Heatsink compound-ZZcooler Electronics Company

Contact Thermal Resistance

Component and heat sink surfaces are not perfectly smooth and flat .When they contact each other, the actual contact area is only a small fraction of the mating surface area .The voids formed by surface roughness are filled with air which has very low thermal conductivity.The thermal resistance due to imperfect contact is called the contact thermal resistance.

Thermal Interface Materials
Thermal interface materials are used to fill the air gaps between two contacting surfaces and improve heat transport across the contact.

Desirable Properties of Interface Materials
High thermal conductance.Compliance to conform to both microscopic and macroscopic irregularities.Ability to wet the contacting surface materials.Robust in manufacturing, storage and application environments.Remain compliant without dryout in use.High dielectric strength when needed.

Types of Thermal Interface Materials
In order of thermal performance.Thermal greases and gels.Phase change materials.Low modulus adhesives.High modulus epoxies.Pressure sensitive tapes or films.Elastomeric Pads.