Shengyi SF202 2-Layer 0.118mm Flexible PCB FPC ENEPIG RA Copper

1.Introduction to SF202 2-Layer Flexible PCB

This 2-layer flexible printed circuit (FPC) is constructed with Shengyi SF202 as the base material. SF202 is an adhesiveless double side flexible copper clad laminate (FCCL) featuring excellent soldering reliability, dimensional stability, and chemical resistance. The board uses RA copper (rolled and annealed copper) which provides much higher flexibility and better flex life endurance than ED copper, making it ideal for dynamic applications. The finished board thickness is 0.118mm with ENEPIG surface finish (Electroless Nickel Electroless Palladium Immersion Gold), green liquid solder mask on both sides, no silkscreen, and 0.1mm minimum hole size.

2.Key Features of SF202 Flexible Laminate

Excellent soldering reliability, dimensional stability and chemical resistance
Excellent mechanical and electrical properties
Halogen free
Flammability rating: UL 94 VTM-0
Compatible with EU RoHS directive (free of Pb, Hg, Cd, Cr6+, PBB, PBDE)
Peel strength: 1.2 N/mm
Thermal stress: Pass
Dimensional stability: MD 0.01%, TD 0%
Chemical resistance: 85%
Moisture absorption: 1.3%
Volume resistivity: 4.8 x 10⁸ MΩ·cm
Surface resistance: 1.2 x 10⁶ MΩ
Dielectric constant (1 GHz): 3.2
Dissipation factor (1 GHz): 0.007
Dielectric strength: 150 V/μm
MIT folding endurance (with coverlay): >2000 times

3.Benefits of This 2-Layer Flexible PCB

RA copper provides superior flexibility and flex life for dynamic applications
Adhesiveless polyimide construction ensures excellent dimensional stability and heat resistance
ENEPIG surface finish offers excellent corrosion resistance, wire bondability, and solderability
Liquid green solder mask provides reliable insulation and protection
Halogen free and RoHS compliant for environmental compliance
UL 94 VTM-0 flammability rating for safety
Low moisture absorption (1.3%) for consistent electrical performance
High dielectric strength (150 V/μm) for reliable insulation
Excellent chemical resistance (85%) for harsh environments

4.SF202 2-Layer Flexible PCB Construction Details

5.PCB Stackup (2-Layer Flexible Structure)

Top Liquid Green Solder Mask: 0.010 mm
Top Copper Layer: RA Copper (Base 12μm + plating), total 0.022 mm
Polyimide Core: SF202 Adhesiveless, 0.050 mm
Bottom Copper Layer: RA Copper (Base 12μm + plating), total 0.022 mm
Bottom Liquid Green Solder Mask: 0.010 mm

Finished thickness: 0.114 mm (nominal), 0.118mm typical

6.Primary Application Areas

Computers
Mobile phones
Digital cameras
Video recorders (VCR)
Flat panel displays
Apparatus and instruments
Automotive electronics
High-end electronic products

7.Quality Assurance

Artwork supplied: Gerber RS-274-X
Accepted standard: IPC-Class-2
Availability: Worldwide

8.SF202 Flexible Laminate – Product Introduction

SF202 is an adhesiveless double side flexible copper clad laminate (FCCL) from Shengyi. It features excellent soldering reliability, dimensional stability, and chemical resistance. The material exhibits excellent mechanical and electrical properties. SF202 is halogen free with flammability rating UL 94 VTM-0, and is compatible with EU RoHS directive, free of Pb, Hg, Cd, Cr6+, PBB, PBDE. The material is certified to IPC-4204/11 Copper Clad Adhesiveless. SF202 is supplied in rolls with standard width of 250mm or 500mm and roll length of 50m or 100m. Storage conditions: stored in dry room with humidity control and no corrosive gases, at temperature 5-35°C and humidity below 75% for one year in original packaging.

9.Features and Benefits of SF202

Benefits:

Excellent soldering reliability for robust assembly
Excellent dimensional stability for precise circuit fabrication
Excellent chemical resistance for harsh environment applications
Halogen free and RoHS compliant for environmental requirements
High electrical strength for reliable insulation
Low moisture absorption for consistent performance
High folding endurance for dynamic flex applications

10.SF202 Data Sheet

11.Some Typical Applications

Computers
Mobile phones
Digital cameras
Video recorders (VCR)
Flat panel displays
Apparatus and instruments
Automotive electronics
High-end electronic products

12.Copper Foil Types for FPC (Educational Section from Source)

ED Copper (Electro-Deposited):
ED copper is produced in the same way as copper foil used for rigid printed circuit boards. It has a vertical grain structure due to the electrolytic process, which implies relatively low ductility. ED copper is not recommended for dynamic applications. Common thicknesses: 17.5, 35, 70, 105 and 175 μm (0.5, 1, 2, 3 and 5 oz).

RA Copper (Rolled and Annealed):
RA copper is produced from electrolytically deposited cathode copper, melted and cast into ingots, then hot-rolled, cold-rolled and annealed. It has a horizontal grain structure which provides much higher flexibility and better flex life endurance than ED copper. RA copper should always be used for dynamic applications. A disadvantage is that the bonding surface is fairly smooth, but bond can be enhanced by an electrolytic copper flash. Common thicknesses: 17.5, 35, 70, 105 and 175 μm (0.5, 1, 2, 3 and 5 oz).

Solder Mask Types for FPC (from Source)

Film Coverlay: A polyimide film with adhesive that is laminated onto the circuit.

Liquid Solder Mask Ink: Liquid photoimageable solder mask applied by screen printing or spray coating. This product uses liquid green solder mask ink.