The Silent Degrader: Preventing Thermal Grease and Pad Oxidization for Consistent Performance
A Thermal Interface Material (TIM) can begin to fail before it ever touches a chip. Oxidization and component separation—driven by exposure to air, heat, and humidity during storage—can silently degrade performance, leading to higher-than-expected thermal resistance or application failure. Proactive handling is key to preserving the performance you paid for.
Common Degradation Modes in Storage:
- Polymer Oil Bleed & Separation (Greases/Pastes): The silicone or hydrocarbon oil carrier can separate from the solid filler particles, rising to the top of the syringe or tube. This leads to inconsistent viscosity and poor thermal performance upon application. It’s accelerated by high-temperature storage.
- Oxidative Cross-Linking & Skin Formation: Exposure to air (oxygen) causes the surface of greases and some pads to form a hard, unusable skin. For pads, this can manifest as a loss of surface tack and conformability.
- Moisture Absorption (Hygroscopic Pads): Some non-silicone polymer matrices absorb water vapor from humid air. This can affect dielectric properties, cause outgassing during reflow, and promote corrosion at the interface.
Best Practices for TIM Preservation:
- Control Temperature: Store in a cool, stable environment (15-25°C/59-77°F). Avoid warehouses or shelves near heat sources. Do not refrigerate, as condensation can form upon removal.
- Limit Air Exposure: For syringes, store tip-down to minimize the surface area of grease exposed to air in the nozzle. Reseal opened containers tightly.
- Manage Humidity: Keep in a low-humidity environment (<60% RH). Use original packaging with desiccant packs. For bulk pads, use sealed bags.
- Follow FIFO (First-In, First-Out): Implement strict inventory rotation based on the manufacturer’s shelf life (typically 12-24 months from production date). Mark received dates clearly.
- Inspect Before Use: For greases, inspect for severe separation. A small amount is normal and can be mixed with a clean tool. For pads, check for discoloration, hardening, or loss of liner adhesion.
Treating TIMs as sensitive chemical components, rather than simple hardware, ensures they deliver their specified performance from the first unit to the last in your production run, safeguarding product quality and reliability.
