Panelization Optimize Rigid Flex PCB Processes
Rigid-flex PCBs are a combination of rigid circuit boards and flexible components or modules. The combination of rigid and flexible layers is achieved by using a special insulating layer between the copper-plated pads of the flexible modules or components, and the rigid circuit board. This insulating layer is called the transition zone. Rigid-flex boards require careful design to avoid stress cracking, delamination, and premature failure of the transition zone. Panelization optimizes these processes by reducing costs, speeding up assembly, and increasing product reliability.
Traditionally, the production process for a flex or rigid-flex pcb has been labor intensive, time-consuming, and requires expensive equipment and specialized staff. By implementing the correct panelization techniques, these costs can be significantly reduced, and the quality of the end product will also improve. Panelization involves assembling multiple circuit boards together into an array and using a special fixture to punch individual circuits out of the array. The individual circuits are then separated, soldered and tested as standalone units.
The optimum panel layout for a rigid-flex pcb depends on the needs of the project. For example, the design must consider whether a large number of solder points are required on the board. In such cases, a high-density PCB with blind or buried vias may be needed. This will increase the number of layers and tightens trace width and spacing, making it more difficult to route. However, it will make the connection density higher and allow for a smaller footprint.
How Does Panelization Optimize Rigid Flex PCB Processes?
In addition, the design must consider whether the board will be used in a harsh environment and what kind of bending or fold-over it will be subjected to. This can determine the flex zones in the design, and the layer stack-up must be carefully optimized for both the rigid sections and flex zones. This includes evaluating impedance control, thermal management, and signal integrity for both the rigid and flex sections of the design.
Other design considerations include incorporating breakaway tabs or mousebites into the design to facilitate separation of the individual circuits after assembly. These features are small, connecting bridges between the individual circuits and the panel frame that can be broken or cut to separate the boards. Alternatively, the panel frame can be designed with perforations or holes that are patterned to create weakened lines along which the boards can be separated.
To help ensure that a rigid-flex board can be manufactured at an optimal level, Sierra Circuits recommends collaborating with the manufacturer early in the design process. This will help identify potential issues that might occur during the fabrication process, and resolve them before they become a problem. Working with a trusted supplier will also help reduce costs and improve the quality of the end product. In addition, working with a supplier that designs, manufactures, and assembles under one roof can eliminate the need for a pre-bake cycle, saving money and accelerating the manufacturing process. Lastly, a good panelization design will reduce the number of times the board is handled and exposed to dust and moisture during the assembly and testing phases, further enhancing the quality of the end product.
