Flex PCB Mechanical Design Benefits And Best Options For Stiffeners

Each type of stiffener material provides a range of benefits depending on what the designer requires for their flexible circuit design. Here are some common applications for stiffeners from which a designer can determine which type of material is best suited for the application, take into account cost considerations and determine additional advantages about a specific material.

Supporting Component / Connectors Areas

When it comes to supporting a component or connector area, stiffeners can be manufactured out of Polyimide, FR4, aluminum and stainless-steel materials. When narrowing down the choices, a manufacturer should review other considerations.

When looking for the least expensive material to use in this situation, polyimide or FR4 is the answer. If the engineering is looking for a material to make the circuit board more rigid as well as being used as a carrier panel for assembly purposes, then FR4 is the most common choice.

ZIF Connectors

Only polyimide stiffeners can be used for ZIF connector applications. The stiffener allows for the necessary increased thickness at the connector contacts. The stiffener can only be applied with thermally bonded flex adhesive and is attached prior to profiling the part outline. It is applied oversized to the part outline which then allows the stiffener and the part outline to be cut simultaneously to ensure the tight dimensional tolerances, required by ZIF connector specifications, are achieved.

Additional Thickness and Strength

When there needs to be an increased thickness in a specifc area, polyimide stiffeners are preferred. Polyimide is also ideal when the flexible circuit board will experience higher than normal wear-and-tear.

Thermal Transfer Management

For Flexible circuits that generate excess heat that needs to be dissipated, aluminum stiffeners can be used. Their heat transfer capabilities will allow heat to be transferred from components to the back of the flexible circuit WHERE it can then dissipate into the environment or the device enclosure.

Controlling Bend Locations

In some designs there may be a requirement where the bend locations must be constrained to specific locations. Polyimide is most commonly used but some applications may require FR4. This can allow the circuit to better fit within in the final product or equipment without the risk of becoming damaged or facilitate the assembly process.

Cost Factors

Controlling costs is an important element of a successful flexible circuit design. With respect to cost polyimide is generally the most cost effective. It is easily crafted using a die or laser cutting, making it easier to manufacturer. FR4 is also widely used and cost effective. Its added rigidity creates a flat and stable surface. It does however typically require additional drill and routing operations to manufacture. Aluminum and stainless steel are more costly. The materials themselves are more expensive and they typically require more expensive machining operations. The designer needs to evaluate the flexible circuit design requirements to determine the best stiffener for the job.

Solutions In Flex Circuit Stiffeners

Stiffeners in a flex PCB design add functionality to the finished part. Either when required to rigidize a specific area for component support or to increase the part thickness, in a localized area, to meet a specific connector specification. If you are trying to figure out the best stiffener for your flexible circuit boards, turn to Epec Engineered Technologies. We design and create flex and rigid-flex circuits for your electronic applications.