If you own an electronic gadget that folds, flexes, or twists, it most likely contains a rigid-flex PCB. These circuits include most components found in a standard PCB, such as traces, vias, and even parts mounted on a flexible ribbon. However, designing these circuits requires software specifically developed for rigid-flex boards.
As electronic devices become more specialized and complex, industrial systems, complex tools, and various other systems require multiple boards with unique form factors. Creating PCBs for these systems requires software that seamlessly integrates multiple design modalities into a single, intuitive interface. Only design software with an integrated design environment can weave these design tools into a single process and provide the necessary flexibility.
The layout for rigid-flex and multi-board designs are closely linked by a flex ribbon. The only difference between the two designs is the presence or absence of a flex ribbon. Rigid-flex boards use a ribbon, while boards in a multi-board connection use a connector and a cable.
One effective way to create both types of systems is to use a hierarchical schematic design. Functional blocks in the system can be separated into separate schematics, which are then connected using hierarchical schematics. The schematics are organized into “levels”, where each lower level represents a schematic for a different function in the system. This allows for connecting multiple schematics like puzzle pieces within a larger schematic.
When laying out the board, it is important to specify which boards contain different functional blocks in the system. This requires design software with a user-friendly layer stack manager to define the material arrangement in each rigid and flexible part of the PCB.
Dividing functionality onto different boards based on functional blocks also helps in determining the number of layers needed in each rigid and flexible part of the board. This is crucial for reducing production costs by using a smaller number of layers in certain rigid areas of the board.
Once the layers are defined and the flex PCB is ready, various schematics can be captured into different rigid and flexible parts of the board. Routing tools should allow easy routing across the flex ribbon and enable the placement of components in the flex area and routing between signal, power, and ground layers.
The most critical part of rigid-flex design is defining the layer stack in each part of the system. An intuitive layer stackup manager that distinguishes between power, ground, and signal layers is crucial for effective interactive routing.
When defining the rigid and flex areas in the board, schematic capture tools should be used to create a preliminary design in each part of the board. Working with hierarchical schematics should not require a complex folder structure, making it easy to find and reuse existing schematics in new projects.
When a flex area connects directly to a rigid area on the board, a transition zone must be defined between the flex ribbon and the board. The stackup manager should be able to handle this transition zone effectively as part of the design workflow.
Validating the board flex and overall form factor requires 3D visualization tools integrated into the PCB design software, allowing collaboration between the electrical and mechanical design teams within a single program.
Rigid-flex design begins with creating the layer stack for the rigid board, overlays, polyimide layers, and flex ribbon, as well as the link between the different layers. Drawing the board outline should be as intuitive as the tools in any CAD program, and capturing different schematics into different sections of the system should be seamless and straightforward.
When designing multi-board systems with rigid-flex sections, it is important to consult with the manufacturer before specifying the stackup and placing components directly on the flex ribbon. Understanding the capabilities and constraints of the manufacturer’s capabilities is essential for a successful design.
If the manufacturer provides stackup files specifying their requirements, the design software should be able to import and reuse these files, saving time and ensuring that the board meets the manufacturer’s capabilities.
As electronic devices become more specialized and complex, industrial systems, complex tools, and various other systems require multiple boards with unique form factors. Creating PCBs for these systems requires software that seamlessly integrates multiple design modalities into a single, intuitive interface. Only design software with an integrated design environment can weave these design tools into a single process and provide the necessary flexibility.
The layout for rigid-flex and multi-board designs are closely linked by a flex ribbon. The only difference between the two designs is the presence or absence of a flex ribbon. Rigid-flex boards use a ribbon, while boards in a multi-board connection use a connector and a cable.
One effective way to create both types of systems is to use a hierarchical schematic design. Functional blocks in the system can be separated into separate schematics, which are then connected using hierarchical schematics. The schematics are organized into “levels”, where each lower level represents a schematic for a different function in the system. This allows for connecting multiple schematics like puzzle pieces within a larger schematic.
When laying out the board, it is important to specify which boards contain different functional blocks in the system. This requires design software with a user-friendly layer stack manager to define the material arrangement in each rigid and flexible part of the PCB.
Dividing functionality onto different boards based on functional blocks also helps in determining the number of layers needed in each rigid and flexible part of the board. This is crucial for reducing production costs by using a smaller number of layers in certain rigid areas of the board.
Once the layers are defined and the flex PCB is ready, various schematics can be captured into different rigid and flexible parts of the board. Routing tools should allow easy routing across the flex ribbon and enable the placement of components in the flex area and routing between signal, power, and ground layers.
The most critical part of rigid-flex design is defining the layer stack in each part of the system. An intuitive layer stackup manager that distinguishes between power, ground, and signal layers is crucial for effective interactive routing.
When defining the rigid and flex areas in the board, schematic capture tools should be used to create a preliminary design in each part of the board. Working with hierarchical schematics should not require a complex folder structure, making it easy to find and reuse existing schematics in new projects.
When a flex area connects directly to a rigid area on the board, a transition zone must be defined between the flex ribbon and the board. The stackup manager should be able to handle this transition zone effectively as part of the design workflow.
Validating the board flex and overall form factor requires 3D visualization tools integrated into the PCB design software, allowing collaboration between the electrical and mechanical design teams within a single program.
Rigid-flex design begins with creating the layer stack for the rigid board, overlays, polyimide layers, and flex ribbon, as well as the link between the different layers. Drawing the board outline should be as intuitive as the tools in any CAD program, and capturing different schematics into different sections of the system should be seamless and straightforward.
When designing multi-board systems with rigid-flex sections, it is important to consult with the manufacturer before specifying the stackup and placing components directly on the flex ribbon. Understanding the capabilities and constraints of the manufacturer’s capabilities is essential for a successful design.
If the manufacturer provides stackup files specifying their requirements, the design software should be able to import and reuse these files, saving time and ensuring that the board meets the manufacturer’s capabilities.
