Rigid-flex PC Board Design Fixes Wearable Healthcare Gadget Complications

The majority of PCB boards nowadays are merely rigid plates for connecting circuitry. Nevertheless, that’s changing fast; the interest in flexible PC boards (or flex circuits) is quickly raising largely caused by the booming wearable device industry. Maybe the biggest segment of that market is the healthcare industry in which wearable devices will be utilized to collect all varieties of bodily data for prognosis and study, and personal health use. Undoubtedly wearables can be obtained to track heartrate, blood pressure levels, glucose, ECG, muscle movement, and more.

The wearable devices present quite a few complications for PCB designers that rigid boards don’t. Here are a couple of those problems as well as what designers can do to alleviate them.


3-D Design

While each PCB board is certainly three-dimensional, flexible circuits enable the entire assy to be bent and folded to adapt to the package that the merchandise takes up. The flexible circuitry is collapsed to ensure that the rigid printed circuit boards fit into the product package, living in minimal room.

There is a lot more to the design, hence the increased challenges, than only connecting the rigid boards. Bends have to be exactly designed so boards get in line where they’re intended to mount, while not placing stress on the connection points. Up to recently, engineers actually used “paper doll” models to emulate the PCB board assembly. Currently, design tools are available that provide 3D modelling of the rigid-flex assembly, permitting more rapidly design and far greater precision.

Small Products and Squeezed Circuits

Obviously, wearable products need to be small and highly discreet. During the past, a medical “wearable” maybe a Holter pulse rate monitor contained a pretty big external device with a neck strap or perhaps belt mount. The new wearables are tiny and install right to the patient with no or very few external wires. They get a range of data and are able to even process some analyses.

An inconspicuous device affixing right to the sufferer requires flexible circuitry and extremely dense layouts. In addition to that, the board shapes in many cases are round or maybe more uncommon shapes, requesting creative placement and routing. For such small and dense boards, a PC board tool which is enhanced for rigid-flex designs helps to make addressing odd shapes a lot less difficult.

Stackup Design is Vital

The stackup – the map of the Electronic Circuit Board layers – is extremely important when working with rigid-flex techniques. Preferably, your PCB design software has the capacity to design your stackup including both the rigid and flexible parts of the assembly. As mentioned previously, the layout of the folding area needs to be made to minimize the pressures on the traces and pads.
One of the biggest problems with rigid-flex designs is qualifying multiple producers. After the design is done, all aspects of the design has to be communicated to the board fabricator therefore it will be properly made. However, the best practice is to select one or more companies at the start of the design and team up with them to make sure that your design satisfies their production requirements as the design improves. Participating with fabricators is made simple by employing standards. In such cases, IPC-2223 is the vehicle for making contact with your fabricators.

The moment the design is completed, the data package has to be assembled to hand-off to be manufactured. Even though Gerber still is employed for standard PCBs in a few firms, when it comes to the complications of rigid-flex, it is strongly advised by both PCB software program providers as well as manufacturers that a more intelligent data exchange format be employed. The two most famous intelligent formats are ODG++ (version 7 or later) and also IPC-2581, because both versions obviously indicate layer standards.


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