JP5268748B2 - Sn or Sn alloy plating film and composite material having the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an Sn or Sn alloy plating film that can give excellent maintenance property of a roll and improve productivity by preventing the Sn or Sn alloy plating film from being rubbed or dropped, and to provide a composite material having the plating film. <P>SOLUTION: The Sn or Sn alloy plating film 2 is formed on one surface of a copper foil or a copper alloy foil 1 where a resin layer or a film 4 is laminated, wherein surface roughness Ra of the plating film when a non-contact type surface roughness meter is used is &ge;0.5&times;10<SP>2</SP>nm. <P>COPYRIGHT: (C)2011,JPO&amp;INPIT

Description

  The present invention relates to an Sn or Sn alloy plating film formed on the other surface of a copper foil or a copper alloy foil laminated with a resin or the like, and a composite material having the same.

The Sn plating film is characterized by excellent corrosion resistance, good solderability and low contact resistance. For this reason, for example, a metal foil such as copper is Sn-plated and used as a composite material for an in-vehicle electromagnetic wave shielding material.
As said composite material, the structure which laminated | stacked the resin layer or the film on one surface of copper foil or copper alloy foil, and formed Sn plating film on the other surface is used.
In recent years, in applications such as connectors, it has been desired that the Sn plating film be hardened from the viewpoint of wear resistance and insertion / removability, and a technique for defining the Knoop hardness Hk of the Sn plating surface layer has been disclosed (patent). Reference 1).

Sn plating on copper or copper alloy foil is usually performed by wet plating, but the plating film is required to have no appearance unevenness and be beautiful, that is, to have a uniform color tone and no color spots or patterns. Therefore, gloss Sn plating is often performed by adding an additive to the plating solution. Therefore, the surface roughness of the Sn plating film is small.
For example, a technique is disclosed in which an alloy plating made of tin, nickel, and molybdenum is performed to produce a copper foil having a reflectance of 1% to 15%, and an electromagnetic wave shielding body is obtained using the copper foil (Patent Literature). 2). In this technique, the surface roughness of the copper foil before alloy plating shows a value of 0.1 to 0.5 μm (1.0 × 10 ^{2 to} 5.0 × 10 ² nm) as a center line average roughness.
On the other hand, whisker-like crystals called whiskers are generated in Sn plating due to internal stress and external stress. In order to prevent this, it is known that the internal stress is reduced by extremely reducing the brightening agent during plating. However, it is difficult to prevent whisker generation due to external stress even by this method. For this reason, a technique has been disclosed in which the brightener in the electroplating bath is reduced and methanol is added to create a void in the Sn plating film to relieve external stress generated by bending or punching after plating. . (See Patent Document 3)

JP 2002-298963 A Japanese Patent Laid-Open No. 2003-201597 JP 2007-254860 JP

However, in the case of normal gloss Sn plating, since the surface roughness Ra is small, when the copper foil strip is continuously plated, the friction with the roll contacting with the plating outlet side is reduced, the roll slips, and the Sn plating surface is There is a problem of rubbing and transferring and adhering to the roll.
Further, for example, since a vehicle-mounted electromagnetic shielding material is manufactured using a composite material based on copper or copper alloy foil, there is a similar problem in a process of applying a thermoplastic adhesive in a continuous line. In this step, the foil passing speed is fast at 40 to 100 m / min, and Sn adhesion to the roll in contact with the plating surface is remarkably observed.
In any case, since the maintenance takes time due to Sn adhesion to the roll, productivity is lowered. Furthermore, when maintenance is neglected, there is a risk that quality abnormalities such as surface scratches due to Sn adhering to the roll side may occur. Moreover, Sn plating film becomes thin by Sn adhesion to a roll, and it may cause a fall of corrosion resistance.

On the other hand, since copper foil is thin, its strength is low. Therefore, when using as a shielding material, it is common to stick a resin or a film on a copper foil. However, even a copper foil to which such a resin or film is attached is broken or wrinkled when the tension applied to the strip is increased during continuous plating. Therefore, in order to prevent the folding and wrinkling, it is necessary to pass the foil with a low tension. In addition, in the plating process, the thermoplastic adhesive coating process, and the like, a roll with a small roughness is used to prevent scratches on the surface, and the resistance between the roll and the Sn plating film is small. Therefore, it becomes easy to produce a slip between rolls. Therefore, when the surface roughness of the Sn plating film is small, the slip is further promoted.
In addition, when the surface roughness of the Sn plating film is small, it is also conceivable that the organic material of the brightener is co-deposited on the Sn film, and the plating becomes brittle and easily falls off.

  When a composite material obtained by Sn plating on a copper foil is used as an electromagnetic shielding material such as a cable, the composite material is wound around the outer periphery of the cable, and further, a resin is coated on the outside. In this coating step, when the composite material passes through the die (die), the Sn plating film may drop off and adhere to the die as Sn residue, and it takes time for maintenance to remove it. And may reduce productivity.

Furthermore, in the case of the technique described in Patent Document 1, it is assumed that the surface roughness of the copper foil is 0.1 to 0.5 μm, and the surface roughness of the plating film on the surface of the copper foil is approximately the same. According to the study by the present inventors, it has been found that if the surface roughness Ra of the Sn plating film is 0.5 × 10 ² nm or more, the roll hardly slips during continuous plating.
However, even if the surface roughness is 0.5 × 10 ² nm or more in the contact-type surface roughness meter, the non-contact-type surface roughness meter may be less than 0.5 × 10 ² nm. In some cases, roll slip occurs during continuous plating. That is, in order to effectively prevent the slip of the roll during continuous plating, it is necessary to strictly control the surface roughness Ra of the Sn plating film with a non-contact type surface roughness meter.

On the other hand, Patent Document 3 describes that the hardness of the Sn plating film is 400 MPa or less in order to make it less susceptible to external stress. However, the technique described in Patent Document 3 is a plating film with many voids because it contains a high concentration of methanol in the plating bath, and if the electrolysis is continued for a long time, a large defect (exposure of the ground) occurs in the Sn plating film. It has been clarified by the inventors' investigation.
This is presumably because methanol in the plating bath is converted into formaldehyde by electrolysis, which inhibits normal Sn deposition and causes defects in the plating film. And if the foundation | substrate is exposed, the malfunction which the corrosion resistance of a foundation | substrate (metal foil) falls will arise.

  The present invention has been made in order to solve the above-mentioned problems. By preventing the sliding or falling off of the Sn or Sn alloy plating film at the time of plating or use, the roll is excellent in maintainability and productivity. An object of the present invention is to provide a Sn or Sn alloy plating film that can be improved and a composite material having the same.

  As a result of various investigations, the present inventors have succeeded in reducing the sliding or dropping of the Sn or Sn alloy plating film by increasing the surface roughness of the Sn or Sn alloy plating film on the surface of the copper or copper alloy foil. did. At the same time, the hardness of the Sn or Sn alloy plating film on the surface of the copper or copper alloy foil was reduced to a predetermined hardness or less, thereby succeeding in reducing the sliding or dropping of the Sn or Sn alloy plating film. Furthermore, by electroplating using a plating bath not containing methanol, the exposure of the substrate due to defects in the plating film was suppressed, and the corrosion resistance was also successfully improved.

In order to achieve the above object, the Sn or Sn alloy plating film of the present invention is formed on the other surface of a copper foil or copper alloy foil having a thickness of 5 to 50 μm made of an electrolytic foil or a rolled foil in which a resin layer or a film is laminated. Sn or Sn—Cu, Sn—Ag, or Sn having a surface roughness Ra of 0.5 × 10 ² nm to 2.0 × 10 ² nm when formed and using a non-contact type surface roughness meter A Sn alloy plating film having an average thickness of 0.5-2 μm made of a Pb alloy , wherein the Sn or Sn alloy plating film has a hardness of 500 MPa or less, and the surface of the Sn or Sn alloy plating film is scanned; When observed with an electron microscope (however, when the thickness of the Sn or Sn alloy plating film exceeds 1.5 μm, the thickness of the Sn or Sn alloy plating film is reduced to 1.5 μm), the copper foil or copper Alloy foil is not exposed Yes .
Examples of the non-contact type surface roughness meter include an atomic force microscope (AFM).

The Sn or Sn alloy plating film is preferably formed by continuous plating.

  The composite material of the present invention is formed on a copper foil or copper alloy foil, a resin layer or film laminated on one surface of the copper foil or copper alloy foil, and the other surface of the copper foil or copper alloy foil. And the Sn or Sn alloy plating film.

  The thickness of the composite material is preferably 0.1 mm or less, and is preferably used for an electromagnetic wave shield.

In the present invention, the hardness of Sn or Sn alloy plating is an indentation hardness with a maximum load of 1 mN in an ultra micro hardness test measured in accordance with ISO 14577-1 2002-10-01 Part 1. . Details of the measurement method will be described later.
In the present invention, when the surface of the Sn or Sn alloy plating film is observed with a scanning electron microscope, “the copper foil or copper alloy foil is not exposed” means that the reflected electron image of the Sn or Sn alloy plating film has a luminance different from that of the reflected electron image. It means that an electron image is not observed at a normal magnification (for example, about 1000 times), and a reflected electron image having a uniform luminance is obtained.
The thickness of the Sn or Sn alloy plating film is an average macro thickness of the Sn or Sn alloy plating film, and can be determined from the amount of electricity when the plating film is electrolyzed and completely dissolved.

  ADVANTAGE OF THE INVENTION According to this invention, the Sn or Sn alloy plating membrane | film | coat which is excellent in the maintainability of a roll and can improve productivity by preventing the sliding and dropping | offset of Sn or Sn alloy plating membrane | film | coat, and a composite material having the same Is obtained.

  Embodiments of the present invention will be described below. In the present invention, “%” means “% by mass” unless otherwise specified.

The composite material which concerns on embodiment of this invention is the copper foil (or copper alloy foil) 1, the resin layer (or film) 4 laminated | stacked on one surface of the copper foil (or copper alloy foil) 1, and copper It consists of Sn or Sn alloy plating film 2 formed on the other surface of the foil (or copper alloy foil) 1.
From the viewpoint of lightening the material, the thickness of the composite material is preferably 0.1 mm or less.

As the copper foil, tough pitch copper having a purity of 99.9% or more, oxygen-free copper, and as the copper alloy foil, a known copper alloy can be used depending on required strength and conductivity. Known copper alloys include, for example, 0.01 to 0.3% tin-containing copper alloys and 0.01 to 0.05% silver-containing copper alloys. -0.12% Sn and Cu-0.02% Ag are often used.
Although the thickness in particular of copper foil (or copper alloy foil) is not restrict | limited, For example, the thing of 5-50 micrometers can be used conveniently.
In addition, as copper foil (or copper alloy foil), it is preferable to use a rolled foil having higher strength than electrolytic copper foil.
Further, the surface roughness of the copper foil (or copper alloy foil) is 0.3 μm or less, preferably 0.2 μm or less in terms of the center line average roughness so as not to affect the surface roughness of the Sn or Sn alloy plating film. It is preferable to use those.

As the resin layer, for example, a resin such as polyimide can be used, and as the film, for example, a film of PET (polyethylene terephthalate) or PEN (polyethylene naphthalate) can be used. The resin layer or film may be bonded to the copper foil (or copper alloy foil) with an adhesive, but the molten resin is cast on the copper foil (copper alloy foil) without using the adhesive, or the film is made of copper. You may make it thermocompression-bond to foil (copper alloy foil).
The thickness of the resin layer or film is not particularly limited, but for example, a thickness of 5 to 50 μm can be suitably used. When an adhesive is used, the thickness of the adhesive layer can be set to 10 μm or less, for example.

  For example, Sn—Cu, Sn—Ag, or Sn—Pb can be used as the Sn alloy plating film.

The surface roughness Ra of the Sn or Sn alloy plating film is 0.5 × 10 ² nm or more. Here, Ra in the present invention is obtained by extending Ra defined in JIS B0601 in three dimensions. However, since the JIS standard does not have an index indicating the average roughness of the surface, Ra output from the surface roughness meter is adopted as a three-dimensional value in the present invention.
When the Ra of the Sn or Sn alloy plating film is 0.5 × 10 ² nm or more, the roughness of the Sn or Sn alloy plating film increases and the frictional force of the contact portion can be increased. For this reason, the slip between rolls at the time of continuous plating can be reduced. Further, when Ra is 0.5 × 10 ² nm or more, when the obtained composite material is processed into an electromagnetic shielding material such as a cable, the Sn or Sn alloy plating film slips between the roll and Sn or Sn. The alloy plating film is less likely to fall off. For this reason, Sn adhesion to the roll can be prevented, productivity can be improved, and when the obtained composite material is processed, Sn or Sn alloy plating film does not fall off, and the fixing force does not decrease.
The upper limit of the surface roughness Ra of the Sn or Sn alloy plating film is not particularly limited because it varies depending on the production conditions of the Sn or Sn alloy plating, but if Ra exceeds 2.0 × 10 ² nm, the plating efficiency is lowered. Or a non-uniform appearance (coarse precipitation, etc.) and corrosion resistance may be reduced.

In the present invention, the surface roughness Ra of the Sn or Sn alloy plating film is measured using a non-contact type surface roughness meter. This is because the Sn or Sn alloy plating film is soft, so if a contact type surface roughness meter is used, Ra cannot be measured accurately, and as a result, the measured surface roughness regardless of the actual surface roughness. The value of shows a large value. Therefore, when measured with a contact-type surface roughness meter, the Ra threshold for reducing roll slip during continuous plating is not clear.
For this reason, in the present invention, Ra is measured using a non-contact type surface roughness meter. Examples of the non-contact type surface roughness meter include a microprobe microscope such as an atomic force microscope and a confocal microscope. An example of the atomic force microscope is a model SPI-4000 (E-Sweep) manufactured by Seiko Instruments Inc.
In order to reduce measurement errors, it is preferable to measure and average Ra at a plurality of positions within a field of view of about 100 × 100 μm when measuring the surface roughness.

As a method for setting the surface roughness Ra of the Sn or Sn alloy plating film to 0.5 × 10 ² nm or more, a brightener (for example, formalin and aldehyde type, imidazole type, benzal acetone) is used in the Sn or Sn alloy plating bath. It is possible to control by not adding commercially available chemicals such as However, a naphthol surfactant such as EN (ethoxylated naphthol) may be added to the Sn or Sn alloy plating bath. Further, a nonionic surfactant such as ENSA (ethoxylated naphthol sulfonic acid), polyethylene glycol, or polyethylene glycol nonylphenol ether may be added to the Sn or Sn alloy plating bath. In addition to the surfactant, an organic substance such as naphthol having a low gloss effect may be added.

A more specific method will be described below.
Examples of the base of the Sn or Sn alloy plating bath include phenolsulfonic acid, sulfuric acid, methanesulfonic acid and the like.
The size of the electrodeposited grains can be adjusted by reducing the current density, increasing the Sn concentration in the bath, and increasing the bath temperature under plating conditions. For example, by making the current density ^{2 to} 12 A / dm ² , Sn concentration 30 to 60 g / L, and bath temperature 30 to 60 ° C., the electrodeposition of granular electrodeposited Sn (or Sn alloy) uniformly on the copper foil surface The surface roughness Ra can be 0.5 × 10 ² nm or more, but is not particularly limited because it varies depending on the apparatus.

In addition, as described in Patent Document 3, it is not preferable to add methanol to the Sn plating bath because voids are generated in the Sn plating film when the electrolysis is continued for a long time, and the corrosion resistance is lowered. This is presumably because methanol in the plating bath is converted into formaldehyde by electrolysis, which inhibits normal Sn deposition and causes defects in the plating film. Therefore, the Sn or Sn alloy plating film of the present invention is formed by an Sn or Sn alloy plating bath to which methanol is not added.
The electrolysis time for giving defects to the plating film varies depending on the plating conditions. However, as the total electrolysis time increases, the formaldehyde in which methanol has changed accumulates in the plating bath, resulting in plating defects that expose the substrate. It becomes easy. “No methanol” in the plating bath means that the methanol concentration in the plating bath is at an impurity level (usually several ppm (several mg / L) or less, for example, 5 mg / L or less).

Examples of the base of the Sn or Sn alloy plating bath include phenolsulfonic acid, sulfuric acid, methanesulfonic acid and the like.
The plating conditions are not particularly limited. For example, the current density may be 8 A / dm ² , the Sn concentration may be 20 to 50 g / L, and the bath temperature may be 30 to 60 ° C.

When the hardness of the Sn or Sn alloy plating film is 500 MPa or less and the surface of the Sn or Sn alloy plating film is observed with a scanning electron microscope (provided that the thickness of the Sn or Sn alloy plating film exceeds 1.5 μm) When the thickness of the Sn or Sn alloy plating film is reduced to 1.5 μm), it is preferable that the copper foil or copper alloy foil is not exposed.
When the hardness of the Sn or Sn alloy plating film is 500 MPa or less, slip between the Sn or Sn alloy plating surface and the roll is reduced during Sn or Sn alloy plating, and the adhesion of Sn or Sn alloy plating is lost. In addition, when the obtained composite material is used for an electromagnetic shielding material such as a cable, Sn does not adhere to a roll or die during processing, and productivity can be improved. And when processing the obtained composite material, the powder fall of Sn or Sn alloy plating film does not arise, and adhesiveness does not fall.
There is no particular limitation on the lower limit of the plating hardness of the Sn or Sn alloy plating film, but it cannot be less than the hardness of the melted and solidified Sn. In the present invention, the lower limit is 100 MPa.

The hardness of the Sn or Sn alloy plating film is an indentation hardness with a maximum load of 1 mN in an ultra micro hardness test measured in accordance with ISO (International Organization for Standardization) 14477-1 2002-10-01 Part 1. The measuring instrument used for this measurement is not limited as long as it can be measured in accordance with ISO 14577-1 2002-10-01 Part1, but for example, ENT-2100 made by Elionix can be used, and Berkovich indenter ( Diamond triangular pyramid indenter) can be used. Moreover, in this invention, the measurement conditions of indentation hardness are as follows.
Test mode: Load-unloading test (unload after pushing to maximum load)
Maximum load: 1mN
Measurement temperature: 32 ± 1 ℃
The hardness value is an average value of five locations.
The indentation hardness that can be measured by this method is affected by the film thickness. That is, the thicker the film, the harder the film itself, and the thinner the film, the lower the influence of the hardness of the intermetallic compound of Cu or Cu-Sn, which is the base metal. However, what is a problem in the present invention is the “apparent hardness” of the surface layer, and when this is measured softly, it does not slip with the roll. As the index, the result of hardness measurement under the above conditions is effective.

  As a method of setting the hardness of the Sn or Sn alloy plating film to 500 MPa or less, for example, it can be performed by controlling the electrodeposited grains (increasing the electrodeposited grains). The size of the electrodeposited grains depends on the plating conditions such as current density, Sn concentration and bath temperature, or in the Sn or Sn alloy plating bath. It can be controlled by changing the amount of added chemical).

In addition, by plating using a Sn or Sn alloy electroplating bath that does not contain methanol, when the surface of the plating film is observed with a scanning electron microscope, the base (copper foil or copper alloy foil) is not exposed and defects are not observed. No plating coating is obtained. In this case, when the surface of the plating film is observed with a scanning electron microscope, a reflected electron image having a luminance different from that of the reflected electron image of the plating film is not observed at a normal magnification (for example, about 1000 times). An electronic image is obtained. That is, the composition different from the plating film is not detected from the surface of the plating film, and the base (copper foil or copper alloy foil) is not exposed.
If the thickness of the Sn or Sn alloy plating film exceeds 1.5 μm, coarse plating grains may cover the exposed part of the base (plating defect part) (however, the base is completely covered). However, when the surface of the plating film is observed with a scanning electron microscope, the reflected electron image of the ground which should be exposed may not be obtained. Also in this case, since the base is actually exposed and the corrosion resistance is inferior, in order to accurately determine whether the base is exposed or not, the thickness of the plating film is reduced to 1.5 μm and observed with a scanning electron microscope.
As a method of reducing the thickness of the plating film to 1.5 μm, a method of producing a cross section of the plating film by FIB (focused ion beam), or a plating metal (or alloy) for reducing the thickness of the plating film to 1.5 μm. There is a method in which the amount of electricity at the time of electrolysis is set so that the amount of dissolution when electrolyzing the plating film coincides with this amount of reduction.

The thickness of the Sn or Sn alloy plating film is preferably 0.5 μm or more. If the thickness is less than 0.5 μm, corrosion resistance and solderability may be deteriorated.
The upper limit of the thickness of the Sn or Sn alloy plating film is not particularly limited because it varies depending on the manufacturing conditions of the Sn or Sn alloy plating, but even if the Sn or Sn alloy plating exceeds 2 μm, the corrosion resistance and solderability There is no further improvement, and conversely, there are problems such as increased costs and reduced productivity. Therefore, it is preferable that the thickness of the Sn or Sn alloy plating film is 0.5 to 2 μm.

  EXAMPLES Next, although an Example is given and this invention is demonstrated further in detail, this invention is not limited to these.

A strip made of a 12.5 μm thick PET film bonded to one side of a 99.9% or more copper tough pitch copper foil (thickness 7.3 μm) using a thermoplastic adhesive was used as a strip. This strip was electroplated in a continuous plating cell facing the tin anode. A phenolsulfonic acid bath was used as a plating bath, and 10 g / L of a surfactant (EN) and tin oxide were added to obtain a Sn concentration of 25 to 37 g / L. The plating conditions were a bath temperature of 35 to 55 ° C., a current density of 9 A / dm ² , and a plating thickness of 1.2 μm.
The surface roughness Ra of the obtained Sn plating film was measured by an atomic force microscope (model SPI-4000 E-Sweep manufactured by Seiko Instruments Inc.) and found to be 1.01 × 10 ² nm. The Ra measurement range was 100 × 100 μm and the measurement mode DFM.
Moreover, the hardness of Sn plating was 470 MPa. In addition, the hardness at the maximum load of 1 mN from the plated surface is measured, the measuring instrument is ENT-2100 made by Elionix, and Barcovich indenter (diamond triangular pyramid indenter) is used as the indenter. , Test mode: Load-unloading test (unloading after pushing to maximum load), measuring temperature: 32 ± 1 ° C. The hardness value was an average value of five measurements.
In addition, when the roll on the plating outlet side was observed during continuous plating, Sn adhesion was not observed on the roll even when 4700 m was fed.
Further, as a corrosion resistance evaluation, a salt spray test (Z2371) (temperature: 35 ° C., salt water concentration: 5% (sodium chloride), spray pressure: 98 ± 10 kPa, spray time: 480 h) was performed, and good results were obtained.

Continuous plating was performed in exactly the same manner as in Example 1 except that the plating thickness was 0.5 μm.
The surface roughness Ra of the obtained Sn plating film was 0.86 × 10 ² nm, and the hardness of the Sn plating was 480 MPa.
In addition, when the roll on the plating outlet side was observed during continuous plating, Sn adhesion was not observed on the roll even when 4700 m was fed. Moreover, corrosion resistance evaluation was also a favorable result.

Continuous plating was performed in exactly the same manner as in Example 1 except that the plating thickness was 1.9 μm and the current density was 7 A / dm ² .
The surface roughness Ra of the obtained Sn plating film was 1.31 × 10 ² nm, and the Sn plating hardness was 450 MPa.
In addition, when the roll on the plating outlet side was observed during continuous plating, Sn adhesion was not observed on the roll even when 4700 m was fed. Moreover, corrosion resistance evaluation was also a favorable result.

Continuous plating was performed in exactly the same manner as in Example 1 except that the plating thickness was 2.0 μm and the current density was 5 A / dm ² .
The surface roughness Ra of the obtained Sn plating film was 1.54 × 10 ² nm, and the Sn plating hardness was 425 MPa.
In addition, when the roll on the plating outlet side was observed during continuous plating, Sn adhesion was not observed on the roll even when 4700 m was fed. Moreover, corrosion resistance evaluation was also a favorable result.

A strip of a tough pitch copper foil (thickness 7.3 μm) of 99.9% or more copper bonded to a 12.5 μm thick PET film and a thermoplastic adhesive was used as a strip. This strip was electroplated in a continuous plating cell facing the tin anode. A phenolsulfonic acid bath was used as a plating bath, and 10 g / L of a surfactant (EN) and tin oxide were added to obtain a Sn concentration of 32 to 40 g / L. The plating conditions were a bath temperature of 35 to 45 ° C., a current density of 9 A / dm ² , and a plating thickness of 2.0 μm.
The surface roughness Ra of the obtained Sn plating film was 1.88 × 10 ² nm, and the hardness of the Sn plating was 475 MPa.
In addition, when the roll on the plating outlet side was observed during continuous plating, Sn adhesion was not observed on the roll even when 4700 m was fed. Moreover, corrosion resistance evaluation was also a favorable result.

A strip was obtained by bonding a PET film having a thickness of 12.5 μm to one surface of a tough pitch copper foil (thickness: 7.3 μm) of 99.9% or more copper using a thermoplastic adhesive. This strip was electroplated in a continuous plating cell facing the tin anode. A phenol sulfonic acid bath was used as a plating bath, and a surfactant EN 10 g / L, a brightener (paraaldehyde 5 ml / L, naphthaldehyde 0.1 ml / L) and tin oxide were added to obtain a Sn concentration of 25 to 37 g / L. . The plating conditions were a bath temperature of 45 to 55 ° C., a current density of 9 A / dm ² , and a plating thickness of 1.3 μm.
The obtained Sn plating film had a surface roughness Ra of 0.55 × 10 ² nm and a hardness of 495 MPa.
During continuous plating, when the roll on the plating outlet side was observed, Sn adhesion was observed on the roll when 4000 m foil was passed. Corrosion resistance was good.

<Comparative Example 1>
Continuous plating was performed in exactly the same manner as in Example 1 except that the plating thickness was 0.4 μm.
The surface roughness Ra of the obtained Sn plating film was 0.43 × 10 ² nm, and the Sn plating hardness was 495 MPa.
Further, when the roll on the plating outlet side was observed during continuous plating, Sn adhesion was observed at the time when 4700 m of foil was passed, and corrosion was observed in the salt spray test (Z2371).

<Comparative example 2>
Continuous plating was performed in exactly the same manner as in Example 1 except that the plating thickness was 1.0 μm and a brightener (paraaldehyde 12 ml / L, naphthaldehyde 0.2 ml / L) was added to the Sn plating bath.
The surface roughness Ra of the obtained Sn plating film was 0.32 × 10 ² nm, and the hardness of the Sn plating was 550 MPa.
Further, when the roll on the plating outlet side was observed during continuous plating, Sn adhesion was noticeably observed on the roll when 3000 m was passed through. The corrosion resistance evaluation was a good result.

<Comparative Example 3>
Continuous plating was performed in exactly the same manner as in Example 1 except that the plating thickness was 0.7 μm and the current density was 13 A / dm ² .
The surface roughness Ra of the obtained Sn plating film was 2.18 × 10 ² nm, and the Sn plating hardness was 580 MPa.
In addition, when the roll on the plating outlet side was observed during continuous plating, Sn adhesion was noticeable on the roll when 3500 m was passed through, and fine corrosion was observed in the salt spray test (Z2371).

<Comparative example 4>
Exactly the same as Example 1 except that the plating thickness was 1.3 μm, and a brightener (paraaldehyde 12 ml / L, naphthaldehyde 0.2 ml / L) was added to the Sn plating bath to obtain a current density of 14 A / dm ^2. Then, continuous plating was performed.
The surface roughness Ra of the obtained Sn plating was 0.29 × 10 ² nm, and the hardness of the Sn plating was 505 MPa.
Further, when the roll on the plating outlet side was observed during continuous plating, Sn adhesion was noticeably observed on the roll when 3000 m was passed through. The corrosion resistance evaluation was a good result.

<Comparative Example 5>
Example 1 was exactly the same except that the plating thickness was 1.3 μm and a brightener (paraaldehyde 12 ml / L, naphthaldehyde 0.2 ml / L) was added to the Sn plating bath to obtain a current density of 8 A / dm ^2. Then, continuous plating was performed.
The surface roughness Ra of the obtained Sn plating film was 0.45 × 10 ² nm, and the hardness of the Sn plating was 470 MPa.
Further, when the roll on the plating outlet side was observed during continuous plating, Sn adhesion was noticeably observed on the roll when 3700 m was fed. The corrosion resistance evaluation was a good result.

  The obtained results are shown in Table 1.

As is clear from Table 1, in each case where the surface roughness Ra of the Sn plating film is 0.5 × 10 ² nm or more, Sn adheres to the roll for a long period of time (4000 m or more) even by continuous plating. There wasn't. In each of Examples 1 to 6, the Sn plating film had a hardness of 500 MPa or less, and Sn did not adhere to the roll for a long time (4000 m or more) even by continuous plating. Furthermore, in the case of each Example 1-6, the reflection image other than Sn by SEM of the Sn plating film surface was not seen, and it turned out that there is no defect in Sn plating film. In addition, about the sample of Examples 3, 4, and 5, after reducing the thickness of Sn plating film to 1.5 micrometers by electrolysis, the reflected image by SEM was observed.

On the other hand, in the case of the comparative example 1 whose thickness of Sn plating film is less than 0.5 micrometer, corrosion resistance deteriorated.
In the case of Comparative Examples 2, 4, and 5 in which Sn plating includes a brightener, the surface roughness Ra of the Sn plating film is less than 0.5 × 10 ² nm, and Sn is formed on the roll when continuous plating is performed at 3000 to 3700 m. Attached.
In the case of Comparative Example 3 in which the current density of Sn plating was 12 A / dm ² or more, the surface roughness Ra of the Sn plating film exceeded 2.0 × 10 ² nm, and the corrosion resistance was deteriorated.
Similarly, in the case of Comparative Example 4 in which the current density of Sn plating is 12 A / dm ² or more, when the surface roughness Ra of the Sn plating film is less than 0.5 × 10 ² nm and continuous plating is performed at 3000 to 3500 m. As a result, Sn adhered to the roll. In Comparative Example 3, it can be seen that the thickness of the Sn plating film is smaller than that of Comparative Example 4, and even if the Sn plating current density is 12 A / dm ² or more, Ra changes depending on the plating thickness.
In the case of Comparative Example 6 in which methanol was added to the Sn plating bath, a reflection image other than Sn by SEM on the surface of the Sn plating film was seen, and the corrosion resistance was deteriorated. This is because the Sn plating film has a defect.

It is the figure which showed an example of the composite material of this invention.

1 Copper foil (or copper alloy foil)
2 Sn or Sn alloy plating film 4 Resin layer (or film)

Claims (6)

Surface roughness Ra when a non-contact type surface roughness meter is used, which is formed on the other surface of a copper foil or copper alloy foil having a thickness of 5 to 50 μm made of electrolytic foil or rolled foil laminated with a resin layer or film. met but 0.5 × 10 ² nm ~2.0 × 10 is ² nm Sn or Sn-Cu, Sn-Ag, or an average thickness of 0.5 to 2 [mu] m Sn alloy plating film consisting of Sn-Pb alloy And
When the hardness of the Sn or Sn alloy plating film is 500 MPa or less and the surface of the Sn or Sn alloy plating film is observed with a scanning electron microscope (however, the thickness of the Sn or Sn alloy plating film is 1.5 μm) When the thickness of the Sn or Sn alloy plating film is reduced to 1.5 μm), the Sn or Sn alloy plating film in which the copper foil or copper alloy foil is not exposed . The Sn or Sn alloy plating film is formed by electroplating at a current density of ^{2 to} 12 A / dm ² ( excluding 2 A / dm ² ) using a plating bath having a Sn concentration of 30 to 60 g / L. The Sn or Sn alloy plating film according to 1. The Sn or Sn alloy plating film according to claim 1 or 2, wherein the Sn or Sn alloy plating film is formed by continuous plating . The copper foil or copper alloy foil, the resin layer or film laminated on one surface of the copper foil or copper alloy foil, and the other surface of the copper foil or copper alloy foil. A composite material comprising the Sn or Sn alloy plating film according to any one of the above.   The composite material according to claim 4, wherein the thickness is 0.1 mm or less.   The composite material according to claim 4 or 5, which is used for an electromagnetic wave shield.

Images