rigid flex boards assembled in complex systems
The complex systems of aerospace and defense, medical devices and automotive electronics use rigid flex boards for their ability to provide flexibility, space efficiency and reliability. However, incorporating rigid flex in your product design requires careful assessment and preparation for the process.
The ability of the rigid flex board to bend, fold or twist allows designers to be more creative in their product designs. This allows for more functionality, increased performance and reduces the overall system cost of a project.
As with rigid boards, a rigid-flex board can contain signal and power layers, as well as copper traces and holes. Adding rigid flex to your design is a simple matter of working with a professional manufacturer that can support the fabrication and assembly of these advanced circuits.
How are rigid flex boards assembled in complex systems?
In addition to meeting dimensional requirements and mechanical specifications, rigid-flex boards require special handling, testing and inspections. In particular, ensuring that the flexible sections of the board can withstand repeated bending and flexing without mechanical failure is crucial for some applications, such as wearables or foldable devices.
This can be achieved by implementing stiffeners around the flex section, and by placing components over the stiffener or rigid area of the board. Fabricators and assembly houses typically prefer to have a rigid-flex circuit supplied in arrays, which helps them to keep the boards stable during assembly.
Incorporating the rigid-flex board in your product design can also help you to save time and money on assembly and shipping costs. Because rigid-flex circuits are often used in conjunction with rigid boards, they are often shipped flat in order to keep the board from warping or folding during transit.
The manufacturing of a rigid-flex circuit begins with the creation of a single or double-sided flex layer, which may start out as laminated or unlaminated PI film, with or without copper. The flex layer is then cladded, which entails depositing and chemically plating copper on the conductive surface of the substrate. Typically, the copper is plated to a minimum of 1 mil in thickness.
Once the flex and rigid sections of the circuit are complete, they are joined together through the use of adhesive layers. Then, the entire assembly is pressed into a routed slot in a backing board (typically MDF, plywood or Teflon), and the flex circuits are cut out using a blanking knife.
As with any specialized PCB, working closely with a rigid-flex circuit fabricator during the design process is key to ensuring success. The IPC-2581 standard, an open, vendor-neutral XML format for exchanging flex and rigid-flex design data with manufacturers, plays an important role in facilitating smooth communication between the two parties. This ensures the transfer of detailed information involving layer stack-ups, drill details and other specifications. In addition, it helps to eliminate misunderstandings and avoid costly errors in the production process. This, in turn, enables quick and accurate turnarounds for the efficient manufacture of a high-quality rigid-flex or rigid-flex PCB.
