ECQ-E4393KZ Film Capacitor Full Parameter Analysis: How to Interpret 400V/0.039μF Specification

A thin-film capacitor no bigger than a fingernail—how many engineering secrets are hidden in its part number? WithECQ-E4393KZFor example, a voltage rating of 400 V and a capacitance of 0.039 μF are not arbitrary values; they directly determine whether the component can operate reliably in power‑supply filtering, inverter circuits, or LED drivers. This article dissects the model‑number coding scheme digit by digit and compares parameter differences within the same series, enabling engineers to quickly decipher the "language of capacitors" when selecting components.

Model coding rule breakdown by digit: The naming logic of ECQ-E4393KZ

Prefix "ECQ-E": Series Classification and Dielectric Type Identification

ECQ-E4393KZThe model prefix carries three layers of information.ECQThis identifies Panasonic's plastic film capacitor product family, distinct from electrolytic capacitors (EEU series) and ceramic capacitors (ECJ series).The letter E following the hyphenSpecifically refers to polyester film (Mylar/PET) dielectric, which maintains stable dielectric properties in the range of -55°C to +105°C. Its cost is approximately 30% lower than polypropylene (ECQ-P series), though its high-frequency loss is slightly higher.

Note the differences in dielectrics between ECQ-E, ECQ-V, and ECQ-M series: the V series uses a metallized polyester film self-healing structure, while the M series employs a laminated package. The standard lead spacing for the E series is 5 mm or 7.5 mm, suitable for through-hole mounting processes.

The numeric code "4393": a combination code representing voltage × capacitance × tolerance

4393 is the core parameter segment of the model number and should be broken down into4-39-3Three segments for interpretation:

This coding system is compatible with IEC 60062 standard, but Panasonic fixes the capacitance unit as μF instead of pF to avoid ambiguity in three-digit codes. For example, 393 interpreted according to EIA code would be 39 × 10³ pF = 0.039 μF—though the result is consistent, Panasonic uses direct labeling to reduce the risk of misreading.

Detailed Explanation of Core Technical Parameters: From Nominal Values to Actual Limits

Rated Voltage 400V: DC/AC Application Scenarios and Key Derating Design Considerations

ECQ-E4393KZThe 400V rating isthe DC rated voltage (DC); AC application scenarios must be strictly distinguished. The AC withstand voltage of polyester film capacitors is typically only 50%–60% of the DC rating, meaning that for this model, the effective value limit under 50/60 Hz power frequency is approximately 200–240 VAC. When used for filtering in a 220 VAC mains supply, at least a 20% voltage margin must be maintained, or a product rated at 630 VDC should be selected.

Derating design follows industry-standard guidelines: in high-temperature environments (>85°C), for every 10°C increase, the operating voltage is recommended to be reduced by 10%; additional calculations are required to account for self-heating effects caused by high-frequency ripple current. Measured data show that, under natural convection conditions, for this size (φ7.5×12.5mm), when the ripple current density exceeds 30mA/μF, the temperature rise can reach over 15K.

0.039μF Capacitance: Nominal Value, Tolerance Range, and Temperature Drift Characteristics

0.039μF falls within the small-capacitance range and is typically used in high-frequency noise bypass and coupling circuits. A ±10% tolerance means that any measured value between 0.0351 and 0.0429 μF is considered acceptable. The temperature coefficient of polyester film is approximately +200±100 ppm/°C, resulting in a capacitance drift of about ±3% across the full temperature range (-55°C to +105°C), which is far superior to the ±80% variation seen in Y5V ceramic capacitors.

In terms of key frequency characteristics, this capacitor has an impedance of about 40 Ω at 100 kHz, and when combined with a 10 μH inductor, it forms an LC filter whose resonance point is around 2.5 MHz, effectively suppressing second-order harmonics in switching power supplies.

Key performance metric comparison: ESR, ripple current, and self-healing properties

The core advantage of metallized polyester film lies inSelf-healingMechanism: When the dielectric breaks down due to weak points, the discharge energy vaporizes the local metal electrode, forming an insulating region that isolates the defect. The ECQ-E series typically has an ESR of 20–50 mΩ at 100 kHz and a ripple current capability of approximately 80–120 mA (@105°C/100 kHz), which is one order of magnitude lower than electrolytic capacitors of the same size. However, its lifetime characteristics show an exponential advantage—rated life of 100,000 hours at 105°C.

Horizontal comparison of specifications within the same series: Differentiated positioning of the KZ suffix

ECQ-E4393KZ vs ECQE4393KT: Differences in lead configuration and temperature rating

Suffix letters define package type and reliability grade.KZIndicates standard radial leads and bulk packaging, with an operating temperature range of -55°C to +105°C;KTThe suffix corresponds to tape-and-reel packaging, suitable for automatic insertion machines, with the same temperature characteristics. If the suffix isJZ, the maximum operating temperature drops to +85°C, and the cost is reduced by approximately 15%.

Regarding pin pitch, KZ defaults to 5.0 mm, while some high-capacity models extend it to 7.5 mm. When laying out the PCB, be sure to verify the hole spacing; in vibrating environments, it is recommended to add epoxy resin fixation at a 5 mm pitch.

Capacitance range and voltage coverage: How to quickly identify alternative models

The ECQ-E series covers capacitances from 0.01 μF to 4.7 μF, with four voltage ratings: 100 V / 250 V / 400 V / 630 V. If you need to replaceECQ-E4393KZ, prioritize searching for models with the same voltage code "4" and a similar capacitance code:

• ECQ-E4333KZ: 0.033 μF/400 V (capacitance -15%, increased ripple current margin)
• ECQ-E4473KZ: 0.047 μF/400 V (capacitance +20%, slightly reduced ESR)
• ECQ-E6393KZ: 0.039 μF/630 V (voltage +57%, size φ10×16 mm)

When substituting across brands, TDK's B32529C3393K series and Vishay's MKT368 series have similar parameters; however, there are millimeter-level differences in pin diameter and package height, so mechanical installation compatibility must be re-verified.

Typical Application Scenarios and Selection Verification

Parameter Matching in EMI Filtering for Switching Power Supplies

In AC-DC front-end common-mode/differential-mode filters, a 0.039 μF/400 V capacitor is typically placed after the rectifier bridge as a differential-mode capacitor. Taking a 65 W flyback power supply as an example, this capacitance, together with a 2.2 mH differential-mode inductor, yields a cutoff frequency of approximately 17 kHz, providing about 40 dB attenuation for conducted noise in the range of 150 kHz to 1 MHz. During component selection and verification, it must be confirmed that the capacitor's dv/dt withstand capability exceeds 500 V/μs to prevent breakdown during switching transients.

Voltage Margin Calculation for the Inverter DC-Link Stage

The DC bus voltage of photovoltaic micro-inverters typically ranges from 360 to 400 V.ECQ-E4393KZThe 400V rating may seem critical, but it's necessary to distinguish between steady-state and transient conditions. Voltage fluctuations caused by the MPPT algorithm are about 10%, and when combined with surges during grid faults, a 30% voltage margin should actually be reserved. In this scenario, ECQ-E6393KZ (630V) is recommended, or switching to the ECQ-P polypropylene series (with lower losses).

Engineer's Practical Guide: Reading Parameter Tables and Confirming Reliability

Quick Reference Checklist for Key Fields in Datasheets

Quick VerificationECQ-E4393KZApplicability: Check the following fields in order of priority:

1. Rated Voltage (Ur): Confirm whether DC/AC ratings are indicated, distinguishing between continuous and pulse withstand voltages
2. Capacitance Tolerance: Verify if J-grade ±10% meets circuit accuracy requirements
3. Dissipation Factor (tanδ): For polyester film at 1 kHz, the typical value is 0.5%-1.0%; used as a basis for assessing high-frequency heating.
4. Insulation Resistance (IR): ≥30,000 MΩ·μF, determining leakage current and long-term reliability
5. Withstanding Voltage (Ut): Typically 1.5Ur for 60 seconds, verifying process safety margin

AEC-Q200 Certification Status and Automotive Grade Upgrade Path

The basic models of the ECQ-E series have not passed AEC-Q200 automotive-grade certification, but Panasonic provides counterparts with the same architectureECQ-E(A)An extended series that adds tests such as temperature cycling and high-humidity bias. For automotive electronic applications (such as OBC onboard chargers), it is necessary to explicitly specify the AEC-Q200 Grade 125℃ version, or switch to the ECW-FG series (polypropylene dielectric + automotive-grade certification).

Key Summary

• Model Decoding:ECQ-E4393KZIn "4" = 400V, "39" = 0.039μF, and "3" = ±10% tolerance, KZ denotes the standard can-type package.
• Voltage Rating: A 400VDC rating corresponds to approximately 200–240VAC in AC applications; additional derating is required under high-temperature and high-frequency conditions.
• Dielectric Advantages: Polyester film with self-healing properties and low temperature drift makes it suitable for filtering circuits that demand high capacitance stability.
• Alternative Strategies: Prioritize matching the voltage code "4"; adjust the capacitance code within one step; pay attention to differences in package size.
• Certification Differences: Basic models are suitable for industrial and consumer-grade applications; for automotive-grade scenarios, verify compliance with AEC-Q200 standards.

Frequently Asked Questions