Below 0.3 mm the rules change. Bulk resistance stops dominating, contact resistance takes over, and a pad that is marginally thinner can measure worse than the one it replaced. Our 0.15 and 0.20 mm graphene pads are produced to order for exactly these stacks - optical mounts, laser crystals, thin modules - and the measured curves below show where they win and where they do not.
Measured performance
26 × 26 mm samples, 80 °C, 600 s per point. Resistance in °C·cm²/W, compression in percent of measured initial thickness (0.159 / 0.197 mm):
| Pressure (psi) | R 0.15 mm | R 0.20 mm | Compression 0.15 | Compression 0.20 |
|---|---|---|---|---|
| 5 | 0.168 | 0.255 | 12.6% | 11.2% |
| 10 | 0.088 | 0.109 | 19.5% | 15.2% |
| 20 | 0.054 | 0.058 | 24.5% | 20.8% |
| 30 | 0.045 | 0.045 | 28.9% | 24.9% |
| 40 | 0.040 | 0.042 | 31.4% | 28.4% |
| 50 | 0.038 | 0.039 | 34.0% | 31.0% |
At 30-50 psi the two thin pads converge with the 0.30 mm standard: 0.038-0.045 °C·cm²/W. Below about 15 psi they do not - and at 5 psi the 0.20 mm is the worst of the three (0.255). Thin pads need flatness and pressure; that is the trade for the lower floor.
Where a 0.15 / 0.20 mm pad is the right part
- Optical and laser assemblies. Crystal-to-copper and optic-to-mount interfaces where the gap is small, the ΔT budget is tight and the load must stay gentle. See the laser and optical crystal guide.
- Thin modules with hard stops. Where the compressed thickness is set by a machined step and the whole stack is under 1 mm.
- Handheld and wearable devices. Where 0.3 mm of pad is a packaging problem and the enclosure acts as the heat sink.
- Replacing a grease or phase-change layer in a sealed unit. Same order of thickness, no pump-out, no migration.
Where it is the wrong part
- Rough or warped surfaces. A thin pad has almost no material to fill a wedge; either lap the surfaces or use 0.5 mm and accept the bulk resistance.
- Light spring clips below 10 psi. Measured data says the thicker pad wins there.
- Large gaps from tolerance stack. If worst-case gap exceeds 0.25 mm, the thin pad cannot bridge it - design the step, not the pad.
Specification
| Property | 0.15 mm | 0.20 mm |
|---|---|---|
| Through-plane conductivity (material) | 180 W/m·K | 180 W/m·K |
| Measured joint resistance, 20-50 psi | 0.038-0.054 °C·cm²/W | 0.039-0.058 °C·cm²/W |
| Compression at 30 psi | 28.9% | 24.9% |
| Operating temperature | -40 to +200 °C | -40 to +200 °C |
| Supply form | Sheet, die-cut to drawing | Sheet, die-cut to drawing |
| Availability | Made to order | Made to order |
Standard stock thicknesses remain 0.3 / 0.5 / 0.7 mm; 0.15 and 0.20 mm are produced to order and die-cut to your drawing. Because thin gauges are less forgiving, we ask for the mounting drawing, the flatness of the mating surfaces and the clamping method before quoting - a thin pad on a bowed heat sink is a wasted sample.
Tolerance and handling notes
- Thickness tolerance matters more here. A ±0.02 mm band is 13% of a 0.15 mm nominal - ask for the measured CoA per lot, not the catalogue band.
- Liner and release force. At this gauge the pad tends to tear on release; specify a liner and release level that suits your pick-and-place, or ask for a carrier film.
- Storage. Keep flat, out of sunlight, below 30 °C; thin sheets take a set if stored rolled.