Should your product continue to experience overheating or performance degradation despite using thermal pads with adequate thermal conductivity, this may be because the thermal pads are unsuitable for your product. Thermal pads offer convenient installation and diverse options, being commonly used in industries such as electronics and industrial equipment. However, they retain disadvantages including insufficient contact area on complex surfaces and relatively high thermal resistance. In some applications, selecting alternative solutions may prove preferable.
Why Do Thermal Pads Fail to Function?
You can determine whether thermal pads are really unsuitable for your product by identifying common errors in their selection or application. This process helps rule out scenarios where thermal pads fail to function due to other factors, such as incorrect selection or improper installation. Consequently, you can better select alternative products or reuse thermal pads to minimise cost losses.
Thermal Pad too Thin or Too Thick
The thickness of the thermal pad should precisely fill the space between the component and the heat sink (or housing). Failure to do so will result in low thermal efficiency, thereby compromising your product’s performance. If your thermal pad is too thin, it may be unable to effectively cover surface irregularities or gaps on the component, allowing air(which have
extremely low thermal efficiency) to enter. An excessively thick thermal pad increases the thermal transfer path or may fail to fill voids. In either case, you will need to choose right thermal pads or purchase alternative products.
Thermal Pad Stick Error
A thermal pad after application must not have wrinkles, damage, or air bubbles, as these factors increase thermal resistance and reduce the thermal contact area. You should reapply the pad and avoid reuse. Before sticking the thermal pad, thoroughly clean the component, housing, and heat sink surfaces to prevent influence from dust, moisture, or old thermal interface material. Unless precisely cut by the supplier, trim the pad yourself according to the component’s dimensions and shape. Furthermore, thermal pads must not be used concurrently with other thermal interface materials on a single component. In such instances, removal and reapplication suffice without necessitating replacement.
Not Fully Adhered
Thermal pads, compared to liquid materials such as thermal paste, are more rigid and lack fluidity, and thus do not effectively fill rough surfaces. While you can opt for ultra-soft thermal pads to achieve better adhesion, thermal paste still performs better on surfaces with highly complex geometries. Should your components or casing surfaces have significant unevenness, it is advisable for you to select alternatives to thermal pads to achieve more satisfactory heat dissipation and enhance product reliability.
Alternative to Thermal Pads: Thermal Grease
Thermal grease is a liquid material different from thermal pads. Its viscous consistency has a degree of fluidity without vertical flow. This enables superior diffusion across component surfaces and more thorough coverage of minute irregularities. Furthermore, it achieves an exceptionally low bond line thickness (BLT), thereby bringing optimal thermal dissipation performance. For rough surfaces, It is very good for thermal paste to replace thermal pads.
Thermal Grease VS Thermal Pads
- Thermal Performance: Thermal paste has a thermal conductivity of approximately 1–8.5 W/m·K, whilst thermal pads offer a thermal conductivity of roughly 1–20 W/m·K. Although thermal paste generally possesses lower thermal conductivity, it achieves lower thermal resistance and thermal impedanceby maximising thermal contact area. Consequently, both thermal paste and thermal pads can satisfy high thermal loads.
- Suitability for Rough Surfaces: Thermal pads are more suitable for relatively flat surfaces, whereas thermal paste achieves satisfactory adhesion on both flat and rough surfaces.
- Application Complexity: Applying thermal pads is very easy. Whilst the fluidity of thermal paste enhances its heat dissipation capabilities, it also introduces greater complexity to the application process. Additional steps such as metering the paste and applying it manually or automatically are required. However, equipment like screen printing can significantly boost processing efficiency.
- Maintenance and Lifespan: Thermal grease suffers from a shorter lifespan (approximately 12 months) and requires frequent maintenance. If you are selecting thermal interface materials for encapsulated or difficult-to-maintain products, you should consider other alternative solutions to achieve a longer product lifespan.
- Cost: Thermal paste is more cheap, but due to its shorter lifespan, it is not a cost-effective choice in the long term. However, owing to its excellent performance, it offers outstanding value for money.
Alternative to Thermal Pads: Thermal Adhesive
Thermal adhesives serve both thermal dissipation and bonding functions. There are single-component and two-component variants, with the latter need to mix before application. Upon curing at ambient or elevated temperatures, they achieve high mechanical strength and chemical resistance, allowing you to use them in applications requiring protection against impact, vibration, and corrosion to better safeguard components.
Thermal Adhesive VS Thermal Pad
- Thermal Performance: Thermal conductive adhesives have thermal conductivity values of approximately 1~3 W/m·K, while also enabling tighter bonding to minimise contact thermal resistance. Thermal pads offer higher thermal conductivity options for more flat surfaces, meeting the thermal dissipation demands of higher-load applications.
- Adhesive Properties: Whilst certain thermal pad models also support the addition of adhesive layers for enhanced stability, this bonding capability falls short of thermal adhesives. Thermal adhesives achieve a maximum hardness of approximately 70 Shore D upon curing, eliminating the need for additional mechanical fasteners.
- Service Life: Once cured, the thermal adhesive achieves a permanent bond and maintains a long service life. It requires no maintenance after application and is highly suitable for components requiring encapsulation.
Alternative to Thermal Pads: Liquid Metal
Liquid metal thermal interface materials are composed of metal alloys possessing high thermal conductivity (such as gallium, tin, and indium). This renders them more costly, yet offers ultra high thermal conductivity. Being liquid in state, they behave similarly to thermal grease, effectively conforming to surface irregularities to provide extremely low contact thermal resistance.
Liquid Metal VS Thermal Pad
- Safety: Given the high electrical conductivity of metal alloys, when using them in electronic devices, you must consider the insulation problems to prevent risks such as short circuits. Furthermore, liquid gallium alloys corrode aluminium heat sinks, leading to failure. Consequently, you should avoid using it between aluminium radiators and components. Thermal pads are typically insulating and offer silicone-free alternatives, generally presenting a safer option.
- Performance and Cost: Liquid metal has a thermal conductivity of approximately 30~80 W/m·K, surpassing conventional thermal pads. It may be used for heat dissipation in high-performance equipment, such as CPU cooling. However, this entails higher initial and maintenance costs.
- Complexity of Use: Liquid metal demands careful control over application quantity and spreading technique during use, alongside precautions against insulation issues and spillage. Given its limited long-term stability, additional measures such as encapsulation may be required. These factors collectively contribute to a more complex installation process. Therefore, the installation of liquid metal is highly complex.
- Performance and Cost: Liquid metal’s thermal conductivity of approximately 30~80 W/m·K, higher than conventional thermal pads. You may use it for heat dissipation in high-performance equipment, such as CPU cooling. However, this entails higher initial expenditure and maintenance costs.
Alternative to Thermal Pads: Thermal Tape
Should you be seeking an alternative to solid thermal pads, thermal tape may well meet your requirements. Its lower thermal conductivity makes it more right for products with lower heat dissipation demands, whilst also offering a more economical option than thermal pads. Furthermore, thermal tape is typically double-sided adhesive, providing superior retention.
Thermal Conductive Tape VS Thermal Pad
- Adhesive Performance: The double-sided adhesive layer of thermal conductive tape offers better bonding capability and provides a degree of fixation. In certain low-temperature applications, you may even dispense with fasteners such as screws or clamps for securing components. Some thermal pads also support the addition of an adhesive layer.
- Thermal Conductivity: Compared to thermal tape, thermal conductive tape has a lower thermal conductivity, typically ranging between 1 and 5 W/m·K. Consequently, it represents a more cost-effective option for applications with small heat dissipation requirements. Should your product necessitate higher cooling capabilities, this material is not suitable.
- Lifespan: The service life of thermal conductive tape is approximately 6 to 12 months, and factors such as operating temperature may influence this duration. Once degraded, the tape’s performance diminishes or may fail entirely, necessitating prompt replacement. Consequently, it is more suitable for products requiring frequent maintenance.
Alternative to Thermal Pads: Graphite Thermal Sheets
Graphite thermal sheets offer a superior alternative to thermal pads. They are made of natural graphite and achieve rapid heat diffusion and transfer across flat surfaces, offering exceptional thermal efficiency while preventing localised overheating. Being free from silicon compounds, they may be safely applied to silicon-sensitive components.
Graphite Thermal Sheets VS Thermal Pad
- Thermal Performance: Benefiting from graphite’s unique three-dimensional structure, graphite thermal pads rapidly dissipate heat across surfaces. They achieve thermal conductivity of up to 1500 W/m·K in the X-Y plane and approximately 5~15 W/m·K in the Z-direction. They have exceptionally superior heat dissipation and cooling performance compared to conventional thermal pads. Furthermore, graphite thermal pads can be manufactured in minimal thicknesses (0.025~0.5mm) and provide a high degree of flexibility,allowing them to conform seamlessly to complex surfaces.
- Maintenance and Lifespan: Graphite thermal pads contain no silicone-based materials, meaning they will not dry out or weep over prolonged use as conventional thermal pads do. This ensures a longer service life with minimal maintenance requirements.
- Reusability: Graphite thermal pads may be reused if they show no signs of damage or deformation. This is due to their strong thermal conductivity and extended service life. Furthermore, they are equally straightforward to install as thermal pads.
Alternative to Thermal Pads: Phase Change Materials
Phase change materials are typically manufactured as thin sheets under normal conditions, allowing for easy installation within the gap between heating elements and casings or heat sinks. At a specific temperature threshold, they will become liquid., maximising thermal contact area to rapidly reduce component temperatures. This threshold varies by model (typically between 45–60°C), and you can select based on product operating conditions. As temperatures decrease, the material releases stored heat. You may employ this to minimise temperature fluctuations, maintaining your components at a near-constant temperature.
Thermal Pads vs Phase Change Materials
- Thermal Performance: Phase change materials have lower thermal conductivity (approximately 2–8.5 W/m·K) than some types of thermal pads. However, their high latent heat characteristic enables them to achieve excellent heat dissipation efficiency. Moreover, phase change materials transform into a liquid state at elevated temperatures, better compensating for surface irregularities than solid thermal pads, thereby minimising thermal resistance and thermal impedance.
- Maintenance and Lifespan: PBM has strong fatigue resistance, maintaining high efficiency through approximately 27,000 cycles of heat absorption and dissipation. Compared to thermal pastes with shorter lifespans, PBM is less prone to drying out or pumping out, ensuring long-term operational stability.
- Usage Limitations: You should consider more when deciding whether to use phase change materials. Firstly, although phase change materials achieve better heat dissipation performance on rough surfaces compared to thermal pads, its phase transition occurs only within fixed temperature ranges, thereby limiting its application. Furthermore, its optimal operating temperature spans -55 to 125°C, exhibiting lower high-temperature tolerance than thermal pads (approximately -60 to 200°C).
How to Select the Most Suitable Thermal Pad Alternative for Your Application
Thermal Performance Requirements
When selecting the appropriate thermal interface material for your application, it is important to know your product’s thermal load. To achieve better results, you should opt for thermal interface material alternatives with higher thermal conductivity for components that generate more heat. If you are unable to obtain accurate estimates, you may contact suppliers to conduct thermal simulation testing for more specialised value. This can economise the additional costs incurred by making the wrong choice.
Select Based on Product
On the one hand, you need to measure the gap size between the component and the housing or heat sink. Thicker gaps are suitable for thermal paste, thermal adhesive, phase change materials, etc. Thinner gaps are suitable for thermal grease, liquid metal, graphite thermal pads, etc. On the other hand, the surface roughness of the component, housing, and heat sink will also influence your choice. Thermal paste, liquid metal, and phase change materials can better conform to uneven surfaces. Furthermore, different thermal interface materials have different operating temperature ranges. You should consider the product’s usage environment before making your selection.
Maintenance Requirements for Products
Should your product necessitate frequent maintenance, selecting materials such as thermal paste, liquid metal, or thermal tape—which require regular replacement—may be appropriate. If you do not anticipate your product requiring frequent servicing, or if components are encapsulated and difficult to disassemble, graphite sheets or thermal adhesive would be more suitable for your product.
Consider the Budget
High-performance thermal interface materials such as liquid metal and graphite pads may bring higher initial costs. However, the extended service life, ease of installation, and low maintenance requirements of graphite pads render them exceptionally cost-effective. While thermal paste offers lower initial expenditure, it necessitates greater installation and maintenance overheads. You may consider the combined costs of purchase, installation and maintenance to select the solution that best fits your budget.
FAQs
What happens if thermal interface materials are not used?
Without thermal interface materials, the void between components and heat sinks or enclosures filled with air. Air has low thermal conductivity, meaning components can’t efficiently dissipate heat generated during operation, leading to heat accumulation. Consequently, your equipment will reduce performance or even failure when overheating occurs. Prolonged exposure may also adversely affect its service life.
Can I Use Thermal Pads in Combination with Other Thermal Interface Materials?
Thermal interface materials must not be layered. Before installing new material, you should completely remove any residual material from the component surface. You may select the best thermal interface material according to the supplier’s guidance, using only one material per component.
Is Thermal Graphite Pad Conductive?
Thermal graphite pads have higher electrical conductivity. Should you wish to utilize them in electronic products whilst ensuring enhanced safety, you may opt for insulating thermal pastes, thermal tapes, thermal adhesives, etc.
Can Thermal Conductive Adhesives be Reused?
Thermal conductive adhesives undergo irreversible chemical changes after mixing. Once cured, they become very robust, making removal exceedingly difficult. Consequently, they cannot be reused.
Which Thermal Pad Alternative is Most Suitable for High-Volume Processing?
Suppliers offer pre-fabricated sheets and precisely cut phase change materials, graphite thermal pads, thermal tapes, etc., which are also well-suited for high-volume processing. For thermal pastes, thermal adhesives, and similar products, automated dispensing and application equipment can also be employed for efficient processing.
Which Thermal Pad Alternatives Offer Greater Resistance to High Temperatures?
Thermal paste has a wider operating temperature range, typically spanning -50 to 200°C. Should you require a material with superior high-temperature resistance, thermal graphite sheets may be more suitable. These can be used within a temperature range of approximately -40 to 400°C while delivering consistent performance.
Final Thoughts
This article outlines alternatives to thermal pads, such as thermal graphite sheet, thermal paste, and liquid metal, allowing you to know quickly and select a more suitable thermal management solution. GALLOP INNOTEK not only offer a range of high-quality thermal interface materials but also provide personalised guidance. Contact us for bespoke solutions.
