TWI843762B - Method for manufacturing connection structure - Google Patents

Abstract

The present invention provides a method for manufacturing a connector capable of connecting electronic components with electrodes having fine pitches, an anisotropic bonding film, and a connector. An anisotropic bonding material containing a solid resin, solder particles, and a flux compound is placed between an electrode of a first electronic component and an electrode of a second electronic component with a thickness of more than 50% and less than 300% of the average particle size of the solder particles, and the electrode of the first electronic component and the electrode of the second electronic component are heat-bonded without a load. The solid resin is selected from at least one of a thermoplastic resin, a solid free radical polymerizable resin, and a solid epoxy resin, is solid at room temperature, and has a melt flow rate of more than 10 g/10 min at a temperature of 190°C and a load of 2.16 kg.

Description

Manufacturing method of connector

The present invention relates to a method for manufacturing a connector for mounting semiconductor chips (components) such as LEDs (Light Emitting Diodes), an anisotropic bonding film, and a connector. This application claims priority based on Japanese Patent Application No. 2018-206058 filed in Japan on October 31, 2018, and Japanese Patent Application No. 2019-194479 filed on October 25, 2019, which are cited in this application as references.

As one of the methods for mounting semiconductor chips (components) such as LEDs, flip chip mounting can be cited. Compared with wire bonding, flip chip mounting can reduce the mounting area and can mount small and thin semiconductor chips.

However, since flip chip mounting requires heating and pressing, when bonding multiple semiconductor chips to a large substrate, for example, very high pressure is required, or parallelism needs to be adjusted, making mass production difficult.

Prior art literature

Patent Literature

Patent document 1: Japanese Patent Publication No. 2009-102545

Patent document 1 describes the use of solder paste containing solder particles, thermosetting resin adhesive and flux components to mount multiple parts together on a wiring board, etc. by reflow.

However, the solder paste of Patent Document 1 contains a large amount of solder particles because the solder particles are melted and integrated, making it difficult to join electronic parts with electrodes with fine pitches.

Figure 8 is a microscope photograph of the solder joint state on the substrate side after the LED chip is peeled off in an LED mounting body made using conventional solder paste. As shown in Figure 8, in a general solder paste, when the solder particles are melted and integrated, the solder particles sometimes aggregate between adjacent terminals to form a bridge A, causing a short circuit.

This technology is proposed in view of such a previous reality, and provides a method for manufacturing a connector that can connect electronic parts with fine-pitch electrodes, an anisotropic bonding film, and a connector.

After intensive research, the inventor of this case found that by using an anisotropic bonding material containing "solid resin that is solid at room temperature and has a specific melt flow rate", the thickness of the anisotropic bonding material between the electrodes is set to a specific value relative to the average particle size of the solder particles, so as to achieve the above purpose, thus completing the present invention.

That is, the manufacturing method of the connector of the present invention is as follows: an anisotropic bonding material containing a solid resin, solder particles, and a flux compound is placed between the electrode of the first electronic component and the electrode of the second electronic component with a thickness of more than 50% and less than 300% of the average particle size of the solder particles, and the electrode of the first electronic component and the electrode of the second electronic component are heat-bonded under no load. The solid resin is selected from at least one of thermoplastic resins, solid free radical polymerizable resins, and solid epoxy resins, is solid at room temperature, and has a melt flow rate of more than 10 g/10 min at a temperature of 190°C and a load of 2.16 kg.

Furthermore, the anisotropic bonding film of the present invention contains a solid resin, solder particles, and a flux compound. The solid resin is selected from at least one of a thermoplastic resin, a solid free radical polymerizable resin, and a solid epoxy resin. It is solid at room temperature, and has a melt flow rate of 10 g/10 min or more at a temperature of 190°C and a load of 2.16 kg. The thickness of the anisotropic bonding film is 50% or more and 300% or less of the average particle size of the solder particles.

Furthermore, the connector of the present invention is formed by bonding the electrode of the first electronic component to the electrode of the second electronic component using the above-mentioned anisotropic bonding film.

According to the present invention, since the solid resin is melted by heating, the solder particles are sandwiched between the electrodes and melted, so that electronic parts with electrodes with fine pitches can be joined.

10:LED components

11: The first conductive electrode

12: Second conductive type electrode

20: Substrate

21: 1st electrode

22: Second electrode

30: Anisotropic bonding film

31: Solder particles

32: Anisotropic conductive film

33: Solder joint

Figure 1 is a cross-sectional view schematically showing a portion of the joining step.

Figure 2 is a cross-sectional view showing an example of the structure of an LED mounting body.

Figure 3 is a schematic cross-sectional view of a portion of an anisotropic bonding film using the present technology.

Figure 4 is a microscope photograph of the solder bonding state on the substrate side after the LED chip is peeled off in Example 1-1.

Figure 5 is a microscope photograph of the solder joint state on the substrate side after the LED chip is peeled off in Comparative Example 1-1.

Figure 6 is a microscope photograph of the solder joint state on the substrate side after the LED chip is peeled off in Comparative Example 1-2.

Figure 7 is a microscope photograph of the solder joint state on the substrate side after the LED chip was peeled off in Comparative Examples 1-3.

Figure 8 is a microscope photograph of the solder joint state on the substrate side of an LED mounting body made using conventional solder paste after the LED chip is peeled off.

Hereinafter, the implementation form of the present invention will be described in detail according to the following sequence while referring to the drawings.

1. Manufacturing method of connector

2. Anisotropic bonding film (anisotropic bonding material)

3. Implementation examples

<1. Manufacturing method of connector>

The manufacturing method of the connector in this embodiment is as follows: an anisotropic bonding material containing a solid resin, solder particles, and a flux compound is placed between the electrode of the first electronic component and the electrode of the second electronic component with a thickness of more than 50% and less than 300% of the average particle size of the solder particles, and the electrode of the first electronic component and the electrode of the second electronic component are heat-bonded under no load. The solid resin is selected from at least one of thermoplastic resins, solid free radical polymerizable resins, and solid epoxy resins, is solid at room temperature, and has a melt flow rate of more than 10g/10min at a temperature of 190°C and a load of 2.16kg.

In this manual, the melt flow rate refers to the value measured at 190℃ and 2.16kg load according to the method for determining the melt flow rate of thermoplastic plastics in JIS K7210:1999, also known as melt mass flow rate (MFR). In addition, the room temperature refers to the range of 20℃±15℃ (5℃~35℃) specified in JISZ 8703. In addition, the connector refers to two materials or components electrically connected. In addition, the bonding refers to connecting two materials or components to each other. In addition, no load refers to the state without mechanical pressure.

The average particle size is the average value of the diameter of the major axis of the particles measured with N=50 or more, preferably N=100 or more, and more preferably N=200 or more in the observed image using a metal microscope, an optical microscope, an electron microscope such as a SEM (Scanning Electron Microscope), etc. When the particles are spherical, the average particle size is the average value of the diameter of the particles. Alternatively, it may be a measured value measured using a known image analysis software (WinROOF, Mitani Shoji Co., Ltd.) or a measured value (N=1000 or more) measured using an image-type particle size distribution measuring device (e.g., FPIA-3000 (Malvern Co., Ltd.)) for the observed image. The average particle size obtained by observing the image or image-type particle size distribution measuring device can be set as the average value of the maximum length of the particles. Furthermore, when making anisotropic bonding materials, the manufacturer's values such as the particle size (D50) at which the cumulative frequency in the particle size distribution is 50% and the arithmetic mean diameter (preferably based on volume) can be used, which can be easily obtained by laser diffraction and scattering methods.

As the first electronic component, preferably, it is a chip (component) such as LED (Light Emitting Diode) or driver IC (Integrated Circuit). As the second electronic component, if it is provided with wiring, it is not particularly limited, as long as it can be broadly defined as "a substrate provided with an electrode that can carry the first electronic component (so-called printed wiring board: PWB)". For example, it can be: a hard substrate, a glass substrate, a flexible substrate (FPC: Fexible Printed Circuits), a ceramic substrate, a plastic substrate and the like. The electrodes (electrode arrangement, electrode group) respectively provided on the first electronic component and the second electronic component are provided in an oppositely anisotropic manner, and the electrodes (electrode arrangement, electrode group) can also be provided in a manner that a plurality of first electronic components are mounted on one second electronic component. The first electronic component may be, in addition to LED (Light Emitting Diode), a chip (e.g., semiconductor element) such as a driver IC (Integrated Circuit), a flexible substrate (FPC: Flexible Printed Circuits), a resin-formed component, etc. provided with wiring (conducting material). The second electronic component is not particularly limited as long as it is provided with at least a portion of terminals corresponding to the terminals of the first electronic component, and can be broadly defined as "a substrate provided with electrodes that can carry the first electronic component (so-called printed wiring board: PWB)". In addition, the same components can be stacked and connected. The number of layers is not particularly limited as long as it does not hinder the connection. The same applies to the stacking of multiple heterogeneous components. The electrodes (electrode arrangements, electrode groups) respectively provided on the first electronic component and the second electronic component are arranged in a manner of oppositely anisotropically connected, and the electrodes (electrode arrangements, electrode groups) can also be arranged in a manner of carrying a plurality of first electronic components on one second electronic component. Furthermore, the above electronic components are preferably heat-resistant during the reflow step.

The anisotropic bonding material contains a solid resin, solder particles, and a flux compound. The solid resin is composed of one selected from a thermoplastic resin, a solid free radical polymerizable resin, and a solid epoxy resin, is solid at room temperature, and has an MFR of 10 g/10 min or more. The flux compound is preferably a carboxylic acid. In this way, a good solder connection can be obtained, and when mixed with an epoxy resin, it can function as a hardener for the epoxy resin. In addition, the flux compound is preferably a blocked carboxylic acid in which the carboxyl group is blocked by an alkyl vinyl ether. In this way, the temperature at which the flux effect and the hardener function are exerted can be controlled.

In addition, the resin flow rate of the anisotropic bonding material can be 1.3~2.5, and it is sometimes better to be set to less than 1.3. By making the resin flow rate become such a value, heat bonding can be performed under no load as described later. The resin flow rate can be measured according to the measurement method described in Japanese Patent Gazette No. 2016-178225. First, the anisotropic bonding film is cut into 2.0mm width, and the cut anisotropic bonding film is clamped with alkali-free glass (thickness 0.7μm) to perform a reflow step. The reflow can be set to the same conditions as those used for connection. Furthermore, the resin expansion before and after the reflow is measured, and the maximum value B of the width of the anisotropic bonding film after pressurization is divided by the width A (=2.0mm) before pressurization. The obtained value can be used as the resin flow. Moreover, it is more preferable to place the anisotropic bonding material without clamping it with alkali-free glass and perform the reflow step to obtain the above value. In the case where the resin flow of the anisotropic bonding material is small, there is a risk that the resin will not melt without load during the reflow step, which may hinder the clamping between the solder particles and the electrode. In this technology, since no load is applied when the adhesive resin is heated and hardened, it is more ideal to make the meltability higher than "the design of the adhesive resin based on the premise of applying a load (such as pressing with a tool like a general anisotropic connection)".

The anisotropic bonding material can be either a film-like anisotropic bonding film or a paste-like anisotropic bonding paste. Furthermore, the anisotropic bonding paste can be made into a film-like shape during connection, or can be made into a shape similar to a film by mounting components.

In the case of anisotropic bonding paste, as long as a specific amount can be uniformly applied on the substrate, for example, dispensing, stamping, screen printing and other coating methods can be used, and drying can be performed as needed. In the case of anisotropic bonding film, not only can the amount of anisotropic bonding material be made uniform by the film thickness, but it can also be laminated on the substrate to shorten the production time, so it is particularly good. In addition, it is easy to handle by making it into a film in advance, so it can be expected to improve the work efficiency.

The lower limit of the thickness of the anisotropic bonding material between the electrode of the first electronic component and the electrode of the second electronic component is 50% or more of the average particle size of the solder particles, preferably 80% or more, and more preferably 90% or more. If the thickness of the anisotropic bonding material is too thin, the solder particles become easily sandwiched between the electrodes, but there is a risk that the difficulty of forming a film will increase. In addition, the upper limit of the thickness of the anisotropic bonding material between the electrode of the first electronic component and the electrode of the second electronic component is 300% or less of the average particle size of the solder particles, preferably 200% or less, and more preferably 150% or less. If the thickness of the anisotropic bonding material is too thick, there is a risk that the bonding band will be hindered.

As a specific example of the method for manufacturing a connector, the method for manufacturing an LED mounting body is described below. The method for manufacturing an LED mounting body comprises: a step of placing an anisotropic bonding material having a thickness of 50% or more and 300% or less of the average particle size of solder particles on a substrate; a step of mounting an LED element on the anisotropic bonding material; and a step of bonding the electrode of the LED element and the electrode of the substrate by heat bonding under no load.

The step of setting the anisotropic bonding material may be a step of forming an anisotropic bonding paste into a film on the substrate before connection, or a temporary bonding step of bonding the anisotropic bonding film to the substrate at low temperature and low pressure as used in the previous anisotropic conductive film, or a lamination step of laminating the anisotropic bonding film on the substrate.

When the step of setting the anisotropic bonding material is a temporary bonding step, the anisotropic bonding film can be set on the substrate under known usage conditions. In this case, since only minimal changes such as changing tools from the previous device are required, the advantage of economy can be obtained.

When the step of setting the anisotropic bonding material is a lamination step, for example, a pressurized lamination machine is used to laminarize the anisotropic bonding film on the substrate. The lamination temperature is preferably 40°C or higher and 160°C or lower, more preferably 50°C or higher and 140°C or lower, and further preferably 60°C or higher and 120°C or lower. Furthermore, the lamination pressure is preferably 0.1MPa or higher and 10MPa or lower, more preferably 0.5MPa or higher and 5MPa or lower, and further preferably 1MPa or higher and 3MPa or lower. Furthermore, the lamination time is preferably 0.1sec or higher and 10sec or lower, preferably 0.5sec or higher and 8sec or lower, and further preferably 1sec or higher and 5sec or lower. In addition, vacuum pressurized lamination is also possible. If the conventional anisotropic conductive film is temporarily bonded using a heating and pressing tool, the width of the film is limited by the width of the tool. However, in the case of the lamination step, since the heating and pressing tool is not used, it can be expected that a relatively wide width can be loaded at one time. In addition, one anisotropic bonding film can be laminated on one substrate. In this way, since the heating and pressing tool does not need to be moved up and down and the anisotropic bonding film is not transported multiple times, the time for setting the anisotropic bonding material step can be shortened.

In the mounting step, for example, a plurality of LED components are arranged and mounted on the anisotropic bonding film. In the present technology, since the self-alignment of the solder particles cannot be expected, it is preferred to accurately align the LED components in the mounting step. Each LED component has, for example, a first conductive type electrode and a second conductive type electrode on a single side, and is arranged on an electrode of the substrate 30 corresponding to the first conductive type electrode and the second conductive type electrode.

Furthermore, in the step of providing the anisotropic conductive bonding material, the thickness of the anisotropic bonding material between the electrode of the LED element and the electrode of the substrate is made to be close to the average particle size of the solder particles, but it is not limited to this. In the mounting step, the thickness of the anisotropic bonding material can be made close to the average particle size of the solder particles by applying pressure (for example, temporary pressing). In the pressurizing step, for example, the pressure is applied from the side of the first electronic component mounted on the second electronic component, so that the thickness of the anisotropic bonding material between the electrode of the LED element and the electrode of the substrate is close to the average particle size of the solder particles. Here, if the thickness of the anisotropic bonding material is too large, there is a risk that it will hinder the pressurization, so it is better to set the thickness to the upper limit mentioned above. The so-called close to the average particle size means that after the pressurization step, the maximum diameter of the solder particles theoretically becomes the thickness of the anisotropic bonding material, so the thickness of the anisotropic bonding material can be regarded as the same as the maximum diameter of the solder particles. If the thickness unevenness is taken into account, it can also be set to 130% or less of the maximum diameter of the solder particles, preferably 120% or less. Furthermore, the lower limit of the pressure in the pressurizing step is preferably 0.2MPa or more, more preferably 0.4MPa or more, and the upper limit of the pressure in the pressurizing step can be 2.0MPa or less, preferably 1.0MPa or less, and more preferably 0.8MPa or less. Since the upper and lower limits sometimes vary depending on the specifications of the device, if the purpose of pressing the resin into the solder particle size can be achieved, it is not limited to the above numerical range. The pressurizing (temporary pressing) step is performed for the purpose of not melting the solder particles but shortening the distance between the electrode and the solder particles.

FIG1 is a cross-sectional view schematically showing a portion of the bonding step. In the bonding step, the electrodes 11, 12 of the LED element 10 and the electrodes 21, 21 of the substrate 20 are heat-bonded under no load. As a method of heat-bonding under no load without mechanical pressurization, there are atmospheric pressure reflow, vacuum reflow, atmospheric pressure oven, high pressure autoclave (pressure oven), etc. Among them, it is preferable to use vacuum reflow, high pressure autoclave, etc. that can eliminate bubbles contained in the bonding part. Since there is no load, there will be no excess resin flow compared to anisotropic conductive connection using general heating and pressurizing tools, so it can be expected that the effect of suppressing the clamping of bubbles can also be achieved.

The solid resin is melted by heating, and the solder particles 31 are sandwiched between the electrodes by the weight of the LED element 10. The solder particles 31 are melted by the main heating above the melting temperature of the solder, and the solder is wetted and diffused in the electrodes. The electrodes of the LED element 10 and the electrodes of the substrate 20 are joined by cooling. In the joining step, as an example, it is preferably to perform the main heating at a temperature of 200°C or more and 300°C or less, more preferably at a temperature of 220°C or more and 290°C or less, and further preferably at a temperature of 240°C or more and 280°C or less. In this way, the electrodes of the LED element 10 and the electrodes of the substrate 20 are joined, so that excellent conductivity, heat dissipation, and adhesion can be obtained. In the bonding step, since there is no load, the movement of solder particles is expected to be small and the capture efficiency of solder particles is high. In addition, since the content of solder particles is not expected to be self-aligned, and in the bonding step, the multiple solder particles contained in the anisotropic bonding film are not integrated, there are multiple solder bonding sites in one electrode. Here, the so-called solder bonding refers to melting the solder to connect the electrodes of the opposing electronic components.

FIG2 is a cross-sectional view showing an example of the structure of an LED mounting body. The LED mounting body is formed by connecting the LED element 10 and the substrate 20 using an anisotropic bonding film formed by dispersing solder particles 31 in a solid resin. That is, the LED mounting body has an LED element 10, a substrate 20, and solder particles 31, and has an anisotropic bonding film 32 formed by connecting the electrodes 11, 12 of the LED element 10 and the electrodes 21, 22 of the substrate 20, and the electrodes 11, 12 of the LED element 10 and the electrodes 21, 22 of the substrate 20 are bonded by a solder bonding portion 33, and the solid resin is filled between the LED element 10 and the substrate 20.

The LED element 10 has a first conductive electrode 11 and a second conductive electrode 12. When a voltage is applied between the first conductive electrode 11 and the second conductive electrode 12, carriers are concentrated in the active layer in the element and light is generated by recombination. The distance between the first conductive electrode 11 and the second conductive electrode 12 is, for example, 100 μm to 200 μm, 50 μm to 100 μm, or 20 μm to 50 μm, depending on the element size. There is no particular limitation on the LED element 10. For example, a blue LED with a peak wavelength of 400 nm to 500 nm can be used well.

The substrate 20 has a first electrode 21 and a second electrode 22 on the base material at positions corresponding to the first conductive type electrode 11 and the second conductive type electrode 12 of the LED element 10, respectively. Examples of the substrate 20 include a printed wiring board, a glass substrate, a flexible substrate, a ceramic substrate, a plastic substrate, etc. The electrode height of the printed wiring board is, for example, greater than 10 μm and less than 40 μm, the electrode height of the glass substrate is, for example, less than 3 μm, and the electrode height of the flexible substrate is, for example, greater than 5 μm and less than 20 μm.

The anisotropic bonding film 32 is formed by the anisotropic bonding material being in a film shape after the bonding step, and the electrodes 11, 12 of the LED element 10 and the electrodes 21, 22 of the substrate 20 are metal-bonded by the solder bonding portion 33, and the anisotropic bonding material is filled between the LED element 10 and the substrate 20.

As shown in FIG2 , the LED mounting body is formed by metal bonding between the terminals (electrodes 11, 12) of the LED element 10 and the terminals (electrodes 21, 22) of the substrate 20 via a solder joint 33, and a solid resin is filled between the LED element 20 and the substrate 30. This prevents moisture from penetrating between the LED element 10 and the substrate 20.

<2. Anisotropic bonding film (anisotropic bonding material)>

FIG3 is a schematic cross-sectional view of a portion of an anisotropic bonding film to which the present technology is applied. As shown in FIG3 , the anisotropic bonding film 30 contains a solid resin, solder particles 31, and a flux compound. In addition, in the anisotropic conductive film 30, a first film may be attached to the first surface and a second film may be attached to the second surface as needed. Furthermore, the anisotropic bonding film is formed by forming an anisotropic bonding material into a film shape.

The lower limit of the film thickness is more than 50% of the average particle size of the solder particles, preferably more than 80%, and more preferably more than 90%. If the film thickness is too thin, the solder particles become easily clamped between the electrodes, but there is a risk that it will be more difficult to make it into a film. In addition, the upper limit of the film thickness is less than 300% of the average particle size of the solder particles, preferably less than 200%, and more preferably less than 150%. If the film thickness is too thick, there is a risk that it will hinder the bonding. The film thickness can be measured using a known micrometer or digital thickness gauge (for example, Mitutoyo Co., Ltd.: MDE-25M, minimum display amount 0.0001mm) that can measure less than 1μm, preferably less than 0.1μm. The film thickness only needs to be measured at more than 10 locations and averaged. However, when the film thickness is thinner than the particle size, the contact-type thickness meter is not applicable, so it is better to use a laser displacement meter (e.g., KEYENCE Corporation, spectral interference displacement type SI-T series, etc.). Here, the so-called film thickness refers to the thickness of the resin layer only, not including the particle size.

[Solid resin]

The solid resin is solid at room temperature, and the MFR measured at a temperature of 190°C and a load of 2.16 kg is 10 g/10 min or more. The upper limit of the MFR is preferably 5000 g/10 min or less, more preferably 4000 g/10 min or less, and further preferably 3000 g/10 min or less. If the MFR is too large, it becomes difficult for the solid resin to be filled between the first electronic component and the second electronic component.

Thermoplastic resins are not particularly limited as long as they are solid at room temperature and satisfy the above-mentioned MFR. For example, they may be ethylene-vinyl acetate copolymers, ethylene-acrylic acid copolymers, polyamide resins, polyester resins, etc. In the case where the solid resin is a thermoplastic resin, sufficient bonding strength can be obtained because the electrode of the first electronic component and the electrode of the second electronic component are metal-bonded by hot melting. In addition, since thermoplastic resins are not accompanied by reactions, there is no need to pay attention to the shelf life (product life is longer than that of those using curable resins and curing agents (reaction initiators)), and handling becomes easy. In addition, since thermoplastic resin is solid at room temperature, the resin will not melt when used. However, if it melts, fillers can be added to prevent melting.

The solid free radical polymerizable resin is not particularly limited as long as it is solid at room temperature, satisfies the above MFR, and has one or more unsaturated double bonds in the molecule. For example, it can be unsaturated polyester (also known as vinyl ester), epoxy-modified or urethane-modified (meth) acrylate, etc. This can maintain the film shape.

The solid epoxy resin is not particularly limited as long as it is solid at room temperature, satisfies the above-mentioned MFR, and has one or more epoxy groups in the molecule. For example, it may be bisphenol A type epoxy resin, biphenyl type epoxy resin, etc. In this way, the film shape can be maintained.

In addition, the anisotropic bonding film may further contain a liquid radical polymerizable resin that is liquid at room temperature and a polymerization initiator. The liquid radical polymerizable resin is not particularly limited as long as it is liquid at room temperature, and may be, for example, acrylate, methacrylate, unsaturated polyester, etc., and may also be modified by amine. By using a liquid radical polymerizable resin, not only can the anisotropic bonding film be given viscosity, thereby improving the lamination properties to the adherend, but also the fluidity of the adhesive as a whole during installation can be improved.

The amount of the liquid radical polymerizable resin blended relative to 100 parts by mass of the solid resin is preferably 100 parts by mass or less, more preferably 80 parts by mass or less, and further preferably 70 parts by mass or less. If the amount of the liquid radical polymerizable resin blended increases, it becomes more difficult to maintain the film shape.

The polymerization initiator is preferably an organic peroxide such as diacyl peroxide. In addition, the reaction starting temperature of the polymerization initiator is preferably higher than the melting point of the solder particles. In this way, since the solid resin begins to harden after flowing, a good solder joint can be obtained.

In addition, the anisotropic bonding film may further contain an epoxy resin that is liquid at room temperature and a hardener. The liquid epoxy resin is not particularly limited as long as it is liquid at room temperature. For example, it may be a bisphenol A type epoxy resin, a bisphenol F type epoxy resin, or an amine-modified epoxy resin.

The amount of liquid epoxy resin blended relative to 100 parts by mass of solid resin is preferably 160 parts by mass or less, more preferably 100 parts by mass or less, and further preferably 70 parts by mass or less. If the amount of liquid epoxy resin blended increases, it becomes more difficult to maintain the film shape.

The hardener is not particularly limited as long as it is a thermal hardener that starts hardening by heat. Examples include: anionic hardeners such as amines and imidazoles; cationic hardeners such as cobalt salts. In addition, the hardener can also be microencapsulated to obtain resistance to the solvent used in the film formation.

Furthermore, the hardener may be a carboxylic acid, or a blocked carboxylic acid in which the carboxyl group is blocked by an alkyl vinyl ether. That is, the hardener may also be a flux compound.

[Solder particles]

The solder particles can be randomly mixed and dispersed in the anisotropic bonding film, or can be arranged when viewed from above. The overall arrangement of the solder particles in the anisotropic bonding film when viewed from above can be regular or random. As a pattern of regular arrangement, there can be listed: square lattice, hexagonal lattice, rhombus lattice, rectangular lattice and other lattice arrangements, without special restrictions. In addition, as a pattern of random arrangement, it is preferred that the solder particles exist without contacting each other when the film is viewed from above, and the solder particles also exist without overlapping each other in the film thickness direction. In addition, it is preferred that more than 95% of the total number of solder particles in the anisotropic bonding film exist independently without contacting other solder particles. This can be confirmed by using a known metal microscope or optical microscope to randomly extract 5 or more locations of an area of ¹ mm2 or more of the film in a top view, and observe 200 or more, preferably 1000 or more solder particles. In addition, when the solder particles are arranged in the anisotropic bonding film in a top view, the solder particles can also be aligned at the same position in the film thickness direction.

Furthermore, the solder particles may be arranged in the form of agglomerates formed by a plurality of agglomerates. In this case, the arrangement of the agglomerates of the anisotropic bonding film in a top view may be regular or random, similar to the arrangement of the solder particles described above. Furthermore, it is preferred that the agglomerates exist without contacting each other in a top view of the film, and the agglomerates also exist without overlapping each other in the film thickness direction. The average particle size of the solder particles of each agglomerate may be measured in the same manner as the above average particle size.

The average particle size of the solder particles is preferably less than 1/3 of the distance between the electrodes of the semiconductor element being connected, more preferably less than 1/4, and further preferably less than 1/5. If the average particle size of the solder particles is larger than 1/3 of the distance between the electrodes of the semiconductor element, the possibility of a short circuit increases. As a specific particle size of the solder particles, it is preferably greater than 1 μm and less than 30 μm. If the average particle size is less than 1 μm, a good solder joint with the electrode portion may not be obtained, and reliability tends to deteriorate. In addition, in order to make the coating thickness of the film constant, the lower limit of the average particle size of the solder particles is preferably greater than 3 μm, and more preferably greater than 5 μm. Furthermore, if the average particle size of the solder particles is greater than 30μm, fine-pitch connection becomes difficult. The upper limit of the average particle size of the solder particles is less than 30μm, preferably less than 25μm, and more preferably less than 20μm. Depending on the connection object, the upper limit of the average particle size of the solder particles is preferably set to less than 15μm. Furthermore, in the case of an agglomerate formed by agglomeration of multiple solder particles, the size of the agglomerate can also be set to be equal to the average particle size of the above-mentioned solder particles. In the case of making an agglomerate, the average particle size of the solder particles can also be set to be smaller than the above value. The size of each solder particle can be observed and obtained using an electron microscope.

Solder particles can be appropriately selected from Sn-Pb, Pb-Sn-Sb, Sn-Sb, Sn-Pb-Bi, Bi-Sn, Sn-Cu, Sn-Pb-Cu, Sn-In, Sn-Ag, Sn-Pb-Ag, Pb-Ag, etc. specified in JIS Z 3282-1999, depending on the electrode material or connection conditions. The melting point of the solder particles is preferably above 110°C and below 180°C, more preferably above 120°C and below 160°C, and further preferably above 130°C and below 150°C. In addition, the solder particles can also be surface activated so that the flux compound is directly bonded to the surface. By activating the surface, the metal bonding with the electrode portion can be promoted.

The lower limit of the mass ratio range of the solder particle blending amount is preferably 20 wt% or more, more preferably 30 wt% or more, and further preferably 40 wt% or more. The lower limit of the mass ratio range of the solder particle blending amount is preferably 80 wt% or less, more preferably 70 wt% or less, and further preferably 60 wt% or less. Furthermore, the lower limit of the volume ratio range of the solder particle blending amount is preferably 5 vol% or more, more preferably 10 vol% or more, and further preferably 15 vol% or more. The upper limit of the volume ratio range of the solder particle blending amount is preferably 30 vol% or less, more preferably 25 vol% or less, and further preferably 20 vol% or less. By making the amount of solder particles mixed satisfy the above-mentioned mass ratio range or volume ratio range, excellent conductivity, heat dissipation, and adhesion can be obtained. When the solder particles are present in the adhesive, the volume ratio can be used, and when the anisotropic conductive bonding material is manufactured (before the solder particles are present in the adhesive), the mass ratio can be used. The mass ratio can be converted into the volume ratio based on the specific gravity of the mixture or the mixing ratio. If the amount of solder particles mixed is too small, it becomes impossible to obtain excellent conductivity, heat dissipation, and adhesion. If the amount of solder particles mixed is too large, the anisotropy is damaged and it becomes impossible to obtain excellent conduction reliability.

[Flux compounds]

The flux compound removes foreign matter or oxide film on the electrode surface, or prevents oxidation of the electrode surface, or reduces the surface tension of the molten solder. As the flux compound, for example, it is preferred to use carboxylic acids such as acetopropionic acid, succinic acid, oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, and sebacic acid. In this way, a good solder connection can be obtained, and when mixed with epoxy resin, it can function as a hardener for epoxy resin.

In addition, as a flux compound, it is preferred to use a blocked carboxylic acid formed by blocking the carboxyl group with an alkyl vinyl ether. In this way, the temperature at which the flux effect and the curing agent function are exerted can be controlled. In addition, since the solubility in the resin is improved, the mixing and uneven coating during film formation can be improved. In addition, the decapping temperature is preferably above the melting point of the solder particles. In this way, a good solder connection can be obtained, and when an epoxy resin is mixed, since the epoxy resin starts to harden after flowing, a good solder joint can be obtained.

[Other additives]

In addition to the above-mentioned solid resin, solder particles, and flux compounds, various additives can be mixed into the anisotropic bonding film within the scope that does not damage the present invention. For example, the anisotropic bonding film can also contain inorganic fillers, organic fillers, metal fillers, coupling agents, leveling agents, stabilizers, and thixotropic agents. From the perspective of connection stability, the particle size of the inorganic filler, organic filler, and metal filler is smaller than the average particle size of the solder particles, for example, nano fillers of 10-1000nm, micro fillers of 1-10μm, etc. are used.

As inorganic fillers, there are: silicon dioxide, aluminum oxide, aluminum hydroxide, titanium oxide, aluminum hydroxide, calcium hydroxide, calcium carbonate, talc, zinc oxide, zeolite, etc. Silicon dioxide can be added for the purpose of improving moisture absorption reliability, titanium oxide can be added for the purpose of improving light reflection, or aluminum hydroxide, calcium hydroxide, etc. can be added for the purpose of preventing corrosion caused by acid.

Examples of organic fillers include acrylic resins, carbon, core-shell particles, etc. By adding organic fillers, effects such as preventing agglomeration and light scattering can be achieved.

As metal fillers, Ni, Cu, Ag, Au, and alloys thereof can be listed. For example, Cu fillers can prevent corrosion of electrodes, etc. by forming complexes with acids. Furthermore, metal fillers may or may not contribute to conduction. The amount of metal fillers added can be adjusted to a level that does not cause short circuits including solder particles.

Furthermore, the above-mentioned anisotropic bonding film can be obtained, for example, by mixing a solid resin, solder particles, and a flux compound in a solvent, applying the mixture to a specific thickness on a stripping treatment film by a rod coater, and then drying to volatilize the solvent. Furthermore, in order to improve the dispersibility of the solder particles, it is preferred to apply high shear in a state containing a solvent. For example, a known batch planetary stirring device can be used. It can also be capable of being carried out in a vacuum environment. Furthermore, the solvent residue of the anisotropic bonding film is preferably less than 2%, and more preferably less than 1%.

Implementation example

<3.1 First Implementation Example>

In the first embodiment, an anisotropic bonding film containing a thermoplastic resin is used to make an LED mounting body, and the forward voltage, chip shear strength, and bonding state of the LED mounting body are evaluated.

[Determination of melt flow rate of solid resin]

According to the method for determining the melt flow rate of plastics in JIS K7210:1999, the melt flow rate measuring device (product name: Melt Indexer G-02, manufactured by Toyo Seiki Seisaku-sho Co., Ltd.) was used to measure the melt flow rate of thermoplastic resins A-E at a temperature of 190°C and a load of 2.16 kg.

A: Polyester resin, Primalloy A1500 (Mitsubishi Chemical), MFR=11g/10min

B: Ethylene-vinyl acetate copolymer, EVAFLEX EV205WR (Mitsui DuPont Chemicals Co., Ltd.), MFR = 800g/10min

C: Ethylene acrylic acid copolymer resin, Nucrel N1050H (DuPont), MFR=500g/10min

D: Polyamide resin, Griltex D1666A (EMS GRIVORY), MFR = 130g/10min

E: Phenoxy resin, Phenotohto YP70 (Nippon Steel & Sumitomo Metal Chemicals Co., Ltd.), MFR = 1g/10min

[Production of LED mounting body]

Prepare LED chips (LED chips for Dexerials evaluation, size 45mil, If=350mA, Vf=3.1V, Au-Sn pads, P-electrode and N-electrode with pad size 300μm×800μm, and pad distance (P-electrode and N-electrode distance) 150μm) and substrates (ceramic substrates for Dexerials evaluation, 18μm thick Cu pattern, Ni-Au coating, pattern gap 50μm). Laminate the anisotropic bonding film on the substrate under the conditions of 80℃-2MPa-3sec, align the LED chips and mount them, then install the LED chips by reflow (peak temperature 260℃).

[Measurement of forward voltage]

The rated current If=350mA is made to flow through the LED chip through the pattern of the substrate, and the forward voltage value Vf of the LED chip is measured. The situation where the reading cannot be made due to excessive voltage is set to "OPEN".

[Determination of chip shear strength]

The chip shear strength of the LED chip was measured using a bonding tester (product number: PTR-1100, manufactured by Lisko Corporation) at a measuring speed of 20μm/sec.

[Observation of the bonding state]

The solder joint state on the substrate side after the LED chip is peeled off is observed using an optical microscope to measure the chip shear strength.

[Determination of film thickness]

The film thickness is measured at more than 10 locations using a digital micrometer, and the average value is taken as the film thickness.

<Implementation Example 1-1>

As shown in Table 1, thermoplastic resin A, flux compound (glutaric acid (1,3-propanedicarboxylic acid), Wako Pure Chemical Industries, Ltd.), solder particles (42Sn-58Bi, Type 6, melting point 139°C, average particle size 10μm, Mitsui Metals, Ltd.), and titanium oxide (average particle size 0.21μm, CR-60, Ishihara Industry Co., Ltd.) were mixed with specific mass fractions to produce an anisotropic bonding film.

After dispersing solder particles in a toluene solution containing a mixture of thermoplastic resin A, flux compound, and titanium oxide, the film was coated on a peeling PET (PET-02-BU, Shikoku-Tohcello (stock)) using a gap coater in a manner such that the thickness after toluene drying was 20μm. Toluene drying was performed at 80℃-10min. The measured film thickness after drying was 20μm.

Table 1 shows the results of the measurement of the forward voltage and chip shear strength of the LED mounting body made using anisotropic bonding film. The forward voltage is 3.1V and the chip shear strength is 40N/chip.

Figure 4 is a microscope photograph of the solder joint state on the substrate side after the LED chip of Example 1-1 was peeled off. The solder is wet and diffused on the LED chip side and the substrate side, and the solder joint state is good. In addition, it can be confirmed that there are multiple solder joints in one electrode.

<Implementation Example 1-2>

As shown in Table 1, thermoplastic resin B was used instead of thermoplastic resin A, and the anisotropic bonding film was prepared in the same manner as in Example 1-1. The LED mounting body prepared using the anisotropic bonding film had a forward voltage of 3.0 V and a chip shear strength of 45 N/chip.

<Implementation Example 1-3>

As shown in Table 1, thermoplastic resin C was used instead of thermoplastic resin A, and the anisotropic bonding film was prepared in the same manner as in Example 1-1. The LED mounting body prepared using the anisotropic bonding film had a forward voltage of 3.0 V and a chip shear strength of 43 N/chip.

<Implementation Example 1-4>

As shown in Table 1, thermoplastic resin D was used instead of thermoplastic resin A, and the anisotropic bonding film was prepared in the same manner as in Example 1-1. The LED mounting body prepared using the anisotropic bonding film had a forward voltage of 3.0 V and a chip shear strength of 46 N/chip.

<Implementation Example 1-5>

As shown in Table 1, the thickness of the anisotropic bonding film was set to 30 μm, and the anisotropic bonding film was prepared in the same manner as in Example 1-1. The forward voltage of the LED mounting body prepared using the anisotropic bonding film was 3.1 V, and the chip shear strength was 47 N/chip.

<Comparison Example 1-1>

As shown in Table 1, thermoplastic resin E was used instead of thermoplastic resin A, and the anisotropic bonding film was prepared in the same manner as in Example 1-1. The forward voltage of the LED mounting body prepared using the anisotropic bonding film became OPEN, and the chip shear strength was 19N/chip.

Figure 5 is a microscope photograph of the solder joint state on the substrate side after the LED chip was peeled off in Comparative Example 1-1. Since the melt flow rate of thermoplastic resin E is 1g/10min, the resin hardly flows, and the solder particles do not contact the pad of the LED chip or the pattern of the substrate and do not melt.

<Comparison Example 1-2>

As shown in Table 1, the anisotropic bonding film was prepared in the same manner as Example 1-1 except that the flux compound was not mixed. The forward voltage of the LED mounting body prepared using the anisotropic bonding film became OPEN, and the chip shear strength was 18N/chip.

Figure 6 is a microscope photograph of the solder joint state on the substrate side after the LED chip was peeled off in Comparative Example 1-2. Since the flux compound was not mixed, the solder particles did not melt.

<Comparison Example 1-3>

As shown in Table 1, the thickness of the anisotropic bonding film was set to 40 μm, and the anisotropic bonding film was prepared in the same manner as in Example 1-1. The forward voltage of the LED mounting body prepared using the anisotropic bonding film became OPEN, and the chip shear strength was 25 N/chip.

Figure 7 is a microscope photograph of the solder bonding state on the substrate side after the LED chip was peeled off in Comparative Example 1-3. Since the thickness of the anisotropic bonding film is relatively thick, at 40μm, the solder particles are not sufficiently clamped between the electrodes, and the solder bonding is insufficient. The wetting and diffusion of solder particles are only found on the side of the LED chip and the side of the substrate.

In Comparative Example 1-1, since thermoplastic resin E with a melt flow rate of 1g/10min was used, the resin had poor fluidity, the solder particles did not melt, and did not bond with the electrode of the connected body. Therefore, the forward voltage could not be measured. In addition, since the resin did not flow sufficiently and no solder joint was formed, the result was that the adhesion of the LED chip was weak and the chip shear strength was low.

In Comparative Example 1-2, since the flux compound was not mixed, the solder particles did not melt and the forward voltage could not be measured.

In Comparative Example 1-3, since a 40μm thick anisotropic bonding film was used, which is 4 times thicker than the average particle size of the solder particles of 10μm, no solder joint was formed and the forward voltage could not be measured. In addition, the chip shear strength was also low.

On the other hand, in Examples 1-1 to 1-5, since thermoplastic resins A-D with a melt flow rate of more than 1g/10min are used, and an anisotropic bonding film with a thickness of 20-30μm, which is 2-3 times the average particle size of solder particles of 10μm, is used, the resin melts and flows, and solder bonding is performed between the electrodes of the connected body by solder particles, and a value close to the rated voltage of 3.1V can be obtained. In addition, the chip shear strength is also good.

<3.2 Second Implementation Example>

In the second embodiment, an anisotropic bonding film containing a free radical polymerizable resin is used to make an LED mount, and the forward voltage, insulation and die shear strength of the LED mount are evaluated. Since the manufacture of the LED mount, the forward voltage of the LED mount, and the measurement of the die shear strength are the same as those in the first embodiment, the description is omitted here.

[Determination of melt flow rate of solid resin]

According to the method for determining the melt flow rate of plastics in JIS K7210:1999, the melt flow rate measuring device (product name: Melt Indexer G-02, manufactured by Toyo Seiki Seisaku-sho) was used to measure the melt flow rate of thermoplastic resins A-C, E and solid free radical polymerizable resins at a temperature of 190°C and a load of 2.16 kg.

A: Polyester resin, Primalloy A1500 (Mitsubishi Chemical), MFR=11g/10min

B: Ethylene-vinyl acetate copolymer, EVAFLEX EV205WR (Mitsui DuPont Chemicals Co., Ltd.), MFR = 800g/10min

C: Ethylene acrylic acid copolymer resin, Nucrel N1050H (DuPont), MFR=500g/10min

E: Phenoxy resin, Phenotohto YP70 (Nippon Steel & Sumitomo Metal Chemicals Co., Ltd.), MFR = 1g/10min

Solid free radical polymerizable resin: vinyl ester resin, Lipoxy VR-90, Showa Denko Co., Ltd., MFR=100g/10min

[Evaluation of Insulation]

A reverse current of 0.1μA is made to flow in the LED chip through the pattern of the substrate. The situation where no current flows is evaluated as "OK", and the situation where current flows is evaluated as "NG".

<Implementation Example 2-1>

As shown in Table 2, a thermoplastic resin A, a liquid radical polymerizable resin (bisphenol A diglycidyl ether, Avolites 4000, Kyoeisha Chemical Co., Ltd.), an initiator (diacyl peroxide, Perhexa 25B, NOF Corporation), a flux compound A (glutaric acid (1,3-propanedicarboxylic acid), Wako Pure Chemical Industries, Ltd.), solder particles (42Sn-58Bi, Type 6, melting point 139°C, average particle size 10μm, Mitsui Metals Co., Ltd.), and titanium oxide (average particle size 0.21μm, CR-60, Ishihara Industry Co., Ltd.) were mixed with specific mass fractions to produce an anisotropic bonding film.

Thermoplastic resin A and liquid free radical polymerizable resin were mixed and dissolved in toluene, flux compound A and titanium oxide were added thereto, and dispersed using a three-roll mill (passed 3 times with a gap of 10μm), and then the initiator and solder particles were dispersed to obtain a resin solution. The resin solution was coated on a peeling PET (PET-02-BU, Shikoku-Tohcello (stock)) using a gap coater in a manner such that the thickness after toluene drying was 20μm. Toluene drying was performed under the condition of 80℃-10min.

As shown in Table 2, the forward voltage of the LED mount made using anisotropic bonding film is 3.1V, the insulation is OK, and the chip shear strength is 42N/chip.

<Implementation Example 2-2>

As shown in Table 2, thermoplastic resin B was used instead of thermoplastic resin A, and the anisotropic bonding film was prepared in the same manner as in Example 2-1. The LED mounting body prepared using the anisotropic bonding film had a forward voltage of 3.0 V, an insulation property of OK, and a chip shear strength of 46 N/chip.

<Implementation Example 2-3>

As shown in Table 2, thermoplastic resin C was used instead of thermoplastic resin A, and the anisotropic bonding film was prepared in the same manner as in Example 2-1. The LED mounting body prepared using the anisotropic bonding film had a forward voltage of 3.0 V, an insulation property of OK, and a chip shear strength of 41 N/chip.

<Implementation Example 2-4>

As shown in Table 2, a solid free radical polymerizable resin was used instead of thermoplastic resin A, and an anisotropic bonding film was prepared in the same manner as in Example 2-1. The LED mounting body prepared using the anisotropic bonding film had a forward voltage of 3.0 V, an insulation property of OK, and a chip shear strength of 47 N/chip.

<Implementation Example 2-5>

As shown in Table 2, flux compound B (blocked carboxylic acid, Santacid G, NOF Corporation) was used instead of flux compound A, and the anisotropic bonding film was prepared in the same manner as in Example 2-1. The LED mounting body prepared using the anisotropic bonding film had a forward voltage of 3.0 V, an insulation property of OK, and a chip shear strength of 46 N/chip.

<Implementation Example 2-6>

As shown in Table 2, the thickness of the anisotropic bonding film was set to 30 μm, and the anisotropic bonding film was prepared in the same manner as in Example 2-1. The forward voltage of the LED mounting body prepared using the anisotropic bonding film was 3.1 V, the insulation was OK, and the chip shear strength was 49 N/chip.

<Comparison Example 2-1>

As shown in Table 2, after the thermoplastic resin E is dissolved by using a reactive diluent (tetrahydrofurfuryl acrylate, Viscoat #150, Osaka Organic Chemical Industry Co., Ltd.), a free radical polymerizable resin, an initiator, a flux compound A, titanium oxide, and solder particles are mixed and dispersed to prepare an anisotropic bonding paste.

Prepare LED chips (Dexerials evaluation LED chips, size 45mil, If=350mA, Vf=3.1V, Au-Sn pads, pad size 300μm×800μm, pad spacing 200μm) and substrates (Dexerials evaluation ceramic substrates, 18μm thick Cu patterns, Ni-Au coating, pattern spacing (gap) 50μm). Use a 30μm thick mask to apply anisotropic bonding paste on the substrate, align the LED chips and mount them, then install the LED chips by reflow (peak temperature 260℃).

As shown in Table 2, the forward voltage of the LED mount made using anisotropic bonding paste is 3.0V, the insulation is NG, and the chip shear strength is 45N/chip.

<Comparison Example 2-2>

As shown in Table 2, thermoplastic resin E was used instead of thermoplastic resin A, and the anisotropic bonding film was prepared in the same manner as in Example 2-1. The forward voltage of the LED mounting body prepared using the anisotropic bonding film was OPEN, the insulation was OK, and the chip shear strength was 19N/chip.

<Comparison Example 2-3>

As shown in Table 2, the anisotropic bonding film was prepared in the same manner as Example 2-1 except that the flux compound was not mixed. The forward voltage of the LED mounting body prepared using the anisotropic bonding film was OPEN, the insulation was OK, and the chip shear strength was 19N/chip.

<Comparison Example 2-4>

As shown in Table 2, the thickness of the anisotropic bonding film was set to 40 μm, and the anisotropic bonding film was prepared in the same manner as in Example 2-1. The forward voltage of the LED mounting body prepared using the anisotropic bonding film was OPEN, the insulation was OK, and the chip shear strength was 26 N/chip.

In Comparative Example 2-1, since a thermoplastic resin E with a melt flow rate of 1g/10min was used to apply anisotropic bonding material in a paste form, a short circuit caused by solder bonding occurred between adjacent terminals of the substrate.

In Comparative Example 2-2, since thermoplastic resin E with a melt flow rate of 1g/10min was used, the resin had poor fluidity, the solder particles did not melt, and did not bond with the electrode of the connected body. Therefore, the forward voltage could not be measured. In addition, since the resin did not flow sufficiently and no solder joint was formed, the LED chip had weak adhesion and low chip shear strength.

In Comparative Example 2-3, since the flux compound was not mixed, the solder particles did not melt and the forward voltage could not be measured.

In Comparative Example 2-4, since a 40μm thick anisotropic bonding film was used, which is 4 times thicker than the average particle size of the solder particles of 10μm, no solder joint was formed and the forward voltage could not be measured. In addition, the chip shear strength was also lower.

On the other hand, in Examples 2-1 to 2-5, since thermoplastic resins A-D with a melt flow rate of more than 1g/10min are used, and an anisotropic bonding film with a thickness of 20-30μm, which is 2-3 times the average particle size of the solder particles of 10μm, is used, the resin melts and flows, and solder bonding is performed between the electrodes of the connected body by soldering the solder particles, and a value close to the rated voltage of 3.1V can be obtained. In addition, the chip shear strength is also good.

<3.3 Implementation Example 3>

In the third embodiment, an anisotropic bonding film containing epoxy resin is used to make an LED mount, and the forward voltage, insulation and chip shear strength of the LED mount are evaluated. Since the manufacture of the LED mount, the measurement of the forward voltage of the LED mount, and the chip shear strength are the same as those in the first embodiment, and the evaluation of the insulation of the LED mount is the same as that in the second embodiment, the description is omitted here.

[Determination of melt flow rate of solid resin]

According to the method for determining the melt flow rate of plastics in JIS K7210:1999, the melt flow rate measuring device (product name: Melt Indexer G-02, manufactured by Toyo Seiki Seisaku-sho) was used to measure the melt flow rate of thermoplastic resins A-C, E and solid epoxy resin at a temperature of 190°C and a load of 2.16 kg.

A: Polyester resin, Primalloy A1500 (Mitsubishi Chemical), MFR=11g/10min

B: Ethylene-vinyl acetate copolymer, EVAFLEX EV205WR (Mitsui DuPont Chemicals Co., Ltd.), MFR = 800g/10min

C: Ethylene acrylic acid copolymer resin, Nucrel N1050H (DuPont), MFR=500g/10min

E: Phenoxy resin, Phenotohto YP70 (Nippon Steel & Sumitomo Metal Chemicals Co., Ltd.), MFR = 1g/10min

Solid epoxy resin: Bisphenol A epoxy resin, 1001, Mitsubishi Chemical Co., Ltd., MFR=2600g/10min

<Implementation Example 3-1>

As shown in Table 3, thermoplastic resin A, liquid epoxy resin (bisphenol A type epoxy resin, YL980, Mitsubishi Chemical Co., Ltd.), hardener A (anionic hardener, microcapsule type imidazole hardener, HX3941HP, Asahi Kasei Co., Ltd.), flux compound A (glutaric acid (1,3-propanedicarboxylic acid), Wako Pure Chemical Industries, Ltd.), solder particles (42Sn-58Bi, Type 6, melting point 139°C, average particle size 10μm, Mitsui Metals Co., Ltd.), and titanium oxide (average particle size 0.21μm, CR-60, Ishihara Sangyo Co., Ltd.) were mixed with specific mass fractions to produce an anisotropic bonding film.

Thermoplastic resin A and liquid epoxy resin were mixed and dissolved in toluene, and flux compound A and titanium oxide were added thereto. After being dispersed using a three-roll grinder (passed 3 times with a gap of 10μm), hardener A and solder particles were dispersed to obtain a resin solution. The resin solution was coated on a peeling PET (PET-02-BU, Shikoku-Tohcello (stock)) using a gap coater in a manner such that the thickness after toluene drying was 20μm. Toluene drying was performed under the condition of 80℃-10min.

As shown in Table 3, the forward voltage of the LED mount made using anisotropic bonding film is 3.1V, the insulation is OK, and the chip shear strength is 43N/chip.

<Implementation Example 3-2>

As shown in Table 3, thermoplastic resin B was used instead of thermoplastic resin A, and the anisotropic bonding film was prepared in the same manner as in Example 3-1. The LED mounting body prepared using the anisotropic bonding film had a forward voltage of 3.0 V, an insulation property of OK, and a chip shear strength of 46 N/chip.

<Implementation Example 3-3>

As shown in Table 3, thermoplastic resin C was used instead of thermoplastic resin A, and the anisotropic bonding film was prepared in the same manner as in Example 3-1. The LED mounting body prepared using the anisotropic bonding film had a forward voltage of 3.0 V, an insulation property of OK, and a chip shear strength of 41 N/chip.

<Implementation Example 3-4>

As shown in Table 3, a solid epoxy resin was used instead of thermoplastic resin A, and an anisotropic bonding film was prepared in the same manner as in Example 3-1. The LED mounting body prepared using the anisotropic bonding film had a forward voltage of 3.0 V, an insulation property of OK, and a chip shear strength of 47 N/chip.

<Implementation Example 3-5>

As shown in Table 3, hardener B (cationic hardener, cobalt salt, San-Aid SI-80L, manufactured by Sanshin Chemical Co., Ltd.) was used instead of hardener A, and the blending ratio of the liquid epoxy resin was adjusted. The anisotropic bonding film was prepared in the same manner as in Example 3-1. The LED mounting body prepared using the anisotropic bonding film had a forward voltage of 3.0 V, an insulation property of OK, and a chip shear strength of 46 N/chip.

<Implementation Example 3-6>

As shown in Table 3, flux compound B (blocked carboxylic acid, Santacid G, NOF Corporation) was used instead of flux compound A, and the anisotropic bonding film was prepared in the same manner as in Example 3-1. The LED mounting body prepared using the anisotropic bonding film had a forward voltage of 3.0 V, an insulation property of OK, and a chip shear strength of 44 N/chip.

<Implementation Example 3-7>

As shown in Table 3, the thickness of the anisotropic bonding film was set to 30 μm, and the anisotropic bonding film was prepared in the same manner as in Example 3-1. The forward voltage of the LED mounting body prepared using the anisotropic bonding film was 3.1 V, the insulation was OK, and the chip shear strength was 49 N/chip.

<Comparison Example 3-1>

As shown in Table 3, an anisotropic bonding paste is prepared by mixing and dispersing liquid epoxy resin, hardener A, flux compound A, titanium oxide, and solder particles.

Prepare LED chips (Dexerials evaluation LED chips, size 45mil, If=350mA, Vf=3.1V, Au-Sn pads, pad size 300μm×800μm, pad spacing 200μm) and substrates (Dexerials evaluation ceramic substrates, 18μm thick Cu patterns, Ni-Au coating, pattern spacing (gap) 50μm). Use a 30μm thick mask to apply anisotropic bonding paste on the substrate, align the LED chips and mount them, then install the LED chips by reflow (peak temperature 260℃).

As shown in Table 3, the forward voltage of the LED mount made using anisotropic bonding paste is 3.0V, the insulation is NG, and the chip shear strength is 45N/chip.

<Comparison Example 3-2>

As shown in Table 2, thermoplastic resin E was used instead of thermoplastic resin A, and the anisotropic bonding film was prepared in the same manner as in Example 3-1. The forward voltage of the LED mounting body prepared using the anisotropic bonding film was OPEN, the insulation was OK, and the chip shear strength was 19N/chip.

<Comparison Example 3-3>

As shown in Table 3, the anisotropic bonding film was prepared in the same manner as Example 3-1 except that the flux compound was not mixed. The forward voltage of the LED mounting body prepared using the anisotropic bonding film was OPEN, the insulation was OK, and the chip shear strength was 19N/chip.

<Comparison Example 3-4>

As shown in Table 3, the thickness of the anisotropic bonding film was set to 40 μm, and the anisotropic bonding film was prepared in the same manner as in Example 3-1. The forward voltage of the LED mounting body prepared using the anisotropic bonding film was OPEN, the insulation was OK, and the chip shear strength was 26 N/chip.

In Comparative Example 3-1, since liquid epoxy was used to apply the paste-like anisotropic bonding material, a short circuit caused by solder bonding occurred between adjacent terminals on the substrate.

In Comparative Example 3-2, since thermoplastic resin E with a melt flow rate of 1g/10min was used, the resin had poor fluidity, the solder particles did not melt, and did not bond with the electrode of the connected body. Therefore, the forward voltage could not be measured. In addition, since the resin did not flow sufficiently and no solder joint was formed, the LED chip had weak adhesion and low chip shear strength.

In Comparative Example 3-3, since the flux compound was not mixed, the solder particles did not melt and the forward voltage could not be measured.

In Comparative Example 3-4, since a 40μm thick anisotropic bonding film was used, which is 4 times thicker than the average particle size of the solder particles of 10μm, no solder joint was formed and the forward voltage could not be measured. In addition, the chip shear strength was also lower.

On the other hand, in Examples 3-1 to 3-7, since thermoplastic resins A-D with a melt flow rate of more than 1g/10min are used, and an anisotropic bonding film with a thickness of 20-30μm, which is 2-3 times the average particle size of the solder particles of 10μm, is used, the resin melts and flows, and solder bonding is performed between the electrodes of the connected body by soldering the solder particles, and a value close to the rated voltage of 3.1V can be obtained. In addition, the chip shear strength is also good. In addition, even if the capped flux compound formed by capping the carboxyl group with vinyl ether in Example 3-6 is used, good results can be obtained.

<3.4 Implementation Example 4>

In the fourth embodiment, an LED mounting body is manufactured using an anisotropic bonding film containing carboxylic acid as a flux compound, and the forward voltage, insulation and chip shear strength of the LED mounting body are evaluated. Since the manufacture of the LED mounting body, the measurement of the forward voltage of the LED mounting body, and the chip shear strength are the same as those in the first embodiment, and the evaluation of the insulation of the LED mounting body is the same as that in the second embodiment, the description is omitted here.

[Determination of melt flow rate of solid resin]

According to the method for determining the melt flow rate of plastics in JIS K7210:1999, the melt flow rate measuring device (product name: Melt Indexer G-02, manufactured by Toyo Seiki Seisaku-sho) was used to measure the melt flow rate of thermoplastic resins A, E and solid epoxy resin at a temperature of 190°C and a load of 2.16 kg.

A: Polyester resin, Primalloy A1500 (Mitsubishi Chemical), MFR=11g/10min

E: Phenoxy resin, Phenotohto YP70 (Nippon Steel & Sumitomo Metal Chemicals Co., Ltd.), MFR = 1g/10min

Solid epoxy resin: Bisphenol A epoxy resin, 1001, Mitsubishi Chemical Co., Ltd., MFR=2600g/10min

<Implementation Example 4-1>

As shown in Table 4, thermoplastic resin A, liquid epoxy resin (bisphenol A type epoxy resin, YL980, Mitsubishi Chemical Co., Ltd.), flux compound A (glutaric acid (1,3-propanedicarboxylic acid), Wako Pure Chemical Industries, Ltd.), solder particles (42Sn-58Bi, Type 6, melting point 139°C, average particle size 10μm, Mitsui Metals Co., Ltd.), and titanium oxide (average particle size 0.21μm, CR-60, Ishihara Sangyo Co., Ltd.) were mixed with specific mass fractions to produce an anisotropic bonding film.

Thermoplastic resin A and liquid epoxy resin were mixed and dissolved in toluene, and flux compound A and titanium oxide were added thereto. After being dispersed by a three-roll grinder (passed 3 times with a gap of 10 μm), solder particles were dispersed to obtain a resin solution. The resin solution was coated on a peeling PET (PET-02-BU, Shikoku-Tohcello (stock)) with a gap coater in a manner such that the thickness after toluene drying was 20 μm. Toluene drying was performed under the condition of 80°C-10min.

As shown in Table 4, the forward voltage of the LED mount made using anisotropic bonding film is 3.1V, the insulation is OK, and the chip shear strength is 44N/chip.

<Implementation Example 4-2>

As shown in Table 4, a solid epoxy resin was used instead of thermoplastic resin A, and an anisotropic bonding film was prepared in the same manner as in Example 4-1. The forward voltage of the LED mounting body prepared using the anisotropic bonding film was 3.1V, the insulation was OK, and the chip shear strength was 45N/chip.

<Implementation Example 4-3>

As shown in Table 4, flux compound B (blocked carboxylic acid, Santacid G, NOF Corporation) was used instead of flux compound A, and the anisotropic bonding film was prepared in the same manner as in Example 4-1. The LED mounting body prepared using the anisotropic bonding film had a forward voltage of 3.0 V, an insulation property of OK, and a chip shear strength of 44 N/chip.

<Implementation Example 4-4>

As shown in Table 4, the thickness of the anisotropic bonding film was set to 30 μm, and the anisotropic bonding film was prepared in the same manner as in Example 4-1. The forward voltage of the LED mounting body prepared using the anisotropic bonding film was 3.1 V, the insulation was OK, and the chip shear strength was 48 N/chip.

<Comparison Example 4-1>

As shown in Table 4, an anisotropic bonding paste is prepared by mixing and dispersing liquid epoxy resin, hardener A, flux compound B, titanium oxide, and solder particles.

Prepare LED chips (Dexerials evaluation LED chips, size 45mil, If=350mA, Vf=3.1V, Au-Sn pads, pad size 300μm×800μm, pad spacing 200μm) and substrates (Dexerials evaluation ceramic substrates, 18μm thick Cu patterns, Ni-Au coating, pattern spacing (gap) 50μm). Use a 30μm thick mask to apply anisotropic bonding paste on the substrate, align the LED chips and mount them, then install the LED chips by reflow (peak temperature 260℃).

As shown in Table 4, the forward voltage of the LED mount made using anisotropic bonding paste is 3.0V, the insulation is NG, and the chip shear strength is 45N/chip.

<Comparison Example 4-2>

As shown in Table 4, thermoplastic resin E was used instead of thermoplastic resin A, and the anisotropic bonding film was prepared in the same manner as in Example 4-1. The forward voltage of the LED mounting body prepared using the anisotropic bonding film was OPEN, the insulation was OK, and the chip shear strength was 19N/chip.

<Comparison Example 4-3>

As shown in Table 4, the anisotropic bonding film was prepared in the same manner as Example 4-1 except that the flux compound was not mixed. The forward voltage of the LED mounting body prepared using the anisotropic bonding film was OPEN, the insulation was OK, and the chip shear strength was 18N/chip.

<Comparison Example 4-4>

As shown in Table 4, the thickness of the anisotropic bonding film was set to 40 μm, and the anisotropic bonding film was prepared in the same manner as in Example 4-1. The forward voltage of the LED mounting body prepared using the anisotropic bonding film was OPEN, the insulation was OK, and the chip shear strength was 25 N/chip.

In Comparative Example 4-1, since a paste-like anisotropic bonding material was applied without mixing with a solid resin, a short circuit caused by solder bonding occurred between adjacent terminals of the substrate.

In Comparative Example 4-2, since thermoplastic resin E with a melt flow rate of 1g/10min was used, the resin had poor fluidity, the solder particles did not melt, and did not bond with the electrode of the connected body. Therefore, the forward voltage could not be measured. In addition, since the resin did not flow sufficiently and no solder joint was formed, the LED chip had weak adhesion and low chip shear strength.

In Comparative Example 4-3, since the flux compound was not mixed, the solder particles did not melt and the forward voltage could not be measured.

In Comparative Example 4-4, since a 40μm thick anisotropic bonding film was used, which is 4 times thicker than the average particle size of the solder particles of 10μm, no solder joint was formed and the forward voltage could not be measured. In addition, the chip shear strength was also lower.

On the other hand, in Examples 4-1 to 4-4, since a thermoplastic resin A or solid epoxy resin having a melt flow rate of more than 1g/10min is used, and an anisotropic bonding film having a thickness of 20-30μm, which is 2-3 times the average particle size of the solder particles of 10μm, is used, the resin melts and flows, and solder bonding is performed between the electrodes of the connected body by solder particles, and a value close to the rated voltage of 3.1V can be obtained. In addition, the chip shear strength is also good. In addition, in Example 4-3, even if a flux compound is used as a hardener, a good result can be obtained.

Furthermore, it is believed that although a film-like anisotropic bonding material is used in the above-mentioned embodiment, the same result can be obtained if the paste-like anisotropic bonding material is adjusted to a specific thickness.

Claims (5)

A method for manufacturing a connector, wherein an anisotropic bonding material containing a solid resin, solder particles, and a flux compound is interposed between an electrode of a first electronic component and an electrode of a second electronic component with a thickness of more than 50% and less than 300% of the average particle size of the solder particles, and the electrode of the first electronic component and the electrode of the second electronic component are heat-bonded under no load, wherein the solid resin is selected from at least one of a thermoplastic resin, a solid free radical polymerizable resin, and a solid epoxy resin, is solid at room temperature, and has a melt flow rate of more than 10 g/10 min at a temperature of 190°C and a load of 2.16 kg. A method for manufacturing a connector as described in claim 1, wherein the anisotropic bonding material is an anisotropic bonding film having a thickness of not less than 50% and not more than 300% of the average particle size of the solder particles. A method for manufacturing a connector as described in claim 2, wherein the second electronic component is a substrate, the anisotropic bonding film is laminated on the substrate, and a plurality of the first electronic components are mounted on the anisotropic bonding film and thermally bonded. A method for manufacturing a connector as described in any one of claims 1 to 3, wherein the flux compound is a carboxylic acid. A method for manufacturing a connector as described in any one of claims 1 to 3, wherein the flux compound is a blocked carboxylic acid in which the carboxyl group is blocked by an alkyl vinyl ether.

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