Flexible Printed Circuit Boards (FPCs) are high-performance circuits known for their reliability, lightweight design, and remarkable flexibility. Typically built using polyimide as the substrate, FPCs are characterized by their thinness, softness, and ability to bend or flex without compromising their electrical integrity.

In certain applications, specific areas of a flex PCB need additional mechanical support to accommodate component placement during assembly. To achieve this, the flexibility of the board is reduced in certain sections by adding a stiffener, a rigid material designed to reinforce these localized areas. This enhancement improves the board’s durability and stability during the assembly process. In addition to providing mechanical support for components, stiffeners can also assist with heat dissipation, and specialized stiffener designs can aid in the overall assembly process.

Key Consideration: It’s important to note that stiffeners serve a mechanical function only and are not part of the electrical design or schematic of the PCB.

When selecting a stiffener, the choice of material depends on factors such as design requirements, performance demands (e.g., heat dissipation, cost), and the specific application’s flexibility requirements. Common stiffener materials include:

• Stainless Steel – Known for its durability and strength.
• Polyimide (PI) – Offers excellent flexibility and thermal resistance.
• FR4 – A widely used, cost-effective material.

Additionally, stiffeners come in a variety of thicknesses to accommodate different design needs and performance requirements.

Stiffener Adhesives: The adhesives used to bond the stiffener to the FPC are just as crucial as the materials themselves. Typically, the same adhesives used for laminating the FPC substrate are employed for stiffener bonding. One of the most common adhesive types is Pressure Sensitive Adhesive (PSA), which offers excellent bonding properties and ease of application. The choice of adhesive should be tailored to meet the specific needs of the project.

If you have any questions regarding PCBs or PCBA, feel free to contact us at info@wellcircuits.com.