Components of a flexible circuit
A flexible circuit consists of copper foil, dielectric substrate+ coverlay and adhesive.
Copper foil is available in two different types of copper: ED Copper and RA copper.

ED copper is an electro-deposited (ED) copper foil produced in the same way as the copper
Foil used for rigid printed circuit boards. this also means that the copper is " treated", i.e., it
Has a slightly rough surface on one side, which ensures a better adhesion when the copper
Foil is bonded to the base material.
RA copper is a rolled and annealed copper foil produced from electrolytically deposited cathode
Copper, which is melted and cast into ingots. the ingots are first hot-rolled to a certain size and
Milled on all surfaces. the copper is then cold-rolled and annealed, until the desired thickness is
Obtained.
Copper foil is available in thickness of 12, 18, 35 and 70 m.

the most common available for dielectric substrate and coverlay is polyimide films. this material
Can also be used as coverlay. Polyimide is best suited for flexible circuits because of its
Characteristics as stated below:
High temperature resistance allows soldering operations without damaging the flexible circuits
Very good electrical properties
Good chemical resistance
Polyimide is available in thicknesses of 12.5, 20, 25 and 50 m.

Base laminates for rigid printed circuit boards are copper foils laminated together with the
Base materials, the adhesive coming from the prepreg material during lamination. Contrart
to this is the flexible circuit where the lamination of the copper foil to the film material is
Achieved by means of an adhesive system. It is necessary to distinguish between two main
Systems of adhesive, namely thermoplastic and thermoset adhesives. The choice is dictated
Partly by the processing, and partly by the application of the finished flexible circuit.



FPC Case: Flexible Printed Circuit Board FPC Built on
Polyimide Film with Double Layer Structure
(Flexible printed circuits 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. It's a 2 layer FPC
at 0.2mm 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 part.

Parameter and data sheet

Size of Flexible PCB	120.18 X 30.28mm
Number of Layers	2
Board Type	Flexible PCB
Board Thickness	0.20mm
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
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
Offer small quantity, prototypes and production.
DDU Door to door shipment with competitive shipping cost.



Application
Capacitive touch screen / panel, industrial control interphone, Consumer electrostatic
Bracelet soft board


Variety of PCBs


Legend inkjet printer