KR101427388B1 - Reinforcing Substrate for Supporting Printed Circuit Board and Method for Processing for the Same - Google Patents

Abstract

Provided in the present invention is a reinforcing substrate for supporting a printed circuit board, which comprises a base plate made of copper alloy including zinc (Zn) or tin (Sn); a basal layer formed by Ni plating or Cu-Ni alloy plating on the base plate; and a nodule layer formed by Ni particles deposited on the basal layer. Moreover, provided are a method for manufacturing a reinforcing plate, a bonding material comprising the reinforcing plate, and a method for manufacturing the bonding material. According to the present invention, adhesion with a conductive film can be improved by maximizing the surface area even without a physical impact and a reinforcing substrate with overall excellent electrical conductivity can be obtained.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a reinforcing plate for supporting a printed circuit board,

The present invention relates to a reinforcing plate for supporting a printed circuit board and a method of manufacturing the same, and more particularly, to a reinforcing plate for supporting a printed circuit board and a method of manufacturing the same, Plate and a manufacturing method thereof.

In general, a camera module or an LCD module used as a component of a mobile device such as a cellular phone requires a reinforcing plate to support a circuit board with component mounting. As the material of the reinforcing plate, stainless steel such as SUS 304 or SUS 301 or a copper alloy such as phosphor bronze or nickel silver is generally used. A predetermined strength and hardness are required to support the loads of the respective modules to be mounted, thereby determining the material and thickness of the reinforcing bars.

On the other hand, the circuit board and the reinforcing plate are bonded together by inserting a thermosetting conductive film therebetween and pressing under high temperature conditions.

At this time, in order to enhance the adhesion between the conductive film and the reinforcing plate, surface treatment is performed to widen the surface area of the reinforcing plate. Conventionally, surface treatment methods conventionally performed for the purpose of increasing the surface area include, for example, cleaning, etching, hair line processing, sand blast processing, and the like. In such conventional methods, the adhesion between the reinforcing plate and the conductive film is increased by removing foreign matter, oil and oxide present on the surface of the reinforcing plate, or the surface area of the reinforcing plate is increased to increase the adhesive force with the conductive film It is.

However, according to the method of simply cleaning the surface of the reinforcing plate, only the foreign substances present on the surface of the reinforcing plate are removed, and the oxide film existing on the surface of the reinforcing plate remains as it is without being removed and the film made of non- When a conductive film is used, high adhesion with the reinforcing plate can not be obtained.

When the surface of the reinforcing plate is etched using an acid solution or the like, it is effective to remove the oxide film present on the surface of the reinforcing plate. However, since the surface of the reinforcing plate is not uniform and the brittleness There is a high disadvantage that it is likely to occur.

On the other hand, the hairline processing can increase the surface area within a certain range by forming a scratch on the surface of the reinforcing plate, but there is a limit to improve the adhesion with the conductive film through hairline processing.

Due to the above-mentioned problems, sandblasting is currently most commonly used. When the surface of the reinforcing plate is treated by such a sand blasting process, the surface area can be effectively increased and the adhesion with the conductive film can be increased. However, by increasing the fatigue of the material by high pressure injection, Oxidation and the like can be caused. Therefore, the predetermined strength, hardness, and the like required as the reinforcing bar can be inhibited, and the working environment can be contaminated by fine dust and fine metal particles generated during the surface treatment.

On the other hand, Korean Patent Laid-Open Nos. 2001-0108078, 2004-0047263 and 2011-0071434 disclose copper foils for PCBs and copper foils for FPCBs, in which electrolytic acid having a certain size and electrolytic nodules And a resin film is adhered on the surface treatment layer. However, in these prior art documents, all the surfaces of the electrolytic copper foil used for a printed circuit board are subjected to a certain surface treatment to improve the adhesion with the resin film, and the adhesion between the reinforcing plate itself and the resin film is improved These prior art documents are distinguished from the present invention, and both of the electrolytic acid and the electrolytic node layer are formed of copper (Cu).

According to an embodiment of the present invention, there is provided a reinforcing plate capable of improving the adhesion between a reinforcing plate and a conductive film by increasing the surface area without applying a physical impact to the surface of the reinforcing plate.

It is another object of the present invention to provide a reinforcing plate capable of increasing the electromagnetic wave shielding effect by reducing the resistance by supporting the module with the reinforcing plate of the present invention and improving the electrical conductivity of all the components coupled with the module.

Further, the present invention is to provide a method of manufacturing a reinforcing plate, a bonding material including the reinforcing plate, and a method of manufacturing the bonding material.

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a reinforcing plate for supporting a printed circuit board, wherein the reinforcing plate of the present invention comprises a base plate made of a copper alloy containing zinc (Zn) or tin (Sn); A base layer formed on the base plate by Ni plating or Cu-Ni alloy plating; And a nodule layer formed by precipitating Ni particles on the base layer.

The Ni layer is preferably formed by precipitating Ni particles of 5 to 300 nm, wherein the Ni layer has a thickness of 0.5 to 10 탆.

It is preferable that the base layer has a thickness of 0.1 to 3 탆.

The base plate may be selected from a Cu-Zn alloy, a Cu-Zn-Ni alloy, a Cu-Sn alloy, a Cu-Sn-P alloy or a Cu-Sn-Ni alloy, Those having a surface roughness of 0.1 to 20 mu m can be used.

Further, the base plate may be a hairline-processed surface.

The present invention also relates to a bonding material on which a printed circuit board is supported, wherein the bonding material comprises a reinforcing plate for supporting the printed circuit board; And a conductive film bonded on the module layer of the reinforcing plate, wherein the printed circuit board can be supported on the conductive film.

At this time, the conductive film may have a thickness of 10 to 100 mu m.

The present invention also relates to a method for manufacturing a reinforcing plate for supporting a printed circuit board, comprising the steps of: forming a base layer by plating Ni or a Ni-Cu alloy on a base plate of a copper alloy containing zinc or tin; And depositing Ni on the base layer to form a nodular layer.

At this time, the base layer may be formed by strike plating on the base plate.

Also, the nodular layer can be formed by plating under a high current density of 10 to 30 A / dm ² and then plating under a low current density of 1 to 5 A / dm ² . At this time, the plating under the low current density is preferably repeated 2 to 5 times.

The method of the present invention may further comprise the step of forming a hairline on the surface of the base plate.

Further, the present invention provides a method for manufacturing a bonding material, which comprises sequentially laminating a conductive film on a module layer of a reinforcing plate manufactured by the above method, bonding the reinforcing plate to the conductive film, can do.

According to the present invention, the bonding force with the conductive film can be increased by increasing the surface area of the base plate surface by electroplating.

In addition, since no physical impact is applied to the base plate in order to increase the surface area of the base plate, adverse effects on the base plate such as deformation, discoloration or oxidation of the base plate due to increase in fatigue to the base plate can be minimized.

Furthermore, by using a copper alloy having high conductivity as a reinforcing plate, it is possible to increase the overall conductivity, thereby increasing the electromagnetic wave shielding effect.

1 is a cross-sectional view schematically showing a cross-sectional structure of a reinforcing plate according to the present invention.
2 is a cross-sectional view schematically showing a bonding material including a reinforcing plate according to the present invention, a printed circuit board, and a model obtained by joining the same.
3 (a), 3 (b) and 3 (c) are photographs taken on an electron microscope of the surfaces of the light and dark materials used in Examples 1 and 2, respectively, at a magnification of 1000, 5000 and 30,000.
4 is a photograph of the surface of the plated layer of Example 1 taken by an electron microscope and taken at 5,000 magnification.
5 (a) and 5 (b) are photographs taken on an electron microscope of the surface of the coating layer of Example 2 at a magnification of 5,000 and 30,000, respectively.
6A is a photograph of the surface of the material layer of Comparative Example 1, and FIG. 6B is a photograph of the surface of the material layer of Comparative Example 2 taken at 5,000 magnification by an electron microscope.

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a reinforcing plate used for mounting components such as a camera module and an LCD module. The reinforcing plate of the present invention includes a base plate, a base layer and a module layer as shown in Fig.

Hereinafter, the present invention will be described in more detail.

The present invention uses a material that can maintain high electrical conductivity and strength among materials commonly used as reinforcing bars, and forms a fine morphology by coating nickel metal particles electrically on the surface of the base plate, To maximize the surface area of the device and to lower the electrical resistance.

In the present invention, the base plate of the reinforcing plate serves to provide strength and hardness for supporting the load of each module mounted on the reinforcing plate, and may be suitably used in the present invention as long as it is a commonly used material. For example, stainless steel such as SUS 301 and SUS 304, or copper alloy such as nickel silver or phosphor bronze can be used. Of these, it is more preferable to use a copper alloy in that it can maintain a constant strength required as a reinforcing plate while providing a high electrical conductivity. Examples of the copper alloy include a Cu-Zn alloy, a Cu-Zn-Ni alloy, a Cu-Sn alloy, a Cu-Sn-P alloy (phosphor bronze) have.

The base plate may be subjected to a pretreatment step as required. The pretreatment step is for removing foreign matter, oil, and oxide film existing on the surface of the base plate, and is not particularly limited as long as it is a commonly used method, and may be performed by degreasing and electrolytic degreasing.

The base plate preferably has a surface roughness of 0.1 to 20 microns. When the surface roughness of the base plate has the above range, the base layer can be easily formed on the base plate surface, and thus the module layer by nickel plating can be easily grown.

On the other hand, hair lines can be formed on the surface of the base plate as required. Such a hair line can more easily form the base layer on the surface of the base plate.

The thickness of the material layer may be selected according to the strength and hardness required to support the load of each module supported on the material layer. The thickness of the material layer is, for example, 10 to 500 microns . However, considering the tendency of downsizing and thinning of the device in recent years, when it exceeds the above range, it is difficult to commercialize it as a reinforcing plate of a circuit board.

The reinforcing plate of the present invention includes a base layer on one side of the base plate or on both sides as needed. The base layer is provided as a nucleus for facilitating electrolytic deposition and growth of metal particles in the formation of the nodular layer by electroplating to give the surface area of the reinforcing plate surface, and improves the adhesion between the base plate and the module layer.

Further, when the base plate is a copper alloy containing zinc such as Cu-Zn or Cu-Zn-Ni, the zinc component in the plating solution during electrolysis can not be firmly adhered to the plating layer due to rapid oxidation or elution, Zinc may diffuse to other parts. However, such a problem can be prevented by performing strike plating on the base plate as described above to form an alloy layer and a zinc component in the base plate.

The base layer may be made of Ni or Ni-Cu alloy, and more preferably Ni-Cu alloy. The base layer thus formed is not particularly limited, but is preferably formed in a thickness range of 0.1 to 3 占 퐉. If the thickness of the base layer is less than 0.1 micron, it is difficult to achieve sufficient Ni growth of the module layer due to lack of nuclei for plating layer growth, and there is a possibility that sufficient adhesion between the base plate and the module layer may not be obtained. On the other hand, if it exceeds 3 탆, the thickness of the reinforcing plate as a whole may increase, so that it is preferable to form the base layer with the thickness within the above range.

Such a base layer is preferably formed by strike plating. The strike plating can be performed by a conventionally performed method and is not particularly limited in the present invention. For example, in the case of forming a base layer by strike plating on a base plate, nickel precursors such as nickel sulfate and nickel chloride, by applying the current density of the immersion of the bed in the plating bath containing a copper precursor, pH 1.5 to 4.5, at a temperature from 10 to 30 ℃ condition 2 seconds to 60 seconds of 0.5 to 15 a / dm ^2, such as copper sulfate, as needed Can be performed.

The reinforcing plate of the present invention includes a module layer formed by electrolytically depositing Ni on a base layer provided as plating nuclei on a surface of a base plate. Such a modular layer can provide a large surface area to the reinforcing plate, thereby improving the adhesion with the conductive film.

The module layer is formed by electrolytically depositing and growing nickel on the base layer provided as plating nuclei in the plating liquid by electroplating. Such electrolytic precipitation can be performed by immersing a base plate in which a base layer is formed in a plating solution containing a nickel precursor and applying an electric current. The electrolytic deposition of the module layer in the present invention is not particularly limited as long as it is suitably applied to the present invention as long as it is conventionally used for nickel plating.

At this time, in the electrolytic deposition, the size of the metal particles to be precipitated can be controlled by adjusting the applied current density. That is, under a high current density, precipitation of a metal having a relatively large particle size can be achieved. Thereafter, a low current density is applied and electrolytic deposition is performed to connect the particles and the particles, thereby enabling bonding between large particle sizes. After performing electrolytic deposition under such a high current density, electrolytic deposition is further performed under a low current density, whereby nickel particles can be densely precipitated and a morphology in which particles having a size of 30 to 500 nm as a whole are electrolytically deposited can be formed. As a result, the surface area of the reinforcing plate surface can be maximized.

Furthermore, the gap between each nodule deposited under a high current density is filled with fine metal particles electrolytically deposited under a low current density, so that the contact area between the conductive polymer and the metal particle can be enlarged. Therefore, the overall resistance due to non-contact with the gap can be lowered, so that the overall electrical conductivity can be increased, and the blocking effect against electromagnetic waves can be further improved.

In forming the module layer, the high current density is preferably in the range of 10 to 30 A / dm ² , and the low current density is preferably in the range of 1 to 5 A / dm ² .

At this time, the time for performing the electrolytic deposition is not particularly limited, and can be appropriately adjusted according to the thickness of the module layer to be obtained. However, the module layer is usually formed to have a thickness of 3 to 10 탆, . Therefore, electrolytic precipitation under a high current density is preferably performed for 1 to 30 seconds, and then electrolytic precipitation under a low current density for bonding between the metal particles precipitated under a high current density is preferably performed for 1 to 30 seconds. The formation of such a morphology is not particularly limited, but the plating process under the low current density is preferably repeated two to five times, more preferably two to four times, more preferably three times .

Thus, by providing a base layer on a copper alloy base plate to provide plating nuclei and nickel plating thereon to produce a reinforcing plate for supporting a printed circuit board, a physical treatment is required to increase the surface area of the base plate of the reinforcing plate It is possible to obtain a reinforcing plate having a large surface area without impairing the physical properties of the base plate. In addition, the contact with the conductive film bonded on the reinforcing plate according to the present invention can be remarkably improved, and the defect due to the non-bonding between the reinforcing plate and the conductive film can be remarkably improved. Further, since the conductive polymer can reduce the non-contact portion of the surface of the reinforcing plate at the minute gap, the overall electrical resistance can be lowered, and as a result, the electromagnetic wave shielding effect can be improved.

As shown in FIG. 2, the above-described reinforcing bar can provide a bonding material by laminating a conductive film on a nodular layer formed on the surface of the reinforcing plate. As shown in Fig. 2, such a bonding material functions as a reinforcing plate for supporting the printed circuit board by bonding the electronic parts on which the printed circuit board is mounted and the conductive film through the joining and joining process.

As shown in FIG. 2, the FPC that has undergone the laminating and the adhesion treatment is bonded to the conductive film at a pressing temperature and an appropriate temperature. The conductive film may be a thermally curable resin and a metal powder. In order to provide maximum adhesion to the reinforcing bar or circuit, the conductive film may be mixed with other additives . The conductive film may have a thickness in the range of 10 to 100 mu m, for example.

Example

The present invention will be described in more detail through the following examples. However, the following examples are provided to aid understanding of the present invention, and the present invention is not limited thereto.

Example  One

The surface was masked to prevent plating on one side of a 100 mu m positive (Cu-Zn-Ni) material whose surface was cleaned by degreasing, electrolytic degreasing, and acid activation treatment. The surface of the nickel silver material was photographed using an electron microscope, and the results are shown in Figs. 3 (a), 3 (b) and 3 (c). (a) is a photograph taken at a magnification of 1000, (b) is a photograph taken at a magnification of 5,000, and (c) is a photograph taken at a magnification of 30,000.

The above nickel-base material was immersed in a plating bath (pH 1.5, temperature 25 ° C.) containing 100 g / L of nickel sulfate, 30 g / L of ammonium chloride and 10 g / L of boric acid, applying a current density of 3 A / dm ² for 30 seconds Nickel strike plating was performed.

Thereby, a Ni base layer was formed on the surface of the above-mentioned nickel base material which was not subjected to the masking treatment. The obtained base layer had a thickness of 0.6 mu m.

The base material was immersed in a plating bath (pH 4.5, temperature 20 ° C) containing 150 g / l of NiSO ₄ , 40 g / l of NiCl ₂ , 15 g / l of HBO ₃ and 0.5 g / l of a surfactant, Nickel particles were electrolytically deposited on the base layer to form a nodular layer. At this time, a current density of 30 A / dm ² was applied to the plating solution for 30 seconds, a current density of 3 A / dm ² was applied for 30 seconds, and this was repeated three times.

The plating surface (the layered bed) thus obtained was photographed at a magnification of 5000 times using an electron microscope, and the results are shown in Fig.

Example  2

The same white cloth as in Example 1 was immersed in a plating bath at a pH of 5.5 and a temperature of 25 占 폚 containing 30 g / l of copper sulfate, 15 g / l of nickel chloride, 15 g / l of sodium citrate and 3 g / dm < ^{2 >} was applied to perform strike plating for 30 seconds.

Thereby forming a Ni-Cu base layer on the surface of the nickel silver. The obtained base layer had a thickness of 0.6 mu m.

The base material was immersed in a plating bath (pH 4.5, temperature: 15 ° C) containing 150 g / l of NiSO ₄ , 40 g / l of NiCl ₂ , 15 g / l of HBO ₃ and 0.5 g / l of a surfactant, Nickel particles were electrolytically deposited on the base layer to form a nickel layer. At this time, a current density of 30 A / dm ² was applied to the plating solution for 30 seconds, a current density of 3 A / dm ² was applied for 30 seconds, and this was repeated three times.

The surface (plating layer) of the plating thus obtained was photographed using an electron microscope, and the results are shown in Fig. 5 (a) is a photograph of the surface of the nodular layer taken at a magnification of 5,000, and FIG. 5 (b) is a photograph taken at a magnification of 30,000.

Comparative Example  1 and 2

For comparison with Examples 1 and 2, the surface of the same Cu-Zn-Ni alloy material as in Example 1 was subjected to surface roughness treatment by hair line processing (Comparative Example 1) and sandblasting treatment (Comparative Example 2) Was photographed using an electron microscope. The resulting photographs are shown in Figs. 6 (a) and 6 (b), respectively. (a) is a photograph of a hairline-processed surface, and (b) is a photograph of a sandblasted surface, each of which was photographed at a magnification of 5,000.

Observation of surface condition

Figs. 4 and 5 (a) and 5 (b) showing the surface state of the nodular layer obtained by the above Examples 1 and 2 are shown in Figs. 3 (a) to 3 It can be confirmed that the moduli obtained in Examples 1 and 2 have a remarkably large surface area when compared with the hair-lined surface and the sandblasted surface shown in Figs. 6 (a) and 6 (b).

3, no metal morphology was present on the surface of the white material, and only the shape similar to the scratch on the surface of the material layer could be observed. However, FIGS. 4 and 5 (a) and 5 b), it was confirmed that the nodular layer obtained by Examples 1 and 2 formed a uniform and dense morphology by electrolytic deposition of nickel particles, and had a larger surface area than the surface of the material .

Also, as compared with Figs. 6A and 6B, it can be seen that the surface area of the nodular layer obtained in Examples 1 and 2 is significantly wider. Also, as can be seen from the results of FIGS. 4 and 5, it can be seen that as the gap between the respective nozzles is finer, the contact area is increased with respect to the conductive polymer that is in contact with each other.

On the other hand, as can be seen from FIG. 4, it can be seen that the plated structure of the nickel layer formed by plating on the base layer of nickel plating has a large surface area due to the precipitation of fine metal particles on the surface. However, it was found that un-grown and overgrowth layers were present in a non-uniform manner in some regions. This appears to be due to the low pH conditions of the Ni strike plating for the formation of the base layer, resulting in the elution of zinc from the nickel-based material, thereby preventing uniform nucleation.

On the other hand, in the case of forming a nickel layer by Ni plating on the Cu-Ni base layer as in Example 2 from FIGS. 5 (a) and 5 (b), nickel particles are formed uniformly and densely, It can be seen that a wide and highly excellent surface state can be formed.

This seems to be the result of strike plating in a high pH plating bath containing a copper and nickel precursor as the base layer. That is, in the case of performing strike plating in a plating bath containing a copper and nickel precursor, the pH of the plating bath can be increased as compared with the case of performing strike plating in a plating bath containing only a nickel precursor, It is possible to reduce the elution of zinc from the nickel base material because of the quick substitution. As a result, it is possible to inhibit zinc from interfering with the adsorption of copper and nickel ions on the surface of the nickel silver material. As a result, copper and nickel are firmly adhered to the nickel silver surface, .

Thus, it can be seen that the formation of the base layer is more preferable to form an alloy plating of copper and nickel containing copper having a quick substitution property.

From the above results, it can be seen that the nodular layer obtained by Example 1 has a base layer of Ni alone and the growth of Ni nodule is somewhat smaller than that of the base layer of Cu-Ni alloy according to Example 2 But the surface morphology states shown in FIGS. 4 and 5 (a) and 5 (b) are similar to each other. In addition, both of these morphologies formed on the surface can provide a significantly large surface area compared to the conventional sandblasting or hairline processing, and it is possible to form a Ni base layer as in Example 1, It is possible to provide an excellent adhesion with the conductive film even when a layer is formed, and the effect of the present invention can be obtained.

Adhesion measurement

Each of the specimens prepared in Comparative Examples 1 and 2 and the specimen prepared in Example 2 were laminated on a conductive film (product name: CBF-300 manufactured by Tatsuda Corp., thickness 40 탆, surface resistance 1.4 Ω) at a pressure of 9.5 MPa and a temperature of 150 캜 Followed by bonding to produce a bonding material.

The bonding material was measured for tensile strength at a width of 1 cm, and the bonding strength between each test piece and the conductive film was measured. The results are shown in Table 1.

Comparative Example 1 Comparative Example 2 Example 1 Bond strength (kgf / cm) 0.4 0.52 0.9

As can be seen from the above Table 1, it can be seen that the bonding material produced using the test piece obtained in Example 1 has a significantly higher bonding force than the bonding material produced using the test pieces of Comparative Example 1 and Comparative Example 2 .

Electrical conductivity measurement

The electrical conductivity was measured using the bonding material used for the adhesion measurement, and the results are shown in Table 2 below.

Comparative Example 1 Comparative Example 2 Example 1 Measured resistance value (mΩ) 16.5 16.2 13.4 Volume resistivity (u? / Cm) 33.0 33.0 26.8 Electrical conductivity (uΩ / Cm) 0.030303 0.030303 0.037313

As can be seen from Table 2, the bonding material obtained using the test piece of Example 1 exhibited a lower resistance value and a volume resistance value as compared with the bonding material obtained using the test pieces of Comparative Example 1 and Comparative Example 2, As shown in FIG.

Claims (15)

A base plate made of a copper alloy containing zinc (Zn) or tin (Sn);
A base layer formed on the base plate by Ni plating or Cu-Ni alloy plating; And
And a nodule layer formed by precipitating Ni particles on the base layer.
The reinforcing plate for supporting a printed circuit board according to claim 1, wherein the Ni layer is formed by precipitating Ni particles of 5 to 300 nm.
The reinforced plate for supporting a printed circuit board according to claim 1, wherein the Ni modulus layer is 1 to 10 microns in thickness.
The reinforced plate for supporting a printed circuit board according to claim 1, wherein the base layer has a thickness of 0.1 to 3 占 퐉.
The reinforcing plate for supporting a printed circuit board according to claim 1, wherein the base plate is a Cu-Zn alloy, a Cu-Zn-Ni alloy, a Cu-Sn alloy, a Cu-Sn-P alloy or a Cu-Sn-Ni alloy.
The reinforcing plate for supporting a printed circuit board according to claim 1, wherein the base plate has a thickness of 10 to 500 탆 and a surface roughness of 0.1 to 20 탆.
The reinforcing plate for supporting a printed circuit board according to claim 1, wherein the base plate is hairline-processed on its surface.
A reinforcing plate for supporting a printed circuit board according to any one of claims 1 to 7; And
And a conductive film bonded on the module layer of the reinforcing plate, wherein the printed circuit board is supported on the conductive film.
The bonding material according to claim 8, wherein the conductive film has a thickness of 10 to 100 microns.
Forming a base layer of Ni or Ni-Cu alloy by strike plating on a base plate of a copper alloy containing zinc or tin; And
And electrolytically depositing Ni on the base layer to form a nodular layer.
The method as claimed in claim 10, wherein the base layer is formed to a thickness of 0.1 to 3 탆.
The method of claim 10, wherein the nodular layer is formed by plating under a high current density of 10 to 30 A / dm ² and then by plating under a low current density of 1 to 5 A / dm ² .
13. The method of claim 12, wherein the plating under the low current density is repeated two to five times.
11. The method of claim 10, further comprising forming a hairline on the surface of the base plate.
15. A method for manufacturing a bonding material, comprising the steps of: sequentially laminating a conductive film on a module layer of a reinforcing plate produced by any one of claims 10 to 14, and joining and abutting the reinforcing plate and the conductive film.

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