JP2015221875A - Adhesive and connection structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an adhesive having excellent adhesivity to a heat-releasing electronic component and a heat-releasing property, and a connection structure using the same.SOLUTION: The adhesive comprises an epoxy compound, a cationic catalyst, and an acrylic resin containing acrylic acid and an acrylic acid ester having a hydroxyl group. The acrylic acid in the acrylic resin reacts with the epoxy compound and generates a link between an island 13 of the acrylic resin and a sea 12 of the epoxy compound, and roughens a surface of an oxide film 11a to increase an anchor effect with the sea 12 of the epoxy compound. Moreover, by melting a solder particle 1 contained, the solder forms a metal bond between the electrode 10, resulting in improvement of adhesion between the adhesive and the electrode 10, and further improvement of heat releasing characteristics from a metal bond surface.

Description

  The present invention relates to an adhesive for electrically connecting electronic components to each other, and more particularly, an adhesive that connects an electronic component that generates heat and a wiring board and dissipates heat from the electronic component, and the electronic component and the wiring board are connected. Connection structure.

  As a method of mounting chip parts such as LEDs on a circuit board, flip-chip mounting using an anisotropic conductive film (ACF) formed by dispersing conductive particles in an epoxy adhesive and forming it into a film shape Are widely adopted (see, for example, Patent Documents 1 and 2). According to this method, since the electrical connection between the chip component and the circuit board is achieved by the conductive particles of the anisotropic conductive film, the connection process can be shortened and the production efficiency can be improved. Can do.

JP 2010-24301 A JP 2012-186322 A

  Some LED products in recent years have changed the wiring of the circuit board from Au, Ag to Al, Cu for cost reduction, and ITO (Indium Tin Oxide) on PET (Polyethylene terephthalate) base material. Some use a transparent substrate on which wiring is formed.

  However, since metal oxides such as Al and Cu and ITO wirings have oxides such as passivation and oxide films, it is difficult to bond with conventional epoxy adhesives.

  In addition, it is difficult to bond, and in order to sufficiently dissipate heat from the electronic parts that generate heat, such as LED products, the heat dissipation material must be included in the adhesive, and the adhesive can be increased by including the heat dissipation material. It was difficult to maintain sufficient adhesive strength due to less ingredients.

  Moreover, when the inorganic filler and metal filler used as a heat dissipation material are contained in the adhesive, these serve as spacers, and the adhesive layer cannot be thinned.

  The present invention solves the above-described problems in the prior art, and uses an adhesive having excellent adhesion to an oxide film and excellent heat dissipation from an electronic component that dissipates heat to the outside. An object is to provide a connection structure.

  In order to solve the above-described problems, an adhesive according to the present invention is an adhesive that bonds an electronic component that generates heat and a substrate having a wiring pattern, and is made of a resin binder containing solder particles. .

  The connection structure according to the present invention includes a substrate having a wiring pattern, an anisotropic conductive film formed on the electrode of the wiring pattern, and an electronic component that generates heat mounted on the anisotropic conductive film. And the anisotropic conductive film contains a resin binder and solder particles, and the solder particles and terminal portions of the electronic component are metal-bonded.

  According to the present invention, the solder particles in the resin binder are metal-bonded to the terminal portion of the electronic component, thereby obtaining an excellent adhesive force between the adhesive layer and the electronic component, and the heat generated in the electronic component. Can be diffused into the metal-bonded solder particles to dissipate heat more efficiently.

It is sectional drawing which shows a sea-island model when an epoxy compound is made into the sea and an acrylic resin is made into an island. It is sectional drawing explaining a solder particle. It is sectional drawing which shows an example of a light-emitting device. It is sectional drawing which shows the outline | summary of a 90 degree peel strength test. It is a figure for demonstrating the preparation process of a LED mounting sample. It is sectional drawing which shows the outline | summary of a die shear strength test. It is a figure explaining the case where diamond particles are used as a heat dissipation material. It is a figure explaining the case where copper powder is used as a heat dissipation material. It is a figure explaining the case where aluminum nitride powder is used as a heat dissipation material. It is a figure explaining the heat dissipation characteristic of a resin binder.

Hereinafter, embodiments of the present invention (hereinafter referred to as the present embodiment) will be described in detail in the following order with reference to the drawings. It should be noted that the present invention is not limited to the following embodiments, and various modifications can be made without departing from the scope of the present invention. Further, the drawings are schematic, and the ratio of each dimension may be different from the actual one. Specific dimensions should be determined in consideration of the following description. Moreover, it is a matter of course that portions having different dimensional relationships and ratios are included between the drawings.
1. 1. Adhesive 2. Connection structure Example

<1. Adhesive>
The adhesive to which the present invention is applied contains an alicyclic epoxy compound or a hydrogenated epoxy compound, a cationic catalyst, an acrylic resin having a weight average molecular weight of 50,000 to 900,000, and solder particles, and the acrylic resin is 0 .5-10 wt% acrylic acid and 0.5-10 wt% acrylic acid ester having a hydroxyl group.

  FIG. 1 is a cross-sectional view showing a sea-island model when the epoxy compound is the sea and the acrylic resin is the island at the interface between the adhesive and the oxide film. This sea-island model is a cured product model in which an acrylic resin island 13 dispersed in an epoxy compound sea 12 is in contact with the oxide film 11 a of the wiring 11.

  In this cured product model, acrylic acid in the acrylic resin reacts with the epoxy compound to cause a connection between the acrylic resin island 13 and the sea 12 of the epoxy compound, and also roughens the surface of the oxide film 11a to form the epoxy compound. Strengthen the anchor effect with the sea 12. Further, the acrylic ester having a hydroxyl group in the acrylic resin obtains an electrostatic adhesive force to the wiring 11 due to the polarity of the hydroxyl group. Thus, by adhering to the oxide film 11a with the entire cured product of the acrylic resin island 13 and the epoxy compound sea 12, excellent adhesion can be obtained.

  Next, solder particles will be described. Specifically, the adhesive will be described using an example in which the LED element is bonded to an aluminum wiring board having a wiring pattern whose surface is an oxide. FIG. 2 is a cross-sectional view for explaining the function of solder particles contained in the adhesive.

  As shown in FIG. 2, the solder particles 1 are added to the resin binder 3 having the above-described configuration together with conductive particles 2 described later. The solder particles 1 are dispersed and arranged between the electrode 10 of the LED element and the wiring 11 of the aluminum wiring board together with the conductive particles 2, and are melted in the pressure bonding step to become the molten solder 1a.

  Here, the electrode 10 of the LED element is made of Au or Au-Sn. When the solder particles 1 are heated to a melting point or higher, they melt, and when they are cooled to a freezing point or lower, they solidify in a substantially columnar shape, and one end face 1b is metal-bonded to the electrode 10. On the other hand, the solder particles 1 cannot be metal-bonded to the wiring 11. This is because an oxide film 11a made of aluminum oxide is present on the wiring 11, and in a general crimping process, the molten solder 1a and the wiring 11 of the aluminum wiring board cannot be metal-bonded. Therefore, the molten solder 1 a does not contribute to electrical conduction between the electrode 10 of the LED element and the wiring 11.

  However, since the molten solder 1a has a metal bond with the electrode 10 at the end face 1b, the electrode 10 and the molten solder 1a form one structure. As a result, the adhesive force increases between the LED element and the adhesive. Specifically, when the molten particle 1a is not present, the electrode 10 of the LED element and the adhesive are only in contact with each other on a two-dimensional surface, but the structure formed by the electrode 10 of the LED element and the molten solder 1a is 3 Since it has a dimensional structure, as a result, an adhesion area increases between the electrode 10 and the adhesive. That is, since the molten solder 1a is metal-bonded with a part of the electrode 10 and functions as a pile (anchor) with respect to the adhesive, the adhesive strength between the electrode 10 and the adhesive can be improved.

  Further, since the molten solder 1a is metal-bonded to the electrode 10, it is not a point contact like other particles used as a heat dissipation material, but a surface contact, and heat is radiated from the LED element side via the molten solder 1a. This can dramatically improve the heat dissipation characteristics. Further, the contact surface with the wiring 11 is also in contact with the surface through the oxide film 11a, so that heat can be easily transferred, and in this respect, the heat dissipation characteristics can be improved. In addition, the comparison with another heat dissipation material is demonstrated in detail also in a comparative example.

  The solder particles 1 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. , Sn—Pb—Cu, Sn—In, Sn—Ag, Sn—Pb—Ag, Pb—Ag, and the like can be appropriately selected according to the electrode material, connection conditions, and the like. Further, the shape of the solder particles 1 can be appropriately selected from granular, flake shaped, and the like.

  The average particle diameter (D50) of the solder particles 1 is preferably 3 μm or more and less than 30 μm, and the addition amount of the solder particles 1 is preferably 50 parts by mass or more and less than 150 parts by mass. If the addition amount is too small, the anchor effect as described above cannot be expected, and if the addition amount is too large, the resin binder 3 is relatively reduced, and the adhesive strength as an adhesive is reduced. is there.

  Moreover, it is preferable to use the solder particles 1 having a melting point equal to or lower than the mounting temperature. When the solder particles 1 having such a melting point are used, the solder particles 1 can be melted by heating in the mounting (crimping process), so that it is not necessary to add a heating process only for melting the solder particles 1. That is, the adhesive can be cured and the solder particles 1a can be melted. Moreover, it is because an excessive heating stress is not given to an LED element or a board | substrate in order to form the molten solder 1a. For example, when the LED element is bonded to a resin substrate using aluminum wiring, the LED element is mounted at 180 ° C. in consideration of the heat resistance of the resin substrate. In this case, the temperature is preferably 180 ° C. or less.

  Next, as an alicyclic epoxy compound, what has two or more epoxy groups in a molecule | numerator is mentioned preferably. These may be liquid or solid. Specific examples include 3,4-epoxycyclohexenylmethyl-3 ′, 4′-epoxycyclohexene carboxylate and glycidyl hexahydrobisphenol A. Among these, 3,4-epoxycyclohexenylmethyl-3 ′, 4′-epoxycyclohexene is preferred because it can ensure light transmission suitable for mounting LED elements on the cured product and is excellent in rapid curing. Carboxylates are preferably used.

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

  Although an alicyclic 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 G, glycidyl ether obtained by reacting polychlorophenol such as A, tetramethylbisphenol F, tris (hydroxyphenyl) methane, bixylenol, phenol novolak, cresol novolak and epichlorohydrin; glycerin, neopentyl glycol, ethylene glycol, propylene glycol , Tylene glycol, hexylene glycol, polyethylene Polyglycidyl ether obtained by reacting aliphatic polyhydric alcohols such as polyglycol and polypropylene glycol with epichlorohydrin; obtained by reacting hydroxycarboxylic acid such as p-oxybenzoic acid and β-oxynaphthoic acid with epichlorohydrin Glycidyl ether esters obtained from phthalic acid, methylphthalic acid, isophthalic acid, terephthalic acid, tetrahydrophthalic acid, endomethylenetetrahydrophthalic acid, endomethylenehexahydrophthalic acid, trimellitic acid, polycarboxylic acids such as polymerized fatty acids Polyglycidyl ester obtained; glycidyl aminoglycidyl ether obtained from aminophenol and aminoalkylphenol; glycidyl aminoglycidyl ester obtained from aminobenzoic acid; Glycidylamine obtained from niline, toluidine, tribromoaniline, xylylenediamine, diaminocyclohexane, bisaminomethylcyclohexane, 4,4'-diaminodiphenylmethane, 4,4'-diaminodiphenylsulfone, etc .; known epoxidized polyolefin, etc. Examples include epoxy resins.

  Examples of the cationic catalyst include latent cationic curing agents such as an aluminum chelate-based latent curing agent, an imidazole-based latent curing agent, and a sulfonium-based latent curing agent. Among these, an aluminum chelate-based latent curing agent that is excellent in rapid curability is preferably used.

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

  The acrylic resin has a weight average molecular weight of 50,000 to 900,000. In the cured product model shown in FIG. 1, the weight average molecular weight of the acrylic resin shows a correlation with the size of the acrylic resin island 13, and the weight average molecular weight of the acrylic resin is 50,000 to 900,000. The acrylic resin island 13 can be brought into contact with the oxide film 11a. When the weight average molecular weight of the acrylic resin is less than 50,000, the contact area between the acrylic resin island 13 and the oxide film 11a becomes small, and the effect of improving the adhesive strength cannot be obtained. Further, when the weight average molecular weight of the acrylic resin is more than 900,000, the acrylic resin island 13 becomes large and is adhered to the oxide film 11a with the entire cured product of the acrylic resin island 13 and the epoxy compound sea 12. However, the adhesive strength is reduced.

  Moreover, an acrylic resin contains 0.5-10 wt% of acrylic acid, More preferably, it contains 1-5 wt%. When the acrylic resin is contained in the acrylic resin in an amount of 0.5 to 10 wt%, the reaction with the epoxy compound causes the connection between the acrylic resin island 13 and the epoxy compound sea 12, and the surface of the oxide film 11 a is roughened. The anchor effect of the epoxy compound with the sea 12 is strengthened.

  Moreover, an acrylic resin contains 0.5-10 wt% of acrylic acid ester which has a hydroxyl group, More preferably, it contains 1-5 wt%. When 0.5 to 10 wt% of an acrylic ester having a hydroxyl group is contained in the acrylic resin, an electrostatic adhesive force to the wiring 11 can be obtained 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 having excellent adhesion to an oxide film is preferably used.

  Moreover, an acrylic resin contains the acrylic acid ester which does not have a hydroxyl group other than acrylic acid ester which has acrylic acid and a hydroxyl group. Examples of the acrylate ester having no hydroxy group include butyl acrylate, ethyl acrylate, and acrylonitrile.

  Moreover, it is preferable that it is 1-10 mass parts with respect to 100 mass parts of epoxy compounds, and, as for content of an acrylic resin, it is more preferable that it is 1-5 mass parts. 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 12 are dispersed at a good density in the sea of the epoxy resin 13 It becomes.

  Moreover, in order to improve the adhesiveness in the interface with an inorganic material, the adhesive agent to which this invention was applied may further contain a silane coupling agent as another component. Examples of the silane coupling agent include epoxy-based, methacryloxy-based, amino-based, vinyl-based, mercapto-sulfide-based, ureido-based, and the like. These may be used alone or in combination of two or more. Also good. Among these, in this Embodiment, an epoxy-type silane coupling agent is used preferably.

  The adhesive may contain an inorganic filler in order to control fluidity and improve the particle capture rate. The inorganic filler is not particularly limited, and silica, talc, titanium oxide, calcium carbonate, magnesium oxide and the like can be used. Such an inorganic filler can be appropriately used depending on the purpose of relaxing the stress of the connection structure connected by the adhesive. Moreover, you may mix | blend softeners, such as a thermoplastic resin and a rubber component.

  According to such an adhesive, a high adhesive force can be obtained for a difficult-to-bond metal such as aluminum.

  The adhesive may be an anisotropic conductive adhesive containing conductive particles. Known conductive particles can be used as the conductive particles. For example, on the surface of particles of various metals and metal alloys such as nickel, iron, copper, aluminum, tin, lead, chromium, cobalt, silver and gold, particles of metal oxide, carbon, graphite, glass, ceramic, plastic, etc. The thing which coated the metal, the thing which coat | covered the insulating thin film further on the surface of these particle | grains, etc. are mentioned. In the case where the surface of the resin particle is coated with metal, examples of the resin particle include an epoxy resin, a phenol resin, an acrylic resin, an acrylonitrile / styrene (AS) resin, a benzoguanamine resin, a divinylbenzene resin, a styrene resin, and the like. The particles can be used.

As an average particle diameter of electroconductive particle, it is 1-10 micrometers normally, More preferably, it is 2-6 micrometers. The average particle density of the conductive particles in the adhesive component is preferably 1000 to 100,000 / mm ² , more preferably 30,000 to 80,000 / mm ² from the viewpoint of connection reliability and insulation reliability. Here, it is preferable that content of electroconductive particle shall be 1-20 mass parts.

  According to such an anisotropic conductive adhesive, excellent connection reliability can be obtained for aluminum wiring and ITO wiring having an oxide film.

<2. Connection structure>
Next, a connection structure to which the present invention is applied will be described. FIG. 3 is a cross-sectional view showing an LED element, which is an electronic component that generates heat, as an example of a connection structure. The connection structure includes a substrate 21 having a wiring pattern 22, an anisotropic conductive film 30 formed on the electrode of the wiring pattern 22, and a light emitting element 23 mounted on the anisotropic conductive film 30. The anisotropic conductive film 30 is made of a cured product of the aforementioned anisotropic conductive adhesive. This light-emitting device has the above-described anisotropy between the wiring pattern 22 on the substrate 21 and the connection bumps 26 formed on the n-electrode 24 and the p-electrode 25 of the LED element as the light-emitting element 23. It is obtained by applying a conductive adhesive and flip-chip mounting the substrate 21 and the light emitting element 23.

  The bumps 26 described here are made of Au or Au—Sn alloy plated. Accordingly, the bump 26 corresponds to the electrode 10 described in FIG. 2, and the solder particles 1 b are metal-bonded with the bump 26.

  In this embodiment, a substrate having a wiring pattern made of aluminum can be suitably used by using the anisotropic conductive adhesive described above. Thereby, cost reduction of LED products can be achieved.

  Moreover, the transparent substrate which has a wiring pattern which consists of transparent conductive films, such as ITO, can be used suitably. Thereby, for example, an LED element can be mounted on a transparent resin substrate in which ITO (Indium Tin Oxide) wiring is formed on a PET (Polyethylene terephthalate) base material.

In addition, you may seal with transparent mold resin with a sufficient heat dissipation characteristic so that the whole LED element 23 may be covered as needed. Further, the LED element 23 may be provided with a light reflecting layer. Moreover, as a light emitting element, the well-known electronic component which heat | fever-generates can be used in the range which does not impair the effect of this invention other than an LED element.
<3. Example>

  Examples of the present invention will be described below. In this example, various anisotropic conductive adhesives were prepared, LED elements were mounted on a substrate using these anisotropic conductive adhesives to prepare LED mounting samples, and terminal portions of the LED elements and solder The presence or absence of alloy formation of the particles, the thermal resistance value, and the adhesive strength to aluminum were evaluated. The present invention is not limited to these examples.

[Measurement of peel strength]
An anisotropic conductive adhesive was applied on a white plate made of ceramic so as to have a thickness of 100 μm, and an aluminum piece of 1.5 mm × 10 mm was thermocompression bonded under the condition of 180 ° C.-1.5 N-30 sec. Was made.

  As shown in FIG. 4, using Tensilon, the aluminum piece of the joined body was peeled off in the 90 ° Y-axis direction at a pulling speed of 50 mm / sec, and the maximum peel strength required for the peeling was measured.

[Production of LED mounting sample]
As shown in FIG. 5, an LED mounting sample was produced. A plurality of 50 μm pitch wiring boards (50 μm Al wiring—25 μm PI (polyimide) layer—50 μm Al base) 51 were arranged on the stage, and about 10 μg of anisotropic conductive adhesive 50 was applied on each wiring board 51. An LED chip manufactured by Cree (trade name: DA3547, maximum rating: 150 mA, size: 0.35 mm × 0.46 mm) 52 is mounted on the anisotropic conductive adhesive 50 and flipped using a heat pressing tool 53. Chip mounting was performed to obtain an LED mounting sample.

[Die shear strength measurement]
As shown in FIG. 6, using a die shear tester, the bonding strength of each LED mounting sample was measured under the conditions of a shear rate of the tool 54 of 20 μm / sec and 25 ° C.

[Evaluation of presence or absence of alloy formation]
The appearance of each LED mounting sample was confirmed by using a microscope (SEM: Scanning Electron Microscope) or the like to determine whether an alloy was formed between the electrode portion of the LED element and the solder particles. Specifically, when an alloy is formed, surface contact is made between the electrode portion and the solder particles by molten solder. For this reason, it is possible to determine whether or not an alloy is formed, that is, whether or not metal bonding is performed, by observing the spread area of the molten solder.

[Evaluation of thermal resistance]
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).

[Comprehensive evaluation]
Whether the terminal part of the LED element and the solder particles are alloyed or not, the thermal resistance value is all “◯”, the peel strength is 2.0 N or more, and the die shear strength is 5.0 N or more is evaluated as “OK”. The others were evaluated as “NG”.

[Example 1]
100 parts by mass of an alicyclic epoxy compound (product name: Celoxide 2021P, manufactured by Daicel Chemical Industries), 5 parts by mass of a latent cationic curing agent (aluminum chelate-based latent curing agent), acrylic resin (butyl acrylate (BA): 15%) , Ethyl acrylate (EA): 63%, acrylonitrile (AN): 20%, acrylic acid (AA): 1 w%, 2-hydroxyethyl methacrylate (HEMA): 1 wt%, weight average molecular weight Mw: 700,000 ) In an adhesive composed of 3 parts by mass, 30 parts by mass of solder particles having a solder melting point of 150 ° C. and 10 parts by mass of conductive particles (product name: AUL704, manufactured by Sekisui Chemical Co., Ltd.) are dispersed to conduct anisotropic conductive adhesion. An agent was prepared. Moreover, the hardening conditions in preparation of a LED mounting sample were 180 degreeC-1.5N-30sec.

  In addition, the average particle diameter of the solder particles was 5 μm, 7 μm, 10 μm, 12 μm, or 25 μm for each example. Since no significant difference was found in the particle size in the above range, the test results for each particle size are omitted, but the results of the examples of the present application can be obtained by using at least the particle size in the above range. The same applies to the following examples and comparative examples containing solder particles.

  Table 1 shows the evaluation results of Example 1. Alloy formation was confirmed, the thermal resistance value was 17 (K / W), and the peel strength was 4.0 N. Moreover, the die shear strength of the LED mounting sample was 8.5N. Therefore, the overall evaluation was OK.

[Example 2]
An anisotropic conductive adhesive was produced in the same manner as in Example 1 except that the melting point of the solder particles was 150 ° C. and the blending was 40 parts by mass.

  Table 1 shows the evaluation results of Example 2. Formation of an alloy was confirmed, the thermal resistance value was 16 (K / W), and the peel strength was 4.0 N. Moreover, the die shear strength of the LED mounting sample was 8.5N. Therefore, the overall evaluation was OK.

[Example 3]
An anisotropic conductive adhesive was produced in the same manner as in Example 1 except that the melting point of the solder particles was 150 ° C. and the blending was 60 parts by mass.

  Table 1 shows the evaluation results of Example 3. Formation of an alloy was confirmed, the thermal resistance value was 16 (K / W), and the peel strength was 4.0 N. Moreover, the die shear strength of the LED mounting sample was 8.5N. Therefore, the overall evaluation was OK.

[Example 4]
An anisotropic conductive adhesive was produced in the same manner as in Example 1 except that the melting point of the solder particles was 150 ° C. and the blending was 80 parts by mass.

  Table 1 shows the evaluation results of Example 4. Alloy formation was confirmed, the thermal resistance value was 15 (K / W), and the peel strength was 4.0 N. Moreover, the die shear strength of the LED mounting sample was 8.5N. Therefore, the overall evaluation was OK.

[Example 5]
An anisotropic conductive adhesive was produced in the same manner as in Example 1 except that the melting point of the solder particles was 170 ° C. and the blending was 30 parts by mass.

  Table 1 shows the evaluation results of Example 5. Formation of an alloy was confirmed, the thermal resistance value was 16 (K / W), and the peel strength was 4.0 N. Moreover, the die shear strength of the LED mounting sample was 8.5N. Therefore, the overall evaluation was OK.

[Example 6]
An anisotropic conductive adhesive was produced in the same manner as in Example 1 except that the melting point of the solder particles was 170 ° C. and the blending was 80 parts by mass.

  Table 1 shows the evaluation results of Example 6. Formation of an alloy was confirmed, the thermal resistance value was 16 (K / W), and the peel strength was 4.0 N. Moreover, the die shear strength of the LED mounting sample was 8.5N. Therefore, the overall evaluation was OK.

[Comparative Example 1]
An anisotropic conductive adhesive was produced in the same manner as in Example 1 except that no solder particles were blended.

  Table 1 shows the evaluation results of Comparative Example 1. Alloy formation could not be confirmed, the thermal resistance value was 29 (K / W), and the peel strength was 4.0 N. Moreover, the die shear strength of the LED mounting sample was 8.5N. Therefore, the overall evaluation was NG.

[Comparative Example 2]
An anisotropic conductive adhesive was produced in the same manner as in Example 1 except that the melting point of the solder particles was 150 ° C. and the composition was 160 parts by mass.

  Table 1 shows the evaluation results of Comparative Example 2. Formation of an alloy was confirmed, the thermal resistance value was 16 (K / W), and the peel strength was 1.2N. Moreover, the die shear strength of the LED mounting sample was 2.0N. Therefore, the overall evaluation was NG.

[Comparative Example 3]
An anisotropic conductive adhesive was produced in the same manner as in Example 1 except that the melting point of the solder particles was 170 ° C. and the blending was 160 parts by mass.

  Table 1 shows the evaluation results of Comparative Example 3. Formation of an alloy was confirmed, the thermal resistance value was 16 (K / W), and the peel strength was 1.2N. Moreover, the die shear strength of the LED mounting sample was 2.0N4. Therefore, the overall evaluation was NG.

[Comparative Example 4]
An anisotropic conductive adhesive was produced in the same manner as in Example 1 except that the melting point of the solder particles was 200 ° C. and the blending was 30 parts by mass.

  Table 1 shows the evaluation results of Comparative Example 4. Alloy formation could not be confirmed, the thermal resistance value was 26 (K / W), and the peel strength was 4.0 N. Moreover, the die shear strength of the LED mounting sample was 8.5N. Therefore, the overall evaluation was NG.

[Comparative Example 5]
An anisotropic conductive adhesive was produced in the same manner as in Example 1 except that the melting point of the solder particles was 200 ° C. and the blending was 80 parts by mass.

  Table 1 shows the evaluation results of Comparative Example 5. Alloy formation could not be confirmed, the thermal resistance value was 23 (K / W), and the peel strength was 4.0 N. Moreover, the die shear strength of the LED mounting sample was 8.5N. Therefore, the overall evaluation was NG.

[Comparative Example 6]
An anisotropic conductive adhesive was produced in the same manner as in Example 1 except that the melting point of the solder particles was 200 ° C. and the blending was 160 parts by mass.

  Table 1 shows the evaluation results of Comparative Example 6. Alloy formation could not be confirmed, the thermal resistance value was 23 (K / W), and the peel strength was 1.2N. Moreover, the die shear strength of the LED mounting sample was 2.0N. Therefore, the overall evaluation was NG.

[Comparative Example 7]
An anisotropic conductive adhesive was produced in the same manner as in Example 1 except that 60 parts by mass of alumina powder having an average particle size of 0.4 μm, which is a heat dissipation material, was blended in the resin binder instead of the solder particles.

  Table 2 shows the evaluation results of Comparative Example 7. Alloy formation could not be confirmed, and the thermal resistance value was 25 (K / W). Moreover, the die shear strength of the LED mounting sample was 8.5N. Therefore, the overall evaluation was NG.

[Comparative Example 8]
An anisotropic conductive adhesive was produced in the same manner as in Example 1 except that 150 parts by mass of alumina powder having an average particle diameter of 0.4 μm, which is a heat dissipation material, was blended in the resin binder instead of the solder particles.

  Table 2 shows the evaluation results of Comparative Example 8. Alloy formation could not be confirmed, and the thermal resistance value was 23 (K / W). Moreover, the die shear strength of the LED mounting sample was 5.3N. Therefore, the overall evaluation was NG.

[Comparative Example 9]
An anisotropic conductive adhesive was produced in the same manner as in Example 1 except that 60 parts by mass of alumina powder having an average particle diameter of 3 μm, which is a heat dissipation material, was blended in the resin binder instead of the solder particles.

  Table 2 shows the evaluation results of Comparative Example 9. Alloy formation could not be confirmed, and the thermal resistance value was 29 (K / W). Moreover, the die shear strength of the LED mounting sample was 8.8N. Therefore, the overall evaluation was NG.

[Comparative Example 10]
An anisotropic conductive adhesive was produced in the same manner as in Example 1 except that 150 parts by mass of alumina powder having an average particle size of 3 μm, which is a heat dissipation material, was blended in the resin binder instead of the solder particles.

  Table 2 shows the evaluation results of Comparative Example 10. Alloy formation could not be confirmed, and the thermal resistance value was 28 (K / W). Moreover, the die shear strength of the LED mounting sample was 6.2N. Therefore, the overall evaluation was NG.

[Comparative Example 11]
An anisotropic conductive adhesive was produced in the same manner as in Example 1 except that 60 parts by mass of alumina powder having an average particle size of 10 μm, which is a heat dissipation material, was blended in the resin binder instead of the solder particles.

  Table 2 shows the evaluation results of Comparative Example 11. Alloy formation could not be confirmed, and the thermal resistance value was 35 (K / W). Moreover, the die shear strength of the LED mounting sample was 6.1N. Therefore, the overall evaluation was NG.

[Comparative Example 12]
An anisotropic conductive adhesive was produced in the same manner as in Example 1 except that 150 parts by mass of alumina powder having an average particle size of 10 μm, which is a heat dissipation material, was blended in the resin binder instead of the solder particles.

  Table 2 shows the evaluation results of Comparative Example 12. Alloy formation could not be confirmed, and the thermal resistance value was 33 (K / W). Moreover, the die shear strength of the LED mounting sample was 5.5N. Therefore, the overall evaluation was NG.

[Comparative Example 13]
An anisotropic conductive adhesive was produced in the same manner as in Example 1 except that 60 parts by mass of aluminum nitride powder having an average particle diameter of 1.5 μm, which is a heat dissipation material, was blended in the resin binder instead of the solder particles.

  Table 3 shows each evaluation result of Comparative Example 13. Alloy formation could not be confirmed, and the thermal resistance value was 22 (K / W). Moreover, the die shear strength of the LED mounting sample was 8.1N. Therefore, the overall evaluation was NG.

[Comparative Example 14]
An anisotropic conductive adhesive was produced in the same manner as in Example 1 except that 150 parts by mass of aluminum nitride powder having an average particle diameter of 1.5 μm, which is a heat dissipation material, was blended in the resin binder instead of the solder particles.

  Table 3 shows the evaluation results of Comparative Example 14. Alloy formation could not be confirmed, and the thermal resistance value was 19 (K / W). Moreover, the die shear strength of the LED mounting sample was 5.9N. Therefore, the overall evaluation was NG.

[Comparative Example 15]
An anisotropic conductive adhesive was produced in the same manner as in Example 1 except that 60 parts by mass of Ni powder having an average particle diameter of 3 μm, which is a heat dissipation material, was blended in the resin binder instead of the solder particles.

  Table 3 shows each evaluation result of Comparative Example 13. Alloy formation could not be confirmed, and the thermal resistance value was 28 (K / W). Moreover, the die shear strength of the LED mounting sample was 7.9N. Therefore, the overall evaluation was NG.

[Comparative Example 16]
An anisotropic conductive adhesive was produced in the same manner as in Example 1 except that 150 parts by mass of Ni powder having an average particle diameter of 3 μm, which is a heat dissipation material, was blended in the resin binder instead of the solder particles.

  Table 3 shows the evaluation results of Comparative Example 16. Alloy formation could not be confirmed, and the thermal resistance value was 27 (K / W). Moreover, the die shear strength of the LED mounting sample was 6.0 N. Therefore, the overall evaluation was NG.

[Comparative Example 17]
An anisotropic conductive adhesive was produced in the same manner as in Example 1, except that 60 parts by mass of Cu powder having an average particle size of 10 μm, which is a heat dissipation material, was blended in the resin binder instead of the solder particles.

  Table 3 shows each evaluation result of Comparative Example 17. Alloy formation could not be confirmed, and the thermal resistance value was 41 (K / W). Moreover, the die shear strength of the LED mounting sample was 8.12N. Therefore, the overall evaluation was NG.

[Comparative Example 18]
An anisotropic conductive adhesive was produced in the same manner as in Example 1 except that 150 parts by mass of Cu powder having an average particle size of 10 μm, which is a heat dissipation material, was blended in the resin binder instead of the solder particles.

  Table 3 shows the evaluation results of Comparative Example 18. Alloy formation could not be confirmed, and the thermal resistance value was 38 (K / W). Moreover, the die shear strength of the LED mounting sample was 6.2N. Therefore, the overall evaluation was NG.

[Comparative Example 19]
An anisotropic conductive adhesive was produced in the same manner as in Example 1 except that 60 parts by mass of diamond powder having an average particle size of 0.3 μm, which is a heat dissipation material, was blended in the resin binder instead of the solder particles.

  Table 3 shows the evaluation results of Comparative Example 19. Alloy formation could not be confirmed, and the thermal resistance value was 21 (K / W). Moreover, the die shear strength of the LED mounting sample was 8.3N. Therefore, the overall evaluation was NG.

[Comparative Example 20]
An anisotropic conductive adhesive was produced in the same manner as in Example 1 except that 150 parts by mass of diamond powder having an average particle size of 0.3 μm, which is a heat dissipation material, was blended in the resin binder instead of the solder particles.

  Table 3 shows the evaluation results of Comparative Example 20. Alloy formation could not be confirmed, and the thermal resistance value was 22 (K / W). Moreover, the die shear strength of the LED mounting sample was 8.1N. Therefore, the overall evaluation was NG.

  In Comparative Example 1, since solder particles were not blended, metal bonding due to molten solder did not occur, the thermal resistance value became too large, and the heat dissipation characteristics were deteriorated.

  In Comparative Examples 2 and 3, since a lot of solder particles were blended, a melted solder was formed, but the adhesive force was lowered between the aluminum wiring substrate and the anisotropic conductive adhesive. The adhesive force has decreased between the isotropic conductive adhesive and the LED element.

  In Comparative Examples 4, 5, and 6, since the melting point of the solder particles is 200 ° C., the solder is not sufficiently melted in the press-bonding process, and metal bonding due to the melted solder does not occur, and the anisotropic conductive adhesive. The adhesive strength between the LED element and the LED element decreased, and the thermal resistance value became too large, resulting in poor heat dissipation characteristics.

  In Comparative Examples 7, 8, 9, 10, 11, and 12, since alumina powder is used as the heat dissipation material, metal bonding due to molten solder does not occur, and the anisotropic conductive adhesive and the LED element are not bonded. The adhesive force was reduced, the thermal resistance value was too large, and the heat dissipation characteristics were deteriorated. The thermal conductivity of the alumina powder is 40 W / mK, but the desired characteristics could not be obtained even when contained in the adhesive instead of the solder particles by comparison with the examples of the present application.

  In Comparative Examples 13 and 14, since aluminum nitride powder is used as the heat dissipation material, metal bonding due to molten solder does not occur, and the adhesive force between the anisotropic conductive adhesive and the LED element is reduced. The heat resistance value becomes too large, and the heat dissipation characteristics are deteriorated. The thermal conductivity of the aluminum nitride powder is 180 W / mK, but the desired characteristics could not be obtained even when contained in the adhesive instead of the solder particles by comparison with the examples of the present application.

  Here, a case where aluminum nitride is added as a heat dissipation material will be considered. As shown in FIG. 7, when the aluminum nitride particles 61 are added to the resin binder 3, they are not easily melted like the solder particles, so that the grain shape is maintained, and the electrode 10 and the aluminum nitride particles 61 are Contact. Therefore, the area for transmitting heat from the LED element is very small, and the heat dissipation characteristics are deteriorated as compared with the case where solder particles are used. Further, the contact between the aluminum nitride particles 61 and the wiring 11 is also a point contact. Therefore, the heat dissipation characteristics from the aluminum nitride particles 61 to the wiring board side are also deteriorated.

  In Comparative Examples 15 and 16, since Ni powder is used as the heat dissipation material, metal bonding due to molten solder does not occur, and the adhesive force between the anisotropic conductive adhesive and the LED element is reduced. The thermal resistance value became too large, and the heat dissipation characteristics were deteriorated. The thermal conductivity of the Ni powder is 95 W / mK, but the desired characteristics could not be obtained even when contained in the adhesive instead of the solder particles by comparison with the examples of the present application.

  In Comparative Examples 17 and 18, since Cu powder is used as a heat dissipation material, metal bonding due to molten solder does not occur, and the adhesive force between the anisotropic conductive adhesive and the LED element decreases, The thermal resistance value became too large, and the heat dissipation characteristics were deteriorated. Although the thermal conductivity of the Cu powder is 400 W / mK, the desired characteristics could not be obtained even when contained in the adhesive instead of the solder particles by comparison with the examples of the present application.

  Here, a case where Cu particles are added as a heat dissipation material will be considered. As shown in FIG. 8, when Cu particles 62 are added to the resin binder 3, the particles 10 are not easily melted like the solder particles, so that the grain shape is maintained, and the electrode 10 and the Cu particles 62 are in point contact. This is the same as in the case of the aluminum nitride particles 61. Moreover, since the Cu particle 62 has a very large particle size, the adhesive thickness is increased. Even when Cu particles having high thermal conductivity were used, the thickness of the adhesive layer hindered the heat dissipation characteristics of the entire adhesive layer, and the desired heat dissipation characteristics could not be obtained.

  Further, in Comparative Examples 19 and 20, since diamond powder is used as a heat dissipation material, metal bonding due to molten solder does not occur, and the adhesive force between the anisotropic conductive adhesive and the LED element is reduced. The thermal resistance value became too large, and the heat dissipation characteristics were deteriorated. The thermal conductivity of the diamond powder is 1500 W / mK, but the desired characteristics could not be obtained even when contained in the adhesive instead of the solder particles by comparison with the examples of the present application.

  Here, a case where diamond particles are added as a heat dissipation material will be considered. As shown in FIG. 9, when diamond particles 63 are added to the resin binder 3, the diamond particles 63 are smaller than the thickness of the adhesive layer, and therefore cannot contact the electrode portion of the LED element or the wiring on the substrate side. That is, since a heat transfer path is not formed from the LED element to the wiring board side, even if diamond particles having high thermal conductivity are used, desired heat dissipation characteristics cannot be obtained.

  On the other hand, since Examples 1-6 are blended with an alicyclic epoxy compound, a latent cationic curing agent, and an acrylic resin having acrylic acid (AA) and 2-hydroxyethyl methacrylate (HEMA), Since it has characteristics for optical use, and furthermore, it can obtain high adhesive force and excellent conduction reliability for aluminum wiring having an oxide film, and the melting point of the solder particles is below the mounting temperature, In the crimping process, the solder particles were melted, and the molten solder was metal-bonded to the electrodes of the LED element, so that high adhesive force and excellent heat dissipation characteristics could be obtained.

  FIG. 10 shows the heat dissipation characteristics of the resin binder for reference. The resin A is an example in which the thermal conductivity is 10 W / mK, the resin B is the thermal conductivity 30 W / mK, the resin C is the thermal conductivity 50 W / mK, and the resin D is the thermal conductivity 70 W / mK. In general, it can be seen that the heat dissipation characteristics cannot be obtained unless the volume ratio (vol%) of the heat dissipation resin in the adhesive layer is increased. Since thermal resistance is defined as layer thickness / (adhesion area x thermal conductivity), if the layer thickness is increased too much, the thermal resistance will be increased. It turns out that it is not preferable.

  DESCRIPTION OF SYMBOLS 1 Solder particle, 1a Molten solder, 1b End surface (metal bonding surface), 2 Conductive particle, 3 Resin binder, 10 Electrode, 11 Wiring, 11a Oxide film, 12 Sea of epoxy compound, 13 Island of acrylic resin, 21 Substrate, 22 wiring patterns, 23 light emitting elements, 24 n electrodes, 25 p electrodes, 26 bumps, 30 anisotropic conductive films, 50 anisotropic conductive adhesives, 51 wiring boards, 52 LED chips, 53 heating tools, 54 tools, 60 Aluminum nitride particles, 61 Cu particles, 62 diamond particles

Claims (10)

An adhesive that bonds an electronic component that generates heat and a substrate,
An adhesive comprising a resin binder containing solder particles. The resin binder contains an alicyclic epoxy compound or a hydrogenated epoxy compound, a cation catalyst, and an acrylic resin having a weight average molecular weight of 50,000 to 900,000,
The adhesive according to claim 1, wherein the acrylic resin contains 0.5 to 10 wt% of acrylic acid and 0.5 to 10 wt% of an acrylate ester having a hydroxyl group.   The adhesive according to claim 1 or 2, wherein the solder particles have a blending amount of 50 parts by weight or more and less than 150 parts by weight.   The adhesive according to any one of claims 1 to 3, wherein the solder particles have an average particle size of 3 µm or more and less than 30 µm.   The adhesive according to any one of claims 1 to 4, wherein a content of the acrylic resin is 1 to 10 parts by mass with respect to 100 parts by mass of the epoxy resin.   The acrylic ester having a hydroxyl group is at least one selected from the group consisting of 2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate, 2-hydroxyethyl acrylate, and 2-hydroxypropyl acrylate. Item 6. The adhesive according to any one of Items 1 to 5.   The adhesive according to any one of claims 1 to 6, wherein the acrylic resin includes butyl acrylate, ethyl acrylate, and ethyl acrylate.   The adhesive according to any one of claims 1 to 7, wherein the cationic catalyst is an aluminum chelate-based latent curing agent.   The adhesive according to any one of claims 1 to 8, comprising conductive particles. A substrate having a wiring pattern;
An anisotropic conductive film formed on the electrode of the wiring pattern;
An electronic component that generates heat mounted on the anisotropic conductive film,
A connection structure in which the anisotropic conductive film contains a resin binder and solder particles, and the solder particles and terminal portions of the electronic component are metal-bonded.

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