Choosing the right silicone thermal interface material is important for efficient heat transfer, preventing overheating, and ensuring the reliable performance and longevity of electronic devices. In this article, we’ll explore the top-rated silicone thermal interface materials and what makes them stand out in the world of thermal management.
Overview: What Are Silicone Thermal Interface Materials?
By replacing air with a thermally conductive material, they significantly improve heat transfer efficiency.
Types of Silicone TIMs
- Thermal Pads: Soft silicone sheets infused with fillers. They are easy to install and conform well to uneven surfaces, but require pressure to perform effectively and generally have lower thermal conductivity compared to other TIMs.
- Thermal Greases/Pastes: Thick, sticky compounds containing metal or ceramic fillers. They provide excellent heat transfer with very thin layers, but can be messy and require careful, precise application.
- Thermal Gels: Similar to greases but more stable over time. They stay in place better and reliably fill gaps without drying out or flowing away.
- Gap Fillers / Gel Pads: Soft, compressible materials designed for filling thicker or uneven gaps. These are commonly used in industrial and power electronics applications where larger gaps must be accommodated.
Why Use Silicone TIMs?
- They enhance heat transfer by replacing insulating air gaps with thermally conductive materials.
- Available as pads, pastes, and gels to fit diverse assembly needs.
- Provide reliable performance even in challenging conditions such as heat, vibration, and moisture.
Silicone TIMs are flexible, reliable, and effective for keeping electronics cool.
Key Points to Consider When Choosing Silicone TIMs
- Thermal Performance & Impedance: Choose thin, flexible TIMs with high thermal conductivity for improved heat transfer and low thermal resistance.
- Gap Size & Compressibility: Select a TIM thickness that matches the gap between components. Very thin gaps (under 0.05 mm) are best filled with pastes or phase-change materials, while larger gaps (over 0.5 mm) require softer, thicker fillers. Ensure the material compresses sufficiently to fill voids and maximize heat transfer.
- Application Method: Greases and gels are ideal for automated, precise dispensing but require careful control. Pads and tapes are easier to handle manually or with pick-and-place equipment. Also, consider the ease of reworking or replacing the TIM.
- Operating Environment & Reliability: Verify that the TIM remains stable across the required temperature range (typically −40 °C to 100–200 °C) and can withstand humidity, vibration, and thermal cycling. In harsh or high-vibration environments, cured gels or potting compounds provide better reliability.
- Material Compatibility & Chemical Stability: Use TIMs that are safe for nearby components and expand or contract at a similar rate as your device to prevent damage from temperature changes.
- Electrical & Safety Requirements: If electrical insulation is necessary, use dielectric pads or gap fillers rather than conductive pastes. Confirm flame-resistance ratings and relevant safety certifications.
How to Choose
- Define your thermal needs – Determine the heat flux your device generates and the exact gap size between components.
- Select the application method – Choose between manual or automated application, and decide whether pads, pastes, gels, or gap fillers best suit your workflow.
- Consider the operating environment – Account for temperature extremes, humidity, vibration, and potential exposure to dust or chemicals.
- Check compatibility – Ensure the TIM is chemically and mechanically compatible with your device materials to avoid corrosion, degradation, or adhesion issues.
- Match the format to your needs – Pads offer quick installation, pastes provide excellent conformity, gels are flexible, and gap fillers work for larger or irregular spaces.
- Verify insulation and safety requirements – Confirm compliance with electrical insulation, flammability ratings, and any industry safety standards.
- Test in real conditions – Evaluate the TIM’s thermal performance and durability under actual operating conditions before finalizing your choice.
Following these steps helps you select a silicone TIM that reliably meets your device’s thermal, mechanical, and production requirements.
Top-Rated Silicone Thermal Interface Materials
- Thermal Pads
Example: TG-AD75 Ultra Soft Thermal Pad.
Thermal Conductivity: They offer a thermal conductivity of 7.5 W/m·K and an ultra-soft texture rated at Shore OO 25.
Why Use:
- Great electrical insulation.
- High thermal conductivity.
- High reliability and stability.
- Low thermal impedance.
- Thermal Grease / Paste
Example: TG-N909 Non-Silicone Thermal Paste.
Thermal Conductivity: About 9W/m·K.
Why Use:
- Non-silicone base, no Environmental pollution.
- Silicone oil free.
- High thermal conductivity.
- No overflow.
- Low thermal impedance/thermal resistance.
- Potting Compound
Example: TG-A09AB / TG-S09AB Potting Compound.
Thermal Conductivity: About 2.8W/m·K.
Why Use:
- A: B=1:1.
- Good thermal conductivity.
- Room temperature or heating curing.
- Protect the base material with a high hardness for support.
Select the silicone TIM type that best matches your device’s thermal requirements, mechanical setup, and environment to maintain component reliability and performance over time.
Best Practices for Applying Silicone TIMs
- Pick the Right Type
Match the TIM to your gap size:
- Less than 0.05 mm → Use thermal paste or grease.
- 0.05 – 0.5 mm → Use thermal pads or phase-change materials (PCM).
- More than 0.5 mm → Use gap fillers, gels, or putties.
- Clean the Surfaces First
Use isopropyl alcohol to clean both the chip and the heatsink. This removes dust, oil, and old TIM, ensuring better heat transfer.
- Apply the Right Amount
Too much TIM adds resistance; too little leaves air gaps. A thin, even layer that fills small gaps without spilling over.
- Avoid These Common Mistakes
- Don’t stack pads or mix TIM types.
- Don’t reuse old TIM, replace it after each disassembly.
- Don’t trap air, apply from one side to let bubbles escape.
- Apply Proper Pressure
Use enough pressure to ensure full contact, but not so much that the TIM is squeezed out or parts get damaged.
- Automate if You Can
If you’re using gels or pastes, use a dispenser or stencil for even application.
Remove air from liquid TIMs to avoid bubbles during curing.
Conclusion: How to Choose the Right Silicone Thermal Interface Material
Choosing the right silicone TIM is important for effective cooling and device longevity, with different types suited to various gaps and conditions.
Consider heat transfer efficiency, gap size, application method, durability, material compatibility, and safety when selecting a TIM.
Proper surface preparation, correct application, and appropriate pressure also improve cooling effectiveness. By understanding your device’s needs and picking the right silicone TIM, you can ensure reliable and efficient thermal management for your electronics.
