Fills the gap between heat source and heat sink to reduce interfacial thermal resistance
Definition: A thermal conductive pad is a silicone sheet filled with thermally conductive powder, used to fill the gap between a heat-generating component and a heat dissipating part.
A thermal conductive pad sits between the heat source and the heat sink, displacing air at the interface and replacing the air layer with a solid conduction path, which lowers interfacial thermal resistance. Under assembly pressure the pad compresses and conforms to surface unevenness, carrying heat into the dissipation structure. Actual results depend on thermal conductivity, thickness, hardness, compression ratio and assembly pressure, and must be assessed together with the structure (subject to the actual test report).
| Model | Thermal conductivity W/(m·K) | Specific gravity g/cm³ | Typical application |
|---|---|---|---|
| Dr.H-10 | 1.0 | 2.00 | Consumer electronics, general gap filling |
| Dr.H-15 | 1.6 | 2.15 | Power modules and LED drivers |
| Dr.H-20 | 2.0 | 2.30 | Industrial control boards, general TIM |
| Dr.H-30 | 3.0 | 2.90 | Telecom base-station power units |
| Dr.H-40 | 4.0 | 3.05 | Energy-storage PCS and vehicle electronic control modules (vehicle-grade qualification rests with the end product manufacturer) |
| Dr.H-50 | 5.0 | 3.20 | AI server chip interfaces |
| Dr.H-80 | 8.0 | 3.35 | Small-area, high heat-flux sources |
Standard grades span 1.0–8.0 W/(m·K). Custom grades built on high-conductivity filler systems such as diamond, graphene and carbon nanotube reach 10–15 W/(m·K); grade names and values are subject to commercial confirmation and the actual test report.
Besides standard silicone thermal pads, the following types are available according to the conduction mechanism and structural requirements. Grade names, thickness and values of custom types are subject to commercial confirmation and the actual test report.
| Type | Base and filler | Characteristics | Typical use | Supply |
|---|---|---|---|---|
| Standard silicone thermal pad | Silicone + alumina / aluminium nitride / boron nitride | General interface filling, wide range of hardness and thickness | Power modules, industrial control boards, telecom equipment | Standard |
| High-conductivity pad | Silicone + high-conductivity fillers such as diamond / graphene / carbon nanotube | Thermal conductivity up to 10–15 W/(m·K) | Small-area high heat-flux chips, AI computing modules | Custom |
| Phase-change pad | Silicone / paraffin-based phase-change system + conductive filler | Softens and wets the interface above the phase-change temperature, lowering contact resistance | Stable gaps where low interfacial resistance is required | Custom |
| Graphene pad | Graphene film / graphene composite layer | Strong in-plane conduction and heat spreading, spreads local hot spots | High power density chip spreading, thin devices | Custom |
| Ceramic heat spreader | Ceramic substrate such as alumina / aluminium nitride | Conducts heat while providing electrical insulation and dielectric strength | Power devices and modules requiring isolation | Custom |
| Thermal absorbing pad | Conductive filler + absorbing filler composite | Conducts heat while absorbing electromagnetic waves in target bands, covering both cooling and EMI | Enclosures with both thermal and interference requirements | Custom |
| Test item | Value | Unit | Test standard |
|---|---|---|---|
| Base material | Silicone + thermally conductive fillers (alumina / aluminium nitride / boron nitride / diamond / graphene / carbon nanotube) | — | — |
| Hardness | 10–50 ±5 | Shore C | ASTM D2240 |
| Dielectric strength | >4.5 | kV/mm | ASTM D149 |
| Volume resistivity | 1014 | Ω·cm | ASTM D257 |
| Flame grade | V0 | — | UL94—2018 |
| Operating temperature | -40 to 200 | °C | — |
| Compression ratio | 10–50 | % | Measured under the specified assembly pressure |
| Environmental test | RoHS 2.0 halogen Pass | — | — |
| Adhesive backing / fibre reinforcement | Optional | — | — |
| Thickness | 0.3–40.0 | mm | Adjustable range; standard supply subject to commercial confirmation |
Values shown are indicative specification ranges for selection discussion. Refer to the actual test report of the specific grade.
| Application | Description |
|---|---|
| AI servers | Thermal filling between GPU modules and heat sinks, building a heat path with air or liquid cooling plates |
| Energy storage PCS | Heat transfer between IGBT / SiC power modules and the base plate, suited to long-term cycling |
| Automotive electronics | Heat transfer between motor controllers, OBC power devices and the housing, with vibration and temperature swing |
| Industrial power | Heat transfer between rectifier modules, transformers and the chassis, helping limit local temperature rise |
1. Quantify power
Determine power dissipation and allowable temperature rise, then derive the required conductivity and interface resistance.
2. Measure the gap
Measure the real assembly gap and tolerance, and choose a thickness that still fills the gap after compression.
3. Set hardness
Select hardness from structural strength; thin-wall parts, ceramics or fragile components suit softer grades.
4. Confirm downstream
Confirm adhesive backing, lamination, die-cut shape, flame retardance and insulation requirements.
Q: What is the difference between a thermal pad and thermal grease?
A thermal pad is a solid sheet with controllable thickness, can be die-cut, suits automated assembly and rework, and fits interfaces with a defined gap. Thermal grease is a paste applied in a very thin layer for very small gaps. The choice depends on gap size, assembly method and rework requirements; parameters are subject to the actual test report.
Q: Is higher thermal conductivity always better?
Not necessarily. Thermal conductivity is a material property; the actual result is also affected by thermal resistance, thickness, compression, assembly pressure and interface wetting. Evaluate conductivity together with the compressed thickness and verify on the structure (subject to the actual test report).
Q: How do I choose the thickness?
Take the measured maximum assembly gap as the baseline and allow a compression margin, so that under assembly pressure the pad compresses to the target ratio and still fills the gap. Excessive thickness raises thermal resistance; insufficient thickness may leave voids. Refer to measurement and testing on the actual structure.
Q: Does a thermal pad need adhesive backing?
Adhesive backing pre-fixes the pad for automated placement and assembly positioning; whether it is needed depends on the assembly process. Note that the adhesive layer introduces an extra interface, so its thickness and thermal effect should be included in the evaluation (subject to the actual test report).
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