JP2014065765A - Anisotropic conductive adhesive - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an anisotropic conductive adhesive which is capable of achieving high heat dissipation performance.SOLUTION: Conductive particles (31) and diamond particles (32) with an average grain diameter smaller than that of the conductive particles (31) are dispersed in a binder. In an LED package which is obtained by thermal compression bonding using this anisotropic conductive adhesive, terminals (electrodes (12a, 14a)) of an LED element and terminals (electrodes (22a, 23a)) of a substrate are electrically connected with each other through the conductive particles (31), while the diamond particles (32) are caught between the terminals of the LED element and the terminals of the substrate.

Description

  The present invention relates to an anisotropic conductive adhesive in which conductive particles are dispersed, and in particular, can dissipate heat generated by a chip (element) such as a driver IC (Integrated Circuit) or an LED (Light Emitting Diode). The present invention relates to an anisotropic conductive adhesive.

  Conventionally, a wire bond method has been used as a method for mounting LED elements on a substrate. As shown in FIG. 3, in the wire bonding method, the electrodes (first conductivity type electrode 104a and second conductivity type electrode 102a) of the LED element face upward, and the LED element and the substrate are electrically joined. Is performed by wire bonding (WB) 301a and 301b, and a die bonding material 302 is used for bonding the LED element and the substrate.

  However, in such a method of obtaining electrical connection by wire bonding, there is a risk of physical breakage / peeling of the wire bond from the electrodes (the first conductivity type electrode 104a and the second conductivity type electrode 102a). High-quality technology is required. Furthermore, since the curing process of the die bond material 302 is performed by oven curing, it takes time for production.

  As shown in FIG. 4, the LED element electrodes (first conductivity type electrode 104a and second conductivity type electrode 102a) face toward the substrate side (face down, flip chip) as shown in FIG. There is a method of using conductive bases 303a and 303b typified by silver paste for electrical connection between the element and the substrate.

  However, since the conductive pastes 303a and 303b have low adhesive strength, reinforcement with the sealing resin 304 is necessary. Furthermore, since the curing process of the sealing resin 304 is performed by oven curing, production takes time.

  As a method of using no conductive paste, as shown in FIG. 5, the electrode surface of the LED element is directed to the substrate side (face down, flip chip), and the electrical connection and adhesion between the LED element and the substrate are insulative. There is a method of using an anisotropic conductive adhesive in which conductive particles 306 are dispersed in an adhesive binder 305. Since the anisotropic conductive adhesive has a short bonding process, the production efficiency is good. An anisotropic conductive adhesive is inexpensive and excellent in transparency, adhesiveness, heat resistance, mechanical strength, electrical insulation, and the like.

  In recent years, LED elements for flip chip mounting have been developed. Since the FC mounting LED element can be designed to have a large electrode area by the passivation 105, bumpless mounting is possible. Further, the light extraction efficiency is improved by providing a reflective film under the light emitting layer.

  As a method for mounting the FC mounting LED element on the substrate, gold-tin eutectic bonding is used as shown in FIG. Gold-tin eutectic bonding is a method in which a chip electrode is formed of an alloy 307 of gold and tin, a flux is applied to a substrate, the chip is mounted and heated, and eutectic bonding is performed with the substrate electrode. However, such a solder connection method has a bad yield because there is an adverse effect on reliability due to chip displacement during heating or flux that could not be cleaned. In addition, advanced mounting technology is required.

  As a method not using gold-tin eutectic, there is a solder connection method using a solder paste for electrical connection between the electrode surface of the LED element and the substrate, as shown in FIG. However, in such a solder connection method, since the paste has isotropic conductivity, the pn electrodes are short-circuited and the yield is poor.

  As shown in FIG. 8, as a method not using a solder paste, the electrical connection and adhesion between the LED element and the substrate are different from each other, such as ACF in which conductive particles are dispersed in an insulating binder, as in FIG. There is a method using an anisotropic conductive adhesive. The anisotropic conductive adhesive is filled with an insulating binder between the pn electrodes. Accordingly, the yield is good because short-circuiting hardly occurs. Moreover, since the bonding process is short, the production efficiency is good.

  By the way, the active layer (junction) 103 of the LED element generates a lot of heat in addition to light, and when the light emitting layer temperature (Tj = junction temperature) reaches 100 ° C. or more, the luminous efficiency of the LED decreases, Life is shortened. Therefore, a structure for efficiently releasing the heat of the active layer 103 is necessary.

  In the WB mounting as shown in FIG. 3, since the active layer 103 is located on the upper side of the LED element, the generated heat is not efficiently transferred to the substrate side, so the heat dissipation is poor.

  Further, when flip-chip mounting as shown in FIGS. 4, 6, and 7 is performed, the active layer 103 is located on the substrate side, so that heat is efficiently transmitted to the substrate side. As shown in FIGS. 4 and 7, when the electrodes are joined with the conductive pastes 303a and 303b, heat can be radiated with high efficiency, but the connection with the conductive pastes 303a and 303b is connected as described above. Reliability is bad. Also, as shown in FIG. 6, even when gold-tin eutectic bonding is performed, the connection reliability is poor as described above.

  Also, as shown in FIGS. 5 and 8, by using flip-chip mounting with an anisotropic conductive adhesive such as ACF (Anisotropic Conductive Paste) or ACP (Anisotropic Conductive Paste) without using the conductive pastes 303a and 303b, The active layer 103 is disposed near the substrate side, and heat is efficiently transmitted to the substrate side. Moreover, since the adhesive force is high, high connection reliability can be obtained.

Japanese Unexamined Patent Publication No. 2000-1223639

  However, since the heat conductivity of the cured product of the conventional anisotropic conductive adhesive is about 0.2 W / (m · K), the heat generated from the LED element cannot be sufficiently released to the substrate side. Further, in flip chip mounting using an anisotropic conductive adhesive, only the conductive particles in the electrical connection portion serve as a heat dissipation path, so that the heat dissipation is poor.

  In addition, it is conceivable to increase the thermal conductivity by filling the binder of the anisotropic conductive adhesive with a high heat dissipation filler, but the viscosity of the binder increases, resulting in poor handling properties. Moreover, since the resin component decreases as the filler amount increases, cracks and a decrease in adhesive strength occur.

  The present invention has been proposed in view of such conventional circumstances, and provides an anisotropic conductive adhesive capable of obtaining high heat dissipation.

  As a result of intensive studies, the present inventor has found that the above object can be achieved by blending diamond particles, and has completed the present invention.

  That is, the anisotropic conductive adhesive according to the present invention is characterized in that conductive particles and diamond particles having an average particle size smaller than that of the conductive particles are dispersed in a binder.

  In the connection structure according to the present invention, the terminal of the first electronic component and the terminal of the second electronic component are electrically connected via the conductive particles, and the terminal of the first electronic component and the second electronic component are electrically connected. It is characterized in that diamond particles are captured between the terminals of the two electronic components.

  According to the present invention, the conductive particles are crushed during thermocompression bonding, and the diamond particles are captured between the opposing terminals, so that high heat dissipation can be obtained.

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 other one Embodiment of this invention. It is sectional drawing which shows an example of the LED mounting body by a wire bond construction method. It is sectional drawing which shows an example of the LED mounting body using an electrically conductive paste. It is sectional drawing which shows an example of the LED mounting body using an anisotropic conductive adhesive. It is sectional drawing which shows an example of the LED mounting body which mounted LED for FC mounting by gold tin eutectic bonding. It is sectional drawing which shows an example of the LED mounting body which mounted LED for FC mounting with the electrically conductive paste. It is sectional drawing which shows an example of the LED mounting body which mounted LED for FC mounting by anisotropic conductive adhesive.

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 and method for producing the same 2. Connection structure and manufacturing method thereof Example

<1. Anisotropic conductive adhesive and method for producing the same>
The anisotropic conductive adhesive in the present embodiment is obtained by dispersing conductive particles and diamond particles having an average particle size smaller than the conductive particles in a binder, and the shape thereof is a paste, a film, or the like. Yes, it can be selected appropriately according to the purpose.

  As the conductive particles, for example, metal particles such as gold particles, silver particles and nickel particles, and metal-coated resin particles obtained by coating the surface of resin particles such as benzoguanamine resin and styrene resin with a metal such as gold, nickel and zinc are used. be able to. Since the metal-coated resin particles are easily crushed and easily deformed during compression, the contact area with the connection pattern can be increased, and variations in the height of the connection pattern can be absorbed.

  Moreover, it is preferable that the average particle diameter of electroconductive particle is 1-10 micrometers, More preferably, it is 2-6 micrometers. Moreover, it is preferable that the compounding quantity of electroconductive particle is 1-100 mass parts with respect to 100 mass parts of binders from a viewpoint of connection reliability and insulation reliability.

  Diamond particles have a very high thermal conductivity compared to metal particles such as silver, copper, and gold, and function as thermally conductive particles. The average particle diameter (D50) of the diamond particles is preferably 5 to 80% of the average particle diameter of the conductive particles. If the diamond particles are too small with respect to the conductive particles, the diamond particles are not captured between the terminals facing each other at the time of pressure bonding, and excellent heat dissipation cannot be obtained. On the other hand, if the diamond particles are too large relative to the conductive particles, the diamond particles cannot be highly filled, and the thermal conductivity of the cured product of the anisotropic conductive adhesive cannot be improved.

  Moreover, it is preferable that the compounding quantity of a diamond particle is 8-50 volume% with respect to an anisotropic conductive adhesive. When the blending amount of the diamond particles is too small, high heat dissipation cannot be obtained, and when the blending amount is too large, the electrical connection of the conductive particles is hindered.

  The diamond particles are preferably white or gray achromatic. Thereby, since a diamond particle functions as a light reflection particle, when it uses for an LED element, high brightness | luminance can be obtained.

  As a binder, the adhesive composition currently used in the conventional anisotropic conductive adhesive and anisotropic conductive film can be utilized. Preferred examples of the adhesive composition include an epoxy curable adhesive mainly composed of an alicyclic epoxy compound, a heterocyclic epoxy compound, a hydrogenated epoxy compound, or the like.

  Preferred examples of the alicyclic epoxy compound include those having two or more epoxy groups in the molecule. These may be liquid or solid. Specific examples include glycidyl hexahydrobisphenol A, 3,4-epoxycyclohexenylmethyl-3 ', 4'-epoxycyclohexene carboxylate, and the like. Among these, 3,4-epoxycyclohexenylmethyl-3 ′, 4′-epoxycyclohexenecarboxylate is preferred because it can ensure light transmission suitable for mounting LED elements on the cured product and is excellent in rapid curing. Can be preferably used.

  Examples of the heterocyclic epoxy compound include an epoxy compound having a triazine ring, and 1,3,5-tris (2,3-epoxypropyl) -1,3,5-triazine-2,4 is particularly preferable. 6- (1H, 3H, 5H) -trione can be mentioned.

  As the water-added epoxy compound, hydrogenated products of the above-described alicyclic epoxy compounds and heterocyclic epoxy compounds, and other known hydrogenated epoxy resins can be used.

  Although an alicyclic epoxy compound, a heterocyclic epoxy compound, and a hydrogenated epoxy compound may be used independently, 2 or more types can be used together. 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, bisresorcinol, bisphenol hexafluoroacetone, tetramethylbisphenol A, glycidyl ether obtained by reacting polychlorophenol such as tetramethylbisphenol F, tris (hydroxyphenyl) methane, bixylenol, phenol novolak, cresol novolak and epichlorohydrin; glycerin, neopentyl glycol, ethylene glycol, propylene glycol , Hexylene glycol, polyethylene glycol, polyp Polyglycidyl ether obtained by reacting an aliphatic polyhydric alcohol such as pyrene glycol with epichlorohydrin; a glycidyl ether obtained by reacting a hydroxycarboxylic acid such as p-oxybenzoic acid or β-oxynaphthoic acid with epichlorohydrin Esters: polyglycidyl esters obtained from polycarboxylic acids such as phthalic acid, methylphthalic acid, isophthalic acid, terephthalic acid, tetrahydrophthalic acid, endomethylenetetrahydrophthalic acid, endomethylenehexahydrophthalic acid, trimet acid, polymerized fatty acid Glycidylaminoglycidyl ether obtained from aminophenol, aminoalkylphenol; glycidylaminoglycidyl ester obtained from aminobenzoic acid; aniline, toluidine, tribromourea Glycidylamine obtained from nilin, xylylenediamine, diaminocyclohexane, bisaminomethylcyclohexane, 4,4′-diaminodiphenylmethane, 4,4′-diaminodiphenylsulfone, and the like; and known epoxy resins such as epoxidized polyolefin .

  Examples of the curing agent include acid anhydrides, imidazole compounds, and dicyan. Among these, acid anhydrides that are difficult to discolor the cured product, particularly alicyclic acid anhydride-based curing agents, can be preferably used. Specifically, methylhexahydrophthalic anhydride etc. can be mentioned preferably.

  In the adhesive composition, when an alicyclic epoxy compound and an alicyclic acid anhydride curing agent are used, the amount of each used is an uncured epoxy compound if there is too little alicyclic acid anhydride curing agent. If the amount is too large, corrosion of the adherend material tends to be accelerated due to the influence of the excess curing agent. Therefore, the alicyclic acid anhydride curing agent is added to 100 parts by mass of the alicyclic epoxy compound. The ratio is preferably 80 to 120 parts by mass, more preferably 95 to 105 parts by mass.

  The anisotropic conductive adhesive having such a configuration is such that the conductive particles are crushed at the time of pressure bonding, and the electrical connection state is maintained, and the diamond particles are captured between the terminals facing each other. Connection reliability can be obtained.

  Moreover, the anisotropic conductive adhesive in this Embodiment can be manufactured by mixing an adhesive composition, electroconductive particle, and a diamond particle uniformly.

<2. Connection structure and manufacturing method thereof>
Next, a connection structure using the above-described anisotropic conductive adhesive will be described. In the connection structure in the present embodiment, the terminal of the first electronic component and the terminal of the second electronic component are electrically connected via the conductive particles, and the terminal of the first electronic component and the second electronic component are connected to each other. Diamond particles are trapped between the terminals of the electronic component.

  As the electronic component in the present embodiment, a chip (element) such as a driver IC (Integrated Circuit) that emits heat or an LED (Light Emitting Diode) is suitable.

  FIG. 1 is a cross-sectional view illustrating a configuration example of an LED mounting body. This LED mounting body uses an anisotropic conductive adhesive in which the above-mentioned conductive particles and diamond particles having an average particle size smaller than the conductive particles are dispersed in an adhesive component for the LED element and the substrate. Connected.

The LED element includes, for example, a first conductive clad layer 12 made of, for example, n-GaN, 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, for example, sapphire, and a second conductivity type cladding layer 14 made of p-GaN, and has a so-called double heterostructure. Further, a first conductivity type electrode 12 a is provided on a part of the first conductivity type cladding layer 12, and a second conductivity type electrode 14 a is provided on a part of the second conductivity type cladding layer 14. When a voltage is applied between the first conductivity type electrode 12a and the second conductivity type electrode 14a of the LED element, carriers are concentrated on the active layer 13 and recombination causes light emission.

  The substrate includes a circuit pattern 22 for the first conductivity type and a circuit pattern 23 for the second conductivity type on the base material 21, and positions corresponding to the first conductivity type electrode 12a and the second conductivity type electrode 14a of the LED element. Each have an electrode 22a and an electrode 23a.

  In the anisotropic conductive adhesive, conductive particles 31 and diamond particles 32 having an average particle size smaller than that of the conductive particles 31 are dispersed in the binder 33 as described above.

  As shown in FIG. 1, the LED mounting body includes a LED element terminal (electrodes 12 a and 14 a) and a board terminal (electrodes 22 a and 23 a) electrically connected via conductive particles 31. The diamond particles 32 are captured between the terminal of the substrate and the terminal of the substrate.

  Thereby, the heat generated in the active layer 13 of the LED element can be efficiently released to the substrate side, the light emission efficiency can be prevented from being lowered, and the life of the LED mounting body can be extended. In addition, since the diamond particles 32 are white or gray achromatic, the light from the active layer 13 is reflected and high luminance can be obtained.

  Further, as shown in FIG. 2, the LED element for flip chip mounting is designed such that the terminals (electrodes 12a, 14a) of the LED element are large due to the passivation 105, so the terminals (electrodes 12a, 14a) of the LED element are designed. ) And the substrate terminals (circuit patterns 22 and 23), more conductive particles 31 and heat conductive particles 32 are captured. Thereby, the heat generated in the active layer 13 of the LED element can be released to the substrate side more efficiently.

  Next, the manufacturing method of the connection structure mentioned above is demonstrated. The manufacturing method of the mounting body in the present embodiment includes the anisotropic conductive adhesive in which the conductive particles described above and diamond particles having an average particle size smaller than the conductive particles are dispersed in the adhesive component. The first electronic component and the second electronic component are thermocompression-bonded between the terminals of the first electronic component and the second electronic component.

  Thereby, the terminal of the first electronic component and the terminal of the second electronic component are electrically connected via the conductive particles, and the terminal of the first electronic component and the terminal of the second electronic component are connected. A connection structure in which diamond particles are trapped therebetween can be obtained.

  In the manufacturing method of the connection structure in the present embodiment, the conductive particles are crushed during thermocompression bonding, and the diamond particles are captured between the opposing terminals, so that high heat dissipation and high connection reliability can be obtained.

<3. Example>
Examples of the present invention will be described in detail below. The present invention is not limited to these examples.

<3.1 Content of Diamond Particles>
In this experiment, an anisotropic conductive adhesive (ACP) was produced, an LED package was produced, and the content of diamond particles was examined. The production of the anisotropic conductive adhesive, the production of the LED mounting body, the evaluation of the heat dissipation of the LED mounting body, the evaluation of the electric characteristics, and the evaluation of the collapse state of the conductive particles were performed as follows.

[Production of anisotropic conductive adhesive]
In an epoxy curing adhesive (epoxy resin (trade name: CEL2021P, manufactured by Daicel Chemical Industries, Ltd.) and acid anhydride (MeHHPA, trade name: MH700, manufactured by Shin Nippon Rika Co., Ltd.)) In addition, 10% by mass of conductive particles (product name: AUL705, manufactured by Sekisui Chemical Co., Ltd.) having an average particle diameter of 5 μm, the surface of which is coated with Au, was blended. Diamond particles were blended with this resin composition to produce an anisotropic conductive adhesive having thermal conductivity.

[Production of LED mounting body]
An LED chip (blue LED, Vf = 3.2 V (If = 20 mA)) was mounted on an Au electrode substrate using an anisotropic conductive adhesive. After an anisotropic conductive adhesive was applied to the Au electrode substrate, the LED chip was aligned and mounted, and thermocompression bonding was performed under the conditions of 200 ° C.-20 seconds-1 kg / chip. As the Au electrode substrate, an Au bump formed by a bump bonder and then flattened was used (glass epoxy substrate, conductor space = 100 μm P, Ni / Au plating = 5.0 / 0.3 μm, gold Bump = 15 μmt).

[Evaluation of heat dissipation]
The thermal resistance value (° C./W) of the LED mounting body was measured using a transient thermal resistance measuring device (manufactured by CATS Electronics Design Co., Ltd.). The measurement conditions were If = 200 mA (constant current control).

[Evaluation of electrical characteristics]
As an initial Vf value, a Vf value at If = 20 mA was measured. Further, the LED mounted body was lit at If = 20 mA for 500 hours in an environment of 85 ° C. and 85% RH (high temperature and high humidity test), and the Vf value at If = 20 mA was measured. The connection reliability was evaluated as x when the rupture of conduction (OPEN) was confirmed, △ when the short (lower than the initial Vf value by 5% or more) was confirmed, and ◯ otherwise.

[Evaluation of crushing state of conductive particles]
The LED chip of the LED mounting body after bonding was peeled off, and the state of the conductive particles captured on the bumps was observed with a metal microscope. By visual inspection, the optimal crushing state (state in which the conductive particles were crushed by about half) was good, and the state in which the conductive particles were not crushed (state in which the crushing state of the conductive particles was less than half) was evaluated as insufficient.

[Example 1]
An anisotropic conductive adhesive was prepared by blending 8% by volume of diamond particles (trade name: IRM, manufactured by Tomei Dia Co., Ltd.) having an average particle diameter (D50) of 2.0 μm as a heat conductive filler, Produced.

  The measurement result of the thermal resistance of this LED mounting body was 173 ° C./W. In addition, the evaluation of the conduction reliability was ○ at the initial stage and ○ after the high temperature and high humidity test. Moreover, evaluation of the crushing state of electroconductive particle was favorable.

[Example 2]
An anisotropic conductive adhesive was prepared by blending 12% by volume of diamond particles (trade name: IRM, manufactured by Tomei Diamond Co., Ltd.) as a heat conductive filler, and an LED package was prepared.

  The measurement result of the thermal resistance of this LED mounting body was 160 ° C./W. In addition, the evaluation of the conduction reliability was ○ at the initial stage and ○ after the high temperature and high humidity test. Moreover, evaluation of the crushing state of electroconductive particle was favorable.

[Example 3]
An anisotropic conductive adhesive was prepared by blending 20% by volume of diamond particles (trade name: IRM, manufactured by Tomei Diamond Co., Ltd.) as a heat conductive filler, and an LED package was prepared.

  The measurement result of the thermal resistance of this LED mounting body was 138 ° C./W. In addition, the evaluation of the conduction reliability was ○ at the initial stage and ○ after the high temperature and high humidity test. Moreover, evaluation of the crushing state of electroconductive particle was favorable.

[Example 4]
An anisotropic conductive adhesive was prepared by blending 50% by volume of diamond particles (trade name: IRM, manufactured by Tomei Diamond Co., Ltd.) as a heat conductive filler, to prepare an LED mounting body.

  The measurement result of the thermal resistance of this LED mounting body was 123 ° C./W. In addition, the evaluation of the conduction reliability was ○ at the initial stage and ○ after the high temperature and high humidity test. Moreover, evaluation of the crushing state of electroconductive particle was favorable.

[Example 5]
An anisotropic conductive adhesive was prepared by blending 60% by volume of diamond particles (trade name: IRM, manufactured by Tomei Diamond Co., Ltd.) as a heat conductive filler, and an LED package was manufactured.

  The measurement result of the thermal resistance of this LED mounting body was 128 ° C./W. In addition, the evaluation of the conduction reliability was ○ in the initial stage and × after the high temperature and high humidity test. Moreover, evaluation of the crushing state of electroconductive particle was inadequate.

[Comparative Example 1]
An anisotropic conductive adhesive was prepared without blending diamond particles, and an LED package was manufactured.

  The measurement result of the thermal resistance of this LED mounting body was 200 ° C./W. In addition, the evaluation of the conduction reliability was ○ at the initial stage and ○ after the high temperature and high humidity test. Moreover, evaluation of the crushing state of electroconductive particle was favorable.

[Comparative Example 2]
An anisotropic conductive adhesive was prepared by blending 20% by volume of diamond particles (trade name: IRM, manufactured by Tomei Diamond Co., Ltd.) having an average particle diameter (D50) of 20 μm as a heat conductive filler to obtain an LED mounting body. .

  The thermal resistance of this LED mounting body could not be measured because fracture was confirmed in the initial conduction reliability evaluation. In addition, the evaluation of conduction reliability was Δ in the initial stage and x after the high-temperature and high-humidity test. Moreover, evaluation of the crushing state of electroconductive particle was inadequate.

  Tables 1 and 2 show the evaluation results of Examples 1 to 5 and Comparative Examples 1 and 2.

  When ACP not added with diamond particles was used as in Comparative Example 1, the LED mounted body had a thermal resistance value of 200 (° C./W). In the lighting storage test of this LED mounting sample in an environment of 85 ° C. and 85% RH, the electrical connection reliability was good in the test 500 h. Further, the degree of collapse of the conductive particles was optimal.

  As in Example 1, the LED package using ACP added with 8% by volume of diamond particles (2 μm) with respect to the binder has a thermal resistance value of 173 (° C./W), which is higher than that of Comparative Example 1. The resistance value could be lowered, and the heat dissipation characteristics of the LED package could be improved. Further, in the lighting storage test in which the LED mounting sample was lit for 500 hours in an 85 ° C. and 85% RH environment, the connection reliability was favorable. Moreover, the degree of collapse of the conductive particles was also optimal.

  As in Example 2, the LED package using ACP added with 12% by volume of diamond particles (2 μm) with respect to the binder has a heat resistance value of 160 (° C./W), which is higher than that of Comparative Example 1. The resistance value could be lowered, and the heat dissipation characteristics of the LED package could be improved. Further, in the lighting storage test in which the LED mounting body was lit for 500 hours in an environment of 85 ° C. and 85% RH, the connection reliability was favorable. Moreover, the degree of collapse of the conductive particles was also optimal.

  As in Example 3, the LED mounted body using ACP in which 20% by volume of diamond particles (2 μm) are added to the binder has a thermal resistance value of 138 (° C./W), which is higher than that of Comparative Example 1. The resistance value could be lowered, and the heat dissipation characteristics of the LED package could be improved. Further, in the lighting storage test in which the LED mounting body was lit for 500 hours in an environment of 85 ° C. and 85% RH, the connection reliability was favorable. Moreover, the degree of collapse of the conductive particles was also optimal.

  As in Example 4, the LED mounting body using ACP in which 50% by volume of diamond particles (2 μm) is added to the binder has a thermal resistance value of 123 (° C./W), which is higher than that of Comparative Example 1. The resistance value could be lowered, and the heat dissipation characteristics of the LED package could be improved. Further, in the lighting storage test in which the LED mounting body was lit for 500 hours in an environment of 85 ° C. and 85% RH, the connection reliability was favorable. Moreover, the degree of collapse of the conductive particles was also optimal.

  As in Example 5, the LED mounted body using ACP in which 60% by volume of diamond particles (2 μm) are added to the binder has a thermal resistance value of 128 (° C./W), which is higher than that of Comparative Example 1. The resistance value could be lowered, and the heat dissipation characteristics of the LED package could be improved. However, in the lighting storage test in which the LED mounting body was lit for 500 hours in an environment of 85 ° C. and 85% RH, a decrease of 5% or more from the initial Vf value was observed. Further, when the degree of crushing of the conductive particles was confirmed, an excessive amount of diamond particles served as a spacer on the bump, and the degree of crushing of the conductive particles was insufficient.

  As in Comparative Example 2, the LED mounted body using ACP in which 20% by volume of diamond particles (20 μm) was added to the binder confirmed the conduction breakage by the measurement of the initial Vf value. Further, when the degree of crushing of the conductive particles was confirmed, the diamond particles having a large particle diameter acted as a spacer on the bump, and the conductive particles were not crushed satisfactorily. In addition, large particles bite into the chip, causing chip breakage of the LED elements.

  As described above, by adding diamond particles to the anisotropic conductive adhesive, the thermal resistance value of the LED package can be lowered, and the heat generated from the LED element can be efficiently radiated to the substrate side. . Moreover, high connection reliability could be obtained by blending diamond particles in an amount of 8 to 50% by volume with respect to the anisotropic conductive adhesive.

<3.2 Thermally conductive particles other than diamond particles>
In this experiment, an anisotropic conductive adhesive (ACP) using thermally conductive particles other than diamond particles was produced to produce an LED package. The production of the anisotropic conductive adhesive, the production of the LED mounting body, the evaluation of the electrical characteristics, and the evaluation of the state of crushing of the conductive particles were performed in the same manner as in <3.1 Compounding amount of diamond particles> described above. The measurement of the thermal conductivity of the cured product was performed as follows.

<Measurement of thermal conductivity of ACP cured product>
An anisotropic conductive adhesive was sandwiched between glass plates and cured at 150 ° C. for 1 hour to obtain a cured product having a thickness of 1 mmt. And the thermal conductivity of the hardened | cured material was measured using the measuring apparatus (Xenon flash analyzer LFA447, the product made from NETZSCH) by the laser flash method.

[Comparative Example 3]
As heat conductive filler, alumina particles having an average particle diameter (D50) of 0.7 μm (appearance: transparent / white, refractive index: 1.76, electrical resistivity: 1 × 10 ¹⁵ Ω · cm, thermal conductivity: 38 W / An anisotropic conductive adhesive was prepared by blending 23% by volume of (m · K) to prepare an LED mounting body.

  The thermal conductivity of the ACP cured product was 0.54 W / (m · K), and the thermal resistance of the LED mounted body was 181 ° C./W. In addition, the evaluation of the conduction reliability was ○ at the initial stage and ○ after the high temperature and high humidity test. Moreover, evaluation of the crushing state of electroconductive particle was favorable.

[Comparative Example 4]
20% by volume of aluminum nitride particles having an average particle diameter (D50) of 1.1 μm (appearance: gray, electrical resistivity: 0.1 × 10 ¹⁵ Ω · cm, thermal conductivity: 200 W / (m · K)) Then, an anisotropic conductive adhesive was produced, and an LED mounting body was produced.

  The thermal conductivity of the ACP cured product was 0.58 W / (m · K), and the thermal resistance of the LED mounted body was 170 ° C./W. In addition, the evaluation of the conduction reliability was ○ at the initial stage and ○ after the high temperature and high humidity test. Moreover, evaluation of the crushing state of electroconductive particle was favorable.

[Comparative Example 5]
12 silver particles having an average particle diameter (D50) of 1.5 μm (appearance: silver luster / gray, electrical resistivity: 1.6 × 10 ⁻⁶ Ω · cm, thermal conductivity: 420 W / (m · K)) An anisotropic conductive adhesive was prepared by blending by volume% to prepare an LED mounting body.

  The thermal conductivity of the ACP cured product was 0.37 W / (m · K), and the thermal resistance of the LED mounted body was 133 ° C./W. In addition, the evaluation of conduction reliability was ◯ at the initial stage and △ after the high temperature and high humidity test. Moreover, evaluation of the crushing state of electroconductive particle was favorable.

  In Table 3, the evaluation result of Example 3 and Comparative Examples 3-5 is shown.

  As in Comparative Example 3, the LED mounting body using ACP in which 23% of alumina particles are added to the binder has a thermal resistance value of 181 ° C./W, and has a similar thermal conductive filler content. The heat resistance was higher than that, and high heat dissipation characteristics could not be obtained.

  As in Comparative Example 4, the LED mounted body using ACP in which 20% of aluminum nitride particles are added to the binder has a thermal resistance value of 170 ° C./W, and has the same heat conductive filler content. Thermal resistance was higher than 3, and high heat dissipation characteristics could not be obtained.

  As in Comparative Example 5, the LED mounting body using ACP in which aluminum nitride particles are added to the binder at 12% has a thermal resistance value of 133 ° C./W, and has the same heat conductive filler content. High heat dissipation characteristics equivalent to 3 were obtained. However, in the lighting storage test in which the LED mounting body was lit for 500 hours in an environment of 85 ° C. and 85% RH, a decrease of 5% or more from the initial Vf value was observed.

  DESCRIPTION OF SYMBOLS 11 Element substrate, 12 1st conductivity type clad layer, 13 Active layer, 14 2nd conductivity type clad layer, 15 Passivation, 21 Base material, 22 Circuit pattern for 1st conductivity type, 23 Circuit pattern for 2nd conductivity type, 31 Conductive particles, 32 diamond particles, 33 binder, 101 element substrate, 102 first conductivity type cladding layer, 103 active layer, 104 second conductivity type cladding layer, 105 passivation, 201 base material, 202 circuit pattern for first conductivity type , 203 second conductive type circuit pattern, 301 wire bond, 302 die bond material, 303 conductive paste, 304 sealing resin, 305 binder, 306 conductive particles, 307 gold-tin alloy

Claims (7)

  An anisotropic conductive adhesive comprising conductive particles and diamond particles having an average particle size smaller than that of the conductive particles dispersed in a binder.   The anisotropic conductive adhesive according to claim 1, wherein the content of the diamond particles is 8 to 50% by volume.   The anisotropic conductive adhesive according to claim 1 or 2, wherein the diamond particles have a white or gray achromatic color.   The anisotropic conductive adhesive according to any one of claims 1 to 3, wherein the thermal resistance value is less than 200 ° C / W.   The terminal of the first electronic component and the terminal of the second electronic component are electrically connected via conductive particles, and diamond is provided between the terminal of the first electronic component and the terminal of the second electronic component. A connection structure in which particles are captured. The first electronic component is an LED element;
The connection structure according to claim 5, wherein the second electronic component is a substrate.   The connection structure according to claim 6, wherein the diamond particles have a white or gray achromatic color.

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