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. Contrary
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 (FPC) Built on 1oz
Polyimide for display carrier
(Flexible printed circuits are custom-made products, the picture and parameters shown
Are just for reference)

General description
this is a type of 2 Layer flexible printed circuit (FPC) built on 1oz polyimide for the
Application of display carrier.

Basic specifications
Base material: Polyimide 25m + 0.3mm stiffener of FR-4 and 0.1mm Stainless steel
Layer count: 2 layers
Type: Individual FPC
Format: 92.1mm x 54mm = 1 type = 1 piece
Surface finish: Immersion gold
Copper weight: Outer layer 35m/ Inner layer 0 m
Solder mask / Legend: Black coverlay / White
Final PCB height: 0.5 mm
Standard: IPC 6012 Class 2
Packing: 100 pieces are packed for shipment. 
Lead time: 10 working days
Shelf life: 6 months

Features and benefits
the end can be whole soldered;
Low cost;
Continuity of processing;
Excellent surface planarity to reduce failure rate during assembly and soldering;
Meeting your PCB needs from prototype to mass production;
Powerful PCB capabilities support your research and development, sales and marketing;
Delivery on time higher than 98% on-time-delivery rate;
More than 15 years of PCB experience;

Application
Keypad FPC, LCD module, Industrial control computer soft board, FFC for industrial
Control equipment

Specifications of standard coverlay

Specifications	Polyimide Film Thickness (m)	Adhesive Thickness (m)	Applications
SF305C 0205	5	5	Ultrathin FPC
SF305C 0305	7.5	5
SF305C 0309	7.5	9
SF305C 0515	12.5	15	General type
SF305C 0520	12.5	20
SF305C 0525	12.5	25
SF305C 1025	25	25
SF305C 1030	25	30
SF305C 1035	25	35	Power batter
SF305C 1050	25	50
SF305C 2050	50	50

Product Code Description
SF305C 05 15
SF305C: Shengyi Coverlay Designation
05: PI Film Thickness, 05- 12.5m; 10-25m
15: Adhesive Thickness, 15-15m, 25- 25m; 35- 35m


FPC

FPC drilling