Rigid-flex Electronic Circuit Board Design Solves Medical Wearables Difficulties

Rigid-flex Electronic Circuit Board Design Solves Medical Wearables Difficulties

The majority of PCB boards these days are basically rigid plates to connect circuitry. Yet, that is changing rapidly; the demand for flexible printed circuit boards (or flexible circuits) is promptly growing mainly because of the engaging wearable device market. Maybe the largest segment of that market is the medical care industry in which wearable devices will be employed to accumulate all varieties of physiological records for medical diagnosis and study, together with individual health use. Presently wearables are offered to track heart rate, blood pressure level, glucose, ECG, muscle movement, and more.


The wearable devices deliver a variety of challenges for circuit board designers that rigid boards don’t. Here are a few of the problems as well as what designers can do to alleviate them.

3D Design

While every single PCB is certainly three-dimensional, flex circuits allow the entire assembly to be bent and folded to conform to the package that the merchandise consumes. The flexible circuitry is folded so the rigid electronic circuit boards easily fit in the item package, taking up small room.
There’s a lot more to the design, therefore, the extra challenges, than simply connecting the rigid boards. Bends should be very well designed so boards get in line where they’re meant to mount, while not placing stress on the connection points. Up Until recently, engineers in fact used “paper doll” models to emulate the circuit board assy. At this time, design tools are offered providing 3D modelling of the rigid-flex assy, helping quicker design and much greater precision.

Small Products and Compacted Circuits

By definition, wearable products need to be small and inconspicuous. In earlier times, a medical “wearable” such as a Holter heartrate monitor contained a pretty big exterior device with a neck strap or belt mount. The recent wearables are small and install straight to the patient with no or few external cables. They obtain an assortment of information and can even process a handful of analyses.

An unobtrusive device affixing directly to the sufferer dictates flexible circuitry and extremely compacted layouts. Furthermore, the board shapes are usually circular or maybe more unconventional shapes, calling for intelligent placement and routing. For this kind of tiny and dense boards, a PCB board tool that is improved for rigid-flex designs helps to make coping with uncommon shapes much simpler.
Stackup Design is necessary

The stackup – the map of the PCB board layers – is vital when you use rigid-flex techniques. If possible, your PCB design software has the capacity to design your stackup including both the rigid and flex parts of the assembly. As mentioned earlier, the layout of the folding area must be built to lower the pressures on the traces and pads.
One of the biggest difficulties with rigid-flex designs is qualifying several producers. After the design is completed, all aspects of the design ought to be communicated to the board fabricator in order that it will be correctly manufactured. Yet, the best practice is to find one or more companies early in the design and collaborate with them to be sure your design fits their fabrication needs as the design goes forward. Working together with manufacturers is made simple by employing standards. In cases like this, IPC-2223 is the vehicle for communicating with your manufacturers.

When the design is done, the data package has to be assembled to hand-off to be made. Whilst Gerber continues to be used for standard PCBs in certain firms, when considering the difficulties of rigid-flex, it is strongly advised by both PCB software tool providers and fabricators that a more intelligent data exchange format be employed. The 2 most sought-after intelligent formats are ODG++ (version 7 or higner) as well as IPC-2581, each of which clearly designate layer specifications.

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