Overview: What Is ThermaCool TC100U?
ThermaCool TC100U is an uncured (B-Stage) by Saint Gobain unsupported thermally conductive silicone rubber sheet designed as both a gap filler and thermal interface. Unlike traditional pre-cured pads, TC100U bonds in place during assembly, making it an effective solution for attaching small passive heat sinks to BGAs and other components without requiring mechanical fasteners.
Key Properties & Engineering Specs
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Material: B-Stage uncured silicone rubber (cures in place)
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Thermal conductivity: ~1.3 W/m·K
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Thermal impedance (1/16″): ~1.25 °C·in²/W
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Hardness: ~65 Shore A
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Break strength: ~200 psi
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Elongation: ~350%
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Dielectric strength: ~9.8 kV/mm
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Operating temperature range: –80 °F to +400 °F
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Standard thicknesses: 0.015″–0.062″ (0.38–1.6 mm)
Why Is TC100U Supplied Uncured?
The “U” in TC100U stands for uncured. This B-Stage formulation is intentional:
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Gap filling before cure: In its uncured state, the silicone can flow slightly under pressure, wetting rough or uneven surfaces. Once cured, it locks into place with minimal interfacial resistance.
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Bonding function: Unlike pre-cured pads, TC100U effectively acts as both a thermal interface and an adhesive, securing a heat sink or component in place.
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Vibration resistance: The material conforms and cures in situ, providing both thermal transfer and mechanical isolation.
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Design flexibility: Engineers can laminate or die-cut the material, apply it during assembly, and let the final cure process “set” the thermal joint.
This uncured design makes TC100U especially valuable in electronics where mechanical fasteners aren’t practical or where a permanent bond is required.
Handling & Assembly Notes
Because TC100U is supplied in an uncured state, it flows to fill surface imperfections when pressed between a component and heat sink, then cures to establish a strong thermal and mechanical bond. This makes it ideal for permanent thermal interfaces where vibration dampening and strong adhesion are desired.
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Liners: TC100U is shipped with protective liners on both sides. These can be slightly more difficult to remove than cured pads, due to the tacky, uncured nature of the material. Operators should peel carefully and, when possible, place the pad in position first and then remove the liner to avoid stretch or distortion.
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Storage: Cold storage is recommended to extend shelf life and prevent premature curing.
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Rework: Once cured, the bond is essentially permanent, so rework should be planned out in advance.
Why Choose TC100U?
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Excellent thermal coupling: Flows and fills gaps, even on rough surfaces.
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Strong adhesion: Bonds directly to substrates such as anodized aluminum, nickel-plated surfaces, and plastic packages.
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Vibration isolation: Its elastomeric properties help protect delicate electronics.
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Easy volume control: Supplied in roll form for consistent, low-waste application.
Common Applications
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Bonding heat sinks to BGAs (flows into them) and chipsets
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Automotive electronic modules
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CD/DVD and optical drive cooling
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Telecom and medical electronics
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Power electronics and industrial modules
Summary Table
| Property | Value |
|---|---|
| Material Type | B-Stage silicone sheet |
| Thermal Conductivity | ~1.3 W/m·K |
| Thermal Impedance | ~1.25 °C·in²/W (1/16″) |
| Hardness | ~65 Shore A |
| Elongation | ~350% |
| Dielectric Strength | ~9.8 kV/mm |
| Temp Range | –80 °F to +400 °F |
| Standard Thicknesses | 0.015″–0.062″ |
| Key Benefits | Gap filling, bonding, vibration isolation |
Final Thoughts
ThermaCool TC100U is not just a thermal pad — it’s a curable bonding solution for electronics that need both efficient heat transfer and mechanical stability. Its uncured design is deliberate, enabling it to flow into gaps, wet surfaces, and cure in place for a permanent thermal and mechanical bond. While the tacky surface can make liner removal a little more challenging, this property is exactly what ensures strong adhesion and low interfacial resistance once cured.