In the modern wire harness industry, flat cables are a core component whose performance directly affects the overall performance of the wire harness system. From automobiles to electronic devices, from industrial machinery to aerospace applications, flat cables play a crucial role in transmitting current and signals, ensuring that information flows freely and power transmission is stable across various systems.

Key Characteristics of Flat Cables

Electrical Performance​​

l Conductivity: Flat cables typically use copper conductors due to their good conductivity and high electrical conductivity. High conductivity means that when transmitting the same amount of electricity, the cable generates less resistance and lower energy loss. For example, in automotive engine start systems, high-conductivity flat cables ensure that the starter motor responds quickly, reducing energy waste on the cable and improving start efficiency.

l Insulation Performance: The insulation layer is an indispensable part of the flat cable. Common insulation materials such as polyvinyl chloride (PVC) and cross-linked polyethylene (XLPE) tightly wrap around the conductor to prevent current leakage and short circuits. In complex electrical environments, such as inside electronic devices, flat cables with good insulation performance can effectively resist electromagnetic interference, ensuring the accuracy and stability of signal transmission.

Physical Performance​

l Flexibility: In some applications where frequent bending or movement is required, such as automotive door harnesses and robotic joints, the flexibility of flat cables is crucial. Multi-strand twisted copper conductors significantly enhance the flexibility of the cable, allowing it to adapt to repeated bending without breaking, ensuring long-term stable operation of the harness.

l Mechanical Strength: Although flat cables need to be flexible, in specific environments, such as areas with strong vibrations in industrial equipment or high mechanical stress in aerospace, the cable also needs to have sufficient mechanical strength to withstand external forces such as pulling and squeezing. By optimizing the design of the cable structure, such as adding reinforcing cores or using special alloy materials, the mechanical strength of the cable can be improved to ensure normal operation in harsh environments.

Temperature Resistance and Corrosion Resistance​

l Temperature Resistance: Different application scenarios have varying requirements for cable temperature resistance. In the engine compartment of automobiles, where temperatures can exceed 100°C, cables need to use high-temperature-resistant materials, such as silicone rubber-insulated cables, to ensure that the insulation performance does not degrade and the cable does not soften or deform at high temperatures, maintaining circuit stability.

l Corrosion Resistance: In harsh environments such as humidity and chemical corrosion, cables are prone to erosion. For example, in ships and chemical equipment, cables need to have excellent corrosion resistance. Using corrosion-resistant metal conductors (such as tinned copper) and special anti-corrosion insulation coatings can effectively resist water and chemical erosion, extending the service life of the cable and ensuring long-term reliable operation of the system.

Selection Criteria for Flat Cables

Selecting Cable Types Based on Application Scenarios​​

l Automotive Industry: In complex environments with high temperatures, vibrations, and oil contamination, such as in the engine compartment, cables are often selected that are resistant to high temperatures, oils, and vibrations, such as German standard FLRY-A type cables; door harnesses require frequent bending due to opening and closing, so AVSS (thin-walled insulated) cables with good flexibility are used; for sensors transmitting weak signals, such as knock sensors and crankshaft position sensors, electromagnetic shielding cables are used to prevent electromagnetic interference.

l Electronics: In small, high-performance electronic devices such as smartphones and tablets, cables need to have small size, high precision, and good flexibility. For example, FFC (Flexible Flat Cable) terminal wires can arbitrarily select the number and spacing of conductors, greatly reducing the size of electronic products, commonly used for connecting motherboards with displays, cameras, and other components to achieve signal and power transmission.

l Industrial Equipment: The environment of industrial automation production lines is complex, with strong vibrations and electromagnetic interference. Cables used to connect industrial robots, CNC machine tools, and other equipment need to have not only good electrical performance but also high anti-interference capabilities and the ability to withstand harsh environments, such as using double-layer shielded cables to resist electromagnetic interference and using wear-resistant, corrosion-resistant materials to deal with harsh industrial environments.

l Aerospace: Aerospace has extremely stringent requirements for wire harness cables, requiring lightweight, high-strength, high-temperature resistance, and radiation resistance. Cables often use special alloy materials and advanced manufacturing processes, such as silver-plated copper cables, which can ensure good conductivity while reducing weight; insulating materials use high-performance materials such as polyimide to adapt to extreme space environments and complex high-altitude conditions.

Determining Cable Cross-Section Based on Current and Power

The size of the cable cross-section directly affects its current-carrying capacity, generally following the principle that the greater the power of the electrical component, the larger the required cable cross-section. For electrical equipment that operates for long periods, to ensure that the cable does not overheat, a cable with 60% of the actual load capacity can be selected; for short-term operation devices, a cable with 60%-100% of the actual load capacity can be used.

In addition, factors such as ambient temperature, cable routing, and the number of connectors need to be considered when determining the cable cross-section. In high-temperature environments, cables have difficulty dissipating heat, so the cross-section needs to be appropriately increased; complex cable routing and multiple connectors can lead to increased voltage drop, which also requires an increase in the cable cross-section to ensure stable electrical performance. Empirical formulas such as I=P/U (I is current, P is power, U is voltage) and A=IpL/Ud (A is cable cross-section, p is copper resistivity, L is wire length, Ud is the maximum allowable voltage drop loss) can be used to assist in calculating the appropriate cable cross-section.

Considering Cable Color Identification​

In applications such as automotive harnesses, cable color is of great significance. Although there is no unified standard for cable colors in the industry, each vehicle manufacturer has its own regulations, but cable colors are mainly divided into single-color, bi-color, and tri-color, with the purpose of facilitating harness assembly and maintenance. For example, industry standards in China stipulate that single black is exclusively used for ground wires, and red is used for power lines to avoid confusion. In actual harness wiring, different colors of cables are used to distinguish different circuit functions, such as blue cables often used for signal circuits, green cables may be used for control circuits, etc., greatly improving the efficiency of harness installation and maintenance.

Development Trends of Flat Cables

Research and Application of High-Performance Materials

As the performance requirements for cables continue to increase in various industries, the development of new high-performance materials has become a trend. In terms of conductor materials, in addition to optimizing the performance of copper and aluminum materials, exploring new conductive materials, such as carbon nanotube composites, is expected to achieve higher conductivity and better comprehensive performance. In the field of insulating materials, developing materials with higher temperature resistance, radiation resistance, and anti-aging properties, such as new ceramic-based insulating materials and high-performance fluoroplastics, is needed to meet the needs of high-end fields such as aerospace and new energy vehicles.

Miniaturization and Lightweight Design​

To adapt to the trend of miniaturization of electronic products and lightweight automobiles, flat cables are developing towards being thinner and lighter. On the one hand, by improving manufacturing processes, reducing the diameter and thickness of the insulation layer of the cable while ensuring electrical and physical performance; on the other hand, using lightweight materials to replace traditional heavier cable materials, such as using lightweight alloy cables and low-density insulating materials in aerospace harnesses, reducing the weight of the harness without affecting its performance, enhancing the overall competitiveness of the product.

Intelligentization and Multi-functional Integration​

In the future, flat cables will not only be limited to transmitting current and signals, but intelligentization and multi-functional integration will become development directions. For example, developing cables with self-monitoring functions can monitor parameters such as cable temperature and current in real-time, and issue timely warnings in case of abnormalities, improving the safety and reliability of the system; integrating cables with sensors, communication modules, etc., to achieve integrated data collection, transmission, and processing, providing support for the development of smart devices and smart grids.

Flat cables are a key foundation in the wire harness industry, and their performance, selection, and development are closely related to technological progress and product upgrades in various application fields. Continuously improving cable performance, optimizing selection criteria, and keeping up with development trends are the core driving forces for continuous innovation and development in the wire harness industry.