What Are Thermal Conductive Insulation Materials?

When choosing a thermal management material, at times balancing between efficient heat dissipation and electrical insulation can be an overwhelming task. It is even a dilemma if you don’t know the right material to use.

In this article, we will explore some fundamental facts about thermal conductive insulation materials.

Key Basics of Thermally Conductive Insulation Materials

These are specialized materials that are effective in the heat transfer while preventing the flow of electrical current. In most cases, these materials fill the gap between the heat-generating components and the cooling components, which dissipate heat.

But even as we explore, thermal conductive insulation materials, some of the fundamental aspects to consider are effective heat dissipation and electrical insulation.

· Effective Heat Dissipation

These materials provide effective channels for heat transfer heat between hot components, such as processors or power transistors, and heat sinks. They seal thermal resistance between surfaces that otherwise would trap heat and cause overheating due to air spaces in the microscopes.

· Electrical Insulation

Electrical insulation eliminates short circuits and electrical failures, but at the same time, enables the flow of heat between material structures. These materials consist of non-conductive substances such as ceramics, polymers, or specially treated rubber that do not permit the flow of electrons completely.

Dielectric strength is measured by kilovolt/mm. Remember, this is a measure of the voltage that the material can handle before collapsing.

Types of Materials used in Thermal Conductive Insulation

By Temperature Range

· Low Temperature

One of the most popular material for this application is polyurethane, which works at a temperature of -200 °C to 100 °C. It is applied extensively in cryogenic storage, refrigeration systems, and cold rooms. This is because it has low thermal conductivity but great moisture resistance.

Alternatively, you may also choose expanded polystyrene. For this material, it is suitable for temperatures ranging from -50 °C to 75 °C. You can use it in building insulation and chilled water systems due to its lighter construction structure and cost efficiency.

· Medium Temperature

In medium temperature applications, choose mineral wool, with the ability to withstand a temperature of up to 650 °C. You will find this material in industrial piping, boilers, and HVAC ducts because it is resistant to fire and has zero variance during thermal output.

Another material is calcium silicate, which can withstand temperatures ranging from 100 °C to 650 °C. It offers a maximum compressive strength and resistance to moisture in the power plant and refinery piping systems.

· Higher Temperatures

For higher temperatures, ceramic fiber offers the perfect solution. This material works well in temperatures ranging from 1000 °C to 1600 °C. Their low density and excellent thermal shock resistance make them perfect for furnaces, kilns, and heat-treatment equipment.

Alternatively, aerogel is also a suitable choice here since it has a maximum operating temperature of 1200 °C (special grades). This material provides thermal conductivity, which is extremely low in thermal management, industrial, and aerospace applications at high temperatures.

By Material Type

· Ceramics

Ceramic materials are highly thermal conductive with greater electrical insulation and high temperature stability in applications with high needs. The most common ceramics available in thermal management are aluminum oxide, aluminum nitride, and beryllium oxide.

· Polyimide Films

Thin polyimide films offer flexible thermal interfaces with excellent electrical insulation, good thermal conductivity, and chemical resistance. You should choose polyimide materials in a situation where you require conformability of interfaces in narrow areas where hard materials do not fit well.

· Fiberglass

Fiberglass products use thermal conductive fills in a glass fiber structure to provide poly-purpose, economical thermal insulation products. When you choose thermal management materials made of fiberglass, you obtain mechanical strength, electrical insulation, and moderate thermal conductivity.

· Thermal Silicone Rubber

High flexibility, coupled with good thermal conductivity, is achieved by adding ceramic or metallic filler particles into thermoplastic silicone rubber.

Silicone rubber pads have an advantage in assembly activities; they are easily installed and have the added advantage of closing gaps. These materials conform to the surface irregularities, offset the height variations of the components, and ensure thermal contact, vibrations, and thermal cycling.

How Thermal Conductive Insulation Materials Work

The working principle of thermal conducting insulation materials involve the formation of unbroken channels for phonons and heat, in addition to preventing the flow of electrons.

To achieve efficient thermal transfer, filler particles, such as ceramics, metal oxides, or carbon, form overlapping conductive networks in the material.

At the same time, the polymer base or binder then offers electrical insulation and mechanical characteristics while allowing the filler particles to conduct heat.

Thereafter, the contacts between the material and the heat-generating components on the surface clear out air gaps that would otherwise form barriers to thermal resistance.

Application of Thermal Conductive Insulation Materials

· Aerospace

Aerospace uses necessitate materials that can be reliably utilized in extreme variations in temperature, vibration, and changes in altitude during working ranges.

They are thermal conductive insulators used in avionics cooling systems, satellite electronics, and engine control systems where there is no room for failure.

· Automotive

With the continued adoption of electric vehicles and advanced electronics in the current vehicle design, automotive applications are increasingly relying on thermal conductive insulation.

These materials are durable, resistant to vibration, moisture, and thermal cycling, and are used in battery thermal management devices, power inverters, LED lights, and engine control devices in vehicles.

· Power Electronics

Power electronics are also sources of high heat, and to ensure reliability and performance under high heat conditions, efficient thermal management is required.

Thermal conductive insulators are installed between the heat sinks, power semiconductors, IGBTs, MOSFETs, and thermal sinks in order to remove heat efficiently and minimize electrical shorts.

· Consumer Electronics

Thermal conductive materials are designed to handle the heat produced by the processors, graphics cards, and power supplies in smartphones and laptops by electronics producers.

Thin, comfortable, affordable materials with a normal temperature range that can fit the tight space constraints of modern consumer device designs.

· Telecommunication Systems

You must invest in thermal conductive insulation materials to constantly operate and produce a lot of heat as a result of signal processing, power amplification, and data transmission equipment components.

The materials should be durable and able to operate in both climate-controlled buildings and natural settings with minimal servicing to ensure no degradation of signals or malfunctioning of equipment.

How to Choose the Right Material

1. Cost vs. Performance

First, define your minimum performance requirements by selecting the most cost-effective material that complies with these requirements.

Analyze the total cost of ownership with regard to installation labor, reliability, and maintenance, and not just the initial cost of purchasing the material.

2. Thickness

Thickness relates directly to thermal resistance. During assembly, you need to evaluate between thermal performance and mechanical demands, such as gap filling, vibration isolation, and handling durability.

The thicker materials allow high component height tolerance and component manufacturing allowances but increase thermal resistance to the system.

· Safety

The safety considerations include flammability rating, toxicity, outgassing, and adherence to regulations specific to the industry in which you will apply. Materials should be checked against applicable safety standards, such as UL94 flammability standards for automotive safety.

Electrical safety require a sufficient dielectric strength to avoid voltage breakdown, which may lead to fire, shocks, or destruction of equipment.

· Thermal Conductivity

The thermal conductivity materials you use should be able to reach your target junction or component temperature when operating with maximum heat loads.

Those materials with elevated thermal conductivity permit either thinner interfaces or higher heat fluxes, but generally are more expensive than lower-performance materials.

Ensure that thermal conductivity, as specified by the manufacturer, is tested in the same manner as the system; this is because different methods tend to give different results.

· Compressibility

You require compressible material in case component height differences or surface roughness are present, which would otherwise be air gaps with hard materials.

During assembly, the compression force should be in line with your capabilities and the equipment used, and should not harm delicate components or substrates.

· Coefficient of Thermal Expansion

Coefficient of thermal expansion (CTE) is a ratio of the change in the dimensions of a material with temperature, and it determines its long-term reliability and performance.

To reduce stresses caused by differentials in the expansion of the material in the thermal cycling process of operation, you should align the material’s CTE with the other components.

Large CTE mismatches generate shear forces at the interfaces, and this, after repeated cycles, could lead to delamination, cracking, or bond failures.

FAQs

What is the difference between thermal insulation and thermally conductive materials?

Thermal insulating materials work by reducing heat transfer to maintain temperature differences, whereas thermally conducting materials enhance maximum heat transfer to even out temperature.

What is the difference between thermal conductivity and thermal resistivity?

Thermal conductivity is a measure of the ease with which heat moves in a material in watts per meter-kelvin, and the higher the level, the better the heat transfer of the material.

The thermal resistivity, on the other hand, is the opposite of thermal conductivity, which is a measure of the resistance of a substance to heat flow in meters-kelvins per watt.

Can material be thermally conductive and electrically insulating?

Yes, numerous materials are now being engineered to have both high thermal conductivity and extraordinarily electrical insulating properties by selection of base material and filler conductor.

Can thermal pads replace thermal paste?

Certainly, in most applications, you can use thermal pads instead of thermal paste, and they are easier to install, handle, and more predictable than pastes.

Do thermal interface materials “dry out” over time?

Yes, unlike thermal pads, which only degrade over time, liquid components in paste evaporate due to oxidation and high heat, leading to dry out.

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Every material is tested to ensure they have the right thermal impedance and conductivity. Besides, we also examine the dielectric strength and volume resistivity. Tell us more about your project needs, and Gallop Innotek engineers will recommend the right material for your project – Explore our TIM and EMI materials catalogue.