Core material, use of the core material as a soldering contact surface for an electronic component, and method for producing a contact surface electrode

Description

Technical Field

[0001] The present embodiment relates to a core material, the use of the core material for an electronic component as a solder bump, and a method for forming a bump electrode.Background Art

[0002] In recent years, with development of a small information device, size of an electronic component mounted on the information device is rapidly being reduced. A ball grid array (BGA) with an electrode disposed on a rear surface of the BGA is applied as the electronic component in order to correspond to narrowing a connection terminal and reducing mounting area according to a demand for miniaturization.

[0003] An example of the electronic component to which the BGA is applied includes a semiconductor package. The semiconductor package is configured by sealing a semiconductor chip having an electrode with a resin. A solder bump is formed on the electrode of the semiconductor chip. The solder bump is formed by bonding a solder ball to the electrode of the semiconductor chip. The semiconductor package to which the BGA is applied is mounted on a printed circuit board by bonding the solder bump melted by heating to a conductive land of the printed circuit board. In recent years, in order to meet the demand for higher-density mounting, a three-dimensional high-density mounting in which semiconductor packages are stacked in a height direction has also been developed.

[0004] When the semiconductor package obtained with the three-dimensional high-density mounting is the BGA and the solder ball is placed on the electrode of the semiconductor chip and reflowed, the solder ball may be crushed due to weight of the semiconductor package itself. When such a situation occurs, there is a problem that the solder extrudes from electrodes to bring the electrodes into contact with each other, and a short-circuit between the electrodes is caused.

[0005] In order to prevent such a short-circuit from occurring, a solder bump that is not crushed due to the weight of the semiconductor package itself and is not deformed when the solder is melted is proposed as a solder ball. Specifically, it is proposed to use a ball molded of metal or a resin as a core, and to use a core material obtained by coating the core with a solder as a solder bump.

[0006] Japanese Patent No. 5367924 discloses a solder bump in which a Cu ball is used as a core and a Sn-based solder alloy formed of Sn and Bi is plated on the Cu ball. A plating treatment is performed at a concentration gradient in which a content of Bi contained in a solder plating layer in Japanese Patent No. 5367924 is high on an inner side (inner circumferential side) and is lower as being directed toward an outer side (outer circumferential side).

[0007] As in Japanese Patent No. 5367924, when a solder is heated and melted in a state in which a concentration of Bi in the solder plating layer is high on the inner circumferential side and is low on the outer circumferential side, a density of Bi on the inner circumferential side is high. Therefore, the solder begins to be melted from a Bi region on the inner circumferential side. Even when the Bi region on the inner circumferential side is melted, the Bi region on the outer circumferential side has yet to begin to be melted. Therefore, a volume expansion in the Bi region on the inner circumferential side occurs early. Due to a slow volume expansion on the inner and outer circumferential sides, a situation occurs in which a pressure difference is generated between the inner circumferential side and the outer circumferential side (outside air) of Bi, and the pressure difference due to the volume expansion on the inner circumferential side causes the Cu ball, which is a core, to burst open when the outer circumferential side of Bi begins to be melted. The occurrence of the situation has to be avoided. As described above, a defect has been generated in a Cu core ball having a solder plating layer formed of the Sn-based solder alloy formed of Sn and Bi when Bi in the solder plating layer has a concentration gradient.

[0008] Japanese Patent No. 6217836 is proposed in order to solve the above-described problems caused in Japanese Patent No. 5367924. In Japanese Patent No. 6217836, in a core material having a solder plating layer formed by plating a (Sn-Bi)-based solder alloy formed of Sn and Bi on a core surface, the core material is provided in which Bi contained in the solder plating layer is distributed in a concentration ratio within a predetermined range of 91.4% to 106.7% in the solder plating layer.

[0009] KR 10-1563884 B1 relates to a core solder ball, to a manufacturing method thereof and to an electronic part including the same, the core solder ball comprising: a multilayered solder layer; and an outermost layer for preventing the oxidation of the core solder ball.

[0010] KR 2016-0103922 A relates to a solder ball for fluxless bonding, a method of manufacturing the same, and a method of forming a solder bump and, more specifically, provides a solder ball for fluxless bonding comprising: a solder core; a first metal layer on a surface of the solder core; and a second metal layer on the first metal layer. The first metal layer comprises at least one of nickel (Ni), silver (Ag), zinc (Zn), tin (Sn), chromium (Cr), antimony (Sb), platinum (Pt), palladium (Pd), aluminum (Al), or an alloy thereof. The second metal layer comprises gold (Au).

[0011] JP 3924552 B2 A is directed to a conductive ball consisting of a core formed of an almost spherical non-metallic material, a Cu layer formed to cover the surface of the core with no space, a solder inner layer formed to cover the surface of the Cu layer with no space and formed of an Sn-Ag alloy and a solder outer layer which is formed to cover the surface of the solder inner layer with no space and consists of an Sn-Ag alloy having a liquid phase line temperature lower than the liquid phase line temperature of the Sn-Ag alloy constituting the solder inner layer and having a solid phase line temperature below the solid phase line temperature of the Sn- Ag alloy constituting the solder inner layer.

[0012] KR 10-1049520 B1 describes a core solder ball, a core solder ball manufacturing method and an electronic component using the same. In the core solder ball, the first metal layer is formed on the surface of a core, the second metal layer is formed on the surface of the first metal layer, the third metal layer is formed on the surface of the second metal layer, and a solder layer is formed on the surface of the third metal layer. The third metal layer is made of metal components different from that of the second metal layer.

[0013] JP 2007-075856 A relates to a Cu core ball comprising a kernel ball containing Cu as a main component, and an Sn group coating film formed on the surface of the kernel ball, wherein a crystalline Ni group underlayer is arranged between the kernel ball and the Sn group coating film, and the Sn group coating film contains Cu as its component.SUMMARY OF INVENTIONPROBLEM TO BE SOLVED BY INVENTION

[0014] When a relatively large amount of Ag and Cu are contained in the surface of the solder plating layer, Ag and Cu are locally discolored to black, and the appearance is mottled, which may cause deteriorated appearance quality. As a result of the color becoming black from the viewpoint of yellowness, the yellowness increases, which may cause defect determination in appearance inspection.

[0015] As described above, when a relatively large amount of Ag and Cu are contained in the surface of the solder plating layer, the solder plating layer easily reacts with a sulfur component of the plating liquid and oxygen in the air. As a result, oxidation easily proceeds, which tends to easily cause an increased oxide film thickness. When the oxide film thickness increases as described above, dissolution behavior at the time of substrate reflow deteriorates, which may cause a state (ball missing) where the solder ball is detached from the electrode pad or positional deviation.

[0016] The present invention provides a core material and so on that is unlikely to be determined to be defective in a visual inspection and can prevent the oxide film thickness from increasing and suppress a bonding defect.Solution to Problem

[0017] A core material according to the present invention comprises: a core; a Sn-based solder layer provided outside the core and being a solder alloy consisting of Sn and at least any one element of Ag, Cu, Sb, Ni, Co, Ge, Ga, Fe, Al, In, Cd, Zn, Pb, Au, P, S, Si, Ti, Mg, Pd, and Pt; and a Sn layer provided outside the solder layer, wherein the solder layer has a thickness of 1 µm or more on one side, the Sn layer has a thickness of 0.1 µm or more on one side, and a thickness of the Sn layer is 0.215% or more and 36% or less of the thickness of the solder layer.

[0018] In the core material according to the present invention, the solder layer may be a (Sn-Ag-Cu)-based solder.

[0019] The core material, according to the present invention, may further comprise a base plating layer made of any one of Ni, Co, Ni-Co, Ni-P and Ni-B between the core and the solder layer.

[0020] In the core material according to the present invention, Cu ball or Cu column may be used as the core.

[0021] The above core materials can be used for an electronic component as a solder bump.

[0022] A method for forming bump electrode according to the present invention comprises steps of: mounting any one of the above core materials on an electrode; forming a bump electrode by heating the mounted core material.

[0023] According to the present invention, a core material and so on that is unlikely to be determined to be defective in a visual inspection and can prevent the oxide film thickness from increasing and suppress a bonding defect can be provided.BRIEF DESCRIPTION OF DRAWINGS

[0024] Fig. 1 is a cross-sectional view illustrating an example of a Cu core ball according to an embodiment of the present invention. Fig. 2 is a cross-sectional view illustrating another example of a Cu core ball according to an embodiment of the present invention. EMBODIMENT FOR CARRYING OUT INVENTION

[0025] Hereinafter, embodiments of the present embodiment will be described in detail. In the embodiment, a core material and an electronic component including a semiconductor package using the core material are provided.

[0026] The core material of the present embodiment includes a core; a Sn-based solder layer provided outside the core and being a solder alloy consisting of Sn and at least any one element of Ag, Cu, Sb, Ni, Co, Ge, Ga, Fe, Al, In, Cd, Zn, Pb, Au, P, S, Si, Ti, Mg, Pd, and Pt; and a Sn layer provided outside the solder layer. The thickness of the solder layer is 1 µm or more on one side. The thickness of the Sn layer is considered to be 0.1 to 12 µm on one side, but the upper limit value thereof may exceed 12 µm as long as the thickness of the Sn layer is 0.215% or more and 36% or less of that of the solder layer.

[0027] The Sn layer may be formed to have a thickness of preferably 0.26% or more and 33.3% or less of that of the solder layer. In the present embodiment, as an example, a solder plating layer is described as the solder layer to be used, and a Sn plating layer is described as the Sn layer to be used, but the present invention is not limited thereto. The solder layer may be formed by a method other than plating, and similarly, the Sn layer may be formed by a method other than plating. The Sn layer may contain a component other than Sn as an impurity such as Ag, Cu, Bi, Sb, Ni, Co, Ge, Ga, Fe, Al, In, Cd, Zn, Pb, Au, P, S, or Si.

[0028] The solder alloy is a Sn-based solder alloy. The Sn-based solder alloy can include other additive elements in addition to (Sn-Ag)-based and (Sn-Cu)-based solder alloys. The element that can be added to the (Sn-Ag)-based and (Sn-Cu)-based solder alloys is one or two or more elements of Ag, Cu, Ni, Bi, Ge, Ga, In, Zn, Fe, Pb, Sb, Au, Pd, and Co and the like. For example, a (Sn-Ag-Cu-Ni)-based solder alloy and a (Sn-Ag-Sb)-based solder alloy and the like are considered. In Examples to be described later, SAC 305 (Ag 3.0 Cu 0.5 Sn balance), SnAg (Ag 3.5 Sn balance), SnCu (Cu 0.7 Sn balance), SnSb (Sb 10 Sn balance), SnIn (In 45 Sn balance), and SnPb (Pb 37 Sn balance) are used, but the present invention is not limited thereto. For example, for SAC, the content of Ag and the content of Cu may be changed, and Ag 0.1 Cu 0.1 Sn balance to Ag 10 Cu 10 Sn balance may be used. For SnAg, Ag 0.1 Sn balance to Ag 10 Sn balance may be used by changing the content of Ag. For SnCu, Cu 0.1 Sn balance to CulSn balance may be used by changing the content of Cu. For SnSb, Sb 0.1 Sn balance to Sb 15 Sn balance may be used by changing the content of Sb. In the present application, the numerical value of the addition amount of each element is represented by % by mass. For example, "Ag 3.0 Cu 0.5 Sn balance" indicates that 3.0% by mass of Ag and 0.5% by mass of Cu are contained, the balance being Sn.

[0029] The Sn plating layer is formed after the solder plating layer is formed. As an example, a solder plating layer containing Sn and at least any one element of Ag, Cu, Sb, Ni, Co, Ge, Ga, Fe, Al, In, Cd, Zn, Pb, Au, P, S, Si, Ti, Mg, Pd, and Pt on the core is formed. The core material on which the solder plating layer is formed may be pulled up from a molten liquid containing Sn and at least any one element of Ag, Cu, Sb, Ni, Co, Ge, Ga, Fe, Al, In, Cd, Zn, Pb, Au, P, S, Si, Ti, Mg, Pd, and Pt, and then immersed in a molten liquid of Sn to form the Sn plating layer. Both the solder plating layer and the Sn plating layer may be formed using barrel electroplating. Electroless plating may be used as a plating method.

[0030] When the Sn plating layer is not provided, and the solder plating layer contains 0.1% by mass or more of a component other than Sn, the problem of discoloration occurs. When the Sn plating layer is not provided, and the solder plating layer is 100% by mass of Sn, the problem of discoloration does not occur, but the problem of discoloration is confirmed to occur when the solder plating layer is made of the following components. In the case of electroplating, if Ag or the like remains in the plating liquid just before the end of solder plating, substitution deposition-based discoloration of the surface is considered to occur. Ag 0.05 Cu 0.05 Sn balance, discolored Ag 0.1 Sn balance, discolored Cu 0.1 Sn balance, discolored Sb 0.1 Sn balance, discolored In 0.1 Sn balance, discolored Pb 0.1 Sn balance, discolored

[0031] Metal or a resin is conceivable as the core, and a shape of the core is conceivable to be a sphere or other shape (columnar column, sheet shape, and the like). In the embodiment, a case of a Cu core ball which is a sphere and uses a ball which is, particularly, formed of Cu as the core (also referred to as "Cu ball") will be described. The Cu core ball in the embodiment only needs to contain Cu in the core, and other configurations are not particularly limited.

[0032] A particle diameter (sphere diameter) of the core differs depending on size of the BGA, but in the following example, the core has a spherical shape of about 300 µmφ and a thickness of the solder plating layer on one side in a diameter direction is 1 µm to 100 µm. A thickness of the Sn plating layer on one side in the diameter direction may be determined based on the thickness of the solder plating layer, and as described above the thickness of the Sn plating layer on one side in the diameter direction is 0.215% or more and 36% or less of the thickness of the solder plating layer, preferably 0.26% or more and 33.3% or less of the thickness of the solder plating layer. The particle diameter of the Cu core ball is appropriately selected according to a density and size of the electronic components to be used. Therefore, the core having the particle diameter in a range of 1 µm to 1000 µm can be used, and the plating thickness can be appropriately selected according to the particle diameter of the core to be used. A typical particle diameter when being used as a ball is 200 µm to 300 um. When the particle diameter is further minimized in the future, a mainstream particle diameter may be 100 µm to 160 µm, and the present application can be used without any problem even with this particle diameter. As a plating apparatus that performs the plating treatment, an electroplating apparatus may be used.

[0033] Subsequently, an example of the Cu core ball using the Cu ball as a core will be described. Figs. 1 and 2 are cross-sectional views illustrating an example of a Cu core ball 10 according to the embodiment of the present invention.

[0034] As illustrated in Fig. 2, in the Cu core ball 10, a core 12 containing Cu and a solder plating layer 16 formed of the solder alloy are formed via a Ni base plating layer 14 in the example, and a Sn plating layer 20 is formed on the solder plating layer 16. The Ni base plating layer 14 functions as a base plating (functions as a barrier layer) for preventing a composition change of the solder plating layer 16 due to a metal diffusion between the core 12 and the solder plating layer 16, and a thickness of the Ni base plating layer 14 on one side is about 1 µm to 4 um. The Ni base plating layer 14 is not an indispensable requirement, and the solder plating layer 16 can be formed directly on the surface of the core 12 as illustrated in Fig. 1 When forming the base plating layer 14, the base plating layer 14 may be configured of a layer formed of one element or more selected from the group consisting of Ni, Co, P and B. More specifically, the base plating layer made of any one of Ni, Co, Ni-Co, Ni-P and Ni-B may be provided.

[0035] Cu used in the core 12 may be pure copper or an alloy of copper.

[0036] When the core 12 having an alloy composition containing Cu as a main component is used, purity of Cu is not particularly limited, but from a viewpoint of suppressing deterioration of electric conductivity and thermal conductivity of the Cu core ball due to a decrease in purity and suppressing α-rays as necessary, the purity of Cu is preferably 99.9% by mass or more.

[0037] The core may be formed of a metal simple substance of Ni, Ag, Bi, Pb, Al, Sn, Fe, Zn, In, Ge, Sb, Co, Mn, Au, Si, Pt, Cr, La, Mo, Nb, Pd, Ti, Zr, Mg, an alloy made from two or more of these components, a metal oxide, or a metal mixture oxide in addition to Cu, and may be formed of a resin material. As the resin material, a resin material formed of an amino resin, an acrylic resin, an ethylenevinyl acetate resin, a styrene-butadiene block copolymer, a polyester resin, a melamine resin, a phenol resin, an alkyd resin, a polyimide resin, a urethane resin, an epoxy resin, a crosslinked resin, or the like is exemplified. Of these, it is preferable to use conductive plastic such as polyacetylene, polypyrrole, polythiophene, and polyaniline. When the core is formed of the resin material, the Cu core ball can be formed by a resin core, a Cu plating layer coating an outer side of the resin core, a base plating layer such as Ni coating a surface of the Cu plating layer, and a solder plating layer coating a surface of the base plating layer. A laminated structure of the Cu core ball is not limited to the above example.

[0038] When the core 12 is spherical, from a viewpoint of controlling a stand-off height, sphericity of the core 12 is preferably 0.95 or more, and more preferably 0.990 or more. When the sphericity of the core 12 is less than 0.95, the core 12 has an indefinite shape. Therefore, a bump having a height which is not uniform is formed at the time of forming the bump, and the possibility of causing defective bonding increases. Further, when the Cu core ball 10 is mounted on the electrode and reflowed, and the sphericity is low, the Cu core ball 10 is misaligned and a self-alignment property deteriorates.

[0039] Here, the sphericity represents a deviation from the sphere. The sphericity is obtained by various methods such as a least squares center method (LSC method), a minimum zone center method (MZC method), a maximum inscribed center method (MIC method), and a minimum circumscribed center method (MCC method). Specifically, the sphericity is an arithmetic average value calculated when the diameter of each of 500 cores is divided by a long diameter, and the closer the value is to the upper limit of 1.00, the closer to the sphere. The length of the long diameter is a length measured by ULTRA QV350-PRO measurement device (ultra quick vision manufactured by MITUTOYO CORPORATION) .

[0040] It is preferable that the diameter of the entire Cu core ball 10 including the solder plating layer 16 is 1 µm to 1000 µm. Within this range, the spherical Cu core ball 10 can be stably manufactured, and by selecting the particle diameter, it is possible to suppress a connection short circuit when there is a narrow pitch between the electrode terminals.

[0041] The solder plating layer 16 is made of an Sn-based solder alloy, and consists of Sn and at least any one element of Ag, Cu, Sb, Ni, Co, Ge, Ga, Fe, Al, In, Cd, Zn, Pb, Au, P, S, Si, Ti, Mg, Pd, and Pt in the present embodiment.

[0042] The thickness of the solder plating layer 16 varies depending on the particle diameter of the core 12, but the thickness of the solder plating layer 16 on one side in the diameter direction is preferably 100 µm or less. For example, when the core 12 has a particle diameter of 300 µmφ, the solder plating layer 16 is formed so as to have a thickness of 1 µm to 100 µm on one side. This is for securing a sufficient amount of solder bonding.

[0043] As the plating liquid, a known plating liquid can be appropriately used according to the solder composition to be formed.[Example]

[0044] Hereinafter, the embodiment will be described in detail with reference to Examples and Comparative Examples. The embodiment is not limited to these Examples.

[0045] As an evaluation of the core ball having a composition shown in each Table which will be described later, an evaluation of yellowness and an evaluation of a defect at the time of bonding were performed based on the following criteria.<Yellowness>

[0046] The yellowness of the core ball was measured by using a CM-2600d spectrophotometer manufactured by KONICA MINOLTA. The yellowness of 8.5 or less in the L*a*b* table color system was set to "Good" and indicated as "o" in each Table. The yellowness of more than 8.5 in the L*a*b* table color system was determined to be "defective" and indicated as "x" in each Table.<Defect at the time of bonding>

[0047] Ten core balls (samples) having a composition in each Example and each Comparative Example, which are produced in the same production batch as each sample of which yellowness was measured, were prepared, and each core ball was bonded to a substrate by normal reflow processing. Regarding defects at the time of bonding, a case where a bonding defect was not measured in all the ten samples was indicated as "Good" and indicated as "o" in each Table. On the other hand, a case where misalignment or a ball missing is caused at the time of bonding in even one sample or a case where a core bursts open as the time of bonding in even one sample was determined to be "defective", and indicated as "x" in Table.

[0048] Core balls 10 in Examples and Comparative Examples were prepared under the following conditions. Diameter of core 12: 300 um Film thickness of Ni base plating layer 14: 2 µm on one side Film thickness of solder plating layer 16: 1 µm on one side, 18 µm or 38 µm on one side Diameter of core ball 10 excluding Sn plating layer 20: 306 µm, 340 µm or 380 µm

[0049] As a method for plating the Ni base plating layer 14, an electroplating method (barrel electroplating) was used for a sample having a core made of Cu. An electroless plating method was used for a sample having a core made of a resin. Aluminum as a core was subjected to a double zincate treatment for a sample having a core made of aluminum. Ni plating was thinly applied to the treated aluminum by an electroless plating method, and the Ni plating was then grown to a desired thickness by an electroplating method.

[0050] The solder plating layer 16 was plated by an electroplating method (barrel electroplating).

[0051] The Sn plating layer 20 was formed by pulling up the core ball including the solder plating layer 16 from a molten liquid containing Sn, Ag and Cu, Cu, Ag, Sb, In or Pb, and then immersing the core ball in a molten liquid of Sn. More specifically, the sample on which the solder plating layer 16 was formed was taken out from a plating liquid containing Sn, Ag and Cu, Cu, Ag, Sb, In or Pb, washed, and dried.

[0052] After that, the sample was put into a plating liquid containing methane sulfonic acid Sn, an organic acid and a surfactant, and the barrel electroplating was performed until the sample has the thickness of the Sn plating layer 20 described in each Example and each Comparative example (excluding Comparative example in which the Sn plating layer 20 is not formed).

[0053] In the following Table 1, aspects in which copper is used as the material of the core and the solder layer composition is made of SAC 305 are shown as Examples 1 to 9. Also in the following Table 2, aspects in which copper is used as the material of the core and the solder layer composition is made of SAC 305 are shown as Comparative Examples 1 to 9. In Examples 1 to 3 and Comparative Examples 1 to 3, the thickness of the solder layer on one side is 18 µm, but the thicknesses of the Sn layer one side are different from each other. In Examples 4 to 6 and Comparative Examples 4 to 6, the thickness of the solder layer one side is 38 µm, but the thicknesses of the Sn layer on one side are different from each other. In Examples 7 to 9 and Comparative Examples 7 to 9, the thickness of the solder layer on one side is 1 µm, but the thicknesses of the Sn layer on one side are different from each other. The "Sn layer: solder layer" shown in each Table is calculated by an expression of Sn layer thickness (one side) / solder layer (one side) × 100, and is a value obtained by dividing the thickness of the Sn layer on one side by the thickness of the solder layer on one side, and expressed in %. It has the same meaning in the other Tables. The phrase "less than the lower limit value" shown in Tables of Comparative Examples means that the thickness of the Sn layer is less than 0.215% of that of the solder layer, and the phrase "exceeding the upper limit value" shown in Tables of Comparative Examples means that the thickness of the Sn layer exceeds 36% of that of the solder layer. These have the same meanings in the other Tables. In all of Examples 1 to 9, good results could be confirmed to be obtained in each of yellowness and a defect at the time of bonding. Meanwhile, in all of Comparative Examples 1 to 9, any of yellowness and the time of bonding could be confirmed to be poor. In particular, it could be confirmed that when the Sn layer is not provided or when the thickness of the Sn layer is less than 0.215% of that of the solder layer, a problem in yellowness occurs. Meanwhile, it could be confirmed that when the thickness of the Sn layer exceeds 36% of that of the solder layer, a defect at the time of bonding occurs. [Table 1]EXAMPLE 1EXAMPLE 2EXAMPLE 3EXAMPLE 4EXAMPLE 5EXAMPLE 6vEXAMPLE 7EXAMPLE 8EXAMPLE 9CORE MATERIALCOPPERCOPPERCOPPERCOPPERCOPPERCOPPERCOPPERCOPPERCOPPERTHICKNESS OF SOLDER LAYER18 µm ON ONE SIDE18 µm ON ONE SIDE18 µm ON ONE SIDE38 µm ON ONE SIDE38 µm ON ONE SIDE38 µm ON ONE SIDE1 µm ON ONE SIDE1 µm ON ONE SIDE1 µm ON ONE SIDECOMPOSITION OF SOLDER LAYERSAC305SAC305SAC305SAC305SAC305SAC305SAC305SAC305SAC305THICKNESS OF Sn LAYER (µm)0.10.560.10.5120.10.230.36Sn LAYER: SOLDER LAYER0.5562.77833.3330.2631.31631.57910.00023.00036.000YELLOWNESS○○○○○○○○○DEFECT AT THE TIME OF BONDING○○○○○○○○○ [Table 2] COMPARATIVE EXAMPLE 1COMPARATIVE EXAMPLE 2COMPARATIVE EXAMPLE 3COMPARATIVE EXAMPLE 4COMPARATIVE EXAMPLE 5COMPARATIVE EXAMPLE 6COMPARATIVE EXAMPLE 7COMPARATIVE EXAMPLE 8COMPARATIVE EXAMPLE 9CORE MATERIALCOPPERCOPPERCOPPERCOPPERCOPPERCOPPERCOPPERCOPPERCOPPERTHICKNESS OF SOLDER LAYER18 µm ON ONE SIDE18 µm ON ONE SIDE18 µm ON ONE SIDE38 µm ON ONE SIDE38 µm ON ONE SIDE38 µm ON ONE SIDE1 µm ON ONE SIDE1 µm ON ONE SIDE1 µm ON ONE SIDECOMPOSITION OF SOLDER LAYERSAC305SAC305SAC305SAC305SAC305SAC305SAC305SAC305SAC305THICKNESS OF Sn LAYER (µm)00.031000.031500.0020.5Sn LAYER: SOLDER LAYER0. 0000.16755.5560. 0000.07939.4740. 0000.20050.0000:100LESS THAN LOWER LIMIT VALUEEXCEEDING UPPER LIMIT VALUE0:100LESS THAN LOWER LIMIT VALUEEXCEEDING UPPER LIMIT VALUE0:100LESS THAN LOWER LIMIT VALUEEXCEEDING UPPER LIMIT VALUEYELLOWNESS××○××○××○DEFECT AT THE TIME OF BONDING○○×○○×○○×

[0054] In the following Table 3, aspects in which copper is used as the material of the core and the solder layer composition is made of SnCu (Cu 0.7 Sn balance) are shown as Examples 10 to 18. Also in the following Table 4, aspects in which copper is used as the material of the core and the solder layer composition is made of SnCu are shown as Comparative Examples 10 to 18. In Examples 10 to 12 and Comparative Examples 10 to 12, the thickness of the solder layer on one side is 18 µm, but the thicknesses of the Sn layer on one side are different from each other. In Examples 13 to 15 and Comparative Examples 13 to 15, the thickness of the solder layer on one side is 38 µm, but the thicknesses of the Sn layer on one side are different from each other. In Examples 16 to 18 and Comparative Examples 16 to 18, the thickness of the solder layer on one side is 1 µm, but the thicknesses of the Sn layer on one side are different from each other. In all of Examples 10 to 18, good results could be confirmed to be obtained in each of yellowness and a defect at the time of bonding. Meanwhile, in all of Comparative Examples 10 to 18, any of yellowness and the time of bonding could be confirmed to be poor. In particular, it could be confirmed that when the Sn layer is not provided or when the thickness of the Sn layer is less than 0.215% of that of the solder layer, a problem in yellowness occurs. Meanwhile, it could be confirmed that when the thickness of the Sn layer exceeds 36% of that of the solder layer, a defect at the time of bonding occurs. [Table 3]EXAMPLE 10EXAMPLE 11EXAMPLE 12EXAMPLE 13EXAMPLE 14EXAMPLE 15EXAMPLE 16EXAMPLE 17EXAMPLE 18CORE MATERIALCOPPERCOPPERCOPPERCOPPERCOPPERCOPPERCOPPERCOPPERCOPPERTHICKNESS OF SOLDER LAYER18 µm ON ONE SIDE18 µm ON ONE SIDE18 µm ON ONE SIDE38 µm ON ONE SIDE38 µm ON ONE SIDE38 µm ON ONE SIDE1 µm ON ONE SIDE1 µm ON ONE SIDE1 µm ON ONE SIDECOMPOSITION OF SOLDER LAYERSnCuSnCuSnCuSnCuSnCuSnCuSnCuSnCuSnCuTHICKNESS OF Sn LAYER (µm)0.10.560.10.5120.10.230.36Sn LAYER: SOLDER LAYER0.5562.77833.3330.2631.31631.57910.00023.00036.000YELLOWNESS○○○○○○○○○DEFECT AT THE TIME OF BONDING○○○○○○○○○ [Table 4] COMPARATIVE EXAMPLE 10COMPARATIVE EXAMPLE 11COMPARATIVE EXAMPLE 12COMPARATIVE EXAMPLE 13COMPARATIVE EXAMPLE 14COMPARATIVE EXAMPLE 15COMPARATIVE EXAMPLE 16COMPARATIVE EXAMPLE 17COMPARATIVE EXAMPLE 18CORE MATERIALCOPPERCOPPERCOPPERCOPPERCOPPERCOPPERCOPPERCOPPERCOPPERTHICKNESS OF SOLDER LAYER18 µm ON ONE SIDE18 µm ON ONE SIDE18 µm ON ONE SIDE38 µm ON ONE SIDE38 µm ON ONE SIDE38 µm ON ONE SIDE1 µm ON ONE SIDE1 µm ON ONE SIDE1 µm ON ONE SIDECOMPOSITION OF SOLDER LAYERSnCuSnCuSnCuSnCuSnCuSnCuSnCuSnCuSnCuTHICKNESS OF Sn LAYER (µm)00.031000.031500.0020.5Sn LAYER: SOLDER LAYER0.0000.16755.5560.0000.07939.4740. 0000.20050.0000:100LESS THAN LOWER LIMIT VALUEEXCEEDING UPPER LIMIT VALUE0:100LESS THAN LOWER LIMIT VALUEEXCEEDING UPPER LIMIT VALUE0:100LESS THAN LOWER LIMIT VALUEEXCEEDING UPPER LIMIT VALUEYELLOWNESS××○××○××○DEFECT AT THE TIME OF BONDING○○×○○×○○×

[0055] In the following Table 5, aspects in which copper is used as the material of the core and the solder layer composition is made of SnAg (Ag 3.5 Sn balance) are shown as Examples 19 to 27. Also in the following Table 6, aspects in which copper is used as the material of the core and the solder layer composition is made of SnAg are shown as Comparative Examples 19 to 27. In Examples 19 to 21 and Comparative Examples 19 to 21, the thickness of the solder layer one side is 18 µm, but the thicknesses of the Sn layer one side are different from each other. In Examples 22 to 24 and Comparative Examples 22 to 24, the thickness of the solder layer on one side is 38 µm, but the thicknesses of the Sn layer on one side are different from each other. In Examples 25 to 27 and Comparative Examples 25 to 27, the thickness of the solder layer on one side is 1 µm, but the thicknesses of the Sn layer on one side are different from each other. In all of Examples 19 to 27, good results could be confirmed to be obtained in each of yellowness and a defect at the time of bonding. Meanwhile, in all of Comparative Examples 19 to 27, any of yellowness and the time of bonding could be confirmed to be poor. In particular, it could be confirmed that when the Sn layer is not provided or when the thickness of the Sn layer is less than 0.215% of that of the solder layer, a problem in yellowness occurs. Meanwhile, it could be confirmed that when the thickness of the Sn layer exceeds 36% of that of the solder layer, a defect at the time of bonding occurs. [Table 5]EXAMPLE 19EXAMPLE 20EXAMPLE 21EXAMPLE 22EXAMPLE 23EXAMPLE 24EXAMPLE 25EXAMPLE 26EXAMPLE 27CORE MATERIALCOPPERCOPPERCOPPERCOPPERCOPPERCOPPERCOPPERCOPPERCOPPERTHICKNESS OF SOLDER LAYER18 µm ON ONE SIDE18 µm ON ONE SIDE18 µm ON ONE SIDE38 µm ON ONE SIDE38 µm ON ONE SIDE38 µm ON ONE SIDE1 µm ON ONE SIDE1 µm ON ONE SIDE1 µm ON ONE SIDECOMPOSITION OF SOLDER LAYERSnAgSnAgSnAgSnAgSnAgSnAgSnAgSnAgSnAgTHICKNESS OF Sn LAYER (µm)0.10.560.10.5120.10.230.36Sn LAYER: SOLDER LAYER0.5562.77833.3330.2631.31631.57910.00023.00036.000YELLOWNESS○○○○○○○○○DEFECT AT THE TIME OF BONDING○○○○○○○○○ [Table 6] COMPARATIVE EXAMPLE 19COMPARATIVE EXAMPLE 20COMPARATIVE EXAMPLE 21COMPARATIVE EXAMPLE 22COMPARATIVE EXAMPLE 23COMPARATIVE EXAMPLE 24COMPARATIVE EXAMPLE 25COMPARATIVE EXAMPLE 26COMPARATIVE EXAMPLE 27CORE MATERIALCOPPERCOPPERCOPPERCOPPERCOPPERCOPPERCOPPERCOPPERCOPPERTHICKNESS OF SOLDER LAYER18 µm ON ONE SIDE18 µm ON ONE SIDE18 µm ON ONE SIDE38 µm ON ONE SIDE38 µm ON ONE SIDE38 µm ON ONE SIDE1 µm ON ONE SIDE1 µm ON ONE SIDE1 µm ON ONE SIDECOMPOSITION OF SOLDER LAYERSnAgSnAgSnAgSnAgSnAgSnAgSnAgSnAgSnAgTHICKNESS OF Sn LAYER (µm)00.031000.031500.0020.5Sn LAYER: SOLDER LAYER0.0000.16755.5560.0000.07939.4740. 0000.20050.0000:100LESS THAN LOWER LIMIT VALUEEXCEEDING UPPER LIMIT VALUE0:100LESS THAN LOWER LIMIT VALUEEXCEEDING UPPER LIMIT VALUE0:100LESS THAN LOWER LIMIT VALUEEXCEEDING UPPER LIMIT VALUEYELLOWNESS××○××○××○DEFECT AT THE TIME OF BONDING○○×○○×○○×

[0056] In the following Table 7, aspects in which copper is used as the material of the core and the solder layer composition is made of SnSb (Sb 10 Sn balance) are shown as Examples 28 to 36. Also in the following Table 8, aspects in which copper is used as the material of the core and the solder layer composition is made of SnSb are shown as Comparative Examples 28 to 36. In Examples 28 to 30 and Comparative Examples 28 to 30, the thickness of the solder layer on one side is 18 µm, but the thicknesses of the Sn layer on one side are different from each other. In Examples 31 to 33 and Comparative Examples 31 to 33, the thickness of the solder layer on one side is 38 µm, but the thicknesses of the Sn layer on one side are different from each other. In Examples 34 to 36 and Comparative Examples 34 to 36, the thickness of the solder layer on one side is 1 µm, but the thicknesses of the Sn layer on one side are different from each other. In all of Examples 28 to 36, good results could be confirmed to be obtained in each of yellowness and a defect at the time of bonding. Meanwhile, in all of Comparative Examples 28 to 36, any of yellowness and the time of bonding could be confirmed to be poor. In particular, it could be confirmed that when the Sn layer is not provided or when the thickness of the Sn layer is less than 0.215% of that of the solder layer, a problem in yellowness occurs. Meanwhile, it could be confirmed that when the thickness of the Sn layer exceeds 36% of that of the solder layer, a defect at the time of bonding occurs. [Table 7]EXAMPLE 28EXAMPLE 29EXAMPLE 30EXAMPLE 31EXAMPLE 32EXAMPLE 33EXAMPLE 34EXAMPLE 35EXAMPLE 36CORE MATERIALCOPPERCOPPERCOPPERCOPPERCOPPERCOPPERCOPPERCOPPERCOPPERTHICKNESS OF SOLDER LAYER18 µm ON ONE SIDE18 µm ON ONE SIDE18 µm ON ONE SIDE38 µm ON ONE SIDE38 µm ON ONE SIDE38 µm ON ONE SIDE1 µm ON ONE SIDE1 µm ON ONE SIDE1 µm ON ONE SIDECOMPOSITION OF SOLDER LAYERSnSbSnSbSnSbSnSbSnSbSnSbSnSbSnSbSnSbTHICKNESS OF Sn LAYER (µm)0.10.560.10.5120.10.230.36Sn LAYER: SOLDER LAYER0.5562.77833.3330.2631.31631.57910.00023.00036.000YELLOWNESS○○○○○○○○○DEFECT AT THE TIME OF BONDING○○○○○○○○○ [Table 8] COMPARATIVE EXAMPLE 28COMPARATIVE EXAMPLE 29COMPARATIVE EXAMPLE 30COMPARATIVE EXAMPLE 31COMPARATIVE EXAMPLE 32COMPARATIVE EXAMPLE 33COMPARATIVE EXAMPLE 34COMPARATIVE EXAMPLE 35COMPARATIVE EXAMPLE 36CORE MATERIALCOPPERCOPPERCOPPERCOPPERCOPPERCOPPERCOPPERCOPPERCOPPERTHICKNESS OF SOLDER LAYER18 µm ON ONE SIDE18 µm ON ONE SIDE18 µm ON ONE SIDE38 µm ON ONE SIDE38 µm ON ONE SIDE38 µm ON ONE SIDE1 µm ON ONE SIDE1 µm ON ONE SIDE1 µm ON ONE SIDECOMPOSITION OF SOLDER LAYERSnSbSnSbSnSbSnSbSnSbSnSbSnSbSnSbSnSbTHICKNESS OF Sn LAYER (µm)00.031000.031500.0020.5Sn LAYER: SOLDER LAYER0.0000.16755.5560.0000.07939.4740. 0000.20050.0000:100LESS THAN LOWER LIMIT VALUEEXCEEDING UPPER LIMIT VALUE0:100LESS THAN LOWER LIMIT VALUEEXCEEDING UPPER LIMIT VALUE0:100LESS THAN LOWER LIMIT VALUEEXCEEDING UPPER LIMIT VALUEYELLOWNESS××○××○××○DEFECT AT THE TIME OF BONDING○○×○○×○○×

[0057] In the following Table 9, aspects in which copper is used as the material of the core and the solder layer composition is made of SnIn (In 45 Sn balance) is shown as Examples 37 to 45. Also in the following Table 10, aspects in which copper is used as the material of the core and the solder layer composition is made of SnIn are shown as Comparative Examples 37 to 45. In Examples 37 to 39 and Comparative Examples 37 to 39, the thickness of the solder layer on one side is 18 µm, but the thicknesses of the Sn layer on one side are different from each other. In Examples 40 to 42 and Comparative Examples 40 to 42, the thickness of the solder layer on one side is 38 µm, but the thicknesses of the Sn layer on one side are different from each other. In Examples 43 to 45 and Comparative Examples 43 to 45, the thickness of the solder layer on one side is 1 µm, but the thicknesses of the Sn layer on one side are different from each other. In all of Examples 37 to 45, good results could be confirmed to be obtained in each of yellowness and a defect at the time of bonding. Meanwhile, in all of Comparative Examples 37 to 45, any of yellowness and the time of bonding could be confirmed to be poor. In particular, it could be confirmed that when the Sn layer is not provided or when the thickness of the Sn layer is less than 0.215% of that of the solder layer, a problem in yellowness occurs. Meanwhile, it could be confirmed that when the thickness of the Sn layer exceeds 36% of that of the solder layer, a defect at the time of bonding occurs. [Table 9]EXAMPLE 37EXAMPLE 38EXAMPLE 39EXAMPLE 40EXAMPLE 41EXAMPLE 42EXAMPLE 43EXAMPLE 44EXAMPLE 45CORE MATERIALCOPPERCOPPERCOPPERCOPPERCOPPERCOPPERCOPPERCOPPERCOPPERTHICKNESS OF SOLDER LAYER18 µm ON ONE SIDE18 µm ON ONE SIDE18 µm ON ONE SIDE38 µm ON ONE SIDE38 µm ON ONE SIDE38 µm ON ONE SIDE1 µm ON ONE SIDE1 µm ON ONE SIDE1 µm ON ONE SIDECOMPOSITION OF SOLDER LAYERSnInSnInSnInSnInSnInSnInSnInSnInSnInTHICKNESS OF Sn LAYER (µm)0.10.560.10.5120.10.230.36Sn LAYER: SOLDER LAYER0.5562.77833.3330.2631.31631.57910.00023.00036.000YELLOWNESS○○○○○○○○○DEFECT AT THE TIME OF BONDING○○○○○○○○○ [Table 10] COMPARATIVE EXAMPLE 37COMPARATIVE EXAMPLE 38COMPARATIVE EXAMPLE 39COMPARATIVE EXAMPLE 40COMPARATIVE EXAMPLE 41COMPARATIVE EXAMPLE 42COMPARATIVE EXAMPLE 43COMPARATIVE EXAMPLE 44COMPARATIVE EXAMPLE 45CORE MATERIALCOPPERCOPPERCOPPERCOPPERCOPPERCOPPERCOPPERCOPPERCOPPERTHICKNESS OF SOLDER LAYER18 µm ON ONE SIDE18 µm ON ONE SIDE18 µm ON ONE SIDE38 µm ON ONE SIDE38 µm ON ONE SIDE38 µm ON ONE SIDE1 µm ON ONE SIDE1 µm ON ONE SIDE1 µm ON ONE SIDECOMPOSITION OF SOLDER LAYERSnInSnInSnInSnInSnInSnInSnInSnInSnInTHICKNESS OF Sn LAYER (µm)00.031000.031500.0020.5Sn LAYER: SOLDER LAYER0.0000.16755.5560.0000.07939.4740. 0000.20050.0000:100LESS THAN LOWER LIMIT VALUEEXCEEDING UPPER LIMIT VALUE0:100LESS THAN LOWER LIMIT VALUEEXCEEDING UPPER LIMIT VALUE0:100LESS THAN LOWER LIMIT VALUEEXCEEDING UPPER LIMIT VALUEYELLOWNESS××○××○××○DEFECT AT THE TIME OF BONDING○○×○○×○○×

[0058] In the following Table 11, aspects in which copper is used as the material of the core and the solder layer composition is made of SnPb (Pb 37 Sn balance) are shown as Examples 46 to 54. Also in the following Table 12, aspects in which copper is used as the material of the core and the solder layer composition is made of SnPb are shown as Comparative Examples 46 to 54. In Examples 46 to 48 and Comparative Examples 46 to 48, the thickness of the solder layer on one side is 18 µm, but the thicknesses of the Sn layer on one side are different from each other. In Examples 49 to 51 and Comparative Examples 49 to 51, the thickness of the solder layer on one side is 38 µm, but the thicknesses of the Sn layer on one side are different from each other. In Examples 52 to 54 and Comparative Examples 52 to 54, the thickness of the solder layer on one side is 1 µm, but the thicknesses of the Sn layer on one side are different from each other. In all of Examples 46 to 54, good results could be confirmed to be obtained in each of yellowness and a defect at the time of bonding. Meanwhile, in all of Comparative Examples 46 to 54, any of yellowness and the time of bonding could be confirmed to be poor. In particular, it could be confirmed that when the Sn layer is not provided or when the thickness of the Sn layer is less than 0.215% of that of the solder layer, a problem in yellowness occurs. Meanwhile, it could be confirmed that when the thickness of the Sn layer exceeds 36% of that of the solder layer, a defect at the time of bonding occurs. [Table 11]EXAMPLE 46EXAMPLE 47EXAMPLE 48EXAMPLE 49EXAMPLE 50EXAMPLE 51EXAMPLE 52EXAMPLE 53EXAMPLE 54CORE MATERIALCOPPERCOPPERCOPPERCOPPERCOPPERCOPPERCOPPERCOPPERCOPPERTHICKNESS OF SOLDER LAYER18 µm ON ONE SIDE18 µm ON ONE SIDE18 µm ON ONE SIDE38 µm ON ONE SIDE38 µm ON ONE SIDE38 µm ON ONE SIDE1 µm ON ONE SIDE1 µm ON ONE SIDE1 µm ON ONE SIDECOMPOSITION OF SOLDER LAYERSnPbSnPbSnPbSnPbSnPbSnPbSnPbSnPbSnPbTHICKNESS OF Sn LAYER (µm)0.10.560.10.5120.10.230.36Sn LAYER: SOLDER LAYER0.5562.77833.3330.2631.31631.57910.00023.00036.000YELLOWNESS○○○○○○○○○DEFECT AT THE TIME OF BONDING○○○○○○○○○ [Table 12] COMPARATIVE EXAMPLE 46COMPARATIVE EXAMPLE 47COMPARATIVE EXAMPLE 48COMPARATIVE EXAMPLE 49COMPARATIVE EXAMPLE 50COMPARATIVE EXAMPLE 51COMPARATIVE EXAMPLE 52COMPARATIVE EXAMPLE 53COMPARATIVE EXAMPLE 54CORE MATERIALCOPPERCOPPERCOPPERCOPPERCOPPERCOPPERCOPPERCOPPERCOPPERTHICKNESS OF SOLDER LAYER18 µm ON ONE SIDE18 µm ON ONE SIDE18 µm ON ONE SIDE38 µm ON ONE SIDE38 µm ON ONE SIDE38 µm ON ONE SIDE1 µm ON ONE SIDE1 µm ON ONE SIDE1 µm ON ONE SIDECOMPOSITION OF SOLDER LAYERSnPbSnPbSnPbSnPbSnPbSnPbSnPbSnPbSnPbTHICKNESS OF Sn LAYER (µm)00.031000.031500.0020.5Sn LAYER: SOLDER LAYER0.0000.16755.5560.0000.07939.4740. 0000.20050.0000:100LESS THAN LOWER LIMIT VALUEEXCEEDING UPPER LIMIT VALUE0:100LESS THAN LOWER LIMIT VALUEEXCEEDING UPPER LIMIT VALUE0:100LESS THAN LOWER LIMIT VALUEEXCEEDING UPPER LIMIT VALUEYELLOWNESS××○××○××○DEFECT AT THE TIME OF BONDING○○×○○×○○×

[0059] In the following Tables 13 to 24, the solder layer composition was changed to SAC 305, SnCu (Cu 0.7 Sn balance), SnAg (Ag 3.5 Sn balance), SnSb (Sb 10 Sn balance), SnIn (In 45 Sn balance), and SnPb (Pb 37 Sn balance), and the thickness of the solder layer on one side and the thickness of the Sn layer on one side were changed in the same manner as in Examples 1 to 54 and Comparative Examples 1 to 54 shown in Tables 1 to 12 except that aluminum was used as the material of the core. In all of Examples 55 to 108, good results could be confirmed to be obtained in each of yellowness and a defect at the time of bonding. Meanwhile, in all of Comparative Examples 55 to 108, any of yellowness and the time of bonding could be confirmed to be poor. In particular, it could be confirmed that when the Sn layer is not provided or when the thickness of the Sn layer is less than 0.215% of that of the solder layer, a problem in yellowness occurs. Meanwhile, it could be confirmed that when the thickness of the Sn layer exceeds 36% of that of the solder layer, a defect at the time of bonding occurs. [Table 13]EXAMPLE 55EXAMPLE 56EXAMPLE 57EXAMPLE 58EXAMPLE 59EXAMPLE 60EXAMPLE 61EXAMPLE 62EXAMPLE 63CORE MATERIALALUMINUMALUMINUMALUMINUMALUMINUMALUMINUMALUMINUMALUMINUMALUMINUMALUMINUMTHICKNESS OF SOLDER LAYER18 µm ON ONE SIDE18 µm ON ONE SIDE18 µm ON ONE SIDE38 µm ON ONE SIDE38 µm ON ONE SIDE38 µm ON ONE SIDE1 µm ON ONE SIDE1 µm ON ONE SIDE1 µm ON ONE SIDECOMPOSITION OF SOLDER LAYERSAC305SAC305SAC305SAC305SAC305SAC305SAC305SAC305SAC305THICKNESS OF Sn LAYER (µm)0.10.560.10.5120.10.230.36Sn LAYER: SOLDER LAYER0.5562.77833.3330.2631.31631.57910.00023.00036.000YELLOWNESS○○○○○○○○○DEFECT AT THE TIME OF BONDING○○○○○○○○○ [Table 14] COMPARATIVE EXAMPLE 55COMPARATIVE EXAMPLE 56COMPARATIVE EXAMPLE 57COMPARATIVE EXAMPLE 58COMPARATIVE EXAMPLE 59COMPARATIVE EXAMPLE 60COMPARATIVE EXAMPLE 61COMPARATIVE EXAMPLE 62COMPARATIVE EXAMPLE 63CORE MATERIALALUMINUMALUMINUMALUMINUMALUMINUMALUMINUMALUMINUMALUMINUMALUMINUMALUMINUMTHICKNESS OF SOLDER LAYER18 µm ON ONE SIDE18 µm ON ONE SIDE18 µm ON ONE SIDE38 µm ON ONE SIDE38 µm ON ONE SIDE38 µm ON ONE SIDE1 µm ON ONE SIDE1 µm ON ONE SIDE1 µm ON ONE SIDECOMPOSITION OF SOLDER LAYERSAC305SAC305SAC305SAC305SAC305SAC305SAC305SAC305SAC305THICKNESS OF Sn LAYER (µm)00.031000.031500.0020.5Sn LAYER: SOLDER LAYER0.0000.16755.5560.0000.07939.4740. 0000.20050.0000:100LESS THAN LOWER LIMIT VALUEEXCEEDING UPPER LIMIT VALUE0:100LESS THAN LOWER LIMIT VALUEEXCEEDING UPPER LIMIT VALUE0:100LESS THAN LOWER LIMIT VALUEEXCEEDING UPPER LIMIT VALUEYELLOWNESS××○××○××○DEFECT AT THE TIME OF BONDING○○×○○×○○× [Table 15] EXAMPLE 64EXAMPLE 65EXAMPLE 66EXAMPLE 67EXAMPLE 68EXAMPLE 69EXAMPLE 70EXAMPLE 71EXAMPLE 72CORE MATERIALALUMINUMALUMINUMALUMINUMALUMINUMALUMINUMALUMINUMALUMINUMALUMINUMALUMINUMTHICKNESS OF SOLDER LAYER18 µm ON ONE SIDE18 µm ON ONE SIDE18 µm ON ONE SIDE38 µm ON ONE SIDE38 µm ON ONE SIDE38 µm ON ONE SIDE1 µm ON ONE SIDE1 µm ON ONE SIDE1 µm ON ONE SIDECOMPOSITION OF SOLDER LAYERSnCuSnCuSnCuSnCuSnCuSnCuSnCuSnCuSnCuTHICKNESS OF Sn LAYER (µm)0.10.560.10.5120.10.230.36Sn LAYER: SOLDER LAYER0.5562.77833.3330.2631.31631.57910.00023.00036.000YELLOWNESS○○○○○○○○○DEFECT AT THE TIME OF BONDING○○○○○○○○○ [Table 16] COMPARATIVE EXAMPLE 64COMPARATIVE EXAMPLE 65COMPARATIVE EXAMPLE 66COMPARATIVE EXAMPLE 67COMPARATIVE EXAMPLE 68COMPARATIVE EXAMPLE 69COMPARATIVE EXAMPLE 70COMPARATIVE EXAMPLE 71COMPARATIVE EXAMPLE 72CORE MATERIALALUMINUMALUMINUMALUMINUMALUMINUMALUMINUMALUMINUMALUMINUMALUMINUMALUMINUMTHICKNESS OF SOLDER LAYER18 µm ON ONE SIDE18 µm ON ONE SIDE18 µm ON ONE SIDE38 µm ON ONE SIDE38 µm ON ONE SIDE38 µm ON ONE SIDE1 µm ON ONE SIDE1 µm ON ONE SIDE1 µm ON ONE SIDECOMPOSITION OF SOLDER LAYERSnCuSnCuSnCuSnCuSnCuSnCuSnCuSnCuSnCuTHICKNESS OF Sn LAYER (µm)00.031000.031500.0020.5Sn LAYER: SOLDER LAYER0.0000.16755.5560.0000.07939.4740. 0000.20050.0000:100LESS THAN LOWER LIMIT VALUEEXCEEDING UPPER LIMIT VALUE0:100LESS THAN LOWER LIMIT VALUEEXCEEDING UPPER LIMIT VALUE0:100LESS THAN LOWER LIMIT VALUEEXCEEDING UPPER LIMIT VALUEYELLOWNESS××○××○××○DEFECT AT THE TIME OF BONDING○○×○○×○○× [Table 17] EXAMPLE 73EXAMPLE 74EXAMPLE 75EXAMPLE 76EXAMPLE 77EXAMPLE 78EXAMPLE 79EXAMPLE 80EXAMPLE 81CORE MATERIALALUMINUMALUMINUMALUMINUMALUMINUMALUMINUMALUMINUMALUMINUMALUMINUMALUMINUMTHICKNESS OF SOLDER LAYER18 µm ON ONE SIDE18 µm ON ONE SIDE18 µm ON ONE SIDE38 µm ON ONE SIDE38 µm ON ONE SIDE38 µm ON ONE SIDE1 µm ON ONE SIDE1 µm ON ONE SIDE1 µm ON ONE SIDECOMPOSITION OF SOLDER LAYERSnAgSnAgSnAgSnAgSnAgSnAgSnAgSnAgSnAgTHICKNESS OF Sn LAYER (µm)0.10.560.10.5120.10.230.36Sn LAYER: SOLDER LAYER0.5562.77833.3330.2631.31631.57910.00023.00036.000YELLOWNESS○○○○○○○○○DEFECT AT THE TIME OF BONDING○○○○○○○○○ [Table 18] COMPARATIVE EXAMPLE 73COMPARATIVE EXAMPLE 74COMPARATIVE EXAMPLE 75COMPARATIVE EXAMPLE 76COMPARATIVE EXAMPLE 77COMPARATIVE EXAMPLE 78COMPARATIVE EXAMPLE 79COMPARATIVE EXAMPLE 80COMPARATIVE EXAMPLE 81CORE MATERIALALUMINUMALUMINUMALUMINUMALUMINUMALUMINUMALUMINUMALUMINUMALUMINUMALUMINUMTHICKNESS OF SOLDER LAYER18 µm ON ONE SIDE18 µm ON ONE SIDE18 µm ON ONE SIDE38 µm ON ONE SIDE38 µm ON ONE SIDE38 µm ON ONE SIDE1 µm ON ONE SIDE1 µm ON ONE SIDE1 µm ON ONE SIDECOMPOSITION OF SOLDER LAYERSnAgSnAgSnAgSnAgSnAgSnAgSnAgSnAgSnAgTHICKNESS OF Sn LAYER (µm)00.031000.031500.0020.5Sn LAYER: SOLDER LAYER0.0000.16755.5560.0000.07939.4740. 0000.20050.0000:100LESS THAN LOWER LIMIT VALUEEXCEEDING UPPER LIMIT VALUE0:100LESS THAN LOWER LIMIT VALUEEXCEEDING UPPER LIMIT VALUE0:100LESS THAN LOWER LIMIT VALUEEXCEEDING UPPER LIMIT VALUEYELLOWNESS××○××○××○DEFECT AT THE TIME OF BONDING○○×○○×○○× [ Table 19] EXAMPLE 82EXAMPLE 83EXAMPLE 84EXAMPLE 85EXAMPLE 86EXAMPLE 87EXAMPLE 88EXAMPLE 89EXAMPLE 90CORE MATERIALALUMINUMALUMINUMALUMINUMALUMINUMALUMINUMALUMINUMALUMINUMALUMINUMALUMINUMTHICKNESS OF SOLDER LAYER18 µm ON ONE SIDE18 µm ON ONE SIDE18 µm ON ONE SIDE38 µm ON ONE SIDE38 µm ON ONE SIDE38 µm ON ONE SIDE1 µm ON ONE SIDE1 µm ON ONE SIDE1 µm ON ONE SIDECOMPOSITION OF SOLDER LAYERSnSbSnSbSnSbSnSbSnSbSnSbSnSbSnSbSnSbTHICKNESS OF Sn LAYER (µm)0.10.560.10.5120.10.230.36Sn LAYER: SOLDER LAYER0.5562.77833.3330.2631.31631.57910.00023.00036.000YELLOWNESS○○○○○○○○○DEFECT AT THE TIME OF BONDING○○○○○○○○○ [Table 20] COMPARATIVE EXAMPLE 82COMPARATIVE EXAMPLE 83COMPARATIVE EXAMPLE 84COMPARATIVE EXAMPLE 85COMPARATIVE EXAMPLE 86COMPARATIVE EXAMPLE 87COMPARATIVE EXAMPLE 88COMPARATIVE EXAMPLE 89COMPARATIVE EXAMPLE 90CORE MATERIALALUMINUMALUMINUMALUMINUMALUMINUMALUMINUMALUMINUMALUMINUMALUMINUMALUMINUMTHICKNESS OF SOLDER LAYER18 µm ON ONE SIDE18 µm ON ONE SIDE18 µm ON ONE SIDE38 µm ON ONE SIDE38 µm ON ONE SIDE38 µm ON ONE SIDE1 µm ON ONE SIDE1 µm ON ONE SIDE1 µm ON ONE SIDECOMPOSITION OF SOLDER LAYERSnSbSnSbSnSbSnSbSnSbSnSbSnSbSnSbSnSbTHICKNESS OF Sn LAYER (µm)00.031000.031500.0020.5Sn LAYER: SOLDER LAYER0.0000.16755.5560.0000.07939.4740. 0000.20050.0000:100LESS THAN LOWER LIMIT VALUEEXCEEDING UPPER LIMIT VALUE0:100LESS THAN LOWER LIMIT VALUEEXCEEDING UPPER LIMIT VALUE0:100LESS THAN LOWER LIMIT VALUEEXCEEDING UPPER LIMIT VALUEYELLOWNESS××○××○××○DEFECT AT THE TIME OF BONDING○○×○○×○○× [Table 21] EXAMPLE 91EXAMPLE 92EXAMPLE 93EXAMPLE 94EXAMPLE 95EXAMPLE 96EXAMPLE 97EXAMPLE 98EXAMPLE 99CORE MATERIALALUMINUMALUMINUMALUMINUMALUMINUMALUMINUMALUMINUMALUMINUMALUMINUMALUMINUMTHICKNESS OF SOLDER LAYER18 µm ON ONE SIDE18 µm ON ONE SIDE18 µm ON ONE SIDE38 µm ON ONE SIDE38 µm ON ONE SIDE38 µm ON ONE SIDE1 µm ON ONE SIDE1 µm ON ONE SIDE1 µm ON ONE SIDECOMPOSITION OF SOLDER LAYERSnInSnInSnInSnInSnInSnInSnInSnInSnInTHICKNESS OF Sn LAYER (µm)0.10.560.10.5120.10.230.36Sn LAYER: SOLDER LAYER0.5562.77833.3330.2631.31631.57910.00023.00036.000YELLOWNESS○○○○○○○○○DEFECT AT THE TIME OF BONDING○○○○○○○○○ [Table 22] COMPARATIVE EXAMPLE 91COMPARATIVE EXAMPLE 92COMPARATIVE EXAMPLE 93COMPARATIVE EXAMPLE 94COMPARATIVE EXAMPLE 95COMPARATIVE EXAMPLE 96COMPARATIVE EXAMPLE 97COMPARATIVE EXAMPLE 98COMPARATIVE EXAMPLE 99CORE MATERIALALUMINUMALUMINUMALUMINUMALUMINUMALUMINUMALUMINUMALUMINUMALUMINUMALUMINUMTHICKNESS OF SOLDER LAYER18 µm ON ONE SIDE18 µm ON ONE SIDE18 µm ON ONE SIDE38 µm ON ONE SIDE38 µm ON ONE SIDE38 µm ON ONE SIDE1 µm ON ONE SIDE1 µm ON ONE SIDE1 µm ON ONE SIDECOMPOSITION OF SOLDER LAYERSnInSnInSnInSnInSnInSnInSnInSnInSnInTHICKNESS OF Sn LAYER (µm)00.031000.031500.0020.5Sn LAYER: SOLDER LAYER0. 0000.16755.5560. 0000.07939.4740. 0000.20050.0000:100LESS THAN LOWER LIMIT VALUEEXCEEDING UPPER LIMIT VALUE0:100LESS THAN LOWER LIMIT VALUEEXCEEDING UPPER LIMIT VALUE0:100LESS THAN LOWER LIMIT VALUEEXCEEDING UPPER LIMIT VALUEYELLOWNESS××○××○××○DEFECT AT THE TIME OF BONDING○○×○○×○○× [Table 23] EXAMPLE 100EXAMPLE 101EXAMPLE 102EXAMPLE 103EXAMPLE 104EXAMPLE 105EXAMPLE 106EXAMPLE 107EXAMPLE 108CORE MATERIALALUMINUMALUMINUMALUMINUMALUMINUMALUMINUMALUMINUMALUMINUMALUMINUMALUMINUMTHICKNESS OF SOLDER LAYER18 µm ON ONE SIDE18 µm ON ONE SIDE18 µm ON ONE SIDE38 µm ON ONE SIDE38 µm ON ONE SIDE38 µm ON ONE SIDE1 µm ON ONE SIDE1 µm ON ONE SIDE1 µm ON ONE SIDECOMPOSITION OF SOLDER LAYERSnPbSnPbSnPbSnPbSnPbSnPbSnPbSnPbSnPbTHICKNESS OF Sn LAYER (µm)0.10.560.10.5120.10.230.36Sn LAYER: SOLDER LAYER0.5562.77833.3330.2631.31631.57910.00023.00036.000YELLOWNESS○○○○○○○○○DEFECT AT THE TIME OF BONDING○○○○○○○○○ [Table 24] COMPARATIVE EXAMPLE 100COMPARATIVE EXAMPLE 101COMPARATIVE EXAMPLE 102COMPARATIVE EXAMPLE 103COMPARATIVE EXAMPLE 104COMPARATIVE EXAMPLE 105COMPARATIVE EXAMPLE 106COMPARATIVE EXAMPLE 107COMPARATIVE EXAMPLE 108CORE MATERIALALUMINUMALUMINUMALUMINUMALUMINUMALUMINUMALUMINUMALUMINUMALUMINUMALUMINUMTHICKNESS OF SOLDER LAYER18 µm ON ONE SIDE18 µm ON ONE SIDE18 µm ON ONE SIDE38 µm ON ONE SIDE38 µm ON ONE SIDE38 µm ON ONE SIDE1 µm ON ONE SIDE1 µm ON ONE SIDE1 µm ON ONE SIDECOMPOSITION OF SOLDER LAYERSnPbSnPbSnPbSnPbSnPbSnPbSnPbSnPbSnPbTHICKNESS OF Sn LAYER (µm)00.031000.031500.0020.5Sn LAYER: SOLDER LAYER0. 0000.16755.5560. 0000.07939.4740. 0000.20050.0000:100LESS THAN LOWER LIMIT VALUEEXCEEDING UPPER LIMIT VALUE0:100LESS THAN LOWER LIMIT VALUEEXCEEDING UPPER LIMIT VALUE0:100LESS THAN LOWER LIMIT VALUEEXCEEDING UPPER LIMIT VALUEYELLOWNESS××○××○××○DEFECT AT THE TIME OF BONDING○○×○○×○○×

[0060] In the following Tables 25 to 36, the solder layer composition was changed to SAC 305, SnCu (Cu 0.75 Sn balance), SnAg (Ag 3.5 Sn balance), SnSb (Sb 10 Sn balance), SnIn (In 45 Sn balance), and SnPb (Pb 37 Sn balance), and the thickness of the solder layer on one side and the thickness of the Sn layer on one side were changed in the same manner as in Examples 1 to 54 and Comparative Examples 1 to 54 shown in Tables 1 to 12, and Examples 55 to 108 and Comparative Examples 55 to 108 shown in Tables 13 to 24 except that a styrene-butadiene block copolymer as a resin was used as the material of the core. In all of Examples 109 to 162, good results could be confirmed to be obtained in each of yellowness and a defect at the time of bonding. Meanwhile, in all of Comparative Examples 109 to 162, any of yellowness and the time of bonding could be confirmed to be poor. In particular, it could be confirmed that when the Sn layer is not provided or when the thickness of the Sn layer is less than 0.215% of that of the solder layer, a problem in yellowness occurs. Meanwhile, it could be confirmed that when the thickness of the Sn layer exceeds 36% of that of the solder layer, a defect at the time of bonding occurs. [Table 25]EXAMPLE 109EXAMPLE 110EXAMPLE 111EXAMPLE 112EXAMPLE 113EXAMPLE 114EXAMPLE 115EXAMPLE 116EXAMPLE 117CORE MATERIALRESINRESINRESINRESINRESINRESINRESINRESINRESINTHICKNESS OF SOLDER LAYER18 µm ON ONE SIDE18 µm ON ONE SIDE18 µm ON ONE SIDE38 µm ON ONE SIDE38 µm ON ONE SIDE38 µm ON ONE SIDE1 µm ON ONE SIDE1 µm ON ONE SIDE1 µm ON ONE SIDECOMPOSITION OF SOLDER LAYERSAC305SAC305SAC305SAC305SAC305SAC305SAC305SAC305SAC305THICKNESS OF Sn LAYER (µm)0.10.560.10.5120.10.230.36Sn LAYER: SOLDER LAYER0.5562.77833.3330.2631.31631.57910.00023.00036.000YELLOWNESS○○○○○○○○○DEFECT AT THE TIME OF BONDING○○○○○○○○○ [Table 26] COMPARATIVE EXAMPLE 109COMPARATIVE EXAMPLE 110COMPARATIVE EXAMPLE 111COMPARATIVE EXAMPLE 112COMPARATIVE EXAMPLE 113COMPARATIVE EXAMPLE 114COMPARATIVE EXAMPLE 115COMPARATIVE EXAMPLE 116COMPARATIVE EXAMPLE 117CORE MATERIALRESINRESINRESINRESINRESINRESINRESINRESINRESINTHICKNESS OF SOLDER LAYER18 µm ON ONE SIDE18 µm ON ONE SIDE18 µm ON ONE SIDE38 µm ON ONE SIDE38 µm ON ONE SIDE38 µm ON ONE SIDE1 µm ON ONE SIDE1 µm ON ONE SIDE1 µm ON ONE SIDECOMPOSITION OF SOLDER LAYERSAC305SAC305SAC305SAC305SAC305SAC305SAC305SAC305SAC305THICKNESS OF Sn LAYER (µm)00.031000.031500.0020.5Sn LAYER: SOLDER LAYER0. 0000.16755.5560. 0000.07939.4740. 0000.20050.0000:100LESS THAN LOWER LIMIT VALUEEXCEEDING UPPER LIMIT VALUE0:100LESS THAN LOWER LIMIT VALUEEXCEEDING UPPER LIMIT VALUE0:100LESS THAN LOWER LIMIT VALUEEXCEEDING UPPER LIMIT VALUEYELLOWNESS××○××○××○DEFECT AT THE TIME OF BONDING○○×○○×○○× [Table 27] EXAMPLE 118EXAMPLE 119EXAMPLE 120EXAMPLE 121EXAMPLE 122EXAMPLE 123EXAMPLE 124EXAMPLE 125EXAMPLE 126CORE MATERIALRESINRESINRESINRESINRESINRESINRESINRESINRESINTHICKNESS OF SOLDER LAYER18 µm ON ONE SIDE18 µm ON ONE SIDE18 µm ON ONE SIDE38 µm ON ONE SIDE38 µm ON ONE SIDE38 µm ON ONE SIDE1 µm ON ONE SIDE1 µm ON ONE SIDE1 µm ON ONE SIDECOMPOSITION OF SOLDER LAYERSnCuSnCuSnCuSnCuSnCuSnCuSnCuSnCuSnCuTHICKNESS OF Sn LAYER (µm)0.10.560.10.5120.10.230.36Sn LAYER: SOLDER LAYER0.5562.77833.3330.2631.31631.57910.00023.00036.000YELLOWNESS○○○○○○○○○DEFECT AT THE TIME OF BONDING○○○○○○○○○ [Table 28] COMPARATIVE EXAMPLE 118COMPARATIVE EXAMPLE 119COMPARATIVE EXAMPLE 120COMPARATIVE EXAMPLE 121COMPARATIVE EXAMPLE 122COMPARATIVE EXAMPLE 123COMPARATIVE EXAMPLE 124COMPARATIVE EXAMPLE 125COMPARATIVE EXAMPLE 126CORE MATERIALRESINRESINRESINRESINRESINRESINRESINRESINRESINTHICKNESS OF SOLDER LAYER18 µm ON ONE SIDE18 µm ON ONE SIDE18 µm ON ONE SIDE38 µm ON ONE SIDE38 µm ON ONE SIDE38 µm ON ONE SIDE1 µm ON ONE SIDE1 µm ON ONE SIDE1 µm ON ONE SIDECOMPOSITION OF SOLDER LAYERSnCuSnCuSnCuSnCuSnCuSnCuSnCuSnCuSnCuTHICKNESS OF Sn LAYER (µm)00.031000.031500.0020.5Sn LAYER: SOLDER LAYER0.0000.16755.5560.0000.07939.4740. 0000.20050.0000:100LESS THAN LOWER LIMIT VALUEEXCEEDING UPPER LIMIT VALUE0:100LESS THAN LOWER LIMIT VALUEEXCEEDING UPPER LIMIT VALUE0:100LESS THAN LOWER LIMIT VALUEEXCEEDING UPPER LIMIT VALUEYELLOWNESS××○××○××○DEFECT AT THE TIME OF BONDING○○×○○×○○× [Table 29] EXAMPLE 127EXAMPLE 128EXAMPLE 129EXAMPLE 130EXAMPLE 131EXAMPLE 132EXAMPLE 133EXAMPLE 134EXAMPLE 135CORE MATERIALRESINRESINRESINRESINRESINRESINRESINRESINRESINTHICKNESS OF SOLDER LAYER18 µm ON ONE SIDE18 µm ON ONE SIDE18 µm ON ONE SIDE38 µm ON ONE SIDE38 µm ON ONE SIDE38 µm ON ONE SIDE1 µm ON ONE SIDE1 µm ON ONE SIDE1 µm ON ONE SIDECOMPOSITION OF SOLDER LAYERSnAgSnAgSnAgSnAgSnAgSnAgSnAgSnAgSnAgTHICKNESS OF Sn LAYER (µm)0.10.560.10.5120.10.230.36Sn LAYER: SOLDER LAYER0.5562.77833.3330.2631.31631.57910.00023.00036.000YELLOWNESS○○○○○○○○○DEFECT AT THE TIME OF BONDING○○○○○○○○○ [Table 30] COMPARATIVE EXAMPLE 127COMPARATIVE EXAMPLE 128COMPARATIVE EXAMPLE 129COMPARATIVE EXAMPLE 130COMPARATIVE EXAMPLE 131COMPARATIVE EXAMPLE 132COMPARATIVE EXAMPLE 133COMPARATIVE EXAMPLE 134COMPARATIVE EXAMPLE 135CORE MATERIALRESINRESINRESINRESINRESINRESINRESINRESINRESINTHICKNESS OF SOLDER LAYER18 µm ON ONE SIDE18 µm ON ONE SIDE18 µm ON ONE SIDE38 µm ON ONE SIDE38 µm ON ONE SIDE38 µm ON ONE SIDE1 µm ON ONE SIDE1 µm ON ONE SIDE1 µm ON ONE SIDECOMPOSITION OF SOLDER LAYERSnAgSnAgSnAgSnAgSnAgSnAgSnAgSnAgSnAgTHICKNESS OF Sn LAYER (µm)00.031000.031500.0020.5Sn LAYER: SOLDER LAYER0.0000.16755.5560.0000.07939.4740.0000.20050.0000:100LESS THAN LOWER LIMIT VALUEEXCEEDING UPPER LIMIT VALUE0:100LESS THAN LOWER LIMIT VALUEEXCEEDING UPPER LIMIT VALUE0:100LESS THAN LOWER LIMIT VALUEEXCEEDING UPPER LIMIT VALUEYELLOWNESS××○××○××○DEFECT AT THE TIME OF BONDING○○×○○×○○× [Table 31] EXAMPLE 136EXAMPLE 137EXAMPLE 138EXAMPLE 139EXAMPLE 140EXAMPLE 141EXAMPLE 142EXAMPLE 143EXAMPLE 144CORE MATERIALRESINRESINRESINRESINRESINRESINRESINRESINRESINTHICKNESS OF SOLDER LAYER18 µm ON ONE SIDE18 µm ON ONE SIDE18 µm ON ONE SIDE38 µm ON ONE SIDE38 µm ON ONE SIDE38 µm ON ONE SIDE1 µm ON ONE SIDE1 µm ON ONE SIDE1 µm ON ONE SIDECOMPOSITION OF SOLDER LAYERSnSbSnSbSnSbSnSbSnSbSnSbSnSbSnSbSnSbTHICKNESS OF Sn LAYER (µm)0.10.560.10.5120.10.230.36Sn LAYER: SOLDER LAYER0.5562.77833.3330.2631.31631.57910.00023.00036.000YELLOWNESS○○○○○○○○○DEFECT AT THE TIME OF BONDING○○○○○○○○○ [Table 32] COMPARATIVE EXAMPLE 136COMPARATIVE EXAMPLE 137COMPARATIVE EXAMPLE 138COMPARATIVE EXAMPLE 139COMPARATIVE EXAMPLE 140COMPARATIVE EXAMPLE 141COMPARATIVE EXAMPLE 142COMPARATIVE EXAMPLE 143COMPARATIVE EXAMPLE 144CORE MATERIALRESINRESINRESINRESINRESINRESINRESINRESINRESINTHICKNESS OF SOLDER LAYER18 µm ON ONE SIDE18 µm ON ONE SIDE18 µm ON ONE SIDE38 µm ON ONE SIDE38 µm ON ONE SIDE38 µm ON ONE SIDE1 µm ON ONE SIDE1 µm ON ONE SIDE1 µm ON ONE SIDECOMPOSITION OF SOLDER LAYERSnSbSnSbSnSbSnSbSnSbSnSbSnSbSnSbSnSbTHICKNESS OF Sn LAYER (µm)00.031000.031500.0020.5Sn LAYER: SOLDER LAYER0.0000.16755.5560.0000.07939.4740.0000.20050.0000:100LESS THAN LOWER LIMIT VALUEEXCEEDING UPPER LIMIT VALUE0:100LESS THAN LOWER LIMIT VALUEEXCEEDING UPPER LIMIT VALUE0:100LESS THAN LOWER LIMIT VALUEEXCEEDING UPPER LIMIT VALUEYELLOWNESS××○××○××○DEFECT AT THE TIME OF BONDING○○×○○×○○× [Table 33] EXAMPLE 145EXAMPLE 146EXAMPLE 147EXAMPLE 148EXAMPLE 149EXAMPLE 150EXAMPLE 151EXAMPLE 152EXAMPLE 153CORE MATERIALRESINRESINRESINRESINRESINRESINRESINRESINRESINTHICKNESS OF SOLDER LAYER18 µm ON ONE SIDE18 µm ON ONE SIDE18 µm ON ONE SIDE38 µm ON ONE SIDE38 µm ON ONE SIDE38 µm ON ONE SIDE1 µm ON ONE SIDE1 µm ON ONE SIDE1 µm ON ONE SIDECOMPOSITION OF SOLDER LAYERSnInSnInSnInSnInSnInSnInSnInSnInSnInTHICKNESS OF Sn LAYER (µm)0.10.560.10.5120.10.230.36Sn LAYER: SOLDER LAYER0.5562.77833.3330.2631.31631.57910.00023.00036.000YELLOWNESS○○○○○○○○○DEFECT AT THE TIME OF BONDING○○○○○○○○○ [Table 34] COMPARATIVE EXAMPLE 145COMPARATIVE EXAMPLE 146COMPARATIVE EXAMPLE 147COMPARATIVE EXAMPLE 148COMPARATIVE EXAMPLE 149COMPARATIVE EXAMPLE 150COMPARATIVE EXAMPLE 151COMPARATIVE EXAMPLE 152COMPARATIVE EXAMPLE 153CORE MATERIALRESINRESINRESINRESINRESINRESINRESINRESINRESINTHICKNESS OF SOLDER LAYER18 µm ON ONE SIDE18 µm ON ONE SIDE18 µm ON ONE SIDE38 µm ON ONE SIDE38 µm ON ONE SIDE38 µm ON ONE SIDE1 µm ON ONE SIDE1 µm ON ONE SIDE1 µm ON ONE SIDECOMPOSITION OF SOLDER LAYERSnInSnInSnInSnInSnInSnInSnInSnInSnInTHICKNESS OF Sn LAYER (µm)00.031000.031500.0020.5Sn LAYER: SOLDER LAYER0.0000.16755.5560.0000.07939.4740.0000.20050.0000:100LESS THAN LOWER LIMIT VALUEEXCEEDING UPPER LIMIT VALUE0:100LESS THAN LOWER LIMIT VALUEEXCEEDING UPPER LIMIT VALUE0:100LESS THAN LOWER LIMIT VALUEEXCEEDING UPPER LIMIT VALUEYELLOWNESS××○××○××○DEFECT AT THE TIME OF BONDING○○×○○×○○× [Table 35] EXAMPLE 154EXAMPLE 155EXAMPLE 156EXAMPLE 157EXAMPLE 158EXAMPLE 159EXAMPLE 160EXAMPLE 161EXAMPLE 162CORE MATERIALRESINRESINRESINRESINRESINRESINRESINRESINRESINTHICKNESS OF SOLDER LAYER18 µm ON ONE SIDE18 µm ON ONE SIDE18 µm ON ONE SIDE38 µm ON ONE SIDE38 µm ON ONE SIDE38 µm ON ONE SIDE1 µm ON ONE SIDE1 µm ON ONE SIDE1 µm ON ONE SIDECOMPOSITION OF SOLDER LAYERSnPbSnPbSnPbSnPbSnPbSnPbSnPbSnPbSnPbTHICKNESS OF Sn LAYER (µm)0.10.560.10.5120.10.230.36Sn LAYER: SOLDER LAYER0.5562.77833.3330.2631.31631.57910.00023.00036.000YELLOWNESS○○○○○○○○○DEFECT AT THE TIME OF BONDING○○○○○○○○○ [Table 36] COMPARATIVE EXAMPLE 154COMPARATIVE EXAMPLE 155COMPARATIVE EXAMPLE 156COMPARATIVE EXAMPLE 157COMPARATIVE EXAMPLE 158COMPARATIVE EXAMPLE 159COMPARATIVE EXAMPLE 160COMPARATIVE EXAMPLE 161COMPARATIVE EXAMPLE 162CORE MATERIALRESINRESINRESINRESINRESINRESINRESINRESINRESINTHICKNESS OF SOLDER LAYER18 µm ON ONE SIDE18 µm ON ONE SIDE18 µm ON ONE SIDE38 µm ON ONE SIDE38 µm ON ONE SIDE38 µm ON ONE SIDE1 µm ON ONE SIDE1 µm ON ONE SIDE1 µm ON ONE SIDECOMPOSITION OF SOLDER LAYERSnPbSnPbSnPbSnPbSnPbSnPbSnPbSnPbSnPbTHICKNESS OF Sn LAYER (µm)00.031000.031500.0020.5Sn LAYER: SOLDER LAYER0.0000.16755.5560.0000.07939.4740.0000.20050.0000:100LESS THAN LOWER LIMIT VALUEEXCEEDING UPPER LIMIT VALUE0:100LESS THAN LOWER LIMIT VALUEEXCEEDING UPPER LIMIT VALUE0:100LESS THAN LOWER LIMIT VALUEEXCEEDING UPPER LIMIT VALUEYELLOWNESS××○××○××○DEFECT AT THE TIME OF BONDING○○×○○×○○×

[0061] The present embodiment also provides a method for forming a bump electrode, the method including the steps of: mounting a core material on an electrode; and forming the bump electrode by heating the mounted core material.

[0062] The shape of the core material also includes not only a spherical body but also a columnar column and a sheet and the like. For example, a core column in which a Ni base plating layer and Co base plating layer and the like of 1 to 4 µm on one side are provided on the surface of a Cu column having diameters of top and bottom surfaces of 1 to 1000 µm and a height of 1 to 3000 µm, and in the same condition as that of Examples, the Cu column is covered with a solder plating layer can provide the same effects as those in Examples described above, and good results could be obtained in each of yellowness and a defect at the time of bonding.

[0063] As an example, the results of using an aspect in which a column having a diameter φ of 0.30 mm and a height of 0.53 mm is used and the Ni plating thickness is 2 µm on one side are shown below. The thickness of the solder layer is a value not including the Ni plating thickness. [Table 37]EXAMPLE 163EXAMPLE 164EXAMPLE 165EXAMPLE 166EXAMPLE 167EXAMPLE 168EXAMPLE 169EXAMPLE 170EXAMPLE 171CORE MATERIALCOPPERCOPPERCOPPERCOPPERCOPPERCOPPERCOPPERCOPPERCOPPERTHICKNESS OF SOLDER LAYER5.5 µm ON ONE SIDE5.5 µm ON ONE SIDE5.5 µm ON ONE SIDE38 µm ON ONE SIDE38 µm ON ONE SIDE38 µm ON ONE SIDE1 µm ON ONE SIDE1 µm ON ONE SIDE1 µm ON ONE SIDECOMPOSITION OF SOLDER LAYERSAC305SAC305SAC305SAC305SAC305SAC305SAC305SAC305SAC305THICKNESS OF Sn LAYER (µm)0.10.51.80.10.5120.10.230.36Sn LAYER: SOLDER LAYER1.8189.09132.7270.2631.31631.57910.00023.00036.000YELLOWNESS○○○○○○○○○DEFECT AT THE TIME OF BONDING○○○○○○○○○ [Table 38] COMPARATIVE EXAMPLE 163COMPARATIVE EXAMPLE 164COMPARATIVE EXAMPLE 165COMPARATIVE EXAMPLE 166COMPARATIVE EXAMPLE 167COMPARATIVE EXAMPLE 168COMPARATIVE EXAMPLE 169COMPARATIVE EXAMPLE 170COMPARATIVE EXAMPLE 171CORE MATERIALCOPPERCOPPERCOPPERCOPPERCOPPERCOPPERCOPPERCOPPERCOPPERTHICKNESS OF SOLDER LAYER5.5 µm ON ONE SIDE5.5 µm ON ONE SIDE5.5 µm ON ONE SIDE38 µm ON ONE SIDE38 µm ON ONE SIDE38 µm ON ONE SIDE1 µm ON ONE SIDE1 µm ON ONE SIDE1 µm ON ONE SIDECOMPOSITION OF SOLDER LAYERSAC305SAC305SAC305SAC305SAC305SAC305SAC305SAC305SAC305THICKNESS OF Sn LAYER (µm)00.012.500.031500.0020.5Sn LAYER: SOLDER LAYER0.0000.18245.4550.0000.07939.4740.0000.20050.0000:100LESS THAN LOWER LIMIT VALUEEXCEEDING UPPER LIMIT VALUE0:100LESS THAN LOWER LIMIT VALUEEXCEEDING UPPER LIMIT VALUE0:100LESS THAN LOWER LIMIT VALUEEXCEEDING UPPER LIMIT VALUEYELLOWNESS××○××○××○DEFECT AT THE TIME OF BONDING○○×○○×○○×

[0064] The description of the embodiments, the description of Examples, and the disclosure of the drawings described above are merely examples for describing the invention described in claims. The invention described in claims is not limited by the description of the embodiments or the disclosure of the drawings described above.[Explanation of Reference]

[0065] 10Cu core ball 12Core 14Base plating layer 16Solder plating layer (solder layer) 20Sn plating layer (Sn layer)

Claims

1. A core material comprising: a core; a solder layer provided outside the core and being a Sn-based solder alloy consisting of Sn and at least any one element of Ag, Cu, Sb, Ni, Co, Ge, Ga, Fe, Al, In, Cd, Zn, Pb, Au, P, S, Si, Ti, Mg, Pd, and Pt; and a Sn layer provided outside the solder layer, wherein the solder layer has a thickness of 1 µm or more on one side, the Sn layer has a thickness of 0.1 µm or more on one side, and a thickness of the Sn layer is 0.215% or more and 36% or less of the thickness of the solder layer.

2. The core material according to claim 1, wherein the solder layer is a (Sn-Ag-Cu)-based solder.

3. The core material according to claim 1 or 2, further comprising a base plating layer made of any one of Ni, Co, Ni-Co, Ni-P and Ni-B between the core and the solder layer.

4. The core material according to any one of claims 1 to 3, wherein Cu ball or Cu column is used as the core.

5. Use of the core material according to any one of claims 1 to 4 for an electronic component as a solder bump.

6. A method for forming bump electrode comprising steps of: mounting the core material according to any one of claims 1 to 4 on an electrode; forming a bump electrode by heating the mounted core material.