  
 Description
 Advantages
 How it Works
 Intimate Contact
 Choosing the Right
 Material
  figure 3
Magnified view of heat generating component/heat sink surface
The Micropores have air in them
Differential Phase Change Compound
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The initial thermal resistance of PHASE CHANGE allows a heat generating component to briefly heat to a temperature higher than it's normal operating temperature.
As a result, PHASE CHANGE transforms from a solid to a liquid form.
After it wets the thermal interface between the heat generating component and heat sink, the component returns to it's normal operating temperature. The compound then returns to the solid state depending on the operating parameters.
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 Low thermal resistance
 Low mounting force so you can use clips, not screws
 Differential phase change characteristic allows one or
 two-phase operation
 Controlled particulate morphology for superior void
 filling
 Organo-metalic wetting action promotes laminar flow
 Controlled thixotropicity eliminates migration
 Thermoplastic adhesion can eliminate fasteners
 Reversible Adhesive Bond (RAB) characteristic
 Easy to handle - "manufacturing friendly"
 Excellent solvent resistance
 Available in a wide range of thickness
 Environmentally friendly/non-toxic
 Available with Zero delta T adhesive backing
How it Works [back to top]
The initial thermal resistance of the PHASE CHANGE compound allows a heat generating component to briefly heat to a temperature higher than it's normal operating temperature.
The Phase Change compound can then change from a solid to a flowable state, allowing it to “wet” the thermal junction. As a result, overall thermal resistance decreases dramatically, and component operating temperature returns to a normal level.
After this initial process, Phase Change fills the micro roughness of the thermal junction between the heat generating component and the heat sink, forming an efficient thermal joint. Temperatures can remain in a normal operating range even after the initial process. Thermal history is shown in the accompanying illustration. (figure 3)
Intimate Contact [back to top]
Although the surfaces of heat generating components and heat sinks may look smooth, they are quite rough. Containing millions of micropores, these surfaces don’t always make contact with thermally conductive material. Consequently, thermal resistance is high.
If a rigid thermal pad is placed between the heat sink and heat generating component, it will only contact the high points, leaving air – a very poor thermal conductor – in the micorpores. Under high mounting forces, an elastomeric thermal pad can partially flow into these pores. It’s a better solution, but it still cannot fill them completely. Silicone grease can flow into the pores, but it is very messy and can migrate away from the thermal joint.
The Phase Change thermal compound completely fills the micropores of the heat generating component and heatsink. Phase Change remains in the joint through capillary attraction. The compound eliminates the problems of silicone grease and elastomeric materials. Flowing at temperatures slightly higher than normal heat-generating component operating temperatures, it is hundreds of times more thermally conductive than air.
Phase Change material is thermoplastic and exhibits Reversible Adhesive Bonding (RAB). When the material reflows due to heat and pressure, it subsequently re-cools below the phase change temperature, holding the component and heat sink together. By reheating the material again beyond its reflow temperature, adhesion can be reversed, separating the component and heat sink. This process can be instituted an unlimited number of times. As such, Phase Change can be used to replace mechanical fasteners.
Choosing the Right Material [back to top]
If your application requires electrical isolation between the heat generating component and heat sink, use the thinnest polyimide carrier material possible – it must provide the dielectric strength and mechanical resistance you need.
If your application does not require electrical isolation between the heat generating component and heat sink, use an aluminum carrier or free standing material.
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