FPC vs. FFC vs. Elastomer Strips
FPC and FFC are both cables used to carry signals from your processor (I/O) to the LCD.
One cable carries signal only, the other carries signal and has additional circuitry.
BREAKDOWN OF FPC AND FFC:
An FFC (Flexible Flat Cable) is a flat ribbon cable with contacts on both ends.
An FPC (Flexible Printed Circuit) is a flat circuit board in the form of a cable with contacts on both ends and added circuitry along the cable.
The job of an FFC is to transport a signal to/from the LCD to the customer’s product. They are custom in length and the contacts on the ends are straight and rigid to slip into a mating connector.
The contact area can face up, down or be located on both sides of the cable to allow additional signals. The cable is protected by a plastic film.
Its thin profile requires much less space than discrete wire cable assemblies.
Their flexibility allows the cable to bend and unbend repeatably without damaging the conductor or suffering signal degradation. Such as the lid of a flip phone that opens and closes many times (yes, we know how old those are).
They are mostly used in automated product manufacturing.
Flat cables provide better suppression of EMI/RFI (electromagnetic interference/ radio-frequency interference), which is unwanted noise/interference that can affect signals.
Flexible Printed Circuit (FPC) is a flexible cable like an FFC that is built to a custom length, but with added circuitry.
It is basically a flexible circuit board that also carries data signals from the LCD to the customer’s product.
No matter which cable type you choose, you need to select a pitch/spacing.
Pitch is the distance (center to center) of the conductors on each end of the cable. Standard pitches include .5mm, .635, .8mm, 1.0mm 2.54mm (.1 of an inch) and many other pitches.
The cable can contain different pitches on each end such as .5mm pitch on one end and a 1.25mm pitch on the other, but this would be a custom design.
Elastomer strips are commonly called Zebra strips (a brand name) because the conductors and insulators alternate between dark and light colors.
The conducive areas include silver, gold, and carbon materials. They are flexible (silicone rubber) and compressible.
Their flexibility acts as a shock absorber which is ideal for high shock and vibration applications.
They are built to a specific length, width, and height. It is possible to modify a strip with a sharp razor blade for prototyping, but not recommended for high volume production.
They fit between the LCD glass and PCB (Printed Circuit Board) or in some cases between two or more PCBs.
Segment and COB LCDs incorporate strips.
Segment displays consist of two layers of ITO glass with a nematic fluid between them. Letters, numbers, and icons are burned on to the glass.
The strips sit between the bottom layer of glass and the PCB for high volume, automated manufacturing.
COB means Chip On Board.
The controller/driver chip is mounted to the back of the PCB. The strip is compressed between the PCB and the LCD glass and held in place by a metal bezel.