Ceramic substrates carry and insulate an electronic circuit. They are the base on which a conductor pattern is deposited, so the surface is the product.
Alumina substrates are the default carrier for thick film and general power circuits. They are the lowest-cost option, available in the widest range of thicknesses, and 96% alumina remains the industry standard for most industrial circuits.
Alumina is the default engineering ceramic. It combines high hardness (1500-1700 HV) with good electrical insulation and chemical inertness at a lower cost than most technical ceramics, and in 99.8% purity it holds strength to 1700°C while resisting most acids, alkalis and solvents.
It is not the toughest option. At 3-4 MPa·m½ fracture toughness, sharp impact or point loading will chip an edge, so chamfers and radii belong in the drawing from the start.
Specifications
| Thickness | 0.25-2.0 mm |
| Maximum size | up to 200×200 mm |
| Thickness tolerance | ±0.02 mm |
| Camber | under 0.1% of length |
| Surface finish | Ra 0.2-0.8 µm |
| Vias | drilled or laser cut, from 0.1 mm |
| Metallisation | thick film, thin film or DBC available |
Alumina Properties
| Composition | Aluminium oxide, 96% / 99.5% / 99.8% |
| Density | 3.70-3.95 g/cm³ |
| Vickers hardness | 1500-1700 HV |
| Flexural strength | 300-400 MPa |
| Fracture toughness | 3-4 MPa·m½ |
| Max. service temperature | 1500°C (99.8%: 1700°C) |
| Thermal conductivity | 25-35 W/m·K |
| Thermal expansion (20-1000°C) | 8.0 ×10⁻⁶/K |
Machining and Tolerances
Substrates are tape cast or rolled to thickness, fired, then lapped or ground to finished gauge. Vias are drilled or laser cut, and where a circuit needs it the surface is metallised with thick film, thin film or direct bonded copper before delivery.
Where It Is Used
- Power module and IGBT base plates
- LED and high-brightness die attach substrates
- RF and microwave circuit carriers
- Sensor and heater element bases
- Insulated metal substrate replacement in power conversion
Frequently Asked Questions
Which substrate material should I choose?
Alumina for general use and lowest cost, aluminium nitride where heat has to move, and silicon nitride where the circuit sees thermal cycling and mechanical load. We base the choice on heat flux and cycling duty rather than on conductivity alone.
Do you supply metallised substrates?
Yes. Thick film, thin film and direct bonded copper are available, and we can supply either the blank or the finished metallised panel depending on your process.