Flexible Circuits Enhance Design
As engineers continue to improve products and create innovative products, they need to take into consideration the function of each component within a circuit board. Oftentimes, components will need to be positioned in a specific way for the product to work properly. This is where flexible circuits can offer significant design flexibility for engineers. Flex circuits can be bent and manipulated multiple times during installation and servicing without electronic failure.
This is a major benefit for manufacturers and consumers alike, because the flexible circuits reduce assembly steps. It also reduces the cost and time of assembly due to less manual labor. Additionally, it can reduce manufacturing error. When it comes to routing, wrapping, and soldering wires in a traditional hand-built wiring harness, errors are common. With a flexible circuit, the components are routed only to those points called for in the schematic, net list, and gerber files, eliminating many opportunities for human error during production.
Using flexible circuit can be beneficial for a wide variety of applications, such as data communication, optical networking, medical treatment, industrial control, aerospace/military, etc. They are also a great solution in applications where space is limited, as they can be easily shaped and placed in small spaces where traditional rigid PCBs cannot.
How Flexible Circuits Enhance Design Flexibility For Engineers
Flex circuits are usually made from a thin film dielectric material, such as polyimide or similar. This allows heat to easily dissipate through the circuit, which in turn allows for a more compact design and improved performance.
This can be a huge advantage in some applications, such as medical devices where the sleek look of a flex circuit can increase patient confidence. In addition, a flex circuit can be used in places where conventional PCB materials would fail due to temperature or moisture concerns.
Multilayer flex circuits can be designed with multiple single-sided or double-sided layers that are interconnected by means of complex connections, pins, stiffeners, and other electrical components. These designs can also include reference plane layers, shielding, and pad fillets to enhance etch yield, material strength, and conductor thickness-to-bend radius performance.
In these cases, the flex circuits may not be continuously laminated together throughout the entire construction, but rather left unbonded in areas occupied by vias or other openings. This can be a cost saving option, especially in cases where maximum flexibility is desired.
When designing a multilayer flex circuit or rigid flex, it is important to consider the construction method and layer count with the flexibility requirements in mind. A higher layer count will limit the bend capabilities of the flex circuit, and in some cases, the ability to provide adequate mechanical stiffeners. To maximize flexibility, it is recommended to use a construction technique that includes the flex layer inside the stack-up. This prevents the flex from being exposed to outer-layer plating, and improves impedance control, signal integrity, and etch yield in the flex region. In addition, this design method provides a greater level of consistency and reliability over the lifetime of the flex circuit.
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