Aluminum Nitride (AlN) Ceramic: Grade Data, Properties and Components
Aluminum nitride ceramic substrates move heat out of power and RF devices at 80–180 W/m·K depending on grade designation (CoorsTek AlN grade data), with a coefficient of thermal expansion near 4.6 ×10⁻⁶/K (Kyocera, 40–400 °C). The grade, not the material name, sets performance.
Microns Advanced Ceramics Advantage
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Custom high-purity, high-precision aluminum nitride ceramic products
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Variety of customized processes to configure AlN ceramics for you
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Thinnest processing thickness of 0.05mm, diameter tolerance down to Ø0.005mm
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20+ years of production experience with fast-manufacturing equipment
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Thermal conductivity up to 180 W/m·K depending on grade, substrates down to 0.1 mm
What is Aluminum Nitride Ceramic
Aluminum nitride is a covalently bonded ceramic with a density of 3.25–3.30 g/cm³ that sublimes rather than melts, above 2200 °C at atmospheric pressure. Commercial sintered grades deliver 80 to 180 W/m·K depending on grade designation and measurement temperature — roughly five times alumina — while holding volume resistivity above 10¹² Ω·cm. A metal-class thermal path combined with ceramic-class electrical insulation is a rare pairing, and it is what places AlN in power electronics, LED heat sinks, laser diode submounts and RF packaging.
AlN's theoretical single-crystal limit is 320 W/m·K. No commercial sintered grade reaches it, for the reason set out further down this page.
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Aluminum Nitride
AlN Ceramic Main Features
High Thermal Conductivity
Widely used in high-power electronic devices requiring efficient heat dissipation
High-Temp Acid & Alkali Resistance
Strong corrosion resistance in harsh chemical environments
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Good Mechanical Properties
Withstands mechanical shocks and vibrations in demanding conditions
High Hardness
Withstands mechanical wear and processing without cracking
Low Density
Among the highest of all technical ceramics
Absorbing Neutrons
Resistant to a wide range of chemicals
Wear-Resistant
Suitable for demanding high-temp environments
Aluminum Nitride Ceramic Feature Box
Thermal Shock Resistance of Aluminum Nitride Ceramics
Aluminum nitride expands at 4.6 ×10⁻⁶/K over 40–400 °C, against 2–4 ×10⁻⁶/K for silicon and 3.7 ×10⁻⁶/K for silicon carbide over the same range. That proximity is why AlN is specified for direct die attach in electronic packaging, where expansion mismatch across thermal cycles is the usual failure path.
Its chemical resistance is strong against molten metals and most non-oxidizing environments. The exception is water: AlN hydrolyzes on contact, so aqueous cleaning, wet sawing and humid storage are process steps that require qualification rather than defaults.
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AlN/Aluminum Nitride Mechanical Properties
Ranges span published commercial grades at room temperature. Where your design depends on a specific value, specify the grade designation — see the grade table above.
AlN/Aluminum Nitride Physical Properties
Published aluminum nitride thermal conductivity spans 80 to 180 W/m·K across named commercial grades. An AlN conductivity figure is specifiable only when it carries two qualifiers: the grade designation it belongs to, and the temperature it was measured at. Specifying "high thermal conductivity AlN" selects nothing.
Read this table by column, not by row maximum. The highest-conductivity grade is not the strongest: AlN 180 reports 180 W/m·K at the lowest flexural strength, 300 MPa, while AlN-HTC reports 150–170 W/m·K at 375 MPa.
Dielectric strength is comparable only where the test thickness is stated. The 20 and 16 ac-kV/mm figures are measured at 6.35 mm, so neither transfers to a 0.63 mm substrate without re-measurement.
Conductivity in this class is usually derived rather than measured directly. The standard route is ASTM E1461, the flash method, which measures thermal diffusivity; conductivity is then calculated from specific heat capacity and density.
Put the grade designation and the measurement temperature in your drawing notes rather than a target W/m·K number. Two grades that both satisfy a conductivity target can differ by more than 100 W/m·K.
Aluminum Nitride Against Alumina, Silicon Nitride and Beryllium Oxide
AlN buys thermal path at the cost of strength and cost. Accuratus publishes aluminum nitride at 140–180 W/m·K against 35 W/m·K for 99.5% alumina and 29–30 W/m·K for silicon nitride. The same source puts AlN's flexural strength at 320 MPa against 689–830 MPa for silicon nitride, and its fracture toughness at 2.6 against 5.7–6.1 MPa·m½.
Expansion figures are comparable only over a stated range. Copper sits well above every ceramic listed, and that mismatch is the loading mechanism described further down this page.
On beryllium oxide: it appears here as a comparison entity only. OSHA 29 CFR 1910.1024 governs occupational exposure to beryllium in all forms, with a permissible exposure limit of 0.2 µg/m³ as an 8-hour TWA. Any operation generating dust from a fired BeO part sits inside that scope. AlN delivers roughly 60% of BeO's conductivity with none of that exposure control burden.
Where AlN is the wrong choice
Its fracture toughness of 2.6 MPa·m½ is the lowest of the four materials above. That shows up as edge and corner chipping during handling, fixturing, singulation and board assembly, and it worsens as thickness falls. Where mechanical load, impact or thermal cycling dominates, silicon nitride is the stronger path. Where 35 W/m·K is sufficient, alumina is the lower-cost one.
Rank the constraint before the material: if cycle count governs, the comparison is AlN against Si₃N₄-AMB; if steady-state junction temperature governs, it is AlN against alumina; if handling yield governs, it is thickness and edge strategy.
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Why Choose Us, Our AlN Advantages
Microns Advanced Ceramics provides US-based engineering, application support and quality assurance, with factory-direct global manufacturing. You work with an engineer on the specification — grade selection, metallization route, tolerance strategy — before anything is quoted.
We supply alumina, aluminum nitride, boron nitride, zirconia and silicon nitride across prototype, short-run and production volumes, to customers in power electronics, semiconductor equipment, electrical materials and industrial manufacturing.
Manufacturing origin is stated on the quotation rather than implied. Landed cost, documentation and schedule are priced on the same quote instead of surfacing later.
Aluminum Nitride Ceramic for Different Industries
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Mechanical Engineering
Used for wearable parts, cutting equipment, coupling devices, and thermal management components requiring high thermal conductivity.
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Electronic Devices
AlN substrates, packaging materials, and electronic ceramics for high heat-dissipation applications.
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Chemical Industry
Corrosion resistance and chemical stability make AlN suited to chemical pump components, agitators, and valves.
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Medical Devices
Excellent biocompatibility and mechanical strength support use in medical instruments.
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Aerospace
Stability and thermal management under high radiation and temperature environments.
Pressureless Sintering Process of Aluminum Nitride Ceramics
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Metallization Routes for Aluminum Nitride Substrates
The biggest commercial gap on the live page. AlN DBC substrate, AlN AMB and AlN DPC are bottom-funnel queries with zero coverage today.
The metallization route sets the substrate requirement, not the reverse. Thickness, flatness and surface condition all follow from whether the part is destined for DBC, AMB, DPC or thin film. Direct bonded copper joins copper to ceramic at up to about 1060 °C and active metal brazing at about 800 °C. Direct plated copper runs below 200 °C and resolves 0.05 mm line and space against DBC's 0.2 mm.
The route also decides when laser features happen. In the DPC process, vertical conduction is created by laser drilling via holes through the ceramic before plating — a substrate-level operation, not a post-metallization one. That ordering changes how the part is dimensioned and when it is most fragile.
Maximum size against minimum thickness
These parameters are coupled, not independent dropdowns. Handling stress, sintering camber and metallization-induced bow all scale with area and rise as thickness falls, so a size that is routine at 1.0 mm may not be producible at 0.25 mm. State both together with the aspect ratio you need.
Surface condition
As-fired surfaces carry the sintering skin and the loosest dimensional spread. Grinding brings thickness and parallelism under control. Lapping and polishing reduce roughness, which is what thin-film adhesion and fine line definition respond to. Laser scribing defines break lines for singulation after metallization. Each is an added operation with its own yield — specify the finish the route needs and no finer.
Inspection parameters are set by your drawing
Not by a catalog: thickness and parallelism, camber and bow over a stated span, roughness per face, pad geometry and edge pull-back, metallization adhesion, and the singulation break condition.
Why Aluminum Nitride Substrates Fail in the Field
Three mechanisms dominate. Oxygen in the AlN lattice lowers thermal conductivity at the material level. Copper-to-ceramic expansion mismatch cracks the ceramic at pad edges under thermal cycling. Water reacts with AlN surfaces. The first is fixed before the substrate ships. The second and third are design and handling decisions you still control.
Oxygen, aluminium vacancies, and the gap to the theoretical limit
AlN's theoretical thermal conductivity is 320 W/m·K, against the 80–180 W/m·K that datasheets publish for real grades. Oxygen accounts for the gap: one aluminium vacancy is created for every three oxygen atoms accommodated in the AlN lattice, and those vacancies and the oxide phases accompanying them scatter phonons. Sintering chemistry exists to draw oxygen out of the lattice, which is why two grades of one compound land a factor of two apart. Treat 320 W/m·K as a physical ceiling and never as a product figure.
Metallization delamination and CTE-mismatch cracking
Metal and ceramic do not expand at the same rate, so temperature swings produce alternating compression and tensile stress, concentrating as edge cracks in the ceramic at the corners and edges of the copper pads. A thick, strong ceramic with thin copper withstands many more cycles than a thin ceramic with thick copper. Conductor thickness is a reliability decision as much as an electrical one.
Hydrolysis, storage, and wet processes
AlN reacts with water: AlN + 3H₂O → Al(OH)₃ + NH₃, with ammonia detectable during hydrolysis. The published work covers powder rather than sintered substrates, so it establishes the chemistry and not a rate for a fired part. The practical response is the same either way: store parts dry and sealed, and treat aqueous cleaning, wet sawing and humid staging as process steps requiring qualification rather than defaults.
The conductivity you buy is set by the sintering route. The cycles you get are set by your copper thickness and pad geometry. The surface you get is set by how the part is stored and cleaned after it arrives.
What Your RFQ Must State to Be Quoted on the First Pass?
A drawing carrying the ten items below comes back quoted rather than queried — with us or with any supplier.
Tell us at RFQ stage which documentation your program requires and we will confirm what can be supplied for your specific part before you commit. If the part is being dual-sourced, say so on the drawing — a substrate qualified against a named grade designation and a stated measurement condition can be re-quoted and re-qualified later, and one qualified against a headline figure cannot.
Frequently Asked Questions
How well does AlN's thermal expansion match silicon, SiC and GaN?
AlN expands at 4.6 ×10⁻⁶/K over 40–400 °C. Silicon is published at 2–4 ×10⁻⁶/K and silicon carbide at 3.7 ×10⁻⁶/K over the same range. The match is close enough for direct die attach but not exact. CTE values are comparable only over a stated temperature range — a single number with no range attached cannot be used for a match calculation.
Is aluminum nitride an electrical conductor or an insulator?
An insulator. Volume resistivity is above 10¹² Ω·cm at 25 °C and dielectric strength is published at 16–20 ac-kV/mm at 6.35 mm test thickness. AlN is unusual in combining that level of insulation with a thermal conductivity in the metal class.
How does AlN's thermal conductivity compare with aluminium metal?
Aluminium metal conducts at roughly 237 W/m·K. Commercial sintered AlN grades deliver 80–180 W/m·K, so the best grades reach about three quarters of aluminium's conductivity while remaining an electrical insulator. The 320 W/m·K figure sometimes quoted for AlN is its theoretical single-crystal limit, not a product specification.
Is aluminum nitride excellent in electrical insulation?
Yes. High volume resistivity and low dielectric loss make it an excellent insulator even while conducting heat efficiently.
Is aluminum nitride magnetic?
No. AlN is a non-magnetic ceramic, suitable for applications sensitive to magnetic interference.
Is a sintered AlN substrate the same thing as an AlN wafer?
No. Bulk single-crystal AlN wafers are a different product class with different suppliers, different properties and different price points. Everything on this page refers to sintered polycrystalline AlN.
How do I compare two suppliers' conductivity figures?
Only at the same grade designation and the same measurement temperature, and ideally with the same derivation method named. A 20 °C figure and a room-temperature figure from different sources are not the same measurement.
Does AlN chip during handling, and what reduces it?
Its fracture toughness of 2.6 MPa·m½ is the lowest of the four substrate materials compared on this page — below alumina at 4 and well below silicon nitride at 5.7–6.1. Edge protection, dedicated fixturing and a singulation method chosen for break quality matter more than any single strength figure, and the risk rises as thickness falls.