JP2021082640A - Conductive paste and semiconductor device - Google Patents

Abstract

To provide a conductive paste that can be used as a die attach paste with excellent physical and electrical connection reliability, while suppressing bleed-out of a diluent and preventing dripping and bleeding.SOLUTION: The conductive paste for electronic component adhesion comprises a binder resin, conductive metal powder, alkylacetalized polyvinyl alcohol and a diluent.SELECTED DRAWING: Figure 1

Description

The present invention relates to conductive pastes and semiconductor devices. More specifically, the present invention is manufactured using a conductive paste used as a semiconductor die attach paste used for adhering and fixing a semiconductor element on a support member such as a metal frame, and the conductive paste. Regarding semiconductor devices.

A semiconductor device in which a semiconductor element is mounted on a lead frame and molded with a resin is widely used. For example, a semiconductor element such as an IC or an LSI is mounted on a metal piece such as a lead frame, fixed with a conductive paste called a die attach paste, and then attached to a lead portion of the lead frame and an electrode on the semiconductor element. Are connected by thin wire (bonding wire), and then these are housed in a package to make a semiconductor product. Further, an optical semiconductor device using a light emitting diode (LED) or the like, which has been put into practical use for various displays, is transparent after bonding an optical semiconductor element to a predetermined portion on a lead frame or a resin substrate with a conductive paste or the like. It is manufactured by sealing it with a sealing resin or the like (for example, Patent Document 1).

In the manufacture of semiconductor devices, the die attach paste used for bonding a semiconductor element and a lead frame and improving the electrical conductivity and thermal conductivity between them is generally a resin and electrical conductivity as a filler. It is composed of high-rate particles. If the thixotropic property of the die attach paste is low, a phenomenon called bleed-out occurs in which the resin component contained in the paste exudes to the substrate depending on the surface condition of the lead frame. In order to solve this problem, a technique for blending an additive has been proposed in order to sufficiently develop thixotropic properties. For example, Patent Document 2 proposes a technique of adding silicone rubber fine powder as an additive to suppress the occurrence of resin bleed-out.

Japanese Unexamined Patent Publication No. 2003-273407 Japanese Unexamined Patent Publication No. 5-335353

As described above, the resin paste for die bonding is generally composed of a resin and a filler. In order to ensure coating workability, such a resin paste needs to be made into a paste by adding a diluent to reduce the viscosity, in other words. However, the present inventor has found that since the organic solvent used as a diluent has a low viscosity, the solvent component may wet and spread due to the capillary phenomenon due to the fine irregularities on the surface of the lead frame to be bonded. It was. It was also found that bleeding to an unexpected part in the lead frame causes the solvent to leak to the bottom surface of the lead frame during the process and causes wire bond failure due to contamination.

The present invention has been made in view of such circumstances, and even when a diluent is added to reduce the viscosity, bleed-out of the diluent is suppressed to prevent dripping and bleeding, and physical physics. An object of the present invention is to provide a conductive paste that can be used as a dielectric paste having excellent physical and electrical connection reliability.

The present inventor has found that bleed-out of a diluent can be suppressed by using a specific additive, and has completed the present invention.

According to the present invention
Binder resin and
With conductive metal powder
Diluent and
A conductive paste for adhering electronic components containing alkyl acetalized polyvinyl alcohol is provided.

According to the present invention, there is provided a conductive paste in which bleed-out is suppressed and can be suitably used as a die attach paste having excellent physical and electrical connection reliability.

It is sectional drawing which shows an example of the electronic apparatus which concerns on this embodiment. It is sectional drawing which shows an example of the electronic apparatus which concerns on this embodiment.

Hereinafter, embodiments of the present invention will be described.

(Conductive paste)
The conductive paste of the present embodiment is a die attach paste used for forming a die attach layer for adhering an electronic component such as a semiconductor element to a base material such as a lead frame or a wiring board. The conductive paste of the present embodiment contains a binder resin, a conductive metal powder, a diluent, and an alkyl acetalized polyvinyl alcohol. In the conductive paste of the present embodiment, the binder resin contained therein is cured by heat treatment, whereby the conductive metal powders agglomerate with each other to form a metal powder connecting structure. As a result, the die attach layer obtained by heating the conductive paste exhibits conductivity or thermal conductivity, and adhesion to electronic components and a base material.

By containing the alkyl acetalized polyvinyl alcohol in the conductive paste of the present embodiment, the bleed-out of the diluent is suppressed. Therefore, when this conductive paste is placed on the surface of the lead frame in the manufacture of an electronic device, the diluent does not get wet and spread. Therefore, the connection between the semiconductor element and the substrate has excellent physical and electrical connection reliability.

Each component used in the conductive paste of this embodiment will be described below.

(Binder resin)
A thermosetting resin is used as the binder resin used for the conductive paste of the present embodiment, and a cyanate resin, an epoxy resin, and a radically polymerizable carbon-carbon double bond are contained in one molecule as the thermosetting resin. One or more selected from the resin having two or more and the maleimide resin can be used. Among these, it is particularly preferable to contain an epoxy resin from the viewpoint of improving the adhesiveness of the heat conductive paste.

As the epoxy resin used as the thermosetting resin, a monomer, an oligomer, or a polymer having two or more glycidyl groups in one molecule can be used in general, and the molecular weight and molecular structure thereof are not particularly limited. Examples of the epoxy resin used in the present embodiment include biphenyl type epoxy resin; bisphenol A type epoxy resin, bisphenol F type epoxy resin, tetramethyl bisphenol F type epoxy resin and other bisphenol type epoxy resin; stillben type epoxy resin; phenol novolac. Novolak type epoxy resin such as type epoxy resin and cresol novolac type epoxy resin; polyfunctional epoxy resin such as triphenol methane type epoxy resin and alkyl modified triphenol methane type epoxy resin; phenol aralkyl type epoxy resin having phenylene skeleton, biphenylene skeleton Aralkyl type epoxy resin such as phenol aralkyl type epoxy resin; naphthol type epoxy resin such as dihydroxynaphthalene type epoxy resin and epoxy resin obtained by glycidyl etherification of dimers of dihydroxynaphthalene; triglycidyl isocyanurate, monoallyldi Examples thereof include triazine nuclei-containing epoxy resins such as glycidyl isocyanurate; and bridged cyclic hydrocarbon compound-modified phenol-type epoxy resins such as dicyclopentadiene-modified phenol-type epoxy resins. The epoxy resin includes, for example, bisphenol compounds such as bisphenol A, bisphenol F, and biphenol among compounds containing two or more glycidyl groups in one molecule or derivatives thereof, hydrogenated bisphenol A, hydrogenated bisphenol F, and the like. Diols having an alicyclic structure such as hydrogenated biphenol, cyclohexanediol, cyclohexanedimethanol, cyclohexanediethanol or derivatives thereof, aliphatic diols such as butanediol, hexanediol, octanediol, nonanediol, decanediol or derivatives thereof, etc. It is also possible to use a bifunctional one obtained by epoxidizing the above, a trihydroxyphenylmethane skeleton, or a trifunctional one having an aminophenol skeleton. The epoxy resin as the thermosetting resin can include one or more selected from those exemplified above.

Among these, from the viewpoint of improving the coating workability and adhesiveness of the obtained conductive paste, it is more preferable to contain a bisphenol type epoxy resin, and it is particularly preferable to contain a bisphenol F type epoxy resin. Further, in the present embodiment, from the viewpoint of more effectively improving the coating workability of the conductive paste, it is more preferable to contain a liquid epoxy resin that is liquid at room temperature (25 ° C.).

The cyanate resin used as the thermosetting resin is not particularly limited, and is, for example, 1,3-disyanatobenzene, 1,4-disyanatobenzene, 1,3,5-tricyanatobenzene, 1,3-disianatonaphthalene. , 1,4-Cyanate naphthalene, 1,6-disiana tonaphthalene, 1,8-disiana tonaphthalene, 2,6-disiana tonaphthalene, 2,7-disiana tonaphthalene, 1,3,6-trisiana tonaphthalene , 4,4'-disyanatobiphenyl, bis (4-cyanatophenyl) methane, bis (3,5-dimethyl-4-cyanatophenyl) methane, 2,2-bis (4-cyanatophenyl) propane, 2,2-Bis (3,5-dibromo-4-cyanatophenyl) propane, bis (4-cyanatophenyl) ether, bis (4-cyanatophenyl) thioether, bis (4-cyanatophenyl) sulfone, Triquantize tris (4-cyanatophenyl) phosphite, tris (4-cyanatophenyl) phosphate, cyanates obtained by the reaction of novolak resin with cyanate halide, and cyanate groups of these polyfunctional cyanate resins. It can include one or more selected from prepolymers having a triazine ring formed thereby. The prepolymer is obtained by polymerizing the polyfunctional cyanate resin monomer using, for example, an acid such as mineral acid or Lewis acid, a base such as sodium alcoholate or tertiary amines, or a salt such as sodium carbonate as a catalyst. be able to.

As a resin having two or more radical-polymerizable carbon-carbon double bonds in one molecule used as a thermosetting resin, for example, a radical-polymerizable acrylic resin having two or more (meth) acryloyl groups in the molecule. Can be used. In the present embodiment, the acrylic resin may include a polyether, polyester, polycarbonate, or poly (meth) acrylate having a molecular weight of 500 to 10000 and having a (meth) acrylic group. When a resin having two or more radically polymerizable carbon-carbon double bonds in one molecule is used as the thermosetting resin, the thermally conductive paste contains, for example, a polymerization initiator such as a thermal radical polymerization initiator. be able to.

The maleimide resin used as the thermosetting resin is not particularly limited, and is, for example, N, N'-(4,4'-diphenylmethane) bismaleimide, bis (3-ethyl-5-methyl-4-maleimidephenyl) methane, and the like. 2,2-Bis [4- (4-maleimidephenoxy) phenyl] One or more selected from bismaleimide resins such as propane can be included.

The thermosetting resin can include an epoxy resin having a biphenyl skeleton (biphenyl type epoxy resin) as a resin having a biphenyl skeleton. Thereby, the metal adhesion of the conductive paste can be improved.

The structure of an epoxy resin having a biphenyl skeleton is not particularly limited as long as it has a biphenyl skeleton in its molecular structure and has two or more epoxy groups, but for example, biphenol or a derivative thereof. Examples thereof include a bifunctional epoxy resin treated with epichlorohydrin, a phenol aralkyl type epoxy resin having a biphenylene skeleton, and a naphthol aralkyl type epoxy resin having a biphenylene skeleton, which may be used alone or in combination. There is no problem. Among these, those having two epoxy groups in the molecule are particularly preferable because they have excellent heat resistance. Examples of such epoxy resins include biphenyl epoxy resins obtained by treating biphenol derivatives with epichlorohydrin, such as biphenyl type epoxy resins and tetramethylbiphenyl type epoxy resins; among phenol aralkyl type epoxy resins having a biphenylene skeleton, epoxys. Those having two groups (sometimes expressed as having two phenol nuclei); those having two epoxy groups among naphthol aralkyl type resins having a biphenylene skeleton; and the like can be mentioned.

In the conductive paste of the present embodiment, the lower limit of the content of the binder resin is, for example, 1% by mass or more, preferably 3% by mass or more, and more preferably 5% by mass with respect to the entire conductive paste. % Or more. Thereby, the handleability of the conductive paste can be improved. In addition, the viscosity of the conductive paste can be adjusted to an appropriate level for use. The upper limit of the content of the binder resin is, for example, 15% by mass or less, preferably 12% by mass or less, and more preferably 10% by mass or less with respect to the entire conductive paste. This makes it possible to improve the balance of various properties such as the conductivity of the conductive paste and the adhesion to the substrate.

(Hardener)
The conductive paste of this embodiment may contain a curing agent. Thereby, the curability of the conductive paste can be improved. As the curing agent, for example, one or more selected from aliphatic amines, aromatic amines, dicyandiamides, dihydrazide compounds, acid anhydrides, and phenol compounds can be used. Among these, it is particularly preferable to contain at least one of dicyandiamide and a phenol compound from the viewpoint of improving production stability.

Examples of the dihydrazide compound used as a curing agent include carboxylic acid dihydrazides such as adipic acid dihydrazide, dodecanoic acid dihydrazide, isophthalic acid dihydrazide, and p-oxybenzoic acid dihydrazide. The acid anhydride used as a curing agent includes phthalic anhydride, tetrahydrophthalic anhydride, hexahydrophthalic anhydride, endomethylenetetrahydrophthalic anhydride, dodecenyl succinic anhydride, maleic anhydride and polybutadiene reaction, and anhydride. Examples thereof include a copolymer of maleic anhydride and styrene.

The phenol compound used as a curing agent is a compound having two or more phenolic hydroxyl groups in one molecule. A more preferable number of phenolic hydroxyl groups in one molecule is 2 to 5, and a particularly preferable number of phenolic hydroxyl groups in one molecule is two or three. As a result, the coating workability of the conductive paste can be improved more effectively, and a crosslinked structure can be formed at the time of curing to improve the cured product characteristics of the conductive paste. The phenol compounds include, for example, bisphenol F, bisphenol A, bisphenol S, tetramethyl bisphenol A, tetramethyl bisphenol F, tetramethyl bisphenol S, dihydroxydiphenyl ether, dihydroxybenzophenone, tetramethyl biphenol, etylidene bisphenol, methyl etylidenebis (methylphenol). , Cyclohexylidene bisphenols, bisphenols such as biphenols and their derivatives, trifunctional phenols such as tri (hydroxyphenyl) methane, tri (hydroxyphenyl) ethane and their derivatives, phenols such as phenol novolac and cresol novolac. A compound obtained by reacting with formaldehyde, which is mainly dinuclear or trinuclear, may contain one or more selected from derivatives thereof. Among these, it is more preferable to contain bisphenols, and it is particularly preferable to contain bisphenol F.

Further, in the present embodiment, as the resin having a biphenyl skeleton as a curing agent, a phenol resin (phenol compound) having a biphenyl skeleton can be used. Thereby, the conductivity of the conductive paste and the adhesion to the base material can be improved. The structure of the phenol resin having a biphenyl skeleton is not particularly limited as long as it has a biphenyl skeleton in its molecular structure and has two or more phenol groups.

In the present embodiment, the content of the curing agent in the conductive paste is preferably 0.5% by mass or more, more preferably 1.0% by mass or more, based on the entire heat conductive paste. Thereby, the curability of the conductive paste can be improved more effectively. On the other hand, the content of the curing agent in the conductive paste is preferably 10% by mass or less, more preferably 7% by mass or less, based on the entire conductive paste. Thereby, the low thermal expansion property and the moisture resistance of the adhesive layer formed by using the conductive paste can be improved.

(Conductive metal powder)
The conductive metal powder contained in the conductive paste of the present embodiment aggregates to form a metal particle connecting structure by subjecting the conductive paste to heat treatment. That is, in the die attach paste layer obtained by heating the conductive paste, the metal powders are agglomerated with each other. As a result, conductivity, thermal conductivity, and adhesion to the substrate are exhibited.

As the conductive metal powder used in the conductive paste of the present embodiment, silver powder, gold powder, platinum powder, palladium powder, copper powder, nickel powder, or alloys thereof can be used. It is preferable to use silver powder from the viewpoint of conductivity and ease of handling.

The shape of the conductive metal powder is not particularly limited, and examples thereof include a spherical shape, a flake shape, and a scaly shape. In the present embodiment, it is more preferable that the conductive metal powder contains spherical particles. Thereby, the uniformity of aggregation of the conductive metal powder can be improved. Further, from the viewpoint of reducing the cost, an embodiment in which the conductive metal powder contains flake-like particles can also be adopted. Furthermore, the conductive metal powder may contain both spherical particles and flake-like particles from the viewpoint of reducing the cost and improving the balance of agglutination uniformity.

The average particle size (D ₅₀ ) of the conductive metal powder is, for example, 0.1 μm or more and 10 μm or less. When the average particle size of the conductive metal powder is at least the above lower limit value, it is possible to suppress an excessive increase in the specific surface area and suppress a decrease in thermal conductivity due to contact thermal resistance. Further, when the average particle size of the conductive metal powder is not more than the above upper limit value, it is possible to improve the formability of the metal particle connecting structure between the conductive metal powders. Further, from the viewpoint of improving the dispensability of the conductive paste, the average particle size (D ₅₀ ) of the conductive metal powder is more preferably 0.6 μm or more and 2.7 μm or less, and 0.6 μm or more and 2.0 μm or more. The following is particularly preferable. The average particle size (D ₅₀ ) of the conductive metal powder can be measured using, for example, a commercially available laser particle size distribution meter (for example, manufactured by Shimadzu Corporation, SALD-7000, etc.).

The maximum particle size of the conductive metal powder is not particularly limited, but can be, for example, 1 μm or more and 50 μm or less, more preferably 3 μm or more and 30 μm or less, and particularly preferably 4 μm or more and 18 μm or less. This makes it possible to more effectively improve the balance between the uniformity of aggregation of the conductive metal powder and the dispensability.

The content of the conductive metal powder in the conductive paste is, for example, preferably 30% by mass or more and 80% by mass or less, and more preferably 40% by mass or more and 80% by mass or less with respect to the entire conductive paste. .. By setting the value to the above lower limit or more, it is possible to contribute to the improvement of the thermal conductivity and the conductivity of the die attach paste layer obtained by heat-treating the conductive paste. On the other hand, when the value is not more than the above upper limit, it is possible to contribute to the improvement of the coating workability of the obtained conductive paste and the mechanical strength of the die attach paste layer obtained by heat-treating the conductive paste.

(Diluent)
In the conductive paste of the present embodiment, a diluent is blended in order to make the conductive paste have an appropriate viscosity in consideration of the coatability to the semiconductor element or the base material and the filling property to the details. As the diluent, a reactive diluent or a non-reactive solvent can be used. Here, the reactive diluent means a compound having a reactive group involved in the cross-linking reaction of the binder resin contained in the conductive paste, and the non-reactive solvent means a reaction involved in the cross-linking reaction of the binder resin. It means a solvent that does not have a reactive group.

Examples of the reactive diluent used as the diluent include glycol monomers, acrylic monomers, epoxy monomers, maleimide monomers and the like.

Examples of the glycol monomer used as the reactive diluent include ethylene glycol, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol mono n-propyl ether, ethylene glycol monoisopropyl ether, ethylene glycol mono n-butyl ether, and ethylene. Glycol monoisobutyl ether, ethylene glycol monohexyl ether, ethylene glycol mono2-ethylhexyl ether, ethylene glycol monoallyl ether, ethylene glycol monophenyl ether, ethylene glycol monobenzyl ether, diethylene glycol, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol mono n-propyl ether, diethylene glycol monoisopropyl ether, diethylene glycol mono n-butyl ether, diethylene glycol monoisobutyl ether, diethylene glycol monohexyl ether, diethylene glycol mono2-ethylhexyl ether, diethylene glycol monobenzyl ether, triethylene glycol, triethylene glycol monomethyl ether, triethylene Glycol monoethyl ether, triethylene glycol mono n-butyl ether, tetraethylene glycol, tetratylene glycol monomethyl, tetratylene glycol monoethyl, tetraethylene glycol mono n-butyl, propylene glycol, propylene glycol monomethyl ether, propylene glycol monoethyl ether, Ethylene glycol mono n-propyl ether, propylene glycol monoisopropyl ether, propylene glycol mono n-butyl ether, propylene glycol monophenyl ether, dipropylene glycol, dipropylene glycol monomethyl ether, dipropylene glycol monoethyl ether, dipropylene glycol mono n- Examples thereof include propyl ether, dipropylene glycol mono-n-butyl ether, tripropylene glycol, tripropylene glycol monomethyl ether, tripropylene glycol monoethyl ether and tripropylene glycol mono n-butyl ether. These may be used individually by 1 type, and may be used in combination of 2 or more type.

When the conductive paste is heat-treated, the metal powders contained therein agglomerate to form a metal particle connecting structure, and the glycol monomer is tripropylene glycol mono-n-butyl ether or ethylene glycol mono-n. -It is preferable to use butyl acetate.

As the acrylic monomer used as the reactive diluent, a monofunctional acrylic monomer having only one (meth) acrylic group or a polyfunctional acrylic monomer having two or more (meth) acrylic groups can be used.

Examples of the monofunctional acrylic monomer include 2-phenoxyethyl (meth) acrylate, ethyl (meth) acrylate, n-butyl (meth) acrylate, isobutyl (meth) acrylate, tert-butyl (meth) acrylate, and isoamyl (meth). Acrylate, 2-ethylhexyl (meth) acrylate, isodecyl (meth) acrylate, n-lauryl (meth) acrylate, n-tridecyl (meth) acrylate, n-stearyl (meth) acrylate, isostearyl (meth) acrylate, ethoxydiethylene glycol ( Meta) acrylate, butoxydiethylene glycol (meth) acrylate, methoxytriethylene glycol (meth) acrylate, 2-ethylhexyldiethylene glycol (meth) acrylate, methoxypolyethylene glycol (meth) acrylate, methoxydipropylene glycol (meth) acrylate, cyclohexyl (meth) ) Acrylate, tetrahydrofurfuryl (meth) acrylate, benzyl (meth) acrylate, phenoxyethyl (meth) acrylate, phenoxydiethylene glycol (meth) acrylate, phenoxypolyethylene glycol (meth) acrylate, nonylphenolethylene oxide modified (meth) acrylate, phenylphenolethylene oxide Modified (meth) acrylate, isobornyl (meth) acrylate, dimethylaminoethyl (meth) acrylate, diethylaminoethyl (meth) acrylate, dimethylaminoethyl (meth) acrylate quaternized product, glycidyl (meth) acrylate, neopentyl glycol (meth) Acrylic acid benzoic acid ester, 1,4-cyclohexanedimethanol mono (meth) acrylate, 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate, 2-hydroxy- 3-Phenoxypropyl (meth) acrylate, 2- (meth) acryloylxyethyl succinic acid, 2- (meth) acryloyloxyethyl succinic acid, 2- (meth) acryloyloxyethyl hexahydrophthalic acid, 2- (meth) acryloyl Oxyethylphthalic acid, 2- (meth) acryloyloxyethyl-2-hydroxyethylphthalic acid, 2- (meth) acryloyloxyethyl acid phosphate, and 2- (meth) acrylate. Loxyethyl acid phosphate and the like can be mentioned. As the monofunctional acrylic monomer, one or a combination of two or more of the above specific examples can be used.

Of the above specific examples, 2-phenoxyethyl methacrylate is preferably used as the monofunctional acrylic monomer. Thereby, the adhesion of the obtained conductive paste to the base material can be improved.

Specific examples of the polyfunctional acrylic monomer include ethylene glycol di (meth) acrylate, trimethylpropantri (meth) acryloyl, propoxylated bisphenol A di (meth) acrylate, and hexane-1,6-diol bis (2-methyl). (Meta) acrylate), 4,4'-isopropyridene diphenol di (meth) acrylate, 1,3-butanediol di (meth) acrylate, 1,6-bis ((meth) acryloyloxy) -2,2 3,3,4,5,5-octafluorohexane, 1,4-bis ((meth) acryloyloxy) butane, 1,6-bis ((meth) acryloyloxy) hexane, triethylene glycol di (meth) ) Acrylate, neopentyl glycol di (meth) acrylate, neopentyl glycol di (meth) acrylate, N, N'-di (meth) acryloyl ethylenediamine, N, N'-(1,2-dihydroxyethylene) bis (meth) Acrylamide, 1,4-bis ((meth) acryloyl) piperazine and the like can be mentioned.

As the epoxy monomer used as the reactive diluent, a monofunctional epoxy monomer having only one epoxy group or a polyfunctional epoxy monomer having two or more epoxy groups can be used.

Examples of the monofunctional epoxy monomer include 4-tert-butylphenylglycidyl ether, m, p-cresyl glycidyl ether, phenylglycidyl ether, and cresyl glycidyl ether. As the monofunctional epoxy monomer, one or a combination of two or more of the above specific examples can be used.

Examples of the polyfunctional epoxy monomer include bisphenol compounds such as bisphenol A, bisphenol F and biphenol or derivatives thereof; hydrogenated bisphenol A, hydrogenated bisphenol F, hydrogenated biphenol, cyclohexanediol, cyclohexanedimethanol, sidilohexanediethanol and the like. Diores having an alicyclic structure or derivatives thereof; bifunctional diols obtained by epoxidizing aliphatic diols such as butanediol, hexanediol, octanediol, nonanediol, decanediol or derivatives thereof; trihydroxyphenylmethane skeleton, Trifunctional ones having an aminophenol skeleton; polyfunctional ones obtained by epoxidizing phenol novolac resin, cresol novolac resin, phenol aralkyl resin, biphenyl aralkyl resin, naphthol aralkyl resin and the like can be mentioned. As the polyfunctional epoxy monomer, one or a combination of two or more of the above specific examples can be used.

Examples of the maleimide monomer used as the reactive diluent include polytetramethylene ether glycol-di (2-maleimide acetate).

In the present embodiment, the content of the reactive diluent in the conductive paste is preferably 3% by mass or more, more preferably 4% by mass or more, based on the entire conductive paste. Thereby, the coating workability of the conductive paste and the flatness of the obtained adhesive layer can be improved more effectively. On the other hand, the content of the reactive diluent in the conductive paste is preferably 20% by mass or less, more preferably 15% by mass or less, based on the entire conductive paste. As a result, it is possible to suppress the occurrence of dripping during the coating work and improve the coating workability. It is also possible to improve the curability of the conductive paste.

The conductive paste of this embodiment may contain a non-reactive solvent. By containing the non-reactive solvent, the fluidity of the obtained conductive paste can be adjusted, and the handleability and workability can be improved. Non-reactive solvents include ethyl alcohol, propyl alcohol, butyl alcohol, pentyl alcohol, hexyl alcohol, heptyl alcohol, octyl alcohol, nonyl alcohol, decyl alcohol, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, and ethylene glycol monopropyl ether. , Ethylene glycol monobutyl ether, propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol monopropyl ether, propylene glycol monobutyl ether, methyl methoxybutanol, α-turpineol, β-turpineol, hexylene glycol, benzyl alcohol, 2-phenyl Alcohols such as ethyl alcohol, isopalmityl alcohol, isostearyl alcohol, lauryl alcohol, ethylene glycol, propylene glycol or glycerin; acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, diacetone alcohol (4-hydroxy-4-methyl-2) Ketones such as −pentanone), 2-octanone, isophorone (3,5,5-trimethyl-2-cyclohexene-1-one) or diisobutylketone (2,6-dimethyl-4-heptanone); ethyl acetate, butyl acetate , Diethyl phthalate, dibutyl phthalate, acetoxietan, methyl butyrate, methyl hexanoate, methyl octanate, methyl decanoate, methyl cellosolve acetate, ethylene glycol monobutyl ether acetate, propylene glycol monomethyl ether acetate, 1,2-diacetoxietan, phosphorus Esters such as tributyl acid, tricresyl phosphate or tripentyl phosphate; tetrahydrofuran, dipropyl ether, ethylene glycol dimethyl ether, ethylene glycol diethyl ether, ethylene glycol dibutyl ether, propylene glycol dimethyl ether, ethoxyethyl ether, 1,2-bis (2) Ethers such as −diethoxy) ethane or 1,2-bis (2-methoxyethoxy) ethane; ester ethers such as 2- (2butoxyethoxy) ethane acetate; ether alcohols such as 2- (2-methoxyethoxy) ethanol Kind: toluene, xylene, n-paraffin, isoparaffin, dodecylbenzene, terepine oil, kerosine Hydrocarbons such as light oil; nitriles such as acetonitrile or propionitrile; amides such as acetamide or N, N-dimethylformamide; low molecular weight volatile silicone oil, volatile organic modified silicone oil, etc. Be done.

The conductive paste of this embodiment does not have to contain a non-reactive solvent. Here, the fact that the non-reactive solvent is not contained means that the non-reactive solvent is substantially not contained, and refers to the case where the content of the non-reactive solvent in the entire conductive paste is 0.1% by mass or less.

(Alkyl acetalized polyvinyl alcohol)
The conductive paste of this embodiment contains an alkyl acetalized polyvinyl alcohol. This makes it possible to suppress the occurrence of bleeding, which is a phenomenon in which the above-mentioned diluent gets wet and spreads on the substrate.

The alkyl acetalized polyvinyl alcohol used in the conductive paste of the present embodiment is an alkyl acetalized polyvinyl alcohol synthesized by an acetalization reaction of polyvinyl alcohol and an aldehyde. Alkyl acetalized polyvinyl alcohol is a vinyl alcohol unit (formula (I)), a vinyl ester unit (formula (II)) and a vinyl acetal unit (a structure in which two vinyl alcohol units are acetalized with an aldehyde, formula (III). ) Is a resin. In the formula below, l is the molar ratio of vinyl alcohol units, m is the molar ratio of vinyl ester units, k / 2 is the molar ratio of vinyl acetal units, and k is the vinyl alcohol acetalized with aldehyde. It is a molar ratio of units, Ra is Ra in the aldehyde (Ra-CHO) used for acetalization, and Ra is an alkyl group having 1 to 10 carbon atoms. Rb is Rb in vinyl ester (RbCOOCH = CH2), and Rb is an alkyl group having 1 to 6 carbon atoms. However, l and / or m may be zero. When the poalkyl acetalized polyvinyl alcohol consists of only vinyl alcohol units, vinyl ester units and vinyl acetal units, k + l + m = 1. The arrangement order of each unit is not limited, and it may be arranged randomly, in a block shape, or in a tapered shape. Further, the bond between the repeating units may be Head-to-Tail or Head-to-Head.

Alkyl acetalized polyvinyl alcohol is obtained by alkyl acetalizing polyvinyl alcohol with an aldehyde.

Here, as the vinyl ester monomer for forming the vinyl ester unit represented by the formula (II), vinyl formate, vinyl acetate, vinyl propionate, vinyl valerate, vinyl caprate, vinyl laurate, stearer. Examples thereof include vinyl acetate, vinyl benzoate, vinyl pivalate, vinyl versatic acid and the like. Among these, vinyl acetate is preferable because of its availability. From the same viewpoint, the alkyl acetalized polyvinyl alcohol preferably contains a methyl group in its molecular structure, and more preferably Rb in the above general formula (II) is a methyl group.

Aldehydes used for alkylacetalizing polyvinyl alcohol include acetaldehyde (including paraacetaldehyde), propionaldehyde, glioxal, butylaldehyde, n-octylaldehyde, amylaldehyde, hexylaldehyde, heptylaldehyde, 2-ethylhexylaldehyde, Cyclohexylaldehyde, furfural, glutaaldehyde, benzaldehyde, 2-methylbenzaldehyde, 3-methylbenzaldehyde, 4-methylbenzaldehyde, p-hydroxybenzaldehyde, m-hydroxybenzaldehyde, phenylacetaldehyde, β-phenylpropionaldehyde and the like can be mentioned. Of these, butyraldehyde is particularly preferable from the viewpoint of ease of production. From the same viewpoint, the alkyl acetalized polyvinyl alcohol preferably contains a butyl group in the molecular structure, and more preferably Ra in the above general formula (III) is a butyl group.

The weight average molecular weight alkyl acetalized polyvinyl alcohol is, for example, 15 × 10 ⁴ or less 6 × 10 ⁴ or more, or preferably 12 × 10 ⁴ or less 8 × 10 ⁴ or more.

Examples of commercially available alkyl acetalized polyvinyl alcohol include Eslek (manufactured by Sekisui Chemical Co., Ltd.), and various grades can be obtained from the market. More specifically, examples thereof include, but are not limited to, Eslek BH-3, Eslek BX-6, Eslek KS-1, Eslek KS-10, and Eslek KS-3.

In the conductive paste of the present embodiment, the blending amount of the alkyl acetalized polyvinyl alcohol is, for example, 0.5% by mass or more and 1.5% by mass or less, preferably 0.8, based on the entire conductive paste. It is 1% by mass or more and 1.2% by mass or less. By blending an alkyl acetalized polyvinyl alcohol in an amount in the above range, the occurrence of bleeding can be effectively suppressed.

(Other ingredients)
The conductive paste of the present embodiment may contain, if necessary, various additional components commonly used in the art, in addition to the components described above. Further, examples thereof include, but are not limited to, a silane coupling agent, a curing accelerator, a radical polymerization initiator, a low stress agent, an inorganic filler, and the like, and can be selected according to desired performance.

Silane coupling agents are used to improve the adhesion between the conductive paste and the substrate. Examples of the silane coupling agent include vinyl silanes such as vinyl trimethoxysilane and vinyl triethoxysilane; 2- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, 3-glycidyloxypropyltrimethoxysilane, and 3-glycid. Epoxysilanes such as xypropylmethyldimethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, 3-glycidoxypropyltriethoxysilane; styryl such as p-styryltrimethoxysilane Silane; methacrylsilanes such as 3-methacryloxypropylmethyldimethoxysilane, 3-methacryloxypropyltrimethoxysilane, 3-methacryloxypropylmethyldiethoxysilane, 3-methacryloxypropyltriethoxysilane; 3- (trimethoxymethacrylate) Acrylic silanes such as silyl) propyl and 3-acryloxypropyltrimethoxysilane; N-2- (aminoethyl) -3-aminopropylmethyldimethoxysilane, N-2- (aminoethyl) -3-aminopropyltrimethoxysilane , 3-Aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3-triethoxysilyl-N- (1,3-dimethyl-butylidene) propylamine, N-phenyl-γ-aminopropyltrimethoxysilane, etc. Aminosilane; isocyanuratesilane; alkylsilane; ureidosilane such as 3-ureidopropyltrialkoxysilane; mercaptosilane such as 3-mercaptopropylmethyldimethoxysilane, 3-mercaptopropyltrimethoxysilane; Examples thereof include isocyanate silane.

The curing accelerator is used to accelerate the reaction between the epoxy monomer used as the reactive diluent or the epoxy resin used as the binder resin and the curing agent. Examples of the curing accelerator include phosphorus atom-containing compounds such as organic phosphine, tetra-substituted phosphonium compound, phosphobetaine compound, adduct of phosphine compound and quinone compound, adduct of phosphonium compound and silane compound; dicyandiamide, 1, Examples thereof include amidines and tertiary amines such as 8-diazabicyclo [5.4.0] undecene-7 and benzyldimethylamine; and nitrogen atom-containing compounds such as the amidine or the quaternary ammonium salt of the tertiary amine.

Specifically, as the radical polymerization initiator, an azo compound, a peroxide, or the like can be used.

As the low stress agent, for example, a silicone compound such as silicone oil or silicone rubber; a polybutadiene compound such as a polybutadiene maleic anhydride adduct; an acrylonitrile butadiene copolymer compound or the like can be used.

Examples of the inorganic filler include fused silica such as molten crushed silica and fused spherical silica; silica such as crystalline silica and amorphous silica; silicon dioxide; alumina; aluminum hydroxide; silicon nitride; and aluminum nitride.

(Preparation of conductive paste)
The method for preparing the conductivity is not particularly limited, but for example, a paste-like composition can be obtained by premixing each of the above-mentioned components, kneading with three rolls, and further vacuum defoaming. it can. At this time, the long-term workability of the conductive paste can be improved by appropriately adjusting the preparation conditions, for example, premixing under reduced pressure.

The viscosity of the conductive paste of this embodiment can be adjusted according to the application. The viscosity of the conductive paste can be controlled by adjusting the type of binder resin used, the type of diluent, the blending amount thereof, and the like. The lower limit of the viscosity of the conductive paste of this embodiment is
For example, it is 10 Pa · s or more, preferably 20 Pa · s or more, and more preferably 30 Pa · s or more. Thereby, the workability of the conductive paste can be improved. On the other hand, the upper limit of the viscosity of the conductive paste is, for example, 1 × 10 ³ Pa · s or less, preferably 5 × 10 ² Pa · s or less, and more preferably 2 × 10 ² Pa · s or less. Is. Thereby, the coatability can be improved.

(Use)
The use of the conductive paste of this embodiment will be described.
The conductive paste according to this embodiment is used, for example, for adhering a substrate and a semiconductor element. Here, examples of the semiconductor element include a semiconductor package and an LED.
The conductive paste according to the present embodiment can improve connection reliability and appearance as compared with the conventional paste-like adhesive composition. As a result, a semiconductor element having a large calorific value can be suitably used for mounting on a substrate. In the present embodiment, the LED means a light emitting diode (Light Emitting Diode).

Specific examples of the semiconductor device using the LED include a bullet type LED, a surface mount device (SMD) LED, a COB (Chip On Board), and a Power LED.

Specifically, the types of the semiconductor packages include a CMOS image sensor, a hollow package, a MAP (Mold Array Package), a QFP (Quad Flat Package), a SOP (Small Outline Package), and a CSP (Chip Size Package). QFN (Quad Flat Non-read Package), SON (Small Outline Non-read Package), BGA (Ball Grid Array), LF-BGA (Lead Frame BGA), FC-BGA (FlipBGA) Types such as Array Process BGA), eWLB (Embedded Waver-Level BGA), Fan-In type eWLB, and Fan-Out type eWLB can be mentioned.

An example of a semiconductor device using the paste-like adhesive composition according to the present embodiment will be described below.
FIG. 1 is a cross-sectional view showing an example of a semiconductor device according to the present embodiment.
The semiconductor device 100 according to the present embodiment includes a base material 30 and a semiconductor element 20 mounted on the base material 30 via an adhesive layer 10 which is a cured product of a conductive paste. The semiconductor element 20 and the base material 30 are electrically connected via, for example, a bonding wire 40 or the like. Further, the semiconductor element 20 is sealed with, for example, a sealing resin 50.

Here, the lower limit of the thickness of the adhesive layer 10 is preferably, for example, 5 μm or more, and more preferably 10 μm or more. As a result, the heat capacity of the cured product of the conductive paste can be improved, and the heat dissipation can be improved. The upper limit of the thickness of the adhesive layer 10 is, for example, preferably 50 μm or less, and more preferably 30 μm or less. As a result, the conductive paste can exhibit suitable adhesion while improving heat dissipation.

In FIG. 1, the base material 30 is, for example, a lead frame. In this case, the semiconductor element 20 is mounted on the die pad 32 or the base material 30 via the adhesive layer 10. Further, the semiconductor element 20 is electrically connected to the outer lead 34 (base material 30) via, for example, a bonding wire 40. The base material 30 which is a lead frame is composed of, for example, 42 alloys and a Cu frame.

The base material 30 may be an organic substrate or a ceramic substrate. The organic substrate is preferably composed of, for example, an epoxy resin, a cyanate resin, a maleimide resin, or the like. The surface of the base material 30 may be coated with a metal such as silver or gold. Thereby, the adhesiveness between the adhesive layer 10 and the base material 30 can be improved.

FIG. 2 is a modification of FIG. 1 and is a cross-sectional view showing an example of the semiconductor device 100 according to the present embodiment. In the semiconductor device 100 according to this modification, the base material 30 is, for example, an interposer. Of the base material 30 that is an interposer, for example, a plurality of solder balls 52 are formed on the other surface on the opposite side to the one on which the semiconductor element 20 is mounted. In this case, the semiconductor device 100 is connected to another wiring board via the solder balls 52.

(Manufacturing method of semiconductor device)
An example of a method for manufacturing a semiconductor device according to the present embodiment will be described.
First, the conductive paste is applied on the base material 30, and then the semiconductor element 20 is arranged on the conductive paste. That is, the base material 30, the paste-like adhesive composition, and the semiconductor element 20 are laminated in this order. The method for applying the conductive paste is not limited, but specifically, a dispensing method, a printing method, an inkjet method, or the like can be used.

Then, the conductive paste is pre-cured and then post-cured to cure the conductive paste. By heat treatment such as pre-curing and post-curing, silver particles in the conductive paste are aggregated, and a heat conductive layer in which the interface between the plurality of silver particles disappears is formed in the adhesive layer 10. As a result, the base material 30 and the semiconductor element 20 are adhered to each other via the adhesive layer 10. Next, the semiconductor element 20 and the base material 30 are electrically connected using the bonding wire 40. Next, the semiconductor element 20 is sealed with the sealing resin 50. This makes it possible to manufacture a semiconductor device.

Although the embodiments of the present invention have been described above, these are examples of the present invention, and various configurations other than the above can be adopted.

Hereinafter, the present invention will be described with reference to Examples and Comparative Examples, but the present invention is not limited thereto.

The components used in Examples and Comparative Examples are shown below.
(Binder resin)
-Epoxy resin 1: Bisphenol-F-diglycidyl ether (manufactured by Nippon Kayaku Co., Ltd., RE-303SL, epoxy equivalent 160 g / eq)
(Diluent)
-Epoxy monomer 1: Mixture of m-glycidyl ether and p-glycidyl ether (manufactured by Sakamoto Yakuhin Kogyo Co., Ltd., m, p-CGE, Mw = 165, epoxy equivalent 165 g / eq)
(Alkyl acetalized polyvinyl alcohol)
-Polyvinyl butyral resin 1: Sekisui Chemical Co., Ltd., Eslek BH-3 (used as a 10% butyl carbitol solution)
(Coupling agent)
-Coupling agent 1: 3-glycidyloxypropyltrimethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd., KBM-403E)
(Hardener)
-Hardener 1: Phenolic novolak resin (hydroxyl equivalent 105, manufactured by Sumitomo Bakelite Co., Ltd., PR-51470)
-Hardener 2: Dicyanamide (ADEKA, EH-3636AS)
(Curing accelerator)
-Curing accelerator 1: Tetraphenylphosphonium / tetraphenyl borate (manufactured by Hokuko Chemical Industry Co., Ltd., TPP-K)
(solvent)
-Solvent 1: Tripropylene glycol mono n-butyl ether Solvent name (Nippon Embroidery Co., Ltd., BFTG)
(Conductive metal powder)
-Silver powder 1: Flaky silver powder (average particle size: 5.0 μm, manufactured by Tokuriki Chemical Co., Ltd., TKR-4A)
(silica)
-Silica 1: Spherical silica (manufactured by Tokuyama Corporation, UF-320)

(Examples 1 to 5, Comparative Example 1)
<Preparation of paste-like adhesive composition>
First, a varnish-like mixture was prepared by kneading the components in the blending amounts shown in "Varnish Composition" in Table 1 at room temperature with a three-roll mill. Next, the obtained varnish-like mixture was used in the blending amount shown in "Paste Composition" in Table 1, and silver powder and silica were mixed and kneaded at room temperature with a three-roll mill to obtain a paste-like composition (paste composition). Conductive paste) was obtained.

The conductive pastes of each Example and each Comparative Example were evaluated for the following items.
<Presence or absence of bleeding after hitting the conductive paste>
The conductive pastes of each example and comparative example were applied onto a silver lead frame activated by argon treatment (200 w, 180 sec), and the wet spread of the paste at the moment of application was measured with a metallurgical microscope (U-PMTVC, OLYNPUS). ) Was used for observation.
Immediately after the paste is applied, it spreads wet and becomes circular, and when observed with a metallurgical microscope, it appears as a circular object that does not transmit light. The diameter of the circular object through which this light is not transmitted was defined as A0. After 1 hour has passed since the paste was applied, the paste that wets and spreads immediately after application appears as a circular object that is semi-transparent to light under a metallurgical microscope. The diameter of the circular object through which this light was semi-transmitted was defined as A1. The larger A1 is than A0, the more wet and spread (bleed) the paste is.
Table 1 shows the results as "○" if A1 / A0 is 1, "Δ" if A1 / A0 is greater than 1 and 1.1 or less, and "x" if A1 / A0 is greater than 1.1. Shown.

<Adhesive strength>
The conductive paste obtained above is applied onto a silver lead frame, and then a silver-plated silicon chip of length 2.0 mm × width 2.0 mm × thickness 350 ± 5 μm is placed on this conductive paste. Then, the temperature was raised from 25 ° C. to 150 ° C. over 30 minutes, and further heat-treated at 150 ° C. for 2 hours to obtain a cured product, which was used as a test piece. For this test piece, the die shear strength of the silver lead frame and the silicon chip at 150 ° C. was measured. The results are shown in Table 1. When the die shear strength is 52.0 N / (2 mm × 2 mm) or more, it can be considered that it is sufficient to secure the operation reliability of the semiconductor device when the semiconductor device is manufactured.

The conductive paste of the example showed almost or no bleeding, and showed excellent adhesive strength when used for adhesion between the lead frame and the silicon chip.

100 Semiconductor device 10 Adhesive layer 20 Semiconductor element 30 Base material 32 Die pad 34 Outer lead 40 Bonding wire 50 Encapsulating resin 52 Solder ball

Claims (9)

Binder resin and
With conductive metal powder
Alkyl acetalized polyvinyl alcohol and
Diluent and
Conductive paste for bonding electronic components, including. The conductive paste according to claim 1, wherein the binder resin contains a thermosetting epoxy resin. The conductive paste according to claim 1 or 2, further comprising a curing agent. The conductive paste according to any one of claims 1 to 3, wherein the diluent comprises at least one selected from a glycol monomer, an acrylic monomer, an epoxy monomer, and a maleimide monomer. The conductivity according to any one of claims 1 to 4, wherein the conductive metal powder comprises at least one selected from silver powder, gold powder, platinum powder, palladium powder, copper powder, and nickel powder, and alloys thereof. Sex paste. The conductive paste according to claim 1 to 5, wherein the conductive metal powder is in an amount of 30% by mass or more and 80% by mass or less with respect to the entire conductive paste. The conductive paste according to any one of claims 1 to 6, wherein the alkyl acetalized polyvinyl alcohol is in an amount of 0.5% by mass or more and 1.5% by mass or less with respect to the entire conductive paste. The conductive paste according to any one of claims 1 to 7, wherein the alkyl acetalized polyvinyl alcohol is in an amount of 5% by mass or more and 20% by mass or less with respect to the diluent. With the base material
A semiconductor element mounted on the base material via an adhesive layer, and the like.
A semiconductor device in which the adhesive layer is made of a cured product of the conductive paste according to any one of claims 1 to 8.

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