TW202236440A - Method of manufacturing member having solder bump, member having solder bump, and member for forming solder bump - Google Patents

Abstract

A method of manufacturing a member having a solder bump, comprising: a preparation step for preparing a base body with a plurality of recessed portions having roughness on a bottom surface; a disposition step for disposing solder particles in the recessed portions; and a pressing step for pressing the base body and a substrate having an electrode in a state in which the solder particles and the electrode face each other, bringing the solder particles and the electrode into contact with each other, and forming, on the electrode, a solder bump having a recess at least in part of a surface.

Description

Method for manufacturing component with solder bump, component with solder bump, and component for forming solder bump

The present invention relates to a method of manufacturing a member with solder bumps, a member with solder bumps, and a member for forming solder bumps.

There is known a mounting method of a semiconductor chip, which is characterized in that, when the semiconductor chip is flip-chip mounted on the circuit board, the flux is transferred to the solder bumps formed on the semiconductor chip and the circuit board. Steps of the next surface and its vicinity; and a step of flip-chip connecting the semiconductor chip with the flux transferred to the circuit board (for example, Patent Document 1).

[Patent Document 1] Japanese Patent Laid-Open No. 1995-078847

Generally, the solder bump surface has a smooth curved surface. Therefore, when the technique of Patent Document 1 is used, the flux may be pushed away from the surface of the solder bump when the solder bump is pressed against the electrode on the circuit board. If a sufficient amount of flux is not secured at the time of bonding, it may be difficult for the solder to wet and spread appropriately, and there may be a possibility that a site where the connection between the electrodes cannot be accurately performed may occur.

This invention was made in view of the said situation, and it aims at providing the manufacturing method of the member with a solder bump which can realize the connection between electrodes more favorable. Another object of the present invention is to provide a member with solder bumps and a member for forming solder bumps.

One aspect of the present invention relates to a method of manufacturing a component with solder bumps, which includes: a preparation step of preparing a substrate having a plurality of concave portions having concavo-convex portions on the bottom surface; an arranging step of arranging solder particles in the concave portions; and pressing In the step of pressing the base and the substrate with the electrodes in a state where the solder particles are facing the electrodes, the solder particles are brought into contact with the electrodes, thereby forming a solder bump having depressions on at least a part of the surface of the electrodes.

Usually, when performing bonding by solder bumps, a liquid flux is applied to a wiring board having metal electrodes such as Au and Cu, and a solder bump is pressed against it to perform bonding. From the viewpoints of shortening steps, reducing raw material costs, and suppressing corrosion of metal electrodes, it is better to use less flux for coating. On the other hand, when the amount of flux is small, the flux is pushed away from the surface of the solder bump, or the flux flows at the bonding temperature, so that the amount of flux required to bond the solder bump to the electrode cannot be ensured. Yu. Therefore, the inventors conducted studies to capture more flux on the solder bump itself while suppressing the amount of flux to be used, and completed the present invention described above. In the present invention, by making a solder bump forming member using a substrate having unevenness on the bottom surface and pressing it against an electrode to form a solder bump, the unevenness on the bottom surface of the substrate is reflected on the surface of the solder bump, enabling the solder bump to be formed on the electrode. At least a portion of the surface is formed with recessed solder bumps. In the member with the solder bump obtained in this way, the depressions on the surface of the solder bump catch flux during connection between electrodes, and the connection between electrodes can be performed more favorably. Thereby, even with a trace amount of flux, it is possible to produce a connection structure capable of achieving both excellent insulation reliability and conduction reliability.

In the pressing step in one aspect of the method of manufacturing a member with solder bumps, the solder particles may be heated.

One aspect of the method of manufacturing a member with solder bumps may further include a reducing step of exposing solder particles to a reducing environment before the disposing step.

One aspect of the method of manufacturing a member with solder bumps may further include a reducing step of exposing solder particles to a reducing environment after the disposing step and before the pressing step.

In the pressing step in one aspect of the method of manufacturing a member with solder bumps, the solder particles may be heated in a reducing environment.

One aspect of the method of manufacturing a member with solder bumps may further include a removal step of removing the base from the substrate after the pressing step.

One aspect of the method of manufacturing a member with a solder bump may further include a cleaning step of removing solder particles not bonded to the electrodes after the removing step.

One aspect of the present invention relates to a component with a solder bump, which includes: a substrate having an electrode; and a solder bump on the electrode, wherein a depression is formed on at least a part of the surface of the solder bump.

In one aspect of the component with solder bumps, the recessed depth of the solder bumps may be less than 25% of the height of the solder bumps.

In one aspect of the component with solder bumps, adjacent solder bumps may be independent of each other.

In an aspect of the component with solder bumps, the height of the solder bumps may be smaller than the diameter in the plane direction of the solder bumps.

One aspect of the present invention relates to a member for forming solder bumps, which includes: a substrate having a plurality of concave portions having concavo-convex portions on a bottom surface; and solder particles in the concave portions.

In one aspect of the member for forming solder bumps, the level difference between the concave and convex portions may be 20% or less of the average particle diameter of the solder particles.

In one aspect of the member for forming solder bumps, the average particle diameter of the solder particles may be 1 to 35 μm, and the C.V. value may be 20% or less. [Invention effect]

According to the present invention, it is possible to provide a method of manufacturing a member with solder bumps capable of achieving better connection between electrodes. Moreover, according to this invention, the member with a solder bump obtained by this manufacturing method, and the member for solder bump formation for obtaining this member with a solder bump can be provided.

Hereinafter, this embodiment will be described. This embodiment is not limited to the following aspects. In addition, unless otherwise specified, materials exemplified below may be used alone or in combination of two or more. When a plurality of substances corresponding to each component exist in the composition, unless otherwise specified, the content of each component in the composition means the total amount of the plurality of substances present in the composition. The numerical range indicated by "~" means the range including the numerical values before and after "~" as the minimum value and the maximum value, respectively. In the numerical ranges described step by step in this specification, the upper limit or lower limit of the numerical range of a certain step may be replaced with the upper limit or lower limit of the numerical range of other steps. In the numerical range described in this specification, the upper limit or the lower limit of the numerical range may be replaced with the value shown in an Example.

<Solder bump forming members> FIG. 1 is a cross-sectional view schematically showing a member for forming solder bumps according to an embodiment. The member 10 for forming a solder bump includes a base 60 including a plurality of recesses having concavities and convexities on the bottom surface, and solder particles 1 in recesses 62 . The concave portion having unevenness on the bottom surface can also be said to have a convex concave portion on the bottom surface. In FIG. 1, the top of the protrusion is schematically curved, and the number of protrusions is uniform in each concave portion, but as long as the protrusion forms a depression on the surface of the solder bump, the top of the protrusion can also be sharper, and the number of protrusions can also be adjusted. Can vary between recesses. In a predetermined longitudinal section of the solder bump forming member 10 , one solder particle 1 is arranged in a horizontal direction (left-right direction in FIG. 1 ) in a state separated from one adjacent solder particle 1 . The solder particle 1 may be in contact with the side surface and/or the bottom surface of the concave portion 62 . The member for forming solder bumps may be in the form of a film (thin film for forming solder bumps), a sheet (sheet for forming solder bumps), or a substrate (substrate for forming solder bumps).

In the member 10 for solder bump formation, a part of the solder particle 1 may protrude from a recessed part, and may not protrude.

When a part of the solder particle 1 protrudes from the recess, 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 base 60 ). In a cross-sectional view perpendicular to the main surface of the solder bump forming member 10, when the depth of the concave portion 62 is H1 and the height from the surface of the base to the top of the solder particle ₁ is _H2 , it may be H ₁ <(H ₁ +H ₂ ), that is, 0<H ₂ . The height H ₂ of the solder particle 1 refers to the height from the surface of the substrate 60 to the apex of the solder particle 1 in a cross-sectional view. The depth H1 _of the concave portion 62 is measured based on the average height of the protrusions existing on the bottom surface. In FIG. ₁ , the protrusion height is schematically depicted as being constant, so H1 is the depth from the apex of the protrusion to the surface of the substrate. However, the protrusion height does not need to be constant (uniform unevenness may not be formed on the bottom surface of the concave portion), so when the protrusion height varies, measure H ₁ based on the average protrusion height as described above. The degree of protrusion of the solder particles 1 is not particularly limited, but the upper limit of the ratio of H ₂ to H ₁ (H ₂ /H ₁ ) may be set to 2.00 from the viewpoint of suppressing the falling off of the solder particles 1 .

The depth H ₁ of the concave portion 62 and the height H ₂ from the base surface to the top of the solder particle 1 can be measured with a laser microscope.

(solder particles) The average particle diameter of the solder particles 1 may be 1 to 35 μm. The average particle diameter of the solder particles 1 may be 30 μm or less, 25 μm or less, 20 μm or less, or 15 μm or less. Moreover, the average particle diameter of the solder particle 1 may be 2 micrometers or more, 3 micrometers or more, or 5 micrometers or more.

The average particle diameter of the solder particle 1 can be measured using various methods matching the size. For example, methods such as a dynamic light scattering method, a laser diffraction method, a centrifugal sedimentation method, an electric detection band method, and a resonance mass measurement method can be used. Furthermore, a method of measuring particle size from an image obtained by an optical microscope, an electron microscope, or the like can be utilized. Specific devices include a flow-type particle image analyzer, MICROTRAC, Coulter counter, and the like. The average particle diameter of the solder particle 1 can be set as the projected area circle equivalent diameter (diameter of a circle having an area equal to the projected area of the particle) when the solder particle 1 is viewed from a direction perpendicular to the main surface of the solder bump forming member 10 ).

The height difference (height of the protrusions) between the concave and convex portions of the unevenness on the bottom surface may be 20% or less of the average particle diameter of the solder particles 1 . From the viewpoint of maintaining the shape of the solder bump, the height difference between the concave and convex portions may be 20% or less, 15% or less, or 10% or less of the average particle diameter of the solder particle 1 . The lower limit of the height difference between the concave and convex portions of the concavo-convex portion can be, for example, 2% or more of the average particle diameter of the solder particles 1 . From this point of view, for example, when the solder particle size is 4 μm, the height difference between the concave and convex portions may be 0.8 μm or less, 0.6 μm or less, or 0.4 μm or less. The lower limit of the height difference between the concave and convex portions can be, for example, 0.08 μm or more.

The height difference (height of protrusions) between the concave and convex portions of the bottom surface can be measured with a laser microscope. The height difference (height of protrusions) between the concave and convex portions on the bottom surface was calculated as the average value of the difference in height (height of protrusions) existing on the bottom surface. In the present specification, the height difference (height of protrusion) between the concave and convex portions of the unevenness formed on the bottom surface of the concave portion of the solder bump forming member 10 is calculated as follows. About 100 recessed parts of the member 10 for arbitrary solder bump formations, the measurement of the protrusion height was performed by observation using the laser microscope, and the protrusion height of each recessed part was computed. Furthermore, the average value of the protrusion heights of the 100 recesses was calculated, and this was taken as the height difference (height of protrusion) between the concave and convex recesses and protrusions on the bottom surface of the recess of the solder bump forming member 10 .

The C.V. value of the solder particles 1 may be 20% or less. The C.V. value of the solder particles 1 may be 20% or less, 10% or less, or 7% or less from the viewpoint of realizing more excellent electrical conductivity reliability and insulation reliability. In addition, the lower limit of the C.V. value of the solder particles 1 is not particularly limited. For example, it may be 1% or more, and may be 2% or more.

The C.V. value of the solder particle 1 was calculated by multiplying the value obtained by dividing the standard deviation of the particle diameter measured by the aforementioned method by the average particle diameter by 100.

The solder particle 1 may contain tin or a tin alloy. As the tin alloy, for example, In-Sn alloy, In-Sn-Ag alloy, Sn-Au alloy, Sn-Bi alloy, Sn-Bi-Ag alloy, Sn-Ag-Cu alloy, Sn-Cu alloy, etc. can be used. Specific examples of such tin alloys include the following. ・In-Sn (In52% by mass, Bi48% by mass, melting point 118°C) ・In-Sn-Ag (In20% by mass, Sn77.2% by mass, Ag2.8% by mass, melting point 175°C) ・Sn-Bi (Sn43 mass%, Bi57 mass%, melting point 138°C) ・Sn-Bi-Ag (Sn42 mass%, Bi57 mass%, Ag1 mass%, melting point 139°C) ・Sn-Ag-Cu (Sn96.5 mass%, Ag3 mass%, Cu0.5 mass%, melting point 217°C) ・Sn-Cu (Sn99.3% by mass, Cu0.7% by mass, melting point 227°C) ・Sn-Au (Sn21.0 mass%, Au79.0 mass%, melting point 278°C)

The solder particles may also contain indium or an indium alloy. As an indium alloy, an In-Bi alloy, an In-Ag alloy, etc. can be used, for example. Specific examples of such indium alloys include the following. ・In-Bi (In66.3% by mass, Bi33.7% by mass, melting point 72°C) ・In-Bi (In33.0% by mass, Bi67.0% by mass, melting point 109°C) ・In-Ag (In97.0% by mass, Ag3.0% by mass, melting point 145°C)

The above-mentioned tin alloy or indium alloy can be selected according to the use of the solder particle 1 (temperature at the time of connection), and the like. For example, when solder particles 1 are used for welding at a low temperature, an In-Sn alloy or a Sn-Bi alloy may be used. In this case, welding can be performed at a temperature of 150° C. or lower. When a material with a high melting point such as Sn-Ag-Cu alloy or Sn-Cu alloy is used, high reliability can be maintained even after being placed at a high temperature.

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 viewpoint. That is, when the solder particle 1 contains Ag or Cu, the melting point of the solder particle 1 can be lowered to about 220° C., and the bonding strength with the electrode is further improved, so better conduction reliability can be easily obtained.

The Cu content rate of the solder particle 1 is 0.05-10 mass %, for example, and may be 0.1-5 mass % or 0.2-3 mass %. When the Cu content rate is 0.05 mass % or more, it becomes easy to achieve better solder connection reliability. Moreover, if the Cu content rate is 10 mass % or less, it will become easy to become the solder particle 1 with a low melting point and excellent wettability, and as a result, the connection reliability of the joint part by the solder particle 1 will become favorable easily.

The Ag content rate of the solder particle 1 is 0.05-10 mass %, for example, and may be 0.1-5 mass % or 0.2-3 mass %. If the Ag content rate is 0.05% by mass or more, better solder connection reliability can be easily achieved. Moreover, if the Ag content rate is 10 mass % or less, it will become easy to become the solder particle 1 with a low melting point and excellent wettability, and as a result, the connection reliability of the junction part by the solder particle 1 will become favorable easily.

(substrate) As the material constituting the base body 60 , inorganic materials such as silicon, metals such as various ceramics, glass, and stainless steel, and organic materials such as various resins can be used. Among them, the substrate 60 may be a heat-resistant material that does not deteriorate at the melting temperature of solder fine particles. In addition, the base body 60 may be made of a heat-resistant material that does not deform at a temperature at which solder particles are melted. In addition, the base body 60 may be made of a material that does not change by alloying or reacting with the material constituting the solder fine particles. The concave portion 62 of the base body 60 can be formed by known methods such as cutting, photolithography, and imprinting. In particular, if the imprint method is used, the concave portion 62 of an accurate size can be formed in a short process.

The surface of the base body 60 may have a coating layer. From the viewpoint of expanding the selectivity of materials that can be used for the base body 60, the coating layer may be made of a material that does not easily alloy with or does not alloy with the material constituting the solder particles, or may have a material that does not deteriorate at the melting temperature of the solder particles. Heat-resistant material. As the coating layer, an inorganic substance or an organic substance can be used. As the coating layer, inorganic substances having a firm oxide layer on the surface of aluminum, chromium, etc., oxides such as titanium oxide, nitrides such as boron nitride, carbon-based materials such as diamond-like carbon (DLC), diamond, graphite, etc., fluorine Resin, high heat-resistant resin such as polyimide, etc. The covering layer can have the function of adjusting the wettability with solder. By providing the coating layer on the surface of the base body 60, the wettability with solder can be appropriately adjusted according to the purpose of use.

As a method of forming the covering layer, lamination, solution immersion, coating, painting, impregnation, sputtering, plating, etc. can be utilized.

From the viewpoint of easily setting the conditions of the transfer step, the material of the substrate 60 may be a material having physical properties close to or identical to those of the electrodes to be transferred with solder particles and the substrate on which the electrodes are formed. For example, when the coefficient of thermal expansion (CTE) is close to or the same material, it is difficult to generate a positional shift at the time of transfer of a solder particle.

Alignment marks may be provided on the substrate 60 . Alignment marks may also be provided on the side of the substrate with the electrodes. Alignment marks are read by the camera. When the solder particles are transferred onto the electrodes, the alignment marks on the substrate 60 and the alignment marks on the substrate having the electrodes are read by a camera mounted on a device capable of position alignment, so that the position of the solder particles can be accurately grasped. The position of the recess 62 and the position of the electrode to which the solder particles are to be transferred. By providing the alignment marks of the substrate 60 and the substrate having the electrodes, it is possible to transfer the solder particles onto the electrodes with high positional accuracy.

It is only necessary to have at least one alignment mark on the base body 60 . When there are two or more alignment marks, the positional accuracy becomes high.

A specific configuration of the base body 60 will be described below.

(organic material single layer) The base body 60 may consist of an organic material. As the organic material, a polymer material may be used, and a thermoplastic material, a thermosetting material, a photocurable material, or the like can be used. By using an organic material, the range of selection of physical properties is expanded, so it is easy to form the substrate 60 suitable for the purpose. For example, if it is an organic material, it is easy to bend or stretch the base 60 (including the concave portion 62 ). As long as it is an organic material, various methods can be utilized also for forming the recessed part 62. As a method for forming the concave portion 62, embossing, photolithography, cutting processing, laser processing, or the like can be used. According to the imprinting 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 a mold and pressing it against the base 60 made of an organic material, the concave portion 62 having a desired pattern can be formed. When a photocurable resin is used to form the concave portion 62 , the substrate 60 having the concave portion 62 can be formed by applying the photocurable resin to a mold, exposing the mold, and then peeling off the mold. In addition, in the case of cutting, the concave portion 62 can be formed using a drill or the like.

(organic material multilayer) The matrix can consist of a plurality of organic materials. The substrate may have a plurality of layers, and the plurality of layers may each be composed of a different organic material. As the organic material, a polymer material may be used, and a thermoplastic material, a thermosetting material, a photocurable material, or the like can be used. The substrate may have two layers made of an organic material, and the organic material layer on one side may have a concave portion formed therein. By forming multiple layers, it is possible to select a material for each layer according to its function. For example, among the materials of the concave portion in contact with solder, a material with appropriate wettability with solder can be selected. For example, Fig. 2 is a cross-sectional view schematically showing an example of a substrate. The base body 600 includes a base layer 601 and a recess layer 602 . The base layer 601 is a layer that supports the concave portion layer 602 , and the concave portion layer 602 is a layer in which the concave portion 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 workability of the recesses 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 concave portion 62 by a stamper can be used for the concave portion layer 602 . For example, by sandwiching a thermosetting resin between polyethylene terephthalate and an imprint mold and applying heat and pressure, the substrate 600 (including the concave portion 62 ) excellent in flatness can be obtained. In addition, when forming the concave portion 62 using a photocurable material, a material with high light transmittance can be used for the base layer 601 . As a material with high translucency, polyethylene terephthalate, transparent (colorless type) polyimide, polyamide, etc. are mentioned, for example. When a photocurable material is used to form the concave portion 62, for example, an appropriate amount of photocurable material is coated on the surface of the imprint mold, a polyethylene terephthalate film is placed thereon, and the polyethylene terephthalate The ester side was irradiated with ultraviolet light while being pressed with a roller. Then, after the photocurable material was cured, the stamper was peeled off to obtain a substrate 600 having a layer of polyethylene terephthalate and a layer of photocurable material and in which the concave portion 62 was formed of the photocurable material. The material composition of the inner wall and the bottom surface of the recess 62 can be changed. For example, the inner wall and the bottom surface of the concave portion 62 may be made of the same resin material. In addition, the inner wall and the bottom surface of the concave portion 62 may be made of different resin materials (for example, a thermosetting material and a thermoplastic material).

As the organic material, a photosensitive material can be used. As a photosensitive material, a positive photosensitive material and a negative photosensitive material are mentioned. For example, the concave portion 62 can be formed by forming a photosensitive material with a uniform thickness on the surface of a thermoplastic polyethylene terephthalate film, exposing and developing (photolithography). The method of using exposure and development is widely used in the manufacture of semiconductors, wiring boards, etc., and is a highly versatile method. As an exposure method, besides exposure using a mask, a direct drawing method such as direct laser exposure can also be used.

By making the material of the base layer 601 thicker than the thickness of the material forming the concave portion layer 602 , the physical properties of the base 600 as a whole can be dominated by the properties of the material of the base layer 601 . Thereby, even if there is a weakness in the properties of the material forming the concave portion layer 602 , the weakness can be compensated for by the material of the base layer 601 . For example, even if the material of the concave portion layer 602 is a material that is easily heat-shrinkable, by selecting a material that is not easily heat-shrinkable among the materials of the base layer 601, and making the thickness of the base layer 601 thicker than the thickness of the material forming the concave portion layer 602, it is possible to Suppresses deformation during heating.

Organic materials 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 low component elution at the melting temperature of solder particles, or a resin material excellent in heat resistance or dimensional stability and solder The wettability of appropriate material combinations etc.

As above, the substrate may be the substrate 600 composed of the base layer 601 and the recess layer 602 . For example, by making the concave portion layer 602 a photosensitive material, the concave portion 62 can be formed by photolithography. By using light or a thermosetting material, a thermoplastic material, or the like in the concave portion layer 602, the concave portion 62 can be produced by imprinting. It is also possible to adjust the properties of the entire substrate by changing the thickness of the base layer 601 , so it is possible to manufacture a substrate having desired properties.

(inorganic material single layer (opaque)) The base body 60 can also be made of inorganic materials. From the viewpoint of making it easier to control the elution of components and the generation of foreign substances, for example, silicon (silicon wafer), stainless steel, aluminum, etc. can be used as inorganic materials. When these materials are used in semiconductor mounting procedures and the like, it is easy to take pollution countermeasures, and it is easy to realize high yield and stable production. For example, when the solder particles formed in the concave portion 62 are transferred to the electrodes on the silicon wafer, if the base body 60 is made of a silicon wafer, the base body and the substrate use materials with close or the same CTE. Thereby, misalignment, warping, and the like are less likely to occur, and it is possible to transfer to an accurate position. As a method for forming the concave portion 62 , processing by laser, cutting, etc., dry etching or wet etching, electron beam drawing (for example, FIB processing), and the like can be used. Dry etching is widely used in the manufacture of semiconductors, MEMS, etc., and can process inorganic materials with high precision from micron to nanometer levels.

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

An advantage of using inorganic materials is that they are superior in dimensional stability compared to organic materials. When the solder particles in the concave portion 62 are transferred onto the electrodes, the transfer can be performed with high positional accuracy. For example, when transferring solder particles to a plurality of electrodes with a micron-order size and a pitch, if an inorganic material excellent in dimensional stability is used, the solder particles can be transferred to the same position on any electrode.

(organic-inorganic composite materials) The substrate can also be composed of multiple materials. The base body may have a plurality of layers, and the plurality of layers may each consist of different materials. As an organic-inorganic composite material, for example, a combination of an inorganic material and an organic material can be used. A combination of an inorganic material and an organic material can easily achieve both dimensional stability and workability of the recessed portion 62 . Examples of substrates having a combination of inorganic materials and organic materials include base layers 601 made of inorganic materials such as silicon, various ceramics, glass, and stainless steel, and recessed layer 602 made of organic materials. Such a substrate can be obtained, for example, by forming a film of a photosensitive material on the surface of a silicon wafer and forming recesses by exposure and development. The inner wall and bottom surface of the concave portion 62 may be made of photosensitive material, or the inner wall of the concave portion 62 may be made of photosensitive material and the bottom surface of the concave portion 62 may be made of a silicon wafer. The configuration of the recessed portion 62 can be appropriately selected according to the purpose of wettability with solder particles in the recessed portion 62, ease of transfer to electrodes, and the like. When the inner wall and bottom surface of the concave portion 62 are made of photosensitive material, the following method can be used: by forming a film of photosensitive material on the surface of the silicon wafer and curing it, a layer of photosensitive material is provided on the surface of the silicon wafer, Then, a film of a photosensitive material is formed again on the surface of the layer, and exposure/development is performed to form the concave portion 62 . In this case, the composition of the photosensitive material on the surface side of the silicon wafer and the photosensitive material further provided on the outermost layer may be different. The photosensitive material can be appropriately selected in consideration of wettability, contamination, and the like of solder particles. When the solder particles formed in the concave portion 62 are transferred onto the electrodes, the surface of the outermost photosensitive material layer may be in contact with the electrodes or the surface of the substrate having the electrodes. Therefore, it is possible to appropriately select a photosensitive material that does not damage the electrodes and the substrate or contaminate the electrodes and the substrate. The photosensitive material may be a material that prevents contamination caused by elution of uncured components, halogen-based materials, silicone-based materials, and the like. The photosensitive material may be a material with high resistance to a reducing environment, a flux, and the like when transferring solder particles to an electrode. For example, the photosensitive material may be a material resistant to reducing environments such as formic acid, hydrogen, and hydrogen radicals. In addition, the photosensitive material may be a material with high resistance to the temperature at the time of transferring the solder particles to the electrodes. Specifically, the photosensitive material may be a material having resistance to a temperature of 100° C. or higher and 300° C. or lower. The melting point of solder particles differs depending on the constituent materials, so the heat-resistant temperature of the photosensitive material can also be selected according to the solder material used. When using tin-silver-copper solder (for example: SAC305 (melting point 219°C)) which is widely used as lead-free solder in electronic equipment, it can be used with heat resistance above 220°C, especially in the reflow process Materials with heat resistance above 260°C. When tin-bismuth solder (for example: SnBi58 (melting point 139°C)) is used, materials with heat resistance above 140°C can be used, and if it is a material with heat resistance above 160°C, it is industrially applicable sexual expansion. When indium solder (melting point: 159° C.) is used, a material having heat resistance of 170° C. or higher can be used. When indium-tin solder (for example: melting point 120° C.) is used, a material having heat resistance of 130° C. or higher can be used.

As another substrate, a substrate having a concave portion 62 formed of a thermosetting or thermoplastic resin on a stainless steel plate may be mentioned. This substrate can be obtained by sandwiching a thermosetting material (resin) between a stainless steel plate and a stamper, pressing and heating it, and then peeling off the stamper. As another substrate, a substrate having a concave portion 62 formed of a photocurable material on a glass plate may be mentioned. This substrate can be obtained by applying a photocurable material on a glass plate, exposing while pressing the stamper to cure the photocurable material, and peeling off the stamper. When the concave portion 62 is formed using a stamper, the material configuration of the inner wall and the bottom surface of the concave portion 62 can be changed according to the press conditions. For example, when the pressurization conditions are relaxed, the inner wall and the bottom surface of the concave portion 62 can be made of the same resin material. On the other hand, when the pressurization condition is strengthened, the inner wall of the concave portion 62 can be made of a resin material, and the bottom surface can be made of an inorganic material.

As the material of the base layer 601, a composite material including glass fibers, fillers, etc., and a resin component can also be used. As a composite material, the copper clad laminated board for wiring boards etc. are mentioned. As described above, the concave portion 62 can be formed by applying a photosensitive material, a thermosetting resin, a photocurable resin, or the like to the surface of the copper-clad laminate. Copper-clad laminates mainly contain a large amount of resin material components, but can be made low CTE by combining with glass fibers, various fillers, etc., so the aforementioned dimensional stability can be ensured. When the electrodes are formed on the copper-clad laminate, by forming the concave portion 62 also on the same copper-clad laminate, the CTEs of the base and the substrate become the same or close to each other. Thereby, at the time of transfer of the solder particle in the recessed part 62, it becomes easy to perform position alignment, and it becomes difficult to generate|occur|produce position misalignment.

A sealing material for packaging can also be used as a material of the recess layer 602 . As the sealing material, any of solid, liquid, and film forms can be used. The concave portion 62 can be formed by laminating a sealing material in a thin layer on glass, a silicon wafer, or the like, and applying pressure and heating using an imprint mold.

The concave-convex shape on the bottom surface of the concave part of the substrate can press a mold (mold: for example, a mold with a plurality of convex parts with concave-convex at the front end) with a desired shape to be pressed against the substrate formed of an organic material as in the imprinting technique. Alternatively, it may be formed by applying a photocurable resin on the above-mentioned mold, exposing it to light, and then peeling off the mold.

The concavo-convex shape can also be formed by post-processing a substrate having a flat bottom surface of the concave portion. For example, a concave-convex shape can be formed on the bottom surface of the concave portion by wet etching, dry etching, or the like. In addition, the concavo-convex shape can be formed on the bottom surface of the concave portion by using a sandblasting method in which an abrasive containing hard fine particles is sprayed at high pressure.

In the concave portion, a concavo-convex shape may be formed other than the bottom surface. The concave-convex shape other than the bottom surface may be of such an extent that the shape of the concave portion can be maintained without hindering the formation of bumps on the electrode.

<Components with solder bumps> The member with the solder bump includes a substrate having an electrode and a solder bump on the electrode, and a depression is formed on at least a part of the surface of the solder bump. The member with the solder bump may have a depression on at least the top of the surface of the solder bump to easily ensure the amount of flux required to bond the solder bump to the electrode. The member with solder bumps can be said to be an electrode substrate with solder bumps.

Specific examples of metal electrodes of members with solder bumps include copper, copper/nickel, copper/nickel/gold, copper/nickel/palladium, copper/nickel/palladium/gold, copper/nickel/gold, Copper/palladium, copper/palladium/gold, copper/tin, copper/silver, indium tin oxide and other electrodes. Electrodes can be formed by electroless or electrolytic plating or sputtering or etching of metal foils.

The depth of the depression on the surface of the solder bump may be 25% or less of the height of the solder bump. From the viewpoint of maintaining the shape of the solder bump, the depth of the depression on the surface of the solder bump may be 25% or less, 15% or less, or 10% or less of the height of the solder bump. The lower limit of the depth of the depression on the surface of the solder bump can be, for example, 2% or more of the height of the solder bump. From this point of view, for example, the recess depth of a solder bump having a bump height of 3.6 μm may be 0.9 μm or less, 0.54 μm or less, or 0.36 μm or less. The lower limit of the dent depth on the surface of the solder bump can be, for example, 0.07 μm or more. The solder bump height is the height from the surface of the electrode to the top of the solder bump when the solder bump does not have a concave (spherical shape).

The depth of the depression on the surface of the solder bump and the height of the solder bump can be measured using a laser microscope.

Adjacent solder bumps formed on the solder bump-attached member may be independent of each other.

From the standpoint of connectivity when using components with solder bumps to obtain connected structures, the pitch of the bumps may be the same as the pitch of the recesses of the substrate, and if the solder bumps are independent of each other, the pitch of the bumps may be the same as the pitch of the recesses of the substrate different.

Part of the solder bump formed on the electrode can be joined to the electrode (metal electrode). Depending on the combination of materials, the electrode may have an alloy layer on its surface (solder bump-electrode interface).

A diameter of the alloy layer may be larger than a diameter of a plane direction of the solder bump. If the solder bumps are independent, the alloy layers formed under the solder bumps can be in contact with each other.

In the solder bump-attached member, the height of the solder bump may be smaller than the diameter of the solder bump in the plane direction (electrode plane direction). The diameter in the plane direction of the solder bump means the maximum diameter (maximum width) of the solder bump in the plane direction. The height of the solder bump is the height from the electrode surface to the top of the solder bump. In this way, since the solder bump is flat, the contact area between the electrode on the opposing member and the solder bump increases when used for mounting, and more stable connection can be performed.

<Manufacturing method of components with solder bumps> A method for manufacturing a component with solder bumps includes: a preparation step of preparing a substrate having a plurality of recesses having concavities and convexities on the bottom surface; an arranging step of arranging solder particles in the recesses; and a pressing step of placing the substrate and the substrate with electrodes on the substrate. The solder particles are pressed in a state where the solder particles are opposed to the electrodes to bring the solder particles into contact with the electrodes, thereby forming a solder bump having a recess in at least a part of the surface on the electrodes.

Through the preparation step and the arrangement step, a member for solder bump formation can be obtained. The method of manufacturing a member for forming solder bumps can be said to include: a preparation step of preparing a substrate having a plurality of recesses having concavities and convexities on the bottom surface; and an arranging step of arranging solder particles in the recesses.

A method of manufacturing the solder bump forming member 10 will be described with reference to FIGS. 3 to 6 . Solder particles can be arranged in the recesses by melting the solder particles in the recesses of the prepared substrate in the procedure described below.

The matrix 60 and the solder particles are prepared for receiving the solder particles. 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 base body 60 shown in FIG. 3( a ) has a plurality of recesses 62 . The plurality of recesses 62 may be arranged sequentially in a predetermined pattern. It is only necessary to set the positions, number, and the like of the plurality of recesses 62 according to the shape, size, pattern, and the like of electrodes to be connected.

The distance L between adjacent recesses is not particularly limited, and may be 0.1 times or more, or 0.2 times or more, the average particle diameter of the solder particles to be accommodated. The distance between the recesses refers to the distance from the edge of the opening of the recess to the edge, not the distance between the centers of the recesses.

The concave portion 62 of the base body 60 may be formed in a tapered shape in which the opening area increases from the bottom surface 62 a side of the concave portion 62 toward the surface 60 a side of the base body 60 . That is, as shown in Figure 3 (a) and Figure 3 (b), the width of the bottom surface 62a of the recess 62 (the width a in Figure 3 (a) and Figure 3 (b)) can be larger than the surface 60a of the recess 62 The width of the opening (width b in Fig. 3(a) and Fig. 3(b)) is narrow. The dimensions (width a, width b, volume, taper angle, depth, etc.) of the concave portion 62 may be set according to the target solder particle size.

The shape of the concave portion 62 of the base body 60 can be freely designed by lithography, machining, embossing techniques, and the like. The size of the solder particle 1 depends on the amount of the solder fine particles 111 accommodated in the concave portion 62 , so the size of the solder particle 1 can be freely designed according to the design of the concave portion 62 .

The shape of the recessed part 62 may be a shape other than the shape shown in FIG.3(a) and FIG.3(b). For example, the shape of the opening on the surface 60 a of the recess 62 may be oval, triangular, quadrilateral, polygonal, etc. other than circular as shown in FIG. 3( a ).

The shape of the concave portion 62 in a cross section perpendicular to the surface 60a may be, for example, the shape shown in FIG. 4 . 4( a ) to 4 ( d ) are cross-sectional views schematically showing examples of the cross-sectional shape of the concave portion of the base body. In any of the cross-sectional shapes shown in FIGS. 4( a ) to 4 ( d ), the width (width b) of the opening on the surface 60 a of the concave portion 62 becomes the maximum width in the cross-sectional shape. Thereby, it becomes easy to take out the solder particle formed in the recessed part 62, and workability improves. In addition, since the width (width b) of the opening is the maximum width in the cross-sectional shape, when the solder particles 1 are transferred to the electrode, the solder particles 1 are easily detached from the recesses 62 , and an improvement in the transfer rate can be expected. In addition, by appropriately adjusting the width (width b) of the above-mentioned opening, it is difficult to cause positional deviation when the solder particles 1 are transferred to the electrode, and it is easy to form a solder bump at an accurate position.

The solder particles only need to contain particles having a particle diameter smaller than the width (width b) of the opening on the surface 60 a of the recess 62 , and more particles having a particle diameter smaller than the width b may be included. For example, the D10 particle size of the particle size distribution of the solder particles may be smaller than the width b, or the D30 particle size of the particle size distribution may be smaller than the width b, or the D50 particle size of the particle size distribution may be smaller than the width b.

The particle size distribution of solder particles can be measured using various methods matched to the size. For example, methods such as a dynamic light scattering method, a laser diffraction method, a centrifugal sedimentation method, an electric detection band method, and a resonance mass measurement method can be used. Furthermore, a method of measuring particle size from an image obtained by an optical microscope, an electron microscope, or the like can be utilized. Specific devices include a flow-type particle image analyzer, MICROTRAC, Coulter counter, and the like.

The C.V. value of the solder particles is not particularly limited, but may be high from the viewpoint of improving fillability in the recess 62 depending on the combination of large and small particles. For example, the C.V. value of solder particles can exceed 20%, and can also be 25% or more or 30% or more.

The C.V. value of the solder particles was calculated by multiplying 100 the value obtained by dividing the standard deviation of the particle diameters measured by the aforementioned method by the average particle diameter (D50 particle diameter).

However, even solder fine particles with large variation in particle size distribution and deformed shape can be used as a raw material as long as they can be accommodated in the concave portion 62 .

The solder fine particles may contain tin or a tin alloy. As the tin alloy, for example, In-Sn alloy, In-Sn-Ag alloy, Sn-Au alloy, Sn-Bi alloy, Sn-Bi-Ag alloy, Sn-Ag-Cu alloy, Sn-Cu alloy, etc. can be used. Specific examples of such tin alloys include the following. ・In-Sn (In52% by mass, Bi48% by mass, melting point 118°C) ・In-Sn-Ag (In20% by mass, Sn77.2% by mass, Ag2.8% by mass, melting point 175°C) ・Sn-Bi (Sn43 mass%, Bi57 mass%, melting point 138°C) ・Sn-Bi-Ag (Sn42 mass%, Bi57 mass%, Ag1 mass%, melting point 139°C) ・Sn-Ag-Cu (Sn96.5 mass%, Ag3 mass%, Cu0.5 mass%, melting point 217°C) ・Sn-Cu (Sn99.3% by mass, Cu0.7% by mass, melting point 227°C) ・Sn-Au (Sn21.0 mass%, Au79.0 mass%, melting point 278°C)

The solder particles may also contain indium or an indium alloy. As an indium alloy, an In-Bi alloy, an In-Ag alloy, etc. can be used, for example. Specific examples of such indium alloys include the following. ・In-Bi (In66.3% by mass, Bi33.7% by mass, melting point 72°C) ・In-Bi (In33.0% by mass, Bi67.0% by mass, melting point 109°C) ・In-Ag (In97.0% by mass, Ag3.0% by mass, melting point 145°C)

The above-mentioned tin alloy or indium alloy can be selected according to the use of the solder particles (temperature at the time of use) and the like. For example, to obtain solder particles used for welding at low temperature, it is only necessary to use In-Sn alloy or Sn-Bi alloy. In this case, solder particles capable of welding at 150° C. or less can be obtained. When a material with a high melting point such as Sn-Ag-Cu alloy or Sn-Cu alloy is used, it is possible to obtain solder particles that can maintain high reliability even after being left at a high temperature.

The solder 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 viewpoint. That is, by including Ag or Cu in the solder fine particles, the following effects can be exhibited: the melting point of the obtained solder particles can be lowered to about 220° C.; since the solder particles with excellent bonding strength with the electrode can be obtained, a better solder particle can be obtained. conduction reliability.

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 rate is 0.05 mass % or more, the solder particle which can achieve favorable solder connection reliability can be obtained easily. Moreover, if the Cu content rate is 10 mass % or less, the solder particle with a low melting point and excellent wettability can be obtained easily, and as a result, the connection reliability of the electrode with a solder bump becomes favorable more easily.

The Ag content rate 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 rate is 0.05 mass % or more, the solder particle which can achieve favorable solder connection reliability can be obtained easily. Moreover, if the Ag content rate is 10 mass % or less, solder particles with a low melting point and excellent wettability can be easily obtained, and as a result, the connection reliability of electrodes with solder bumps becomes more likely to be good.

The solder particles prepared as described above are accommodated in each of the concave portions 62 of the base body 60 . Here, all of the solder particles may be accommodated in the recess 62 , or a part of the solder particles (for example, solder particles smaller than the width b of the opening of the recess 62 ) may be accommodated in the recess 62 .

FIG. 5 is a cross-sectional view schematically showing a state in which solder fine particles 111 are accommodated in the concave portion 62 of the base body 60 . As shown in FIG. 5 , a plurality of solder fine particles 111 are housed in each of the plurality of recesses 62 .

By adjusting the amount of solder particles 111 accommodated in the concave portion 62, the degree of protrusion of the solder particles 1 can be adjusted. The amount of solder fine particles 111 accommodated in the concave portion 62 may be, for example, 20% or more, 30% or more, 50% or more, or 60% or more of the volume of the concave portion 62 . Thereby, a part of solder particle can be made to protrude from the recessed part 62. As shown in FIG. In addition, variations in the storage amount are suppressed, and solder particles having a smaller particle size distribution can be easily obtained.

In general, a solder material has a property of gathering into balls due to its own surface tension when it becomes molten in an environment above its melting point.

The solder fine particles 111 accommodated in the concave portion 62 are aggregated by a melting process described later, and become solder particles 1 . The height of the obtained solder particle 1 becomes higher than the depth of the recess 62 , and the solder particle 1 protrudes from the recess 62 . Therefore, when the diameter of the solder particle 1 becomes larger than the depth of the recess 62 , the solder particle 1 protrudes from the recess 62 . Since the diameter of the solder particle 1 can be adjusted according to the shape of the concave portion 62 and the amount of the solder particles 111 accommodated in the concave portion 62 , the degree of protrusion from the concave portion 62 can be adjusted accordingly.

When the solder particles 111 are melted by the melting process described later, depending on the material of the recess 62, wetting spread occurs on the bottom surface and the inner wall, and at least a part of the solder particle 1 contacts the bottom surface and/or the inner wall of the recess 62. . Thereby, a flat part may generate|occur|produce in at least a part of the solder particle 1. The size of the flat portion varies depending on the combination of the surface material of the concave portion 62 and the composition of the solder constituting the solder particles 111 . Therefore, the form of the solder particle 1 may be a spherical form, an ellipsoid, a flattened sphere, a form having a flat portion in a part, or the like. Inorganic materials such as glass and silicon or organic materials such as plastics and resins can be used as the substrate 60 . Generally, such materials tend to have low wettability with solder, and the solder particles 1 tend to be roughly spherical. Therefore, it is also possible to approximate the height of the solder particle 1 to the diameter of the solder particle 1 by assuming that the solder particle 1 is a sphere close to a sphere. The diameter of solder particles 1 can be calculated from the total volume of solder particles 111 filled in recesses 62 , so the amount of solder particles 111 required for solder particles 1 to protrude from recesses 62 can be calculated.

The amount of solder particles 111 required for solder particles 1 to protrude from recess 62 can be represented by assuming that all solder particles 111 filled in recesses 62 are melted and fused to become solder particles 1 and that solder particles 1 are spherical.

When the upper diameter (opening width b) of the concave portion 62 is L and the depth of the concave portion 62 is D, the aspect ratio of the concave portion is represented by L/D. At this time, the filling rate of the solder particles 111 in the concave portion 62 may be 66% by volume or more when the aspect ratio is 1, 38% by volume or more when the aspect ratio is 0.75, and 17% by volume when the aspect ratio is 0.5. % or more, when the aspect ratio is 0.25, it may be 5 volume % or more.

In order to suppress variation in the amount of storage, the average particle diameter, grain size, etc. of the solder fine particles 111 can 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 (the aspect ratio is 1), by using the solder particles 111 with an average particle diameter of 1 to 2 μm or less, it is possible to suppress the variation in the filling amount of the concave portion 62, and the obtained Variations in the diameter of the solder particles 1 are also suppressed, and variations in the amount of protrusion (height) from the concave portion 62 are also easily suppressed. If the variation in the protrusion amount (height) from the concave portion 62 is suppressed, when the solder particle 1 is pressed against the electrode, the contact between the solder particle 1 and the electrode is stabilized, and the variation in formation of the solder bump is easily suppressed.

The method of accommodating solder fine particles in the concave portion 62 is not particularly limited. The storage method may be either a dry type or a wet type. For example, by disposing solder particles on the substrate 60 and rubbing the surface 60 a of the substrate 60 with a squeegee, excess solder particles can be removed while sufficient solder particles can be accommodated in the concave portion 62 . When the width b of the opening of the concave portion 62 is larger than the depth of the concave portion 62 , solder particles may protrude from the opening of the concave portion 62 . If a squeegee is used, solder particles protruding from the opening of the recessed portion 62 are removed. As a method of removing excess solder fine particles, methods such as blowing compressed air and wiping the surface 60a of the substrate 60 with a non-woven cloth or a fiber bundle are also mentioned. Compared with squeegee rollers, the physical force of these methods is weak, so it is easy to handle deformable solder particles. Also in these methods, it is possible to leave the solder fine particles protruding from the opening of the recessed part 62 in the recessed part.

Next, the solder particles 111 housed in the concave portion 62 are melted (for example, by heating to 130° C. to 260° C.) to form solder particles 1 partially protruding from the concave portion 62 in the concave portion 62 . The solder fine particles 111 accommodated in the concave portion 62 are fused by melting and spheroidized by surface tension. At this time, in the contact portion with the bottom surface 62 a of the concave portion 62 , the molten solder can form the planar portion 11 on a part of the surface of the solder particle along the bottom surface 62 a. In this way, the solder bump forming member 10 shown in FIG. 1 is obtained.

As a method of melting the solder fine particles 111 accommodated in the concave portion 62, there may be mentioned a method of heating the solder fine particles 111 to a temperature equal to or higher than the melting point of the solder. Due to the influence of the oxide film, the solder fine particles 111 may not melt or wet and spread even if heated at a temperature higher than the melting point, and may not be fused. Therefore, after exposing the solder fine particles 111 to a reducing environment to remove the surface oxide film of the solder fine particles 111, heating to a temperature above the melting point of the solder fine particles 111 can melt, wet and spread, and fuse the solder fine particles 111. Melting of the solder particles 111 may be performed under a reducing environment. By heating the solder particles 111 above the melting point of the solder particles 111 in a reducing environment, the oxide film on the surface of the solder particles 111 is reduced, and the solder particles 111 can be melted, wetted and fused easily and efficiently.

The method of creating a reducing environment is not particularly limited as long as the above-mentioned effect can be obtained. For example, there are methods using hydrogen gas, hydrogen radicals, formic acid gas, and the like. For example, by using a hydrogen reduction furnace, a hydrogen radical reduction furnace, a formic acid reduction furnace, or these conveyor belt furnaces or continuous furnaces, it is possible to melt the solder fine particles 111 in a reducing environment. These devices may be equipped with a heating device in the furnace, a chamber filled with inert gas (nitrogen, argon, etc.), a mechanism for vacuuming the chamber, etc., so that it is easier to control the reducing gas. Moreover, if the chamber can be vacuumed, voids can be removed by reducing the pressure after melting and fusion of the solder fine particles 111 , and solder particles 1 with further excellent connection stability can be obtained.

The profile of reduction of solder particles 111 , melting conditions, temperature, furnace environment adjustment, etc. may be appropriately set in consideration of the melting point, particle size, concave portion size of solder particles 111 , material of substrate 60 , and the like. For example, solder particles can be obtained as follows. The substrate 60 filled with the solder fine particles 111 in the concave portion is inserted into the furnace and vacuumed. A reducing gas is introduced, the furnace is filled with the reducing gas, and the oxide film on the surface of the solder particles 111 is removed. Reducing gases were removed by evacuation. The solder particles are heated to a temperature equal to or higher than the melting point of the solder particles 111 to melt and fuse the solder particles, thereby forming solder particles in the concave portion 62 . After filling the nitrogen gas, the temperature in the furnace was returned to room temperature to obtain solder particles 1 .

Also, for example, solder particles can also be obtained as follows. In the following method, since the reducing force is increased by heating the solder fine particles in a reducing environment, there is an advantage that the surface oxide film of the solder fine particles can be easily removed. The substrate 60 filled with the solder fine particles 111 in the concave portion is inserted into the furnace and vacuumed. The reducing gas is introduced, and the furnace is filled with the reducing gas. The solder fine particles 111 are heated by a heating heater in the furnace to remove the surface oxide film of the solder fine particles 111 . Reducing gases were removed by evacuation. The solder particles are heated to a temperature equal to or higher than the melting point of the solder particles 111 to melt and fuse the solder particles, thereby forming solder particles in the concave portion 62 . After filling the nitrogen gas, the temperature in the furnace was returned to room temperature to obtain solder particles 1 .

Furthermore, for example, solder particles can also be obtained as follows. In the following method, it is only necessary to adjust the rise and fall of the temperature in the furnace only once, so there is an advantage that it can be processed in a short time. The substrate 60 filled with the solder fine particles 111 in the concave portion is inserted into the furnace and vacuumed. The reducing gas is introduced, and the furnace is filled with the reducing gas. The oxide film on the surface of the solder fine particles 111 is reduced and removed by heating to a temperature above the melting point of the solder fine particles 111 with a heating heater in the furnace. At the same time, the solder particles are melted and fused to form solder particles in the concave portion 62 . The voids within the solder particles are further reduced by vacuuming to remove reducing gases. After filling the nitrogen gas, the temperature in the furnace was returned to room temperature to obtain solder particles 1 .

After forming the solder particles in the above-mentioned concave portion 62, a step of removing the incompletely removed surface oxide film may be added by making the inside of the furnace into a reducing environment again. Thereby, it is possible to reduce residues such as solder fine particles remaining without melting, a part of the oxide film remaining without melting, and the like.

When using an atmospheric pressure conveyor belt furnace, the substrate 60 filled with the solder fine particles 111 in the recesses is placed on a conveyance conveyor, and the solder particles 1 can be obtained by passing through a plurality of zones continuously. For example, solder particles can be obtained as follows. The substrate 60 filled with the solder fine particles 111 in the recesses is placed on a conveyor set at a constant speed. This is passed through a region filled with an inert gas such as nitrogen or argon at a temperature lower than the melting point of the solder particles 111 . The oxide film on the surface of the solder fine particles 111 is removed by passing through a region where a reducing gas such as formic acid gas having a temperature lower than the melting point of the solder fine particles 111 exists. Solder fine particles 111 are melted and fused by passing through a region filled with inert gas such as nitrogen or argon at a temperature equal to or higher than the melting point of solder fine particles 111 . Solder particles 1 can be obtained by passing through a region filled with inert gas such as nitrogen and argon.

In addition, solder particles can also be obtained as follows using an atmospheric pressure conveyor furnace. The substrate 60 filled with the solder fine particles 111 in the recesses is placed on a conveyor set at a constant speed. This is passed through a region filled with an inert gas such as nitrogen or argon at a temperature equal to or higher than the melting point of the solder particles 111 . The oxide film on the surface of the solder fine particles 111 is removed by passing through a region 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. At the same time, the solder particles are melted and fused. Solder particles 1 can be obtained by passing through a region filled with inert gas such as nitrogen and argon.

The conveyor belt furnace is capable of processing under atmospheric pressure, so it is also possible to continuously process film-like materials in a roll-to-roll manner. For example, solder fine particles can be melted as follows. A continuous roll of the substrate 60 filled with solder particles 111 in the recesses is produced. A coil unwinder is installed on the entrance side of the conveyor furnace, and a coil coiler is installed on the exit side of the conveyor furnace, and the substrate 60 is conveyed at a constant speed. The solder particles 111 filled in the recesses can be melted by passing through each region in the conveyor furnace.

By the method described above, solder particles 1 of uniform size can be formed regardless of the material and shape of solder particles 111 . For example, indium-based solder can be deposited by plating, but it is difficult to deposit in the form of particles, and it is difficult to handle because it is soft. However, in the above method, indium-based solder particles having a uniform particle diameter can be easily produced by using indium-based solder fine particles as a raw material. In addition, the formed solder particles 1 can be handled in a state accommodated in the concave portion 62 of the base body 60 . Therefore, transportation, storage, and the like can be performed without deforming the solder particles 1 . In addition, the formed solder particle 1 is in the state accommodated in the concave part 62 of the base body 60 . Therefore, the solder particles can be brought into contact with the electrodes without being deformed.

In the above method, the solder particles 111 are melted in the concave portion 62 of the substrate 60 to arrange the solder particles 1 in the concave portion 62, but it is also possible to arrange separately prepared solder particles in the concave portion of the substrate to obtain a member for forming solder bumps, The separately prepared solder particles are, for example, those obtained by taking out and storing the solder particles produced by the above-mentioned method from the concave portion, or those purchased as industrial products and made to have a desired particle size distribution.

As a method of accommodating separately prepared solder particles in the recessed portion of the substrate, for example, the above method of accommodating solder fine particles in the recessed portion can be used.

Next, the process of preparing the member with a solder bump by pressing the member for solder bump formation prepared above against an electrode is described.

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, and driver ICs; and rigid package substrates. Usually, these circuit members have a plurality of circuit electrodes. Other examples of a substrate having a plurality of electrodes on its surface include a flexible tape substrate with metal wiring, a flexible printed wiring board, and a glass substrate on which indium tin oxide (ITO) is vapor-deposited.

Examples of electrodes include copper, copper/nickel, copper/nickel/gold, copper/nickel/palladium, copper/nickel/palladium/gold, copper/nickel/gold, copper/palladium, copper/palladium/gold, copper Electrodes formed by /tin, copper/silver, indium tin oxide, etc. The electrodes can be formed by electroless plating, electrolytic plating, sputtering, etching of metal foil, or the like.

6( a ) and FIG. 6( b ) are cross-sectional views schematically showing an example of a manufacturing process of a member with solder bumps (electrode substrate with solder bumps). The substrate 60 shown in FIG. 6( a ) is in a state in which one solder particle 1 is accommodated in each of the concave portions 62 having concavities and convexities on the bottom surface. On the other hand, the substrate 2 has a plurality of electrodes 3 on the surface. Make the surface of the electrode 3 side of the substrate 2 face the surface of the opening side of the recess 62 of the substrate 60, and press the substrate 60 and the substrate 2 until the solder particles 1 accommodated in the recess 62 of the substrate 60 contact the electrode 3 ( FIG. 6 Arrows A, B in (a). From the standpoint of suitably bonding the solder particles 1 and the electrodes 3, the pressing refers to the pressure between the solder bump forming member 10 and the substrate 2 in the direction of the arrows A and B in FIG. The state of tension. Thereby, the solder bump which has a recess in at least a part of the surface can be formed on an electrode. FIG. 6( b ) is a schematic diagram of a component 20 with solder bumps obtained in this way. The number of solder particles 1 in contact with each electrode 3 is not particularly limited, and may be one particle for one electrode, or a plurality of particles for one electrode. Moreover, you may make the solder particle 1 contact only the specific electrode among several electrodes. Since the force acting between the solder particle 1 and the concave portion 62 (for example, intermolecular force such as van der Waals force) is greater than the gravitational force applied to the solder particle 1, even if the main surface of the substrate 60 is Even downward, the solder particles 1 will not come off but stay in the concave portion 62 . Also, when at least a part of solder particle 1 has a flat surface that contacts the bottom surface and/or the inner wall of recess 62 , solder particle 1 is less likely to fall off from recess 62 .

If alignment marks are provided on the surfaces of the base body and the substrate, respectively, the alignment of both can be easily performed. For example, when the member for forming solder bumps is opposed to the substrate with electrodes, alignment marks are set in advance on the surfaces of the base and the substrate so that the positions of the recesses face the positions of the electrodes. Thereafter, when the member for forming solder bumps is actually opposed to the substrate with electrodes, the alignment marks are used for positional adjustment, whereby solder bumps can be formed on the electrodes with high positional accuracy.

In the pressing step, the base body 60 may be pressed against the substrate 2 previously coated with an adhesive resin material, a flux material, etc., to form solder bumps. In this case, the solder particles 1 are transferred onto the electrodes 3, and a solder bump-attached member in which the solder bumps 1A and the electrodes 3 are not metal-bonded can be obtained. By manufacturing a connection structure using such a solder bump-attached member, inter-electrode joining can be performed more suitably. The solder bumps are melted by heating at the time of manufacturing the bonded structure, and the upper and lower electrodes are joined.

In the pressing step, the solder particles may be heated while bringing the solder particles and the electrodes into contact in a pressurized state from the viewpoint of more preferably bonding the solder particles and the electrodes. From the viewpoint of shortening the production time, in the pressing step, the solder particles may be heated to a temperature equal to or higher than the melting point of the solder particles. When the solder particles are heated to a temperature equal to or higher than the melting point of the solder particles, the solder particles are melted, and bonding to the electrode surface can be performed appropriately in a short time. In addition, when the solder particles are heated to a temperature equal to or higher than the melting point of the solder particles, the fluidity of the solder particles increases, so that the solder particles are more likely to come into contact with the electrode surface, and the bonding reliability with the electrodes is improved. Specifically, for example, when solder particles are collectively joined to a plurality of electrodes, it is possible to reduce unjoined electrodes and improve productivity. In addition, since the bonding reliability between the solder particles and the electrodes is improved, the pressing time can be shortened as a result. Moreover, in the pressing process, you may heat a solder particle to the temperature which does not reach the melting point of a solder particle from a viewpoint of making the connection of a solder particle and an electrode more uniform. If the solder particles are heated to a temperature lower than the melting point of the solder particles, although the solder particles will not melt, mutual diffusion of the metal elements in the solder particles and the metal elements in the electrodes will occur at the contact surface between the solder particles and the electrodes. The two join. Since the interdiffusion occurs slowly by setting the heating temperature below the melting point, the solder composition can be easily maintained even if heated for a long time (for example, 10 minutes or more). Specifically, when solder particles are collectively joined to a plurality of electrodes, even in a situation where unevenness in bonding is likely to occur due to uneven pressure, height variation of the electrode surface, etc., by setting the pressing time for a long time, the uneven pressure can be alleviated. Even solder particles and electrodes can be bonded more reliably.

The solder particles 1 may not be melted or wetted and spread even when heated due to the influence of the oxide film. Therefore, the solder particles 1 can be melted by exposing the solder particles 1 to a reducing environment to remove the oxide film on the surface of the solder particles 1 and then heating the solder particles 1 . In addition, melting of the solder particles 1 can be performed in a reducing environment. By heating the solder particles 1 in a reducing environment, the oxide film on the surface of the solder particle 1 is reduced, and the oxide film on the surface of the electrode is reduced, so that the melting and wet spread of the solder particle 1 can be efficiently performed. That is, the method of manufacturing a component with solder bumps may further include a reducing step of exposing solder particles (and/or electrodes) to a reducing environment before the disposing step, or after the disposing step and before the pressing step. In addition, in the pressing step of the method of manufacturing the member with the solder bump, the solder particles may be heated in a reducing environment. In the pressing step of forming solder bumps on the electrodes, the solder bumps are formed only on the electrodes by bringing the electrodes into close contact with the opening surface of the solder bump forming member (heating it while heating as necessary), and the adjacent electrodes The bridging caused by the solder between them is easily suppressed.

The description of the manufacturing method of the member for solder bump formation can be referred suitably about the detail of reducing environment.

When heating is performed during the pressing step, by cooling the whole after heating, solder bump 1A formed by melting solder particles 1 is fixed on electrode 3 .

After forming the solder bump 1A on the electrode 3, the member 10 for solder bump formation is removed from the board|substrate 2, and the member 20 with a solder bump can be obtained by this. That is, the method of manufacturing the member with solder bumps may further include a removal step of removing the base from the substrate after the pressing step.

On the obtained solder bump-attached member 20 , there may be solder particles 1 detached from the concave portion 62 but not joined to the electrode 3 . Therefore, the method of manufacturing a member with a solder bump may further include a cleaning step for removing solder particles not bonded to the electrodes. As a cleaning method, methods such as blowing compressed air and rubbing the surface of the substrate with a non-woven cloth or fiber bundle are mentioned.

According to the method of manufacturing the member with solder bumps, the member with solder bumps 20 including the substrate 2 , the electrodes 3 , and the solder bumps 1A in this order and having recesses formed on at least a part of the surface of the solder bumps can be obtained.

<Manufacturing method of bonded structure> 7( a ) and FIG. 7( b ) are cross-sectional views schematically showing an example of the manufacturing process of the bonded structure. Referring to FIG. 7( a ) and FIG. 7( b ), the method of manufacturing the bonded structure will be described. First, the member 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. And both are arrange|positioned so that 1 A of solder bumps may oppose the other electrode 5. As shown in FIG. Thereafter, by heating in a state where the solder bump 1A is in contact with the other electrode 5 , the solder bump 1A is melted between the electrode 3 and the other electrode 5 . Then, by cooling the whole, solder layer 1B is formed between electrode 3 and other electrode 5, and the electrodes are electrically connected. At this time, by heating in an atmosphere where oxygen is blocked, oxidation of the solder bump 1A and the electrode 5 can be suppressed. For example, heating in an inert gas atmosphere such as nitrogen can be mentioned, and specifically, a vacuum reflow furnace, a nitrogen reflow furnace, or the like can be used.

In order to melt the solder bump 1A by heating and join the opposing electrode 3 and electrode 5 more suitably, heating can be performed in a reducing environment. In order to set it as a reducing environment, hydrogen gas, hydrogen radicals, formic acid, etc. can be utilized. Specifically, a hydrogen reduction furnace, a hydrogen reflow furnace, a hydrogen radical furnace, a formic acid furnace, a vacuum furnace, a continuous furnace, and a conveyor furnace can be used. By using a reducing environment, 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 is easy to wet and spread on the electrode 5, and the electrode 3 and the electrode 5 can be connected via the solder layer 1B. 5 to achieve a more stable joint.

In order to achieve a stable connection, pressure can be applied. The component 20 with solder bumps shown in FIG. 6( b ) is prepared in advance. Also, another substrate 4 having a plurality of other electrodes 5 on the surface is prepared. And both are arrange|positioned so that 1 A of solder bumps may oppose the other electrode 5. As shown in FIG. Thereafter, pressure is applied along the thickness direction of the laminated body of these members (directions of arrows A and B shown in FIG. 7( a )). The solder bump 1A is melted between the electrode 3 and the other electrode 5 by heating the whole when pressurized. Then, by cooling the whole, solder layer 1B is formed between electrode 3 and other electrode 5, and the electrodes are electrically connected. In this case, in order to suppress the oxidation of the surface of the solder bump 1A, the electrode 5, and the electrode 3, the above steps may be performed under vacuum, under an inert gas atmosphere such as nitrogen, or under a reducing atmosphere. As a method for making a reducing environment, the aforementioned hydrogen gas, hydrogen radicals, formic acid, and the like are mentioned. Specifically, a hydrogen reduction furnace, a hydrogen reflow furnace, a hydrogen radical furnace, a formic acid furnace, a vacuum furnace of these, a continuous furnace, a conveyor furnace, and the like can be used.

A flux material having a reducing effect can be disposed near the solder bump 1A or the electrodes 5 and 3 . First, the member 20 with solder bumps shown in FIG. 6( b ) is prepared in advance. A flux material is placed on the entire surface of the member 20 with solder bumps 20 on which the solder bumps 1A are formed or in the vicinity of the solder bumps 1A and the electrodes 3 including the solder bumps 1A. Also, another substrate 4 having a plurality of other electrodes 5 on the surface is prepared. And both are arrange|positioned so that 1 A of solder bumps may oppose the other electrode 5. As shown in FIG. Thereafter, by heating in a state where the solder bump 1A and the other electrode 5 are in contact, for example, via a flux material, the solder bump 1A is melted between the electrode 3 and the other electrode 5 . Then, by cooling the whole, solder layer 1B is formed between electrode 3 and other electrode 5, and the electrodes are electrically connected. Thereafter, if the flux components are removed by washing, corrosion of the solder layer 1B, the electrodes 3, and the electrodes 5 due to flux residues can be suppressed.

As another method, the solder bump-attached member 20 shown in FIG. 6( b ) is prepared in advance. Also, prepare another substrate 4 having a plurality of other electrodes 5 on the surface, and arrange a flux material on the entire surface of the substrate 4 having the electrodes 5 or near the surface of the electrodes 5 . And both are arrange|positioned so that 1 A of solder bumps may oppose the other electrode 5. As shown in FIG. Thereafter, by heating in a state where the solder bump 1A and the other electrode 5 are in contact, for example, via a flux material, the solder bump 1A is melted between the electrode 3 and the other electrode 5 . Then, by cooling the whole, solder layer 1B is formed between electrode 3 and other electrode 5, and the electrodes are electrically connected.

In any of the above methods, the flux material is captured in the depression on the surface of the solder bump, and the amount of flux required to bond the solder bump to the electrode can be sufficiently secured.

As a heating method for melting the solder bump 1A, for example, a method of heating a heating plate in a reflow furnace under vacuum and transferring it to the solder bump 1A via the substrate 2 and the substrate 4 in contact with the heating plate, A method using radiation such as infrared rays, etc. Moreover, the method of heating the solder bump 1A via the heated gas can be utilized other than the heating method using a hot plate or infrared rays, or in parallel with it. Specifically, the solder bump 1A can be heated by heating an inert gas such as nitrogen, hydrogen, hydrogen radicals, formic acid, or the like. The flux material 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.

As another method, a method using electromagnetic waves such as microwaves can be mentioned. For example, a specific electromagnetic wave that heats the components of the electrode 3 , the electrode 5 , and the solder bump 1A can be applied from the outside. For example, when the substrate 4 and the substrate 2 are resin substrates, if a specific electromagnetic wave is irradiated from the outside of the substrate 4 and the substrate 2, the electromagnetic wave passes through the substrate 4 and the substrate 2, and the electrode 3 and the solder bump 1A or the electrode 5 are heated by the electromagnetic wave. In the case of this method, since it is possible to selectively heat the portion to be joined, there is an advantage that no unnecessary heat history remains. For example, even if the substrate 2 and the substrate 4 are materials with low heat resistance, the solder bump 1A can be melted to reliably join the electrode 3 and the electrode 5 . In addition, since the thermal history does not easily remain in the entire system to be joined, there is an advantage that warping and disassembly after joining can be easily suppressed. When microwaves are used, compared with using a heating plate, infrared rays, heating gas, etc., the solder bump 1A can be melted in a short time, so there is an advantage that the thermal history of the entire system to be joined can be reduced, and the aforementioned Effect. In addition, if microwaves are used, only the electrode 3 to be joined or melted, the solder bump 1A, and the electrode 5 can be locally heated. Therefore, there is no need to heat the entire system, and even if materials with low heat resistance and other electronic components that do not want to be heated are located near the electrodes 3 and 5 , the solder bumps 1A can be melted and bonded.

As another method, a method utilizing ultrasonic waves can be mentioned. For example, if an ultrasonic vibrator is disposed on the side of the substrate 2 opposite to the electrode 3 and ultrasonic waves are applied, the solder bumps 1A are melted by the vibration energy of the ultrasonic waves. Thereby, the electrode 3 and the electrode 5 previously arrange|positioned at the position facing the electrode 3 are joined via the solder layer 1B. Bonding by ultrasonic waves can melt the solder bump 1A in a short time, so there is no need to heat the entire substrate 2 and substrate 4, and even if the substrate 2 and substrate 4 are made of materials with low heat resistance, electrodes 3 and electrodes can be reliably bonded 5.

FIG. 7( b ) is a schematic diagram of the connection structure 30 obtained in this way. That is, FIG. 7( b ) schematically shows a state in which the electrode 3 included in the substrate 2 is connected to the other electrode 5 included in the other substrate 4 via the solder layer 1B formed by welding. In this specification, "welding" refers to a state in which at least a part of the electrode is joined by heat-melted solder (solder bump 1A), and thereafter, the solder is joined to the surface of the electrode through a solidification step. The connection structure 30 can be said to have a first circuit member, a second circuit member, a plurality of electrodes, and a solder layer between a plurality of other electrodes. The first circuit member has a substrate and a plurality of electrodes on its surface. The second circuit component has another substrate and a plurality of other electrodes on the surface thereof. From the perspective of maintaining the strength of the connection structure and cutting off the cause of deterioration (moisture, oxygen, etc.) ), edge bonding (edge bond) and other methods for sealing. For example, the space between the first circuit member and the second circuit member can be filled with an underfill material mainly composed of epoxy resin.

As the application object of the bonded structure, there are connection parts such as semiconductor memories and semiconductor logic chips, connection parts of primary mounting and secondary mounting of semiconductor packages, CMOS image elements, laser elements, LED light emitting elements, etc. Connectors, cameras, sensors, liquid crystal displays, personal computers, mobile phones, smart phones, tablet computers and other devices using them.

The contents of this embodiment are listed below. A method for manufacturing a component with solder bumps, comprising: a preparation step of preparing a substrate with a plurality of recesses having concavities and convexities on the bottom surface; an arranging step of arranging solder particles in the recesses; and a pressing step of placing the substrate and electrodes The substrate is pressed in a state where the solder particles and the electrodes are opposed to bring the solder particles into contact with the electrodes, thereby forming a solder bump having a depression in at least a part of the surface on the electrodes. According to the above manufacturing method, in the pressing step, the solder particles are heated. According to the above-mentioned manufacturing method, a reducing step of exposing the solder particles to a reducing environment is further provided before the disposing step. According to the above-mentioned manufacturing method, a reducing step of exposing the solder particles to a reducing environment is further provided after the disposing step and before the pressing step. According to the above manufacturing method, in the pressing step, the solder particles are heated in a reducing environment. According to the above manufacturing method, a removing step of removing the base from the substrate is further provided after the pressing step. According to the above-mentioned manufacturing method, after the removal step, a cleaning step of removing solder particles not bonded to the electrodes is further provided. A component with a solder bump includes a substrate having an electrode and a solder bump on the electrode, and a depression is formed on at least a part of the surface of the solder bump. According to the above component with solder bumps, the depth of the depression of the solder bumps is 25% or less of the height of the solder bumps. According to the above component with solder bumps, adjacent solder bumps are independent from each other. According to the above member with solder bumps, the height of the solder bumps is smaller than the diameter of the solder bumps in the planar direction. A member for forming solder bumps, comprising: a substrate having a plurality of recesses having concavities and convexities on the bottom surface; and solder particles in the recesses. According to the above member for forming solder bumps, the height difference between the concave and convex portions of the concavo-convex is 20% or less of the average particle diameter of the solder particles. According to the above member for forming solder bumps, the average particle diameter of the solder particles is 1 to 35 μm, and the C.V. value is 20% or less. [Example]

Hereinafter, the present embodiment will be described in more detail using examples, but the present embodiment is not limited to these examples.

<Production of members for bump formation> (Production example 1) Step a1: Classification of solder particles After dipping 100 g of Sn-Bi solder particles (manufactured by 5N Plus Inc., melting point 139°C, Type 8) in distilled water and ultrasonically dispersing, the solder particles floating in the supernatant were collected by standing still. This operation was repeated, and 10 g of solder fine particles were collected. The obtained solder fine particles had an average particle diameter of 1.0 µm and a C.V. value of 42%. Step b1: Configuration on the substrate As shown in Table 1, a plurality of recesses having an opening diameter of 6.2 μm, a bottom surface diameter of 4.8 μm, a depth of 3.7 μm, and a bottom surface unevenness (the height difference between a concave portion and a convex portion. Formed by dry etching.) 0.4 μm were prepared. Substrate 1 (polyimide film, thickness 100 μm). A plurality of recesses are arranged in an orderly manner with a pitch of 6.4 μm. The solder microparticles (average particle diameter: 1.0 μm, C.V. value: 42%) obtained in step a1 were placed in the concave portion of the substrate 1 . In addition, excess solder fine particles were removed by rubbing the surface side of the substrate 1 on which the recesses were formed with a slightly sticky roller, and solder fine particles were arranged only in the recesses. Step c1: Formation of solder particles In step b1, the substrate 1 with solder fine particles arranged in the concave portion is put into a hydrogen radical reduction furnace (manufactured by SHINKO SEIKI CO., LTD., plasma reflow device), and after vacuuming, hydrogen gas is introduced into the furnace, Fill the furnace with hydrogen. Thereafter, the inside of the furnace was adjusted to 120° C., and hydrogen radicals were irradiated for 5 minutes. Thereafter, hydrogen gas in the furnace was removed by vacuuming, and after heating to 170° C., nitrogen was introduced into the furnace to return to atmospheric pressure, and the temperature in the furnace was lowered to room temperature to form solder particles. Thereby, the member (thin film) for solder bump formation which has solder particle in a recessed part was obtained.

【Table 1】 Production example 1 Production example 2 Production example 3 Production example 4 Matrix 1 Substrate 2 Matrix 3 Matrix 4 Opening diameter (μm) 6.2 9.4 15.6 23.7 Bottom diameter (μm) 4.8 7.2 12.0 18.2 Depth (μm) 3.7 5.6 9.2 14.0 Bottom unevenness (μm) 0.4 0.5 1.2 1.9 Dimple pitch (μm) 6.4 10.5 19.5 32.6

＜Evaluation of solder particles＞ A part of the solder bump forming member obtained through step c1 was fixed to the surface of a scanning electron microscope (SEM) observation stand, and platinum sputtering was performed on the surface. The diameters of 300 solder particles were measured by SEM, and the average particle diameter was calculated. The results are shown in Table 2. Also, using a laser microscope (manufactured by Olympus Corporation, LEXT OLS5000-SAF), the surface shape of a part of the member for forming solder bumps obtained through step c1 was measured, and the height of the solder particles from the surface of the substrate was measured, and 300 pieces were calculated. average value. The results are shown in Table 2.

(Production examples 2 to 4) Except having changed the recessed part dimension etc. as described in Table 1, the base body which held the solder particle inside was produced in the same manner as Production Example 1, and it evaluated. The results are shown in Table 2.

【Table 2】 Production example 1 Production example 2 Production example 3 Production example 4 Solder bump forming member 1 Solder bump forming member 2 Solder bump forming member 3 Solder bump forming member 4 Average particle size (μm) 4.1 6.1 10.1 15.3 CV value (%) 15.8 9.6 5.9 6.2 Height of solder particles from the surface of the substrate (μm) 0.4 0.5 0.9 1.3

＜Fabrication of evaluation wafer with solder bumps＞ Step d1: Evaluation of wafer preparation Four types of wafers with gold bumps (5×5 mm, thickness: 0.5 mm) shown below were prepared. Chip C1... Electrode size: 24μm×12μm, pitch: 48μm in X direction, 24μm in Y direction, number of bumps: 15,000 Wafer C2... Electrode size: 72μm×36μm, pitch: 144μm in X direction, 72μm in Y direction, number of bumps: 3400 Wafer C3... Electrode size: 96μm×48μm, pitch: 192μm in X direction, 96μm in Y direction, number of bumps: 850 Chip C4... Electrode size: 140μm×70μm, pitch: 280μm in X direction, 140μm in Y direction, number of bumps: 420

Step e1: Solder bump formation Solder bumps were formed on the wafer C1 prepared in step d1 using the member 1 for forming solder bumps produced in step c1 in the order of i) to ii) shown below. i) A glass plate (thickness 0.3mm) is placed on the lower hot plate of a formic acid reflow furnace (manufactured by SHINKO SEIKI CO.,LTD., intermittent vacuum welding device), and placed on the glass plate so that the Au electrode faces upward Wafer C1 was evaluated. The member 1 for forming solder bumps whose size was adjusted to 7×7 mm was placed on the evaluation wafer C1 so that the opening side of the recessed portion would face the Au electrode. In addition, a glass plate (0.3 mm in thickness) and a weight made of SUS were placed in this order on it. ii) After evacuation, formic acid gas was filled, and the temperature of the lower hot plate was raised to 150° C. and heated for 1 minute. Thereafter, after the formic acid gas was exhausted by vacuuming, nitrogen substitution was carried out, the lower hot plate was returned to room temperature, and the inside of the furnace was opened to the atmosphere, and solder particles were transferred onto the electrodes of the evaluation wafer C1 to form solder bumps. Piece. In this way, an evaluation wafer with solder bumps (member with solder bumps) was obtained. A depression of a predetermined depth is formed on top of the solder bump.

<Evaluation of evaluation wafers with solder bumps> Using a laser microscope (manufactured by Olympus Corporation, LEXT OLS5000-SAF), the height and diameter of the solder bumps on the evaluation wafer obtained through step e1 and the depth of depressions at the top of the solder bumps were measured, and the average value of 300 pieces was calculated. The results are shown in Table 3.

【table 3】 Production example 1 Production example 2 Production example 3 Production example 4 Evaluation wafer with solder bumps 1 Evaluation wafer with solder bumps 2 Evaluation wafer with solder bumps 3 Evaluation wafer with solder bumps 4 Bump height (μm) 3.6 5.5 9.0 13.8 Bump diameter (μm) 4.4 6.7 10.9 16.2 Depression depth at the top (μm) 0.4 0.5 0.8 1.1

(Production examples 2 to 4) Solder bump formation was performed in the same manner as in step e1 except that the members 2 to 4 for forming solder bumps and the evaluation wafers C2 to C4 were used. Moreover, 300 solder bumps on the electrode were evaluated, and the average value of the height and diameter of a solder bump, and the depth of the dent at the top of a solder bump was calculated. The results are shown in Table 3.

FIG. 8 is a SEM photograph of a member for forming solder bumps obtained in Production Example 1. FIG. It can be seen that a depression is formed on the top of the solder bump.

＜Creation of joint structure＞ Step f1: Evaluation of substrate preparation Four types of evaluation substrates (70×25 mm, thickness: 0.5 mm) with gold bumps shown below were prepared. This gold bump was arrange|positioned at the position which opposed the gold electrode of the said evaluation wafer C1-C4, and the alignment mark was provided in the board|substrate. In addition, lead wiring for resistance measurement was formed on a part of the gold bump. Substrate D1...area 24μm×12μm, pitch: 48μm in X direction, 24μm in Y direction, height: 3μm, number of bumps: 15,000 Substrate D2...area 72μm×36μm, pitch: 144μm in X direction, 72μm in Y direction, height: 3μm, number of bumps: 3400 Substrate D3...area 96μm×48μm, pitch: 192μm in X direction, 96μm in Y direction, height: 3μm, number of bumps: 850 Substrate D4...area 140μm×70μm, pitch: 280μm in X direction, 140μm in Y direction, height: 3μm, number of bumps: 420

Step g1: Bonding of electrodes In the order of i) to iv) shown below, the evaluation wafer with solder bumps produced in step e1 and the evaluation substrate with gold bumps prepared in step f1 were connected via solder bumps. i) Using a polyimide tape, the evaluation substrate D1 with gold bumps was fixed on the stage of a spin coater SC-308S (manufactured by Oshigane Co., Ltd.). A two-stage program in which a total of 9.6 g of WHS-003C (manufactured by ARAKAWA CHEMICAL INDUSTRIES, LTD.) as a liquid flux is added drop by drop at intervals of 1 cm, and the table is operated at 500 rpm for 10 seconds and at 1000 rpm for 3 seconds By rotating, the evaluation substrate D1 with gold bumps uniformly coated with liquid flux was obtained. The thickness of the flux layer measured after natural drying is 1 μm or less. ii) Place the flux-coated evaluation substrate D1 with gold bumps on the workbench of FC3000W (manufactured by TORAY ENGINEERING Co., Ltd.), pick up the evaluation chip C1 with solder bumps with the head, and use The alignment marks made the gold electrodes face each other, and the evaluation wafer C1 with solder bumps was placed on the evaluation substrate with gold bumps D1 coated with flux. Then, the bonded sample 1 was obtained by heat-compression bonding at a tool temperature of 220° C. for 6 seconds while pressing both with a tool. iii) The flux remaining between the evaluation wafer and the evaluation substrate was removed by washing the bonded sample 1 with isopropyl alcohol. iv) Put an appropriate amount of underfill material with adjusted viscosity (manufactured by Hitachi Chemical Co., Ltd., CEL series) between the evaluation wafer of bonding sample 1 and the evaluation substrate from which the residual flux has been removed, and fill it by vacuuming Then, it cured at 125 degreeC for 4 hours, and the bonded structure 1 of the evaluation wafer and the evaluation board|substrate was produced.

(Production examples 2 to 4) Except having used the evaluation wafer C2-4 with a solder bump, and the evaluation board|substrate D2-4 with a gold bump, it carried out similarly to process g1, and produced the bonded structures 2-4. The combinations of materials used in the fabrication of the connection structure are as follows. Connection structure (1): Wafer C1/member 1 for forming solder bumps/substrate D1 Connection structure (2): Wafer C2/member 2 for forming solder bumps/substrate D2 Connection structure (3): Wafer C3/member 3 for forming solder bumps/substrate D3 Connected structure (4): Wafer C4/Solder bump forming member 4/Substrate D4

＜Evaluation of bonded structures＞ A conduction resistance test and an insulation resistance test were performed on a part of the obtained bonded structure. The results are shown in Table 4, Table 5 and Table 6.

(On-resistance test-moisture absorption heat resistance test) Regarding the on-resistance between wafer with gold bumps/substrate with gold bumps, the initial value of on-resistance and moisture absorption and heat resistance test (placed under the conditions of temperature 85°C and humidity 85%) were measured for 20 samples 100, 500, 1000 hours), and calculate the average value of these. Based on the obtained average values, the conduction resistance was evaluated according to the following criteria. The results are shown in Table 4. In addition, when the following criteria of A or B are satisfied after 1000 hours of the moisture absorption heat resistance test, it can be said that the conduction resistance is good. A: The average value of on-resistance is less than 2Ω B: The average value of on-resistance is more than 2Ω and less than 5Ω C: The average value of on-resistance is more than 5Ω and less than 10Ω D: The average value of on-resistance is more than 10Ω and less than 20Ω E: The average value of on-resistance is 20Ω or more

(On-resistance test - high temperature storage test) Regarding the on-resistance between wafer with gold bump (bump)/substrate with gold bump (bump), the initial value of on-resistance and high-temperature placement test (at a temperature of 100°C) were measured for 20 samples The value after placing 100, 500, 1000 hours under the same conditions). After standing at a high temperature, a drop impact was applied, and the conduction resistance of the sample after the drop impact was measured. The drop impact is caused by fixing the connection structure to the metal plate by screw fastening and dropping it from a height of 50cm. After the drop, DC resistance values were measured at the solder joints (4 locations) at the corners of the wafer where the impact was greatest, and when the measured value increased by 5 times or more from the initial resistance, it was evaluated as fracture. Four sites were measured for each sample, and a total of 80 sites were measured. The results are shown in Table 5. After the number of times of dropping was 20 times, when the following criteria of A or B were satisfied, it was evaluated that the solder connection reliability was good. A: The fracture occurrence site is 0 site. B: Fracture occurrence sites are at least one site and at most five sites. C: Fracture occurrence sites are at least 6 sites and at most 20 sites. D: There are 21 or more fracture occurrence sites.

(Insulation resistance test) Regarding the insulation resistance between wafer electrodes, the initial value of insulation resistance and migration test were measured for 20 samples (100, 500, 1000 hours under conditions of temperature 60°C, humidity 90%, 20V application) Then, the ratio of the samples having an insulation resistance value of 10 ⁹ Ω or more among all 20 samples was calculated. Based on the obtained ratio, the insulation resistance was evaluated according to the following criteria. The results are shown in Table 6. In addition, when the following criteria of A or B are satisfied after 1000 hours of the migration test, it can be said that the insulation resistance is good. A: 100% of the insulation resistance value is 10 ⁹ Ω or more B: 90% or less of the insulation resistance value is 10 ⁹ Ω or more C: 80% of the insulation resistance value is 10 ⁹ Ω or more % or more and less than 90% D: The ratio of the insulation resistance value of 10 ⁹ Ω or more is more than 50% and less than 80% E: The ratio of the insulation resistance value of 10 ⁹ Ω or more is less than 50%

【Table 4】 Example 1 Example 2 Example 3 Example 4 connection structure Test time Production example 1 Production example 2 Production example 3 Production example 4 ON resistance Moisture absorption and heat resistance test (1) early stage A 100 hours later A after 500 hours A after 1000 hours A (2) early stage A 100 hours later A after 500 hours A after 1000 hours A (3) early stage A 100 hours later A after 500 hours B after 1000 hours B (4) early stage A 100 hours later A after 500 hours B after 1000 hours B

【table 5】 Example 1 Example 3 connection structure Test time Production example 1 Production example 3 ON resistance High temperature storage test (1) early stage A 100 hours later A after 500 hours A after 1000 hours B (3) early stage A 100 hours later A after 500 hours B after 1000 hours B

【Table 6】 Example 1 Example 2 Example 3 Example 4 connection structure Test time Production example 1 Production example 2 Production example 3 Production example 4 Insulation resistance Moisture absorption and heat resistance test (1) early stage A 100 hours later A after 500 hours A after 1000 hours B (2) early stage A 100 hours later A after 500 hours A after 1000 hours B (3) early stage A 100 hours later A after 500 hours A after 1000 hours A (4) early stage A 100 hours later A after 500 hours A after 1000 hours A

1: Solder particles 1A: Solder bumps 1B: Solder layer 2: Substrate 3: electrode 4: Other substrates 5: Other electrodes 10: Members for forming solder bumps 20: Components with solder bumps 30: Connection structure 60: matrix 62: Concave 111: Solder particles 600: matrix 601: Basal layer 602: Concave layer

FIG. 1 is a cross-sectional view schematically showing a member for forming solder bumps according to an embodiment. Fig. 2 is a cross-sectional view schematically showing an example of a substrate. 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). 4( a ) to 4 ( d ) are cross-sectional views schematically showing examples of the cross-sectional shape of the concave portion of the base body. FIG. 5 is a cross-sectional view schematically showing a state in which solder fine particles 111 are accommodated in the concave portion 62 of the base body 60 . 6( a ) and FIG. 6( b ) are cross-sectional views schematically showing an example of a manufacturing process of a member with solder bumps. 7( a ) and FIG. 7( b ) are cross-sectional views schematically showing an example of the manufacturing process of the bonded structure. FIG. 8 is a SEM photograph of a member for forming solder bumps obtained in Production Example 1. FIG.

1: Solder particles

2: Substrate

3: electrode

20: Components with solder bumps

60: matrix

A, B: Arrows

1A: Solder bumps

Claims (14)

A method of manufacturing a component with solder bumps, comprising: A preparation step, preparing a substrate having a plurality of concave portions with concavities and convexities on the bottom surface; an arranging step of arranging solder particles in the aforementioned recess; and In the pressing step, pressing the base body and the substrate having the electrodes in a state where the solder particles and the electrodes are opposed to bring the solder particles into contact with the electrodes, thereby forming a solder bump having depressions on at least a part of the surface of the electrodes. Piece. The manufacturing method as described in claim 1, wherein In the pressing step, the solder particles are heated. The manufacturing method as described in claim 1 or claim 2, wherein A reducing step of exposing the solder particles to a reducing environment is further provided before the arranging step. The manufacturing method according to any one of claim 1 to claim 3, wherein A reducing step of exposing the solder particles to a reducing environment is further provided after the arranging step and before the pressing step. The manufacturing method according to any one of claim 1 to claim 4, wherein In the pressing step, the solder particles are heated in a reducing environment. The manufacturing method according to any one of claim 1 to claim 5, wherein After the pressing step, a removing step of removing the base from the substrate is further provided. The manufacturing method as described in claim 6, wherein After the removal step, a cleaning step for removing the solder particles not bonded to the electrode is further provided. A component with solder bumps, comprising: a substrate having electrodes; and solder bumps on the electrodes, A depression is formed on at least a part of the surface of the solder bump. The component with solder bumps as described in Claim 8, wherein The concave depth of the aforementioned solder bump is less than 25% of the height of the solder bump. The component with solder bumps as described in Claim 8 or Claim 9, wherein Adjacent solder bumps are independent from each other. The component with solder bumps according to any one of claims 8 to 10, wherein The height of the aforementioned solder bump is smaller than the diameter in the planar direction of the aforementioned solder bump. A member for forming solder bumps, comprising: a substrate having a plurality of concave portions having concavo-convex portions on a bottom surface; and solder particles in the concave portions. The member for forming solder bumps according to claim 12, wherein The height difference between the concave and convex portions of the unevenness is 20% or less of the average particle diameter of the solder particles. The solder bump forming member according to claim 12 or claim 13, wherein The solder particles have an average particle diameter of 1 to 35 μm, and a C.V. value of 20% or less.

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