Both are black, both are sold as graphene or graphite thermal solutions, and they do opposite things. A graphite sheet spreads heat sideways. A thermal pad moves heat across a gap. Choosing the wrong one is one of the most common and most expensive TIM specification errors.
The one-line difference
| Graphite / graphene sheet | Thermal pad | |
|---|---|---|
| Primary job | Spread heat laterally (in-plane) | Conduct heat across a gap (through-plane) |
| Typical in-plane k | 400–1600 W/m·K | Low — not its function |
| Typical through-plane k | 5–20 W/m·K | 3–180 W/m·K |
| Conformability | Poor — it is a stiff foil | Good — compresses into surface roughness |
| Fills an air gap? | No | Yes — this is its purpose |
| Requires flatness | Yes, and contact pressure | Tolerant of imperfect surfaces |
| Typical use | Behind a display, on a phone mid-frame | Between a chip and a heatsink |
Why the anisotropy exists
Graphite is a layered crystal. Within each layer, carbon atoms are bound strongly and heat moves easily; between layers, the bonding is weak and heat moves slowly. Roll that into a sheet and the layers lie flat, so the fast direction is in the plane of the sheet. This is physics, not a manufacturing defect — no amount of processing makes a conventional graphite sheet conduct well through its thickness.
When to use each
Use a sheet when heat is concentrated and needs distributing
A phone SoC hot spot, a display driver, a narrow PCB trace carrying high current. The sheet turns a point source into a broad one that the enclosure can dissipate.
Use a pad when heat must cross from one part to another
Die to lid, lid to cold plate, baseplate to heatsink, cell to cold plate. There is a gap, however small, and something has to fill it.
Use both when you have both problems
Common in slim devices: a pad moves heat off the die, a sheet spreads it across the back of the housing. Stacked correctly they complement each other; used as substitutes they fail.
Where our products sit
Lenecold thermal pad — 180 W/m·K through-plane, for crossing gaps. Lenecold thermal plate — 1200 W/m·K with real thickness, machinable, for spreading where a foil is too flimsy to do the job. The plate behaves like a structural spreader rather than a film, which suits aerospace, UAV and high-flux RF hardware.