Thermal Straps and Busses

What are Thermal Straps and Thermal Busses?

Thermal straps and thermal busses are passive thermal management technologies used to conduct heat from sensitive components to another surface. Boyd encapsulates annealed pyrolytic graphite (APG) in another more durable material to leverage the high conductivity of graphite and strength or flexibility of the parent material in a single component.

Thermal Straps

Passive, flexible heat transport solutions that allow increased movement and a degree of freedom between your heat source and cooler dissipation regions.

Thermal Busses

High performance heat transport components with lightweight, high thermal conductivity graphite protected by higher strength, more durable encapsulating materials.

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Extended Thermal Performance for Orbital Satellites

Passive and reliable thermal straps will withstand launch and deployment to ensure long, reliable satellite lifetimes

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Enable Planetary Exploration with Reliable Rover Performance

Maintain electronic performance throughout the challenging conditions of launch, landing, and surveying for planetary rovers

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Cool Critical Avionics Electronics in Rugged Conduction Cooling

Maintain optimal electronics performance with high performance, reliable solutions

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Reliable Performance

Rely on ruggedized passive conduction thermal management to transport heat.

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Protect Power Converters, Inverters and Batteries

Manage the temperature of power management components and batteries for optimal performance and protect from heat damage

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Meet Cost Targets

Leverage a range of material options and configuration styles for a best-fit solution.

Polyimide encapsulated graphite Thermal Strap component
Encapsulated Graphite Thermal Bus Cross section

Robust, Reliable Conduction Cooling with Thermal Straps and Thermal Busses

Thermal straps and thermal busses rely on high conductivity materials to transport thermal energy away from heat sources to a safer region, even in the most challenging environments. Thermal busses offer conduction cooling in a rigid, high strength configuration whereas thermal straps enable consistent thermal performance in a flexible format. These conduction-based thermal management systems do not rely on any moving components and exhibit long and reliable lifetimes, even in microgravity conditions.

Aluminum and copper are widely used materials for thermal straps and thermal busses, but Boyd’s material expertise enable us to utilize other film materials such as graphite to enhance the performance of thermal straps and busses.

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k-Core®: Encapsulated Graphite

Boyd leverages its material science and manufacturing expertise to combine graphite into assemblies to create passive, lightweight, reliable, and highly thermally conductive solutions called k-Core®. Our proprietary process enables us to hermetically seal annealed pyrolytic graphite into an encapsulating metal, protecting the brittle graphite, but reducing the weight of the parent metal.

Thermal busses integrated with k-Core® to combine the lightweight benefits of graphite with the strength of copper or aluminum and offer increased thermal conductivity compared to the enveloping material.

By utilizing flexible materials like copper foil, aluminum foil, or polyimide film, to contain and support graphite sheets, thermal straps with k-Core® offer both performance and physical flexibility in your thermal management solution.

Thermal Straps


Maintain Flexibility and Movement Freedom

Take advantage of flexible heat transport in a reliable package


Push product reliability

With no active components like fans or blowers, thermal straps offer the most reliable flexible cooling solution

Thermal Straps

Thermal Straps, also called thermal links, provide a flexible, lightweight conduction path for moving heat to a cooling solution. This advanced solid conduction solution consists of highly conductive, flexible materials connected to headers to mount on separate surfaces which enable point-to-point heat transfer. Thermal Straps are a completely passive solution, eliminating maintenance costs, in a lightweight solution for semi-dynamic, weight sensitive applications. Boyd customizes Thermal Straps to meet conductance, stiffness or flexibility, and mass requirements.

Custom metal foil thermal strap assemblies are fabricated from a variety of metals including aluminum and copper. With special consolidation methods, Boyd can fabricate thermal straps with metal foils as thin as 0.0005 to 0.0100 inches to ensure high conductance and high flexibility.

Copper Thermal Strap

k-Core® Graphite-Encapsulated Thermal Straps

Boyd’s k-Core® (Encapsulated Graphite) Thermal Straps are highly conductive and formable for semi-dynamic heat transfer components. Encapsulated Graphite Thermal Straps are fabricated with Annealed Pyrolytic Graphite (APG) sheets, a highly thermally conductive material, contained in a stronger yet flexible film material, like polyimide, copper, or aluminum foil designs. k-Core® thermal straps perform effectively with aluminum encapsulant thicknesses of as little as 0.002 inches. Encapsulated Graphite Thermal Straps offer a solution that bends with the strength of the external material with a higher effective thermal conductivity and less weight than a completely metal construction. Since Encapsulated Graphite Thermal Straps are lighter in weight, smaller in size and offer better conduction than traditional thermal solutions, Boyd’s thermal straps increase design flexibility while maintaining performance. APG straps can achieve a thermal conductivity up to 1200 W/mK. Typically, Encapsulated Graphite Thermal Straps are 3 to 5 times more conductive per unit mass than aluminum foil designs and 9 to 15 times per unit mass of copper. k-Core® thermal straps also show increased conductivity at cryogenic temperatures and are proven effective in dissipating heat from high-powered electronic components without maintenance.

Thermal Busses 


Strength and Performance in one Component

Combine structural strength and thermal performance into a thermal bus for reduced product complexity



Replace heavier solid metal solutions with encapsulated graphite components

Thermal Bus Conduction Cooling

A thermal bus is a conductive, rigid component that serves as a pathway for passive heat transfer. Thermal busses are an ideal solution where active systems like air cooling or liquid cooling are not viable options. Without any moving components like fans or pumps, thermal busses transport heat reliably for extended lifetimes ensuring consistent thermal management for your application.

Encapsulated graphite cross section

k-Core® Encapsulated Graphite Thermal Busses

By encapsulating lightweight, but highly thermally conductive annealed pyrolytic graphite, Boyd’s k-Core® thermal busses can act as a drop-in replacement for solid metal solutions. Thermal busses leveraging APG cores help significantly reduce semiconductor temperatures with less weight, which is critical in demanding space, defense, and transportation applications.

Encapsulated graphite thermal busses can reach in-plane conductivities up to 1700 W/mK at isotropic room temperatures. The thermal coefficient of thermal expansion (CTE) of thermal busses can also be tailored to match semiconductor devices for reliable direct mounting.

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