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 How to choose PCB thermal conductivity for your electrical fabrication?

How to choose PCB thermal conductivity for your electrical fabrication?

Introduction

The PCB thermal conductivity may vary depending on the materials used in their manufacture. Here are some general thermal conductivity ranges for some common PCB materials. including FR4, aluminum, ceramic, and copper.

Other elements that influence  thermal conductivity include the thickness of the board. the presence of vias or other structures, and the specific design of the board. A PCB with increased thermal conductivity can dissipate heat more efficiently. which is beneficial for heat-generating electrical equipment.

 

PCB Thermal Conductivity

The thermal conductivity refers to the ability of a Printed Circuit Board (PCB). To transfer heat from one point to another within the board. It is a measure of how easily heat can flow through the materials that make up the board.

The PCB formula of  thermal conductivity

Thermal conductivity is an important consideration for PCB designers. because electronic devices generate heat during operation. and that heat released to assure dependable functioning and protect the components.

PCBs with high thermal conductivity can efficiently transfer heat away. from the heat-generating components. helping to prevent overheating and prolonging the lifespan of the device.

Thermal conductivity of PCB = (Power dissipated in the board) x (Thermal resistance of the board)

The thermal resistance of the board calculated using the following formula:

Thermal resistance of PCB = (Thickness of the board) / (Thermal conductivity of the board)

It’s worth noting that the thermal conductivity of different PCB substrates. and copper thicknesses can vary widely. so it’s important to use specific values for the materials used in your PCB design.

 

PCB thermal conductivity

 

FR4 PCB Thermal Conductivity

FR4 is a widely used PCB material that consists of a woven fiberglass cloth impregnated with an epoxy resin. The thermal conductivity of FR4 PCBs is relatively low, typically ranging from 0.3 to 0.4 W/mK.

The low thermal conductivity of FR4 PCBs can be a limiting factor in certain applications. as it may not be sufficient to efficiently dissipate heat generated. by the electronic components on the board. To overcome this limitation, designers may use alternative PCB materials . with higher thermal conductivity, such as aluminum or copper.

However, FR4 remains a popular choice for many applications. because of its other properties. such as its high strength, rigidity, and electrical insulation properties. Additionally, some FR4 PCBs designed with specific heat dissipation techniques. such as adding thermal vias or heatsinks, to improve the thermal management of the board.

Aluminum PCB Thermal Conductivity

Aluminum PCBs have a higher thermal conductivity compared to FR4 PCBs. The thermal conductivity of aluminum PCBs typically ranges from 1.0 to 3.0 W/mK, which is higher than that of FR4 PCBs.

multilayer-aluminum-PCB

The higher thermal conductivity of aluminum PCBs makes them a popular choice for applications . that require efficient dissipation of heat generated by the electronic components. This includes applications in power electronics, LED lighting, and automotive electronics, among others.

The thermal conductivity of aluminum PCBs can be further improved . by using thicker aluminum core layers or by adding thermal vias or heatsinks to the board. By optimizing the design and material choices. aluminum PCBs can effectively dissipate heat and prevent overheating of electronic components. which can help to prolong the lifespan and improve the performance of the device.

Thermal Conductivity of Aluminum Nitride PCB 

Aluminum Nitride (AlN) is another material. that is sometimes used for PCBs in applications. where high thermal conductivity is required. AlN has a thermal conductivity ranging from 140 to 320 W/mK. which is significantly higher than that of FR4 or aluminum PCBs. This high thermal conductivity makes AlN a good choice for high-power applications. such as power electronics, where efficient heat dissipation is crucial.

Thermal Conductivity of Ceramic PCB

Ceramic PCBs have higher thermal conductivity compared to traditional FR-4 PCBs. which makes them suitable for high-power applications. that generate a significant amount of heat.

WHAT IS A CERAMIC PCB

The thermal conductivity of ceramic PCBs varies depending on the specific material used. For example, aluminum oxide ceramic PCBs have a thermal conductivity of around 25-30 W/mK. while aluminum nitride (AlN) ceramic PCBs can have a thermal conductivity of up to 170 W/mK.

Thermal Conductivity of Other PCB

Other materials that are sometimes used for PCBs include ceramic materials. such as alumina and beryllium oxide (BeO). which have even higher thermal conductivities than AlN. ranging from 20 to 230 W/mK and 220 to 330 W/mK, respectively. However, BeO is a toxic material that requires special handling. and its use restricted in many countries due to safety concerns.

In general, the choice of PCB material depends on the specific requirements of the application. including the desired thermal conductivity, mechanical strength, and electrical properties. PCB designers must carefully evaluate the properties of different materials. and choose the one that best meets the needs of their application.

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