Here is a summary of the different types of thermal interface materials available today. They are divided into two categories: non-adhesive or clamping required, and adhesive or self-supporting solutions. Non-adhesive materials require a mechanical fixture in order to hold the assembly together. Thermal greases, phase change materials, and gels offer the best thermal performance because they are liquid during operation. This provides excellent wetting of the interface and low thermal resistance. Phase change materials have the added benefit of being solid at room temperature, and are supplied in preforms and sheets that are easy to work with. Thermal films or pads come in similar formats, but have lower thermal performance. Adhesive materials provide structural support for the assembly, so no screws or clamps are needed. Thermally conductive pastes and films are widely used for bonding parts together with excellent heat dissipation. Solder can only be used on metallic surfaces, and tapes offer decreased thermal performance.