| Material Class |
Description |
Benefits |
Drawbacks |
Bulk K (W/mK) |
Surface Wetting |
Surface Conforming |
Vendors |
| Grease |
These are the traditional TIMs filled with conductive particles of Al2O3, BeO, Al, Ag, etc. |
Can achieve very thin bond lines <0.005" |
Difficult to apply to assemblies Messy Typically pumps out affecting long-term reliability Requires controlled dispensing No electrical isolation |
0.3-2 Al filled 6+ |
Very Good |
Very Good |
Hi-K Grease Shinetsu Bergquist |
| Gel |
Grease replacement that closs-links during cure to form a gel-like substance |
Can achieve very thin bond lines <0.005" Does not pump out |
Cannot be preapplied to assemblies Requires cure which can be from burn-in Messy Requires controlled dispensing No electrical isolation |
0.3-2 |
Very Good |
Very Good |
Thermoset-Lord MG Series |
| Adhesive |
Heat cured adhesives filled with conductive particles similar to grease |
Can achieve very thin bond lines <0.005" Mechanical and thermal attach |
Cannot be preapplied Typically requires process oven curing Messy Requires controlled dispensing Typically no electrical isolation |
0.3-1.3 |
Very Good |
Very Good |
Dow Corning 3M |
| Tape |
Usually pressure sensitive adhesive filled with conductive particles on a fiberglass or plastic carrier |
Mechanical and thermal attach Can be die cut and preapplied Clean, simple processing Typically electrical isolating |
Typically thick bondlines with low conductivity |
0.7-1.5 |
Moderate |
Poor |
Bergquist 3M Dow Corning |
| Phase Change |
A waxy type material that changes to a gel at apporximately 50°C, allowing it to conform to surface irregularities. Can be preapplied or supplied on a carrier |
Can achieve very thin bond lines <0.005" when preapplied Fairly clean process With carrier has electrical isolation |
Typically low thermal conductivity The phase change material itself is usually very thin and does not conform to large irregularities |
0.8-1.5 |
Very Good |
Very good for irregularities <0.002" Very poor for large irregularities or bowing |
Bergquist 3M Dow Corning |
| Pads |
Typically thick materials 0.010"-0.250" thick. Some are very compliant with a low K and others are not very compliant with a reasonably high K |
Simple to use Can typically be re-used Can be die-cut and preapplied Clean process |
Typically requires moderate to high pressuresto achieve reasonable performance - can be tricky to use effectively Typically do not conform well to small surface irregularities Thick bondlines |
0.8-4 |
Poor |
Very good for large irregularities Very poor for small irregularities |
Bergquist 3M Dow Corning |