Resin composition and method for producing connection structure

Abstract

The present invention provides a resin composition (11) with which it is possible to enhance the ease of capturing a semiconductor chip (3) that is incoming at high speed.　The resin composition (11) according to the present invention contains a thermosetting component (11B), a flux (11C), a thixotropic agent that is in a liquid state at 25° C, and solder particles (11A).

Description

Resin composition and method for producing connection structure

[0001] The present invention relates to a resin composition containing solder particles, and also to a method for producing a connection structure using the resin composition.

[0002] Anisotropic conductive materials such as anisotropic conductive pastes and anisotropic conductive films are widely known. In these anisotropic conductive materials, conductive particles are dispersed in a binder. Solder particles are widely used as the conductive particles.

[0003] The anisotropic conductive material is used to obtain various connection structures, such as a connection between a flexible printed circuit board and a glass substrate (FOG (Film on Glass)), a connection between a semiconductor chip and a flexible printed circuit board (COF (Chip on Film)), a connection between a semiconductor chip and a glass substrate (COG (Chip on Glass)), and a connection between a flexible printed circuit board and a glass epoxy substrate (FOB (Film on Board)).

[0004] In recent years, devices using connection structures have become smaller and lighter. Accordingly, there is a demand for the development of connection structures using fine semiconductor chips such as micro-light emitting diode (micro-LED) chips. Laser transfer methods have attracted attention as a method for placing fine semiconductor chips such as micro-LED chips on circuit boards.

[0005] Japanese Patent Application Laid-Open No. 2006-124993 discloses a laser transfer device. In this laser transfer device, a source substrate on which a plurality of elements are formed is placed above a destination substrate. Laser light is irradiated onto the source substrate from above, causing a plurality of target elements to be transferred downward, and the target elements are transferred to the destination substrate.

[0006] Patent Document 2 listed below discloses a transfer method for transferring a chip component held on a transfer substrate via a photocurable adhesive layer to a destination substrate. The transfer method includes an exposure step of pattern-exposing the adhesive layer to light of a wavelength that hardens the adhesive layer to partially reduce the adhesive strength of the adhesive layer, and a laser lift-off step of transferring the chip component to the destination substrate by a laser lift-off method after the exposure step.

[0007] WO2020 / 188780A1 JP 2020-53558 A

[0008] In the method of arranging semiconductor chips using laser transfer, multiple semiconductor chips can be moved and mounted in one go from a wafer substrate (source substrate) to a circuit board (destination substrate), thereby increasing the productivity of the connection structure.

[0009] However, in the method of placing a semiconductor chip using the laser transfer method, the semiconductor chip may not be accurately placed in a predetermined position on the circuit board (connection target member) due to the impact when the semiconductor chip, which is flying at high speed, lands on the circuit board (connection target member). If misalignment occurs during placement of the semiconductor chip, it may be impossible to electrically connect the upper and lower electrodes.

[0010] An object of the present invention is to provide a resin composition that can enhance the capture of semiconductor chips flying at high speeds. Another object of the present invention is to provide a method for producing a connection structure using the resin composition.

[0011] As a result of extensive research, the inventors have discovered that by placing a specific resin composition on the surface of a circuit board (a component to be connected), it is possible to effectively capture semiconductor chips that fly in at high speed using a laser transfer method or the like.

[0012] Disclosed herein are the following resin compositions and methods for producing connection structures using the resin compositions.

[0013] Item 1. A resin composition comprising a thermosetting component, a flux, a thixotropic agent that is liquid at 25°C, and solder particles.

[0014] Item 2. The resin composition according to Item 1, wherein the flux includes a first flux having an even number of carbon atoms in its main chain and a second flux having an odd number of carbon atoms in its main chain.

[0015] Item 3. The hydrogen bond term δH in the Hansen solubility parameter of the thixotropic agent is 10 MPa １／２ Item 3. The resin composition according to Item 2, wherein the number of carbon atoms in the main chain of the first flux is an even number of 4 or more and 14 or less, and the number of carbon atoms in the main chain of the second flux is an odd number of 3 or more and 11 or less.

[0016] Item 4. The resin composition according to Item 2 or 3, wherein the first flux has an average particle size of 10 μm or less.

[0017] Item 5. The resin composition according to any one of Items 2 to 4, wherein the second flux is soluble in the thixotropic agent at 25°C.

[0018] Item 6. The resin composition according to any one of Items 2 to 5, wherein the content of the second flux is 1% by weight or more and 20% by weight or less, based on 100% by weight of the resin composition.

[0019] Item 7. The resin composition according to any one of Items 1 to 6, wherein the thixotropic agent includes glycerin.

[0020] Item 8. The resin composition according to any one of Items 1 to 7, wherein the content of the flux is 5% by weight or more and 25% by weight or less, based on 100% by weight of the resin composition.

[0021] Item 9. The resin composition according to any one of Items 1 to 8, wherein the solder particles have an average particle size of 10 μm or less.

[0022] Item 10. A method for producing a connection structure, comprising: a first arrangement step of using the resin composition according to any one of Items 1 to 9 to arrange the resin composition on a surface of a first connection target component having at least one first electrode on its surface; a second arrangement step of moving a second connection target component having at least one second electrode on its surface by laser transfer onto a surface of the resin composition opposite the first connection target component side, and arranging the second connection target component so that the first electrode and the second electrode face each other; and a connection step of heating the resin composition to a temperature equal to or higher than the melting point of the solder particles to form a connection portion connecting the first connection target component and the second connection target component using the resin composition, and electrically connecting the first electrode and the second electrode by a solder portion in the connection portion.

[0023] Item 11. The method for manufacturing a connection structure according to Item 10, wherein in the second placing step, the second connection target member is moved by a laser transfer method on a surface of the resin composition opposite to the first connection target member side at a speed of 1 cm / s or more, and the second connection target member is placed so that the first electrode and the second electrode face each other.

[0024] The resin composition according to the present invention contains a thermosetting component, a flux, a thixotropic agent that is liquid at 25° C., and solder particles. Because the resin composition according to the present invention has the above-described configuration, it can improve the ability to capture semiconductor chips that fly at high speed.

[0025] Fig. 1 is a cross-sectional view schematically showing a connection structure obtained using a resin composition according to one embodiment of the present invention. Fig. 2 is a cross-sectional view illustrating the steps of an example of a method for producing a connection structure using a resin composition according to one embodiment of the present invention. Fig. 3 is a cross-sectional view illustrating the steps of an example of a method for producing a connection structure using a resin composition according to one embodiment of the present invention. Fig. 4 is a cross-sectional view illustrating the steps of an example of a method for producing a connection structure using a resin composition according to one embodiment of the present invention. Fig. 5 is a cross-sectional view illustrating a modified example of the connection structure.

[0026] The present invention will be described in detail below.

[0027] (Resin Composition) The resin composition according to the present invention contains a thermosetting component, a flux, a thixotropic agent that is liquid at 25° C., and solder particles.

[0028] In conventional methods for placing semiconductor chips using laser transfer, the impact of a semiconductor chip flying at high speed on a circuit board (a component to be connected) can make it difficult to accurately place the semiconductor chip in a predetermined location on the circuit board (a component to be connected). If misalignment occurs during placement of the semiconductor chip, it may be impossible to establish a conductive connection between the upper and lower electrodes.

[0029] The resin composition according to the present invention has the above-described configuration, and therefore can enhance the capture of semiconductor chips arriving at high speed. In particular, the capture of semiconductor chips arriving at high speed by laser transfer can be enhanced. As a result, the arriving semiconductor chip can be accurately positioned in a predetermined location on the circuit board (connection target component) (effectively suppressing misalignment during placement of the semiconductor chip).

[0030] In the present invention, the use of a specific resin composition greatly contributes to achieving the above-mentioned effects.

[0031] The resin composition is used by being placed on the surface of a connection target member (circuit board, transfer destination substrate) in a method for manufacturing a connection structure. The resin composition is suitably used in a method for manufacturing a connection structure to effectively capture a semiconductor chip that flies in at high speed by a laser transfer method. The resin composition is preferably a resin composition for capturing a semiconductor chip by a laser transfer method.

[0032] In particular, the resin composition according to the present invention is preferably used for connecting semiconductor chips by laser transfer method (use of resin composition for connecting semiconductor chips by laser transfer method). More specifically, the resin composition according to the present invention is more preferably used for connecting semiconductor chips to a substrate by laser transfer method (use of resin composition for connecting semiconductor chips to a substrate by laser transfer method).

[0033] The resin composition has a water contact angle of preferably 65° or less, more preferably 60° or less, even more preferably 55° or less, and particularly preferably 45° or less. When the resin composition has a water contact angle of less than the upper limit, the ability to capture semiconductor chips arriving at high speeds by laser transfer can be further enhanced. Specifically, semiconductor chip electrodes generally contain gold, copper, or alloys thereof, and therefore the surfaces of the semiconductor chip electrodes are often hydrophilic. When the resin composition according to the present invention has a water contact angle of less than the upper limit, the surface of the resin composition has hydrophilicity, resulting in a high affinity with the surface of the semiconductor chip electrodes. When the resin composition is placed on the surface of a connection target component (circuit board), the ability to capture semiconductor chips arriving at high speeds by laser transfer can be further enhanced. The lower limit of the water contact angle of the resin composition at 25°C is not particularly limited. The water contact angle of the resin composition at 25°C may be 0° or greater, greater than 0°, 1° or greater, or 5° or greater. The range of the contact angle can be set by appropriately selecting the lower limit and the upper limit.

[0034] The contact angle of the resin composition with water at 25°C can be measured, for example, by the following method. 1 ml of water is dropped onto the surface of the resin composition, and the contact angle of the resin composition with water is measured using a contact angle measuring device. An example of the contact angle measuring device is the "DMo-601" manufactured by KYOWA Corporation. The contact angle of the resin composition with water at 25°C is measured 10 seconds after the water is placed on the surface of the resin composition.

[0035] The contact angle of the resin composition with water at 25°C can be adjusted by the following methods, etc.: A method of combining multiple skeletons of a thermosetting component such as an epoxy resin; A method of selecting a skeleton of a thermosetting component such as an epoxy resin; A method of selecting a side chain of a thermosetting component such as an epoxy resin; A method of dispersing an additive that is liquid at 25°C into the resin composition.

[0036] The resin composition is preferably in a liquid state at 25°C. A paste state is included in the liquid state. The resin composition is preferably in a paste state at 25°C. The resin composition contains solder particles and is therefore a conductive material. The resin composition is preferably a conductive paste. The resin composition is preferably a conductive paste at 25°C. In these cases, the resin composition can be applied more thinly and effectively to the surface of the connection target component, which can more effectively enhance the ability to capture semiconductor chips that fly at high speed by the laser transfer method and more effectively enhance the cohesion of the solder during conductive connection.

[0037] The viscosity (η25) of the resin composition at 25°C is preferably 30 Pa·s or more, more preferably 50 Pa·s or more, and preferably 250 Pa·s or less, more preferably 200 Pa·s or less. When the viscosity (η25) is above the lower limit, the capture ability of semiconductor chips flying at high speed by laser transfer method can be more effectively improved. When the viscosity (η25) is below the upper limit, the resin composition can be applied thinly and well to the surface of the connection target component, effectively improving the cohesion of the solder during conductive connection. The viscosity (η25) can be appropriately adjusted by the type and amount of the blended components.

[0038] The viscosity (η25) can be measured, for example, using an E-type viscometer ("TVE-22L" manufactured by Toki Sangyo Co., Ltd.) under conditions of 25° C. and 5 rpm.

[0039] The viscosity (ηmp) of the resin composition at the melting point of the solder particles is preferably 0.1 Pa·s or more, more preferably 1 Pa·s or more, and preferably 10 Pa·s or less, more preferably 5 Pa·s or less. The viscosity (ηmp) can be appropriately adjusted by the types and amounts of the blended components. When the viscosity (ηmp) is equal to or greater than the lower limit and equal to or less than the upper limit, the cohesion of the solder during conductive connection can be more effectively improved, voids at the connection can be more effectively suppressed, and the resin composition can be more effectively suppressed from spilling out of the connection area. When the viscosity (ηmp) is equal to or greater than the lower limit and equal to or less than the upper limit, the insulation reliability between electrodes can be more effectively improved, and the conduction reliability between electrodes can be more effectively improved.

[0040] The viscosity (ηmp) can be measured, for example, using a viscoelasticity measuring device ("HAAKE" manufactured by SCIENTIFIC) under conditions of stress control of 1 Pa, frequency of 1 Hz, temperature rise rate of 20°C / min, and measurement temperature range of 25°C to 200°C. However, if the melting point of the solder particles exceeds 200°C, the upper temperature limit is set to the melting point of the solder particles. In this measurement, the viscosity (ηmp) is calculated by reading the viscosity at the melting point of the solder particles.

[0041] The resin composition can be used as a conductive paste, a conductive film, etc. The conductive paste is preferably an anisotropic conductive paste, and the conductive film is preferably an anisotropic conductive film. From the viewpoint of more effectively suppressing misalignment when arranging components to be connected and more effectively enhancing the cohesiveness of solder during conductive connection, the resin composition is preferably in the form of a paste, and is preferably a conductive paste. The resin composition is suitably used for electrical connection of electrodes. The resin composition is preferably a circuit connection material.

[0042] Each component contained in the resin composition will be described below. In this specification, the term "(meth)acrylate" refers to acrylate and methacrylate. The term "(meth)acrylic" refers to acrylic and methacrylic. The term "(meth)acryloyl" refers to acryloyl and methacryloyl.

[0043] (Thermosetting Component) The resin composition according to the present invention contains a thermosetting component. The thermosetting component preferably contains a thermosetting compound. The resin composition may or may not contain a thermosetting agent as the thermosetting component. Since the resin composition according to the present invention has the above-mentioned configuration, even when the resin composition does not contain a thermosetting agent, it can improve the capture ability of semiconductor chips flying at high speed by laser transfer method. From the viewpoint of more effectively improving the cohesion of solder during conductive connection, it is preferable that the resin composition does not contain a thermosetting agent. In order to cure the resin composition more satisfactorily, the resin composition may contain a curing accelerator as the thermosetting component.

[0044] (Thermosetting Component: Thermosetting Compound) The resin composition according to the present invention preferably contains a thermosetting compound. The thermosetting compound is a compound that can be cured by heating. The thermosetting compound is not particularly limited. Examples of the thermosetting compound include oxetane compounds, epoxy compounds, episulfide compounds, (meth)acrylic compounds, phenolic compounds, amino compounds, unsaturated polyester compounds, polyurethane compounds, silicone compounds, and polyimide compounds. From the viewpoint of further improving the curability and viscosity of the resin composition and further increasing the conductivity reliability, the thermosetting compound is preferably an epoxy compound or an episulfide compound, and more preferably an epoxy compound. The resin composition preferably contains an epoxy compound or an episulfide compound, and more preferably contains an epoxy compound. Only one type of the thermosetting compound may be used, or two or more types may be used in combination.

[0045] The epoxy compound is a compound having at least one epoxy group. Examples of the epoxy compound include bisphenol A type epoxy compounds, bisphenol F type epoxy compounds, bisphenol S type epoxy compounds, phenol novolac type epoxy compounds, biphenyl type epoxy compounds, biphenyl novolac type epoxy compounds, biphenol type epoxy compounds, naphthalene type epoxy compounds, fluorene type epoxy compounds, phenol aralkyl type epoxy compounds, naphthol aralkyl type epoxy compounds, dicyclopentadiene type epoxy compounds, anthracene type epoxy compounds, epoxy compounds having an adamantane skeleton, epoxy compounds having a tricyclodecane skeleton, naphthylene ether type epoxy compounds, and epoxy compounds having a triazine nucleus in the skeleton. The epoxy compounds may be used alone or in combination of two or more.

[0046] The epoxy compound is liquid or solid at room temperature (25°C). If the epoxy compound is solid at room temperature, the melting temperature of the epoxy compound is preferably equal to or lower than the melting point of the solder particles. By using the preferred epoxy compound, the viscosity is high when the connection target components are bonded together, and misalignment between the connection target components (circuit boards) and the semiconductor chips can be suppressed when acceleration is applied due to impacts such as transport. Furthermore, the heat generated during curing significantly reduces the viscosity of the resin composition, allowing the solder to efficiently aggregate during conductive connection.

[0047] From the viewpoint of more effectively improving insulation reliability and more effectively improving conduction reliability, it is preferable that the thermosetting component contains an epoxy compound, and it is preferable that the thermosetting compound contains an epoxy compound.

[0048] From the viewpoint of disposing the solder on the electrodes more effectively, the thermosetting compound preferably includes a thermosetting compound having a polyether skeleton.

[0049] Examples of the thermosetting compound having a polyether skeleton include a compound having a glycidyl ether group at both ends of an alkyl chain having 3 to 12 carbon atoms, and a polyether-type epoxy compound having a polyether skeleton having 2 to 4 carbon atoms and a structural unit in which 2 to 10 such polyether skeletons are bonded in succession.

[0050] From the viewpoint of more effectively increasing the heat resistance of the cured product, the thermosetting compound preferably includes a thermosetting compound having an isocyanuric skeleton.

[0051] Examples of the thermosetting compound having an isocyanuric skeleton include triisocyanurate-type epoxy compounds, such as the TEPIC series (TEPIC-G, TEPIC-S, TEPIC-SS, TEPIC-HP, TEPIC-L, TEPIC-PAS, TEPIC-VL, and TEPIC-UC) manufactured by Nissan Chemical Industries, Ltd.

[0052] From the viewpoints of more efficiently disposing the solder on the electrodes, more effectively improving the reliability of conduction between the upper and lower electrodes to be connected, and more effectively suppressing discoloration of the thermosetting compound, the thermosetting compound preferably has high heat resistance and more preferably contains a novolac epoxy compound. Novolac epoxy compounds have relatively high heat resistance.

[0053] In 100% by weight of the resin composition, the content of the thermosetting compound is preferably 5% by weight or more, more preferably 8% by weight or more, even more preferably 10% by weight or more, and preferably 99% by weight or less, more preferably 90% by weight or less, even more preferably 80% by weight or less, and particularly preferably 70% by weight or less. When the content of the thermosetting compound is above the lower limit and below the upper limit, the capture of semiconductor chips flying at high speed by laser transfer method can be more effectively improved, solder can be more efficiently placed on the electrodes, the insulation reliability between electrodes can be more effectively improved, and the conduction reliability between electrodes can be more effectively improved. From the viewpoint of more effectively improving the impact resistance of the resulting connection structure, the content of the thermosetting compound is preferably high.

[0054] In 100% by weight of the resin composition, the content of the epoxy compound is preferably 5% by weight or more, more preferably 8% by weight or more, even more preferably 10% by weight or more, and preferably 99% by weight or less, more preferably 90% by weight or less, even more preferably 80% by weight or less, and particularly preferably 70% by weight or less. When the content of the epoxy compound is above the lower limit and below the upper limit, the capture of semiconductor chips flying at high speed by laser transfer method can be more effectively improved, solder can be more efficiently placed on the electrodes, the insulation reliability between electrodes can be more effectively improved, and the conduction reliability between electrodes can be more effectively improved. From the viewpoint of further improving the impact resistance of the resulting connection structure, the content of the epoxy compound is preferably high.

[0055] The content of the novolac epoxy compound in 100% by weight of the resin composition is preferably 1% by weight or more, more preferably 3% by weight or more, even more preferably 5% by weight or more, and preferably 99% by weight or less, more preferably 90% by weight or less, even more preferably 80% by weight or less, and particularly preferably 70% by weight or less. When the content of the novolac epoxy compound is above the above lower limit and below the above upper limit, the capture ability of semiconductor chips flying at high speed by laser transfer method can be more effectively improved, solder can be more efficiently arranged on the electrodes, the insulation reliability between electrodes can be more effectively improved, and the conduction reliability between electrodes can be more effectively improved. From the viewpoint of further improving the impact resistance of the resulting connection structure, the content of the novolac epoxy compound is preferably higher.

[0056] (Flux) The resin composition contains a flux, which can more effectively enhance the cohesion of the solder during conductive connection.

[0057] Examples of the flux include zinc chloride, a mixture of zinc chloride and an inorganic halide, a mixture of zinc chloride and an inorganic acid, a molten salt, phosphoric acid, a derivative of phosphoric acid, an organic acid, an organic acid amine salt, an organic halide, hydrazine, an amine compound other than an organic acid amine salt, and pine resin. Only one type of the flux may be used, or two or more types may be used in combination.

[0058] The flux preferably contains an organic acid or an organic acid amine salt. The organic acid is preferably a dicarboxylic acid, and the organic acid amine salt is preferably a dicarboxylic acid amine salt. The flux preferably contains a dicarboxylic acid or a dicarboxylic acid amine salt, and more preferably contains a dicarboxylic acid and a dicarboxylic acid amine salt.

[0059] Examples of the dicarboxylic acid include glutaric acid, adipic acid, azelaic acid, and pimelic acid.

[0060] Examples of the dicarboxylic acid amine salt include benzylamine glutarate, benzylamine adipate, benzylamine azelaate, stearylamine glutarate, stearylamine adipate, and stearylamine azelaate.

[0061] The flux is preferably solid and may be spherical, may have a shape other than spherical, or may be flat.

[0062] From the viewpoint of more effectively enhancing the capture ability of semiconductor chips flying at high speed by the laser transfer method, it is preferable that the flux contains two or more types of fluxes having different numbers of carbon atoms in their main chains. From the viewpoint of more effectively enhancing the capture ability of semiconductor chips flying at high speed by the laser transfer method, it is preferable that the flux contains a first flux having an even number of carbon atoms in its main chain and a second flux having an odd number of carbon atoms in its main chain. Only one type of flux may be used as the first flux, or two or more types of flux may be used. Only one type of flux may be used as the second flux, or two or more types of flux may be used.

[0063] The number of carbon atoms in the main chain of the first flux is an even number. The number of carbon atoms in the main chain of the first flux is an even number, and the number of carbon atoms in the main chain of the first flux is preferably 4 or more, more preferably 6 or more, and preferably 14 or less, more preferably 12 or less, even more preferably 10 or less, and particularly preferably 8 or less. The number of carbon atoms in the main chain of the first flux is preferably an even number of 4 or more and 14 or less. When the number of carbon atoms in the main chain of the first flux is equal to or more than the above lower limit and equal to or less than the above upper limit, the solder can be more efficiently disposed on the electrodes.

[0064] The number of carbon atoms in the main chain of the second flux is an odd number. The number of carbon atoms in the main chain of the second flux is an odd number, and the number of carbon atoms in the main chain of the second flux is preferably 3 or more and preferably 11 or less, more preferably 9 or less, and even more preferably 7 or less. The number of carbon atoms in the main chain of the second flux is preferably an odd number between 3 and 11. When the number of carbon atoms in the main chain of the second flux is equal to or greater than the above lower limit and equal to or less than the above upper limit, the solder can be more efficiently arranged on the electrodes.

[0065] The average particle diameter of the flux (average particle diameter of the entire flux) is preferably 10 μm or less, more preferably 7 μm or less, even more preferably 5 μm or less, and particularly preferably 3 μm or less. When the average particle diameter of the flux is equal to or less than the above upper limit, the ability to capture semiconductor chips flying at high speed by laser transfer method can be more effectively improved. The lower limit of the average particle diameter of the flux is not particularly limited. The average particle diameter of the flux may be 0.01 μm or more, 0.1 μm or more, 0.5 μm or more, or 1.0 μm or more. The range of the average particle diameter of the flux can be set by appropriately selecting the above lower limit and upper limit.

[0066] The average particle diameter of the first flux is preferably 10 μm or less, more preferably 7 μm or less, and even more preferably 5 μm or less. When the average particle diameter of the first flux is equal to or less than the above upper limit, the capture ability of semiconductor chips flying at high speed by laser transfer method can be more effectively improved. The lower limit of the average particle diameter of the first flux is not particularly limited. The average particle diameter of the first flux may be 0.5 μm or more, or may be 1.0 μm or more. The range of the average particle diameter of the first flux can be set by appropriately selecting the above lower limit and upper limit.

[0067] The average particle diameter of the second flux is preferably 7 μm or less, more preferably 5 μm or less, and even more preferably 3 μm or less. When the average particle diameter of the second flux is equal to or less than the above upper limit, the capture ability of semiconductor chips flying at high speed by laser transfer method can be more effectively improved. The lower limit of the average particle diameter of the second flux is not particularly limited. The average particle diameter of the second flux may be 0.01 μm or more, or may be 0.1 μm or more. The range of the average particle diameter of the second flux can be set by appropriately selecting the above lower limit and upper limit.

[0068] The average particle size of the flux and the average particle sizes of the first and second fluxes are number-average particle sizes. The average particle size of the flux and the average particle size of the first and second fluxes can be determined, for example, by observing 50 random fluxes with an electron microscope or an optical microscope and calculating the average particle size of each flux, or by performing laser diffraction particle size distribution measurement. In observation with an electron microscope or an optical microscope, the particle size of each flux is determined as the particle size of a circle-equivalent diameter. In observation with an electron microscope or an optical microscope, the average particle size of 50 random fluxes with the circle-equivalent diameter is approximately equal to the average particle size of each sphere-equivalent diameter. In laser diffraction particle size distribution measurement, the particle size of each flux is determined as the particle size of a sphere-equivalent diameter. The average particle size of the flux and the average particle sizes of the first and second fluxes are preferably calculated by laser diffraction particle size distribution measurement.

[0069] The flux and the first and second fluxes may be pulverized commercially available fluxes. Examples of methods for pulverizing commercially available fluxes include agate pulverization, jet mill pulverization, and bead mill pulverization.

[0070] The coefficient of variation (CV value) of the particle size of the flux (coefficient of variation (CV value) of the particle size of the entire flux) is preferably 10% or less, more preferably 5% or less. When the coefficient of variation of the particle size of the flux is equal to or less than the above upper limit, the flux can be more efficiently disposed on the electrode. The lower limit of the coefficient of variation (CV value) of the particle size of the flux is not particularly limited. The coefficient of variation (CV value) of the particle size of the flux may be 0% or more, 1% or more, or 5% or more. The range of the coefficient of variation of the particle size of the flux can be set by appropriately selecting the above lower limit and upper limit.

[0071] The coefficient of variation (CV value) of the particle size of the flux can be measured as follows.

[0072] CV value (%) = (ρ / Dn) × 100 ρ: Standard deviation of flux particle diameter Dn: Average value of flux particle diameter

[0073] The activation temperature (melting point) of the flux is preferably 50°C or higher, more preferably 70°C or higher, and even more preferably 80°C or higher, and is preferably 200°C or lower, more preferably 190°C or lower, and even more preferably 180°C or lower. When the activation temperature of the flux is above the lower limit and below the upper limit, the flux effect is more effectively exerted, and the solder is more efficiently disposed on the electrodes. The activation temperature (melting point) of the flux is preferably 70°C or higher and 190°C or lower, and particularly preferably 80°C or higher and 180°C or lower.

[0074] The activation temperature (melting point) of the flux can be determined by differential scanning calorimetry (DSC). Examples of DSC devices include the "EXSTAR DSC7020" manufactured by SII.

[0075] Examples of the flux having an active temperature (melting point) of 80°C or higher and 180°C or lower include dicarboxylic acids such as glutaric acid (melting point 96°C), glutaric acid benzylamine salt (melting point 108°C), adipic acid (melting point 152°C), adipic acid benzylamine salt (melting point 180°C), pimelic acid (melting point 104°C), and suberic acid (melting point 142°C), benzoic acid (melting point 122°C), and malic acid (melting point 130°C).

[0076] The boiling point of the flux is preferably 200° C. or less.

[0077] From the viewpoint of improving the coatability and screen printability of the resin composition, it is preferable that the second flux be soluble in the thixotropic agent at 25°C. The first flux may or may not be soluble in the thixotropic agent at 25°C. From the viewpoint of improving the coatability and screen printability of the resin composition and enhancing the cohesion of solder particles, it is preferable that the first flux is not soluble in the thixotropic agent at 25°C, and the second flux is soluble in the thixotropic agent at 25°C. In this specification, "the flux is soluble in the thixotropic agent" means that when 10 g of the flux is placed in 20 g of the thixotropic agent and maintained at 25°C for 10 minutes, the weight of the flux that dissolves in the thixotropic agent is 4 g or more.

[0078] The flux and the first and second fluxes may be dispersed in a resin composition or may be attached to the surfaces of solder particles. The second flux may be dissolved in a thixotropic agent before use. The material of the resin composition may contain the second flux dissolved in the thixotropic agent.

[0079] From the viewpoint of disposing the solder on the electrodes more efficiently, the first flux is preferably 1,10-decanedicarboxylic acid, adipic acid, or a salt thereof, and more preferably adipic acid or a salt of adipic acid. From the viewpoint of disposing the solder on the electrodes more efficiently, the first flux is preferably 1,10-decanedicarboxylic acid or adipic acid, and more preferably adipic acid.

[0080] From the viewpoint of disposing the solder on the electrode more efficiently, the second flux is preferably pimelic acid, azelaic acid, glutaric acid, or a salt thereof, and more preferably azelaic acid, a salt of azelaic acid, glutaric acid, or a salt of glutaric acid. From the viewpoint of disposing the solder on the electrode more efficiently, the second flux is preferably pimelic acid, glutaric acid, or a salt thereof, and more preferably glutaric acid or a salt of glutaric acid. From the viewpoint of disposing the solder on the electrode more efficiently, the second flux is preferably pimelic acid or glutaric acid, and more preferably glutaric acid.

[0081] The flux is preferably a flux that releases cations when heated. The first flux is preferably a flux that releases cations when heated. The second flux is preferably a flux that releases cations when heated. Use of a flux that releases cations when heated allows the solder to be more efficiently placed on the electrodes.

[0082] The content of the flux (total flux content) in 100% by weight of the resin composition is preferably 5% by weight or more, preferably 10% by weight or more, more preferably 15% by weight or more, and preferably 30% by weight or less, more preferably 25% by weight or less. When the content of the flux is equal to or greater than the lower limit and equal to or less than the upper limit, oxide films are less likely to form on the surfaces of the solder and electrodes, and oxide films formed on the surfaces of the solder and electrodes can be more effectively removed. When the flux includes the first flux and the second flux, the content of the flux refers to the sum of the content of the first flux and the content of the second flux (the same applies hereinafter).

[0083] The content of the first flux in 100% by weight of the resin composition is preferably 5% by weight or more, more preferably 8% by weight or more, and even more preferably 10% by weight or more, and is preferably 25% by weight or less, more preferably 20% by weight or less, and even more preferably 15% by weight or less. When the content of the first flux is equal to or more than the lower limit and equal to or less than the upper limit, solder cohesion can be improved.

[0084] The content of the second flux in 100% by weight of the resin composition is preferably 1% by weight or more, more preferably 2% by weight or more, and even more preferably 5% by weight or more, and is preferably 25% by weight or less, more preferably 20% by weight or less, and even more preferably 15% by weight or less. When the content of the second flux is equal to or more than the lower limit and equal to or less than the upper limit, the coatability and screen printability of the resin composition can be improved.

[0085] The content of the first flux in 100% by weight of the flux is preferably 40% by weight or more, more preferably 50% by weight or more, even more preferably 60% by weight or more, and is preferably 100% by weight or less, more preferably less than 100% by weight, even more preferably 90% by weight or less, particularly preferably 80% by weight or less, and most preferably 70% by weight or less. When the content of the first flux is equal to or more than the above lower limit and equal to or less than the above upper limit, the coatability and screen printability of the resin composition can be improved.

[0086] The content of the flux (content of the total flux) relative to 100 parts by weight of the thixotropic agent is preferably 100 parts by weight or more, more preferably 150 parts by weight or more, even more preferably 200 parts by weight or more, and is preferably 500 parts by weight or less, more preferably 400 parts by weight or less, and even more preferably 300 parts by weight or less. When the content of the flux is equal to or more than the above lower limit and equal to or less than the above upper limit, the coatability and screen printability of the resin composition can be improved.

[0087] The content of the first flux relative to 100 parts by weight of the thixotropic agent is preferably 10 parts by weight or more, more preferably 20 parts by weight or more, even more preferably 40 parts by weight or more, even more preferably 100 parts by weight or more, particularly preferably 150 parts by weight or more, and most preferably 200 parts by weight or more, and is preferably 500 parts by weight or less, more preferably 400 parts by weight or less, and even more preferably 300 parts by weight or less. When the content of the first flux is not less than the above lower limit and not more than the above upper limit, the coatability and screen printability of the resin composition can be improved.

[0088] The content of the second flux relative to 100 parts by weight of the thixotropic agent is preferably 10 parts by weight or more, more preferably 20 parts by weight or more, and even more preferably 40 parts by weight or more, and is preferably 100 parts by weight or less, more preferably 80 parts by weight or less, and even more preferably 60 parts by weight or less. When the content of the second flux is equal to or more than the above lower limit and equal to or less than the above upper limit, the coatability and screen printability of the resin composition can be improved.

[0089] (Thixotropic Agent) The resin composition contains a thixotropic agent that is liquid at 25°C.

[0090] Examples of the thixotropic agent include ethylene glycol, diethylene glycol, 2-phenylethanol, 1,3-propanediol, glycerin, etc. The thixotropic agent may be used alone or in combination of two or more.

[0091] From the viewpoint of improving coatability and screen printability, the thixotropic agent preferably contains a polar compound, and more preferably contains a compound having a hydroxyl group or a carboxyl group. From the viewpoint of improving coatability and screen printability, the thixotropic agent preferably contains ethylene glycol, diethylene glycol, 2-phenylethanol, 1,3-propanediol, or glycerin, and more preferably contains ethylene glycol, 1,3-propanediol, or glycerin. From the viewpoint of improving coatability and screen printability, it is particularly preferable that the thixotropic agent contains glycerin.

[0092] From the viewpoint of improving the coatability and screen printability of the resin composition, it is preferable that the second flux contains azelaic acid, a salt of azelaic acid, glutaric acid or a salt of glutaric acid, and that the thixotropic agent contains glycerin or 1,3-propanediol. From the viewpoint of improving the coatability and screen printability of the resin composition, it is preferable that the second flux is azelaic acid, a salt of azelaic acid, glutaric acid or a salt of glutaric acid, and that the thixotropic agent is glycerin or 1,3-propanediol. From the viewpoint of improving the coatability and screen printability of the resin composition, it is preferable that the second flux is glutaric acid or a salt of glutaric acid, and that the thixotropic agent contains glycerin. From the viewpoint of improving the coatability and screen printability of the resin composition, it is preferable that the second flux is glutaric acid or a salt of glutaric acid, and that the thixotropic agent is glycerin. From the viewpoint of improving the coatability and screen printability of the resin composition, it is preferable that the second flux is glutaric acid and the thixotropic agent is glycerin.

[0093] From the viewpoint of improving the coatability and screen printability of the resin composition, it is particularly preferable that the resin composition contains azelaic acid, azelaic acid salt, glutaric acid or a glutaric acid salt, and glycerin or 1,3-propanediol, with azelaic acid, azelaic acid salt, glutaric acid or a glutaric acid salt being dissolved in glycerin or 1,3-propanediol. From the viewpoint of improving the coatability and screen printability of the resin composition, it is particularly preferable that the resin composition contains glutaric acid or a glutaric acid salt and glycerin, with glutaric acid or a glutaric acid salt being dissolved in glycerin. From the viewpoint of improving the coatability and screen printability of the resin composition, it is particularly preferable that the resin composition contains glutaric acid and glycerin, with glutaric acid being dissolved in glycerin.

[0094] The hydrogen bond term δH in the Hansen solubility parameter of the thixotropic agent is preferably 10 MPa １／２ More preferably, 12 MPa or more １／２ More preferably, 14 MPa or more １／２ More preferably, 16 MPa or more １／２ When the hydrogen bond term δH in the Hansen solubility parameter of the thixotropic agent is equal to or greater than the lower limit, the coating property and screen printability of the resin composition can be improved. The upper limit of the hydrogen bond term δH in the Hansen solubility parameter of the thixotropic agent is not particularly limited. The hydrogen bond term δH in the Hansen solubility parameter of the thixotropic agent is 100 MPa or less. １／２ It may be 50 MPa or less, １／２ It may be the following:

[0095] The hydrogen bond term δH in the Hansen solubility parameters of the thixotropic agent can be easily estimated, for example, by using computer software "Hansen Solubility Parameters in Practice (HSPiP)."

[0096] The content of the thixotropic agent in 100% by weight of the resin composition is preferably 1% by weight or more, more preferably 2% by weight or more, even more preferably 3% by weight or more, and is preferably 20% by weight or less, more preferably 15% by weight or less, even more preferably 10% by weight or less. When the content of the thixotropic agent is equal to or more than the above lower limit and equal to or less than the above upper limit, the coatability and screen printability of the resin composition can be improved.

[0097] The content of the glycerin in 100% by weight of the resin composition is preferably 1% by weight or more, more preferably 2% by weight or more, even more preferably 3% by weight or more, and is preferably 20% by weight or less, more preferably 15% by weight or less, even more preferably 10% by weight or less. When the content of the glycerin is equal to or more than the above lower limit and equal to or less than the above upper limit, the coatability and screen printability of the resin composition can be improved.

[0098] (Solder particles) The resin composition contains solder particles. The solder particles are formed of solder at both the center and the outer surface. The solder particles are particles in which both the center and the outer surface are solder. If conductive particles comprising base particles formed of a material other than solder and solder portions arranged on the surface of the base particles are used instead of the solder particles, the conductive particles are less likely to gather on the electrode. Furthermore, since the conductive particles have low solder bonding between the conductive particles, the conductive particles that have moved onto the electrode tend to easily move outside the electrode.

[0099] The solder is preferably a metal having a melting point of 450°C or less (low-melting-point metal). The solder particles are preferably metal particles having a melting point of 450°C or less (low-melting-point metal particles). The low-melting-point metal particles are particles containing a low-melting-point metal. The low-melting-point metal refers to a metal having a melting point of 450°C or less. The melting point of the low-melting-point metal is preferably 300°C or less, more preferably 220°C or less, and even more preferably 190°C or less.

[0100] The melting point of the solder particles is preferably 100° C. or higher, more preferably 105° C. or higher, and preferably 250° C. or lower, more preferably 245° C. or lower. When the melting point of the solder particles is equal to or higher than the lower limit and equal to or lower than the upper limit, the cohesion of the solder during conductive connection can be more effectively improved. When the melting point of the solder particles is equal to or higher than the lower limit and equal to or lower than the upper limit, when electrodes are electrically connected, the conductivity reliability can be more effectively improved and the insulation reliability can be more effectively improved.

[0101] The melting point of the solder particles can be determined by differential scanning calorimetry (DSC). Examples of DSC devices include the "EXSTAR DSC7020" manufactured by SII Corporation.

[0102] The solder particles preferably contain 90 wt% or more of solder in 100 wt% of the solder particles. The solder particles also preferably contain tin. The tin content in 100 wt% of the metals contained in the solder particles is preferably 30 wt% or more, more preferably 40 wt% or more, even more preferably 70 wt% or more, and particularly preferably 90 wt% or more. When the tin content in the solder particles is equal to or greater than the lower limit, the connection reliability between the solder portion and the electrode can be more effectively improved.

[0103] The tin content can be measured using a high-frequency inductively coupled plasma optical emission spectrometer ("ICP-AES" manufactured by Horiba, Ltd.) or a fluorescent X-ray analyzer ("EDX-800HS" manufactured by Shimadzu Corporation).

[0104] By using the solder particles, the solder melts and bonds to the electrodes, and the solder portion establishes electrical continuity between the electrodes. For example, the solder portion and the electrodes are more likely to have surface contact rather than point contact, which reduces connection resistance. Furthermore, the use of the solder particles increases the bonding strength between the solder portion and the electrodes, making it even less likely for the solder portion and the electrodes to peel off, thereby more effectively improving the electrical continuity reliability and connection reliability.

[0105] The low-melting point metal constituting the solder particles is not particularly limited. The low-melting point metal is preferably tin or an alloy containing tin. Examples of such alloys include a tin-silver alloy, a tin-copper alloy, a tin-silver-copper alloy, a tin-bismuth alloy, a tin-zinc alloy, and a tin-indium alloy. Because of their excellent wettability with respect to electrodes, the low-melting point metal is preferably tin, a tin-silver alloy, a tin-silver-copper alloy, a tin-bismuth alloy, or a tin-indium alloy. More preferably, the low-melting point metal is a tin-bismuth alloy or a tin-indium alloy.

[0106] The solder particles are preferably filler metals having a liquidus temperature of 450°C or less based on JIS Z3001: Welding Terminology. Examples of the composition of the solder particles include metal compositions containing zinc, gold, silver, lead, copper, tin, bismuth, indium, etc. The solder particles preferably do not contain lead, and preferably contain tin and indium, or tin and bismuth.

[0107] In order to more effectively increase the bond strength between the solder part and the electrode, the solder particles may contain metals such as nickel, copper, antimony, aluminum, zinc, iron, gold, titanium, phosphorus, germanium, tellurium, cobalt, bismuth, manganese, chromium, molybdenum, and palladium. Furthermore, from the viewpoint of even more effectively increasing the bond strength between the solder part and the electrode, the solder particles preferably contain nickel, copper, antimony, aluminum, or zinc. From the viewpoint of even more effectively increasing the bond strength between the solder part and the electrode, the content of these metals for increasing the bond strength is preferably 0.0001 wt % or more, and preferably 1 wt % or less, based on 100 wt % of the metals contained in the solder particles.

[0108] The average particle diameter of the solder particles is preferably 0.01 μm or more, more preferably 0.03 μm or more. When the average particle diameter of the solder particles is equal to or greater than the lower limit, the solder can be more efficiently disposed on the electrode. The average particle diameter of the solder particles may be 10 μm or less, 5 μm or less, or 3 μm or less. The range of the average particle diameter of the solder particles can be set by appropriately selecting the lower limit and the upper limit.

[0109] The average particle diameter of the solder particles is the number average particle diameter. The average particle diameter of the solder particles can be determined, for example, by observing 50 random solder particles with an electron microscope or an optical microscope and calculating the average particle diameter of each solder particle, or by performing laser diffraction particle size distribution measurement. In observation with an electron microscope or an optical microscope, the particle diameter of each solder particle is determined as the particle diameter in equivalent circle diameter. In observation with an electron microscope or an optical microscope, the average particle diameter of 50 random solder particles in equivalent circle diameter is approximately equal to the average particle diameter in equivalent sphere diameter. In laser diffraction particle size distribution measurement, the particle diameter of each solder particle is determined as the particle diameter in equivalent sphere diameter. The average particle diameter of the solder particles is preferably calculated by laser diffraction particle size distribution measurement.

[0110] The coefficient of variation (CV value) of the particle diameter of the solder particles is preferably 5% or more, more preferably 10% or more, and preferably 40% or less, more preferably 30% or less. When the coefficient of variation of the particle diameter of the solder particles is equal to or greater than the lower limit and equal to or less than the upper limit, the solder can be arranged on the electrode more efficiently. However, the CV value of the particle diameter of the solder particles may be less than 5%.

[0111] The coefficient of variation (CV value) can be measured as follows.

[0112] CV value (%) = (ρ / Dn) × 100 ρ: Standard deviation of solder particle diameter Dn: Average value of solder particle diameter

[0113] The shape of the solder particles is not particularly limited, and may be spherical, may be a shape other than spherical, or may be flat.

[0114] The content of the solder particles in 100% by weight of the resin composition is preferably 1% by weight or more, more preferably 2% by weight or more, even more preferably 10% by weight or more, particularly preferably 20% by weight or more, and most preferably 30% by weight or more, and is preferably 80% by weight or less, more preferably 60% by weight or less, and even more preferably 50% by weight or less. When the content of the solder particles is equal to or greater than the lower limit and equal to or less than the upper limit, the solder can be more efficiently arranged on the electrodes, making it easy to arrange a large amount of solder between the electrodes, and the electrical conductivity reliability can be more effectively improved. From the viewpoint of more effectively improving the electrical conductivity reliability, a larger content of the solder particles is preferable.

[0115] (Other Components) The resin composition may contain various additives, as needed, such as a filler, an extender, a softener, a plasticizer, a thickener, a leveling agent, a polymerization catalyst, a curing catalyst, a colorant, an antioxidant, a heat stabilizer, a light stabilizer, an ultraviolet absorber, a lubricant, an antistatic agent, and a flame retardant.

[0116] (Connection structure and method for manufacturing connection structure) The connection structure according to the present invention comprises a first connection target member having a first electrode on its surface, a second connection target member having a second electrode on its surface, and a connection portion connecting the first connection target member and the second connection target member. In the connection structure according to the present invention, the material of the connection portion is the resin composition described above. In the connection structure according to the present invention, the first electrode and the second electrode are electrically connected by a solder portion in the connection portion.

[0117] The connection structure according to the present invention uses a specific resin composition, which makes it easier for solder to collect between the first electrode and the second electrode, allowing the solder to be efficiently placed on the electrodes (lines). Furthermore, some of the solder is less likely to be placed in areas (spaces) where no electrodes are formed, significantly reducing the amount of solder placed in areas where no electrodes are formed. This improves the reliability of electrical continuity between the first electrode and the second electrode. Furthermore, it is possible to prevent electrical connection between laterally adjacent electrodes that should not be connected, thereby improving insulation reliability.

[0118] Furthermore, in order to efficiently place the solder on the electrodes and significantly reduce the amount of solder placed in areas where no electrodes are formed, it is preferable to use a conductive paste rather than a conductive film as the resin composition.

[0119] In the connection structure, it is preferable that the first connection target member is a circuit board, and the second connection target member is a semiconductor chip.

[0120] The method for manufacturing a connection structure according to the present invention comprises the following steps: (1) a first arrangement step of using the above-described resin composition to arrange the resin composition on the surface of a first connection target component having at least one first electrode on its surface; (2) a second arrangement step of using a laser transfer method to move a second connection target component having at least one second electrode on its surface onto the surface of the resin composition opposite the first connection target component, and arranging the second connection target component so that the first electrode and the second electrode face each other; and (3) a connection step of heating the resin composition to a temperature equal to or higher than the melting point of the solder particles to form a connection part connecting the first connection target component and the second connection target component using the resin composition, and electrically connecting the first electrode and the second electrode via a solder part in the connection part.

[0121] The method for manufacturing a connection structure according to the present invention has the above-described configuration, and therefore can improve the capture ability of the second connection target component (semiconductor chip) that flies in at high speed by the laser transfer method.

[0122] Hereinafter, specific embodiments of the present invention will be described with reference to the drawings.

[0123] FIG. 1 is a cross-sectional view that schematically shows a connection structure obtained using a resin composition according to one embodiment of the present invention.

[0124] 1 includes a first connection target member 2, a second connection target member 3, and a connection part 4 connecting the first connection target member 2 and the second connection target member 3. The connection part 4 is formed from the resin composition described above.

[0125] In this embodiment, the resin composition includes a thermosetting component, a flux, a thixotropic agent that is liquid at 25° C., and solder particles. In this embodiment, a conductive paste is used as the resin composition.

[0126] The connection portion 4 has a solder portion 4A in which a plurality of solder particles are gathered and joined together, and a cured portion 4B in which a thermosetting component is thermally cured.

[0127] The first connection target member 2 has a plurality of first electrodes 2a on its surface (upper surface). The second connection target member 3 has a plurality of second electrodes 3a on its surface (lower surface). The first electrodes 2a and the second electrodes 3a are electrically connected by solder portions 4A. Therefore, the first connection target member 2 and the second connection target member 3 are electrically connected by solder portions 4A. In the connection portion 4, no solder is present in a region (hardened portion 4B) other than the solder portion 4A gathered between the first electrode 2a and the second electrode 3a. In a region (hardened portion 4B) other than the solder portion 4A, no solder is present apart from the solder portion 4A. In a small amount, solder may be present in a region (hardened portion 4B) other than the solder portion 4A gathered between the first electrode 2a and the second electrode 3a.

[0128] As shown in FIG. 1 , in the connection structure 1, multiple solder particles gather between the first electrode 2a and the second electrode 3a. After the multiple solder particles melt, the molten solder particles wet and spread over the surface of the electrodes, then solidify, forming a solder portion 4A. This increases the connection area between the solder portion 4A and the first electrode 2a, and between the solder portion 4A and the second electrode 3a. That is, by using solder particles, the contact area between the solder portion 4A and the first electrode 2a, and between the solder portion 4A and the second electrode 3a is increased compared to when conductive particles whose outer surface is made of a metal such as nickel, gold, or copper are used. This increases the electrical conductivity and connection reliability of the connection structure 1. The flux and thixotropic agent contained in the resin composition generally gradually deactivate when heated.

[0129] In the connection structure 1 shown in FIG. 1, all of the solder portions 4A are located in the opposing region between the first and second electrodes 2a, 3a. The modified connection structure 1X shown in FIG. 5 differs from the connection structure 1 shown in FIG. 1 only in the connection portion 4X. The connection portion 4X has a solder portion 4XA and a hardened portion 4XB. Like the connection structure 1X, most of the solder portion 4XA is located in the opposing region between the first and second electrodes 2a, 3a, and some of the solder portion 4XA may extend laterally from the opposing region between the first and second electrodes 2a, 3a. The solder portion 4XA extending laterally from the opposing region between the first and second electrodes 2a, 3a is part of the solder portion 4XA and is not solder separated from the solder portion 4XA. In this embodiment, the amount of solder separated from the solder portion can be reduced, but solder separated from the solder portion may be present in the hardened portion.

[0130] If the amount of solder particles used is reduced, it becomes easier to obtain the connection structure 1. If the amount of solder particles used is increased, it becomes easier to obtain the connection structure 1X.

[0131] The thickness of the solder portion between the first electrode and the second electrode is preferably 10 μm or more, more preferably 20 μm or more, and preferably 100 μm or less, more preferably 80 μm or less. In the first electrode and the second electrode, the solder wetted area on the surface of the electrode (the area in contact with the solder out of 100% of the exposed area of ​​the electrode) is preferably 50% or more, more preferably 60% or more, even more preferably 70% or more, and preferably 100% or less. When the solder portion in the connection satisfies the above preferred aspects, the conductivity reliability and insulation reliability can be further effectively improved.

[0132] In the connection structure 1, 1X, when the portion where the first electrode 2a and the second electrode 3a face each other is viewed in the stacking direction of the first electrode 2a, the connection portion 4, 4X, and the second electrode 3a, the solder portions 4A, 4XA in the connection portion 4, 4X are preferably arranged in 50% or more of the 100% area of ​​the portion where the first electrode 2a and the second electrode 3a face each other. When the solder portions 4A, 4XA in the connection portion 4, 4X satisfy the above-mentioned preferred aspects, the electrical conductivity reliability can be further improved.

[0133] When the opposing portion of the first electrode and the second electrode is viewed in the stacking direction of the first electrode, the connection portion, and the second electrode, the solder portion in the connection portion is preferably disposed over 50% or more of the 100% area of ​​the opposing portion of the first electrode and the second electrode. When the opposing portion of the first electrode and the second electrode is viewed in the stacking direction of the first electrode, the connection portion, and the second electrode, the solder portion in the connection portion is more preferably disposed over 60% or more of the 100% area of ​​the opposing portion of the first electrode and the second electrode. When the opposing portion of the first electrode and the second electrode is viewed in the stacking direction of the first electrode, the connection portion, and the second electrode, the solder portion in the connection portion is even more preferably disposed over 70% or more of the 100% area of ​​the opposing portion of the first electrode and the second electrode. It is particularly preferable that the solder portion in the connection portion be disposed over 80% or more of the 100% area of ​​the opposing portion of the first electrode and the second electrode when viewed in the stacking direction of the first electrode, the connection portion, and the second electrode. It is most preferable that the solder portion in the connection portion be disposed over 90% or more of the 100% area of ​​the opposing portion of the first electrode and the second electrode when viewed in the stacking direction of the first electrode, the connection portion, and the second electrode. When the solder portion in the connection portion satisfies the above-mentioned preferable aspects, the electrical connection reliability can be further improved.

[0134] When the opposing portions of the first electrode and the second electrode are viewed in a direction perpendicular to the stacking direction of the first electrode, the connection portion, and the second electrode, it is preferable that 60% or more of the solder portion in the connection portion is disposed in the opposing portion of the first electrode and the second electrode. When the opposing portions of the first electrode and the second electrode are viewed in a direction perpendicular to the stacking direction of the first electrode, the connection portion, and the second electrode, it is more preferable that 70% or more of the solder portion in the connection portion is disposed in the opposing portion of the first electrode and the second electrode. It is even more preferable that 90% or more of the solder portion in the connection portion is disposed in the opposing portion of the first electrode and the second electrode when the opposing portions of the first electrode and the second electrode are viewed in a direction perpendicular to the stacking direction of the first electrode, the connection portion, and the second electrode. When the opposing portions of the first electrode and the second electrode are viewed in a direction perpendicular to the stacking direction of the first electrode, the connection portion, and the second electrode, it is particularly preferable that 95% or more of the solder portion in the connection portion is disposed in the opposing portion of the first electrode and the second electrode. When the opposing portions of the first electrode and the second electrode are viewed in a direction perpendicular to the stacking direction of the first electrode, the connection portion, and the second electrode, it is most preferable that 99% or more of the solder portion in the connection portion is disposed in the opposing portion of the first electrode and the second electrode. When the solder portion in the connection portion satisfies the above-mentioned preferred aspects, the electrical conductivity reliability can be further improved.

[0135] Next, an example of a method for producing a connection structure 1 using a resin composition according to one embodiment of the present invention will be described with reference to Figures 2 to 4. Figures 2 to 4 are cross-sectional views for explaining each step of an example of a method for producing a connection structure using a resin composition according to one embodiment of the present invention.

[0136] First, a first connection target member (circuit board) 2 having a first electrode 2a on its surface (top surface) is prepared. Next, as shown in Fig. 2, a resin composition 11 containing a thermosetting component 11B, solder particles 11A, flux 11C, and a thixotropic agent (not shown) that is liquid at 25°C is placed on the surface of the first connection target member (circuit board) 2 (first placement step). The thermosetting component 11B contains a thermosetting compound.

[0137] A resin composition 11 is placed on the surface of a first connection target component (circuit board) 2 on which a first electrode 2a is provided. After placing the resin composition 11, solder particles 11A, flux 11C, and a thixotropic agent are placed on both the first electrode 2a (lines) and the area (space) where the first electrode 2a is not formed. The resin composition may be placed only on the surface of the first electrode.

[0138] There is no particular limitation on the method for disposing the resin composition 11. Examples of the method for disposing the resin composition 11 include application using a dispenser, screen printing, and ejection using an inkjet device.

[0139] Also, a second connection target member (semiconductor chip) 3 having second electrodes 3a on its surface (lower surface) is prepared. The second connection target member (semiconductor chip) 3 having second electrodes 3a on its surface (lower surface) is disposed on the surface of the support film 6 side of the transfer source substrate which includes a support member 5 and a support film 6. The second connection target member (semiconductor chip) 3 having second electrodes 3a on its surface (lower surface) is disposed on the surface of the support film 6.

[0140] Next, as shown in FIG. 3 , in the resin composition 11 on the surface of the first connection target member (circuit board) 2, a second connection target member (semiconductor chip) 3 is transferred by laser transfer onto the surface of the resin composition 11 opposite the first connection target member (circuit board) 2 side, and the second connection target member (semiconductor chip) 3 is placed (second placement process). The second connection target member (semiconductor chip) 3 is placed on the surface of the resin composition 11 from the second electrode 3a side. In the second placement process, a laser is irradiated from the support member 5 side of the transfer source substrate using a laser irradiation device 51, which causes the curing reaction of the curable component (resin component) in the support film 6 to proceed, significantly reducing the adhesive strength of the surface of the support film 6. As a result, the second connection target member (semiconductor chip) 3 is peeled off from the transfer source substrate (particularly the support film 6) and moved onto the surface of the resin composition 11 opposite the first connection target member (circuit board) 2 side. The second connection target member (semiconductor chip) 3 moves independently, for example, with the surface of the second connection target member (semiconductor chip) 3 not in contact with (not held by) any other member, with the first electrode 2a and the second electrode 3a facing each other.

[0141] In this embodiment, the resin composition is used, so that the capture of the second connection target member (semiconductor chip) 3 arriving at high speed by the laser transfer method can be improved in the second placement step. As a result, the arriving second connection target member (semiconductor chip) can be accurately placed in a predetermined location on the first connection target member (circuit board) (effectively suppressing misalignment during placement of the semiconductor chip).

[0142] Next, the resin composition 11 is heated to a temperature equal to or higher than the melting point of the solder particles 11A. Preferably, the resin composition 11 is heated to a temperature equal to or higher than the curing temperature of the thermosetting component 11B (thermosetting compound). During this heating, the solder particles 11A present in the area where no electrodes are formed gather between the first electrode 2a and the second electrode 3a (self-aggregation effect). When a conductive paste is used instead of a conductive film, the solder particles 11A gather more effectively between the first electrode 2a and the second electrode 3a. The solder particles 11A also melt and bond to each other. The thermosetting component 11B also thermally cures. As a result, as shown in FIG. 4 , a connection 4 connecting the first connection target component (circuit board) 2 and the second connection target component (semiconductor chip) 3 is formed from the resin composition 11. The connection part 4 is formed from the resin composition 11, the solder part 4A is formed by joining the plurality of solder particles 11A, the thermosetting component 11B is thermally cured to form the cured part 4B, and the first electrode 2a and the second electrode 3a are electrically connected by the solder part 4A in the connection part 4 (connection step). If the solder particles 11A move sufficiently, it is not necessary to maintain a constant temperature from the start of the movement of the solder particles 11A that are not located between the first electrode 2a and the second electrode 3a until the movement of the solder particles 11A between the first electrode 2a and the second electrode 3a is completed.

[0143] It is preferable not to apply pressure in the second arrangement step and the connection step. In this case, the weight of the second connection target component (semiconductor chip) 3 is added to the resin composition 11. Therefore, when the connection portion 4 is formed, the solder particles 11A gather more effectively between the first electrode 2a and the second electrode 3a. Note that if pressure is applied in at least one of the second arrangement step and the connection step, the action of the solder particles 11A to gather between the first electrode 2a and the second electrode 3a is more likely to be inhibited.

[0144] Furthermore, in this embodiment, since no pressure is applied, even if the first connection target component (circuit board) 2 and the second connection target component (semiconductor chip) 3 are overlapped with a slight misalignment between the first electrode 2a and the second electrode 3a, the slight misalignment can be corrected to connect the first electrode 2a and the second electrode 3a (self-alignment effect). This is because the molten solder self-aggregating between the first electrode 2a and the second electrode 3a is energetically stable when the contact area between the solder and the other components of the resin composition is minimized, and a force acts to create an aligned connection structure with this minimum contact area. At this time, it is desirable that the resin composition is not cured and that the viscosity of the components of the resin composition other than the solder particles is sufficiently low at that temperature and time.

[0145] In this way, the connection structure 1 shown in Figure 1 is obtained. The second arrangement step and the connection step may be performed consecutively. After the second arrangement step, the resulting laminate of the first connection target member 2, the resin composition 11, and the second connection target member 3 may be moved to a heating section to perform the connection step. To perform the heating, the laminate may be placed on a heating member, or the laminate may be placed in a heated space.

[0146] In the second placement step, it is preferable to move the second connection target member on the surface of the resin composition opposite the first connection target member side by a laser transfer method at a speed of 1 cm / s or more, and place the second connection target member so that the first electrode and the second electrode face each other. In the second placement step, the speed at which the second connection target member is moved on the surface of the resin composition opposite the first connection target member side by the laser transfer method is preferably 5 cm / s or more, more preferably 10 cm / s or more, and even more preferably 50 cm / s or more. There is no particular upper limit to the speed at which the second connection target member is moved by the laser transfer method. In the laser transfer method in the second placement step, the second connection target member may be moved on the surface of the resin composition opposite the first connection target member side at a speed of 500 cm / s or less. In the second placement step, the range of the speed at which the second connection target member is moved by laser transfer onto the surface of the resin composition opposite the first connection target member side can be set by appropriately selecting the lower limit value and the upper limit value.

[0147] The heating temperature in the connecting step is preferably 250° C. or higher, more preferably 300° C. or higher, and preferably 450° C. or lower, more preferably 400° C. or lower, and even more preferably 350° C. or lower. When the heating temperature in the connecting step is equal to or higher than the lower limit and equal to or lower than the upper limit, the solder can be more efficiently disposed on the electrodes, and the reliability of conductivity between the upper and lower electrodes to be connected can be more effectively improved.

[0148] Heating methods for the above connection process include a method of heating the entire connection structure using a reflow furnace or oven to a temperature above the melting point of the solder and above the curing temperature of the thermosetting component, and a method of locally heating only the connection portion of the connection structure.

[0149] Examples of tools used for localized heating include a hot plate, a heat gun that applies hot air, a soldering iron, and an infrared heater.

[0150] Furthermore, when heating locally with a hot plate, it is preferable to form the top surface of the hot plate with a metal having high thermal conductivity directly below the connection part, and with a material having low thermal conductivity such as fluororesin for other areas where heating is not desirable.

[0151] The first and second connection target members are not particularly limited. Examples of the first and second connection target members include electronic components such as semiconductor chips, semiconductor packages, capacitors, and diodes, as well as electronic components such as resin films, printed circuit boards, flexible printed circuit boards, flexible flat cables, rigid-flexible boards, glass epoxy boards, and glass boards. The semiconductor chip may be an LED chip, and the semiconductor package may be an LED package. The second connection target member is preferably an electronic component. The second connection target member is preferably a semiconductor chip, more preferably an LED chip, and even more preferably a micro LED chip.

[0152] At least one of the first connection target member and the second connection target member is preferably a resin film, a flexible printed circuit board, a flexible flat cable, or a rigid-flexible substrate. The first connection target member is preferably a resin film, a flexible printed circuit board, a flexible flat cable, or a rigid-flexible substrate. Resin films, flexible printed circuit boards, flexible flat cables, and rigid-flexible substrates have the properties of being highly flexible and relatively lightweight. When a conductive film is used to connect such connection target members, solder tends to be less likely to collect on the electrodes. In contrast, by using a conductive paste, solder can be efficiently collected on the electrodes, even when a resin film, a flexible printed circuit board, a flexible flat cable, or a rigid-flexible substrate is used, thereby sufficiently improving the reliability of conduction between the electrodes.

[0153] Examples of the electrodes provided on the connection target members include metal electrodes such as gold electrodes, nickel electrodes, tin electrodes, aluminum electrodes, copper electrodes, molybdenum electrodes, silver electrodes, SUS electrodes, and tungsten electrodes. When the connection target members are flexible printed circuit boards, the electrodes are preferably gold electrodes, nickel electrodes, tin electrodes, silver electrodes, or copper electrodes. When the connection target members are glass substrates, the electrodes are preferably aluminum electrodes, copper electrodes, molybdenum electrodes, silver electrodes, or tungsten electrodes. When the electrodes are aluminum electrodes, they may be formed solely from aluminum, or may be electrodes in which an aluminum layer is laminated on the surface of a metal oxide layer. Examples of materials for the metal oxide layer include indium oxide doped with a trivalent metal element and zinc oxide doped with a trivalent metal element. Examples of the trivalent metal element include Sn, Al, and Ga.

[0154] The support member is not particularly limited, and examples of the support member include a glass substrate, a sapphire substrate, a silicone substrate, a metal substrate, and an organic substrate.

[0155] The support film is not particularly limited. Examples of the support film include a silicone resin film, an acrylic resin film, and a polyimide resin film. The support film preferably has an adhesive layer.

[0156] In the second disposing step, the integrated light amount of the irradiated laser is preferably 100 mJ / cm ２ More preferably, 150 mJ / cm ２ More preferably, 200 mJ / cm ２ or more, preferably 400 mJ / cm ２ or less, more preferably 350 mJ / cm ２ More preferably, 300 mJ / cm or less ２ When the integrated light amount of the laser irradiated in the second placement step is equal to or greater than the lower limit and equal to or less than the upper limit, the ability to capture semiconductor chips flying at high speed can be further improved.

[0157] The present invention will be specifically described below with reference to examples and comparative examples, but the present invention is not limited to the following examples.

[0158] Thermosetting component (thermosetting compound): Phenol novolac type epoxy compound ("JER152" manufactured by Mitsubishi Chemical Corporation) Bisphenol F type epoxy compound ("830-S" manufactured by DIC Corporation)

[0159] Fluxes: Benzylamine adipate (first flux (4 carbon atoms in main chain), average particle size 10 μm, melting point 180° C., prepared according to Synthesis Example 1 below) Benzylamine glutarate (second flux (3 carbon atoms in main chain), average particle size 10 μm, melting point 108° C., prepared according to Synthesis Example 2 below) Stearylamine azelaate (second flux (7 carbon atoms in main chain), average particle size 10 μm, melting point 110° C., prepared according to Synthesis Example 3 below)

[0160] Synthesis Example 1: 24 g of water as a reaction solvent and 14.612 g of adipic acid (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) were placed in a glass bottle and heated at 100°C for 10 minutes to dissolve. Then, 10.715 g of benzylamine (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) was added and stirred for approximately 5 minutes to obtain a mixed solution. The resulting mixed solution was placed in a refrigerator at 5°C to 10°C and left overnight. The precipitated crystals were separated by filtration, washed with water, and vacuum dried to obtain benzylamine adipate (average particle size 30 μm). The obtained benzylamine adipate was pulverized using a jet mill to obtain benzylamine adipate with an average particle size of 10 μm.

[0161] Synthesis Example 2: 24 g of water as a reaction solvent and 13.212 g of glutaric acid (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) were placed in a glass bottle and dissolved at room temperature until homogeneous. Then, 10.715 g of benzylamine (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) was added and stirred for approximately 5 minutes to obtain a mixed solution. The obtained mixed solution was placed in a refrigerator at 5°C to 10°C and left overnight. The precipitated crystals were separated by filtration, washed with water, and vacuum dried to obtain benzylamine glutarate. The obtained benzylamine glutarate was pulverized using a jet mill to obtain benzylamine glutarate with an average particle size of 10 μm.

[0162] Synthesis Example 3: 24 g of water as a reaction solvent and 9.411 g of azelaic acid (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) were placed in a glass bottle and heated at 100°C for 10 minutes to dissolve. Then, 13.476 g of stearylamine (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) was added and stirred for approximately 5 minutes to obtain a mixed solution. The resulting mixed solution was placed in a refrigerator at 5°C to 10°C and left overnight. The precipitated crystals were separated by filtration, washed with water, and vacuum dried to obtain stearylamine azelaate (average particle size 30 μm). The obtained stearylamine azelaate was pulverized using a jet mill to obtain benzylamine adipate having an average particle size of 10 μm.

[0163] Thixotropic agent in which flux is dissolved: Thixotropic agent in which glutaric acid is dissolved in glycerin (Nacalai Tesque's "Glycerol", glutaric acid 30% by weight, glycerin 70% by weight, hydrogen bond term δH in the Hansen solubility parameter of glycerin 14.3 MPa) １／２ )

[0164] Thixotropic agent: Ethylene glycol (manufactured by Wako Co., Ltd., liquid at 25°C, hydrogen bond term δH in Hansen solubility parameters: 12.7 MPa) １／２ 1,3-propanediol (manufactured by TCI, liquid at 25°C, hydrogen bond term in Hansen solubility parameters δH 12.9 MPa) １／２ )

[0165] Solder particles: SnAgCu solder particles (melting point 220°C, solder particles selected from "Sn96.5Ag3Cu0.5" manufactured by Mitsui Mining & Smelting Co., Ltd., average particle diameter 3 μm) SnBi solder particles (melting point 139°C, solder particles selected from "Sn42Bi58" manufactured by Mitsui Mining & Smelting Co., Ltd., average particle diameter 3 μm)

[0166] (Average particle size of flux and solder particles) The average particle size of the flux and solder particles was measured using a laser diffraction particle size distribution measuring device ("LA-920" manufactured by Horiba, Ltd.).

[0167] (Melting Points of Solder Particles and Flux) The melting points of the solder particles and flux were calculated using differential scanning calorimetry (DSC). The DSC device used was an "EXSTAR DSC7020" manufactured by SII Corporation.

[0168] (Examples 1 to 8 and Comparative Examples 1 and 2) (1) Preparation of resin composition (anisotropic conductive paste) The components shown in Tables 1 to 3 below were blended in the amounts shown in Tables 1 to 3 below to obtain resin compositions (anisotropic conductive pastes).

[0169] (2) Preparation of connection structure As a first connection target member (circuit board), a glass substrate (thickness: 0.7 mm) having a plurality of electrodes (first electrodes, copper electrodes measuring 23 μm wide × 30 μm long × 12 μm thick, with a 14 μm inter-electrode space) on its surface was prepared.

[0170] As the second connection target member (semiconductor chip), a micro LED chip (material: GaN, thickness: 0.01 mm) having multiple electrodes (second electrode: gold electrode 20 μm wide × 20 μm long × 3 μm thick, 10 μm space between electrodes) on its surface was prepared.

[0171] The resin composition (anisotropic conductive paste) immediately after preparation was applied to the upper surface of the glass substrate by screen printing to a thickness of 10 μm to form a resin composition (anisotropic conductive paste) layer. Next, a semiconductor chip was laminated on the upper surface of the resin composition (anisotropic conductive paste) layer by laser transfer so that the electrodes faced each other. From this state, the resin composition (anisotropic conductive paste) layer was heated so that the temperature reached the melting point of the solder particles 5 seconds after the start of the temperature rise. Further, the resin composition (anisotropic conductive paste) layer was heated so that the temperature reached 250 ° C. 10 seconds after the start of the temperature rise, and the resin composition (anisotropic conductive paste) layer was cured to obtain a connection structure. No pressure was applied during heating.

[0172] (Evaluation) (1) Contact angle with water at 25° C. The contact angle with water at 25° C. of the obtained resin composition was measured by the method described above.

[0173] (2) Screen Printability (Coatability) The resulting resin composition (anisotropic conductive paste) was screen printed on a glass substrate using a metal mask with openings measuring 114 μm × 60 μm and a thickness of 10 μm. The printed surface of 50 printed patterns was observed with a laser microscope immediately after printing to calculate the volume of the resin composition applied to the glass substrate, and the ratio X (%) of the volume of the resin composition applied to the glass substrate to the volume of each opening in the metal mask was calculated. The screen printability was evaluated according to the following criteria.

[0174] [Criteria for Screen Printability] ◯: Ratio X is 50% or more. ○: Ratio X is 40% or more and less than 50%. Δ: Ratio X is 30% or more and less than 40%. ×: Ratio X is less than 30%.

[0175] (3) Solder Cohesion In the resulting connection structures (20 pieces), when the portion where the first electrode and the second electrode face each other in the stacking direction of the first electrode, the connection portion, and the second electrode, the proportion of the area where the solder portion in the connection portion is arranged relative to the total area of ​​the portion where the first electrode and the second electrode face each other was evaluated. The values ​​for the 20 pieces were averaged to determine the area proportion Y. From the area proportion Y, the cohesion of the solder during conductive connection was evaluated according to the following criteria.

[0176] [Criteria for evaluating solder cohesion] ○○: The ratio Y is 70% or more. ○: The ratio Y is 60% or more and less than 70%. △: The ratio Y is 50% or more and less than 60%. ×: The ratio Y is less than 50%.

[0177] (4) Capturing Ability of Semiconductor Chips In "(2) Screen Printability," semiconductor chips were moved at a speed of 1 cm / s by laser transfer onto the surface opposite the glass substrate of the resin composition applied by screen printing onto the glass substrate, and 20 semiconductor chips were arranged so that the first electrode of the glass substrate faced the second electrode of the semiconductor chip. Of the 20 semiconductor chips, the percentage Z of the number of semiconductor chips captured at a position within ±3 μm of a predetermined position was calculated. The capturing ability of the semiconductor chips was evaluated according to the following criteria.

[0178] [Criteria for determining the capture ability of semiconductor chips] ○○: Ratio Z is 70% or more ○: Ratio Z is 50% or more but less than 70% ×: Ratio Z is less than 50%

[0179] The results are shown in Tables 1 to 3 below.

[0180]

[0181]

[0182]

[0183] DESCRIPTION OF SYMBOLS 1, 1X...Connection structure 2...First connection target member (circuit board) 2a...First electrode 3...Second connection target member (semiconductor chip) 3a...Second electrode 4, 4X...Connection portion 4A, 4XA...Solder portion 4B, 4XB...Cured portion 5...Support member (transfer origin substrate) 6...Support film (transfer origin substrate) 11...Resin composition 11A...Solder particles 11B...Thermosetting component 11C...Flux 51...Laser irradiation device

Claims

1. A resin composition comprising a thermosetting component, a flux, a thixotropic agent that is liquid at 25°C, and solder particles.

2. The resin composition according to claim 1, wherein the flux comprises a first flux having an even number of carbon atoms in its main chain and a second flux having an odd number of carbon atoms in its main chain.

3. The hydrogen bond term δH in the Hansen solubility parameter of the thixotropic agent is 10 MPa. １／２ or more, the number of carbon atoms in the main chain of the first flux is an even number of 4 or more and 14 or less, and the number of carbon atoms in the main chain of the second flux is an odd number of 3 or more and 11 or less.

4. A resin composition according to claim 2 or 3, wherein the average particle size of the first flux is 10 μm or less.

5. A resin composition according to any one of claims 2 to 4, wherein the second flux is soluble in the thixotropic agent at 25°C.

6. A resin composition according to any one of claims 2 to 5, wherein the content of the second flux is 1% by weight or more and 20% by weight or less, based on 100% by weight of the resin composition.

7. The resin composition according to any one of claims 1 to 6, wherein the thixotropic agent comprises glycerin.

8. A resin composition according to any one of claims 1 to 7, wherein the content of said flux is 5% by weight or more and 25% by weight or less, based on 100% by weight of said resin composition.

9. The resin composition according to any one of claims 1 to 8, wherein the average particle size of the solder particles is 10 μm or less.

10. A method for producing a connection structure, comprising: a first arrangement step of using the resin composition according to any one of claims 1 to 9 to arrange the resin composition on a surface of a first connection target member having at least one first electrode on its surface; a second arrangement step of moving a second connection target member having at least one second electrode on its surface onto a surface of the resin composition opposite the first connection target member by a laser transfer method, and arranging the second connection target member so that the first electrode and the second electrode face each other; and a connection step of forming a connection part connecting the first connection target member and the second connection target member from the resin composition by heating the resin composition to a temperature equal to or higher than the melting point of the solder particles, and electrically connecting the first electrode and the second electrode by a solder part in the connection part.

11. A method for manufacturing a connection structure as described in claim 10, wherein in the second placement step, the second connection target member is moved at a speed of 1 cm / s or more by laser transfer onto the surface of the resin composition opposite the first connection target member, and the second connection target member is placed so that the first electrode and the second electrode face each other.

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