Gap Pad

Gap Pad 3500ULM

Features & Benefits

  • Thermal conductivity: 3.5 W/m-k
  • Highly conformable and maintains structure integrity with extremely low compression stress
  • Fiberglass reinforced for puncture, shear and tear resistance
  • Non-fiberglass option for reduced stress required in application


Gap Pad® 3500ULM (ultra low-modulus) is an extremely soft gap filling material rated at a thermal conductivity of 3.5 W/m-K. The material offers exceptional thermal performance at low pressures due to a unique 3.5 W/m-K filler package and ultra-low modulus resin formulation. The enhanced material is well suited for high performance applications requiring extremely low assembly stress. Gap Pad® 3500ULM maintains a conformable nature that allows for excellent interfacing and wet-out characteristics, even to surfaces with high roughness and/or topography. Gap Pad® 3500ULM is offered with and without fiberglass and has higher natural inherent tack on one side of the material, eliminating the need for thermally-impeding adhesive layers. The top side has minimal tack for ease of handling. Gap Pad® 3500ULM is supplied with protective liners on both sides.

Typical Applications include

  • Consumer electronics
  • Telecommunications
  • ASICs and DSPs
  • PC applications


Typical properties of Gap Pad 3500ULM
Properties Imperial Value Metric Value Test Method
Reinforcement Carrier Fiberglass or No fiberglass Fiberglass or No fiberglass ***
Color Gray Gray Visual
Inherent Surface Tack 2 2 ***
Density (Bulk Rubber) (g/cc) 3.1 3.1 ASTM D792
Heat Capacity (J/g-K) 1.0 1.0 ASTM E1269
Young's Modulus (psi) / (kPa) (1) 4 27.5 ***
Typical Use Temp (°F) / (°C) -76 to 392 -60 to 200 ***
Thickness (inch) / (mm) 0.020 to 0.125 0.508 to 3.175 ASTM D374
Typical properties of Gap Pad 3500ULM
Electrical Imperial Value Metric Value Test Method
Dielectric Breakdown Voltage (Vac) >5000 >5000 ASTM D149
Dielectric Constant (1000 Hz) (2) 6.0 6.0 ASTM D150
Volume Resistivity (Ohm-meter) 10^10 10^10 ASTM D257
Flame Rating V-O V-O U.L. 94
Typical properties of Gap Pad 3500ULM
Thermal Imperial Value Metric Value Test Method
Thermal Conductivity (W/m-K) 3.5 3.5 ASTM D5470
Typical properties of Gap Pad 3500ULM
Deflection (% strain) 10 20 30
Thermal Impedance (ºC-in2/W) 0.040" 0.50 0.44 0.39
  • (1) Young’s Modulus, calculated using 0.01 in/min. step rate of strain with a sample size of 0.79 inch^2 after 5 minutes of compression at 10% strain on a 1mm thickness material.

  • (2) Minimum value at 20 mil.


Configurations available

  • Sheet form and die-cut parts available


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