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? ? Electrolytic copper foil The varieties of electrolytic copper foil can be divided into standard electrolytic copper foil (sTD type), high ductility electrolytic copper foil (HD type), high temperature and high ductility electrolytic copper foil (HTE type) and annealed electrolytic copper foil (ANN type) according to their properties. According to the surface conditions, there are four kinds of rust prevention: surface untreated, surface untreated, single-sided and double-sided. From the thickness direction, the thin electrolytic copper foil with thickness less than 12um is called. In order to avoid the error in thickness measurement, it is also expressed by the weight per unit area, such as the common 18 and 35um electrolytic copper foil, whose unit weight is 153 and 305g/m2 respectively. The quality standards of commercial electrolytic copper foil include purity, resistivity, strength, elongation, solderability, porosity, surface roughness, etc.

The production process of electrolytic copper foil is divided into three parts: preparation of electrolyte, electrolysis and post-treatment.

The purity of electrolyte preparation will be higher than 99 8% of the copper material is put into the copper dissolving tank after degreasing, mixed with the sulfuric acid steamer, and dissolved into copper sulfate. When the concentration meets the requirements, it will be transferred to the liquid storage tank, and the liquid storage tank will be connected with the electrolytic tank through pipes and pump sets to form a solution circulation system. After the bath solution circulation is stable, the electrolyzer can be electrified for electrolysis. An appropriate amount of surfactant shall be added to the electrolyte to ensure the particle size value, crystal crystallization direction, roughness, porosity and other indicators of the copper foil.

The electrode and cathode used in electrolysis process is a rotatable drum, called cathode roller; The movable headless metal belt can also be used as the cathode. The copper starts to deposit on the cathode after being electrified. Therefore, the width of the wheel and belt determines the width of the electrolytic copper foil. The copper deposited on the cathode is continuously stripped off,

After cleaning, drying, trimming, coiling and inspection, the qualified ones will be sent for post-processing. The anode for electrolysis is insoluble lead or lead alloy. In addition to the running speed of the cathode, the electrolytic process parameters include the concentration and temperature of the electrolyte, and the cathode current density during electrolysis. For example, when producing 25um electrolytic copper foil, the electrolyte should contain CuSO4.? 5H20150~280g/1. and H2S04.100~110g/1 The temperature is 40~- 60 ° C. The cathode current density is 1600~300A/m2

The cathode roll is formed by spinning titanium plate. Because titanium has high chemical stability and high strength, electrolytic copper foil is easy to peel off from the roll surface and has low porosity. The titanium cathode will also be passivated during electrolysis, so it needs to be cleaned regularly. Grinding, polishing, nickel plating and chromium plating. Corrosion inhibitors, such as nitro or nitroso aromatic or aliphatic compounds, can also be added to the electrolyte to slow down the passivation rate of titanium cathode. Stainless steel cathodes are also used to reduce costs.