Synthetic Ester Cooling Fluids

Overview

Synthetic ester cooling fluids are dielectric liquids derived from synthetic ester chemistry, engineered as drop-in or system-redesign alternatives to water-glycol (PG25) and deionized water in direct-to-chip (DTC) cooling, and as PFAS-free alternatives to fluorocarbon fluids in immersion cooling. Their key properties distinguish them from both water-based and fluorinated alternatives:

• Dielectric: Volume resistivity >1×10¹² Ω·cm — a leak causes no electrical damage to components, eliminating the primary operational risk of water-based coolants.
• PFAS-free: No per- or polyfluoroalkyl substances, positioning them as compliant with EU ECHA PFAS restrictions effective 2025–2027 and US EPA regulations.
• Biodegradable: Readily biodegradable with low ecotoxicological impact, reducing environmental liability from fluid disposal and spills.
• High flash/fire points: 180°C–263°C depending on grade, versus water-glycol which has no flash point — enabling deployment in fire-safety critical environments.
• Thermally stable: Long-term oxidation stability validated by OEM/ODM material compatibility programs.

Compared to water-glycol, synthetic ester dielectric fluids are more viscous (5–30 cSt vs. ~2 cSt for water), which historically reduced flow rate and heat transfer efficiency. Intel's SuperFluid technology addresses this through air infusion (bubble generator in the CDU), which reduces working fluid viscosity via an air lubricant effect — allowing oil-based dielectric coolants to achieve comparable flow characteristics and heat removal to water-glycol.

Perstorp's SYNMERSE portfolio (DC-L at 5.6 cSt, DC at 16 cSt, DC-R at 29 cSt) covers the DTC and immersion use cases with PFAS-free synthetic esters. Combined with Intel SuperFluid, the DC-L fluid achieved 1,100 W TDP at 0.7 L/min in Inventec hardware.