Unique to Flexible PCBs
Incorporating flexible circuits into your PCB design allows for the elimination of bulky wire and cable connections and reduces overall package size. However, there are design considerations that are unique to flex or rigid-flex circuits that should be taken into account during the layout phase.
Flex and rigid-flex circuits are designed to bend, fold, crease or reposition in ways that conventional PCBs cannot. This means that they can be positioned into tight spaces and eliminates the need for bulky wires or solder joints, resulting in substantial savings in space and weight. This advantage helps to make flex circuits a more attractive interconnect solution than traditional rigid boards, particularly when SWaP (space weight and packaging) is a major concern for your product or assembly.
Unlike conventional PCBs, flex circuits can be bent or folded multiple times without damage to the copper layers. This allows for significant reduction in the footprint, enabling the use of smaller components and reduced component costs. They are ideal for replacing or consolidating wires and cables in a range of applications, including consumer electronics, medical devices, automotive systems, aerospace technology, and industrial electronic products.
Due to their thinner dielectric substrates, flex PCBs are much lighter than their rigid counterparts. This significantly reduces the overall package weight, especially when they are used in combination with rigid-flex boards to provide structural support. This is especially beneficial for high-stress environments and applications where the product may be subject to a range of vibration and stress conditions.
Design Considerations Unique to Flexible PCBs
Another key advantage of flex circuits is that they are more reliable than traditional rigid-boards, which can suffer from points of failure due to solder joints, connectors and internal components. Moreover, the flexibility of flex circuits increases reliability by minimizing the number of joints and improving signal integrity.
A key aspect of designing a robust flex or rigid-flex circuit is maintaining strict quality standards. Conducting critical inspections and quality control measures ensures that the fabrication process adheres to stringent industry standards, preventing errors that can impact the functionality of your final product.
Flex PCBs can be fabricated using different copper plating techniques, including panel plating (which deposits copper across the entire surface of the board) and pad-only-plating (button plating). The latter technique is more cost-effective than panel plating because it only applies copper to areas where the conductor traces are located. Button plating also provides better etch yields for small etch patterns and enables controlled impedance at higher speeds by ensuring consistent copper thickness, width, and spacing.
In addition to these manufacturing processes, a range of other materials can be added to a flexible pcb to improve its mechanical properties. For example, stiffeners can be applied to selected areas of a flex circuit to add rigidity and durability, particularly where the board is expected to undergo repeated bending cycles or abrasion. Stiffeners can be made from a variety of materials, such as steel or aluminum, depending on the application.
