When I first started my career in the automotive flexible flat cable (AFFC) supply business, most of my clients were focused on infotainment systems, seat adjusters, and door modules. Those were clear, established use cases—familiar applications where AFFCs had already proven their reliability over decades in the industry. About five years ago, though, a client from a commercial vehicle manufacturer reached out with a question that would push our entire product line in a new direction: Can we use AFFCs in brake systems? At the time, I’ll admit I paused. Brake systems are the backbone of vehicle safety; every component has to meet the strictest performance standards, and the idea of a flat, flexible cable replacing traditional wiring harnesses in such a critical system felt risky. But as a supplier, my job isn’t to say “no” to a bold question—it’s to dig into the engineering behind it, test the limits, and see if the answer is actually “yes.” Automotive Flexible Flat Cable
To understand why this question matters, I first had to break down what modern brake systems require from their wiring components. Traditional brake systems used to be mostly mechanical, but today’s electric and hybrid vehicles, as well as next-generation internal combustion models, rely on electronic brake systems (EBS) that connect brake control units, wheel speed sensors, brake pad wear sensors, and electronic parking brakes (EPB). These systems need wires that can handle extreme conditions: temperatures that swing from -40°C in harsh winters to 125°C under the hood, constant vibration from rough roads, exposure to road salt, moisture, and even brief contact with brake fluid. Traditional round wire harnesses work, but they have drawbacks. They’re bulkier, harder to route through tight spaces near brake calipers and chassis components, and more prone to tangling or rubbing against other parts over time. That’s where AFFCs come in—their flat, thin profile saves space, and their uniform conductor arrangement reduces signal interference, which is key for accurate sensor data in EBS.
The first step in testing if AFFCs can hold up in brake environments was collaborating with a small engineering team at a local test lab. We pulled our standard AFFC materials—polyester film insulation, copper conductors with a thin tin plating for corrosion resistance—and subjected them to the exact same tests required for brake system wiring. The temperature cycle test alone ran for 1,000 hours, cycling between -40°C and 125°C every two hours. I’ll never forget waiting for the first results; we had 10 test samples, and half of them showed no signs of insulation cracking or conductor degradation after 1,000 hours. The other half? We’d accidentally used a thinner polyester film that wasn’t rated for under-hood temperatures, which is a common mistake when mixing standard and specialized AFFC grades. That taught us a critical lesson: not all AFFCs are created equal. To work in brake systems, we needed to adjust our core materials to meet ISO 6722, the international standard for automotive wiring. That meant upgrading the insulation to a cross-linked polyester that resists brake fluid swelling and has a higher melting point, and using stranded copper conductors that can flex repeatedly without breaking—something AFFCs are actually designed to do, unlike solid-core round wires.
Next came the flexing test, which is make-or-break for any cable near moving brake components. EPB systems, for example, need a cable that can move as the brake caliper expands and contracts during operation. We mounted AFFC samples to a test rig that mimicked the movement of a brake caliper, cycling the cable 1 million times—about the equivalent of 10 years of average vehicle use. After that, we pulled the cables apart to check conductor continuity, and every single sample passed. I still have a small section of that test cable in my desk; it’s a little worn at the edges, but the conductors are intact. That’s when I started to see the potential: AFFCs’ flexibility isn’t just a space-saver—it’s a performance benefit in applications that require constant, controlled movement. Traditional round harnesses would need extra strain relief and routing space, but AFFCs can snake through tight gaps near brake lines without adding bulk, which is a huge advantage for vehicle designers trying to cut weight and optimize space in electric vehicles, where battery pack size is everything.
Of course, brake systems don’t just care about physical durability—they care about safety. If a cable fails, it could lead to a sensor sending incorrect data, or an EPB that won’t engage, which is a nightmare scenario for drivers. AFFCs’ flat design means that the distance between conductors is uniform, so electromagnetic interference (EMI) is lower than in round wires, which is critical for wheel speed sensors that send data to the anti-lock braking system (ABS). We tested this in an anechoic chamber, connecting AFFCs and traditional harnesses to a wheel speed sensor, and found that the AFFC signal had 30% less noise, even when routed near a brake control unit. That’s a big deal for ABS, which relies on precise sensor readings to prevent skidding. It’s also a big reason why more and more brake system designers are looking to AFFCs: the signal consistency reduces the risk of false readings, which is a top safety concern.
I’ll be honest, though—there are still limitations to using AFFCs in brake systems, and as a supplier, I never want to oversell a product. For example, high-pressure hydraulic brake lines still need rigid connectors, so AFFCs work best in the electronic components of the brake system, not the hydraulic lines themselves. They also aren’t ideal for areas that are exposed to direct, constant brake fluid spray, unless we add a layer of polyurethane coating over the insulation, which we’ve developed as a specialized variant for this exact use case. Another consideration is cost: high-performance AFFCs for brake systems are slightly more expensive than standard harnesses, but when you factor in the weight savings (AFFCs are 40% lighter than equivalent round wire harnesses) and easier installation, the total cost of ownership actually goes down for manufacturers. A few of our early clients told us they were able to reduce installation time by 2 hours per vehicle by using AFFCs, since they don’t need to route as many separate wires and can be pre-assembled into a single flat unit.
Over the last two years, we’ve supplied AFFCs to three commercial vehicle manufacturers and two electric vehicle startups for their EBS and EPB systems, and none of them have reported performance issues. The first client, a medium-duty truck maker, tested our AFFCs in 50 units last year, and after 12 months of field testing, zero cable-related failures were reported. One of their maintenance teams even told us that the AFFCs were easier to inspect during routine brake checks, since their flat surface made it simple to see if the insulation was intact. That feedback is what drives our business—we don’t just sell cables, we sell solutions that work in real-world conditions.
So, back to the original question: Can automotive flexible flat cables be used in brake systems? The answer, after years of testing, collaboration, and iteration, is a resounding yes—but only with the right materials and design tailored to brake system requirements. It’s not a one-size-fits-all solution, but when engineered to meet ISO 6722 standards, with cross-linked polyester insulation and stranded conductors for flex resistance, AFFCs can outperform traditional round harnesses in many brake system applications. For vehicle designers, they offer a way to save space, reduce weight, and improve signal reliability—all critical as we move toward more advanced driver-assistance systems (ADAS) where brake systems are integrated with automatic emergency braking and adaptive cruise control, which rely on even more precise sensor data.
If you’re a brake system designer, vehicle manufacturer, or maintenance team looking to test AFFCs for your brake systems, we’d love to work with you to develop a customized solution. Our engineering team can tailor insulation thickness, conductor size, and coating options to meet your specific environmental and performance needs, and we provide sample testing to make sure the cables hold up in your exact operating conditions. We’ve spent years refining AFFC technology for automotive applications, and we’re confident that with the right design, they’re a reliable, high-performance option for brake systems of all types.
If you’re ready to discuss how AFFCs can fit into your brake system projects, or want to learn more about our specialized automotive-grade AFFC variants, don’t hesitate to reach out for a consultation. We’re here to answer your questions, provide test data, and help you find the right cable solution for your needs.
Automotive Flexible Flat Cable References
- International Organization for Standardization. (2020). Road vehicles – Wiring systems – Dimensions and performance requirements (ISO 6722:2020). Geneva, Switzerland: ISO.
- Society of Automotive Engineers. (2021). Flexible flat cables for automotive applications (SAE J2040:2021). Warrendale, PA: SAE International.
- Automotive Electronics Council. (2022). Qualification of integrated circuits and passive components for automotive environments – Cable materials (AEC-Q100:2022). Troy, MI: AEC.
- International Organization for Standardization. (2019). Road vehicles – Electronic brake systems – General technical requirements (ISO 15031:2019). Geneva, Switzerland: ISO.
Tennrich Electronics Technical Development (Kunshan) Co., Ltd.
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