WO2024162036A1 - Method for manufacturing electronic component with bump - Google Patents

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

Manufacturing method for electronic components with bumps

The present invention relates to a method for manufacturing electronic components with bumps.

In recent years, in the display field, structures using LED chips with sides of 100 μm or less, called μLEDs, have been actively considered. For mounting μLEDs, the flip-chip mounting method is preferably used, which can minimize the area of the wiring between the chip and the substrate by forming electrodes on the surface of the chip and directly connecting the chip to the electrodes on the substrate. In the flip-chip mounting method, the bonding material for electrically connecting the electrodes on the chip surface and the electrodes on the substrate is called a bump. Bumps have generally been formed mainly from solder, but because they are melted by heating during formation and connection, if the electrode pitch is less than 20 μm, there is a high risk of electrodes shorting out due to the connection between adjacent bumps by molten solder. For this reason, connection materials that replace solder as bump materials are being considered for fine structures.

As a method suitable for implementing μLEDs, a method for manufacturing a substrate with a conductive pattern has been proposed that includes the steps of forming a pattern of a composition having an organic component and conductive particles on a transfer substrate, and irradiating the back side of the transfer substrate with a laser to transfer the pattern to a transfer substrate (see, for example, Patent Document 1).

JP 2022-55760 A

Although the method of Patent Document 1 can obtain a substrate with a conductive pattern that has high positional accuracy during transfer, the conductive pattern that forms the bumps collides with the substrate at high speed by laser irradiation, so the transferred conductive pattern tends to be easily destroyed, and there is a problem that the conductive pattern pieces generated by the destruction contaminate the electronic components. There is a concern that such contamination may induce short circuits due to unintended connections of peripheral circuits in some cases. In addition, as a method for forming bumps with fine structures such as μLEDs, it is possible to form patterns of bumps by photolithography using a photosensitive resin composition. However, in pattern formation by photolithography, a film of the photosensitive resin composition is formed in places other than the places where the bumps are formed, so residues of the photosensitive resin composition are likely to be generated on the surface of the electronic components. There is also a concern that contamination by such residues may induce short circuits due to unintended connections of peripheral circuits in some cases.

The present invention aims to provide a method for manufacturing electronic components with bumps that can suppress contamination of the electronic components during bump formation.

In order to solve the above problems, the present invention mainly has the following configuration.
(1) A method for manufacturing an electronic component with bumps, comprising a step of transferring conductive resin bumps to electrodes of the electronic component by facing the electrodes of the electronic component to conductive resin bumps formed on a supply substrate and pressing the electrodes against the conductive resin bumps.
(2) The method for producing an electronic component with bumps according to (1), wherein the height of the electrodes of the electronic component is 0.5 to 10.0 μm.
(3) The method for producing an electronic component having bumps according to (1) or (2), wherein the area of each of the conductive resin bumps formed on the supply substrate is 5 to ⁶⁰⁰ μm2.
(4) The method for producing an electronic component with bumps according to any one of (1) to (3), wherein the area of each of the conductive resin bumps formed on the supply substrate is 0.3 to 1.8 times the area of each of the electrodes of the electronic component.
(5) The method for producing an electronic component with bumps according to any one of (1) to (4), wherein the difference in height per electrode of the electronic component is 0.5 to 5.0 μm.
(6) The method for producing an electronic component with bumps according to any one of (1) to (5), wherein the pressure-bonding temperature when the electrodes of the electronic component are placed opposite the conductive resin bumps and pressure-bonded is 40° C. or higher and 180° C. or lower.
(7) The method for producing an electronic component having bumps according to any one of (1) to (6), wherein a plurality of the electronic components are held on a holding substrate.
(8) The 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 base material is greater than the number of conductive resin bumps transferred to an electronic component by one cycle of compression bonding.

The electronic component manufacturing method of the present invention makes it possible to form bumps while suppressing contamination of the electronic components.

1A to 1C are schematic diagrams showing an example of a method for producing an electronic component with bumps according to the present invention. FIG. 2 is a schematic diagram showing the electrode height and the height difference per electrode in the present invention. FIG. 2 is a schematic diagram showing a method for evaluating a bump damage rate in the examples. 5A to 5C are schematic diagrams showing a process for forming a conductive resin bump in Comparative Example 1. 11A to 11C are schematic diagrams showing a transfer process of conductive resin bumps in Comparative Examples 2 and 3.

The method for manufacturing electronic components with bumps of the present invention includes a step of transferring conductive resin bumps to the electrodes of the electronic component by facing the electrodes of the electronic component to the conductive resin bumps formed on a supply substrate and pressing the electrodes together. As described above, when conductive resin bumps formed in advance on a transfer substrate are transferred to a transfer substrate using a laser, or when bumps are formed on electronic components by photolithography using a photosensitive resin composition, contamination by conductive resin bump pieces or photosensitive resin composition can be an issue. However, in the present invention, the conductive resin bumps are transferred by pressing, so contamination due to residues or damage to the bumps can be suppressed. Furthermore, compared to techniques for forming conductive resin bumps using a dispenser or inkjet, conductive resin bumps with higher resolution can be formed.

Below, an embodiment of the method for manufacturing electronic components with bumps according to the present invention will be described in detail with reference to the drawings. Note that the drawings are schematic. Furthermore, the present invention is not limited to the embodiment described below.

FIG. 1 is a schematic diagram showing an example of an embodiment of the method for manufacturing electronic components with bumps according to the present invention. First, as shown in (a), conductive resin bumps 2 formed on a supply substrate 1 and multiple electronic components 4 held on a holding 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 holding substrate 5 are pulled apart, transferring the conductive resin bumps 2 onto the electrodes 3.

Examples of bonding devices include flip chip bonders and diaphragm laminators. Thermocompression is a preferred bonding method, and the bonding temperature is preferably 40°C or higher and 180°C or lower. By setting the bonding temperature at 40°C or higher, the storage modulus of the conductive bumps can be reduced, improving adhesion to the electrodes of the electronic components. On the other hand, by setting the bonding temperature at 180°C or lower, thermal expansion and thermal contraction of the supply substrate and electronic components can be suppressed, and the positional accuracy of the transfer can be further improved.

The bonding temperature may be different for the conductive resin bumps and the electronic components. 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, the conductive bumps can be transferred more easily even when the temperature of the upper side plate described later is low. 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 of the conductive resin bumps due to thermal reaction 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 electronic components 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 bumps can be transferred more easily. On the other hand, by setting the temperature of the upper side plate to 180°C or lower, the waiting time associated with the rise and fall of the temperature 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 the temperature of at least one of the upper and lower side panels is in the range of 40°C to 180°C.

The pressure during bonding is preferably 0.1 MPa or more and 10 MPa or less, which can further prevent damage to the conductive resin bumps due to bonding and further prevent contamination of the electronic components. The pressure is the value obtained by dividing the load applied by the device by the total contact area. The total contact area is the product of the area per smaller one of the conductive resin bumps transferred during bonding and the electrodes of the electronic components in contact with it, and the number of electrodes.

The bonding time is preferably 0.1 seconds or more and 20 seconds or less, which can improve productivity.

The following describes the materials used in the manufacturing method for electronic components with bumps of the present invention.

<Supply Board>
The supply substrate in the present invention is a substrate that holds conductive resin bumps in order to supply conductive resin bumps to be transferred to electrodes of electronic components. Examples of materials constituting the supply substrate include organic materials and inorganic materials such as glass and silicon. Among these, inorganic materials with high in-plane flatness are preferred in order to increase the parallelism of the supply substrate during pressure bonding. As a supply substrate made of an inorganic material, for example, a glass substrate is preferred.

The surface of the supply substrate may be subjected to a release treatment, which makes it easier to transfer the conductive resin bumps. The surface of the supply substrate may also have a flexible layer, which absorbs the inclination of the supply substrate when transferring the conductive resin bumps, making it easier to transfer the conductive resin bumps.

The number of conductive resin bumps formed on the supply substrate (hereinafter referred to as the number of formed bumps) is preferably greater than the number of conductive resin bumps transferred to an electronic component by one cycle of pressure bonding (hereinafter referred to as the number of used bumps). By making the number of formed bumps greater than the number of used bumps, multiple transfers can be performed using one supply substrate, improving productivity. It is more preferable that the number of formed bumps is at least twice the number of used bumps. Here, the number of used bumps when multiple transfers are performed using one supply substrate refers to the smallest number of bumps used per transfer among the multiple transfers, and the number of formed bumps refers to the total number of bumps formed on the supply substrate before transfer.

<Conductive resin bump>
The conductive resin bump has conductivity and has a function of electrically connecting the conductive resin bump and the electrode in contact therewith. Here, "having conductivity" means that the conductive resin bump has conductivity when the electronic component finally functions, and may have conductivity by a specific process. For example, the conductive resin bump may have conductivity by heating or pressure when transferred to the electronic component. The conductive resin bump preferably has an electrical resistivity of 1 Ω·m or less. The electrical resistivity ρ of the conductive resin bump is calculated by ρ=R×S/L, where S is the cross-sectional area of the electrode having a smaller area among two electrodes that are in contact with the conductive resin bump and electrically connected to form a circuit, L is the linear distance from the surface of the electrode to the surface of the other electrode, and R is the electrical resistance value of the conductive resin bump. If L is not constant within the plane due to unevenness on the electrode surface, etc., a cross-sectional area S corresponding to the region with different L is set for each region, and the parallel circuit of these electrodes forms an electrical resistance R, and ρ can be calculated as follows: ρ=R(S ₁ /L ₁ +S ₂ /L ₂ +...).

The conductive resin bump may contain a conductive resin or may contain conductive particles. In the latter case, the conductive particles may be dispersed in the resin and the conductive particles may be continuously contacted to obtain an electrical connection, or the conductive particles may be connected by sintering to obtain an electrical connection. Examples of the 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, particles of conductive oxides such as indium tin oxide (ITO) and indium zinc oxide (IZO), etc. Two or more of these may be contained. In addition, the above-mentioned materials may have a structure in which the surface of the particles formed by the resin or inorganic material is covered. In the present invention, it is preferable that the conductive particles contain a photosensitive organic component and conductive particles. Examples of such organic components include binder resins, compounds having photopolymerizable groups, and photopolymerization initiators. It may also contain a curing catalyst or other additives.

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 contained. The binder resin preferably has a carboxyl group, which can improve developability.

A compound having a photopolymerizable group refers to a monomer or oligomer having a photopolymerizable group. Examples of photopolymerizable groups include acryloyl groups and methacryloyl groups. Examples of compounds having a photopolymerizable group include bifunctional 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 adduct of ethylene glycol diglycidyl ether; trifunctional monomers such as pentaerythritol triacrylate, pentaerythritol triacrylate, trimethylolpropane triacrylate, trimethylolpropane ethoxy triacrylate, and glycerin propoxy triacrylate; tetrafunctional monomers such as dipentaerythritol hexaacrylate, pentaerythritol tetraacrylate, pentaerythritol ethoxy tetraacrylate, and ditrimethylolpropane tetraacrylate, and compounds in which the acrylic group of these monomers is replaced with a methacrylic group. Two or more of these may be included.

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, anthraquinone compounds, etc. Two or more of these may be contained.

The area per conductive resin bump is preferably ⁵ μm2 or more, which allows sufficient adhesion during compression bonding and therefore facilitates transfer. The area per conductive resin bump is more preferably ⁴⁰ μm2 or more. On the other hand, the area per conductive resin bump is preferably ⁶⁰⁰ μm2 or less, which reduces the load required for peeling from the supply substrate and facilitates transfer. The area is more preferably ⁴⁰⁰ μm2 or less.

In addition, the area of each conductive resin bump is preferably at least 0.3 times the area of each electrode of the electronic component to be transferred, which allows for sufficient electrical connection with the electronic component. On the other hand, the area of each conductive resin bump is preferably no more than 1.8 times the area of each electrode of the electronic component to be transferred, and more preferably no more than 1.5 times, which allows for better prevention of damage to the bumps when transferring the conductive resin bumps from the supply substrate, and better prevention of contamination of the electronic component.

Here, the area of each conductive resin bump refers to the area of one conductive resin bump projected onto a plane parallel to the supply substrate on which the conductive resin bump is formed, and can be found by measuring the area of each of 100 randomly selected conductive resin bumps using an optical microscope or scanning electron microscope (SEM) and calculating the median.

The thickness of the conductive resin bump is preferably 0.5 μm or more, which can suppress the variation in electrical resistance value. It can also improve the adhesive strength between the conductive resin bump and the electrode to which it is connected. It can also make transfer easier. On the other hand, the thickness of the conductive resin bump is preferably 5 μm or less, and more preferably 3 μm or less.

The conductive resin bumps preferably have adhesive properties and a glass transition point of 100°C or less when formed on the supply substrate.

The conductive resin bumps can be formed, for example, by applying a paste made by kneading the components constituting the conductive resin bumps described above 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, the method preferably includes the steps of applying the paste onto the supply substrate to form a dry film, and exposing and developing the dry film.

Examples of paste application methods include rotary application using a spinner, spray application, roll coating, screen printing, and application using a blade coater, die coater, calendar coater, meniscus coater, or bar coater.

Drying methods include, for example, heat drying using an oven, a hot plate, infrared rays, etc., and vacuum drying. The drying temperature is preferably 50 to 180°C, and the drying time is preferably 1 minute to several hours.

The thickness of the dry film can be appropriately selected according to the desired thickness of the conductive resin bump. The thickness of the dry film is preferably 0.5 μm or more. On the other hand, the thickness of the dry film is preferably 5 μm or less, which allows light to easily reach deep into the dry film during exposure and suppresses peeling during development. The thickness of the dry film is more preferably 3 μm or less. The thickness of the dry film of the paste can be measured using a stylus step gauge. More specifically, the thickness is measured at three randomly selected locations using a stylus step gauge (measurement length: 1 mm, scanning speed: 0.3 mm/sec) and the average value is calculated.

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

The exposed dry film is then developed. Examples of development methods include spraying a developer onto the surface of the dry film while the supply substrate with the exposed dry film is stationary or rotated, immersing the supply substrate with the exposed dry film in a developer, and applying ultrasonic waves to the supply substrate with the exposed dry film while immersing it in a developer.

The developer is preferably an alkaline aqueous solution. After development, a rinse treatment may be performed using a rinse solution. Examples of rinse solutions include water, or an aqueous solution of water to which alcohols such as ethanol or isopropyl alcohol have been added, or esters such as ethyl lactate or propylene glycol monomethyl ether acetate have been added.

<Electronic Components>
The electronic component in the present invention refers to a general element that is mounted on a substrate with electrical connection and functions based on the input or output of an electrical signal, or both. The electronic component has at least one electrode. Examples of electronic components include semiconductor chips, interposers, and optical elements. Among these, the present invention can be preferably applied to optical elements. Examples of optical elements include LEDs, photoresistors, phototransistors, photodiodes, micromirrors, solar cells, and the like. In particular, μLEDs with each side of 100 μm or less are preferable because the productivity can be increased by using the manufacturing method of the present invention.

<Electrodes>
The electrodes are generally made of a metal material or a semiconductor.

The ratio of the electrode area to the total area of the surface of the electronic component having the electrodes (hereinafter sometimes referred to as the "electrode area ratio") is preferably 0.1 to 0.8. By making the electrode area ratio 0.1 or more, it is possible to obtain a sufficient current to operate the electronic component. It is more preferable that the electrode area ratio is 0.2 or more. On the other hand, by making the electrode area ratio 0.8 or less, it is possible to suppress short circuits between electrodes. It is more preferable that the electrode area ratio of the electronic component is 0.7 or less.

Here, the area of the surface of an electronic component having electrodes and the area of the electrodes are the areas of projections onto a plane parallel to the board 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 board on which it is mounted, and then observing each of them using an optical microscope or a scanning electron microscope (SEM).

The electrode height is preferably 0.5 μm or more, and even if the conductive resin bump is deformed during compression, adhesion of the conductive resin bump to the surface of the electronic component is further suppressed, and contamination of the electronic component is further suppressed. On the other hand, the electrode height is preferably 10.0 μm or less, and variation in electrode height can be suppressed and processing precision can be improved.

The electrodes may have a structure with different heights within the electrode surface (hereinafter, sometimes referred to as "height difference"). During compression, the contact area between the conductive resin bump and the electrode becomes larger, improving adhesion and making it easier to transfer. 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, a method in which a concave-convex shape is formed in advance by etching or the like on the electronic component at the position where the electrode is to be formed, and then the electrode is formed on top of that by plating or the like, thereby reflecting the concave-convex shape on the electronic component on the electrode surface, and a method in which the formed electrode is processed by etching or the like.

Here, the method of measuring the electrode height of each part and the height difference per electrode will be described with reference to Figure 2. Electrode height B is the height of the point (hereinafter referred to as the apex) of the electrode that is farthest from the surface of the electronic component when observed from a plane (hereinafter referred to as the vertical plane) perpendicular to the electronic component on which the electrode is formed, and is the length of a perpendicular line drawn from a horizontal plane passing through the electrode apex to reference plane A. Here, reference plane A of the electronic component is a horizontal plane passing through the reference point, which is the position on the electronic component surface that is the longest when a perpendicular line is drawn from the horizontal plane passing through the electrode apex to the electronic component in the part of the electronic component surface excluding the electrodes. However, the part where the angle between the tangent to the electronic component surface and the horizontal plane is 70 to 110 degrees is not used as the reference point. When an electronic component has multiple electrodes, the largest value of the electrode heights is taken as electrode height B.

If there is a height difference within the electrode surface, the height difference C per electrode is the largest difference between the height of each evaluation point and the height of the apex, based on the reference plane A. The evaluation points are points on the electrode surface excluding the parts where the angle D between the tangent to the electrode surface and the reference plane is 70 to 110°, and are measured in the same way as the electrode height.

<Grip substrate>
The gripping substrate in the present invention is a substrate for gripping an electronic component. The gripping substrate preferably has a plurality of electronic components gripped thereon. Methods for gripping electronic components include, for example, a method using an adhesive. Materials constituting the gripping substrate include those exemplified for the supply substrate. In order to increase the parallelism with the supply substrate, inorganic materials with high in-plane flatness are preferred, for example, silicon substrates are preferred. The surface of the gripping substrate may further have a flexible layer, which can absorb the inclination of the conductive resin bumps when transferring the conductive resin bumps, making it easier to transfer the conductive resin bumps. The gripping substrate may have a flexible layer for absorbing the inclination of the member when transferring the conductive resin bumps.

The present invention will be described in detail below with examples and comparative examples, but the aspects of the present invention are not limited to these.

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

[Photosensitive component]
(Synthesis Example) Acrylic Copolymer (A)
In a reaction vessel in a nitrogen atmosphere, 150 g of diethylene glycol monobutyl ether (hereinafter, "DGME") was charged, 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-methylol acrylamide (hereinafter, "MAA"), 0.8 g of 2,2'-azobisisobutyronitrile, and 10 g of DGME was dropped into the reaction vessel over 1 hour. After the dropwise addition, the mixture was heated at 80 ° C. for 6 hours to carry out a polymerization reaction. Then, 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 dropped into the reaction vessel over 0.5 hours. After the dropwise addition was completed, the mixture was heated for an additional 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 an unsaturated double bond and a carboxyl group with a copolymerization ratio (by mass): EA/2-EHMA/BA/GMA/AA=20/40/20/5/15.

[Photopolymerization initiator]
OXE04: "IRGACURE (registered trademark)" OXE04
[Compounds having 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 diameter (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: "Curesol (registered trademark)" C11Z-CN (manufactured by Shikoku Kasei Co., Ltd.)
[solvent]
・PGMEA: Propylene glycol monomethyl ether acetate [electronic parts]
A μLED chip made of gallium nitride with a thickness of 5 μm and having two electrodes made of gold was used. The dimensions of each part are as shown in Tables 1 and 2.

[Grip substrate]
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×30 mm to prepare a substrate for gripping.

The evaluation methods for each example and comparative example are as follows:

<Electrode height, height difference per electrode>
From the electronic components with bumps obtained in each Example and Comparative Example, a cross section passing through the electrodes of the electronic components was formed by ion milling, and the cross section was then enlarged and observed using a scanning electron microscope (SEM), and the length of the perpendicular line connecting the apex and the reference plane when observed from a vertical plane was measured and taken as the electrode height. In addition, when there was a height difference within the electrode plane, the largest value among the differences between the height of each evaluation point based on the reference plane and the height of the apex was measured and taken as the height difference per electrode.

<Contamination of electronic components>
The electronic components with bumps obtained in each of the examples and comparative examples were magnified and observed using a SEM to observe whether or not the conductive resin was attached. Of the line segments connecting the centers of the two electrodes of the electronic components, the length from the end of one electrode to the end of the adjacent electrode was defined as LA. In addition, the total length of the above line segments to which the conductive resin was attached was defined as LB. The average value of LB/LA for 100 electronic components was defined as the value of contamination of the electronic components, and the degree of contamination of the electronic components was evaluated. The value of contamination of the electronic components is preferably 0.3 or less, and more preferably 0.1 or less.

<Transfer rate to electrode>
The electronic components with bumps obtained in each Example and Comparative Example were magnified and observed using a SEM to observe whether the conductive resin bumps were transferred onto the electrodes of the electronic components. When the total area of the conductive resin bumps transferred onto the target electrode was 0.3 times or more the area of the electrode, it was determined that the conductive resin bumps were transferred, and the ratio of the number of electrodes onto which the conductive resin bumps were transferred to the total number of electrodes was determined as the transfer rate to the electrodes. The area referred to here is the projected area onto a plane parallel to the electronic component. The higher the transfer rate, the better the transfer was. The transfer rate to the electrodes is preferably 0.8 or more, and more preferably 0.9 or more.

<Bump damage rate>
FIG. 3 shows an example of the state of each member after completion of thermocompression bonding, and is a schematic diagram showing a method for measuring the bump damage rate. Among the electrodes 3 of 100 bumped electronic components obtained in each example, the electrodes to which the conductive resin bumps were transferred were observed under magnification using a SEM. A case in which the area of the transferred conductive resin bumps was 0.9 times or less of the initial area was deemed to be a bump damage, and the ratio of the number of electrodes with damaged bumps to the number of electrodes to which the electrode bumps were transferred was deemed to be the bump damage rate. Here, the initial area of the bumps is the average area of 100 conductive resin bumps on the supply substrate before transfer. The electrodes to which the conductive resin bumps are transferred to be observed are electrodes in which the total area of the conductive resin bumps transferred to the target electrode is 0.3 times or more the area of the electrode. The area refers to the projected area on a plane parallel to the electronic component. When the conductive resin bumps are divided, the largest area E formed by the conductive resin bumps in contact with the electrode is used to judge the breakage, as shown in FIG. 3. The bump breakage rate is preferably 0.4 or less, and more preferably 0.1 or less.

<Peeling Force>
In each example, when the holding substrate and the supply substrate were separated after thermocompression bonding, the tensile force in the direction perpendicular to the holding 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 they did not involve thermocompression bonding. The peel force is preferably 0.4 N or less, and more preferably 0.1 N or less.

Example 1
<Preparation of paste>
The acrylic copolymer (A) obtained in Synthesis Example: 30 parts by weight, BP-4EA: 20 parts by weight, OXE04: 3 parts by weight, N-865: 10 parts by weight, YL-980: 10 parts by weight, MEH-7600: 5 parts by weight, C11Z-A: 0.2 parts by weight, silver particles: 170 parts by weight, and PGMEA: 30 parts by weight were mixed to obtain a paste.

<Formation of conductive resin bumps>
The paste was applied by spin coating onto a glass substrate, which was a supply 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 having a thickness of 1.5 μm. Thereafter, the dried film was pattern-exposed with an exposure amount of 2000 mJ/ ^cm2 of i-line (wavelength 365 nm) using an exposure device (PEM-6M; manufactured by Union Optical Co., Ltd.) having an ultra-high pressure _mercury lamp, and then shower-developed for 40 seconds using a 0.1 wt% _Na2CO3 aqueous solution, and rinsed with ultrapure water to form a conductive resin bump. The size of the conductive resin bump was 40 μm x 30 μm, and it was formed at a position corresponding to the electrode of the electronic component arranged on the gripping substrate described later.

<Thermocompression bonding process>
On the holding substrate, 50 electronic components shown in Table 1 were arranged vertically and 50 electronic components horizontally at a pitch of 200 μm.

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 holding substrate on which electronic components were arranged was picked up, and the electrodes of the electronic components on the holding substrate were placed opposite the conductive resin bumps of the supply substrate, and thermocompression bonding was performed under the following conditions: stage temperature 40°C, head temperature 80°C, load 5N, 10 seconds. When thermocompression bonding was completed, the head of the flip chip bonder was withdrawn while the holding substrate was adsorbed and destroyed, and a laminate of the holding substrate and the supply substrate was obtained. The holding substrate and the supply substrate of the laminate were then separated. Through this process, the conductive resin bumps were transferred onto the electrodes of the electronic components arranged on the holding substrate, and electronic components with bumps were obtained.

(Examples 2 to 11)
Electronic components with bumps were obtained in the same manner as in Example 1, except that the size of the electronic components, the electrode height, the height difference per electrode, the electrode size, and the bump size were changed as shown in Tables 1 and 2.

The electronic components used in Examples 1 to 10 were μLEDs having two electrodes of the size shown in Tables 1 and 2 per electronic component on the bonding surface with the bump. The electronic components used in Example 11 were vertical μLEDs having one electrode of the size shown in Table 2 per electronic component on the underside of the chip.

(Comparative Example 1)
4 shows a method for forming conductive resin bumps in Comparative Example 1. As shown in (a), the same paste as that used in Example 1 was applied by spin coating onto the release-treated surface of a release film 6 (trade 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 for 10 minutes in a drying oven at 100° C. to form a dry film 7 having a thickness of 1.5 μm. The obtained dry film was thermocompressed onto the surface of the gripping substrate 5 on which the electronic components 4 were arranged, using a laminating device (Nikko Materials Corporation, CVP-300T), under conditions of a temperature of 80° C., a pressure of 0.1 MPa, and a thermocompression time of 20 seconds, and then the release film 6 was peeled off as shown in (b). The dried film pressed onto the surface of the holding substrate on which the electronic components were arranged was exposed to a pattern of i-line (wavelength 365 nm) at an exposure dose of 2000 mJ/ ^cm2 using an exposure device (PEM-6M; manufactured by Union Optical Co., Ltd.) having an ultra-high pressure _mercury lamp, and then the pattern was developed by shower development for 40 seconds using a 0.1 wt% _Na2CO3 aqueous solution and rinsed with ultrapure water to form the conductive resin bump 2 shown in (c). The size of the conductive resin bump was 16 μm × 8 μm, and it was formed at a position corresponding to the electrode 3 of the electronic component of the same type as in Example 7 arranged on the holding substrate.

(Comparative Examples 2 to 3)
5 shows the transfer process of the conductive resin bumps in Comparative Examples 2 and 3. After preparing the supply substrate in the same manner as in Example 1, as shown in (a), the supply substrate 1 and the holding substrate 5 on which the electronic components 4 are arranged are opposed to each other with a distance of 50 μm, and the conductive resin bumps 2 on the supply substrate are aligned to overlap with 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 holding substrate by irradiating the respective conductive resin bumps from the rear surface of the supply substrate with a laser 8, thereby obtaining electronic components with bumps. The laser has a wavelength of 355 nm, a pulse width of 8 ns, and a beam size that is 1.5 times the short and long sides of the conductive resin bumps. The sizes of the conductive resin bumps, the electronic components, and the electrodes are as shown in Table 2.

The main configurations and evaluation results of each example and comparative example are shown in Tables 1 and 2.

1: Supply substrate 2: Conductive resin bump 3: Electrode 4: Electronic component 5: Holding substrate 6: Release film 7: Dry film 8: Laser A: Reference surface of electronic component B: Electrode height C: Height difference per electrode D: Angle between tangent of electrode surface and reference surface

Claims (8)

A method for manufacturing an electronic component with bumps, which includes a step of transferring conductive resin bumps to electrodes of an electronic component by facing the electrodes of the electronic component to conductive resin bumps formed on a supply substrate and crimping the electrodes. The method for manufacturing an electronic component with bumps according to claim 1, wherein the electrode height of the electronic component is 0.5 to 10.0 μm. 3. The method for producing an electronic component with bumps according to claim 1, wherein the area of each of the conductive resin bumps formed on the supply substrate is 5 to ⁶⁰⁰ μm2. The method for manufacturing an electronic component with bumps according to claim 1 or 2, 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. The method for manufacturing an electronic component with bumps according to claim 1 or 2, wherein the difference in height between the electrodes of the electronic component is 0.5 to 5.0 μm. The method for manufacturing an electronic component with bumps according to claim 1 or 2, wherein the pressure bonding temperature when the electrodes of the electronic component are placed opposite the conductive resin bumps and pressure bonded is 40°C or higher and 180°C or lower. The method for manufacturing an electronic component with bumps according to claim 1 or claim 2, in which a plurality of the electronic components are held on a holding substrate. The method for manufacturing an electronic component with bumps according to claim 1 or 2, wherein the number of conductive resin bumps formed on the supply base material is greater than the number of conductive resin bumps transferred to the electronic component by one cycle of compression bonding.

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