Civen Metal Material (Shanghai) Co., Ltd. is one of the leading manufacturers and suppliers of 35μm high-precision ra copper foil in China. Welcome to buy bulk durable 35μm high-precision ra copper foil made in China here from our factory. If you have any enquiry about cooperation, please feel free to email us.
35μm High-Precision RA Copper Foil is a fully annealed rolled copper foil for electronic and electrical applications where thickness control, conductivity, and flexibility all matter. At a nominal thickness of 35μm, it can be processed into conductive layers, shielding components, and other precision copper parts.
The material goes through precision ingot casting, multi-pass cold rolling, and controlled-atmosphere annealing. The rolling and annealing sequence produces an equiaxed grain structure and keeps the foil stable during subsequent etching, forming, and slitting operations.
For other thicknesses in this product range, see High-Precision RA Copper Foil.
Material and Metallurgical Condition
The base material is high-purity electrolytic copper with Cu ≥99.99%, using UNS C11000 or C10200 grades.
The finished foil is fully annealed in the O temper. Its equiaxed grain structure gives the material relatively high elongation and good resistance to repeated bending. Vacuum induction melting is used during material preparation to limit oxygen and trace metallic impurities that may contribute to pinholes or micro-cracks during rolling.
Thickness and Surface Control
The nominal thickness is 35μm, with thickness variation controlled within ±0.8μm in both the transverse and longitudinal directions.
The two sides of the foil have different surface profiles. The shiny side is specified at ≤0.8μm Rz, while the matte side is ≤1.5μm Rz. This relatively low surface profile is suitable for fine-line circuit processing, with the current product specification indicating processing capability down to 20μm pitch under suitable conditions.
Residual oil is limited to ≤0.5mg/m² after finishing, helping maintain a clean surface for subsequent processing.
Mechanical and Electrical Properties
The tensile strength range is 250–320MPa, while longitudinal elongation is ≥25%.
For applications involving repeated movement or bending, the higher elongation of the fully annealed foil allows the copper layer to deform without becoming excessively brittle.
Electrical conductivity is ≥100% IACS at 20°C. This makes the material suitable where the copper layer needs to carry current while keeping electrical resistance low.
Technical Specifications
|
Parameter |
Specification Value |
Test Standard |
|
Nominal Thickness |
35 um (Tolerance: +/- 0.8 um) |
IPC-TM-650 2.2.19 |
|
Width Range |
20 mm – 600 mm (Customizable) |
Mechanical gauge |
|
Tensile Strength |
250 – 320 MPa |
ASTM E8 / IPC-TM-650 2.4.18 |
|
Elongation |
>= 25% |
ASTM E8 |
|
Surface Roughness (Rz) |
Shiny side <= 0.8 um; Matte side <= 1.5 um |
ISO 4287 |
|
Electrical Conductivity |
>= 100% IACS at 20°C |
ASTM B193 |
|
Residual Oil Content |
<= 0.5 mg/m2 |
Solvent extraction test |
Production and Quality Control
Thickness is regulated during rolling with multi-high mills and automatic gauge control. After rolling, the foil is annealed in a hydrogen-nitrogen atmosphere.
Surface inspection is carried out online during production and slitting. The inspection system checks for pinholes, scratches, edge cracks, and other visible defects.
Laboratory checks include tensile testing, chemical purity analysis by atomic absorption spectroscopy (AAS), and surface topography measurement by atomic force microscopy (AFM).
Production is carried out under ISO 9001 and IATF 16949 quality management systems, with lot-level traceability maintained for finished material.
Applications
Flexible Printed Circuits
The 35μm gauge can be used for conductor layers in multilayer and dynamic FPC constructions, including electronics requiring repeated flexing.
Battery Components
The foil is suitable for selected current-collector applications in pouch and cylindrical lithium-ion cells where conductivity and mechanical stability are required.
EMI Shielding
35μm copper foil can be processed into tape or wrap structures for electromagnetic shielding in coaxial cables and electronic equipment.
Transformer Windings
The material can also be used as a foil conductor in compact high-frequency transformer designs.
Customization & Supply
Slit widths can be adjusted for different converting and processing equipment. Slitting accuracy is maintained at ±0.1mm, with burr-free edges.
Available surface treatments include anti-tarnish passivation, chemical roughening, and bonding-promotion coatings. These options can be matched to substrates such as polyimide, PET, and epoxy.
The foil can be supplied on 3-inch or 6-inch plastic or aluminum cores. Depending on width and production requirements, continuous splice-free coil lengths can reach up to 3000 meters.
Packaging & Delivery
Finished coils are vacuum-sealed in anti-static multilayer aluminum foil bags with active desiccant to reduce moisture exposure during storage and transportation.
Master coils and slit rolls are secured in heavy-duty wooden crates with edge protection and cushioning. Each coil is marked with a QR code or barcode for production traceability, including information such as heat number, thickness profile, test data, and manufacturing time.
FAQ
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