rigid flex circuit
Rigid flex circuits are popular for medical imaging equipment, military missile guidance systems, cameras and wearable electronics because they provide excellent durability, reliability and flexibility. However, designing a rigid-flex PCB requires careful consideration to achieve optimal results. Whether your project calls for a single-sided, double-sided or multi-layered board, the steps involved in creating a rigid flex design can be complex. In this blog post, we will explore some of the key steps involved in designing a rigid-flex PCB.
The first step in designing a rigid flex circuits is to review the mechanical requirements of your project. It is important to ensure that the rigid-flex board will fit into your device, and that the bending radius of the board will allow for proper installation. You can check these parameters by constructing a virtual mock-up of your flex-rigid circuit in 3D using a powerful CAD program. This will help you to visualize your flex-rigid circuit in its formed installed configuration, and identify any potential interference issues that may arise.
In addition to reviewing the mechanical criteria of your project, you should also pay attention to the materials used for both the rigid and flex sections of your design. Different materials have varying thermal expansion properties, which can cause mechanical stress and reliability issues during temperature variations. Choosing the right materials can help ensure that your rigid-flex PCB will withstand dynamic and stable bending operations, maintain signal integrity, and control electromagnetic interference (EMI).
What are the steps involved in designing a rigid flex circuit?
Once you have reviewed the mechanical requirements of your project, you should begin to design your traces and components. Considering that the flex circuit will be subject to a high level of strain, it is important to route all traces through the flex area perpendicularly. This will help to prevent them from fracturing or cracking when they are bent. It is also important to use a thicker copper pad when routing through the flex areas, and to include an annular ring around the pads when necessary.
When routing traces, you should always keep in mind that flex processes require larger traces and vias than rigid boards. Additionally, you should use the highest quality copper available for traces and vias to help increase your product’s life cycle. It is also important to remember that a flex process can be more susceptible to corrosion than a rigid process, so it is recommended to use a halogen-free copper material.
Another crucial aspect of a rigid-flex circuit is the choice of stiffeners. There are many types of stiffeners available, including FR4 and polyimide, that can be thermally bonded to the flex and rigid areas of your design. Depending on the type of stiffener, it is important to consider how much flex-to-rigid transition your design will undergo, and how long you will be bending your board for.
The final step in the design process is to prepare your flex-rigid PCB for manufacturing by generating a Gerber file and assembly drawings. By utilizing integrated MCAD and ECAD tools within a single application, you can make it easier to prepare your design for production and to resolve any fit and form or electrical concerns.
