Manufacturing method for electronic components with bumps

Abstract

This method for manufacturing an electronic component with a bump comprises a step in which an electrode of an electronic component is opposed to a conductive resin bump formed on a supply substrate and pressure-bonded, thereby transferring the conductive resin bump onto the electrode of the electronic component. Thus, a method for manufacturing an electronic component with a bump is provided by which contamination of the electronic component during bump formation can be suppressed.

Description

Technical Field

[0001] The present invention relates to a method for manufacturing an electronic component with bumps.

Background Art

[0002] In recent years, in the display field, a structure using LED chips with each side of 100 μm or less, called μLEDs, has been actively studied. For mounting μLEDs, a flip-chip mounting method is preferably used, in which an electrode is formed on the surface of the chip and the electrode on the substrate and the chip are directly connected, thereby minimizing the area of the wiring between the chip and the substrate. In the flip-chip mounting method, a bonding material for electrically connecting the electrode on the chip surface and the electrode on the substrate is called a bump. Bumps were generally formed mainly by solder. However, since melting due to heating occurs during formation and connection, when the electrode pitch is less than 20 μm, there is a high risk of short-circuiting of the electrodes by connecting adjacent bumps with melted solder. Therefore, in a fine structure, connection materials replacing solder are being studied as bump materials.

[0003] As a method preferably used for mounting μLEDs, a method for manufacturing a substrate with a conductive pattern has been proposed, which includes a step of forming a pattern of a composition having an organic component and conductive particles on a transfer substrate, and a step of irradiating a laser from the back side of the transfer substrate to transfer the pattern to a transfer target substrate (see, for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] While the method described in Patent Document 1 allows for the creation of conductive patterned substrates with high positional accuracy during transfer, the conductive patterns forming the bumps collide with the substrate at high speed due to laser irradiation, making the transferred conductive patterns prone to damage. This damage can lead to contamination of electronic components by the resulting conductive pattern fragments. Such contamination may, in some cases, induce short circuits due to unintended connections in surrounding circuits. Another method for forming bumps of fine structures such as μLEDs is to use a photosensitive resin composition to create the bump pattern using photolithography. However, in pattern formation using photolithography, a film of the photosensitive resin composition is formed not only in the areas where the bumps are formed, making it easy for residue of the photosensitive resin composition to accumulate on the surface of electronic components. Contamination by such residue may also, in some cases, induce short circuits due to unintended connections in surrounding circuits.

[0006] Therefore, the present invention aims to provide a method for manufacturing an electronic component with bumps that can suppress contamination of electronic components during bump formation. [Means for solving the problem]

[0007] To solve the aforementioned problems, the present invention mainly has the following configuration. (1) A method for manufacturing an electronic component with bumps, comprising the step of transferring conductive resin bumps to the electrodes of an electronic component by pressing the electrodes of the electronic component against conductive resin bumps formed on a supply substrate. (2) A method for manufacturing a bumped electronic component according to (1), wherein the electrode height of the electronic component is 0.5 to 10.0 μm. (3) The area of ​​each conductive resin bump formed on the supply substrate is 5 to 600 μm². 2 A method for manufacturing an electronic component with bumps as described in (1) or (2). (4) A method for manufacturing an electronic component with bumps according to any one of (1) to (3), wherein the area of ​​each conductive resin bump formed on the supply substrate is 0.3 to 1.8 times the area of ​​each electrode of the electronic component. (5) A method for manufacturing a bumped electronic component according to any one of (1) to (4), wherein the height difference per electrode of the electronic component is 0.5 to 5.0 μm. (6) A method for manufacturing an electronic component with bumps according to any one of (1) to (5), wherein the pressure temperature when the electrodes of the electronic component are pressed against the conductive resin bump is 40°C or more and 180°C or less. (7) A method for manufacturing a bumped electronic component according to any one of (1) to (6), wherein a plurality of the electronic components are gripped on a gripping substrate. (8) A method for manufacturing an electronic component with bumps according to any one of (1) to (7), wherein the number of conductive resin bumps formed on the supply substrate is greater than the number of conductive resin bumps transferred to the electronic component by one cycle of crimping. [Effects of the Invention]

[0008] According to the method for manufacturing electronic components of the present invention, bumps can be formed while suppressing contamination of the electronic components. [Brief explanation of the drawing]

[0009] [Figure 1] This is a schematic diagram illustrating an example of a method for manufacturing an electronic component with bumps according to the present invention. [Figure 2] This is a schematic diagram showing the difference in electrode height and the height of each electrode in the present invention. [Figure 3] This is a schematic diagram illustrating the method for evaluating the bump failure rate in the embodiment. [Figure 4] This is a schematic diagram showing the process of forming conductive resin bumps in Comparative Example 1. [Figure 5] This is a schematic diagram showing the transfer process of conductive resin bumps in Comparative Examples 2 and 3. [Modes for carrying out the invention]

[0010] The present invention provides a method for manufacturing bumped electronic components, which includes a step of transferring conductive resin bumps to the electrodes of an electronic component by pressing the electrodes of the electronic component against conductive resin bumps formed on a supply substrate. As mentioned above, when transferring conductive resin bumps that have been previously formed on a transfer substrate to a substrate to be transferred using a laser, or when forming bumps on an electronic component using a photolithography method with a photosensitive resin composition, contamination by conductive resin bump fragments or the photosensitive resin composition becomes a problem. In contrast, the present invention transfers conductive resin bumps by pressing, thus suppressing contamination due to residue and bump destruction. Furthermore, it is possible to form conductive resin bumps with higher resolution compared to technologies that form conductive resin bumps using dispensers or inkjet printers.

[0011] The following describes in detail embodiments of the method for manufacturing bumped electronic components according to the present invention with reference to the drawings. Note that the drawings are schematic. Furthermore, the present invention is not limited to the embodiments described below.

[0012] Figure 1 is a schematic diagram showing an example of an embodiment of the method for manufacturing bumped electronic components of the present invention. First, as shown in (a), conductive resin bumps 2 formed on a supply substrate 1 and a plurality of electronic components 4 held on a gripping substrate 5 are arranged so that the conductive resin bumps 2 and the electrodes 3 of the electronic components 4 face each other. Next, as shown in (b), the electrodes 3 of the electronic components 4 are pressed against the conductive resin bumps 2, and then, as shown in (c), the supply substrate 1 and the gripping substrate 5 are separated, thereby transferring the conductive resin bumps 2 onto the electrodes 3.

[0013] Examples of the crimping device include a flip chip bonder, a diaphragm laminator, and the like. As the crimping method, thermocompression bonding is preferable, and the crimping temperature is preferably 40°C or higher and 180°C or lower. By setting the crimping temperature to 40°C or higher, the storage elastic modulus of the conductive bump can be reduced, and the adhesion to the electrode of the electronic component can be improved. On the other hand, by setting the crimping temperature to 180°C or lower, the thermal expansion and thermal contraction of the supply substrate and the electronic component can be suppressed, and the positional accuracy of transfer can be further enhanced.

[0014] The crimping temperature may be different between the conductive resin bump and the electronic component. For example, the temperature of the member (lower side plate) on which the supply substrate is placed is preferably 20°C or higher and 150°C or lower. By setting the temperature of the lower side plate to 20°C or higher, even when the temperature of the upper side plate described later is low, the conductive bump can be more easily transferred. The temperature of the lower side plate is more preferably 30°C or higher. On the other hand, by setting the temperature of the lower side plate to 150°C or lower, deterioration due to the thermal reaction of the conductive resin bump can be suppressed. The temperature of the lower side plate is more preferably 100°C or lower. The temperature of the member (upper side plate) that holds the holding substrate or the electronic component is preferably 20°C or higher and 180°C or lower.By setting the temperature of the upper side plate to 20°C or higher, the conductive bump can be more easily transferred. On the other hand, by setting the temperature of the upper side plate to 180°C or lower, the standby time associated with the temperature rise and fall of the upper side plate can be shortened, and productivity can be improved. The temperature of the upper side plate is more preferably 100°C or lower. It is more preferable that at least one of the temperatures of the upper side plate and the lower side plate is in the temperature range of 40°C or higher and 180°C or lower.

[0015] The pressure in crimping is preferably 0.1 MPa or higher and 10 MPa or lower, which can further suppress the breakage of the conductive resin bump due to crimping and further suppress the contamination of the electronic component. The pressure is the value obtained by dividing the load applied by the device by the total contact area. The total contact area refers to the product of the area per one of the smaller of the conductive resin bumps transferred during crimping and the electrode of the electronic component in contact with it and the number of electrodes.

[0016] The pressure bonding time is preferably 0.1 second or more and 20 seconds or less, and productivity can be improved.

[0017] Hereinafter, the materials used in the method for manufacturing the bump-mounted electronic component of the present invention will be described.

[0018] <Supply substrate> The supply substrate in the present invention is a substrate that holds conductive resin bumps for supplying conductive resin bumps to be transferred to the electrodes of electronic components. Examples of the material constituting the supply substrate include organic materials, inorganic materials such as glass and silicon, and the like. Among these, an inorganic material with high in-plane flatness is preferable in order to improve the parallelism within the surface of the supply substrate during pressure bonding. As the supply substrate composed of an inorganic material, for example, a glass substrate is preferable.

[0019] The surface of the supply substrate may be subjected to a release treatment, which can make it easier to transfer the conductive resin bumps. Further, the surface of the supply substrate may further have a flexible layer, which can absorb the inclination of the supply substrate when transferring the conductive resin bumps and make it easier to transfer the conductive resin bumps.

[0020] The number of conductive resin bumps formed on the supply substrate (hereinafter referred to as the number of formed bumps) is preferably larger than the number of conductive resin bumps transferred to the electronic component by one cycle of pressure bonding (hereinafter referred to as the number of used bumps). By making the number of formed bumps larger than the number of used bumps, multiple transfers can be performed using a single supply substrate, and productivity can be improved. The number of formed bumps is more preferably 2 times or more the number of used bumps. Here, the number of used bumps in the case of performing multiple transfers using a single supply substrate refers to the smallest number among the number of used bumps per transfer in multiple transfers, and the number of formed bumps refers to the total number of bumps formed on the supply substrate before transfer.

[0021] <Conductive resin bump> The conductive resin bump has conductivity and functions to electrically connect the conductive resin bump to the electrode in contact with it. Here, "having conductivity" means that it is sufficient for the electronic component to be conductive when it ultimately functions, and conductivity may be manifested by a specific process. For example, conductivity may be manifested by heating or pressure when transferring to the electronic component. It is preferable that the electrical resistivity of the conductive resin bump is 1 Ω·m or less. The electrical resistivity ρ of the conductive resin bump can be calculated by ρ = R × S / L, where S is the cross-sectional area of ​​the smaller electrode among the two electrodes that contact the conductive resin bump and form a circuit, L is the straight-line distance from the surface of the electrode to the surface of the other electrode, and R is the electrical resistance of the conductive resin bump. If L is not constant in the plane due to irregularities on the electrode surface, etc., the cross-sectional area S corresponding to each region with different L can be set, and the parallel circuit of these regions can be assumed to form the electrical resistance R, and ρ can be calculated as ρ = R(S1 / L1 + S2 / L2 + ...).

[0022] The conductive resin bump may contain a conductive resin or conductive particles. In the latter case, electrical connection may be obtained by dispersing the conductive particles in the resin and bringing the conductive particles into continuous contact, or by linking the conductive particles by sintering. Examples of conductive particles include particles of silver, gold, copper, platinum, lead, tin, nickel, aluminum, tungsten, molybdenum, chromium, titanium, indium, magnesium, zinc, iron, and alloys thereof, carbon black particles, conductive oxide particles such as indium tin oxide (ITO) and indium zinc oxide (IZO), etc. Two or more of these may be included. Furthermore, the materials listed above may form a structure that covers the surface of particles formed by resin or inorganic material. In the present invention, it is preferable to include a photosensitive organic component and conductive particles. Examples of such organic components include binder resins, compounds having photopolymerizable groups, and photopolymerization initiators. Furthermore, curing catalysts and other additives may also be included.

[0023] Examples of binder resins include acrylic resins, phenoxy resins, polyester resins, polyurethane resins, polyimide resins, siloxane-modified polyimide resins, polybenzoxazole resins, polyamide resins, polycarbonate resins, and polybutadiene. Two or more of these may be included. The binder resin preferably has carboxyl groups, which can improve developability.

[0024] A compound having a photopolymerizable group refers to a monomer or oligomer that has a photopolymerizable group. Examples of photopolymerizable groups include acryloyl groups and methacryloyl groups. Examples of photopolymerizable compounds include difunctional monomers such as ethylene glycol diacrylate, diethylene glycol diacrylate, triethylene glycol diacrylate, 1,4-butanediol diacrylate, glycerin diacrylate, tripropylene glycol diacrylate, ethoxylated (4) bisphenol A diacrylate, ethoxylated (10) bisphenol A diacrylate, and acrylic acid adducts of ethylene glycol diglycidyl ether; trifunctional monomers such as pentaerythritol triacrylate, pentaerythritol triacrylate, trimethylolpropane triacrylate, trimethylolpropane ethoxytriacrylate, and glycerin propoxytriacrylate; tetrafunctional monomers such as dipentaerythritol hexaacrylate, pentaerythritol tetraacrylate, pentaerythritol ethoxytetraacrylate, and ditrimethylolpropane tetraacrylate, as well as compounds in which the acrylic groups of these monomers are substituted with methacrylic groups. Two or more of these may be included.

[0025] Examples of photopolymerization initiators include benzophenone derivatives, acetophenone derivatives, thioxanthone derivatives, benzyl derivatives, benzoin derivatives, oxime compounds, α-hydroxyketone compounds, α-aminoalkylphenone compounds, phosphine oxide compounds, anthrone compounds, and anthraquinone compounds. Two or more of these may be included.

[0026] The area of ​​each conductive resin bump is 5 μm². 2 The above is preferable, as it ensures sufficient adhesion during pressing, making transfer easier. The area of ​​each conductive resin bump is 40 μm². 2 The above is more preferable. On the other hand, the area of ​​each conductive resin bump is 600 μm². 2 The following is preferable, as it reduces the load required to peel the material from the supply substrate and makes transfer easier. The area is 400 μm². 2 The following are preferable.

[0027] Furthermore, the area of ​​each conductive resin bump is preferably 0.3 times or more the area of ​​each electrode of the electronic component being transferred, which allows for sufficient electrical connection with the electronic component. On the other hand, the area of ​​each conductive resin bump is preferably 1.8 times or less the area of ​​each electrode of the electronic component being transferred, and more preferably 1.5 times or less, which further suppresses damage to the bumps when transferring the conductive resin bumps from the supply substrate and further suppresses contamination of the electronic component.

[0028] Here, the area of ​​a single conductive resin bump is the area of ​​the projection of a single conductive resin bump onto a surface parallel to the supply substrate on which the conductive resin bump is formed. This can be determined by measuring the area of ​​100 randomly selected conductive resin bumps using an optical microscope or scanning electron microscope (SEM) and calculating the median value.

[0029] The thickness of the conductive resin bump is preferably 0.5 μm or more, which can suppress variations in electrical resistance. It can also improve the adhesion between the conductive resin bump and the electrode to which it is connected. Furthermore, it can be made easier to transfer. On the other hand, the thickness of the conductive resin bump is preferably 5 μm or less, and more preferably 3 μm or less.

[0030] The conductive resin bumps are preferably adhesive, and it is preferable that their glass transition temperature is 100°C or lower when formed on the supply substrate.

[0031] Methods for forming conductive resin bumps include, for example, applying a paste, which is made by kneading the components constituting the conductive resin bumps and, if necessary, a solvent, onto a supply substrate. If the paste is photosensitive, the conductive resin bumps can be formed by photolithography. More specifically, it is preferable to have the steps of applying the paste onto the supply substrate to form a dry film, and exposing and developing the dry film.

[0032] Methods for applying paste include, for example, rotational coating using a spinner, spray coating, roll coating, screen printing, blade coater, die coater, calender coater, meniscus coater, and bar coater.

[0033] Drying methods include, for example, heat drying using an oven, hot plate, or infrared, as well as vacuum drying. The drying temperature is preferably 50 to 180°C, and the drying time is preferably 1 minute to several hours.

[0034] The thickness of the dried film can be appropriately selected according to the desired thickness of the conductive resin bump. A dried film thickness of 0.5 μm or more is preferred. On the other hand, a dried film thickness of 5 μm or less is preferred, as this allows light to reach deeper into the dried film during exposure, suppressing peeling during development. A dried film thickness of 3 μm or less is more preferred. The thickness of the dried film of the paste can be measured using a stylus-type step meter. More specifically, the thickness is measured at three randomly selected locations using a stylus-type step meter (measuring length: 1 mm, scanning speed: 0.3 mm / sec), and the average value is calculated.

[0035] Next, the dried film is exposed to light. Examples of exposure light sources include high-pressure mercury lamps, ultra-high-pressure mercury lamps, and LEDs that emit i-lines (wavelength 365 nm), h-lines (wavelength 405 nm), and g-lines (wavelength 436 nm). Examples of exposure methods include vacuum adsorption exposure, proxy exposure, projection exposure, and direct writing exposure.

[0036] Next, the exposed dried film is developed. Examples of development methods include spraying the developer onto the dried film surface while the supply substrate with the exposed dried film is stationary or rotated, immersing the supply substrate with the exposed dried film in the developer, or applying ultrasonic waves while the supply substrate with the exposed dried film is immersed in the developer.

[0037] An alkaline aqueous solution is preferred as the developing solution. After development, rinsing with a rinsing solution may be performed. Examples of rinsing solutions include water, or an aqueous solution of water to which alcohols such as ethanol or isopropyl alcohol, or esters such as ethyl lactate or propylene glycol monomethyl ether acetate have been added.

[0038] <Electronic Components> In this invention, an electronic component refers to any element that is mounted on a substrate with electrical connections and functions based on the input or output of an electrical signal, or both. An electronic component has at least one electrode. Examples of electronic components include semiconductor chips, interposers, and optical elements. Among these, the present invention is preferably applicable to optical elements. Examples of optical elements include LEDs, photoresistors, phototransistors, photodiodes, micromirrors, and solar cells. In particular, μLEDs with sides of 100 μm or less are preferred because productivity can be increased by using the manufacturing method of the present invention.

[0039] <Electrode> Electrodes are generally composed of materials such as metals or semiconductors.

[0040] The ratio of the electrode area to the total surface area of ​​the surface having electrodes of an electronic component (hereinafter sometimes referred to as the "electrode area ratio") is preferably 0.1 to 0.8. By setting the electrode area ratio to 0.1 or higher, sufficient current can be obtained to operate the electronic component. A more preferable electrode area ratio is 0.2 or higher. On the other hand, by setting the electrode area ratio to 0.8 or lower, short circuits between electrodes can be suppressed. A more preferable electrode area ratio for an electronic component is 0.7 or lower.

[0041] Here, the area of ​​the surface of an electronic component having electrodes and the area of ​​the electrodes are the areas of the projection onto a plane parallel to the substrate on which the electronic component is mounted. The area of ​​the surface of an electronic component having electrodes and the area of ​​the electrodes can be measured by physically separating the electronic component from the substrate and then observing them using an optical microscope or a scanning electron microscope (SEM).

[0042] The electrode height is preferably 0.5 μm or more. Even if the conductive resin bump deforms during crimping, this further suppresses the adhesion of the conductive resin bump to the surface of the electronic component, thereby further suppressing contamination of the electronic component. On the other hand, the electrode height is preferably 10.0 μm or less. This suppresses variations in electrode height and improves processing accuracy.

[0043] The electrodes may have structures of different heights within the electrode surface (hereinafter sometimes referred to as "height differences"), which increases the contact area between the conductive resin bump and the electrode during pressing, improving adhesion and making transfer easier. The height difference per electrode is preferably 0.5 μm or more. On the other hand, the height difference per electrode is preferably 5.0 μm or less, which can suppress voids between the conductive resin bump and the electrode. The height difference per electrode is preferably smaller than the electrode height. Methods for forming height differences within the electrode surface include, for example, forming an uneven shape on the electronic component at the position where the electrode is to be formed by etching or the like, and then forming the electrode on top of that by plating or the like, thereby reflecting the uneven shape on the electronic component on the electrode surface, or applying etching or other processing to the formed electrode.

[0044] Here, the method for measuring the electrode height of each part and the difference in height per electrode will be explained with reference to Figure 2. Electrode height B is the height of the point on the electrode furthest from the surface of the electronic component (hereinafter referred to as the vertex) when observed from a plane perpendicular to the electronic component on which the electrode is formed (hereinafter referred to as the perpendicular plane), and is the length of the perpendicular line drawn from the horizontal plane passing through the electrode vertex to the reference plane A. Here, the reference plane A of the electronic component is the horizontal plane passing through the reference point, where the position on the electronic component surface excluding the electrodes results in the longest perpendicular line when drawn from the horizontal plane passing through the electrode vertex to the electronic component. However, the part where the angle between the tangent to the electronic component surface and the horizontal plane is 70 to 110° is not considered a reference point. If an electronic component has multiple electrodes, the largest of those electrode heights is taken as electrode height B.

[0045] If there is a difference in height within the electrode surface, the height difference C for each electrode is the largest difference between the height of each evaluation point relative to the reference plane A and the height of the vertex. An evaluation point is a point on the electrode surface excluding the area where the angle D between the tangent to the electrode surface and the reference plane is between 70 and 110°, and is measured in the same way as the electrode height.

[0046] <Gripping board> In this invention, the gripping substrate is a substrate for gripping electronic components. Preferably, multiple electronic components are gripped on the gripping substrate. A method for gripping the electronic components may be, for example, a method using an adhesive. Examples of materials constituting the gripping substrate are those exemplified for the supply substrate. In order to increase the parallelism with the supply substrate, an inorganic material with high in-plane flatness is preferred, for example, a silicon substrate. Furthermore, the surface of the gripping substrate may have a flexible layer to absorb the tilt of the conductive resin bumps when transferring them, making it easier to transfer the conductive resin bumps. A flexible layer may also be provided to absorb the tilt of the member when transferring the conductive resin bumps. [Examples]

[0047] The present invention will be described in detail below with reference to examples and comparative examples, but the embodiments of the present invention are not limited thereto.

[0048] The materials used in the examples and comparative examples are as follows:

[0049] [Photosensitive component] (Synthesis example) Acrylic copolymer (A) 150 g of diethylene glycol monobutyl ether (hereinafter, "DGME") was charged into a reaction vessel under a nitrogen atmosphere, and the temperature was raised to 80°C using an oil bath. A mixture consisting of 20 g of ethyl acrylate (hereinafter, "EA"), 40 g of 2-ethylhexyl methacrylate (hereinafter, "2-EHMA"), 20 g of n-butyl acrylate (hereinafter, "BA"), 15 g of N-methylolacrylamide (hereinafter, "MAA"), 0.8 g of 2,2'-azobisisobutyronitrile, and 10 g of DGME was added dropwise over 1 hour. After the addition was complete, the polymerization reaction was carried out by heating at 80°C for 6 hours. Subsequently, 1 g of hydroquinone monomethyl ether was added to stop the polymerization reaction. Subsequently, a mixture consisting of 5 g of glycidyl methacrylate (hereinafter, "GMA"), 1 g of triethylbenzylammonium chloride, and 10 g of DGME was added dropwise over 0.5 hours. After the dropwise addition was complete, the mixture was heated for a further 2 hours to carry out the addition reaction. The resulting reaction solution was purified with methanol to remove unreacted impurities, and then vacuum-dried for 24 hours to obtain an acrylic copolymer (A) having unsaturated double bonds and carboxyl groups, with a copolymerization ratio (by mass): EA / 2-EHMA / BA / GMA / AA = 20 / 40 / 20 / 5 / 15.

[0050] [Photopolymerization initiator] ·OXE04: “IRGACURE (registered trademark)” OXE04 [Compounds containing unsaturated double bonds] • BP-4EA: “Light Acrylate (registered trademark)” BP-4EA (manufactured by Kyoeisha Chemical Co., Ltd.) [Conductive particles] • Silver particles: Silver particles with a particle size (D50) of 0.3 μm. [Epoxy resin] • N-865: “EPICLON (registered trademark)” N-865 (manufactured by DIC Corporation) • YL-980: “jER (registered trademark)” YL-980 (manufactured by Mitsubishi Chemical Corporation) [Novolac-type phenolic resin] • MEH-7600: MEH-7600-4H (Manufactured by Meiwa Kasei Co., Ltd.) [Curing accelerator] • C11Z-CN: “Curezol (registered trademark)” C11Z-CN (manufactured by Shikoku Chemicals Co., Ltd.) [solvent] • PGMEA: Propylene glycol monomethyl ether acetate [Electronic components] A μLED chip made of gallium nitride with a thickness of 5 μm and having two electrodes formed of gold was used. The dimensions of each part are as shown in Tables 1 and 2.

[0051] [Gripping board] A 5 μm thick adhesive layer (KR-3704, manufactured by Shin-Etsu Chemical Co., Ltd.) was formed on a silicon wafer cut to 30 mm x 30 mm to create a gripping substrate.

[0052] The evaluation methods for each example and comparative example are as follows.

[0053] <Electrode height, difference in height per electrode> In each example and comparative example, after forming a cross-section through the electrodes of the bumped electronic component by ion milling, the cross-section was observed under magnification using a scanning electron microscope (SEM). The length of the perpendicular line connecting the vertex and the reference plane when observed from a vertical plane was measured and defined as the electrode height. Furthermore, if there was a difference in height within the electrode surface, the largest difference between the height of each evaluation point relative to the reference plane and the height of the vertex was measured and defined as the height difference per electrode.

[0054] <Contamination of electronic components> The bumped electronic components obtained in each example and comparative example were observed under magnification using a scanning electron microscope (SEM) to check for the presence or absence of conductive resin adhesion. LA was defined as the length of the line segment connecting the centers of two electrodes of the electronic component, from one electrode end to the adjacent electrode end. LB was defined as the sum of the lengths of the portions of the line segment where conductive resin was attached. The average value of LB / LA for 100 electronic components was used as the contamination value of the electronic components to evaluate the degree of contamination. A contamination value of 0.3 or less is preferable, and 0.1 or less is more preferable.

[0055] <Transfer rate to electrodes> The bumped electronic components obtained in each example and comparative example were observed under magnification using a scanning electron microscope (SEM) to determine whether or not conductive resin bumps had been transferred onto the electrodes of the electronic components. A component was deemed to have "transferred conductive resin bumps" if the total area of ​​the transferred conductive resin bumps relative to the electrode area was 0.3 times or more the electrode area. The ratio of the number of electrodes with transferred conductive resin bumps to the total number of electrodes was defined as the transfer rate to the electrodes. Here, "area" refers to the projected area onto a plane parallel to the electronic component. A higher transfer rate indicates better transfer. A transfer rate of 0.8 or higher is preferred, and 0.9 or higher is more preferred.

[0056] <Bump damage rate> Figure 3 shows an example of the state of each component after thermocompression bonding is complete, and is a schematic diagram illustrating the method for measuring the bump failure rate. Of the 100 bump-equipped electronic components 3 obtained in each embodiment, the electrodes to which conductive resin bumps were transferred were observed under magnification using an SEM. Bump failure was defined as the case where the area of ​​the transferred conductive resin bumps became 0.9 times or less the initial area, and the ratio of the number of bump-damaged electrodes to the number of electrodes to which electrode bumps were transferred was defined as the bump failure rate. Here, the initial area of ​​the bump is the average value of the area of ​​100 conductive resin bumps on the supply substrate before transfer. The electrodes to which conductive resin bumps are transferred that are subject to observation are electrodes to which the total area of ​​the transferred conductive resin bumps relative to the area of ​​the electrode is 0.3 times or more the area of ​​the electrode. Area refers to the projected area on a plane parallel to the electronic component. If the conductive resin bump is fragmented, the determination is made using the maximum area E formed by the conductive resin bumps in contact with the electrode, as shown in Figure 3. A bump break rate of 0.4 or less is preferable, and 0.1 or less is even preferable.

[0057] <Peeling force> In each embodiment, when separating the gripping substrate and the supply substrate after thermocompression bonding, the tensile force perpendicular to the gripping substrate was measured using a force gauge (AD-4932A-50N, manufactured by A&D Co., Ltd.). Comparative Examples 1 to 3 were excluded from evaluation because thermocompression bonding was not performed. The peeling force is preferably 0.4 N or less, and more preferably 0.1 N or less.

[0058] (Example 1) <Making the paste> A paste was obtained by mixing 30 parts by weight of the acrylic copolymer (A) obtained in the synthesis example, 20 parts by weight of BP-4EA, 3 parts by weight of OXE04, 10 parts by weight of N-865, 10 parts by weight of YL-980, 5 parts by weight of MEH-7600, 0.2 parts by weight of C11Z-A, 170 parts by weight of silver particles, and 30 parts by weight of PGMEA.

[0059] <Formation of conductive resin bumps> The paste was applied to a glass substrate, which served as the supply substrate, by spin coating to form a coated film. The coated film was dried in a drying oven at 100°C for 10 minutes to form a dried film with a thickness of 1.5 μm. Subsequently, exposure was performed using an exposure apparatus (PEM-6M; manufactured by Union Optical Co., Ltd.) equipped with an ultra-high pressure mercury lamp, with an exposure dose of 2000 mJ / cm² for the i-line (wavelength 365 nm). 2 After pattern exposure of the dried film, it was shower-developed for 40 seconds with a 0.1 wt% Na2CO3 aqueous solution, rinsed with ultrapure water, and conductive resin bumps were formed. The size of the conductive resin bumps was 40 μm × 30 μm, and they were formed at positions corresponding to the electrodes of the electronic components placed on the gripping substrate described later.

[0060] <Thermocompression bonding process> On the gripping substrate, the electronic components shown in Table 1 were arranged in a 50x50 grid with a pitch of 200 μm.

[0061] The following operations were performed using a flip-chip bonder (FC-3000WS, manufactured by Toray Engineering Co., Ltd.): The supply substrate was fixed to the stage. The gripping substrate, on which electronic components were arranged, was picked up, and the electrodes of the electronic components on the gripping substrate were placed opposite the conductive resin bumps on the supply substrate. Thermocompression bonding was performed under the conditions of a stage temperature of 40°C, a head temperature of 80°C, a load of 5N, and 10 seconds. Upon completion of thermocompression bonding, the head of the flip-chip bonder was retracted while adsorbing and destroying the gripping substrate, thereby obtaining a laminate of the gripping substrate and the supply substrate. After this, the gripping substrate and the supply substrate of the laminate were separated. Through this process, conductive resin bumps were transferred onto the electrodes of the electronic components arranged on the gripping substrate, thereby obtaining electronic components with bumps.

[0062] (Examples 2-11) An electronic component with bumps was obtained in the same manner as in Example 1, except that the size of the electronic component, electrode height, height difference per electrode, electrode size, and bump size were changed as shown in Tables 1 and 2.

[0063] The electronic components used in Examples 1 to 10 are μLEDs, each having two electrodes of the sizes listed in Tables 1 and 2 on the bonding surface with the bump. The electronic component used in Example 11 is a vertical μLED, each having one electrode of the size listed in Table 2 on the underside of the chip.

[0064] (Comparative Example 1) Figure 4 shows the method for forming conductive resin bumps in Comparative Example 1. As shown in (a), the same paste used in Example 1 was applied by spin coating to the release surface of a release film 6 (product name PET25AL-5, thickness 25 μm, manufactured by Lintec Corporation) fixed on a glass substrate to form a coating film. The coating film was dried in a drying oven at 100°C for 10 minutes to form a dried film 7 with a thickness of 1.5 μm. The obtained dried film was heat-pressed onto the surface of the gripping substrate 5 on which the electronic components 4 were placed using a laminating device (Nikko Materials Co., Ltd., CVP-300T) under the conditions of a temperature of 80°C, a pressure of 0.1 MPa, and a heat-pressure bonding time of 20 seconds, and then the release film 6 was peeled off as shown in (b). On the dried film pressed onto the surface of the gripping substrate where the electronic components are located, an exposure apparatus (PEM-6M; manufactured by Union Optical Co., Ltd.) equipped with an ultra-high pressure mercury lamp was used to expose the i-line (wavelength 365 nm) at an exposure dose of 2000 mJ / cm². 2 After pattern exposure, the material was shower-developed with a 0.1 wt% Na2CO3 aqueous solution for 40 seconds, and then rinsed with ultrapure water to form the conductive resin bump 2 shown in (c). The conductive resin bump was 16 μm × 8 μm in size and was formed at a position corresponding to the electrode 3 of the same type of electronic component as in Example 7, which was placed on the gripping substrate.

[0065] (Comparative Examples 2-3) Figure 5 shows the transfer process of conductive resin bumps in Comparative Examples 2 and 3. After preparing a supply substrate using the same procedure as in Example 1, as shown in (a), the supply substrate 1 and the gripping substrate 5 on which the electronic components 4 are placed are positioned opposite each other at a distance of 50 μm, and the conductive resin bumps 2 on the supply substrate are aligned to overlap the electrodes 3 of the electronic components. As shown in (b), the conductive resin bumps are transferred onto the electrodes of the electronic components arranged on the gripping substrate by irradiating each conductive resin bump with a laser 8 from the back surface of the supply substrate, thereby obtaining electronic components with bumps. The laser had a wavelength of 355 nm, a pulse width of 8 n seconds, and a beam size that was 1.5 times the short side and long side of the conductive resin bump, respectively. The sizes of the conductive resin bumps, electronic components, and electrodes are shown in Table 2.

[0066] Tables 1 and 2 show the main configurations and evaluation results for each example and comparative example.

[0067] [Table 1]

[0068] [Table 2] [Explanation of symbols]

[0069] 1: Supply board 2: Conductive resin bump 3: Electrode 4: Electronic components 5: Gripping board 6: Release film 7: Dry membrane 8: Laser A: Reference surface of electronic components B: Electrode height C: Height difference per electrode D: Angle between the tangent to the electrode surface and the reference plane.

Claims

1. A method for manufacturing an electronic component with bumps, comprising the step of transferring conductive resin bumps to the electrodes of an electronic component by pressing the electrodes of the electronic component against conductive resin bumps formed on a supply substrate, wherein the height difference per electrode of the electronic component is 0.5 to 5.0 μm.

2. A method for manufacturing a bumped electronic component according to claim 1, wherein the electrode height of the electronic component is 0.5 to 10.0 μm.

3. A method for manufacturing an electronic component with bumps, comprising the step of transferring conductive resin bumps to the electrodes of an electronic component by pressing the electrodes of the electronic component against conductive resin bumps formed on a supply substrate, wherein the area of ​​each conductive resin bump formed on the supply substrate is 5 to 600 μm². ２ A method for manufacturing bump-type electronic components.

4. A method for manufacturing an electronic component with bumps according to claim 1 or claim 3, wherein the area of ​​each conductive resin bump formed on the supply substrate is 0.3 to 1.8 times the area of ​​each electrode of the electronic component.

5. A method for manufacturing an electronic component with bumps according to claim 1 or claim 3, wherein the pressure temperature when pressing the electrodes of the electronic component against the conductive resin bumps is 40°C or more and 180°C or less.

6. A method for manufacturing a bumped electronic component according to claim 1 or claim 3, wherein a plurality of the aforementioned electronic components are gripped on a gripping substrate.

7. A method for manufacturing an electronic component with bumps according to claim 1 or claim 3, wherein the number of conductive resin bumps formed on the supply substrate is greater than the number of conductive resin bumps transferred to the electronic component by one cycle of crimping.

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