Keramische PCB
(AlN / Al₂O₃ / DPC)
Alumina and aluminium nitride ceramic substrates — up to 170 W/m·K thermal conductivity, stable from -55°C to +350°C, and zero CTE mismatch with SiC and GaN power semiconductors.
The substrate for applications where organic PCBs physically cannot perform
A ceramic PCB uses an alumina (Al₂O₃) or aluminium nitride (AlN) ceramic tile as the substrate — instead of the FR4 or polyimide organic base used in standard PCBs. Copper circuit traces are deposited directly onto the ceramic surface by the Direct Plate Copper (DPC) process or by thick-film screen printing.
The performance difference is not incremental. AlN has thermal conductivity of 170 W/m·K — more than 500× higher than FR4's 0.3 W/m·K. For a 200W SiC MOSFET, this difference means a junction temperature of 180°C on FR4 vs 95°C on AlN — the difference between thermal runaway and reliable operation.
Ceramic substrates are also chemically inert, mechanically stable to 1600°C, and have a coefficient of thermal expansion (CTE) that closely matches SiC (3.7 ppm/°C) and GaN (5.6 ppm/°C) — eliminating the CTE-mismatch fatigue that destroys organic substrate power modules under thermal cycling.
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Three engineering realities that make ceramic the only viable substrate
When temperature, thermal conductivity or CTE matching exceeds what organic substrates handle — the physics require ceramic.
Thermal Conductivity — 500× Better Than FR4
FR4 thermal conductivity: 0.3 W/m·K. Metal core PCB (MCPCB): 1–4 W/m·K. Alumina Al₂O₃: 24 W/m·K. Aluminium nitride AlN: 170 W/m·K. For a 100W power device, this sequence corresponds to junction temperatures of approximately 180°C, 85°C, 45°C and 30°C above ambient respectively. AlN doesn't just perform better — it enables power density levels that organic substrates physically cannot support.
AlN = 170 W/m·K · Al₂O₃ = 24 W/m·K · FR4 = 0.3 W/m·K · 500× differenceZero CTE Mismatch — The End of Thermal Fatigue
SiC has a CTE of 3.7 ppm/°C. FR4's CTE is 14–17 ppm/°C — a 4× mismatch that generates thermal fatigue stress in every power cycle. After 10,000–100,000 cycles, solder joints crack and the device fails. AlN's CTE of 4.5 ppm/°C nearly matches SiC — enabling direct die attach without thermal interface material and module lifetimes measured in decades rather than years.
AlN CTE = 4.5 ppm/°C · SiC CTE = 3.7 ppm/°C · thermal fatigue eliminatedChemical and Temperature Inertness Above 200°C
FR4 epoxy matrix begins to degrade at temperatures approaching its Tg (130–220°C depending on grade) and is attacked by process solvents and harsh cleaning agents. Alumina and AlN ceramics are stable to 1600°C, chemically inert to virtually all industrial solvents and acids, and non-absorbent of moisture. For high-temperature processes, harsh chemical environments and applications requiring 20+ year service life, ceramic is not a premium option — it is the appropriate engineering specification.
stable to 1600°C · chemical inert · moisture-free · 20+ year lifeFull ceramic PCB specification
Al₂O₃ and AlN substrates stocked in-house. Thermal conductivity measured per lot and reported with delivery.
Parameter für die Herstellung
| Substrate Material | Al₂O₃ 96% · Al₂O₃ 99% · AlN |
| Wärmeleitfähigkeit | 24 W/m·K (Al₂O₃) · up to 170 W/m·K (AlN) |
| Prozess | DPC · HTCC · LTCC |
| Min. Spur/Leerzeichen | 25 µm / 25 µm (DPC process) |
| Kupferdicke | 5 µm – 300 µm (DPC) |
Leistung und Standards
| Betriebstemperatur | -55°C to +350°C (ceramic) · +850°C (HTCC) |
| CTE (AlN) | 4.5 ppm/°C — near-match to SiC / GaN |
| Oberfläche | ENIG · bare Cu · Electrolytic Au |
| Substrate Thickness | 0.25 mm – 3.0 mm |
| Surface Roughness (Ra) | < 0.1 µm on die-attach surfaces |
How ceramic PCB is manufactured
Ceramic substrate fabrication combines ceramic sintering, thin-film deposition and precision electrolytic plating — entirely different from organic PCB manufacturing.
Substrate Preparation
Fired ceramic tile (Al₂O₃ or AlN) is cut to size, lapped and polished to Ra < 0.1 µm on die-attach surfaces. Incoming thermal conductivity is verified by laser flash.
PVD Seed Layer
Ti/Cu or Ti/Ni seed layer is deposited by physical vapour deposition (PVD / sputtering) to provide a uniform conductive base for subsequent electroplating.
Electrolytic Copper Plating & Imaging
Copper is electroplated to target thickness (5–300 µm). Circuit traces are patterned by photolithography and etched to final geometry — 25 µm minimum trace width.
Surface Finish & Inspection
ENIG or electrolytic gold finish is applied. 100% optical inspection, electrical test and peel strength testing complete the DPC process.
Where ceramic PCB is the only viable substrate
High temperature, high current density or CTE-matched die-attach — ceramic is the engineering requirement.
SiC & GaN Power Modules
AlN substrates directly under SiC MOSFET and GaN HEMT die — eliminating thermal interface materials.
High-Power LED Arrays
Alumina ceramic for multi-die LED arrays and UV disinfection where junction temperature controls lifespan.
Automotive SiC Inverters
DPC AlN for automotive traction inverter power modules requiring continuous 150°C junction temperature.
RF Power Amplifiers
AlN for RF PA modules requiring simultaneous thermal management and electrical isolation.
Laser Diode Submounts
High-precision ceramic for single-emitter and bar laser diodes requiring sub-micron flatness.
Aerospace Power Electronics
Weight-efficient ceramic for avionics DC-DC converters and satellite power conditioning.
Medical Electrosurgery
High-voltage isolated ceramic for electrosurgical generator output circuits.
Military Power Systems
Military-spec ceramic for radar T/R module power stages operating at extreme temperatures.
Ceramic substrate quality — verified for thermal and mechanical performance.
Copper-ceramic interface adhesion is the life-limiting variable in DPC ceramic substrates under power cycling. Our peel strength testing and thermal cycle qualification confirm the interface quality that determines module operating life — not just day-one electrical integrity.
- ISO 9001 : 2015Von Dritten geprüftes Qualitätsmanagement
- Material CertificationAl₂O₃ and AlN substrate purity documentation
- Thermal Conductivity CoCPer-lot laser flash measurement on AlN
- RoHS / REACHEinhaltung der EU-Vorschriften für gefährliche Stoffe
Inspektions- und Prüfverfahren
- 100% Elektrischer Test - Fliegender TastkopfAll nets, every substrate
- 100% AOICopper trace and dimension inspection
- Copper Peel Strength TestDPC Cu-ceramic interface adhesion per lot
- Thermal Conductivity — Laser FlashPer-lot measurement on AlN substrates
- Surface Roughness (Ra)Profilometry on die-attach surfaces
- Bow and FlatnessLaser profilometry for die-attach planarity
- Thermal Cycling -55°C to +350°CPower cycling qualification on request
- XRF Coating ThicknessENIG / Au finish thickness measurement
Ceramic substrates we have built
Real high-power and high-temperature substrate challenges — solved.
AlN Substrate for 150 kW SiC Inverter
DPC AlN, 170 W/m·K, 300 µm copper for bus bar integration, bare copper surface for direct SiC die attach, -55°C to +175°C operating range.
Junction-to-case thermal resistance 22% below competing alumina design. Passed 10,000 power cycle qualification. Customer achieved 35% higher power density vs previous generation.
500 W UV-C LED Ceramic Array
Al₂O₃ 99%, 24 W/m·K, ENIG finish, 8×8 multi-die array, continuous 120°C operating temperature for UV-C disinfection module.
LED junction temperature 28°C lower than equivalent MCPCB design. Efficiency 8% higher at rated power. Module lifespan exceeded 50,000 hours in accelerated life testing.
AlN Substrate for 200 W GaN PA
DPC AlN, 50 µm trace width for RF feed lines, ENIG, CTE-matched to GaN-on-SiC die, 0.1 µm Ra surface for die attach.
RF performance met specification at first build without layout revision. Thermal measurements 15°C below simulation. Passed MIL-STD-883 qualification first attempt.
Common questions about Ceramic PCB
Technical questions about DPC ceramic substrates, material selection and thermal performance.
DPC (Direct Plate Copper) deposits a thin PVD seed layer directly onto the ceramic surface, then electrolytically plates copper to target thickness. This achieves fine-line capability (25 µm minimum trace width), thin uniform copper and a very smooth surface finish. Thick-film screen printing applies a conductive paste through a screen mask and fires it — minimum line width is typically 100–150 µm and surface roughness is significantly higher. DPC is preferred for power modules, RF applications and precision circuits. Thick-film is used for resistor networks and sensor substrates.
Choose Al₂O₃ (alumina) when thermal conductivity of 24 W/m·K is sufficient and cost is a primary constraint — suitable for LED drivers, general power electronics and medical devices. Choose AlN (aluminium nitride) when your power device junction temperature budget requires conductivity above 80 W/m·K, when CTE matching to SiC or GaN die is critical, or when operating temperatures exceed 200°C continuously. AlN is approximately 3–4× the cost of alumina.
The minimum copper thickness in our DPC process is 5 µm (for signal-layer applications). Standard power module copper is 100–200 µm. For bus bar and high-current applications, copper up to 300 µm is achievable. Copper thickness affects current carrying capacity, thermal resistance and the required minimum trace width — thicker copper requires wider traces to maintain uniform plating.
Yes — DPC ceramic with bare copper or ENIG finish is suitable for direct die attach using silver sinter paste, gold-tin (AuSn) solder or SAC305 solder. For direct silver sinter, the copper surface must be silver-plated after DPC. The ceramic substrate provides the CTE match to the die and the thermal path to the heat sink, eliminating thermal interface material layers and their associated thermal resistance.
Thermal conductivity of AlN substrates is measured by laser flash analysis (LFA) on material coupons cut from the same production lot as the substrates shipped. We report the measured value in the material Certificate of Conformance (CoC) delivered with each order. Typical measured values for our standard AlN grade are 155–170 W/m·K. If your thermal model requires a specific minimum value, specify it at enquiry stage.
DPC ceramic substrates with copper traces are rated for continuous operation to 350°C. The copper-ceramic bond begins to degrade above 400°C due to differential CTE. For applications requiring operation above 350°C, HTCC (High Temperature Co-fired Ceramic, fired at 1500°C) with refractory metal conductors (W, Mo) is the appropriate technology — consult our engineering team for HTCC capability.
Get your ceramic substrate design reviewed — today.
Send your thermal requirements, die-attach spec and power cycling profile. Our ceramic engineers return a material recommendation and DPC process review within 8 hours.
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