How do flexible PCB boards reduce the need for connectors?
flexible PCB boards reduce the need for connectors
As PCB components are increasingly being integrated into consumer electronics, automobiles, aircraft and medical devices, flexible printed circuit boards are gaining in popularity as the solution for these complex, space-limited applications. They offer the ability to accommodate both a wide range of connections and non-traditional shapes that cannot be achieved with traditional rigid-boards, allowing manufacturers to reduce the number of connectors required in their final products.
In addition to their flexibility, flexible pcb board can be designed with higher layer counts than rigid-boards without losing performance or reliability. While the higher layer count can make the design more complicated, innovations like laser direct imaging (LDI) and roll-to-roll lamination have refined the process to improve trace patterning accuracy and speed, enabling high-density circuits on a flexible substrate.
Another important consideration in designing a flex circuit is the type of flexing it will be subjected to. If the flex section will be static – such as in a handheld ultrasound device – you can be more flexible in your choice of material and copper options, as well as layer count. But if the flex section will be subjected to repeated bending, you should avoid very thick traces and consider using an air gap between layers to maintain flexibility.
How do flexible PCB boards reduce the need for connectors?
Lastly, you should always plan your flex circuit to eliminate stress points. Especially when routing traces to and from a connector, make sure the transition is smooth rather than abrupt. Abrupt changes in thickness cause stress points that can snap or break the traces. Ideally, you should route the thinnest traces away from the connector and use fillets or a gradual transition.
Connectors can add a lot of bulk and weight to the finished product, so reducing the need for them in a flex PCB design is key to saving on both assembly and manufacturing costs. There are many ways to do this, including etching plated-through holes and reducing the size of the access openings in the coverlay. It is also common to add flex-to-rigid stiffeners made of FR4, polyimide or aluminum to support the connection area and reduce fatigue.
Another option is to incorporate shielding into a flex circuit. Shielding is particularly effective in preventing electromagnetic interference and electronic shocks, and can be applied to the traces, vias or the entire layer stack.
Using flexible PCBs with a hot bar solder connection can also significantly reduce the amount of wires and connections needed for your product. In some cases, this can even replace the need for a connector completely by allowing the flex circuit to attach directly to a hardboard via an ultra-thin, waterproof solder interface.
Other alternatives include the use of flex cables, which utilize parallel conductor traces on the flex substrate to create a ribbon cable capable of high-density interconnections for signals, data and power. And a variety of graphic overlays, which combine flexible circuitry with acrylic or polyester covers to provide a user interface with LEDs, LCDs and switches.