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 PCB | Impedance controlled Flex
PCB | Polyimide Flex PCB
(Flexible printed circuits are custom-made products, the picture and parameters shown
Are just for reference)

General description
this is a type of flexible PCB built on polyimide 76 micron substrate with 90 ohm impedance
Controlled on 0.15mm/0.3mm track and gap for the application of Wireless Broadband. It's
Standard 0.20 mm thick with yellow solder mask (coverlay) on both sides and immersion
Gold are on pads. FR-4 as stiffener is on the head and tail. the base material is used from
Shengyi, entire board supplying 1 up flex per panel. They're fabricated per IPC 6012 Class
2 using supplied Gerber data. Each 25 pieces are packed for shipment. 

Parameter and data sheet

PCB Size:	116 X 108mm = 1 PCS
Number of Layers	2 layers
Board Type	Flexbile PCB
Board Thickness	0.2mm +/-10%
Stackup	TOP FR-4 Steffener 0.8mm
	PI coverlay 0.025mm
	Copper top 0.035mm finish
	Polyimide substrate 0.076mm
	Copper top 0.035mm finish
	PI coverlay 0.025mm
Board Material Supplier	Shengyi
Tg Value of Board Material	60
PTH Cu thickness	20 um
Inner Iayer Cu thicknes	N/A
Surface Cu thickness	35 um (1oz)
Coverlay Colour	Yellow
Number of Coverlay	2
Thickness of Coverlay	25 um
Stiffener	FR-4 0.8mm
Type of Silkscreen Ink	N/A
Supplier of Silkscreen	N/A
Color of Silkscreen	N/A
Number of Silkscreen	N/A
Minimum via (mm)	0.3
Minimum Trace (mil)	5.90
Minimum Gap(mil)	11.8
Surface Finish	Immersion Gold
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
Type of artwork to be supplied	Email file, Gerber RS-274-X, PCBDOC etc
Service area	Worldwide, Globally.

Features and benefits
Excellent flexibility;
Reducing the volume;
Weight reduction;
Consistency of assembly;
Increased reliability;
Powerful PCB capabilities support your research and development, sales and marketing;
Delivery on time with higher than 98% on-time-delivery rate;
Team with passion, discipline, responsibility and honesty;
No minimum order quantity. 1 piece is available;


Application
Flexible flat cable, Industrial control temperature controller soft board, medical equipment
Controller, automobile GPS navigation flex board, tablet keypad flex board, display backlight


FPC

Workshop environment