Thermally Conductive Insulators

Thermally Conductive Insulators

In the context of advanced 3D integrated circuit technologies, The Power of Thermally Conductive Insulators management is an important design challenge. Because of the high thermal contact between different elements, insulators are required to keep the heat generated within a package from transferring to the surroundings and thereby affecting chip performance. In addition, insulators must withstand rigorous mechanical stresses that can be placed on components during assembly and re-entry into the atmosphere from space (as demonstrated by the failure of insulating tiles on the Space Shuttle Columbia).

Thermal insulation is a material that reduces heat transfer by obstructing convection, radiation or conduction paths between objects at different temperatures. Many natural, biological insulators such as fur or feathers function by trapping air in pockets or pores that obstruct the flow of thermal energy, and some specialized synthetic insulators like expanded and extruded polystyrene foam (commonly known as styrofoam) and silica aerogel are similar. In general, a material's ability to inhibit the flow of thermal energy depends on its mass, thickness and porosity.

Graphene-based materials have unique properties that make them an excellent choice for insulators, despite their relatively low thermal conductivity. Graphene can be combined with conventional materials to increase the insulating properties, and it can even serve as a structural component in some cases. For example, carbon-ceramic composites retain both high electrical conductivity and impressive insulating qualities – properties that are normally impossible to achieve together.

For insulators to be effective, they must also have low specific heat (a measure of the amount of thermal energy required to raise the temperature of a volume of the material by 1°C), and be resistant to chemical damage and moisture. They must be capable of dissipating the heat they absorb quickly to minimize the risk of overheating and damage.

The thermal conductivity of polymer adhesives is typically quite low, but by adding metal, silver, gold, nickel, or inorganic fillers with high thermal conductivity, the conductivity can be increased 10-fold or more. However, metallic fillers can render adhesives electrically conductive and are not suitable in applications that require electrical insulation or isolation.

An alternative to metal-based materials, carbon-based fillers are highly conductive but can be made very thin, so they do not interfere with the adhesion of adjacent layers in an assembly. Moreover, their high atomic density allows them to dissipate the heat they absorb extremely quickly, minimizing damage and thermal stress.

For complex multi-layer circuit boards and systems, the insulating properties of traditional polymers can be improved by mixing inorganic fillers with high conductivity into the polymer matrix to fabricate a composite. This approach is often more cost-effective than purchasing a pre-fabricated material, and it can help to create a tailormade solution for a specific application.

In addition to insulating and conducting, thermally conductive insulation must also provide good electrical properties, and it is important that it be durable enough to withstand drilling in mechanical fixing installations and maintain its breakdown voltage over time. Bergquist's SIL PAD family of thermally conductive, heat curable adhesive pads offer reliability and durability in a range of pad sizes and thicknesses. They are suitable for a variety of applications, including those that need to be machined or die-cut into custom shapes and sizes.