Thermal Management Solutions
Sensitive components and systems often require strict temperature maintenance to keep them operating efficiently and safely. Thermal management is the practice of using specialized media to control the distribution of heat throughout a system. It involves a combination of careful hardware and software design to effectively manage the thermodynamic properties of a system using techniques like heat transfer, convection, radiation, and conduction. There are a variety of use cases for thermal management ranging from electronics and aerospace to automotive and manufacturing.
Electronic components are prime candidates for thermal management since they quickly gather and produce heat. When they overheat, they can experience processing issues and internal damage that affect their reliability, integrity, and longevity. Overcoming this issue has become of prime importance to the electronics sector as it continues to strive for more powerful components placed in smaller spaces; qualities which combined increase the risk of overheating. In addition to mitigating this problem in normal and harsh operating conditions, strategic thermal management can also reduce vibrations and overall energy usage and costs by recovering wasted energy and leveraging it as a secondary power source.
Types of Thermal Management Materials
Thermal interface materials (TIM), or heat-dissipating materials, are available in a wide range of formats, including adhesives, gels, grease, pads, paste, putty, phase change compounds, and tape. Although these options are often considered less important and effective than thermal management components, such as heatsinks and fans, they offer their own unique benefits. In fact, to ensure optimal system reliability and avoid issues down the line, best practice suggests including both thermal interface materials and large thermal components in electronics systems design.
Some of the materials commonly used in thermal management products include:
Phase Change Materials (PCMs)
Phase change materials (PCMs) are materials that change their physical properties when introduced to heat or energy. When phase change materials hit a specific temperature (referred to as the PCM melting point), they change from a solid into a liquid. In this liquid state, the PCM absorbs heat, reducing the overall thermal temperature of the component. When the temperature lowers to beyond the designated freezing point, the PCM changes back into a solid and releases the heat back into the system.
Some common PCMs are:
- Paraffin wax
- Hydrated salts
- Non-paraffin organics
PCMs are used in a variety of products to reduce energy waste and improve thermal properties in applications involving textiles, electronics, storage, construction, and more.
Thermally Conductive Insulators
Typically used in place of grease or gels, thermally conductive insulators provide both thermal transfer and electric insulation properties. A core measurement used in the creation of thermally conductive insulators is dielectric breakdown voltage—commonly referred to as the “breakdown voltage—which is the point at which an electric field can render the insulator ineffective. Thicker thermally conductive insulators typically have higher dielectric breakdown voltages, but they also require more space.
Thermally conductive insulators are made out of a robust and durable carrier material such as silicone rubber, epoxy filled with boron nitride, or fiberglass combined with a filler material such as mica. Similar to PCMs, thermally conductive insulators have many use cases. Most often, people use these materials between heat sinks and other electrical components, such as CPUs and processors.
Thermally and Electrically Conductive Materials
As the name suggests, thermally and electrically conductive materials demonstrate both thermal and electrical conductivity. The base of these materials typically consists of graphite, silver, or diamond coated in electrically conductive pastes or filled with electrically conductive filler materials.
There are a variety of use cases for thermally and electrically conductive material. From electronic components with high electric power such as circuit breakers to power switches, they find application in most situations where electrical conductivity is critical.
Thermally Conductive Tapes
Thermally conductive tapes are used to manage the transfer of heat between electrical components. They are sticky and filled with ceramic fillers that have the thermal properties necessary to form a thermal interface between the component and the heat sink. In addition to having good thermal conductivity, they adhere to components and are somewhat electrically conductive.
These qualities are ideal for applications where a strong bond is needed and adhering one material to another is ideal.
Thermal greases are thermally conductive greases with medium viscosity. They are available in various combinations of zinc oxide, silicon, and other materials (e.g., aluminum) that offer different thermal and electric conductivities, viscosity, and fluidity. The overall conductivity of the grease depends on the substrates, the bond line thickness (lower BLT is typically preferred), and the properties of the grease.
There is a wide range of applications for thermal greases, including ones where a strong adhesive (e.g., thermal pads) is not necessary.
While thermal gels share many characteristics with thermal greases—such as the use of base materials like aluminum nitride, zinc oxide, aluminum oxide, boron, and silicon—they form stronger, more permanent bonds. They are applied as a fluid and cure into a harder, more long-lasting form.
Thermal gels are best used for low BLT bonds that require more permanent bonding.
Thermal putties are highly viscous thermal interface materials applied like thermal grease but capable of forming stronger bonds and minimizing vibrations between parts. They are used in a variety of industries and are the perfect solution for filling in large gaps near a heat sink or creating strong bonds between parts with a tendency to vibrate.
Primary Factors to Consider When Choosing Thermally Conductive Materials
While every material mentioned above demonstrates thermal conductivity, each has different properties that make it suitable for specific applications. Here are some primary factors to consider when choosing a thermal interface material.
- Thermal conductivity. The thermal conductivity of a material is its ability to transfer heat along the temperature gradient. While this quality is important, it shouldn’t be the deciding factor. Since thermal conductivity is largely determined by the makeup of the material (e.g., the substrate mixture, etc.), all of the above materials can vary in thermal conductivity by brand and composition.
- Hardness. The hardness of a TIM is often measured using Shore durometer and ASTM D2240-00. The harder the material, the better it fills in gaps and prevents vibrations. The softer the material, the better suited it is for use on components that are already secured and don’t require micro-gap fills. Any gaps in the material can impact its thermal properties.
- Thermal resistance. This factor is the measure of the temperature difference between two materials as it relates to heat flow. The thermal resistance is based on the basic formula L/KA, with the thickness of the material (L), the thermal conductivity (K), and the area of heat transfer (A). The higher the thermal resistance, the lower the heat transfer—i.e., the more heat the system retains. In general, the lower the thermal resistance, the better its thermal properties.
- Operating temperature range. This factor is the range of temperature in which electronic components function. The chosen TIM should work within these ranges. For PCMs, the melting point should be below the maximum operating temperature, since the heat transfer works when the material transitions from a solid into a liquid.
- Viscosity and fluidity. In general, the TIM should fit within the viscosity and fluidity range needed for the application. For example, if a person is trying to apply thermal grease to a vertical component, the viscosity should be high enough that it doesn’t drip or drain out of the system. It’s also essential to consider fluidity. Some applications need thinner, more fluid thermal materials to perform specific functions.
- Pressure. Some thermal materials are conductive under high pressures, while others are conductive over low pressures.
Secondary Factors to Consider When Choosing Thermally Conductive Materials
Beyond the considerations mentioned above, there are other factors to keep in mind when choosing a thermally conductive material, such as:
- Surface finish. Since air is a poor heat thermal conductor, having any gaps between surfaces lowers a system’s heat transfer capabilities. Surface finish refers to the roughness and imperfections in a surface. A smoother surface finish leaves less air between materials and improves heat transfer.
- Ease of application. A thermal material should be easy to apply, especially for high-volume production applications.
Applications of Thermally Conductive Materials
One of the most challenging parts of electronic equipment design and management is figuring out how to handle temperature issues. Electronics with high-speed processors generate significant amounts of heat. When that heats increases the temperature, it can decrease the longevity of the device, impact performance, and cause premature failure that renders the device non-functional well before expected.
This thermal issue is compounded in today’s electronics. For example:
- High performing CPUs are a necessity for businesses developing cutting-edge, emerging technologies. However, these CPUs generate more heat due to their greater operating capacities and smaller footprints. Thermal management can control heat levels to ensure that temperature stays within the acceptable operating temperature range.
- Microprocessors are also challenging due to their higher density and compact size, which increase the risk of hotspot creation. Thermal management of these electronic components requires careful attention toward the thermal interface materials and management techniques utilized and the microarchitecture.
Thermal management is useful for a wide range of electronics—not just in microprocessors and high-speed processors. From smartphones to speakers to aircraft components, it helps increase the longevity and performance of virtually any electronic system across a diverse set of industries, including in the following:
- Consumer products
Types of Thermal Management Products
At Robert McKeown, we supply a variety of thermal management products, including:
Gap Filling Thermal Interface Sheets and Pads
Our THERM-A-GAP™ gap-filler sheets and pads demonstrate excellent thermal and conformability properties at low clamping forces. They have UL recognized V-0 flammability and are compliant with RoHS standards. Available in both aluminum foil (A) or clean break glass (G), these products can easily fit into most electronic component spaces and protrusions.
Thin Interface Thermal Insulators
Our CHO-THERM® commercial-grade thermal insulator pads are an economical thermal management solution that offers good thermal, electrical, and mechanical properties. They also feature UL recognized V-0 flammability rating and RoHS compliance and are available die-cut on continuous rolls for easy peel and stick. We also offer a high-power variation that has enhanced thermal, electrical, and mechanical properties and resistance to punctures.
The CHO-THERM® line has a proven track record spanning multiple decades in consumer electronics, aerospace, military, and industrial industries.
Double Coated Attachment Tapes
Our line of THERMATTACH® double-coated attachment tapes come in four variations:
- THERMATTACH® T418. This latest product offering is the culmination of years spent combining research and industry insights to develop a best-of-breed thermal attachment tape using world-class materials. It demonstrates exceptional thermal and mechanical capabilities.
- THERMATTACH® T410 and T410R. T410 and T410R (a RoHS compliant variation) consist of a pressure-sensitive acrylic adhesive with high bond strength embedded with aluminum oxide that is coated onto a 0.002-inch aluminum foil carrier. For adhesion, the other side of the tape has a pressure-sensitive silicone adhesive that can stick to silicon-contaminated plastics and other low energy surfaces.
- THERMATTACH® T411. The T411 has an expanded aluminum mesh carrier layer that allows it to conform to curved surfaces for a strong adhesive bond. It is suitable for attaching heat sinks to other components.
- THERMATTACH® T413 and T414. T413 and T414 are ionically clean tapes with a fiberglass carrier. Using an electrically insulating film carrier, they provide the ideal interface between components. They also exhibit good thermal conductivity, exceptional bonding properties, and a unique textured pattern that allows for a reduction in air pockets.
Phase Change Thermal Interface Materials
HERMFLOW™ - our patented phase change material - is ideal for dissipating heat between components and heat sinks. Due to its phase change nature, it starts as a solid and conforms to heat sinks using minimal clamping once it reaches the melting point. This quality makes THERMFLOW™ a unique solution that’s easy to handle like a thermal pad but provides the filling function and performance of thermal grease.
As the electronics industry continues to increase production and generate novel solutions, the thermal interface materials sector needs to be ready to adjust to unique product and thermal specifications. At Robert McKeown, we’re prepared to develop custom thermal interface parts that meet your exact specifications. Whether you need thermal interface molded or adhesive parts, we can design and deliver a solution tailored to your needs.
A Leading Provider of Thermal Management Products
As overheating can cause significant damage to electronic components and systems, thermal management is key to ensuring their reliability and longevity. Offering a broad selection of thermal interface materials, Robert McKeown can help you find a quality thermal management solution for your electronics. For additional information about our thermal management product offerings, contact us or request a quote today.