Thermal Gel vs Thermal Grease Comparison | Material Selection Guide for Heat Dissipation of Power Supply & PCB Electronic Modules

With the continuous power upgrade of new energy power supplies, inverters, charging piles and industrial control PCB modules, heat generation of components has become increasingly prominent. Many procurement engineers often confuse thermal gel and thermal grease. Improper material selection may lead to heat dissipation failure and higher rework rates. This article analyzes the core differences between the two materials from material properties and working conditions, helping electronics manufacturers select suitable thermal interface materials efficiently.
1. Core Parameter Differences Between Thermal Gel and Thermal Grease
Thermal Grease
Base material: silicone oil + thermal conductive powder, paste form, non-curing.
Typical specification: Thermal conductivity 0.8~4.0 W/m·K.
Form: Fluid paste, filling interface gaps relying on fluidity and coating pressure.
Advantages & Disadvantages: Easy to apply with low cost. Prone to oil bleeding and migration under long-term high temperature, not suitable for vertical surfaces or long-term sealed modules.
Thermal Gel
Soft semi-solid material made of cross-linked silicone polymer matrix compounded with thermal conductive fillers, non-curing with inherent adhesion.
Typical specification: Thermal conductivity 1.0~6.0 W/m·K.
Form: Jelly-like elastomer with supporting property and shape retention.
Advantages & Disadvantages: Low oil bleeding, anti-creep, able to adapt to height differences of electronic components, excellent shock resistance, no flow under vertical installation.
2. Application Scenarios Classification
✅ Preferred Scenarios for Thermal Grease
Flat components with uniform gaps (0.05~0.2 mm);
Normal temperature rise conditions, open modules, mass simple assembly, occasions requiring frequent disassembly and maintenance;
Examples: Heat dissipation for common power adapters and small PCB chips.
✅ Preferred Scenarios for Thermal Gel
New energy inverters, energy storage power supplies, vehicle electronic control units, photovoltaic modules;
Uneven components with large gap height differences; equipment under long-term vibration and vertical installation; sealed housings where silicone oil contamination on PCB circuits is prohibited.
3. Common Selection Misunderstandings for Electronic Industry Procurement
Misunderstanding 1: The higher thermal conductivity, the better. Blind pursuit of high thermal conductivity products
Analysis: If the contact gap is large or the surface flatness is insufficient, blindly pursuing high thermal conductivity while ignoring material thickness will cause insufficient fitting. The improvement of heat dissipation performance is limited. Priority should be given to matching material thermal resistance with interface gap thickness.
Misunderstanding 2: Thermal grease can be used in sealed new energy modules for long service life
Analysis: Thermal grease tends to bleed oil under long-term high and low temperature cycles. Oil stains on PCB will absorb dust, reduce surface insulation resistance and cause risks of electric leakage or short circuit. Caution is required for long-life sealed products such as energy storage and automotive electronics.
Misunderstanding 3: Higher hardness thermal gel delivers better heat dissipation
Analysis: Over-hard gel has poor compression resilience, cannot absorb assembly tolerance and thermal expansion stress, and easily causes poor interface contact. Soft materials are required for electronic heat dissipation to fully fit component surfaces and maintain low thermal resistance.
4. Standardized Selection Suggestions
Small consumer power supplies, static equipment, limited budget → Thermal Grease
Energy storage power supplies, charging piles, vehicle ECU, vibration working conditions, sealed modules → Thermal Gel
For components with height difference over 0.3 mm, thermal gel is recommended priority.
Automated dispensing is available for both materials. Thermal gel requires dedicated dispensing equipment, while thermal grease supports screen printing or manual blade coating.
5. Practical Application Case
An inverter manufacturer originally adopted thermal grease of 3.0 W/m·K for power module cooling. After 3 months of continuous high-low temperature cycling test, silicone oil precipitation was found inside the housing, and partial PCB suffered poor insulation performance.
After switching to thermal gel with identical thermal conductivity, no oil bleeding occurred under the same test conditions. Shock resistance was improved, and the overall rework rate dropped by 60%. Although the unit material cost increased slightly, long-term after-sales maintenance cost was greatly reduced.
6. Conclusion
Brief summary: Choose thermal grease for static open environments with small flat gaps. Choose thermal gel for vibrating environments, sealed modules, components with large height differences and long-lifespan new energy products.
Do not compare unit price only during procurement. Comprehensive evaluation combining working conditions, service life and long-term reliability can avoid mass failures in the later stage.