At NEDC, we like to think we are experts in thermal interface materials. Flexible graphite material is an excellent thermally conductive material. In fact, I see a lot of thermal interface pads going in this direction due to its great thermal conductivity, & low thermal impedance. In this blog, I wanted to mention a thermal pad type that stands above all the rest in the thermal conductivity category: HPMS Graphite
Properties of HPMS Graphite:
Conductivity In-Plane: 1800 W/m-K (think about that number its 5 times that of copper, 5 times!)
Conductivity Through-Plane(Varies): 10- 26 W/m-K
How HPMS Compares to Other Graphite Thermal Pads
The graphite thermal pad category includes several product families, most prominently Henkel’s TGON 800 series and NEDC’s HPMS line. The key differences: HPMS graphite is rated 1800 W/m-K in-plane (about 5x copper, 7–8x the TGON 800 in-plane rating), and unlike TGON 800, HPMS is configured as an electrically isolating flexible graphite thermal pad in most standard configurations. The trade-off is through-plane conductivity: HPMS ranges from 10–26 W/m-K through-plane, which is lower than some silicone-bound gap pads but is more than sufficient for heat-spreader applications. The decision between HPMS and TGON 800 typically comes down to (a) whether the assembly needs electrical isolation, and (b) whether maximum in-plane spreading is the primary thermal goal.
Applications for Flexible Graphite Sheets
Applications for HPMS Graphite include computer servers, gaming systems, telecommunications, peripherals, and various electronics. In these applications, the flexible graphite serves as either a heat spreader, Z heat transfer, or as EMI shielding, absorbing in electronics. AI accelerator boards, GPU backplates, and high-current power-conversion boards are emerging application areas for HPMS, where 1800 W/m-K in-plane spreading is increasingly specified to manage the localized hot spots that arise from stacked memory and dense power-delivery networks.
What I like about HPMS Thermally Conductive Graphite:
There’s a number of things I like about this material. I’m going just name my two favorite things below because otherwise I’m just repeating all the features :).
It’s not often that we come across a graphite solution that can withstand consistent flexing. Most graphites when bent, immediately crumble. This can be especially frustrating during converting/die-cutting, or even packaging of this material. In addition, these thermal pads provide the highest level of thermal conductivity in the X-Y direction. This is why HPMS is specified for high-density electronics where in-plane heat spreading (not through-plane transfer) is the dominant thermal challenge — for example, across the back of a smartphone PCB, behind an LED array, or between a power-management IC and its enclosure.
More Information
Thicknesses for this flexible graphite include the thin gauges of.012mm, .017mm, .025mm, .040mm, .050mm, .070mm and .100mm. Naturally, the graphite comes in a silver gray color. NEDC is a die cutter that makes custom die-cut products, shapes and sizes for customers. When converting graphite, conventional die cutting is the only thing that works, laser, nor knife works real well. This graphite is available with an adhesive backing for ease in an assembly. For a deeper look at why conventional die-cutting is the right fabrication method for graphite TIMs (and how the cutting method differs from silicone-based gap pads), see our coverage of die-cutting and customization for AI thermal solutions. For more information on thermally conductive graphite material, please contact sales@nedc.com.