Printed Flexible Circuits Contribute to Faster Prototyping
Printed flexible circuits (FPC) are the core of many innovative products. Designed to be lightweight, durable and versatile, flex PCBs are an essential tool for manufacturers who want to create sleek, sophisticated electronics that fit seamlessly into a wide range of shapes and sizes. Whether it’s a headset for a drone or a microcircuit in an advanced medical device, flex PCBs are used in almost every electronic product, enabling engineers to push the boundaries of innovation while keeping production costs low.
However, while printed flexible circuits may look similar to traditional rigid designs from the outside, the inner workings of these circuits are much different. As such, producing a flex circuit prototype is a more intensive undertaking than creating a rigid prototype. The manufacturing process requires careful attention to detail, ensuring that the layout is properly optimized for DFM and that the design takes into account the unique mechanical properties of flex PCBs.
For example, elongating through-hole pads and adding tabs to provide better substrate grip are important steps in the layout process. It’s also critical to avoid conductor stacking, which reduces flexibility and causes internal strain in the circuit. In addition, the material used for a flex circuit is an important consideration. While there are a number of viable choices, copper foils offer the best balance of cost and physical performance for most applications.
How Printed Flexible Circuits Contribute to Faster Prototyping
The base layer of a flex circuit is also an important factor. Typically, this is made from FR4, which provides crucial stability, thermal resistance and excellent mechanical force. While it can be folded, it cannot bend, so a flexible circuit requires another base material. Often, this is polyimide. While it is flexible, it can only bend to a certain degree and has limited dimensional stability.
To complete a multi-layer flex circuit, it’s necessary to use an adhesive material for connecting the conductive tracks with the dielectric substrate or, in the case of a single-layer flexible circuit, to join the individual layers together. Lastly, an adhesive layer can also be used to protect the flex from moisture, dust and other external agents that could damage or contaminate the components.
Getting an experienced manufacturer engaged early in the design process is critical to optimizing prototype fabrication. This ensures clear communication and sets expectations that a prototype will accurately reflect the final product. An effective manufacturing partner will ideally be able to deliver high-quality flex circuit prototypes within days, reducing overall project timelines and allowing for rapid iterations as needed.
The most effective prototypes are those that provide a realistic representation of the final product, down to the component holes and outline features. This helps the engineering team identify and vet the design to make sure it’s ready for mass production and that no further changes are required before moving on. A comprehensive flex PCB prototyping process can even include a mechanical sample that mimics the structure of the finished product, which allows for a more thorough evaluation and review.
