Introduction to flexible flat cables | Explanation of the differences with FPC cables and types

In today's world where electronic devices are becoming increasingly miniaturized, the choice of wiring has become a critical factor in determining the success or failure of product development. Flexible flat cables in particular have been attracting attention at many development sites due to their characteristics, but a systematic understanding of appropriate selection criteria and applications is required.

In this article, we will provide a systematic explanation of flexible flat cables, from basic knowledge to usage scenarios. We hope that this article will help you understand the basics of flexible flat cables.

What is a flexible flat cable?

Flexible flat cables are thin, flexible, and flat wiring materials that can be easily fitted into tight spaces inside devices and are suitable for connecting to moving parts.

Its major feature is that it achieves both lightweight and low cost by arranging multiple conductors in parallel and sandwiching them between insulating films from above and below.

Although it does not have an external shield like a coaxial cable, it is widely used in laptops, printers, etc. because it can neatly bundle multiple signal lines.

It is easy to handle even in large-scale production sites and is highly valued as a cable that contributes to space-savings for a variety of equipment.

Types of flexible flat cables

There are several types of flexible flat cables depending on the usage environment and application.

The following are some typical types:

• Halogen-free flexible flat cable
• Gold-plated flexible flat cable
• Gold-plated shielded flexible flat cable

Let's take a look at each feature.

Halogen-free flexible flat cable

Halogen-free flexible flat cables are environmentally friendly cables made from materials that suppress the generation of harmful gases.

Conventional flexible flat cables sometimes contain halogen elements such as chlorine and bromine, which raises concerns that toxic gases may be generated when incinerated.

In contrast, halogen-free types reduce this risk by using materials that are less likely to emit harmful substances when burned.

It is attracting attention as a suitable option for areas with strict environmental regulations and for products where safety is a priority.

Halogen-free flexible flat cables are also effective when you want to improve recyclability or your corporate image.

Gold-plated flexible flat cable

Gold-plated flexible flat cables are cables in which the contact points are plated with gold to reduce contact resistance and stabilize transmission quality.

Gold is a metal that is resistant to oxidation and corrosion, so a major advantage is that its resistance value remains almost unchanged over a long period of time.

In medical equipment and precision instruments, there are many situations where even weak signals need to be communicated accurately, making this technology highly useful for such applications.

However, since the plating process tends to increase manufacturing costs, you will need to consider this in your budget.

However, for applications that require a high quality connection, gold-plated flexible flat cables may be the better choice.

Gold-plated shielded flexible flat cable

Gold-plated shielded flexible flat cables are high-performance types that combine the contact reliability of gold plating with external noise prevention provided by shielding.

In devices that handle video signals and high-speed data, electromagnetic interference can easily cause a decline in image quality and communication accuracy. Therefore, by using an external shield to prevent the intrusion of unnecessary noise and protecting the contacts with gold plating, stable transmission can be achieved over the long term.

Although the unit price is higher than that of general flexible flat cables, there is a possibility of achieving overall cost benefits in fields where you want to reduce cable replacements and troubles. The introduction of gold-plated shielded flexible flat cables is effective in fields that require high precision or in environments that are sensitive to noise.

The difference between flexible flat cables and FPC cables

A cable that is very similar to a flexible flat cable is the FPC cable.

FPC is an abbreviation for "Flexible Printed Circuits," which is called "flexible printed circuit board" in Japanese. Both are thin and flexible cables, but there are differences in their structure and characteristics.

Here we take a closer look at the differences between flexible flat cables and FPC cables.

	Flexible Flat Cable	FPC Cable
Construction	Multiple conductors are arranged at regular intervals and sandwiched between insulating films.	Copper foil pattern formed on polyimide substrate
Features	Simple structure, low cost	Allows circuit designs with complex shapes, including curves and meanders
Use	For devices that require simple signal wiring	For devices that require compact size and high density mounting
Benefit	Low manufacturing cost, easy connector connection	High degree of freedom in circuit design, high density mounting possible
Demerit	Low degree of freedom in wiring	High manufacturing costs, specialized knowledge and equipment required
Manufacturing process	Conductors are lined up and crimped with insulating film, a simple process with short lead times	Multiple processes include attaching copper foil to the board, etching it, and protecting it with coverlay.
Production Efficiency	Suitable for mass production	Manufacturing takes a lot of time and effort

Differences by Features

The basic structure of a flexible flat cable is that multiple conductors are arranged at regular intervals and sandwiched between insulating film.

On the other hand, FPC cables have copper foil patterns formed on a thin substrate such as polyimide, allowing you to freely design wherever you need it.

Therefore, FPCs allow for the design of complex circuit shapes, including curves and meanderings. However, when simple signal wiring is sufficient, flexible flat cables, which are low-cost and suitable for mass production, are often chosen.

FPCs are suitable for devices where miniaturization and multi-layer wiring are important, while flexible flat cables are suitable for simple wiring.

Advantages and disadvantages

The advantage of flexible flat cables is that they can be manufactured relatively inexpensively due to their simple structure, and because the conductors are arranged at regular intervals, they can be easily connected to connectors.

The disadvantage is that there is less freedom in wiring compared to FPC cables.

On the other hand, the advantage of FPC cables is that they offer a high degree of freedom in circuit design. Since they can be used to form fine wiring and complex circuits, they are suitable for applications that require high-density mounting.

The disadvantages are that the manufacturing costs tend to be higher than for flexible flat cables, and specialized knowledge and equipment are required for design and manufacturing.

Differences in manufacturing process

The main process for making a flexible flat cable is to line up the conductors, crimp them with an insulating film, and then process the connector contacts on both ends.

Because the work is simple, it is suitable for mass production and has the advantage of being able to deliver with a short lead time.

The production of FPC cables requires a process in which copper foil is first attached to a board, and then the pattern is etched to remove unnecessary areas.

Furthermore, multiple processes are added, such as protecting the surface with a coverlay and insulating layer. Because more manufacturing equipment and labor are required, the cost is generally higher than that of flexible flat cables.

Flexible Flat Cable Applications

Flexible flat cables are widely used for connecting the LCD display and circuit board of a laptop computer, wiring movable parts inside a printer, etc. They are easy to shape into a narrow space and can arrange the necessary signal lines in parallel, making them easy to assemble.

It is also increasingly being used for wiring in automobile instruments and various sensors, and is also widely used for connecting boards in flat-screen TVs.

By combining gold plating and shielding, noise resistance and contact stability can be improved, making this cable trusted in many fields. From the standpoints of productivity, cost, and space efficiency, it is likely to continue to attract attention in a variety of electronic devices.

Summary

Thin and highly flexible, flexible flat cables are used for the internal connections of various electronic devices. The conductors are arranged in parallel and sandwiched between insulating films, which allows for increased production efficiency while reducing costs.

In addition, a variety of specifications are available, such as halogen-free and gold-plated, making them suitable for situations where environmental considerations and long-term reliability are important.

In the future, demand is expected to increase in the areas of small mobile devices such as smartphones and wearable devices, as well as in the area of ​​in-vehicle equipment due to the development of autonomous driving technology.