Thin, thin polyimide flex foils covered with copper are the main material for pure flex circuit boards. The use is due to their affinity to withstand high temperatures.

Rigid flex circuits combine the advantages of rigid boards and flex circuits integrated in one channel.

Rigid-flex offers designers a variety of opportunities to help meet the mechanical constraints of existing systems. Rigid-flex helps to address certain parts of factor, form, and adaptability, allowing designers to accommodate overall design variability. The main advantage of rigid-flexible is that it will allow the use of many variables and meet the requirements of signal processing and other predictable values.

Rigid-Flex Circuit Design Guidelines

To create rigid flex, follow the precautions below to ensure the best results.

Considerations When Designing Rigid-Flex Circuits

To produce rigid-flex PCBs with unmatched quality and functionality, you must follow proper manufacturing practices. This is a set of guidelines and standards that manufacturers must consider when designing and manufacturing flexible circuit boards.

Determine the manufacturing process and materials in advance

Depending on the flexibility you need, you'll need to decide in advance what materials to use and how to use them. For example; when the circuit board you want to design only needs to be folded during the manufacturing process and thereafter in a fixed position without bending, you can decide the following

a. Copper type and grade

b. Manufacturing method

c. The number of layers to use.

On the other hand, if the board is suitable for applications with frequent movement, vibration and shock, it must be clear when choosing:

a. Copper coil

b. Adhesive and

c. Layers

Place copper traces on rigid-flex right angles

Copperworks is a great fit when placed on the right edge of the board. Avoid bending the copper traces around the corners as it will strain and may not produce the best bend. For PCB flex that requires bending, use sharp radius bends to avoid fouling copper traces.

Adequate pad support for exposed copper

Repeated stress from frequent flexing can cause copper on the circuit to peel off the polyimide substrate. Support exposed copper with pads to prevent separation.

Use shaded polygons

Hatched polygons in place of cured copper wires help keep the flex PCB flexible.

Leave at least a 1/2mm gap between the copper ring and the adjacent via

1/2mm helps avoid fatigue caused by frequent bending. Placing vias in fixed areas of the board helps avoid frequent movement and bending, resulting in optimal rigid-flex.

Contact your raw material supplier

If you plan to use less adhesive laminates and non-standard base dielectric materials, you should contact your material supplier during the design phase. The supplier must be contacted as components are made to standard sizes by special order and it may take some time for delivery without prior contact.

Finally

While there are a number of design options when combining rigid boards with flex circuits, this article gives you the best guidelines for designing rigid flex circuits.