Gap Fillers

What are thermal gap fillers?

Thermally conductive gap fillers are materials that are placed between electronic components and heat dissipating surfaces to fill air between the components, aiding heat transfer and keeping electronic systems cooler so that they can perform reliably over a product’s lifetime.

Design engineers use thermal gap fillers to fill larger heights and can often use one gap filler pad to cover multiple heat sources within an application. These materials are soft and pliant, designed to avoid putting too much pressure on sensitive components within an electronic system.

The Laird™ portfolio of thermal gap fillers includes both silicone and non-silicone-based offerings. Silicone-based thermal gap pads are chosen for their surface wetting abilities, high thermal stability and physical inertness. The silicone is normally used as the binder within a gap filler system. The silicone matrix is then filled with thermally conductive fillers - BN, ZnO, and alumina. These fillers make up the functional portion of the gap filler which gives it its thermal properties. Non-silicone-based thermal pads are often a requirement in sensitive applications with optical components and sensors, where outgassing and oil bleed can cause performance and reliability challenges. Laird’s line of non-silicone-based thermal gap fillers offer excellent deflection properties and low overall thermal resistance due to excellent surface wetting properties, all while minimizing contamination risks.

How do thermal gap fillers work?

Thermal gap fillers replace air gaps within electronic systems and fill in microscopic voids to better transfer heat from heat-generating components to heat-dissipating components. By removing the air – which has low thermal conductivity – with a material that offers high thermal conductivity, design engineers are able to improve heat dissipation within the system, keeping devices cooler and helping electronic systems stay within heat limits.

How are thermal gap fillers different from other thermal interface materials?

Thermal gap fillers differ from other thermal interface materials, such as thermal greases or phase change materials, in form factor and application method. The gap filler pads are pre-formed and die-cut to shape. They can be applied manually or automated with pick-and-place robotics. Compared to greases, gap fillers offer easier handling, better mechanical stability, and reduced mess. And unlike phase change materials, they don’t require a burn-in step. Gap fillers are ideally suited for applications that require rework, automation, or coverage of multiple heat sources with varying topographies.

In addition to thermal gap fillers, Laird also offers a comprehensive portfolio of liquid gap fillers, and specialty TIMs that offer both thermal management and other functionalities, such as heat spreading or electromagnetic interference absorption.

What are the key properties of thermally conductive gap fillers?

The optimal properties of thermal gap fillers include low total thermal resistance, high thermal conductivity, and low contact resistance (good surface wetting), all of which enable heat dissipation. Most Laird™ gap fillers are also electrically insulating, which helps prevent electrical shorts.

Thermally conductive gap filler materials should be easy to handle, soft and pliant to avoid damaging the sensitive componentry in electronic systems. Laird offers thermal gap fillers with low Shore hardness to help manufacturers achieve optimal surface contact under low pressure.

Low outgassing and bleed are also key properties for thermal gap fillers used in optical or sensitive electronic applications. Excessive outgassing can cause silicone to condense and build up on optical applications. Laird’s non-silicone-based thermal gap fillers reduce outgassing and bleed, improving long-term reliability of the system.

How can I determine the right thermal gap filler for my application?

There are a variety of considerations when it comes to choosing the right thermally conductive gap filler. Design engineers must evaluate:

• Thermal performance needs: Match the material’s thermal conductivity to the application’s heat load.
• Mechanical tolerances: Select the appropriate thickness and softness to accommodate gaps. Thermal gap fillers typically range from 0.25 mm to 5 mm in thickness. Laird offers high-performance gap fillers as thick as 0.1 mm.
• Electrical insulation requirements: Ensure the material meets dielectric standards.
• Environmental conditions: Consider vibration, temperature excursions, and vertical orientation.
• Automation compatibility: For high-volume production, dispensable or die-cut options may be preferred. Laird can produce its materials in custom die-cut shapes, tabbed liners, and kitting, enabling tailored solutions for complex assemblies.

What are common uses of thermally conductive gap fillers?

Gap fillers are used widely across industries to help dissipate heat in electronic devices. They’re especially valuable in applications requiring high reliability, low outgassing, and precise thermal management. They are also used in high-production products, where automated application is critical. Common applications include:

• Automotive: ADAS, lighting, infotainment, and powertrain systems.
• AI & Data Centers: GPUs, CPUs, and high-performance computing.
• Aerospace and Defense: Satellites and drones.
• Telecom: Wireless infrastructure, routers, and servers.
• Consumer Electronics: Smartphones, tablets, and gaming consoles.
• Industrial: Sensors and instrumentation, automation and motion control solutions.

What are the benefits of the portfolio of Laird™ thermal gap fillers?

Laird is a world leader in high-performance thermal interface materials. It has a comprehensive portfolio of thermally conductive gap fillers with solutions – including both silicone and non-silicone-based options and ultra-thin solutions – ranging from 1.2 W/m-K all the way up to 34 W/m-K thermal conductivity.

Using its deep materials science expertise, Laird develops gap filler solutions that boost product reliability and performance. Laird’s thermal gap fillers are designed to offer low outgassing and stable thermal performance over time.

Additionally, the Laird™ TIM Pick™ robotic motion control solution allows manufacturers to automate the application of die-cut thermal gap pads. The pick-and-place robotic arm places thermal gap pads onto an electronic component in a single process step, offering time and cost savings, and reducing scrap and rework. Learn more about Laird’s automated application offerings.

Review our thermal interface materials brochure to see the full range of TIM offerings.