Heatsinks vs. Heat Spreaders: Understanding the Difference - PHYTEC

A heatsink is a passive cooling device that dissipates heat away from a component by increasing the surface area exposed to the surrounding air. Heatsinks are typically made of thermally conductive materials like aluminum or copper and are used in conjunction with fans or other cooling systems for enhanced heat dissipation.

Key Features of Heatsinks:

• Designed with fins to maximize surface area and enhance heat transfer.
• Commonly used in applications with significant heat generation, such as embedded systems with heavy loaded CPUs or GPUs.
• Often paired with forced convection (e.g., fans) to increase airflow and improve thermal management.
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Pros of Heatsinks:

• Efficient Heat Dissipation: Excellent for transferring heat from a small, concentrated source to the surrounding environment due to fins extending the surface area.
• Wide Applicability: Suitable for high-power devices with significant heat generation.
• Superior Dissipation: Better at heat dissipation than a heat spreader due to more surface area creating air channels for better air flow performance.
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Cons of Heatsinks:

• Bulkiness: Can add significant size and weight to designs, making it less suitable for compact systems.
• Cost: High-performance materials like copper are expensive, and complex designs may increase manufacturing costs.
• Dependency on Airflow: Without adequate airflow, performance can be compromised, meaning your design would require air vents or proper environment testing to validate end system requirements.

A heat spreader is a device that distributes heat evenly across a larger surface area. It does not necessarily dissipate heat into the surrounding environment but rather prepares it for further cooling via heatsinks, fans, liquid cooling systems, metal housing contact, etc. Heat spreaders are typically flat on top and made of materials like copper or graphite. The heat spreader differs from the heatsink due to the lack of fins on top.

Key Features of Heat Spreaders:

• Focused on distributing heat across a uniform surface.
• Often used in conjunction with other cooling methods.
• Ideal for systems needing light thermal cooling.
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Pros of Heat Spreaders:

• Compact Form Factor: Ideal for space-constrained designs due to flat top.
• Uniform Heat Distribution: Prevents hotspots and enhances the effectiveness of subsequent cooling systems.
• Versatility: Works well with various cooling solutions, including liquid cooling and vapor chambers due to low and flat top profile.
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Cons of Heat Spreaders:

• Limited Heat Dissipation: Requires an additional mechanism to remove heat from the system.
• Material Constraints: High thermal conductivity materials can be costly.
• Dependency on Integration: Must be paired with other cooling elements for maximum effectiveness.

The choice between a heatsink and a heat spreader depends on your application:

• High Heat Load Applications (e.g., CPUs, power electronics): A heatsink is typically better for complex fully loaded CPU, GPU, DSP systems that tend to run fairly warm because the heatsink is actively dissipating heat into the environment.
• Compact Low Power Devices (e.g., smartphones, handhelds): A heat spreader is ideal for distributing heat evenly for systems that only need light thermal management.

At PHYTEC, we offer both heat spreaders and heatsinks, each designed with custom form fitting undersides to perfectly pair with our SOMs. Customers can choose to purchase a Thermal Management Evaluation Kit to determine the optimal setup for their application or directly purchase a heat spreader or heatsink from PHYTEC. Additionally, PHYTEC offers free design files for both systems, allowing customers to modify the designs to suit their specific housing and enabling cost-effective mass production with their preferred manufacturer.

What Makes PHYTEC’s Design Special?

Heatsink Design

Our heatsink design features the classic square fin structure on top for efficient heat dissipation, matched with a custom-molded underside to ensure seamless contact with the SOM. This ensures that all critical components, including known warm components (PMIC, SoC, DDR, PHY), are making perfect contact with the heatsink.

Key features include:

• Fan Support: Mounting holes for a 30x30mm fan to enhance cooling performance.
• Secure System Attachment: Includes legs to securely attach the heatsink to the SOMs mounting holes

The heatsink system included in PHYTEC’s Thermal Management Evaluation accessory kit can be implemented in a final application when paired with a fan.

Heat Spreader Design

Our heat spreader shares the same custom fit for optimal thermal contact but features a flat top surface instead of fins.

Key features include:

• Compact and Versatile: The flat surface allows easy integration with additional thermal solutions, such as attaching a larger heatsink or integrating with metal housing to transfer heat externally.
• Secure Mounting: Legs extending from the sides ensure reliable attachment to the SOM’s mounting holes.

Unlike the heatsink, the heat spreader cannot accommodate a fan and requires pairing with an external thermal solution for final applications.