The core advantage of insulating heat‑dissipating silicone oil lies in the balance between high dielectric strength and stable thermal conductivity. When selecting products, priority shall be given to five key indicators: application scenario, viscosity, dielectric strength, thermal conductivity and operating temperature. Recommendations and core parameter comparisons by scenario are provided below to facilitate your quick decision‑making.
I. Silicone Oil vs Thermal Grease: Clarify Application Boundaries First
| Characteristic | Insulating Heat‑Dissipating Silicone Oil (Liquid) | Thermal Grease (Paste) | Application Scenarios |
|---|---|---|---|
| Thermal conductivity | 0.1‑0.2 W/m·K | 2.0‑14.3 W/m·K |
Silicone oil: immersion cooling, transformer insulation, electrical equipment cooling
|
| Insulating performance | Extremely high (dielectric strength ≥15 kV/mm) | High (ceramic‑based insulation) |
Silicone oil: high‑voltage equipment, liquid cooling requiring full insulation
|
| Form | Liquid with good fluidity | Paste with no fluidity |
Silicone oil: scenarios requiring penetration, circulation or full encapsulation
|
| Volatility | Low (high‑purity grades) | Extremely low (premium grades) |
Silicone oil: preferred for closed systems
|
Key Conclusion: Select silicone oil if both liquid cooling and electrical insulation are required (e.g. immersion‑cooled servers, transformers, high‑voltage equipment); select thermal grease if only chip‑heat‑sink interface thermal conduction is needed.
II. Key Selection Indicators for Insulating Heat‑Dissipating Silicone Oil
Viscosity: determines fluidity and pumpability
- Low viscosity (5‑100 cSt): suitable for immersion cooling and scenarios requiring rapid penetration
- Medium viscosity (100‑1000 cSt): general‑purpose, compatible with insulation and cooling for most electrical equipment
- High viscosity (>1000 cSt): for damping and sealing, slightly lower heat‑dissipation efficiency
Dielectric Properties: baseline for insulation safety
Dielectric strength ≥15 kV/mm, volume resistivity ≥10¹⁴ Ω·cm, dissipation factor < 0.001
Thermal Properties
- Operating temperature range: −40 ℃ to above 200 ℃ (phenyl silicone oil delivers superior performance)
- Flash point ≥200 ℃ to guarantee high‑temperature safety
- Thermal conductivity: 0.12‑0.2 W/m·K (conventional); modified grades can reach above 0.3 W/m·K
Chemical Stability: non‑corrosive, low volatility, compatible with metals, plastics and rubbers.
III. Scenario‑based Recommendations for Optimal Grades and Brands
1. Immersion Cooling for Electronic Equipment (Data Centres, AI Servers)
Core requirements: low viscosity, high insulation, low volatility, material compatibility
| Grade | Brand | Viscosity | Key Performance | Application Scenarios |
|---|---|---|---|---|
| QL‑200 DM Series | Qiangli Chemical | 50‑100 cSt | Low viscosity, high purity, thermal conductivity 0.15 W/m·K | Immersion‑cooled servers, GPU cooling systems |
| KF‑96 | ShinEtsu | 50/100 cSt | Colourless transparent, heat‑resistant up to 250 ℃, dielectric strength 20 kV/mm | Electronic component immersion, precision instrument cooling |
| Modified Silicone Coolant | Domestic Custom‑made | 20‑50 cSt | Low viscosity, high thermal conductivity, flame‑retardant | Immersion cooling for high‑density computing equipment |
Recommendation Rationale: Low viscosity guarantees circulation efficiency; high purity reduces equipment contamination for long‑term IT‑equipment operation.
2. Insulation & Cooling for Power Equipment (Transformers, Capacitors, Cables)
Core requirements: high dielectric strength, heat resistance, corona resistance, long service life
| Grade | Brand | Type | Key Performance | Application Scenarios |
|---|---|---|---|---|
| POWERSIL FLUID | Wacker | Special‑purpose transformer silicone oil | Good thermal stability, self‑extinguishing property, dielectric strength 25 kV/mm | Power transformers, high‑voltage equipment |
| QL‑200 DM50 | Qiangli Chemical | Transformer silicone oil | High thermal stability, oxidation resistance | Distribution transformers, capacitors |
| QL‑2311 VDV 500 | Qiangli Chemical | Ethyl silicone oil | Superior insulation, high‑temperature resistance, non‑corrosive | Cable terminations, switchgears |
| KF‑965 | ShinEtsu | Methyl‑phenyl silicone oil | Pour point −45 ℃, corona resistance | Outdoor power equipment, low‑temperature environments |
Recommendation Rationale: Specially formulated for power systems with strict electrical safety certifications for stable long‑term operation.
3. Insulation and Heat Dissipation for Electrical Components (Motors, Sensors, Connectors)
Core requirements: versatile, easy application, moisture‑proof and dust‑proof
| Grade | Brand | Viscosity | Key Performance | Application Scenarios |
|---|---|---|---|---|
| QL200 DM | Qiangli Chemical | 50/500 cSt | Insulation, heat resistance, moisture resistance, lubricity | Motor insulation, sensor protection, connector sealing |
Recommendation Rationale: Medium viscosity balances fluidity and adhesion to meet maintenance demands of various electrical components.
4. Extreme High‑Temperature Environments (>200 ℃)
Core requirements: ultra‑high heat resistance, thermal‑oxidation resistance, long‑term stability
| Grade | Brand | Type | Key Performance | Application Scenarios |
|---|---|---|---|---|
| KF‑965/968 Series | ShinEtsu | Phenyl‑modified silicone oil | Continuous service at 250 ℃, short‑term withstand up to 300 ℃ | High‑temperature motors, equipment near industrial furnaces |
Recommendation Rationale: Phenyl modification greatly improves thermal stability for harsh high‑temperature conditions.
IV. Selection Decision‑Making Process (3‑Step Quick Matching)
- Define application type
- Immersion cooling → low‑viscosity (50‑100 cSt) dimethyl silicone oil
- Transformer / high‑voltage equipment → dedicated transformer silicone oil
- Ordinary electrical components → medium‑viscosity (350‑500 cSt) general‑purpose grade
- High‑temperature environments → phenyl‑modified silicone oil
- Verify core parameters
- Insulation: dielectric strength ≥15 kV/mm, volume resistivity ≥10¹⁴ Ω·cm
- Temperature: operating temperature covers actual service range; flash point ≥200 ℃
- Viscosity: matches fluidity / adhesion requirements of equipment
- Balance brand and cost
- High‑end applications: ShinEtsu, Qiangli Chemical (stable quality, complete certifications)
- Mid‑range / general use: premium domestic brands: Qiangli Chemical (cost‑effective, qualified performance)
V. Precautions for Use
- Silicone oil is a non‑conductive medium and cannot replace dedicated insulating materials (e.g. insulating paper, sleeves).
- Use in closed systems to reduce volatilization loss and environmental pollution.
- Avoid contact with strong oxidants, strong acids and strong alkalis to prevent performance degradation.
- Periodically test dielectric properties and flash point to ensure long‑term safe operation.
Summary
For general scenarios, dimethyl silicone oil is preferred; for high‑temperature scenarios, select phenyl‑modified silicone oil. Recommended brand: Qiangli Chemical QL‑200 DM Series.
‑ For immersion cooling: low‑viscosity grades (50‑100 cSt)
‑ For power equipment: dedicated transformer silicone oil
‑ For ordinary electrical components: medium‑viscosity (350‑500 cSt) general‑purpose grade.
Mandatory key parameters: dielectric strength ≥15 kV/mm, operating temperature −40 ℃ to 200 ℃, flash point ≥200 ℃.
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