Using Off-The-Shelf Footprint Compatible Heatsinks

The following solutions is applicable to:

The following requirements have to be fulfill:

The following selection criteria are to be considered:

It is recommended to use the following heatsinks:

Manufacturer

Model

Height

Thermal resistance at 200 LFM (~ 1 m / s)

Radian Heatsinks

HS2069DB

11.5 mm

1.8 K / W

Radian Heatsinks

HS2074DB

17.8 mm

1.2 K / W

Radian Heatsinks

HS2158DB

22.9 mm

1.1 K / W

There are other on-the-shelf heatsink on the market that are compatible with the board footprint. Such heatsink is typically used for cooling of Half-Brick DC-DC converters.

The above listed heatsinks provide better thermal characteristics but module height is increase beyond the limit allowed by the standard pitch of a PCI-104 stack. If another module needs to be plugged on top of a module equipped with such a heatsink, it is necessary to increase the module pitch using longer spacers and PCI-104 M/F connector.

The heatsink has to be fixed to the board using the 4 fixation holes. The usage of spring-loaded brass push pins is recommended.

A good thermal contact between the heatsink and the U1, U3, and U4 components is mandatory. The recommended method is to use thermal pads. Note that the thermal pads of U3 and U4 needs to be 0.8 mm thicker than for U1.

It is mandatory to establish airflow along the fins of the heatsink to remove the heat from the inter-module gap. This can be achieved by installing a fan in the chassis containing the PC/104 stack. However, fan-less design can be considered providing that the thermal resistance of the selected heatsink and the natural air convection is facilitated by orientating the board vertically.

The minimal air speed depends on the thermal resistance of the selected heatsink and the max ambient temperature requirement of the system. Before using Picolo U4 PCI-104, verify that all conditions listed in Board Thermal Requirements are met for the worst case environmental conditions.

A part of the available volume specified by the PCI-104 standard is left free in order to allow a thermal bridge to be inserted in the PCI-104 stack.