HiK™ Plates

Thermal Plots showing aluminum cover and base (top) versus an aluminum cover with HiK™ base (bottom) for maximum thermal management

Thermal Plots showing aluminum cover and base (top) and aluminum cover with HiK™ base (bottom).

HiK™ or high conductivity plates are heat spreaders with embedded heat pipes to transport heat as desired in your system. These plates are particularly useful for cooling of multiple high-power components and managing the thermal load. The HiK™ plate collects and moves the heat from these discrete heat sources to the liquid-cooled edge or air-cooled heat sinks with minimal temperature gradients.  As electronics continue to move forward with higher power and smaller packaging, HiK™ plates are a great way to move heat to boost performance. Whether it’s adding more power to the system or reducing the hot spot temperature in hot ambient environments, HiK™ plates provide a reliable, easy to integrate thermal solution.

 

Aluminum has a thermal conductivity of 180 W/m K.  As discussed in When to Use Heat Pipes, HiK™ Plates, Vapor Chambers, and Conduction Cooling, the effective conductivity of HiK™ plates ranges from 600 to 1200 W/m K or more.  An additional advantage is that HiK™ plates are less expensive than vapor chambers (which have higher effective thermal conductivities), and much, much less expensive than encapsulated graphite conduction cards (which also have lower effective thermal conductivities).  HiK™ plates can also use L-shaped heat pipes to extend the effective high conductivity around corners.

 

Scroll left to right and right to left using the arrow at the center of the image.  Demonstrates the conventional aluminum plate vs. HiK™ Plate. The conventional aluminum plate’s highest temperature was 90.3° C whereas the HiK™ aluminum plate is 69.1° C. 

Cooling Embedded VME and VPX Systems

Many embedded electronics systems with VME/VPX boards have the following configuration:

VME or VPX System Example- Conduction card heat spreaders

Figure 1.

  • Metal frames under the electronics that serve as heat spreaders to move heat to the card edge
  • Card retainer clamp/wedge lock to mechanically and thermally attach the card to the chassis
    • Allows for easy assembly and rigid attachment
    • Easy to service and replace the cards
  • A chassis that removes heat in one of two ways:
    • Liquid cooling, typically at the base, relying on conduction from chassis
    • Air cooling, using fins directly attached to the chassis sidewalls
Air-cooled conduction card chassis with a single card installed

Figure 2. Air-cooled chassis with a single card installed.

As shown in Figure 2, these chassis have a number of thermal challenges that can be reduced with HiK™ products:

  • (1) Thermal Conductivity (k) of the thin aluminum frames is not high enough to move heat efficiently. Copper causes weight issues
  • (2) Card clamps/wedge locks transfer heat disproportionately into the chassis.
    • 80% through the card frame
    • 20% through the wedge lock
  • (3) The thermal conductivity of the chassis is not high enough to move heat to a liquid-cooled base or spread the heat evenly across the full fin stack.
  • (4) Fin Stacks must be optimized for volume and available airflow.

THE FOLLOWING MATERIALS CAN BE USED:

Traditional Aluminum with embedded copper-water and/or copper-methanol heat pipes.

Low CTE ALSIC where the plate has a low enough CTE for direct attachment of electronic components.

Lightweight Magnesium which have a lower mass than an aluminum plate with equivalent dimensions, with up to three times the effective thermal conductivity of aluminum.

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