Each working component will act as a heat source, and it is unavoidable that the temperature of your board will increase during operation. As a result, you need to have a strategy to remove heat from active components and spread it throughout your circuit board in order to keep your component temperatures within acceptable limits.
Thermal design and simulation software can help you validate your thermal strategy during design time. This requires some knowledge of the thermal properties of your circuit board substrate material and your components.
What are the special techniques of PCB heat dissipation?
Passive heat techniques are the easiest to implement, both from component selection, PCB layout, PCB material selection, and stackup design perspectives.
Learn more about passive thermal management techniques for your circuit board.
- Devices that run at high current will require some particular thermal management strategies that can also be used in board with lower current. Learn more about thermal management for high current circuit boards.
- Thermal design, power integrity, and signal integrity in a circuit board are all intimately related. You can use a simulation-driven workflow to validate your thermal design strategy and ensure that your circuit board temperature stays within acceptable limits.
Pay attention to thermal via arrays
You can turn a PCB into an onboard heat sink by incorporating thermal via arrays over copper-filled areas, as shown above. The idea behind doing so is to have heat flowing from components to the copper area and dissipating through the air from the vias. Usually, thermal via arrays are used for power management modules and components with thermal pads.
When implementing thermal via arrays, remember that it needs to have a reasonably large diameter, in the region of 0.1 mm, for the heat to be dissipated effectively. Also, ensure the vias are not thermal-relief pads but padded holes that are connected to the copper area at all sides. Increasing the number of thermal vias further helps with heat dissipation.
How to reduce heat resistant?
A low thermal resistance ensures that the heat is transferred through the material much faster. This resistance is directly proportional to the length of the thermal path and inversely proportional to the cross-sectional area and thermal conductivity of the thermal path.
Thermal resistance \[\theta = \frac {t}{A \times K}\]
Where
- t is the thickness of the material
- K is the thermal conductivity factor
- A is the cross-sectional area
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