Advanced Heat Sink Materials for High Performance Thermal Management

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Heatsink for laser application

Technology abstract

A metal diamond composite material exhibiting enhanced isotropic thermal conductivities (400-600 W/mK) and an adaptable coefficient of thermal expansion (6-10ppm/K) was developed. The composite material can be soldered and even brazed to metal or ceramics up to temperatures of 800°C.

This allows reliable thermal management for high-tech electronic components while enhancing design flexibility. The technology developed by an Austrian SME is patented.

Technology Description

The combination of a metallic matrix (e.g. Cu, Ag or Al) with a high thermal conductivity in combination with a reinforcement such as diamond with a low Coefficient of Thermal Expansion (CTE) results in a material with tailorable thermal properties. These are obtained by varying the volume content of the diamond particles between 10 and 60 vol.%. or the processing conditions. High surface quality can be achieved by simultaneous processing of metal layers in combination with the metal-diamond composite. This allows for a later-on surface finishing via grinding and polishing and obtaining excellent surface quality (Ra<1µm)
 
The used processing technology allows preparing parts with a certain degree of geometric complexity. Plates for applications such as e.g. IGBT base-plates can be prepared including holes/threads; heat spreaders for CPUs can be prepared including cavities or heat sinks for laser diodes with perfect surface finish by realising the above mentioned sandwich structures.
 
DiaCool combines a high thermal conductivity with a low CTE matching the characteristics of materials such as Si, GaAs, GaN or SiC or of typically used substrate materials such as Al2O3 or AlN. This reduces internal thermo-mechanical stresses during thermal cycling between ambient temperature operating temperatures.
 
DiaCool  products can be supplied with tailored thermo-physical properties in a broad range, depending on the specific composition and manufacturing conditions, namely the
-  thermal conductivity can be varied between 300 to 600 W/mK
- coefficient of thermal expansion can be varied between 6 ppm/K to 14 ppm/K
- density of the material is in the range of 5.5 to 8 g/cm3 for Cu/Ag and 3 g/cm3 for Al based materials.
 
DiaCool  products can be supplied in various sizes between 10mm x 10mm up to approx. 150mm x 150mm. The plate thickness can vary between 1 and about 50 mm, preferably between 3 and 10 mm. Further they can be machined for complex pin-fin structures and other geometric arrangements.
 
The company has extensive experience in material development and various hot pressing technologies, focusing on R&D of innovative new material properties. 

 

Innovations & Advantages

Characteristics:
·        Thermal conductivities of 400 – 600 W/mK
·        coefficient of thermal expansion tailorable between 6 – 10 ppm/K
·        isotropic material properties
·        the materials can be soldered and brazed (up to 800°C)
·        operating temperatures up to 200°C
·        wider range of design flexibility, e.g. integrated pin-fin structures or cooling channels
·        surface quality comparable to metals (due to sandwich structure)
·        cutting, grinding, lapping, coating (Ni, Au, Ag,…) possible

The innovative new material significantly increases flexibility in electronics design processes, allows higher heat flux and power densities on tight geometric dimensions (like for chip-on-board solutions). Because of its physical properties described (high thermal conductivity & reduced coefficient of thermal expansion), lifetime is increased and failures due to active or passive thermal cycling are reduced. 

 

Current and Potential Domains of Application

Cooling plates, heat sinks for:
·        GaN devices
·        Laser-Diodes
·        High Brightness (high power) LEDs
·        Power Electronic modules
·        RF-Generators
·        MW-packages
·        Microelectronic packages
·        Thermal management of high thermally loaded electronic components
·        Solid State Lasers
 
Examples for application areas are IGBTs in Hybrid/Electric vehicles, DC/DC convertors and DC/AC invertors for alternative energy power generation among others, laser bars and high power laser diodes, GaN devices or high brighness LEDs. DiaCool can be combined and integrated in pin-fin heat dissipators or with cooling channels for liquid cooling. It can be used as heat spreaders or heat sinks for microwave, optoelectronic or power electronic applications and in microprocessor lids or flip chip lids.