Validate Rigid Flex PCB Designs with Onshape and Altium 365

Rigid-flex boards are showing up in more products every year, from wearables and medical devices to drones, robots, and aerospace hardware, because folding a board into a tight space eliminates the connectors and cables that would otherwise tie separate boards together.

That same folding is what makes them hard to get right. A rigid-flex board is fabricated flat and installed folded, and the folded shape is where fit problems live. A flex tail that looks fine in layout can rub against a housing edge, and a component that clears everything on the flat board can collide with a boss once the rigid sections stack.

Rigid-flex fabrication is expensive and slow, so finding one of these problems at the prototype stage costs real time and money.

Onshape PCB Studio now imports rigid-flex boards from Altium 365 with their bends intact.

Mechanical engineers can place the folded board directly into the enclosure assembly and check fit against the actual bend geometry, while ECAD engineers keep ownership of the board design in Altium. Both teams work from the same data through the Onshape Altium Connector, and every change is tracked in Onshape’s built-in version history.

Why the Rigid-Flex Workflow Starts in Altium

The workflow starts in Altium because that’s where the board’s flexibility is defined. The rigid and flex regions come from the layer stackup, and details like flex layer count, copper weight, and stiffener placement determine where the board can bend and how tightly. ECAD tools also treat the flattened board as the master definition, since that’s what the fab shop builds, so it makes sense for the folded shape to be derived from it.

In Altium Designer, the ECAD engineer sets up the rigid and flex stackups, assigns them to board regions, and adds bending lines to the flex regions with a fold sequence. One rigid region gets locked in 3D, so Altium has a fixed reference to fold around, and the Fold State slider lets the designer preview the folded board before saving the project to Altium 365.

Importing a Rigid-Flex Board into Onshape PCB Studio

From there, the mechanical engineer opens a PCB Studio tab in Onshape, chooses Import from Altium 365, and selects the workspace, project, and variation. The board comes in with its copper, solder mask, and silkscreen decals, along with the 3D component models from the Altium library.

When you sync it to Onshape, PCB Studio builds a Part Studio and an Assembly just as it does for any board, but for rigid-flex, it also creates Flattened and Folded configurations in both. It places Mate connectors on components mounted to flex zones and between the flex zones themselves, so those components move with the board as it folds, and it fixes the board part in the Assembly by default, so nothing drifts out of alignment while you work.

Checking Folded Fit and Clearance in the Enclosure

With the Folded configuration inserted into the product assembly, you can run interference detection, section through the bends, and measure how close the flex tail gets to the housing wall.

These are the problems that tend to stay hidden until a prototype shows up, like a tall capacitor that clears everything on the flat board and then lands on a boss once the rigid sections stack.

When you need the board as it will be fabricated, for stiffener placement or fixture design, you switch to Flattened, and it's still the same board with the same version history.

Sending Changes Back to Altium 365

If the enclosure calls for a change, such as moving a connector or trimming the outline, you make it in Onshape, sync it back to PCB Studio, and push the board to Altium 365 with a note explaining what changed.

The ECAD engineer reviews the edit in Altium, accepts or rejects it, makes any electrical changes of their own, and pushes the board back.

A pull in PCB Studio brings those updates into Onshape, and the two sides can go back and forth this way until the board is final. Board outline and component positions travel in both directions, while copper and silkscreen come from Altium into Onshape only.

Rigid Flex Support for Cadence Allegro via IDX 4.0

Teams using Cadence Allegro or other ECAD tools get the same rigid-flex handling through IDX 4.0.

Importing an IDX file into PCB Studio builds the Part Studio, Assembly, Mate connectors, and Flattened and Folded configurations automatically, and when the mechanical work is done, you can export back to IDX 4.0, keeping IDX extended checked for the best compatibility with third-party tools.

Reference designators carry through in both directions. If the enclosure is driving the board shape early in a project, you can also start the rigid-flex layout in Onshape with the Flex PCB model features and hand it to any ECAD system that supports IDX 4.0.

A few details are worth knowing before you start. Decals don’t display on bend regions after syncing, keep-in and keep-out areas aren’t tied to the folding regions automatically and may need to be mated by hand, and flex zones can occasionally export from Onshape as rigid in IDX, so validate every export before it goes to production.

The Altium 365 Integration and Rigid-flex PCB pages in Onshape’s Help Documentation cover the full setup.

What This Means for Your Hardware Team

The payoff shows up in the prototype schedule. When the mechanical engineer can check the folded board against the real enclosure while the layout is still changing, fit problems get resolved in a design review instead of on the bench, and fewer expensive rigid-flex spins go out the door.

The ECAD engineer keeps control of the stackup and bend definitions in Altium, the mechanical engineer works with accurate geometry instead of an approximation, and the changes that pass between them are visible and reviewable on both sides.

Because Onshape runs in the browser, there’s nothing to install on the mechanical side, and everyone on the project, from the enclosure designer to the manufacturing engineer planning fixtures, can open the same board in whichever state they need.

Whether your team designs in Altium, Allegro, or another IDX-capable tool, the folded board and the flat board now live in the same place as the rest of the product.