
