KR20220062055A - Method for manufacturing a connector, anisotropic conductive bonding material, and a connector - Google Patents

Abstract

Provided are a method for manufacturing a connector, an anisotropic conductive bonding film, and a connector capable of bonding electronic components having fine-pitch electrodes. An anisotropic conductive bonding material formed by dispersing solder particles in a thermosetting type insulating binder and having a minimum melt viscosity reaching temperature lower than the melting point of the solder particles and a curing temperature higher than the melting point of the solder particles; Using a reflow furnace interposed between the electrode and the electrode of the second electronic component and set to a peak temperature equal to or higher than the curing temperature, the electrode of the first electronic component and the electrode of the second electronic component are joined without load.

Description

Method for manufacturing a connector, anisotropic conductive bonding material, and a connector

The present invention relates to a method for manufacturing a connector on which a semiconductor chip (element) is mounted, an anisotropic conductive bonding material, and a connector. This application claims priority on the basis of Japanese Patent Application No. 2019-194428 for which it applied in Japan on October 25, 2019, This application is used for this application by being referred.

As one of the methods of mounting a semiconductor chip (element), flip-chip mounting is mentioned. Flip-chip mounting can make a mounting area small compared with wire bonding, and can mount a small and thin semiconductor chip.

However, since flip-chip mounting is thermally compressed, for example, when bonding a large number of semiconductor chips and a large substrate, a very high pressure is required or adjustment of parallelism is required, and mass productivity is difficult.

Japanese Patent Laid-Open No. 2009-102545

Patent Document 1 describes that a plurality of components are collectively mounted on a wiring board or the like by reflow using a solder paste containing solder particles, a thermosetting resin binder, and a flux component.

However, the solder paste of Patent Document 1 contains a large amount of solder particles in order to melt and integrate the solder particles, and it is difficult to bond electronic components with fine-pitch electrodes.

The present technology has been proposed in view of such a conventional situation, and provides a method for manufacturing a connector, an anisotropic conductive bonding material, and a connector capable of joining electronic components having fine-pitch electrodes.

As a result of earnest examination, this inventor discovered that the objective mentioned above can be achieved by using the anisotropic electrically conductive bonding material which shows electroconductivity only in the direction in which the electrically-conductive particle was inserted, and came to complete this invention.

That is, in the method for manufacturing a connector according to the present invention, solder particles are dispersed in a thermosetting insulating binder, the minimum melt viscosity reaching temperature lower than the melting point of the solder particles, and a curing temperature higher than the melting point of the solder particles An anisotropic conductive bonding material having It is used and joined without a load, and the peak temperature of the said reflow furnace is 10 degrees or more higher than the hardening temperature of the said anisotropic conductive bonding material.

Further, the anisotropic conductive bonding material according to the present invention is made by dispersing solder particles in a thermosetting type insulating binder, and has a minimum melt viscosity reaching temperature lower than the melting point of the solder particles, and a curing temperature higher than the melting point of the solder particles. have

Moreover, in the connection body which concerns on this invention, the electrode of a 1st electronic component and the electrode of a 2nd electronic component are joined using the anisotropic electrically conductive bonding material mentioned above.

According to the present invention, since the insulating binder is melted by heating and the binder is cured in a state in which solder particles are sandwiched between the electrodes, it is possible to bond electronic components having fine-pitch electrodes.

BRIEF DESCRIPTION OF THE DRAWINGS It is sectional drawing which shows typically a part of a bonding process.
Fig. 2 is a cross-sectional view showing a configuration example of an LED mounting body.
3 : is sectional drawing which shows typically a part of anisotropic conductive bonding film to which this technique was applied.
4 is a graph showing a reflow temperature profile.
It is a graph which shows the measurement result of the differential scanning calorimetry (DSC:Differential scanning calorimetry) of the anisotropic conductive bonding film of Example 1. FIG.
Fig. 6 is a photomicrograph when the solder joint state of the substrate side after peeling the LED chip of Example 1 is observed.

EMBODIMENT OF THE INVENTION Hereinafter, embodiment of this invention is described in detail in the following order, referring drawings.

1. Method of manufacturing a connector

2. Anisotropic conductive bonding material

3. Examples

<1. Manufacturing method of connector>

The method for manufacturing a connector according to the present embodiment is formed by dispersing solder particles in a thermosetting type insulating binder, and has a minimum melt viscosity reaching temperature lower than the melting point of the solder particles, and a curing temperature higher than the melting point of the solder particles. An anisotropic conductive bonding material is interposed between the electrode of the first electronic component and the electrode of the second electronic component, and the electrode of the first electronic component and the electrode of the second electronic component are joined without a load using a reflow furnace, , the peak temperature of the reflow furnace is 10 degrees or more higher than the curing temperature of the anisotropic conductive bonding material. In this way, when the temperature of the reflow furnace (reflow process) is raised, the insulating binder is melted to the minimum melt viscosity reaching temperature, so that the solder particles easily come into contact with the electrode of the first electronic component and the electrode of the second electronic component. can

In the present specification, the minimum melt viscosity attainable temperature of the anisotropic conductive bonding material is measured using, for example, a rotary rheometer (manufactured by TA Instruments), a measurement pressure of 5 g, a temperature range of 30 to 200°C, and a temperature increase rate of 10°C. It measures under the conditions of /min, measuring frequency 10 Hz, measuring plate diameter 8 mm, and the load fluctuation|variation with respect to the measuring plate 5g, and a viscosity means the temperature at which the lowest value (minimum melt viscosity) becomes. In addition, the curing temperature of the anisotropic conductive bonding material is the exothermic peak temperature measured by measuring 5 mg or more of a sample with an aluminum pan by differential thermal analysis (DSC), and under the conditions of a temperature range of 30 to 250°C and a temperature increase rate of 10°C/min. am. In addition, a connection body is what two materials or members were electrically connected. In addition, joining means joining two materials or members together. The no-load means a state in which there is no mechanical pressurization.

As the first electronic component, a wiring (conducting material) such as an LED (Light Emitting Diode), a driver IC (Integrated Circuit), and a flexible substrate (FPC: Flexible Printed Circuits, resin-molded components) may be formed, and among these, the LED , a chip (for example, a semiconductor device) such as a driver IC, etc. The second electronic component is not particularly limited as long as a terminal corresponding at least in part to the terminal of the first electronic component is formed, and the first electronic component is As long as it can be defined in a broad sense as a substrate (so-called printed wiring board: PWB) on which mountable electrodes are formed, for example, rigid substrates, glass substrates, flexible substrates (FPC: Flexible Printed Circuits), ceramic substrates, plastics and substrate such as board.In addition, the same component may be laminated and connected.The number of this layering is not particularly limited as long as it does not impede the connection.It is the same even in the case of multiple stacking of different components. The electrodes (electrode arrangement, electrode group) respectively formed on the component and the second electronic component are formed to face each other and anisotropically connected, and the electrodes (electrode arrangement, electrode group) may be formed.In addition, it is preferable that the said electronic component is equipped with the heat resistance in a reflow process.

The connector in this embodiment is connected by solder particles widely used in BGA (Ball grid array) and the like, and since the connection reliability is high, sensor devices, in-vehicle devices, IoT (Internet of Things) devices, etc.; It can be applied to many uses.

The anisotropic conductive bonding material may be either a film-like anisotropic conductive bonding film or a paste-like anisotropic conductive bonding paste. Moreover, it is good also as a form close|similar to a film by mounting components, even if it is a film form at the time of connecting an anisotropic electrically conductive bonding paste.

In the case of the anisotropic conductive bonding paste, it is sufficient that a predetermined amount can be uniformly applied on the substrate. In the case of an anisotropic conductive bonding film, not only can the amount of anisotropic conductive bonding material be equalized by the film thickness, but it can laminate on a board|substrate collectively, and since tact can be shortened, it is especially preferable. Moreover, since it is easy to handle by setting it as a film form beforehand, it can be expected that working efficiency is also made high.

Hereinafter, as a specific example of the manufacturing method of a connection body, the manufacturing method of an LED mounting body is demonstrated. The manufacturing method of an LED mounting body is made by dispersing solder particles in a thermosetting type insulating binder, and an anisotropic conductive bonding material having a minimum melt viscosity reaching temperature lower than the melting point of the solder particles and a curing temperature higher than the melting point of the solder particles. It has a process of forming on a board|substrate, a mounting process of mounting an LED element on an anisotropic conductive bonding material, and a bonding process of heat-bonding the electrode of an LED element and the electrode of a board|substrate with no load. A plurality of components may be mounted collectively.

The step of forming the anisotropic conductive bonding material may be a step of forming an anisotropic conductive bonding paste on a substrate before connection, and as used in conventional anisotropic conductive films, the anisotropic conductive bonding film is applied on the substrate at low temperature and low pressure. The temporary bonding process to stick may be sufficient, and the lamination process of laminating an anisotropic conductive bonding film on a board|substrate may be sufficient.

When the process of forming the anisotropic conductive bonding material is a temporary bonding process, the anisotropic conductive bonding film can be formed on the substrate under known conditions of use. In this case, since it can be solved only with minimal changes such as installation or change of tools from the conventional apparatus, an economical advantage is obtained.

When the process of forming the anisotropic conductive bonding material is a lamination process, for example, an anisotropic conductive bonding film is laminated on a substrate using a pressurized laminator. A vacuum pressurization type may be sufficient as a lamination process. In the case of temporary adhesion using a conventional anisotropic conductive film using a heating and pressing tool, the width of the film is limited by the tool width. can be expected to be Moreover, you may laminate one anisotropic conductive bonding film with respect to one board|substrate. Thereby, since the vertical movement of a thermocompression-bonding tool and conveyance of an anisotropic conductive bonding film are not carried out in multiple times, the time of the process of forming an anisotropic conductive bonding material can be shortened.

In the step of forming the anisotropic conductive bonding material, it is preferable to approximate the thickness of the anisotropic bonding material between the electrode of the LED element and the electrode of the substrate to the average particle diameter of the solder particles. The lower limit of the thickness of the anisotropic bonding material is 50% or more, preferably 80% or more, more preferably 90% or more of the average particle diameter of the solder particles. When the thickness of the anisotropic bonding material is too thin, the sandwiching between the electrodes of the solder particles becomes easy, but there is a fear that the difficulty in forming a film may increase. Further, the upper limit of the thickness of the anisotropic bonding material is 300% or less of the average particle diameter of the solder particles, preferably 200% or less, and more preferably 150% or less. When the thickness of the anisotropic bonding material is too thick, there is a possibility that the bonding may be impaired.

In the present specification, the average particle diameter is an observation image using an electron microscope such as a metal microscope, an optical microscope, or an SEM (Scanning Electron Microscope), N = 50 or more, preferably N = 100 or more, more preferably It is an average value of the major axis diameter of particle|grains measured by N=200 or more, and when particle|grains are spherical, it is an average value of particle diameters. Moreover, the measurement value measured using well-known image analysis software ("WinROOF": Mitani Corporation, "A-Zokun (trademark)": Asahi Chemical Engineering Co., Ltd., etc.) for an observation image, an image type particle size distribution measuring apparatus (For example, it may be a measurement value (N=1000 or more) measured using FPIA-3000 (Malvern Corporation)). The average particle diameter calculated|required from an observation image or an image-type particle size distribution analyzer can be made into the average value of the maximum length of particle|grains. In addition, when manufacturing an anisotropic bonding material, the particle diameter (D50) and the arithmetic mean diameter (preferably on a volume basis) at which the accumulation of frequencies in the particle size distribution simply obtained by the laser diffraction/scattering method is 50%. You can use maker values such as

In a mounting process, a some LED element is arrange|positioned on an anisotropic conductive bonding film, and it mounts, for example. In the present technology, since self-alignment by solder particles cannot be expected, it is preferable to accurately align the LED element in the mounting step. Each LED element has, for example, a first conductivity type electrode and a second conductivity type electrode on one side, and is disposed on an electrode of the substrate 30 corresponding to the first conductivity type electrode and the second conductivity type electrode.

In addition, in the step of forming the anisotropic conductive bonding material described above, the thickness of the anisotropic bonding material between the electrode of the LED element and the electrode of the substrate is approximated to the average particle size of the solder particles, but it is not limited thereto, and the mounting is not limited thereto. In the process, the thickness of the anisotropic bonding material may be approximated to the average particle diameter of the solder particles by pressing. In this pressing step, for example, by pressing from the side of the first electronic component mounted on the second electronic component, the thickness of the anisotropic bonding material between the electrode of the LED element and the electrode of the substrate is reduced to that of the solder particles. It approximates the average particle diameter. Here, when the thickness of the anisotropic bonding material is too large, it can be said that it is preferable to set it as the thickness of the upper limit mentioned above, since there exists a possibility of causing trouble to pressurization. The approximation to the average particle diameter means that, theoretically, the maximum diameter of the solder particles becomes the thickness of the anisotropic connection material after this pressing step. Considering this, it may be 130% or less of the maximum diameter of the solder particles, preferably 120% or less. The lower limit of the pressure in the pressurization step is preferably 0.2 MPa or more, more preferably 0.4 MPa or more, and the upper limit of the pressure in the pressurization step may be 2.0 MPa or less, preferably 1.0 MPa or less, more Preferably it is 0.8 MPa or less. Since the upper and lower limits may fluctuate depending on the specifications of the device, they are not limited to the above numerical ranges as long as the purpose of pushing the resin up to the solder particle size can be achieved.

1 : is sectional drawing which shows typically a part of a bonding process. In a bonding process, the electrodes 11 and 12 of the LED element 10 and the electrodes 21 and 21 of the board|substrate 20 are heat-bonded by no load. As a method of heat bonding without mechanical pressure and without a load, atmospheric pressure reflow, vacuum reflow, atmospheric pressure oven, autoclave (pressurized oven), etc. are mentioned. Among these, air bubbles contained in the joint can be excluded. It is preferable to use a vacuum reflow, an autoclave, or the like. Since unnecessary resin flow does not generate|occur|produce compared with the anisotropic electrically conductive connection using a general heating-pressing tool by no load, the effect that bubble entrapment is also suppressed can be anticipated.

The peak temperature in the reflow furnace is required to be 10 degrees or more higher than the curing temperature of the anisotropic conductive bonding material, preferably 150°C or more and 250°C or less, more preferably 160°C or more and 230°C or less, still more preferably It is heated to 170 ℃ or higher and 210 ℃ or lower. Thereby, since the electrode of the LED element 10 and the electrode of the board|substrate 20 are joined, the outstanding conduction property, heat dissipation property, and adhesiveness can be acquired. In the bonding step, since there is no load, it is expected that the amount of movement of the solder particles is small and the solder particle trapping efficiency is high. In addition, the content of the solder particles is such that self-alignment cannot be expected, and in the bonding process, since the plurality of solder particles contained in the anisotropic conductive bonding film are not integrated, a plurality of solder joint points in one electrode There are cases where this exists. Here, solder bonding means that each electrode of the electronic component which opposes is melted and connected with solder.

In the reflow furnace, the thermosetting resin is melted by heating, the solder particles 31 are sandwiched between the electrodes by the weight of the LED element 10, and the solder particles 31 are melted by the main heating that is equal to or higher than the solder melting point. , the solder is wetted with the electrode and diffused, and the electrode of the LED element 10 and the electrode of the substrate 20 are joined by cooling. The reflow may include a step (keep step) of maintaining the temperature at a constant temperature in addition to the temperature increasing step and the temperature decreasing step. The peak process used as the highest temperature may exist, and a process may be included in the middle of temperature increase or temperature fall. The temperature raising step may be a two-step process: a step of melting the binder (eg, to 120° C. in FIG. 4) and a step of melting and spreading the solder particles (eg, 120 to 175° C. in FIG. 4). Therefore, as an example, the temperature increase rate may be 10-120 degreeC/min, and 20-100 degreeC/min may be sufficient as it. The holding time of the keep step (eg, 175 to 180° C. in FIG. 4 ) may be a step of curing the binder. This temperature is a temperature of 160-230 degreeC as an example, and there may be a difference of about 5-10 degreeC, and may be the same as a peak temperature. When it is too short, the life performance of the binder decreases and handleability is impaired, so it is 0.5 min or more, preferably 0.75 min or more, and when it is too long, since manufacturing efficiency deteriorates, it is 5 min or less, preferably 3 min or less. By cooling (below the melting point of solder particle|grains) through a temperature-fall process, solder particle|grains can be made into a solid phase, and it can join between electrodes. The temperature-fall rate is preferably high in order to take out quickly in order to increase productivity, and since it is preferable for the quality improvement of a joined body not to rapidly cool a joined state, the lower one is better. As an example, the same rate as the temperature increase step may be sufficient, and it is preferable that it is 10-30 degreeC/min. The temperature-fall rate can be adjusted according to the combination of the object to be joined, the conditions of the binder to be used, etc. It also affects the ejection temperature and its environment.

According to the manufacturing method of the LED mounted body mentioned above, bonding can be performed more easily by approximating a solder particle and a film thickness before a reflow process, and making a solder particle and an electrode contact. In addition, by matching the temperature rise/maintenance/fallen temperature of the reflow process and the thermosetting behavior of the anisotropic conductive bonding film, it is possible to optimize resin melting during no-load connection, pinching of solder particles between electrodes, and solder melting/resin curing. can In addition, the thermosetting behavior of an anisotropic conductive bonding film can be known by DSC measurement or the viscosity measurement by a rheometer.

Fig. 2 is a cross-sectional view showing a configuration example of an LED mounting body. In this LED mounting body, the LED element 10 and the board|substrate 20 are connected using the anisotropic conductive bonding film in which the solder particle 31 was disperse|distributed in the insulating binder of a thermosetting type. That is, the LED mounting body includes an LED element 10 , a substrate 20 , and solder particles 31 , and electrodes 11 and 12 of the LED element 10 and electrodes 21 of the substrate 20 , 22) is provided, and the electrodes 11 and 12 of the LED element 10 and the electrodes 21 and 22 of the substrate 20 are connected by a solder joint 33 It is formed by bonding, and solid resin is filled between the LED element 10 and the board|substrate 20.

The LED element 10 includes a first conductivity type electrode 11 and a second conductivity type electrode 12 , and applies a voltage between the first conductivity type electrode 11 and the second conductivity type electrode 12 . When applied, carriers are concentrated in the active layer in the device, and light is emitted by recombination. The distance between the space of the first conductivity type electrode 11 and the second conductivity type electrode 12 depends on the element size, for example, 100 μm or more and 200 μm or less, 100 μm or more and 50 μm or less, 20 μm or more 50 Some are smaller than ㎛. Although it does not specifically limit as the LED element 10, For example, the blue LED etc. which have a peak wavelength of 400 nm - 500 nm can be used suitably.

The substrate 20 is provided on the substrate with the first electrode 21 and the second electrode 22 at positions corresponding to the first conductivity type electrode 11 and the second conductivity type electrode 12 of the LED element 10, respectively. ) has As the board|substrate 20, a printed wiring board, a glass substrate, a flexible board|substrate, a ceramic board|substrate, a plastic board|substrate, etc. are mentioned. The electrode heights of a printed wiring board are 10 micrometers or more and 40 micrometers or less, for example, the electrode heights of a glass substrate are 3 micrometers or less, for example, and the electrode heights of a flexible substrate are 5 micrometers or more and 20 micrometers or less, for example.

In the anisotropic conductive bonding film 32 , the anisotropic conductive bonding material becomes a film after the bonding step, and the electrodes 11 and 12 of the LED element 10 and the electrodes 21 and 22 of the substrate 20 are It is formed by filling an anisotropic conductive bonding material between the LED element 10 and the board|substrate 20 while connecting and bonding with the solder joint part 33. As shown in FIG.

As shown in FIG. 2 , in the LED mounting body, the terminals (electrodes 11 and 12 ) of the LED element 10 and the terminals (electrodes 21 , 22 ) of the substrate 20 are connected to a solder joint 33 . It is metal-bonded by this, and solid resin is filled between the LED element 20 and the board|substrate 30. Thereby, the penetration|invasion of moisture etc. into between the LED element 10 and the board|substrate 20 can be prevented.

<2. Anisotropic conductive bonding material>

The anisotropic conductive bonding material in the present embodiment is formed by dispersing solder particles in a thermosetting type insulating binder, and has a minimum melt viscosity reaching temperature lower than the melting point of the solder particles, and a curing temperature higher than the melting point of the solder particles. will have Here, the curing temperature is an exothermic peak temperature measured under the condition of a temperature increase rate of 10°C/min, as described above.

It is preferable that the hardening temperature of an anisotropic conductive bonding material is 150 degreeC or more and 200 degrees C or less. As a result, the insulating binder is melted by heating and the solder particles are melted while being sandwiched between the electrodes, so that the electronic component including the fine-pitch electrodes can be joined.

Moreover, the minimum melt viscosity of the anisotropic conductive bonding material may be less than 100 Pa.s, Preferably it is 50 Pa.s or less, More preferably, it is 30 Pa.s or less, More preferably, it is 10 Pa.s or less. When the minimum melt viscosity is too high, the resin melting does not proceed under no load in the reflow step, and there is a risk of impairing the clamping between the solder particles and the electrode. In this technology, since a load is not applied during heat curing of the binder resin, it is necessary to set it lower than the minimum melt viscosity of the binder resin on the premise that a load is applied (pressing with a tool as in general anisotropic connection). . Further, the minimum melt viscosity reaching temperature of the anisotropic conductive bonding material is preferably -10°C to -60°C of the melting temperature of the solder particles, more preferably -10°C to -50°C of the melting temperature of the solder particles, further Preferably, it is -10 degreeC - -40 degreeC of the melting temperature of a solder particle. Thereby, the lowest melt viscosity can be reached before melting the solder, the solder particles can be melted after melting the resin, and the resin can then be cured, so that a good solder joint can be obtained.

3 : is sectional drawing which shows typically a part of the anisotropic conductive bonding film to which this technique was applied. As shown in FIG. 3 , the anisotropic conductive bonding film 30 is formed by dispersing solder particles 31 in a thermosetting type insulating binder. Moreover, on the anisotropic conductive film 30, a 1st film may be affixed on a 1st surface as needed, and a 2nd film may be affixed on a 2nd surface. In addition, the anisotropic conductive bonding film formed the anisotropic conductive bonding material in the form of a film.

The lower limit of the film thickness is 50% or more of the average particle diameter of the solder particles, preferably 80% or more, and more preferably 90% or more. When the film thickness is too thin, pinching of the solder particles between electrodes will be facilitated, but there is a fear that the difficulty in forming a film may increase. The upper limit of the film thickness is 300% or less of the average particle diameter of the solder particles, preferably 200% or less, and more preferably 150% or less. When film thickness is too thick, there exists a possibility of causing trouble to bonding. The film thickness is measured using a known micrometer or digital tickness gauge capable of measuring 1 µm or less, preferably 0.1 µm or less (eg, Mitsutoyo Corporation: MDE-25M, minimum display amount 0.0001 mm) can do. What is necessary is just to measure a film thickness at 10 points or more, and just to average it and to calculate|require it. However, when the film thickness is thinner than the particle diameter, since a contact-type thickness gauge is not suitable, it is preferable to use a laser displacement meter (eg, Keyence Co., Ltd., spectral interference displacement type SI-T series, etc.). Here, the film thickness is only the thickness of the resin layer, and the particle diameter is not included.

[thermosetting type insulating binder]

Examples of the thermosetting insulating binder (insulating resin) include a thermal radical polymerization type resin composition comprising a (meth)acrylate compound and a thermal radical polymerization initiator, and a thermal cation polymerization type resin composition containing an epoxy compound and a thermal cationic polymerization initiator and a thermal anion polymerization type resin composition containing an epoxy compound and a thermal anion polymerization initiator. Moreover, you may use a well-known adhesive composition. In addition, a (meth)acryl monomer is a meaning including both an acryl monomer and a methacryl monomer.

Below, as a specific example, the thermal anion polymerization type resin composition containing a solid epoxy resin, a liquid epoxy resin, an epoxy resin hardening|curing agent, and a flux compound is mentioned as an example, and it demonstrates.

The solid epoxy resin is not particularly limited as long as it is an epoxy resin that is solid at room temperature and has one or more epoxy groups in the molecule, and may be, for example, a bisphenol A epoxy resin or a biphenyl epoxy resin. Thereby, the film shape can be maintained. In addition, normal temperature is the range of 20 degreeC±15 degreeC (5 degreeC - 35 degreeC) prescribed|regulated by JISZ8703.

The liquid epoxy resin will not be specifically limited as long as it is liquid at normal temperature, For example, a bisphenol A epoxy resin, a bisphenol F epoxy resin, etc. may be sufficient, and a urethane-modified epoxy resin may be sufficient.

To [ the compounding quantity of a liquid epoxy resin / 100 mass parts of solid epoxy resins ], Preferably it is 160 mass parts or less, More preferably, it is 100 mass parts or less, More preferably, it is 70 mass parts or less. When the compounding quantity of a liquid epoxy resin increases, it will become difficult to maintain a film shape.

The epoxy resin curing agent is not particularly limited as long as curing is initiated by heat, and examples thereof include anionic curing agents such as amines and imidazoles, and cationic curing agents such as sulfonium salts. Moreover, the hardening|curing agent may be microencapsulated so that tolerance may be acquired with respect to the solvent used when making it into a film.

Moreover, carboxylic acid or blocked carboxylic acid in which the carboxyl group was blocked with alkylvinyl ether may be sufficient as a hardening|curing agent. That is, the curing agent may be a flux compound.

The flux compound removes foreign substances and oxide films on the electrode surface, prevents oxidation of the electrode surface, or reduces the surface tension of the molten solder. As the flux compound, it is preferable to use, for example, carboxylic acids such as levulinic acid, maleic acid, oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid and sebacic acid. Thereby, while being able to obtain a favorable solder connection, when an epoxy resin is mix|blended, it can make it function as a hardening|curing agent of an epoxy resin.

Moreover, as a flux compound, it is preferable to use the blocked carboxylic acid in which the carboxyl group was blocked with the alkyl vinyl ether. Thereby, the temperature at which the flux effect and the curing agent function are exhibited can be controlled. Moreover, since the solubility with respect to resin improves, the mixing and application|coating nonuniformity at the time of film-forming can be improved. In addition, it is preferable that the dissociation temperature at which blocking is canceled is equal to or higher than the melting point of the solder particles. Thereby, while being able to obtain a favorable solder connection, when an epoxy resin is mix|blended, since hardening starts after flow of an epoxy resin, favorable solder joint can be obtained.

[Solder particles]

The solder particles may be randomly kneaded and dispersed in the anisotropic conductive bonding film, or may be arranged in a planar view. These may be used separately depending on the intended use. Regular arrangement or random arrangement may be sufficient as arrangement|positioning of the whole solder particle in the planar view of an anisotropic conductive bonding film. Examples of the regular arrangement include a lattice arrangement such as a square lattice, a hexagonal lattice, a tetragonal lattice, and a rectangular lattice, and there is no restriction in particular. Moreover, as an aspect of a random arrangement|positioning, it is preferable that each solder particle exists without mutual contact in the planar view of a film, and it exists without overlapping each other also in the film thickness direction. Moreover, it is preferable that 75 % or more, preferably 95 % or more of the total number of solder particles in the anisotropic conductive bonding film are non-contact with other solder particles and are independent. This can be confirmed by using a known metallurgical microscope or an optical microscope, arbitrarily extracting an area of 1 mm2 or more in a film plane view at 5 or more points, and observing 200 or more, preferably 1000 or more, of solder particles. . Moreover, when the solder particle is arrange|positioned in planar view in an anisotropic conductive bonding film WHEREIN: The solder particle may be arrange|positioned at the same position in the film thickness direction.

Moreover, the solder particle|grains may be arrange|positioned as an aggregate which a plurality of pieces aggregated. In this case, the arrangement of the aggregates in the planar view of the anisotropic bonding film may be a regular arrangement or a random arrangement, similarly to the arrangement of the solder particles described above. Moreover, it is preferable that each aggregate exists without mutual contact in the planar view of a film, and exists without mutually overlapping aggregates also in the film thickness direction. The average particle diameter of the individual solder particles in the aggregate can be measured in the same manner as the above-mentioned average particle diameter.

The average particle diameter of the solder particles is preferably 1/3 or less, more preferably 1/4 or less, still more preferably 1/5 or less of the distance between spaces between electrodes of a semiconductor element as an adherend. When the average particle diameter of the solder particles is larger than 1/3 of the distance between the electrodes of the semiconductor element, the possibility of short circuit increases.

The lower limit of the average particle diameter of the solder particles is preferably 0.5 µm or more, more preferably 3 µm or more, and still more preferably 5 µm or more. Thereby, the application|coating thickness of a film can be made constant. When the average particle diameter of the solder particles is smaller than 0.5 mu m, a good solder joint state with the electrode portion cannot be obtained, and reliability tends to deteriorate. Moreover, the upper limit of the average particle diameter of a solder particle is 30 micrometers or less, Preferably it is 25 micrometers or less, More preferably, it is 20 micrometers or less. Depending on the connection object, the upper limit of the average particle diameter of the solder particles can be 15 µm or less, preferably 12 µm or less, and more preferably 10 µm or less. In the case of an aggregate in which a plurality of solder particles are aggregated, the size of the aggregate may be equal to the average particle diameter of the solder particles described above. In the case of an aggregate, the average particle diameter of the solder particles may be smaller than the above-mentioned value. The size of each solder particle can be determined by observing it with an electron microscope.

The maximum diameter of the solder particles can be 200% or less of the average particle diameter, preferably 150% or less of the average particle diameter, and more preferably 120% or less of the average particle diameter. When the maximum diameter of the solder particles is within the above range, the solder particles can be sandwiched between the electrodes, and the electrodes can be joined by melting the solder particles. The thickness of the anisotropic conductive bonding material after pressurization may be the maximum diameter of the solder particles. In the case of an aggregate in which a plurality of solder particles are aggregated, the size of the aggregate may be equal to the maximum diameter of the solder particles described above. In the case of an aggregate, the maximum diameter of the solder particles may be smaller than the above-mentioned value. The size of each solder particle can be determined by observing it with an electron microscope.

Solder particles are, for example, Sn-Pb-based, Pb-Sn-Sb-based, Sn-Sb-based, Sn-Pb-Bi-based, Bi-Sn-based, Sn-Cu-based, as specified in JIS Z 3282-1999. , Sn-Pb-Cu, Sn-In, Sn-Ag, Sn-Pb-Ag, Pb-Ag, etc., can be appropriately selected according to the electrode material, connection conditions, and the like. The lower limit of the melting point of the solder particles is preferably 110°C or higher, more preferably 120°C or higher, and still more preferably 130°C or higher. The upper limit of the melting point of the solder particles is preferably 180°C or lower, more preferably 160°C or lower, still more preferably 150°C or lower. Further, the solder particles may be directly bonded to the surface of the flux compound for the purpose of activating the surface. By activating the surface, metal bonding with the electrode part can be promoted.

The lower limit of the mass ratio range of the blending amount of the solder particles is preferably 20 wt% or more, more preferably 30 wt% or more, and still more preferably 40 wt% or more, and the upper limit of the mass ratio range of the blending amount of the solder particles is preferably preferably 80 wt % or less, more preferably 70 wt % or less, still more preferably 60 wt % or less. The lower limit of the volume ratio range of the blending amount of the solder particles is preferably 5 vol% or more, more preferably 10 vol% or more, and still more preferably 15 vol% or more, and the upper limit of the volume ratio range of the blending amount of the solder particles is , preferably 30 vol% or less, more preferably 25 vol% or less, still more preferably 20 vol% or less. When the blending amount of the solder particles satisfies the above-described mass ratio range or volume ratio range, excellent conductivity, heat dissipation, and adhesiveness can be obtained. When the solder particles are present in the binder, the volume ratio may be used, or when the anisotropic conductive bonding material is manufactured (before the solder particles are present in the binder), the mass ratio may be used. The mass ratio can be converted into a volume ratio from the specific gravity of the compound, the compounding ratio, and the like. When the amount of the solder particles is too small, excellent conductivity, heat dissipation, and adhesiveness cannot be obtained.

[Other Additives]

In the anisotropic conductive bonding film, in addition to the above-mentioned insulating binder and solder particle, various additives can be mix|blended in the range which does not impair the effect of this invention. For example, the anisotropic conductive bonding film may contain an inorganic filler, an organic filler, a metal filler, a coupling agent, a leveling agent, a stabilizer, a thixotropic agent, etc. The particle diameters of inorganic fillers, organic fillers, and metal fillers are smaller than the average particle diameter of solder particles from the viewpoint of connection stability, for example, 10-1000 nm nano fillers, 1-10 μm micro fillers, etc. do.

Examples of the inorganic filler include silica, aluminum oxide, aluminum hydroxide, titanium oxide, aluminum hydroxide, calcium hydroxide, calcium carbonate, talc, zinc oxide, zeolite, and the like. Silica is added for the purpose of improving moisture absorption reliability, or light reflection Titanium oxide may be added for the purpose of improving the corrosion resistance, or aluminum hydroxide, calcium hydroxide, etc. may be added for the purpose of preventing corrosion by acid.

As an organic filler, an acrylic resin, carbon, core-shell particle|grains, etc. are mentioned, By addition of an organic filler, effects, such as blocking prevention and light scattering, can be acquired.

Ni, Cu, Ag, and Au are mentioned as a metal filler, These alloys may be sufficient. For example, since Cu filler forms a complex with an acid, corrosion of an electrode etc. can be prevented. In addition, the metal filler may or may not contribute to conduction|electrical_connection, and what is necessary is just to adjust the compounding quantity of a metal filler to the extent which does not short-circuit including a solder particle.

In the anisotropic conductive bonding film described above, for example, an insulating binder and solder particles are mixed in a solvent, the mixture is applied with a bar coater to a predetermined thickness on a release treatment film, and then dried It can be obtained by volatilizing a solvent. Moreover, after apply|coating a mixture on the peeling process film with a bar coater, it is good also as a predetermined thickness by pressurization. In addition, in order to increase the dispersibility of the solder particles, it is preferable to apply a high shear in a state containing a solvent. For example, a known batch type planetary stirring device can be used. What can be implemented in a vacuum environment may be sufficient. Moreover, the amount of residual solvent of an anisotropic conductive bonding film becomes like this. Preferably it is 2 % or less, More preferably, it is 1 % or less.

Example

<3. Example>

In this Example, the anisotropic conductive bonding film from which hardening temperature differs was manufactured. And the LED mounting body was manufactured using the anisotropic conductive bonding film, and the forward voltage of the LED mounting body, die-share intensity|strength, and bonding state were evaluated.

[Measurement of minimum melt viscosity, minimum melt viscosity reaching temperature, and curing temperature of the anisotropic conductive bonding film]

Using a rotary rheometer (manufactured by TA Instruments), a measurement pressure of 5 g, a temperature range of 30 to 200°C, a temperature increase rate of 10°C/min, a measurement frequency of 10 Hz, a diameter of a measurement plate of 8 mm, a load variation on the measurement plate 5 The melt viscosity was measured under the conditions of g, and the minimum melt viscosity and minimum melt viscosity reached temperature were calculated|required. In addition, the curing temperature was set as the exothermic peak temperature measured by measuring 5 mg or more of a sample with an aluminum pan by differential scanning calorimetry (DSC), and measuring under the conditions of a temperature range of 30 to 250°C and a temperature increase rate of 10°C/min. In addition, even if it is an anisotropic electrically conductive bonding paste, what is necessary is just to measure under the same conditions.

[Manufacture of LED mounting body]

LED chip (LED chip for Dexerials evaluation, size 45 mil, If = 350 mA, Vf = 3.1 V, Au-Sn pad, pad size 300 ㎛ × 800 ㎛ P electrode and N electrode are respectively formed, the pad A distance (distance between P electrode and N electrode) of 150 µm) and a substrate (ceramic substrate for Dexerials evaluation, 18 µm thick Cu pattern, Ni-Au plating, 50 µm between patterns (space)) were prepared.

On the board|substrate, the anisotropic conductive bonding film was laminated on the conditions of 60 degreeC - 2 Mpa - 2 sec, and the LED chip was mounted. Then, the LED chip was mounted by reflow.

4 is a graph showing a reflow temperature profile. As shown in FIG. 4, reflow raised the temperature stepwise so that it might become 180 degreeC of peak temperature in 240 sec. First, in order to melt the binder, the temperature was raised from 20°C to 120°C in 60 seconds, and then the temperature was raised from 120°C to 140°C in 60 seconds in order to melt the solder particles and wet and diffuse the solder particles. Next, in order to harden the binder, the temperature was raised from 140°C to 175°C in 60 seconds, maintained at 175°C to 180°C in 60 seconds, and cooled from 180°C to 160°C in 60 seconds.

[Measurement of forward voltage]

A rated current If = 350 mA was passed through the LED chip through the pattern of the substrate, and the forward voltage value Vf of the LED chip was measured. The case where reading could not be performed due to overvoltage was defined as "OPEN".

[Measurement of die share strength]

Using a bonding tester (product number: PTR-1100, manufactured by Lesca), the die share strength of the LED chip was measured at a measurement rate of 20 µm/sec.

[Observation of junction state]

After measuring die shear strength, the solder joint state of the board|substrate side after peeling an LED chip was observed with the optical microscope.

<Example 1>

As shown in Table 1, a solid epoxy resin (bisphenol F-type epoxy resin, Mitsubishi Chemical Co., Ltd., JER4007P, softening point 108 ° C.), a liquid epoxy resin (dicyclopentadiene skeleton epoxy resin, ADEKA Co., Ltd., EP4088L), Flux compound (glutaric acid (1,3-propanedicarboxylic acid), Tokyo Chemical Co., Ltd.), solder particles (Si-Bi, Mitsui Metals Co., Ltd., ST-7, melting point 139°C, average particle diameter (D50) ) 7.1 µm) and an epoxy resin curing agent (imidazole curing agent, Shikoku Chemical Industry Co., Ltd., Qazole 2P4MHZ-PW) in a predetermined mass part to prepare an anisotropic conductive bonding film.

The main constituent epoxy resin and liquid epoxy resin dissolved in PMA (propylene glycol monomethyl ether acetate) were mixed with a MEK (methyl ethyl ketone) solution of a flux compound and an epoxy resin curing agent. After dispersing solder particles in this mixed solution, it was applied on a PET (polyethylene terephthalate) film to a thickness of 10 µm after solvent drying with a gap coater to prepare an anisotropic conductive bonding film. Drying was performed under the conditions of 70 °C - 5 min.

In Table 1, the measurement result of the forward voltage of the LED mounting body manufactured using the anisotropic conductive bonding film, and die-share intensity|strength is shown. The forward voltage was 3.1 V and the die share strength was 32 N/chip.

It is a graph which shows the measurement result of the differential scanning calorimetry of the anisotropic conductive bonding film of Example 1. FIG. The graph shown in FIG. 5 shows that the endothermic reaction of solder melting appears around 139°C, and the exothermic peak temperature of resin curing appears around 163°C.

Fig. 6 is a photomicrograph when the solder joint state of the substrate side after peeling the LED chip of Example 1 is observed. Solder was wet and diffused on the LED chip side and the substrate side, and it was confirmed that the solder joint was in a good state. In addition, it was confirmed that a plurality of solder joint points existed in one electrode.

<Example 2>

As shown in Table 1, except having replaced the solid epoxy resin (bisphenol F-type epoxy resin, Mitsubishi Chemical Co., Ltd., JER4005P, softening point 87 degreeC), it carried out similarly to Example 1, The anisotropic conductive bonding film was manufactured. The LED mounted body manufactured using the anisotropic electrically conductive bonding film was 3.0V and the die-share intensity|strength of the forward voltage was 29 N/chip.

<Example 3>

As shown in Table 1, an anisotropic conductive bonding film was produced in the same manner as in Example 1 except that the solid epoxy resin (bisphenol A epoxy resin, Mitsubishi Chemical Co., Ltd., JER1004AF, softening point 97°C) was replaced. As for the LED mounted body manufactured using the anisotropic conductive bonding film, the forward voltage was 3.0V, and the die-share intensity|strength was 30 N/chip.

<Comparative Example 1>

As shown in Table 1, an anisotropic conductive bonding film was produced in the same manner as in Example 1, except that the epoxy resin curing agent (ammonium salt-based acid generator, KINGINDUSTRIES Co., Ltd., CXC-1821) was replaced. As for the LED mounting body manufactured using the anisotropic conductive bonding film, a forward voltage became open, and the die-share intensity|strength was 28 N/chip.

In Comparative Example 1, since the curing temperature of the anisotropic conductive bonding film was lower than the melting point of the solder particles, the binder of the anisotropic conductive bonding film was cured before the solder particles were melted. For this reason, the forward voltage could not be measured. Moreover, since the solder joint was not also formed, the adhesiveness of an LED chip was weak, and it brought the result with low die share intensity|strength.

On the other hand, in Examples 1 to 3, since the anisotropic conductive bonding film has a minimum melt viscosity reaching temperature lower than the melting point of the solder particles and a curing temperature higher than the melting point of the solder particles, the binder of the anisotropic conductive bonding film is melted - The binder was cured in a state where it flowed and the solder particles were sandwiched between the electrodes of the adherend. For this reason, the value close|similar to rated voltage 3.1V was obtained. Moreover, the die-share intensity|strength also brought a favorable result.

10: LED element
11: first conductive type electrode
12: second conductive type electrode
20: substrate
21: first electrode
22: second electrode
30: anisotropic conductive bonding film
31: solder particles
32: anisotropic conductive film
33: solder joint

Claims (10)

An anisotropic conductive bonding material formed by dispersing solder particles in a thermosetting insulating binder and having a minimum melt viscosity reaching temperature lower than the melting point of the solder particles and a curing temperature higher than the melting point of the solder particles, the first electronic component Interposed between the electrode and the electrode of the second electronic component,
The electrode of the first electronic component and the electrode of the second electronic component are joined without a load using a reflow furnace,
A method for producing a connection body, wherein the peak temperature of the reflow furnace is 10 degrees or more higher than the curing temperature of the anisotropic conductive bonding material. The method of claim 1,
A method for producing a connector, wherein the solder particles have a melting point of 110°C or higher and 180°C or lower. 3. The method according to claim 1 or 2,
The insulating binder includes a solid epoxy resin that is solid at room temperature,
The softening point of the said solid epoxy resin is 80 degreeC or more and 120 degrees C or less, The manufacturing method of the connection body. 4. The method of claim 3,
The insulating binder further comprises a liquid epoxy resin liquid at room temperature, an epoxy resin curing agent, and a flux compound,
The method for producing a connector, wherein the epoxy curing agent is an anionic curing agent. 5. The method of claim 4,
A method for producing a connector, wherein the flux compound is a carboxylic acid. 5. The method according to any one of claims 1 to 4,
The second electronic component is a substrate,
A method of manufacturing a connector comprising laminating the anisotropic bonding material in a film form on the substrate, and mounting and bonding the first electronic component on the anisotropic bonding material. An anisotropic conductive bonding material comprising solder particles dispersed in a thermosetting type insulating binder and having a minimum melt viscosity reaching temperature lower than the melting point of the solder particles and a curing temperature higher than the melting point of the solder particles. 8. The method of claim 7,
The anisotropic conductive bonding material whose said curing temperature is 150 degreeC or more and 200 degrees C or less. The anisotropic conductive bonding film in which the said anisotropic conductive bonding material of Claim 7 or 8 is formed in the film form. A connector formed by bonding an electrode of a first electronic component to an electrode of a second electronic component using the anisotropic conductive bonding material according to claim 7 or 8 or the anisotropic conductive bonding film according to claim 9.

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