An improved circuit board assembly includes a cover or other member
disposed adjacent to the substrate and, for example, spaced therefrom so
as to define a plenum. Self-aligning heat sinks (or other heat dissipative
elements) are spring-mounted (or otherwise resiliently mounted) to the
cover and, thereby, placed in thermal contact with one or more of the
circuit components. Flow-diverting elements are provided, e.g., so that
the overall impedance of the board substantially matches that of one or
more of the other circuit boards in a common chassis. The circuit board
cover can be adapted to provide thermal and/or electromagnetic emission
control, as well as shock and vibration. A connector arrangement provides
electrical, mechanical and/or other operational coupling between the
circuit board and a chassis regardless of whether the board is disposed in
a slot on a first (e.g., upper) side of a source of cooling air for the
chassis or on a second (e.g, lower) opposite side of that source. A
circuit board can have one or two portions, each with an air flow inlet
edge through which cooling air flow is received and an air flow outlet
edge through which the air flow exists. An improved chassis for mounting
of such circuit boards can have a center air inlet. It can also have a
circuit-board insertion slot with a first air flow aperture disposed
adjacent to a first edge of an inserted circuit board and a second
apertures disposed adjacent to a second edge of the board. These apertures
can be sized so that the impedance to air flow to a circuit board inserted
in the slot substantially matches that to one or more other boards in the
chassis. Such slots can form part of a card cage that is vacuum or dip
brazed, or manufactured by an alternate process yielding a cage of desired
structural stiffness and air-flow/interference sealing. The circuit boards
and chassis can include an air and/or electromagnetic interference (EMI)
seal which forms as the circuit board is inserted into the chassis slot.
