You will find that thermal pads, thermal grease, and thermal tape are used in electronic devices, automobiles, and machinery to aid in heat dissipation. You may be seeking a suitable thermal management solution for your product, yet find it difficult to decide. This article compares the performance, characteristics, and applications of three materials, providing a reference for your consideration.
What is the Thermal Pad？
Thermal pads are solid materials chemically cured by mixing polymer-based resins, thermally conductive fillers, a curing agent, and other additives. They are elastomeric, soft, rubber-like sheets that you can easily place between the surface of a heat-generating component and the surface of its housing or heatsinks, with/without copper heatpipes. They increase the contact area for heat transfer and reduce thermal resistance caused by trapped air gaps. Due to their ease of use and excellent cost-effectiveness, thermal pads are widely used in projects with low- to high-end thermal management requirements.
What is the Thermal Paste？
Thermal paste is also applied to the surface of heat-generating components to help the device achieve superior heat dissipation. However, it is a paste-like substance composed of silicone oil and thermally conductive materials, having a certain degree of fluidity. It requires some technical training to optimize its thermal performance with the support of a printed stencil and scraper. Due to its minimal BLT, it can deliver low thermal impedance between contact surfaces, thereby achieving higher thermal performance.
What is the Thermal Tape？
Thermal tape is a thermal interface material to transfer heat while also providing adhesion and securing components. Typically featuring a double-sided adhesive layer, it offers exceptional holding power and achieves long-term reliability without failure. Thanks to thermal conductive tape, you can secure heat sinks, thermal pads, and components without the need for screws or other fasteners, provided the working temperature is not over 85 degrees C.
Thermal Pad vs. Paste vs. Tape: Composition
Composition of Thermal Pad
Thermal pads are typically manufactured from silicone and thermally conductive fillers. And certain variants utilising graphene to create graphite thermal pads offering exceptionally high thermal conductivity. If your product is sensitive to silicon, silicone free thermal pads are available that do not release silicone oil or evaporate silicone gas. To ensure optimal surface contact with components, thermal pads can be customized in an ultra-soft version, 0-5 Shore 00, with thermal conductivity up to 12 W/m. K. This version is designed to be highly flexible, effectively expelling air from gaps under minimal stress. If your application requires enhanced adhesion, thermal pads can be modified with a laminated adhesive layer to fulfill your mechanical expectations.
Composition of Thermal Paste
Thermal paste is typically formulated from silicone oil and thickening agents, with the addition of thermal conductive materials (such as aluminium oxide, graphene, aluminium nitride, etc.) and stabilisers. This renders it a grease-like thermal material possessing a certain degree of viscous fluidity and stability. Its structure enables you to use it on uneven, contoured surfaces whilst facilitating superior diffusion.
Composition of Thermal Tape
Double-sided thermal tape shares a structure similar to double-sided adhesive tape. It is typically made by spraying thermal coatings on both sides of the fiberglass carrier. Additionally, a top protective liner prevents adhesive failure, such as contamination and oxidation, during transport and storage. Its thermal conductivity is primarily determined by the filler ratio. However, it’s sometimes a paradox. Technically, we can add over 80% filler for the tape materials, but it’ll lose the adhesion performance in adverse conditions. For most cases, we focus more attention on adhesion than thermal performance, so there are very limited performance ranges available for this category.
Thermal Pad vs. Paste vs. Tape: How to Apply
These three thermal interface materials require a clean surface to achieve optimal adhesion and minimise thermal resistance. You should select a suitable cleaning agent for your product and use a soft cloth to remove dust, residual thermal interface material, stains, and other dirt from the surface. Furthermore, before installation, you must disconnect the device’s power supply and implement proper insulation measures to protect both yourself and the components from hazards such as short circuits. Installation procedures vary depending on the specific structure of each material.
How to Apply a Thermal Pad？
Selecting and Trimming Thermal Pads
The installation process for thermal pads is very easy. As they are pre-machined sheets, you need only select the best thermal pads according to your requirements, including thickness, thermal conductivity, and so forth. The pad size plays a critical role in impacting the total thermal performance of the thermal modules. If the pad is way smaller than the chip size, it cannot ensure a good coverage of the heat path, leading to ineffective outcomes. Conversely, a bigger pad size will maintain the same performance and won’t help as much as expected. However, you’ll bear a higher cost in your BOM budgets. Therefore, we will support cutting the thermal pads to the most suitable size and shape according to your specific drawings, or we can suggest a good match based on your mechanical structures in 3D drawings.
Installation
Before using the pads, you should remove the protective film from the surface and press the thermal pad onto the component surface. It is very soft, so you need not apply excessive force to achieve a tight fit. Pressing multiple times will help expel any trapped air more effectively. Subsequently, the casing or heat sink can be mounted on the opposite side of the thermal pad.
Inspect and Secure
In addition to ensuring adequate contact, you must also inspect the thermal pads for misalignment, creasing, or dimensional discrepancies. Alternatively, conduct a professional load test to verify thermal conductivity performance. Should any such issues arise, you should reinstall the pads to prevent diminished thermal performance. As the adhesive properties of thermal pads are insufficient for secure fastening, assembly must be achieved using screws, clamps, or other types of fastening solutions.
How to Apply a Thermal Tape？
Compared to thermal pads, thermal tape is also a pre-formed, ready-to-use tape material in rolls. Therefore, their installation procedures are similar, but thermal tape can serve a securing function, eliminating the need for screw-fastening methods on specific occasions, such as for lightweight and low-temperature applications.
Cutting
The thickness of thermal tape is also fixed at some specific values. You must select it according to the gap dimensions. During application, it’s not a good idea to stack or adhere multiple layers. For a good fit to your mounting requirements, we will follow your drawings and cut out to its dimensions, including pull tabs for ease of assembly and peeling off the protective liners.
Installation
Subsequently, peel off the protective film from one side of the thermal tape, align it, and press it on the surface. Once fully adhered and secured, remove the protective film from the other side before installing the casing or heat sink.
Inspect
Thermal tape provides satisfactory adhesion for your components and heat sinks. Once installed, you need only observe and test whether it functions correctly in transferring heat, without requiring further securing.
How to Apply the Thermal Paste？
Compared to thermal tape and thermal pads, applying thermal paste is a more complex process.
Applying Thermal Paste
Thermal paste is fluid rather than solid. Therefore, you should determine the required quantity based on the manufacturer’s recommendations. When applying, start with a small amount and add more if necessary to prevent overflow and difficult clean-up. You may evenly spread the paste or simply place it on the component surface and allow it to spread naturally.
Installation and Finishing
Air bubbles and trapped air will influence the thermal paste’s heat dissipation performance. Once the paste has fully covered uneven surfaces, press the heat sink or casing onto the paste. Finally, promptly remove any excess thermal paste and secure the assembly with screws.
Thermal Pad vs. Paste vs. Tape: Application Complexity and Repeatability
Application Complexity and Repeatability of Thermal Pad
Thermal pads eliminate the need for metering, application, and curing steps, thereby reducing times. However, they necessitate you to use mechanical fastening with additional components, making them more complex than thermal tape. Provided the thermal pad remains undamaged, free from deformation, and retains satisfactory thermal conductivity, it may be reused. Should the pad incorporate an adhesive layer, it is advisable to replace it with a new one.
Application Complexity and Repeatability of Thermal Paste
The application of thermal paste is highly complex, requiring you to carefully control both the quantity and the technique, whilst also needing the use of screws. Furthermore, it hardens over prolonged use, demanding regular replacement and making cleanup more difficult. Due to the effects of drying and dust accumulation, you’d better not reuse it.
Application Complexity and Repeatability of Thermal Tape
Thermal tape requires no metering or application techniques, nor does it necessitate additional components. Consequently, it offers the simplest solution compared to thermal pads and thermal pastes. However, while its strong adhesive properties eliminate the need for fasteners, they also render removal considerably more challenging. Furthermore, it cannot be reused, as removal can harm both its adhesive strength and thermal conductivity.
Thermal Pad vs. Paste vs. Tape: Adhesion Strength and Tackiness
Adhesion Strength and Tackiness of Thermal Pad
Thanks to the flexibility of thermal pads, they can adhere closely to component surfaces, displacing air in irregularities to achieve superior thermal conductivity. However, as each component can only use one thickness of thermal pad, they can’t provide adequate filling on uneven components or very rough surfaces. Additionally, certain thermal pad models permit you to add an adhesive layer to secure them in place.
Adhesion Strength and Tackiness of Thermal Paste
When you apply thermal paste, it flows across surfaces to fill all grooves. Unlike thermal pads, it avoids the problem of uniform thickness, achieving high conformity even on extremely rough surfaces to enhance heat transfer efficiency. Although thermal pastes contain added binders, their adhesive properties merely help to achieve tighter bonding and can’t withstand the vibrations and impacts encountered during device operation.
Adhesion Strength and Tackiness of Thermal Tape
Similar to thermal pads, thermal tape achieves superior filling on flatter surfaces, minimising thermal resistance. However, it performs less effectively than thermal paste on rough or uneven surfaces. Nevertheless, the double-sided adhesive layer of thermal tape offers high bonding strength, maintaining its effectiveness for you in high-temperature environments (approximately -40 to 120°C) and during prolonged use.
Thermal Pad vs. Paste vs. Tape: Thermal Conductivity
Thermal Conductivity of Thermal Pads
The thermal conductivity of thermal pads must be determined by their specific model. Carbon fibre thermal pads exhibit higher thermal conductivity (up to 50 W/mK), while graphene thermal pads can achieve thermal conductivity as high as 90 W/mK. Compared to thermal tape and thermal paste, their common thermal conductivity is moderate. Your application scenario will also influence their thermal performance. On rough surfaces, even thermal pads with high thermal conductivity struggle to deliver high heat transfer efficiency.
Thermal Conductivity of Thermal Tape
Thermal conductive tape serves dual functions of securing components and transferring heat, though it is not solely dedicated to thermal conduction. The adhesive layer impedes heat transfer, resulting in relatively low thermal conductivity (1–5 W/m·K). It is suitable for your projects with small thermal requirements where lightweight properties are important.
Thermal Conductivity of Thermal Paste
Should you seek enhanced thermal conductivity for equipment with demanding heat dissipation requirements, thermal paste is an ideal solution. On the one hand, its high thermal conductivity ensures more efficient heat transfer. On the other hand, compared to solid-state tapes and gaskets, it minimizes thermal resistance, enabling you to achieve more satisfactory thermal load management.
Thermal Pad vs. Paste vs. Tape: Cost and Lifespan
Cost and Lifespan of Thermal Pads
Thermal pads are typically more expensive than thermal paste and thermal tape, particularly high-performance thermal pads, which may command a significantly higher price. However, despite the higher initial cost, their extended lifespan reduces expenses associated with replacement and maintenance.
Cost and Lifespan of Thermal Tape
Owing to its lower thermal conductivity, thermal tape typically has a lower initial cost. Moreover, it maintains its effectiveness over a long period. Consequently, thermal tape is the preferred choice for applications with modest heat dissipation requirements and budgetary constraints.
Cost and Lifespan of Thermal Paste
Thermal paste’s price is lower than thermal pads yet higher than thermal tape. Moreover, it has superior performance compared to standard thermal pads, making it a cost-effective choice. However, it has a short lifespan and is prone to drying out and hardening during use, needing more frequent replacement (approximately every 1 to 3 years). This may result in higher costs for you over the long term.
Thermal Pad vs. Paste vs. Tape: Application
Applications of Thermal Interface Materials
Firstly, there are various thermal pads with different thermal conductivity ratings and thicknesses for you to suit most component gaps in electronic devices, LED lighting, and industrial machinery. Secondly, unlike thermal paste, they require no frequent replacement and can be used in complex equipment to reduce maintenance needs. However, their use in projects demanding high thermal conductivity results in higher costs. Furthermore, it is not recommended for you to use them on devices with rough component surfaces.
Applications of Thermal Paste
If you are looking for a highly effective thermal interface material for components with complex geometries, thermal paste is a good choice. It not only suits surfaces ranging from flat to intricate, but also offers superior thermal performance compared to thermal pads and thermal tapes. Furthermore, it is particularly well-suited for applications involving small gaps. You may select it for thermal management in CPUs/GPUs, communication equipment, electronic devices, and similar applications.
Applications of Thermal Tape
Thermal tape is better suited for projects that demand high bonding performance, such as displays, mobile phones, and tablets. Opting for thermal conductive tape in portable devices with lower thermal dissipation requirements offers exceptional value. However, it cannot endure the load of applications with high thermal dissipation demands.
Thermal Pad vs. Paste vs. Tape
| Item | Thermal pads | Thermal paste | Thermal tape |
| Form | Preformed solid sheet material | Semi-solid mud-like material | Preformed solid sheet material |
| Ease of use | Easy | Complex | Very easy |
| Repeated use | Yes (without adhesive laminated) | N/A | N/A |
| Thermal conductivity | Low, some models are even higher | Higher | Lower |
| Lifespan | 5-10 years | 12 months | 6-12 months |
| Adhesion strength and tackiness | Adheres to flat surfaces; some models can be customised with an adhesive layer | None | Adheres to flat surfaces with high bonding strength |
| cost | High, with some models commanding a higher price | Low, but requires regular replacement | Lower |
| Application | Rough or Smooth surface | Smooth and rough surfaces, small gaps, high-performance applications | Smooth surface, low thermal dissipation requirements, applications not requiring screw fastening |
FAQs
May I Use Thermal Pads or Thermal Tape of Two Different Thicknesses on the Component Surface?
As splicing may result in loose connections, causing air ingress and increasing thermal resistance, it is better to use a thermal pad or tape. Alternatively, thermal paste should be selected for uneven surfaces to achieve minimum thermal impedance.
Why Use Thermal Interface Materials?
Components generate heat during operation. Failure to dissipate this heat promptly can influence performance or shorten equipment lifespan. Thermal interface materials replace low-thermal-conductivity air to accelerate heat transfer and reduce thermal resistance caused by insufficient contact area, thereby bringing more efficient heat dissipation.
Can Thermal Tape Replace Thermal Pads?
Thermal tape, though also a solid sheet material offering additional fixing abilities, has a lower thermal conductivity and is commonly used in projects involving small heat dissipation loads.
Does Thermal Paste Require Curing?
Thermal paste functions effectively without curing during installation. However, it tends to dry out over long use, and you need to replace it.
Is Thermal Tape Conductive?
Thermal tape is insulating, safeguarding the electrical systems of your equipment and achieving stable operation.
If There is a Bigger Gap between the Component and the Heat Sink, Which Material Should I Use?
Thermal pads offer greater thickness options and can be used for larger gaps. If your component is rough but the gap is less than 0.2mm, you may apply a thicker layer of thermal paste to achieve a minimal BLT.
Final Thoughts
Based on the information in this article, you can select the best solution from thermal pads, thermal adhesives, and thermal pastes. If you require a reliable supplier for your next step, GALLOP INNOTEK has over 10 years of expertise in the TIM and is capable of providing bespoke services, from NPI to product launch.
