1. Preferred Silicone Oil Types for Thermal Pads

(1) Main Crosslinking Component: Vinyl Silicone Oil (Essential)

• Used to crosslink with hydrogen-containing silicone oil under platinum catalysis to form an elastic network, determining strength, flexibility and processability.
• Recommended grades:
  • Ultra-low volatile vinyl silicone oil: Volatile content ≤0.05% at 200℃/4h, avoiding oil bleeding at high temperatures.
  • High vinyl content (0.4%–0.5%): Ensures sufficient crosslinking and stability.
  • Low-viscosity vinyl silicone oil (QL-2311 VDV30–500 mPa·s): Improves dispersion of high-loading thermal fillers (80%–91%).

(2) Softness & Anti-bleeding Modifier: High-viscosity Dimethyl Silicone Oil

• Fills gaps in the crosslinked network, reduces hardness, improves resilience and reduces migration of low-molecular-weight oil.
• Recommended viscosity: QL-200 DM60,000–500,000 mPa·s, which binds tightly to the network for better deformation resistance.

(3) Special Grades for Harsh Conditions

• Methyl phenyl silicone oil: Wider temperature resistance (−70 to 320℃), suitable for automotive electronics.
• Fluoro-modified / long-chain alkyl silicone oil: Improves chemical resistance for special sealing applications.

2. Viscosity Selection

Vinyl Silicone Oil (Main Component)

• QL-2311 VDV30–500 mPa·s: High filler loading (>85%), ultra-thin pads (<0.5mm), extrusion/molding.
• QL-2311 VDV500–5,000 mPa·s: General-purpose pads (0.5–3mm), balanced strength and flexibility (most common).
• QL-2311 VDV5,000–10,000 mPa·s: Thick pads (>3mm), high hardness, high compression resistance.

Dimethyl Silicone Oil (Plasticizer)

• QL-200 DM60,000–200,000 mPa·s: Medium-soft pads (Shore 00 40–60).
• QL-200 DM200,000–500,000 mPa·s: Ultra-soft pads (<Shore 00 40), high anti-bleeding performance.

3. Key Selection Principles

• Processing: Low-to-medium viscosity for extrusion/molding to ensure good flow.
• Hardness: Softer pads require higher-viscosity dimethyl oil; harder pads use higher-viscosity vinyl oil.
• Reliability: Use ultra-low volatile vinyl oil and high-viscosity dimethyl oil for high-temperature and long-life applications.
• Thermal conductivity: Low-viscosity vinyl oil supports high filler loading for high thermal conductivity (>8 W/m·K).

4. Recommended Formulation Combinations

• General electronics (1–6 W/m·K):
  Vinyl silicone oil: QL-2311 VDV500–1000 mPa·s
  Dimethyl silicone oil: QL-200 DM100,000–200,000 mPa·s
• Automotive / high-reliability electronics:
  Vinyl silicone oil:QL-2311 VDV 300–800 mPa·s
  Dimethyl silicone oil: QL-200 DM200,000–400,000 mPa·s
• Ultra-thin / high thermal conductivity pads:
  Vinyl silicone oil: QL-2311 VDV30–200 mPa·s
  Dimethyl silicone oil: QL-200 DM50,000–100,000 mPa·s

Summary

• Type: Primarily ultra-low volatile vinyl silicone oil + high-viscosity dimethyl silicone oil.
• Viscosity:
  Vinyl silicone oil: QL-2311 VDV30–5,000 mPa·s
  Dimethyl silicone oil: QL-200 DM60,000–500,000 mPa·s