Rigid-flex Electronic Circuit Board Design Eliminates Wearable Medical System Complications
The vast majority of printed circuit boards in the world today are simply rigid plates for connecting circuitry. However, that’s changing rapidly; the requirement for flex electronic circuit boards (or flex circuits) is aggressively increasing largely thanks to the booming wearable product industry. Probably the most significant segment of that market is the medical industry where wearable products will be utilized to collect all varieties of biological records for examination and study, as well as individual health use. Actually wearables are offered to keep tabs on heart rhythm, blood pressure levels, glucose, ECG, muscle movement, and a lot more.
The wearable devices bring many troubles for PC board designers that rigid boards don’t. The following are some of such problems along with what designers can do to help remedy them.
3 Dimensional Design
While each PC board is certainly 3 dimensional, flex circuits allow the entire assembly to be bent and folded to adapt to the package that the merchandise uses up. The flexible circuitry is collapsed to ensure that the rigid PC boards easily fit into the product package, occupying minimum space.
There is a lot more to the design, so the added challenges, than simply connecting the rigid boards. Bends have to be properly designed so boards get in line where they are meant to mount, while not placing stress on the connection points. Up to recently, engineers actually used “paper doll” models to emulate the circuit board assembly. At this point, design tools are offered that offer 3D modelling of the rigid-flex assy, helping more rapidly design and a lot greater precision.
Little Items and Squeezed Circuitry
Obviously, wearable products are required to be tiny and inconspicuous. Previously, a healthcare “wearable” maybe a Holter pulse rate monitor integrated a fairly large exterior device with a neck strap or maybe belt mount. The recent wearables are small and attach straight to the sufferer without any or very few external cables. They collect many different data and are able to even process several analyses.
An highly discreet device affixing straight to the patient dictates flex circuitry and really compressed layouts. Moreover, the board shapes usually are spherical or even more unusual shapes, requiring clever placement and routing. For this sort of tiny and dense boards, a PC board tool that is designed for rigid-flex designs helps to make handling unusual shapes easier.
Stackup Design is vital
The stackup – the map of the electronic circuit board layers – is critical when you use rigid-flex techniques. Perfectly, your PCB design software has the ability to design your stackup including both the rigid and flex parts of the assembly. As said before, the layout of the folding area ought to be built to decrease the stresses on the traces and pads.
One of the primary challenges with rigid-flex designs is qualifying multiple producers. After the design is fully gone, all aspects of the design is required to be communicated to the board fabricator so it will be effectively produced. But, the best practice is to pick one or more makers at the start of the design and work together with them to assure your design satisfies their manufacturing needs as the design moves on. Taking part with manufacturers is made simple by employing standards. In cases like this, IPC-2223 is the vehicle for getting in touch with your fabricators.
As soon as the design is done, the data package has to be assembled to hand-off to be produced. Though Gerber remains employed for standard PCBs in some companies, in terms of the difficulties of rigid-flex, it is strongly advised by both PCB program vendors together with fabricators that a more intelligent data exchange format be utilized. The 2 most wellwell-known intelligent formats are ODG++ (version 7 or higner) as well as IPC-2581, as both versions precisely define layer standards.