Creating a Practical Solution for Long Flex Circuits with Thin Traces
Challenge
Epec was approached by a long-standing customer who was facing new design challenges in their flexible circuit requirements. Traditionally, their applications had been served with standard trace widths and manageable circuit lengths. However, as their products evolved, they began to require much longer flex circuits with thinner trace widths.
This combination, long lengths paired with very fine traces, introduced significant manufacturing difficulties. In the etching process, thin traces over large areas become highly susceptible to damage. Maintaining trace integrity without sections etching away is extremely difficult, and in many cases, nearly impossible with existing production methods. The customer recognized this limitation and came to Epec with two possible needs: either find a way to produce these longer, thinner flex circuits reliably, or suggest an alternative approach that would still achieve their performance goals.
Complicating matters, this was not a request that other manufacturers were willing to take on. The customer had already approached several other suppliers and received rejections. Some declined outright, stating the design was not manufacturable, while others did not provide constructive feedback or potential alternatives.
With the project at risk of stalling, the customer relied on Epec’s engineering expertise and collaborative approach to evaluate the challenge from a fresh perspective.
Solution
After carefully reviewing the design requirements, Epec’s engineering team determined that producing a single, extremely long flex circuit with ultra-thin traces was not feasible with current manufacturing technology. Instead of dismissing the project, Epec proposed a creative workaround that would maintain electrical performance while avoiding the risks of trace loss during etching.
The solution was to break down the design into multiple shorter flexible circuit boards that could be connected using a daisy-chain configuration. By linking these smaller flex circuits together, the customer could still achieve a continuous and unbroken connection from point A to point B without relying on a single, excessively long piece. This approach balanced manufacturability with performance, ensuring that the trace widths could remain within stable tolerances.
To support this strategy, Epec worked closely with the customer to validate the daisy-chain method as a practical solution. Our engineers explained the technical reasoning behind the approach and demonstrated how the configuration could deliver the same electrical continuity required by their design. Rather than presenting a “yes or no” answer, Epec provided a pathway forward that preserved the customer’s design intent while remaining realistic in terms of production capabilities.
This proactive problem-solving also underscores one of Epec’s core strengths: we don’t just point out limitations, we offer alternative solutions. Where other manufacturers had walked away, Epec leaned in and worked collaboratively with the customer to reshape the design into something that could be built and delivered reliably.
Result
The daisy-chain solution proved successful. While Epec did not receive extensive details on the customer’s final assembly, there were no reported issues with the flex circuits that were manufactured under this approach. Production moved forward without defects related to the new configuration, and the customer continued to order additional parts for other projects, indicating their satisfaction with the outcome.
It is worth noting that this particular flex circuit design was a niche requirement. For the customer, it was not a make-or-break component for their overall business, but it represented an important step in exploring new design directions. With Epec’s guidance, they were able to pursue that development path without the setbacks of costly delays or failed prototypes.
Equally important, the experience reinforced the customer’s trust in Epec. By being transparent about the limits of manufacturing technology while still offering a workable alternative, Epec demonstrated both technical expertise and a commitment to partnership. Instead of rejecting the request outright, we helped the customer move forward in a way that made sense for their application.
Today, the customer continues to collaborate with Epec across multiple projects. The daisy-chain flex circuit case is a strong example of how Epec approaches engineering challenges: not with a binary answer, but with solutions that keep projects alive, practical, and manufacturable.
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