Generally, rigid flex PCBs are used across various industries in applications for which a combination of flexibility, space efficiency, and high reliability is required. Rigid flex PCBs are often seen in aerospace and defense applications, like aircraft instrumentation and military equipment, as well as in the medical industry, where they are utilized in devices like implants and diagnostic equipment. Automotive electronics, industrial machinery and many other applications that demand an adaptable circuitry solution will also use rigid flex PCBs to great effect.
On a more granular level, rigid flex circuit boards are ideal for applications that present challenges to the circuitry during installation or operati...
Generally, rigid flex PCBs are used across various industries in applications for which a combination of flexibility, space efficiency, and high reliability is required. Rigid flex PCBs are often seen in aerospace and defense applications, like aircraft instrumentation and military equipment, as well as in the medical industry, where they are utilized in devices like implants and diagnostic equipment. Automotive electronics, industrial machinery and many other applications that demand an adaptable circuitry solution will also use rigid flex PCBs to great effect.
On a more granular level, rigid flex circuit boards are ideal for applications that present challenges to the circuitry during installation or operation. Flex-to-install applications, in which the circuit is designed to be flexed or bent during the installation process, call for rigid flex PCBs due to the application’s space constraints and/or the need for conformability to irregular shapes. In dynamic flex applications, the circuit will be continuously flexed during operation, so they are specifically designed to withstand and accommodate the ongoing mechanical stress without compromising their electrical performance or reliability. Rigid flex PCBs that follow the manufacturer’s recommended minimum bend radius offer hundreds of thousands of flex cycles without failure.
Applications in high-vibration environments present their own challenges that rigid flex PCBs overcome. Vibration generates mechanical stress that can impact circuits, causing them to flex and bend repeatedly during operation. This dynamic flexing can raise various concerns, including material fatigue, interconnect reliability issues, and component integrity failures.
To mitigate these risks, rigid flex PCBs designed for high-vibration environments are subjected to specific design and manufacturing considerations, like reinforcement to enhance their rigidity and mechanical stability or selecting a material with high flexural strength for their construction.
Finally, rigid flex PCBs are also commonly used in applications that handle high currents and generate heat, like high-speed data communication, industrial equipment or power electronics. Rigid flex PCBs generally have a higher current carrying capacity than rigid boards with flex circuit connections, which makes them a compelling choice for these applications — but that higher capacity comes at a cost.
In a phenomenon known as thermal expansion, the heat generated by a high current passing through a conductive trace or copper plane on a PCB causes the circuit material to expand and contract repeatedly. The flexible sections may undergo stretching or elongation, while the rigid sections experience minimal expansion; when the current stops or decreases, the PCB cools down and contracts. This presents several potential problems for the integrity of the circuit board, including the risks of mechanical stress and fatigue, as well as the risk of electrical performance issues.
But as with rigid flex PCBs designed for high-vibration applications, flex circuit board manufacturers can implement certain design and manufacturing considerations to help mitigate these risks. Choosing materials with good thermal stability and low coefficient of thermal expansion (CTE), implementing thermal management techniques like heat sinks and thermal vias, and optimizing the trace widths, thickness, and copper plane configurations can all help ensure the reliability and long-term performance of rigid flex PCBs in high-heat environments.
