Chip-on-heat-sink on the metalized surface of CeramCool® heat-sinks makes it possible to achieve an extremely compact design for the entire cooling system. Using ceramic as the material for the heat-sink ensures outstanding thermal conductivity and electrical insulation; the closer it is used to a source of heat, the greater the cooling advantage it offers.
Heat-sensitive semi-conductor components are often mounted onto standard substrates. They need to offer suitable thermal conductivity in addition to electrical insulation. The result is often a “sandwich component” with multiple layers made of different materials. Each layer introduces its own set of risks, thereby restricting thermal conductivity. With CeramCool®, however, the substrate is the heat-sink because this solution uses advanced ceramics such as alumina or aluminum nitride.
Ceramics combine two essential properties: electrical insulation and thermal conductivity. They offer good electromagnetic compatibility and have a thermal expansion coefficient close to that of semiconductor materials. Unlike other materials, ceramics feature the same thermal expansion coefficient and thermal conductivity in all directions. Moreover, ceramics are watertight and UV and corrosion-resistant.
The simplified design combined with the direct, permanent bonding between heat-sensitive electronic components and the CeramCool® surface – chip-on-heat-sink – create the ideal operating conditions.
CeramTec developed chip-on-heat-sink as a revolutionary process for mounting a heat source such as an LED or power semi-conductor directly onto a metalized heat-sink via soldering or Ag sintering. This achieves an optimum thermal connection with the coolant (air or liquid).
To prove the performance capability of the CeramCool® principle in liquid-cooled systems, a directly metalized heat-sink (chip-on-heat-sink) went head to head with a conventional liquid cooler with a soldered-on DCB. During an exhibition, identical load current was applied to both cooling solutions’ IGBTs until a constant temperature was reached. Then the cool down curve was measured. The result: With the same power supplied, ΔT – and thus the thermal resistance – in the CeramCool® system design was only half that of a conventionally designed system.
Comparison: Chip-on-Heatsink/Conventional structure of a Powermodule (Pin = 100 W)
This makes CeramCool® Liquid Cooling one of the most efficient and reliable liquid cooling systems on the market. No other design can achieve this and still assure such a long lifetime. The ceramic heat-sink is perfectly electrically insulated and inert. It can be populated with electrical circuits and advanced components without creating any thermal barriers. This ceramic system’s efficiency grows with the power density.
A fin heat-sink was optimized for 4W cooling and used as a basis for comparison in order to prove the performance capability of the CeramCool® principle in air-cooled systems. The result: The total thermal resistance of the ceramic Rubalit® design is at least 13% better than that of an aluminum assembly with an identical design. Using Alunit® even helped CeramCool® achieve a minimum improvement of 31%.