PCB thermal management often involves a combination of design and helper components, such as heatsinks, to handle excess heat.
Carefully selecting and distributing components and testing for thermal shock resilience are ways to improve PCB thermal management.
High power density electronics are particularly difficult to manage thermally because they create a lot of heat very quickly.
PCB Thermal Management
PCB thermal management is a group of strategies designers can use to reduce the amount of heat a PCB generates during normal operation and to reduce the possibility of high heat generation during abnormal operation.
PCB thermal management lowers the chances of physical damage during the normal operation of devices and can improve the integrity of signals that travel through electronics. The more power runs through a PCB, the more thermal management is necessary to make it work well. Every PCB, no matter how complex and no matter its purpose, should have effective thermal management.
PCB Thermal Management Techniques
PCB thermal management is a complex undertaking involving the analysis of components, materials, layouts, spacing, and electrical interference. There is no single answer for how to manage heat in PCBs, and as new types of PCBs are created, it’s reasonable to assume that new guidelines for thermal management may be necessary. However, here are a few suggestions of ways to manage heat in your PCB.
Carefully Select and Distribute Components
Board temperatures should be as low as possible at all times, and many factors can influence changes in temperature. The efficiency of components, spacing of conductive leads, and materials used in the board substrate can all create different baseline board temperatures.
Designers can control the flow of heat in a PCB by distributing components thoughtfully, using conformal coatings, and minimizing thermal barriers. Thermal barriers are areas of a board that hold pockets of heat, like holes and slots. These barriers can be difficult to mitigate with spacing or components like heatsinks, especially if they are negative space.
Test for Thermal Shock Resilience
If a PCB heats up to a high temperature in a very short time, it reaches a state called thermal shock. Thermal shock is dangerous because it can disrupt current flow or cause a PCB to fail completely. Designers should test for thermal shock resilience as part of PCB thermal management. When thermal shock occurs, failures can occur within the board substrate or within the components connected to the board.
A PCB can be designed to meet multiple international standards of thermal shock resilience. Thermal shock resilience may also overlap with thermal cycling resistance, which protects a PCB from failure due to rapid temperature changes. Rapid changes in temperature can weaken component soldering, cause deformations in protective coatings, or cause fractures.
Why is PCB Thermal Management in Some Electronics Difficult?
It is difficult to control heat generation in PCBs with a high power density. This happens because there are many traces drawing power at once and many components that simultaneously rely on a supply of current. A high power density PCB is not necessarily a bad design; some applications require a high power density to perform a variety of functions. Efficient use of space is vital in these situations because any crosstalk can quickly cause thermal spikes.
Some high power density PCBs require large components, which adds another level of complexity to their thermal management. Large components naturally produce more heat, but they also reduce the available surface area on a PCB for the dissipation of that heat. Maintaining enough area on a PCB for heat dissipation is an important part of keeping it cool; packing components together as close as possible to cover a board, even if they all meet IPC standards, could be detrimental.
PCB thermal management is a critical part of PCB design that impacts the physical function and performance of a PCB, so it should be on every designer’s radar. The PCB Design and Analysis overview page at Cadence Design Systems provides tools ideal for analyzing PCB designs, including the Allegro PCB Editor. You can also use InspectAR to accurately assess and improve PCBs using augmented reality and intuitive interaction. Inspecting, debugging, reworking, and assembling PCBs has never been faster or easier.
If you’re looking to learn more about how Cadence has the solution for you, talk to us and our team of experts.