The thermal pad material selected for CPU cooling affects performance, reliability, and long-term system integrity. Silicone-based pads are the default, but silicone-free alternatives address specific failure modes, and graphene pads represent an emerging third option.
This guide compares the three material categories for CPU thermal pad applications.
Silicone Thermal Pads
Silicone-based thermal pads are the most common type. The silicone elastomer serves as the matrix material, filled with thermally conductive particles (aluminum oxide, zinc oxide, boron nitride) to achieve the target conductivity.
Advantages:
- Wide range of conductivities available (1.5-24 W/mK)
- Excellent conformability and softness
- Good compression characteristics
- Cost-effective
- Available from many manufacturers (Bergquist, Laird, T-Global, Parker Chomerics)
Disadvantages:
- Silicone bleeding — silicone oil can migrate from the pad onto nearby components, contaminating optical surfaces, electrical contacts, and sensors
- Outgassing — in vacuum or low-pressure environments, silicone releases volatile compounds (see our outgassing guide)
- Silicone sensitivity — some manufacturing processes prohibit silicone due to contamination risks
For a balanced perspective on silicone-free adoption, see our guide on why silicone-free thermal pads are not exclusively used.
Search volume for “silicone thermal pads” is approximately 2,400 monthly searches, reflecting their dominance in the market.
Silicone-Free Thermal Pads
Silicone-free thermal pads use alternative elastomer matrices — typically urethane, acrylic, or proprietary polymer blends — to eliminate the risks associated with silicone bleeding and outgassing.
Advantages:
- No silicone bleeding — safe for use near optics, sensors, and electrical contacts
- Low outgassing — suitable for aerospace and vacuum applications
- Compatible with silicone-sensitive manufacturing processes
Disadvantages:
- Higher cost than silicone pads
- Fewer material options available
- Some silicone-free pads are stiffer than silicone equivalents (lower conformability)
- Limited thickness range for some product lines
Recommended Silicone-Free Materials
- Laird TFLEX SF10 (10 W/mK) — compliant, ultra-soft, high conductivity
- Laird TFLEX SF16 (16 W/mK) — ultra-soft, silicone-free
- T-Global TG-APC93 — non-silicone thermal pad
- Parker Chomerics CHO-THERM T444 — thin non-silicone insulator with PSA
For more, see our guide on silicone-free gap pads and our silicone-free thermal pad options. Our guide on silicone-based thermal pads and alternatives provides a broader comparison.
Graphene Thermal Pads
Graphene thermal pads use flexible graphite or graphene-based materials as the thermal interface. Graphene’s in-plane thermal conductivity is extremely high (up to 5,000 W/mK), but through-thickness conductivity — the direction that matters for CPU cooling — is more modest.
Advantages:
- Extremely high in-plane conductivity (useful for heat spreading)
- Thin profile available
- No polymer matrix — no bleeding, no outgassing
- Electrically conductive (can serve as EMI shield in some designs)
Disadvantages:
- Through-thickness conductivity is only 5-10 W/mK — comparable to mid-range silicone pads
- Electrically conductive — cannot be used where electrical isolation is needed
- Limited conformability — graphene pads are relatively stiff
- Higher cost than silicone pads
- Limited commercial availability at production scale
Search volume for “graphene thermal pads” is approximately 480 monthly searches. While promising, graphene pads are not yet a mainstream choice for CPU cooling. For more on thermal conductivity comparisons, see our guide on thermal conductivity is not everything.
Thermal Putty: A Fourth Option
Thermal putty is a moldable compound applied by hand. It fills gaps of any size and conforms to any surface, but it cannot be die-cut and is only practical for manual installation. See our guide on phase-change thermal pads for a comparison with putty alternatives.
Search volume for “thermal putty vs thermal pads” is approximately 880 monthly searches.
Conductivity Comparison for CPU Applications
Which Material Should Be Chosen for CPU Cooling?
Default: silicone thermal pads — suitable for the majority of CPU cooling applications. Available in the widest range of conductivities and thicknesses, cost-effective, and well-documented.
Choose silicone-free when:
- The CPU is near optical components or sensors
- The application is in a vacuum or low-pressure environment
- Manufacturing processes prohibit silicone contamination
Choose graphene when:
- In-plane heat spreading is more important than through-thickness heat transfer
- EMI shielding is needed alongside thermal management
- The application can accommodate a stiffer pad
Choose phase-change when:
- The gap is thin (<0.3 mm) and paste-level performance is needed
- Production consistency is critical
For more on material types, see our guide on different types of thermal pads and our guide on thermal pad comparisons.
Sourcing Thermal Pad Materials from NEDC
NEDC stocks silicone, silicone-free, phase-change, and graphite thermal pad materials from all major manufacturers. We can help select the right material for CPU applications and die-cut custom shapes for production.
Request a quote or visit our thermal pads page for the full material catalog. For silicone bleeding considerations, we can provide testing data on request.