When to Use Heat Pipe Heat Sinks
When designing a thermal solution, engineers must determine whether a conventional heat sink is sufficient or if advanced heat transfer mechanisms are required. Heat pipe heat sinks (2-phase heat sinks) should be considered when heat needs to be transported over a distance, spread efficiently, or managed in compact, weight-sensitive applications. Below is a quick reference guide for when to incorporate a heat pipe heat sink in your design.
Heat pipes move heat efficiently – When heat must be transferred over a distance – typically greater than 25-50mm, heat pipe heat sinks provide a significant advantage. The effective thermal conductivity of two-phase devices increases with the distance heat is transported, far surpassing that of solid aluminum or copper. Additionally, heat pipes can be bent to navigate around PCB keep-out zones, ensuring efficient heat transfer from the source to the fin stack without compromising spatial constraints.
Vapor chambers spread heat uniformly – While embedded heat pipes do a very good job of spreading heat across the base of the heat sink, nothing beats a vapor chamber for reducing thermal resistance and delta-T. This is especially important for high heat flux integrated circuits (ICs) and components with localized hotspots as high power densities usually require exceptional heat transfer in order to maintain thermal budgets within acceptable limits. The example below compares aluminum and vapor chamber base designs.
2-phase devices can reduce delta-T though the fin stack – In applications where maximum fan speed reduction or enhanced thermal performance is required, additional fin area becomes necessary. Increasing the length, width, or height of fins often necessitates the use of 2-phase devices. When heat sink length or width is increased, vapor chambers allow better heat distribution across the surface, If fin height is increased, it may be necessary to run heat pipes though the center of the fin stack as seen below. This most easily accomplished when zipper fins (fin packs) are used.
Heat Pipes Allow Both Fin Base and Mid-Fin Contact to Heat Source
Weight and stack height can be reduced with 2-phase designs. Lightweight designs with minimal vertical stack height are essential in weight-sensitive and space-constrained applications. A heat pipe heat sink utilizing a vapor chamber base can maintain the same weight as an aluminum-based design while achieving half the thermal resistance and reducing thickness by approximately 2mm, in this application. This allows for compact and efficient thermal solutions while improving performance.
Vapor chamber and heat pipe heat sinks offers versatile and high-performance thermal management solutions by efficiently transporting and spreading heat, while enabling lightweight, low-profile designs. These advantages make them an ideal choice for demanding applications where traditional heat sinks fall short. By leveraging two-phase cooling technology, heat pipe heat sinks provide superior thermal performance while meeting system constraints.
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