Bordered Single Layer Capacitor 220pF 50V Low ESR Capacitor COG Ceramic For Ku Ka Band

High-Frequency Technical Summary

The HACC221S15V500 is a high-voltage, ultra-miniature Single-Sided Bordered Single Layer Ceramic Capacitor (SLC) engineered for broadband DC blocking, RF coupling, and microwave bypass filtering in high-voltage hybrid microcircuits operating through Ku, K, and Ka bands. Delivering 220 pF ±10% capacitance with an elevated 50 V DC continuous rating and >125 V breakdown voltage (250% rated), this capacitor is packaged into a 15 mil × 15 mil (0.38 mm × 0.38 mm) footprint with an ultra-low profile of 0.15 mm (6 mil). Designed for reliable operation from 0.5 GHz to 40.0 GHz across UHF through Ka microwave bands, the HACC221S15V500 is purpose-built for GaN-on-SiC HEMT power amplifier drain bias decoupling, LEO/MEO satellite payload filters,  phased-array radar T/R modules, and 5G mmWave infrastructure where 50 V operating voltage with >125 V breakdown margin and millimeter-wave SRF are simultaneously required.

Fabricated with Class I COG/NPO (C0G/NP0) ultra-stable ceramic dielectric optimized for both high dielectric strength (>50 V/μm) and Class I temperature stability, this capacitor maintains capacitance within ±0.3% across -55°C to +125°C. The ultra-low equivalent series inductance (ESL <35 pH) — achieved through a single-layer coaxial electrode geometry — pushes the first series self-resonance above 25 GHz, ensuring clean, resonance-free bypass and DC blocking through the entire Ku-band (12-18 GHz), K-band (18-27 GHz), and into Ka-band (27-40 GHz) with flip-chip mounting. The single-sided bordered architecture with a ceramic insulating margin around the top gold electrode prevents conductive epoxy climb-up during die attach. Top electrode features TiW-Au with minimum 4.0 μm Au for heavy wire bonding. Bottom electrode utilizes TiW-Pt-Au with a platinum (Pt) diffusion barrier that is completely insoluble in AuSn eutectic solder, eliminating gold scavenging failures during high-temperature reflow assembly.

Key Performance Advantages

Ultra-Low ESR/ESL & High Self-Resonant Frequency — Single-Layer Coaxial Architecture

Multi-layer ceramic capacitors (MLCCs) achieve high capacitance by stacking alternating electrode layers, but each internal electrode adds both ohmic resistance (due to thin nickel electrodes) and parasitic inductance (from the serpentine current path through vias). The HACC221S15V500 eliminates both sources of loss through its single-layer coaxial structure: current flows straight-through from the top Au bond pad, through the COG/NPO dielectric, to the bottom Au ground plane — a path length of just 0.15 mm.

• ESR <0.15 Ω at 1 GHz: An order of magnitude lower than 0402 COG MLCCs of equivalent capacitance (0.5-1.5 Ω). In a Ku-band (14 GHz) power amplifier output matching network, this 10× ESR reduction translates directly to 0.5-1.0 dB lower insertion loss per matching element. In a 4-stage Doherty PA with multiple matching and bypass elements, the cumulative PAE improvement exceeds 2-3 percentage points.
• ESL <35 pH: Compared to 300-600 pH for 0402 MLCCs. The single-layer coaxial current path has no internal vias, no electrode edges, and no serpentine routing — only a direct vertical path through the dielectric. For a DC blocking capacitor, this means the first series self-resonance occurs above 25 GHz, more than 10× higher than an equivalent MLCC (2-4 GHz).
• SRF >25 GHz (wire-bonded), >35 GHz (flip-chip): The self-resonant frequency is the frequency at which the capacitive reactance equals the inductive reactance — above SRF, the capacitor behaves as an inductor. With SRF >25 GHz, the HACC221S15V500 provides true capacitive behavior through the entire Ku-band (12-18 GHz) and well into K-band (18-27 GHz). For Ka-band (27-40 GHz) operation, flip-chip mounting (Cu UBM with SnAg solder bumps available on request) reduces ESL to <25 pH, extending SRF beyond 35 GHz.
• Transmission-line behavior: Below SRF, the SLC behaves as a near-ideal series coupling element with S21 (insertion loss) <0.2 dB through 20 GHz and S11 (return loss) <-20 dB — essentially transparent to the RF signal path while providing complete DC isolation.

High Breakdown Voltage & TDDB Reliability — 2.5× Voltage Margin with >10-Year Lifetime

In GaN power amplifier drain bias networks and satellite payload power distribution, the DC blocking capacitor must withstand not only the nominal operating voltage (typically 28-50 V for GaN) but also voltage transients, load mismatch reflections, and supply ripple — all at elevated junction temperatures approaching 125°C. The HACC221S15V500 is designed with a conservative 2.5× derating margin: 50 V rated, >125 V breakdown, 100% tested.

• 50 V continuous rating: Addresses the needs of 28 V (airborne), 48 V (telecom), and 50 V (GaN HEMT drain) power distribution buses with appropriate margin. Standard 16-25 V capacitors are insufficient for these applications — they require at least 2× derating to 32-50 V rated devices.
• >125 V breakdown (250% rated): Every die is 100% production tested at 125 V DC (5 sec dwell) to guarantee dielectric integrity. The 2.5× margin exceeds the industry-standard 2× derating practice recommended by MIL-PRF-55681 and NASA EEE-INST-002 for space-grade ceramic capacitors.
• TDDB lifetime >10 years at 50 V, 125°C: Time-Dependent Dielectric Breakdown (TDDB) is the dominant long-term wear-out mechanism in ceramic capacitors operated at high DC bias and temperature. Under sustained electric field stress at elevated temperature, atomic-scale defects in the dielectric lattice slowly accumulate and grow until they form a percolation path — a conductive filament that shorts the electrodes. The HACC221S15V500's COG/NPO dielectric has been characterized using constant-voltage TDDB testing per JEDEC JESD92 at accelerated conditions (elevated voltage and temperature) and projected to >10 years at 50 V/125°C using the E-model (thermochemical breakdown model). Weibull lifetime distribution data, acceleration factors, and TDDB test reports are available to qualified customers under NDA.
• No single-event breakdown: The single-layer, borderless-edge electrode geometry eliminates the internal electrode edge effects where electric field crowding occurs in MLCCs. In MLCCs, breakdown consistently initiates at internal electrode edges where the field strength can be 3-5× higher than the bulk dielectric. The HACC221S15V500's coaxial geometry produces a uniform electric field distribution, maximizing the dielectric's intrinsic breakdown strength.

Ultra-Miniaturization & Low Profile — 50 V Rating in 15 mil Footprint

The HACC221S15V500 achieves 50 V rating in a 0.38 × 0.38 × 0.15 mm package — a volumetric power density that no multi-layer ceramic capacitor can match. This is enabled by a proprietary high-K COG/NPO ceramic formulation that simultaneously delivers Class I temperature stability, >50 V/μm dielectric strength, and sufficient permittivity to achieve 220 pF in a 15 mil footprint. The single-layer coaxial geometry eliminates the need for internal electrodes, vias, and margin regions that consume volume without contributing to capacitance in MLCC designs.

• 15 mil footprint vs. 0402 MLCC: The HACC221S15V500 occupies 0.14 mm² vs. 0.50 mm² for an 0402 — a 3.6× area reduction. In a 64-element Ka-band phased-array with 2 DC blocks and 2 bypass caps per element (256 capacitors total), the board area savings exceed 90 mm² — enough to add two additional GaN PA MMICs per panel.
• 0.15 mm height vs. 0.50 mm for 0402: The 3.3× height reduction enables thinner module profiles, critical for conformal phased arrays, UAV payloads, and handheld  radios where Z-height is severely constrained by chassis thickness.
• Die-level integration: Unlike SMD MLCCs that require PCB pads, vias, and trace routing — each adding 200-400 pH of parasitic inductance — the HACC221S15V500 integrates directly onto the MMIC carrier or hermetic hybrid substrate, minimizing the interconnect path to <100 μm of 25 μm Au bond wire (<50 pH additional ESL).
• Single-sided bordered: The ceramic margin on the top electrode physically contains conductive epoxy during die attach, enabling fully automated high-speed assembly without the risk of short-circuit defects that plague borderless capacitor designs. No manual rework, no yield loss from epoxy bridging.

Comprehensive Parameter Datasheet

Comparative Technical Matrix: HACC221S15V500 vs. Industry Alternatives for 50 V RF Bypass

Thin-Film Metallization Stack Engineering

The HACC221S15V500 employs an asymmetric, high-reliability vacuum-sputtered thin-film metallization system that is independently optimized for the top (wire bond) and bottom (die attach) interfaces:

S-Parameter Engineering & Assembly Guide for Millimeter-Wave Integration

Epotek H20E Conductive Silver Epoxy SOP

• Adhesive: Epoxy Technology H20E (or equivalent qualified silver-filled conductive epoxy).
• Dispensing: 2-5 nL per die using pneumatic micro-dispenser. The single-sided bordered ceramic margin on the top electrode physically contains excess epoxy, preventing capillary climb-up to the gold bond pad.
• Placement: <50 gf collet force with compliant tip. Verify die alignment within ±25 μm using automated vision system.
• Curing: 120°C / 30 min (standard) or 150°C / 15 min (fast-cure). Ramp rate <10°C/sec. Natural cool-down to ambient before wire bonding.

Gold Wire Bonding Parameters

• Wire: 0.7-1.0 mil (18-25 μm) 99.99% Au wire.
• Wedge bonding: 20-35 gf, 60-100 mW ultrasonic, 20-50 ms, 120-150°C stage.
• Ball bonding: 15-30 gf, 40-80 mW ultrasonic, 10-30 ms, 150°C stage.
• Clearance: Bond landing point must be ≥25 μm from Au electrode edge (ceramic border).
• Inspection: 50× optical. Reject bonds with >25% pad deformation, visible cratering, or bond placement within 25 μm of electrode edge.

Flip-Chip Assembly Option (for Ka-Band Optimization)

• UBM: Electroless Ni/Au or Cu UBM with SnAg solder bumps (contact factory for flip-chip capable variants).
• ESL reduction: Flip-chip mounting eliminates bond wire inductance, reducing total ESL to <25 pH and extending SRF to >35 GHz.
• Underfill: Capillary underfill recommended for thermal cycling reliability. Choose low-loss, low-Dk underfill (<3.5 @ 40 GHz) to minimize mmWave dielectric losses.
• S-parameter models: Two-port .s2p data (100 MHz-40 GHz) available for both wire-bonded and flip-chip configurations under NDA.

Frequently Asked Questions

Q1: How does the HACC221S15V500 achieve 50 V rating and 220 pF in a 15 mil footprint — is there a trade-off?

There is a deliberate design trade-off between capacitance and voltage rating in the 15 mil platform. The HACC221S15V500 (220 pF / 50 V) uses a slightly thicker COG/NPO dielectric layer compared to the 330 pF / 25 V variant, trading some capacitance density for higher dielectric strength. The capacitance scales inversely with dielectric thickness (C = εε₀A / d), while breakdown voltage scales linearly (V_BD = E_BD × d). This is an intentional design choice: 220 pF is the maximum capacitance achievable at 50 V rating in a 15 mil footprint using the current COG/NPO formulation while maintaining the 2.5× breakdown margin (>125 V DWV). For applications requiring higher capacitance at lower voltage, the 330 pF / 25 V HACC331S15V250 is available in the same 15 mil footprint.

Q2: What makes TDDB (Time-Dependent Dielectric Breakdown) the critical reliability metric for space-grade capacitors, and how is the >10-year lifetime validated?

TDDB is the dominant long-term failure mechanism for ceramic capacitors operated at high DC bias and elevated temperature — exactly the conditions in satellite payload power distribution and GaN PA drain bias networks. Unlike instantaneous breakdown (DWV testing), which detects gross defects, TDDB is a wear-out phenomenon: under sustained electric field stress at high temperature, atomic-scale oxygen vacancies in the COG/NPO lattice migrate, accumulate at defect sites, and eventually form a conductive percolation filament that shorts the electrodes. This is a statistical process — devices from the same wafer lot will fail at different times following a Weibull distribution.

Validation methodology: The HACC221S15V500 dielectric is characterized using constant-voltage TDDB testing per JEDEC JESD92. Multiple populations of capacitors are stressed at accelerated voltages (75 V, 100 V, 125 V) and temperatures (125°C, 150°C, 175°C) until breakdown. The failure times are fit to a Weibull distribution, and the E-model (thermochemical breakdown model) is used to extract the field acceleration factor (γ) and thermal activation energy (E_a). These parameters are then used to project the lifetime at use conditions (50 V, 125°C). The >10-year projection at 50 V/125°C is based on zero failures at accelerated conditions with a 90% confidence bound. Full TDDB qualification reports with Weibull plots, acceleration factors, and E-model parameters are available under NDA.

Q3: For Ka-band (27-40 GHz) satellite communication phased arrays, should I use wire-bonded or flip-chip assembly?

For Ka-band operation (27-40 GHz), flip-chip assembly is strongly recommended. The rationale: at 35 GHz, the inductive reactance of a 50 pH bond wire is approximately j11 Ω — comparable to the capacitive reactance of the 220 pF capacitor (-j21 Ω at 35 GHz). This additional inductance shifts the effective SRF downward and introduces frequency-dependent phase shift that complicates phased-array beamforming calibration. Flip-chip mounting eliminates the bond wire entirely, reducing total ESL to <25 pH and pushing the effective SRF to >35 GHz — ensuring purely capacitive behavior across the entire Ka-band. For Ku-band (12-18 GHz) and K-band (18-27 GHz) applications, wire bonding is fully sufficient with SRF >25 GHz. Contact our applications team for S-parameter comparison data between both assembly configurations at your specific operating frequency.