Solder bump formation member, method for manufacturing solder bump formation member, and method for manufacturing electrode substrate with solder bumps

Abstract

A component for solder bump formation, comprising: a base having a plurality of recesses; and solder particles and a fluidizing agent in the recesses, the average particle diameter of the solder particles being 1 to 35 μm, and the C.V. value being 20% or less.

Description

Technical Field

[0001] The present invention relates to a component for forming solder bumps, a method for manufacturing the component for forming solder bumps, and a method for manufacturing an electrode substrate with solder bumps. Background Technology

[0002] A solder ball mounting plate is known, characterized in that it comprises a mask having a plurality of solder ball insertion holes arranged in a predetermined pattern, solder balls housed in the insertion holes, and a fixing agent holding the solder balls in the insertion holes (for example, see Patent Document 1).

[0003] There are known manufacturing methods for solder bump forming sheets that include the following steps (for example, see Patent Document 2).

[0004] A. Prepare a sheet with multiple recesses on a specified location on one side, the bottom surface of which is made of adhesive; B. Fill each recess of the sheet with solder powder, which is held in place by the adhesive on the bottom surface of the recess; C. Remove the solder powder that is not held in place by the adhesive from the sheet; and D. Cover the solder powder in the recesses of the sheet.

[0005] There is a known method for forming solder bumps on electrodes by transferring solder balls disposed in grooves onto the surface of an adhesive roller, and then moving the solder balls onto the adhesive on the electrodes (for example, see Patent Document 3).

[0006] Previous technical documents

[0007] Patent documents

[0008] Patent Document 1: Japanese Patent Application Publication No. 2004-080024

[0009] Patent Document 2: International Publication No. 2006 / 043377

[0010] Patent Document 3: Japanese Patent Application Publication No. 2017-157626 Summary of the Invention

[0011] The technical problem to be solved by the invention

[0012] In the transfer sheet and manufacturing method shown in Patent Documents 1 and 2, a bonding layer is required to hold the solder particles. Therefore, by heating the solder above its melting point to melt / unify it, and then heating it during transfer to the electrode, the bonding layer components soften / melt / decompose, potentially becoming impurities. These impurities, located between the solder and the electrode, may hinder the stable formation of solder bumps. If these impurities are removed after transferring solder bumps to the electrode, the substrate with the electrode and the semiconductor package are exposed to the cleaning solution, potentially leading to increased processing steps, substrate / semiconductor package defects, and defects caused by inadequate cleaning.

[0013] In Patent Document 3, solder balls (particles) are placed on the electrode via an adhesive. However, adhesive residue remains on the solder ball surface, potentially causing poor bonding. Furthermore, controlling the adhesive thickness and surface roughness is feasible when the solder ball size is around 100 μm, but becomes difficult as the size decreases to 50 μm or 30 μm. Therefore, it is difficult to improve the transfer rate if solder balls (particles) smaller than 30 μm are transferred / moved via adhesive.

[0014] Furthermore, transfer sheets are known where solder balls (particles) are in contact with each other and uniformly disposed on the surface of a substrate via an adhesive. The transfer sheet is designed to be pressed onto a substrate with electrodes and heated to transfer the solder balls onto the electrodes, forming bumps via subsequent reflow. However, the inventors' research has shown that if the electrode spacing becomes narrow, solder bridging occurs between the electrodes, resulting in short circuits. It is speculated that because adjacent solder balls are in contact with each other, the solder melts / merges due to the heat during transfer to the electrodes, creating portions that span between adjacent electrodes. In solder transfer sheets where solder particles are in contact and uniformly arranged, with electrode spacing on the order of a few micrometers, it is currently difficult to form solder bumps without short circuits.

[0015] The present invention was made in view of the above circumstances, and its object is to provide a solder bump forming component and a method thereof useful in manufacturing a connection structure that exhibits excellent insulation reliability and conductivity reliability even at small connection points of circuit components that should be electrically connected to each other. Furthermore, the present invention aims to provide a method for manufacturing an electrode substrate with solder bumps using this component.

[0016] means for solving technical problems

[0017] One aspect of the present invention relates to a component for forming solder bumps, which includes a substrate having a plurality of recesses and solder particles and a fluidizing agent within the recesses, wherein the average particle size of the solder particles is 1 to 35 μm and the CV value is 20% or less.

[0018] The aforementioned solder bump forming component is useful in manufacturing connection structures that are small at the connection points of circuit components that should be electrically connected to each other, and that have both excellent insulation reliability and conductivity reliability.

[0019] In one method of forming a component for solder bumps, the fluidizing agent may include at least one selected from the group consisting of succinic acid, glutaric acid, adipic acid, pimelic acid, octanoic acid, benzoic acid, and malic acid.

[0020] In one method of forming a component for solder bumps, a planar portion may be formed on a part of the surface of a solder particle.

[0021] In one method of forming a component for solder bumps, the distance between adjacent recesses can be more than 0.1 times the average particle size of the solder particles.

[0022] One aspect of the present invention relates to a method for manufacturing a component for forming solder bumps, comprising: a pre-process, preparing a substrate having a plurality of recesses as well as solder particles and a fluidizing agent; and a configuration process, configuring solder particles and a fluidizing agent in the recesses.

[0023] One aspect of the present invention relates to a method for manufacturing a component for forming solder bumps, comprising: a preparation step of preparing a substrate having a plurality of recesses and solder particles; a receiving step of receiving at least a portion of the solder particles in the recesses; a fusing step of fusing the solder particles received in the recesses to form solder particles within the recesses; and an injection step of disposing a fluidizing agent within the recesses where solder particles are formed.

[0024] In one method of manufacturing a component for forming solder bumps, the average particle size of the solder particles can be 1 to 35 μm, and the CV value can be 20% or less.

[0025] In one method of manufacturing a component for forming solder bumps, the CV value of the solder particles can exceed 20%.

[0026] In one method of manufacturing a component for forming solder bumps, a reduction step may be performed before the fusion step, in which solder particles contained in the recess are exposed to a reducing atmosphere.

[0027] In one method of manufacturing a component for forming solder bumps, solder particles can be fused in a reducing atmosphere during the fusion process.

[0028] One aspect of the present invention relates to a method for manufacturing an electrode substrate with solder bumps, comprising: a preparation step of preparing the aforementioned solder bump forming component and a substrate having a plurality of electrodes; an arrangement step of bringing the surface of the solder bump forming component having a recess into contact with the surface of the substrate having electrodes; and a heating step of heating solder particles to a temperature above the melting point of the solder particles.

[0029] In one aspect of the method for manufacturing an electrode substrate with solder bumps, during the heating step, the component for forming solder bumps and the substrate can be brought into contact under pressure, and the solder particles are heated to a temperature above the melting point of the solder particles.

[0030] In one method of manufacturing an electrode substrate with solder bumps, a reduction step may be performed before the configuration step, in which solder particles are exposed to a reducing atmosphere.

[0031] In one method of manufacturing an electrode substrate with solder bumps, a reduction step of exposing solder particles to a reducing atmosphere may be included after the configuration step and before the heating step.

[0032] In one method of manufacturing an electrode substrate with solder bumps, during the heating step, solder particles can be heated to a temperature above the melting point of the solder particles under a reducing atmosphere.

[0033] In one method of manufacturing an electrode substrate with solder bumps, a removal step may be performed after the heating step to remove the solder bump forming component from the substrate.

[0034] In one method of manufacturing an electrode substrate with solder bumps, a cleaning step for removing solder particles that are not bonded to the electrode can be performed after the removal step.

[0035] Invention Effects

[0036] According to the present invention, a solder bump forming component and a method thereof are provided that are useful in manufacturing connection structures where both insulation reliability and conductivity reliability are excellent, even when the connection points of circuit components that should be electrically connected are small. Furthermore, according to the present invention, a method for manufacturing an electrode substrate with solder bumps using this component is provided. Attached Figure Description

[0037] Figure 1 This is a schematic cross-sectional view of a solder bump forming component according to one embodiment.

[0038] Figure 2 (a) is from Figure 1 A diagram showing solder particles observed on the side opposite to the opening of the concave portion. Figure 2 (b) is a graph showing the distances X and Y (where Y < X) between opposite sides in the case of a quadrilateral circumscribed by two pairs of parallel lines and the projected image of solder particles.

[0039] Figure 3 (a) is a top view schematically representing an example of a substrate. Figure 3 (b) is Figure 3(a) A cross-sectional view of the Ib-Ib line.

[0040] Figure 4 (a) to (h) are sectional views schematically representing examples of the cross-sectional shape of a recess in a matrix.

[0041] Figure 5 It is a schematic cross-sectional view showing the state in which solder particles are contained in the recess of the substrate.

[0042] Figure 6 (a) and Figure 6 (b) is a cross-sectional view schematically illustrating an example of the manufacturing process of an electrode substrate with solder bumps.

[0043] Figure 7 (a) and Figure 7 (b) is a cross-sectional view schematically illustrating an example of the manufacturing process of a connecting structure.

[0044] Figure 8 This is a cross-sectional view schematically representing an example of the substrate. Detailed Implementation

[0045] The embodiments of the present invention will be described below. The present invention is not limited to the following embodiments. Furthermore, unless otherwise specified, any one of the materials exemplified below may be used alone, or two or more may be used in combination. Regarding the content of each component in the composition, if multiple substances equivalent to each component are present in the composition, unless otherwise specified, the content refers to the total amount of the multiple substances present in the composition. The numerical range indicated by "~" represents the range encompassed by the values ​​before and after "~" as the minimum and maximum values, respectively. In the numerical ranges described in stages in this specification, the upper or lower limit of the numerical range for one stage may be replaced by the upper or lower limit of the numerical range for another stage. The upper or lower limit of the numerical ranges described in this specification may be replaced by the values ​​shown in the examples.

[0046] <Components for solder bump formation>

[0047] In one embodiment, the component for forming solder bumps includes a substrate having multiple recesses, solder particles and a fluidizing agent within the recesses, wherein the average particle size of the solder particles is 1 to 35 μm and the CV value is 20% or less.

[0048] Figure 1This is a schematic cross-sectional view of a solder bump forming component according to one embodiment. The solder bump forming component 10 includes a base 60 having a plurality of recesses 62, and solder particles 1 and fluidizing agent F within the recesses 62. In a predetermined longitudinal section of the solder bump forming component 10, the solder particles 1 are arranged such that one solder particle 1 is spaced apart from the adjacent solder particle 1 along the transverse direction ( Figure 1 The solder particles 1 are arranged in a left-right direction within the recess 62. The solder particles 1 can be within the recess 62, in contact with its side surface and / or bottom surface. The fluidizing agent F can be present between the solder particles 1 and the bottom surface of the recess 62. The component for forming solder bumps can be in the form of a film (film for forming solder bumps), a sheet (sheet for forming solder bumps), etc.

[0049] (solder particles)

[0050] The average particle size of the solder particles 1 is, for example, 35 μm or less, preferably 30 μm or less, 25 μm or less, 20 μm or less, or 15 μm or less. Furthermore, the average particle size of the solder particles 1 is, for example, 1 μm or more, preferably 2 μm or more, more preferably 3 μm or more, and even more preferably 5 μm or more.

[0051] The average particle size of solder particles 1 can be determined using various methods that conform to size requirements. For example, methods such as dynamic light scattering, laser diffraction, centrifugal sedimentation, inductively coupled plasma mass spectrometry, and resonant mass measurement can be used. Furthermore, methods for determining particle size can be employed using images obtained from optical microscopes, electron microscopes, etc. Specific devices include flow cytometry particle image analysis devices, microtracks, and Coulter counters. The average particle size of solder particles 1 can be set as the equivalent diameter of the projected area circle (the diameter of a circle having an area equal to the projected area of ​​the particle) when observing solder particles 1 from a direction perpendicular to the main surface of the solder bump forming component 10.

[0052] From the viewpoint of achieving superior conductivity and insulation reliability, the CV value of solder particles 1 is preferably 20% or less, more preferably 10% or less, and even more preferably 7% or less. Furthermore, there is no particular limitation on the lower limit of the CV value of solder particles 1. For example, the CV value of solder particles 1 can be 1% or more, or it can be 2% or more.

[0053] The CV value of solder particle 1 is calculated by multiplying the value obtained by dividing the standard deviation of the particle size measured by the aforementioned method by the average particle size by 100.

[0054] A planar portion can be formed on a part of the surface of the solder particles. Figure 2 (a) is from Figure 1The diagram shows the solder particle 1 viewed from the side opposite to the opening of the recess 62. The solder particle 1 has a shape in which a planar portion 11 of diameter A is formed on a portion of the surface of a sphere having diameter B. Furthermore, Figure 1 and Figure 2 The solder particle 1 shown in (a) has a flat portion 11 because the bottom of the recess 62 is a plane. However, if the bottom of the recess 62 is a shape other than a plane, it has a surface with a different shape corresponding to the shape of the bottom.

[0055] like Figure 2 As shown in (a), the solder particle 1 may have a planar portion 11 formed on a portion of its surface, and the surface other than the planar portion 11 is preferably spherical. That is, the solder particle 1 may have a planar portion 11 and a spherical curved portion. The ratio (A / B) of the diameter A of the planar portion 11 to the diameter B of the solder particle 1 may, for example, be greater than 0.01 and less than 1.0 (0.01 < A / B < 1.0), or it may be 0.1 to 0.9. The planar portion 11 may contact the bottom surface of the recess 62. Figure 1 As shown, the solder particle 1 has a planar portion 11, and this planar portion contacts the bottom surface of the recess, thereby making it less likely for it to detach from the solder bump forming component 10. Additionally, sometimes a planar portion is also formed in the part of the inner wall of the recess 62 that contacts the solder particle 1. However, when manufacturing the solder bump forming component, if, as described later, the solder particle 1 is temporarily removed from the substrate 60 and the solder particle 1 and fluidizing agent F are then repositioned in the recess of the substrate, the planar portion 11 may not necessarily contact the bottom surface of the recess 62.

[0056] When a quadrilateral circumscribed by the projected image of solder particle 1 is formed by two pairs of parallel lines, and the distances between opposite sides are set as X and Y (where Y < X), the ratio of Y to X (Y / X) can be greater than 0.8 and less than 1.0 (0.8 < Y / X < 1.0), or it can be greater than 0.9 and less than 1.0. This solder particle 1 can be described as a particle that more closely approximates a sphere. By making the solder particle 1 closer to a sphere, unevenness is less likely to occur in the contact between the solder particle 1 and the electrode, tending to achieve a stable connection.

[0057] Figure 2 (b) is a graph showing the distances X and Y (where Y < X) between opposite sides in the case of a quadrilateral circumscribed by two pairs of parallel lines and a projection image of a solder particle. For example, a projection image is obtained by observing an arbitrary particle using a scanning electron microscope. Two pairs of parallel lines are drawn for the obtained projection image, one pair of parallel lines is positioned where the distance between the parallel lines is the minimum, and the other pair of parallel lines is positioned where the distance between the parallel lines is the maximum, and the Y / X of that particle is calculated. This operation is performed on 300 solder particles, and the average value is calculated and set as the Y / X of the solder particle.

[0058] Solder particles 1 may contain tin or tin alloys. Examples of tin alloys include In-Sn alloys, In-Sn-Ag alloys, Sn-Au alloys, Sn-Bi alloys, Sn-Bi-Ag alloys, Sn-Ag-Cu alloys, and Sn-Cu alloys. Specific examples of these tin alloys are given below.

[0059] •In-Sn (In 52% by mass, Bi 48% by mass, melting point 118℃)

[0060] •In-Sn-Ag (In 20% by mass, Sn 77.2% by mass, Ag 2.8% by mass, melting point 175℃)

[0061] • Sn-Bi (Sn 43% by mass, Bi 57% by mass, melting point 138℃)

[0062] • Sn-Bi-Ag (Sn 42% by mass, Bi 57% by mass, Ag 1% by mass, melting point 139℃)

[0063] Sn-Ag-Cu (Sn 96.5% by mass, Ag 3% by mass, Cu 0.5% by mass, melting point 217℃)

[0064] Sn-Cu (Sn 99.3% by mass, Cu 0.7% by mass, melting point 227℃)

[0065] Sn-Au (Sn 21.0% by mass, Au 79.0% by mass, melting point 278℃)

[0066] Solder particles may contain indium or indium alloys. Examples of indium alloys include In-Bi alloys and In-Ag alloys. Specific examples of these indium alloys are given below.

[0067] •In-Bi (In 66.3% by mass, Bi 33.7% by mass, melting point 72℃)

[0068] •In-Bi (In 33.0% by mass, Bi 67.0% by mass, melting point 109℃)

[0069] •In-Ag (In 97.0% by mass, Ag 3.0% by mass, melting point 145℃)

[0070] Depending on the intended use of solder particles 1 (the temperature at which they are joined), the aforementioned tin alloy or indium alloy can be selected. For example, when solder particles 1 are used for welding at low temperatures, In-Sn alloys or Sn-Bi alloys can be used, in which case welding can be achieved at temperatures below 150°C. When materials with high melting points, such as Sn-Ag-Cu alloys or Sn-Cu alloys, are used, high reliability can be maintained even after being placed at high temperatures.

[0071] Solder particles 1 may contain one or more elements selected from Ag, Cu, Ni, Bi, Zn, Pd, Pb, Au, P, and B. Among these elements, Ag or Cu may be included from the viewpoint that by including Ag or Cu in solder particles 1, the melting point of solder particles 1 can be lowered to about 220°C, and the bonding strength with the electrode can be further improved, thus making it easier to obtain better conductivity reliability.

[0072] The Cu content of solder particles 1 is, for example, 0.05 to 10% by mass, or 0.1 to 5% by mass or 0.2 to 3% by mass. If the Cu content is 0.05% by mass or more, it is easier to achieve better solder joint reliability. Furthermore, if the Cu content is 10% by mass or less, it is easier to obtain solder particles 1 with low melting point and excellent wettability. As a result, the joint reliability of the joint based on solder particles 1 is easier to achieve.

[0073] The Ag content of solder particles 1 is, for example, 0.05 to 10% by mass, or 0.1 to 5% by mass or 0.2 to 3% by mass. If the Ag content is 0.05% by mass or more, it is easier to achieve better solder joint reliability. Furthermore, if the Ag content is 10% by mass or less, it is easier to obtain solder particles 1 with low melting point and excellent wettability. As a result, the joint reliability based on solder particles 1 is easier to achieve.

[0074] (fluidizing agent)

[0075] The fluidizing agent F functions as a flowing phase during recirculation, extruding solder particles 1 from the recess 62 toward the electrode side. Furthermore, the fluidizing agent F can be a flux, organic solvent, etc. The fluxing agent improves the wettability of the solder to the electrode by dissolving oxides on the surface of the solder particles and the electrode surface.

[0076] Various organic solvents can be used as the fluidizing agent F. The boiling point of the fluidizing agent F can be higher than the melting point of the solder. With the electrode and the recess facing each other, when heated, the boiling point of the fluidizing agent F, being higher than the melting point of the solder, causes it to flow within the recess. As the fluidizing agent F flows, the solder particles also flow. Through the flow of the fluidizing agent F and the solder particles, the electrode surface and the solder particles become more easily in contact, thus promoting the formation of solder bumps. Therefore, when forming solder bumps, if a heating temperature is at least higher than the melting point of the solder particles, higher than the softening point or melting point of the fluidizing agent F, and lower than the boiling point of the fluidizing agent F, solder bumps are easily formed on the electrode. If, after sufficient solder bump formation, the heating temperature is increased to above the boiling point of the fluidizing agent F, residues originating from the fluidizing agent F on the substrate surface and the electrode surface can be reduced.

[0077] As a variety of organic solvents that can be used in fluidizing agent F, it can utilize aliphatic hydrocarbons such as cyclohexane (boiling point: 80℃), cycloheptane (boiling point: 118℃), cyclooctane (boiling point: 149℃), heptane (boiling point: 98℃), octane (boiling point: 126℃), nonane (boiling point: 150℃), decane (boiling point: 174℃), undecane (boiling point: 196℃), dodecane (boiling point: 215℃), tridecane (boiling point: 234℃), tetradecane (boiling point: 254℃), pentadecane (boiling point: 269℃), hexadecane (boiling point: 287℃), heptadecane (boiling point: 302℃), octadecane (boiling point: 317℃), and nonadecane (boiling point: 330℃). These aliphatic hydrocarbons are nonpolar and do not have the reducing function of the metals used in solder and electrodes such as Au and Cu. However, as solvents with boiling points above the melting point of solder, they can be appropriately selected and have the function of making solder particles come into contact with the electrode surface by heating and causing the solder particles to flow.

[0078] Various organic solvents that can be used in fluidizing agent F include, for example, mono- and polyols such as pentanol, hexanol, heptanol, octanol, decanol, ethylene glycol, diethylene glycol, propylene glycol, butanediol, α-terpineol, and isoborneol cyclohexanol (MTPH); ethylene glycol butyl ether, ethylene glycol phenyl ether, diethylene glycol methyl ether, diethylene glycol ethyl ether, diethylene glycol butyl ether, diethylene glycol isobutyl ether, diethylene glycol hexyl ether, triethylene glycol methyl ether, diethylene glycol dimethyl ether, diethylene glycol diethyl ether, diethylene glycol dibutyl ether, diethylene glycol butyl methyl ether, diethylene glycol isopropyl methyl ether, triethylene glycol dimethyl ether, triethylene glycol butyl methyl ether, propylene glycol propyl ether, dipropylene glycol methyl ether, dipropylene glycol ethyl ether, dipropylene glycol propyl ether, dipropylene glycol propyl ether, dipropylene glycol propyl ether, dipropylene glycol methyl ether, dipropylene glycol ethyl ether, dipropylene glycol propyl ether, dipropylene glycol methyl ... Ethers such as butyl alcohol ether, dipropylene glycol dimethyl ether, tripropylene glycol methyl ether, and tripropylene glycol dimethyl ether; esters such as ethylene glycol ethyl ether acetate, ethylene glycol butyl ether acetate, diethylene glycol ethyl ether acetate, diethylene glycol butyl ether acetate, dipropylene glycol methyl ether acetate (DPMA), ethyl lactate, butyl lactate, γ-butyrolactone, and propylene carbonate; amides such as N-methyl-2-pyrrolidone, N,N-dimethylacetamide, and N,N-dimethylformamide; aliphatic hydrocarbons such as cyclohexane, octane, nonane, decane, and undecane; aromatic hydrocarbons such as benzene, toluene, and xylene; thiols with alkyl groups having 1 to 18 carbon atoms; and thiols with cycloalkyl groups having 5 to 7 carbon atoms. Examples of thiols having alkyl groups with 1 to 18 carbon atoms include ethanethiol, n-propanethiol, isopropanethiol, n-butanethiol, isobutanethiol, tert-butanethiol, pentamethylthiol, hexanethiol, and dodecylthiol. Examples of cycloalkylthiols having 5 to 7 carbon atoms include cyclopentanethiol, cyclohexanethiol, and cycloheptanethiol. In addition, examples of thiols as organic solvents include monoalkylamines, dialkylamines, trialkylamines, alkanolamines, cyclohexylamine, dicyclohexylamine, and other alicyclic amines, as well as aromatic amines such as diphenylamine and triphenylamine. Examples of thiols as organic solvents include ethylenediethanolamine, n-butyldiethanolamine, diethanolamine, and N,N-bis(2-hydroxyethyl)isopropanolamine.

[0079] Glycol ether solvents can also be used as organic solvents for fluidizing agent F. Examples of solvents with boiling points below 200°C include dipropylene glycol monomethyl ether, propylene glycol monobutyl ether, diethylene glycol dimethyl ether, ethylene glycol monoallyl ether, and ethylene glycol monoisopropyl ether. Examples of solvents with boiling points above 200°C include ethylene glycol monohexyl ether, diethylene glycol monohexyl ether, triethylene glycol monomethyl ether, ethylene glycol mono-2-ethylhexyl ether, diethylene glycol mono-2-ethylhexyl ether, diethylene glycol dibutyl ether, triethylene glycol butyl methyl ether, and tetraethylene glycol dimethyl ether.

[0080] As a flux that can be used as fluidizing agent F, fluxes commonly used for solder bonding, etc., can be used. The flux can be appropriately selected based on the composition of the solder particles, melting point, surface condition, heating / atmosphere conditions during transfer, etc. Examples include zinc chloride, mixtures of zinc chloride and inorganic halides, mixtures of zinc chloride and inorganic acids, molten salts, phosphoric acid, derivatives of phosphoric acid, organohalides, hydrazine, organic acids, rosin, etc. One of these can be used alone, or two or more can be used simultaneously.

[0081] Examples of molten salts include ammonium chloride. Examples of organic acids include lactic acid, citric acid, stearic acid, glutamic acid, and glutaric acid. Furthermore, examples of organic acids that can be used as fluxes include organic acids with 8 to 16 carbon atoms. Examples of organic acids with 8 to 16 carbon atoms include octanoic acid, methylheptanoic acid, ethylhexanoic acid, propylvalerate, nonanoic acid, methyloctanoic acid, ethylheptanoic acid, propylhexanoic acid, decanoic acid, methylnonanoic acid, ethyloctanoic acid, propylheptanoic acid, butylhexanoic acid, undecanoic acid, methyldecanoic acid, ethylnonanoic acid, propyloctanoic acid, butylheptanoic acid, lauric acid, methylundecanoic acid, ethyldecanoic acid, propylnonanoic acid, butyloctanoic acid, pentylheptanoic acid, tridecanoic acid, methyldodecanoic acid, ethylundecanoic acid, propyldecanoic acid, butylnonanoic acid, pentyloctanoic acid, myristic acid, methyltridecanoic acid, ethyldodecanoic acid, propylundecanoic acid, butyldecanoic acid, pentylnonanoic acid, hexyloctanoic acid, pentadecanoic acid, methyltetradecanoic acid, ethyltridecanoic acid, propyldecadecanoic acid, etc. Dialkyl acids, butylundecanoic acid, pentyldecanoic acid, hexylnonanoic acid, palmitic acid, methylpentadecanoic acid, ethyltetradecanoic acid, propyltridecanoic acid, butyldodecanoic acid, pentylundecanoic acid, hexyldecanoic acid, heptylnonanoic acid, methylcyclohexanecarboxylic acid, ethylcyclohexanecarboxylic acid, propylcyclohexanecarboxylic acid, butylcyclohexanecarboxylic acid, pentylcyclohexanecarboxylic acid, hexylcyclohexanecarboxylic acid, heptylcyclohexanecarboxylic acid, octylcyclohexanecarboxylic acid, nonylcyclohexanecarboxylic acid, and other saturated fatty acids; octenic acid, nonenoic acid, methylnonenoic acid, decenoic acid, undecenoic acid, dodecenoic acid, tridecenoic acid, tetradecenoic acid, myristenoic acid, pentadecenoic acid, hexadecenoic acid, palmitoleic acid, cis-6-hexadecenoic acid (sapienic acid) Unsaturated fatty acids such as terephthalic acid, pyromellitic acid, o-phenoxybenzoic acid, methylbenzoic acid, ethylbenzoic acid, propylbenzoic acid, butylbenzoic acid, pentylbenzoic acid, hexylbenzoic acid, heptylbenzoic acid, octylbenzoic acid, and nonylbenzoic acid are used. Organic acids can be used alone or in combination of two or more. Examples of rosin include activated and unactivated rosin. Rosin is a type of rosin resin with rosin acid as its main component. As a flux, the use of organic acids or rosin with two or more carboxyl groups can further improve the reliability of conductivity between electrodes.

[0082] The melting point of the flux can be above 50°C, above 70°C, or above 80°C. The melting point of the flux can be below 200°C, below 160°C, below 150°C, or below 140°C. If the melting point of the flux is above the lower limit and below the upper limit, the flux effect is further enhanced, and solder particles are more efficiently configured on the electrode. The melting point range of the flux can be 80–190°C or below 80–140°C.

[0083] Examples of fluxes with melting points in the range of 80–190°C include dicarboxylic acids such as succinic acid (melting point 186°C), glutaric acid (melting point 96°C), adipic acid (melting point 152°C), pimelic acid (melting point 104°C), and octanoic acid (melting point 142°C), as well as benzoic acid (melting point 122°C) and malic acid (melting point 130°C). Fluidizing agents may contain at least one selected from the group consisting of succinic acid, glutaric acid, adipic acid, pimelic acid, octanoic acid, benzoic acid, and malic acid.

[0084] The amount of fluidizing agent F present in the recess 62 is not particularly limited, but from the viewpoint of easily obtaining a suitable flow effect and fluxing effect, it can be 1 to 50 parts by mass, 1 to 20 parts by mass, or 20 to 50 parts by mass relative to 100 parts by mass of solder particles 1. The fluidizing agent F can also be a mixture with a solvent or resin material. Various organic solvents mentioned above can be used as solvents. If it is a mixture, the concentration of fluidizing agent F can be appropriately adjusted according to the solder particles 1. In order for the mixture to extrude the solder particles 1 onto the electrode during reflow, the softening point or melting point can be adjusted so that the fluidity of the mixture is increased by heating. If the softening point or melting point is higher than room temperature, the solder particles 1 are difficult to detach from the recess 62 at room temperature, thus making the processing before the solder bump formation process easier. High-boiling-point solvents can be used as solvents constituting the mixture. High-boiling-point solvents cause the solder particles 1 to evaporate after flowing on the electrode by reheating, thus making it difficult for them to remain on the electrode. Alcohol-based solvents can be used as solvents. If it is an alcohol-based solvent, it can exhibit reducing properties.

[0085] (Matrix)

[0086] The substrate 60 can be made of inorganic materials such as silicon, various ceramics, glass, and stainless steel, as well as organic materials such as various resins. Among these, the substrate 60 can be a heat-resistant material that does not deteriorate at the melting temperature of the solder particles. Furthermore, the substrate 60 can be a heat-resistant material that does not deform at the melting temperature of the solder particles. Also, the substrate 60 can be a material that does not change due to alloying or reaction with the material constituting the solder particles. The recesses 62 of the substrate 60 can be formed using known methods such as cutting, photolithography, and imprinting. In particular, if imprinting is used, recesses 62 of accurate size can be formed in a shorter number of steps.

[0087] The surface of the substrate 60 may have a coating layer. From the viewpoint of expanding the selectivity of materials that can be used for the substrate 60, the coating layer may be a material that is not easily alloyed with or does not alloy with the material constituting the solder particles. Inorganic or organic materials can be used as the coating layer. Examples of suitable coating layers include inorganic materials with a strong oxide layer on the surface of aluminum, chromium, etc.; oxides such as titanium oxide; nitrides such as boron nitride; carbon-based materials such as diamond-like carbon, diamond, and graphite; fluoropolymers; and high heat-resistant resins such as polyimide. Furthermore, the coating layer may have the function of adjusting the wettability with the solder. By providing a coating layer on the surface of the substrate 60, the wettability with the solder can be appropriately adjusted according to the intended use.

[0088] Methods for forming a coating layer include lamination, solution impregnation, coating, painting, impregnation, sputtering, and electroplating.

[0089] From the viewpoint of easily setting the conditions for the transfer process, the material of the substrate 60 can be a material with properties similar to or the same as those of the electrodes of the transferred solder particles and the substrate on which the electrodes are formed. For example, if the material has a similar or the same coefficient of thermal expansion (CTE), it is difficult for the solder particles to deviate from their original position during transfer.

[0090] Alignment marks can be provided on the substrate 60. These alignment marks can be read by a camera. Alignment marks can also be provided on the side of the substrate with electrodes. By providing alignment marks on the substrate 60 and the substrate with electrodes, when solder particles are transferred onto the electrodes, the alignment marks on the substrate 60 and the alignment marks on the substrate with electrodes are read by a camera mounted on an alignment device, thereby accurately determining the position of the recess 62 with solder particles and the position of the electrode on which the solder particles are transferred. Furthermore, by providing alignment marks on the substrate 60 and the substrate with electrodes, solder particles can be transferred onto the electrodes with high positional accuracy.

[0091] There should be one or more alignment marks on the substrate 60. If there are two or more alignment marks, the positional accuracy will be higher.

[0092] The structure of the specific substrate 60 is described below.

[0093] (Single layer of organic material)

[0094] The substrate 60 can be made of organic materials. Organic materials can be polymers, thermoplastics, thermosetting materials, photocurable materials, etc. By using organic materials, the range of physical properties is expanded, making it easier to form a substrate 60 that meets the desired purpose. For example, if it is an organic material, the substrate 60 (including the recess 62) is easily bent or stretched. If it is an organic material, various methods can be used to form the recess 62. Methods for forming the recess 62 include imprinting, photolithography, machining, laser processing, etc. In particular, according to the imprinting method, a mold with a desired shape can be pressed onto the substrate 60 made of organic material, thereby forming an arbitrary shape on the surface. By forming a convex pattern on the mold and pressing it onto the substrate 60 made of organic material, a recess 62 with a desired pattern can be formed. Furthermore, a photocurable resin can also be used in the formation of the recess 62. If a photocurable resin is applied to a mold and exposed, and then the mold is peeled off, a substrate 60 with the recess 62 can be formed. In the case of machining, the recess 62 can be formed using a drill bit or the like.

[0095] (Multi-layered organic materials)

[0096] The substrate can be composed of multiple organic materials. Furthermore, the substrate can have multiple layers, each composed of a different organic material. These organic materials can be polymers, thermoplastics, thermosetting materials, photocurable materials, etc. The substrate can have two layers composed of organic materials, with a recess formed in the organic material layer on one side. By multilayering, the material of the recess in contact with the solder can be selected based on its wettability with the solder, and each material can be selected according to its function. For example, Figure 8This is a schematic cross-sectional view illustrating an example of a substrate. The substrate 600 includes a base layer 601 and a recessed layer 602. The base layer 601 supports the recessed layer 602, and the recessed layer 602 is a layer in which recesses 62 are formed through processing. The base layer 601 can use a resin material with excellent heat resistance and dimensional stability, while the recessed layer 602 can be made of a material with excellent processability for the recesses 62. For example, thermoplastic resins such as polyethylene terephthalate and polyimide can be used in the base layer 601, and thermosetting resins in the recessed layer 602 can be used to form the recesses 62 using an impression die. For example, by clamping the thermosetting resin between polyethylene terephthalate and an impression die and then heating and pressurizing it, a substrate 600 with excellent flatness (including the recesses 62) can be obtained. Furthermore, when using a photocurable material to form the recesses 62, a material with high light transmittance can be used in the base layer 601. Materials with high light transmittance can include, for example, polyethylene terephthalate, transparent (colorless) polyimide, polyamide, etc. When using a photocurable material to form the recess 62, for example, a suitable amount of photocurable material is applied to the surface of the impression mold, and a polyethylene terephthalate film is placed on it. Ultraviolet light is then applied while applying pressure from the polyethylene terephthalate side using a roller. Furthermore, by curing the photocurable material and then peeling it off from the impression mold, a layer of polyethylene terephthalate and a layer of photocurable material can be obtained, and the recess 62 is a substrate 600 formed of the photocurable material. The material composition of the inner wall and bottom of the recess 62 can be changed. For example, the inner wall and bottom of the recess 62 can be made of the same resin material. Furthermore, the inner wall and bottom of the recess 62 can be made of different resin materials (e.g., thermosetting materials and thermoplastic materials).

[0097] Furthermore, photosensitive materials can be used as organic materials. These photosensitive materials can be positive or negative. For example, by forming a photosensitive material of uniform thickness on the surface of a thermoplastic polyethylene terephthalate film, followed by exposure and development, the recess 62 can be easily formed. The exposure and development method (photolithography) is widely used and highly versatile in the manufacture of semiconductors, circuit boards, etc. Moreover, in addition to exposure using a mask, direct drawing methods such as direct laser exposure can also be used as exposure methods.

[0098] By making the material of the base layer 601 thicker than the material forming the recessed layer 602, the properties of the entire substrate 600 can be dominated by the properties of the material of the base layer 601. Thus, even if there are weaknesses in the properties of the material forming the recessed layer 602, these weaknesses can be compensated for by the material of the base layer 601. For example, even if the material forming the recessed layer 602 is a material prone to thermal shrinkage, by selecting a material that is not prone to thermal shrinkage in the base layer 601 and making the thickness of the base layer 601 thicker than the material forming the recessed layer 602, deformation during heating can be suppressed.

[0099] Furthermore, organic materials can be appropriately selected according to the purpose, such as a combination of resin materials with excellent heat resistance or dimensional stability and materials with less component leaching at the melting temperature of solder particles, or a combination of resin materials with excellent heat resistance or dimensional stability and materials with appropriate wettability to solder, etc.

[0100] As described above, the substrate can be a substrate 600 composed of a base layer 601 and a recess layer 602. For example, by using a photosensitive material for the recess layer 602, the recess 62 can be fabricated by photolithography. By using photosensitive or thermosetting materials, thermoplastic materials, etc., in the recess layer 602, the recess 62 can be easily fabricated by imprinting. Furthermore, by changing the thickness of the base layer 601, the properties of the entire substrate can be adjusted, thus providing the advantage of being able to fabricate a substrate with the desired properties.

[0101] (Inorganic material, single layer (opaque))

[0102] The substrate 60 can be made of inorganic materials. From the viewpoint of easily and minimally controlling the washing of components and the generation of foreign matter, inorganic materials such as silicon (silicon wafer), stainless steel, and aluminum can be used. When these materials are used in semiconductor mounting processes, contamination control is easily implemented, contributing to high yield and stable production. Furthermore, for example, when transferring solder particles formed in the recess 62 onto electrodes on a silicon wafer, if the substrate 60 is made of a silicon wafer, a material with a similar or identical CTE can be used. This reduces the likelihood of positional deviations or warping, allowing for accurate transfer. Methods for forming the recess 62 can utilize laser-based processing, cutting, dry etching or wet etching, electron beam mapping (e.g., FIB processing), etc. Dry etching is widely used in the fabrication of semiconductors, MEMS, etc., enabling the processing of inorganic materials with high precision from the micrometer to the nanometer scale.

[0103] (Inorganic material, single layer (transparent))

[0104] As the substrate 60, glass, quartz, sapphire, etc., can be used. Because these materials are transparent, it is easy to align the solder particles in the recess 62 when transferring them to other substrates on which electrodes are formed. As the method of forming the recess 62, laser-based processing, cutting, dry etching or wet etching, electron beam drawing (e.g., FIB processing), etc., can be used.

[0105] Regarding the advantages of using inorganic materials, they offer superior dimensional stability compared to organic materials. When transferring solder particles from the recess 62 to the electrodes, the transfer can be performed with high positional accuracy. For example, when transferring solder particles to multiple electrodes with micrometer-level dimensions and spacing, using an inorganic material with excellent dimensional stability allows for the transfer of solder particles to the same position on every electrode.

[0106] (Organic-inorganic composite materials)

[0107] The substrate can be composed of multiple materials. Furthermore, the substrate can have multiple layers, each composed of different materials. For example, organic-inorganic composite materials can be used, such as combinations of inorganic materials or combinations of inorganic and organic materials. Combinations of inorganic and organic materials achieve a balance between dimensional stability and the processability of the recess 62. Examples of substrates with combinations of inorganic and organic materials include a substrate layer 601 composed of an inorganic material such as silicon, various ceramics, glass, or stainless steel, and a recess layer 602 composed of an organic material. Such a substrate can be obtained, for example, by forming a photosensitive material film on the surface of a silicon wafer and forming the recess by exposure and development. The inner wall and bottom of the recess 62 can be composed of a photosensitive material, or the inner wall of the recess 62 can be composed of a photosensitive material and the bottom of a silicon wafer. The structure of the recess 62 can be appropriately selected based on purposes such as wettability with solder particles within the recess 62 and ease of transfer to electrodes. When the inner wall and bottom of the recess 62 are made of a photosensitive material, the following method can be used: a photosensitive material layer is formed on the surface of the silicon wafer by forming a photosensitive material film on the surface of the silicon wafer and curing it; a photosensitive material film is then formed again on the surface of this layer, and exposure / development is performed to form the recess 62. In this case, the photosensitive material on the surface of the silicon wafer and the photosensitive material further provided on the outermost layer can have different compositions. Regarding the photosensitive material, appropriate selection can be made considering factors such as the wettability and contamination of solder particles. In particular, when solder particles formed in the recess 62 are transferred to the electrode, the surface of the outermost photosensitive material layer may come into contact with the electrode or the surface of the substrate having the electrode. Therefore, a photosensitive material that does not damage or contaminate the electrode and substrate can be appropriately selected. The photosensitive material can be a material that prevents the leaching of uncured components and contamination caused by halogen-based materials, silicone-based materials, etc. Furthermore, the photosensitive material can be a material with high resistance to reducing atmospheres and fluxes during the transfer of solder particles to the electrode. For example, the photosensitive material can be a material resistant to reducing atmospheres such as formic acid, hydrogen, and hydrogen free radicals. Moreover, the photosensitive material can be a material with high temperature resistance during the transfer of solder particles to the electrode. Specifically, the photosensitive material can be a material resistant to temperatures above 100°C and below 300°C. Since the melting point of solder particles varies depending on their constituent materials, the heat resistance temperature of the photosensitive material can also be selected based on the solder material used. When using tin-silver-copper solders (e.g., SAC305 (melting point 219°C)) widely used as lead-free solders in electronic devices, materials with heat resistance of 220°C or higher, especially 260°C or higher for reflow processes, can be used.When using tin-bismuth solder (e.g., SnBi58 (melting point 139°C)), materials with heat resistance of 140°C or higher can be used; if the heat resistance is 160°C or higher, the industrial applicability expands. When using indium solder (melting point 159°C), materials with heat resistance of 170°C or higher can be used. When using indium-tin solder (e.g., melting point 120°C), materials with heat resistance of 130°C or higher can be used.

[0108] As another substrate, an example is a substrate having recesses 62 formed of thermosetting or thermoplastic resin on a stainless steel plate. This substrate can be obtained by clamping the thermosetting material (resin) between a stainless steel plate and an impression die, applying pressure and heating, and then peeling off the impression die. Another example is a substrate having recesses 62 formed of a photocurable material on a glass plate. This substrate can be obtained by coating the glass plate with the photocurable material, pressing the impression die while exposing it to light to cure the photocurable material, and then peeling off the impression die. When forming the recesses 62 using an impression die, the material composition of the inner wall and bottom of the recesses 62 can be changed depending on the pressure conditions. For example, under relaxed pressure conditions, the inner wall and bottom of the recesses 62 can be made of the same resin material. On the other hand, under stronger pressure conditions, the inner wall of the recesses 62 can be made of a resin material, and the bottom can be made of an inorganic material.

[0109] As the material for the base layer 601, a composite material containing glass fiber, fillers, and resin components can also be used. Examples of composite materials include copper foil laminates for circuit boards. As described above, a recess 62 can be formed by coating the surface of the copper foil laminate with a photosensitive material, thermosetting resin, or photocurable resin. While the copper foil laminate mainly contains a large portion of resin material, its CTE can be set to low by combining it with glass fiber, various fillers, etc., thus ensuring the aforementioned dimensional stability. Furthermore, when electrodes are formed on the copper foil laminate, the recess 62 is also formed on the same copper foil laminate, resulting in the same or similar CTE values ​​for both. This provides the advantage of easy alignment during solder particle transfer within the recess 62 and minimizes the risk of positional deviation.

[0110] The material for the recessed layer 602 can also be a sealing material for encapsulation. The sealing material can be any of solid, liquid, or film-like substances. The recess 62 can be formed by laminating a thin layer of sealing material onto glass, silicon wafers, or similar materials and then applying pressure and heat using an imprinting mold.

[0111] <Manufacturing Method of Components for Solder Bump Formation>

[0112] The manufacturing method of the solder bump forming component 10 includes: a preparation step, preparing a substrate having multiple recesses and solder particles; a receiving step, receiving at least a portion of the solder particles in the recesses; a fusion step, fusing the solder particles received in the recesses to form solder particles in the recesses; and an injection step, disposing of (injecting) a fluidizing agent (mobile phase) in the recesses where solder particles are formed.

[0113] While referring Figures 3-5 The manufacturing method of the solder bump forming component 10 according to the first embodiment will be described.

[0114] First, prepare solder particles and a substrate 60 for containing the solder particles. Figure 3 (a) is a top view schematically representing an example of the base 60. Figure 3 (b) is Figure 3 (a) A cross-sectional view of the Ib-Ib line. Figure 3 The substrate 60 shown in (a) has a plurality of recesses 62. The plurality of recesses 62 can be arranged regularly in a prescribed pattern. The position and number of the plurality of recesses 62 can be set according to the shape, size and pattern of the electrodes to be connected.

[0115] There is no particular limitation on the distance L between adjacent recesses, but it can be set to at least 0.1 times or more than 1 times the average particle size of the solder particles contained therein. The distance L can be adjusted appropriately according to the configuration of the electrodes forming the solder bumps. The distance between recesses does not refer to the distance between the centers of the recesses, but rather to the distance from the edge of the recess opening to the edge.

[0116] The recess 62 of the substrate 60 is preferably formed as a tapered shape in which the opening area increases from the bottom 62a side of the recess 62 towards the surface 60a side of the substrate 60. That is, as Figure 3 (a) and Figure 3 As shown in (b), the width of the bottom 62a of the recess 62 ( Figure 3 (a) and Figure 3 The width of (b) in (a) is preferably greater than the width of the opening in the surface 60a of the recess 62. Figure 3 (a) and Figure 3 The width of (b) is narrow. Furthermore, the dimensions of the recess 62 (width a, width b, volume, cone angle, and depth, etc.) can be set according to the size of the target solder particles.

[0117] Alternatively, the shape of the recess 62 can also be... Figure 3 (a) and Figure 3 Shapes other than those shown in (b). For example, the shape of the opening in the surface 60a of the recess 62, in addition to the shape shown in (b). Figure 3In addition to the circle shown in (a), it can also be an ellipse, triangle, quadrilateral, polygon, etc.

[0118] Furthermore, the shape of the recess 62 in the cross-section perpendicular to surface 60a can be, for example, as shown in the figure below. Figure 4 The shape shown. Figure 4 (a) to (h) are sectional views schematically representing examples of the cross-sectional shape of a recess in a matrix. Figure 4 In any of the cross-sectional shapes shown in (a) to (h), the width (width b) of the opening in the surface 60a of the recess 62 becomes the maximum width in the cross-sectional shape. This makes it easier to remove solder particles formed within the recess 62, improving operability. Furthermore, since the width (width b) of the opening is the maximum width in the cross-sectional shape, when solder particles 1 are transferred to the electrode, they easily detach from the recess 62, leading to an expected increase in transfer rate. Moreover, by appropriately adjusting the width (width b) of the opening, it is difficult for positional deviations to occur when transferring solder particles 1 to the electrode, and solder bumps are easily formed at accurate positions.

[0119] The solder particles prepared in the preparation process only need to include particles whose particle size is smaller than the width (width b) of the opening in the surface 60a of the recess 62, and preferably include more particles whose particle size is smaller than width b. For example, the solder particles preferably have a particle size distribution of D10 smaller than width b, more preferably a particle size distribution of D30 smaller than width b, and even more preferably a particle size distribution of D50 smaller than width b.

[0120] The particle size distribution of solder particles can be determined using various methods that correspond to the size. For example, methods such as dynamic light scattering, laser diffraction, centrifugal sedimentation, inductively coupled plasma mass spectrometry, and resonant mass determination can be used. Furthermore, particle size can be determined from images obtained using optical microscopes, electron microscopes, etc. Specific devices include flow cytometry particle image analysis devices, microtracks, and Coulter counters.

[0121] The CV value of the solder particles prepared in the preparation process is not particularly limited, but from the viewpoint of improving the filling performance of the recess 62 based on the combination of large and small particles, a higher CV value is preferred. For example, the CV value of the solder particles may exceed 20%, preferably 25% or more, and more preferably 30% or more.

[0122] The CV value of solder particles is calculated by multiplying the value obtained by dividing the standard deviation of the particle size measured by the aforementioned method by the average particle size (D50 particle size) by 100.

[0123] Solder particles may contain tin or tin alloys. Examples of tin alloys include In-Sn alloys, In-Sn-Ag alloys, Sn-Au alloys, Sn-Bi alloys, Sn-Bi-Ag alloys, Sn-Ag-Cu alloys, and Sn-Cu alloys. Specific examples of these tin alloys are given below.

[0124] •In-Sn (In 52% by mass, Bi 48% by mass, melting point 118℃)

[0125] •In-Sn-Ag (In 20% by mass, Sn 77.2% by mass, Ag 2.8% by mass, melting point 175℃)

[0126] • Sn-Bi (Sn 43% by mass, Bi 57% by mass, melting point 138℃)

[0127] • Sn-Bi-Ag (Sn 42% by mass, Bi 57% by mass, Ag 1% by mass, melting point 139℃)

[0128] Sn-Ag-Cu (Sn 96.5% by mass, Ag 3% by mass, Cu 0.5% by mass, melting point 217℃)

[0129] Sn-Cu (Sn 99.3% by mass, Cu 0.7% by mass, melting point 227℃)

[0130] Sn-Au (Sn 21.0% by mass, Au 79.0% by mass, melting point 278℃)

[0131] Solder particles may contain indium or indium alloys. Examples of indium alloys include In-Bi alloys and In-Ag alloys. Specific examples of these indium alloys are given below.

[0132] •In-Bi (In 66.3% by mass, Bi 33.7% by mass, melting point 72℃)

[0133] •In-Bi (In 33.0% by mass, Bi 67.0% by mass, melting point 109℃)

[0134] •In-Ag (In 97.0% by mass, Ag 3.0% by mass, melting point 145℃)

[0135] Depending on the intended use of the solder particles (temperature at which they are used), the aforementioned tin alloys or indium alloys can be selected. For example, if solder particles for low-temperature welding are desired, In-Sn alloys or Sn-Bi alloys can be used, resulting in solder particles capable of welding at temperatures below 150°C. Using materials with high melting points, such as Sn-Ag-Cu alloys or Sn-Cu alloys, solder particles that maintain high reliability even after being placed at high temperatures can be obtained.

[0136] Solder particles may contain one or more elements selected from Ag, Cu, Ni, Bi, Zn, Pd, Pb, Au, P, and B. Among these elements, Ag or Cu may be included from the following perspectives: by including Ag or Cu in the solder particles, the following effects are achieved: the melting point of the obtained solder particles can be lowered to approximately 220°C, and better conductivity reliability is obtained by obtaining solder particles with excellent bonding strength to the electrode.

[0137] The Cu content of the solder particles can be, for example, 0.05–10% by mass, or 0.1–5% by mass or 0.2–3% by mass. If the Cu content is 0.05% by mass or more, solder particles that achieve good solder joint reliability are easily obtained. Furthermore, if the Cu content is 10% by mass or less, solder particles with low melting point and excellent wettability are easily obtained, resulting in better connection reliability of electrodes with solder bumps.

[0138] The Ag content of the solder particles can be, for example, 0.05–10% by mass, or 0.1–5% by mass, or 0.2–3% by mass. If the Ag content is 0.05% by mass or higher, solder particles that achieve good solder joint reliability are easily obtained. Furthermore, if the Ag content is 10% by mass or lower, solder particles with low melting point and excellent wettability are easily obtained, resulting in better connection reliability of electrodes with solder bumps.

[0139] In the receiving process, solder particles prepared in the preparation process are received in each of the recesses 62 of the substrate 60. The receiving process may be a process of receiving all the solder particles prepared in the preparation process in the recesses 62, or it may be a process of receiving a portion of the solder particles prepared in the preparation process (for example, solder particles smaller than the width b of the opening of the recess 62) in the recesses 62.

[0140] Figure 5 This is a schematic cross-sectional view showing solder particles 111 contained in the recess 62 of the substrate 60. (Example) Figure 5 As shown, each of the plurality of recesses 62 contains a plurality of solder particles 111.

[0141] The amount of solder particles 111 contained in the recess 62 is preferably 20% or more, more preferably 30% or more, further preferably 50% or more, and most preferably 60% or more, relative to the volume of the recess 62. This suppresses deviations in the amount contained and makes it easier to obtain solder particles with a smaller particle size distribution.

[0142] There is no particular limitation on the method of collecting solder particles in the recess 62. The collection method can be either dry or wet. For example, solder particles prepared in the preparation step can be placed on the substrate 60, and the surface 60a of the substrate 60 can be wiped with a scraper. This removes excess solder particles and collects sufficient solder particles within the recess 62. If the width b of the opening of the recess 62 is greater than the depth of the recess 62, solder particles may sometimes fly out from the opening of the recess 62. If a scraper is used, the solder particles flying out from the opening of the recess 62 are removed. Other methods for removing excess solder particles include blowing compressed air or wiping the surface 60a of the substrate 60 with non-woven fabric or fiber bundles. These methods use weaker physical force compared to scrapers, and are therefore preferred for handling easily deformable solder particles. Furthermore, these methods can also leave solder particles that have flown out from the opening of the recess 62 within the recess.

[0143] The fusion process is a process in which solder particles 111 housed in the recess 62 are fused together (for example, by heating to 130–260°C) to form solder particles 1 inside the recess 62. The solder particles 111 housed in the recess 62 are unified by melting and sphericalized by surface tension. At this time, in the contact portion with the bottom 62a of the recess 62, the molten solder follows the bottom 62a to form a planar portion 11. Thus, the formed solder particles 1 have a planar portion 11 on a part of their surface. In this way, a... Figure 1 The solder bump forming component 10 shown.

[0144] One method for melting the solder particles 111 housed in the recess 62 is to heat the solder particles 111 to a temperature above the melting point of the solder. However, due to the influence of the oxide film, the solder particles 111 may not melt or wet and spread even when heated to a temperature above their melting point, thus failing to coalesce. Therefore, by exposing the solder particles 111 to a reducing atmosphere to remove the surface oxide film, and then heating them to a temperature above their melting point, the solder particles 111 can be melted, wetted, and coalesced. Furthermore, the melting of the solder particles 111 is preferably performed in a reducing atmosphere. By heating the solder particles 111 to a temperature above their melting point and using a reducing atmosphere, the oxide film on the surface of the solder particles 111 is reduced, making the melting, wetting, and coalescing of the solder particles 111 easy and efficient. That is, in the manufacturing method of the component for forming solder bumps, a reduction step may be included before the fusion step, in which solder particles housed in the recess are exposed to a reducing atmosphere. Furthermore, in the fusion step of the manufacturing method of the component for forming solder bumps, the solder particles may be fused under a reducing atmosphere.

[0145] Regarding the method for creating a reducing atmosphere, there are no particular limitations as long as the aforementioned effect is achieved; for example, methods using hydrogen gas, hydrogen radicals, formic acid gas, etc., are acceptable. For instance, by using a hydrogen reduction furnace, a hydrogen radical reduction furnace, a formic acid reduction furnace, or a conveyor furnace or continuous furnace of these, the solder particles 111 can be melted under a reducing atmosphere. These devices can include a heating device, a chamber filled with an inert gas (nitrogen, argon, etc.), and a mechanism for creating a vacuum within the chamber, thereby facilitating the control of the reducing gas. Furthermore, if a vacuum can be created within the chamber, after the solder particles 111 have melted and coalesced, voids can be removed by depressurization, resulting in solder particles 1 with even better bonding stability.

[0146] The distribution of solder particles 111 reduction, melting conditions, temperature, and furnace atmosphere adjustment can be appropriately set considering the melting point, particle size, recess size, and substrate 60 material of the solder particles 111. For example, after inserting the substrate 60 with the recess filled with solder particles 111 into the furnace and performing vacuum extraction, reducing gas is introduced to fill the furnace with reducing gas. After removing the surface oxide film of the solder particles 111, the reducing gas is removed by vacuum extraction. Then, the furnace is heated to above the melting point of the solder particles 111 to melt and unify the solder particles, thereby forming solder particles in the recess 62. After filling with nitrogen, the furnace temperature is returned to room temperature, thereby obtaining solder particles 1. Furthermore, for example, after inserting a substrate 60 containing solder particles 111 in the recess into a furnace and performing vacuum extraction, a reducing gas is introduced to fill the furnace. The solder particles 111 are then heated by a furnace heater to remove the surface oxide film. The reducing gas is then removed by vacuum extraction. The furnace is then heated to above the melting point of the solder particles 111, causing them to melt and coalesce, thus forming solder particles within the recess 62. Nitrogen gas is then added, and the furnace temperature is returned to room temperature, thereby obtaining solder particles 1. Heating the solder particles in a reducing atmosphere has the advantages of increasing reducing power and easily removing the surface oxide film of the solder particles.

[0147] Furthermore, for example, after inserting a substrate 60 filled with solder particles 111 into a furnace and performing vacuum extraction, reducing gas is introduced to fill the furnace. The furnace is then heated by a furnace heater to above the melting point of the solder particles 111. This process removes the surface oxide film of the solder particles 111 through reduction, simultaneously melting and unifying the solder particles, thereby forming solder particles within the recess 62. After removing the reducing gas through vacuum extraction to further reduce the voids within the solder particles, nitrogen is added, and the furnace temperature is returned to room temperature, thus obtaining solder particles 1. In this case, the furnace temperature can be adjusted only once for both rising and falling, thus offering the advantage of processing in a short time.

[0148] After solder particles are formed in the aforementioned recess 62, a process can be added to create a reducing atmosphere in the furnace again to remove any remaining surface oxide film. This reduces residues such as unfused solder particles and parts of the unfused oxide film.

[0149] In the case of using an atmospheric pressure conveying furnace, a substrate 60 with solder particles 111 filling the recess is placed on a conveyor and continuously passed through multiple zones to obtain solder particles 1. For example, the substrate 60 with solder particles 111 filling the recess is placed on a conveyor set at a constant speed, and passes through a zone filled with an inert gas such as nitrogen or argon with a temperature lower than the melting point of the solder particles 111. Then, it passes through a zone containing a reducing gas such as formic acid with a temperature lower than the melting point of the solder particles 111 to remove the surface oxide film of the solder particles 111. Then, it passes through a zone filled with an inert gas such as nitrogen or argon with a temperature higher than the melting point of the solder particles 111 to melt and unify the solder particles 111. Finally, it passes through a cooling zone filled with an inert gas such as nitrogen or argon to obtain solder particles 1. For example, a substrate 60 with solder particles 111 filling the recesses is placed on a conveyor set at a constant speed. It passes through an area filled with an inert gas such as nitrogen or argon at a temperature above the melting point of the solder particles 111, and then through an area filled with a reducing gas such as formic acid at a temperature above the melting point of the solder particles 111. This removes the surface oxide film of the solder particles 111, melting and fusing them. Finally, it passes through a cooling zone filled with an inert gas such as nitrogen or argon, thereby obtaining solder particles 1. The conveyor furnace is capable of processing at atmospheric pressure, thus enabling continuous roll-to-roll processing of film-like materials. For example, in manufacturing a continuous roll product of a substrate 60 with solder particles 111 filling the recesses, a roll uncoiler is installed at the inlet side of the conveyor furnace, and a roll coiler is installed at the outlet side. The substrate 60 is conveyed at a constant speed, passing through various areas within the conveyor furnace, thereby fusing the solder particles 111 filling the recesses.

[0150] From the preparation step to the fusion step, solder particles 1 of uniform size can be formed regardless of the material and shape of the solder particles 111. For example, indium-based solders can be deposited based on electroplating, but they are difficult to deposit in particle form, being soft and difficult to handle. However, in the above method, by using indium-based solder particles as raw materials, indium-based solder particles with uniform particle size can be easily manufactured. Furthermore, the formed solder particles 1 can be processed in a state of being housed in the recess 62 of the substrate 60, thus allowing for handling / storage without deforming the solder particles 1. Moreover, since the formed solder particles 1 are housed in the recess 62 of the substrate 60, they can contact the electrode without deforming the solder particles. The average particle size of the obtained solder particles can be 1 to 35 μm, and the CV value can be 20% or less.

[0151] Furthermore, even if the particle size distribution of solder particles 111 is significantly different, their shape can be deformed. As long as they can be contained within the recess 62, they can be appropriately used as raw materials.

[0152] Furthermore, in the above method, the substrate 60 can freely design the shape of the recess 62 through photolithography, machining, imprinting, etc. The size of the solder particles 1 depends on the amount of solder particles 111 contained in the recess 62, so the size of the solder particles 1 can be freely designed by designing the recess 62.

[0153] Next, in the process of preparing the fluidizing agent, the fluidizing agent is placed in the recess 62 where the solder particles 1 are formed. There are no particular limitations on the method of preparing the fluidizing agent, but examples include immersing the substrate 60 in a liquid fluidizing agent solution and extracting it, coating the liquid fluidizing agent, or dripping it onto the substrate 60 (especially onto the recess 62). Furthermore, in the case of a solid fluidizing agent, methods such as placing a fluidizing agent with a diameter smaller than that of the recess 62 on the surface of the substrate 60 and filling it into the recess 62 using a scraper can be used. Alternatively, methods such as CVD, vapor deposition, or sputtering can be used to prepare the fluidizing agent. Excess fluidizing agent overflowing from the recess 62 can be removed. Examples of removal methods include evaporation based on reduced pressure, scraping, wiping, abrasion, laser etching, and sandblasting.

[0154] For example, an appropriate amount of liquid fluidizing agent is dripped onto the substrate 60 (recess 62), and while spreading the liquid fluidizing agent with a scraper and filling the recess 62, the remaining liquid fluidizing agent that was not filled into the recess 62 can be removed again with a scraper. Fluidizing agent that cannot be completely removed with a scraper can be wiped off, for example, with a lint-free cleaning cloth.

[0155] A method for manufacturing a solder bump forming component 10 may include: a preliminary step of preparing a substrate having multiple recesses, solder particles, and a fluidizing agent; and a preparation step of preparing solder particles and a fluidizing agent in the recesses. Thus, solder particles 1 are temporarily removed from the substrate 60, and the solder particles 1 and fluidizing agent F are then re-prepared in the recesses of the substrate, thereby enabling the fabrication of the solder bump forming component. With this method, solder particles 111 that did not become solder particles 1 during the melting process, solder particles 111 existing outside the recesses 62, and other residues, foreign matter, etc., can be separated from the solder particles 1. Specifically, after the melting process, the substrate 60 containing solder particles 1 within the recesses 62 is immersed in a solvent, and the solder particles 1 are removed from the recesses 62. After the substrate 60 with the removed solder particles 1 is extracted from the solvent, the solvent is passed through a filter, screen, etc., thereby removing foreign matter from the solvent. Then, the solder particles 1 are temporarily dispersed and allowed to stand in the solvent for precipitation separation. By performing precipitation separation, solder particles 1 are separated from residues (e.g., solder microparticles 111 and foreign matter), thereby obtaining a mixture of solder particles 1 and solvent. After repeated precipitation separation to further remove residues, the mixture of solder particles 1 and solvent is vacuum dried to obtain high-purity solder particles 1. In the preparation process, the solder particles 1 are re-prepared into the recess 62 on the surface of the substrate 60. Then, a fluidizing agent can be prepared into the recess 62. Alternatively, the fluidizing agent can be pre-prepared into the recess 62 before preparing the solder particles 1 into the recess 62. Alternatively, the fluidizing agent and solder particles 1 can be pre-mixed and the mixture prepared into the recess 62. The substrate for re-preparing the solder particles can be the substrate used when making the solder particles or a different substrate.

[0156] In addition, as solder particles 1, besides the solder particles obtained by the above methods, solder particles can be produced by known methods such as spraying, water spraying, cutting and melting fine wires, and using a precision spray head to produce tiny solder droplets.

[0157] <Manufacturing Method of Electrode Substrate with Solder Bumps>

[0158] A method for manufacturing an electrode substrate with solder bumps includes: a preparation step, in which the solder bump forming component and a substrate having multiple electrodes are prepared; an arrangement step, in which the surface of the solder bump forming component having a recess is brought into contact with the surface of the substrate having electrodes; and a heating step, in which solder particles are heated to a temperature above the melting point of the solder particles.

[0159] Specific examples of substrates (circuit components) having multiple electrodes on their surface include chip components such as IC chips (semiconductor chips), resistor chips, capacitor chips, and driver ICs; and rigid packaging substrates. These circuit components have circuit electrodes, typically multiple circuit electrodes. Other examples of substrates having multiple electrodes on their surface include wiring substrates such as flexible tape substrates with metal wiring, flexible printed circuit boards, and glass substrates coated with indium tin oxide (ITO).

[0160] Specific examples of electrodes 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 electrodes. Electrodes can be formed by electroless plating, electrolytic plating, sputtering, or etching of metal foil.

[0161] Figure 6 (a) and Figure 6 (b) is a cross-sectional view schematically illustrating an example of the manufacturing process of an electrode substrate with solder bumps. Figure 6 The substrate 60 shown in (a) is in a state where each recess 62 contains a solder particle 1 and a fluidizing agent F. On the other hand, the substrate 2 has multiple electrodes 3 on its surface. The electrode 3 side of the substrate 2 is brought into contact with the opening side of the recess 62 of the substrate 60. The number of solder particles 1 in contact with each electrode 3 is not particularly limited; it can be one particle per electrode or multiple particles per electrode. Furthermore, the force acting between the solder particle 1 and the recess 62 (e.g., intermolecular forces such as van der Waals forces) is greater than the gravity applied to the solder particle 1, so even with the main surface of the substrate 60 facing down, the solder particle 1 will not fall off and will remain in the recess 62. Moreover, at least a portion of the solder particle 1 contacts the bottom and / or inner wall of the recess 62; in the case of a flat portion, the solder particle 1 is in close contact with the recess 62, making it difficult for it to fall off.

[0162] With the solder particles in contact with the electrode, the entire electrode substrate and base 60 are heated to a temperature at least above the melting point of the solder particles 1 (e.g., 130–260°C). This causes the solder particles 1, which become easily flowable due to the heated fluidizing agent F, to melt upon contact with the electrode 3, thereby forming solder bumps on the electrode 3. From the viewpoint of more suitable bonding of the solder particles 1 and the electrode 3, during the heating process, the solder bump forming component 10 and the substrate 2 can be brought into contact under pressure, and the solder particles 1 can be heated to a temperature above their melting point. The pressure state refers to applying a force of approximately 30–600 Pa to the solder bump forming component 10 and the substrate 2 towards each other. Figure 6The state of pressing in the directions of arrows A and B in (a) is as follows. Solder particles 1 are contained in the recesses 62 and pressed against the electrodes. Therefore, even when flowing under the action of the fluidizing agent F, the solder particles 1 in adjacent recesses 62 are difficult to mix with each other, and solder bumps of the same size can be formed only on the desired electrodes. Furthermore, the solder is less likely to bridge adjacent electrodes, thus suppressing short-circuit defects.

[0163] Solder particles 1 oxidize rapidly upon heating in the atmosphere, making it difficult for them to wet and spread onto electrode 3. Therefore, a deoxidizing atmosphere is preferred during heating. For example, an inert gas atmosphere such as nitrogen or argon, or a vacuum atmosphere, can be used. As the furnace, reflow ovens (under a nitrogen atmosphere) and vacuum reflow ovens commonly used in solder bonding processes can be used, including conveyor-type reflow ovens under a nitrogen atmosphere and intermittent (chamber-type) reflow ovens. When using these reflow ovens, adding a step of setting a vacuum after the solder melts can remove air bubbles (voids) within the solder. Furthermore, from the viewpoint of improving productivity, a laminator can be used. A roller laminator can simultaneously apply pressure and heat. A vacuum-pressurized laminator can also be used. The vacuum-pressurized laminator can maintain a vacuum within the chamber and simultaneously apply pressure and heat, making it easier to transfer solder bumps onto electrode 3, thus it is preferred. Furthermore, continuous conveying based on a carrier film is possible, thus also providing the advantage of improved productivity.

[0164] Due to the influence of the oxide film, solder particles 1 sometimes fail to melt or wet-spread even when heated to temperatures above their melting point. Therefore, by exposing solder particles 1 to a reducing atmosphere to remove the surface oxide film, and then heating them to a temperature above their melting point, the solder particles 1 can be melted. Furthermore, the melting of solder particles 1 is preferably performed in a reducing atmosphere. By heating the solder particles 1 to above their melting point and using a reducing atmosphere, the oxide film on the surface of the solder particles 1 is reduced, and further, the oxide film on the electrode surface is reduced, making the melting and wet-spreading of the solder particles 1 easy and efficient. In other words, in the method for manufacturing an electrode substrate with solder bumps, a reduction step of exposing the solder particles (and / or electrodes) to a reducing atmosphere can be included before the placement step, or after the placement step and before the heating step. Furthermore, in the heating step of the method for manufacturing an electrode substrate with solder bumps, the solder particles can be heated to a temperature above their melting point in a reducing atmosphere. In the heating process of forming solder bumps on the electrode, by bringing the electrode and the opening face of the solder bump forming component into close contact (as needed under pressure), solder bumps are formed only on the electrode, which easily suppresses solder-based bridging between adjacent electrodes.

[0165] For details regarding the reducing atmosphere, please refer to the documentation on the manufacturing method of components for solder bump formation.

[0166] After the heating process, the entire assembly is cooled, and the solder bumps 1A formed on the electrode 3 and the molten solder particles 1 are fixed together, thereby electrically connecting the two. In the method for manufacturing an electrode substrate with solder bumps, a removal process can be performed after the heating process to remove the solder bump forming component from the substrate. After forming the solder bumps 1A on the electrode 3, the solder bump forming component 10 can be removed from the substrate 2 (removal process) to obtain an electrode substrate 20 with solder bumps. Figure 6 (b) is a schematic diagram of the electrode substrate 20 with solder bumps thus obtained.

[0167] On the obtained electrode substrate 20 with solder bumps, there may be solder particles 1 that have detached from the recess 62 but have not bonded to the electrode 3. Therefore, in the method for manufacturing the electrode substrate with solder bumps, a cleaning step can be included after the removal step to remove the solder particles 1 that have not bonded to the electrode. Examples of cleaning methods include blowing compressed air or wiping the substrate surface with nonwoven fabric or fiber bundles. Furthermore, if the fluidizing agent F is present as residue on the electrode substrate 20 with solder bumps, this fluidizing agent can also be removed by the cleaning step. In the cleaning step, a solution that easily dissolves the fluidizing agent F can be used.

[0168] According to the manufacturing method of the electrode substrate with solder bumps, it is possible to obtain an electrode substrate 20 with solder bumps having a substrate 2, an electrode 3 and a solder bump 1A in sequence.

[0169] <Manufacturing Method of Connecting Structures>

[0170] Figure 7 (a) and Figure 7 (b) is a cross-sectional view schematically illustrating an example of the manufacturing process of a connecting structure. (See reference...) Figure 7 (a) and Figure 7 (b) will explain the manufacturing method of the connecting structure. First, prepare in advance... Figure 6 The electrode substrate 20 with solder bumps is shown in (b). Another substrate 4 with multiple other electrodes 5 on its surface is prepared. Both are configured such that solder bumps 1A are opposite the other electrodes 5. Then, in the thickness direction of the stack of these components (… Figure 7Pressurization is applied in the direction of arrows A and B shown in (a). During pressurization, the entire assembly is heated to a temperature at least above the melting point of the solder bump 1A (e.g., 130–260°C), causing the solder bump 1A to melt between the electrode 3 and the other electrodes 5. Afterward, the entire assembly is cooled, forming a solder layer 1B between the electrode 3 and the other electrodes 5, thereby establishing an electrical connection between the electrodes. To suppress oxidation of the solder bump 1A and the electrode 5, heating is preferably performed in an oxygen-blocking atmosphere. For example, heating in an inert gas atmosphere such as nitrogen is preferred. Specifically, a vacuum reflow oven, a nitrogen reflow oven, or the like can be used.

[0171] Furthermore, in order to melt the solder bump 1A by heating and to more effectively bond the opposing electrodes 3 and 5, heating is preferably performed in a reducing atmosphere. Hydrogen, hydrogen radicals, formic acid, etc., can be used to create a reducing atmosphere. Specifically, a hydrogen reduction furnace, a hydrogen reflow furnace, a hydrogen radical furnace, a formic acid furnace, a vacuum furnace, a continuous furnace, or a conveyor furnace can be used. By creating a reducing atmosphere, the oxide film on the surface of the solder bump 1A and the oxide film on the surface of the electrode 5 can be reduced and removed, thus allowing the solder bump 1A to easily wet and spread on the electrode 5, achieving a more stable bond between the electrode 3 and the electrode 5 via the solder layer 1B.

[0172] Furthermore, pressure can be applied to achieve a stable connection. (Preparation in advance) Figure 6 The electrode substrate 20 with solder bumps is shown in (b). Another substrate 4 with multiple other electrodes 5 on its surface is prepared. Both are configured such that solder bumps 1A are opposite the other electrodes 5. Then, in the thickness direction of the stack of these components (… Figure 7 Pressurization is applied in the direction of arrows A and B shown in (a). During pressurization, the entire assembly is heated to a temperature at least above the melting point of the solder bump 1A (e.g., 130–260°C), causing the solder bump 1A to melt between the electrode 3 and the other electrodes 5. Afterward, the entire assembly is cooled, forming a solder layer 1B between the electrode 3 and the other electrodes 5, thereby establishing an electrical connection between the electrodes. In this case, to suppress oxidation of the solder bump 1A, the electrode 5, and the surface of the electrode 3, the above process is preferably performed under vacuum, in an inert gas atmosphere such as nitrogen, or a reducing atmosphere. Examples of reducing atmospheres include hydrogen, hydrogen radicals, and formic acid. Specifically, hydrogen reduction furnaces, hydrogen reflux furnaces, hydrogen radical furnaces, formic acid furnaces, vacuum furnaces, continuous furnaces, and conveyor furnaces can be used.

[0173] As a method for setting a reducing atmosphere, materials with reducing properties can be used. For example, flux materials or materials containing flux components can be placed near solder bump 1A, electrode 5, and electrode 3. Pastes, films, etc., containing flux materials or materials containing flux components can be used. First, preparation is made in advance. Figure 6 The electrode substrate 20 with solder bumps shown in (b) is used. Flux material or a paste containing flux components is disposed on the entire surface of the electrode substrate 20 where the solder bumps 1A are formed, or near the solder bumps 1A and the electrode 3 containing the solder bumps 1A. Another substrate 4 with a plurality of other electrodes 5 on its surface is prepared. Both are arranged such that the solder bumps 1A are opposite the other electrodes 5. Then, while the solder bumps 1A are in contact with the other electrodes 5, for example via flux material or a paste containing flux components, the substrate is heated to at least a temperature higher than the melting point of the solder bumps 1A (e.g., 130°C to 260°C), whereby the solder bumps 1A melt between the electrode 3 and the other electrodes 5. Afterwards, by cooling the entire substrate, a solder layer 1B is formed between the electrode 3 and the other electrodes 5, thereby establishing an electrical connection between the electrodes. Afterwards, by cleaning to remove the flux components, corrosion of the solder layer 1B, electrode 3, and electrode 5 caused by flux residue can be suppressed.

[0174] As another method, preparation in advance Figure 6 The electrode substrate 20 with solder bumps is shown in (b). Another substrate 4 with a plurality of other electrodes 5 on its surface is prepared, and flux material or a paste containing flux components is disposed on the entire surface of the substrate 4 having the electrodes 5, or near the surface of the electrodes 5. Both are arranged such that solder bump 1A is opposite to the other electrodes 5. Then, while the solder bump 1A is in contact with the other electrodes 5, for example via flux material and a paste containing flux components, it is heated to at least a temperature higher than the melting point of the solder bump 1A (e.g., 130°C to 260°C), whereby the solder bump 1A melts between the electrode 3 and the other electrodes 5. Afterwards, by cooling the entire assembly, a solder layer 1B is formed between the electrode 3 and the other electrodes 5, thereby achieving electrical connection between the electrodes.

[0175] Furthermore, films containing flux components can also be used. Preparation in advance. Figure 6 The electrode substrate 20 with solder bumps shown in (b) is provided. A thin film containing flux is disposed on the side of the electrode substrate 20 on which the solder bumps 1A are formed. Another substrate 4 with a plurality of other electrodes 5 on its surface is also prepared. Both are arranged such that the solder bumps 1A are opposite the other electrodes 5. Then, while the solder bumps 1A are in contact with the other electrodes 5 via the thin film containing flux, or while pressure is applied between the opposing electrodes 3 and 5 to squeeze the thin film containing flux between them, thereby keeping the solder bumps 1A in contact with the electrodes 5, the substrate is heated to at least a temperature higher than the melting point of the solder bumps 1A (e.g., 130°C to 260°C), whereby the solder bumps 1A melt between the electrodes 3 and the other electrodes 5. Afterwards, by cooling the entire substrate, a solder layer 1B is formed between the electrodes 3 and the other electrodes 5, thereby achieving electrical connection between the electrodes.

[0176] The paste and film containing flux components can contain thermosetting materials. Thus, while melting the solder bump 1A, the thermosetting components solidify, thereby fixing the electrode substrate 20 and the substrate 4. The solidification of the thermosetting material differs from the melting and heating of the solder bump 1A and can be achieved by reheating in a subsequent process. Furthermore, the film containing flux components can be pre-positioned on the side of the substrate 4 where the electrode 5 is formed. The choice of whether to position the film containing flux components on the side of the solder bump 1A or on the side of the substrate 4 with the electrode 5 can be appropriately selected based on the shape of the electrode, the shape and size of the solder bump 1A, and the bonding process.

[0177] As a heating method for melting solder bump 1A, there are methods such as heating a heating plate in a reflow oven under vacuum, for example, and transferring the heat to the solder bump 1A via substrates 2 and 4 in contact with the heating plate, and methods using radiation such as infrared rays. Furthermore, in addition to the aforementioned heating methods using heating plates and infrared rays, or using them simultaneously, methods can be used to heat the solder bump 1A using heated gas. Specifically, the solder bump 1A can be heated by heating an inert gas, nitrogen, hydrogen, hydrogen radicals, and formic acid. The flux material and flux composition may include at least one selected from the group consisting of succinic acid, glutaric acid, adipic acid, pimelic acid, octanoic acid, benzoic acid, and malic acid.

[0178] Other methods include those utilizing electromagnetic waves such as microwaves. For example, specific electromagnetic waves can be applied externally to heat the components of electrodes 3, 5, and solder bump 1A. For instance, if substrates 4 and 2 are resin substrates, irradiating them with specific electromagnetic waves from the outside allows the waves to penetrate substrates 4 and 2, heating electrodes 3 and solder bump 1A or electrode 5. In this method, the desired bonding portions can be selectively heated, thus eliminating the advantage of residual thermal paths. For example, even if substrates 2 and 4 are made of materials with low heat resistance, solder bump 1A can be melted to reliably bond electrodes 3 and 5. Furthermore, since residual thermal paths are minimal in the bonded system, it is advantageous to easily suppress warping and decomposition after bonding. Moreover, when using microwaves, compared to methods such as heating plates, infrared rays, or heated gases, solder bump 1A can be melted in a shorter time, thus reducing the thermal path across the entire bonded system and easily achieving the aforementioned effects. Furthermore, if microwaves are used, only the portions of electrode 3, solder bump 1A, and electrode 5 that are to be joined or melted can be locally heated. Therefore, without heating the entire system, even if materials with low heat resistance or other electronic components that do not want to be heated are near electrode 3 and electrode 5, solder bump 1A can be melted and joined.

[0179] As another method, the use of ultrasound can be cited. For example, if an ultrasonic transducer is placed on the side of substrate 2 opposite to electrode 3 and ultrasound is applied, the solder bump 1A is melted by the vibration energy of the ultrasound. Thus, electrode 3 and electrode 5, which are pre-positioned opposite to electrode 3, are bonded via solder layer 1B. Since ultrasonic bonding can melt the solder bump 1A in a short time, it is not necessary to heat the entire substrate 2 and substrate 4. Even if substrate 2 and substrate 4 are made of materials with low heat resistance, electrode 3 and electrode 5 can be reliably bonded.

[0180] Figure 7 (b) is a schematic diagram of the connection structure 30 obtained in this way. That is, Figure 7(b) schematically illustrates the state in which the electrode 3 of substrate 2 is connected to the other electrode 5 of another substrate 4 via a solder layer 1B formed by fusion. In this specification, "fusion" refers to a state in which at least a portion of the electrode is joined by solder (solder bump 1A) that melts due to heat, and then solder is bonded to the surface of the electrode through a curing process. The connection structure 30 may include: a first circuit component having a substrate and a plurality of electrodes on its surface; a second circuit component having another substrate and a plurality of other electrodes on its surface; and a solder layer between the plurality of electrodes and the plurality of other electrodes. Furthermore, the space between the first circuit component and the second circuit component may be filled, for example, with an epoxy resin-based underfill material.

[0181] Examples of applications for connecting structures include connectors for semiconductor memories and semiconductor logic chips, connectors for primary and secondary mounting of semiconductor packages, assemblies for CMOS image elements, laser elements, and LED light-emitting elements, and devices that use these connectors such as cameras, sensors, liquid crystal displays, personal computers, mobile phones, smartphones, and tablets.

[0182] The preferred embodiments of the present invention have been described above, but the present invention is not limited to the above embodiments.

[0183] Example

[0184] The present invention will be described in more detail below through embodiments, but the present invention is not limited to these embodiments.

[0185] <Fabrication of a Film for Solder Bump Formation>

[0186] (Production example 1)

[0187] Process a1: Grading of solder particles

[0188] 100g of Sn-Bi solder particles (manufactured by 5N Plus, melting point 139℃, Type 8) were immersed in distilled water, ultrasonically dispersed, and then allowed to stand. The solder particles suspended in the supernatant were recovered. This operation was repeated, and 10g of solder particles were recovered. The average particle size of the obtained solder particles was 1.0μm, and the CV value was 42%.

[0189] Process b1: Placement of substrate

[0190] A substrate (polyimide film, 100 μm thick) with multiple recesses having an opening diameter of 2.3 μm φ, a bottom diameter of 2.0 μm φ, and a depth of 2.0 μm (when viewed from above, the bottom diameter of 2.0 μm φ is located in the center of the opening diameter of 2.3 μm φ) as shown in Table 1 was prepared. The multiple recesses were arranged regularly at 1.0 μm intervals. Solder particles (average particle size 1.0 μm, CV value 42%) obtained in step a were disposed in the recesses of the substrate. Furthermore, excess solder particles were removed by wiping the recessed side of the substrate with a micro-adhesion roller, thereby obtaining a substrate in which solder particles were disposed only within the recesses.

[0191] Process c1: Formation of solder particles

[0192] The substrate with solder particles arranged in the recess in step b1 is placed in a hydrogen reduction furnace (manufactured by SHINKO SEIKI CO.,LTD., vacuum welding equipment). After vacuum extraction, hydrogen gas is introduced into the furnace to fill it with hydrogen. Then, the furnace is maintained at 280°C for 20 minutes, followed by vacuum extraction again, introduction of nitrogen gas to return to atmospheric pressure, and then the temperature inside the furnace is lowered to room temperature. This process forms solder particles inside the recess.

[0193] <Evaluation of solder particles>

[0194] A portion of the substrate obtained in process c1 was fixed onto the surface of a SEM observation base, and platinum sputtering was performed on the surface. Using SEM, the diameter of 300 solder particles was measured, and the average particle size and CV value were calculated. The results are shown in Table 2. Furthermore, a laser microscope (Olympus Corporation, LEXT OLS5000-SAF) was used to measure the surface shape of the portion of the substrate obtained in process c1, and the height of the solder particles from the substrate surface was measured, calculating the average value of the 300 particles. The results are shown in Table 2.

[0195] Process d1: Flux preparation

[0196] A mobile phase is prepared by mixing 20 parts by mass of adipic acid with 90 parts by mass of dihydroterpineol as a fluxing agent. This mobile phase is then placed into the recesses containing solder particles obtained in step c1. Next, the recessed surfaces of the substrate are wiped with a rubber scraper to remove excess mobile phase (fluxing agent) not filling the recesses. Finally, the substrate surface is further wiped with a lint-free cleaning cloth to create a solder bump forming film.

[0197] (Production examples 2 to 6)

[0198] Except for changes to the recess dimensions as described in Table 1, a solder bump forming film was fabricated in the same manner as in Example 1, and its quality was evaluated. The results are shown in Table 2.

[0199] (Production example 7)

[0200] Except for performing step c2 instead of step c1, a solder bump forming film was fabricated in the same manner as in Example 1, and its quality was evaluated. The results are shown in Table 2.

[0201] Process c2: Formation of solder particles

[0202] In step b1, the substrate with solder particles arranged in the recess is placed into a hydrogen radical reduction furnace (manufactured by SHINKO SEIKICO., LTD., plasma reflow apparatus). After vacuum extraction, hydrogen gas is introduced into the furnace, filling it with hydrogen. The furnace temperature is then adjusted to 120°C, and hydrogen radicals are irradiated for 5 minutes. Afterward, the hydrogen gas in the furnace is removed by vacuum extraction, and the temperature is heated to 170°C. Nitrogen gas is then introduced into the furnace, which is then returned to atmospheric pressure. The furnace temperature is then lowered to room temperature, thereby forming solder particles.

[0203] (Production examples 8 to 12)

[0204] Except for changes to the recess dimensions as described in Table 1, a solder bump forming film was fabricated in the same manner as in Example 7, and its performance was evaluated. The results are shown in Table 2.

[0205] (Production example 13)

[0206] Except for performing step c3 instead of step c1, a solder bump forming film was fabricated in the same manner as in Example 1, and its quality was evaluated. The results are shown in Table 2.

[0207] Process c3: Formation of solder particles

[0208] The substrate with solder particles arranged in the recess in step b1 is placed into a formic acid reduction furnace. After vacuum extraction, formic acid gas is introduced into the furnace, filling it with formic acid gas. The furnace temperature is then adjusted to 130°C and maintained for 5 minutes. Next, the formic acid gas is removed from the furnace using vacuum extraction, and the temperature is heated to 180°C. Nitrogen gas is then introduced into the furnace and returned to atmospheric pressure. The furnace temperature is then lowered to room temperature, thereby forming solder particles.

[0209] (Production examples 14 to 18)

[0210] Except for changes to the recess dimensions as described in Table 1, a solder bump forming film was manufactured in the same manner as in Manufacturing Example 13, and its performance was evaluated. The results are shown in Table 2.

[0211] (Production example 19)

[0212] Except for performing step c4 instead of step c1, a solder bump forming film was fabricated in the same manner as in Example 1, and its quality was evaluated. The results are shown in Table 2.

[0213] Process c4: Formation of solder particles

[0214] The substrate with solder particles arranged in the recess in step b1 is placed into a formic acid conveying reflow oven (manufactured by Heller Industries, Inc., 1913MK). While being conveyed by a conveyor, it continuously passes through a nitrogen zone, a nitrogen and formic acid gas mixing zone, and another nitrogen zone, all set at 190°C. After passing through the nitrogen and formic acid gas mixing zone for 20 minutes, solder particles are formed in the recess.

[0215] (Production examples 20 to 24)

[0216] Except for changes to the recess dimensions as described in Table 1, a solder bump forming film was manufactured in the same manner as in Manufacturing Example 19, and its performance was evaluated. The results are shown in Table 2.

[0217] [Table 1]

[0218]

[0219] [Table 2]

[0220]

[0221] <Fabrication of Evaluation Chips with Solder Bumps>

[0222] Process e1: Preparation for chip evaluation

[0223] Seven types of chips with gold bumps (3.0×3.0mm, thickness: 0.5mm) were prepared as shown below.

[0224] Chip C1… Area: 100μm × 100μm, Spatial: 40μm, Height: 10μm, Number of bumps: 362

[0225] Chip C2… Area: 75μm × 75μm, Spatial: 20μm, Height: 10μm, Number of bumps: 362

[0226] Chip C3… Area: 40μm × 40μm, Spatial: 16μm, Height: 7μm, Number of bumps: 362

[0227] Chip C4… Area: 20μm × 20μm, Spatial: 7μm, Height: 5μm, Number of bumps: 362

[0228] Chip C5… Area: 10μm × 10μm, Spatial: 6μm, Height: 3μm, Number of bumps: 362

[0229] Chip C6… Area: 10μm × 10μm, Spatial: 4μm, Height: 3μm, Number of bumps: 362

[0230] Chip C7… Area: 5μm × 10μm, Spatial: 3μm, Height: 2μm, Number of bumps: 362

[0231] Process f1: Forming solder bumps (without using formic acid gas)

[0232] Following the sequence shown below (i) to (iii), solder bumps were formed on a chip with gold bumps (3.0 × 3.0 mm, thickness: 0.5 mm) using the solder bump forming film (manufacturing example 7) prepared in step c2.

[0233] i) A 0.3 mm thick glass plate was placed on the heating plate, and the evaluation chip was placed on the glass plate with the gold bumps facing upwards.

[0234] ii) The solder bump forming film is configured such that the opening side of the recessed portion faces downward, so that the gold bump surface of the evaluation chip contacts the solder bump forming film. Furthermore, a glass plate with a thickness of 0.3 mm is placed on the solder bump forming film, and a stainless steel ingot is placed on the glass plate so that the solder bump forming film is in close contact with the gold bump.

[0235] iii) A bell-shaped glass dome was prepared into which nitrogen gas was blown in. This dome was used to cover the sample prepared in ii) with a solder bump forming film stacked on it. Next, nitrogen gas was introduced into the glass dome, placing the entire sample under a nitrogen atmosphere. The hot plate of the heating element was heated to 160°C and heated for 5 minutes. Afterward, the heating element was allowed to return to room temperature, the nitrogen gas was stopped, and the atmosphere was opened. The topmost spindle, glass plate, and solder bump forming film were removed in that order. The evaluation chip was then immersed in a methanol solution, the mobile phase was washed away, and vacuum dried (at 40°C for 60 minutes) to obtain an evaluation chip with solder bumps.

[0236] <Evaluation of solder bumps: No formic acid gas used>

[0237] The evaluation chip obtained through process f1 was fixed onto the surface of a SEM observation base, and platinum sputtering was performed on the surface. For 30 gold bumps, the number of solder bumps mounted on the gold bumps was counted using SEM, and the average number of solder bumps mounted on one gold bump was calculated. The results are shown in Table 3. Furthermore, the height of the solder bumps from the gold bumps was measured using a laser microscope (Olympus Corporation, LEXT OLS5000-SAF), and the average value of 100 bumps was calculated. The results are shown in Table 3.

[0238] Except for using the solder bump forming film of Examples 8 to 12 instead of the solder bump forming film of Example 7, solder bump formation and evaluation were performed in the same manner as described above.

[0239] The evaluation results are shown in Table 3.

[0240] (Compare with Example 1)

[0241] Except for omitting step d1 (flux preparation), a comparative solder bump forming film with solder particles in the recess was fabricated in the same manner as in Example 8. Solder bump formation and evaluation were performed using the same method as in step f1, except that the comparative solder bump forming film was used. The results are shown in Table 3.

[0242] [Table 3]

[0243]

[0244] In Examples 7-12, solder bumps were formed on the gold bumps of the evaluation chip. However, in Comparative Example 1, no solder bumps were observed on the gold bumps regardless of the type of evaluation chip.

[0245] In the recess of Comparative Example 1, there was no mobile phase containing flux, so the surface oxide film of the solder particles was not reduced, and no wetting spread of the solder particles on the gold bump was generated.

[0246] A mobile phase containing flux components is contained within the recess along with solder particles. Heating the flux components removes the oxide film on the surface of the solder particles and also cleans the surface of the gold bumps (electrodes). Furthermore, the solder particles melt and are moved to the surface of the gold bumps by the mobile phase, thereby forming solder bumps on the gold bumps. Figure 1As shown, the mobile phase exists within the recess. Therefore, the mobile phase removes the oxide film near the surface of the solder particles opposite the gold bump (electrode), activating the contact between the solder particles and the gold bump. Heating is performed with the opening surface of the recess in contact with the surface of the gold bump, allowing the solder particles to contact the surface of the gold bump. At this time, due to the presence of the recess wall, the flow of solder particles and flux towards the surface of the component used for forming solder bumps is suppressed, enabling the formation of solder bumps on the gold bump. Furthermore, for the same reason, solder particles in adjacent recesses are difficult to bond with each other, resulting in the formation of good solder bumps. Depending on the heating temperature and time during bump formation, it is necessary to control the amount of wetting spread on the gold bump surface. However, since the solder particles and flux are pressed against the gold bump surface in a state of being contained within the recess, it is difficult for adjacent solder particles to bond with each other for the aforementioned reasons, resulting in a high likelihood of bonding between heating temperature and time. Therefore, stable solder bump formation for industrial use is achieved. Furthermore, a small amount of flux components and solder particles were found in the areas without gold bumps, but these were removed by cleaning the evaluation chip in methanol. The recessed opening faces the evaluation chip surface other than the gold bumps, but because the gold bumps are higher than other surfaces, the recessed opening is difficult to contact, making it difficult for solder particles to move to the evaluation chip side. Even when a portion of the recessed opening contacts the evaluation chip side, there is no solder-wetted metal (electrode), so it can be easily removed by subsequent cleaning. Moreover, as mentioned earlier, the presence of solder particles and flux within the recess suppresses solder particle flow in the surface direction of the solder bump forming component, thus reducing the likelihood of short-circuit defects caused by gold bumps.

[0247] As in Comparative Example 1, without a mobile phase, even heating cannot fully reduce the surface oxide film of the solder particles, and it is difficult to make the solder particles flow to the gold bumps (electrode), making it difficult to stably form solder bumps.

[0248] Process f2: Forming solder bumps (using formic acid gas)

[0249] Following the sequence shown below (i) to (iii), solder bumps were formed on a chip with gold bumps (3.0 × 3.0 mm, thickness: 0.5 mm) using the solder bump forming film (manufacturing example 7) prepared in step c2.

[0250] i) A 0.3mm thick glass plate was placed on a 5mm thick stainless steel plate, and an evaluation chip was placed on the glass plate with the gold bumps facing upwards.

[0251] ii) The solder bump forming film is configured such that the opening side of the recessed portion faces downward, so that the gold bump surface of the evaluation chip contacts the solder bump forming film. Furthermore, a glass plate with a thickness of 0.3 mm is placed on the solder bump forming film, and a stainless steel ingot is placed on the glass plate so that the solder bump forming film is in close contact with the gold bump.

[0252] iii) The stainless steel plate prepared in ii) was placed on a belt conveyor in a formic acid reflux furnace (Heller Industries Inc. 1936MKV) and flowed at a speed of 40 mm / s. Inside the furnace, the sample first passed through a nitrogen zone. At this time, oxygen around the sample was removed. Then it passed through a nitrogen zone heated to 150°C, and further through a formic acid gas (4%) zone at 180°C, and then into a vacuum chamber set at 160°C. After the vacuum chamber was closed, it was kept under vacuum for 1 minute, nitrogen was introduced to return it to atmospheric pressure, and then the sample left the vacuum chamber and returned to room temperature through a nitrogen atmosphere cooling zone. The topmost spindle, glass plate, and solder bump forming film were removed in that order. Next, the evaluation chip was immersed in a methanol solution and the mobile phase was washed away, and then vacuum dried (at 40°C for 60 minutes) to obtain an evaluation chip with solder bumps.

[0253] <Evaluation of solder bumps: using formic acid gas>

[0254] The evaluation chip obtained through process f2 was fixed onto the surface of a SEM observation base, and platinum sputtering was performed on the surface. For 30 gold bumps, the number of solder bumps mounted on the gold bumps was counted using SEM, and the average number of solder bumps mounted on one gold bump was calculated. The results are shown in Table 3. Furthermore, the height of the solder bumps from the gold bumps was measured using a laser microscope (Olympus Corporation, LEXT OLS5000-SAF), and the average value of 100 bumps was calculated. The results are shown in Table 4.

[0255] Except that the solder bump forming film of Examples 8-12 was used instead of the solder bump forming film of Example 7, solder bump forming and evaluation were performed in the same manner as in step f2. The evaluation results are shown in Table 4.

[0256] Except for using the comparative solder bump forming film obtained in Comparative Fabrication Example 1, solder bump formation and evaluation were performed using the same method as in step f2. The results are shown in Table 4.

[0257] [Table 4]

[0258]

[0259] In Examples 7-12, solder bumps were formed on the gold bumps. In particular, compared with the case without a formic acid gas atmosphere (Table 3), there was a tendency for the number of solder bumps to increase. This is believed to be because the surface oxide film of the solder particles in the recess is fully reduced by the flux components contained in the mobile phase and the formic acid gas, and the organic matter on the surface of the gold pad is also removed by the formic acid gas, thus making it easier for solder bumps to form on the gold bumps. When the solder bumps obtained using a formic acid gas atmosphere are observed using a microscope and an electron microscope, there is less spherical deformation compared with the solder bumps obtained without a formic acid gas atmosphere. This is believed to be because the vacuum chamber is created after heating, thereby removing air bubbles in the solder bumps, and the low molecular weight components of the mobile phase are also fully evaporated, thus the solder bumps become spherical with less deformation.

[0260] In Comparative Example 1, solder bump formation was confirmed on the gold bumps, but compared to Examples 7-12, the number of bumps tended to be smaller. Even when using the same Comparative Example 1, no solder bump formation was observed when no formic acid gas atmosphere was set, but when a formic acid gas atmosphere was set, some solder particles in the recesses had their surface oxide film removed by the formic acid gas, and a certain amount was placed on the gold bumps. However, since the recess side was pressed against the gold bumps, it was considered that the formic acid gas did not sufficiently remove the surface oxide film of the solder particles in the recesses.

[0261] <Construction of Connecting Structures>

[0262] Process g1: Preparation of the evaluation substrate

[0263] Seven types of substrates with gold bumps (70×25mm, thickness: 0.5mm) were prepared as shown below. Additionally, lead wires for resistance measurement were formed within these gold bumps.

[0264] Substrate D1… Area: 100μm × 100μm, Spacing: 40μm, Height: 4μm, Number of bumps: 362

[0265] Substrate D2… Area: 75μm × 75μm, Spacing: 20μm, Height: 4μm, Number of bumps: 362

[0266] Substrate D3… Area: 40μm × 40μm, Spacing: 16μm, Height: 4μm, Number of bumps: 362

[0267] Substrate D4… Area: 20μm × 20μm, Spacing: 7μm, Height: 4μm, Number of bumps: 362

[0268] Substrate D5… Area: 10μm × 10μm, Spacing: 6μm, Height: 3μm, Number of bumps: 362

[0269] Substrate D6… Area: 10μm × 10μm, Spacing: 4μm, Height: 3μm, Number of bumps: 362

[0270] Substrate D7… Area: 5μm × 10μm, Spacing: 3μm, Height: 3μm, Number of bumps: 362

[0271] Process h1: Electrode bonding

[0272] Following the sequence shown below (i) to (iii), the evaluation chip with solder bumps produced in step f1 is connected to the evaluation substrate with gold bumps via solder bumps.

[0273] i) An evaluation substrate was placed with the gold bumps facing upwards on the lower hot plate of a formic acid reflux furnace (SHINKO SEIKI CO., LTD., intermittent vacuum welding apparatus).

[0274] ii) The evaluation chip with solder bumps formed is positioned with the solder bump face down, and is fixed in such a way that the gold bump face of the evaluation substrate contacts the solder bumps, so as not to move.

[0275] iii) The formic acid vacuum reflux furnace was operated, and after vacuum evacuation, formic acid gas was filled in. The lower hot plate was heated to 180°C and heated for 5 minutes. Afterwards, the formic acid gas was removed by vacuum evacuation, nitrogen purging was performed, the lower hot plate was returned to room temperature, and the furnace was opened to the atmosphere. An appropriate amount of underfill material (manufactured by Hitachi Chemical Co., Ltd., CEL series) with adjusted viscosity was placed between the evaluation chip and the evaluation substrate. After filling using vacuum evacuation, it was cured at 165°C for 2 hours, thus fabricating the connection structure between the evaluation chip and the evaluation substrate. The combination of materials in the connection structure is as follows.

[0276] (1) Chip C1 / Solder bump forming film / Substrate D1

[0277] (2) Chip C2 / Solder bump forming film / Substrate D2

[0278] (3) Chip C3 / Solder bump forming film / Substrate D3

[0279] (4) Chip C4 / Solder bump forming film / Substrate D4

[0280] (5) Chip C5 / Solder bump forming film / Substrate D5

[0281] (6) Chip C6 / Solder bump forming film / Substrate D6

[0282] (7) Chip C7 / Solder bump forming film / Substrate D7

[0283] <Evaluation of the connection structure>

[0284] The continuity resistance test and insulation resistance test were performed on a portion of the obtained connection structure as follows.

[0285] (Conductivity Resistance Test - Moisture Absorption and Heat Resistance Test)

[0286] Regarding the on-resistance between the chip (bump) with gold bumps and the substrate (bump) with gold bumps, the initial value of the on-resistance and the value after moisture absorption and heat resistance tests (placed at 85°C and 85% humidity for 100, 500, and 1000 hours) were measured for 20 samples, and the average value of these values ​​was calculated.

[0287] The on-resistance was evaluated based on the obtained average values ​​according to the following criteria. The results are shown in Table 5. Furthermore, after 1000 hours of moisture absorption and heat resistance testing, if criteria A or B below are met, the on-resistance can be considered good.

[0288] A: The average on-resistance is less than 2Ω.

[0289] B: The average on-resistance is greater than 2Ω and less than 5Ω.

[0290] C: The average on-resistance is 5Ω or higher and less than 10Ω.

[0291] D: The average on-resistance is 10Ω or higher and less than 20Ω.

[0292] E: The average on-resistance is above 20Ω.

[0293] (Conductivity Resistance Test - High Temperature Placement Test)

[0294] Regarding the on-resistance between the chip (bump) and the substrate (bump) with gold bumps, the initial value and the value after high-temperature placement tests (placed at 100°C for 100, 500, and 1000 hours) were measured for 20 samples. Additionally, after high-temperature placement, drop impacts were applied, and the on-resistance of the samples after the drop impacts was measured. The drop impact was generated by fastening the connecting structure to a metal plate with threads and dropping it from a height of 50 cm. After the drop, the DC resistance value was measured at the solder joint at the corner of the chip with the greatest impact (4 locations). When the measured value increased by more than 5 times compared to the initial resistance, it was considered as a breakage and was evaluated. Furthermore, measurements were performed at 4 locations for each sample, for a total of 80 measurements. The results are shown in Table 6. After 20 drop cycles, those meeting criteria A or B below were evaluated as having good solder joint reliability.

[0295] A: There are 0 solder joints where the resistance has increased by more than 5 times compared to the initial resistance.

[0296] B: There are more than 1 but less than 5 solder joints where the resistance has increased by more than 5 times compared to the initial resistance.

[0297] C: There are 6 to 20 solder joints where the resistance has increased by more than 5 times compared to the initial resistance.

[0298] D: There are more than 21 solder joints where the resistance has increased by more than 5 times compared to the initial resistance.

[0299] (Insulation resistance test)

[0300] Regarding the insulation resistance between chip electrodes, for 20 samples, the initial value and the value after migration tests (100, 500, and 1000 hours under conditions of 60°C, 90% humidity, and 20V) were measured. For all 20 samples, the insulation resistance value was calculated to be 10. 9 The proportion of samples with an Ω or higher was determined. Insulation resistance was evaluated according to the following criteria based on the obtained proportions. The results are shown in Table 7. Furthermore, after 1000 hours of migration testing, insulation resistance can be considered good if either criterion A or B below is met.

[0301] A: Insulation resistance value 10 9 The proportion of Ω and above is 100%.

[0302] B: Insulation resistance value 10 9 The proportion of Ω and above is 90% or more but less than 100%.

[0303] C: Insulation resistance value 10 9 The proportion of those with an Ω rating or higher is between 80% and 90%.

[0304] D: Insulation resistance value 10 9 The proportion of Ω and above is 50% or more but less than 80%.

[0305] E: Insulation resistance value 10 9 The proportion of Ω and above is less than 50%.

[0306] [Table 5]

[0307]

[0308] [Table 6]

[0309]

[0310] [Table 7]

[0311]

[0312] <Fabrication of a Film for Solder Bump Formation>

[0313] Process i1: Evaluation of the substrate fabrication

[0314] A liquid photoresist (manufactured by Hitachi Chemical Co., Ltd., AH series) was spin-coated to a thickness of 2.3 μm onto a 6-inch silicon wafer. The photoresist on the silicon wafer was exposed and developed to form an evaluation pattern with a recessed area having an opening diameter of 3.1 μm φ, a bottom diameter of 2.0 μm φ, and a depth of 2.3 μm (when viewed from above, the bottom diameter of 2.0 μm φ is located at the center of the opening diameter of 3.1 μm φ). In addition, the aforementioned recess was positioned within a 20 mm × 20 mm area, with a 10 mm × 10 mm region at its center. The recess was positioned opposite the electrode arrangement pattern of the evaluation chip C8 described later (X-direction spacing, Y-direction spacing), and three alignment marks were also provided. The substrate 1 for evaluation was obtained by slicing it to a 20 mm × 20 mm size using a slicer. A summary of the evaluation substrate is shown in Table 8.

[0315] [Table 8]

[0316]

[0317] Evaluation substrates 2–6 were prepared using the values ​​shown in Table 8 for the thickness, opening diameter, and spacing of the photosensitive resist.

[0318] <Preparation of Solder Particles>

[0319] Process j1: Preparation of solder particles

[0320] After processes a1, b1, and c1, solder bump forming films with solder particles in the recesses, as shown in Examples 7 to 12 of Table 2, were obtained. Isopropanol was filled into a stainless steel bath, and the obtained solder bump forming films were impregnated with it. Ultrasonic waves at 28 kHz and 600 W were applied for 5 minutes. The solder particles detached from the recesses and dispersed in the isopropanol solvent. The solvent containing the dispersed solder particles was allowed to stand, and the supernatant was discarded. Then, the bath was filled again with isopropanol to further disperse the solder particles, and the solution was allowed to stand. This precipitation separation operation was performed three times, yielding solder particles 1 to 6 with uniform particle size. A summary of solder particles 1 to 6 is shown in Table 9.

[0321] [Table 9]

[0322]

[0323] (Production example 25)

[0324] Process k1: Preparation of fluidizing agent and solder particles

[0325] Dodecane and solder particles 1 were placed in a capped glass bottle and dispersed using ultrasound. The dispersion was dripped onto the surface of an evaluation substrate 1 (20 mm × 20 mm) fixed to a glass plate. The surface of the evaluation substrate 1 was wiped with a polyurethane scraper, filling the recesses with solder particles 1 and dodecane. The remaining solder particles 1 and dodecane on the surface of the evaluation substrate 1 were wiped away with a cleaning cloth, resulting in a solder bump forming film containing solder particles 1 and dodecane disposed within the recesses of the evaluation substrate 1.

[0326] [Table 10]

[0327]

[0328] (Production examples 26 to 42)

[0329] Except for setting the types of fluidizing agent, solder particles, and evaluation matrix as shown in Table 10, the same as in process k1, evaluation solder bump forming films 26-42 with solder particles and fluidizing agent disposed in the recess were obtained. Furthermore, regarding adipic acid, 20 parts by mass of adipic acid were added to 90 parts by mass of dihydroterpene alcohol and thoroughly mixed to prepare a mobile phase.

[0330] <Fabrication of Evaluation Chips with Solder Bumps>

[0331] Process e2: Preparation for chip evaluation

[0332] Six types of chips with gold bumps (10mm×10mm, thickness: 0.5mm) were prepared as shown below.

[0333] Chip C8… Dimensions: 8×4μm, X-axis pitch: 16μm, Y-axis pitch: 8μm, height: 3μm, bump count: 382000

[0334] Chip C9… Dimensions: 16μm × 8μm, X-axis pitch: 32μm, Y-axis pitch: 16μm, height: 5μm, bump count: 95700

[0335] Chip C10… Dimensions: 24μm × 12μm, X-axis pitch: 48μm, Y-axis pitch: 24μm, height: 8μm, bump count: 42500

[0336] Chip C11… Dimensions: 72μm × 36μm, X-axis pitch: 144μm, Y-axis pitch: 72μm, height: 10μm, bump count: 4700

[0337] Chip C12… Dimensions: 96μm × 48μm, X-axis pitch: 192μm, Y-axis pitch: 96μm, height: 13μm, bump count: 2600

[0338] Chip C13… Dimensions: 140μm × 70μm, X-axis pitch: 280μm, Y-axis pitch: 140μm, height: 18μm, bump count: 1200

[0339] In addition, there are three alignment marks.

[0340] <Forming solder bumps>

[0341] Process f3: Forming solder bumps: Nitrogen atmosphere

[0342] Following the sequence shown below (i) to (iii), the evaluation solder bump forming film 25 prepared in step k1 is used to form solder bumps on a chip with gold bumps (10mm × 10mm, thickness: 0.5mm).

[0343] i) Chip C8 was fixed on a 30mm x 30mm (0.5mm thick) glass plate with the gold bumps facing upwards. It was then magnetically attached to the worktable of a flip chip bonding machine (FC3000: manufactured by Toray Industries, Inc.).

[0344] ii) Using a heating and pressurizing head, pick up the 20mm×20mm evaluation substrate 1, read the alignment mark through the camera, align the electrode position of chip C8 with the recess of evaluation substrate 1 and place it temporarily.

[0345] iii) A bell-shaped glass dome was prepared to be blown with nitrogen gas. This dome was used to cover the entire heating plate, and the hot plate was heated to 150°C. The sample prepared in ii) was placed on the heating plate, and a stainless steel ingot was placed on the top layer of the evaluation substrate 1. Heating was performed for 3 minutes under a nitrogen atmosphere. Afterwards, the top ingot and the evaluation substrate 1 were removed in that order. Next, the chip C8 was immersed in a methanol solution, the mobile phase was washed away, and it was vacuum dried (at 40°C for 60 minutes) to obtain the evaluation chip 25 with solder bumps.

[0346] <Evaluation of solder bumps: No formic acid gas used>

[0347] The evaluation chip 25 obtained through process f1 was fixed onto the surface of a SEM observation base, and platinum sputtering was performed on the surface. For 300 gold bumps, the number of solder bumps formed on the gold bumps was counted using SEM, the solder bump formation rate was calculated, and evaluated according to the following evaluation criteria. The results are shown in Table 11. Furthermore, if the solder bump formation rate meets criteria A or B, it can be considered good.

[0348] A: Solder bump formation rate is over 90%.

[0349] B: Solder bump formation rate is 80% or higher but less than 90%.

[0350] C: Solder bump formation rate is 70% or more but less than 80%.

[0351] D: Solder bump formation rate is 60% or more but less than 70%.

[0352] E: Solder bump formation rate is less than 60%.

[0353] Furthermore, the height of the solder bumps on the gold bumps was measured using a laser microscope (LEXT OLS5000-SAF, Olympus Corporation), and the average value of 100 bumps was calculated. The results are shown in Table 11.

[0354] Next, except that the evaluation solder bump forming films 26-42 of Fabrication Examples 26-42 were used, and chips C8-13 corresponding to the positions of each gold bump (electrode) and recess were used instead of the evaluation solder bump forming film 25 of Fabrication Example 25, solder bump formation and evaluation were performed in the same manner as described above. The evaluation results are shown in Table 11.

[0355] [Table 11]

[0356]

[0357] For the evaluation chips 25-42, solder bumps are fully formed on the gold bumps. The solder bumps are formed only on the electrodes, and there are no solder particles between the electrodes. Since the opening of the recess of the solder bump forming film is pressed against the electrode surface, even if a mobile phase is present, the possibility of molten solder leaking from the electrode surface is low, and solder bumps can be formed stably.

[0358] <Forming solder bumps>

[0359] Process f4: Forming solder bumps: Formic acid atmosphere

[0360] Except for replacing step f3 iii) with the following method, solder bumps were formed using the same method as step f3, and the results were evaluated. The evaluation results are shown in Table 12.

[0361] iii) A glass plate on which the evaluation substrate 1 is mounted on the chip C8 is fixed on a hot plate of a formic acid furnace (manufactured by SHINKOSEIKI CO., LTD.), and a stainless steel ingot is mounted on the evaluation substrate 1. After vacuum degassing in the furnace, the sample is treated at 150°C for 3 minutes in a formic acid atmosphere and then returned to atmospheric pressure. The ingot and evaluation substrate 1 are then removed sequentially. Next, the chip C8 is immersed in a methanol solution, the mobile phase is washed away, and it is vacuum dried (at 40°C for 60 minutes) to obtain the evaluation chip 43 with solder bumps.

[0362] [Table 12]

[0363]

[0364] Using the method of process f4, solder bumps were formed in the combination shown in Table 12, thereby obtaining evaluation chips 44 to 60. The evaluation results, performed in the same manner as described above, are shown in Table 12.

[0365] In the evaluation of chips 43-60, good solder bumps were formed. This was due to the use of formic acid as a reducing atmosphere, resulting in excellent results.

[0366] <Forming solder bumps>

[0367] Process f5: Forming solder bumps: Vacuum pressurization

[0368] Except for replacing step f3 iii) with the following method, solder bumps were formed using the same method as step f3, and the results were evaluated. The evaluation results are shown in Table 13.

[0369] iii) A glass plate with the evaluation substrate 1 mounted on the chip C8 was placed on a carrier film in a vacuum pressure laminator (MVL-500: manufactured by The Japan Steel Works, Ltd.). The temperature of the upper and lower heating plates was set to 145°C, and the process was carried out at a pressure of 0.5 MPa and a pressurization time of 3 s. Afterward, the evaluation substrate 1 was removed. Next, the chip C8 was immersed in a methanol solution, and the mobile phase was washed away. It was then vacuum dried (at 40°C for 60 minutes) to obtain the evaluation chip 61 with solder bumps. The results are shown in Table 13.

[0370] [Table 13]

[0371]

[0372] Using the method of process f5, solder bumps were formed in the combination shown in Table 13, thereby obtaining evaluation chips 62-78. The evaluation results, performed in the same manner as described above, are shown in Table 13.

[0373] In the evaluation of chips 61-78, good solder bumps were formed. Vacuum pressurization ensured that pressure was applied evenly within the surface, resulting in excellent outcomes.

[0374] <Fabrication of Evaluation Chips with Solder Bumps>

[0375] Process e3: Preparation for chip evaluation

[0376] Six types of chips with copper bumps (10mm×10mm, thickness: 0.5mm) were prepared as shown below.

[0377] Chip C14… Dimensions: 8×4μm, X-axis pitch: 16μm, Y-axis pitch: 8μm, height: 3μm, bump count: 382000

[0378] Chip C15… Dimensions: 16μm × 8μm, X-axis pitch: 32μm, Y-axis pitch: 16μm, height: 5μm, bump count: 95700

[0379] Chip C16… Dimensions: 24μm × 12μm, X-axis pitch: 48μm, Y-axis pitch: 24μm, height: 8μm, bump count: 42500

[0380] Chip C17… Dimensions: 72μm × 36μm, X-axis pitch: 144μm, Y-axis pitch: 72μm, height: 10μm, bump count: 4700

[0381] Chip C18… Dimensions: 96μm × 48μm, X-axis pitch: 192μm, Y-axis pitch: 96μm, height: 13μm, bump count: 2600

[0382] Chip C19… Dimensions: 140μm × 70μm, X-axis pitch: 280μm, Y-axis pitch: 140μm, height: 18μm, bump count: 1200

[0383] In addition, there are three alignment marks.

[0384] <Forming solder bumps>

[0385] Process f6: Forming solder bumps: Vacuum pressurization

[0386] Except for replacing step f3 iii) with the following method, solder bumps were formed using the same method as step f3, and the results were evaluated. The evaluation results are shown in Table 14.

[0387] iii) A glass plate with the evaluation substrate 1 mounted on the chip C14 was placed on a carrier film in a vacuum pressure laminator (MVL-500: manufactured by The Japan Steel Works, Ltd.). The temperature of the upper and lower heating plates was set to 150°C, and the process was carried out at a pressure of 0.5 MPa and a pressurization time of 10 s. After that, the evaluation substrate 1 was removed. Next, the chip C14 was immersed in a methanol solution, and the mobile phase was washed away. It was then vacuum dried (at 40°C for 60 minutes) to obtain the evaluation chip 79 with solder bumps.

[0388] [Table 14]

[0389]

[0390] Using the method of process f6, solder bumps were formed in the combination shown in Table 14, thereby obtaining evaluation chips 80-96. The evaluation results, performed in the same manner as described above, are shown in Table 14.

[0391] Evaluation chips 79-96 with Cu bumps (electrodes) can also form good solder bumps.

[0392] <Construction of Connecting Structures>

[0393] Process g2: Preparation of the evaluation substrate

[0394] Six types of substrates with gold bumps (40×40mm, thickness: 0.5mm) were prepared as shown below. The Au bumps are positioned opposite to the Au bumps of chips C8 to C13, and have three alignment marks for proper alignment. Furthermore, resistance measurement leads are formed within these gold bumps.

[0395] Substrate D8… Corresponding chip: Chip C8 / Size 8×4μm, X-axis pitch 16μm, Y-axis pitch 8μm, Height: 3μm, Number of bumps: 382000

[0396] Substrate D9… Corresponding chip: Chip C9 / Size 16μm × 8μm, X-axis pitch 32μm, Y-axis pitch 16μm, Height: 5μm, Number of bumps: 95700

[0397] Substrate D10… Corresponding chip: Chip C10 / Size 24μm × 12μm, X-axis pitch 48μm, Y-axis pitch 24μm, Height: 8μm, Number of bumps: 42500

[0398] Substrate D11… Corresponding chip: Chip C11 / Size 72μm × 36μm, X-axis pitch 144μm, Y-axis pitch 72μm, Height: 10μm, Number of bumps 4700

[0399] Substrate D12… Corresponding chip: Chip C12 / Size 96μm × 48μm, X-axis pitch 192μm, Y-axis pitch 96μm, Height: 13μm, Number of bumps 2600

[0400] Substrate D13… Corresponding chip: Chip C13 / Size 140μm × 70μm, X-axis pitch 280μm, Y-axis pitch 140μm, Height: 18μm, Number of bumps 1200

[0401] Process h2: Electrode bonding

[0402] Following the sequence shown below (i) to (iii), the evaluation chip with solder bumps produced in step f5 is connected to the evaluation substrate with gold bumps via solder bumps.

[0403] i) The substrate with gold bumps is fixed on the worktable of a flip chip bonding machine (FC3000: manufactured by Toray Industries, Inc.). An evaluation chip with solder bumps is picked up using a heated and pressurized head and positioned so that the gold bumps are aligned with each other from the alignment marks.

[0404] ii) The substrate containing the evaluation chip was placed on the lower hot plate of the formic acid reflow oven (SHINKO SEIKI CO., LTD., intermittent vacuum welding equipment), and a stainless steel ingot was placed on top of the evaluation chip.

[0405] iii) The formic acid vacuum reflux furnace was put into operation, and after vacuum evacuation, formic acid gas was filled in. The lower hot plate was heated to 150°C and heated for 5 minutes. Afterward, the formic acid gas was removed by vacuum evacuation, nitrogen was used for purging, the lower hot plate was returned to room temperature, and the furnace was opened to the atmosphere. An appropriate amount of underfill material with adjusted viscosity (manufactured by Hitachi Chemical Co., Ltd., CEL series) was placed between the evaluation chip and the evaluation substrate. After filling by vacuum evacuation, it was cured at 125°C for 4 hours, thereby creating the connection structure between the evaluation chip and the evaluation substrate.

[0406] <Evaluation of the connection structure>

[0407] A portion of the obtained connection structure underwent conduction resistance and insulation resistance tests in the same manner as in process h1. The results are shown in Tables 15, 16, and 17.

[0408] [Table 15]

[0409]

[0410] [Table 16]

[0411]

[0412] [Table 17]

[0413]

[0414] <Construction of Connecting Structures>

[0415] Process g3: Preparation of the evaluation substrate

[0416] Six types of substrates with copper bumps (40×40mm, thickness: 0.5mm) were prepared as shown below. The copper bumps are positioned opposite to the copper bumps of chips C14 to C19, and have three alignment marks for proper alignment. Additionally, resistance measurement leads are formed within these copper bumps.

[0417] Substrate D14… Corresponding chip: Chip C14 / Size 8×4μm, X-axis pitch 16μm, Y-axis pitch 8μm, Height: 3μm, Number of bumps 382000

[0418] Substrate D15… Corresponding chip: Chip C15 / Size 16μm × 8μm, X-axis pitch 32μm, Y-axis pitch 16μm, Height: 5μm, Number of bumps: 95700

[0419] Substrate D16… Corresponding chip: Chip C16 / Size 24μm × 12μm, X-axis pitch 48μm, Y-axis pitch 24μm, Height: 8μm, Number of bumps: 42500

[0420] Substrate D17… Corresponding chip: Chip C17 / Size 72μm × 36μm, X-axis pitch 144μm, Y-axis pitch 72μm, Height: 10μm, Number of bumps: 4700

[0421] Substrate D18… Corresponding chip: Chip C18 / Size 96μm × 48μm, X-axis pitch 192μm, Y-axis pitch 96μm, Height: 13μm, Number of bumps: 2600

[0422] Substrate D19… Corresponding chip: Chip C19 / Size 140μm × 70μm, X-axis pitch 280μm, Y-axis pitch 140μm, Height: 18μm, Number of bumps 1200

[0423] Process h3: Electrode bonding

[0424] Following the sequence shown below (i) to (iii), the evaluation chip with solder bumps produced in step f6 is connected to the evaluation substrate with copper bumps via solder bumps.

[0425] i) The evaluation substrate was placed on a spin coater (SC-308S, manufactured by Oshigane Co., Ltd.), and 0.5 ml of flux (WHS-003C: manufactured by Arakawa Chemical Industries, Ltd.) was dropped onto the surface with Cu bumps. The coating was processed at 500 rpm for 10 s, followed by 1000 rpm for 3 s, thereby forming a flux layer for the thin film.

[0426] ii) The evaluation substrate is fixed on the worktable of a flip chip bonding machine (FC3000: manufactured by Toray Industries, Inc.). The evaluation chip with solder bumps is picked up using a heated and pressurized head and positioned so that the bumps are aligned with each other according to the alignment marks. The substrate carrying the evaluation chip is placed on the lower hot plate of a formic acid reflow oven (manufactured by SHINKO SEIKI CO.,LTD., intermittent vacuum bonding apparatus), and a stainless steel ingot is placed on top of the evaluation chip.

[0427] iii) The formic acid vacuum reflux furnace was operated, and after vacuum evacuation, formic acid gas was filled in. The lower hot plate was heated to 160°C and heated for 3 minutes. Afterwards, the formic acid gas was removed by vacuum evacuation, nitrogen purging was performed, the lower hot plate was returned to room temperature, and the furnace was opened to the atmosphere. An appropriate amount of underfill material (manufactured by Hitachi Chemical Co., Ltd., CEL series) with adjusted viscosity was placed between the evaluation chip and the evaluation substrate. After filling using vacuum evacuation, the material was cured at 125°C for 4 hours, thus creating the connection structure between the evaluation chip and the evaluation substrate.

[0428] <Evaluation of the connection structure>

[0429] A portion of the obtained connection structure underwent conduction resistance and insulation resistance tests in the same manner as in process h1. The results are shown in Tables 18, 19, and 20.

[0430] [Table 18]

[0431]

[0432] [Table 19]

[0433]

[0434] [Table 20]

[0435]

[0436] Stable connection characteristics are also observed when Cu electrodes are joined together by solder bumps formed on the Cu electrodes.

[0437] Symbol Explanation

[0438] 1-Solder particles, 1A-Solder bumps, 1B-Solder layer, 2-Substrate, 3-Electrode, 4-Another substrate, 5-Other electrodes, 10-Components for forming solder bumps, 20-Electrode substrate with solder bumps, 30-Connecting structure, 60-Base, 62-Recess, 111-Solder particles, F-Fluorescent agent, 600-Base, 601-Base layer, 602-Recess layer.

Claims

1. A method for manufacturing an electrode substrate with solder bumps, comprising: The preparation process includes preparing a component for forming solder bumps and a substrate having multiple electrodes. The component for forming solder bumps includes: a substrate having multiple recesses; and solder particles and a fluidizing agent within the recesses. The solder particles have an average particle size of 1 to 35 μm and a CV value of 20% or less. The force acting between the solder particles and the recess is an intermolecular force; In the configuration process, the surface of the solder bump forming component having the recess is brought into contact with the surface of the substrate having the electrode; and The heating process involves heating the solder particles to a temperature above their melting point. The method for manufacturing the solder bump forming component includes: Preparation process: Prepare a substrate with multiple recesses and solder particles; The storage process involves storing at least a portion of the solder particles in the recess; The fusion process fuses the solder particles contained in the recess, thereby forming solder particles within the recess; and In the injection process, a fluidizing agent is disposed within the recess where the solder particles are formed.

2. The manufacturing method according to claim 1, wherein, The fluidizing agent comprises at least one selected from the group consisting of succinic acid, glutaric acid, adipic acid, pimelic acid, octanoic acid, benzoic acid, and malic acid.

3. The manufacturing method according to claim 1 or 2, wherein, A planar portion is formed on a part of the surface of the solder particles.

4. The manufacturing method according to claim 1 or 2, wherein, The distance between adjacent recesses is more than 0.1 times the average particle size of the solder particles.

5. The manufacturing method according to claim 1 or 2, wherein, In the heating process, the solder bump forming component and the substrate are brought into contact under pressure, and the solder particles are heated to a temperature above the melting point of the solder particles.

6. The manufacturing method according to claim 1 or 2, wherein, Prior to the configuration step, there is also a reduction step in which the solder particles are exposed to a reducing atmosphere.

7. The manufacturing method according to claim 1 or 2, wherein, After the configuration step and before the heating step, there is a reduction step in which the solder particles are exposed to a reducing atmosphere.

8. The manufacturing method according to claim 1 or 2, wherein, In the heating process, the solder particles are heated to a temperature above the melting point of the solder particles under a reducing atmosphere.

9. The manufacturing method according to claim 1 or 2, wherein, After the heating process, a removal process is performed to remove the solder bump forming component from the substrate.

10. The manufacturing method according to claim 9, wherein, Following the removal process, a cleaning process is also performed to remove solder particles that are not bonded to the electrode.

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