Epec's Blog | Electronics Manufacturing Solutions

Flex circuit suppliers vary widely in experience, capabilities, and financial stability. Choosing the right partner is critical to the success of your application.

A structured vetting process helps ensure that your supplier can support design requirements, manufacturing constraints, and long-term production goals. The following five questions identify the most important areas to evaluate when selecting a flex circuit supplier.

Flexible circuits share some characteristics with rigid printed circuit boards, but the manufacturing approach is fundamentally different. The thinness and lack of reinforcement in flex materials introduce unique challenges that affect handling, processing, and dimensional control.

In the world of flexible circuit boards, stiffeners are a common requirement in a lot of flex designs. By definition, a circuit board stiffener provides a mechanical support function and is not part of the electrical schematic of a design.

Today, there are well over 3,000 companies that manufacturer printed circuit boards (PCB) in Asia (China, Taiwan, Japan, India, Korea, Thailand) with the supply capacity continuing to grow well ahead of the global demand.

It is critical for any flex circuit design to be free of errors and violations in order to get the application to market as fast as possible without unnecessary delay. To help designers avoid common IPC PCB design standards violations in rigid-flex PCBs, this blog post will discuss three of the most common IPC Association Connecting Electronics Industries design violations.

A common question in PCB development is why flex and rigid-flex PCB tooling costs more than rigid-only circuit boards. The primary reason is process complexity. Flex circuit tooling involves more fabrication steps, tighter coordination between materials, and a higher level of hands-on engineering compared to standard rigid PCBs.

In addition to fabrication complexity, flex and rigid-flex PCB designs require more engineering programs to be manually created. Many of these steps cannot be fully automated, which increases setup time and engineering labor during the tooling phase.

Flexible circuits use either polyimide coverlay or flexible LPI solder mask to encapsulate external circuitry, each with distinct performance and design requirements. Polyimide coverlay is the most widely used due to its durability, flexibility, and dielectric properties, while LPI solder mask is applied similarly to rigid circuits but behaves differently in flex applications.

Rigid-flex printed circuit boards combine rigid and flex circuit technologies into a single, integrated construction. This integration introduces design constraints that do not exist in rigid-only or flex-only designs. As a result, specific layout rules must be reviewed and implemented during the Gerber layout phase to avoid reliability issues and manufacturing rework.

Flex and rigid-flex PCB constructions have many variations that allow for a wide range of applications and solutions. A significant difference to rigid PCB constructions is that uneven layer counts are allowed and frequently used. The primary reasons being reduced flex thickness, improved flexibility and reduced part cost.

Essential to any flex or rigid-flex printed circuit board (PCB) contruction is validation that your flex PCB design will meet your mechanical bend requirements. Minimum flex bend radius requirements were put in place so your design won't exceed the physical capabilities of copper circuitry, which would result in failed parts, long term reliability concerns, and several giant headaches.