Designing a PCB for Vibration: Component Placement for Durability

It is important to be mindful of component placement and understanding of how they will function together when designing PCBs to meet the demands of high vibration environments (automotive, Industrial & Aerospace). There are many stresses placed on the mechanical structures at the PCB level due to cyclic nature of vibrational forces. If these stresses are not properly mitigated, mechanical failure will occur within components or solder joints due to fatigue, cracks or intermittent failure.

When locating heavier components, such as inductors, large capacitors and connectors, it is best to place them as close as possible to the mounting point or areas of board support. This serves two purposes; reducing the mechanical leverage applied to the components thus reducing stress on the solder joints and keeping these heavier components from being placed in large unsupported areas of the PCB, which have the highest amount of flexure when subjected to vibration forces.

Using low-profile components whenever possible will also reduce the overall amount of inertial (force) produced during vibration for these parts. Sensitive integrated circuits (BGAs and QFNs) should be located within the mechanically stable areas of the PCB and not at the edges or corners of the PCB where bending is most pronounced.

The orientation of the components will also matter. The longer axis of the component should be aligned with the direction of the expected vibrational load. This will reduce the concentration of the stress on the solder joints. By evenly distributing the components you can avoid the imbalanced distribution of mass, which can enhance the vibrations.

For all critical areas you should reinforce these with mechanical support, such as standoffs or additional mounting holes. In addition, you may also want to utilize adhesive, underfill and/or staking compounds when securing connectors and/or larger components to provide additional mechanical stability.

Ensure your PCB thickness and stack-up are appropriate to ensure structural rigidity. Thicker pcbs or multi-layer designs will minimize flex during vibration due to increased strength. Use good soldering techniques and reliable pad design to help improve durability.

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