TWI647345B - Copper strip, electroplated copper strip, lead frame and LED module - Google Patents

Abstract

The present invention provides a copper strip, a plated copper strip, and a lead frame that can form a surface plating layer having a higher reflectance. A copper strip having a growth surface of a base plating layer formed in an in-plane uniform manner in a growth rate of a base plating layer of a copper strip at a growth rate of a base plating layer, and a non-formed growth surface of the base plating layer At least any one of a crystalline region or a region formed of fine crystal grains.

Description

Copper strip, electroplated copper strip, lead frame and LED module

The invention relates to copper strips, electroplated copper strips and lead frames which are preferably used for lead frames.

In recent years, a light-emitting diode (LED) has a light-emitting element such as a lead frame formed using a copper strip and an LED chip mounted on a lead frame. On such a copper strip, for example, at least one of a copper (Cu) plating layer or a nickel (Ni) plating layer as a base plating layer, and a silver (Ag) plating layer that reflects light from the light-emitting element are formed as a surface. Plating. The Ag plating layer is grown on the surface of the copper ribbon on the side on which the light-emitting element is mounted. The Ag plating layer is excellent in reflectance in the entire visible light wavelength region. Therefore, when the Ag plating layer is provided, the light emitted from the light emitting element is reflected by the Ag plating layer, so that light originating from the light emitting element can be efficiently emitted to the outside. As a result, optical performances such as light output (luminance), light beam, and brightness of the LED (LED module) can be further improved.

The evaluation of the optical performance of the LED is performed, for example, by using the total luminous flux measured by an integrating sphere (or an integrating sphere or ulbrichi sphere) using an integrating photometer. That is, regarding the optical performance of the LED, the sample light source is applied to the integrating sphere, and the light is received by the sensor to be evaluated. Therefore, the optical performance of the LED is largely affected by the surface state of the surface plating layer such as the Ag plating layer provided in the LED. For example, when the gloss of the surface of the Ag plating layer or the like is low and uneven gloss is generated, the total luminous flux measured by the integrating sphere method is lowered, and the optical performance is evaluated to be low. That is, when gloss unevenness occurs on the surface of the Ag plating layer or the like, the reflectance of the Ag plating layer is lowered, and the optical performance of the LED is lowered.

For this reason, for example, a work-affected layer is removed so that the thickness of the work-affected layer formed on the surface of the metal substrate (for example, a copper tape) is equal to or less than a predetermined value (see, for example, Patent Document 1). Therefore, when Ag plating is performed on such a metal substrate, electricity is suppressed. Abnormal precipitation of plating. Therefore, the decrease in the reflectance of the Ag plating layer can be suppressed.

Prior art literature

Patent literature

Patent Document 1: Japanese Laid-Open Patent Publication No. 2007-39804

In recent years, the use of LEDs has expanded. Therefore, it is required to further improve the optical performance of the LED. That is, it is required to make the reflectance of the surface plating layer such as the Ag plating layer higher. However, in the conventional method of increasing the reflectance of the Ag plating layer, it is difficult to satisfy the required reflectance of the Ag plating layer.

An object of the present invention is to solve the above problems and to provide a copper strip, a plated copper strip, and a lead frame which can form a surface plating layer having a higher reflectance.

In order to solve the above problems, the present invention is constructed as follows.

A first embodiment of the present invention provides a copper strip which is a copper strip having a growth layer of a base plating layer, wherein a growth rate of the underlying plating layer is formed in an in-plane uniform manner on a growth surface of a base plating layer of the copper strip. At least one of an amorphous region or a region formed of fine crystal grains is formed on the growth surface of the underlying plating layer.

According to a second aspect of the present invention, in the copper strip according to the first aspect of the present invention, the base plating layer growth surface is obtained by measuring by using an EBSD method that the measurement region is 90 μm × 120 μm and the measurement interval is 0.2 μm. The reliability index is 0.1 or less, and the ratio of the measurement points is 50% or more.

A third embodiment of the present invention provides a copper strip which is a copper strip having a growth layer of a base plating layer, and a growth surface of the base plating layer of the copper strip is measured by using an EBSD method to have a measurement area of 90 μm × 120 μm and The ratio of the measurement points whose reliability index is 0.1 or less, which is measured by the interval of 0.2 μm, is 50% or more.

According to a fourth aspect of the present invention, in the copper strip of the second or third aspect, the reliability index is measured by removing the substrate having a thickness of 50 nm or more by chemical etching. The plating layer is grown after the growth surface.

According to a fifth aspect of the present invention, there is provided a plated copper strip, wherein the base plating layer growth surface of the copper strip according to any one of the first to fourth embodiments is formed as a base plating layer by Cu plating. At least one of a layer or a Ni plating layer.

According to a sixth aspect of the present invention, there is provided a plated copper strip according to the fifth aspect of the present invention, wherein an Ag plating layer is formed on the underlying plating layer as a surface plating layer that reflects light.

A seventh embodiment of the present invention provides a lead frame formed by using the electroplated copper strip of the fifth or sixth embodiment.

According to the copper strip, the electroplated copper strip, and the lead frame of the present invention, a surface plating layer having a higher reflectance can be formed.

1‧‧‧Electroplated copper strip

2‧‧‧ copper strip

3‧‧‧Base plating

4‧‧‧Surface plating

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic cross-sectional view showing an electroplated copper strip according to an embodiment of the present invention; and FIG. 2 is a flow chart showing a manufacturing step of a copper strip and an electroplated copper strip according to an embodiment of the present invention; An IPF diagram of a growth layer of a base plating layer of a copper strip according to an embodiment of the present invention; and FIG. 4 is a graph showing a relationship between a CI value and a cumulative ratio of CI values according to an embodiment of the present invention; A graph showing the relationship between the wavelength of the irradiation light of the Ag plating layer formed on the copper strip and the reflectance according to an embodiment of the present invention; and FIG. 6(a) is an Ag plating layer formed on the copper strip according to an embodiment of the present invention. SEM image of the surface, (b) an SEM image of the surface of the Ag plating layer formed on the copper strip of a comparative example of the present invention; and FIG. 7 is a SEM of the surface of the Ag plating layer conventionally formed on the copper strip image.

(information gained by the inventor, etc.)

First, the findings obtained by the inventors and the like will be described before explaining the embodiments of the present invention.

According to intensive studies by the present inventors, the reason why the reflectance of the Ag plating layer formed as a surface plating layer for reflecting light on the copper strip is reduced is, for example, as shown in FIG. The surface of the mountain's convex part (mountain-like convex part). Figure 7 is a SEM image of a conventional Ag plating layer formed on a copper strip. The SEM image shown in Fig. 7 was taken as follows: Sample of at least one of a Cu plating layer or a Ni plating layer having a copper strip, a base plating layer, and an Ag plating layer as a surface plating layer That is, the electroplated copper strip was taken from one side of the Ag plating layer by tilting 70 degrees in the up and down direction of the paper surface. This is because it is difficult to observe the mountain-like convex portion when photographing from directly above the sample. In Fig. 7, the left-right direction of the paper surface is formed as the rolling direction of the copper strip. It can be confirmed from Fig. 7 that a mountain-like convex portion is formed along the rolling direction of the copper strip. For example, it has been confirmed that the mountain-like convex portion is continuously formed in the rolling direction with a length of 10 μm to 30 μm. Further, it was confirmed that a plurality of mountain-like convex portions were formed at intervals of 30 μm to 100 μm in the direction orthogonal to the rolling direction of the copper strip.

This mountain-like convex portion is formed by crystal alignment of the crystal structure of the surface of the base plating layer (base plating growth surface) of the copper strip. In general, a copper strip is formed by repeatedly performing a rolling process and an annealing process a predetermined number of times. In this process, the crystal structure of the rolled surface of the copper strip tends to be connected to the crystal orientation of the alignment in the same direction as the rolling direction and the crystal orientation of the alignment in the direction of the rolling direction. The growth of the Cu plating layer or the Ni plating layer as the underlying plating layer depends on the rolling plane of the copper strip, that is, the crystal orientation of the crystal grains of the growth layer of the underlying plating layer. Thereby, the growth rate of the underlying plating layer differs depending on the crystal alignment of the crystal grains of the growth layer of the underlying plating layer. This is because the copper (Cu) used in the copper strip is the same FCC metal as the copper (Cu) and nickel (Ni) used in the base plating layer, and the average of Cu and Ni used in the base plating layer. Since the particle diameter is substantially the same as the particle diameter of Cu used in the copper strip, the underlying plating layer easily receives the crystal orientation of the crystal grains (Cu) on the growth layer of the underlying plating layer of the copper strip and is epitaxially grown. Thereby, uneven growth occurs in the underlying plating layer on the growth surface of the underlying plating layer, so that a difference in film formation amount (growth amount) of the underlying plating layer grown (electrodeposited) on the growth layer of the underlying plating layer occurs. That is, along the rolling direction of the copper strip, a place where the thickness of the underlying plating layer is thick and a thin place are generated. Thereby, a mountain-like convex portion is formed on the surface of the underlying plating layer. The result is known to be on the substrate. The surface of the Ag plating layer formed by growing on the plating layer forms a mountain-like convex portion, and the reflectance of the Ag plating layer is lowered. Further, on the base plating layer growth surface, there are irregularities such as ribs transferred from the surface of the rolling roll during the rolling process. However, the unevenness transferred to the growth surface of the underlying plating layer by the rolling roll during the rolling process is not directly related to the mountain-like convex portion formed on the surface of the Ag plating layer.

Therefore, the present inventors thought that it is necessary to make the surface of the Ag plating layer flatter depending on the state of the crystal structure of the growth layer of the base plating layer of the copper strip. In other words, in order to form an Ag plating layer having a higher reflectance, it is necessary to adjust the state of the crystal structure (grain) of the growth layer of the underlying plating layer of the copper strip. The present invention has been made based on the above findings discovered by the inventors and the like.

(1) Composition of copper strip and electroplated copper strip

First, the configuration of the copper strip and the electroplated copper strip according to an embodiment of the present invention will be mainly described using FIG. Fig. 1 is a schematic cross-sectional view showing a plated copper strip 1 of the present embodiment.

As shown in Fig. 1, the plated copper strip 1 is composed of a copper strip 2, a base plating layer 3, and a surface plating layer 4. On the at least one main surface of the copper strip 2, the underlying plating layer 3 is formed by growth. Copper strip 2 combines good mechanical strength and electrical conductivity. The copper strip 2 is formed by subjecting an ingot such as copper or a copper alloy to rolling treatment, annealing treatment, or the like.

As a material for forming the copper strip 2, a copper alloy containing iron (Fe), nickel (Ni), cobalt (Co) or the like can be used. For example, as the material for forming the copper strip 2, a Cu-Fe-P-based copper alloy containing Fe and phosphorus (P) may be used. As the Cu-Fe-P-based copper alloy, for example, a copper alloy (C19210) containing 0.05% by weight to 0.15% by weight of Fe and 0.025% by weight to 0.04% by weight of P, which is 2.1% by weight to 2.6% by weight, is widely known. Fe, 0.015 wt% to 0.15 wt% of P and 0.05 wt% to 0.20 wt% of a zinc (Zn) copper alloy (C19400). Further, for example, as a material for forming the copper strip 2, an oxygen-free copper (OFC, Oxyger Free Copper) or a Cu-Zr-based copper alloy containing zirconium (Zr) (for example, C15150) may be used, and each of them may contain a predetermined amount of Zn. And copper alloys of Ni and P and Corson of bismuth (Si). Therefore, it is considered that the copper alloy strip formed using a copper alloy in the present embodiment is also included in the copper strip 2.

Regarding the surface of the base plating layer of the copper strip 2 (hereinafter, also simply referred to as "base plating growth surface"), that is, the rolled surface of the copper strip 2 is grown on the underlying plating layer at the growth rate of the underlying plating layer 3. The faces are formed in a uniform manner in the plane. In other words, in the base plating layer growth surface, an amorphous region or a region in which crystal grains having a very small crystal grain size (fine crystal grains of about 10 nm or less in terms of diameter) are formed (hereinafter, , also known as "fine grain area") Any one. Further, at least one of the amorphous region or the fine crystal grain region may be uniformly distributed in the growth surface of the underlying plating layer. Thereby, the growth rate of, for example, a copper (Cu) plating layer or a nickel (Ni) plating layer as the underlying plating layer 3 is formed in-plane uniformity in the in-plane growth of the underlying plating layer. Therefore, the thickness of the base plating layer 3 is formed to be in-plane uniform in the growth surface of the base plating layer, and the surface of the base plating layer 3 is formed to be flat. As a result, as will be described later, the surface of the silver (Ag) plating layer which is light-reflected as the surface plating layer 4 formed on the base plating layer 3 is flattened, so that the reflectance of the surface plating layer 4 can be improved.

The base plating plating growth surface was obtained by measuring with an EBSD (Electron Back Scattering Diffracted Pattern) method in which the measurement region (observation region) was 90 μm×120 μm and the measurement interval (step size) was 0.2 μm. The reliability index (CI value, Confidence Index value) is 0.1% or less, and the ratio of the measurement points is 50% or more, preferably 68% or more.

The ratio of the measurement points having a CI value of 0.1 or less refers to the ratio of the measurement points having a CI value of 0.1 or less in the measurement region to the total number of measurement points. For example, when the measurement area is 90 μm × 120 μm and the step size is 0.2 μm, the total number of measurement points in the measurement area is 270,000 points. Therefore, in this case, the ratio of the measurement points having a CI value of 0.1 or less is 50% or more, and the number of measurement points having a CI value of 0.1 or less is 135,000 or more.

In addition, the CI value is a value indicating the reliability (measurement accuracy) of the result of measurement and analysis of the crystal orientation of the crystal grains of the underlying plating layer growth surface by the EBSD method using the EBSD method. By using the EBSD method, information on only the top surface of the copper strip 2 can be obtained. For example, when the accelerating voltage is set to 20 kV, only information from the growth surface of the underlying plating layer to a depth of about 30 nm to 50 nm can be obtained. In addition, the CI value can be determined for each measurement point. In the EBSD method, it is difficult to accurately measure the crystal orientation of crystal grains in the following regions: an amorphous region and a plurality of fine crystal grains having different crystal orientations in one measurement point (for example, about 10 nm in diameter) The area of the following crystal grains (ie, the fine grain area). Therefore, at such a measurement point, the reliability of the analysis result based on the EBSD method is lowered, and the CI value is lowered. In other words, regarding the measurement point having a CI value of 0.1 or less, it is determined that there is a possibility that the crystal alignment of the crystal grains is not accurately measured by the EBSD method. Therefore, the measurement point having a CI value of 0.1 or less is determined to be an amorphous region or a fine crystal grain region. On the other hand, in the measurement point where the CI value exceeds 0.1, it is determined that the crystal orientation of the crystal grains is accurately measured by the EBSD method and analyzed. That is, the measurement point where the CI value exceeds 0.1 It is determined that the crystallization is progressing and the crystallinity is high (not the amorphous region or the fine crystal grain region). Further, the method of measuring the CI value will be described later.

As described above, the base plating layer growth surface may have a ratio of a measurement point having a CI value of 0.1 or less in a predetermined measurement region of 50% or more, preferably 68% or more. In the case of such a base plating layer growth surface, substantially, crystal grains having the same crystal orientation are not continuously formed along the rolling direction of the copper strip 2 by a length of 10 μm to 30 μm. Therefore, when the underlying plating layer 3 is grown on the growth surface of the underlying plating layer of the copper strip 2, the growth rate of the underlying plating layer 3 can be made uniform in the surface of the underlying plating layer growth surface. Thereby, the underlying plating layer 3 is uniformly grown on the growth surface of the underlying plating layer, so that the surface of the underlying plating layer 3 is formed to be flat. As a result, the surface of the surface plating layer 4 formed on the underlying plating layer 3 can be formed flat, and the reflectance of the surface plating layer 4 can be improved.

Further, the measurement points having a CI value of 0.1 or less may be distributed as uniformly as possible within the measurement region. Thereby, the growth rate of the underlying plating layer 3 can be made uniform in the surface of the growth layer of the underlying plating layer.

For the determination of the CI value, for example, in the plating of the base layer by chemical etching After the surface (that is, the measurement surface) is removed by 50 nm or more, it is preferably carried out after removing 50 nm or more and 100 nm or less. Thereby, the natural oxide film formed on the growth surface of the underlying plating layer and the contaminant adhering to the growth surface of the underlying plating layer can be removed. Therefore, for example, it is possible to suppress the case where the region having high crystallinity is determined to be an amorphous region or a fine crystal grain region. As a result, the measurement of the CI value of the growth surface of the underlying plating layer can be performed more accurately.

(Method for measuring CI value)

Hereinafter, a method of obtaining the CI value of the underlying plating layer growth surface by measuring the growth surface of the underlying plating layer of the copper strip 2 by the EBSD method will be described.

First, an electron beam is irradiated onto a plurality of measurement points (irradiation points) on the growth surface of the base plating layer of the copper strip 2 using, for example, an EBSD apparatus, thereby obtaining a diffraction pattern (electron backscatter diffraction image) at each measurement point. As the EBSD device, for example, an OIM (Orientation Imaging Microscopy) device manufactured by TSLSolutions Co., Ltd., which is a scanning electron microscope (SU-70) manufactured by Hitachi High-Technologies Co., Ltd., can be used. When the electron beam is irradiated onto the base plating growth surface of the copper strip 2, the copper strip 2 is held at an inclination angle of, for example, 70°. In addition, the acceleration voltage of the EBSD device is set to, for example 20kV. Thereby, it is possible to obtain only information from the growth surface of the underlying plating layer to a depth of about 30 nm to 50 nm.

Next, based on the obtained diffraction pattern of each measurement point, the crystal alignment of the crystal grains in each measurement point was determined. That is, for example, the diffraction pattern of each measurement point is analyzed by a computer, and the crystal alignment which is judged to be the most reliable is selected by the computer. Further, the selected crystal alignment was determined as the crystal alignment in each measurement point. At this time, when the growth surface of the underlying plating layer is an amorphous region, a diffraction pattern cannot be obtained. Further, when the underlying plating layer growth surface is a fine crystal grain region, even if a crystal grain of a lattice image is obtained by high resolution TEM, a diffraction pattern may not be obtained in an EBSD device. In other words, when the underlying plating layer growth surface is a fine crystal grain region, a plurality of fine crystal grains having different crystal orientations are included in one measurement point, and thus a diffraction pattern cannot be obtained similarly to the amorphous region. Therefore, when the diffraction pattern is analyzed by a computer, for example, in an amorphous region or a fine crystal grain region on the growth surface of the underlying plating layer, the computer selects a random sampling point at each measurement point without obtaining a diffraction pattern. Crystallographic alignment.

Specifically, the determination of the crystal orientation at each measurement point is carried out as described below. For example, when the surface to be analyzed by the EBSD method for measuring the crystal orientation (that is, the underlying plating layer growth surface) is an FCC metal such as copper (Cu), the EBSD device (the OIM analysis software included in the EBSD device) is usually used from each measurement point. The diffraction pattern detects 7 bands (detection lines), respectively. Further, three bands are selected from the detected seven bands, and the crystal alignment is estimated based on the angular relationship. The combination of three bands selected from the seven bands is 35 types. Therefore, the crystal orientation is estimated for each of the 35 combinations. It is not limited to the fact that the crystal alignments estimated in each combination are all formed in the same alignment. In other words, the crystal alignment estimated in each combination is not limited to one, and there are cases where a plurality of crystal alignments are estimated. Among the crystal orientations estimated for each of the 35 combinations, the crystal orientation which is most estimated is determined as the crystal orientation in the measurement point.

Next, based on the crystal orientation in each of the obtained measurement points, the alignment difference of the crystal orientation in the adjacent measurement points was calculated. If the alignment difference is less than the Tolerance Angle (for example, 5°), it is regarded as the same crystal grain, and if the alignment difference is an allowable angle (for example, 5°) or more, it is regarded as a different crystal grain.

The crystal grains were classified according to the obtained crystal orientation, and an IPF (Inverse Pole Figure) map was obtained. At this time, the same color is imparted to the crystal grains having the same crystal alignment. That is, in the IPF diagram, regarding the crystallized region, according to the size (particle diameter) of the crystal grains thereof And show the area of the same color.

Next, the reliability index (CI value) of each measurement point was obtained by calculation. Hereinafter, a method of calculating the CI value will be described by taking a case where the three bands are selected from the above seven bands and the crystal alignment in each measurement point is determined as an example. In other words, among the crystal orientations estimated in each of the 35 combinations, the number of times of the estimated crystal alignment is referred to as, for example, a number of Votes. It can be said that the greater the difference between the maximum Vote number and the second largest Vote number, the higher the reliability of the estimated crystal alignment. The CI value is calculated based on the following (Formula 1) based on such findings.

(Formula 1) CI value = (V1-V2) / V _ideal

Here, V1 is the maximum Vote number, V2 is the second largest Vote number, and V _ideal is the combined number. For example, when three bands are selected from the seven bands, V _ideal is 35.

The CI value is a value from 0.0 to 1.0. For example, in the case of a combination of 35 types, the CI value = 1.0 at V1 = 35 and V2 = 0, and the reliability is the highest. On the other hand, when V1 = V2, the CI value = 0.0, and the reliability is the lowest.

In general, in a FCC metal such as Cu, when the CI value is 0.2 to 0.3 or more, it can be said that the crystal alignment is accurately measured with a probability of 90% or more. On the other hand, in the measurement point where the CI value is 0.1 or less, the crystal alignment which is most estimated (the maximum number of Votes) is the same as the crystal orientation of the second most estimated (the second largest Vod number). The probability of the degree of selection is chosen, and thus the reliability of the selected crystal alignment is low. That is, a measurement point having a CI value of 0.1 or less is an amorphous region or a fine crystal grain region in which a diffraction pattern cannot be obtained. In this order, the CI values were calculated at all measurement points.

In addition, when the IPF map is compared with the distribution of the CI values of all the measurement points, the more the measurement points are, the more the measurement points are 0.1 or less, the more amorphous regions or fine crystals. A place with many grain areas.

As described above, the underlying plating layer 3 is formed by growth on the growth surface of the underlying plating layer of the copper ribbon 2. As the underlying plating layer 3, at least one of a copper (Cu) plating layer or a nickel (Ni) plating layer may be formed by growth. As described above, at least one of an amorphous region or a fine crystal grain region is formed on the base plating layer growth surface of the copper strip 2 on which the underlying plating layer 3 is formed. Thereby, the growth rate of the underlying plating layer 3 is formed to be in-plane uniform on the growth surface of the underlying plating layer of the copper ribbon 2. Therefore, the base plating layer 3 is uniformly produced in-plane on the growth surface of the base plating layer. The length is such that the surface of the base plating layer 3 is formed to be flat. That is, the smoothness of the surface of the underlying plating layer 3 can be improved.

On the base plating layer 3, a surface plating layer 4 is formed by growth. As the surface plating layer 4, for example, a silver (Ag) plating layer having a high reflectance (light reflectance) may be formed by growth. The surface plating layer 4 may be formed by, for example, growth by electroplating. Thus, the surface plating layer 4 is formed on the base plating layer 3 whose surface is flat (i.e., highly smooth). Thereby, the surface plating layer 4 is uniformly grown in the upper surface of the base plating layer 3, thereby making the surface of the surface plating layer 4 flat. That is, the smoothness of the surface of the surface plating layer 4 can be improved. Therefore, the gloss of the surface plating layer 4 can be improved, and the reflectance can be improved.

Such an electroplated copper strip 1 is preferably used for, for example, a lead frame or the like. For example, the plated copper strip 1 is subjected to press working using a mold or the like to form, for example, a lead frame.

(2) Copper tape and method for manufacturing the same

Next, an embodiment of the copper strip 2 and the method of manufacturing the plated copper strip 1 of the present embodiment will be mainly described using FIG. 2 . Fig. 2 is a flow chart showing the steps of manufacturing the copper strip 2 and the plated copper strip 1 of the present embodiment.

(casting step (S10))

As shown in FIG. 2, first, a copper melt is produced by melting copper (Cu) as a base material using an electric furnace such as a kiln type melting furnace or a channel type melting furnace. Further, in the case of casting an ingot of a copper alloy, a predetermined amount of a predetermined element is added to the molten metal of copper to produce a molten metal of a copper alloy. Then, by supplying the molten metal of the copper or the molten alloy of the copper alloy to the mold, an ingot (block) of copper or copper alloy having a thickness of about 150 mm to 250 mm and a width of about 400 mm to 1000 mm and having a rectangular cross section is cast. (cake)).

(hot rolling step (S20))

After the casting step (S10) is completed, the cast block is heated to a predetermined temperature and subjected to hot rolling treatment to form a hot rolled material having a predetermined thickness. That is, the block is carried in a heating furnace heated to a predetermined temperature (for example, 800 ° C or more and 1000 ° C or less). Then, the block is heated in a heating furnace for a predetermined time (for example, 30 minutes or longer) to heat the block. After the lapse of a predetermined period of time, the block is carried out from the heating furnace, and the hot-rolled material is rolled, for example, at a room temperature to form a block having a predetermined thickness (for example, 10 mm to 15 mm) to form a hot-rolled material. After the completion of the hot rolling treatment, the hot rolled material may be cooled as quickly as possible to, for example, room temperature.

The treatment temperature of the hot rolling treatment, that is, the heating temperature of the heating furnace may be adjusted according to the chemical composition of the copper alloy. For example, in a copper alloy (precipitated copper alloy) in which an additive added to a copper alloy is precipitated, the treatment temperature of the hot rolling treatment (particularly, the starting temperature of the hot rolling treatment) is made to be an element added to the copper alloy. The temperature of the solution can be. Thereby, the oxide film (scale) formed on the surface of the hot-rolled material can be reduced by the hot rolling treatment. That is, when the treatment temperature of the hot rolling treatment is too high, the scale formed on the surface of the hot rolled material may increase.

(face cutting step (S30))

After the completion of the hot rolling step (S20), the surface film is subjected to surface cutting to remove the oxide film (scale) formed on the surface of the hot-rolled material by the hot rolling treatment, and the oxide film is removed.

(cold rolling step, annealing step (S40, S50))

After the surface-cutting step (S30) is completed, the hot-rolled material is subjected to a cold rolling treatment (a cold rolling step (S40)) of a predetermined degree of processing for a predetermined number of times, and an annealing treatment for a predetermined time at a predetermined temperature (annealing step (S50) )), forming a cold-rolled material called a billet of a predetermined thickness. The strength of the copper strip 2 can be improved by imparting a processing strain caused by the cold rolling treatment to the hot rolled material. Further, the annealing treatment may also include an aging treatment.

(buffing step (S60))

After the predetermined number of cold rolling steps (S40) and annealing steps (S50) are repeated, a polishing process of polishing the rolled surface of the cold rolled material, that is, the surface formed as the underlying plating growth surface, is performed. The polishing treatment is performed in such a manner that at least one of an amorphous region or a fine crystal grain region is formed on the base plating layer growth surface (ie, the rolled surface) of the copper strip 2 . In other words, in the EBSD method, the ratio of the measurement points of the base plating layer growth surface obtained by measuring the measurement area to 90 μm × 120 μm and the step size of 0.2 μm is 0.1 or less is 50. It is sufficient to carry out the method of % or more, preferably 68% or more. The polishing treatment is performed, for example, by using a cylindrical buff which has a polishing abrasive attached to the surface. Further, by rotating such a polishing wheel on a growth surface of the base plating layer of the copper strip 2 in a predetermined direction (for example, clockwise direction), the base plating growth surface of the copper strip 2 is ground by using the abrasive on the surface of the polishing wheel. At least one of an amorphous region or a fine crystal grain region is formed on the growth surface of the base plating layer. At this time, as the abrasive, a abrasive having a particle size corresponding to #600 to #3000 can be used.

(finishing step (S70))

After the completion of the polishing step (S60), the cold-rolled material is subjected to a finish rolling treatment at a predetermined degree of work to form a copper strip 2 having a predetermined thickness (for example, 0.2 mm). Further, after the finish rolling step (S70) is completed, the copper strip 2 may not be annealed. When the annealing treatment is performed after the completion of the finish rolling step (S70), the crystal structure of the growth layer of the underlying plating layer of the copper strip 2 sometimes changes. In other words, the amorphous region or the fine crystal grain region formed on the growth surface of the underlying plating layer may not be an amorphous region or a fine crystal grain region. Thereby, the copper strip 2 of this embodiment is manufactured.

(Substrate plating layer forming step (S80))

After the finish rolling step (S70) is completed, the underlying plating layer 3 having a predetermined thickness is formed on the underlying plating growth surface (rolled surface) of the copper strip 2. As the base plating layer 3, at least one of, for example, a Cu plating layer or a Ni plating layer is formed.

(Surface plating layer forming step (S90))

When the base plating layer forming step (S80) is completed, on the underlying plating layer 3, as the surface plating layer 4 for reflecting light, for example, an Ag plating layer is formed. Thus, the manufacturing step is completed by manufacturing the plated copper strip 1 of the present embodiment.

(3) Effects of the present embodiment

According to the present embodiment, one or a plurality of effects described below are exhibited.

(a) According to the present embodiment, the base plating layer growth surface of the copper strip 2 having the underlying plating layer growth surface 3 is formed in such a manner that the growth rate of the underlying plating layer 3 is uniform in the surface of the underlying plating layer growth surface. There is at least one of an amorphous region or a fine crystal grain region. Thereby, the underlying plating layer 3 is uniformly grown on the growth surface of the underlying plating layer, and thus the surface of the underlying plating layer 3 is formed to be flat. As a result, the surface of the surface plating layer 4 (for example, an Ag plating layer) formed by growing on the underlying plating layer 3 becomes flat, and the light reflectance of the surface plating layer 4 is improved.

(b) According to the present embodiment, the base plating layer growth surface is a reliability index (CI value) obtained by measuring the measurement region to be 90 μm × 120 μm by the EBSD method and measuring at a measurement interval of 0.2 μm. The ratio of the measurement points is 50% or more, preferably 68% or more. That is, the base plating layer growth surface is a surface having an amorphous region or a fine crystal grain region of 50% or more, preferably 68% or more. Thereby, on the base plating layer growth surface of the copper strip 2, a base plating layer 3 having a flat surface can be grown. Therefore, the surface of the surface plating layer 4 which is formed by growing on the base plating layer 3 can be made flatter, and the light reflectance of the surface plating layer 4 can be further improved.

(c) According to the present embodiment, the CI value of the growth surface of the underlying plating layer is measured after removing the underlying plating layer growth surface by chemical etching by 50 nm or more. Thereby, a more accurate CI value of the growth surface of the underlying plating layer can be obtained.

(d) According to the present embodiment, the plated copper strip 1 is configured by including a copper strip 2 having a base plating layer growth surface that forms at least one of an amorphous region or a fine crystal grain region. That is, on the growth surface of the base plating layer of the copper strip 2, the underlying plating layer 3 and the surface plating layer 4 are sequentially grown from one side of the copper strip 2, thereby forming the electroplated copper strip 1. Therefore, in the electroplated copper strip 1, the surface of the surface plating layer 4 becomes flat, and the light reflectance becomes high.

(e) According to the present embodiment, the lead frame is formed using the plated copper strip 1. Thereby, for example, when a light-emitting element is mounted on a lead frame to form a light-emitting diode, the light extraction efficiency of the light-emitting diode can be improved.

(Other embodiments of the present invention)

The embodiment of the present invention is specifically described above, but the present invention is not limited to the above-described embodiments, and can be appropriately modified without departing from the scope of the invention.

For example, a lead frame is formed using the plated copper strip 1 forming the underlying plating layer 3 and the surface plating layer 4, and when a light-emitting element is mounted on the lead frame to form a light-emitting diode (LED), the copper strip 2 and the external wiring are formed. The connection portion can also be plated in order to improve the reliability of the electrical connection. As such a plating treatment, for example, silver (Ag), nickel (Ni), palladium (Pd) or the like may be used.

In addition, the copper strip 2 can also be used for applications other than the lead frame. For example, on the growth surface of the base plating layer of the copper strip 2, if another plating layer containing FCC metal is formed by growth, the underlying plating layer 3 and the surface plating layer 4 may not be formed. In this case, the surface of the plating layer can also be flattened to improve the gloss. Therefore, it can be effectively applied to all applications in which the appearance and the gloss of the surface of the plating layer are emphasized.

Example

Hereinafter, embodiments of the invention will be described, but the invention is not limited thereto.

(Example 1)

An alloy (C194: CDA No. C19400) containing 2.1 wt% to 2.6 wt% of iron (Fe), 0.05 wt% to 0.2 wt% of zinc (Zn), and 0.015 wt% to 0.15 wt was used in Example 1. % phosphorus (P), and the remainder is formed by more than 97% by weight of copper (Cu) and unavoidable impurities. this At the time, 97 wt% or more of Cu is contained in the copper alloy. Further, the copper alloy was melted in a krypton melting furnace under a nitrogen atmosphere to prepare a molten metal. Then, the melt is supplied to the mold, and a block having a predetermined width is cast at a predetermined thickness.

Next, the block is heated to a predetermined temperature and subjected to hot rolling treatment to produce a hot rolled material having a predetermined thickness. Then, the hot-rolled material is subjected to cold rolling treatment and annealing treatment of a predetermined degree of processing for a predetermined number of times to produce a cold-rolled material having a predetermined thickness. Further, the annealing treatment is carried out under a reducing atmosphere.

Then, the rolled surface of the cold rolled material, that is, the surface on which the growth surface of the underlying plating layer is formed is subjected to a polishing treatment under a predetermined condition. The polishing treatment is performed in such a manner that an amorphous region or a fine crystal grain region is formed on the underlying plating growth surface (ie, the rolled surface) of the copper ribbon as the produced sample. Then, the cold-rolled material subjected to the buffing treatment was subjected to finish rolling treatment at a predetermined degree of work to produce a copper strip having a thickness of 0.2 mm. This was made into the sample of Example 1.

(Examples 2 to 9 and Comparative Examples 1 to 8)

In Examples 2 to 9 and Comparative Examples 1 to 8, the types of copper alloys were as shown in Table 1, and the polishing treatment conditions were changed. Others, a copper tape was produced in the same manner as in the above-described Example 1. These were used as the samples of Examples 2 to 9 and Comparative Examples 1 to 8, respectively.

Further, the OFC in Table 1 means copper (oxygen-free copper) containing less than 0.0010% by weight of oxygen (O) and the remainder being composed of 99.95 wt% or more of Cu and unavoidable impurities (CDA No. C10200) . In addition, HCL02Z is a copper alloy (CDA No. C15150) containing 0.015 wt% to 0.03 wt% of zirconium (Zr) and a total weight of Cu and Zr (Cu + Zr) of 99.96 wt% or more. In addition, HCL305 is called a Corson-based copper alloy, and includes 1.5 wt% to 2.0 wt% of zinc zinc (Zn), 2.2 wt% to 2.8 wt% of nickel (Ni), and 0.015 wt% to 0.06 wt%. Phosphorus (P), 0.3 wt% to 0.7 wt% of bismuth (Si), and the balance being a copper alloy formed of Cu and unavoidable impurities.

(pre-processing steps)

Next, with respect to each of the samples of Examples 1 to 9 and Comparative Examples 1 to 8, a cathodic electrolytic degreasing step and a pickling step were carried out under the conditions shown in Table 2, and a pretreatment for cleaning the surface of the sample was performed. That is, by performing the pretreatment, the natural oxide film formed on the surface of each sample and the contaminant adhering to the surface of each sample are removed. Further, regarding the processing conditions of the pickling step in the present embodiment, conditions for the pickling treatment in the mass-producing Ag plating line in the case where a silver (Ag) plating layer is formed as a surface plating layer by growth on each sample is assumed and determined. . In addition, the conditions of the pickling treatment are conditions in which the amount of etching increases in the range of the conditions of the pickling treatment in the mass production Ag plating line. Specifically, the amount (etching amount) to be etched in the pickling treatment in the mass production Ag plating line is generally 50 nm to 100 nm. Therefore, in the present embodiment, the processing conditions such that the etching amount in the pickling step is 50 nm to 100 nm are also set.

Table 2

As shown in Table 2, in the cathode electrolytic degreasing step, a SUS plate was used as an anode, and in an aqueous solution containing 20 g/L of sodium hydroxide and 20 g/L of sodium carbonate, the liquid temperature was set to 40 ° C, and the current density was set. For 5 A/dm ² , the treatment time was set to 30 seconds, and each sample was subjected to electrolytic degreasing treatment. After the end of the cathodic electrolytic degreasing step, each sample was washed with water. Then, in the pickling step, the liquid temperature of the aqueous solution was set to room temperature in an aqueous solution containing 5 wt% of sulfuric acid and 10 g/L of potassium persulfate, and each sample was immersed in an aqueous solution for 10 seconds to carry out pickling treatment. In the pickling step, when the etching rate fluctuates due to temperature conditions, deterioration of potassium persulfate (oxidizing agent), etc., the processing time of the pickling treatment is appropriately adjusted so that the etching amount is 50 nm to 100 nm (impregnation) Time).

<Evaluation of Growth Surface of Substrate Plating Layer>

The base plating layer growth surface (that is, the rolling surface) of each of the samples of Examples 1 to 9 and Comparative Examples 1 to 8 before the completion of the treatment step was evaluated. The evaluation of the underlying plating growth surface can be performed more accurately after the end of the pre-treatment step.

(Calculation of the ratio of the measurement points with a CI value of 0.1 or less)

First, under the conditions shown in Table 3, the ratio of the measurement points at which the CI value of the underlying plating layer growth surface of each of the samples of Examples 1 to 9 and Comparative Examples 1 to 8 was 0.1 or less was calculated. The results are shown in Table 1.

In other words, as shown in Table 3, OIM, Orientation Imaging Microscopy, manufactured by TSL Solutions, Inc., a scanning electron microscope (SU-70) manufactured by Hitachi High-Technologies Co., Ltd., was used as the EBSD device. ) device. Further, each sample was held at an inclination of 70°, and an electron beam was irradiated onto a plurality of measurement points (irradiation points) on the growth layer (rolling surface) of the underlying plating layer of each sample using an EBSD apparatus, thereby obtaining at each measurement point. Diffraction pattern (electron backscatter diffraction image). At this time, the acceleration voltage of the scanning electron microscope was set to 20 kV, and the observation magnification was set to 1000 times. Further, when the electron beam was irradiated by the EBSD apparatus, each sample was held at an inclination of 70°. Thereby, the focus is displaced by the electron beam irradiation position (measurement point). When the measurement is performed in a state where the focus is not aligned, the IQ (image quality) value is lowered, and proper measurement and analysis cannot be performed, so that the tilt focus correction is performed. In addition, the tilt focus correction is accurately performed in accordance with the observation magnification. Further, an IPF pattern was prepared based on the obtained crystal alignment. Further, based on the obtained diffraction pattern of each measurement point, the crystal orientation of crystal grains in each measurement point was measured and analyzed, and the CI value at each measurement point was obtained by calculation.

Next, with respect to each of the samples of Examples 1 to 9 and Comparative Examples 1 to 8, the CI values obtained for all the measurement points were calculated, and the measurement points in the observation region were calculated to be 0.1 or less with respect to The ratio of the total number of points measured. In this embodiment, due to the observation area It is 90 μm × 120 μm, and the measurement interval (step size) is 0.2 μm, so the total number of measurement points in the observation area is 270,000 points.

(analysis result of the growth surface of the base plating layer of the copper strip)

An example of the obtained IPF map is shown in Fig. 3. Fig. 3 is an IPF chart of each of the samples of Example 1, Example 2, Example 9, Comparative Example 1, and Comparative Example 2 using C194 as a copper alloy. According to the third drawing, it was confirmed that each of the samples of Example 1, Example 2, and Example 9 had an amorphous region or a fine crystal grain region formed on the growth surface of the underlying plating layer. That is, it was confirmed that the base plating layer growth faces of the respective samples of Example 1, Example 2, and Example 9 showed that the same crystal alignment was exhibited by a plurality of consecutive measurement points, or the alignment difference was shown to be smaller than the allowable angle (Tolerance Angle). 5° in the present embodiment is thus regarded as the same crystal grain, where the crystal grains identified as having a large particle diameter are interspersed, but in most places of the observation area, at each measurement point, by the display Random crystallized grain formation. Further, it was confirmed that in the growth layer of the underlying plating layer of each of the samples, the amorphous region or the fine crystal grain region was uniformly distributed in the observation region, that is, it was not biased at a specific place.

On the other hand, it was confirmed that crystal grains having a large particle diameter were formed on the growth surface of the underlying plating layer of each of the samples of Comparative Example 1 and Comparative Example. Further, it was confirmed that these crystal grains were continuously formed in a predetermined length along the rolling direction (the vertical direction of the paper surface). In other words, it was confirmed that the crystal structure of the underlying plating layer growth surface of each of the samples of Comparative Example 1 and Comparative Example 2 was associated with the crystal orientation of the alignment in the same direction as the rolling direction and the crystal orientation of the alignment in the direction of the rolling direction. .

(analysis result of cumulative distribution of CI values)

Further, the analysis results of the cumulative distribution of the CI values of the respective samples of Example 1, Example 2, Example 9, Comparative Example 1, and Comparative Example 2 are shown in Fig. 4 . Figure 4 is a graph showing the relationship between the CI value and the cumulative ratio of CI values. That is, in the graph shown in Fig. 4, for example, the cumulative ratio of the CI values in the place where the CI value is 0.3 indicates all the measurement points having a CI value of 0.3 or less (including, for example, a CI value of 0.1 or 0.2). The ratio of the measurement point). According to Fig. 4 and Table 1, it was confirmed that the ratio of the measurement points having a CI value of 0.1 or less in the predetermined observation region was 85% in the sample of Example 1, and 68% in the sample of Example 2, It was 52% in the sample of Example 9, 37% in the sample of Comparative Example 1, and 16% in the sample of Comparative Example 2. Further, it was confirmed from Fig. 4 that in each of the samples of Example 1, Example 2, and Example 9, the number of measurement points having a CI value exceeding 0.1 was small, and thus when the CI value exceeded 0.1, the gradient of the cumulative graph became gentle. Also confirmed that in Comparative Example 1 In each of the samples of Comparative Example 2, since the CI value exceeded 0.1, the curve of the CI value exceeded 0.1 as compared with the cumulative graph of each of the samples of Example 1, Example 2, and Example 9. The gradient becomes larger.

(Evaluation results of the growth surface of the base plating layer of the copper strip)

According to Fig. 3 and Fig. 4, it was confirmed that the more the measurement points having a CI value of 0.1 or less on the growth surface of the base plating layer of the copper strip, the more amorphous regions or fine crystal grains are formed in the observation region. Grain area. In other words, it was confirmed that the measurement point having a CI value of 0.1 or less is an amorphous region or a fine crystal grain region, and thus the crystal alignment cannot be accurately measured.

<Evaluation of reflectance>

Next, on the underlying plating growth faces of the samples of Examples 1 to 9 and Comparative Examples 1 to 8, under the conditions shown in Table 4, a base plating layer was formed by growth, and growth was performed on the underlying plating layer. A surface plating layer is formed to separately produce an electroplated copper strip. Then, the reflectance of the surface plating layer was measured and evaluated.

(pre-processing steps)

Specifically, first, each of the samples of Examples 1 to 9 and Comparative Examples 1 to 8 was subjected to a cathodic electrolytic degreasing step and a pickling step under the conditions shown in Table 4, and a pretreatment for cleaning the surface of the sample was performed. That is, in the cathode electrolytic degreasing step, a SUS plate was used as an anode, and in an aqueous solution containing 20 g/L of sodium hydroxide and 20 g/L of sodium carbonate, the liquid temperature was set to 40 ° C, and the current density was set to 5 A/dm ^{2 .} The treatment time was set to 30 seconds, and each sample was subjected to electrolytic degreasing treatment. After the end of the cathodic electrolytic degreasing step, each sample was washed with water. Then, in the pickling step, the liquid temperature of the aqueous solution was set to room temperature in an aqueous solution containing 5 wt% of sulfuric acid and 120 g/L of potassium persulfate, and each sample was immersed in an aqueous solution for 10 seconds to carry out pickling treatment. In the pickling step, when the etching rate is changed by temperature conditions, deterioration of potassium persulfate (oxidizing agent), etc., the processing time of the pickling treatment is appropriately adjusted so that the etching amount is 50 nm to 100 nm (impregnation) Time). Thereby, the natural oxide film formed on the surface of each sample and the contaminant adhering to the surface of each sample were removed.

(Substrate plating step forming step)

Next, the base plating layer growth surface of each of the samples 1 to 9 and the comparative examples 1 to 8 of the above pretreatment step was completed, and under the conditions shown in Table 4, a base plating of a predetermined thickness was formed by growth. Floor. As the underlying plating layer, any one of a copper (Cu) plating layer or a nickel (Ni) plating layer is grown. Further, the target plating thickness (target filming amount) of the underlying plating layer was formed to be 1 μm.

That is, in the case where a Cu plating layer is formed as the underlying plating layer, in the base plating layer forming step, a Cu plate is used as an anode, and in a solution containing copper sulfate pentahydrate 200 g/L and sulfuric acid 100 g/L, the liquid temperature is used. The substrate plating layer was formed by growth at 40 ° C, a current density of 5 A/dm ² , and a treatment time of 55 seconds.

Further, in the case where a Ni plating layer is formed as the underlying plating layer, in the base plating layer forming step, a Ni plate is used as an anode, and nickel sulfate hexahydrate 280 g/L and nickel chloride hexahydrate 45 g/L and boric acid are contained. In the 45 g/L aqueous solution, the liquid temperature was set to 40 ° C, the current density was set to 5 A/dm ² , and the treatment time was set to 55 seconds, and the underlying plating layer was formed by growth.

(surface plating layer forming step)

Next, each of the samples of Examples 1 to 9 and Comparative Examples 1 to 8 in which the underlying plating layer was formed was subjected to growth under the conditions shown in Table 4 to form a surface plating layer. That is, a silver (Ag) plating layer as a surface plating layer was formed by growth on the underlying plating layer of each sample. Further, the target plating thickness (target filming amount) of the surface plating layer was formed to be 3 μm.

That is, in the surface plating layer forming step, the liquid temperature is set to room temperature in an aqueous solution containing 36 g/L of silver cyanide, 60 g/L of potassium cyanide, 15 g/L of potassium carbonate, and 70 mg/L of potassium selenocyanate. The current density was set to 4 A/dm ² , and the treatment time was set to 210 seconds, and an Ag plating layer as a surface plating layer was formed by growth.

(Measurement of reflectance)

Next, the reflectance of the electroplated copper strip produced by using each of the samples of Examples 1 to 9 and Comparative Examples 1 to 8 was measured. The reflectance of each sample after the completion of the surface plating layer formation step was measured. That is, the reflectance of each sample in which the underlying plating layer and the surface plating layer were formed was measured. The measurement of the reflectance of each sample was performed as follows, under the conditions shown in Table 5.

As shown in Table 5, as a device for measuring the reflectance, a device in which a device manufactured by Ocean Photonics Co., Ltd. was combined was used. Further, the wavelength of the irradiation light was changed in the range of 350 nm to 850 nm, and the reflectance at each wavelength was measured. First, wavelengths of 350 nm to 850 nm were respectively irradiated onto the surface of a mirror panel as a standard plate, and the amount of reflected light at each wavelength was measured. Next, the surfaces of the surface plating layers of the samples of Examples 1 to 9 and Comparative Examples 1 to 8 were each irradiated with wavelengths of 350 nm to 850 nm, and the amounts of reflected light at respective wavelengths were measured. Then, the ratio of the amount of reflected light of each sample at each wavelength to the amount of reflected light of the standard plate was calculated, and this was set as the reflectance (%) of each sample. That is, the reflectance (%) of each sample is represented by the relative reflectance when the reflectance of the standard plate is 100%. Therefore, when the reflectance exceeds 100%, the amount of reflected light is larger than that of the standard plate, and more light than the incident light is reflected. Further, in the present embodiment, for the sake of simplicity, the reflectance at a wavelength of 550 nm having a high sensitivity in the human eye is compared. The results are shown in Table 1.

(evaluation of reflectance)

In Fig. 5, the measurement results of the reflectance of the electroplated copper strip formed by using each of the samples of Example 1 and Comparative Example 2 at respective wavelengths are shown in a graph. It was confirmed from Fig. 5 that the electroplated copper strip formed by using the sample of Example 1 was in the entire visible light wavelength region as compared with the electroplated copper strip formed by using the sample of Comparative Example 2 (i.e., even in any At one wavelength, the reflectance becomes high. For example, when light having a wavelength of 550 nm having the highest sensitivity in the human eye is irradiated, the reflectance of the plated copper strip formed by using the sample of Example 1 is 113%, whereas the sample of Comparative Example 2 is used. The resulting electroplated copper strip had a reflectance of 98%. Moreover, as described above, the reflectance is a relative reflectance when the amount of reflected light of the standard plate is 100%. Therefore, a reflectance of 113% means 13% more reflection than a standard plate.

In addition, Fig. 6(a) shows a plated copper strip formed by using the sample of Example 1. An example of an SEM image of the surface of the surface plating layer, and FIG. 6(b) shows an example of an SEM image of the surface of the surface plating layer of the plated copper strip formed by using the sample of Comparative Example 2. According to FIG. 6, it was confirmed that the surface of the surface plating layer of the electroplated copper strip formed by using the sample of Example 1 was flat and uniform as compared with the electroplated copper strip formed by using the sample of Comparative Example 2. Smoothness is high. On the other hand, it was confirmed that a mountain-like convex portion was formed along the rolling direction (the horizontal direction of the paper surface) on the surface of the surface plating layer of the plated copper strip formed by using the sample of Comparative Example 2, and the smoothness was low. .

Further, it was confirmed that when the amorphous region or the fine crystal grain region was formed on the growth surface of the underlying plating layer of the copper strip by comparing FIG. 5 with FIG. 6, the growth rate of the underlying plating layer was in the substrate plating. The layer growth surface is formed to be in-plane uniform. From this, it was confirmed that since the underlying plating layer was uniformly grown on the growth surface of the underlying plating layer, the surface of the underlying plating layer was formed to be flat. As a result, it was confirmed that a surface plating layer (Ag plating layer) having a flat surface can be formed on the underlying plating layer, and the reflectance of the surface plating layer can be improved.

<Comprehensive evaluation>

According to Table 1, it was confirmed that the electroplated copper strip formed by using the samples of Examples 1 to 9 had a higher reflectance than the standard plate. In other words, it was confirmed that the sample having a CI value of 0.1 or less at a measurement point of 50% or more has a reflectance of 108% to 116% irrespective of the material for forming the copper strip. From this, it was confirmed that, as in the samples of Examples 1 to 9, when an amorphous region or a fine crystal grain region was formed on the growth surface of the underlying plating layer, the growth rate of the underlying plating layer was formed on the growth surface of the underlying plating layer. The surface is uniform and the surface of the base plating layer is formed to be flat. As a result, it was confirmed that the surface of the surface plating layer (Ag plating layer) formed on the underlying plating layer was flat and the reflectance was high.

When each of the samples of Examples 1 to 9 is used for, for example, an LED (LED module), the evaluation of the optical performance of the LED is high. That is, for example, when the optical performance of the LED is evaluated by the total luminous flux measured by using the integrating sphere, a high total luminous flux can be obtained. Further, the higher the reflectance of the surface plating layer, the higher the evaluation of the optical performance of the LED, that is, the larger the total luminous flux.

On the other hand, it was confirmed that the electroplated copper strip formed using the samples of Comparative Examples 1 to 8 had a lower reflectance than the standard plate. That is, it was confirmed that the reflectance of the sample having a CI value of 0.1 or less at a measurement point of less than 50% was 95% to 99%. This confirms that copper When the growth surface of the base plating layer of the belt is a surface having a high crystallinity (not a region of an amorphous region or a fine crystal grain region), the base plating layer is caused by crystal grains (crystal structure) of the growth surface of the base plating layer. The crystal orientation is epitaxially grown, and a difference occurs in the amount of film formation of the underlying plating layer on the growth surface of the underlying plating layer. That is, it was confirmed that in the samples of Comparative Examples 1 to 8, the growth rate of the underlying plating layer on the underlying plating layer growth surface was not formed to be in-plane uniform. Therefore, it was confirmed that the underlying plating layer was not uniformly grown in-plane on the growth surface of the underlying plating layer, so that the surface of the underlying plating layer became uneven. As a result, it was confirmed that in the samples of Comparative Examples 1 to 8, a mountain-like convex portion was formed on the surface of the surface plating layer formed on the underlying plating layer, and the smoothness was lowered. From this, it was confirmed that in the samples of Comparative Examples 1 to 8, the reflectance of the surface plating layer was lowered.

Claims (7)

A copper strip characterized in that it is a copper strip having a growth layer of a base plating layer, and the growth surface of the base plating layer of the copper strip is formed into an in-plane uniform manner at a growth rate of the base plating layer. The underlying plating layer growth surface is formed with at least one of an amorphous region or a region formed of crystal grains having a grain size of 10 nm or less in terms of a diameter, wherein the underlying plating layer growth surface, In the EBSD method, the ratio of the measurement points having a reliability index of 0.1 or less obtained by measurement in a measurement region of 90 μm × 120 μm and a measurement interval of 0.2 μm is 50% or more. The copper tape according to claim 1, wherein the reliability index is measured by chemical etching after removing the growth surface of the underlying plating layer by 50 nm or more. A copper strip according to claim 1 or 2, wherein the copper strip is composed of any one of the following: comprising 2.1 wt% to 2.6 wt% of iron, 0.05 wt% ~0.2wt% zinc, 0.015wt%~0.15wt% phosphorus, and the balance is more than 97wt% copper and copper alloy formed by unavoidable impurities; contains 0.0010wt% or less of oxygen, and the remaining part is 99.95wt More than % of Cu and copper formed by unavoidable impurities; a copper alloy containing 0.015 wt% to 0.03 wt% of zirconium and a total weight of Cu and Zr of 99.96 wt% or more; or 1.5 wt% to 2.0 wt% Zinc, 2.2 wt% to 2.8 wt% of nickel, 0.015 wt% to 0.06 wt% of phosphorus, 0.3 wt% to 0.7 wt% of rhodium, and the balance being a copper alloy formed of Cu and unavoidable impurities. An electroplated copper strip, characterized in that the base plating layer growth surface of the copper strip according to any one of claims 1 to 3 is formed by growing a Cu plating layer or a Ni plating layer. At least one of them is used as a base plating layer. The electroplated copper strip according to claim 4, wherein an Ag plating layer is formed as a surface plating layer for reflecting light on the underlying plating layer by growth. A lead frame characterized in that it is formed by using an electroplated copper strip as described in claim 4 or 5. An LED module characterized in that an LED chip is mounted on a lead frame as described in claim 6 of the patent application.