JP6282886B2 - Semiconductor adhesive paste and semiconductor device - Google Patents

Description

  The present invention relates to a semiconductor adhesive paste and a semiconductor device that are excellent in high thermal conductivity and heat dissipation and that can satisfactorily bond a semiconductor element to a metal substrate.

  Generally, a semiconductor device is manufactured by bonding a semiconductor element such as a semiconductor chip to a lead frame with a die bonding material. Conventionally, Au-Si eutectic, solder, conductive adhesive, and the like are known as semiconductor die bonding materials, but in recent years, conductive adhesives have been widely used in terms of workability and cost. .

  Semiconductor elements such as semiconductor chips tend to have higher integration density and higher heat generation per unit area with higher integration and miniaturization. Therefore, in a semiconductor device on which a semiconductor element is mounted, it is necessary to efficiently dissipate the heat generated from the semiconductor element to the outside, and improvement of the thermal conductivity of the die bonding material is a problem.

  In addition, solder bonding is the mainstream for bonding devices in power device packages. However, due to environmental problems, there has been a trend toward lead-free soldering. The demand for conductive paste is increasing.

  However, since the conventional conductive paste has a smaller thermal conductivity than that of the solder, further higher thermal conductivity is desired.

  On the other hand, in order to improve the thermal conductivity of the conductive paste, it may be possible to add many inorganic fillers such as silver powder. However, if a large amount of inorganic filler is added, the viscosity increases and the coating workability is increased. And a problem that the cured product becomes brittle and the adhesive force between the lead frame and the device is lowered. Further, when the content of the metal particle filler such as silver is increased, the semiconductor adhesive paste coating weight per unit use volume is increased, which causes a problem that the manufacturing cost of the semiconductor device is increased.

  Therefore, as a solution to such a problem, a highly thermally conductive resin composition that is lightweight and has high thermal conductivity, including flaky metal powder and a fibrous carbon material has been proposed (for example, , See Patent Document 1).

JP 2012-72363 A

  However, when used as a conductive material, fibrous carbon materials such as carbon nanotubes exhibit good conductivity even when added in a small amount, but when used as a heat conductive material, the heat conduction path is small and carbon Nanotubes are poorly dispersible and easily agglomerated, making them difficult to handle. In particular, it has been difficult to highly fill resin compositions with dry blends.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a semiconductor adhesive paste and a semiconductor device that can maintain a specific gravity low, have excellent thermal conductivity and heat dissipation, and can satisfactorily bond a semiconductor element to a metal substrate.

  As a result of intensive studies to solve the above problems, the present inventors have formed a semiconductor adhesive paste by blending ceramic particles containing nanocarbon in a dispersed state in addition to silver particles as thermally conductive particles. The present inventors have found that the above problems can be solved, and have completed the present invention.

  That is, the semiconductor adhesive paste of the present invention comprises (A) silver powder having an average particle diameter of 0.5 to 30 μm, (B) ceramic particles containing nanocarbon in a dispersed state, (C) a thermosetting resin, (D) A semiconductor adhesive paste having a curing agent as an essential component, wherein the total amount of the flaky silver powder (A) and the ceramic particles (B) in the semiconductor adhesive paste [( A) + (B)] is contained in an amount of 50 to 90% by mass.

  The semiconductor adhesive paste of the present invention has good contact between the ceramic particles and the silver particles and between the ceramic particles through the nanocarbon present on the surface of the ceramic particles in a dispersed state, and has good thermal conductivity. In addition, since it has a low specific gravity and excellent adhesiveness, it has excellent solder reflow resistance, and a semiconductor device having high reliability can be obtained.

  Furthermore, since it is easy to ensure the thermal conductivity by the ceramic particles of the component (A), the silver content can be reduced, so that the specific gravity is low, which is advantageous for mounting semiconductor elements, and expensive silver and nanocarbon. Since the amount of semiconductor adhesive paste applied can be reduced at the time of use and semiconductor device manufacturing, it is advantageous in terms of cost reduction.

It is sectional drawing which shows the semiconductor device which is one Embodiment of this invention.

  In the present invention, (A) the silver powder having an average particle diameter of 0.5 to 30 μm is particularly limited as long as it is a conventionally known silver powder as an inorganic filler added to the resin paste in order to impart thermal conductivity. Can be used without being.

  Examples of the shape of the silver powder of component (A) used here include flakes, scales, dendrites, rods, wires, spheres, plates, and the like. Of these, in order to maintain high thermal conductivity, flakes, scales, rods, wires, etc. are preferred, and in particular, flakes and scales of silver powder are preferred because of their high effect of maintaining thermal conductivity. .

  Moreover, the average particle diameter of the silver powder of the (A) component used here is 0.5-30 micrometers, Preferably it is 0.5-10 micrometers. Generally, there is a dispersing agent such as fatty acid on the surface of silver powder to prevent agglomeration, and since this dispersing agent acts as a thermal barrier, it inhibits the effect of thermal conductivity and is highly filled with silver powder. Then, high thermal conductivity cannot be obtained. However, in the structure of this invention, it turned out that heat conductivity can be maintained even if it reduces the compounding quantity of silver powder by making an average particle diameter into the said range.

  This is because a good contact is formed between the fibrous protrusions of nanocarbon existing on the surface of the ceramic (sintered) particles of the component (B), which will be described later, and the silver powder of the component (A). This is thought to be due to a drop in the threshold value.

In addition, in this specification, the average particle diameter of the silver powder of the component (A) is the particle diameter (50% particle diameter D ₅₀ ) in which the integrated volume is 50% in the particle size distribution measured by the laser diffraction particle size distribution measuring device. Say.

  In the present invention, (B) ceramic particles containing nanocarbon in a dispersed state are ceramic particles obtained by sintering so that nanocarbon is dispersed and contained.

  In the present invention, “nanocarbon” means fine carbon having a size of at least one side of 1000 nm or less (preferably 500 nm or less) in the shape of the material. Layer / multilayer type, cup stack type) and carbon nanofibers. Among these nanocarbons, carbon nanotubes are preferable because the fibrous protrusions act as tentacles, and the silver particles can be well connected to each other through the ceramic particles, and the thermal conductivity can be effectively improved.

  The carbon nanotubes may be single wall carbon nanotubes or multi-wall carbon nanotubes. The average fiber length of the carbon nanotube is preferably 0.1 to 100 μm, more preferably 0.1 to 50 μm, and particularly preferably 0.1 to 20 μm. The average fiber diameter of the carbon nanotubes is preferably 5 to 200 nm, more preferably 8 to 160 nm, and particularly preferably 9 to 120 nm.

  The aspect ratio ([length] / [diameter]) of the carbon nanotube is preferably 20 to 3000, more preferably 40 to 2000, and particularly preferably 100 to 1200.

  In this invention, 2-20 volume% is preferable and, as for the content rate of the nanocarbon contained in the ceramic particle containing nanocarbon, 5-10 volume% is more preferable. If the content of nanocarbon is less than 2% by volume, sufficient thermal conductivity may not be obtained, and if it exceeds 20% by volume, the sinterability of ceramic particles may be reduced, which is not preferable.

  By selecting the carbon nanotubes having the shape and size as described above, the carbon nanotubes are easily entangled with each other, and good thermal conductivity can be obtained.

  The length and diameter of the carbon nanotube are measured with respect to 100 or more structures existing within a predetermined range using an AFM (Atomic Force Microscope), and the number is 90% or more.

  Furthermore, you may use 2 or more types of nanocarbon combining nanocarbon other than a carbon nanotube. For example, it is known that when the amount of carbon nanotubes increases, aggregates tend to be formed, but when carbon nanohorns are mixed with carbon nanotubes, they are more easily dispersed. Furthermore, it is preferable to disperse carbon nanohorns in the ceramic since an effect of absorbing strain can be expected.

  Moreover, the ceramic material which comprises the ceramic particle used here will not be specifically limited if it functions as a heat conductive material in the hardened | cured material of a semiconductor adhesive paste. As such ceramics, those having a thermal conductivity of 10 W / (m · K) or more at room temperature as measured by the laser flash method of the ceramic particles of component (B) are preferable, and 20 W / (m · K) or more. Is more preferable. When the thermal conductivity is less than 10 W / (m · K), there is a possibility that sufficient thermal conductivity as a semiconductor adhesive paste cannot be obtained.

  Specific examples of the ceramic used here include ceramics such as oxides such as alumina, zinc oxide, and magnesium oxide, and nitrides such as aluminum nitride, hexagonal boron nitride, cubic boron nitride, and silicon nitride. Examples include ligation. Among these, alumina is preferable because it has a good balance between thermal conductivity and specific gravity.

  The particle diameter of the ceramic particles (sintered body) containing the (B) nanocarbon in a dispersed state is preferably 1 to 25 μm, more preferably 5 to 20 μm. By setting the average particle diameter within such a range, an appropriate viscosity can be imparted to the composition, and bleeding of the resin component during application or curing can be suppressed. If the maximum particle size of the ceramic particles exceeds 50 μm, when the adhesive composition is applied by a dispenser, the needle outlet may be blocked and cannot be used for a long time. Is preferably 50 μm or less.

  Furthermore, the ceramic particles of the component (B) having different average particle diameters may be mixed and used. In that case, each average particle diameter satisfies the range of 1 to 25 μm, and the mixed powder is an average. Those having a particle diameter in the range of 1 to 25 μm are preferred.

In the present specification, the particle size of the ceramic particles of component (B) is the particle size (50% particle size D ₅₀ ) at which the integrated volume is 50% in the particle size distribution measured by a laser diffraction particle size distribution measuring device. Say.

  By setting the average particle diameter in the above range, even when the amount of expensive carbon nanotubes is small, good heat conductivity can be expressed in the cured semiconductor adhesive paste. This is because the percolation threshold decreases because (B) the carbon fiber fibrous protrusions present on the surface of the ceramic particles containing nanocarbon in a dispersed state form a good contact point with other conductive particles. it is conceivable that.

  As described above, since carbon nanotubes are fibrous, even if dispersed in ceramic particles, a plurality of fibrous protrusions are present, which is effective in improving characteristics.

  When such fine fibrous protrusions are present, a good contact is formed between the particles of the component (A) and the component (B) when the semiconductor adhesive paste is cured. This is preferable because the silver content in the semiconductor paste can be reduced and the specific gravity and manufacturing cost of the semiconductor adhesive paste can be reduced.

  The method for producing the ceramic particles of component (B) is not particularly limited as long as the ceramic raw material particles in which nanocarbon is dispersed and contained can be obtained. For example, a predetermined amount of nanocarbon and ceramic raw material particles in a solvent. And a slurry, which is dried and then sintered.

  The slurry may be prepared by first mixing nanocarbon and ceramic raw material particles, and putting this in a solvent. This mixing may be performed by a mixing method using a known disperser such as a ball mill or a bead mill. Moreover, what is necessary is just to select a preferable solvent from the point of dispersibility, workability | operativity (easily removable at the time of powder refinement | purification), etc. from the well-known solvent used in manufacture of sintered compact particle | grains, for example, water, acetone, Preferred examples include alcohols and hydrocarbons. In adjusting the slurry, a dispersant, a binder, or the like may be added as necessary.

  Also, in order to obtain a mixed composition comprising ceramic raw material particles and carbon nanotubes by drying the slurry, a method of drying using a blower dryer, a spray drying method in which the slurry is sprayed into a spray dryer, a freeze drying method, etc. The solvent may be removed by a known method.

  Finally, the mixed composition is heated and sintered, but the type of the heating furnace is not particularly limited, and a single kiln, a tunnel kiln, a rotary kiln, or the like can be used. The heating temperature should just be able to form a sintered compact, for example, 1000 to 1600 degreeC is preferable. When the temperature is lower than 1000 ° C., sintering may be insufficient. When the temperature exceeds 1600 ° C., the agglomeration force of the agglomerates becomes strong, and crushing into primary particles may not easily proceed. Moreover, although heating time changes with heating temperature, about 1 hour-about 3 hours are preferable normally.

  Since the ceramic particles thus produced often take the form of secondary agglomerated grains, the obtained ceramic particles can be crushed in a short time by a pulverizing means such as a ball mill, a vibration mill or a jet mill. Through the process, ceramic particles containing nanocarbon as the component (B) having a desired particle size distribution are obtained.

  The ceramic particles as the component (B) preferably have an average particle size of 1 to 25 μm, and more preferably 5 to 20 μm.

  As described above, by connecting the silver particles, which are thermally conductive particles, in the conductive paste through the nanocarbon fibrous protrusions protruding like tentacles from the surface of the ceramic particles, the content of silver particles Even if it is reduced, good thermal conductivity is exhibited, and a semiconductor adhesive paste having good adhesion and low specific gravity can be obtained.

  At this time, the total amount [(A) + (B)] of the silver powder of the component (A) and the ceramic particles of the component (B) is mixed in the semiconductor adhesive paste by 50 to 90% by mass. Is more preferable, and 75 mass%-85 mass% is more preferable. It is preferable for the total amount of the component (A) and the component (B) to be in such a range because of excellent thermal conductivity and adhesiveness.

  If the total amount of the component (A) and the component (B) is less than 50% by mass in the semiconductor adhesive paste, sufficient thermal conductivity cannot be obtained, and if it exceeds 90% by mass, the viscosity increases and the workability decreases. This is not preferable because of fear.

  In addition, the mixing ratio of the component (A) and the component (B) is preferably 50:50 to 90:10 by volume ratio. When the mixing ratio is within this range, the balance between the thermal conductivity and the specific gravity of the semiconductor adhesive paste is achieved. It is preferable because it is excellent. Moreover, when it exists in such a range, it can be made light so that the specific gravity of a semiconductor paste may be 5 or less. For example, when the specific gravity of the semiconductor paste is reduced from 5.9 to 4.0, the used weight of the semiconductor paste is reduced by 30% or more when compared with the same discharge volume.

  The (C) thermosetting resin used in the present invention can be used without any particular limitation as long as it is a thermosetting resin generally used as an adhesive. Among these, a resin that is liquid at room temperature (25 ° C.) is preferable.

  Examples of the (C) thermosetting resin include cyanate resin, epoxy resin, radical polymerizable acrylic resin, maleimide resin, and the like.

  The cyanate resin is a compound having an —NCO group in the molecule, and forms a three-dimensional network structure by the reaction of the —NCO group by heating to be cured. Specifically, 1,3-dicyanatobenzene, 1,4-dicyanatobenzene, 1,3,5-tricyanatobenzene, 1,3-dicyanatonaphthalene, 1,4-dicyanatonaphthalene, 1, 6-dicyanatonaphthalene, 1,8-dicyanatonaphthalene, 2,6-dicyanatonaphthalene, 2,7-dicyanatonaphthalene, 1,3,6-tricyanatonaphthalene, 4,4'-dicyanatobiphenyl, 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) Examples of the polyfunctional cyanate resins include luphone, tris (4-cyanatophenyl) phosphite, tris (4-cyanatophenyl) phosphate, and cyanates obtained by reacting novolac resins with cyanogen halides. A prepolymer having a triazine ring formed by trimerizing a cyanate group can also be used.

  This prepolymer is obtained by polymerizing the above-mentioned polyfunctional cyanate resin monomer using, for example, an acid such as mineral acid or Lewis acid, a base such as sodium alcoholate or tertiary amine, or a salt such as sodium carbonate as a catalyst. It is done. In addition, the cyanate resin can be used in combination with other resins such as an epoxy resin, an oxetane resin, an acrylic resin, and a maleimide resin.

  The epoxy resin is a compound having one or more glycidyl groups in the molecule, and is a resin that forms a three-dimensional network structure by the reaction of the glycidyl groups by heating and cures. It is preferable that two or more glycidyl groups are contained in one molecule, but this is because sufficient cured product characteristics cannot be exhibited even if the glycidyl group is reacted with only one compound. Compounds containing two or more glycidyl groups per molecule include bisphenol compounds such as bisphenol A, bisphenol F, and biphenol or derivatives thereof, hydrogenated bisphenol A, hydrogenated bisphenol F, hydrogenated biphenol, cyclohexanediol, and cyclohexanedimethanol. Diols having an alicyclic structure such as cyclohexanediethanol or derivatives thereof, bifunctional ones obtained by epoxidizing aliphatic diols such as butanediol, hexanediol, octanediol, nonanediol, decanediol, or derivatives thereof, Hydroxyphenylmethane skeleton, trifunctional one having aminophenol skeleton, phenol novolac resin, cresol novolac resin, phenol aralkyl resin, biphenyla Alkyl resins, and the naphthol aralkyl resin as polyfunctional epoxidized. However, the epoxy resin is not limited to these. In addition, since the resin composition is pasty or liquid at room temperature, an epoxy resin that is liquid at room temperature alone or as a mixture is preferable. It is also possible to use reactive diluents as is usual. Examples of the reactive diluent include monofunctional aromatic glycidyl ethers such as phenyl glycidyl ether and cresyl glycidyl ether, and aliphatic glycidyl ethers. The epoxy resin is also preferably used in combination with a cyanate resin, an acrylic resin, or a maleimide resin.

  The radical polymerizable acrylic resin is a compound having a (meth) acryloyl group in the molecule, and is a resin that forms a three-dimensional network structure by the reaction of the (meth) acryloyl group and cures. It is preferable that one or more (meth) acryloyl groups are contained in the molecule. Particularly preferred acrylic resins are polyethers, polyesters, polycarbonates, poly (meth) acrylates having a (meth) acrylic group having a weight average molecular weight of 100 to 10,000.

  Here, as a polyether, what a C1-C6 organic group repeated via the ether bond is preferable, and what does not contain an aromatic ring is preferable. It can be obtained by reacting a polyether polyol with (meth) acrylic acid or a derivative thereof.

  The polyester is preferably a group in which an organic group having 1 to 6 carbon atoms is repeated via an ester bond, and preferably does not contain an aromatic ring. It can be obtained by reacting a polyester polyol with (meth) acrylic acid or a derivative thereof.

  As a polycarbonate, what a C1-C6 organic group repeated via the carbonate bond is preferable, and the thing which does not contain an aromatic ring is preferable. It can be obtained by reacting a polycarbonate polyol with (meth) acrylic acid or a derivative thereof.

  Examples of the poly (meth) acrylate include a copolymer of (meth) acrylic acid and (meth) acrylate or a copolymer of (meth) acrylate having a polar group and (meth) acrylate having no polar group. preferable. In the case of reacting these copolymers with a carboxyl group, it can be obtained by reacting an acrylate having a hydroxyl group, and in the case of reacting with a hydroxyl group, (meth) acrylic acid or a derivative thereof.

  If necessary, the following compounds can be used. For example, 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate, 3-hydroxybutyl (meth) acrylate, 4-hydroxy Butyl (meth) acrylate, 1,2-cyclohexanediol mono (meth) acrylate, 1,3-cyclohexanediol mono (meth) acrylate, 1,4-cyclohexanediol mono (meth) acrylate, 1,2-cyclohexanedimethanol mono (Meth) acrylate, 1,3-cyclohexanedimethanol mono (meth) acrylate, 1,4-cyclohexanedimethanol mono (meth) acrylate, 1,2-cyclohexanediethanol mono (meth) acrylate 1,3-cyclohexanediethanol mono (meth) acrylate, 1,4-cyclohexanediethanol mono (meth) acrylate, glycerin mono (meth) acrylate, glycerin di (meth) acrylate, trimethylolpropane mono (meth) acrylate, tri (Meth) acrylate having a hydroxyl group such as methylolpropane di (meth) acrylate, pentaerythritol mono (meth) acrylate, pentaerythritol di (meth) acrylate, pentaerythritol tri (meth) acrylate, neopentyl glycol mono (meth) acrylate, Examples thereof include (meth) acrylates having a carboxy group obtained by reacting these (meth) acrylates having a hydroxyl group with dicarboxylic acids or derivatives thereof. Examples of the dicarboxylic acid usable here include oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, maleic acid, fumaric acid, phthalic acid, and tetrahydrophthalic acid. , Hexahydrophthalic acid and derivatives thereof.

  In addition to the above, methyl (meth) acrylate, ethyl (meth) acrylate, n-butyl (meth) acrylate, isobutyl (meth) acrylate, tertiary butyl (meth) acrylate, isodecyl (meth) acrylate, lauryl (meth) acrylate, Tridecyl (meth) acrylate, cetyl (meth) acrylate, stearyl (meth) acrylate, isoamyl (meth) acrylate, isostearyl (meth) acrylate, behenyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, others Alkyl (meth) acrylate, cyclohexyl (meth) acrylate, tertiary butyl cyclohexyl (meth) acrylate, tetrahydrofurfuryl (meth) acrylate, benzyl (meth) acrylate, Xylethyl (meth) acrylate, isobornyl (meth) acrylate, glycidyl (meth) acrylate, trimethylolpropane tri (meth) acrylate, zinc mono (meth) acrylate, zinc di (meth) acrylate, dimethylaminoethyl (meth) acrylate, diethylaminoethyl ( (Meth) acrylate, neopentyl glycol (meth) acrylate, trifluoroethyl (meth) acrylate, 2,2,3,3-tetrafluoropropyl (meth) acrylate, 2,2,3,3,4,4-hexafluoro Butyl (meth) acrylate, perfluorooctyl (meth) acrylate, perfluorooctylethyl (meth) acrylate, ethylene glycol di (meth) acrylate, propylene glycol di (meth) acrylate 1,4-butanediol di (meth) acrylate, 1,6-hexanediol di (meth) acrylate, 1,9-nonanediol di (meth) acrylate, 1,3-butanediol di (meth) acrylate, 1 , 10-decanediol di (meth) acrylate, tetramethylene glycol di (meth) acrylate, methoxyethyl (meth) acrylate, butoxyethyl (meth) acrylate, ethoxydiethylene glycol (meth) acrylate, methoxypolyalkylene glycol mono (meth) acrylate , Octoxy polyalkylene glycol mono (meth) acrylate, Lauroxy polyalkylene glycol mono (meth) acrylate, Stearoxy polyalkylene glycol mono (meth) acrylate, Allyloxy polyalkyl Lenglycol mono (meth) acrylate, nonylphenoxypolyalkylene glycol mono (meth) acrylate, acryloylmorpholine, hydroxyethyl acrylamide, N, N'-methylenebis (meth) acrylamide, N, N'-ethylenebis (meth) acrylamide, 1,2-di (meth) acrylamide ethylene glycol, di (meth) acryloyloxymethyl tricyclodecane, N- (meth) acryloyloxyethylmaleimide, N- (meth) acryloyloxyethyl hexahydrophthalimide, N- (Meth) acryloyloxyethylphthalimide, n-vinyl-2-pyrrolidone, a styrene derivative, an α-methylstyrene derivative and the like can also be used.

  The radical polymerizable acrylic resin is also preferably used in combination with a cyanate resin, an epoxy resin, or a maleimide resin.

  The maleimide resin is a compound that contains one or more maleimide groups in one molecule, and forms a three-dimensional network structure when the maleimide group reacts by heating, and is cured. For example, N, N ′-(4,4′-diphenylmethane) bismaleimide, bis (3-ethyl-5-methyl-4-maleimidophenyl) methane, 2,2-bis [4- (4-maleimidophenoxy) phenyl ] A bismaleimide resin such as propane may be mentioned. More preferred maleimide resins are compounds obtained by reaction of dimer acid diamine and maleic anhydride, and compounds obtained by reaction of maleimidated amino acids such as maleimide acetic acid and maleimide caproic acid with polyols.

  The maleimidated amino acid is obtained by reacting maleic anhydride with aminoacetic acid or aminocaproic acid. As the polyol, polyether polyol, polyester polyol, polycarbonate polyol, poly (meth) acrylate polyol is preferable, and an aromatic ring is formed. What does not contain is especially preferable.

  Since the maleimide group can react with an allyl group, the combined use with an allyl ester resin is also preferable. The allyl ester resin is preferably an aliphatic one, and particularly preferred is a compound obtained by transesterification of a cyclohexane diallyl ester and an aliphatic polyol.

  The number average molecular weight of the allyl ester compound is not particularly limited, but is preferably 500 to 10,000, and particularly preferably 500 to 8,000. When the number average molecular weight is within such a range, curing shrinkage can be particularly reduced, and deterioration of adhesion can be prevented. Moreover, combined use with cyanate resin, an epoxy resin, and an acrylic resin is also preferable.

  In the present invention, as the (D) curing agent, a known curing agent for the thermosetting resin of the component (C) may be mentioned. The thermosetting resin is cured by this curing agent.

  When a cyanate resin is used as the component (C), examples of the curing agent include active hydrogen compounds, that is, polyols such as polyamines having a hydroxyl group, polyamides, glycols, polyether polyols, polyester polyols, acrylics, and polyols.

  As the curing accelerator for the cyanate resin, generally known ones can be used. Examples include organometallic complexes such as zinc octylate, tin octylate, cobalt naphthenate, zinc naphthenate and acetylacetone iron, metal salts such as aluminum chloride, tin chloride and zinc chloride, and amines such as triethylamine and dimethylbenzylamine. However, it is not limited to these. These curing accelerators can be used alone or in combination.

  When an epoxy resin is used as the component (C), examples of the curing agent include aliphatic amines, aromatic amines, dicyandiamide, dihydrazide compounds, acid anhydrides, and phenol resins. Examples of the dihydrazide compound include carboxylic acid dihydrazides such as adipic acid dihydrazide, dodecanoic acid dihydrazide, isophthalic acid dihydrazide, p-oxybenzoic acid dihydrazide, and the acid anhydrides include phthalic anhydride, tetrahydrophthalic anhydride, hexahydroanhydride. Examples thereof include phthalic acid, endomethylenetetrahydrophthalic anhydride, dodecenyl succinic anhydride, a reaction product of maleic anhydride and polybutadiene, and a copolymer of maleic anhydride and styrene.

  A phenol resin used as a curing agent for an epoxy resin is a compound having two or more phenolic hydroxyl groups in one molecule. In the case of a compound having one phenolic hydroxyl group in one molecule, a cross-linked structure may be taken. Therefore, the cured product characteristics deteriorate and cannot be used.

  The number of phenolic hydroxyl groups in one molecule can be used as long as it is 2 or more, but the number of phenolic hydroxyl groups is preferably 2 to 5. When the amount is larger than this, the molecular weight becomes too large, and the viscosity of the conductive paste becomes too high, which is not preferable. The number of phenolic hydroxyl groups in one molecule is more preferably 2 or 3.

  Such compounds include bisphenol F, bisphenol A, bisphenol S, tetramethyl bisphenol A, tetramethyl bisphenol F, tetramethyl bisphenol S, dihydroxy diphenyl ether, dihydroxy benzophenone, tetramethyl biphenol, ethylidene bisphenol, methyl ethylidene bis (methyl phenol). ), Bisphenols such as cyclohexylidene bisphenol and biphenol and derivatives thereof, trifunctional phenols such as tri (hydroxyphenyl) methane and tri (hydroxyphenyl) ethane, and phenols such as phenol novolac and cresol novolac A compound obtained by reacting formaldehyde with formaldehyde, which is mainly dinuclear or trinuclear and its derivatives Body and the like.

Furthermore, a curing accelerator can be blended in order to accelerate curing. Examples of epoxy resin curing accelerators include imidazoles, triphenylphosphine or tetraphenylphosphine and salts thereof, amine compounds such as diazabicycloundecene, and the like. Examples thereof include 2-methylimidazole, 2-ethylimidazole-2-phenylimidazole, 2-phenyl-4-methylimidazole, 2-phenyl-4-methyl-5-hydroxymethylimidazole, 2-phenyl- 4,5-dihydroxy methyl imidazole, _2-C 11 _{H 23} -, imidazole compounds such as the adduct of 2-methylimidazole and 2,4-diamino-6-vinyl-triazine is preferably used. Particularly preferred is an imidazole compound having a melting point of 180 ° C. or higher.

  When a radically polymerizable acrylic resin is used as the component (C), a polymerization initiator is generally used as the curing agent. A thermal radical polymerization initiator is preferred as the polymerization initiator, and a known thermal radical polymerization start is initiated. Any agent can be used without particular limitation.

  In addition, as the thermal radical polymerization initiator, those having a decomposition temperature of 40 to 140 ° C. in a rapid heating test (decomposition start temperature when 1 g of a sample is placed on an electric heating plate and heated at 4 ° C./min). preferable. When the decomposition temperature is less than 40 ° C., the preservability of the conductive paste at room temperature deteriorates, and when it exceeds 140 ° C., the curing time becomes extremely long.

  Specific examples of the thermal radical polymerization initiator satisfying such characteristics include methyl ethyl ketone peroxide, methylcyclohexanone peroxide, methyl acetoacetate peroxide, acetylacetone peroxide, 1,1-bis (t-butylperoxy) 3, 3,5-trimethylcyclohexane, 1,1-bis (t-hexylperoxy) cyclohexane, 1,1-bis (t-hexylperoxy) 3,3,5-trimethylcyclohexane, 1,1-bis ( t-butylperoxy) cyclohexane, 2,2-bis (4,4-di-t-butylperoxycyclohexyl) propane, 1,1-bis (t-butylperoxy) cyclododecane, n-butyl- 4,4-bis (t-butylperoxy) valerate, 2,2-bis (t-butyl) -Oxy) butane, 1,1-bis (t-butylperoxy) -2-methylcyclohexane, t-butyl hydroperoxide, p-menthane hydroperoxide, 1,1,3,3-tetramethylbutyl hydroperoxide T-hexyl hydroperoxide, dicumyl peroxide, 2,5-dimethyl-2,5-bis (t-butylperoxy) hexane, α, α′-bis (t-butylperoxy) diisopropylbenzene, t-Butyl cumyl peroxide, di-t-butyl peroxide, 2,5-dimethyl-2,5-bis (t-butylperoxy) hexyne-3, isobutyryl peroxide, 3,5,5-trimethyl Hexanoyl peroxide, octanoyl peroxide, lauroyl peroxide, cinnamic acid Oxide, m-toluoyl peroxide, benzoyl peroxide, diisopropyl peroxydicarbonate, bis (4-t-butylcyclohexyl) peroxydicarbonate, di-3-methoxybutyl peroxydicarbonate, di-2-ethyl Hexyl peroxydicarbonate, di-sec-butyl peroxydicarbonate, di (3-methyl-3-methoxybutyl) peroxydicarbonate, di (4-t-butylcyclohexyl) peroxydicarbonate, α, α′-bis (neodecanoylperoxy) diisopropylbenzene, cumylperoxyneodecanoate, 1,1,3,3-tetramethylbutylperoxyneodecanoate, 1-cyclohexyl-1-methylethyl Peroxyneodecanoate, t-hexy Luperoxyneodecanoate, t-butylperoxyneodecanoate, t-hexylperoxybivalate, t-butylperoxybivalate, 2,5-dimethyl-2,5-bis (2-ethylhexa Noylperoxy) hexane, 1,1,3,3-tetramethylbutylperoxy-2-ethylhexanoate, 1-cyclohexyl-1-methylethylperoxy-2-ethylhexanoate, t-hexyl Peroxy-2-ethylhexanoate, t-butylperoxy-2-ethylhexanoate, t-butylperoxyisobutyrate, t-butylperoxymaleic acid, t-butylperoxylaurate, t -Butylperoxy-3,5,5-trimethylhexanoate, t-butylperoxyisopropyl monocarbonate T-butylperoxy-2-ethylhexyl monocarbonate, 2,5-dimethyl-2,5-bis (benzoylperoxy) hexane, t-butylperoxyacetate, t-hexylperoxybenzoate, t -Butylperoxy-m-toluoylbenzoate, t-butylperoxybenzoate, bis (t-butylperoxy) isobutarate, t-butylperoxyallyl monocarbonate, 3,3 ', 4,4'-tetra (t -Butylperoxycarbonyl) benzophenone and the like can be mentioned, but these can be used alone or in combination of two or more in order to control curability.

  When a maleimide resin is used as the component (C), the polymerization initiator exemplified for the acrylic resin is preferably used as the curing agent.

  These (D) curing agents may be used alone or in combination of two or more in order to control curability. Furthermore, various polymerization inhibitors may be added in advance in order to improve the storage stability of the adhesive thermosetting resin composition. As for the compounding quantity of this (D) hardening | curing agent, 0.1-10 mass parts is preferable with respect to 100 mass parts of (C) component. If it exceeds 10 parts by mass, the change in the viscosity of the adhesive thermosetting resin composition with time will increase, causing problems in workability, and if it is less than 0.1 part by mass, the curability may be significantly reduced.

  In the semiconductor adhesive paste of the present invention, in addition to the above components, a curing accelerator, a low stress agent such as rubber or silicone, which is generally blended with this type of composition within a range not inhibiting the effects of the present invention. , Coupling agents, antifoaming agents, surfactants, colorants (pigments, dyes), various polymerization inhibitors, antioxidants, and other various additives can be blended as necessary. Each of these additives may be used alone or in combination of two or more.

Moreover, you may contain the silver fine particle whose average particle diameter is 10-100 nm.
When such silver fine particles are contained, the sinterability of the silver powder of the component (A) can be improved and a resin paste with high thermal conductivity can be obtained. The silver fine particles used here are preferably spherical. In addition, it is preferable that the silver fine particles have a metal surface provided with a coating layer made of an organic compound or the silver fine particles dispersed in an organic compound. In such a form, since the silver fine particles contained can be prevented from directly contacting the metal surface, the formation of agglomerates of silver fine particles can be suppressed, and the silver fine particles are dispersed individually Can be retained. In addition, the average particle diameter of the silver fine particles is determined in accordance with the measurement procedure described in JIS Z8901: 2006 8.3.2 b) with respect to 100 arbitrary particles by a TEM or SEM in a certain direction (obtained). This is the number-based median diameter calculated by plotting the data on logarithmic probability paper.

  The coupling agent is not particularly limited, and examples thereof include an epoxy silane coupling agent, an acrylic silane coupling agent, a thiol silane coupling agent, an amine silane coupling agent, etc., among which acrylic silane A coupling agent and a thiol-based silane coupling agent are preferably used.

  The acrylic silane coupling agent is a silane coupling agent having a methacrylic group in the skeleton, for example, 3-methacryloxypropyltrimethoxysilane, 3-methacryloxypropyltriethoxysilane, 3-acryloxypropyltrimethoxysilane. , 3-acryloxypropyltriethoxysilane, methacryloxymethyltrimethoxysilane, methacryloxymethyltriethoxysilane, acryloxymethyltrimethoxysilane, acryloxymethyltriethoxysilane, and the like.

  The thiol-based silane coupling agent is a thiol-based silane coupling agent having a thiol group at the terminal, and examples thereof include 3-mercaptopropyltrimethoxysilane and 3-mercaptopropyltriethoxysilane. These form a stable bond close to a covalent bond with the silver metal surface.

  The thermosetting resin composition for semiconductors of the present invention is publicly known such that components (A) to (D) and other additives are premixed and kneaded using a roll and then defoamed under vacuum. It is obtained by the manufacturing method.

Next, the semiconductor device of the present invention will be described.
The semiconductor device of the present invention can be produced by a known method using the thermosetting resin composition for semiconductor bonding of the present invention. For example, the semiconductor device is bonded between the semiconductor element and the semiconductor element supporting member via the resin composition. It is done by fixing. For example, a semiconductor element is mounted on a lead frame as a support member via the thermosetting resin composition for semiconductor bonding of the present invention, the thermosetting resin composition for semiconductor bonding is heated and cured, and then the lead frame The lead portion and the electrode on the semiconductor element can be connected by wire bonding, and then these can be sealed with a sealing resin. As a bonding wire, the wire which consists of copper, gold | metal | money, aluminum, a gold alloy, aluminum-silicon etc. is illustrated, for example. Moreover, the temperature at the time of hardening an electrically conductive paste is 100-230 degreeC normally, Preferably it is 100-200 degreeC, and when using the lead frame made from copper, 190 degrees C or less is especially preferable, and 0. It is preferable to heat for about 5 to 2 hours.

  FIG. 1 shows an example of the semiconductor device of the present invention thus obtained. The present invention is provided between a lead frame 1 such as a copper frame or PPF (palladium pre-plating lead frame) and a semiconductor element 2. An adhesive layer 3 which is a cured product of the semiconductor adhesive paste of the invention is interposed. Further, the electrode 4 on the semiconductor element 2 and the lead portion 5 of the lead frame 1 are connected by a bonding wire 6, and these are further sealed by a sealing resin 7. In addition, as thickness of the adhesive bond layer 3, about 10-30 micrometers is preferable. In the above description, the lead frame is exemplified as the semiconductor element support member. However, the lead frame is not limited as long as it is a target to which the semiconductor element is fixed, and can be applied to, for example, a circuit board or a heat dissipation member.

  The semiconductor device of the present invention is excellent in solder reflow resistance and high reliability because the semiconductor element is bonded and fixed with a semiconductor adhesive paste having a low elastic modulus and excellent adhesion. .

  EXAMPLES Next, although an Example demonstrates this invention further in detail, this invention is not limited to these Examples at all.

(Synthesis Example 1)
As raw materials, α-Al ₂ O ₃ powder, and carbon nanotubes in an amount of 10% by volume with respect to the volume of the ceramic sintered body to be manufactured (manufactured by Showa Denko KK, trade name: VGCF-S; average (Fiber diameter: 80 nm, average fiber length: 10 μm). Acetone was added to these as a solvent to form a slurry containing α-Al ₂ O ₃ powder and carbon nanotubes, and mixed using a ball mill.

The mixed slurry was dried in an evaporating dish to obtain a mixed powder of α-Al ₂ O ₃ and carbon nanotubes. It put into the baking container and heat-processed in the tunnel kiln furnace at maximum 1500 degreeC and residence time 3 hours. After the heat treatment, it was taken out from the firing container and pulverized with an airflow pulverizer to obtain ceramic particles containing nanocarbon having an average particle diameter of 5.6 μm.

(Examples 1-3, Comparative Examples 1-5)
Each component was mixed according to the composition of Table 1 and kneaded with a roll to obtain a semiconductor adhesive paste. The obtained semiconductor adhesive paste was evaluated by the following method. The results are shown in Table 1. In addition, the material used by the Example and the comparative example used the commercial item as follows except (B) component.

(A) Silver powder: flaky silver powder (Fukuda Metal Foil Powder Co., Ltd., trade name: AgC-212D; average particle size: 5 μm)
(B) Ceramic particles containing 10% by volume of nanocarbon in a dispersed state: Ceramic particles produced in Synthesis Example 1 (C) Thermosetting resin: Hydroxylethylacrylamide (manufactured by Kojin Co., Ltd., HEAA)
(D) Hardener: Dicumyl peroxide (Nippon Yushi Co., Ltd., trade name: Park Mill D)

Other components Inorganic filler: Spherical alumina CB-A10 (made by Showa Denko KK, trade name)
Solvent: Diethylene glycol (manufactured by Tokyo Chemical Industry Co., Ltd.)
Nanocarbon: carbon nanotube (manufactured by Showa Denko KK, trade name: VGCF-S; average fiber diameter: 80 nm, average fiber length: 10 μm)

<Evaluation method>
[specific gravity]
Based on the specific gravity of the constituent raw materials, the specific gravity of the semiconductor adhesive paste was calculated.

[Thermal conductivity]
According to JIS R1611-1997, the thermal conductivity of the cured product was measured by a laser flash method.

[Adhesive strength]
A 4 mm × 4 mm silicon chip and a back gold chip provided with a gold vapor deposition layer on the bonding surface are mounted on PPF (Ni-Pd / Au plated copper frame) using a semiconductor resin paste, and 200 ° C., 60 minutes. Cured with. After curing and moisture absorption treatment (85 ° C., relative humidity 85%, 72 hours), the hot die shear strength at 260 ° C. was measured using a mount strength measuring device.

[IR reflow resistance]
A 6 mm x 6 mm silicon chip was mounted on a copper frame using the obtained resin paste, and heated on a hot plate at 200 ° C for 60 seconds (HP curing) or using an oven at 200 ° C for 60 minutes. Was heat-cured (OV curing). This was subjected to a moisture absorption treatment at 85 ° C. and a relative humidity of 85% for 168 hours using an epoxy sealing material (trade name: KE-G3000D) manufactured by Kyocera Chemical Co., Ltd., followed by an IR reflow treatment ( 260 ° C., 10 seconds), and the number of internal cracks in the package was observed with an ultrasonic microscope. The number of samples in which cracks occurred for five samples is shown.

Package: 80pQFP (14mm x 20mm x 2mm thickness)
Chip: Silicon chip and gold-plated chip on the back surface Lead frame: PPF and copper Molding of sealing material: 175 ° C., 2 minutes Post mold cure: 175 ° C., 8 hours

  As described above, the semiconductor adhesive paste of the present invention has a low specific gravity, good thermal conductivity and adhesiveness, and excellent IR reflow resistance, and adheres a semiconductor element onto a supporting substrate. It is suitable for doing.

DESCRIPTION OF SYMBOLS 1 ... Lead frame, 2 ... Semiconductor element, 3 ... Adhesive layer, 4 ... Electrode, 5 ... Lead part, 6 ... Bonding wire, 7 ... Sealing resin

Claims (7)

(A) silver powder having an average particle size of 0.5 to 30 μm;
(B) ceramic particles containing nanocarbon in a dispersed state;
(C) a thermosetting resin;
(D) a curing agent;
Is a semiconductor adhesive paste having an essential component,
The semiconductor adhesive paste contains 50 to 90% by mass of a total amount [(A) + (B)] of the silver powder of the component (A) and the ceramic particles of the component (B). Adhesive paste.   2. The semiconductor adhesive paste according to claim 1, wherein the ratio of the component (A) to the component (B) is 50:50 to 90:10 on a volume basis.   3. The semiconductor adhesive paste according to claim 1, wherein 2 to 20% by volume of the nanocarbon is contained in the ceramic particles of the component (B).   The semiconductor adhesive paste according to any one of claims 1 to 3, wherein the silver powder of the component (A) is a flaky silver powder.   The semiconductor adhesive paste according to any one of claims 1 to 4, wherein an average particle diameter of the ceramic particles of the component (B) is 1 to 25 µm.   The semiconductor adhesive paste according to claim 1, wherein the ceramic particles of the component (B) are alumina particles.   7. A semiconductor device, wherein a semiconductor chip is bonded onto a support substrate via the semiconductor adhesive paste according to claim 1.

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