High Current Long Life MOS Capacitors Unlimited Shelf Life 15V 220 pF Capacitor Single Layer RF Chip

High Current Long-Life MOS Capacitor HACC221S15V500 220pF 15V Unlimited Shelf Life Single Layer RF Chip

HACC221S15V500 Long-Life MOS Capacitor: 220pF 15V with High Current Density and Unlimited Shelf Life

The HACC221S15V500 is a 220pF ±10% single-layer MOS capacitor rated at 15V DC, fabricated on float-zone silicon with 300nm thermal SiO₂ dielectric. Chip dimensions are 0.50mm * 0.50mm * 0.15mm with TiW-Au top metallization and TiW-Pt-Au backside. The 220pF value provides three times the capacitance density of standard 100pF chips in the same footprint, enabling higher current handling and more effective low-frequency bypass in a single component.

1. High RF Power Handling and Current Density

The RF current-carrying capability of a bypass or coupling capacitor limits the maximum power that can be handled in a given circuit topology. The HACC221S15V500 is designed for circuits requiring both high capacitance and high current density in a compact footprint:

• Capacitance advantage for bypass: In a shunt bypass configuration, the impedance to ground at frequency f is Z = 1/(2πfC) + ESR + j2πf·ESL. A 220pF capacitor provides 2.2* lower capacitive reactance than a 100pF device—for example, 7.2Ω vs. 15.9Ω at 100MHz. This lower impedance improves supply decoupling effectiveness and reduces ripple voltage amplitude for a given RF current.
• RMS current rating: The current-carrying capacity is limited by I²R heating in the effective series resistance. At 1GHz, ESR is typically under 0.1Ω. For a temperature rise limit of 20°C with θ_JC under 30 K/W, the maximum allowable dissipation is 0.67W, corresponding to an RMS current of √(0.67/0.1) ≈ 2.6A. In practice, the bond wire fusing current (0.8A DC for a single 25µm Au wire) becomes the limiting factor. With two parallel bond wires, continuous RF currents up to 1.5A RMS are supported, adequate for coupling and bypass in 10-50W power amplifier stages.
• Current density comparison: The 220pF value in a 0.50mm * 0.50mm footprint yields a capacitance density of 880pF/mm² (220pF / 0.25mm²). For equivalent capacitance using 100pF chips, 2.2 chips would be required, consuming approximately 0.55mm² including spacing. The single 220pF chip thus reduces assembly complexity while providing the same bypass performance.
• Low ESR at DC and RF: The gold metallization and high-conductivity silicon substrate keep ESR below 0.1Ω at 1GHz and the DC series resistance below 0.05Ω. The low ESR ensures that even at multi-ampere RF currents, the I²R voltage drop across the capacitor is negligible compared to the supply voltage.

2. Infinite Shelf Life and Zero Storage Degradation

Component shelf life is a logistics concern for manufacturers maintaining inventory of critical components for long-lifecycle products. Many capacitor types have defined shelf life limitations due to material aging mechanisms. The HACC221S15V500 has no such limitations:

• No dielectric aging: Class II ceramic capacitors (X7R, X5R) exhibit a logarithmic decrease in capacitance over time due to ferroelectric domain relaxation—a phenomenon known as aging. A typical X7R capacitor can lose 3-5% of its capacitance per decade-hour after the last heat treatment above the Curie temperature (~125°C). This means a capacitor measured at 100nF immediately after soldering may read 95nF after 1,000 hours, 90nF after 100,000 hours, and 85nF after 10 million hours (~1 year). The SiO₂ dielectric in the HACC221S15V500 has no ferroelectric domains and therefore exhibits zero aging—capacitance measured at any time after fabrication is stable to within the measurement repeatability (±0.1%).
• No moisture absorption: Some capacitor dielectrics (paper, polymer film, porous ceramics) gradually absorb atmospheric moisture during storage, shifting capacitance upward and increasing dissipation factor. Thermal SiO₂ is a fully dense amorphous glass with zero porosity and zero moisture uptake, making the capacitance value immune to ambient humidity during storage.
• No solderability degradation: The gold metallization does not oxidize, tarnish, or form a non-wettable surface layer under any practical storage condition. Unlike tin-plated or silver-plated terminations that require solderability testing after extended storage, gold surfaces remain solderable indefinitely when stored in a clean environment. The vacuum-sealed packaging is provided for mechanical protection and ESD control, not for solderability preservation.
• No intermetallic growth at room temperature: In some metallization systems (e.g., gold on aluminum, tin on copper), intermetallic compounds grow slowly even at room temperature, eventually consuming the solderable layer. The TiW-Au and TiW-Pt-Au systems are thermodynamically stable—the TiW barrier prevents silicon-gold interdiffusion, and the Pt layer prevents gold-silver interdiffusion from epoxy. No intermetallic growth occurs at temperatures below 150°C on any practical timescale.
• Practical consequence: The HACC221S15V500 can be procured in a single large-quantity order and stored indefinitely without requalification, periodic testing, or derating adjustments. For programs with 10-20 year production lifetimes, this eliminates the need for multiple small procurements with their associated lot-to-lot variation and requalification overhead.

3. Ultra-High Self-Resonant Frequency

Despite the higher capacitance value (220pF vs. 100pF in the standard HACC101), the HACC221S15V500 maintains a high self-resonant frequency through the same low-inductance single-layer construction. With intrinsic chip ESL under 0.05nH, the chip-level SRF is approximately 1/(2π√(0.05*10⁻⁹ * 220*10⁻¹²)) ≈ 1.5GHz. In a practical assembly with a 0.5mm bond wire (~0.4nH total), the system SRF is approximately 1/(2π√(0.4*10⁻⁹ * 220*10⁻¹²)) ≈ 540MHz—still adequate for bypass applications through UHF and into lower L-band frequencies. Where higher SRF is required, the same parallel-bond-wire techniques described for the 100pF variant apply, with approximately √(220/100) ≈ 1.48* lower SRF at any given inductance due to the higher capacitance.

Key Features

• High RF Power Handling and Current Density: 220pF in 0.50mm footprint yields 880pF/mm² density. Supports 1.5A RMS RF current with dual parallel bond wires. ESR under 0.1Ω at 1GHz minimizes I²R losses in power amplifier bypass applications.
• Infinite Shelf Life and Zero Aging: Amorphous SiO₂ dielectric with zero ferroelectric aging—no logarithmic capacitance decay over time. Zero moisture absorption during storage. Gold metallization resists oxidation with no solderability degradation.
• Ultra-High SRF: Chip-level SRF above 1.5GHz for 220pF. System SRF above 540MHz with single bond wire, scalable with parallel bonding.
• No Requalification Needed: Stable electrical parameters allow single large procurement for multi-year programs without periodic lot testing or derating adjustments.
• Wafer-Level 100% Test: Every capacitor probed for capacitance, leakage, and breakdown before dicing.

Electrical Specifications (T = 25°C unless noted)

Storage and Inventory Management

Typical Applications

• RF power amplifier supply decoupling where high capacitance and high current handling are required in a single compact component
• Long-lifecycle industrial and infrastructure equipment where component requalification costs must be minimized over 10-20 year production spans
• High-reliability programs where single large procurements with consistent lot characteristics are preferred over multiple small buys
• DC blocking in wideband RF signal chains where the higher 220pF value provides lower reactance at the low-frequency end of the band
• Inventory-critical applications where storage conditions cannot be tightly controlled and component degradation during shelf storage is unacceptable

Ordering Information

Standard product ships as 0.50mm * 0.50mm chips in anti-static waffle packs with vacuum-sealed moisture barrier bag outer packaging. No special storage conditions are required—the MSL 1 rating permits unlimited floor life at standard factory ambient conditions (≤30°C, ≤85%RH). For programs planning single large-quantity procurements, contact us to discuss lot reservation and extended delivery schedules to align with your production ramp.

Contact us for current density derating data, shelf-life certification letters for your quality system, or volume pricing for multi-year procurement agreements.