Three Common sense of Flexible circuit board

Flexible circuit board Product description

Flexible circuit board (FPC) is made of a kind of laminated material that has insulation to resist heat, electrical properties, metal foil, and adhesive. Usually, conductive bumps allow conductivity between the flexible circuit board and another circuit board by pressing the bumps to pads with pressure. This creates electric flow between the systems. Flexible circuit boards are known for their lightness, thinness, flexibility, and convenience in size.

FPC has several advantages in many applications:
1) Tightly assembled electronic packages, where electrical connections are required in 3 axes, such as cameras (static application).
2) Electrical connections where the assembly is required to flex during its normal use, such as folding cell phones (dynamic application).
3) Electrical connections between sub-assemblies to replace wire harnesses, which are heavier and bulkier, such as in cars, rockets and satellites.
4) Electrical connections where board thickness or space constraints are driving factors.

Applications of Flexible circuit board

> FPCs 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. In addition to cameras, a common application of flex circuits is in computer keyboard manufacturing; most keyboards made today use flex circuits for the switch matrix.

Common structures of Flexible circuit board

1) Single side:
   A single-conductor flex circuit is often employed as an inter-connect, either using connectors, or soldered directly to pads on the board using techniques such as hot bar soldering.  
 2) Double sides:
Flex circuits with two conductive layers can be made with or without plated through-holes, though through-holes are usually provided. As with the single-layer circuit, apertures can be cut in the cover layer to allow assembly on one or both sides.
 3) Single side double access
Applied with single sided material to make pattern but make some window on base film and add on cover layer on pattern top. The final products will have single layer copper but two side access possibility. This structure we call that single side double access boards.  
 4) Single side plus single side
Binding two single sided FPC by end point joint. The bending area will be non adhesive for getting better flexibility. This structure so called single side plus single side with air gap.
 5) Multi-layers
 Binding several boards together so called Multi-layer and the drawing show here is an example of binding a single sided and a double sided FPC together.
6) COF (Clip-on-film)
7) Rigid-flex board