Thermal Pad
Thermal Gap Pad Selection Guide: Thickness, Hardness, Thermal Conductivity and Product Series
Thermal Pad Selection Guide
Thermal gap pad selection must account for gap size, thickness, hardness, compression ratio, thermal resistance, electrical insulation, handling and operating conditions.
The right material can conform to the heat source and heat sink, reducing interface thermal resistance without placing excessive stress on the component.
Check the Gap and Fill Area
Measure the minimum and maximum gaps between the heat-generating component and heat sink. Include component height differences, PCB warpage and assembly tolerances in the assessment.
- Minimum and maximum gap
- Component height differences
- Positive and negative mechanical tolerances
- Expected compression after assembly
Choosing thickness from the nominal gap alone may overlook production tolerances. Some areas may lose contact, while excessive compression may increase stress on components.
Choose the Right Thickness
The pad must be thick enough to fill the gap and maintain full contact after compression, without adding unnecessary distance to the heat-transfer path.
- Uncompressed thickness
- Actual gap size
- Compressed thickness
- Mechanical tolerance range
A thicker pad is not necessarily safer. Excess thickness may increase thermal resistance, assembly pressure and lateral deformation.
Assess Hardness and Compression
Pad hardness affects conformity, compression, handling and the mechanical stress placed on the PCB and components.
- Maximum pressure the PCB and components can withstand
- Required compression ratio
- Contact-surface unevenness
- Clamping pressure and its uniformity
Softer pads can accommodate tolerances and reduce assembly stress. If too soft, however, they may be harder to pick up, position or place automatically. Choose according to the process conditions.
Compare Conductivity and Resistance
Thermal conductivity describes the material’s ability to conduct heat. Actual cooling performance also depends on thickness, compression, contact area and how well the surfaces conform.
- Thermal conductivity
- Thickness in use
- Contact after compression
- Thermal resistance at different pressures
Higher thermal conductivity does not always produce better cooling in the device. A pad that is too hard, too thick or poorly conformed may perform worse than a lower-conductivity material with better contact.
Check Electrical Insulation
When a thermal gap pad sits between an electronic component and a metal heat sink, confirm its electrical isolation capability against the equipment’s operating voltage and safety requirements.
- Dielectric breakdown voltage
- Volume resistivity
- Surface resistivity
- Material thickness
Do not judge insulation by appearance or feel alone. Check the electrical properties of wave-absorbing, graphite and other specialized composite materials separately.
Assess Form and Handling
Tack, reinforcement, toughness and release-liner design affect cutting, pick-and-place, installation and later rework.
- Sheet stock or custom die-cut shapes
- One-sided, two-sided or no tack
- Glass-fiber reinforcement
- High-toughness construction
- Release liner and pull-tab design
- Manual or automated placement
More tack is not always better. It helps positioning, but may complicate rework and cause tearing or residue during removal.
Assess Environment and Reliability
Under the actual temperature, humidity, pressure, vibration and service-life conditions, the pad must maintain its thermal performance, dimensions and compression behavior.
- Prolonged high temperature
- Thermal cycling
- High temperature and humidity
- Continuous compression
- Vibration and shock
- Compression set
- Change in thermal resistance after aging
The maximum operating temperature is only a starting point. Confirm performance after prolonged aging, thermal cycling and continuous compression.
Check Special Requirements
Beyond heat transfer and gap filling, some equipment requires non-silicone materials, low outgassing, electromagnetic-wave absorption, low weight or coolant compatibility.
- Proximity to optical components or precision contacts
- Use in a vacuum or sealed environment
- Need to absorb electromagnetic interference
- Weight limits
- Contact with immersion-cooling fluid
- Need to reduce oil bleed and contamination
Do not infer special properties from a product name alone. Non-silicone does not necessarily meet a low-outgassing requirement, and low-bleed does not mean zero oil bleed. Confirm with test data.
Special Requirements
| Application | Suggested property |
|---|---|
| Optical lenses, precision contacts | non-silicone, low outgassing |
| Radar, 5G and millimeter-wave equipment | thermally conductive wave absorption |
| Satellites, drones and mobile devices | lightweight, low density |
| High-voltage and power modules | electrical insulation |
| Sealed equipment and clean appearance | Low Oil Bleed |
| Single-phase immersion-cooling equipment | coolant compatibility |
Validate Samples in the Device
Datasheets support initial screening. Final selection still requires testing in the actual equipment at the intended thickness, clamping pressure and operating conditions.
- Actual component temperature rise
- Hotspot location
- Degree of PCB bending
- Pad compression and displacement
- Thermal resistance after cycling
- Material condition after disassembly
- Oil bleed, swelling or contamination
- Stability during prolonged operation
Make sample testing as close to production conditions as possible, including pad dimensions, die-cutting method, clamping pressure and environment. This helps avoid a mismatch between laboratory and production results.
Quick Selection Guide
| Need | Series |
|---|---|
| High power, lower thermal resistance | High Thermal Conductive Pad |
| General gap filling, broad specification choice | General-Purpose Gap Pads |
| Very small gaps and slim designs | Ultra-Thin Gap Pads |
| Lower stress on PCBs and components | Ultra-Soft Gap Pads |
| Complex die-cutting and automated handling | High-Toughness Gap Pads |
| Less oil bleed and visible contamination | Low-Bleed Gap Pads |
| Large sizes, die-cutting and dimensional stability | Glass-Fiber-Reinforced Gap Pads |
| Prolonged operation in coolant | Single-Phase Immersion-Cooling-Compatible Gap Pads |
Find the Right Thermal Gap Pad
Designed for high-power chips, power modules and equipment with high heat flux. A highly conductive formulation and good compressibility fill contact gaps, reduce interface thermal resistance and transfer heat from components to the heat sink.
High conductivity
transfers heat from high-power components.
Lower thermal resistance
reduces interface gaps and contact resistance.
Compressive conformity
fills small surface irregularities.
Electrical isolation
conducts heat while providing insulation.
Custom processing
supports tailored thicknesses, sizes and shapes.
AI Servers
high-end processors
Power supplies
power modules
5G base stations
high-speed storage equipment
Available in a range of thermal-conductivity grades, hardnesses and thicknesses. Flexibility, compressibility, inherent tack and electrical insulation help accommodate mechanical tolerances in many consumer and industrial electronic devices.
Broad specification range
multiple thicknesses, hardnesses and conductivity grades.
Tolerance compensation
accommodates component height and mechanical variation.
Inherent tack
aids attachment and positioning.
Stable insulation
combines heat transfer with electrical isolation.
Custom die-cutting
supports holes, cuts and custom shapes.
consumer electronics
displays and panels
networking equipment
Power modules
storage equipment
industrial control equipment
Designed for very small gaps and slim assemblies. The thin structure shortens the heat-transfer path while providing low thermal resistance, compressive strength and electrical isolation for high-power components in limited space.
Ultra-thin design
suits very small gaps and slim devices.
Shorter thermal path
reduces the distance from component to heat sink.
Lower thermal resistance
improves heat transfer across thin interfaces.
Compressive stability
maintains strength in a thin structure.
Electrical isolation
separates components from metal cooling structures.
ultra-thin laptops
Mobile devices
optical modules
compact communication modules
high-density PCBs
slim power modules
Low hardness and high resilience help the pad conform to components and heat sinks under lower assembly pressure. It accommodates height variation and reduces the risk of PCB bending, chip stress and damage to fragile components.
Very low hardness
conforms under low pressure.
Lower stress
reduces assembly load on chips and PCBs.
High compressibility
accommodates larger gaps and height variation.
Stable recovery
maintains contact after compression.
Electrical isolation
combines soft heat transfer with insulation.
thin PCBs
large-area chips
fragile optical components
display panels
precision sensor modules
equipment with low clamping pressure
High toughness and stretchability improve durability during cutting, handling and assembly. Narrow strips, openings and irregular shapes are less likely to tear or deform, making these pads suitable for automated processes and applications requiring rework.
Tear resistance
reduces damage during handling and assembly.
Shape stability
suits complex outlines and narrow die cuts.
Easier handling
supports automated pickup and accurate placement.
Rework durability
resists tearing and deformation during repeated removal.
Cushioning
absorbs vibration, shock and mechanical tolerances.
automated placement processes
narrow heat-transfer areas
complex cutout structures
large pads
equipment requiring rework or repair
high-vibration electronic modules
Designed to reduce oil bleed under prolonged compression and high temperatures. Less silicone oil migration helps limit dust pickup, electronic-component contamination and visible staining while retaining heat transfer, flexibility and electrical insulation.
Less oil bleed
reduces migration under prolonged compression.
Less contamination
lowers the risk of oil-film contamination.
Cleaner surfaces
reduces dust adhesion and visible soiling.
Long-term stability
maintains thermal performance under continuous compression.
Electrical isolation
combines heat transfer, compressibility and insulation.
precision electronics
products with visible surfaces
sealed modules
automotive electronics
modules near optical components
equipment in continuous operation
A glass-fiber reinforcement layer improves dimensional stability and handling strength. It reduces stretching during pickup, die-cutting and assembly, making the material suitable for large sheets, complex shapes and automated processes.
Glass-fiber reinforcement
improves structural strength and durability.
Rework durability
resists tearing and deformation during repeated removal.
Die-cutting flexibility
suits large parts, openings and complex shapes.
Stable placement
improves automated handling and positioning accuracy.
Thermal and electrical performance
transfers heat while providing isolation.
large-area heat sinks
automated placement
Power supplies
industrial computers
complex cutout structures
Communication Equipment
Designed for single-phase immersion cooling, these pads maintain their structure and thermal performance during prolonged exposure to coolant. They serve as thermal interfaces for high-power components such as GPUs, AI accelerators and ASICs.
Coolant compatibility
suits single-phase immersion-cooling environments.
Immersion stability
retains material structure during long-term exposure.
Stable heat transfer
retains thermal performance after immersion.
High-power applications
suits GPUs and high-power chips.
Environmental durability
supports prolonged operation in demanding conditions.
AI GPU servers
AI accelerators
ASIC computing modules
high-performance computing platforms
single-phase immersion-cooled data centers
cold-plate cooling modules
Thermal Gap Pad Installation
Clean the surfaces
Clean the component and heat-sink surfaces.
Remove the bottom liner
Peel off the first release liner.
Align and place
Position the pad at the installation site.
Remove the top liner
Peel off the upper release liner.
Apply even pressure
Install the heat sink and apply pressure evenly.
Note: Avoid stretching, folding or contaminating the pad during installation. Tighten evenly to the product’s recommended compression ratio. Too little compression can impair contact; too much can stress components and deform the material.
Feature Overview
Non-Silicone
Reduce Siloxane Outgassing and Contact Contamination
Evaluate material outgassing, condensable substances and water-vapor regain to reduce the risk of contaminating lenses, sensors and precision components in vacuum or sealed environments.
Low Outgassing
For Vacuum and High-Cleanliness Applications
The stable formulation is designed to limit oil migration and volatile emissions, helping reduce contamination of nearby components and improve long-term equipment reliability.
Reliability
Stable Under Heat and Thermal Cycling
Suited to prolonged high-temperature operation and thermal cycling. It helps reduce material softening, degradation, displacement and increases in thermal resistance, maintaining contact and heat-transfer reliability.
Immersion-Cooling Compatible
Retain Structure and Heat Transfer in Coolant
Designed for immersion compatibility, the material maintains its dimensions, structure and thermal performance during prolonged exposure to single-phase immersion-cooling fluid. It is suited to AI servers and high-performance computing platforms.
Electrical Insulation
Heat Transfer with Electrical Isolation
High volume resistivity and dielectric breakdown voltage provide electrical isolation between components and metal heat sinks, suiting power devices and high-voltage electronic modules.
Wave Absorption
Manage Heat and Electromagnetic Interference
Sheet-form material combines heat conduction with electromagnetic-wave absorption to help reduce signal interference across frequency bands and address hotspots. It suits millimeter-wave, terahertz, radar and communications equipment.
Lightweight
Lower Weight, Maintain Heat Transfer
Low-density materials reduce the weight of thermal-management structures while balancing cooling performance and weight limits. They suit satellites, drones and portable electronic equipment.
Thermal Pad Selection FAQs
How do thermal gap pads differ from liquid gap fillers?
Thermal gap pads are preformed sheets whose thickness and shape are easy to control. They can be applied or replaced directly and suit clean, fast assembly. Liquid gap fillers conform to complex surfaces and larger tolerances and are better suited to automated dispensing, but dispensing volume, curing and other process conditions must be controlled.
Does higher thermal conductivity always mean better cooling?
Not necessarily. Actual performance also depends on pad thickness, compression, contact area, surface flatness and interface thermal resistance. A highly conductive pad that is too thick, too hard or poorly conformed may perform worse than a lower-rated material with better contact.
How should I choose pad thickness?
Measure the minimum and maximum gaps and account for mechanical tolerances. Choose a thickness that maintains full contact after compression. A pad that is too thin leaves gaps; one that is too thick may increase thermal resistance and assembly pressure.
Is a softer pad always better?
No. Ultra-soft materials can reduce assembly stress and accommodate tolerances, but may be harder to handle, more prone to displacement or less suitable for automated assembly. Select hardness according to component pressure limits, pad area and assembly method.
When should I choose a glass-fiber-reinforced pad?
For large pads, complex shapes, narrow cuts, automated handling or repeated rework, the reinforcement layer improves dimensional stability and reduces stretching, tearing and deformation during assembly.