Rigid-flex Electronic Circuit Board Design Resolves Wearable Healthcare Product Challenges

The majority of printed circuit boards in the world today are simply inflexible plates to connect circuitry. But, that is changing fast; the need for flex PCB boards (or flexible circuits) is quickly growing mainly because of the burgeoning wearable product industry. Possibly the biggest segment of that market is the healthcare industry in which wearable products will be employed to gather all varieties of physiological information for medical diagnosis and study, together with personal health use. Witout a doubt wearables can be bought to keep tabs on heartrate, blood pressure levels, glucose, ECG, muscle movement, and a lot more.


The wearable devices deliver quite a lot of difficulties for PCB designers that rigid boards do not. Here are several of these problems as well as what designers can do to alleviate them.

Three-dimensional Design

While every single electronic circuit board is certainly three-dimensional, flexible circuits allow the entire assy to be bent and folded to adapt to the package that the merchandise requires. The flexible circuitry is collapsed to ensure the rigid circuit cards fit into the product package, living in minimum room.
There is lots more to the design, hence the increased challenges, than simply connecting the rigid boards. Bends must be properly designed so boards get in line where they’re intended to mount, while not putting stress on the connection points. Up until recently, engineers in fact used “paper doll” models to simulate the circuit card assy. Right away, design tools are obtainable that provide 3D modelling of the rigid-flex assy, helping speedier design and a lot greater accuracy.

Tiny Products and Compacted Circuitry

Obviously, wearable items must be tiny and highly discreet. Up to now, a healthcare “wearable” such as a Holter heartrate monitor integrated a pretty big exterior device with a neck strap or belt mount. The innovative wearables are small and attach straight away to the sufferer with no or few external wires. They gather a wide range of records and are able to even process several analyses.

An unobtrusive device mounting straight to the sufferer demands flex circuitry and incredibly compressed layouts. Moreover, the board shapes are regularly circular or maybe more uncommon shapes, requiring intelligent placement and routing. For this kind of small and densely-packed boards, a PC board tool that’s enhanced for rigid-flex designs can make dealing with strange shapes less of a challenge.

Stackup Design is necessary

The stackup – the map of the PC board layers – is extremely important when using rigid-flex techniques. Preferably, your PCB design software has the power to design your stackup including both the rigid and flexible parts of the assembly. As mentioned earlier, the layout of the folding area must be designed to reduce the pressures on the traces and pads.
One of the primary issues with rigid-flex designs is qualifying several manufacturers. After the design is finished, all aspects of the design have to be communicated to the board fabricator so it will be appropriately manufactured. Yet, the best practice is to choose one or more makers early in the design and collaborate with them to be sure your design satisfies their manufacturing specifications as the design goes forward. Participating with fabricators is made easier by utilizing standards. In this case, IPC-2223 is the vehicle for talking with your fabricators.

In the event the design is finished, the data package needs to be assembled to hand-off to be made. While Gerber still is employed for standard PCBs in some firms, on the subject of the complexities of rigid-flex, it is highly recommended by both PCB program vendors along with manufacturers that a more intelligent data exchange format be employed. The two most popular intelligent formats are ODG++ (version 7 or later) and IPC-2581, as both versions certainly establish layer specifications.