A Guide to Thermal Gap Fillers

Thermal gap fillers act as aids within a wide range of electronic components. The primary purpose of gap fillers is to replace insulative air spaces with these materials. The thermally conductive properties of these materials increase overall heat transfer for a specific system or an entire device.

With a vast range of gap fillers including silicone, non-silicone and 2-part dispensable gap fillers, selecting materials early in the planning phase can aid in heat dissipation, manufacturing, and even the design of electronics.

The Role of Thermal Gap Fillers in Electronics

Within the broader classification of thermal interface materials, gap fillers primarily function to cover large voids and improve contact with microscopic surface defects between interfacial surfaces. In today’s more complex and intricate designs, gap fillers are far more versatile at transferring heat than ever before. At Polymer Science, our team designs silicone, non-silicone and two-part dispensable gap fillers capable of spanning multiple components, normalizing uneven surfaces, and even adding protection to final electronic devices.

Electric vehicles are a key example of the importance of choosing the optimal thermal interface materials. Specifically, the role of gap fillers within electronics can improve the performance, function, and durability of electronic devices. Not only do gap fillers minimize thermal resistance, but within compact and energy-dense electronics, both gap fillers and 2-part dispensables reduce stress and deliver additional protection. A few examples include dampening vibration, minimizing pressure within the system, and sealing against moisture and chemicals.

From roadways and air travel to consumer devices like smartphones, thermal interface materials play a small, but vital role in transforming the world. Polymer Science is a leading designer and manufacturer of silicone gap fillers. Available in soft, ultrasoft, hypersoft, and 2-part dispensables, P-THERM® silicone-based gap fillers offer properties such as mitigating surface imperfections, high thermal stability, and physical inertness. Our team works with businesses in all stages of the design and manufacturing process.

In this article, Polymer Science explores both the general benefits and the role of gap fillers in specific applications.

General Benefits of Thermal Gap Fillers

These benefits span various manufacturing processes and operational requirements of thermal gap fillers within modern electronics. Here’s a closer look at their general advantages.

Versatility for Different Manufacturing Processes

Manufacturers often face the initial decision between gap filler pads or 2-part dispensable thermal gap fillers, each with unique attributes catering to different production needs. Two-component systems, requiring a mix before application, offer a tailored approach to thermal conductivity and cure time, allowing for a custom fit to specific operational demands. Gap filler pads reduce initial setup costs and are ready to use within any manufacturing process.

In short, thermally conductive gap filler materials can be suited to the specific goals of manufacturers.

Low Outgas Options

In applications where purity is non-negotiable, such as with sensitive electronics and aerospace applications, low outgas thermal gap fillers are critical. These specialized materials are engineered to minimize the release of volatile organic compounds (VOCs) during use, which could otherwise compromise component reliability or contaminate sensitive environments. This is particularly vital in vacuum or aerospace applications where outgassing can lead to system failures.

Curing Options

The curing process solidifies the gap filler’s position and properties, and having options to cure at room temperature or with added heat broadens the application spectrum. Room temperature curing is ideal for scenarios where additional heat may damage sensitive components or is simply not feasible.

P-THERM® 2-part dispensables curing can be tuned for room temperature or accelerated by heat for environments where time constraints are a primary concern. Ultimately, dispensable gap filler materials can increase production efficiency and reduce cost because they can be selectively applied at thin bond lines and to areas where heat transfer is required.

Electrical Insulation

One standout feature of thermal gap fillers is their electrical insulating properties. This characteristic is vital in preventing electrical shorts between closely packed components, which is increasingly important as electronic devices become more compact and dense. By maintaining component integrity, thermal gap fillers ensure devices operate safely and effectively over their intended lifespan.

Protection Benefits

Beyond thermal management, gap fillers serve as a protective layer that absorbs shock and dampens vibration, which can be detrimental to the delicate internal components of electronic devices. By providing a buffer, thermal gap filler pads minimize stress and pressure on components.

2-part dispensables can coat components decreasing thermal resistance and safeguarding against the wear and tear of regular use, rigors of transportation, and even sudden shocks to the device.

Summary of General Benefits of Thermally Conductive Gap Fillers

In essence, thermal gap fillers are a key component in the design and assembly of electronic devices. These are just a few of the general benefits the optimal thermal gap filler provides both for manufacturing flexibility and protection for sensitive components.

Specific Applications of Thermal Gap Fillers

Beyond general benefits, specific electronic system applications highlight the importance of gap fillers in the present and future of manufacturing.

In Battery Packs

The advanced battery industry is rapidly growing in electric vehicles and hybrid technology in consumer and commercial transportation. Consumer devices like smartphones, tablets, and computers are now essential to everyday life around the globe.

Polymer Science works with many other industries, including marine, medical, military, and aerospace, where innovations and breakthroughs in battery packs open new possibilities.

Thermal gap fillers are used to enhance the connection between individual cells and cooling plates in battery packs. Efficient heat transfer away from the cells is vital for maintaining battery life, performance, and safety.

As battery cells are assembled into modules and modules into packs, thermal management becomes increasingly complex. Thermal gap fillers bridge the gaps within these assemblies, ensuring that heat generated by the cells is effectively dissipated. This not only prevents hot spots, but it also contributes to the overall thermal stability of the battery pack.

In EV Charging Systems

Thermal gap fillers find a significant role in the inverters and converters of EV charging systems. The conversion of electrical energy generates substantial amounts of heat. Gap fillers mitigate heat improving the efficiency of charging plugin electric vehicles and maintaining the integrity of the charging unit.

In Consumer Electronics

Thermal gap fillers serve a dual purpose in consumer electronics: protecting components including circuit boards from thermal stress and absorbing shocks from daily use. By doing so, they contribute to the durability and continued functionality of devices such as smartphones, laptops, and tablets.

In the case of 2-part dispensable gap fillers, an entire system can be coated encasing sensitive components against thermal and mechanical stresses. Without the need for additional heating equipment in the manufacturing process, the assembly process is simplified and production cycles are faster.

In Infotainment Devices

Infotainment systems in vehicles combine complex electronics with user interfaces that must operate flawlessly. Thermal gap fillers dampen vibrations that regularly occur in moving vehicles and provide electrical insulation, protecting sensitive components from interference. This ensures that the performance of infotainment systems remains consistent and reliable, enhancing the user experience.


Each of these applications demonstrates how thermal gap fillers are not just a supplementary component, but a necessity for modern electronic design and functionality. Their ability to manage heat, while providing mechanical protection, makes them a key element in the development and sustained performance of electronic systems.

How Polymer Science Helps Manufacturers

Clearly, thermal gap fillers and 2-part dispensables do more than simply fill air gaps. At Polymer Science, decades of experience working across many industries affords our partners expertise and a proven process for selecting, customizing, and supplying the right solution in thermal interface materials. Contact our team to learn more about how we power better performance, smart design, and the most efficient manufacturing process.