FFC/FPC ribbon cables
(3 925)In the 1970s, flexible flat cables were universally used in connecting printed circuit boards. They have proved their reliability in many projects, including military and government ones. They have showed high reliability and worked well even in the harshest conditions – they were used for example in aviation, submarines, and even NASA projects..
FFC and FPC – what’s the difference?
The name flexible flat cables can be applied to any type of electrical cable that is flexible and flat, while FPC is in fact a flexible printed circuit.
Flexible flat cables are made of thin copper wires laminated rectangularly between two layers of polyester insulation. Copper conductive parts are left bare on each end, and then tinned, in order to ensure electric contact with the connector. Stiffener is fixed to cable’s end, which ensures mechanical stability of bare copper wires during the process of connecting and disconnecting the FPC.
Flexible printed circuits (FPC) are similar, in terms of construction, to ribbon cables, with the exception that the layer of copper has been etched chemically in order to obtain a specific pattern. These circuits are made on request for every type of application – different shapes and geometry may solve even the hardest problems with installation and the place provided for installation.
What can FFCs be used for?
Flexible flat cables are ribbon cables, named so because of their wide, flat structure. Usually those are simple connectors, without any additional elements. The ribbon cable is usually made of plastic film, on which conducting wires are placed. The space between centres of the wires is known as a pitch.
Thanks to the way in which they are designed and constructed, ribbon cables take less space and offer greater flexibility than round cables. Additionally, FFCs often offer better filtering of EMI/RFI.
They are usually used in densely packed electronic systems, especially in ones where high flexibility is needed, and the space is constrained. These are for example connections with a moving printhead, flip phones etc.
TME offers a wide range of ribbon cables that meet all specific requirements, including the number of tracks, cable pitch and its length.
FPC cables?
Flexible printed circuit is an example of flexible electronics and is made of flexible polymer base, on which a conductive circuit can be printed before sealing it with protective polymer layer. It is more than a cable and connector – FPC is a printed board that is lighter, thinner and offers greater flexibility in comparison to the traditional stiff PCB. Flexibility enhances durability and reliability, which makes it a perfect solution for use instead of a stiff circuit in highly flexible electronical elements or where weight and/or space are limiting factors. These are, for example, consumer electronics, hearing aids or flexible solar cells in satellites.
FFC – how to replace an old cable with a new one?
When replacing or choosing the ribbon cable, pitch is one of the main parameters. It comes in numerous variants, from 0.3 mm to 2.54mm. Here, it is important to understand what the pitch of an FPC cable and the interface on a printed board is.
Many beginners or those who have never had to do with the subject treat the space between the two end points of the connectors as a pitch, while in fact the pitch is the distance between cable wire axes or lead holes on a PCB. Even with this knowledge, it’s not easy to measure distance between the axes. However, it can be calculated with a simple mathematical formula:
Cable width = (number of wires in a cable + 1) x pitch
So, with a 5mm ribbon cable with 9 contacts, we can calculate easily that the pitch is 0.5mm.
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