JP2021103608A - Anisotropic conductive adhesive - Google Patents

Abstract

To provide an anisotropic conductive adhesive which can obtain excellent connection reliability and heat dissipation even for aluminum wiring.SOLUTION: An anisotropic conductive adhesive has a base material composed of a resin and a conductive layer arranged on a surface of the base material, and contains conductive particles having a K value in 30% compressive deformation of 50-400Kgf/mm2 and a recovery rate in 30% compressive deformation of 16-48%, solder particles, conductive particles, and a binder dispersing the solder particles. Thereby, excellent connection reliability and heat dissipation even for aluminum wiring can be obtained.SELECTED DRAWING: Figure 1

Description

The present invention relates to an anisotropic conductive adhesive in which conductive particles are dispersed, and more particularly, anisotropic conductive adhesive for mounting a chip (element) such as an LED (Light Emitting Diode) or a driver IC (Integrated Circuit). Regarding agents.

In recent years, LED products have become explosively widespread worldwide, and cost reduction is desired. As a method of cost reduction, for example, a resin substrate having wiring made of an inexpensive metal such as aluminum is used to reduce the cost of the substrate material, or the number of manufacturing processes is reduced to shorten the manufacturing time. A method for improving production efficiency can be considered.

As a method of mounting chip components such as LEDs on a circuit board, a method of flip-chip mounting using an anisotropic conductive film formed by dispersing conductive particles in a work-type adhesive and forming a film is widely adopted. (See, for example, Patent Document 1). However, the adhesive described in Patent Document 1 does not have sufficient adhesive strength with respect to inexpensive difficult-to-adhere metals such as aluminum.

As an adhesive exhibiting excellent adhesiveness to a metal, an adhesive using a cycloolefin as a pace has been proposed (see, for example, Patent Document 2). However, an adhesive based on a cycloolefin such as dicyclopentadiene is expected to have a large discoloration due to energy absorption of the olefin and a decrease in the amount of light due to a change with time. Moreover, since the curing time is long, it is not suitable for practical use as an LED mounting.

As another technique conscious of the adhesion of aluminum, an adhesive in which a fine particle component made of a thermoplastic resin material is blended with a one-component epoxy thermosetting adhesive containing a latent curing agent has been proposed. (See, for example, Patent Document 3.). According to the technique described in Patent Document 3, although high adhesiveness to aluminum can be realized, discoloration is severe and it is not yet sufficiently satisfactory for long-life LED applications.

Further, conventionally, solder or gold-tin (AuSn) alloy paste has been used for bonding metals. However, bonding with solder or gold tin requires high temperature, resulting in poor production efficiency, and sufficient bonding is difficult due to the influence of the oxide film existing on the surface of the aluminum wiring.

Japanese Unexamined Patent Publication No. 2010-024301 Japanese Unexamined Patent Publication No. 11-080698 Japanese Unexamined Patent Publication No. 11-012554

The present invention has been proposed in view of such conventional circumstances, and provides an anisotropic conductive adhesive capable of obtaining excellent connection reliability and heat dissipation even for aluminum wiring.

As a result of diligent studies, the present inventor described above by blending conductive particles having a K value at the time of 30% compression deformation within a predetermined range and a recovery rate at the time of 30% compression deformation, and solder particles. It was found that the object of the above can be achieved, and the present invention has been completed.

That is, the anisotropic conductive adhesive according to the present invention has a base material made of a resin and a conductive layer arranged on the surface of the base material, and has a K value of 50 to 400 Kgf / at the time of 30% compressive deformation. It contains conductive particles having a thickness of mm ² and a recovery rate of 16 to 48% at the time of compression deformation of 30%, solder particles, the conductive particles, and a binder for dispersing the solder particles.

Further, the connecting structure according to the present invention includes a first electronic component, a second electronic component, and a base material made of resin between the first electronic component and the second electronic component. It has a conductive layer arranged on the surface of the base material, has a K value of 50 to 400 Kgf / mm ² at the time of 30% compression deformation, and has a recovery rate of 16 to 48% at the time of 30% compression deformation. The first electron is provided with an anisotropic conductive film obtained by curing an anisotropic conductive adhesive containing the sex particles, the solder particles, the conductive particles, and a binder that disperses the solder particles. The terminal of the component and the terminal of the second electronic component are electrically connected via the conductive particles and are joined by the solder particles.

Further, the method for producing a connection structure according to the present invention has a base material made of resin and a conductive layer arranged on the surface of the base material, and the K value at the time of 30% compression deformation is 50 to 400 Kgf /. Anisotropic conductivity containing conductive particles of mm ² and a recovery rate of 16 to 48% at the time of compression deformation of 30%, solder particles, the conductive particles, and a binder that disperses the solder particles. An adhesive is interposed between the terminals of the first electronic component and the terminals of the second electronic component, and the first electronic component and the second electronic component are heat-bonded.

According to the present invention, excellent connection reliability for aluminum wiring can be obtained by blending conductive particles having a K value at the time of 30% compression deformation in a predetermined range and a recovery rate at the time of 30% compression deformation. At the same time, excellent heat dissipation can be obtained by joining with solder particles.

It is sectional drawing which shows an example of the LED mounting body which concerns on one Embodiment of this invention. It is sectional drawing which shows an example of the LED mounting body which concerns on one Embodiment of this invention.

Hereinafter, embodiments of the present invention will be described in detail in the following order with reference to the drawings.
1. 1. Anisotropic conductive adhesive 2. Connection structure and its manufacturing method 3. Example

<1. Anisotropic conductive adhesive ＞
The anisotropic conductive adhesive in the present embodiment has a base material made of a resin and a conductive layer arranged on the surface of the base material, and has a K value of 50 to 400 Kgf / mm at the time of 30% compression deformation. ^2. It contains conductive particles having a recovery rate of 16 to 48% at the time of 30% compression deformation, solder particles, conductive particles, and a binder that disperses the solder particles. As a result, excellent connection reliability can be obtained for the aluminum wiring, and excellent heat dissipation can be obtained.

The anisotropic conductive adhesive may be either a film-like anisotropic conductive film or a paste-like anisotropic conductive paste. Further, the anisotropic conductive paste may be in the form of a film at the time of connection, or may be in the form of a film by mounting a component.

[Conductive particles]
The conductive particles have a base material made of a resin and a conductive layer arranged on the surface of the base material. Examples of the base material include divinylbenzene-based resin, epoxy resin, phenol resin, acrylic resin, acrylonitrile-styrene (AS) resin, benzoguanamine resin, and styrene-based resin. Further, the conductive layer is preferably a metal-plated layer such as nickel, gold, copper, or palladium, and particularly preferably a nickel-gold-plated layer in which a gold-plated layer is formed on the nickel-plated layer. As a result, excellent connection reliability can be obtained for aluminum wiring.

The compressive hardness K value of the conductive particles at the time of 30% compressive deformation is 50 to 400 Kgf / mm ² , preferably 150 to 300 Kgf / mm ² , and more preferably 180 to 250 Kgf / mm ² . The recovery rate of the conductive particles at the time of 30% compression deformation is 16 to 48%, preferably 16 to 40%, and more preferably 16 to 30%. As a result, the conductive particles are compressed at a relatively low pressure, the oxide film existing on the surface of the aluminum wiring is removed, and the recovery rate is not significantly large, so that excellent connection reliability can be obtained for the aluminum wiring. ..

The compressive hardness K value of the conductive particles at the time of 30% compressive deformation is calculated by the following formula (1).

Here, in the formula (1), F and S are the load value (kgf) and the compressive displacement (mm) at the time of 30% compressive deformation of the conductive particles, respectively, and R is the radius (mm).

The K value is measured by, for example, the following measuring method. Specifically, first, conductive particles are sprayed on a steel sheet having a smooth surface at room temperature. Next, one conductive particle is selected from the sprayed conductive particles. Then, the smooth end face of a diamond-made cylinder having a diameter of 50 μm provided by a microcompression tester (for example, PCT-200 type: manufactured by Shimadzu Corporation) is pressed against one selected conductive particle to carry out this conductivity. Compress the sex particles. At this time, the compressive load is electrically detected as an electromagnetic force, and the compressive displacement is electrically detected as a displacement due to the working transformer. Here, the "compressive displacement" means a value (mm) obtained by subtracting the length of the minor axis of the conductive particles after deformation from the particle size of the conductive particles before deformation. Then, another conductive particle on the steel sheet is selected, and the compressive load and the compressive displacement of the selected conductive particle are also measured. For example, for 10 conductive particles, the compressive displacement for different compressive loads is measured. Then, for example, the load value F (kgf) and the compression displacement S (mm) at the time of 30% compression of the conductive particles are obtained from a graph or formula showing the relationship between the compression displacement and the load value, and the formula (1) is used. The compression hardness K value at the time of 30% compression is calculated.

Further, the recovery rate of the conductive particles at the time of 30% compression deformation is measured by, for example, the following method. First, using a microhardness meter, the load is compressed and deformed by 30% in the direction of the center of the conductive particles at a compression rate of 0.33 mN / sec at a temperature of 25 ° C., that is, until the diameter is shortened by 30%. After applying a load and holding for 5 seconds, unloading is performed at 0.33 mN / sec. Then, the compression recovery rate can be obtained from the following equation (2), where the thickness of the conductive particles under a 30% displacement load is A mm and the thickness of the conductive particles when left for 30 minutes after unloading is B mm. ..
Compression recovery rate (%) = [(BA) / A] x 100 ... (2)

The average particle size of the conductive particles is preferably 1 μm or more and 20 μm or less, and more preferably 2 μm or more and 10 μm or less. Further, the average particle size of the conductive particles is preferably smaller than the average particle size of the solder particles. Thereby, heat dissipation can be improved.

The blending amount of the conductive particles is preferably 5 to 50 parts by mass, more preferably 5 to 15 parts by mass, and further preferably 8 to 15 parts by mass with respect to 100 parts by mass of the binder. .. If the blending amount of the solder particles is too small, excellent heat dissipation characteristics cannot be obtained, and if the blending amount is too large, the anisotropy is impaired and excellent connection reliability cannot be obtained.

In the present specification, the "average particle size" is N = 50 or more, preferably N = 100 or more, in an observation image using an electron microscope such as a metallurgical microscope, an optical microscope, or a SEM (Scanning Electron Microscope). More preferably, it is the average value of the major axis diameters of the particles measured at N = 200 or more, and when the particles are spherical, it is the average value of the diameters of the particles. Further, the observed image may be a measured value measured by using a known image analysis software or a measured value (N = 1000 or more) measured by using an image-type particle size distribution measuring device. The average particle size obtained from the observed image or the image-type particle size distribution measuring device can be the average value of the maximum lengths of the particles. When producing the anisotropic conductive adhesive, the manufacturer values such as the particle size (D50) and the arithmetic mean diameter at which the cumulative frequency in the particle size distribution simply obtained by the laser diffraction / scattering method is 50%. Can be used.

[Solder particles]
The 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 defined in JIS Z 3282-1999. It can be appropriately selected from Sn-Pb-Cu system, Sn-In system, Sn-Ag system, Sn-Pb-Ag system, Pb-Ag system and the like according to the electrode material, connection conditions and the like. Further, the shape of the solder particles can be appropriately selected from granular, scaly and the like. The solder particles may be coated with an insulating layer in order to improve anisotropy.

The average particle size of the solder particles is larger than the average particle size of the conductive particles, and is preferably 120% or more and less than 250% of the average particle size of the conductive particles. If the solder particles are too small with respect to the conductive particles, the solder particles will not be trapped between the terminals facing each other during crimping, and excellent heat dissipation characteristics and electrical characteristics cannot be obtained. On the other hand, if the solder particles are too large with respect to the conductive particles, for example, a shoulder touch due to the solder particles occurs at the edge portion of the LED chip, a leak occurs, and the yield of the product deteriorates.

The blending amount of the solder particles is preferably 30 to 200 parts by mass, more preferably 50 to 150 parts by mass, and even more preferably 120 to 150 parts by mass with respect to 100 parts by mass of the binder. If the blending amount of the solder particles is too small, excellent heat dissipation characteristics cannot be obtained, and if the blending amount is too large, the anisotropy is impaired and excellent connection reliability cannot be obtained.

[binder]
The binder may be a thermocurable insulating binder (insulating resin), a thermal radical polymerization type resin composition containing a (meth) acrylate compound and a thermal radical polymerization initiator, an epoxy compound and a thermal cationic polymerization initiator. Examples thereof include a thermal cationic polymerization type resin composition containing the above, a thermal anion polymerization type resin composition containing an epoxy compound and a thermal anion polymerization initiator, and the like. The (meth) acrylic monomer means to include both an acrylic monomer and a methacrylic monomer.

Hereinafter, as a specific example, a thermosetting insulating binder containing an acrylic resin, an alicyclic epoxy compound or a hydrogenated epoxy compound, and a cationic catalyst will be described as an example.

The acrylic resin preferably contains 0.5 to 10 wt% of acrylic acid, and more preferably 1 to 5 wt%. Due to the inclusion of acrylic acid in the acrylic resin, in the cured product model in which the acrylic resin is an island and the epoxy compound is a sea, the island of the acrylic resin and the sea of the epoxy compound are connected, and the surface of the oxide film is formed. Since the epoxy compound becomes rough and the anchor effect with the sea is strengthened, excellent connection reliability can be obtained for aluminum wiring.

Further, the acrylic resin preferably contains 0.5 to 10 wt% of an acrylic acid ester having a hydroxyl group, and more preferably 1 to 5 wt%. Since the acrylic resin contains an acrylic acid ester having a hydroxyl group, an electrostatic adhesive force can be obtained for the aluminum wiring due to the polarity of the hydroxyl group.

Examples of the acrylic acid ester having a hydroxyl group include 2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate, 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate and the like. Among these, 2-hydroxyethyl methacrylate, which has excellent adhesiveness to an oxide film, is preferably used.

Further, the acrylic resin contains an acrylic acid ester having no hydroxy group in addition to the acrylic acid and an acrylic acid ester having a hydroxyl group. Examples of the acrylic acid ester having no hydroxy group include butyl acrylate, ethyl acrylate, nitrile acrylate and the like.

The acrylic resin preferably has a weight average molecular weight of 50,000 to 900,000. In the cured product model in which the acrylic resin is an island and the epoxy compound is a sea, the weight average molecular weight of the acrylic resin correlates with the size of the islands of the acrylic resin. Therefore, the weight average molecular weight of the acrylic resin is 50,000 to When the value is 900,000, it is possible to bring an island of an acrylic resin having an appropriate size into contact with the oxide film. When the weight average molecular weight of the acrylic resin is less than 50,000, the contact area between the islands of the acrylic resin and the oxide film becomes small, and the effect of improving the adhesive strength cannot be obtained. Further, when the weight average molecular weight of the acrylic resin exceeds 900,000, the islands of the acrylic resin become large, and it cannot be said that the islands of the acrylic resin and the entire cured product of the epoxy compound are adhered to the oxide film. , Adhesive strength decreases.

The content of the acrylic resin is preferably 1 to 10 parts by mass, more preferably 1 to 5 parts by mass with respect to 100 parts by mass of the epoxy compound. When the content of the acrylic resin is 1 to 10 parts by mass with respect to 100 parts by mass of the epoxy compound, it is possible to obtain a cured product in which the islands of the acrylic resin are dispersed in the sea of the epoxy resin at a good density. ..

As the alicyclic epoxy compound, those having two or more epoxy groups in the molecule are preferably mentioned. These may be liquid or solid. Specific examples thereof include 3,4-epoxycyclohexenylmethyl-3', 4'-epoxycyclohexene carboxylate, glycidyl hexahydrobisphenol A and the like. Among these, 3,4-epoxycyclohexenylmethyl-3', 4'-epoxycyclohexene can ensure light transmission suitable for mounting LED elements on a cured product and has excellent quick-curing properties. Carboxylates are preferably used.

As the hydrogenated epoxy compound, a hydrogenated product of the above-mentioned alicyclic epoxy compound or a known hydrogenated epoxy compound such as bisphenol A type or bisphenol F type can be used.

The alicyclic epoxy compound and the hydrogenated epoxy compound may be used alone, but two or more kinds may be used in combination. Further, in addition to these epoxy compounds, other epoxy compounds may be used in combination as long as the effects of the present invention are not impaired. For example, bisphenol A, bisphenol F, bisphenol S, tetramethylbisphenol A, diarylbisphenol A, hydroquinone, catechol, resorcin, cresol, tetrabromobisphenol A, trihydroxybiphenyl, benzophenone, bisresolsinol, bisphenol hexafluoroacetone, tetramethylbisphenol. Glycidyl ether obtained by reacting epichlorohydrin with polyhydric phenols such as A, tetramethylbisphenol F, tris (hydroxyphenyl) methane, bixylenol, phenol novolac, cresol novolac; glycerin, neopentyl glycol, ethylene glycol, propylene glycol , Polyglycidyl ether obtained by reacting aliphatic polyhydric alcohols such as hexylene glycol, polyethylene glycol and polypropylene glycol with epichlorohydrin; hydroxycarboxylic acids such as p-oxybenzoic acid and β-oxynaphthoic acid and epichlorohydrin. Glysidyl ether ester obtained by reacting with; phthalic acid, methylphthalic acid, isophthalic acid, terephthalic acid, tetrahydrophthalic acid, endomethylenetetrahydrophthalic acid, endomethylenehexahydrophthalic acid, trimellitic acid, polymerized fatty acids, etc. Polyglycidyl ester obtained from polycarboxylic acid; glycidyl aminoglycidyl ether obtained from aminophenol, aminoalkylphenol; glycidyl aminoglycidyl ester obtained from aminobenzoic acid; aniline, toluidin, tribromaniline, xylylene diamine, diaminocyclohexane, bis. Glysidylamines obtained from aminomethylcyclohexane, 4,4'-diaminodiphenylmethane, 4,4'-diaminodiphenylsulfone and the like; known epoxy resins such as epoxidized polyolefins can be mentioned.

Examples of the cation catalyst include latent cation curing agents such as aluminum chelate-based latent curing agents, imidazole-based latent curing agents, and sulfonium-based latent curing agents. Among these, an aluminum chelate-based latent curing agent having excellent fast-curing properties is preferably used.

If the content of the cation catalyst is too small, the reactivity tends to be lost, and if it is too large, the product life of the adhesive tends to be shortened. Therefore, the content is preferably 0.1 to 30 parts by mass with respect to 100 parts by weight of the epoxy compound. It is preferably 0.5 to 20 parts by mass.

In addition, the insulating binder may further contain light-reflecting insulating particles as another component. The light-reflecting insulating particles are preferably at least one selected from the group consisting of _{titanium oxide (TiO 2} ), boron nitride (BN), zinc oxide (ZnO) and aluminum oxide (Al ₂ O _3). Since these light-reflecting insulating particles themselves are gray to white under natural light, the wavelength dependence of the reflection characteristics on visible light is small, and the luminous efficiency can be improved. Among these, titanium oxide having a high refractive index is preferably used.

In addition, the insulating binder may further contain a silane coupling agent as another component in order to improve the adhesiveness at the interface with the inorganic material. Examples of the silane coupling agent include epoxy-based, methacryloxy-based, amino-based, vinyl-based, mercapto-sulfide-based, and ureido-based agents, which may be used alone or in combination of two or more. May be good.

In addition, the insulating binder may contain an inorganic filler in order to control the fluidity and improve the particle capture rate. The inorganic filler is not particularly limited, but silica, talc, titanium oxide, calcium carbonate, magnesium oxide and the like can be used. Such an inorganic filler can be appropriately used for the purpose of relieving the stress of the connecting structure connected by the adhesive. Further, a softener such as a thermoplastic resin or a rubber component may be blended.

According to such an insulating binder, a high adhesive force can be obtained for a difficult-to-adhere metal such as aluminum wiring.

<2. Connection structure and its manufacturing method>
Next, the connection structure using the anisotropic conductive adhesive described above will be described. The connecting structure according to the present embodiment includes a base material made of resin and a base material between the first electronic component, the second electronic component, and the first electronic component and the second electronic component. Conductive particles having a conductive layer arranged on the surface, having a K value of 50 to 400 Kgf / mm ² at the time of 30% compressive deformation, and a recovery rate of 16 to 48% at the time of 30% compressive deformation. A terminal of a first electronic component and a second electronic component are provided with an anisotropic conductive adhesive obtained by curing an anisotropic conductive adhesive containing solder particles, conductive particles, and a binder that disperses the solder particles. The terminals of electronic components are electrically connected via conductive particles and are joined by solder particles. As a result, excellent connection reliability can be obtained for aluminum wiring, and excellent heat dissipation can be obtained by joining with solder particles.

As the first electronic component in the present embodiment, a chip (element) such as an LED (Light Emitting Diode) or a driver IC (Integrated Circuit) that emits heat is suitable, and as a second electronic component, a chip is used. The board to be mounted is suitable.

FIG. 1 is a cross-sectional view showing a configuration example of an LED mounting body. In this LED mounting body, the LED element and the substrate are connected by using an anisotropic conductive adhesive in which the above-mentioned conductive particles 31 and solder particles 32 are dispersed in an insulating binder.

The LED element includes, for example, a first conductive clad layer 12 made of, for example, n-GaN, and an active layer 13 made of, for _{example, an In x} Al _y Ga _{1-xy N layer, on an element substrate 11 made of sapphire.} It is provided with a second conductive clad layer 14 made of p-GaN, and has a so-called double heterostructure. Further, a first conductive electrode 12a is provided on a part of the first conductive clad layer 12, and a second conductive electrode 14a is provided on a part of the second conductive clad layer 14. When a voltage is applied between the first conductive electrode 12a and the second conductive electrode 14a of the LED element, the carriers are concentrated on the active layer 13 and recombinated to generate light.

The substrate is provided with a first conductive type circuit pattern 22 and a second conductive type circuit pattern 23 on the base material 21, and is positioned corresponding to the first conductive type electrode 12a and the second conductive type electrode 14a of the LED element. Has an electrode 22a and an electrode 23a, respectively.

As shown in FIG. 1, in the LED mount, the terminals of the LED element (electrodes 12a and 14a) and the terminals of the substrate (electrodes 22a and 23a) are electrically connected via the conductive particles 31, and further. It is joined by solder particles 32. As a result, the contact area between the terminals is increased, the heat generated in the active layer 13 of the LED element can be efficiently dissipated to the substrate side, the decrease in luminous efficiency can be prevented, and the life of the LED mount can be extended. it can.

Further, as shown in FIG. 2, in the LED element for mounting the flip chip, since the terminals (electrodes 12a and 14a) of the LED element are designed to be large by the passivation 15, the terminals (electrodes 12a and 14a) of the LED element are designed to be large. ) And the terminals (circuit patterns 22 and 23) of the substrate, more conductive particles 31 and solder particles 32 are captured. As a result, the heat generated in the active layer 13 of the LED element can be released to the substrate side more efficiently.

Next, a method of manufacturing the above-mentioned connection structure will be described. The method for producing a connecting structure in the present embodiment has a base material made of resin and a conductive layer arranged on the surface of the base material, and has a K value of 50 to 400 Kgf / mm ^{2 at the time of 30% compressive deformation.} An anisotropic conductive adhesive containing conductive particles having a recovery rate of 16 to 48% at the time of 30% compression deformation, solder particles, conductive particles, and a binder that disperses the solder particles. It is interposed between the terminal of the first electronic component and the terminal of the second electronic component, and heat-bonds the first electronic component and the second electronic component.

According to the method for manufacturing the connection structure in the present embodiment, the conductive particles are flattened and electrically connected by pressing during crimping, and the contact area between the opposing terminals is increased by joining with the solder particles. Therefore, high heat dissipation and high connection reliability can be obtained.

<3. Example>
Hereinafter, examples of the present invention will be described in detail, but the present invention is not limited to these examples. In this example, an LED mount was prepared using an anisotropic conductive adhesive, and the conduction reliability and heat dissipation were evaluated.

3.1 Evaluation of Conductive Reliability for Compressive Deformation of Conductive Particles <Experimental Examples 1-12>
[Preparation of anisotropic conductive adhesive]
Alicyclic epoxy compound (product name: Celoxide 2021P, manufactured by Daicel Chemical Co., Ltd.) 100 parts by mass, latent cation curing agent (aluminum-cleaning latent curing agent) 5 parts by mass, acrylic resin (butyl acrylate (BA): 15) %, Ethyl acrylate (EA): 63%, Nitrile acrylate (AN): 20%, Acrylic acid (AA): 1 w%, 2-Hydroxyethyl methacrylate (HEMA): 1 wt%, Weight average molecular weight Mw: 70 Ten thousand) In a binder composed of 3 parts by mass, 50 parts by mass of solder particles having an average particle diameter of 10 μm and a melting point of 150 ° C. and 5 parts by mass of conductive particles shown in Table 1 are blended to obtain anisotropic conductivity. An adhesive was prepared.

[Preparation of LED mounting sample]
After applying the anisotropic conductive adhesive to the aluminum wiring board A (fluorine resin substrate, conductor space = 100 μmP, Ni / Au plating = 5.0 / 0.3 μm), the LED chip for FC mounting (trade name: DA3547, Made by CREE, Vf = 3.08V / If = 60mA) was aligned and mounted. Then, heat crimping was performed under the conditions of 180 ° C. for 60 seconds and a load of 0.8 N / chip to prepare an LED mounting sample A.

Further, after applying to an aluminum wiring board B (PET substrate, conductor space = 100 μmP, Ni / Au plating = 5.0 / 0.3 μm) using an anisotropic conductive adhesive, an LED chip for FC mounting (commodity). Name: DA3547, manufactured by CREE, Vf = 3.08V / If = 60mA) was aligned and mounted. Then, heat crimping was performed under the conditions of 180 ° C. for 60 seconds and a load of 0.8 N / chip to prepare an LED mounting sample B.

[Evaluation of conduction resistance]
The conduction resistance of each of the LED mounting samples A and B was measured at the initial stage and after the thermal cycle test (TCT). In the cold cycle test, the LED mounting sample was exposed to an atmosphere of −40 ° C. and 100 ° C. for 30 minutes each, and 100, 500, and 1000 cycles were performed with this as one cycle, and the conduction resistance was measured for each. For the evaluation of conduction resistance, the Vf value when If = 50 mA is measured, and when the increase in Vf value from the Vf value in the test report is less than 5%, it is regarded as "OK", and the fluctuation from the initial Vf value is regarded as "OK". The case of 5% or more was regarded as "NG". Table 1 shows the evaluation results of the conduction resistance of the LED mounting samples A and B.

In Experimental Examples 6 and 7, since nickel particles were used, there was no compression deformation, so that they could not be connected to either the aluminum wiring board A (fluororesin substrate) or the aluminum wiring board B (PET substrate).

Further, in Experimental Example 8, the K value of the conductive particles at the time of 30% compressive deformation ^{exceeds 400 Kgf / mm 2} , and in Experimental Examples 9 and 10, the recovery rate of the conductive particles at the time of 30% compressive deformation Is less than 16%, and in Experimental Examples 11 and 12, the K value of the ^{conductive particles at the time of 30% compression deformation exceeds 400 Kgf / mm 2} , and the recovery rate of the conductive particles at the time of 30% compression deformation is 16%. Since it is less than, it could not be connected to either the aluminum wiring board A (fluorine resin substrate) or the aluminum wiring board B (PET substrate).

On the other hand, in Experimental Examples 1 to 5, the K value of the conductive particles at the time of 30% compression deformation is 50 to 400 Kgf / mm ² , and the recovery rate of the conductive particles at the time of 30% compression deformation is 16 to 48%. Therefore, both the aluminum wiring board A (fluororesin substrate) and the aluminum wiring board B (PET substrate) were able to obtain excellent connection reliability. It is considered that this is because the conductive particles are compressed at a relatively low pressure to remove the oxide film existing on the surface of the aluminum wiring, and the recovery rate is not significantly large.

3.2 Evaluation of conduction reliability by mounting method <Experimental example 13>
An attempt was made to mount an LED chip by reflowing at 260 ° C. using solder (melting point 217 ° C.) instead of the anisotropic conductive adhesive. However, it could not be connected to either the aluminum wiring board A (fluororesin substrate) or the aluminum wiring board B (PET substrate).

<Experimental Example 14>
An attempt was made to mount an LED chip by reflowing at 300 ° C. using gold-tin eutectic solder (melting point 280 ° C.) instead of the anisotropic conductive adhesive. However, it could not be connected to either the aluminum wiring board A (fluororesin substrate) or the aluminum wiring board B (PET substrate).

<Experimental Example 15>
An attempt was made to mount an LED chip by ultrasonic fusion with an apparatus using a wire bond instead of an anisotropic conductive adhesive. However, it could not be connected to either the aluminum wiring board A (fluororesin substrate) or the aluminum wiring board B (PET substrate).

Since Experimental Examples 13 to 15 are not mounting methods using an anisotropic conductive adhesive, they could not be connected to either the aluminum wiring board A (fluororesin substrate) or the aluminum wiring board B (PET substrate). ..

3.3 Evaluation of heat dissipation <Experimental example 16>
[Preparation of anisotropic conductive adhesive]
Alicyclic epoxy compound (product name: Celoxide 2021P, manufactured by Daicel Chemical Co., Ltd.) 100 parts by mass, latent cation curing agent (aluminum-cleaning latent curing agent) 5 parts by mass, acrylic resin (butyl acrylate (BA): 15) %, Ethyl acrylate (EA): 63%, Nitrile acrylate (AN): 20%, Acrylic acid (AA): 1 w%, 2-Hydroxyethyl methacrylate (HEMA): 1 wt%, Weight average molecular weight Mw: 70 In a binder composed of 3 parts by mass, 50 parts by mass of solder particles having a melting point of 150 ° C. and the conductive particles (resin core / Ni / Au plating, average particle diameter 5 μm, 30) used in Experimental Example 1 An anisotropic conductive adhesive was prepared by blending 5 parts by mass of a K value of 215 kgf / mm ² at the time of% compressive deformation and a recovery rate of 18% at the time of 30% compressive deformation).

[Preparation of LED mounting sample]
After applying the anisotropic conductive adhesive to the aluminum wiring board B (PET substrate, conductor space = 100 μmP, Ni / Au plating = 5.0 / 0.3 μm), the LED chip for FC mounting (trade name: DA3547, CREE) Made by the company, Vf = 3.08V / If = 60mA) was aligned and mounted. Then, heat crimping was performed under the conditions of 180 ° C. for 60 seconds and a load of 0.8 N / chip to prepare an LED mounting sample.

<Experimental example 17>
In the binder of Experimental Example 16, the conductive particles used in Experimental Example 1 (resin core / Ni / Au plating, average particle diameter 5 μm, K value at 30% compression deformation 215 kgf / mm ² , at 30% compression deformation An LED-mounted sample was prepared in the same manner as in Experimental Example 16 except that an anisotropic conductive adhesive containing only 5 parts by mass of recovery rate (18%) was used.

<Experimental Example 18>
An LED mounting sample was prepared in the same manner as in Experimental Example 16 except that an anisotropic conductive adhesive containing only 50 parts by mass of solder particles having a melting point of 150 ° C. was used in the binder of Experimental Example 16.

[Evaluation of thermal resistance value (heat dissipation)]
As a reference (reference example), the thermal resistance value (K / W) was measured using a transient thermal resistance measuring device (manufactured by CATS Electronics Design Co., Ltd.) for a sample in which an LED was mounted on a copper wiring PET substrate using solder. .. The measurement conditions were If = 60 mA (constant current control). Then, the thermal resistance values of Experimental Examples 16 to 18 were converted with the thermal resistance value of the reference as 100%. Table 2 shows the evaluation results of the thermal resistance values of each LED mounting sample.

From Experimental Examples 16 to 18, it was found that the solder particles greatly contribute to the heat dissipation property of dissipating heat to the substrate while playing an auxiliary role of conduction to the aluminum wiring.

3.4 Evaluation of Conductive Reliability with respect to the Blending Amount of Conductive Particles and Solder Particles <Experimental Examples 19 to 24>
[Preparation of anisotropic conductive adhesive]
Alicyclic epoxy compound (product name: Celoxide 2021P, manufactured by Daicel Chemical Co., Ltd.) 100 parts by mass, latent cation curing agent (aluminum-cleaning latent curing agent) 5 parts by mass, acrylic resin (butyl acrylate (BA): 15) %, Ethyl acrylate (EA): 63%, Nitrile acrylate (AN): 20%, Acrylic acid (AA): 1 w%, 2-Hydroxyethyl methacrylate (HEMA): 1 wt%, Weight average molecular weight Mw: 70 (10,000) In a binder composed of 3 parts by mass, the conductive particles (resin core / Ni / Au plating, average particle diameter 5 μm, K value at 30% compression deformation 215 kgf / mm ² , 30) used in Experimental Example 1 % Recovery rate at the time of compression deformation) and solder particles (melting point 150 ° C., particle diameter 10 μm) are shown in Table 3 (mass part (conductive particles / solder particles), Experimental Example 19: 5/50, Experiment Example 20: 8/50, Experimental Example 21: 12/50, Experimental Example 22: 15/60, Experimental Example 23: 8/120, Experimental Example 24: 15/150). Was produced.

[Preparation of LED mounting sample]
An LED chip for FC mounting (trade name: DA3547, CREE) is attached to an aluminum wiring board B (PET substrate, conductor space = 100 μmP, Ni / Au plating = 5.0 / 0.3 μm) using an anisotropic conductive adhesive. Made by the company, Vf = 3.08V / If = 60mA) was installed.

After applying the anisotropic conductive adhesive to the aluminum wiring board B, the LED chip is mounted on the aluminum wiring board, and heat-pressed under the conditions of 180 ° C.-60 seconds and a load of 0.8 N / chip to prepare an LED mounting sample. Made.
[Reliability test (TCT test)]

The LED mounting sample was evaluated by measuring the conduction resistance at the initial stage and after the 1000 cycle TCT test. The measurement condition of the conduction resistance was If = 60 mA (constant current control). The evaluation was "OK" when the amount of change in the Vf value was within 0 to 0.1 V in the initial stage and after the 1000-cycle TCT test, and "NG" in other cases.

<Experimental Examples 25 to 31>
The amount of conductive particles shown in Table 3 (Experimental Example 25: 1 parts by mass, Experimental Example 26: 3 parts by mass, Experimental Example 27: 5 parts by mass, Experimental Example 28: 8 parts by mass) without blending solder particles. , Experimental Example 29:15 parts by mass, Experimental Example 30:20 parts by mass, Experimental Example 31:50 parts by mass), an anisotropic conductive adhesive was prepared in the same manner as in Experimental Example 19 and conducted. The reliability was evaluated.

<Experimental Examples 32-38>
The amount of solder particles shown in Table 3 (Experimental Example 32:30 parts by mass, Experimental Example 33:50 parts by mass, Experimental Example 34:60 parts by mass, Experimental Example 35: 100 parts by mass) without blending conductive particles. , Experimental Example 36: 120 parts by mass, Experimental Example 37: 150 parts by mass, Experimental Example 38: 200 parts by mass). The reliability was evaluated.

In Experimental Examples 25 to 31, the conduction resistance after the TCT test was OK, but since no solder particles were mixed, the thermal resistance was high and the heat dissipation was low as shown in Experimental Example 17. Further, in Experimental Examples 32 to 38, since the conductive particles were not blended, the lights were turned off in about 100 cycles in the TCT test.

On the other hand, in Experimental Examples 19 to 24, 5 to 15 parts by mass of conductive particles and 50 to 150 parts by mass of solder particles are blended with respect to 108 parts by mass of the binder, so that the thermal resistance is high as shown in Experimental Example 16. It was low and the conduction resistance after the TCT test was OK.

3.5 Evaluation of conduction reliability for large current (700 mA) <Experimental Examples 39 to 44>
[Preparation of anisotropic conductive adhesive]
Alicyclic epoxy compound (product name: Celoxide 2021P, manufactured by Daicel Chemical Co., Ltd.) 100 parts by mass, latent cation curing agent (aluminum-cleaning latent curing agent) 5 parts by mass, acrylic resin (butyl acrylate (BA): 15) %, Ethyl acrylate (EA): 63%, Nitrile acrylate (AN): 20%, Acrylic acid (AA): 1 w%, 2-Hydroxyethyl methacrylate (HEMA): 1 wt%, Weight average molecular weight Mw: 70 (10,000) In a binder composed of 3 parts by mass, the conductive particles (resin core / Ni / Au plating, average particle diameter 5 μm, K value at 30% compression deformation 215 kgf / mm ² , 30) used in Experimental Example 1 % Recovery rate at the time of compression deformation) and solder particles (melting point 150 ° C., particle diameter 10 μm) are shown in Table 4 (mass part (conductive particles / solder particles), Experimental Example 39: 5/50, Experiment Example 40: 8/50, Experimental Example 41: 12/50, Experimental Example 42: 15/60, Experimental Example 43: 8/120, Experimental Example 44: 15/150). Was produced.

[Preparation of LED mounting sample]
An LED chip for FC mounting (trade name: DA700, CREE) is attached to an aluminum wiring board B (PET substrate, conductor space = 100 μmP, Ni / Au plating = 5.0 / 0.3 μm) using an anisotropic conductive adhesive. It was equipped with Vf = 3.2V / If = 350mA) manufactured by the company.

After applying the anisotropic conductive adhesive to the aluminum wiring board B, the LED chip is mounted on the aluminum wiring board, and heat-pressed under the conditions of 180 ° C.-60 seconds and a load of 0.8 N / chip to prepare an LED mounting sample. Made.

[Reliability test (TCT test)]
The LED mounting sample was evaluated by measuring the conduction resistance after the initial continuity and the TCT test of 500 cycles, 1000 cycles, and 2000 cycles. The measurement conditions for the conduction resistance were If = 350 mA (constant current control) and 700 mA (constant current control). The evaluation was performed according to the following criteria. Table 4 shows the evaluation results of the conduction resistance value of each LED mounting sample.
(Evaluation criteria)
A: Normal conduction (change in Vf value: 0 to less than 0.1V)
B: Several resistance rises and poor continuity occurs (change of 0.1V or more to non-lighting)
C: Conduction failure occurs at the moment when current is applied (not lit)

In Experimental Examples 39 to 44, 5 to 15 parts by mass of conductive particles and 50 to 150 parts by mass of solder particles are mixed with 108 parts by mass of the binder, so that the current of 350 mA is the same as in Experimental Examples 19 to 24. We were able to obtain long-term reliability. In particular, in Experimental Examples 43 and 44, the amount of the conductive particles compounded was 8 to 15 parts by mass with respect to 100 parts by mass of the binder, and the amount of the solder particles compounded was 120 to 150 parts by mass with respect to 100 parts by mass of the binder. This made it possible to obtain long-term reliability for a current of 700 mA for aluminum wiring. It is considered that this is because the solder particles play an auxiliary role of conduction and dissipate heat generated by a large current to the substrate.

11 element substrate, 12 first conductive type clad layer, 13 active layer, 14 second conductive type clad layer, 21 base material, 22 first conductive type circuit pattern, 23 second conductive type circuit pattern, 15 passivation, 31 Conductive particles, 32 solder particles, 33 binders

Claims (9)

It has a base material made of resin and a conductive layer arranged on the surface of the base material, has a K value of 50 to 400 Kgf / mm ² at the time of 30% compression deformation, and has a recovery rate at the time of 30% compression deformation. With conductive particles that are 16-48%
With solder particles
An anisotropic conductive adhesive containing the conductive particles and a binder for dispersing the solder particles. The anisotropic conductive adhesive according to claim 1, wherein the amount of the conductive particles blended is 5 to 50 parts by mass with respect to 100 parts by mass of the binder. The anisotropic conductive adhesive according to claim 1 or 2, wherein the amount of the solder particles blended is 30 to 200 parts by mass with respect to 100 parts by mass of the binder. The blending amount of the conductive particles is 5 to 15 parts by mass with respect to 100 parts by mass of the binder.
The anisotropic conductive adhesive according to claim 1 or 2, wherein the amount of the solder particles blended is 50 to 150 parts by mass with respect to 100 parts by mass of the binder. The anisotropic conductive adhesive according to any one of claims 1 to 4, wherein the average particle size of the conductive particles is smaller than the average particle size of the solder particles. The average particle size of the conductive particles is 3 to 10 μm.
The anisotropic conductive adhesive according to claim 5, wherein the average particle size of the solder particles is 5 to 20 μm. The first electronic component and
The second electronic component and
A base material made of resin and a conductive layer arranged on the surface of the base material are provided between the first electronic component and the second electronic component, and the K value at the time of 30% compression deformation is It contains conductive particles having a recovery rate of 50 to 400 Kgf / mm ² and a recovery rate at the time of 30% compression deformation of 16 to 48%, solder particles, the conductive particles, and a binder for dispersing the solder particles. With an anisotropic conductive film obtained by curing the anisotropic conductive adhesive,
A connection structure in which a terminal of the first electronic component and a terminal of the second electronic component are electrically connected via the conductive particles and are joined by the solder particles. The first electronic component is an LED element.
The connection structure according to claim 7, wherein the second electronic component is a substrate. It has a base material made of resin and a conductive layer arranged on the surface of the base material, has a K value of 50 to 400 Kgf / mm ² at the time of 30% compression deformation, and has a recovery rate at the time of 30% compression deformation. An anisotropic conductive adhesive containing 16 to 48% of conductive particles, solder particles, the conductive particles, and a binder that disperses the solder particles is applied to the terminals of the first electronic component and the second. A method for manufacturing a connection structure in which a first electronic component and a second electronic component are heat-bonded so as to be interposed between the terminals of the electronic component.

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