Background Theory > PCB Design > How to avoid Avoid Mechanical Stress in PCBs

Mechanical stress can lead to various issues in PCBs, including fractured traces, delamination, cracked solder joints, and damaged components. Thus, it is crucial to design and handle PCBs in a way that minimizes mechanical stress. Here are several ways to avoid mechanical stress in PCBs:

Component Placement

Avoid placing components near the edges of the board, as these areas are more likely to be exposed to mechanical stress. Similarly, components should not be placed near holes or slots on the board.

Support Heavy Components

Heavy components, like transformers or large capacitors, can cause the board to bend or warp under their weight. If possible, these components should be supported with additional hardware to distribute their weight more evenly.

Avoid Sharp Corners

Sharp corners in the board layout are more likely to crack under stress. Using rounded corners can help distribute stress more evenly.

Consider Thermal Expansion

Different materials on a PCB expand at different rates when heated. This differential thermal expansion can lead to mechanical stress. Choose materials with similar thermal expansion coefficients and design your board with thermal management in mind.

Proper Handling and Assembly

Mechanical stress can also be introduced during the assembly and handling of the PCB. Be sure to handle boards carefully, and consider using fixtures during assembly to prevent bending or warping of the board.

Vibration and Shock

Consideration should be given to the environment in which the PCB will operate. If the board is likely to be exposed to vibration or shock, use mounting hardware that can absorb some of these forces, and consider using components that are rated for such environments.

Proper De-panelization Methods

PCBs are typically manufactured in panels that contain multiple boards. The process of separating, or de-panelizing, these boards can introduce mechanical stress. Use methods that minimize this, such as routing, laser cutting, or V-scoring.

Designing for Uniform Copper Distribution

Uneven copper distribution can lead to board warping during the heat cycles of manufacturing or during operation. Try to keep copper distribution as uniform as possible.

In conclusion, avoiding mechanical stress in PCBs requires thoughtful design and careful handling. By considering potential sources of stress in the design stage and addressing them proactively, you can significantly increase the reliability and lifespan of your PCBs.