HiK™ Dual Condensers

Thermal Resistance Network in a typical card chassis assembly

Fig 1. Thermal Resistance Network in a typical card chassis assembly

In conduction cooled embedded computing systems the electronics boards are slid into card chassis and ridgidly attached via wedge locks. This allows cards to be easily removed for maintenance or replacement. While wedge locks accomplish the mechanical attachment quite well, they don’t provide an efficient thermal path. Fig 1 shows the thermal path for a typical configuration. Due to high thermal resistances through the wedge lock, nearly 80% of the heat goes through the board directly to the chassis and only 20% goes through the wedge lock. This joint is a thermal bottleneck and is limiting the amount of power that can be dissipated from any given card.

To combat this challenge, ACT developed the HiK™ Dual Condenser Frame. This patented solution uses embedded heat pipe technology to move heat throughout the card. Instead of just moving heat to the card edge, ACT goes one step further and integrates the heat pipe into floating condenser blocks. These blocks sit above the wedge lock creating an even distribution of heat to both sides of the wedge lock. In this configuration, the wedge lock is no longer a thermal path, eliminating multiple thermal resistances. The thin-walls of heat pipes allow them to easily move the small distance required to mechanically attach to the chassis. ACT has demonstrated the ability for these heat pipes to withstand hundreds of clamped/unclamped cycles.

This product greatly reduces the card to chassis interface described in Figure 1. The figure below shows the impact of the Dual Condenser at this interface. This resistance is the temperature difference between the card edge and the chassis wall divided by the dissipated power.

HiK™ Dual Condenser Card Frames allow heat to bypass the wedge lock with movable condenser blocks.

Fig. 2. HiK™ Dual Condenser Card Frames allow heat to bypass the wedge lock with movable condenser blocks.

 

Contact an ACT representative to learn more about these applications