Flex Circuit Boards
The rise of wearable technology has spurred new horizons for design creativity, allowing for sleek and unobtrusive electronics. A key enabler is the use of flex circuit boards, also known as flexible printed circuit board (FPCB). Unlike rigid PCBs, flex circuits are highly adaptable and can bend to match the contours of a device or garment. In the case of wearable devices, flex circuits are crucial to designing sensors that monitor a wearer’s daily physiological and neurological changes and transmit those data to medical professionals for analysis.
In addition, flex circuits are capable of accommodating more components than ribbon cables can and offer conductor density that exceeds those of conventional ribbon cables. These advantages are especially important when designing wearables for use in a variety of environments, including the workplace. In the manufacturing industry, flex circuits are used to interface with rigid boards without the tall and bulky connectors flat cables require or in some cases can be integral with the board itself, eliminating external connectors altogether.
As the number of wearables continues to grow, engineers are constantly pushing the boundaries of what these devices can achieve. This requires the development of innovative flex circuit board designs that can accommodate critical electronic components within a compact space, such as sensors, power sources, and communication modules. The resulting flex circuits must be robust enough to withstand repeated bending cycles and other environmental stresses.
Flex Circuit Boards and Wearable Technology
To meet the challenges of these applications, flex circuits are typically constructed using finer lines and spaces, thinner copper, and reduced base material. This helps to ensure that soldered connections can withstand multiple bending cycles. Additionally, the traces must be designed to be flexible in order to minimize electrical resistance. PCBWay recommends that if a trace is expected to be bended frequently, then it should have wide endings at the edge in order to better resist the forces that will pull on it during bending.
Another way to maximize flex PCB durability is to add metal cages or shield planes that reduce electromagnetic interference (EMI). These features are installed during the pick-and-place process and can be either solid or perforated depending on the application.
Cost considerations are an important factor when developing wearable devices, and balancing cost and quality is a key challenge for designers. Flex PCB suppliers can help manage costs by recommending cost-effective materials and streamlined manufacturing processes. Standardizing design elements across different wearables can also help to reduce costs.
A specialized test called pull testing is often performed on flex circuits to determine whether or not soldered joints can withstand a designated number of bending cycles. This test can be done on rigid PCBs as well, but it is especially useful for flex circuits because the test can be conducted in a controlled environment that simulates real-world conditions.
As a result of these design requirements, flex circuits tend to be more expensive than rigid PCBs, but they offer superior performance and durability. By partnering with experienced, reliable manufacturers, wearable designers can take advantage of these benefits while staying within their budgets.