Gap Pads: Thermal Gap Filler Pads, Thermally Conductive Pads, Thermal Interface Pads

Thermal Gap Filler PadsStockwell Elastomerics manufactures thermal gap filler pads for managing heat within electronic assemblies. Thermal gap filler pads are made from silicone polymer that is combined with a thermal medium (usually ceramic). The silicone and ceramic powders are mixed, cast and cured to a soft, conformal thermal pad material, in sheet form. Thin, precut thermal pads speed up the assembly process without the mess associated with thermal greases. Gap filler pads are inherently tacky which also aides in the assembly process. Thermal pads are also more stable than phase change products and have higher operating temperatures. Thermal gap filler pads range in thickness from .020″ to .250″ thick. Thermal performance ranges from 1.0 Watt/meter-Kelvin (W/m-K) to 5.0 W/m-K. Gap pads are either water jet cut into individual pads or flash cut and supplied on sheets of release liner. Samples are readily available for evaluation.

Thermally Conductive Gap Pad Demo


Thermal Gap Filler Pads

Thermal Gap Filler PadsThermal gap fillers or gap filler pad materials are very soft and conformal, with a dough-like consistency. These very soft thermal gap filler materials are designed to conform and fill in gaps between a heat source and heat sink. In some cases the gaps are a function of tolerance variation and in other cases there is intentional spacing. Thermal gap fillers are intended to be compressed – the pressure drives the material into the microscopic surface texture to maximize thermal conductivity.

For example, the surface of a heat generating microprocessor and a heat sink will never mate perfectly. The air gaps between the surfaces will inhibit good heat transfer. By bridging the voids with a thermally conductive gap filler, the heat generated by the microprocessor can be transferred better, through conduction, to the finned heat sink or chassis. Cooler electronics improve performance and reliability.

Stockwell Elastomerics custom cuts thermal gap filler pads to customer specifications. Using tool-less cutting, extra care is taken to optimize the yield and minimize waste, to help keep material costs down.

A gap filler is a thermally conductive pad with a dough-like consistency. These very soft gap fillers are designed to conform to and fill in between inconsistent surfaces as well as fill microscopic voids on contact surfaces. As an example, the surface of a heat generating microprocessor and a heat sink will never mate perfectly. The air gaps between the surfaces will prohibit good heat transfer. By filling these gaps with thermally conductive materials, the heat generated by the microprocessor can be properly managed, which in turn will aid in performance and reliability. Due to the cost of gap filler materials, Stockwell Elastomerics takes extra effort to optimize the yield and minimize waste.

Material Manufacturers for Thermal Pads

Stockwell Elastomerics uses three primary sources for the materials it uses for thermal pads. These material manufacturers and their products are:
Polymer Science P-THERM Gap Filler pad

  • Saint-Gobain ThermaCool® Gap Fillers
  • Polymer Science P-THERM® Gap Fillers
  • Bergquist Gap Pad®

All three manufacturers produce a family of thermal pad materials with various physical properties such as thickness, thermal conductivity, dielectric strength, availability of coated fabric surface on one side and hardness (Shore A). Stockwell Elastomerics’ Applications Engineers are adept at working with customers to select the best material for the specific application.

Saint-Gobain produces Thermacool Gap Fillers TC3006, highly compliant, 1.1 W/m-K), TC2006, compliant, 1.6 W/m-K) and high performance TC-3008, 3.0 W/m-K in 24″ x 24″ sheets to provide opportunities for best yield and production economies. Stockwell Elastomerics maintains a broad inventory of these materials in thicknesses ranging from .020” to .250” thick to support needs for fast-turn initial production.

Polymer Science offers a variety of thermally conductive gap filler pad materials designed to achieve desired heat management properties, including some semi-low compression set gap fillers and some ultra-soft gap fillers. Their P-THERM® silicone gap fillers include the PS-2505 (5.0 W/m-K) gap filler, PS-1543 (3.0 W/m-K), and PS-1541 (1.0 W/m-K) gap fillers, among others. Polymer Science’s gap fillers are manufactured in 18″ wide continuous length, which allows for many options in cutting techniques and good material yield. Polymer Science P-THERM® gap fillers are made in the USA, offering a robust supply chain.

Bergquist has the softest thermal material available with its Gap Pad V0 Ultra Soft and a broad range of materials.

Thermal Gap Filler Pads Replace Thermal Grease

Customers are now choosing very soft and thin gap filling pads to replace thermal greases and thermal pastes. Since thermal gap filler pads are made into sheets that Stockwell Elastomerics cuts to customer specification, these can be simple or complex geometries. Gap filler pads eliminate the need to work with messy thermal greases or cumbersome thermal paste. Gap filler pads are inherently tacky which allows them to be adhered in place for fast installation.

View more technical information about replacing messy thermal grease with thermal gap pads.

Thermal Gap Filler Pads Used with Thermal Heat Sinks

Gap fillers have gained popularity for improving the efficiency of finned heat sinks and chassis heat sinks. Thermal gap filler pads are available in various levels of softness and conductivity, with a wide range of thicknesses. Thermal heat sink pads increase the heat transfer efficiency by “wetting out” into the microscopic surfaces of a heat source and heat sink – this includes surface finish of machined, finned heat sinks. Voids and air pockets act as thermal insulation that inhibit heat transfer between the heat source and the sink. The soft silicone thermal pads also create a thermal bridge that allows conduction to occur between surfaces. Thermal gap filler pads are most commonly used in the electronics industry but can be used in many other applications. Typical heat sinks are aluminum finned plates, chassis or housings.

The thicker, softer gap filler can be laid directly over components or features on PCBs such as pins. Clamping the gap filler pad between the heat sink and board allows the thermal gap filler pad to conform around components and press against the board to create the intimate contact that optimizes heat sink efficiency.

Additional Thermal Management

Stockwell Elastomerics is a manufacturer of custom components to help manage and transfer heat. Thermal pads can be cut from a variety of thermal interface materials such as thermal tapes, thermal coated fabrics, thermally conductive silicone rubber, green heat conducting silicone sponge (R10404) or soft thermal gap fillers. Thermal interface materials offered by Stockwell Elastomerics are designed to help transfer heat; in some cases, such as with thermal gap fillers, they are used to remove heat to keep PCBs cool. In other applications such as heat presses, green conducting silicone rubber is used to transfer heat in the printing process. Stockwell Elastomerics also offers high temperature silicone foam for heat insulation.

Insulating Silicone Foam

In some instances, thermal management or heat management means insulating components from heat. Stockwell Elastomerics offers heat reflective foam, which is an insulating silicone foam with a foil facing to help reflect radiant heat (see product RF-120). In other cases, high temperature silicone foam and silicone sponge rubber materials are used. The cell structure of these expanded silicone materials gives them thermally insulating properties. Similar to home insulation, the small pockets of stagnant air in the cells inhibit heat transfer. UL 94V-0 rated, insulating, silicone foams such as open cell BF-1000 and closed cell HT-800 are commonly specified. Their thermal conductivities are 0.06 W/m-K and 0.07 W/m-K respectively and have an upper operating temperature of 392°F (200°C).

Contact Stockwell Elastomerics for Gap Pads, Thermal Gap Filler Pads, Thermal Conductive Pads, Thermal Interface Pads

Contact Us for further assistance with thermal gap pads, including thermal gap filler pads, thermally insulating foam, heat conductive pads, thermal conductive pads, and thermal interface pads.

ThermaCool® is a registered trademark of Saint-Gobain.
P-THERM® is a registered trademark of Polymer Science, Inc.
Gap Pad® is a registered trademark of Bergquist, a Henkel Corporation Company.