Methodology to achieve the thermal management of a 6U conduction-cooled board with 130W power dissipation and an operating temperature of 85°C

Abstract

We are presenting a methodology to optimize the design of a thermally challenging Single Board Computer (SBC) in order to achieve ambitious thermal management goals at reasonable cost. The case study presented describes the design of a conduction cooled SBC in 6U-VPX [1] form factor, dissipating up to 130 W (2 high performance CPUs) and presenting a high density of components (ca 4500 on 640cm2). In order to achieve high reliability (low MTBF), all components must be operated at least 5°C below their maximum rating, while the board's thermal interface, i.e. the upper and lower board edges, are kept at 85°C. Any “active” cooling (including heat pipes) is prohibited. This puts tight constraints on the allowable temperature gradients between the board edges and any of the thermally critical components. It turns out that a heat frame design based on advanced composite materials (aluminium, copper and graphite) can meet these constraints even in the presence of layout constraints that impose a less-than-optimal placement of thermally critical components.