AMB Ceramic Copper-Clad Substrates: Engineered for New Energy Power Density
Puwei's Active Metal Brazing (AMB) Ceramic Copper-Clad Substrates represent the pinnacle of high-reliability interconnection technology for next-generation power electronics. Designed specifically to meet the extreme thermal, mechanical, and electrical demands of new energy applications, AMB technology creates an unbreakable metallurgical bond between copper and ceramic. This substrate is the cornerstone for building compact, efficient, and ultra-reliable power modules in Electric Vehicles (EVs), Renewable Energy, and Industrial Drives, directly addressing the core challenges of heat dissipation, power cycling, and long-term durability in high-power microelectronic components.
Why AMB is the Superior Choice for Demanding New Energy Applications
- Unmatched Bond Strength & Reliability (>80 MPa): The active metal brazing process forms a chemical-metallurgical bond, virtually eliminating the risk of copper delamination under extreme thermal cycling—a critical advantage over traditional DBC for high-vibration automotive and industrial environments.
- Superior Thermal & Mechanical Performance with Si3N4: Silicon Nitride (Si3N4) AMB offers an exceptional combination of high thermal conductivity (>90 W/mK), outstanding flexural strength, and a CTE that closely matches Silicon Carbide (SiC) and other wide-bandgap semiconductors, drastically reducing thermomechanical stress in power devices.
- Highest Power Density & Current Capacity: Supports thick copper layers (up to 0.8mm standard, 2.00mm custom) enabling extremely high current carrying capacity (>500A), allowing for more compact inverter and converter designs in EVs and solar systems.
- Exceptional Thermal Cycling Lifetime (>5,000 cycles): Proven reliability under harsh temperature swings (-55°C to 150°C), far exceeding the lifespan of standard substrates, which translates directly into extended product warranty and reduced field failures.
- Material Flexibility for Design Optimization: Choose from AlN-AMB for maximum heat conduction (up to 200 W/mK), Si3N4-AMB for ultimate strength and reliability, or Al2O3-AMB for cost-effective solutions—all within the same robust AMB bonding architecture.
Technical Specifications
Our AMB substrates are engineered with precision to provide consistent, high-performance characteristics critical for your power module design.
Available Material Systems & Configurations
- Ceramic Options:
- Aluminum Nitride (AlN): Ultra-high thermal conductivity (180-200 W/mK).
- Silicon Nitride (Si3N4): Best-in-class mechanical strength, fracture toughness, and excellent thermal conductivity (>90 W/mK) with perfect CTE match for SiC.
- Alumina (Al2O3 - 96% & 99%): Cost-effective and reliable with good electrical insulation.
- Copper Layer: Oxygen-Free High Conductivity (OFHC) Copper, thickness from 0.3mm to 0.8mm (standard), customizable up to 2.00mm.
- Ceramic Thickness: 0.25mm, 0.32mm, 0.38mm, 0.63mm, 1.0mm (Custom available).
- Panel Size: Standard up to 240mm x 280mm. Larger formats for specific applications upon request.
Key Performance Parameters
- Peel Strength (Copper to Ceramic): > 80 MPa (Typically 100-150 MPa).
- Thermal Conductivity: AlN: 180-200 W/mK | Si3N4: >90 W/mK | Al2O3 (99%): 24-28 W/mK.
- Dielectric Strength: > 20 kV/mm.
- Coefficient of Thermal Expansion (CTE): Si3N4: ~3.2 ppm/K | AlN: ~4.5 ppm/K | Al2O3: ~6.8 ppm/K.
- Operating Temperature Range: -55°C to +400°C (continuous).
- Thermal Cycling Performance: > 5,000 cycles (-55°C to +150°C) per industry standard tests.
AMB Technology: The Robust Bonding Solution
Active Metal Brazing (AMB) is a vacuum brazing process using a special solder paste containing active elements like Titanium (Ti) or Zirconium (Zr). During high-temperature firing, these active elements react with the ceramic surface, creating a strong chemical bond, while the solder alloy wets and bonds to the copper foil. This results in a dense, void-free, and exceptionally strong interface.
Why AMB Outperforms DBC and DPC
- vs. Direct Bonded Copper (DBC): AMB provides significantly higher peel strength and better resistance to thermal fatigue and delamination, especially with challenging ceramics like Si3N4. Ideal for applications with severe mechanical stress or extreme temperature swings.
- vs. Direct Plated Copper (DPC): AMB supports much thicker copper layers (for higher current) and offers superior thermal performance due to the absence of a plated seed layer interface. It is the preferred choice for high-power, high-current modules rather than high-frequency modules where fine features are paramount.
- vs. Conventional Thick Film Metallization: AMB provides a fully dense, solderable copper surface ideal for high-power die attach and heavy wire bonding, unlike printed thick film conductors used in some hybrid micro circuits.
Primary Application Scenarios in New Energy & Beyond
1. Electric & Hybrid Vehicle (EV/HEV) Powertrains
The substrate of choice for main traction inverters, onboard chargers (OBC), and DC-DC converters. Si3N4-AMB is particularly critical for 800V+ architectures using SiC MOSFETs/IGBTs, where its CTE matching and high reliability under aggressive driving cycles are essential. It serves as the core insulation element and heat spreader in these power devices.
2. Renewable Energy Power Conversion
Central to solar inverters (both string and central), wind turbine converters, and energy storage system (ESS) inverters. AMB substrates handle high power density and outdoor environmental stresses, improving efficiency and lifetime of integrated circuit-based power stacks.
3. Industrial Motor Drives & UPS Systems
Used in high-power AC drives, servo drives, and Uninterruptible Power Supplies (UPS) where reliability and continuous operation are critical. The robust construction withstands industrial electrical noise and thermal stress.
4. Rail Transportation & Marine Electrification
Essential for traction converters and auxiliary power units in trains, trams, and ships. The exceptional thermal cycling and vibration resistance meet the stringent requirements of transportation standards.
5. Aerospace & Defense Power Systems
Finding applications in more-electric aircraft (MEA) power distribution and military vehicle electrification, where weight, power density, and extreme environment reliability are paramount.
Integration & Design for Manufacturing (DFM) Guidance
Successfully integrating AMB substrates requires careful planning. Follow this roadmap for optimal results.
- Material Selection: Choose the ceramic based on thermal, mechanical, and cost targets. Use our expertise: Si3N4 for highest reliability with SiC, AlN for maximum heat flux, Al2O3 for cost-sensitive applications.
- Design & Layout (with Puwei Support): Provide your circuit layout. We will advise on manufacturable trace widths, spacing, and copper balancing to minimize warpage during the high-temperature brazing process. We handle precision etching.
- Substrate Preparation & Inspection: Upon receipt, inspect for visual defects. Clean with standard solvents (IPA) if necessary. For high-reliability assemblies, plasma cleaning is recommended to ensure perfect wettability for solder or epoxy die attach.
- Component Assembly:
- Die Attach: Solder (SnAgCu, high-Pb) or silver sintering are preferred for power dies. The flat, solderable copper surface is ideal.
- Wire Bonding: Thick aluminum or copper wires can be bonded directly to the copper traces.
- Busbar/ Terminal Attachment: Solder or screw to designated high-current pads.
- Thermal Interface & Housing: Attach the substrate assembly to the heatsink using thermal grease, gap pads, or phase-change materials. Ensure even pressure. The substrate can be integrated into various module housings (transfer mold, epoxy gel, hard case).
- Testing & Validation: Perform standard electrical tests (HiPot, insulation resistance) and thermal characterization (Rth-jc). Puwei can provide substrates pre-tested for critical parameters.
Customization & Full-Scope OEM/ODM Services
Every power module is unique. Puwei provides end-to-end co-engineering support to tailor the AMB substrate to your exact system requirements.
Our Customization Capabilities Include:
- Full Custom Sizes & Shapes: Non-standard dimensions, cut-outs, and contours machined post-brazing.
- Complex Multi-Layer & Pattern Design: Single/double-sided, intricate circuit patterns with fine features, and multi-step copper thickness on the same substrate.
- Specialized Surface Finishes: Immersion Tin (ImSn), Immersion Silver (ImAg), Electrolytic Ni/Au, or ENEPIG on the copper traces for specific solderability or wire bonding needs.
- Hybrid Constructions: Integration of different ceramic types or combination with other Puwei products like Alumina Ceramic Substrate (Al2O3) insulators or CERAMIC COMPONENTS into a single assembly.
- Rapid Prototyping & Volume Scale-up: From quick-turn prototype samples to high-volume manufacturing with consistent quality.
Advanced Manufacturing Process & Quality Assurance
Our state-of-the-art manufacturing process ensures every AMB substrate meets the highest standards of quality and performance.
- Ceramic Blank Preparation: High-purity ceramic powder is formed and sintered into precise blanks with controlled microstructure.
- Surface Activation & Paste Printing: The ceramic surface is prepared, and the active metal braze paste is applied with precise screen printing.
- Copper Foil Lamination & Vacuum Brazing: Oxygen-free copper foil is placed over the paste. The stack undergoes vacuum brazing at ~800°C, where the active elements diffuse and create the permanent bond.
- Post-Braze Processing: The bonded assembly is cleaned and may undergo heat treatment to optimize the bond interface.
- Precision Etching: Photolithography and chemical etching define the customer's specific circuit pattern on the copper layer.
- Final Machining & Plating: Substrates are cut to final size, edges are smoothed, and surface finish (Ni/Au, etc.) is applied if specified.
- Rigorous 100% Inspection & Testing: Every substrate undergoes visual (AOI), dimensional, and electrical testing (HiPot). Peel strength, thermal cycling, and microsection analysis are performed on sample batches.
Certifications, Compliance & Global Standards
Quality and reliability are built into our process, aligning with the stringent requirements of global industries.
- Quality Management System: ISO 9001:2015 Certified.
- Material & Environmental Compliance: Fully compliant with RoHS and REACH. Halogen-free options available.
- Automotive Alignment: Our processes and quality controls are developed in line with the core principles of IATF 16949 to serve the automotive supply chain.
- Reliability & Qualification Testing: We support customer qualification with data from standard tests (thermal shock, thermal cycling, HAST, Power Cycling) and can perform custom testing per your specifications.
- Traceability: Full material and process traceability for every production batch.
