Flexible electronics, also known as
flex circuits, is a
technology
for assembling
electronic circuits by mounting electronic
devices on
flexible
plastic
substrates, such as
polyimide,
PEEK or transparent
conductive polyester
film. Additionally, flex circuits can be
screen
printed silver circuits on
polyester.
Flexible electronic assemblies may be manufactured using identical components
used for rigid
printed circuit boards, allowing the board
to conform to a desired shape, or to flex during its use. These flexible
printed circuits (FPC) are made with a photolithographic technology. An
alternative way of making flexible foil circuits or
flexible flat cables (FFCs) is laminating very
thin (0.07 mm) copper strips in between two layers of PET. These PET
layers, typically 0.05 mm thick, are coated with an adhesive which is
thermosetting,
and will be activated during the lamination process. FPCs and FFCs have several
advantages in many applications:
- Tightly assembled electronic
packages, where electrical connections are required in 3 axes, such as cameras
(static application).
- Electrical connections where
the assembly is required to flex during its normal use, such as folding cell
phones (dynamic application).
- Electrical connections
between sub-assemblies to replace wire harnesses, which are heavier and
bulkier, such as in cars, rockets and satellites.
- Electrical connections where
board thickness or space constraints are driving factors.
·
Applications
·
Flex circuits are often
used as connectors in various applications where flexibility, space savings, or
production constraints limit the serviceability of rigid circuit boards or hand
wiring. A common application of flex circuits is in computer keyboards; most
keyboards use flex circuits for the
switch matrix.
·
In
LCD fabrication, glass is used as a
substrate. If thin flexible plastic or metal foil is used as the substrate
instead, the entire system can be flexible, as the film deposited on top of the
substrate is usually very thin, on the order of a few micrometres.
·
Most flexible circuits are
passive wiring structures that are used to interconnect electronic components
such as integrated circuits, resistor, capacitors and the like, however some
are used only for making interconnections between other electronic assemblies
either directly or by means of connectors.
·
In the automotive field,
flexible circuits are used in instrument panels, under-hood controls, circuits
to be concealed within the headliner of the cabin, and in ABS systems. In
computer peripherals flexible circuits are used on the moving print head of
printers, and to connect signals to the moving arm carrying the read/write
heads of disk drives. Consumer electronics devices make use of flexible
circuits in cameras, personal entertainment devices, calculators, or exercise
monitors.
·
Flexible circuits are found
in industrial and medical devices where many interconnections are required in a
compact package. Cellular telephones are another widespread example of flexible
circuits.
·
Flexible
solar cells
have been developed for powering
satellites.
These cells are lightweight, can be rolled up for launch, and are easily
deployable, making them a good match for the application. They can also be sewn
into backpacks or outerwear.
