JP2017508890A - Copper foil, electrical parts including the same, and battery - Google Patents

Abstract

A copper foil having a low illuminance and excellent adhesive strength is proposed. The proposed copper foil is a copper foil in which irregularities are formed on at least one surface and a fine particle layer is formed on the surface, and the upper fine particles located above the average line according to the average height of the surface are average lines. More than the lower fine particles located below.

Description

  The present invention relates to a copper foil, an electrical component including the copper foil, and a battery. More specifically, the present invention relates to a copper foil having excellent adhesive strength while having low illuminance.

  Printed circuit board laminates used in the electronics industry are made by impregnating glass cloth, craft paper, glass fiber nonwoven fabric, etc. with thermosetting resins such as phenolic resins and epoxy resins. The resin is semi-cured to prepare a prepreg, and a copper foil is laminated on one or both sides of the prepreg. The multilayer printed wiring board is manufactured by forming a circuit on both sides of a copper-clad laminate to form an inner layer material, and laminating copper foil on both sides of the inner layer material via a prepreg.

  When the copper foil is laminated on one side or both sides of the prepreg, the adhesion rate may not be sufficient due to the difference between the materials, and the copper foil may be separated from the prepreg in a later process, resulting in a defect in the product. Therefore, a surface treatment for enhancing the adhesion between the copper foil and a resin such as a prepreg is performed.

  A copper foil used for manufacturing a printed wiring board is subjected to a roughening treatment for forming irregularities by attaching fine copper particles to one surface. When performing bonding with a resin such as a prepreg, the uneven shape of the roughened copper foil is embedded in the base resin to provide an anchoring effect. Improved adhesion.

  Recently, the demand for the wiring density of the printed wiring board has been increasing year by year due to the effects of lighter, thinner and smaller electronic devices incorporating the printed wiring board. The improvement in product quality is required, and the shape of a circuit formed by etching has been improved, and a level of circuit etching factor that enables complete impedance control has been required.

  If the copper foil surface treatment as described above is performed, the surface roughness of the copper foil is increased, and the adhesion between the copper foil and the base resin is improved, but the etching property to the fine circuit is lowered. There is. Therefore, there is a demand for development of a technique that can promote adhesion while maintaining the surface roughness of the copper foil in consideration of etching properties.

  The present invention has been devised in order to solve the above-mentioned problems, and an object of the present invention is to provide a copper foil having excellent adhesive strength while having low illuminance.

  The copper foil according to one aspect of the present invention for achieving the above object is a copper foil in which irregularities are formed on at least one surface and a fine particle layer is formed on the surface, depending on the average height of the surface. There are more upper fine particles located above the average line than lower fine particles located below the average line.

  The ratio of the number of upper fine particles and the number of lower fine particles may be 80:20 to 100: 0.

  The shape of the upper fine particles connecting the center points can form a triangle.

  The diameter of the fine particles may be 1 to 3 μm.

  The fine particles may be metal particles containing at least one of copper (Cu), iron (Fe), molybdenum (Mo), and cobalt (Co), or copper alloy particles.

  The peel strength of the copper foil may be 1.28 to 1.33 kgf / cm, the surface roughness Rz may be 5.2 to 6.5 μm, and the surface roughness Rmax is 6.5. To 7.7 μm.

  According to another aspect of the present invention, an electrical component is proposed that includes an insulating substrate and the copper foil as described above attached to one surface of the insulating substrate.

  According to another aspect of the present invention, a battery including the copper foil as described above is provided.

  According to another aspect of the present invention, a step of preparing a copper foil having irregularities formed on at least one surface, and forming a fine particle layer on the surface having irregularities, the average height of the surface Forming a fine particle layer such that there are more upper fine particles located above the average line than the lower fine particles located below the average line.

  In the step of forming the fine particle layer, the copper foil is immersed in a surface treatment solution containing copper sulfate, sulfuric acid, and a metal containing iron (Fe), molybdenum (Mo), and cobalt (Co) and electrolyzed. This is carried out by forming a fine particle layer on the surface on which the irregularities are formed.

The iron content can be 10 to 30 g, the molybdenum content can be 0.5 to 10 g, and the cobalt content can be 1 to 15 g. The electroplating process for forming the fine particle layer can be performed between 20 to 60 A / dm ² to 1 to 5 seconds.

  The copper foil according to the present invention has excellent adhesive strength while having low illuminance. Therefore, while ensuring the etching property for forming the fine circuit board, the adhesive strength is excellent and the adhesiveness with the resin is improved, so that there is an effect of improving the product reliability when manufacturing the product using the copper foil.

1 is a view showing a surface of a copper foil according to an embodiment of the present invention. It is drawing which showed the surface of the copper foil except the fine particle in FIG. It is drawing which showed a part of copper foil surface in FIG. 2 is a scanning electron microscopy (SEM) image of the surface of the copper foil surface-treated in Example 1. FIG. 3 is an SEM image of the surface of the copper foil of Example 2. 4 is a SEM image of the surface of the copper foil of Example 3. 4 is a SEM image of the surface of the copper foil of Example 4. 3 is a SEM image for the surface of the copper foil of Comparative Example 1. 3 is a SEM image for the surface of a copper foil of Comparative Example 2. 4 is a SEM image for the surface of the copper foil of Comparative Example 3.

  The copper foil according to one aspect of the present invention is an upper fine particle located on an average line according to the average height of the surface, as a copper foil in which irregularities are formed on at least one surface and a fine particle layer is formed on the surface. Are more than the lower fine particles located below the average line.

  Hereinafter, a copper foil, an electrical component and battery including the copper foil, and a surface treatment method for the copper foil according to preferred embodiments will be described in more detail.

  FIG. 1 is a view showing the surface of a copper foil according to an embodiment of the present invention, FIG. 2 is a view showing the surface of the copper foil excluding fine particles in FIG. 1, and FIG. It is drawing which showed a part of copper foil surface. The copper foil according to the present example is formed with irregularities on the surface, and as the copper foil with the fine particle layer formed on the surface, the upper fine particles located above the average line due to the average height of the surface are below the average line. More than the lower fine particles located.

  The copper foil according to the present invention has irregularities formed on the surface. The process of manufacturing a copper foil is generally classified into a foil manufacturing process, that is, a process of manufacturing the copper foil itself and a process of treating the surface of the manufactured copper foil. Although the copper foil manufactured by the foil making process has a different value depending on the process, it has surface roughness. That is, when the illuminance is high, the surface includes large unevenness, and when the illuminance is low, the surface includes small unevenness.

  If necessary, the surface including such irregularities is subjected to a number of surface treatment steps, and necessary characteristics are imparted in the subsequent steps. For example, when used in an FPCB or in a cathode current collector of a secondary battery, the illuminance can be increased by roughening the surface in order to improve adhesion with a resin or an active material. In addition, it can be barrier-treated to prevent copper particles from diffusing into other layers, and it can be rust-prevented to prevent surface oxidation, or surface treatment using a silane coupling agent on the outermost surface. A surface treatment for strengthening the adhesive force can be performed.

  Among these, in order to increase the adhesion between the copper foil and the resin or active material, a roughening treatment is performed to increase the surface roughness. A fine particle layer can be formed on the surface of the foil.

  Referring to FIG. 1, the copper foil 100 has irregularities 120 formed on the surface of the copper foil layer 110, and fine particles 131 form the fine particle layer 130 on the irregularities 120. Referring to FIG. 2 together, fine particles can be classified based on the average line (m) based on the average height of the unevenness 220 of the copper foil 210. That is, it can be said that the fine particles located on the average line (m) are the upper fine particles, and the fine particles located below the average line (m) are the lower fine particles.

  The copper foil 100 according to the present invention has more upper fine particles than lower fine particles. The upper fine particles are located in the peak portions of the unevenness 120, and the lower fine particles are the fine particles located in the valley portions of the unevenness 120. When the upper fine particles are larger than the lower fine particles or there are no lower fine particles as in the copper foil 100 of the present invention, there are few or no fine particles in the valley portions of the unevenness 120. Therefore, a vacant space is generated in the valley portion of the unevenness 120, and the porosity increases. In such a vacant space, for example, when the copper foil 100 is in contact with a resin or an active material, the resin or the active material is filled with the vacant space, and the adhesion is improved.

  The reason for roughening the surface of the copper foil is that the surface of the copper foil in which the unevenness phenomenon is further aggravated by the roughening treatment is embedded in a resin or the like to provide an anchor effect to improve adhesion. However, in the case of another copper foil according to the present invention, in addition to this, a small space is generated by generating a small amount of fine particles in the valley between the uneven peaks, and the fine particles are formed on the upper portion thereof. The resin filled in the vacant space provides an anchor effect and improves the adhesion.

  For this purpose, it is desirable that fine particles are located above the average line (m) of the copper foil 210 and few fine particles are located in the lower part to ensure the maximum porosity. For example, the ratio of the number of upper fine particles and the number of lower fine particles may be 80:20 to 100: 0.

Further, in order to maximize the anchor effect, the upper fine particles can form a triangle having a shape in which center lines are connected. Referring to FIG. 3, three upper fine particles 331, 332, and 333 are located on the unevenness 320. A central shape 340 connecting these center lines (P ₁ , P ₂ , P ₃ ) is a triangle. It is.

  The diameter of the fine particles may be 1 to 3 μm. If the diameter of the fine particles is too small, the proportion of the lower fine particles may infiltrate into the valleys of the irregularities, and if the diameter of the fine particles is too large, the overall irregularities will increase and the copper will increase. Since the surface roughness of the foil is increased, the etching property is disadvantageous.

  The fine particles may be metal particles or copper alloy particles containing at least one metal among copper (Cu), iron (Fe), molybdenum (Mo), and cobalt (Co).

  The peel strength of the copper foil may be 1.28 to 1.33 kgf / cm, the surface roughness Rz may be 5.2 to 6.5 μm, and the surface roughness Rmax is 6.5 to It may be 7.7 μm. In the copper foil according to the present invention, the fine particles formed in the uneven portions are positioned so as to be biased to the peak portions, and the peel strength is high and the adhesion is improved while the surface roughness is low.

  According to another aspect of the present invention, an electrical component is proposed that includes an insulating base and a copper foil attached to one surface of the insulating base. The copper foil included in the electrical component includes a circuit formed by etching the copper foil.

  Examples of such electrical components include TAB tape, printed wiring board (PCB), and flexible printed wiring board (FPC, Flexible PCB). However, the present invention is not limited to these, and a copper foil is formed on an insulating substrate. Anything that can be used in the art as attached and used is possible.

  According to another aspect of the present invention, a battery including the above-described copper foil is provided. The copper foil can be used in the cathode current collector of the battery, but is not necessarily limited thereto, and can be used in other components used in the battery. The battery is not particularly limited and includes all primary batteries and secondary batteries, and may be used in the art as a battery using a copper foil as a current collector, such as a lithium ion battery, a lithium polymer battery, or a lithium air battery. All possible batteries are possible.

  According to another aspect of the present invention, a step of preparing a copper foil having irregularities formed on at least one surface, and forming a fine particle layer on the surface having irregularities, the average height of the surface Forming a fine particle layer such that there are more upper fine particles located above the average line than the lower fine particles located below the average line.

  In the surface treatment method for copper foil according to the present invention, the copper foil is immersed in a surface treatment solution containing copper sulfate, sulfuric acid, and a metal containing iron (Fe), molybdenum (Mo), and cobalt (Co) for electrolysis. Then, a fine particle layer is formed on at least one surface of the copper foil having an uneven surface.

  The surface treatment liquid contains 10 to 30 g of iron, 0.5 to 10 g of molybdenum, and 1 to 15 g of cobalt. If the metal content in the surface treatment solution is too small, the copper alloy is not sufficiently formed, and it is difficult to adjust the ratio of the upper and lower fine particles, and if the metal content is very high, too many fine particles are formed. As a result, the surface roughness becomes high and the etching property may be disadvantageous.

The electroplating process for forming the fine particle layer can be performed between 20 to 60 A / dm ² to 1 to 5 seconds.

  The copper foil according to the invention can additionally be surface treated. For example, any one of heat resistance and chemical resistance treatment, chromate treatment, silane coupling treatment or a combination thereof can be cited, and what kind of surface treatment is performed depends on the subsequent process. Can be selected.

  For heat and chemical resistance treatment, for example, any one of metals such as nickel, tin, zinc, chromium, molybdenum and cobalt or an alloy thereof is sputtered, electroplated or electrolessly plated on a metal foil. It can be implemented by forming. In terms of cost, electroplating is desirable. In order to facilitate the precipitation of metal ions, an igniting agent such as citrate, tartrate or sulfamic acid can be added in a necessary amount.

As the chromate treatment, an aqueous solution containing hexavalent to trivalent chromium ions is used. The chromate treatment can be a simple immersion treatment, but is preferably performed by a cathode treatment. It is desirable to carry out under conditions of sodium dichromate 0.1 to 70 g / L, pH 1 to 13, bath temperature 15 to 60 ° C., current density 0.1 to 5 A / dm ² , and electrolysis time 0.1 to 100 seconds. It can also carry out using chromic acid or potassium dichromate instead of sodium dichromate. Moreover, it is desirable that the chromate treatment is performed on the rust-proofing treatment, whereby the moisture resistance and heat resistance can be further improved.

  Examples of the silane coupling agent used for the silane coupling treatment include epoxy-functional silanes such as 3-glycidoxypropyltrimethoxysilane, 2- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, 3- Amino-functional silanes such as aminopropyltrimethoxysilane, N-2- (aminoethyl) -3-aminopropyltrimethoxysilane, N-2- (aminoethyl) -3-amino-propylmethyldimethoxysilane, vinyl silane, vinyl Olefin functional silanes such as phenyltrimethoxysilane, vinyltris (2-methoxyethoxy) silane, acrylic functional silanes such as 3-acryloxypropyltrimethoxysilane, methacrylic functional silanes such as 3-methacryloxypropyltrimethoxysilane, 3-mercaptopropyltrimethoxy And mercapto-functional silanes such as silane are used. These can be used alone or in combination.

Such a coupling agent is dissolved in a solvent such as water at a concentration of 0.1 to 15 g / L and applied to a metal foil at a temperature of room temperature to 70 ° C. or electrodeposited. These silane coupling agents form a film by condensation bonding with the hydroxyl group of the rust-preventing metal on the surface of the metal foil. After the silane coupling treatment, a stable bond is formed by heating, ultraviolet light inspection or the like. The heating is performed at a temperature of 100 to 200 ° C. for 2 to 60 seconds. Ultraviolet rays are checked in the range of 200 to 400 nm and 200 to 2500 mJ / cm ² . The silane coupling treatment is desirably performed on the outer layer of the copper foil, thereby improving the moisture resistance and the adhesion between the insulating resin composition layer and the metal foil.

  Hereinafter, the present invention will be described in more detail with reference to preferred examples, but the present invention is not limited thereto.

(Manufacture of copper foil)
In order to produce a copper foil by electrolysis, a 3 L capacity electrolytic cell system capable of circulating at 20 L / min was used, and the temperature of the copper electrolyte was kept constant at 45 ° C. The positive electrode used was a DSE (Dimentionally Stable Electrode) electrode plate having a thickness of 5 mm and a size of 10 × 10 cm ² , and the cathode used was a titanium electrode plate having the same size and thickness as the positive electrode.

Current density in order to facilitate movement of Cu 2 ⁺ ions, the plating to was performed at 35A / dm ^2, to produce a copper foil of 18μm thickness.

* The basic composition of copper electrolyte is as follows:
_{CuSO 4 · 5H 2 O: 250~400g} / L
H ₂ SO ₄ : 80 to 150 g / L
Copper electrolyte chloride ions and additives were added.

(Example 1)
The manufactured copper foil was electrolyzed at a current density of 35 A / dm ² for 1 to 5 seconds using the following copper electrolyte to form a fine particle layer. The scanning electron microscopy (SEM) image with respect to the surface of the copper foil in which the fine particle layer was formed by Example 1 appears in FIG.

_{CuSO 4 · 5H 2 O: 85g} / L
H ₂ SO ₄ : 125 g / L
Fe: 19g / L
Mo: 1.1 g / L
Co: 8g / L
(Example 2)
Except for the following contents, the fine particle layer was formed by performing electrolytic plating on the surface of the copper foil as in Example 1. The SEM image with respect to the surface of the copper foil in which the fine particle layer was formed appears in FIG.

_{CuSO 4 · 5H 2 O: 85g} / L
H ₂ SO ₄ : 125 g / L
Fe: 25g / L
Mo: 1.1 g / L
Co: 8g / L
Example 3
Except for the following contents, the fine particle layer was formed by performing electrolytic plating on the surface of the copper foil as in Example 1. The SEM image with respect to the surface of the copper foil in which the fine particle layer was formed appears in FIG.

_{CuSO 4 · 5H 2 O: 85g} / L
H ₂ SO ₄ : 125 g / L
Fe: 19g / L
Mo: 0.7g / L
Co: 8g / L
Example 4
* Except for the following, a fine particle layer was formed by performing electrolytic plating on the surface of the copper foil in the same manner as in Example 1. The SEM image with respect to the surface of the copper foil in which the fine particle layer was formed appears in FIG.

_{CuSO 4 · 5H 2 O: 85g} / L
H ₂ SO ₄ : 125 g / L
Fe: 19g / L
Mo: 1.1 g / L
Co: 10g / L
(Comparative Example 1)
Except for the following contents, the fine particle layer was formed by performing electrolytic plating on the surface of the copper foil as in Example 1. An SEM image of the surface of the copper foil on which the fine particle layer is formed appears in FIG.

_{CuSO 4 · 5H 2 O: 70g} / L
H ₂ SO ₄ : 165 g / L
Mo: 0.57g / L
W: 10g / L
(Comparative Example 2)
Except for the following contents, the fine particle layer was formed by performing electrolytic plating on the surface of the copper foil as in Example 1. An SEM image of the surface of the copper foil on which the fine particle layer is formed appears in FIG.

_{CuSO 4 · 5H 2 O: 70g} / L
H ₂ SO ₄ : 165 g / L
Mn: 1g / L
(Comparative Example 3)
Except for the following contents, the fine particle layer was formed by performing electrolytic plating on the surface of the copper foil as in Example 1. The SEM image with respect to the surface of the copper foil in which the fine particle layer was formed appears in FIG.

_{CuSO 4 · 5H 2 O: 70g} / L
H ₂ SO ₄ : 165 g / L
Ga: 1 g / L
The surface roughness (Rz, Rmax) and peel strength of the surface treated with the copper foils of Examples 1 to 4 and Comparative Examples 1 to 3 were measured and shown in Table 1. Surface roughness Rz and Rmax were measured in accordance with JIS B0601-1994 standard, and peel strength was measured by attaching a test piece prepared on a halogen-free prepreg in a size of 10 × 100 mm and performing hot press bonding at 210 ° C. for 30 minutes. Prepare a test piece and replace the prepared test piece with U.S. T.A. The measurement was carried out at a speed of 50 mm for the M equipment. The lower the surface roughness, the smaller the roughness.

図４乃至図７は、本発明による実施例１乃至実施例４の銅箔の表面イメージである。図４を参照すれば、微細粒子が銅箔表面の凹凸の山部分に集中されていることを確認することができる。図５乃至図７も図１と類似に微細粒子が銅箔表面の凹凸山部分に稠密に位置して、谷部分には山部分よりさらに少なく位置することが分かる。

4 to 7 are surface images of the copper foils of Examples 1 to 4 according to the present invention. Referring to FIG. 4, it can be confirmed that the fine particles are concentrated on the uneven peaks of the copper foil surface. 5 to 7 also show that fine particles are densely located in the uneven peak portion on the surface of the copper foil, and are located in the valley portion less than the peak portion, similarly to FIG.

  In comparison, in FIGS. 8 to 10 which are the surface images of the copper foils of Comparative Examples 1 to 3, it can be seen that the fine particles are not only located in the uneven peaks but also in the valleys. In the copper foils of Comparative Examples 1 to 3, fine particles cover the entire surface of the copper foil.

  In the copper foil surfaces of Examples 1 to 4 according to the present invention, there are more upper fine particles located above the average line of unevenness than the lower fine particles, and there are fewer lower fine particles, and the resin or active material Are highly likely to penetrate into the valleys and are expected to have high adhesion.

  Thus, as can be seen in Table 1, the surface roughness of the copper foil of Example 1 is lower than the surface roughness of Comparative Example 1, but the peel strength is even higher, such as a resin or active material that is contacted in the subsequent process. It can be seen that the adhesion to other substances is high. In particular, the evaluation result that the peel strength of the copper foil of Example 1 having a lower surface roughness that is not the same surface roughness is higher than that of Comparative Example 1 appears with the fine particle positions of Example 1 biased. Can be inferred from the results. The copper foils of Examples 2 to 4 also have a deviation in surface roughness values, but are smaller than or similar to the surface roughness values of Comparative Examples 1 to 3, but the peel strength is 1.30 kgf. It is higher than the peel strength of Comparative Examples 1 to 3 at / cm or more.

Therefore, if the copper foils of Examples 1 to 4 according to the present invention are used, the adhesiveness with other substances such as resins and active materials is high at the time of product manufacture, and the defect rate is low and the yield is high in the process. Therefore, the surface roughness is low, the etching property is excellent, the fine circuit pattern can be formed, and the product reliability is increased.
The present invention is not limited by the above-described embodiments and the accompanying drawings, but should be interpreted by the appended claims. In addition, the present invention has ordinary knowledge in the technical field that various forms can be replaced, modified and changed without departing from the technical idea of the present invention described in the claims. It will be obvious to the person.

  As described above, the copper foil according to the present invention has excellent adhesive strength even though the illuminance is low. Therefore, while ensuring the etching property for forming the fine circuit board, the adhesive strength is excellent and the adhesiveness with the resin is improved, so that there is an effect of improving the product reliability when manufacturing the product using the copper foil.

Claims (16)

  As a copper foil in which irregularities are formed on at least one surface and a fine particle layer is formed on the surface, upper fine particles located above the average line according to the average height of the surface are located below the average line More copper foil than lower fine particles.   The copper foil according to claim 1, wherein a ratio of the number of the upper fine particles and the number of the lower fine particles is 80:20 to 100: 0.   The copper foil according to claim 1, wherein the upper fine particles have a triangular shape in which center lines are connected.   The copper foil according to claim 1, wherein the fine particles have a diameter of 1 to 3 μm.   2. The copper foil according to claim 1, wherein the fine particles are metal particles containing at least one metal of copper (Cu), iron (Fe), molybdenum (Mo), and cobalt (Co).   The copper foil according to claim 1, having a peel strength of 1.28 to 1.33 kgf / cm.   2. The copper foil according to claim 1, wherein the surface roughness Rz is 5.2 to 6.5 μm.   The copper foil according to claim 1, wherein the surface roughness Rmax is 6.5 to 7.7 µm. An insulating substrate;
An electrical component comprising: a copper foil according to any one of claims 1 to 8 attached to one surface of the insulating substrate.   A battery comprising a copper foil according to any one of claims 1 to 8. Preparing a copper foil having at least one surface with irregularities; and forming a fine particle layer on the surface having the irregularities; Forming a fine particle layer so that there are more particles than the lower fine particles located below the average line.   In the step of forming the fine particle layer, the copper foil is immersed in a surface treatment solution containing copper sulfate, sulfuric acid, and a metal containing iron (Fe), molybdenum (Mo), and cobalt (Co). The copper foil surface treatment method according to claim 11, which is a step of forming a fine particle layer on the surface on which the irregularities are formed by electrolysis.   The copper foil surface treatment method according to claim 12, wherein the iron content is 10 to 30 g.   The copper foil surface treatment method according to claim 12, wherein the molybdenum content is 0.5 to 10 g.   The copper foil surface treatment method according to claim 12, wherein the cobalt content is 1 to 15 g. The copper foil surface treatment method according to claim 12, wherein the electrolysis is performed at 20 to 60 A / dm ² for 1 to 5 seconds.

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