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

Abstract

To provide a solder bump forming member useful for manufacturing a connection structure with both excellent insulation reliability and conduction reliability, even if the connection points of circuit members to be electrically connected to each other are minute, and a method for manufacturing the same.SOLUTION: A solder bump forming member has a base substance with a plurality of recesses and solder particles in the recesses, the average size of solder particles is from 1 to 35 μm, the C.V. value is equal to or less than 20%, a portion of the solder particles protrudes from the recess, or when the depth of the recess is H1 and the height of the solder particles is H2 in cross-sectional view, H1<H2.SELECTED DRAWING: Figure 1

Description

Technical Field

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

Background Art

[0002] A solder ball arrangement sheet is known, which is composed of a mask provided with a plurality of solder ball insertion holes provided in a predetermined pattern, solder balls accommodated in the insertion holes, and an adhesive for holding the solder balls in the insertion holes (see, for example, Patent Document 1).

[0003] A method for manufacturing a sheet for forming solder bumps, which holds solder balls or solder powder at a predetermined position and includes the following steps, is known (see, for example, Patent Document 2). A. Prepare a sheet having a large number of depressions on one side, the bottom surface of which is composed of an adhesive, at predetermined positions; B. Fill each depression of the sheet with solder powder and adhere and hold the solder powder by the adhesive on the bottom surface of the depression; C. Remove the solder powder not held by the adhesive from the sheet, and D. Cover the solder powder in the depression of the sheet.

[0004] A method is known in which solder balls arranged in a concave groove are transferred to the surface of an adhesive roll, and then the solder balls are transferred to an adhesive on an electrode to form solder bumps on the electrode (see, for example, Patent Document 3).

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Patent Document 2

Patent Document 3

Summary of the Invention

Problems to be Solved by the Invention

[0006] In the transfer sheet and manufacturing method shown in Patent Documents 1 and 2, an adhesive layer for holding solder particles is required. Therefore, when heated above the solder melting point to melt and integrate the solder, and further heated during transfer onto the electrode, the adhesive layer components may soften, melt, and decompose to become contaminants. If contaminants intervene between the solder and the electrode, there is a risk of preventing the stable formation of solder bumps. When removing these contaminants after transferring the solder bumps onto the electrode, the substrate and semiconductor package on which the electrodes are formed will be exposed to a cleaning liquid, which may lead to an increase in processes, defects in the substrate and semiconductor package, and defects due to poor cleaning.

[0007] In Patent Document 3, since solder balls (particles) are placed on the electrode via an adhesive, there is a risk that the adhesive components will remain on the surface of the solder balls and cause problems in bonding. Also, controlling the thickness of the adhesive and the unevenness of the adhesive surface is possible to some extent when the size of the solder balls is about 100 μm, but it becomes difficult as the size decreases to 50 μm and 30 μm. Therefore, when transferring and moving solder balls (particles) with a size less than 30 μm via an adhesive, it becomes difficult to increase the transfer rate.

[0008] In addition, there is known a transfer sheet in which solder balls (particles) are uniformly arranged on a substrate surface via an adhesive while being in contact with each other. By pressing the solder ball surface of this transfer sheet against a substrate on which electrodes are formed and heating it, the solder balls are transferred onto the electrodes, and bumps can be formed by subsequent reflow. However, as a result of investigations by the inventors, when the electrode pitch becomes narrow, solder bridges between the electrodes, resulting in a short circuit failure. Since adjacent solder balls are in contact with each other, it is presumed that due to the heat during transfer to the electrodes, the solder melts and coalesces, creating a portion that spans between adjacent electrodes. In such a solder transfer sheet in which solder particles are uniformly arranged while being in contact with each other, it is currently difficult to form solder bumps without short circuits when the electrode pitch is at the micron level.

[0009] The present invention has been made in view of the above circumstances, and an object thereof is to provide a member for forming solder bumps and a method for manufacturing the same, which are useful for manufacturing a connection structure excellent in both insulation reliability and conduction reliability even when the connection portions of circuit members to be electrically connected to each other are minute. Another object of the present invention is to provide a method for manufacturing an electrode substrate with solder bumps using the member.

Means for Solving the Problems

[0010] One aspect of the present invention relates to a member for forming solder bumps, which includes a substrate having a plurality of recesses and solder particles in the recesses, wherein the average particle diameter of the solder particles is 1 to 35 μm, the C.V. value is 20% or less, and a part of the solder particles protrudes from the recesses.

[0011] One aspect of the present invention relates to a member for forming solder bumps, which includes a substrate having a plurality of recesses and solder particles in the recesses, wherein the average particle diameter of the solder particles is 1 to 35 μm, the C.V. value is 20% or less, and in a cross-sectional view, when the depth of the recess is H1 and the height of the solder particles is H2, H1 < H2.

[0012] The above solder bump forming member is useful for manufacturing a connection structure excellent in both insulation reliability and conduction reliability even when the connection portions of circuit members to be electrically connected to each other are minute.

[0013] In one aspect of the solder bump forming member, a flat portion may be formed on a part of the surface of the solder particles.

[0014] In one aspect of the solder bump forming member, the distance between adjacent recesses may be 0.1 times or more the average particle diameter of the solder particles.

[0015] One aspect of the present invention relates to a method for manufacturing a solder bump forming member, including: a preparation step of preparing a substrate having a plurality of recesses and fine solder particles; a housing step of housing at least a part of the fine solder particles in the recesses; a fusion step of fusing the fine solder particles housed in the recesses to form solder particles in the recesses; and a step in which a part of the solder particles protrudes from the recesses.

[0016] In one aspect of the method for manufacturing a solder bump forming member, the average particle diameter of the solder particles may be 1 to 35 μm and the C.V. value may be 20% or less.

[0017] In one aspect of the method for manufacturing a solder bump forming member, the C.V. value of the fine solder particles may exceed 20%.

[0018] One aspect of the method for manufacturing a solder bump forming member may further include a reduction step of exposing the fine solder particles housed in the recesses to a reducing atmosphere before the fusion step.

[0019] In the fusion step in one aspect of the method for manufacturing a solder bump forming member, the fine solder particles may be fused in a reducing atmosphere.

[0020] 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 solder bump forming member and a substrate having a plurality of electrodes; an arrangement step of opposing a surface having a concave portion of the solder bump forming member and a surface having the electrodes of the substrate and bringing the solder particles and the electrodes into contact; and a heating step of heating the solder particles to a temperature equal to or higher than the melting point of the solder particles.

[0021] In one aspect of the heating step in the method for manufacturing an electrode substrate with solder bumps, the solder particles may be heated to a temperature equal to or higher than the melting point of the solder particles while bringing the solder particles and the electrodes into contact in a pressurized state.

[0022] One aspect of the method for manufacturing an electrode substrate with solder bumps may further include a reduction step of exposing the solder particles to a reducing atmosphere before the arrangement step.

[0023] One aspect of the method for manufacturing an electrode substrate with solder bumps may further include a reduction step of exposing the solder particles to a reducing atmosphere after the arrangement step and before the heating step.

[0024] In one aspect of the method for manufacturing an electrode substrate with solder bumps, in the heating step, the solder particles may be heated to a temperature equal to or higher than the melting point of the solder particles in a reducing atmosphere.

[0025] One aspect of the method for manufacturing an electrode substrate with solder bumps may further include a removal step of removing the solder bump forming member from the substrate after the heating step.

[0026] One aspect of the method for manufacturing an electrode substrate with solder bumps may further include a cleaning step of removing solder particles not bonded to the electrodes after the removal step.

Advantages of the Invention

[0027] According to the present invention, even if the connection portions of circuit members to be electrically connected to each other are minute, it is possible to provide a member for forming solder bumps and a method for manufacturing the same, which are useful for manufacturing a connection structure excellent in both insulation reliability and conduction reliability. Further, according to the present invention, it is possible to provide a method for manufacturing an electrode substrate with solder bumps using the member.

Brief Description of the Drawings

[0028]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Embodiments for Carrying Out the Invention

[0029] Hereinafter, embodiments of the present invention will be described. The present invention is not limited to the following embodiments. Note that, unless otherwise specified, the materials exemplified below may be used alone or in combination of two or more. The content of each component in the composition means the total amount of the plurality of substances present in the composition when there are a plurality of substances corresponding to each component in the composition. The numerical range indicated using "~" indicates a range including the numerical values described before and after "~" as the minimum value and the maximum value, respectively. In the numerical ranges described stepwise in this specification, the upper limit value or the lower limit value of a certain step's numerical range may be replaced with the upper limit value or the lower limit value of another step's numerical range. In the numerical ranges described in this specification, the upper limit value or the lower limit value of the numerical range may be replaced with the value shown in the examples.

[0030] <Solder bump forming member> In one aspect, the solder bump forming member includes a substrate having a plurality of recesses and solder particles in the recesses, the average particle diameter of the solder particles is 1 to 35 μm, the C.V. value is 20% or less, and a part of the solder particles protrudes from the recesses. Further, in one aspect, the solder bump forming member includes a substrate having a plurality of recesses and solder particles in the recesses, the average particle diameter of the solder particles is 1 to 35 μm, the C.V. value is 20% or less, and in a cross-sectional view, when the depth of the recess is H1 and the height of the solder particles is H2, H1 < H2.

[0031] FIG. 1 is a cross-sectional view schematically showing a solder bump forming member according to an embodiment. The solder bump forming member 10 includes a substrate 60 having a plurality of recesses 62 and solder particles 1 in the recesses 62. In a predetermined longitudinal section of the solder bump forming member 10, one solder particle 1 is arranged to be aligned in the lateral direction (left-right direction in FIG. 1) in a state separated from an adjacent solder particle 1. The solder particle 1 may be in contact with its side surface and / or bottom surface within the recess 62. The solder bump forming member may be in the form of a film (solder bump forming film), a sheet (solder bump forming sheet), or the like.

[0032] In the solder bump forming member 10, a part of the solder particles 1 protrudes from the recesses. It can be said that at least the top of the solder particle 1 protrudes from the recess 62 of the solder bump forming member 10 (protrudes from the main surface of the substrate 60). Specifically, in a cross-sectional view perpendicular to the main surface of the solder bump forming member 10, when the depth of the recess 62 is H1 and the height of the solder particle 1 is H2, H1 < H2. The height H2 of the solder particle 1 refers to the length from the bottom surface of the recess 62 to the top of the solder particle 1 in the cross-sectional view. The degree of protrusion of the solder particle 1 is not particularly limited, but from the viewpoint of more suitable bonding with the electrode, the ratio of H2 to H1 (H2 / H1) can be 1.02 or more, and may be 1.07 or more. The upper limit of the ratio may be 3.00 from the viewpoint of suppressing the dropout of the solder particle 1.

[0033] (Solder particles) The average particle diameter 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. Also, the average particle diameter of the solder particles 1 is, for example, 1 μm or more, preferably 2 μm or more, more preferably 3 μm or more, and still more preferably 5 μm or more.

[0034] The average particle size of the solder particles 1 can be measured using various methods according to the size. For example, methods such as dynamic light scattering method, laser diffraction method, centrifugal sedimentation method, electrical sensing zone method, resonant mass measurement method, etc. can be used. Furthermore, a method of measuring the particle size from an image obtained by an optical microscope, an electron microscope, etc. can be used. Specific apparatuses include a flow-type particle image analyzer, Microtrac, Coulter counter, etc. The average particle size of the solder particles 1 can be 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 the solder particles 1 from a direction perpendicular to the main surface of the solder bump forming member 10.

[0035] From the viewpoint of achieving more excellent conductive reliability and insulating reliability, the C.V. value of the solder particles 1 is preferably 20% or less, more preferably 10% or less, and still more preferably 7% or less. Also, the lower limit of the C.V. value of the solder particles 1 is not particularly limited. For example, the C.V. value of the solder particles 1 may be 1% or more, or may be 2% or more.

[0036] The C.V. value of the solder particles 1 is calculated by multiplying the value obtained by dividing the standard deviation of the particle size measured by the above-described method by the average particle size by 100.

[0037] A flat portion may be formed on a part of the surface of the solder particle. FIG. 2(a) is a view of the solder particle 1 seen from the side opposite to the opening of the recess 62 in FIG. 1. The solder particle 1 has a shape in which a flat portion 11 having a diameter A is formed on a part of the surface of a sphere having a diameter B. Note that the solder particle 1 shown in FIGS. 1 and 2(a) has the flat portion 11 because the bottom of the recess 62 is flat, but when the bottom of the recess 62 has a shape other than flat, it has a surface with a different shape corresponding to the shape of the bottom.

[0038] As shown in Fig. 2(a), the solder particle 1 may have a flat portion 11 formed on a part of its surface. At this time, the surface other than the flat portion 11 is preferably spherical crown-shaped. That is, the solder particle 1 may have the flat portion 11 and a spherical crown-shaped curved surface portion. The ratio (A / B) of the diameter A of the flat portion 11 to the diameter B of the solder particle 1 may be, for example, greater than 0.01 and less than 1.0 (0.01 < A / B < 1.0), and may also be 0.1 to 0.9. The flat portion 11 and the bottom surface of the concave portion 62 may be in contact. As shown in Fig. 1, since the solder particle 1 has the flat portion 11 and the flat portion is in contact with the bottom surface of the concave portion 62, the detachment of the solder particle 1 from the solder bump forming member 10 is less likely to occur. As will be described later, the flat portion may also occur at a portion where the inner wall portion of the concave portion 62 and the solder particle 1 are in contact.

[0039] When a quadrilateral circumscribing the projection image of the solder particle 1 is created by two pairs of parallel lines, when the distances between opposite sides are X and Y (where Y < X), the ratio (Y / X) of Y to X may be greater than 0.8 and less than 1.0 (0.8 < Y / X < 1.0), and may also be 0.9 or more and less than 1.0. Such a solder particle 1 can be said to be a particle closer to a true sphere. Since the solder particle 1 is closer to a true sphere, unevenness in contact between the solder particle 1 and the electrode is less likely to occur, and a stable connection tends to be obtained. Also, when the variation in the volume of the solder particle 1 is small, the bonding to the electrode is likely to be stable.

[0040] Fig. 2(b) is a diagram showing the distances X and Y (where Y < X) between opposite sides when a quadrilateral circumscribing the projection image of the solder particle is created by two pairs of parallel lines. For example, an arbitrary particle is observed with a scanning electron microscope to obtain a projection image. Two pairs of parallel lines are drawn on the obtained projection image. One pair of parallel lines is arranged at a position where the distance between the parallel lines is the minimum, and the other pair of parallel lines is arranged at a position where the distance between the parallel lines is the maximum, and Y / X of the particle is obtained. This operation is performed on 300 solder particles and the average value is calculated to obtain Y / X of the solder particles.

[0041] The solder particles 1 may contain tin or a tin alloy. As the tin alloy, for example, an In-Sn alloy, an In-Sn-Ag alloy, a Sn-Au alloy, a Sn-Bi alloy, a Sn-Bi-Ag alloy, a Sn-Ag-Cu alloy, a Sn-Cu alloy, etc. can be used. Specific examples of these tin alloys are as follows. · In-Sn (In 52% by mass, Bi 48% by mass, melting point 118 °C) · In-Sn-Ag (In 20% by mass, Sn 77.2% by mass, Ag 2.8% by mass, melting point 175 °C) · Sn-Bi (Sn 43% by mass, Bi 57% by mass, melting point 138 °C) · Sn-Bi-Ag (Sn 42% by mass, Bi 57% by mass, Ag 1% by mass, melting point 139 °C) · Sn-Ag-Cu (Sn 96.5% by mass, Ag 3% by mass, Cu 0.5% by mass, melting point 217 °C) · Sn-Cu (Sn 99.3% by mass, Cu 0.7% by mass, melting point 227 °C) · Sn-Au (Sn 21.0% by mass, Au 79.0% by mass, melting point 278 °C)

[0042] The solder particles may contain indium or an indium alloy. As the indium alloy, for example, an In-Bi alloy, an In-Ag alloy, etc. can be used. Specific examples of these indium alloys are as follows. · In-Bi (In 66.3% by mass, Bi 33.7% by mass, melting point 72 °C) · In-Bi (In 33.0% by mass, Bi 67.0% by mass, melting point 109 °C) · In-Ag (In 97.0% by mass, Ag 3.0% by mass, melting point 145 °C)

[0043] Depending on the use (temperature during connection, etc.) of the solder particles 1, the above tin alloy or indium alloy can be selected. For example, when using the solder particles 1 for fusion at a low temperature, an In-Sn alloy or a Sn-Bi alloy can be adopted, and in this case, fusion can be performed at 150 °C or lower. When using a material with a high melting point such as a Sn-Ag-Cu alloy or a Sn-Cu alloy, high reliability can be maintained even after high-temperature storage.

[0044] The solder particles 1 may contain one or more selected from Ag, Cu, Ni, Bi, Zn, Pd, Pb, Au, P, and B. Among these elements, Ag or Cu may be contained from the following viewpoints. That is, when the solder particles 1 contain Ag or Cu, the melting point of the solder particles 1 can be lowered to about 220°C, and the bonding strength with the electrode is improved, so that better conduction reliability is easily obtained.

[0045] The Cu content of the solder particles 1 is, for example, 0.05 to 10% by mass, and may be 0.1 to 5% by mass or 0.2 to 3% by mass. When the Cu content is 0.05% by mass or more, it is easier to achieve better solder connection reliability. Also, when the Cu content is 10% by mass or less, the solder particles 1 tend to have a low melting point and excellent wettability, and as a result, the connection reliability of the joint by the solder particles 1 tends to be good.

[0046] The Ag content of the solder particles 1 is, for example, 0.05 to 10% by mass, and may be 0.1 to 5% by mass or 0.2 to 3% by mass. When the Ag content is 0.05% by mass or more, it is easier to achieve better solder connection reliability. Also, when the Ag content is 10% by mass or less, the solder particles 1 tend to have a low melting point and excellent wettability, and as a result, the connection reliability of the joint by the solder particles 1 tends to be good.

[0047] (Substrate) As materials for constituting the substrate 60, for example, inorganic materials such as silicon, various ceramics, glass, metals such as stainless steel, and organic materials such as various resins can be used. Among these, the substrate 60 may be a material having heat resistance that does not deteriorate at the melting temperature of the solder fine particles. Also, the substrate 60 may be a material having heat resistance that does not deform even at the temperature at which the solder fine particles are melted. Further, the substrate 60 may be a material that does not alloy or react with the material constituting the solder fine particles and does not change. Also, the concave portion 62 of the substrate 60 can be formed by a known method such as a cutting method, a photolithography method, an imprint method, etc. In particular, when the imprint method is used, a concave portion 62 with an accurate size can be formed in a short process.

[0048] 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 difficult or does not alloy with the material constituting the solder fine particles. As the coating layer, an inorganic substance or an organic substance can be used. As the coating layer, inorganic substances having a strong oxide layer on the surface such as aluminum and chromium, oxides such as titanium oxide, nitrides such as boron nitride, carbon-based materials such as diamond-like carbon, diamond, and graphite, fluororesins, high heat-resistant resins such as polyimide, etc. can be used. Further, the coating layer may have a role of adjusting the wettability with solder. By providing a coating layer on the surface of the substrate 60, the wettability with solder can be appropriately adjusted according to the purpose of use.

[0049] As methods for forming the coating layer, lamination, solution dipping, coating, painting, impregnation, sputtering, plating, etc. can be used.

[0050] From the viewpoint of facilitating the setting of the conditions of the transfer process, the material of the substrate 60 may be a material having physical properties close to or the same as those of the electrode for transferring the solder particles and the substrate on which the electrode is formed. For example, when the coefficient of thermal expansion (CTE) is close to or the same, displacement is less likely to occur during the transfer of the solder particles.

[0051] The substrate 60 may be provided with alignment marks. These alignment marks may be readable by a camera. The substrate side having electrodes may also have alignment marks. By providing the alignment marks on the substrate 60 and the substrate having electrodes, when transferring solder particles onto the electrodes, the camera mounted on the alignment device can read the alignment marks on the substrate 60 and the alignment marks on the substrate having electrodes, and accurately grasp the position of the concave portion 62 having solder particles and the position of the electrodes to which the solder particles are to be transferred. Also, by providing the alignment marks on the substrate 60 and the substrate having electrodes, the solder particles can be transferred onto the electrodes with high positional accuracy.

[0052] There may be one or more alignment marks on the substrate 60. If there are two or more alignment marks, the positional accuracy will be higher.

[0053] The specific configuration of the substrate 60 will be described below.

[0054] (Organic material single layer) The substrate 60 may be made of an organic material. The organic material may be a polymer material, and thermoplastic, thermosetting, photo-curable materials, etc. can be used. By using an organic material, the range of selection of physical properties is widened, making it easy to form the substrate 60 according to the purpose. For example, if it is an organic material, the substrate 60 (including the recess 62) is easy to bend or stretch. If it is an organic material, various methods can also be used to form the recess 62. As a method for forming the recess 62, imprinting, photolithography, cutting, laser processing, etc. can be used. In particular, according to the imprint method, a mold having a desired shape can be pressed against the substrate 60 made of an organic material to form an arbitrary shape on the surface. By forming a convex pattern on the mold and pressing it against the substrate 60 made of an organic material, a recess 62 having a desired pattern can be formed. Also, a photo-curable resin can be used to form the recess 62. After applying the photo-curable resin to the mold and exposing it, and then peeling off the mold, a substrate 60 having the recess 62 can be formed. In the case of cutting, the recess 62 can be formed with a drill or the like.

[0055] (Organic material multi-layer) The substrate may be composed of a plurality of organic materials. Further, the substrate may have a plurality of layers, and the plurality of layers may each be composed of a different organic material. The organic material may be a polymer material, and thermoplastic, thermosetting, photocurable materials, etc. can be used. The substrate may have two layers composed of an organic material, and a recess may be formed in the organic material layer on one side. By forming multiple layers, it is possible to select materials with appropriate wettability with solder for the material of the recess that comes into contact with the solder, etc., and select each material with different functions. For example, FIG. 9 is a cross-sectional view schematically showing an example of the substrate. The substrate 600 includes a base layer 601 and a recess layer 602. The base layer 601 is a layer that supports the recess layer 602, and the recess layer 602 is a layer in which the recess 62 is formed by processing. A resin material excellent in heat resistance and dimensional stability can be used for the base layer 601, and a material excellent in processability of the recess 62 can be selected for the recess layer 602. For example, a thermoplastic resin such as polyethylene terephthalate or polyimide can be used for the base layer 601, and a thermosetting resin capable of forming the recess 62 by an imprint mold can be used for the recess layer 602. For example, by sandwiching a thermosetting resin between polyethylene terephthalate and an imprint mold and heating and pressing, a substrate 600 (including the recess 62) with excellent flatness can be obtained. Further, when the recess 62 is formed using a photocurable material, a material with high light transmissivity may be used for the base layer 601. Examples of the material with high light transmissivity may include polyethylene terephthalate, transparent (colorless type) polyimide, polyamide, etc. When the recess 62 is formed using a photocurable material, for example, an appropriate amount of the photocurable material is applied to the surface of the imprint mold, a polyethylene terephthalate film is placed thereon, and ultraviolet light is irradiated while pressing with a roller from the polyethylene terephthalate side. Then, after curing the photocurable material, the imprint mold is peeled off to obtain a substrate 600 having a layer of polyethylene terephthalate and a layer of the photocurable material, and the recess 62 is formed of the photocurable material. The material composition of the inner wall and the bottom of the recess 62 can be changed. For example, the inner wall and the bottom of the recess 62 can have the same resin material composition.In addition, the inner wall and the bottom of the recess 62 can be made of different resin materials (for example, a thermosetting material and a thermoplastic material).

[0056] Also, a photosensitive material may be used as the organic material. The photosensitive material may be a positive-type photosensitive material or a negative-type photosensitive material. For example, by forming a photosensitive material with a uniform thickness on the surface of a thermoplastic polyethylene terephthalate film and performing exposure and development, the recess 62 can be easily formed. The method using exposure and development (photolithography) is widely used in the manufacture of semiconductors, wiring boards, etc., and is a highly versatile method. In addition to exposure using a mask, a direct drawing method such as direct laser exposure can also be used as the exposure method.

[0057] By making the material of the base layer 601 thicker than the thickness of the material forming the recess layer 602, the physical properties of the entire substrate 600 can be predominantly governed by the properties of the material of the base layer 601. Thereby, even if there are weaknesses in the properties of the material forming the recess layer 602, for example, they can be compensated for by the material of the base layer 601. For example, even if the material forming the recess layer 602 is a material that easily undergoes thermal shrinkage, by selecting a material with low thermal shrinkage for the material of the base layer 601 and making the thickness of the base layer 601 thicker than the thickness of the material forming the recess layer 602, deformation during heating can be suppressed.

[0058] In addition, an organic material can be appropriately selected according to the purpose, such as a combination of a resin material excellent in heat resistance or dimensional stability and a material with little component elution at the melting temperature of solder fine particles, or a combination of a resin material excellent in heat resistance or dimensional stability and a material with appropriate wettability with solder.

[0059] As described above, the substrate may be a substrate 600 composed of a base layer 601 and a recess layer 602. For example, by using the recess layer 602 as a photosensitive material, the recess 62 can be formed by photolithography. By using a light or thermosetting material, a thermoplastic material, etc. for the recess layer 602, the recess 62 can be easily formed by an imprint method. In addition, since it is possible to adjust the characteristics of the entire substrate by changing the thickness of the base layer 601, there is an advantage that a substrate having desired characteristics can be manufactured.

[0060] (Inorganic material single layer (opaque)) The substrate 60 may be composed of an inorganic material. From the viewpoint of easily controlling the elution of components and the generation of foreign matters, for example, as the inorganic material, silicon (silicon wafer), stainless steel, aluminum, etc. can be used. When these materials are used in a semiconductor mounting process, etc., it is easy to take contamination countermeasures and can contribute to high yield and stable production. Also, for example, when transferring the solder particles formed in the recess 62 to the electrodes on a silicon wafer, if the substrate 60 is made from a silicon wafer, materials with similar or the same CTE will be used. As a result, misalignment, warping, etc. are less likely to occur, and accurate transfer to the correct position becomes possible. As a method for forming the recess 62, processing by laser, cutting, etc., dry etching or wet etching methods, electron beam lithography (for example, FIB processing), etc. can be used. Dry etching is widely used in the manufacture of semiconductors, MEMS, etc., and can process inorganic materials with high precision from the micron order to the nano order.

[0061] (Inorganic material single layer (transparent)) As the substrate 60, glass, quartz, sapphire, etc. can be used. Since these materials are transparent, it is easy to perform alignment when transferring the solder particles in the recess 62 to another substrate on which electrodes are formed. As a method for forming the recess 62, processing by laser, cutting, etc., dry etching or wet etching methods, electron beam lithography (for example, FIB processing), etc. can be used.

[0062] The advantage of using an inorganic material is that it has excellent dimensional stability compared to an organic material. When transferring solder particles in the recess 62 onto the electrode, it can be transferred with high positional accuracy. For example, when transferring solder particles to a plurality of electrodes with a size and pitch on the order of micrometers, by using an inorganic material with excellent dimensional stability, the solder particles can be transferred to the same position on any electrode.

[0063] (organic-inorganic composite material) The substrate may be composed of a plurality of materials. Further, the substrate may have a plurality of layers, and the plurality of layers may each be composed of a different material. As the organic-inorganic composite material, for example, a combination of inorganic materials and a combination of inorganic materials and organic materials can be used. The combination of inorganic materials and organic materials can achieve both dimensional stability and workability of the recess 62. Examples of the substrate having a combination of inorganic materials and organic materials include a substrate including a base layer 601 made of a metal such as silicon, various ceramics, glass, or stainless steel, which are inorganic materials, and a recess layer 602 made of an organic material. Such a substrate can be obtained, for example, by forming a photosensitive material on the surface of a silicon wafer and forming a recess by exposure and development. The inner wall and bottom of the recess 62 may be composed of a photosensitive material, or the inner wall of the recess 62 may be composed of a photosensitive material and the bottom may be composed of a silicon wafer. The configuration of the recess 62 can be appropriately selected according to purposes such as wettability with solder particles in the recess 62 and ease of transfer to an electrode. When the inner wall and bottom of the recess 62 are composed of a photosensitive material, a method can be used in which a photosensitive material layer is provided on the surface of the silicon wafer by forming and curing a photosensitive material on the surface of the silicon wafer, a photosensitive material is again formed on the surface of the layer, and the recess 62 is provided by exposure and development. In this case, the photosensitive material on the silicon wafer surface side and the photosensitive material provided on the outermost layer may have different compositions. The photosensitive material can be appropriately selected in consideration of wettability and contaminativeness of solder particles. In particular, when transferring the solder particles formed in the recess 62 onto an electrode, the surface of the outermost photosensitive material layer may come into contact with the surface of the electrode or the substrate having the electrode. Therefore, a photosensitive material that does not damage the electrode and the substrate or does not contaminate the electrode and the substrate can be appropriately selected. The photosensitive material may be a material that prevents elution of uncured components, contamination by halogen-based materials, silicone-based materials, etc. Further, the photosensitive material may be a material having high resistance to a reducing atmosphere, flux, etc. when transferring solder particles to an electrode. For example, the photosensitive material may be a material having resistance to a reducing atmosphere such as formic acid, hydrogen, or hydrogen radicals. Furthermore, the photosensitive material may be a material having high resistance to the temperature when transferring solder particles to an electrode.Specifically, the photosensitive material may be a material resistant to temperatures from 100°C to 300°C. Since the melting point of solder particles varies depending on their constituent materials, the heat-resistant temperature of the photosensitive material can also be selected according to the solder material used. When using a lead-free solder widely used in electronic devices, such as a tin-silver-copper-based solder (e.g., SAC305 with a melting point of 219°C), a material with heat resistance of 220°C or higher, particularly 260°C or higher when used in the reflow process, can be used. When using a tin-bismuth-based solder (e.g., SnBi58 with a melting point of 139°C), a material with heat resistance of 140°C or higher can be used, and if the material has heat resistance of 160°C or higher, the industrial utilization likelihood becomes wider. When using indium solder (melting point 159°C), a material with heat resistance of 170°C or higher can be used. When using indium-tin solder (e.g., melting point 120°C), a material with heat resistance of 130°C or higher can be used.

[0064] Examples of other substrates include a substrate having a recess 62 formed of a thermosetting or thermoplastic resin on a stainless steel plate. This substrate can be obtained by sandwiching a thermosetting material (resin) between the stainless steel plate and an imprint mold, heating under pressure, and then peeling off the imprint mold. Examples of other substrates also include a substrate having a recess 62 formed of a photocurable material on a glass plate. This substrate can be obtained by applying a photocurable material on the glass plate, exposing it while pressing an imprint mold to cure the photocurable material, and then peeling off the imprint mold. When forming the recess 62 using an imprint mold, the material composition of the inner wall and bottom of the recess 62 can be changed according to the pressure conditions. For example, when the pressure conditions are relaxed, the inner wall and bottom of the recess 62 can have the same resin material composition. On the other hand, when the pressure conditions are strengthened, the inner wall of the recess 62 can be made of a resin material and the bottom can be made of an inorganic material.

[0065] As the material of the base layer 601, a composite material containing glass fiber, filler, etc. and a resin component can also be used. Examples of the composite material include copper-clad laminates for wiring boards. A photosensitive material, a thermosetting resin, a photocurable resin, etc. can be applied to the surface of the copper-clad laminate to form the concave portion 62 as described above. Although the copper-clad laminate mainly contains a large amount of resin material, it can be made to have a low CTE by combining with glass fiber, various fillers, etc., so that the above-mentioned dimensional stability can be ensured. Further, when an electrode is formed on the copper-clad laminate, by forming the concave portion 62 on the same copper-clad laminate, the CTEs of both become the same or close values, and there is an advantage that alignment is easy during the transfer of the solder particles in the concave portion 62 and displacement is less likely to occur.

[0066] As the material of the concave portion layer 602, a sealing material for packages can also be used. Any of solid, liquid, and film-like sealing materials can be used. The concave portion 62 can be formed by laminating the sealing material in a thin layer on glass, a silicon wafer, etc. and pressurizing and heating with an imprint mold.

[0067] <Manufacturing method of member for forming solder bump> The manufacturing method of the member 10 for forming solder bumps includes a preparation step of preparing a substrate having a plurality of concave portions and solder fine particles, a housing step of housing at least a part of the solder fine particles in the concave portions, and a fusion step of fusing the solder fine particles housed in the concave portions to form solder particles in the concave portions, and a step in which a part of the solder particles protrudes from the concave portions.

[0068] With reference to FIGS. 3 to 6, the manufacturing method of the member 10 for forming solder bumps according to the first embodiment will be described.

[0069] First, solder fine particles and a substrate 60 for accommodating the solder fine particles are prepared. FIG. 3(a) is a plan view schematically showing an example of the substrate 60, and FIG. 3(b) is a cross-sectional view taken along line Ib-Ib of FIG. 3(a). The substrate 60 shown in FIG. 3(a) has a plurality of recesses 62. The plurality of recesses 62 may be regularly arranged in a predetermined pattern. The positions and numbers of the plurality of recesses 62 may be set according to the shape, size, pattern, etc. of the electrodes to be connected.

[0070] There is no particular limitation on the distance L between adjacent recesses, but it can be 0.1 times or more the average particle diameter of the solder particles to be accommodated, and may be 0.2 times or more. The upper limit of this value can be, for example, 0.3 times. The distance between recesses is the distance from the edge to the edge of the recess opening, not the center-to-center distance of the recesses.

[0071] The recess 62 of the substrate 60 is preferably formed in a tapered shape in which the opening area expands from the bottom 62a side of the recess 62 toward the surface 60a side of the substrate 60. That is, as shown in FIGS. 3(a) and 3(b), the width of the bottom 62a of the recess 62 (width a in FIGS. 3(a) and 3(b)) is preferably narrower than the width of the opening at the surface 60a of the recess 62 (width b in FIGS. 3(a) and 3(b)). And the size of the recess 62 (width a, width b, volume, taper angle, depth, etc.) may be set according to the size of the target solder particles.

[0072] Note that the shape of the recess 62 may be a shape other than the shapes shown in FIGS. 3(a) and 3(b). For example, the shape of the opening at the surface 60a of the recess 62 may be an ellipse, a triangle, a quadrilateral, a polygon, etc., in addition to a circle as shown in FIG. 3(a).

[0073] Also, the shape of the recess 62 in a cross-section perpendicular to the surface 60a may be, for example, the shape shown in FIG. 4. FIGS. 4(a) to (h) are cross-sectional views schematically showing examples of the cross-sectional shape of the recess of the substrate. In any of the cross-sectional shapes shown in FIGS. 4(a) to (h), the width of the opening (width b) on the surface 60a of the recess 62 is the maximum width in the cross-sectional shape. Thereby, the solder particles formed in the recess 62 are easily taken out, and the workability is improved. Further, since the width (width b) of the opening is the maximum width in the cross-sectional shape, when transferring the solder particles 1 onto the electrode, the solder particles 1 can easily escape from the recess 62, and an improvement in the transfer rate can be expected. Further, by appropriately adjusting the width (width b) of the opening, displacement during the transfer of the solder particles 1 onto the electrode is less likely to occur, and it becomes easier to form solder bumps at accurate positions.

[0074] The solder fine particles prepared in the preparation step may contain fine particles having a particle diameter smaller than the width of the opening (width b) on the surface 60a of the recess 62, and it is preferable to contain more fine particles having a particle diameter smaller than the width b. For example, it is preferable that the D10 particle diameter of the particle size distribution of the solder fine particles is smaller than the width b, more preferably the D30 particle diameter of the particle size distribution is smaller than the width b, and even more preferably the D50 particle diameter of the particle size distribution is smaller than the width b.

[0075] The particle size distribution of the solder fine particles can be measured using various methods according to the size. For example, methods such as dynamic light scattering method, laser diffraction method, centrifugal sedimentation method, electrical sensing zone method, resonance mass measurement method can be used. Further, a method of measuring the particle size from an image obtained by an optical microscope, an electron microscope, etc. can be used. Specific devices include flow-type particle image analyzers, Microtrac, Coulter counters, etc.

[0076] The C.V. value of the solder fine particles prepared in the preparation step is not particularly limited, but from the viewpoint of improving the filling property of the recess 62 by the combination of large and small fine particles, it is preferable that the C.V. value is high. For example, the C.V. value of the solder fine particles may exceed 20%, preferably 25% or more, and more preferably 30% or more.

[0077] The C.V. value of the solder fine particles is calculated by multiplying the value obtained by dividing the standard deviation of the particle diameter measured by the above-described method by the average particle diameter (D50 particle diameter) by 100.

[0078] The solder fine particles may contain tin or a tin alloy. As the tin alloy, for example, an In-Sn alloy, an In-Sn-Ag alloy, a Sn-Au alloy, a Sn-Bi alloy, a Sn-Bi-Ag alloy, a Sn-Ag-Cu alloy, a Sn-Cu alloy, etc. can be used. Specific examples of these tin alloys are as follows. · In-Sn (In 52 mass%, Bi 48 mass%, melting point 118°C) · In-Sn-Ag (In 20 mass%, Sn 77.2 mass%, Ag 2.8 mass%, melting point 175°C) · Sn-Bi (Sn 43 mass%, Bi 57 mass%, melting point 138°C) · Sn-Bi-Ag (Sn 42 mass%, Bi 57 mass%, Ag 1 mass%, melting point 139°C) · Sn-Ag-Cu (Sn 96.5 mass%, Ag 3 mass%, Cu 0.5 mass%, melting point 217°C) · Sn-Cu (Sn 99.3 mass%, Cu 0.7 mass%, melting point 227°C) · Sn-Au (Sn 21.0 mass%, Au 79.0 mass%, melting point 278°C)

[0079] The solder fine particles may contain indium or an indium alloy. As the indium alloy, for example, an In-Bi alloy, an In-Ag alloy, etc. can be used. Specific examples of these indium alloys are as follows. · In-Bi (In 66.3 mass%, Bi 33.7 mass%, melting point 72°C) · In-Bi (In 33.0 mass%, Bi 67.0 mass%, melting point 109°C) · In-Ag (In 97.0 mass%, Ag 3.0 mass%, melting point 145°C)

[0080] The above-mentioned tin alloy or indium alloy can be selected according to the use of the solder particles (temperature during use), etc. For example, when it is desired to obtain solder particles for use in fusion bonding at a low temperature, an In-Sn alloy or a Sn-Bi alloy may be employed. In this case, solder particles capable of being fusion-bonded at 150°C or lower can be obtained. When materials with a high melting point such as Sn-Ag-Cu alloy or Sn-Cu alloy are employed, solder particles capable of maintaining high reliability even after being left at a high temperature can be obtained.

[0081] The solder fine particles may contain one or more selected from Ag, Cu, Ni, Bi, Zn, Pd, Pb, Au, P, and B. Among these elements, Ag or Cu may be contained from the following viewpoints. That is, when the solder fine particles contain Ag or Cu, the melting point of the obtained solder particles can be lowered to about 220°C, and solder particles with excellent bonding strength to the electrodes can be obtained, resulting in better conduction reliability.

[0082] The Cu content of the solder fine particles is, for example, 0.05 to 10% by mass, and may be 0.1 to 5% by mass or 0.2 to 3% by mass. When the Cu content is 0.05% by mass or more, it is easy to obtain solder particles capable of achieving good solder connection reliability. Also, when the Cu content is 10% by mass or less, solder particles with a low melting point and excellent wettability are easily obtained, and as a result, the connection reliability of the electrode with solder bumps tends to be better.

[0083] The Ag content of the solder fine particles is, for example, 0.05 to 10% by mass, and may be 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 easy to obtain solder particles capable of achieving good solder connection reliability. Also, when the Ag content is 10% by mass or less, solder particles with a low melting point and excellent wettability are easily obtained, and as a result, the connection reliability of the electrode with solder bumps tends to be better.

[0084] In the accommodation step, solder fine particles prepared in the preparation step are accommodated in each of the recesses 62 of the substrate 60. The accommodation step may be a step of accommodating all of the solder fine particles prepared in the preparation step in the recesses 62, or may be a step of accommodating a part of the solder fine particles prepared in the preparation step (for example, those smaller than the width b of the opening of the recess 62) in the recesses 62.

[0085] FIG. 5 is a cross-sectional view schematically showing a state in which solder fine particles 111 are accommodated in the recess 62 of the substrate 60. As shown in FIG. 5, a plurality of solder fine particles 111 are accommodated in each of the plurality of recesses 62.

[0086] By adjusting the amount of the solder fine particles 111 accommodated in the recess 62, the degree of protrusion of the solder particles 1 can be adjusted. The amount of the solder fine particles 111 accommodated in the recess 62 is preferably, for example, 20% or more, more preferably 30% or more, still more preferably 50% or more, and most preferably 60% or more with respect to the volume of the recess 62. Thereby, a part of the solder particles can be protruded from the recess 62. In addition, variations in the accommodation amount can be suppressed, and solder particles with a smaller particle size distribution can be easily obtained.

[0087] Generally, when a solder material is in a molten state in an environment above its melting point, it has a property of aggregating into a spherical shape due to its own surface tension.

[0088] The solder fine particles 111 accommodated in the recess 62 are aggregated by a fusion step described later to form solder particles 1. The height of the obtained solder particles 1 becomes higher than the depth of the recess 62, and the solder particles 1 protrude from the recess 62. Therefore, if the diameter of the solder particles 1 is larger than the depth of the recess 62, the solder particles 1 protrude from the recess 62. Since the diameter of the solder particles 1 can be adjusted according to the shape of the recess 62 and the amount of the solder fine particles 111 accommodated in the recess 62, the degree of protrusion from the recess 62 can be adjusted thereby.

[0089] Also, when the solder fine particles 111 are dissolved in the fusion process described later, depending on the material of the bottom and inner wall portions of the recess 62, wetting spread occurs at the bottom and inner wall portions, and at least a part of the solder particles 1 comes into contact with the bottom and / or inner wall portions of the recess 62. As a result, a flat portion may be generated in at least a part of the solder particles 1. The size of this flat portion varies depending on the combination of the surface material of the bottom and inner wall portions of the recess 62 and the solder composition constituting the solder fine particles 111. Therefore, the shape of the solder particles 1 becomes a spherical shape, an ellipsoid, a flattened sphere, a shape having a flat portion in part, etc. As the substrate 60, an inorganic substance such as glass or silicon, or an organic substance such as plastic or resin can be used. The bottom and inner wall portions of such materials generally tend to have low wettability with solder, and the solder particles 1 tend to be approximately spherical close to a perfect sphere. Therefore, assuming that the solder particles 1 are spheres close to a perfect sphere, the height of the solder particles 1 can be approximated to the diameter of the solder particles 1. Since the diameter of the solder particles 1 can be calculated from the total volume of the solder fine particles 111 filled in the recess 62, the amount of the solder fine particles 111 required for the solder particles 1 to protrude from the recess 62 can be calculated.

[0090] It is possible to show the amount of the solder fine particles 111 required for the solder particles 1 to protrude from the recess 62, assuming that all of the solder fine particles 111 filled in the recess 62 are dissolved and united to form the solder particles 1 and the solder particles 1 are spherical.

[0091] When the upper diameter (opening width b) of the recess 62 is L and the depth of the recess 62 is D, the aspect ratio of the recess is represented by L / D. At this time, the filling rate of the solder fine particles 111 into the recess 62 is preferably 66% by volume or more when the aspect ratio is 1, 38% by volume or more when the aspect ratio is 0.75, 17% by volume or more when the aspect ratio is 0.5, and 5% by volume or more when the aspect ratio is 0.25.

[0092] In order to suppress the variation in the storage capacity, the average particle diameter, particle size, etc. of the solder fine particles 111 may be selected according to the size of the concave portion 62 and the ratio of the diameter to the depth (aspect ratio). For example, when the diameter of the concave portion 62 is 4 μm and the depth is 4 μm (aspect ratio is 1), by using the solder fine particles 111 with an average particle diameter of 1 to 2 μm or less, the variation in the filling amount of the concave portion 62 can be suppressed, the variation in the diameter of the obtained solder particles 1 can also be suppressed, and the variation in the protruding amount (height) from the concave portion 62 is also easily suppressed. When the variation in the protruding amount (height) from the concave portion 62 is suppressed, when the solder particles 1 are pressed against the electrode, the contact between the solder particles 1 and the electrode is stable, and the variation in the formation of solder bumps is easily suppressed.

[0093] When the solder fine particles 111 accommodated in the concave portion 62 are dissolved and unified, in order to make them easily united into one, it is preferable to adjust the bottom shape of the concave portion 62. For example, as shown in FIGS. 4(b), (e), (g), and (h), it is preferable to select a bottom shape with a gradient toward the center. In particular, when the aspect ratio of the concave portion 62 is large, in other words, when the opening width of the concave portion 62 is wide and has a shallow shape, when the solder fine particles 111 are dissolved, the solder fine particles 111 that remain without being unified are likely to occur. Therefore, it is preferable to adjust the shape of the bottom of the concave portion 62 as shown in FIGS. 4(b), (e), (g), and (h).

[0094] The method of accommodating the solder fine particles in the recess 62 is not particularly limited. The accommodating method may be either dry or wet. For example, the solder fine particles prepared in the preparation step are placed on the substrate 60, and the surface 60a of the substrate 60 is wiped using a squeegee, so that sufficient solder fine particles can be accommodated in the recess 62 while removing excess solder fine particles. When the width b of the opening of the recess 62 is larger than the depth of the recess 62, the solder fine particles may jump out from the opening of the recess 62. When using a squeegee, the solder fine particles jumping out from the opening of the recess 62 are removed. As methods for removing excess solder fine particles, there are also methods such as blowing compressed air, wiping the surface 60a of the substrate 60 with a non-woven fabric or a bundle of fibers, etc. Since these methods have a weaker physical force than a squeegee, they are preferable when handling solder fine particles that are easily deformed. Also, with these methods, the solder fine particles jumping out from the opening of the recess 62 can be left in the recess.

[0095] The fusion step is a step of fusing the solder fine particles 111 accommodated in the recess 62 (for example, by heating to 130 to 260 ° C) to form solder particles 1 in which a part protrudes from the recess 62 in the recess 62. The solder fine particles 111 accommodated in the recess 62 are united by melting and spheroidized by surface tension. At this time, at the contact portion with the bottom portion 62a of the recess 62, the molten solder follows the bottom portion 62a to form a flat portion 11. Thereby, the formed solder particles 1 have a shape having a flat portion 11 on a part of the surface. In this way, the solder bump forming member 10 shown in FIG. 1 is obtained.

[0096] As a method of melting the solder fine particles 111 accommodated in the recess 62, a method of heating the solder fine particles 111 to a temperature equal to or higher than the melting point of the solder can be mentioned. Due to the influence of the oxide film, the solder fine particles 111 may not melt or wet and spread even when heated to a temperature equal to or higher than the melting point, and may not coalesce. Therefore, by exposing the solder fine particles 111 to a reducing atmosphere, removing the surface oxide film of the solder fine particles 111, and then heating to a temperature equal to or higher than the melting point of the solder fine particles 111, the solder fine particles 111 can be melted, wet and spread, and coalesced. Further, the melting of the solder fine particles 111 is preferably performed in a reducing atmosphere. By heating the solder fine particles 111 to a temperature equal to or higher than the melting point of the solder fine particles 111 and setting it to a reducing atmosphere, the oxide film on the surface of the solder fine particles 111 is reduced, and the melting, wet spreading, and coalescence of the solder fine particles 111 easily proceed efficiently. That is, the method for manufacturing a member for forming solder bumps may further include a reduction step of exposing the solder fine particles accommodated in the recess to a reducing atmosphere before the fusion step. Further, in the fusion step of the method for manufacturing a member for forming solder bumps, the solder fine particles may be fused in a reducing atmosphere.

[0097] The method for creating a reducing atmosphere is not particularly limited as long as the above-described effects can be obtained. For example, there is a method using hydrogen gas, hydrogen radicals, formic acid gas, etc. For example, by using a hydrogen reduction furnace, a hydrogen radical reduction furnace, a formic acid reduction furnace, or a conveyor furnace or a continuous furnace thereof, the solder fine particles 111 can be melted in a reducing atmosphere. These apparatuses may be provided with a heating device, a chamber filled with an inert gas (nitrogen, argon, etc.), a mechanism for evacuating the inside of the chamber, etc. in the furnace, which makes it easier to control the reducing gas. Further, if the inside of the chamber can be evacuated, after the melting and coalescence of the solder fine particles 111, voids can be removed by reducing the pressure, and solder particles 1 with even better connection stability can be obtained.

[0098] The profiles such as the reduction, dissolution conditions, temperature, and adjustment of the furnace atmosphere of the solder fine particles 111 may be appropriately set in consideration of the melting point, particle size, recess size, material of the substrate 60, etc. of the solder fine particles 111. For example, after inserting the substrate 60 filled with the solder fine particles 111 into the furnace and performing evacuation, a reducing gas is introduced to fill the furnace with the reducing gas, and after removing the surface oxide film of the solder fine particles 111, the reducing gas is removed by evacuation. Then, it is heated to a temperature above the melting point of the solder fine particles 111 to dissolve and unite the solder fine particles to form solder particles in the recess 62. After that, nitrogen gas is filled and then the furnace temperature is returned to room temperature, and the solder particles 1 can be obtained. Also, for example, after inserting the substrate 60 filled with the solder fine particles 111 into the furnace and performing evacuation, a reducing gas is introduced to fill the furnace with the reducing gas, and the solder fine particles 111 are heated by the furnace heating heater to remove the surface oxide film of the solder fine particles 111. After that, the reducing gas is removed by evacuation. Then, it is heated to a temperature above the melting point of the solder fine particles 111 to dissolve and unite the solder fine particles to form solder particles in the recess 62. After that, nitrogen gas is filled and then the furnace temperature is returned to room temperature, and the solder particles 1 can be obtained. By heating the solder fine particles in a reducing atmosphere, there is an advantage that the reducing power increases and it becomes easier to remove the surface oxide film of the solder fine particles.

[0099] Furthermore, for example, after inserting the substrate 60 filled with the solder fine particles 111 into the furnace and performing evacuation, a reducing gas is introduced to fill the furnace with the reducing gas, and the furnace heating heater is used to heat the solder fine particles 111 to a temperature above the melting point of the solder fine particles 111. At the same time, the surface oxide film of the solder fine particles 111 is removed by reduction and the solder fine particles are dissolved and united to form solder particles in the recess 62. The reducing gas is removed by evacuation, and after further reducing the voids in the solder particles, nitrogen gas is filled and then the furnace temperature is returned to room temperature, and the solder particles 1 can be obtained. In this case, since the adjustment of the increase and decrease of the furnace temperature can be done only once each, there is an advantage that the processing can be done in a short time.

[0100] After forming solder particles in the concave portion 62 described above, the inside of the furnace may be made into a reducing atmosphere again, and a step of removing the surface oxide film that could not be completely removed may be added. Thereby, it is possible to reduce residues such as solder fine particles that remained unfused and a part of the oxide film that remained unfused.

[0101] When using an atmospheric pressure conveyor furnace, the substrate 60 filled with solder fine particles 111 in the concave portion is placed on a conveying conveyor, and the solder particles 1 can be obtained by continuously passing through a plurality of zones. For example, the substrate 60 filled with the solder fine particles 111 is placed on a conveyor set at a constant speed, passed through a zone filled with an inert gas such as nitrogen or argon at a temperature lower than the melting point of the solder fine particles 111, and then passed through a zone where a reducing gas such as formic acid gas at a temperature lower than the melting point of the solder fine particles 111 exists to remove the surface oxide film of the solder fine particles 111. Subsequently, it is passed through a zone filled with an inert gas such as nitrogen or argon at a temperature equal to or higher than the melting point of the solder fine particles 111 to melt and unite the solder fine particles 111. Subsequently, it is passed through a cooling zone filled with an inert gas such as nitrogen or argon to obtain the solder particles 1. For example, the substrate 60 filled with the solder fine particles 111 is placed on a conveyor set at a constant speed, passed through a zone filled with an inert gas such as nitrogen or argon at a temperature equal to or higher than the melting point of the solder fine particles 111, and then passed through a zone where a reducing gas such as formic acid gas at a temperature equal to or higher than the melting point of the solder fine particles 111 exists to remove the surface oxide film of the solder fine particles 111, melt and unite them, and subsequently passed through a cooling zone filled with an inert gas such as nitrogen or argon to obtain the solder particles 1. Since the above-mentioned conveyor furnace can be processed at atmospheric pressure, a film-like material can also be continuously processed in a roll-to-roll manner. For example, a continuous roll product of the substrate 60 filled with the solder fine particles 111 is produced, a roll unwinding machine is installed on the inlet side of the conveyor furnace, and a roll winding machine is installed on the outlet side of the conveyor furnace. The substrate 60 is conveyed at a constant speed and passed through each zone in the conveyor furnace, whereby the solder fine particles 111 filled in the concave portion can be fused.

[0102] According to the preparation process - fusion process, solder particles 1 with a uniform size can be formed regardless of the material and shape of the solder fine particles 111. For example, indium-based solder can be deposited by plating, but it is difficult to deposit it in a particulate form and it is soft and difficult to handle. However, by using indium-based solder fine particles as raw materials in the above method, indium-based solder particles with a uniform particle diameter can be easily manufactured. In addition, since the formed solder particles 1 can be handled in a state of being accommodated in the recess 62 of the substrate 60, they can be transported, stored, etc. without being deformed. Furthermore, since the formed solder particles 1 are in a state of being accommodated in the recess 62 of the substrate 60, they can be brought into contact with the electrodes without deforming the solder particles. The average particle diameter of the obtained solder particles may be 1 to 35 μm, and the C.V. value may be 20% or less.

[0103] Also, the solder fine particles 111 may have a large variation in particle size distribution or may have an irregular shape, and can be suitably used as a raw material as long as they can be accommodated in the recess 62.

[0104] In addition, in the above method, the shape of the recess 62 of the substrate 60 can be freely designed by lithography, machining, imprint technology, etc. Since the size of the solder particles 1 depends on the amount of the solder fine particles 111 accommodated in the recess 62, the size of the solder particles 1 can be freely designed by the design of the recess 62.

[0105] <Method for manufacturing an electrode substrate with solder bumps> The method for manufacturing an electrode substrate with solder bumps includes a preparation step of preparing the above-described solder bump forming member and a substrate having a plurality of electrodes, an arrangement step of opposing the surface having the recess of the solder bump forming member and the surface having the electrodes of the substrate and bringing the solder particles and the electrodes into contact with each other, and a heating step of heating the solder particles to a temperature equal to or higher than the melting point of the solder particles.

[0106] Specific examples of a substrate (circuit member) having a plurality of electrodes on its surface include chip components such as IC chips (semiconductor chips), resistor chips, capacitor chips, driver ICs, etc.; and rigid package substrates. These circuit members are provided with circuit electrodes, and those having a large number of circuit electrodes are common. Other examples of a substrate having a plurality of electrodes on its surface include wiring substrates such as flexible tape substrates having metal wiring, flexible printed wiring boards, and glass substrates vapor-deposited with indium tin oxide (ITO).

[0107] Specific examples of the electrodes include electrodes such as 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. The electrodes can be formed by electroless plating, electrolytic plating, sputtering, or etching of a metal foil.

[0108] FIGS. 6(a) and 6(b) are cross-sectional views schematically showing an example of the manufacturing process of an electrode substrate with solder bumps. The substrate 60 shown in FIG. 6(a) is in a state where one solder particle 1 is accommodated in each of the recesses 62. On the other hand, the substrate 2 has a plurality of electrodes 3 on its surface. The substrate 2 and the substrate 60 are brought closer to each other (arrows A and B in FIG. 6(a)) until the solder particles 1 accommodated in the recesses 62 of the substrate 60 come into contact with the electrodes 3 with the surface of the electrode 3 side of the substrate 2 facing the opening side surface of the recesses 62 of the substrate 60. The number of solder particles 1 contacting each electrode 3 is not particularly limited, and may be one particle per electrode or a plurality of particles per electrode. Since the force acting between the solder particles 1 and the recesses 62 (for example, an intermolecular force such as van der Waals force) is greater than the gravitational force applied to the solder particles 1, even if the main surface of the substrate 60 is facing downward, the solder particles 1 remain in the recesses 62 without falling off. Further, at least a part of the solder particles 1 is in contact with the bottom and / or inner wall portion of the recesses 62, and when having a flat portion, the solder particles 1 are in close contact with the recesses 62 and are difficult to fall off.

[0109] In this state, by heating the whole to a temperature higher than the melting point of the solder particles 1 (for example, 130 to 260 °C) at least, the solder particles 1 melt, and solder bumps are formed on the electrodes 3. From the viewpoint of more suitably performing the bonding between the solder particles 1 and the electrodes 3, in the heating step, the solder particles 1 may be heated to a temperature equal to or higher than the melting point of the solder particles while bringing the solder particles 1 and the electrodes 3 into contact with each other in a pressurized state. The pressurized state is a state in which the solder bump forming member 10 and the substrate 2 are pressed against each other in the directions of arrows A and B in Fig. 6(a) with a force of about 20 to 600 MPa.

[0110] Due to the influence of the oxide film, the solder particles 1 may not melt or may not wet and spread even when heated to a temperature equal to or higher than the melting point. Therefore, after exposing the solder particles 1 to a reducing atmosphere to remove the surface oxide film of the solder particles 1, the solder particles 1 can be melted by heating to a temperature equal to or higher than the melting point of the solder particles 1. Further, the melting of the solder particles 1 is preferably performed in a reducing atmosphere. By heating the solder particles 1 to a temperature equal to or higher than the melting point of the solder particles 1 and providing 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 it easier for the melting and wetting spread of the solder particles 1 to proceed efficiently. That is, the method for manufacturing an electrode substrate with solder bumps may further include a reducing step of exposing the solder particles (and / or electrodes) to a reducing atmosphere before the placement step or after the placement step and before the heating step. Further, in the heating step of the method for manufacturing an electrode substrate with solder bumps, the solder particles may be heated to a temperature equal to or higher than the melting point of the solder particles in a reducing atmosphere. In the heating step of forming solder bumps on the electrodes, by bringing the opening surface of the electrode and the solder bump forming member into close contact (in a pressurized state if necessary), solder bumps are formed only on the electrodes, and it is easy to suppress bridges due to solder between adjacent electrodes.

[0111] Regarding the details of the reducing atmosphere, the description of the method for manufacturing the solder bump forming member can be appropriately referred to.

[0112] After the heating process, by cooling the whole, the electrodes 3 and the solder bumps 1A formed by melting the solder particles 1 are fixed to each other, and the two are electrically connected. The method for manufacturing an electrode substrate with solder bumps may further include a removing step of removing the solder bump forming member from the substrate after the heating step. After the solder bumps 1A are formed on the electrodes 3, by removing the solder bump forming member 10 from the substrate 2 (removing step), an electrode substrate 20 with solder bumps can be obtained. FIG. 6(b) is a schematic diagram of the electrode substrate 20 with solder bumps thus obtained. It is preferable that there are alignment marks on the surfaces of the solder bump forming member and the substrate, as it facilitates alignment. For example, when the concave portion of the solder bump forming member faces the electrode surface side of the substrate surface, the position of the concave portion of the solder bump forming member and the position of the electrode on the substrate surface are arranged in advance at the relative positions. Solder particles are arranged in the concave portion of the solder bump forming member, the opening surface side of the concave portion of the solder bump forming member and the electrode surface side of the base material are opposed to each other, and after adjusting the position between the electrode on which the solder bump is to be formed and the concave portion of the solder bump forming member using the alignment mark, the solder bump can be formed on the electrode by the above-mentioned various methods. By this method, the solder bump can be formed only on a specific electrode. For example, by providing in advance the concave portion of the solder bump forming member at a position relative to the position of a specific electrode with respect to a plurality of electrodes on the surface of the base material, the solder bump can be formed only on the specific electrode on the surface of the base material. Further, one solder bump can be formed on one electrode.

[0113] On the obtained electrode substrate 20 with solder bumps, there may exist solder particles 1 that have detached from the concave portion 62 and are not used for bonding to the electrodes 3. Therefore, the method for manufacturing an electrode substrate with solder bumps may further include a cleaning step of removing the solder particles 1 not bonded to the electrodes after the removing step. Examples of the cleaning method include blowing compressed air, rubbing the substrate surface with a non-woven fabric or a bundle of fibers, and the like.

[0114] According to the method for manufacturing an electrode substrate with solder bumps, an electrode substrate 20 with solder bumps can be obtained, which includes a substrate 2, an electrode 3, and a solder bump 1A in this order.

[0115] <Method for manufacturing a connection structure> FIGS. 7(a) and 7(b) are cross-sectional views schematically showing an example of the manufacturing process of the connection structure. The method for manufacturing the connection structure will be described with reference to FIGS. 7(a) and 7(b). First, an electrode substrate 20 with solder bumps shown in FIG. 6(b) is prepared in advance. Also, another substrate 4 having a plurality of other electrodes 5 is prepared. Then, both are arranged such that the solder bump 1A and the other electrode 5 face each other. After that, while keeping the solder bump 1A and the other electrode 5 in contact, at least heating is performed to a temperature higher than the melting point of the solder bump 1A (for example, 130°C to 260°C), so that the solder bump 1A melts between the electrode 3 and the other electrode 5. Then, by cooling the whole, a solder layer 1B is formed between the electrode 3 and the other electrode 5, and the electrodes are electrically connected. In order to suppress the oxidation of the solder bump 1A and the electrode 5, it is preferable to heat in an atmosphere where oxygen is blocked. For example, heating in an inert gas atmosphere such as nitrogen is preferable. Specifically, a vacuum reflow furnace, a nitrogen reflow furnace, etc. can be used.

[0116] Furthermore, in order to dissolve the solder bump 1A by heating and more suitably join the opposing electrode 3 and electrode 5, it is preferable to heat in a reducing atmosphere. In order to create a reducing atmosphere, hydrogen gas, hydrogen radicals, formic acid, etc. can be used. Specifically, a hydrogen reduction furnace, a hydrogen reflow furnace, a hydrogen radical furnace, a formic acid furnace, these vacuum furnaces, continuous furnaces, conveyor furnaces 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, so that the solder bump 1A easily wets and spreads on the electrode 5, and a more stable joint is achieved between the electrode 3 and the electrode 5 through the solder layer 1B.

[0117] Furthermore, in order to achieve a stable connection, pressure may be applied. Prepare in advance an electrode substrate 20 with solder bumps shown in Fig. 6(b). Also, prepare another substrate 4 having a plurality of other electrodes 5 on its surface. Then, arrange the two so that the solder bumps 1A and the other electrodes 5 face each other. Thereafter, apply pressure in the thickness direction of the laminate of these members (the directions of arrow A and arrow B shown in Fig. 7(a)). When applying pressure, at least heat the whole to a temperature higher than the melting point of the solder bumps 1A (for example, 130 to 260 °C), so that the solder bumps 1A melt between the electrode 3 and the other electrodes 5. Thereafter, by cooling the whole, a solder layer 1B is formed between the electrode 3 and the other electrodes 5, and the electrodes are electrically connected. Also in this case, in order to suppress oxidation of the solder bumps 1A, the electrodes 5, and the surface of the electrode 3, it is preferable to perform the above steps under vacuum, in an inert gas atmosphere such as nitrogen, or in a reducing atmosphere. Examples of methods for creating a reducing atmosphere include the aforementioned hydrogen gas, hydrogen radicals, formic acid, etc. Specifically, a hydrogen reduction furnace, a hydrogen reflow furnace, a hydrogen radical furnace, a formic acid furnace, a vacuum furnace, a continuous furnace, a conveyor furnace, etc. of these can be used.

[0118] As a method for creating a reducing atmosphere, materials with a reducing effect can be utilized. For example, a flux material or a material containing a flux component can be disposed in the vicinity of solder bump 1A or electrodes 5 and 3. Pastes, films, etc. containing a flux material and a material containing a flux component can be used. First, an electrode substrate 20 with solder bumps as shown in Fig. 6(b) is prepared in advance. A paste containing a flux material or a flux component is disposed over the entire surface of the electrode substrate 20 where the solder bumps 1A are formed, or in the vicinity of the solder bumps 1A and electrode 3 including the solder bumps 1A. Also, another substrate 4 having a plurality of other electrodes 5 on its surface is prepared. Then, the two are arranged such that the solder bumps 1A and the other electrodes 5 face each other. Thereafter, while keeping the solder bumps 1A and the other electrodes 5 in contact via, for example, a paste containing a flux material or a flux component, at least heating is performed to a temperature higher than the melting point of the solder bumps 1A (for example, 130°C to 260°C), so that the solder bumps 1A melt between electrode 3 and the other electrodes 5. Then, by cooling the whole, a solder layer 1B is formed between electrode 3 and the other electrodes 5, and the electrodes are electrically connected. Thereafter, when the flux component is washed away, corrosion of the solder layer 1B, electrode 3, and electrode 5 can be suppressed by the flux residue.

[0119] As another method, an electrode substrate 20 with solder bumps as shown in Fig. 6(b) is prepared in advance. Also, another substrate 4 having a plurality of other electrodes 5 on its surface is prepared, and a paste containing a flux material or a flux component is disposed over the entire surface of the substrate 4 having the electrodes 5, or in the vicinity of the surface of the electrodes 5. Then, the two are arranged such that the solder bumps 1A and the other electrodes 5 face each other. Thereafter, while keeping the solder bumps 1A and the other electrodes 5 in contact via, for example, a paste containing a flux material and a flux component, at least heating is performed to a temperature higher than the melting point of the solder bumps 1A (for example, 130°C to 260°C), so that the solder bumps 1A melt between electrode 3 and the other electrodes 5. Then, by cooling the whole, a solder layer 1B is formed between electrode 3 and the other electrodes 5, and the electrodes are electrically connected.

[0120] Also, a film containing a flux component can be used. Prepare in advance an electrode substrate 20 with solder bumps as shown in Fig. 6(b). Place a film containing a flux component on the side of the electrode substrate 20 where the solder bumps 1A are formed. Also, prepare another substrate 4 having a plurality of other electrodes 5 on its surface. Then, arrange the two so that the solder bumps 1A and the other electrodes 5 face each other. After that, while keeping the solder bumps 1A and the other electrodes 5 in contact with each other via the film containing a flux component, or by applying pressure between the opposing electrodes 3 and 5 to push out the film containing a flux component from between them, heat at least to a temperature higher than the melting point of the solder bumps 1A (for example, 130°C to 260°C) with the solder bumps 1A and the electrodes 5 in contact, so that the solder bumps 1A melt between the electrode 3 and the other electrodes 5. Then, by cooling the whole, a solder layer 1B is formed between the electrode 3 and the other electrodes 5, and the electrodes are electrically connected.

[0121] The paste and film containing a flux component may contain a thermosetting material. Thereby, simultaneously with the melting of the solder bumps 1A, the thermosetting component can be cured to fix the electrode substrate 20 and the substrate 4. The curing of the thermosetting material may be carried out by reheating in a subsequent process separately from the heating for melting the solder bumps 1A. Also, the film containing a flux component may be placed in advance on the side of the substrate 4 where the electrodes 5 are formed. The choice of the placement position, whether to place the film containing a flux component on the side of the solder bumps 1A or on the side of the substrate 4 having the electrodes 5, can be appropriately selected according to the shape of the electrodes, the shape and size of the solder bumps 1A, the convenience in the bonding process, etc.

[0122] As a method for manufacturing the connection structure, it is also possible to perform electrode - to - electrode sealing with resin simultaneously with soldering. A connection structure can be obtained in the same manner as in the case of using a film containing a flux component, except that an insulating resin layer (resin film) is used instead of the film containing a flux component. Thereby, the electrode 3 and the other electrode 5 are connected via the solder bump 1A, and the space between the substrate 2 and the substrate 4 is filled with the insulating resin layer. At this time, if the insulating resin layer is a material having thermosetting properties, it is preferable because the substrate 2 and the substrate 4 are firmly fixed, and the electrode 3, the solder layer 1B, and the other electrode 5 are sealed, suppressing corrosion and oxidation of the electrodes and the solder due to moisture, oxygen, etc.

[0123] As a heating method for melting the solder bump 1A, under vacuum, for example, there are a method of heating a heating plate in a reflow furnace and transmitting heat to the solder bump 1A through the substrate 2 and the substrate 4 in contact with the heating plate, a method using radiation such as infrared rays, etc. Further, in addition to or in combination with the above - mentioned heating method using the heating plate or infrared rays, a method of heating the solder bump 1A through heated gas and gas can be used. Specifically, the solder bump 1A can be heated by heating an inert gas, nitrogen, hydrogen, hydrogen radicals, and formic acid. The flux material and the flux component may contain at least one selected from the group consisting of succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, benzoic acid, and malic acid.

[0124] As another method, there is a method of using electromagnetic waves such as microwaves. For example, specific electromagnetic waves that heat the components of the electrode 3, the electrode 5, and the solder bump 1A can be applied from the outside. For example, when the substrates 4 and 2 are resin substrates, when specific electromagnetic waves are irradiated from the outside of the substrates 4 and 2, the electromagnetic waves penetrate the substrates 4 and 2, and the electrode 3 and the solder bump 1A or the electrode 5 are heated by the electromagnetic waves. In the case of this method, since the portion to be joined can be selectively heated, there is an advantage that no unnecessary heat history remains. For example, even if the substrates 2 and 4 are made of materials with low heat resistance, the solder bump 1A can be melted to surely join the electrode 3 and the electrode 5. In addition, since it is difficult for a heat history to remain in the entire joining system, there is an advantage that warping and decomposition after joining are easily suppressed. Further, when using microwaves, the solder bump 1A can be melted in a shorter time than using a heating plate, infrared rays, a heating gas, etc. as described above, so there is an advantage that the heat history to the entire system to be joined can be reduced, and the above-described effects are easily obtained. Furthermore, when using microwaves, only the portions of the electrode 3, the solder bump 1A, and the electrode 5 to be joined or melted can be locally heated. Therefore, there is no need to heat the entire system, and even if there are materials with low heat resistance and other electronic components that do not want to be heated in the vicinity of the electrode 3 and the electrode 5, the solder bump 1A can be melted and joined.

[0125] As another method, there is a method of using ultrasonic waves. For example, when an ultrasonic vibrator is arranged on the side opposite to the electrode 3 of the substrate 2 and ultrasonic waves are applied, the solder bump 1A is melted by the vibration energy of the ultrasonic waves. Thereby, the electrode 3 and the electrode 5 previously arranged at the opposing position of the electrode 3 are joined via the solder layer 1B. Since the joining by ultrasonic waves can melt the solder bump 1A in a short time, there is no need to heat the entire substrates 2 and 4, and even if the substrates 2 and 4 are made of materials with low heat resistance, the electrode 3 and the electrode 5 can be surely joined.

[0126] Figure 7(b) is a schematic diagram of the connection structure 30 thus obtained. That is, Figure 7(b) schematically shows a state in which the electrode 3 of the substrate 2 and the other electrode 5 of the other substrate 4 are connected via the solder layer 1B formed by fusion. In this specification, "fusion" means a state in which at least a part of the electrode is joined by molten solder (solder bump 1A) due to heat and then solidifies, and solder is joined to the surface of the electrode through this process. The connection structure 30 can be said to include a first circuit member including a substrate and a plurality of electrodes on its surface, a second circuit member including 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. Note that the space between the first circuit member and the second circuit member can be filled with an underfill material mainly composed of, for example, an epoxy resin.

[0127] Examples of the application target of the connection structure include connection parts such as semiconductor memories and semiconductor logic chips, connection parts for primary and secondary mounting of semiconductor packages, bonded bodies such as CMOS image sensor elements, laser elements, and LED light-emitting elements, and devices such as cameras, sensors, liquid crystal displays, personal computers, mobile phones, smartphones, and tablets using these.

[0128] As described above, the preferred embodiments of the present invention have been described, but the present invention is not limited to the above embodiments.

Example

[0129] Hereinafter, the present invention will be described in more detail by way of examples, but the present invention is not limited to these examples.

[0130] <Fabrication of Film for Solder Bump Formation> (Fabrication Example 1) Step a1: Classification of Solder Particles 100 g of Sn-Bi solder particles (manufactured by 5N Plus, melting point 139 °C, Type 8) were immersed in distilled water, ultrasonically dispersed, allowed to stand, and the solder particles floating in the supernatant were collected. This operation was repeated to collect 10 g of solder particles. The average particle size of the obtained solder particles was 1.0 μm, and the C.V. value was 42%. Step b1: Placement on the substrate A substrate (polyimide film, thickness 100 μm) having a plurality of recesses with an opening diameter of 2.3 μmφ, a bottom diameter of 2.0 μmφ, and a depth of 1.5 μm (the bottom diameter of 2.0 μmφ is located at the center of the opening diameter of 2.3 μmφ when viewed from above the opening) shown in Table 1 was prepared. The plurality of recesses were regularly arranged at intervals of 1.0 μm. The solder particles obtained in step a (average particle size 1.0 μm, C.V. value 42%) were placed in the recesses of the substrate. In addition, by rubbing the surface side where the recesses of the substrate were formed with a microadhesive roller, excess solder particles were removed, and a substrate having solder particles arranged only in the recesses was obtained. Step c1: Formation of solder particles The substrate with solder particles placed in the recesses in step b1 was placed in a hydrogen reduction furnace (manufactured by Shinko Seiki Co., Ltd., vacuum soldering apparatus). After evacuation, hydrogen gas was introduced into the furnace to fill the furnace with hydrogen. Then, after maintaining the furnace at 280 °C for 20 minutes, it was evacuated again, nitrogen was introduced to return to atmospheric pressure, and then the temperature in the furnace was lowered to room temperature to form solder particles. A film for forming solder bumps having solder particles in the recesses was obtained.

[0131] <Evaluation of the film for forming solder bumps> A part of the film for forming solder bumps obtained through step c1 was fixed to the surface of the SEM observation pedestal, and platinum sputtering was performed on the surface. The diameters of 300 solder particles were measured with an SEM, and the average particle size and C.V. value were calculated. The results are shown in Table 2. In addition, the surface shape of a part of the film for forming solder bumps obtained through step c1 was measured using a laser microscope (manufactured by Olympus Corporation, LEXT OLS5000 - SAF), the height of the solder particles from the substrate surface was measured, and the average value of 300 was calculated. The results are shown in Table 2.

[0132] (Production Examples 2 to 6) A solder bump forming film was produced and evaluated in the same manner as in Production Example 1, except that the size of the concave portion and the like were changed as described in Table 1. The results are shown in Table 2.

[0133] (Production Example 7) A solder bump forming film was produced and evaluated in the same manner as in Production Example 1, except that the following step c2 was performed instead of step c1. The results are shown in Table 2. Step c2: Formation of solder particles The substrate with solder fine particles disposed in the concave portion in step b1 was put into a hydrogen radical reduction furnace (manufactured by Shinko Seiki Co., Ltd., plasma flow device), evacuated, and then hydrogen gas was introduced into the furnace to fill the furnace with hydrogen gas. Thereafter, the temperature inside the furnace was adjusted to 120 °C and irradiated with hydrogen radicals for 5 minutes. Thereafter, the hydrogen gas inside the furnace was removed by evacuation, heated to 170 °C, then nitrogen was introduced into the furnace to return to atmospheric pressure, and then the temperature inside the furnace was lowered to room temperature to form solder particles. A solder bump forming film having solder particles in the concave portion was obtained.

[0134] (Production Examples 8 to 12) A solder bump forming film was produced and evaluated in the same manner as in Production Example 7, except that the size of the concave portion and the like were changed as described in Table 1. The results are shown in Table 2.

[0135] (Production Example 13) A solder bump forming film was produced and evaluated in the same manner as in Production Example 1, except that the following step c3 was performed instead of step c1. The results are shown in Table 2. Step c3: Formation of solder particles The substrate with solder fine particles disposed in the concave portion in step b1 was put into a formic acid reduction furnace, evacuated, and then formic acid gas was introduced into the furnace to fill the furnace with formic acid gas. Thereafter, the temperature inside the furnace was adjusted to 130 °C and held for 5 minutes. Thereafter, the formic acid gas inside the furnace was removed by evacuation, heated to 180 °C, then nitrogen was introduced into the furnace to return to atmospheric pressure, and then the temperature inside the furnace was lowered to room temperature to form solder particles. A solder bump forming film having solder particles in the concave portion was obtained.

[0136] (Production Examples 14 to 18) A solder bump forming film was produced and evaluated in the same manner as in Production Example 13, except that the size of the concave portion and the like were changed as shown in Table 1. The results are shown in Table 2.

[0137] (Production Example 19) A solder bump forming film was produced and evaluated in the same manner as in Production Example 1, except that the following step c4 was performed instead of step c1. The results are shown in Table 2. Step c4: Formation of solder particles The substrate with solder fine particles disposed in the concave portion in step b1 was put into a formic acid conveyor reflow furnace (manufactured by Heller Industries, Inc., 1913MK), and while being conveyed by the conveyor, it was continuously passed through a nitrogen zone adjusted to 190 °C, a nitrogen and formic acid gas mixed zone, and a nitrogen zone. The nitrogen and formic acid gas mixed zone was passed through for 20 minutes to form a solder bump forming film.

[0138] (Production Examples 20 to 24) A solder bump forming film was produced and evaluated in the same manner as in Production Example 19, except that the size of the concave portion and the like were changed as shown in Table 1. The results are shown in Table 2.

[0139]

Table 1

[0140]

Table 2

[0141] <Fabrication of Evaluation Chip with Solder Bumps> Step d1: Preparation of evaluation chip Seven types of chips with gold bumps (3.0 × 3.0 mm, thickness: 0.5 mm) shown below were prepared. Chip C1… Area 100 μm × 100 μm, space 40 μm, height: 10 μm, number of bumps 362 Chip C2… Area: 75μm × 75μm, Space: 20μm, Height: 10μm, Number of bumps: 362 Chip C3… Area: 40μm × 40μm, Space: 16μm, Height: 7μm, Number of bumps: 362 Chip C4… Area: 20μm × 20μm, Space: 7μm, Height: 5μm, Number of bumps: 362 Chip C5… Area: 10μm × 10μm, Space: 6μm, Height: 3μm, Number of bumps: 362 Chip C6… Area: 10μm × 10μm, Space: 4μm, Height: 3μm, Number of bumps: 362 Chip C7… Area: 5μm × 10μm, Space: 3μm, Height: 2μm, Number of bumps: 362

[0142] Process e1: Solder bump formation Following the procedures of i) to iii) shown below, using the solder bump formation film (Production Example 7) prepared in Process c2, solder bumps were formed on the chip with gold bumps (3.0 × 3.0 mm, thickness: 0.5 mm). i) A glass plate with a thickness of 0.3 mm was placed on the lower hot plate of a formic acid reflow furnace (manufactured by Shinkou Seiki Co., Ltd., batch-type vacuum soldering device), and the evaluation chip was placed on the glass plate with the gold bumps facing up. ii) The surface of the solder bump formation film where the solder particles were exposed was turned downward and arranged so that the solder particles came into contact with the gold bump surface of the evaluation chip. Further, a glass plate with a thickness of 0.3 mm was placed on the solder bump formation film to make the solder particles adhere closely to the gold bumps. iii) The formic acid vacuum reflow furnace was operated. After evacuation, it was filled with formic acid gas, the lower hot plate was heated to 150°C and heated for 5 minutes. Then, after discharging the formic acid gas by evacuation, nitrogen substitution was performed, the lower hot plate was returned to room temperature, and the inside of the furnace was opened to the atmosphere. The top glass plate and the solder bump formation film were removed in order to obtain an evaluation chip with solder bumps.

[0143] <Evaluation of solder bumps> The evaluation chip obtained through process e1 was fixed on the surface of the pedestal for SEM observation, and platinum sputtering was performed on the surface. With an SEM, for 30 gold bumps, the number of solder bumps placed on the gold bumps was counted, and the average number of solder bumps placed on one gold bump was calculated. The results are shown in Table 3. Also, using a laser microscope (manufactured by Olympus Corporation, LEXT OLS5000 - SAF), the height of the solder bumps from the gold bumps was measured, and the average value of 100 was calculated. The results are shown in Table 3.

[0144] Solder bump formation was performed in the same manner as above, except that the solder bump forming films of Preparation Examples 8 to 12 were used instead of the solder bump forming film of Preparation Example 7. The evaluation results are shown in Table 3.

[0145] Figure 8(a) is an SEM image of a part of the gold bumps of chip C4. Figure 8(b) is an SEM image after forming solder bumps on the gold bumps of chip C4 using the solder bump forming film of Preparation Example 8. The solder bumps are formed only on the gold bumps, and no solder particles and solder material derived from the solder bumps are seen between the gold bumps.

[0146]

Table 3

[0147] <Fabrication of the connection structure> Process f1: Preparation of the evaluation substrate Seven types of substrates with gold bumps (70×25 mm, thickness: 0.5 mm) shown below were prepared. Note that lead - out wirings for resistance measurement were also formed on these gold bumps. Substrate D1… Area 100 μm×100 μm, space 40 μm, height: 4 μm, number of bumps 362 Substrate D2… Area 75 μm×75 μm, space 20 μm, height: 4 μm, number of bumps 362 Substrate D3… Area 40 μm×40 μm, space 16 μm, height: 4 μm, number of bumps 362 Substrate D4… Area: 20μm × 20μm, Space: 7μm, Height: 4μm, Number of Bumps: 362 Substrate D5… Area: 10μm × 10μm, Space: 6μm, Height: 3μm, Number of Bumps: 362 Substrate D6… Area: 10μm × 10μm, Space: 4μm, Height: 3μm, Number of Bumps: 362 Substrate D7… Area: 5μm × 10μm, Space: 3μm, Height: 3μm, Number of Bumps: 362

[0148] Process g1: Bonding of Electrodes Following the procedures of i) to iii) shown below, the evaluation chip with solder bumps fabricated in Process e1 was used to connect to the evaluation substrate with gold bumps via the solder bumps. i) The evaluation substrate was placed on the lower hot plate of a formic acid reflow furnace (manufactured by Shinko Seiki Co., Ltd., batch-type vacuum soldering device) with the gold bumps facing up. ii) The solder bump surface of the evaluation chip with solder bumps was oriented downward, and it was arranged so that the solder bumps contacted the gold bump surface of the evaluation substrate and fixed in place so that it did not move. iii) The formic acid vacuum reflow furnace was operated. After evacuation, it was filled with formic acid gas, the temperature of the lower hot plate was raised to 180°C, and it was heated for 5 minutes. Then, after discharging the formic acid gas by evacuation, nitrogen replacement was performed, the temperature of the lower hot plate was returned to room temperature, and the furnace was opened to the atmosphere. An appropriate amount of underfill material (CEL series, manufactured by Hitachi Chemical Co., Ltd.) with adjusted viscosity was placed between the evaluation chip and the evaluation substrate. After filling by evacuation, it was cured at 125°C for 3 hours to fabricate the connection structure of the evaluation chip and the evaluation substrate. The combinations of each material in the connection structure are as follows. (1) Chip C1 / Solder Bump Formation Film / Substrate D1 (2) Chip C2 / Solder Bump Formation Film / Substrate D2 (3) Chip C3 / Solder Bump Formation Film / Substrate D3 (4) Chip C4 / Solder Bump Formation Film / Substrate D4 (5) Chip C5 / Solder Bump Formation Film / Substrate D5 (6) Chip C6 / Solder Bump Formation Film / Substrate D6 (7) Chip C7 / Film for Forming Solder Bumps / Substrate D7

[0149] <Evaluation of Connection Structure> For a part of the obtained connection structure, the conduction resistance test and the insulation resistance test were carried out as follows.

[0150] (Conduction Resistance Test - Damp Heat, Steady State Test) Regarding the conduction resistance between the chip with gold bumps (bumps) and the substrate with gold bumps (bumps), the initial value of the conduction resistance and the values after the damp heat, steady state test (left standing for 100, 500, and 1000 hours under the conditions of temperature 85°C and humidity 85%) were measured for 20 samples, and their average values were calculated. The conduction resistance was evaluated according to the following criteria from the obtained average values. The results are shown in Table 4. Note that when the following criteria A or B are satisfied after 1000 hours of the damp heat, steady state test, it can be said that the conduction resistance is good. A: The average value of the conduction resistance is less than 2 Ω B: The average value of the conduction resistance is 2 Ω or more and less than 5 Ω C: The average value of the conduction resistance is 5 Ω or more and less than 10 Ω D: The average value of the conduction resistance is 10 Ω or more and less than 20 Ω E: The average value of the conduction resistance is 20 Ω or more

[0151] (Conduction Resistance Test - High Temperature Storage Test) Regarding the conduction resistance between the chip with gold bumps (bumps) and the substrate with gold bumps (bumps), the initial value of the conduction resistance and the values after the high temperature storage test (left standing for 100, 500, and 1000 hours under the condition of temperature 100°C) were measured for 20 samples. Note that after the high temperature storage, a drop impact was applied, and the conduction resistance of the samples after the drop impact was measured. The drop impact was generated by fixing the connection structure to a metal plate with screws and dropping it from a height of 50 cm. After dropping, the DC resistance values were measured at the solder joints (4 locations) of the chip corner with the most impact, and when the measured value increased by 5 times or more from the initial resistance, it was regarded that breakage occurred and the evaluation was carried out. Note that for each sample, 4 measurements were made at 4 locations, for a total of 80 measurements. The results are shown in Table 5. When the following criteria A or B are satisfied after 20 drops, it was evaluated that the solder joint reliability is good. A: There were 0 solder joints with a resistance increase of more than 5 times the initial resistance. B: There were 1 or more and 5 or fewer solder joints with a resistance increase of more than 5 times the initial resistance. C: There were 6 or more and 20 or fewer solder joints with a resistance increase of more than 5 times the initial resistance. D: There were 21 or more solder joints with a resistance increase of more than 5 times the initial resistance.

[0152] (Insulation Resistance Test) Regarding the insulation resistance between chip electrodes, the initial value of the insulation resistance and the values after the migration test (left for 100, 500, and 1000 hours under the conditions of a temperature of 60 °C, a humidity of 90%, and an applied voltage of 20 V) were measured for 20 samples. Among all 20 samples, the proportion of samples with an insulation resistance value of 10 9 Ω or more was calculated. The insulation resistance was evaluated according to the following criteria based on the obtained proportion. The results are shown in Table 6. Note that if the following criteria A or B are met after 1000 hours of the migration test, it can be said that the insulation resistance is good. A: The proportion of samples with an insulation resistance value of 10 9 Ω or more is 100% B: The proportion of samples with an insulation resistance value of 10 9 Ω or more is 90% or more and less than 100% C: The proportion of samples with an insulation resistance value of 10 9 Ω or more is 80% or more and less than 90% D: The proportion of samples with an insulation resistance value of 10 9 Ω or more is 50% or more and less than 80% E: The proportion of samples with an insulation resistance value of 10 9 Ω or more is less than 50%

[0153]

Table 4

[0154]

Table 5

[0155]

Table 6

[0156] <Production of Film for Forming Solder Bumps> (Production Example 25) Step h1: Production of Substrate A liquid photosensitive resist (AH series, manufactured by Hitachi Chemical Co., Ltd.) was spin-coated on a 6-inch silicon wafer to a thickness of 1.5 μm. The photosensitive resist on this silicon wafer was exposed and developed to obtain a substrate 25 having recesses with an opening diameter of 3.1 μmφ, a bottom diameter of 2.0 μmφ, and a depth of 1.5 μm (the bottom diameter of 2.0 μmφ is located at the center of an opening diameter of 2.3 μmφ when viewed from above the opening). These recesses were arranged at positions (X-direction pitch, Y-direction pitch) relative to the electrode arrangement pattern of the evaluation substrate. Also, three alignment marks were arranged on the surface of the substrate 25 simultaneously with the formation of the recesses. The outline of the substrate 25 is shown in Table 7.

[0157] [Table 7]

[0158] Solder fine particles were obtained in the same manner as in Step a1, and solder fine particles were arranged in the recesses in the same manner as in Step b1 except that the substrate 25 was used, and a film 25 for forming solder bumps having solder particles in the recesses was obtained by Step c3.

[0159] <Evaluation of Film for Forming Solder Bumps> A part of the film 25 for forming solder bumps was fixed to the surface of the SEM observation pedestal, and platinum sputtering was performed on the surface. The diameters of 300 solder particles were measured by SEM, and the average particle diameter and C.V. value were calculated. The results are shown in Table 8. Also, the surface shape of a part of the film 25 for forming solder bumps was measured using a laser microscope (LEXT OLS5000 - SAF, manufactured by Olympus Corporation), the height of the solder particles from the substrate surface was measured, and the average value of 300 was calculated. The results are shown in Table 8.

[0160] [Table 8]

[0161] (Production Examples 26 to 30) The thickness of the photosensitive resist was changed to the value of the depth shown in Table 7, and the recess size was also changed as described in Table 7. A solder bump forming film was produced and evaluated in the same manner as in Production Example 25, except that the arrangement position of the recesses was set to the position relative to the electrode arrangement pattern of the evaluation substrate described in Table 7. The results are shown in Table 8.

[0162] (Fabrication of Evaluation Chip with Solder Bumps) Step d2: Preparation of Evaluation Chip Six types of chips with gold bumps (5×5 mm, thickness: 0.5 mm) shown below were prepared. Chip C8… Electrode size: 8μm×4μm, pitch: 16μm in the X direction, 8μm in the Y direction, number of bumps: 180,000 Chip C9… Electrode size: 16μm×8μm, pitch: 32μm in the X direction, 16μm in the Y direction, number of bumps: 46,000 Chip C10… Electrode size: 24μm×12μm, pitch: 48μm in the X direction, 24μm in the Y direction, number of bumps: 15,000 Chip C11… Electrode size: 72μm×36μm, pitch: 144μm in the X direction, 72μm in the Y direction, number of bumps: 3,400 Chip C12… Electrode size: 96μm×48μm, pitch: 192μm in the X direction, 96μm in the Y direction, number of bumps: 850 Chip C13… Electrode size: 140μm×70μm, pitch: 280μm in the X direction, 140μm in the Y direction, number of bumps: 420

[0163] Step e2: Solder Bump Formation Place the solder bump forming film 25 on the stage of FC3000W (manufactured by Toray Engineering Co., Ltd.), pick up the evaluation chip C8 by mounting it on the head, and use the alignment marks of both to align the solder particles placed in the recess of the solder bump forming film 25 with the electrode positions of the evaluation chip C8. Then, temporarily place the evaluation chip C8 on the solder bump forming film 25. After that, place it on the lower hot plate of a formic acid reflow furnace (manufactured by Shinko Seiki Co., Ltd., batch type vacuum soldering equipment), evacuate, fill with formic acid gas, heat the lower hot plate to 145 °C, and heat for 1 minute. Then, after discharging the formic acid gas by evacuation, perform nitrogen substitution, return the lower hot plate to room temperature, open the furnace to the atmosphere, transfer the solder particles onto the electrodes of the evaluation chip C8, and form solder bumps.

[0164] <Evaluation of Solder Bumps> Regarding the evaluation chips obtained through process e2, the number of solder particles that could be transferred (the number of solder bumps) was counted for 300 electrodes, and the transfer rate was calculated. Also, the height of the solder bumps was measured using a laser microscope (manufactured by Olympus Corporation, LEXT OLS5000 - SAF), and the average value of 300 was calculated. The results are shown in Table 9.

[0165]

Table 9

[0166] Solder bump formation was carried out in the same manner as in process e2, except that the solder bump forming films 26 - 30 and the evaluation chips C9 - C13 were used. Furthermore, for each evaluation chip, the transfer rate and the average height value were calculated in the same manner as above. The results are shown in Table 9.

[0167] <Fabrication of Connection Structure> Six types of evaluation substrates with gold bumps (70 × 25 mm, thickness: 0.5 mm) shown below were prepared. These gold bumps are arranged at positions facing the gold electrodes of the aforementioned evaluation chips C8 - C13, and alignment marks are arranged on the substrate. Also, lead - out wirings for resistance measurement are formed on a part of the gold bumps. Substrate D8… Area: 8 μm × 4 μm, Pitch: 16 μm in the X direction, 8 μm in the Y direction, Height: 2 μm, Number of bumps: 180,000 Substrate D9… Area: 16 μm × 8 μm, Pitch: 32 μm in the X direction, 16 μm in the Y direction, Height: 3 μm, Number of bumps: 46,000 Substrate D10… Area: 24 μm × 12 μm, Pitch: 48 μm in the X direction, 24 μm in the Y direction, Height: 3 μm, Number of bumps: 15,000 Substrate D11… Area: 72 μm × 36 μm, Pitch: 144 μm in the X direction, 72 μm in the Y direction, Height: 3 μm, Number of bumps: 3,400 Substrate D12… Area: 96 μm × 48 μm, Pitch: 192 μm in the X direction, 96 μm in the Y direction, Height: 3 μm, Number of bumps: 850 Substrate D13… Area: 140 μm × 70 μm, Pitch: 280 μm in the X direction, 140 μm in the Y direction, Height: 3 μm, Number of bumps: 420

[0168] Process g2: Bonding of electrodes Following the procedures of i) to iii) shown below, the evaluation chip with solder bumps fabricated in Process e2 was used to connect to the evaluation substrate with gold bumps via the solder bumps. i) The evaluation substrate D8 with gold bumps was placed on the stage of FC3000W (manufactured by Toray Engineering Co., Ltd.). The evaluation chip C8 with solder bumps was picked up with the head. The gold electrodes were opposed to each other using the alignment marks of both, and the evaluation chip C8 with solder bumps was placed on the evaluation substrate D8 with gold bumps to obtain the pre-bonding sample 8. ii) The pre-bonding sample 8 obtained in i) was placed on the lower hot plate of a formic acid reflow furnace (manufactured by Shinko Seiki Co., Ltd., batch-type vacuum soldering device). (iii) The formic acid vacuum reflow furnace was operated. After evacuation, it was filled with formic acid gas, the lower hot plate was heated to 160 °C and heated for 5 minutes. Then, after discharging the formic acid gas by evacuation, nitrogen replacement was performed, the lower hot plate was returned to room temperature, and the inside of the furnace was opened to the atmosphere. An appropriate amount of underfill material (CEL series, manufactured by Hitachi Chemical Co., Ltd.) with adjusted viscosity was placed between the evaluation chip and the evaluation substrate. After filling by evacuation, it was cured at 125 °C for 3 hours to fabricate a connection structure of the evaluation chip and the evaluation substrate. The combination of each material in the connection structure is as follows. (8) Chip C8 / Solder Bump Forming Film 25 / Substrate D8 (9) Chip C9 / Solder Bump Forming Film 26 / Substrate D9 (10) Chip C10 / Solder Bump Forming Film 27 / Substrate D10 (11) Chip C11 / Solder Bump Forming Film 28 / Substrate D11 (12) Chip C12 / Solder Bump Forming Film 29 / Substrate D12 (13) Chip C13 / Solder Bump Forming Film 30 / Substrate D13

[0169] <Evaluation of the Connection Structure> For a part of the obtained connection structure, a conduction resistance test and an insulation resistance test were performed in the same manner as above. The results are shown in Tables 10 to 12.

[0170]

Table 10

[0171]

Table 11

[0172]

Table 12

[0173] (Production Examples 31 to 36) Preparation of the substrate for Process h1 and preparation of the evaluation chips for Process d2, and further, obtaining the solder bump formation in Process e2, thus obtaining the evaluated chips C8 to C13 with solder bumps formed as shown in Table 9.

[0174] <Fabrication of the connection structure> Six types of evaluation substrates (70×25 mm, thickness: 0.5 mm) with gold bumps as shown below were prepared. These gold bumps are arranged at positions facing the gold electrodes of the aforementioned evaluation chips C8 to C13, and alignment marks are arranged on the substrate. Also, lead-out wirings for resistance measurement are formed on a part of the gold bumps. Substrate D8… Area 8μm×4μm, pitch: 16μm in the X direction, 8μm in the Y direction, height: 2μm, number of bumps: 180,000 Substrate D9… Area 16μm×8μm, pitch: 32μm in the X direction, 16μm in the Y direction, height: 3μm, number of bumps: 46,000 Substrate D10… Area 24μm×12μm, pitch: 48μm in the X direction, 24μm in the Y direction, height: 3μm, number of bumps: 15,000 Substrate D11… Area 72μm×36μm, pitch: 144μm in the X direction, 72μm in the Y direction, height: 3μm, number of bumps: 3,400 Substrate D12… Area 96μm×48μm, pitch: 192μm in the X direction, 96μm in the Y direction, height: 3μm, number of bumps: 850 Substrate D13… Area 140μm×70μm, pitch: 280μm in the X direction, 140μm in the Y direction, height: 3μm, number of bumps: 420

[0175] Process g3: Bonding of the electrodes Following the procedures of i) to vi) shown below, the evaluation chips with solder bumps fabricated in Process e2 were used to connect to the evaluation substrate with gold bumps via the solder bumps. i) The evaluation substrate with gold bumps was set on a spin coater, and a liquid flux (NS-334, manufactured by Arakawa Chemical Industries, Ltd.) was coated on the gold bump surface side. ii) Place the evaluation substrate with gold bumps obtained in i) on the stage of FC3000W (manufactured by Toray Engineering Co., Ltd.), pick up the evaluation chip with solder bumps using the head, align the gold electrodes with each other using the alignment marks on both sides, place the evaluation chip with solder bumps on the evaluation substrate with gold bumps, and obtain pre-bonding samples 14 to 19. iii) Place the pre-bonding sample on the lower hot plate of a formic acid reflow furnace (manufactured by Shinko Seiki Co., Ltd., batch-type vacuum soldering apparatus). iv) Operate the formic acid vacuum reflow furnace. After evacuation, fill it with nitrogen gas, heat the lower hot plate to 160 °C, and heat for 3 minutes. Then, after evacuation, perform nitrogen replacement, return the lower hot plate to room temperature, and open the furnace to the atmosphere. v) Immerse the bonded sample in isopropyl alcohol solution to wash away the flux residue. vi) Put an appropriate amount of underfill material (CEL series, manufactured by Hitachi Chemical Co., Ltd.) with adjusted viscosity between the evaluation chip and the evaluation substrate. After filling by evacuation, cure it at 125 °C for 3 hours to fabricate a connection structure of the evaluation chip and the evaluation substrate. The combinations of each material in the connection structure are as follows. (14) Chip C8 / Solder bump forming film 25 / Substrate D8 (15) Chip C9 / Solder bump forming film 26 / Substrate D9 (16) Chip C10 / Solder bump forming film 27 / Substrate D10 (17) Chip C11 / Solder bump forming film 28 / Substrate D11 (18) Chip C12 / Solder bump forming film 29 / Substrate D12 (19) Chip C13 / Solder bump forming film 30 / Substrate D13

[0176] <Evaluation of the connection structure> For a part of the obtained connection structure, perform a conduction resistance test and an insulation resistance test in the same manner as above. The results are shown in Tables 13 to 15.

[0177]

Table 13

[0178]

Table 14

[0179]

Table 15

Explanation of Symbols

[0180] 1… solder particle, 1A… solder bump, 1B… solder layer, 2… substrate, 3… electrode, 4… other substrate, 5… other electrode, 10… member for forming solder bump, 20… electrode substrate with solder bump, 30… connection structure, 60… base body, 62… recess, 111… fine solder particle, 600… base body, 601… base layer, 602… recess layer.

Claims

1. A substrate having a plurality of recesses and solder particles in the recesses, The solder particles have an average particle size of 1 to 35 μm and a CV value of 20% or less; A solder bump forming member, wherein a portion of the solder particle protrudes from the recess.

2. A substrate having a plurality of recesses and solder particles in the recesses, The solder particles have an average particle size of 1 to 35 μm and a CV value of 20% or less; In a cross-sectional view, the depth of the recess is H １ The height of the solder particles is H ２ Then, H １ <H ２ A solder bump forming member.

3. 3. The member for forming a solder bump according to claim 1, wherein a flat portion is formed on a part of the surface of the solder particle.

4. 4. The member for forming a solder bump according to claim 1, wherein the distance between adjacent recesses is 0.1 times or more the average particle diameter of the solder particles.

5. 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 recess; a fusing step of fusing the solder particles contained in the recesses to form solder particles in the recesses, with a portion of the solder particles protruding from the recesses; The method for manufacturing a solder bump forming member includes the steps of:

6. 6. The method according to claim 5, wherein the solder particles have an average particle size of 1 to 35 μm and a CV value of 20% or less.

7. The manufacturing method according to claim 5 or 6, wherein the C.V. value of the solder fine particles exceeds 20%.

8. 8. The manufacturing method according to claim 5, further comprising a reduction step of exposing the solder particles contained in the recess to a reducing atmosphere before the fusing step.

9. 9. The manufacturing method according to claim 5, wherein in the fusing step, the solder fine particles are fused in a reducing atmosphere.

10. A preparation step of preparing the solder bump forming member according to any one of claims 1 to 4 and a substrate having a plurality of electrodes; a placement step of placing the surface of the solder bump forming member having the recesses and the surface of the substrate having the electrodes opposite each other to bring the solder particles and the electrodes into contact with each other; a heating step of heating the solder particles to a temperature equal to or higher than the melting point of the solder particles; A method for manufacturing an electrode substrate with solder bumps, comprising:

11. The method according to claim 10 , wherein in the heating step, the solder particles are heated to a temperature equal to or higher than a melting point of the solder particles while the solder particles and the electrodes are in contact with each other under pressure.

12. The manufacturing method according to claim 10 or 11, further comprising a reduction step of exposing the solder particles to a reducing atmosphere before the placing step.

13. The manufacturing method according to claim 10, further comprising a reduction step of exposing the solder particles to a reducing atmosphere after the placing step and before the heating step.

14. The manufacturing method according to any one of claims 10 to 13, wherein in the heating step, the solder particles are heated to a temperature equal to or higher than the melting point of the solder particles in a reducing atmosphere.

15. The manufacturing method according to any one of claims 10 to 14, further comprising a removing step of removing the solder bump forming member from the substrate after the heating step.

16. The method of claim 15 , further comprising, after the removing step, a cleaning step of removing the solder particles not bonded to the electrodes.

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