Thermal Pad
Introduction
A thermal pad is a heat conductive pad or material of a certain thickness that is used to provide heat transfer between two or more solid interface surfaces. These surfaces would otherwise have air gaps which would reduce cooling performance due to air's relatively low thermal conductivity. Thermal pads are commonly used in the electronics industry to aid heat transfer from hot components such as integrated circuits to heat sinks where the heat can be dissipated into the environment.
Composition and Types
Thermal pads are typically made from a filled silicone elastomer material. The fillers are typically ceramic or metallic in nature and are added to the silicone to enhance its thermal conductivity. The silicone elastomer helps to provide the pad with compliance and tackiness, which aids in the interface between the heat source and the heat sink. There are several types of thermal pads available in the market, each with their own unique properties and applications. Some of the common types include:
- Phase Change Material (PCM) Pads: These pads are designed to melt at a certain temperature, filling the air gaps and voids to provide better thermal conductivity. They are commonly used in high performance applications.
- Graphite Pads: These pads are made from a graphite material and are known for their high thermal conductivity and thin profile. They are commonly used in applications where space is a constraint.
- Silicone-Free Pads: These pads are designed for applications where silicone contamination is a concern. They are typically made from a ceramic filled polyimide or polyester material.
Thermal Conductivity
The thermal conductivity of a thermal pad is a key property that determines its effectiveness in transferring heat. It is typically measured in watts per meter-kelvin (W/mK). The higher the thermal conductivity, the better the material is at transferring heat. Most thermal pads have a thermal conductivity in the range of 1 to 10 W/mK, although some specialized pads can have thermal conductivities as high as 20 W/mK or more.
Applications
Thermal pads are widely used in the electronics industry to provide heat transfer between a heat generating component and a heat dissipating component. Some of the common applications include:
- Integrated Circuits (ICs): Thermal pads are commonly used to provide heat transfer from ICs to heat sinks. This helps to prevent the IC from overheating and potentially failing.
- Light Emitting Diodes (LEDs): Thermal pads are used in LED applications to provide heat transfer from the LED chip to the heat sink. This helps to maintain the LED's performance and lifespan.
- Power Transistors: Thermal pads are used in power transistor applications to provide heat transfer from the transistor to the heat sink. This helps to prevent the transistor from overheating and potentially failing.
- Battery Cooling: In electric vehicle applications, thermal pads are used to provide heat transfer from the battery pack to the cooling system. This helps to maintain the battery's performance and lifespan.
Installation and Use
When installing a thermal pad, it is important to ensure that the pad is properly aligned with the heat source and the heat sink. The pad should be cut to the correct size and shape to cover the entire surface area of the heat source. Once the pad is in place, pressure should be applied to ensure good contact between the pad, the heat source, and the heat sink. It is also important to note that thermal pads are typically one-time use only and should be replaced each time the heat source or heat sink is removed.