4700pF 50V Isolation Capacitor SiO2 Dielectric Low Leakage Capacitor For High Frequency

HACC472S50V500 Isolation-Optimized MOS Capacitor for High-Signal-Integrity Circuits

The HACC472S50V500 is a single-layer MOS capacitor specifically characterized for applications where electrical isolation, minimal leakage current, and signal fidelity are the dominant performance requirements. Nominal capacitance is 4700pF (4.7nF) at a rated working voltage of 50V DC. The device uses the same thermally grown SiO₂ dielectric and gold metallization process as the HACC series, with emphasis on maximizing isolation resistance and minimizing DC leakage across the full operating temperature range.

Understanding MOS Capacitor Isolation Performance

MOS capacitor isolation is primarily determined by the quality of the thermal SiO₂ dielectric layer and the resistivity of the underlying silicon substrate. The HACC472S50V500 achieves high isolation through three design factors:

• High-quality thermal oxide: The SiO₂ layer is grown in a controlled dry oxidation furnace, producing a dense, pinhole-free dielectric with bulk resistivity exceeding 10¹⁶Ω·cm.
• Float-zone silicon substrate: Substrate resistivity above 1000Ω·cm minimizes parasitic conduction paths through the silicon, sustaining isolation resistance above 10GΩ at room temperature.
• Edge passivation: Chip edges are passivated to suppress surface leakage currents that would otherwise degrade isolation, particularly at elevated humidity levels.

Measured isolation resistance exceeds 10GΩ at 25°C and 50V DC bias, with leakage current typically below 5nA at room temperature and below 50nA at 125°C.

Key Features

• Superior Isolation — >10GΩ at 25°C: High isolation resistance ensures minimal cross-talk between adjacent channels in multi-chip modules and densely packed RF assemblies. This parameter is measured at the full rated voltage of 50V DC to reflect real-world operating conditions.
• Ultra-Low Leakage — <5nA at 25°C: Low DC leakage preserves the charge state in sample-and-hold circuits, reduces offset errors in precision integrators, and maintains signal integrity in high-impedance analog front-ends. Leakage remains below 50nA at the maximum rated temperature of 125°C.
• Wire Bondable Gold Metallization: The 2.5µm minimum gold top electrode is compatible with both thermosonic gold ball bonding (25µm wire, 120-150°C stage, >6g pull strength typical) and ultrasonic aluminum wedge bonding (25µm or 33µm wire, room temperature). The 1.0µm minimum gold backside metallization supports eutectic AuSn die attach and conductive epoxy mounting.
• Flexible Assembly Options: The chip form factor supports integration into hybrid microcircuits, ceramic substrate modules, and chip-on-board assemblies. Standard waffle-pack or gel-pak shipping formats are compatible with automated pick-and-place equipment using ESD-safe tooling.
• 4700pF Capacitance at 50V Rating: The combination of 4.7nF capacitance and 50V working voltage covers a broad range of coupling, bypass, and filtering applications where higher capacitance values reduce the number of parallel components needed.
• Stable Over Temperature: TCC of approximately +35ppm/°C across -55°C to +125°C, with capacitance variation typically within ±2% over the full range. This stability simplifies circuit calibration and reduces temperature-dependent tuning requirements.

Assembly and Integration Guide

Die Attach: Eutectic gold-tin (AuSn) solder provides the lowest thermal resistance path. Use a 320°C peak reflow profile with forming gas (N₂/H₂) to prevent oxidation. Silver-filled conductive epoxy is an alternative for temperature-sensitive substrates; follow the epoxy manufacturer's cure schedule and ensure full wetting of the backside gold surface.

Wire Bonding Best Practices:

• Gold ball bonding: 25µm diameter Au wire, 120-150°C stage temperature, bond force 25-35gf, ultrasonic power 80-120mW. Typical pull strength exceeds 6gf with heel break failure mode.
• Aluminum wedge bonding: 25µm or 33µm Al-1%Si wire at room temperature, bond force 20-30gf, ultrasonic power 100-150mW. Provides a lower-cost single-step process suitable for non-hermetic packages.
• Bond pad layout: The 0.50mm * 0.50mm top pad accommodates a single bond wire. For multiple bonds, consider connecting at the substrate level rather than the chip pad.

ESD Precautions: Class 0 HBM sensitivity per JESD22-A114. Maintain grounded work surfaces, wrist straps, and ionized air flow during all assembly steps. Store chips in conductive containers prior to use.

Electrical Specifications (T = 25°C unless noted)

Typical Applications

• Sample-and-hold amplifier charge storage, where leakage below 5nA ensures minimal voltage droop between sampling intervals
• Precision analog integrator and ramp generator circuits requiring low dielectric absorption
• High-impedance sensor front-end AC coupling, preserving the signal-to-noise ratio of photodiode and piezoelectric transducer signals
• Multi-channel data acquisition system input filtering, where high isolation between channels prevents cross-channel interference
• Medical imaging electronics including ultrasound transducer interfaces and CT detector readout circuits
• Industrial process control instrumentation with 4-20mA loop-powered sensor conditioning
• Bypass and decoupling in mixed-signal circuits where digital switching noise must be isolated from sensitive analog nodes

Reliability and Qualification

Devices are subjected to 100% DC probe testing at wafer level prior to dicing. Sample-based reliability testing includes: high-temperature operating life (HTOL) at 125°C and 50V bias for 1000 hours, temperature cycling (-65°C to +150°C, 500 cycles per MIL-STD-883 Method 1010), and 85°C/85%RH biased humidity testing for 500 hours. Contact us for the full qualification report and lot-specific test data.

To request samples, discuss custom capacitance values, or receive a detailed application note on wire bonding optimization, contact our sales team for a quotation.