Ceramic PCBs - High Thermal Conductivity, Low Expansion

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Thermal Management Optimisation

Ceramic PCBs

About Ceramic PCBs

With the increasing popularity and availability of ceramic PCBs circuit designers have considerably more options at their disposal.  Ceramic substrates have excellent thermal performance, Thermal Conductivity to 180W/mK, and can sustain high working temperatures. They are essential for high-power packages with thermal issues to solve.

Because of the mechanical and thermal advantages, ceramics have been utilised extensively in electronics and electronic components for many years. Recent technological and manufacturing advancements have led to the replacement of complete PCBs.

Advantages Over Other Technologies

The main advantage ceramic has over more traditional materials like FR4 and Metal Clad PCBs is heat dissipation. The transfer of heat through the boards is much more effective when components are placed directly on the boards without the use of a dielectric layer.

 

Additionally, ceramic material has a very low CTE (Coefficient of Thermal Expansion), which gives circuit designers more compatibility options. Ceramic material can endure high operating temperatures (up to 800°C).

See a full list of advantages below:

  • Through Hole Plating available with DPC technology
  • Superior values of Thermal Conductivity (up to 180W/mK)
  • Higher operating temperatures up to 800°C
  • Lower CTE
  • Suitable for high-frequency applications due to low signal loss
  • Possibility for Hermetic packages with 0% water absorption

GSPK Circuits Capabilities

GSPK specialises in Alumina Oxide (Al2O3), Aluminium Nitride (AIN), and Silicon Nitride (SiN)  boards. Direct bond copper (DBC), direct plated copper (DPC) Active Metal Brazing (AMB), and Thick Film technologies are used for the circuitry depending on the requirements and/or applications.

Depending on the technology required or the end application, circuits can be printed using either Copper (Cu) or Silver (Ag).

If using a Copper (Cu) track, solder resist/ident/surface finish options are much the same as conventional PCBs. If Silver (Ag) is being used we use a clear/glass solder mask. Gold plating can also be used in certain applications where the silver pads require protection.

See below for more information on Al2O3, AIN, and other technologies available.

Alumina Oxide (Al2O3) PCB (96% & 99.6%)
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About

Alumina Oxide 96% is the most popular Ceramic substrate for PCBs. By the nature of the material it has excellent electrical insulation and exhibits excellent thermal characteristics. Although Alumina’s thermal conductivity is not as high as Aluminium Nitrides', it is still significantly greater than the best Metal Clad PCB materials, which have a thermal conductivity of about 24 W/mK for the 96% variant.

Alumina Oxide is a material that works well for LED applications because of its strong light reflection and favourable thermal characteristics. While having low thermal expansion and signal loss values, it can be used for a variety of applications, such as cooling systems, high-frequency systems, and sensor modules.

Advantages

  • High values of Thermal Conductivity (24-29W/mK)
  • High operating temperatures up to 800°C
  • Low CTE
  • Suitable for high frequency applications due to low signal loss
  • High light reflectivity
  • 0% water absorption – ideal for Hermetic packages

Technical Specifications

Download our complete design rules and manufacturing capabilities below.

If you have different requirements, or have any questions please contact us.

Ceramic Manufacturing Capabilities document

Aluminium Nitride (AlN)
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About

Aluminium Nitride (AlN) is an ideal choice when a high thermal conductivity is needed. AlN has a better thermal conductivity than other materials; up to 180 W/mK.

AlN is suited for a wide range of applications, such as high power LEDs, testing, sensors, integrated components (ICs), and more. It also has a very low CTE and high operating temperatures .

Advantages

  • Superior values of Thermal Conductivity (Up to 180W/mK)
  • High operating temperatures up to 850°C
  • Very Low CTE
  • Suitable for high frequency applications due to low signal loss
  • 0% water absorption - ideal for Hermetic packages

Technical Specifications

Download our complete design rules and manufacturing capabilities below.

If you have different requirements, or have any questions please contact us.

Ceramic Manufacturing Capabilities document

Silicon Nitride PCB
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Property Unit SiN
Thermal Conductivity W/mK 85
Maximum Operating Temperature (MOT) °C 1000
Coefficient of Thermal Expansion (CTE) x 10¯6/K 2.6
Dielectric Constant - 9
Signal Loss x 10¯3 0.2
Light Reflectivity % -
Breakdown Voltage KV/mm 15
Rupture Strength Mpa 800
  • SiN is more desirable when the end application will be exposed to significant amounts of vibration, such as the automobile industry, due to its high rupture strength
  • The thermal conductivity ranges of SiN is between 85 and 90 W/mK putting it in-between Al2O3 and AlN
  • Max operating temperatures of over 850°C
  • CTE is extremely low
  • Low signal loss makes it suitable for high frequency applications
  • Possibility of hermetic packages as no water is absorbed
Active Metal Brazing (AMB)
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Active Metal Brazing (AMB) - Ceramic PCBs

Active Metal Brazing is a new novel technique for producing ceramics without metallization (AMB).

AMB "brazes" the copper directly to the ceramic substrate while operating at high temperatures in a vacuum.

AMB creates a substrate with exceptional heat dissipation qualities in a highly reliable substrate.

The brazing process is perfect for Power Electronics applications because it can create copper weights of up to 800µm on extremely thin ceramic substrates.

AMB Single Sided

The possible copper weights and matching substrate thicknesses are listed in the table below. It is always advised that the copper thickness be kept to no more than half the thickness of the ceramic for mechanical stability.

AMB Double Sided

With copper both sides a higher stability and mechanical strength is achieved enabling Heavy Copper to be offered on thin ceramic substrates. The following is a guide on double sided material availability although during the etching process original copper weights can be reduced.

Active Metal Brazing Double Sided Panels
  200µm 250µm 300µm 400µm 500µm 800µm
0.25mm SiN
AlN
SiN
AlN
SiN SiN SiN SiN
0.32mm SiN SiN SiN SiN SiN SiN
0.38mm AlN AlN AlN      
0.63mm AlN AlN AlN AlN AlN  
1.00mm AlN AlN AlN AlN AlN AlN
Copper Thickness
Ceramic Thickness
Immersion Tin Panel Immersion Tin Panel
AIN used for UV LED products AIN used for UV LED products
Silver Paste Conductor with ENIG surface treatment Silver Paste Conductor with ENIG surface treatment
Direct Bond Copper Direct Bond Copper
Alumina Oxide Al203 Alumina Oxide Al203
Alumina Oxide Al203 Alumina Oxide Al203