Outdoor radio case study

The client is developing a new point to point radio product. This is an outdoor product that is mounted high on a pole.

Within the current design it houses a six layer PCB with all components on one side of the board. The components will face to the inside of the product, into a five sided plastic housing with the sixth side of the enclosure being the heat sink.

The back side of the board will interface with the heat sink using a compressible thermal pad.

Eaton’s objective is to verify the potential success of its thermal solution and to optimize the heat sink design.

Eaton was tasked with the following:

• To create a thermal CFD model of the existing product and implement PCB thermal properties
• Create package level model for all critical components, apply thermal resistances and power
• Compute internal and external thermal radiation paths. Simulate the baseline case and analyze temperature data, identify hot spots and explore opportunities for improvements
• Design heat sink for total power of 45W, to limit the internal enclosure temperature to 85°C with an external ambient of 55°C. (max 30°C rise)
• Optimize the heat sink design including: fin height, spacing, materials, base thickness, manufacturing process, size etc.

For the total of 45W power, at 55°C ambient, with the addition of copper layer and aluminum heat spreader, all components are under maximum junction temperature limit.

• The ambient temperature inside the enclosure is well below 85°C with the proposed heat sink design at 55°C ambient
• The shape of the enclosure is thermally close to the shape shown in drawings

Eaton was able to manufacture the proposed heat sink and helped launch a successful project to market.