HiK Plates
HiK AlSiC Plates for power electronics cooling
The HiK Plate is particularly useful for cooling of multiple high power components. A typical application involves multiple high power electronic devices mounted on the HiK Plate. The HiK Plate collects and moves the heat from these discrete heat sources to the edge mount liquid or air heat sinks with minimal temperature gradients (i.e. thermal resistances).
Traditional aluminum, AlSiC and copper plates have thermal conductivities between 180 and 380 W/m-°C. The HiK Plates have effective thermal conductivities that are at least several factors higher. ACT has designed and manufactured HiK Plates having effective thermal conductivities ranging from 500 to 800 W/m-°C.
The following two figures compare the performances of a conventional aluminum plate (first figure) and a HiK Aluminum Plate (second figure), under the same heat loads. The highest temperature on the aluminum plate is 90.3°C. The highest temperature on the HiK Aluminum Plate is 69.1°C, a 20°C reduction in the hot spot temperature.
Temperature Profile on an Aluminum plate
Temperature Profile on a HiK Aluminum Plate
The layout of the embedded heat pipes is often custom-optimized based on the heat source profiles and locations. A higher concentration of heat pipes may be embedded in areas on the plate where large heat sources are attached. The embedded heat pipe can be straight or bent for optimum performance.
ACT is a leader in
HiK Plate design
and manufacture.
Many electronics cooling applications require the heat spreaders to be able to survive in cold ambient conditions. ACT designs and manufactures its heat pipes to be tolerant of large numbers of working fluid (water) freeze/thaw cycles. Each HiK Plate design is qualified by a series of freeze/thaw tests at various orientations. Surface coatings and finishes may be applied to the HiK Plates to provide weather resistance as required by specific applications.
Compared to the HiK Aluminum Plate, the HiK AlSiC plate offers an additional feature of being CTE tailorable. By controlling the composition of the Al and SiC, the CTE (coefficient of thermal expansion) of the plate can be matched to that of the electronic device. This allows for the direct attachment of the electronic device to the plate, eliminating the need for stress compensating thermal interface materials and consequently reducing the thermal interface resistance.
The following two figures compare the thermal conductivity to the CTE as well as the cost for several commercially available heat-spreading materials [Knippscheer and Bollina, 2008].
Thermal Conductivity vs. CTE of Various Materials
(click for larger version)
Cost vs. Thermal Conductivity of Various Heat spreaders (click for larger version)
In general, a HiK plate has a thermal conductivity comparable to high performance composite materials but can be manufactured at a reduced cost.