Circuit member with bump, method for manufacturing circuit member with bump, connection structure, and method for manufacturing connection structure

Abstract

To provide a circuit member with a bump capable of enhancing both conduction reliability and insulation reliability, a method for manufacturing a circuit member with a bump, a connection structure, and a method for manufacturing a connection structure.SOLUTION: A circuit member with a bump 1 includes a substrate 2, an electrode 3 disposed on one plane of the substrate 2, and a bump 4 disposed on the electrode 3, the bump 4 includes conductive particles 11, and a foundation layer 5 containing tin or tin alloy to electrically connect the conductive particle 11 and the electrode 3 with a least a portion of the conductive particle 11 covered, and the foundation layer 5 is configured to include an alloy layer 5A with metal constituting the electrode 3 and a eutectic solder layer 5B.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present disclosure relates to a circuit member with bumps, a method for manufacturing a circuit member with bumps, a connection structure, and a method for manufacturing a connection structure. [Background technology]

[0002] In recent years, with the trend toward higher definition electronic devices, the pitch and area of ​​bumps in circuit components used in electronic devices are becoming narrower. This has led to a technical problem that conductive particles used in the circuit components may flow out between electrodes and cause short circuits.

[0003] To address these technical issues, a method has been proposed that uses composite particles in which a plurality of insulating particles are attached to the surface of a conductive particle. For example, in the methods described in Patent Documents 1 and 2, spherical resin particles are attached to the surface of a conductive particle. In Patent Document 3, first insulating particles and second insulating particles having a lower glass transition temperature than the first insulating particles are attached to the surface of a conductive particle. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 4773685 [Patent Document 2] Patent No. 3869785 [Patent Document 3] JP 2014-17213 A Summary of the Invention [Problem to be solved by the invention]

[0005] In the current situation where the size of electrodes of circuit members that are electrically connected to each other is becoming increasingly smaller, there is a demand for technology that can further improve both the electrical continuity reliability and the insulation reliability.

[0006] The present disclosure has been made to solve the above-mentioned problems, and aims to provide a bumped circuit member, a method for manufacturing a bumped circuit member, a connection structure, and a method for manufacturing a connection structure that can further improve both conductivity reliability and insulation reliability. [Means for solving the problem]

[0007] A bumped circuit member according to one aspect of the present disclosure comprises a substrate, an electrode provided on one side of the substrate, and a bump provided on the electrode, the bump having conductive particles and a base layer containing tin or a tin alloy and electrically connecting the conductive particles and the electrode while covering at least a portion of the conductive particles, the base layer being configured to include an alloy layer with a metal constituting the electrode and a eutectic solder layer.

[0008] In this circuit member with bumps, bumps containing tin or a tin alloy are provided on the electrodes, and the bumps are electrically connected to the electrodes through a base layer including an alloy layer with the metal constituting the electrodes and a eutectic solder layer. According to this circuit member with bumps, the presence of the eutectic solder layer in the base layer allows the conductive particles to be firmly crushed between the electrodes when the circuit member with bumps is connected to another circuit member, and the solder spreads sufficiently. Therefore, the reliability of conduction can be improved. In addition, in this circuit member with bumps, since the conductive particles are bonded to the electrodes by the base layer, the conductive particles can be prevented from flowing into the space between the electrodes when the circuit member with bumps is connected to another circuit member. Therefore, the reliability of insulation can also be improved.

[0009] The conductive particles may have a portion that directly contacts the electrode without the base layer in between. In this case, the conductive particles are firmly supported by the base layer, so that the electrical conductivity reliability and the insulating reliability can be more reliably improved.

[0010] The effective amount of the eutectic solder layer in the base layer may be 5% to 95%. By making the effective amount of the eutectic solder layer in the base layer 5% or more, the conductive particles can be sufficiently deformed together with the base layer when connecting a circuit member with bumps to another circuit member. This reduces the connection resistance and stabilizes the resistance value. By making the effective amount of the eutectic solder layer in the base layer 95% or less, the bonding strength of the conductive particles to the electrodes can be sufficiently ensured. This improves the stability of the connection.

[0011] The conductive particles have a base particle and a metal layer covering the base particle, and the melting point of the metal constituting the metal layer may be higher than the melting point of tin or a tin alloy. In this case, the melting of the metal layer can be suppressed when the conductive particles are bonded to the electrode. Therefore, the conductive particles and the electrode can be firmly bonded by the solder layer melted at a predetermined position on the surface of the electrode, while the state in which the metal layer covers the base particle is sufficiently maintained, and excellent connection reliability can be obtained when the circuit member with bumps is connected to another circuit member.

[0012] A method for manufacturing a circuit member with bumps according to one aspect of the present disclosure includes a preparation step of preparing a circuit member having an electrode on one side of a substrate and conductive particles at least partially covered with a solder layer containing tin or a tin alloy, and a formation step of forming bumps made of the conductive particles on the electrode, in which the formation step joins the conductive particles to the electrode at a temperature below the melting point of the tin or tin alloy, and forms a base layer including an alloy layer with a metal constituting the electrode and a eutectic solder layer, thereby electrically connecting the conductive particles and the electrode.

[0013] In this method for manufacturing a circuit member with bumps, conductive particles are bonded to electrodes at a temperature below the melting point of tin or a tin alloy, and a base layer is formed that includes an alloy layer with the metal constituting the electrode and a eutectic solder layer. According to the circuit member with bumps obtained by this method for manufacturing a circuit member with bumps, the presence of a eutectic solder layer in the base layer allows the conductive particles to be firmly crushed between the electrodes when the circuit member with bumps is connected to another circuit member, and the solder spreads sufficiently. Therefore, the reliability of conduction can be improved. In addition, since the conductive particles are bonded to the electrodes by the base layer, the conductive particles can be prevented from flowing into the space between the electrodes when the resulting circuit member with bumps is connected to another circuit member. Therefore, the reliability of insulation can also be improved.

[0014] A connection structure according to one aspect of the present disclosure is a connection structure in which a first circuit member constituted by the above-mentioned circuit member with bumps and a second circuit member having electrodes corresponding to the electrodes of the first circuit member are electrically connected via bumps, the bumps having conductive particles and a base layer containing tin or a tin alloy and electrically connecting the conductive particles to the electrodes of the first circuit member while covering at least a portion of the conductive particles, and the base layer is constituted by including an alloy layer with a metal constituting the electrode and a eutectic solder layer.

[0015] In this connection structure, the presence of a eutectic solder layer in the base layer of the first circuit member allows the conductive particles to be firmly crushed between the electrodes, and the solder to spread sufficiently. This improves the reliability of electrical continuity. In addition, in this connection structure, the conductive particles are bonded to the electrodes by the base layer, so that when the circuit member with bumps is connected to another circuit member, the conductive particles are prevented from flowing into the space between the electrodes. This also makes it possible to improve the reliability of insulation.

[0016] A method for manufacturing a connection structure according to one aspect of the present disclosure includes a preparation step of preparing the above-mentioned circuit member with bumps as a first circuit member and preparing a second circuit member having electrodes corresponding to the electrodes of the first circuit member, and a connection step of facing the electrodes of the second circuit member to the bumps of the first circuit member and electrically connecting the conductive particles to the electrodes of the second circuit member by heating the conductive particles to a temperature higher than the melting point of tin or a tin alloy.

[0017] In this method for manufacturing a connection structure, the presence of a eutectic solder layer in the base layer of the first circuit member allows the conductive particles to be firmly crushed between the electrodes, and the solder spreads sufficiently. This improves the reliability of electrical continuity. In addition, in this method for manufacturing a connection structure, the base layer bonds the conductive particles to the electrodes, preventing the conductive particles from flowing into the space between the electrodes. This also makes it possible to improve the reliability of insulation. Effect of the Invention

[0018] According to the present disclosure, it is possible to further improve both the electrical continuity reliability and the insulation reliability. [Brief description of the drawings]

[0019] [Figure 1] 1 is a schematic cross-sectional view showing a bumped circuit member according to an embodiment of the present disclosure. [Diagram 2] 2A is a schematic cross-sectional view showing an example of a conductive particle used in the circuit member with bumps shown in FIG. 1, and FIG. 2B is a schematic cross-sectional view showing another example of the conductive particle. [Diagram 3] FIG. 1A is a schematic cross-sectional view showing a preparatory step of a method for manufacturing a circuit member with bumps according to one embodiment of the present disclosure, FIG. 1B is a schematic cross-sectional view showing a step subsequent to (a), and FIG. 1C is a schematic cross-sectional view showing a step subsequent to (a). [Figure 4] FIG. 2A is a schematic cross-sectional view showing a forming step in a method for producing a circuit member with bumps according to an embodiment of the present disclosure, and FIG. 2B is a schematic cross-sectional view showing a step subsequent to that in FIG. [Diagram 5] 1 is a schematic cross-sectional view showing a connection structure according to an embodiment of the present disclosure. [Figure 6] FIG. 2A is a schematic cross-sectional view showing an insulation step of a method for manufacturing a connection structure according to an embodiment of the present disclosure, and FIG. 2B is a schematic cross-sectional view showing a step subsequent to (a). [Figure 7] FIG. 2A is a schematic cross-sectional view showing a preparation step of a method for manufacturing a connection structure according to an embodiment of the present disclosure, and FIG. 2B is a schematic cross-sectional view showing a connection step following the preparation step. [Figure 8] FIG. 13 is a diagram showing the results of a conduction reliability test of a circuit member with bumps according to the present disclosure. [Figure 9] FIG. 13 is a diagram showing the results of an insulation reliability test of a circuit member with bumps according to the present disclosure. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0020] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, preferred embodiments of a circuit member with bumps, a method for manufacturing a circuit member with bumps, a connection structure, and a method for manufacturing a connection structure according to one aspect of the present disclosure will be described in detail with reference to the drawings.

[0021] Unless otherwise specified, the materials exemplified in the following description may be used alone or in combination of two or more. When a plurality of substances corresponding to each component are present in the composition, the content of each component in the composition means the total amount of the plurality of substances present in the composition, unless otherwise specified. A numerical range indicated using "~" indicates a range including the numerical values ​​described before and after "~" as the minimum and maximum values, respectively. In the numerical ranges described in stages in this specification, the upper limit or lower limit of a numerical range of a certain stage may be replaced with the upper limit or lower limit of a numerical range of another stage.

[0022] Fig. 1 is a schematic cross-sectional view showing a circuit member with bumps according to an embodiment of the present disclosure. As shown in the figure, the circuit member with bumps 1 includes a substrate 2, an electrode 3 provided on one surface 2a of the substrate 2, and a bump 4 provided on the electrode 3. The circuit member with bumps 1 is formed by bonding a metal layer 13 and a solder layer 14 (see Fig. 2(a) or Fig. 2(b)) of conductive particles 11 constituting the bump 4 to the electrode 3. Although Fig. 1 shows one electrode 3 and bump 4, in an actual circuit member with bumps 1, a plurality of electrodes 3 and bumps 4 are arranged in a lattice pattern at a predetermined pitch on one surface 2a of the substrate 2.

[0023] The electrodes 3 are formed in a predetermined pattern on one surface 2a of the substrate 2 by using a technique such as electroless plating, electrolytic plating, or sputtering. Examples of materials constituting the electrodes 3 include copper, copper / nickel, copper / nickel / gold, copper / nickel / palladium, copper / nickel / palladium / gold, copper / nickel / gold, copper / palladium, copper / palladium / gold, copper / tin, copper / silver, and indium tin oxide.

[0024] The bump 4 is formed using conductive particles 11. As shown in FIG. 2(a), the conductive particles 11 include a base particle 12, a metal layer 13 covering the base particle 12, and a solder layer 14 covering at least a part of the metal layer 13. In the example of FIG. 2(a), the conductive particles 11 are spherical, but are not limited to being perfectly spherical, and may also be ellipsoids or any solid of revolution of a plane curve. In this case, the aspect ratio of the conductive particles 11 (the ratio of the length in the major axis direction to the length in the minor axis direction) may be 0.5 or more, or may be 0.8 or more.

[0025] The particle size of the conductive particles 11 may be, for example, 2.3 μm to 25 μm, 3 μm to 20 μm, or 3.5 μm to 10 μm. If the particle size of the conductive particles 11 is 2.3 μm or more, the conductive particles 11 tend to be able to sufficiently absorb the impact even if the conductive particles 11 are subjected to an impact. If the particle size of the conductive particles 11 is 25 μm or less, the variation in the particle size of the conductive particles 11 can be sufficiently reduced, making it easier to achieve both electrical continuity reliability and insulation reliability. The particle size of the conductive particles 11 can be measured by observation using a scanning electron microscope (hereinafter, SEM). The average particle size of the conductive particles 11 can be calculated by measuring the particle size of, for example, 300 arbitrary particles by observation using SEM and averaging the measured values.

[0026] The base particle 12 is spherical and made of a non-conductive material. The particle size of the base particle 12 may be, for example, 1.5 μm to 10 μm, or 2 μm to 10 μm. If the particle size of the base particle 12 is 1.5 μm or more, the base particle 12 tends to be able to sufficiently absorb the impact even if the conductive particle 11 is subjected to an impact. If the particle size of the base particle 12 is 10 μm or less, the variation in particle size of the base particle 12 can be sufficiently reduced. The particle size of the base particle 12 can be measured by observation using a SEM, as with the conductive particle 11. The average particle size of the base particle 12 can be calculated by measuring the particle size of 300 arbitrary base particles by observation using a SEM and averaging the measured values.

[0027] The material of the base particle 12 is not particularly limited, but may be resin or silica. Specific examples include acrylic resins such as polymethyl methacrylate and polymethyl acrylate; polyolefin resins such as polyethylene, polypropylene, polyisobutylene, and polybutadiene; glass; and silica. When resin particles are used as the base particle 12, crosslinked acrylic particles, crosslinked polystyrene particles, etc. may be used.

[0028] Assuming that reflow connection is performed using solder, the glass transition point (Tg) of the base particle 12 is preferably higher than the melting point of the solder. Taking the commonly used Sn-3 mass % Ag-0.5 mass % Cu as an example, its melting point is 217 to 219°C. For this reason, a material with a Tg of, for example, 220°C or higher may be used as the base particle 12. By using such a material, if the temperature at which the solder layer 14 is joined is lower than the Tg of the base particle 12, deformation of the base particle 12 is sufficiently suppressed. Therefore, the base particle 12 exhibits excellent dimensional stability, and good connection reliability and insulation reliability are achieved.

[0029] The metal layer 13 is, for example, a layer containing nickel or a nickel alloy. The nickel content of the metal layer 13 may be, for example, 85% by mass to 98% by mass, 87% by mass to 96% by mass, or 90% by mass to 95% by mass. If the nickel content is 85% by mass to 98% by mass, the metal layer 13 is likely to remain stable even after the solder layer 14 described below is bonded to the electrode 3, and high connection reliability can be maintained. The metal layer 13 does not necessarily need to cover the entire surface of the base particle 12. The metal layer 13 may cover 80% or more, more preferably 90% or more, of the surface of the base particle 12.

[0030] The thickness of the metal layer 13 may be, for example, 0.05 μm to 5 μm, 0.1 μm to 3 μm, or 0.2 μm to 2 μm. If the thickness of the metal layer 13 is 0.05 μm or more, the metal layer 13 is likely to remain stable even after the solder layer 14 is bonded to the electrode 3, and high connection reliability can be maintained. The metal layer 13 may contain at least one of phosphorus and boron, and may particularly contain phosphorus. In this case, when the solder layer 14 is bonded to the electrode 3, it is possible to suppress the nickel contained in the metal layer 13 from diffusing into the tin or tin alloy contained in the solder layer 14. This makes it possible to suppress a decrease in the thickness of the metal layer 13.

[0031] The metal layer 13 can be formed by, for example, electroless nickel plating. In this case, for example, the surface of the base particle 12 may be subjected to palladium catalysis treatment, and then electroless nickel plating may be performed. More preferably, phosphorus-containing compounds such as sodium hypophosphite may be used as a reducing agent to codeposit phosphorus, and a metal layer 13 containing an alloy containing nickel and phosphorus (nickel-phosphorus alloy) may be formed. Boron may be codeposit by using a boron-containing compound such as dimethylamine borane, sodium borohydride, potassium borohydride, and the like as a reducing agent to codeposit boron, and a metal layer 13 containing an alloy containing nickel and boron (nickel-boron alloy) may be formed.

[0032] The melting point of the metal constituting the metal layer 13 may be higher than the melting point of tin or a tin alloy (the melting point of the solder layer 14). In this case, melting of the metal layer 13 can be suppressed when the conductive particles 11 are joined to the electrode 3. Therefore, the conductive particles 11 and the electrode 3 can be firmly joined by the solder layer 14, while the state in which the metal layer 13 covers the base particle 12 is sufficiently maintained, and excellent connection reliability can be obtained.

[0033] The solder layer 14 is a layer containing tin or a tin alloy. Examples of tin alloys constituting the solder layer 14 include In-Sn, In-Sn-Ag, Sn-Bi, Sn-Bi-Ag, Sn-Ag-Cu, and Sn-Cu. Specific examples are given below. In-Sn (In 52% by mass, Bi 48% by mass, melting point 118°C) ·In-Sn-Ag (In20% by mass, Sn77.2% by mass, Ag2.8% by mass, melting point 175℃) Sn-Bi (Sn 43% by mass, Bi 57% by mass, melting point 138°C) Sn-Bi-Ag (Sn 42% by mass, Bi 57% by mass, Ag 1% by mass, melting point 139°C) ·Sn-Ag-Cu (Sn96.5% by mass, Ag3% by mass, Cu0.5% by mass, melting point 217℃) Sn-Cu (Sn 99.3% by mass, Cu 0.7% by mass, melting point 227°C)

[0034] The tin alloy is selected according to the connection temperature. When an In-Sn alloy or an Sn-Bi alloy is selected, connection can be made at a low temperature of 150°C or less. When a material with a high melting point such as Sn-Ag-Cu or Sn-Cu is used, high reliability tends to be achieved even when the circuit member 1 with bumps is left at high temperatures. The solder layer 14 may contain, in addition to tin or a tin alloy, trace amounts of metals such as Ni, Mn, Sb, Al, and Zn as necessary.

[0035] The solder layer 14 may cover, for example, 20% to 60% or 30% to 50% of the surface of the metal layer 13. The thickness (thickest part) of the solder layer 14 may be, for example, 0.03 μm to 3 μm, 0.05 μm to 2 μm, or 0.1 μm to 1 μm. If the thickness of the solder layer 14 is 0.03 μm or more, high reliability can be achieved in the state where the solder layer 14 is bonded to the electrode 3. From the viewpoint of preventing the conductive particles 11 and the transfer mold 21 (see FIG. 3(a) and the like) from being connected by the solder layer 14 formed by sputtering, it is preferable that the upper limit of the thickness of the solder layer 14 is about 3 μm as described above.

[0036] The solder layer 14 may contain Ag, Cu, Ni, Bi, Zn, Pd, Pb, Au, P, B, or an alloy of two or more selected from these. The solder layer 14 may contain Ag or Cu. When the solder layer 14 contains Ag or Cu, the melting point of the solder layer 14 can be lowered to about 220°C. In addition, the bonding strength with the electrode 3 is improved, and good connection reliability can be obtained.

[0037] The Cu content of the solder layer 14 may be, for example, 0.05% by mass to 10% by mass, 0.1% by mass to 5% by mass, or 0.2% by mass to 3% by mass. If the Cu content is 0.05% by mass or more, good connection reliability is easily obtained. If the Cu content is 10% by mass or less, the melting point of the solder layer 14 is lowered and the wettability of the solder is improved. As a result, good connection reliability is easily obtained.

[0038] The Ag content of the solder layer 14 may be, for example, 0.05% by mass to 10% by mass, 0.1% by mass to 5% by mass, or 0.2% by mass to 3% by mass. If the Ag content is 0.05% by mass or more, good solder connection reliability is easily obtained. If the Ag content is 10% by mass or less, the melting point of the solder layer 14 is lowered and the wettability of the solder is improved. As a result, good connection reliability is easily obtained. When the solder layer 14 contains Ag, Ag3Sn is formed in the solder layer 14. The dispersion of Ag3Sn in the solder layer 14 improves the strength of the solder layer 14 against impact.

[0039] The solder layer 14 can be formed by, for example, sputtering. To form the solder layer 14 by sputtering, for example, a barrel-type sputtering device can be used. For example, when a cylindrical, oblique, polygonal, or other barrel sputtering device is used, agglomeration of particles tends to be suppressed. The solder layer 14 can be formed by deposition or ion plating, without being limited to sputtering.

[0040] Vapor deposition is a method of heating and evaporating a vapor deposition material under vacuum to deposit the vapor deposition material on the surface of an object. A vacuum vapor deposition apparatus includes, for example, a vacuum chamber. In the vacuum chamber, a container containing the vapor deposition material, a heating mechanism for heating the vapor deposition material in the container, a stage for placing the vapor deposition object, and the like are provided.

[0041] When multiple deposition materials are used, multiple containers and heating mechanisms may be provided. In this case, for example, two types of metals are placed in separate containers and heated and evaporated at the same time, so that an alloy or mixture of the two types of metals can be deposited on the deposition target. Since the deposition rate at the heating temperature differs depending on the type of deposition material, it is preferable that the heating mechanism can control the temperature of each container individually. This allows the ratio of the alloy and mixture deposited on the non-deposition target to be freely adjusted.

[0042] As the heating mechanism, various heating methods such as electric heating wire (resistance) heating, induction heating, radiation heating, and electron beam heating can be used. A mechanism for heating the object to be vapor-deposited may be provided. By heating the object to be vapor-deposited, it is possible to improve the adhesion between the vapor deposition material and the object to be vapor-deposited and to shape the deposition layer of the vapor deposition material (for example, flattening). In addition, a mechanism for rotating and swinging the object to be vapor-deposited may be provided. The rotation of the object to be vapor-deposited may be rotation on its axis or a combination of rotation and revolution. In this case, the deposition thickness of the vapor deposition material on the object to be vapor-deposited is made uniform. The positional relationship between the vapor deposition material container and the object to be vapor-deposited is not particularly limited, but by arranging them opposite to each other, more uniform film formation is possible. The position of the vapor deposition material container and the distance from the object to be vapor-deposited are appropriately adjusted depending on the vapor deposition material, the size of the object to be vapor-deposited, and the like.

[0043] In this embodiment, a mixed film layer of tin and bismuth was used as the solder layer 14. Tin and bismuth deposition materials were respectively contained in two containers (molybdenum boats) in the vacuum chamber. The two deposition materials were installed concentrically at a radius of 250 mm from the revolution axis of the substrate located at the center of the vacuum chamber, and a resistance heating mechanism was provided for each. The deposition target was fixed to a holder and rotated at a height of 1100 mm from the deposition material. The rotation and revolution referred to here means that the substrate rotates around the rotation axis while simultaneously revolving around the revolution axis.

[0044] A shielding mask was installed about 100 mm below the substrate. The shielding mask was machined into a pre-designed shape so that a film could be formed on the substrate with a uniform thickness. In addition, a film thickness monitor placed at the center of the revolution plane was used to monitor the film formation rate, and a mechanism was provided to control the current value of the resistance heating so that the film formation rate would be constant. The pressure inside the vacuum chamber during film formation was 5.0×10 -4 The vapor deposition pressure was set to 1 Pa, and the temperature of the object to be vapor-deposited was set to 50° C. Then, the conditions were adjusted so that the film formation ratio of tin and bismuth was 42:58, and a specified amount of a mixed film of tin and bismuth was formed on the surface of the object to be vapor-deposited.

[0045] Ion plating is a method of heating and evaporating the deposition material in the same way as the deposition method. In ion plating, the vapor of the deposition material is positively charged while a negative charge is applied to the target object, and the target object attracts the positively charged vapor of the deposition material, forming a film with good adhesion to the target object.

[0046] As shown in FIG. 2(b), the conductive particle 11 may have a configuration in which the metal layer 13 is covered with a surface layer 15. The surface layer 15 is, for example, a layer containing palladium or a palladium alloy. The surface layer 15 is formed, for example, through a plating process. The surface layer 15 may be an electroless plating type palladium layer. The electroless palladium plating may be either a substitution type (a type that does not contain a reducing agent) or a reduction type (a type that contains a reducing agent). Examples of electroless palladium plating include reduction type APP (Ishihara Chemical Industry Co., Ltd., product name) and replacement type MCA (World Metal Co., Ltd., product name). When comparing the substitution type and the reduction type, the reduction type tends to have fewer voids. Compared to the substitution type in which the metal inside is dissolved while being precipitated, the reduction type is easier to ensure a covering area.

[0047] The surface layer 15 may have a multi-layer structure. In this case, the surface layer 15 may be composed of a first palladium plating film provided on the outside of the metal layer 13 and a second palladium plating film provided on the outside of the first palladium plating film. The first palladium plating film is, for example, a displacement or electroless palladium plating film having a purity of 99% by mass or more. The second palladium plating film is, for example, an electroless palladium plating film having a purity of 90% by mass or more and less than 99% by mass.

[0048] When a substitutional or reduction-type electroless palladium plating coating having a purity of 99% by mass or more is formed alone as surface layer 15, the inclusion of Pd in ​​Sn-Cu-Ni compounds or Sn-Ni compounds has the effect of suppressing the growth of these compounds, but a reduction-type electroless palladium plating coating having a purity of 90% by mass or more but less than 99% by mass is more effective in suppressing the growth of these compounds.

[0049] On the other hand, when a reduced-type electroless palladium plating film having a purity of 90% by mass or more and less than 99% by mass is formed alone as the surface layer 15, the phosphorus content in the electroless palladium plating film can be increased, but it is difficult to deposit a film with a uniform thickness over the entire base particle 12 on which the metal layer 13 is formed. In this case, particles on which a phosphorus-containing film (electroless palladium-phosphorus film) is not formed, or particles on which the phosphorus-containing film is extremely thin, tend to be generated. This phenomenon tends to occur more easily as the particle size of the conductive particles 11 becomes smaller. As a result, when a reduced-type electroless palladium plating film having a purity of 90% by mass or more and less than 99% by mass is formed alone, the palladium-phosphorus alloy plating film may not function as a protective layer for the metal layer 13.

[0050] A displacement or reduction type electroless palladium plating coating with a purity of 99% by mass or more is more likely to deposit on the metal layer 13 than a reduction type electroless palladium plating coating with a purity of 90% by mass or more and less than 99% by mass, and deposition occurs with a sufficiently uniform thickness over the entire base particle 12 on whose surface the metal layer 13 is formed, and deposition occurs independently of the particle size of the base particle 12. After a displacement or reduction type electroless palladium plating coating with a purity of 99% by mass or more and less than 99% by mass is formed, deposition of a reduction type electroless palladium plating coating with a purity of 90% by mass or more and less than 99% by mass is more likely to occur on the surface, and deposition occurs independently of the particle size of the base particle 12.

[0051] For these reasons, as described above, surface layer 15 preferably has a first palladium plating coating provided on the outside of metal layer 13, and a second palladium plating coating (an electroless palladium plating coating having a purity of 90% by mass or more and less than 99% by mass) provided on the outside of the first palladium plating coating.

[0052] The surface layer 15 may disappear due to the diffusion of palladium into the solder layer 14 after the solder layer 14 is bonded to the electrode 3. In this case, the diffusion of palladium into the solder layer 14 forms a Sn-Cu-Ni-Pd compound or a Sn-Ni-Pd compound between the metal layer 13 and the solder layer 14. The Pd content in these compounds may be 0.01% by mass to 3% by mass, 0.02% by mass to 1% by mass, or 0.05% by mass to 0.5% by mass. If the Pd content of the above compounds is 0.01% by mass or more, the effect of suppressing the growth of Sn-Cu-Ni compounds or Sn-Ni compounds in a high-temperature environment of about 100° C. is easily obtained. If the Pd content of the above compounds is 3% by mass or less, the surface layer 15 diffuses into the solder layer 14, and drop impact resistance reliability is improved.

[0053] The surface layer 15 also functions as a layer that ensures the wetting and spreading of the solder layer 14. The thickness of the surface layer 15 may be, for example, 0.01 μm to 0.5 μm, 0.03 μm to 0.4 μm, or 0.05 μm to 0.3 μm. If the thickness of the surface layer 15 is 0.01 μm or more, the Pd content in the Sn-Cu-Ni-Pd compound or Sn-Ni-Pd compound is easily set to 0.01 mass % or more after the solder layer 14 is bonded to the electrode 3. As a result, the effect of suppressing the growth of the Sn-Cu-Ni compound or Sn-Ni compound in a high-temperature environment of about 100° C. is easily obtained. If the thickness of the surface layer 15 is 0.5 μm or less, the surface layer 15 diffuses into the solder layer 14, and drop impact resistance reliability is improved.

[0054] The bump 4 is bonded to the electrode 3 by heating and pressing the conductive particles 11 against the electrode 3. In a bonded state with the electrode 3, the bump 4 has a base layer 5 as shown in Fig. 1. The base layer 5 is formed by the above-mentioned solder layer 14 being deformed and altered during bonding with the electrode 3. In other words, the base layer 5 contains tin or a tin alloy, and electrically connects the conductive particles 11 to the electrode 3 while covering at least a portion of the conductive particles 11.

[0055] When the solder layer 14 and the electrode 3 are joined, the conductive particles 11 are joined to the electrode 3 at a temperature lower than the melting point of the tin or tin alloy contained in the solder layer 14. By setting the joining temperature to a temperature lower than the melting point of the tin or tin alloy contained in the solder layer 14, an alloy layer 5A with the metal constituting the electrode 3 and a eutectic solder layer 5B that originally constitutes the solder layer 14 coexist in the base layer 5. The alloy layer 5A is located in a portion of the base layer 5 closer to the electrode 3, and the eutectic solder layer 5B is located in a portion of the base layer 5 closer to the conductive particles 11. In this embodiment, the effective amount of the eutectic solder layer 5B in the base layer 5 is 5% to 95%.

[0056] 1, in the bump 4, the conductive particles 11 have a portion P that directly contacts the electrode 3 without the base layer 5. In the portion P, the metal layer 13 or the surface layer 15 of the conductive particles 11 is in contact with the surface of the electrode 3. The conductive particles 11 may be bonded to the electrode 3 via the base layer 5. In this case, the thickness of the base layer 5 between the conductive particles 11 and the electrode 3 can be adjusted by the temperature and pressure when bonding the conductive particles 11 of the electrode 3.

[0057] Next, a method for manufacturing the above-mentioned circuit member 1 with bumps will be described.

[0058] The manufacturing method of the circuit member 1 with bumps includes a preparation step of preparing a circuit member 25 (see Figure 4(a)) having an electrode 3 on one surface 2a of a substrate 2 and conductive particles 11 at least partially covered with a solder layer 14 containing tin or a tin alloy, and a formation step of forming a bump made of the conductive particles 11 on the electrode 3.

[0059] Here, in carrying out the preparation step and the formation step, a transfer mold 21 is used as shown in FIG. 3(a). The transfer mold 21 is formed in a sheet shape from inorganic materials such as silicon, various ceramics, glass, metals such as stainless steel, and organic materials such as various resins. The transfer mold 21 may be formed from a flexible resin material. One surface 21a of the transfer mold 21 is provided with a recess 22 holding the conductive particles 11. The recess 22 is formed by using a known method such as photolithography. The recess 22 is shaped such that the opening area expands from the bottom toward the opening.

[0060] Next, as shown in Fig. 3(b), the transfer mold 21 is placed facing the sputtering electrode 23. The sputtering electrode 23 is composed of a layer containing tin or a tin alloy. By sputtering using the sputtering electrode 23, a solder layer 14 is formed so as to cover a part of the metal layer 13 of the conductive particles 11. Note that a layer containing tin or a tin alloy is also formed on one surface 21a of the transfer mold 21 by sputtering.

[0061] After the solder layer 14 is formed, as shown in Fig. 4(a), a circuit member 25 having an electrode 3 on one surface 2a of the substrate 2 is prepared, and a transfer mold 21 is placed on the circuit member 25 so that the electrode 3 and the conductive particles 11 face each other. It is preferable to use a transfer mold 21 in a state in which the conductive particles 11 are still accommodated in the recesses 22 after the solder layer 14 is formed by sputtering. This makes it possible to improve the efficiency of the manufacturing process and easily make the thickest part of the solder layer 14 face the surface of the electrode 3.

[0062] Next, as shown in Fig. 4(b), the solder layer 14 is brought into contact with the surface of the electrode 3. Then, the conductive particles 11 are heated and pressurized at a temperature below the melting point of tin or a tin alloy to form a base layer 5 including an alloy layer 5A with the metal constituting the electrode 3 and a eutectic solder layer 5B. The conductive particles 11 and the electrode 3 are electrically connected by the base layer 5, and a bump 4 is formed on the electrode 3, thereby obtaining the circuit member 1 with bumps shown in Fig. 1. The reason why the conductive particles 11 and the electrode 3 are joined even at a temperature below the melting point of tin or a tin alloy is presumably due to slight mutual diffusion of metal elements between the tin or tin alloy and the metal constituting the electrode 3.

[0063] The lower limit of the heating temperature is appropriately set depending on the constituent material of the solder layer 14, but from the viewpoint of producing good bonding between the solder layer 14 and the electrode 3, when the melting point of tin or a tin alloy is Tc, the lower limit of the heating temperature may be (Tc-40)°C or more, or may be (Tc-20)°C or more. The lower limit of the heating temperature may be (Tc-15)°C or more, or may be (Tc-15)°C or more.

[0064] For example, when the tin alloy is a Sn-Bi alloy (melting point 138°C), the conductive particles 11 are heated to 125°C or higher and lower than 138°C, thereby forming the bump 4 on the electrode 3 while maintaining the eutectic state of the Sn-Bi alloy. The Sn-Bi alloy generally contains 42% by mass of Sn and 58% by mass of Bi. By heating within the above temperature range, the mass ratio Sn / Bi of Sn and Bi in the Sn-Bi alloy contained in the eutectic solder layer 5B can be set to 0.2 or higher. From the viewpoint of suppressing deformation of the bump 4, the mass ratio Sn / Bi may be 0.3 or higher, or may be 0.5 or higher.

[0065] The heating time is not particularly limited and can be adjusted as appropriate depending on the pressure conditions or heating atmosphere. As an example, the heating time can be 0.1 to 20 minutes. When the heating time is 0.1 minute or more, the conductive particles 11 and the electrodes 3 can be bonded more appropriately. When the heating time is 20 minutes or less, the eutectic solder layer 5B is easily maintained. From this viewpoint, the heating time may be 1 to 15 minutes, or 3 to 10 minutes.

[0066] The pressure is not particularly limited, but may be, for example, about 0.5 MPa to 100 MPa. By heating the conductive particles 11 and the electrode 3 while they are in contact with each other under pressure, the heating temperature can be set low, and a portion P (see FIG. 1) can be formed in the bump 4 where the conductive particles 11 are in direct contact with the electrode 3 without the base layer 5 therebetween. From this viewpoint, the pressure may be 0.7 MPa to 70 MPa, or 1.0 MPa to 50 MPa.

[0067] The conductive particles 11 may be heated and pressurized in a reducing atmosphere. By heating the conductive particles 11 at a temperature lower than the melting point of tin or a tin alloy and creating a reducing atmosphere, the oxide film on the surface of the solder layer 14 and the oxide film on the surface of the electrode 3 are reduced, making it easier to bond the conductive particles 11 and the electrode 3 better. Examples of reducing gases include hydrogen gas, hydrogen radicals, and formic acid gas.

[0068] Next, a connection structure using the circuit member 1 with bumps will be described.

[0069] FIG. 5 is a schematic cross-sectional view showing a connection structure according to an embodiment of the present disclosure. As shown in FIG. 5, the connection structure 31 is configured by electrically connecting a first circuit member 32A formed by the above-mentioned circuit member 1 with bumps and a second circuit member 32B having an electrode 34 corresponding to the electrode 3 of the first circuit member 32A via a bump 4. In the example of FIG. 5, the second circuit member 32B has a substrate 33 and an electrode 34 provided on one surface 33a of the substrate 33. In addition, an insulating resin layer 35 is provided between the first circuit member 32A and the second circuit member 32B so as to cover the electrodes 3, 34 and the bump 4. Since the conduction between the electrodes 3, 34 is ensured by the bump 4, it is not necessary to use an anisotropic conductive adhesive for the insulating resin layer 35, and an insulating resin material that does not contain conductive particles can be appropriately adopted.

[0070] The connection structure 31 can be applied to electronic devices such as liquid crystal displays, personal computers, mobile phones, smartphones, and tablets. One of the first circuit member 32A and the second circuit member 32B is, for example, a chip component such as an IC chip (semiconductor chip), a resistor chip, a capacitor chip, or a driver IC; a rigid package substrate. These circuit members generally have a large number of circuit electrodes. One of the first circuit member 32A and the second circuit member 32B is a wiring substrate such as a flexible tape substrate having metal wiring, a flexible printed wiring board, or a glass substrate on which indium tin oxide (ITO) or zinc oxide (IZO) is vapor-deposited.

[0071] Next, a method for manufacturing the above-mentioned connection structure 31 will be described.

[0072] A manufacturing method for the connection structure 31 includes a preparation step of preparing a bumped circuit member 1 as a first circuit member 32A and a second circuit member 32B having an electrode 34 corresponding to the electrode 3 of the first circuit member 32A, and a connection step of electrically connecting the conductive particles 11 and the electrode 34 of the second circuit member 32B by facing the electrode 34 of the second circuit member 32B to the bump 4 of the first circuit member 32A and heating the conductive particles 11 to a temperature higher than the melting point of tin or a tin alloy.

[0073] First, as shown in Fig. 6(a), a first circuit member 32A and an insulating resin film F made of an insulating resin material are prepared. Next, as shown in Fig. 6(b), the insulating resin film F is laminated onto one surface 2a of the substrate 2 of the first circuit member 32A. As a result, the electrodes 3 and bumps 4 of the first circuit member 32A are covered with the insulating resin film F. After laminating the insulating resin film F, as shown in Fig. 7(a), the second circuit member 32B is disposed relative to the first circuit member 32A so that the electrodes 34 face the bumps 4 of the first circuit member 32A.

[0074] After arranging the second circuit member 32B, as shown in Fig. 7(b), the conductive particles 11 are heated and pressurized at a temperature below the melting point of tin or a tin alloy, and the electrodes 34 of the second circuit member 32B are pressed toward the bumps 4. This electrically connects the conductive particles 11 and the electrodes 34 of the second circuit member 32B, and the connection structure 31 shown in Fig. 5 is obtained. When the insulating resin film F is made of a thermosetting resin, the thermosetting resin is cured as the conductive particles 11 are heated and pressurized, and an insulating resin layer 35 is formed.

[0075] As described above, in the circuit member 1 with bumps according to this embodiment, the bumps 4 containing tin or a tin alloy are provided on the electrodes 3, and the bumps 4 are electrically connected to the electrodes 3 through the base layer 5 including the alloy layer 5A with the metal constituting the electrodes 3 and the eutectic solder layer 5B. According to this configuration, the presence of the eutectic solder layer 5B in the base layer 5 allows the conductive particles 11 to be firmly crushed between the electrodes when the circuit member 1 with bumps is connected to another circuit member, and the solder spreads sufficiently. Therefore, the reliability of conduction can be improved. In addition, in the circuit member 1 with bumps, the conductive particles 11 are bonded to the electrodes 3 through the base layer 5, so that the conductive particles 11 can be prevented from flowing into the space between the electrodes when the circuit member 1 with bumps is connected to another circuit member. Therefore, the reliability of insulation can also be improved.

[0076] In this embodiment, the conductive particles 11 have a portion P that directly contacts the electrode 3 without the base layer 5. In this case, the conductive particles 11 are firmly supported by the base layer 5, so that the electrical conductivity reliability and the insulating reliability can be more reliably improved.

[0077] When the effective amount of the eutectic solder layer 5B in the base layer 5 is less than 5%, it means that most of the base layer 5 is formed of an alloy having a melting point higher than that of the solder layer 14. In this case, when the bump 4 of the circuit member 1 with bumps is connected to the electrode of another circuit member, the base layer 5 is hardly deformed, and it is considered that the deformation of the conductive particles 11, which are components of the bump 4, is hindered. If the deformation of the conductive particles 11 is hindered, the contact area between the conductive particles 11 and the electrode of the other circuit member becomes insufficient, and the connection resistance may increase. In addition, when an attempt is made to reduce the distance between the circuit member 1 with bumps and the other circuit member in order to stabilize the resistance value, it is considered that only the conductive particles 11 will try to deform and the conductive particles 11 will be damaged, even though the base layer 5 does not deform.

[0078] In addition, when forming the circuit member 1 with bumps, the conductive particles 11 having the solder layer 14 are pressed against the electrode 3, but generally, the pressing force at this time is greater than the pressing force when the conductive particles 11 of the circuit member 1 with bumps are pressed against the electrode of another circuit member. The shape of the base layer 5 that joins the electrode 3 of the circuit member 1 with bumps and the conductive particles 11 is shaped along the curvature of the surface of the conductive particles 11 as shown in FIG. 1, but when the conductive particles 11 of the circuit member 1 with bumps are pressed against the electrode of another circuit member, a force is also applied to the base layer 5 due to the deformation of the conductive particles 11. At this time, if the effective amount of the eutectic solder layer 5B in the base layer 5 of the base layer 5 is less than 5%, the likelihood of the base layer 5 being deformed is low, resulting in damage to the conductive particles 11. Since it is difficult to increase the contact area between the electrode 3 of the circuit member 1 with bumps and the conductive particles 11, it is difficult to reduce the connection resistance.

[0079] When the effective amount of the eutectic solder layer 5B in the base layer 5 is greater than 95%, the alloy layer 5A of the base layer 5 is almost absent. The alloy layer 5A is made of an alloy of the metal constituting the electrode 3 and the solder layer 14, and the effective amount of the alloy layer 5A means that the solder has "wet" the electrode surface. The solder is a component containing tin or a tin alloy, but tin or a tin alloy is a relatively soft material among metals. For this reason, when the conductive particles 11 are pressed against the electrode 3, the solder layer 14 may deform and appear as if the conductive particles 11 are bonded to the electrode 3, but if the wetting of the solder to the electrode surface is insufficient, an interface exists between the electrode 3 and the solder layer 14, and the bonding strength between the electrode 3 and the conductive particles 11 is considered to be insufficient. In this case, the bonding of the conductive particles 11 to the electrode 3 is likely to be poor, and the conductive particles 11 may peel off from the electrode 3 after bonding, or the conductive particles 11 may move to an electrode 3 other than the target electrode 3, causing a malfunction.

[0080] To address such problems, in this embodiment, the effective amount of the eutectic solder layer 5B in the base layer 5 is set to 5% to 95%. By setting the effective amount of the eutectic solder layer 5B in the base layer 5 to 5% or more, the conductive particles 11 can be sufficiently deformed together with the base layer 5 when the circuit member 1 with bumps is connected to another circuit member. This reduces the connection resistance and stabilizes the resistance value. By setting the effective amount of the eutectic solder layer 5B in the base layer 5 to 95% or less, the bonding strength of the conductive particles 11 to the electrode 3 can be sufficiently ensured. This improves the stability of the connection.

[0081] In this embodiment, the conductive particle 11 has a base particle 12 and a metal layer 13 covering the base particle 12, and the melting point of the metal constituting the metal layer 13 is higher than the melting point of tin or a tin alloy. This makes it possible to suppress melting of the metal layer 13 when the conductive particle 11 is joined to the electrode 3. Therefore, the conductive particle 11 and the electrode 3 can be firmly joined by the solder layer 14 melted at a predetermined position on the surface of the electrode 3, while the state in which the metal layer 13 covers the base particle 12 is sufficiently maintained, and excellent connection reliability can be obtained when the circuit member 1 with bumps is connected to another circuit member.

[0082] In the method for manufacturing a circuit member with bumps according to the present embodiment, the conductive particles 11 are bonded to the electrodes 3 at a temperature below the melting point of tin or a tin alloy, and a base layer 5 is formed that includes an alloy layer 5A with the metal constituting the electrode 3 and a eutectic solder layer 5B. According to the circuit member with bumps 1 obtained by this method for manufacturing a circuit member with bumps, the eutectic solder layer 5B is present in the base layer 5, so that when the circuit member with bumps 1 is connected to another circuit member, the conductive particles 11 are firmly crushed between the electrodes, and the solder spreads sufficiently. Therefore, the reliability of conduction can be improved. In addition, since the conductive particles 11 are bonded to the electrodes 3 by the base layer 5, the conductive particles 11 can be prevented from flowing into the space between the electrodes when the obtained circuit member with bumps 1 is connected to another circuit member. Therefore, the reliability of insulation can also be improved.

[0083] 8 is a diagram showing the results of a conduction reliability test of the circuit member with bumps according to the present disclosure. In this conduction reliability test, a high-temperature, high-humidity test was performed on a connection structure (comparative example) in which a circuit member with bumps obtained by bonding conductive particles to electrodes at a temperature higher than the melting point of tin or a tin alloy was connected to another circuit member, and a connection structure (example) in which a circuit member with bumps obtained by bonding conductive particles to electrodes at a temperature higher than the melting point of tin or a tin alloy was connected to another circuit member, and the change over time in the connection resistance value of each was measured.

[0084] In the examples and comparative examples, the solder layer was made of Sn-Bi58 (melting point 139°C). In the examples, the temperature when bonding the conductive particles and the electrodes was 135°C, and in the comparative examples, the temperature when bonding the conductive particles and the electrodes was 170°C. The high temperature and high humidity test was carried out at a temperature of 85°C and a humidity of 85 RH% for 250 hours.

[0085] As shown in Fig. 8, in the comparative example, the initial connection resistance was about 4Ω, but the connection resistance after 250 hours increased to about 6Ω (about 1.5 times the initial connection resistance). In contrast, in the working example, the initial connection resistance was about 2.6Ω, but the connection resistance after 250 hours was about 2.9Ω (about 1.1 times the initial connection resistance). From this result, it was confirmed that the method of joining conductive particles to electrodes at a temperature higher than the melting point of tin or tin alloy as disclosed herein contributes to improving the conduction reliability.

[0086] 9 is a diagram showing the results of an insulation reliability test of the circuit member with bumps according to the present disclosure. This insulation reliability test was conducted by observing the positions of conductive particles between the electrodes of a connection structure (comparative example) in which the electrodes of two circuit members were connected together using a general anisotropic conductive film, and a connection structure (example) in which a circuit member with bumps obtained by bonding conductive particles to electrodes at a temperature higher than the melting point of tin or a tin alloy was connected to another circuit member.

[0087] In the insulation reliability test, evaluation was performed using a glass substrate with a transparent electrode (with ITO) and a sapphire chip with an Au electrode. The connection structures obtained in the examples and comparative examples were placed on the stage of a differential interference microscope (ECLIPSEL200N, manufactured by Nikon), and the periphery of the electrodes was observed in transmitted light mode at magnifications of 500x and 1000x.

[0088] As shown in Fig. 9, in the comparative example, a plurality of conductive particles are located in the space between adjacent electrodes. On the other hand, in the example, the conductive particles do not protrude into the space between adjacent electrodes, and the electrodes are firmly separated. From this result, it was confirmed that the method of bonding conductive particles to electrodes at a temperature higher than the melting point of tin or tin alloy as disclosed herein contributes to improving insulation reliability.

[0089] The gist of this disclosure is as follows: [1] to [7] [1] A circuit member with bumps comprising a substrate, an electrode provided on one surface of the substrate, and a bump provided on the electrode, the bump having conductive particles and a base layer containing tin or a tin alloy and electrically connecting the conductive particles and the electrode while covering at least a portion of the conductive particles, the base layer being composed of an alloy layer with a metal constituting the electrode and a eutectic solder layer. [2] The circuit member with bumps according to [1], wherein the conductive particles have portions that are in direct contact with the electrodes without the intermediation of the base layer. [3] The circuit member with bumps according to [1] or [2], wherein the effective amount of the eutectic solder layer in the base layer is 5% to 95%. [4] The circuit member with bumps according to any one of [1] to [3], wherein the conductive particles have a base particle and a metal layer covering the base particle, and the melting point of the metal constituting the metal layer is higher than the melting point of the tin or tin alloy. [5] A method for manufacturing a circuit member with bumps, comprising: a preparation step of preparing a circuit member having an electrode on one side of a substrate and conductive particles at least partially covered with a solder layer containing tin or a tin alloy; and a formation step of forming bumps on the electrode using the conductive particles, wherein in the formation step, the conductive particles are joined to the electrode at a temperature below the melting point of the tin or tin alloy, and a base layer including an alloy layer with a metal constituting the electrode and a eutectic solder layer is formed, thereby electrically connecting the conductive particles to the electrode. [6] A connection structure in which a first circuit member constituted by the circuit member with bumps described in any one of [1] to [4] and a second circuit member having electrodes corresponding to electrodes of the first circuit member are electrically connected via the bumps, the bumps having conductive particles and a base layer containing tin or a tin alloy and electrically connecting the conductive particles to the electrodes of the first circuit member while covering at least a portion of the conductive particles, the base layer being constituted by including an alloy layer with a metal constituting the electrodes and a eutectic solder layer. [7] A method for manufacturing a connection structure, comprising: a preparation step of preparing a circuit member with bumps according to any one of [1] to [4] as a first circuit member, and preparing a second circuit member having electrodes corresponding to the electrodes of the first circuit member; and a connection step of opposing the electrodes of the second circuit member to the bumps of the first circuit member, and heating the conductive particles to a temperature higher than the melting point of the tin or tin alloy, thereby electrically connecting the conductive particles and the electrodes of the second circuit member. [Explanation of symbols]

[0090] 1...circuit member with bumps, 2...substrate, 2a...one side, 3...electrode, 4...bump, 5...base layer, 5A...alloy layer, 5B...eutectic solder layer, 11...conductive particles, 32A...first circuit member (circuit member with bumps), 32B...second circuit member, 34...electrode.

Claims

1. A substrate; An electrode provided on one surface of the substrate; A bump provided on the electrode, the bump has conductive particles and a base layer that contains tin or a tin alloy and electrically connects the conductive particles to the electrode while covering at least a portion of the conductive particles; The circuit member with bumps, wherein the base layer is configured to include a eutectic solder layer and an alloy layer with the metal constituting the electrode.

2. 2. The circuit member with bumps according to claim 1, wherein the conductive particles have portions that directly contact the electrodes without being connected through the base layer.

3. 2. The bumped circuit member according to claim 1, wherein an effective amount of the eutectic solder layer in the base layer is 5% to 95%.

4. The conductive particle has a base particle and a metal layer covering the base particle, 2. The circuit member with bumps according to claim 1, wherein the melting point of the metal constituting the metal layer is higher than the melting point of the tin or tin alloy.

5. A preparation step of preparing a circuit member having an electrode on one surface of a substrate and conductive particles at least partially covered with a solder layer containing tin or a tin alloy; and forming a bump on the electrode using the conductive particles. A method for manufacturing a circuit member with bumps, in which the forming process electrically connects the conductive particles to the electrode at a temperature below the melting point of the tin or tin alloy, and forms a base layer including an alloy layer with a metal constituting the electrode and a eutectic solder layer.

6. A connection structure in which a first circuit member constituted by the circuit member with bumps according to any one of claims 1 to 4 and a second circuit member having electrodes corresponding to the electrodes of the first circuit member are electrically connected via the bumps, the bump has conductive particles and a base layer that contains tin or a tin alloy and electrically connects the conductive particles to the electrode of the first circuit member while covering at least a portion of the conductive particles; A connection structure, wherein the base layer is configured to include a eutectic solder layer and an alloy layer with the metal constituting the electrode.

7. A preparation step of preparing a circuit member with bumps according to any one of claims 1 to 4 as a first circuit member and preparing a second circuit member having electrodes corresponding to the electrodes of the first circuit member; a connection process for electrically connecting the conductive particles and the electrodes of the second circuit member by placing the electrodes of the second circuit member opposite the bumps of the first circuit member and heating the conductive particles to a temperature higher than the melting point of the tin or tin alloy.

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