Surface coarsening method and surface coarsening liquid for copper foil

Abstract

A roughening treatment method for copper foil comprises: a stage A where an acidic solution containing sulfuric acid comprising at least one roughening additional substance as a heterocyclic compound having a chemical structure represented by the formula in each molecule and also having two or more cyclic structures is prepared as a treatment liquid for roughening treatment; and a stage B where one side or both the sides of copper foil are subjected to cathode treatment at the critical current density or higher using the acidic solution containing sulfuric acid, and projection-shaped copper electrodeposited material is formed on the surface of the copper foil. The invention provides a roughening treatment method where uniform roughened particles having no danger of falling can be obtained in a short time, the obtained roughened particles have low roughness and high adhesion with resin or the like, and productive efficiency is high even to thin copper foil, and to provide a treatment liquid used in the roughening treatment method for the copper foil.

Description

technical field [0001] The present invention relates to a method for surface treatment of copper foil, and more particularly, to a method for roughening the surface of copper foil having low roughness, improving adhesion to resin, etc., and efficiently producing thin copper foil. Moreover, this invention also relates to the roughening treatment liquid used for the above-mentioned roughening treatment method. Background technique [0002] Copper foil is widely used as a printed circuit board application and as a current collector of secondary batteries. Copper foil is roughly divided into rolled copper foil and electrolytic copper foil according to the manufacturing method. [0003] Rolled copper foil is manufactured by rolling a copper ingot to a target thickness with a calender, and winding it. [0004] In addition, the electrodeposited copper foil is manufactured by electrolytically depositing copper of a desired thickness from a copper electrolytic solution with an elect...

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Problems solved by technology

[0027] In addition, in JP-A-2002-69691, a method for forming a rough surface from a sulfuric acidic copper electrolytic bath containing polythionic acid, thiosulfate, and polythionate is reported. Anodes in which thio-inorganic compounds are insoluble, the additives are consumed very quickly due to oxygen bubbles generated at the anode, the bath is unstable, and the decomposition products need to be continuously removed

[0028] In addition, many techniques for roughening treatment with a weakly acidic copper bath have been proposed, but this technique requires a soluble anode, and in the case of applying a current near the limiting current, the composition stability of the solution is lacking, and it is difficult to process a long foil. In the case of the case, there is a characteristic deviation before and after, and a special mechanism is required to make it stable.

[0029] In addition, the treatment (blackening treatment) of forming needle-shaped particles of copper oxide represented by Japanese Patent Publication No. 32-137, even when used for printed circuit boards, cannot be adapted to the subsequent chemical adhesion and durability. Various electrolytic surface treatments aimed at heat, chemical resistance, and rust prevention

[0030] As substrate materials for printed circuit boards, environmentally friendly substrate materials that do not use halogen elements and antimony, and high heat-resistant substrate materials suitable for lead-free solder are gradually attracting attention, but the adhesion of copper foil to these resins is insufficient. full

In addition, in order to satisfy high-frequency characteristics and high-density wiring along with the high-performance of mobile electronic devices, it is required that the thickness of the copper foil be thinner, and the surface of the copper foil be uniformly roughened with low roughness, but conventional The roughening treatment process of this method takes a long time and requires multiple steps, so the foil-through property for thin foil is poor, and the roughened particles are not uniform, so the roughness is high, and there is a risk of the roughened particles falling off during the process, so Improvement in productivity and yield is required in addition to improvement in rough surface characteristics

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