TWI574594B - A method of manufacturing a connecting structure and an anisotropic conductive adhesive - Google Patents

Description

Method for manufacturing connecting structure and anisotropic conductive adhesive

The present technology relates to an anisotropic conductive adhesive in which conductive particles are dispersed, and a method for producing a bonded structure using the same, and more particularly to a wafer (element) capable of emitting a driver IC (Integrated Circuit) or an LED (Light Emitting Diode). An anisotropic conductive adhesive that generates heat, and a method of producing a bonded structure using the same.

As a method of assembling an LED element on a substrate, a wire bonding method is used. In addition, as a method of not using a bonding wire, a method of using a conductive paste is suggested, and as a method of not using a conductive paste, a method of using an anisotropic conductive adhesive is suggested.

Further, an LED element for fabricating a flip chip (FC: Flip Chip) has been developed, and as a method of arranging the LED element for the FC package on a substrate, gold tin eutectic bonding can be used. In addition, as a method of not using gold-tin eutectic bonding, a welding method using a solder paste is recommended, and as a method of not using a solder paste, a method of using an anisotropic conductive adhesive is suggested.

[Patent Document 1] Japanese Patent Laid-Open No. 11-4064

[Patent Document 2] Japanese Laid-Open Patent Publication No. 60-178690

[Patent Document 3] Japanese Patent Laid-Open No. Hei 11-176879

[Patent Document 4] Japanese Patent Laid-Open No. Hei 8-186156

[Patent Document 5] Japanese Patent Laid-Open Publication No. 2011-057917

However, since the thermal conductivity of the cured product of the anisotropic conductive adhesive is about 0.2 W/(m.K), the heat generated by the LED element cannot be sufficiently released to the substrate side. Further, since the FC having the anisotropic conductive adhesive is used, since only the conductive particles of the electrically connected portion serve as a heat dissipation path, the heat dissipation property is inferior.

Therefore, it is preferable to provide an anisotropic conductive adhesive having high connection reliability and high heat dissipation, and a method for producing a bonded structure.

In the present technology, it has been found that the above object can be attained by using solder particles as conductive particles and using an anisotropic conductive adhesive to perform heat pressing at a temperature lower than the melting point of the solder particles.

That is, the method for producing a bonded structure in one embodiment of the present technology includes the step of disposing a composition containing a thermosetting adhesive composition and solder particles dispersed in the thermosetting adhesive composition. The conductive adhesive is disposed between the terminal of the first electronic component and the terminal of the second electronic component, wherein the thermosetting adhesive composition contains an epoxy resin and an acid anhydride; and the electrical connection step is to use a terminal of the first electronic component And any one of the terminals of the second electronic component presses the anisotropic conductive adhesive at a temperature that does not reach the melting point of the solder paste, so that the solder particles are held between the terminal of the first electronic component and the terminal of the second electronic component. Thereby, the terminal of the first electronic component and the terminal of the second electronic component are electrically connected by solder bumps.

Further, the anisotropic conductive adhesive in one embodiment of the present technology contains: a thermosetting adhesive composition containing an epoxy resin and an acid anhydride, and a solder particle dispersed in the thermosetting adhesive composition, wherein The thermosetting adhesive composition in which the solder particles are dispersed is heated at a temperature that does not reach the melting point of the solder pellet.

According to the method for producing a bonded structure or the anisotropic conductive adhesive in an embodiment of the present technology, since the anisotropic conductive adhesive is pressed at a temperature that does not reach the melting point of the solder particles, although the surface of the solder fillet is wet, However, the entire solder pellet did not melt. Therefore, it is possible to ensure the bonding of the solder particles to the metal of the terminal surface, and to have an effect that the contact area will not be unnecessarily increased, thereby preventing cracks and the like generated in the heat cycle test. In addition, the contact formed by the metal bonding can function as a heat dissipation path. Therefore, it is possible to provide a manufacturing method in which the connection structure is high, the heat dissipation property is high, and in particular, the connection structure for connecting the LED elements is provided.

11, 101‧‧‧ element substrate

12, 102‧‧‧1st conductive coating

13, 103‧‧‧ active layer

14, 104‧‧‧2nd conductive coating

15, 105‧‧‧ Passivation layer

21, 201‧‧‧ substrate

22, 202‧‧‧first conductive type circuit pattern

23, 203‧‧‧2nd conductive type circuit pattern

31‧‧‧ solder pellets

32‧‧‧White inorganic particles

33, 305‧‧‧Binder

301‧‧‧welding line

302‧‧‧Solid crystal

303‧‧‧ conductive paste

304‧‧‧ sealing resin

1 is a cross-sectional view showing an embodiment of an LED package in an embodiment of the present technology.

2 is a cross-sectional view showing an embodiment of an LED package in another embodiment of the present technology.

Fig. 3 is a cross-sectional view showing an embodiment of an LED package using a wire bonding method.

Fig. 4 is a cross-sectional view showing an embodiment of an LED package using a conductive paste.

Fig. 5 is a cross-sectional view showing an embodiment of an LED package using an anisotropic conductive adhesive.

Fig. 6 is a cross-sectional view showing an embodiment of an LED package in which an LED for mounting an FC structure is bonded by a gold-tin eutectic bonding.

Fig. 7 is a cross-sectional view showing an embodiment of an LED package in which an LED for mounting an FC is mounted by a conductive paste.

Fig. 8 is a cross-sectional view showing an embodiment of an LED package in which an LED for an FC bonding is bonded to an anisotropic conductive adhesive.

An embodiment of the present technology will be described in detail below in the following order with reference to the accompanying drawings.

1. Anisotropic conductive adhesive and method for producing the same

2. Connection structure and manufacturing method thereof

3. Examples

<1. Anisotropic conductive adhesive and method for producing the same>

The anisotropic conductive adhesive in one embodiment of the present technology is an adhesive in which a solder paste is dispersed in a binder containing an epoxy resin and an acid anhydride (a thermosetting adhesive composition of an adhesive component), and has a shape Paste, film, etc., can be selected according to the purpose of use.

In one embodiment of the present technology, by making the anisotropic conductive adhesive have a configuration as described later, at the time of crimping, the solder particles are heated and pressurized at a temperature that does not reach the melting point thereof, so the solder particles are The surface is wet, but the entire pellet is not melted. Therefore, the bonding of the solder particles to the metal of the terminal surface can be ensured, and the contact area will not be unnecessarily increased, so that cracks and the like generated by the heat cycle test can be prevented. In addition, the contact formed by the metal bonding can function as a heat dissipation path. Therefore, it is possible to provide a manufacturing method in which the connection structure is high, the heat dissipation property is high, and in particular, the connection structure for connecting the LED elements is provided.

The composition and shape of the solder particles and the like are defined, for example, by JIS Z 3282-1999. As a constituent material of the solder particles, it may be from Sn-Pb type, Pb-Sn-Sb type, Sn-Sb type, Sn-Pb-Bi type, Bi-Sn type, Sn-Cu type, Sn-Pb-Cu type, In the Sn-In type, the Sn-Ag type, the Sn-Pb-Ag type, the Pb-Ag type, and the like, it is appropriately selected depending on the electrode material, the connection conditions, and the like. Further, the shape of the solder particles can be appropriately selected from granular or scaly shapes. Furthermore, the solder particles can also be The insulating layer is coated by increasing the anisotropy.

In one embodiment of the present technology, although the heating temperature at the time of heating pressing is set lower than the melting point of the solder particles, the heating temperature at the time of the heating pressing is preferably equal to or greater than the reaction start of the thermosetting adhesive composition. temperature. Specifically, when the reaction temperature of the thermosetting adhesive composition is generally 140 ° C to 220 ° C, the melting point of the solder particles is preferably 210 to 250 ° C, more preferably 210 to 240 ° C.

Among the solder particles, there are so-called solder particles having a solid phase point and a liquid phase point, and eutectic solder particles in which the solid phase point and the liquid phase point are substantially identical and are understood to be one melting point. In one embodiment of the present technology, although any of the solder pellets may be used, when the former solder pellet is used, the heat is pressed without reaching the solid phase point, when the latter solder pellet is used, Heating and pressing in the case of reaching the eutectic melting point. That is, in the present specification, the melting point of the solder particles means the solidus temperature at which the solid particles (solid) of the solid particles start to melt under atmospheric pressure.

The average particle diameter (D50) of the solder particles is preferably from 1 μm to 20 μm, more preferably from 2 μm to 10 μm. In addition, in view of connection reliability and insulation reliability, the blending amount of the solder particles is preferably in the range of 1% by volume to 50% by volume based on the total amount of the anisotropic conductive adhesive agent, particularly preferably 3% by volume to 25% by volume. range. When the blending amount of the solder particles is 3% by volume or more, connection reliability and heat dissipation can be ensured, and if it is 25% by volume or less, short-circuiting due to contact of adjacent solder particles can be avoided.

Further, as the conductive particles, in addition to the solder particles, the epoxy resin, the phenol resin, the acrylic resin, the acrylonitrile-styrene (AS) resin, and the benzoguanamine can be used together without affecting the effects of the present technology. The surface of the resin, the divinylbenzene resin, and the styrene resin is coated with metal coated resin particles of a metal such as Au, Ni, or Zn.

In addition, an anisotropic conductive adhesive (thermoset) in one embodiment of the present technology Preferably, the white inorganic particles are dispersed in the chemical binder composition. The purpose of blending white inorganic particles is not only to impart light reflectivity to the anisotropic conductive adhesive, but also to somewhat improve the thermal conductivity of some anisotropic conductive adhesives.

As the white inorganic particles, inorganic fine particles such as metal oxides, metal nitrides, and metal sulfides can be used, and it is preferred to use particles which exhibit gray to white under natural light. Specifically, as the white inorganic particles, various particles selected from titanium oxide, boron nitride, zinc oxide, and aluminum oxide are preferably used.

Further, the thermal conductivity of the white inorganic particles is preferably 10 W/(m.K) or more. By setting the thermal conductivity of the white inorganic particles to 10 W/(m.K) or more, the heat dissipation property of the bonded structure can be improved.

The shape of the white inorganic particles may be spherical, scaly, irregular, needle-like or the like, but in view of the reflectance, it is preferably spherical or scaly. If the average particle diameter (D50) of the white inorganic particles is larger than the solder particles, it will become an obstacle to the connection between the terminals, and therefore it is preferably smaller than the solder particles. Specifically, when the white inorganic particles are spherical, the average particle diameter (D50) is preferably 0.02 μm to 20 μm, more preferably 0.2 μm to 10 μm, still more preferably 0.2 μm to 1.0 μm.

Further, if the amount of the white inorganic particles blended is too small, the effect of achieving light reflectivity is not obtained, and if it is too much, the solder joint connection is hindered, so that it is preferably 1 volume of the total amount of the anisotropic conductive adhesive. %~50% by volume, more preferably 2% by volume to 25% by volume.

As the thermosetting adhesive composition, a conventional anisotropic conductive adhesive and an adhesive composition used for the anisotropic conductive film can be used. The main component of the thermosetting adhesive composition is an epoxy curing adhesive containing a alicyclic epoxy compound, a heterocyclic epoxy compound, a hydrogenated epoxy compound or the like as a main component.

As the alicyclic epoxy compound, those having two or more epoxy groups in the molecule are preferably exemplified. They may be in a liquid state or in a solid state. Specific examples thereof include hexahydrobisphenol A glycidyl ether and 3,4-epoxycyclohexylmethyl-3',4'-epoxycyclohexylcarboxylate. Among them, 3,4-epoxycyclohexylmethyl-3', 4' can be preferably used from the viewpoint of ensuring optical transmittance of a cured product suitable for LED element assembly and the like and having excellent rapid curability. - Epoxycyclohexylformate.

As examples of heterocyclic epoxy compounds, there are three Ring epoxy compounds, particularly preferred are 1,3,5-tris(2,3-epoxypropyl)-1,3,5-three -2,4,6-(1H,3H,5H)-trione.

As the hydrogenated epoxy compound, a hydrogenated product of the above alicyclic epoxy compound and a heterocyclic epoxy compound, or other known hydrogenated epoxy resin can be used.

The alicyclic epoxy compound, the heterocyclic epoxy compound or the hydrogenated epoxy compound may be used singly or in combination of two or more. Further, these epoxy compounds may be used in combination with other epoxy compounds as long as the effects of the present technique are not impaired. For example, bisphenol A, bisphenol F, bisphenol S, tetramethyl bisphenol A, diaryl bisphenol A, hydroquinone, catechol, resorcin, m-cresol, tetra Bromobisphenol A, trihydroxybiphenyl, benzophenone, bis resorcinol, bisphenol hexafluoroacetone, tetramethylbisphenol F, tris(hydroxyphenyl)methane, bisxylenol, Glycidyl ether formed by reaction of polyphenols such as phenol novolac and cresol novolak with epichlorohydrin; aliphatics such as glycerin, neopentyl glycol, ethylene glycol, propylene glycol, hexanediol, polyethylene glycol, polypropylene glycol a polyglycidyl ether formed by reacting a polyhydric alcohol with epichlorohydrin; a glycidyl ether ester formed by reacting a hydroxycarboxylic acid such as p-hydroxybenzoic acid or β-oxo-naphthoic acid with epichlorohydrin; Phthalic acid, methyl phthalic acid, isophthalic acid, terephthalic acid, tetrahydrophthalic acid, endea Polyglycidyl ester obtained from polycarboxylic acid such as tetrahydrophthalic acid, internal hexahydrophthalic acid, trimellitic acid, or polymeric fatty acid; shrinkable aminoglycidyl obtained from aminophenol or aminoalkylphenol Ether; glycidyl aminoglycidyl ester obtained from aminobenzoic acid; from aniline, toluidine, tribromoaniline, m-xylylenediamine, diaminocyclohexane, bisaminomethylcyclohexane, 4,4'-di A glycidylamine obtained by aminodiphenylmethane, 4,4'-diaminodiphenylphosphonium or the like; a known epoxy resin such as an epoxidized polyolefin.

Examples of the curing agent for reacting the main component include an acid anhydride, an imidazole compound, and dicyandiamide. Among them, an acid anhydride which is less likely to cause discoloration of a cured product, particularly an alicyclic acid anhydride type curing agent, can be preferably used. Specifically, methylhexahydrophthalic anhydride or the like is preferably exemplified.

Further, the acid anhydride can function as a flux for the solder particles, and the equivalent amount of the epoxy resin exceeding the epoxy resin of the main agent is also no problem. Specifically, from the viewpoint of the reaction, it is sufficient to blend 0.7 equivalent to 1.0 equivalent of an acid anhydride to 1.0 equivalent of the epoxy resin, and it is preferable to blend 1.0 to 1.3 equivalents of an acid anhydride in order to further exert the function of the flux. . Therefore, it is preferred to blend 0.7 to 1.3 equivalents of an acid anhydride for 1.0 equivalent of the epoxy resin. It is also possible to blend more than 1.0 equivalent of anhydride for 1.0 equivalent of epoxy resin.

The anisotropic conductive adhesive thus constituted, in addition to the manufacturing method described later, can achieve high heat dissipation and high connection reliability while maintaining a certain contact area between the terminals.

<2. Connection structure and method of manufacturing the same>

Next, a bonded structure using the above an anisotropic conductive adhesive will be described. In the connection structure according to the embodiment of the present invention, the terminal of the first electronic component and the terminal of the second electronic component are conductive particles formed by forming a conductive metal layer on the surface of the resin particle. And make an electrical connection. The solder bump can be captured (held) between the terminal of the first electronic component and the terminal of the second electronic component.

The electronic component in one embodiment of the present technology is applied to a wafer (element) such as a driver IC (Integrated Circuit) or an LED (Light Emitting Diode) that generates heat.

Fig. 1 is a cross-sectional view showing the configuration of an LED package. In the LED package, an LED conductive member (first electronic component) and a substrate (second electronic component) on which the LED device is mounted are connected by using an anisotropic conductive adhesive in which the solder particles are dispersed in an adhesive component. .

The LED element has, for example, a first conductive type cladding layer 12 formed of n-GaN, an active layer 13 formed of, for example, an In _x Al _y Ga _1-xy N layer, and, for example, p, on the element substrate 11 made of sapphire. The second conductive type cladding layer 14 formed of GaN has a so-called double heterostructure. In addition, the first conductive type electrode 12a is provided in one of the first conductive type cladding layers 12, and the second conductive type electrode 14a is provided in one of the second conductive type coating layers 14. When a voltage is applied between the first conductive type electrode 12a and the second conductive type electrode 14a of the LED element, carriers are concentrated in the active layer 13 and recombined to emit light.

In the substrate, the first conductive type circuit pattern 22 and the second conductive type circuit pattern 23 are provided on the substrate 21, and the electrodes are respectively provided at the first conductive type electrode 12a and the second conductive type electrode 14a corresponding to the LED element. 22a and electrode 23a.

The anisotropic conductive adhesive is the same as described above, and the solder particles 31 and the white inorganic particles 32 are dispersed in the binder 33.

As shown in FIG. 1, in the LED package, the terminals (electrodes 12a, 14a) of the LED elements and the terminals (electrodes 22a, 23a) of the substrate are electrically connected by solder particles 31. Further, white inorganic particles 32 are dispersed between the LED element and the substrate.

Therefore, the heat generated by the active layer 13 of the LED element can be effectively released to the substrate side by the solder particles 31, preventing the luminous efficiency from being lowered and extending the service life of the LED package. Further, since the white inorganic particles 32 are white or gray achromatic, light from the active layer 13 can be reflected to obtain high luminance.

In addition, as shown in FIG. 2, the LED element for fabricating the flip chip can widely design the terminals (electrodes 12a, 14a) of the LED element by the passivation layer 15, and thus the terminal of the LED element (electrode 12a, 14a) More solder particles 31 can be trapped between the terminals of the substrate (circuit patterns 22, 23). Therefore, the heat generated by the active layer 13 of the LED element can be more effectively released to the substrate side.

Further, the materials of the terminals (12a, 14a) of the LED elements and the terminals (22, 23) of the substrate are preferably eutectic bonded to the solder particles, and are preferably gold (Au) or gold-tin alloy (AuSn). Specifically, it is preferable that the terminals (12a, 14a) of the LED elements and the terminals (22, 23) of the substrate contain gold. More preferably, the terminals (12a, 14a) of the LED elements are gold-tin alloys, and the terminals (22, 23) of the substrate are gold.

Next, a method of manufacturing the above-described bonded structure will be described. A method of manufacturing a package according to an embodiment of the present technology has the following steps: a step of disposing an anisotropic conductive adhesive in which the above-described solder particles are dispersed in a thermosetting adhesive composition containing an epoxy resin and an acid anhydride. Between the terminal of the first electronic component and the terminal of the second electronic component; and the pressing step: pressing any one of the terminal of the first electronic component and the terminal of the second electronic component to press the anisotropy at a predetermined heating temperature The conductive adhesive causes the solder particles to be caught between the terminals of the first electronic component and the terminals of the second electronic component. In the pressing step, the anisotropic conductive adhesive is heated and pressed by a heating tool such as a heating head using the first electronic component and the second electronic component.

When the solder paste is caught between the terminal of the first electronic component and the terminal of the second electronic component by the heat pressing, the heating temperature does not reach the melting point of the solder ball, so that the solder particles are not melted as a whole. Terminal contact. More specifically, the heating temperature is preferably equal to or higher than the reaction initiation temperature of the thermosetting adhesive composition and lower than the melting point of the solder pellet by 15 ° C or lower. Therefore, the contact area of the solder particles with the terminals will not be unnecessarily increased, thereby preventing cracks and the like generated by the heat cycle test.

Further, when only the heating tool is used, the temperature of the heating tool can be approximately regarded as the heating temperature at the time of heating pressing. In addition, when the stage in which the connection structure is disposed is heated, since the temperature applied to the anisotropic conductive adhesive may be higher than the temperature of the heating tool, the temperature of the heating tool is not used as a standard, and it is preferable to use a thermocouple. The measuring instrument directly measures the temperature of the heated anisotropic conductive adhesive.

Further, the method of manufacturing the bonded structure and the method of the anisotropic conductive adhesive and the problems thereof, which do not use the above-described one embodiment of the present technology, are as follows.

As a method of assembling an LED element on a substrate, a wire bonding (WB: Wire Bonding) method is used. As shown in FIG. 3, in the WB method, the electrodes of the LED elements (the first conductive type electrode 104a and the second conductive type electrode 102a) face up, and the LED elements are bonded using the bonding wires (WB) 301a and 301b. The substrate is electrically bonded to the substrate, and the LED element and the substrate are bonded using the bonding material 302.

However, such a method of electrically connecting by a bonding wire requires a higher risk and a higher risk of physical breakage and peeling of the bonding wires from the electrodes (the first conductive type electrode 104a and the second conductive type electrode 102a). Technology. Furthermore, the curing process of the solid crystal material 302 requires a long production time due to curing in an oven.

As a method of not using a bonding wire, as shown in FIG. 4, the electrode of the LED element (the first conductive type electrode 104a and the second conductive type electrode 102a) faces the substrate side (face down, flips the wafer), and is used. A method in which the LED element and the substrate are electrically connected to each other by a conductive paste 303 (303a, 303b) typified by a silver paste.

However, since the adhesive force of the conductive paste 303 (303a, 303b) is weak, it is necessary to be reinforced with the sealing resin 304. Furthermore, the curing process of the sealing resin 304 requires a long production time due to curing using an oven.

As a method of not using the conductive paste, as shown in FIG. 5, the electrode surface of the LED element is directed toward the substrate side (face down, flip chip), and the conductive particles 306 are dispersed in the insulating adhesive 305. An anisotropic conductive adhesive is a method of electrically connecting and bonding the LED element to the substrate. Since the bonding process of the anisotropic conductive adhesive is short, the production efficiency is good. Further, the anisotropic conductive adhesive is inexpensive, and has excellent transparency, adhesion, heat resistance, mechanical strength, electrical insulation, and the like.

In addition, LED elements for fabricating flip chip (FC: Flip Chip) have been developed. In the LED component for the FC package, since the electrode area can be largely designed by the passivation layer 105, the interference-free package can be performed. In addition, the light extraction efficiency can be improved by providing a reflective film under the light-emitting layer.

As a method of assembling the LED element for FC mounting in a substrate, as shown in FIG. 6, gold-tin eutectic bonding can be used. The gold tin eutectic bonding is performed by forming a wafer electrode using a gold tin alloy 307, then applying a flux to the substrate, mounting the wafer, and heating to bond the substrate and the electrode eutectic. However, such a welding method has a poor yield due to wafer offset occurring during heating or the flux is not washed to affect reliability. In addition, a high degree of construction technology is required.

As a method of not using the gold tin eutectic, as shown in FIG. 7, there is a welding method in which the LED element and the substrate are electrically connected using a solder paste. However, in this welding method, since the paste has an isotropic conductivity, short-circuiting between the pn electrodes results in poor yield.

As a method of not using a solder paste, as shown in FIG. 8, an anisotropic conductive adhesive such as an ACF (Anisotropic Conductive Film) in which conductive particles are dispersed in an insulating adhesive as in FIG. 5 is used. A method of electrically connecting and bonding a substrate. When an anisotropic conductive adhesive is used, the pn electrodes are filled with an insulating adhesive. Therefore, the yield can be improved because the short circuit is less likely to occur. In addition, since the bonding process is short, the production efficiency is good.

However, the active layer (junction) 103 of the LED element generates a large amount of heat in addition to light. If the temperature of the light-emitting layer (Tj=junction temperature) reaches 100 ° C or higher, the luminous efficiency of the LED is lowered, and the life of the LED is shortened. . Therefore, a structure capable of effectively releasing the heat of the active layer 103 is required.

In the WB package shown in FIG. 3, since the active layer 103 is above the LED element, the generated heat cannot be efficiently transmitted to the substrate side, so the heat dissipation is poor.

Further, if the flip chip is mounted as shown in FIGS. 4, 6, and 7, since the active layer 103 is on the substrate side, heat energy is efficiently transmitted to the substrate side. As shown in FIG. 4 and FIG. 7, when the electrodes are bonded by the conductive paste 303 (303a, 303b), heat can be efficiently radiated, but the connection by the conductive paste 303 (303a, 303b) is poor in connection reliability as described above. . Further, as shown in FIG. 6, even if gold-tin eutectic bonding is performed, the connection reliability is inferior as described above.

Further, as shown in FIGS. 5 and 8, the active layer can be formed by using a conductive paste 303 (303a, 303b) and a flip chip by using an anisotropic conductive adhesive such as ACF or ACP (Anisotropic Conductive Paste). 103 is disposed near the substrate side, effectively transferring heat to The substrate side. In addition, because of the strong bonding force, high connection reliability can be obtained.

Further, as a technique similar to solder paste, solder particles as conductive particles may be blended in an anisotropic conductive adhesive.

Further, in order to effectively utilize the light incident into the inside of the adhesive layer, the anisotropic conductive adhesive used in the LED element may contain white inorganic particles to reflect the light to increase the total amount of light emitted from the LED element.

When the solder particles are used in the anisotropic conductive adhesive, not only the connection reliability but also the heat dissipation property can be ensured. However, if the entire solder pellet is melted, the contact area between the solder bump and the terminal will unnecessarily increase, and in this state, a heat cycle test is performed, and defects such as cracks are generated.

Further, when the anisotropic conductive adhesive contains white inorganic particles, the thermal conductivity of the anisotropic conductive adhesive containing white inorganic particles is 10 W/(m.K), and it is expected to have a high thermal conductivity. Improve heat dissipation. However, if the particle diameter of the white inorganic particles is equal to or larger than the particle diameter of the conductive particles, it will cause a poor contact between the terminals of the LED element and the terminals of the substrate. Further, when the particle diameter of the white inorganic particles is small, the terminals are not in contact with each other and cannot be a heat dissipation path. As a result, the reality is that white inorganic particles cannot promote heat dissipation if it is desired to ensure connection reliability.

[Examples]

<3. Example>

Embodiments of the present technology will be described in detail below, but the present technology is not limited to these embodiments.

[Production of anisotropic conductive adhesive]

In Examples 1 to 3 and Comparative Examples 2 and 3, the surface of the white inorganic particles was coated with Si. And titanium oxide (product name: JR, manufactured by Tayca Co., Ltd.) having an average particle diameter of 0.5 μm, and solder particles (M707, manufactured by Senju Metal Co., Ltd.) dispersed in an epoxy resin curable adhesive. Become the desired anisotropic conductive adhesive.

Further, the composition of the above-mentioned solder particles was Sn-3.0Ag-0.5Cu, and its melting point (solid phase point) was 217 °C. Further, the white inorganic particles had a refractive index of 2.71. Further, in the epoxy resin-curable adhesive, an alicyclic epoxy resin (product name: CEL2021P, manufactured by Daicel Chemical Co., Ltd.) and an acid anhydride (MH700, manufactured by Nippon Chemical and Chemical Co., Ltd.) are respectively 1.0:1.1. The equivalence ratio is blended.

In Example 4, an anisotropic conductive adhesive was produced in the same manner as in Example 1 except that the solder pellets (M10, manufactured by Senju Metal Co., Ltd.) were replaced. Here, the composition of the solder particles was Sn-5.0Sb, and its melting point (solid phase point) was 240 °C.

In Example 5, an anisotropic conductive adhesive was produced in the same manner as in Example 1 except that the white inorganic particles were not blended.

In Comparative Example 1, except that the conductive particles (particles formed by electroless gold plating of 0.2 μm of acrylic resin particles, manufactured by Nippon Chemical Industry Co., Ltd.) were used instead of the solder particles, the same method as in Example 1 was used. A conductive adhesive.

In Comparative Example 2, an anisotropic conductive adhesive was produced in the same manner as in Example 1 except that the acid anhydride was not used.

The composition of the anisotropic conductive adhesive in Comparative Example 3 was the same as that of Example 1, but as will be described later, the difference was that the temperature at the time of heat pressing was higher than the melting point of the solder particles.

[Measurement of Light Reflectance of Anisotropic Conductive Adhesive]

The above various anisotropic conductive adhesives were applied in such a manner that the thickness after drying was 100 μm. The white plate made of ceramic was then cured by heating at 200 ° C for 1 minute. Next, the reflectance of the cured product against light having a wavelength of 450 nm (JIS K7150) was measured using a spectrophotometer (U3300, Hitachi, Ltd.). The results obtained are shown in Table 1. It is desirable that the reflectance is 30% or more in actual use.

[Production of LED structure]

Using the anisotropic conductive adhesives of Examples 1, 2, 4, and 5 and Comparative Examples 1 to 3, an LED chip for flip chip which does not require Au bumps (blue LED, Vf = 3.2 V (If = 350 mA) )) Mounted on the Au electrode substrate. After the anisotropic conductive adhesive is applied to the Au electrode substrate, the LED chip is mounted in alignment, by changing the temperature of the heating head (180 ° C, 200 ° C, 220 ° C, 260 ° C), at 60 sec - 1 kg / chip Heating and crimping are carried out under the conditions. Further, the temperature of the anisotropic conductive adhesive was directly measured using a thermocouple measuring device (product name: data logger, manufactured by Graphtec) in accordance with the temperature of the heating head.

Further, after forming an Au bump using an uneven soldering machine, planarization treatment was performed to use it as an Au electrode substrate (epoxy glass substrate, conductive space = 100 μm, Ni/Au plating = 5.0 μm / 0.3 μm, gold bump = 15 μm) ).

The heat dissipation characteristics, optical characteristics, adhesive properties, and electrical characteristics of the obtained LED package are shown in Table 1. Furthermore, each measurement method is as follows.

Further, in the third embodiment, an LED wafer having AuSn bumps is mounted on the Au electrode substrate.

[Evaluation of heat dissipation]

The thermal resistance (°C/W) of the LED package was measured using a transient thermal resistance measuring device (manufactured by CATS Electronic Design Co., Ltd.). The measurement condition was If=200 mA (constant current control).

[Evaluation of optical characteristics]

The total beam amount (mlm) of the LED package was measured using a total beam measuring device (LE-2100, manufactured by Otsuka Electronics Co., Ltd.) using the integrating sphere principle. The measurement condition was If=200 mA (constant current control).

[Evaluation of adhesion characteristics (Die shear)]

The shear strength of the wafer/anisotropic conductive adhesive/substrate was measured. Shear strength refers to the strength measured when the fabricated LED wafer is pulled laterally when the wafer is detached. The measurement was performed at a measurement speed of 20 μm/sec in a measurement environment of 25 °C. The measuring device used was a Bond Tester PTR-1100 (manufactured by Resuka Corporation).

[Evaluation of electrical characteristics]

(conductive properties)

As the initial Vf value, the Vf value at If = 20 mA was measured. Further, 1000 thermal shock tests were carried out under the conditions of -40 ° C / 30 minutes < > 100 ° C / 30 minutes, and the Vf value at If = 20 mA was measured. The initial stage of the thermal shock test was evaluated as follows: When it was confirmed that the electric conduction was cut (OPEN), the evaluation was "x", and the other evaluation was "○". After the thermal shock test, it was evaluated as follows: when the initial Vf value was 5% or more, it was conductive NG, and the evaluation was "x", and the others were evaluated as "○". Furthermore, "○" means good, and "X" means bad.

(insulation characteristics)

The initial Ir value when a reverse voltage of 5 V was applied was measured, and if Ir = 1 μA or more, the leakage NG was evaluated, and it was evaluated as "X", and the others were evaluated as "○".

Table 1 shows the evaluation results of Examples 1 to 5 and Comparative Examples 1 to 3.

In Example 1, a solder pellet (particle size: 10 μm, mp 217 ° C) and white inorganic particles were mixed in an adhesive containing epoxy resin (CEL2021P) and an acid anhydride (MH700) as a main component, and light was obtained at 450 nm. An anisotropic conductive adhesive having a reflectance of 65%. At the temperature lower than the melting point of the solder pellets, the anisotropic conductive adhesive is used to perform "Alumina-plated LED wafer on the LED wafer-side electrode" and "A Au-plated substrate on the substrate-side electrode". The heating and crimping and electrical connection are performed to obtain an LED module. The total luminous flux of the LED module is 9 lm, the thermal resistance of the electrical connection portion is 15 K/W, and the shear strength is 50 N/1 mm □. Observing the cross-section of the electrical connection portion of the LED module, it was confirmed that the LED wafer side electrode and the solder particles, and the substrate side electrode and the solder pellet were Au-Su eutectic bonded, and the solder particles were not pulverized and dispersed, and the adhesive layer was maintained. thickness of. In addition, the initial conductivity characteristics and initial insulation characteristics of the LED module were good, and stable conductive characteristics were also obtained in the TCT test (-40 to 100).

In Example 2, in a binder containing an epoxy resin (CEL2021P) and an acid anhydride (MH700) as a main component, a solder particle (particle size: 10 μm, mp 217 ° C) and white inorganic particles were mixed to obtain a light at 450 nm. An anisotropic conductive adhesive having a reflectance of 65%. At the temperature lower than the melting point of the solder particles, the Au-plated LED chip is formed on the LED wafer side electrode and the Au-plated substrate is formed on the substrate-side electrode using the anisotropic conductive adhesive. The heating and crimping and electrical connection are performed to obtain an LED module. The total luminous flux of the LED module is 9 lm, the thermal resistance of the electrical connection portion is 15 K/W, and the shear strength is 50 N/1 mm □. Observing the cross-section of the electrical connection portion of the LED module, it was confirmed that the LED wafer side electrode and the solder particles, and the substrate side electrode and the solder pellet were Au-Su eutectic bonded, and the solder particles were not pulverized and dispersed, and the adhesive layer was maintained. thickness of. In addition, the initial conductivity characteristics and initial insulation characteristics of the LED module were good, and stable conductive characteristics were also obtained in the TCT test (-40 to 100).

In Example 3, in a binder containing epoxy resin (CEL2021P) and an acid anhydride (MH700) as a main component, a solder particle (particle size: 10 μm, mp 217 ° C) and white inorganic particles were mixed to obtain a light at 450 nm. An anisotropic conductive adhesive having a reflectance of 65%. At the temperature lower than the melting point of the solder pellets, the anisotropic conductive adhesive is used to perform "an AuSn-plated LED wafer on the LED wafer side electrode" and "A Au plating substrate on the substrate side electrode". The heating and crimping and electrical connection are performed to obtain an LED module. The total beam amount of the LED module is 9 lm, the thermal resistance of the electrical connection portion is 15 K/W, and the shear strength is 45 N/1 mm □. Observing the cross-section of the electrical connection portion of the LED module, it was confirmed that the LED wafer side electrode and the solder particles, and the substrate side electrode and the solder pellet were Au-Su eutectic bonded, and the solder particles were not pulverized and dispersed, and the adhesive layer was maintained. thickness of. In addition, the initial conductivity characteristics and initial insulation characteristics of the LED module were good, and stable conductive characteristics were also obtained in the TCT test (-40 to 100).

In Example 4, in a binder containing epoxy resin (CEL2021P) and an acid anhydride (MH700) as a main component, a solder particle (particle size: 10 μm, mp 240 ° C) and white inorganic particles were mixed, and light was obtained at 450 nm. An anisotropic conductive adhesive having a reflectance of 60%. At the temperature 220 ° C lower than the melting point of the solder particles, "the Au-plated LED chip is formed on the LED wafer-side electrode" and "the Au-plated substrate is formed on the substrate-side electrode" using the anisotropic conductive adhesive. The heating and crimping and electrical connection are performed to obtain an LED module. The total beam amount of the LED module is 8.5 lm, the thermal resistance of the electrical connection portion is 14 K/W, and the shear strength is 40 N/1 mm □. Observing the cross-section of the electrical connection portion of the LED module, it was confirmed that the LED wafer side electrode and the solder particles, and the substrate side electrode and the solder pellet were Au-Su eutectic bonded, and the solder particles were not pulverized and dispersed, and the adhesive layer was maintained. thickness of. In addition, the initial conductivity characteristics and initial insulation characteristics of the LED module were good, and stable conductive characteristics were also obtained in the TCT test (-40 to 100).

In Example 5, in a binder containing an epoxy resin (CEL2021P) and an acid anhydride (MH700) as a main component, a solder pellet (particle diameter: 10 μm, mp 240 ° C) was mixed, and a reflectance of 8 was obtained under illumination of 450 nm. % anisotropic conductive adhesive. At the temperature lower than the melting point of the solder particles, the Au-plated LED chip is formed on the LED wafer side electrode and the Au-plated substrate is formed on the substrate-side electrode using the anisotropic conductive adhesive. The heating and crimping and electrical connection are performed to obtain an LED module. Although the total beam amount of the LED module is as low as 5 lm, the electrical connection portion has a thermal resistance of 15 K/W and a shear strength of 50 N/1 mm □. Observing the cross-section of the electrical connection portion of the LED module, it was confirmed that the LED wafer side electrode and the solder particles, and the substrate side electrode and the solder pellet were Au-Su eutectic bonded, and the solder particles were not pulverized and dispersed, and the adhesive layer was maintained. thickness of. In addition, the initial conductivity characteristics and initial insulation characteristics of the LED module were good, and stable conductive characteristics were also obtained in the TCT test (-40 to 100).

In Comparative Example 1, conductive particles (particles having a particle diameter of 10 μm and Au-plated with a resin core surface) and white inorganic particles were mixed in a binder containing an epoxy resin (CEL2021P) and an acid anhydride (MH700) as main components. An anisotropic conductive adhesive having a reflectance of 55% under illumination of 450 nm was obtained. At the temperature lower than the melting point of the solder particles, the Au-plated LED chip is formed on the LED wafer side electrode and the Au-plated substrate is formed on the substrate-side electrode using the anisotropic conductive adhesive. The heating and crimping and electrical connection are performed to obtain an LED module. Although the total beam amount of the LED module is 7 lm, the electrical resistance of the electrical connection portion is as high as 30 K/W, and the shear strength is as low as 20 N/1 mm □. In addition, the initial conductivity characteristics and initial insulation characteristics of the LED module were good, and stable conductive characteristics were also obtained in the TCT test (-40 to 100).

In Comparative Example 2, in a binder containing an epoxy resin (CEL2021P) and an amine curing agent as a main component, a solder pellet (particle size: 10 μm, mp 217 ° C) and white inorganic particles were mixed. An anisotropic conductive adhesive having a reflectance of 65% under illumination of 450 nm was obtained. At the temperature lower than the melting point of the solder particles, the Au-plated LED chip is formed on the LED wafer side electrode and the Au-plated substrate is formed on the substrate-side electrode using the anisotropic conductive adhesive. The heating and crimping and electrical connection are performed to obtain an LED module. Although the total beam amount of the LED module is 9 lm, the electrical resistance of the electrical connection portion is as high as 25 K/W, and the shear strength is as low as 20 N/1 mm □. As a result of observing the cross section of the electrical connection portion of the LED module, it was confirmed that Au-Su eutectic bonding did not occur between the LED wafer side electrode and the solder bump, and the substrate side electrode and the solder bump. As a result, the initial conductive characteristics and initial insulation characteristics of the LED module were good, but the conductive OPEN occurred after 1000 cycles in the TCT test (-40 to 100).

In Comparative Example 3, in a binder containing epoxy resin (CEL2021P) and an acid anhydride (MH700) as a main component, a solder pellet (particle size: 10 μm, mp 217 ° C) and white inorganic particles were mixed to obtain a light at 450 nm. An anisotropic conductive adhesive having a reflectance of 65%. At the temperature 260 ° C higher than the melting point of the solder particles, the Au-plated LED chip is formed on the LED wafer side electrode and the Au-plated substrate is formed on the substrate-side electrode using the anisotropic conductive adhesive. The heating and crimping and electrical connection are performed to obtain an LED module. As a result, the initial conductive characteristics of the LED module are short-circuited. Further, as a result of observing the cross section of the electrical connection portion of the LED module, it was confirmed that the solder particles were melted and diffused between the PN electrodes.

As described above, as a method of electrically connecting the electrode of the LED element and the electrode of the substrate, it is possible to manufacture by using an anisotropic conductive adhesive containing solder particles and heating and pressing at a temperature lower than the melting point of the solder pellet. LED module with high heat dissipation characteristics and high adhesion characteristics. Further, it was found that the heating temperature and the melting point of the solder particles were different from each other in Examples 1 to 4 by 17 ° C, 20 ° C, and 37 ° C, that is, the difference between the heating temperature and the melting point of the solder pellet was 15 ° C or higher. In addition, Examples 1 to 4 were found. In the bonded structure of the LED wafer, the white inorganic particles are blended, and the reflectance is high, so that the optical characteristics are improved. Further, it was found that in Examples 1 to 5, since an acid anhydride was used as a curing agent, and the acid anhydride had a function as a flux in addition to the epoxy resin which cured the main component, compared with Comparative Example 2 in which no acid anhydride was blended, High adhesion characteristics can be obtained.

In addition, the present technology can also adopt the following configuration.

(1)

The method for producing a bonded structure includes a step of disposing the anisotropic conductive adhesive containing a thermosetting adhesive composition and solder particles dispersed in the thermosetting adhesive composition in the first electronic component Between the terminal and the terminal of the second electronic component, wherein the thermosetting adhesive composition contains an epoxy resin and an acid anhydride; and the electrical connection step: using the terminal of the first electronic component and the terminal of the second electronic component And pressing the anisotropic conductive adhesive at a temperature that does not reach the melting point of the solder particles, and holding the solder particles between the terminal of the first electronic component and the terminal of the second electronic component; The terminal of the electronic component and the terminal of the second electronic component are electrically connected by the solder bump.

(2)

The method for producing a bonded structure according to (1), wherein the temperature is 15 ° C or more lower than a melting point of the solder pellet.

(3)

The method for producing a bonded structure according to any one of (1), wherein the temperature is higher than a reaction initiation temperature of the thermosetting adhesive composition.

(4)

The method for producing a bonded structure according to any one of (1) to (3) wherein the solder pellet has a melting point of about 210 ° C to 250 ° C.

(5)

The method for producing a bonded structure according to any one of (1), wherein the thermally curable adhesive composition has white inorganic particles dispersed therein.

(6)

(5) The method for producing a bonded structure according to (5), wherein the white inorganic particles have a thermal conductivity of about 10 W/(m.K) or more.

(7)

The method of manufacturing any of the connection structures according to the above aspect, wherein the first electronic component is an LED element, and the second electronic component is a substrate on which the LED element is mounted.

(8)

(7) The method for producing a bonded structure according to (7), wherein the terminal of the LED element contains gold, and the terminal of the substrate contains gold.

(9)

(8) The method for producing a bonded structure according to (8), wherein the terminal of the LED element is a gold-tin alloy, and the terminal of the substrate is gold.

(10)

The anisotropic conductive adhesive contains: a thermosetting adhesive composition containing an epoxy resin and an acid anhydride; solder particles dispersed in the thermosetting adhesive composition; and the thermosetting adhesive agent in which the solder particles are dispersed The composition is heated at a temperature that does not reach the melting point of the solder pellet.

(11)

The anisotropic conductive adhesive according to (10), wherein the thermally curable adhesive composition has white inorganic particles dispersed therein.

(12)

The anisotropic conductive adhesive according to (11), wherein the white inorganic particles have an average particle diameter of about 0.2 μm to 10 μm, and the white inorganic particles are contained in an amount of about the total amount of the anisotropic conductive adhesive. 1% by volume to 50% by volume; the average particle diameter of the solder particles is about 1 μm to 20 μm, the welding The content of the granules is about 1% by volume to 50% by volume based on the total amount of the anisotropic conductive adhesive; and 0.7 equivalents to 1.3 equivalents of the acid anhydride is contained with respect to 1.0 equivalent of the epoxy resin.

(13)

The anisotropic conductive adhesive according to (12), wherein the epoxy resin contains more than 1.0 equivalent of an acid anhydride with respect to 1.0 equivalent of the epoxy resin.

The present application claims priority on the basis of Japanese Patent Application No. 2012-210225, filed on Sep. 24, 2012, the entire entire entire entire entire entire entire entire content

Any modifications, combinations, sub-combinations and alterations made by the industry in accordance with the design requirements and other factors should be included in the scope of the additional patent application and its equivalents.

12‧‧‧1st conductive coating

12a‧‧‧1st conductive electrode

13‧‧‧Active layer

14‧‧‧2nd conductive coating

14a‧‧‧2nd conductive electrode

21‧‧‧Substrate

22‧‧‧Circuit pattern for the first conductivity type

22a‧‧‧electrode

23‧‧‧Circuit pattern for the second conductivity type

23a‧‧‧Electrode

31‧‧‧ solder pellets

32‧‧‧White inorganic particles

33‧‧‧Binder

Claims (13)

A method for producing a bonded structure, comprising the steps of: disposing an anisotropic conductive adhesive containing a thermosetting adhesive composition and solder particles dispersed in the thermosetting adhesive composition in a step of disposing The terminal of the first electronic component and the terminal of the second electronic component, wherein the thermosetting adhesive composition contains an epoxy resin and an acid anhydride; and the electrical connection step: using the terminal of the first electronic component and the second electronic component Any one of the terminals presses the anisotropic conductive adhesive at a temperature that does not reach the melting point of the solder particles, and the solder resist is held between the terminal of the first electronic component and the terminal of the second electronic component. Thereby, the terminal of the first electronic component and the terminal of the second electronic component are electrically connected by the solder bump. The method for producing a bonded structure according to claim 1, wherein the temperature is 15 ° C or more lower than a melting point of the solder pellet. The method for producing a bonded structure according to claim 1, wherein the temperature is higher than a reaction initiation temperature of the thermosetting adhesive composition. The method for producing a bonded structure according to claim 1, wherein the solder pellet has a melting point of about 210 ° C to 250 ° C. The method for producing a bonded structure according to claim 1, wherein the thermally curable adhesive composition has white inorganic particles dispersed therein. The method for producing a bonded structure according to claim 5, wherein the white inorganic particles have a thermal conductivity of about 10 W/(m.K) or more. The method of manufacturing a bonded structure according to the first aspect of the invention, wherein the first electronic component is an LED component, and the second electronic component is a substrate on which the LED component is mounted. The method for manufacturing a bonded structure according to claim 7, wherein the LED element The terminal of the piece contains gold, and the terminal of the substrate contains gold. The method for manufacturing a bonded structure according to claim 8, wherein the terminal of the LED element is a gold-tin alloy, and the terminal of the substrate is gold. An anisotropic conductive adhesive comprising: a thermosetting adhesive composition containing an epoxy resin and an acid anhydride, and a solder pellet dispersed in the thermosetting adhesive composition; the heat dispersed in the solder pellet The curable adhesive composition is heated at a temperature that does not reach the melting point of the solder pellet. The anisotropic conductive adhesive according to claim 10, wherein the thermally curable adhesive composition has white inorganic particles dispersed therein. The anisotropic conductive adhesive according to claim 11, wherein the white inorganic particles have an average particle diameter of about 0.2 μm to 10 μm, and the white inorganic particles are contained in an amount of about the total amount of the anisotropic conductive adhesive. 1% by volume to 50% by volume; the average particle diameter of the solder particles is about 1 μm to 20 μm, and the content of the solder particles is about 1% by volume to 50% by volume based on the total amount of the anisotropic conductive adhesive; 1.0 equivalent of the epoxy resin contained 0.7 to 1.3 equivalents of the anhydride. An anisotropic conductive adhesive according to claim 12, wherein the epoxy resin contains more than 1.0 equivalent of the acid anhydride with respect to 1.0 equivalent of the epoxy resin.