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By Mark Swanson on  7/12/2018

Gap Fillers for Heat Management in Electronic Assemblies

Gap Fillers for Heat Management in Electronic Assemblies

Gap fillers are thermal interface materials (TIMs) that move heat away from sensitive components in electronic assemblies. They’re usually made of silicone rubber and contain a ceramic filler. Like other types of TIMs, gap fillers are designed to fill the tiny air gaps between a heat source and a heat sink. Most gap fillers are inherently tacky and have a doughy consistency, but engineers can also choose materials with a non-tack surface for manual assembly.

Gap fillers provide greater stability than phase change materials (PCMs) that melt or solidify at certain temperatures. They’re also easier to install than thermal greases or pastes. For fast, precise, cost-effective fabrication, gap pads are die cut from sheet materials into specially-shaped parts called pads. These die cut products are available with release liners and pressure-sensitive adhesives (PSAs). For heat management in electronic assemblies, gap fillers with specific features may be required.      

Thermally-Conductive Silicone Interface Pads

Thermally-conductive silicone interface pads are gap fillers that help speed device assembly and extend component life. They have good thermal stability, excellent softness, and support ease of handling and rework. Examples include 3M™ 5591, 5583S, 5584, 5595, 5516, 5516S, 5519, 5519S, 5514, 5515, and 5515S materials. These thermally-conductive silicone interface pads come in different thicknesses and colors. Some have UL 94 V0 flame ratings or meet RoHS requirements.

Fiberglass-Reinforced Gap Fillers

Gap fillers with fiberglass reinforcements provide added tear strength. They support product rework and are a good choice for applications with low-to-moderate clamping force. Often, fiberglass-reinforced gap fillers are used in telecommunications equipment, consumer and automotive electronics, and LED lighting. Examples of these materials include Parker Chomerics THERM-A-GAP™ 976, A174, T274, and G174. Like other types of gap fillers, fiberglass-reinforced materials support precision die cutting.

EMI Shielding and Thermal Management

Some thermal interface pads combine heat management with resistance to electromagnetic interference (EMI). For example, Parker Chomerics THERM-A-GAP™ 569, 570, 579, and 580 materials are available on aluminum foil for EMI shielding. They are highly conformable and can be used in applications where other gap filling pads place excessive amounts of stress on component solder joints and leads, which can cause damage to printed circuit board (PCBs).

Find Die Cut Gap Filers

JBC Technologies is a 3M™ preferred converter and precision die cutter. We can also source, convert, and die cut gap fillers from other parts of our strategic supply chain. In addition, JBC provides help with material selection. To learn more about gap fillers, contact the JBC Sales Team.


3M™ is a trademark of the 3M Company.

THERM-A-GAP™ is a trademark of Parker Chomerics

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