Alumina Oxide (Al2O3) 96% or Alumina 96% is the most used ceramic material for ceramic printed circuit boards and packages. Thanks to its good thermal properties, low expansion and hermeticity in combination with a relatively low cost and a more easy handling. Applications include cooling and heating applications, LED boards, medical circuits, sensor modules and high-frequency devices.
Alumina 96% advantages over other printed circuit boards:
- Higher operating temperature up to 350ºC
- Lower expansion coefficient (6-8 ppm/ºC)
- Good thermal properties (22-24 W/mK)
- Superior high-frequency performance
- Smaller package size due to integration and multi-layer possibilities
- Cost effective for dense package due to parallel processing of layers
- Hermetic packages possible, 0% water absorption
- Good light reflection due to white color.
- Limited to no outgassing
- Strong rigid material
DK Thermal manufacturers Alumina Oxide (Al2O3) 96% by using both thick film process as well as Direct Plated Copper Technologies (DPC) to print the circuits.
Circuits can either be printed using Copper (Cu) or Silver (Ag) depending on the application and the request. Copper is offered in DPC and silver using a thick film process. We advise copper in 1-2 layer applications from low to high volume applications. Silver is advised when going to multi-layer and only in medium to high volume due to the higher tooling costs. In case you are unsure what material to specify, please do not hesitate to contact us.
Solder resist and surface finishes can be applied similarly to regular PCB when copper metallization is used. However, for silver thick film designs, we offer only a glass solder mask which is recommended for high-temperature designs. For high sulfur environments where silver corrosion can be an issue, we offer Gold plating as a solution to protect the exposed pads.
Material properties Al2O3 96%
AluminaOxide 96% or Al2O3 is the most widely used ceramic substrates thanks to its low cost and bright white color.
|Material - Aluminium%||%||96% (more is possible)|
|Electrical||Dielectric Constant (1MHz)||-||9.8|
|Dielectric strenght||MV/m or KV/mm||>14|
|Mechanical||Density after Sintering (Bulk density)||g/cm3||3.72|
|Flexural Strength (3 point)||Mpa||400|
|Thermal||Coefficient of Thermal Expansion (CTE)||ppm/°C||5.95|
|Coefficient of Thermal Expansion (CTE) RT~500 °C||ppm/°C||6.82|
|Thermal Conductivity (25°C)||W/m‧K||22|
* Reflectivity test reference thickness of 1mm * Reflectivity test reference thickness of 0.5mm
The data shown is typical of commercially available material and is only offered for comparative purposes. The information shall not to be interpreted as absolute material properties nor does it constitute a representation or warranty for which we assume legal liability. User shall determine suitability of the material for the intended use and assumes all risk and liability whatsoever in connection therewith.
Frequently asked questions (faq)
Why do you claim Alumina Oxide PCB (Al2O3) have a good thermal conductivity compared metal core PCB (IMS) when you know Al (160 W/mK) and Cu (>200 W/mK) have a much higher thermal conductivity compared to Al2O3 (22 W/mK)?
Al & Cu have indeed high thermal performances but the dielectric layer which separates the metal core from the conductive traces will increase the thermal resistance significantly. Both the dielectric by itself (usually <3 W/mK thermal conductivity) as the interface resistance will reduce the total thermal performance. Depending on the thickness of this layer (<10 W/mK) the thermal conductivity of the board can be reduced by 70-90%!
Alumina 96% (Al2O3), on the other hand, is a dielectric material and thus traces can be placed directly onto the board eliminating any loss in conductivity. Additionally, DK thermal is using As well Copper (Cu) (396 W/mK)) and Silver (Ag) (400 W/mK) metallization allowing the heat to spread even better over a large ceramic surface away from the sensitive component and down to the heatsink.
Are Aluminum Oxide PCBs expensive?
While ceramic boards are usually more expensive then FR4 & CEM3 boards, the cost of thick film Al2O3 is in line with high-end Al metal core PCBs and even below Cu metal core PCBs. Also, thanks to better thermal management and reliability, costs can be saved on other parts of the design making the total price lower.
Can ceramic PCBs pass reflow and be used in SMT & pick-and-place machines?
Yes, both are possible.
Can Al2O3 PCBs be multi-layer?
Yes, and we have experience in making multilayer ceramic circuits up to 4 layers. More layers might be possible, please enquire.
How big can Alumina boards be?
Our standard size is 125mmx125mm or 5″x 5″ panels. Upon request, we can accommodate boards up to 180mm x 180mm (7″x 7″) or even larger.
Is there also a solder mask layer, surface finish and silkscreen possible?
Yes. The possibilities depend on the manufacturing process. Solder mask similar to other PCB can be applied in most cases, however, we do also offer a glass for high-temperature solutions which can be transparent or black.
Surface finish has a similar reasoning, however, for high-temperature applications, we offer only silver and gold plating.
Last but not least, applying silkscreen is no issue.
What should I take into account when designing circuits layouts for a ceramic board? What are your design rules?
You can download and see our complete design rules under ‘Design & cost’ in the top menu
What is the difference between Thick film ceramics and LTCC?
Thick film ceramic boards are post fired which means vias, traces, stacking, etc… are only done after the board has been ‘baked’ already and is in its sturdy and hard form. On the other hand, LTCC or Low-Temperature Co-fired Ceramics are still in a relatively soft state when cavities, vias & holes are punched and traces are printed. This way, it is still possible to smooth & round inclinations so multi-shape and angled designs are possible. Only after this process, the board will be co-fired at a temperature of 900°C.