Rigid-flex Electronic Circuit Board Design Fixes Wearable Medical Product Issues

Rigid-flex Electronic Circuit Board Design Fixes Wearable Medical Product Issues

The majority of PC boards today are basically rigid plates to connect circuitry. Nevertheless, that is changing rapidly; the need for flexible printed circuit boards (or flexible circuits) is swiftly growing mainly on account of the developing wearable device industry. Most likely the biggest segment of that market is the medical care industry where wearable products will be utilized to gather all varieties of bodily info for prognosis and study, in addition to private health use. By now wearables can be purchased to keep an eye on pulse rate, blood pressure level, glucose, ECG, muscle movement, and more.


Those wearable devices bring many different issues for electronic circuit board designers that rigid boards do not. Here are several of the problems along with what designers can perform to ease them.

Three-dimensional Design

While every single PCB is certainly three-dimensional, flex circuits enable the entire assembly to be bent and folded to conform to the package that the merchandise requires. The flex circuitry is collapsed so the rigid electronic circuit boards fit into the product package, occupying small space.
There is a lot more to the design, hence the extra challenges, than simply connecting the rigid boards. Bends should be correctly designed so boards align where they’re intended to mount, while not putting force on the connection points. Up to recently, engineers actually used “paper doll” models to simulate the Printed Circuit Board assy. Today, design tools are obtainable providing 3D modelling of the rigid-flex assy, allowing for quicker design and far greater precision.

Tiny Items and Dense Circuits

Obviously, wearable goods must be tiny and unobtrusive. During the past, a medical “wearable” such as a Holter heartrate monitor integrated a pretty big external device with a neck strap or belt mount. The innovative wearables are tiny and attach directly to the patient without any or very few external wires. They get a range of records and can even process some analyses.

An highly discreet device mounting right to the sufferer requires flexible circuitry and incredibly compressed layouts. Aside from that, the board shapes are regularly circular or even more uncommon shapes, requesting wise placement and routing. For such tiny and dense boards, a PC board tool which is enhanced for rigid-flex designs makes handling unconventional shapes less of a challenge.

Stackup Design is important

The stackup – the map of the PCB layers – is essential if you use rigid-flex techniques. If at all possible, your PCB design software has the ability to design your stackup including both the rigid and flexible parts of the assy. As mentioned earlier, the layout of the flexing area ought to be made to lower the pressures on the traces and pads.
One of the biggest obstacles with rigid-flex designs is qualifying several makers. After the design is completed, every aspect of the design has to be communicated to the board fabricator as a result it will be appropriately manufactured. But, the best practice is to select one or more companies early in the design and work together with them to assure your design suits their assembly needs as the design goes forward. Taking part with fabricators is made simple by employing standards. In this instance, IPC-2223 is the vehicle for communicating with your manufacturers.

The moment the design is finished, the data package must be assembled to hand-off to be made. Although Gerber remains used for standard PCBs in a few companies, on the subject of the difficulties of rigid-flex, it is highly recommended by both PCB program suppliers along with fabricators that a more intelligent data exchange format be utilized. The 2 most well-liked intelligent formats are ODG++ (version 7 or later) and IPC-2581, as both versions obviously stipulate layer demands.


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