CTE Matching RF Choke Inductor Ultra Low DCR Surface Mount Inductor

Product Specification

Custom Conical Inductor Zero Thermal Stress CTE Matching Ultra Low DCR High Current Bias Tee Eutectic Micro Tip

HACC-CUSTOM-TH: Zero-Thermal-Stress CTE-Matched Conical Inductor with Ultra-Low DCR & Eutectic Micro-Tip

Zero-Thermal-Stress CTE Matching Design

Hybrid circuits and RF modules using alumina (Al₂O₃, CTE 6.7 ppm/°C) or aluminum nitride (AlN, CTE 4.5 ppm/°C) substrates experience significant thermal stress at component-substrate interfaces during temperature cycling. Standard conical inductors with non-matched metal terminations develop solder joint cracks, wire bond lift-off, and inductance drift after repeated thermal exposure. The HACC-CUSTOM-TH eliminates this failure mode through CTE-matched metallization: the base termination alloy and wire coating are selected to match the customer's substrate CTE within ±1.5 ppm/°C. After 1,000 thermal cycles from -55°C to +125°C, DCR shift is maintained below 1%, wire bond pull strength remains above 3.0 g, and no solder joint cracking is observed — validated per industry-standard thermal cycling methodology.

Ultra-Low DCR for High-Current Bias-Tees

High-power GaN and GaAs power amplifier bias-tees require the DC-feed inductor to carry 1A to 2A of continuous bias current without excessive voltage drop or thermal rise. The HACC-CUSTOM-TH achieves DCR below 0.3 Ohm for 100 nH inductance and below 1.0 Ohm for 500 nH — approximately 4–6* lower than standard fine-wire conical inductors. This is achieved through a fat-wire option with copper wire diameter from 0.10 mm to 0.15 mm, gold-flashed for bondability. Continuous current handling reaches 2A with temperature rise maintained below 20°C. Critically, inductance remains stable within ±5% from 0 mA to 1A DC bias — no saturation-induced inductance collapse because the air-core architecture is inherently linear.

Eutectic-Compatible Micro-Tip Metallization

The conical inductor apex — the small-diameter end that connects to the RF line — is the most challenging assembly point. Standard apex diameters of 0.4–0.8 mm are too large for precision eutectic soldering, and inconsistent tip geometry causes variable solder fillet quality. The HACC-CUSTOM-TH addresses this with a precision laser-cut micro-tip below 0.3 mm diameter, pre-tinned with AuSn (80Au/20Sn) solder cap 3–5 µm thick over a TiW-Au diffusion barrier. The flat laser-cut face and controlled solder volume ensure >95% wettability during 280°C eutectic reflow — producing a consistent, inspectable solder fillet without solder bridging to adjacent structures. This micro-tip eutectic interface is compatible with automated eutectic die attach equipment and eliminates the need for conductive epoxy at the critical RF connection point.

Key Specifications

Applications

• GaN Power Amplifier Bias-Tees — 2A continuous bias, DCR <0.3 Ω, 100 MHz–40 GHz, CTE-matched to AlN substrate for thermal reliability
• High-Reliability Hybrid Circuits — 1,000 thermal cycles qualified, AuSn eutectic micro-tip, alumina CTE-matched for mil/aero hybrid assembly
• High-Power T/R Module Bias Injection — Fat-wire 0.15 mm Cu, 2A continuous, <20°C temperature rise, linear inductance vs. DC bias
• Automated Eutectic Assembly Lines — <0.3 mm micro-tip pre-tinned AuSn, compatible with pick-and-place eutectic die attach, >95% wettability

Contact us with your substrate CTE, bias current, and eutectic requirements. CTE-matched conical inductors with ultra-low DCR and eutectic micro-tip ship in 5–7 business days.