Flex PCBs Handle Prolonged Exposure to Vibration
Whether used in hearing aids or heart monitors, PCBs must be durable to stand up to repeated bending and flexing. This flexibility allows them to mimic the shape of the body, allowing them to fit where rigid devices cannot. They are also able to handle harsh environmental conditions, such as extreme temperatures and vibrations. This reliability makes flex PCBs well suited for aerospace applications, as they are more likely to survive longer exposure to vibration than rigid boards.
To make a flexible PCB, copper conductors are placed on the surface of an adhesive-based insulator film. This is typically Polyimide, although other materials are available. The conductors are then plated with copper through holes (PTH) and soldered in place using an etch and drill process similar to that used on rigid PCBs. The resulting PCB is then laminated with an adhesive-based coverlay, which provides insulation and protects the circuit from damage and corrosion. Stiffeners are sometimes added to the flex PCB, which helps it hold its shape during bending, insertion, and soldering.
Single-layer flex pcbs can be constructed from PI, PET, or thin flexible-epoxy and glass fiber cores. These are layered with a layer of copper and an epoxy, tin, or silver ink. In order to get the desired level of flexibility, it is important to ensure the flex area has a large enough bend radius. This will prevent the copper from fatigue and cracking during repeated flexing.
How Do Flex PCBs Handle Prolonged Exposure to Vibration?
When designing a flex PCB, the number of layers should be kept to a minimum. A high layer count will add to the cost of production due to the extra time and material that is required to laminate each section. Additionally, multiple surface finishes can increase costs by requiring more complex and slower plating and assembly processes.
The key to success with a flex or rigid-flex PCB is working closely with an experienced manufacturer. They can provide insight into the advantages and disadvantages of each type of board, helping you balance cost and functionality to meet your needs. Additionally, they can help you understand environmental factors that can impact the performance of your product and suggest mitigation strategies.
Both flex and rigid-flex PCBs can suffer from damage as a result of prolonged exposure to vibration. However, careful design and material selection can mitigate these issues. For example, choosing a laminate with good resistance to humidity and tears will reduce the likelihood of premature failure in harsh environments. Signal integrity and impedance mismatches can also be impacted by repeated bending, but careful design and tight control of the flex area’s bend radius can mitigate these problems.
In addition, selecting an upgraded PI film can improve resistance to humidity and tear damage. Finally, minimizing the number of layers can improve signal integrity and reduce the chance of erroneous terminations. By collaborating with an experienced PCB manufacturer, you can be confident that your flex or rigid-flex circuit will perform in harsh environmental conditions. This will ensure long-term reliability and performance.
