JP4349149B2 - Method for producing surface-treated steel sheet having excellent conductivity - Google Patents

Description

  The present invention relates to a method for producing a surface-treated steel sheet having excellent conductivity.

  For the purpose of improving the corrosion resistance of zinc-based plated steel sheets used in applications such as steel sheets for home appliances, steel sheets for building materials, and steel sheets for automobiles, the chromate treatment is widely performed on the surfaces thereof. Among the above-mentioned applications, excellent conductivity is required for galvanized steel sheets used for applications such as electrical and electronic equipment because the processed parts are joined by resistance welding or grounded. The

  Since the chromate treatment solution contains hexavalent chromium, the use of wastewater treatment with a completely closed system during chromate treatment and the development of coating-type chromate treatment technology that does not require a water-washing process have been conducted as environmental measures. . In addition, regarding hexavalent chromium contained in a minute amount in the chromate film, development of an organic composite coated steel sheet that prevents elution of chromium, and examination of poor coating-type chromate film have been carried out.

On the other hand, from the viewpoint of environmental measures, a steel plate (chromium-free steel plate) formed with a chromium-free chemical conversion coating that does not use hexavalent chromium has been developed. For example, the following methods have been proposed.
(1) Method using tannic acid (for example, Patent Document 1)
(2) A method using a thermosetting paint in which an epoxy resin, an amino resin, and tannic acid are mixed (for example, Patent Document 2)
(3) A method using a mixed composition of an aqueous resin and a polyhydric phenol carboxylic acid (for example, Patent Document 3)
(4) Surface treatment method for applying an aqueous solution of hydrazine derivative to the surface of tinplate or zinc iron plate (for example, Patent Document 4)
(5) A method using a surface treatment composition comprising an organic resin containing a hydroxyl group-containing monomer as a copolymerization component, phosphoric acid, and a metal phosphate compound (for example, Patent Document 5)
(6) A method of forming an organic composite coating comprising a phosphoric acid and / or phosphoric acid compound film containing an oxide in the lower layer and a resin film on the upper layer (for example, Patent Document 6, Patent Document 7)
The prior art document information is described below.
JP-A-51-71233 JP-A 63-90581 JP-A-8-325760 Japanese Patent Publication No. 56-10386 Japanese Patent Laid-Open No. 9-208859 JP 2001-11645 A JP 2001-11656 A

  However, the above (1) to (6) do not describe conductivity at all. Since the electrical conductivity of the chemical conversion coating depends on the thickness of the insulating coating coated on the surface, the electrical conductivity can be improved by reducing the thickness of the chemical conversion coating. However, since the corrosion resistance is reduced when the chemical conversion film is thinned, it is difficult to obtain a surface-treated steel sheet having excellent conductivity without reducing the corrosion resistance.

  An object of the present invention is to solve the above problems and to provide a method for producing a surface-treated steel sheet capable of obtaining excellent conductivity without reducing corrosion resistance.

  As a result of investigation and examination in order to solve the above problems, the present inventors have found that the conductivity is affected by the surface texture of the original plating plate. As a result of further investigation on this point, the present invention has been achieved.

  Means of the present invention for solving the above problems are as follows.

In the first invention, when manufacturing a surface-treated steel sheet on which an organic and / or inorganic film is formed on the surface of a zinc-based plated steel sheet , the surface roughness Ra at a cutoff value of 0.8 mm is 1. Refining with EDM rolls with a PPI in the range of 195 to 300, which is the number of peaks per length of 25.4 mm in the average line direction of the roughness curve at 8 to 3.2 μm and cut level ± 0.638 μm It is a manufacturing method of the surface treatment steel plate excellent in electroconductivity characterized by using a rolled steel plate.

In the second invention, when manufacturing a surface-treated steel sheet on which an organic and / or inorganic film is formed on the surface of a zinc-based plated steel sheet , the surface roughness Ra at a cutoff value of 0.8 mm is 1. Temper rolling with a rolling roll having a PPI in the range of 195 to 300, which is the number of peaks per length of 25.4 mm in the average line direction of the roughness curve at a cutting level of ± 0.638 μm at 8 to 3.2 μm It is a manufacturing method of the surface treatment steel plate excellent in electroconductivity characterized by using the made steel plate.

According to a third invention, in the first or second invention , the organic and / or inorganic coating is an organic and / or inorganic coating that does not contain chromium. It is a manufacturing method.

According to a fourth aspect of the present invention, in the first to third aspects of the invention, the organic and / or inorganic film not containing chromium is a phosphoric acid and / or phosphoric acid compound film containing an oxide in the lower layer, and a resin film in the upper layer It is the manufacturing method of the surface-treated steel plate excellent in electroconductivity characterized by the multilayer film which formed the organic composite coating which consists of.

5th invention is the manufacturing method of the surface treatment steel plate which is excellent in electroconductivity characterized by the said zinc system plating steel plate in 1st invention- 4th invention being an electrogalvanization steel plate.

  In this specification, the electric discharge machining roll is a roll dulled by an electric discharge machining method. The cut-off value of the surface roughness Ra is 0.8 mm. PPI is the number of peaks per length of 25.4 mm in the average line direction of the roughness curve, and the cut level is ± 0.638 μm.

  According to the present invention, since the conductivity can be improved without reducing the film thickness, it is possible to produce a surface-treated steel sheet having excellent conductivity without reducing the corrosion resistance.

  According to the present invention, excellent conductivity can be exhibited without reducing corrosion resistance even on a surface-treated steel sheet in which an organic and / or inorganic film not containing chromium is formed on the surface of a zinc-based plated steel sheet. Can do.

Among the prior art described in the background art, an organic composite in which an organic composite coating comprising a phosphoric acid and / or phosphoric acid compound film containing an oxide in the lower layer described in (6) and a resin film is formed on the upper layer. The coated steel sheet has characteristics that can sufficiently replace the conventional chromate-treated steel sheet. Therefore, the present inventors have excellent surface-treated steel sheets in which the multilayer coating (organic composite coating) described in (6) above is formed on the surface of the electrogalvanized steel sheet without reducing the corrosion resistance. various studies to have how to obtain conductivity.

  The surface-treated steel sheet in which the above-mentioned multilayer coating (organic composite film) is formed on the surface of the electrogalvanized steel sheet is obtained by subjecting a cold-rolled steel sheet to annealing and temper rolling. Plating is performed, and then a multilayer film is formed on the surface. In the manufacturing process, the inventors of the present invention formed a multilayer film when the dull processing method of the rolling roll used in the temper rolling step was a shot blasting method and a test electric discharge processing method. It was found that there was a difference in conductivity between the surface-treated steel sheets. As a result of further examination on this point, the following became clear.

(1) From the examination result of the surface texture of the rolling roll, the following was found. (I) When the surface roughness Ra of the rolling roll is large, the conductivity is improved, but the corrosion resistance is lowered. (Ii) With the same surface roughness Ra, the conductivity increases as the PPI increases. (Iii) Corrosion resistance does not change even if PPI increases.
(2) Comparing the electric discharge machining roll and the shot blast roll, if the same surface roughness Ra is applied, the electric discharge machining roll can obtain a larger PPI (high PPI) than the shot blast roll. For this reason, in the temper rolling process, by using an electric discharge machining roll as a rolling roll, the conductivity can be improved without reducing the corrosion resistance of the surface-treated steel sheet.

  The reason why the conductivity of the surface-treated steel sheet is improved by rolling using an electric discharge roll in the temper rolling process is not clear, but is presumed as follows.

  The surface texture of the temper-rolled steel sheet (plating original sheet) has a correlation with the surface texture of the rolling roll, and the surface texture after film formation has a certain degree of correlation with the surface texture of the plating original sheet. In the temper rolling process, the surface roughness Ra and PPI of the rolling roll are transferred at a certain ratio on the surface of the rolled steel sheet (generally referred to as a transfer rate). The transfer rate is different between the surface roughness Ra and the PPI, but there is no difference in the transfer rate between the shot blast roll and the electric discharge machining roll. When rolled with a roll having the same surface roughness Ra, a steel sheet rolled with an electric discharge machining roll having a high PPI has a higher PPI than a steel sheet rolled with a shot blast roll.

  FIG. 1 shows a schematic cross-sectional view of a surface-treated steel sheet in which a plated, organic and / or inorganic film is formed on the surface of a plating base plate having a different PPI. In FIG. 1, (a) is a case where the plating base plate is a high PPI, and (b) is a case where the plating base plate is a low PPI. In FIG. 1, 1 is a base steel plate, 2 is a plating layer, and 3 is a film formed on the surface of the plating layer.

  If the surface of the underlying steel plate 1 has irregularities, the surface of the plating layer 2 is also substantially irregular, and the thickness distribution of the coating 3 becomes uneven due to the irregularities. That is, the thickness of the coating 3 is relatively thin at the convex portion (the peak portion of the roughness curve) on the surface of the base steel plate 1, and the coating 3 is relatively small at the concave portion (the valley portion on the roughness curve) of the surface of the base steel plate 1. The thickness of becomes thicker. It is considered that the conductivity of the film is determined by the film thickness of the film at the convex portion.

  When the average roughness Ra is approximately the same, the number of peaks exceeding the cut level in the average line direction of the roughness curve is higher in the high PPI plating plate than in the low PPI plating plate. In the convex part of the surface-treated steel sheet with high PPI, the plating base plate of (b) has more locally thin parts than the convex part of the surface-treated steel plate with low plating temperature (b). As a result, it is considered that the conductivity of the film is improved.

  On the other hand, as described above, if the average film thickness and the surface roughness Ra of the plating base plate are the same, the corrosion resistance of the surface-treated steel plate using the high PPI plating base plate and the surface-treated steel plate using the low PPI plating base plate Corrosion resistance is about the same. Therefore, the electrical conductivity can be improved without reducing the corrosion resistance by using a high PPI plating original plate without changing the surface roughness Ra.

  The present invention will be further described below.

  In 1st invention, when manufacturing the surface treatment steel plate which forms an organic and / or inorganic type film on the surface of a zinc system plating steel plate, the steel plate which carried out the temper rolling with the electric discharge machining roll is used as a plating original plate. That is, a surface-treated steel sheet that uses a steel sheet that has been temper-rolled with an electric discharge machining roll as the plating base plate, and has a zinc-based plating and further an organic and / or inorganic coating formed on the surface of the steel sheet has a high plating surface texture. Therefore, excellent conductivity can be obtained without deteriorating the corrosion resistance.

  In order to improve both the corrosion resistance and the conductivity, it is desirable that the rolling roll used in the temper rolling process has a surface roughness Ra of 1.8 to 3.2 μm and a PPI of 150 to 300. When the surface roughness Ra is less than 1.8 μm, the conductivity is lowered, and when it exceeds 3.2 μm, the corrosion resistance is lowered. When the PPI is less than 150, the effect of improving the conductivity is insufficient, and when it exceeds 300, the dull wear powder foreign matter of the roll adheres to the roll surface, and roll wrinkles called “Dalhage” tend to occur.

If the surface roughness Ra and PPI of the rolling roll used in the temper rolling step are within the above-mentioned ranges, the dull processing method of the rolling roll is not particularly limited ( second invention), but the present technology has the surface of the rolling roll. An electric discharge machining method that can easily make the roughness Ra and PPI within the aforementioned ranges is advantageous. In the electric discharge machining method, the surface roughness Ra and PPI of the rolling roll can be set to the above-mentioned ranges by controlling the current magnitude and the current on / off time appropriately.

  Next, the manufacturing method of the surface treatment steel plate of this invention is demonstrated. A rolling roll whose surface roughness Ra and PPI are adjusted within the aforementioned ranges is prepared, and the steel sheet is temper-rolled with this rolling roll to produce a plating original sheet. Next, in the plating process, the plating base plate manufactured as described above is subjected to zinc-based plating to obtain a zinc-based plated steel sheet. Next, in the film forming step, a treatment liquid containing an organic and / or inorganic film component is applied to the galvanized steel sheet obtained above, and then dried by heating to form an organic and / or inorganic film.

In the present invention, the zinc-based plated steel sheet used as a base is a galvanized steel sheet, a Zn-Ni alloy-plated steel sheet, a Zn-Fe alloy-plated steel sheet, a Zn-Cr alloy-plated steel sheet, a Zn-Mn alloy-plated steel sheet, or a Zn-Co alloy. Galvanized steel sheet, Zn-Co-Cr alloy-plated steel sheet, Zn-Cr-Ni alloy-plated steel sheet, Zn-Cr-Fe alloy-plated steel sheet, zinc-based composite plated steel sheet in which metal oxide, polymer, etc. are dispersed (for example, , it can be used Zn-SiO ₂ dispersion plating steel plate) and the like. Moreover, the multilayer plating steel plate which plated two or more layers of the same kind or different kind among the above plating can also be used. As a plating method, any feasible method can be adopted among an electrolytic method (electrolysis in an aqueous solution or electrolysis in a nonaqueous solvent) and a gas phase method.

  The organic and / or inorganic film formed on the surface of the galvanized steel sheet is not particularly limited. The film may be a chromate-treated film.

  The film may be an organic and / or inorganic film that does not contain chromium, whose conductivity has not been sufficiently studied in the prior art. A surface-treated steel sheet in which an organic composite coating composed of a phosphoric acid and / or phosphoric acid compound film containing an oxide in the lower layer and a resin film is formed on the lower layer as described in (6) of the prior art is a conventional chromate-treated steel sheet It has the characteristics that can be sufficiently substituted. Accordingly, the film formed on the surface of the zinc-based plated steel sheet is preferably an organic composite coating comprising a phosphoric acid and / or phosphoric acid compound film containing an oxide in the lower layer and a resin film on the upper layer.

  The organic composite film is formed by applying a treatment liquid containing phosphoric acid and / or a phosphoric acid compound to the base zinc-based plated steel sheet, and then drying and heating to form a lower phosphoric acid-containing film. An organic film is formed on the upper layer.

  The treatment liquid containing phosphoric acid and / or a phosphoric acid compound used for forming the lower layer phosphoric acid-containing film contains (i) phosphoric acid and / or a phosphoric acid compound, or (b) oxide fine particles; (C) Selected from Mg, Ca, Sr, Ba, Mn, Al, Fe metal ions, water-soluble ions containing at least one of the metals, and compounds containing at least one of the metals And a treatment liquid containing at least one kind.

Examples of the phosphoric acid and / or phosphoric acid compound as the component (a) include polyphosphoric acid such as orthophosphoric acid, pyrophosphoric acid, and tripolyphosphoric acid, metaphosphoric acid, and inorganic salts thereof (for example, primary aluminum phosphate), Compounds containing phosphoric acid such as phosphorous acid, phosphite, hypophosphorous acid, hypophosphite, etc. exist as complex ions with anions or metal cations generated when dissolved in aqueous solution The form and the form existing as a free acid are all included, and the amount of the phosphoric acid component in the present invention defines the sum of all these forms present in an acidic aqueous solution as P ₂ O ₅ equivalent.

The amount of phosphoric acid and / or phosphoric acid compound added in the treatment liquid is 0.001 to 6.0 mol / L, preferably 0.02 to 1.0 mol / L, more preferably in terms of P ₂ O _5. 0.1 to 0.8 mol / L. If the addition amount of phosphoric acid and / or phosphoric acid compound is less than 0.001 mol / L, the effect of addition is not sufficient, and the corrosion resistance is poor. On the other hand, when the addition amount exceeds 6.0 mol / L, excess phosphate ions react with the plating film in a wet environment, and depending on the corrosive environment, the corrosion of the plating base is promoted, causing discoloration and spot-like rust. It becomes.

  In addition, as the component (a), it is also effective to use an ammonium phosphate salt because a composite oxide having excellent corrosion resistance can be obtained. As an ammonium phosphate salt, it is preferable to use 1 type (s) or 2 or more types, such as primary ammonium phosphate and secondary ammonium phosphate.

As the oxide fine particles as the component (b), silicon oxide (SiO ₂ fine particles) is most preferable. The silicon oxide may be water-dispersible SiO ₂ fine particles that are stable in an acidic aqueous solution, and commercially available silica sol, water-dispersible silicic acid oligomer, and the like can be used. However, since fluorides such as hexafluorosilicic acid are highly corrosive and have a great influence on the human body, it is desirable not to use them from the viewpoint of influence on the working environment. As the oxide fine particles, in addition to the above silicon oxide, colloidal solutions such as aluminum oxide, zirconium oxide, titanium oxide, cerium oxide, and antimony oxide, and fine powders can also be used.

The addition amount of oxide fine particles (addition amount as SiO ₂ amount in the case of silicon oxide) in the treatment liquid is 0.001 to 3.0 mol / L, preferably 0.05 to 1.0 mol / L. More preferably, the content is 0.1 to 0.5 mol / L. When the addition amount of the oxide fine particles is less than 0.001 mol / L, the effect of the addition is not sufficient, and the corrosion resistance is inferior. On the other hand, when the addition amount exceeds 3.0 mol / L, the water resistance of the film is deteriorated, and as a result, the corrosion resistance is also deteriorated.

  The component (c), Mg, Ca, Sr, Ba, Mn, Al, Fe metal ions, water-soluble ions containing at least one of the metals, compounds containing at least one of the metals In order to introduce one or more selected from the above into the treatment liquid, one or more of the metal phosphates, sulfates, nitrates, chlorides, etc. may be added to the treatment liquid.

  The addition amount of the additive component (c) in the treatment liquid is 0.001 to 3.0 mol / L, preferably 0.01 to 0.5 mol / L in terms of the total metal amount. If the total addition amount is less than 0.001 mol / L, the effect of addition cannot be sufficiently obtained. On the other hand, if the addition amount exceeds 3.0 mol / L, these components conversely cause a film network. It becomes difficult to form a dense film. In addition, the metal component tends to be eluted from the film, and defects such as discoloration of the appearance occur depending on the environment.

  In the additive component (c), Mg and Mn remarkably improve the corrosion resistance. In order to supply the ions of the additive component (c) as a metal salt, anions such as chlorine ions, nitrate ions, sulfate ions, acetate ions, borate ions may be added to the treatment liquid.

  It is important that the treatment liquid containing the additive component (c) is an acidic aqueous solution. That is, since the plating component such as zinc is easily dissolved by making the treatment solution acidic, a phosphoric acid compound layer containing a plating component such as zinc is formed at the chemical conversion coating and the plating interface. As a result of strengthening, it is presumed that the film has excellent corrosion resistance.

  The pH of the treatment liquid (aqueous solution) is 0.5-5, preferably 2-4. If the treatment liquid is less than pH 0.5, the reactivity of the treatment liquid becomes too high, so fine defects are formed in the film, and the corrosion resistance is lowered. On the other hand, when the treatment liquid exceeds pH 5, the reactivity of the treatment liquid becomes low, and the bonding at the interface between the plating film and the composite oxide film becomes insufficient. In this case, the corrosion resistance is also lowered.

In the present invention, the treatment liquid containing the component (a) or the treatment liquid containing the components (a), (b) and (c) is applied to the base plated steel sheet, and then heated and dried. As a first layer coating (lower layer) on the surface of the plated steel plate,
(A) phosphoric acid and / or a phosphoric acid compound,
Or, in addition,
(B) oxide particles;
(C) one or two or more metals selected from Mg, Ca, Sr, Ba, Mn, Al, and Fe (including cases where they are included as compounds), and the film thickness is 0 A phosphoric acid-containing film of 0.005 to 4 μm is formed.

  The reason why the film thickness of the lower layer film is limited to 0.005 to 4 μm is that when the film thickness is less than 0.005 μm, the corrosion resistance decreases, and when it exceeds 4 μm, the conductivity such as solubility decreases. The film thickness is preferably 0.005 to 3 μm, and more preferably 0.01 to 2 μm.

In addition, the presence form of phosphoric acid and phosphoric acid compound in the film is not particularly limited, and it may be crystalline or non-crystalline. There are no particular restrictions on the ionicity and solubility of phosphoric acid and phosphoric acid compounds in the film. Preferred coating weight 0.01~3000mg / ^{m 2} with _P 2 _{O 5} amount conversion from the viewpoint of the above components, such as corrosion resistance and weldability (a), more preferably 0.1 to 1000 mg / ^{m 2,} more preferably 1 it is a ~500mg / ^{m 2.}

Preferred coating weight of the corrosion resistance and weldability viewpoint from the component (b) 0.01~3000mg / ^{m 2,} more preferably 0.1 to 1000 mg / ^{m 2,} more preferably from 1-500 mg / ^{m 2.}

  The form in which the specific metal component (Mg, Ca, Sr, Ba, Mn, Al, Fe) as the component (c) is present in the film is not particularly limited, and may be a metal or an oxide, hydroxide, There are no particular limitations on the ionicity, solubility, etc. of the hydrated oxide, phosphate compound, coordination compound, and the like.

Preferred adhesion amount of the components from the viewpoint of preventing deterioration in corrosion resistance and film appearance (c) is 0.01 to 1000 / ^{m 2} by metal weight basis, more preferably 0.1 to 500 mg / ^{m 2,} more preferably 1 to there is 100mg / ^{m 2.}

  In the present invention, an organic film having a film thickness of 0.1 to 5 μm is formed on the upper layer of the lower film. The reason why the thickness of the upper layer is limited to 0.1 to 5 μm is that the corrosion resistance is insufficient when the thickness is less than 0.1 μm, and the conductivity and workability are deteriorated when the thickness exceeds 5 μm.

After annealing a cold-rolled steel sheet having a thickness of 0.8 mm, temper rolling was performed using rolling rolls having different dull processing methods, Ra, and PPI, and further including zinc sulfate 400 g / l, sodium sulfate 50 g / l, pH 2 Was subjected to electrogalvanizing (plating amount (per one side): 20 g / m ² ) in a sulfuric acid acidic plating bath to produce a galvanized steel sheet. Table 1 shows the roughness conditions of the rolling rolls used in the temper rolling.

Next, the electrogalvanized steel sheet obtained above is subjected to alkaline degreasing treatment, washing with water and drying, and then using a roll coater, 0.32 mol / L of primary phosphoric acid in terms of P ₂ O _{5, in} terms of SiO ₂ Then, a treatment solution (pH = 2.7) containing 0.50 mol / L colloidal silica and 0.16 mol / L Mn was applied, and then dried at 140 ° C. to obtain a film thickness of 0.1 μm. A silica-containing phosphoric acid-containing film (first layer film) was formed. Mn was supplied as primary phosphate. Next, an organic resin solution containing an epoxy resin was applied onto the phosphoric acid-containing film and baked at 140 ° C. to form an organic resin film having a thickness of 0.6 μm. The conductivity of the organic composite coated steel sheet obtained above was evaluated as follows.

About each sample, the surface resistance value was measured and evaluated using Lolesta AP and ASP terminal made from Mitsubishi Yuka. The surface resistance value was measured at 8 points and evaluated as follows based on the measured value having the highest surface resistance value.
◎: 10 ⁻⁴ Ω or less ○: More than 10 ⁻⁴ Ω, less than 10 ⁷ Ω ×: 10 ⁷ Ω or more.

  The evaluation results are also shown in Table 1.

  The organic composite coated steel sheet of the invention example using a steel sheet tempered and rolled using an electric discharge machining roll having surface roughness Ra and PPI within the scope of the present invention as the plating original sheet has good conductivity.

  On the other hand, the organic composite-coated steel sheet of the comparative example using a steel sheet tempered and rolled using a shot blast roll having surface roughness Ra and PPI outside the scope of the present invention as the plating original sheet has poor conductivity.

  The present invention can be used as a method for producing a surface-treated steel sheet having excellent conductive properties. The surface-treated steel sheet manufactured by the method of the present invention needs to be grounded for applications that require conductive properties, such as automobiles, home appliances, and building materials, in particular, electrical and electronic devices that need to be joined by resistance welding. Suitable for use in applications.

The surface-treated steel sheet produced by the third invention can be used for applications requiring an environment-adaptive surface-treated steel sheet that does not use chromium. Since the surface-treated steel sheet manufactured in the fourth invention has characteristics that can be sufficiently substituted for the conventional chromate-treated steel sheet, the environment-adaptive surface treatment that does not use chromium for applications in which the chromate-treated steel sheet is used. It can be used as a steel plate.

Fig. 2 is a schematic cross-sectional view of a surface-treated steel sheet in which an organic and / or inorganic film is formed on the surface of a plating base plate having a different PPI. (A) is a high PPI and (b) is a low plating base plate. The case of PPI is shown.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Base steel plate 2 Plating layer 3 Film (organic and / or inorganic film)

Claims (5)

When manufacturing a surface-treated steel sheet on which an organic and / or inorganic film is formed on the surface of a zinc-based plated steel sheet , the surface roughness Ra at a cutoff value of 0.8 mm is 1.8 to 3.2 μm as a plating original sheet. In addition, a steel sheet that has been temper- rolled with an electric discharge machining roll having a PPI in the range of 195 to 300, which is the number of peaks per length of 25.4 mm in the average line direction of the roughness curve at a cut level of ± 0.638 μm, is used. A method for producing a surface-treated steel sheet having excellent electrical conductivity. When manufacturing a surface-treated steel sheet on which an organic and / or inorganic film is formed on the surface of a zinc-based plated steel sheet , the surface roughness Ra at a cutoff value of 0.8 mm is 1.8 to 3.2 μm as a plating original sheet. In addition , a steel sheet that has been temper- rolled with a rolling roll having a PPI in the range of 195 to 300, which is the number of peaks per length of 25.4 mm in the average line direction of the roughness curve at a cut level of ± 0.638 μm, is used. A method for producing a surface-treated steel sheet having excellent electrical conductivity. The method for producing a surface-treated steel sheet having excellent conductivity according to claim 1 or 2, wherein the organic and / or inorganic coating is an organic and / or inorganic coating that does not contain chromium. The organic and / or inorganic film not containing chromium is a multilayer film in which an organic composite coating composed of a phosphoric acid and / or phosphoric acid compound film containing an oxide as a lower layer and a resin film as an upper layer is formed. The method for producing a surface-treated steel sheet having excellent conductivity according to any one of claims 1 to 3 . The method for producing a surface-treated steel sheet having excellent conductivity according to any one of claims 1 to 4 , wherein the zinc-based plated steel sheet is an electrogalvanized steel sheet.

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