Eliminate hot spots in your embedded computing system and keep your electronics performing longer. Standard off-the-shelf VME / VPX card frames can be enhanced with thermal management technologies offered by ACT. From ICE-Lok® enhanced wedge locks that reduce up to 30% of your cards heat load to HiK™ card frames or enhanced VPX card frames that have embedded heat pipes to eliminate hot spots and move heat from the chip to the board. Both technologies can be applied to terrestrial and space grade VME/VPX cards.
COOLING EMBEDDED VME AND VPX SYSTEMS
Many embedded electronics systems with VME/VPX boards have the following configuration:
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
HIK™ CARD FRAMES SOLVE THERMAL MANAGEMENT CHALLENGES
HiK™ card frames increase thermal conductivity. In conduction systems, it’s paramount to get heat efficiently to the edge, and spread heat along the edge to lower heat flux into the chassis. Heat pipes can be strategically placed to accomplish both goals simultaneously. On air-cooled boards, the increased thermal conductivity will isothermalize the fin stack base and reduce hot spots, optimizing fin efficiency. As shown in Figure 2, these chassis have several 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.
EMBEDDED COMPUTING SPACE SYSTEMS THERMAL MANAGEMENT
Embedded computing systems are leveraged across many mission-critical platforms, but few with more challenging requirements than space vehicles. The power requirements for on-board processing, optoelectronics and other high heat flux components are very similar to terrestrial embedded computing applications; however, the space environment adds temperature extremes and other operational conditions that make the thermal design a major factor in system architecture.
When operating in the vacuum of space, heat must be transferred long distances to adequate radiator surface area. The conduction paths from component to card edge and from chassis to the radiator are often limited by the thermal conductivity of the base metal. Due to the high heat flux of the electronics and conduction being the primary bottleneck, copper-water heat pipes are an ideal solution- the challenge is making them so they can survive the mission! Through years of development, ACT has qualified and flown SCWHPs that feature more robust manufacturing techniques to survive the severities of space. An example of a 4U Space VPX board having three (3) SCWHPs transferring heat from components to the card edge is shown below.
