CIRCULAR ELECTRONICS Circularity in power electronics: Status of R-strategy adoption

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MERSEN

DOWA HD Europe GmbH

Heraeus Electronics GmbH & Co. KG

As power electronics scales from microwatt IoT nodes to multi-megawatt energy infrastructure, its material footprint is growing just as rapidly. Circularity strategies are increasingly seen as a way to decouple performance gains from resource consumption and waste generation. This article reviews how far different R-strategies have already been adopted across key power electronics components and where practical limits remain.

Moving from a linear “design–use–discard” model toward circular design principles is becoming a strategic requirement for the long-term sustainability of power electronics systems.

1. Scope and necessity of power electronics and R-strategies

Power electronics is essential for conversion, control, and conditioning of electrical energy across a wide spectrum:

• Microwatt scale (~10^-6 W): Ultra-low-power IoT sensors and biomedical implants consume 10–500 µW, enabling multi-year lifetimes from coin cells or energy harvesters¹.

• Kilowatt to megawatt scale (10³–10⁶ W): EV traction inverters operate at 50–250 kW, utility-scale solar inverters at 1–5 MW, and HVDC converter stations at >500 MW².

This ubiquity means that design choices directly influence circularity. The 10-R model ranks approaches from most to least circular — from Refuse (avoiding new production) to Recover (material recycling)³. Applying these principles to power electronics can shift the industry from material-intensive long-loop recovery to reuse at the highest level.

2. Status of R-strategies by component group

To assess how circularity principles are being implemented in practice, the following sections examine the adoption of R-strategies across major power electronics component groups, starting with short-loop approaches focused on design and material choices.

2.1 Short loops (R0–R2): Avoidance via design and materials

Semiconductors — Design-for-Recoverability⁴

• Modular packaging: TO-247, EasyPACK housings allow die removal without destruction.

• Socketable modules: Spring-clip/press-fit mounts enable tool-free replacement.

• Active disassembly: Shape-memory alloy fasteners disengage at ~90 °C.

• Removable die-attach: Low-temperature solders (<150 °C) or sintered layers permit die separation.

Capacitors — Sustainable Dielectrics

• Cellulose films: εᵣ ≈ 4.5, breakdown ~300 MV/m, tan δ ≈ 0.002; embodied energy ~40 MJ/kg vs. ~85 MJ/kg for ceramic⁵.

• Recycled PET films: ±3% capacitance drift from –40 °C to 125 °C; ~45% CO₂e reduction vs. electrolytics¹.

Inductors — Sustainable Core Materials

• Amorphous alloys: Bₛ 1.56 T, ~70% lower core loss at 20 kHz vs. ferrite; embodied energy ~22 MJ/kg vs. ~60 MJ/kg for MnZn ferrite⁶.

• Nanocrystalline alloys: μᵣ > 80,000, stable –40 °C to 150 °C.

Connectors — Sintering & Longevity

• Sintered silver joints: Resistivity ~2 µΩ·cm, >1,000 thermal cycles; outlast PCB solder joints in vibration environments⁷.

• Modular shells allow contact replacement and mechanical reuse.

2.2 Medium loops (R3–R7): Reuse, repair, refurbish, remanufacture

Medium-loop R-strategies shift the focus from avoidance to extending product lifetimes by enabling reuse, repair, refurbishment, and remanufacturing without fully breaking components down to raw materials.

PCBs — “xPCB” Technologies

• vPCB: Vitrimer-based; repairable/recyclable; ~1.3× cost of FR-4; >5 repair cycles.

• DissolvPCB: Water-soluble; >95% component recovery; ~1.5× FR-4 cost; ~150 °C thermal limit.

• PCB Renewal: Conductive epoxy rerouting; low cost; reuse until substrate fatigue.

• ProForm: Thermoformed encapsulation; +10–15% cost; full component recovery; slightly lower space efficiency.

Passives — Salvage Center Performance

• Sims Lifecycle (US/EU): 85–90% recovery of capacitors/transformers; 95% pass re-test; longevity comparable to new ⁸.

• TES-AMM (Asia): 15% of passives reused; ~90% meet OEM spec ⁹.

• Centrica Energy Salvage (UK): 70% reinstallation rate in industrial gear; service life within ±5% of new¹⁰.

Connectors — Replaceable Contact Economics

• Contact insert replacement: ~15–25% of full connector cost; housings reused multiple cycles.

• High-reliability (MIL-DTL-38999) rated for 500–1,500 mating cycles before contact change¹¹.

Semiconductors — Retronix/Jabil Data

• Devices: BGAs, FPGAs, power MOSFETs, IGBTs.

• 90% functional yield after reball/re-tin; <3% degradation vs. new after 1,000 h stress testing¹².

Battery Collectors

• Reused Al/Cu collectors: capacity fade <5% vs. new after 100 cycles¹³.

2.3 Residual share (formerly long loops): Recycling & recovery

When short- and medium-loop strategies are no longer technically or economically viable, residual material value is recovered through recycling and metallurgical processes at the end of the product life cycle.

Recycling Processes

• Hydrometallurgy: Cu (>98%), Au (>95%), Pd (>90%) recovery¹⁴.

• Pyrolysis: Separates organics with minimal oxidation⁸.

• Bio-leaching: Microbial extraction of Au, Cu⁸.

Composite/Complex Composition

• PCBs: FR-4 epoxy + glass + Cu (~25%), SnAgCu solder, gold plating.

• Connectors: Thermoplastics + brass/phosphor bronze.

• Semiconductors: Si/SiC dies, copper leadframes, plastic encapsulants.

Precious-Metal Recovery from Chips

• Au bond wires (~20–40 mg/chip), Pd plating (~5–10 mg), Ag pads (~10–50 mg).

• Recovery: Au ~95%, Pd ~85%, Ag ~90%¹⁴.

Firms

• Sims Recycling Solutions: >95% Au yield⁸.

• Umicore: >200 t/year IC waste processed¹⁴.

Battery System Study

• ¹⁵ On-board charger recycling yields: 40% metals, 20% polymers, rest mixed; polymer recovery <10%.

2.4 Reuse at the highest level

Beyond recycling and material recovery, the highest level of circularity is achieved when entire components or sub-systems can be reused with minimal processing and performance loss.

Current Component-Level Reuse

• PCBs: Refurbishing industrial control boards.

• Passives: Reinstalling salvaged HV capacitors in wind turbine converters.

• Connectors: Contact replacement in MIL-DTL-38999 shells.

• Semiconductors: Refurbishing wafer-scale IGBTs in HVDC stations ².

• Battery Collectors: Direct reuse in remanufactured packs¹³.

• Metals: Re-melting recovered copper busbars for new switchgear.

Sub-System Reuse Potential

Power electronics follow a system → sub-system → component hierarchy:

• System: inverter, charger, converter.

• Sub-system: control board, power stage, filter module, cooling assembly.

• Component: PCB, capacitor, IGBT, connector, etc.

Reusing sub-systems rather than individual components retains more material and embodied energy:

• Tested inverter power stages preserve >80% of material and >90% of embodied energy vs. dismantling into components⁴.

• Reduces testing cost per unit, shortens repair lead time, and simplifies logistics.

• Requires modular mechanical and electrical interfaces for swap-in reuse.

3. Reuse adoption index (RAI) and residual share

The Reuse Adoption Index (RAI) is a measure of how widely components are captured in higher-value circular economy loops before reaching end-of-life recycling or disposal.

It is expressed as the proportion of a component group’s total units that are either avoided through design (short loops) or retained in use via reuse, repair, refurbishment, or remanufacture (medium loops).

The remaining portion — the residual share — represents components that bypass these higher-value loops and go directly into long-loop material recovery or waste streams.

High residual share reflects missed opportunities for higher-value loops.