JP2007081141A - Cu core ball and manufacturing method thereof - Google Patents

Abstract

To provide a Cu core ball on which an appropriate underlayer is formed and a method for producing the same.
A Cu core ball having a core ball 1 containing Cu as a main component and an Sn-based coating 3 on the surface thereof, and more than 6 mass% and not more than 15 mass% of P between the core ball and the Sn-based coating. A Cu core ball characterized by having an Ni—P amorphous alloy underlayer 2 containing Ni, and a method for manufacturing the same. Thereby, it can be set as the reliable Cu core ball | bowl with a small shear strength fall rate in the 150 degreeC 500-hour heat test.
[Selection] Figure 1

Description

  The present invention relates to a composite microball used for input / output terminal bumps of a semiconductor device, and more particularly to a Cu core solder ball and a manufacturing method thereof.

  In next-generation high-density packages, the number of pins and the pitch are reduced, and it is predicted that a pitch of 200 to 120 μm or less will be required. Then, as the mounting density increases, ensuring the reliability of the electrodes in chip size package (CSP) and bare chip mounting becomes a serious issue. At that time, a composite microball is used as an input / output terminal of the semiconductor device. In the composite microball, the inner core ball does not melt at the reflow temperature at the time of flip chip bonding, the distance between the chip and the printed circuit board (PCB) is maintained, and high bonding reliability is obtained. As a manufacturing method, a plating method is generally used. However, when the diameter of the core ball material is 200 μm or less, it tends to stick like a bunch of grapes at the time of plating, and the plating time over a long time due to uniform stirring and low current amount is long. This is a time consuming and expensive operation.

  In addition, since circuits are densely arranged on the chip, it is necessary to guarantee heat resistance against heat generated from the semiconductor device.

  Since it is used as a junction terminal of a semiconductor element, particularly as an internal electrode, a copper core solder ball is suitable for making a semiconductor package reliable for heat cycle, and a PbSn around a Cu core having a diameter of 0.04 to 0.1 mm. It has been proposed to coat a solder of CuSn, AgSn, SnZn, SnBi and Bi. Around the Cu, nickel electroplating is proposed as a barrier film for preventing Cu diffusion, and Sn electroless plating is proposed as a solder layer (Patent Documents 1 and 2). For the same purpose, a tungsten core ball has also been proposed as a solder plated ball (Patent Document 3). In order to prevent the formation of brittle compounds in the wettability with solder and subsequent thermal history, Cu core balls are plated with an electric Ni underlayer film or electroless Ni-B film, and then fixed on the graphite plate with small holes and the Cu core. A method has been proposed in which a small piece of solder wire of the amount is put and heated to obtain a solder-coated ball (Patent Document 4). An example of a Cu core solder ball using a Ni-P film as a barrier film is not so much taken up and is said to have poor solder wettability (Patent Document 4). There is also one in which copper, gold, or an alloy containing at least one of these is selected as the core, and a structure of an electric Ni plating base film, an Sn plating film, and an Ag plating film is created (Patent Document 5). Also, a solder ball in which Cu is contained in a solder component (Sn—Pb) has been proposed in order to obtain a high temperature durability equivalent to this without using a Cu core ball (Patent Document 6).

Japanese Patent Laid-Open No. 11-74311 JP-A-10-163404 JP-A-11-135570 JP 2000-195889 A JP 2001-319994 A JP 2001-274275 A

  When a Ni-based underlayer is formed, it is said that Ni has a Cu diffusion preventing effect. However, it is said that a Cu core solder ball using a Ni-P film as a barrier film does not have good solder wettability. Although a Ni-B film is also used, a boron compound used as a reducing agent is about 2 to 4 times more expensive than a Ni-P phosphorus compound.

  Accordingly, an object of the present invention is to provide a Cu core ball on which an appropriate underlayer is formed and a method for manufacturing the same in order to solve the above-described problems.

  The gist of the present invention is as follows.

  A first invention is a core ball having Cu as a main component and a Cu core ball having a Sn-based film on the surface thereof, and more than 6 mass% and not more than 15 mass% of P between the core ball and the Sn-based film. Cu core ball having a Ni—P amorphous alloy underlayer containing Ni.

  2nd invention is Cu core ball | bowl as described in 1st invention which has unevenness in the Sn system membrane | film | coat side surface of a base layer.

  3rd invention is Cu core ball | bowl as described in 1st or 2nd invention whose thickness of the said foundation | substrate layer is 0.001-15 micrometers.

  A fourth invention is the Cu according to the first invention, wherein the Sn-based film is an alloy of Sn and one or more selected from Ag, Cu, P, B, Ni, Bi, Zn, Pd, and Au. It is a core ball.

  According to a fifth aspect of the present invention, the Sn-based film comprises an Sn layer and one or more metal layers, alloy layers, or Sn alloy layers selected from Ag, Cu, P, B, Ni, Bi, Zn, Pd, and Au. It is Cu core ball | bowl as described in 1st invention which is a multilayer coating of 2 or more layers with 1 type or 2 types or more.

  6th invention is Cu core ball | bowl as described in 1st, 3rd or 4th invention whose thickness of Sn system membrane | film | coat is 1-50 micrometers.

  7th invention is Cu core ball | bowl as described in 1st invention whose component of the said core ball is 99 mass% or more of Cu.

  An eighth invention is the Cu core ball according to the first invention, wherein the component of the core ball is an alloy of Cu and one or more of Zn, Sn, P, Ni, Au, Mo, and W. is there.

  A ninth invention is the Cu core ball according to the first, sixth or seventh invention, wherein the core ball has a diameter of 1-1000 μm.

  According to a tenth aspect of the present invention, an Sn-based film is formed after forming a Ni-P amorphous alloy underlayer containing more than 6 mass% and 15 mass% or less P on the surface of a core ball containing Cu as a main component. A method of manufacturing a Cu core ball, wherein when forming the Sn-based film, the core ball having the base layer is placed in a barrel that is rotationally driven and has a cathode lead therein, and the vicinity of the peripheral surface of the barrel In an Sn-based plating bath equipped with an anode, the current value decreased to 1/3 or less of the current value at the start of electrolysis while maintaining the applied voltage during electroplating at a predetermined value of 0.1 to 2.0 V. Until then, stirring is performed by adding stirring means in addition to the rotation of the barrel to prevent aggregation of the core balls due to electroplating, and once the current value has decreased, aggregation does not occur by adjusting the applied voltage. As well as increasing the current value, only rotating the barrel A 拌 a method of manufacturing a Cu core ball, characterized in that the electroplating to a predetermined film thickness.

  The eleventh aspect of the present invention is the method for producing a Cu core ball according to the ninth aspect, wherein the formation method of the Ni—P amorphous alloy underlayer is an electroless plating method.

  A twelfth aspect of the invention is a method for producing a Cu core ball according to the ninth aspect of the invention, wherein the formation method of the Ni—P amorphous alloy underlayer is an electrolytic plating method.

  A thirteenth aspect of the invention is a semiconductor device using any one of the first to ninth Cu core balls as a bump.

  The Cu core ball of the present invention is a highly reliable Cu core ball with a small reduction in shear strength in a heat resistance test at 150 ° C. for 500 hours, and the method for producing the Cu core ball of the present invention includes fine particle barrel plating. In this case, it is possible to eliminate the sticking between fine particles, which is likely to occur, and to grow a plating film smoothly and efficiently in a relatively short time.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings, but the present invention is not limited to the following embodiments.

  The Cu core ball according to the present invention has a core ball containing Cu as a main component (hereinafter also referred to as a core), a predetermined base film surrounding the core, and an Sn-based film thereon. Here, the Sn-based coating may be a single-layer coating of Sn-based alloy, or may be a multilayer coating of Sn and other alloy components or Sn alloy. When a multilayer coating of Sn and other alloy components or Sn alloys is used, Sn and other alloy components or Sn alloys melt and diffuse in the reflow process for forming bumps of Cu core balls on the substrate electrodes. Accordingly, a uniform alloy layer is formed.

  FIG. 1 shows a schematic cross-sectional view of a Cu core ball according to an embodiment of the present invention. In the Cu core ball shown in FIG. 1, a core ball (core) 1 having Cu as a main component is at the center. A metal or metal alloy material 2 of the base film is formed around it, a solder material 3 is formed around it, and another solder material 4 is formed around it. The solder material 4 may be absent, for example, when the solder is only Sn alloy.

  The component of the core ball is not particularly limited as long as Cu is the main component (that is, the Cu content is 50% by mass or more), but the ball having a Cu content of 99% by mass or more, or Cu and Zn, Sn , P, Ni, Au, Mo, and W are easy to use in the case of an alloy ball with one or more of them. If the Cu content is too low, the thermal conductivity and electrical conductivity of the corner Cu will be lost.

  About the diameter of a core ball, 1-1000 micrometers is preferable. If it is smaller than this, handling is difficult and it is not a realistic size. If the diameter is larger than 1000 μm, it does not fall within the category of fine balls. A diameter of 40 to 200 μm is a size that is expected to be used in the future.

The underlayer which is a feature of the present invention is a Ni—P amorphous alloy underlayer containing P of more than 6 mass% and 15 mass% or less. When the P content is 6% by mass or less, the amorphous Ni does not become amorphous but the crystalline Ni prevents diffusion of Cu. Therefore, an interface reaction layer ((Ag, Ni) Sn ₃ alloy) grows in the Sn-based film outside the Ni—P film, and the shear strength decreases. When the P content exceeds 6% by mass, the barrier effect due to Ni is not sufficient, and Cu gradually passes through the Ni-P film and diffuses into the Sn-based film. Suppress. If the solder as the Sn-based film is, for example, Sn-3.5Ag, a Cu ₆ Sn ₅ -based intermetallic compound that grows slowly with Cu can be formed. With this intermetallic compound, the decrease in shear strength is extremely reduced in a heat resistance test at 150 ° C. for 500 hours or longer. It is considered that the rate of decrease in the shear strength under a high temperature environment is reduced by the action of such a base Ni—P film. Therefore, high temperature reliability is improved. An Ni-P film having a P content exceeding 15% by mass has not yet been produced industrially. If the crystalline Ni-based underlayer is thin, for example, if it is less than 0.001 μm, Cu may diffuse and ooze into the Sn-based film. However, it is difficult to control a too thin plating film, and it is difficult to stably form an ultrathin crystalline Ni-based underlayer.

  And it is preferable to have unevenness in the Sn system film side surface of a foundation layer. Since the Sn-based film is formed while filling the unevenness to some extent, the anchor effect works and the film adhesion is ensured.

  The thickness of the underlayer is 0.001 to 15 μm, and if it is thinner than this, there is no effect, and if it is thicker than 15 μm, the interface reaction layer suppressing effect is saturated and the processing cost increases. Preferably it is 0.5-2 micrometers.

  In our study results, the solder wettability of the Ni-P film was not inferior.

  In the ground layer of electric Ni plating or Ni-B plating, the plating surface is flat, and the anchor effect of the Sn-based plating layer cannot be expected. In Ni-B, the content of B is generally about 0.2%, and it is considered that the barrier property is thin even in terms of quantity.

  The component of the Sn-based film is an alloy of Sn and one or more selected from Ag, Cu, P, B, Ni, Bi, Zn, Pd, and Au. In addition, the Sn-based film is an Sn layer and at least one metal layer selected from Ag, Cu, P, B, Ni, Bi, Zn, Pd, and Au, an alloy layer, or an Sn alloy layer. And may be a multilayer coating of two or more layers. In the case of a multilayer coating, the multilayer coating melts and mixes in the reflow process at the time of bump formation, resulting in a uniform Sn-based solder alloy as a whole. The above elements are generally elements that form an alloy with Sn, and are used as solder materials. Moreover, although content rate changes with each elements, it is 0.1-30 mass%.

  And it is preferable that the thickness of a Sn-type membrane | film | coat is 1-50 micrometers. If it is thinner than this range, it will not be useful as solder. If it is thicker than 50 μm, it is too thick as compared with the size of the Cu ball, and there is a possibility that it melts and flows out at the time of bump formation and comes into contact with an adjacent electrode or bump.

  Next, the manufacturing method of the Cu core ball of the present invention will be described.

  A Cu ball having a desired diameter of 1 to 1000 μm is prepared. As the component of the Cu ball, 99% by mass or more of Cu or an alloy of Cu and one or more of Zn, Sn, P, Ni, and Au can be selected. A dummy ball is also prepared. The diameter and quantity of the dummy ball are not particularly specified, and the diameter and quantity suitable for the plating apparatus can be selected. As a selection criterion for the dummy ball, it is sufficient if it can be well stirred, and a diameter of about 0.8 to 5 mm is reasonable. A single diameter or several different diameters may be mixed. The material is not particularly limited, but is suitable because an iron ball is inexpensive and easy to handle. Depending on the case, it may be made of ceramics, copper, glass or the like. The iron ball is fully degreased because it is oiled with rust prevention when purchased. You may wash | clean with organic solvents, such as acetone. A commercially available degreasing solution may be used. A general detergent can also be used. Next, activation treatment is performed with dilute sulfuric acid for 30 seconds to 5 minutes to remove the surface oxide film. Cu core balls are also subjected to the same activation treatment as the same alkaline degreasing. The dummy balls are placed in a barrel plating bath together with fine particles to be plated so that the Cu cores do not form dumplings.

  After washing, amorphous Ni—P plating is performed. In the case of electroless plating, a dummy ball and a Cu core ball are simultaneously put into the plating solution in the Ni—P plating solution, and are vigorously stirred. A plating film having a thickness of 1 to 2 μm can be formed in 1 to 5 minutes. In the case of Ni-P electroless plating, all commercially available electroless plating solutions can be used. What is necessary is just to select suitably the electroless-plating bath composition and plating conditions in which P content rate in a Ni-P base layer will be more than 6 mass% and 15 mass% or less. In the case of Ni-P electroplating, a mixed solution of nickel salt, phosphorous acid and phosphoric acid, as described in the “Technical Guidebook for Plating Technology”, page 359, published in 1959, edited by the Technical Committee of the Tokyo Sheet Metal Cooperative Association To form the plating.

  The thickness of the Ni—P underlayer is 0.001 to 15 μm. Preferably, the thickness is 0.5 to 2.0 μm.

  Next, an Sn-based film is applied to the Cu core ball on which the Ni—P underlayer is formed. The Sn-based film may be a solder alloy film of Sn and Ag, Cu, P, B, Ni, Bi, Zn, Pd, or Au, or Sn layer and Ag, Cu. , P, B, Ni, Bi, Zn, Pd, Au may be used as a multilayer coating of two or more layers including one or more of metal layers, alloy layers, or Sn alloy layers.

  The method for forming the Sn-based film is not particularly limited, but the electroplating method is simple and efficient. The basic electroplating of Sn will be described. The basic composition of the plating solution is a sulfuric acid-based tin plating solution using stannous sulfate. In this case, a commercially available brightener may be added. Thus, tin plating is performed on the core ball plated with the Ni-P alloy. The plating apparatus is not particularly limited as long as it is a barrel plating apparatus, but an oblique barrel plating apparatus is preferable from the viewpoint of workability. The temperature is room temperature. The time change of the current value at that time is shown in FIGS. It is a current value in a state where sufficient stirring is performed. What is characteristic here is that, in the case of a Ni—P underlayer, sticking is very intense at the start of tin plating, and current on / off and strong stirring conditions are required. However, it was found that the current value dropped to one-third or less of the initial setting after 10 minutes to 120 minutes, and the sticking disappeared. Thereafter, the plating rate can be easily increased by increasing the current value and increasing the plating rate. In any case, the optimum voltage range is a predetermined value of 0.1 to 2V. Some devices may require higher voltages due to internal resistance. This is a potential difference as a guide. For stirring, in addition to the use of dummy balls and rotation of the barrel, stirring is performed by adding stirring means to prevent aggregation of the core balls due to electroplating. It has been explained that the electroplating is performed up to a predetermined film thickness as the stirring only by rotating the barrel and the current value is set so as not to agglomerate by adjustment. However, as stirring other than the rotation of the barrel, use of an ultrasonic transmitter, stirring There is agitation with a propeller and agitation to break up agglomeration of particles by sticking with a round bar. Any method should be chosen.

  As the solder alloy composition, Sn—Ag alloy plating may be performed on the Sn plating layer in order to make the Sn-based film into, for example, a Sn—Ag alloy. There are commercially available alkanol sulfonic acid plating solutions. Here, other Ag plating solutions may be used. Those that are used at room temperature are aimed at low cost. A predetermined amount of this is plated and combined with the amount of Sn layer deposited, for example, a composition of Sn-3.5% Ag. Of course, Sn-Ag alloy plating may be performed from the beginning without performing Sn single plating. It goes without saying that a solder alloy composition other than Sn-Ag may be used.

  Moreover, even if the solder composition is difficult to alloy, if a multilayer coating is formed by plating each composition element, the multilayer coating is melted in the reflow process at the time of bump formation. There are advantages you can do.

  The Cu core ball produced in this way has solder on the surface when used for bumps, so that it has excellent bondability with semiconductor elements and electrodes formed on a substrate, and the core Cu ball serves as a spacer. Therefore, the distance between the substrate and the semiconductor element can be reliably maintained at a constant value.

  A Cu ball having a diameter of 150 μm was prepared. The dummy ball iron balls (various sizes from 0.5mm to 5.0mm, etc., but choose a size suitable for the device) are fully degreased with alkali since the rust stopper is oiled when purchased. . A commercially available degreasing solution was used. Next, in order to remove the surface oxide film, activation treatment was performed with 10% dilute sulfuric acid for 3 to 5 minutes. Cu balls were also subjected to the same activation treatment. After washing, it was plated with Ni or Ni alloy.

  In the case of Ni electroplating, barrel plating was performed to a thickness of 0.5 μm on a Cu ball 30 g using a watt bath at room temperature and a voltage of 4V.

  In the case of electroless plating, a dummy ball and a Cu core were simultaneously added to the plating solution in the Ni—P plating solution or the Ni—B plating solution, and the mixture was vigorously stirred. The throwing ratio between the Cu ball and the dummy ball is not particularly limited, and it is sufficient that the particles rotate evenly during stirring. A plating film having a thickness of 1 to 2 μm was formed in 1 to 5 minutes. Commercially available products were used for all electroless plating solutions.

  Example 1 using Ni-6.5% P, Example 2 using Ni-11% P, Comparative Example 1 using Ni-B plating and Comparative Example 1 Using electroless Ni-B This is referred to as Comparative Example 2. In the case of Ni plating and Ni-B system, the current value change at the start of Sn electroplating was similar. In addition, Comparative Example 3 was not subjected to the ground treatment. According to the surface observation in the SEM photograph of the Cu core ball subjected to the base plating, the Ni-P plating had irregularities on the ball surface. The other electric Ni plating, electroless Ni-B plating, and the balls with the Cu core as they were had a smooth surface. When the obtained underlayers were examined by X-ray diffraction, it was found from the half width of the spectrum that the Ni—P system was an amorphous film and the Ni and Ni—B systems were crystalline.

  As the Sn-based coating layer, a two-layer plating of a Sn layer and a Sn—Ag alloy plating layer was used. First, the Sn plating layer was plated with a thickness of 25 μm by electric Sn barrel plating. This is a sulfuric acid-based tin plating solution (Sn concentration 40 g / L) using stannous sulfate. In this case, a commercially available brightener (Top Serina MU, Top Serena R: Okuno Pharmaceutical) 10 mL / L was used. Tin plating was performed on the balls and Cu balls having the underlayer of Ni, Ni-P, or Ni-B alloy. The temperature was room temperature, and the total plating time of tin was 4 to 6 hours. The time change of the current value at that time is shown in FIG. The Ni underlayer is not shown, but is omitted because it is similar to the Ni-B underlayer.

  What is characteristic here is that in the case of Ni-P plating, sticking was extremely intense during tin plating. However, it was found that the current value decreased and sticking disappeared after 10 to 120 minutes. Thereafter, it was found that the plating rate could be easily increased by increasing the current value to increase the plating rate. When Sn plating was applied to Cu balls having Ni or Ni-B base layers or directly to Cu balls, there was no change in current value and there was little sticking. In either case, the electrolysis start voltage was 1V.

  In order to make the Sn-based coating layer an Sn—Ag alloy, Sn—Ag alloy plating was performed as the second layer. It is a commercial product (UTB TS 140BASE: Ishihara Yakuhin) with an alkanol sulfonic acid plating solution. Plating was performed for 60 minutes, and the total was adjusted to Sn-3.5% Ag together with the first Sn layer.

  In the case of Ni-P base plating, a Ni-P alloy base layer is formed on the surface of a core ball containing Cu as a main component, and then, when an Sn-based alloy film is formed, it is rotationally driven and has a cathode inside. A core ball having the base layer is placed in a barrel provided with a lead, and the current value at the time of electroplating in the Sn-based plating bath having an anode near the peripheral surface of the barrel is the current value at the start of electrolysis. Stir vigorously until it falls to 1/3 or less to prevent the core balls from sticking to each other, and once the current value has been lowered, it is raised to a current value that does not cause aggregation by adjusting the applied voltage to obtain a predetermined film thickness The method of electroplating was taken.

  As for the stirring, in addition to the rotation of the barrel, stirring is performed by adding stirring means to prevent the core balls from aggregating due to electroplating. Once the current value has decreased, the agglomeration can be achieved by adjusting the applied voltage. It was explained that the electroplating was performed up to the specified film thickness as the stirring only for the rotation of the barrel while raising the current value so that it did not come out, but for the stirring other than the rotation of the barrel, the use of an ultrasonic transmitter, a stirring propeller was put in And agitation that breaks up the agglomeration of particles by sticking with a round bar. Any method should be chosen. This time, the agitation was performed by crushing the particles with a round bar.

  The results are described in Table 1. Table 1 shows the respective elemental analysis values, shear strength, shear strength after a heat test at 150 ° C. for 500 hours, and the reduction rate of the shear strength. The shear strength is measured by applying a water-soluble flux on Ni / Au UBM (Under Bump Metal) with an opening diameter of 120 μm, mounting the prepared Cu core solder balls, reflowing at 250 ° C., and ball height after cleaning. The shear strength was measured at one third from the bottom.

  It can be seen from the elemental analysis values that the Sn-based coating layer is within Sn-3.5 ± 1.0% Ag. Depending on the type of Ni film, the difference between the shear strength when it is mounted on the UBM of the printed circuit board at the time of ball preparation and the shear strength measured after a heat resistance test at 150 ° C. for 500 hours after mounting is as follows. It can be seen that the rate of decrease is the lowest. From this data, it can be interpreted that the effect of Ni as a Cu diffusion barrier does not work when the P concentration is high. It was found that Cu oozing from the Cu core can be adjusted by the amount of P in the Ni-P film. This slight Cu exudation is considered to be the reason why the Ni-11% P film has high heat resistance. For Ni-6.5% P, the effect of Ni blocking the seepage of Cu was strengthened, so the rate of decrease in the shear strength was slightly increased. In Comparative Examples 1 and 2, the Ni plating surface was smooth and solder plating was easy, but the shear strength after the heat resistance test was not good. In Comparative Example 3, there is no Ni at all, the shear strength after the heat resistance test is not good, and the Cu core eventually diffuses as a result of the change over time, and further when it is used for a long time. Reliability becomes a problem. In the Ni-P system, when the crystallinity becomes strong, there is a tendency to block the diffusion of Cu, and it can be judged that the block of the diffusion of Cu is weaker as it is amorphous.

  Both the electric Ni—P plating film and the electric Ni—B plating film as the underlayer had substantially the same results as the respective electroless plating films. In addition, in the case of other Sn-based alloy films, almost the same results as the Sn-Ag-based films were obtained.

An example of the cross-sectional schematic diagram of Cu core ball of this invention. The difference in the base film and the fluctuation of the current value in tin plating.

Explanation of symbols

1 Core (core ball)
2 Underlayer 3 Sn layer 4 Solder alloy component layer other than Sn

Claims (13)

  Ni-P, which is a core ball mainly composed of Cu and a Cu core ball having a Sn-based film on the surface thereof, and containing more than 6 mass% and not more than 15 mass% of P between the core ball and the Sn-based film. A Cu core ball comprising an amorphous alloy underlayer.   The Cu core ball according to claim 1, wherein the underlayer has an uneven surface on the Sn-based film side surface.   The Cu core ball according to claim 1 or 2, wherein the thickness of the underlayer is 0.001 to 15 µm.   The Cu core ball according to claim 1, wherein the Sn-based film is an alloy of Sn and one or more selected from Ag, Cu, P, B, Ni, Bi, Zn, Pd, and Au.   The Sn-based film is composed of an Sn layer and at least one metal layer selected from Ag, Cu, P, B, Ni, Bi, Zn, Pd, and Au, an alloy layer, or an Sn alloy layer. The Cu core ball according to claim 1, wherein the Cu core ball is a multilayer coating of two or more layers.   The Cu core ball according to claim 1, 3 or 4, wherein the Sn-based film has a thickness of 1 to 50 μm.   The Cu core ball according to claim 1, wherein a component of the core ball is 99% by mass or more of Cu.   The Cu core ball according to claim 1, wherein the core ball component is an alloy of Cu and one or more of Zn, Sn, P, Ni, Au, Mo, and W.   The Cu core ball according to claim 1, 6 or 7, wherein the core ball has a diameter of 1 to 1000 μm.   A method for producing a Cu core ball, in which a Ni-P amorphous alloy underlayer containing P of more than 6% by mass and 15% by mass or less is formed on the surface of a core ball containing Cu as a main component, and then an Sn-based film is formed. When forming the Sn-based film, a core ball having the base layer is placed in a barrel that is rotationally driven and includes a cathode lead, and an Sn is provided in the vicinity of the peripheral surface of the barrel. Rotating the barrel until the current value drops to 1/3 or less of the current value at the start of electrolysis while maintaining the applied voltage at the time of electroplating at a predetermined value of 0.1 to 2.0 V in the plating bath In addition, stirring is performed by adding a stirring means to prevent aggregation between the core balls by electroplating, and once the current value has decreased, it is increased to a current value at which aggregation does not occur by adjusting the applied voltage, Predetermined as stirring only for barrel rotation Method for manufacturing a Cu core ball, characterized in that the electroplated to film thickness.   The method for producing a Cu core ball according to claim 9, wherein the formation method of the Ni—P amorphous alloy underlayer is an electroless plating method.   The method for producing a Cu core ball according to claim 9, wherein the formation method of the Ni—P amorphous alloy underlayer is an electrolytic plating method.   A semiconductor device comprising the Cu core ball according to claim 1 as a bump.

Images