Under an electron microscope, the surface of electrolytic copper is extended with undulating ripples of
0.05 microns, and these invisible dimensional features determine the limits of the material's electrical
conductivity. From giant busbars for power transmission to nanoscale wires inside chips, the precision
control of electrolytic copper dimensions is like the invisible ruler of modern industry, supporting the
energy revolution and the iterative development of electronic technology. The global high-end
manufacturing requirements for electrolytic copper size tolerance has exceeded ± 0.5μm, this seemingly
simple geometric parameters, in fact, is the integration of metallurgy, machinery, chemistry and other
multidisciplinary cutting-edge issues.
Industrial Standards for Dimensional Parameters
International standard system to build a quality framework. ASTM B115 stipulates that the thickness tolerance
of electrolytic copper plate is ± 0.5%, and ISO 2098 limits the waviness of electrolytic copper foil to 3mm/m.
High-precision copper strip implements EN 13599 standard, and the parallelism deviation of 0.1mm thickness
products needs to be less than 0.001mm.
Thickness control technology realizes nano breakthrough. The surface roughness of cathode rollers is reduced
to Ra0.1μm, so that the thickness fluctuation of electrolytic deposition layer is controlled at ±0.3μm. The
titanium-based cathode master plate prepared by magnetron sputtering coating technology enhances the
thickness uniformity of 0.006mm ultra-thin copper foil to 98%.
Geometric precision graded to match application scenarios. The thickness tolerance of copper rows for electric
power is relaxed to ±0.1mm, while the flatness of copper plates for semiconductor targets needs to reach
0.01mm/m². The chamfer radius of the battery connecting piece for new energy vehicles is required to be
accurate to R0.05±0.005mm.
Process code for size formation
Electrolysis parameters regulate the crystal growth dimension. When the current density is increased from 250A/m²
to 380A/m², the copper grain size is refined from 50μm to 12μm, and the material ductility is increased by 30%. For
every 5 ppm increase in the concentration of the additive sodium dodecyl sulfate, the surface roughness of the
copper foil is reduced by 0.02 μm.
Equipment precision determines the size boundary. The roundness error of cathode roll is less than 0.003mm,
ensuring that the thickness of copper foil fluctuates within 1%. Electrolyzer electrode parallelism deviation control
needs to be up to 0.05mm/m, otherwise it will cause edge thickening effect.
Post-treatment process to improve the dimensional characteristics. After the electrolytic copper plate is straightened
by three rolls, the flatness is improved from 0.3mm/m to 0.05mm/m. The surface polishing process adopts diamond
abrasive with a grain size of 0.25μm, which can reduce the roughness of copper strip from Ra0.8μm to Ra0.05μm.
Revolution in the application of dimensional standards
The power transmission field reconstructs the conductor specification. Rectangular copper rows with ±0.05mm
precision increase the utilization of substation space by 40%, and electromagnetic coil loss made of ultra-flat
copper tape is reduced by 15%. The oval degree of copper pipe for extra-high voltage projects is required to be
less than 0.1%, and the guaranteed current-carrying capacity has been raised to 6,500A.
The electronics industry has spawned micro-size standards: the flatness of 5G base station heat dissipation
copper sheets needs to reach 0.01mm, and the tolerance of IC packaging copper column diameter is required
to be ±1μm. The thickness of copper foil for flexible circuit boards has exceeded the limit of 6μm, and the
surface roughness of Ra is ≤0.3μm.
New energy equipment rewrite material specifications. Power battery lug copper strip thickness tolerance tightened
to ±2μm, photovoltaic welding strip copper diameter fluctuations need to be less than 0.5%. Hydrogen fuel cell
bipolar plate runner copper sheet depth tolerance required ±5μm.
When the laser micrometer draws a 0.01mm inspection grid on the surface of the copper foil, behind those
jumping numbers are the precision coupling of countless process parameters. From the 10,000-ton electrolysis
workshop to the nano-scale processing center, the evolutionary history of electrolytic copper size is the epitome
of human conquest of the material limit. This size code embedded in the metal atoms will continue to unlock
new possibilities in the field of high-end manufacturing, and outline a finer scale on the precision map of
industrial civilization.