Structure of FPC
According to the number of layers of conductive copper foil, FPC can be divided into single
Layer circuit, double layer circuit, multi-layer circuit, double sided and so on. 

Single-layer structure: the flexible circuit of this structure is the simplest structure of the
Flexible PCB. Usually the base material (dielectric substrates) + transparent rubber(adhesive)
+ copper foil is a set of purchased raw materials(semi-manufactures), the protective film
and transparent glue are another kind of bought raw material. First, copper foil must be
Etched to obtain the required circuit, and the protective film should be drilled to reveal
the corresponding pad. after cleaning, the two are combined by rolling. Then the exposed
Part of the pad electroplated gold or tin to protect. In this way, the big panel board will
Be ready. Generally also it's stamped into the corresponding shape of the small circuit
Board. There is also no protective film directly on the copper foil, but printed resistance
Soldering coating, so that the cost will be lower, but the mechanical strength of the circuit
Board will become worse. unless the strength requirement is not high and the price needs
to be as low as possible, it is best to apply the protective film method. 

Double layer structure: when the circuit is too complex to be wired, or copper foil is needed
to shield the ground, it is necessary to choose a double layer or even a multilayer. the most
Typical difference between a multilayer and a single plate is the addition of a perforated structure
to connect the layers of copper foil. the first process of transparent rubber + base material +
Copper foil is to make holes. Drill holes in the base material and copper foil first, clean and then
Plated with a certain thickness of copper. the subsequent fabrication process is almost the same
as the single-layer circuit. 

Double sided structure: both sides of the double sided FPC have pads, mainly used to connect
Other circuit boards. Although it and monolayer structure is similar, but the manufacturing
Process is very different. Its raw material is copper foil, protective film and transparent glue.
the protective film should be drilled according to the position of the pad first, then the copper
Foil should be affixed, the pad and track lines should be etched and then the protective film
of another drilled hole should be affixed.



FPC Case: Flexible Printed Circuit (FPC) Built on 2oz
Polyimide for Analog Controller
(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 2oz polyimide for the
Application of Analog Controller.

Basic specifications
Base material: Polyimide 25m
Layer count: 2 layers
Type: Individual FPC
Format: 97mm x 51.5mm = 1 type = 1 piece
Surface finish: Immersion gold
Copper weight: Outer layer 70m/ Inner layer 0 m
Solder mask / Legend: Yellow coverlay / White
Final PCB height: 0.25 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
Controllability of electrical parameter design;
the end can be whole soldered;
Low cost;
High solderability, no stressing of circuit boards and less contamination of PCB surface;
Meeting your PCB needs from prototype to mass production;
RoHS materials;
Eligible products rate of first production: >95%  
Customer complaint rate: <1% 

Application
Capacitive touch screen / panel, Toy lamp strip, industrial surveying and mapping
Instrument, medical equipment controller, Toy lamp strip, industrial control audio
Equipment

General Properties of Coverlay

Test Item		Treatment Condition	Unit	Property Date
				IPC Standard * value	Typical Value
					SF305C 0205	SF305C 0309
Resin Flow		A	mm	-	0.15	0.15
Peeling Strength (90)		A	N/mm	0.7	0.82	1.06
		288, 5s		0.53	0.80	1.11
Thermal Stress		288, 20s	-	-	No Delamination	No Delamination
Dimensional Stability	MD	after peeling off the paper	%	0.2	0.1	0.1
	TD				0.1	0.1
Chemical Resistance		after Chemical Exposure	%	80	90	90
Volume Resistvitiy		C-96/35/90	M-cm	10^6	7.8 x 10^6	2.2 x 10^7
Surface Resistance		C-96/35/90	M	10^4	2.5 x 10^5	4.2 x 10^5

Explanations:
C = Humidity conditioning;
E = Temperature conditioning;
1. Testing after laminating with shining side of copper foil in suitable condition;
* Certified to IPC-4203/2 Epoxy adhesive on one or two sides of polyimide dielectirc

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

Film Exposure machine