role do thermal vias play in pcb assemblers
Using thermal vias in the right place helps a pcb assembler to prevent hot spots, but it’s only one part of a comprehensive PCB heat dissipation strategy. Other thermal management techniques must be implemented in order to ensure the board can withstand the intended operating conditions.
The high thermal resistance of many pcb assemblers substrates often leads to hot spots accumulating near components that generate significant amounts of heat. These spots are problematic because they cause a large increase in the component temperature, which in turn can shorten the life of the device or lead to failure. Thermal vias are an effective way to transport heat from the surface of a PCB into the inner layers, where it can be dissipated.
When used correctly, thermal vias allow a much higher degree of uniformity in the temperature distribution across the stackup. They do this by providing a path for heat to travel from the heated pad into an internal plane, which is often the ground layer. The greater the distance between the pad and the thermal via, the less impact it has on the pad temperature.
What role do thermal vias play in pcb assemblers?
Thermal vias must be located in close proximity to the heat-generating component. If they are not, the heat will be absorbed in the substrate and transferred to other areas of the PCB, where it can contribute to the overall temperature rise. The best locations for thermal vias are directly below the pads of the heating element.
The size and placement of the thermal vias also play a role in their effectiveness. Ideally, they should be as small in diameter as possible. This reduces their footprint and costs, as well as the number of drill holes on the PCB. Smaller vias are also easier to “tent,” or cover with the solder mask, which protects them from shorts caused by solder migration.
Manufacturers often provide recommendations for the ideal dimensions and spacing of thermal vias. However, these are not universal and must be evaluated on an individual basis. The actual design of the PCB and its construction materials, as well as its thickness and layer number, can have a substantial effect on the validity of these recommendations.
Another important consideration when designing a circuit board with thermal vias is the choice of via-fill material. This can be either conductive or non-conductive, and it’s best to choose a material that closely matches the coefficient of thermal expansion (CTE) of the substrate. This will help the PCB maintain a more uniform temperature throughout its life. Using a PCB simulation tool such as Physics can help you optimize the placement of thermal vias to maximize their utility and minimize their cost. You can import the design status of your PCB, including its layer stackup, schematic, and drilling scheme into Physics to perform a thermal analysis. Then, you can use the results to create a manufacturability report that will inform you of any potential issues with your design.