Clarifications of FPC
According to the combination of base material and copper foil, flexible circuit board can
Be divided into two types: flexible board with adhesive and flexible board without adhesive.
the price of non-adhesive flexible PCB is much higher than that of adhesive flexible PCB,
but its flexibility, bonding force between copper foil and substrate and flatness of solder are
Also better than that of adhesive flexible PCB. So it is only used in the high demand situations,
Such as the: COF (CHIP on FLEX, flexible board with bare chip, the high flatness of the pad)
and so on. Because its price is high, most of the flexible PCBs used in the market are still
Adhesive flexible circuit board. Because the flexible circuit board is mainly used in the situation
Where bending is required, if the design or process is not reasonable, it is easy to produce
Micro-cracks, welding and other defects.

Economy of using FPC
If the circuit design is relatively simple, the total volume is small, and the space is suitable,
the traditional internal connection is much cheaper. Flexible circuits are a good design option
If the circuit is complex, processes many signals or has special electrical or mechanical
Requirements. When the size and performance of applications exceed the capacity of rigid
Circuits, flexible assembly is the most economical. A 12mil pad with a 5mil through hole
and a flexible circuit with 3mil lines and spacing can be fabricated on a thin film. Therefore,
It is more reliable to mount the chip directly on the film. There is no flame retardant that
Could be an ion source. these films may be protective and solidified at higher temperatures
to obtain higher glass transition temperatures. Flexible materials are less costly than rigid
Materials because they are free of connectors.


FPC Case: Single Layer Flexible FPC with 3M Tape for
Keypad Membrane
(FPC's are custom-made products, the picture and parameters shown are just for reference)

General description
this is a type of flexible printed circuit for the application of keypad membrane. It's a single
Layer FPC at 0.1mm thick. the base laminate is from ITEQ, It's fabricated per IPC 6012 Class
2 using supplied Gerber data. Polyimide stiffener is applied on the inserting head.

Parameter and data sheet

Size of Flexible PCB	67.23 X 50.56mm
Number of Layers	1
Board Type	Flexible PCB
Board Thickness	0.10mm
Board Material	Polyimide 25m
Board Material Supplier	ITEQ
Tg Value of Board Material	60
PTH Cu thickness	20 m
Inner Iayer Cu thicknes	N/A
Surface Cu thickness	35 m
Coverlay Colour	Yellow
Number of Coverlay	2
Thickness of Coverlay	25 m
Stiffener Material	Polyimide stiffner / 3M tape
Stiffener Thickness	0.2mm
Type of Silkscreen Ink	IJR-4000 MW300
Supplier of Silkscreen	TAIYO
Color of Silkscreen	White
Number of Silkscreen	1
Peeling test of Coverlay	No peelable
Legend Adhesion	3M 90 No peeling after Min. 3 times test
Surface Finish	Immersion Gold
Thickness of Nickle/Gold	Au: 0.03m(Min.); Ni 2-4m
RoHS Required	Yes
Famability	94-V0
Thermal Shock Test	Pass, -25125, 1000 cycles.
Thermal Stress	Pass, 3005,10 seconds, 3 cycles. No delamination, no Blistering.
Function	100% Pass electrical test
Workmanship	Compliance with IPC-A-600H & IPC-6013C Class 2

Features and benefits
Excellent flexibility
Reducing the volume
Weight reduction
Consistency of assembly
Increased reliability
Controllability of electrical parameter design
the end can be whole soldered
Material optionality
Low cost
Continuity of processing
Diversified shipping method
Customer complaint rate: <1% 


Application
Telephone receiver / earphone FPC, LCD TV soft board, Digital camera soft board, Tablet
PC module soft board