How Do Flex Rigid PCBs Handle Bending and Twisting?
Flex Rigid PCBs Handle Bending and Twisting
Rigid-flex PCBs are used across industries in applications that require a combination of flexibility and space efficiency. They’re found in aerospace and defense equipment, automotive electronics, medical devices, industrial machinery, and more. However, rigid-flex PCBs are not without their challenges. One of the biggest issues is how they handle bending and twisting. This is a critical issue because if the rigid-flex circuit board is not designed correctly, it can lead to malfunction and failure. This is why it’s essential that designers carefully consider the flex rigid pcbs fabrication process before they finalize their design.
The flex rigid pcb manufacturing process begins with a rigid PCB being creased. This is done by placing it in a machine that applies pressure to the backside of the circuit board. This causes the copper to bond to the rigid board, and this helps the circuit board retain its shape after it’s been creased. The creased rigid-flex circuit boards are then assembled into the final product. They’re secured to the product with the use of a pressure-sensitive adhesive, or PSA.
While the flex rigid pcb manufacturing process is relatively simple, there are several factors that must be considered when designing a flex circuit board. Specifically, the transition zone between the rigid and flex sections of the circuit board must be properly designed to prevent stress concentration and possible failure. The transition zone must also be able to handle the thermal expansion and contraction of both the rigid and flex portions of the circuit board. Finally, signal integrity and EMI concerns must be addressed when routing signals to the flexible portion of the circuit board.
How Do Flex Rigid PCBs Handle Bending and Twisting?
To ensure that a flex PCB can bend and twist without breaking, designers must choose a thicker copper thickness than what’s normally used in rigid PCBs. Additionally, the copper must be plated using an air gap technique, and it should have a high dielectric constant. In addition, all through-holes must be plated with up to 1.5 mils. This is necessary because a rigid-flex circuit board’s plated through holes provide mechanical support for the flex section of the circuit board.
Another key factor in ensuring that a flex circuit board can handle bending and twisting is the layout of the traces. To reduce stress points, traces should be routed perpendicular to the bend line. In addition, designers should avoid abrupt changes between wide and narrow traces as these areas are more likely to break due to stress concentration.
Rigid-flex PCBs can be more expensive than rigid PCBs because of their unique design constraints. To help mitigate costs, it’s important that designers carefully consider the rigid-flex manufacturing process before they finalize their design. They can also utilize a rigid-flex cost calculator, like the one available from PCBway, to check how their flex circuit board will fare during production. This will help them determine if it’s an appropriate solution for their application.