Flexible Flat Cables: The Best Alternative to Round Cables

FACTS CHECKED BY  Jose George​

Modern applications like robotics, automated medical diagnostic equipment, or axis-control manufacturing require movement. To ensure flexibility in these applications, engineers used round cables. However, with repeated bending, conductors in round cables may get kinked. As a result, it leads to circuit failure. Thus, engineers are picking up something that can provide them with better performance and reliability. Now, flexible flat cables are fulfilling the demanding requirements of these modern applications. 

Table of Contents

What are flexible flat cables?

Flexible flat cables or FFCs are the cables that are both flexible and flat, having solid conductors which are flat. It comes in the category of flexible electronics; however, FFC means fragile cables used in highly dense electronic items such as laptops and cell phones. 

You can consider FFC as the miniature formation of ribbon cables which are also flexible and flat. The FFC has a flexible and flat plastic base with numerous flat metal conductors bonded firmly to the plastic base. Generally, manufacturers treat one end of the cable with the help of a stiffener so that insertion becomes easier and helps strain relief. The cable’s end becomes slightly thick due to the stiffener.

You can use these cables as a replacement for round cables. The flexible flat cables allow easy management of cables, particularly in high-flex applications. Further, FFC cables use less space, offer better RFI and EMI suppression, and eliminate wire coupling issues. On the other hand, in round cables, different materials wrap the conducting wires, making the cable heavy and stiff. On the contrary, conducting wires of FFC do not have any wrapping, and thus, the cable is lightweight and flexible.

Generally speaking, You can find an FFC cable in plotters, copiers, printed connections, scanners, DVD players, signal transmission, and plate board connections.

flat wires cables

Image: flat wires cables

Specifications of flexible flat cables

You can specify the flexible flat cables based on the following parameters.

Pitch:

Pitch is the space between the centers of the two conductors. An FFC cable may have dissimilar pitches as the distance among different conductors may differ. However, it is not very common. The different pitches of the FFC cables include 0.500mm, 0.625mm, 0.635mm, 0.8mm, 1.00mm, 1.25mm, 1.27mm, 2.0mm, and 2.54mm. However, the common ones are 0.5mm, 1.0mm, and 1.25mm. You can also get multiple pitches and custom pitches.

Type:

Würth Elektronik explains that some cables are Type 1, while Molex calls them Type A, where all the cable’s ends with exposed contacts are on a similar side. Another cable type is type 2/Type D, where the cable ends with exposed contacts on the cable’s reverse sides. As a result, if a cable lies flat, its first end has contacts facing up and another facing down.

Exposure length:

Exposure length refers to the length of the cable’s exposed contact at the cable’s termination point.

Stiffener:

Most FFC cables have stiffeners attached to the opposite sides of the cable’s exposed areas to allow LIF and ZIF connections.

Conductor size:

conductor size refers to the thickness and the width of the metal conductors.

flat ribbon wire cable

Image: flat ribbon wire cable

FPC vs. FFC: What are the differences?

You may get confused with the term FPC (Flexible Printed Circuit ) and FFC. Though FFC and FPC sound similar, they have different features and functionality.

  • Firstly, a flexible flat cable is an electrical cable that is flat and flexible, while a flexible printed circuit is a complicated circuit that incorporates different electronic components. 
  • Secondly, FFCs have multiple metallic conductors on a plastic base, while Flexible printed circuits comprise polyimide material with etched copper conductors. It is available in 0.3mm thickness and can tolerate severe conditions. 
  • The varieties of FFC cables include cables with 2 to 32 pins having varied insulation materials so you can use them in various applications. Some FFC cables are suitable for use in very high temperatures, for example, high-temperature jumper systems, which can operate well at 1500C.  On the other hand, different FPC include single-layer boards, double-layer, or multilayer flex boards. In single-sided flex circuits, you will see a single conductor of metal or any metal-filled polymer on a dielectric film. Double-sided flex circuits have two conductor layers, while circuits with three or more layers are flexible multilayer circuits. In these, layers connect using plated through holes. FPC in rigid printed circuit boards can provide flexibility in tightly packed electronic components. 

FFC/FPC Connector and Cable Compatibility Basics

FFC/FPC connectors and jumper cables are sold and used together in electronics. Thus, it is essential that you know and picks the best mating connector and cable that suits your applications in the best manner. 

First of all, you must pick a suitable FFC/FPC connector. If a connector has 30 circuits, you must also have 30 circuits. Similarly, a connector with 0.5mm distanced contacts will need a cable with a pitch of 0.50mm. With the right connector, you can choose a suitable cable. 

Make sure that you check the plating of the connector because it is essential to match the plating of the cable and the connector.

Knowing the circuit counts, plating, and pitch information, you must assess your application to pick the suitable cable.

  • Firstly, determine the distance between the two components you want to connect. For example, whether they are two PCBs, an LCD, a PCB, etc.
  • Secondly, determine which cable type (Type A with exposed contacts at the same end, Type D with exposed contacts at opposite ends) you need for your application.
  • Thirdly, determine how many motions a cable must endure in your application. You can take a thick cable with around 10,000 flex cycles if it is a static application. On the contrary, you will need a cable designed for at least 100,000 – 2.5 million flex cycles for a flexible application like a robotic arm.

Conclusion

FFC cables are the best cable alternatives in applications requiring high flexibility, dense packaging, and where you need to design small components. However, making the right choice is essential. If you have any doubt regarding the pitch, circuit counts, or cable plating, Cloom’s knowledgeable technicians can guide you well. We have a high quality of flexible flat cables in multiple lengths. Call us or email us and we will discuss your queries and suggest you the best possible solution.

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