NOJB686M006RWJ

FAQFrequently Asked Questions

• Can the NOJB686M006RWJ be used as a direct replacement for tantalum capacitors in legacy designs, and what are the key differences in behavior I should account for? The NOJB686M006RWJ niobium oxide capacitor can often replace tantalum capacitors of similar voltage and capacitance ratings, but several design considerations apply. Niobium oxide capacitors like the NOJB686M006RWJ exhibit lower failure rates under surge conditions and do not exhibit the same catastrophic short-circuit failure mode as tantalum. However, the NOJB686M006RWJ has a ±20% capacitance tolerance compared to tantalum's typical ±10%, which may affect filter performance or frequency response in precision circuits. The ESR of 1.5 Ohms in the NOJB686M006RWJ is relatively high compared to some modern tantalum grades, so ripple current handling and thermal behavior should be re-evaluated. If your original tantalum design operated near voltage limits, the NOJB686M006RWJ's 6.3 V rating offers identical headroom, but ensure DC bias does not exceed this value or capacitance will degrade significantly.
• What ripple current and thermal management factors should I consider when using the NOJB686M006RWJ in a switching power supply output filter? The NOJB686M006RWJ's ESR of 1.5 Ohms will generate resistive heating under ripple current conditions according to I²R losses. In a switching supply, if ripple current through the NOJB686M006RWJ reaches 1 A at 100 kHz, dissipation will be approximately 1.5 W, raising the capacitor's temperature significantly above ambient. The NOJB686M006RWJ's maximum operating temperature of 105°C means you must ensure the capacitor does not exceed this limit, leaving limited margin if the PCB environment is already warm. For high-ripple applications, consider using multiple NOJB686M006RWJ capacitors in parallel to distribute current and reduce individual device heating, or evaluate lower-ESR alternatives if available at your voltage and capacitance point. The NOJB686M006RWJ's dissipation factor of 20% also contributes to self-heating, particularly under sustained AC stress.
• How does the ±20% capacitance tolerance of the NOJB686M006RWJ affect circuit performance in timing or filtering applications? The NOJB686M006RWJ carries a ±20% tolerance, meaning actual capacitance may range from 54.4 µF to 81.6 µF across production lots and temperature extremes. In RC timing circuits, this directly shifts the time constant by up to 20%, which may violate system specifications unless your design includes calibration or redundancy. In filter applications, ±20% tolerance shifts the corner frequency by roughly the same percentage, potentially moving the cutoff into or out of your intended passband. If your design requires tighter control, you must either select a tighter-tolerance capacitor grade, add adjustable components to trim the circuit, or validate that your system can tolerate the full ±20% variation without performance degradation. The NOJB686M006RWJ tolerance is typical for niobium oxide capacitors and reflects the inherent process variability of the technology, so alternative niobium oxide suppliers will exhibit similar behavior.
• Is the NOJB686M006RWJ rated for use in medical devices or aerospace applications, and what certifications apply? The NOJB686M006RWJ is RoHS3 compliant and carries an MSL (Moisture Sensitivity Level) rating of 1, indicating unlimited shelf life and minimal moisture sensitivity. However, the NOJB686M006RWJ does not carry explicit medical device (ISO 13485) or aerospace (AS9100) qualification in its standard datasheet. If your application requires these certifications, contact KYOCERA AVX directly to confirm whether screened or qualified versions of the NOJB686M006RWJ exist. For medical applications, additional concerns include biocompatibility of materials and long-term reliability under extended storage or repeated temperature cycling. For aerospace applications, radiation tolerance and performance under vacuum conditions require specific validation. The NOJB686M006RWJ's ECCN classification of EAR99 means it is generally available for export but does not itself indicate suitability for restricted end-use categories.
• What is the leakage current behavior of the NOJB686M006RWJ over temperature, and how does it affect precision analog circuits? The NOJB686M006RWJ specifies a leakage current of 8.2 µA at rated voltage and temperature. Niobium oxide capacitors, including the NOJB686M006RWJ, exhibit temperature-dependent leakage that typically doubles for every 10–15°C increase, meaning leakage may reach 20–30 µA or higher near 105°C. In precision analog applications such as sample-and-hold circuits or transimpedance amplifier feedback networks, this leakage appears as a parasitic current path that introduces error. If your circuit requires leakage below 1 µA, the NOJB686M006RWJ is not suitable; consider ceramic capacitors or film capacitors instead. For bias circuits or filtering where occasional tenths-of-microampere leakage is tolerable, the NOJB686M006RWJ performs adequately. Measure leakage over your expected temperature range during prototype validation to confirm the circuit meets specifications.
• Can the NOJB686M006RWJ withstand surge or transient voltages beyond its 6.3 V rating, and what design margin should I maintain? The NOJB686M006RWJ carries a 6.3 V rated voltage and is not rated for continuous overvoltage stress. Niobium oxide capacitors have demonstrated better surge tolerance than tantalum under short, high-energy transients, but the NOJB686M006RWJ should not be routinely exposed to voltages above 6.3 V. For designs with transient spikes, apply voltage suppression (such as series resistors or varistors) to limit the NOJB686M006RWJ's exposure, or select a higher-voltage grade such as a 10 V part if available. If your circuit has a 6.3 V nominal rail with potential overshoot to 7–8 V during load transients, the NOJB686M006RWJ is a marginal choice; design margin should be at least 20% below rated voltage for long-term reliability. The NOJB686M006RWJ's capacitance will degrade under DC bias stress and may fail if subjected to repeated or sustained overvoltage.
• How does the NOJB686M006RWJ perform in high-frequency applications, and what impedance behavior should I expect? The NOJB686M006RWJ has an ESR of 1.5 Ohms and inherent inductance from its 1210 surface-mount package geometry. At higher frequencies, the impedance becomes dominated by the equivalent series inductance (ESL), typically in the low nanohenry range for a 1210 package. The impedance of the NOJB686M006RWJ will increase above a few megahertz, limiting its effectiveness as a power supply bypass capacitor in the 10–100 MHz range. For high-frequency decoupling at microprocessor or RF circuits, ceramic capacitors with lower inductance and ESR are more effective than the NOJB686M006RWJ. The NOJB686M006RWJ is better suited for power delivery and bulk filtering at lower frequencies (below 1 MHz) where its high capacitance density and moderate ESR provide effective energy storage and ripple reduction.
• What moisture absorption and soldering process considerations apply to the NOJB686M006RWJ, and can I use standard reflow profiles? The NOJB686M006RWJ carries an MSL rating of 1, which means it has unlimited shelf life and does not require baking before soldering. This simplifies inventory and manufacturing logistics compared to higher MSL components. The NOJB686M006RWJ can be used in standard lead-free reflow soldering with typical peak temperatures of 260°C for 10–30 seconds; the niobium oxide chemistry is robust to standard IPC-A-610 reflow profiles. However, avoid prolonged thermal stress or multiple reflow cycles, as repeated heating can affect the NOJB686M006RWJ's capacitance and ESR. If rework is necessary, inspect the NOJB686M006RWJ for visual damage (cracking, delamination) after desoldering, as thermal cycling may have compromised the device. Manual wave soldering is not recommended for the NOJB686M006RWJ due to its 1210 surface-mount package; stick to reflow or selective soldering.
• How does voltage derating affect the effective capacitance and reliability of the NOJB686M006RWJ in long-term applications? The NOJB686M006RWJ's capacitance decreases with applied DC bias. At full rated voltage of 6.3 V, the effective capacitance may be 10–20% lower than the nameplate 68 µF due to voltage derating effects inherent to niobium oxide chemistry. This further compounds the ±20% tolerance, so worst-case effective capacitance could be 44–60 µF in actual circuits. For designs where capacitance stability is critical, measure or specify the NOJB686M006RWJ's capacitance at your actual operating voltage during design validation. Operating the NOJB686M006RWJ significantly below its 6.3 V rating (for example, at 3 V) will improve both capacitance retention and reliability, but this trade-off requires evaluating your circuit's voltage distribution. The NOJB686M006RWJ's temperature coefficient also means capacitance varies across the -55°C to 105°C operating range; critical timing or filtering circuits should account for combined voltage and temperature derating.
• What alternatives exist to the NOJB686M006RWJ for 68 µF at 6.3 V, and what are the practical trade-offs? At 68 µF and 6.3 V, alternatives include tantalum capacitors (such as AVX or Kemet 68 µF/6.3 V grades), ceramic capacitors (typically X5R or X7R), and other niobium oxide suppliers. Tantalum offers tighter tolerance (±10%) and lower ESR but carries higher cost and potential supply chain constraints; niobium oxide, including the NOJB686M006RWJ, offers improved surge tolerance and lower failure rates. Ceramic capacitors at this capacitance require large case sizes (1206 or 1210) and often have higher voltage coefficients, meaning capacitance drops more significantly under bias. Film capacitors (polypropylene) provide excellent stability and low leakage but require even larger footprints. For space-constrained designs, the NOJB686M006RWJ's 1210 package and 68 µF density offer a practical middle ground. For cost-sensitive applications, lower-capacitance ceramic grades with parallel connection may be competitive. Prototype and validate whichever alternative you select under your actual operating conditions, as performance varies significantly across families.
• Does the NOJB686M006RWJ exhibit any known failure modes or aging effects during extended storage or operation? Niobium oxide capacitors, including the NOJB686M006RWJ, do not exhibit the same catastrophic short-circuit degradation seen in some tantalum lots. However, the NOJB686M006RWJ can experience gradual capacitance loss and ESR increase over years of continuous operation, particularly under elevated temperature or ripple current stress. The NOJB686M006RWJ's dissipation factor of 20% indicates higher internal losses compared to ceramic or film alternatives, which accelerates aging under AC stress. Electrolytic capacitors (whether aluminum or niobium oxide) also experience annual capacitance loss rates of 1–3% in ideal conditions; the NOJB686M006RWJ should be expected to lose measurable capacitance over a 10-year service life. For mission-critical or long-life applications (industrial control, telecom infrastructure, automotive), design with margin and plan for periodic component replacement or monitoring. The NOJB686M006RWJ's MSL rating of 1 ensures that shelf storage does not degrade the device prior to soldering.
• How should I handle the NOJB686M006RWJ in designs with reverse polarity or bipolar AC signals, and are unipolar-only ratings enforced? The NOJB686M006RWJ is a solid electrolytic (niobium oxide) capacitor and is polar, meaning its terminals have defined positive and negative connections. Reverse polarity connection will cause rapid capacitor failure and potential catastrophic short. The NOJB686M006RWJ is rated for unipolar DC or AC signals that do not reverse the polarity of the applied voltage. If your application requires AC biasing or bipolar signaling superimposed on a DC offset, the DC bias must always keep the capacitor positively polarized. For true AC coupling or bipolar applications, use film capacitors or unpolarized ceramic capacitors instead of the NOJB686M006RWJ. Verify polarity marking on the NOJB686M006RWJ's package (typically a stripe or marking on the negative terminal) during assembly and apply design safeguards such as reverse-polarity protection circuits if the risk of incorrect connection exists.
• What is the typical lead time and supply risk for the NOJB686M006RWJ, and are qualified second sources available? The NOJB686M006RWJ is manufactured by KYOCERA AVX, a primary supplier of niobium oxide capacitors. Lead times for the NOJB686M006RWJ vary with market conditions but typically range from 4–12 weeks for standard orders. Qualified second sources for exact equivalents are limited, as niobium oxide capacity is primarily concentrated at KYOCERA AVX and a few competitors. Alternatives at the same 68 µF / 6.3 V rating exist from Kemet (tantalum) or ceramic suppliers, but these are not direct replacements and require circuit re-evaluation. If supply continuity is critical, consider designing your circuit to accept multiple capacitor types (tantalum, ceramic, or niobium oxide) through parallel component qualification, or allocate longer lead time in your project schedule. The NOJB686M006RWJ's Tape & Reel packaging supports high-volume assembly and is generally available through authorized distributors.
• What creepage and clearance requirements apply when using the NOJB686M006RWJ in high-voltage or safety-critical circuits? The NOJB686M006RWJ's 6.3 V rating is low-voltage for high-voltage systems, so creepage and clearance distances to other conductors are minimal under IEC 60950 or UL standards. The NOJB686M006RWJ's small 1210 package (3.5 mm × 2.8 mm) leaves limited exposed conductor area. For applications below 50 V, no special creepage requirements apply to the NOJB686M006RWJ itself. However, if the NOJB686M006RWJ is placed adjacent to high-voltage traces or circuits, maintain standard PCB spacing rules to prevent cross-coupling or capacitive coupling effects. In medical or industrial safety circuits where the NOJB686M006RWJ might be part of a protection network, verify that the capacitor's voltage rating and leakage specifications are compatible with the safety function; if isolation or safety certification is required, contact KYOCERA AVX for specific guidance.
• Can the NOJB686M006RWJ be paralleled with other capacitor types, and what voltage balancing or current-sharing issues might arise? The NOJB686M006RWJ can be paralleled with other niobium oxide or tantalum capacitors of the same voltage to increase total capacitance and distribute ripple current. However, paralleling the NOJB686M006RWJ with ceramic or film capacitors creates impedance and frequency response mismatches because their ESR, ESL, and frequency characteristics differ significantly. The NOJB686M006RWJ's ESR of 1.5 Ohms means it will carry most low-frequency ripple current, while ceramic capacitors with lower ESR handle higher-frequency components. This uneven current sharing does not damage the NOJB686M006RWJ but may underutilize the ceramic capacitors and increase losses. If paralleling is necessary, keep the NOJB686M006RWJ and parallel capacitors on the same PCB region to minimize loop inductance, and validate that the NOJB686M006RWJ's ESR does not create hot spots or frequency response anomalies in your filter design. For most designs, using a single larger-capacitance device or multiple NOJB686M006RWJ units in parallel is more predictable than mixing capacitor families.