JP6134597B2 - Die attach agent - Google Patents

Description

  The present invention relates to a die attach agent and a semiconductor device manufactured using the die attach agent.

  In manufacturing a semiconductor device, a die attach agent is used to bond and fix a semiconductor chip to a metal plate such as a lead frame. The die attach agent is required to have an adhesive strength (die shear strength), particularly an adhesive strength during reflow. In recent years, the amount of heat generated from the semiconductor chip is increasing, and high heat conduction is also required. In order to obtain a high thermal conductivity die attach agent, a high thermal conductivity filler such as silver powder can be highly filled. However, in this case, since the filler is highly filled, the amount of the resin is reduced correspondingly, and the adhesive strength is reduced. The problem of deteriorating arises.

  In order to improve adhesive strength, it has been proposed to add a silane coupling agent containing sulfur to the die attach agent (Patent Documents 1 to 3).

JP 2009-191214 A JP 2011-207944 A JP 2000-103940 A

  However, for example, when a die attach agent to which a silane coupling agent containing sulfur is added is used, although the adhesive strength can be improved, the thermal conductivity cannot be improved. This invention makes it a subject to provide the die attach agent which can improve both adhesive strength and heat conductivity, hold | maintaining low volume resistivity.

  The present invention incorporates a dicarboxylic acid compound containing a disulfide bond (—S—S—) in the molecular structure into a die attach agent, thereby maintaining both low volume resistivity and both adhesive strength and thermal conductivity. It was made based on the knowledge that it can be improved.

The present invention 1
(A) epoxy resin,
(B) Silver powder,
(C) The aliphatic dicarboxylic acid compound containing a disulfide bond, and (D) It relates to the die attach agent which contains a silane coupling agent and (C) is 0.08 to 0.65 mass% in the die attach agent.
The present invention 2 relates to the die attach agent of the present invention 1, wherein (C) is dithiodiglycolic acid and / or dithiodipropionic acid.
In the die attach agent of the present invention 3, (A) is 3.5 to 19% by mass, (B) is 80 to 96% by mass, and (D) is 0.05 to 0.5% by mass. This relates to the die attach agent of the present invention 1 or 2.
This invention 4 is related with the die attach agent in any one of this invention 1-3 containing a hardening | curing agent further.
This invention 5 relates to the die attach agent of this invention 4 whose hardening | curing agent is 0.01-3 mass% in a die attach agent.
This invention 6 relates to the semiconductor device produced using the die attach agent in any one of this invention 1-5.
This invention 7 is related with the semiconductor device of this invention 6 whose surface which applied the die attach agent in any one of this invention 1-5 is copper.

  According to the die attach agent of the present invention, both adhesive strength and thermal conductivity can be improved while maintaining a low volume resistivity.

It is a figure which shows the addition amount of the dithiodipropionic acid in an Example, and the relationship of volume resistivity and thermal conductivity. It is a figure which shows the relationship between the addition amount of the dithiodipropionic acid in an Example, and the die shear strength on the bare copper lead frame in room temperature.

The die attach agent of the present invention is
(A) epoxy resin,
(B) Silver powder,
(C) an aliphatic dicarboxylic acid compound containing a disulfide bond, and (D) a silane coupling agent.

(A) Epoxy Resin The die attach agent of the present invention includes (A) an epoxy resin. (A) is a compound having one or more epoxy groups in the molecule, and can form a three-dimensional network structure and be cured by the reaction of the epoxy groups by heating. It is preferable that two or more epoxy groups are contained in one molecule from the viewpoint of cured product characteristics.

  (A) includes bisphenol compounds such as bisphenol A, bisphenol F, and biphenol or derivatives thereof (for example, alkylene oxide adducts), hydrogenated bisphenol A, hydrogenated bisphenol F, hydrogenated biphenol, cyclohexanediol, and cyclohexanedimethanol. Diols having an alicyclic structure such as shidilohexanediethanol or derivatives thereof, bifunctional epoxies obtained by epoxidizing aliphatic diols such as butanediol, hexanediol, octanediol, nonanediol, decanediol, or derivatives thereof Resin; Trifunctional epoxy resin having trihydroxyphenylmethane skeleton and aminophenol skeleton; phenol novolak resin, cresol novolak resin, phenol aralkyl resin, vinyl E alkenyl aralkyl resins, polyfunctional epoxy resins obtained by epoxidizing a naphthol aralkyl resin and the like, without limitation.

  (A) is preferably liquid at room temperature (25 ° C.), and can be liquid at room temperature alone or as a mixture.

  As (A), those having a low viscosity of 30 Pa · s or less are preferable, and among them, 1,4-cyclohexanedimethanol diglycidyl ether is particularly preferable.

  (A) may be used alone or in combination of two or more.

(B) Silver powder The die attach agent of this invention contains (B) silver powder.

The shape of (B) is not particularly limited, and examples thereof include a spherical shape, a flake shape, and a dendrite shape. Preferably, it is flake shaped.
The average particle diameter of (B) can be 0.5-30 micrometers, Preferably it is 1-10 micrometers. Here, the average particle diameter refers to a volume-based median diameter measured by a laser diffraction method.

(B) is preferably a silver powder having a high tap density and a low specific surface area in order to obtain a high-conductivity and low-viscosity die attach agent. The tap density can be 4 to 7 g / cm ³ , preferably 5 to 7 g / cm ³ , and more preferably 6 to 7 g / cm ³ . The specific surface area can be a 0.05-0.5 M ² / g, preferably from 0.08~0.35m ² / g.

  (B) may be used alone or in combination of two or more.

(C) Aliphatic dicarboxylic acid compound containing a disulfide bond The die attach agent of the present invention contains (C) an aliphatic dicarboxylic acid compound containing a disulfide bond (-SS-). The carboxy part of (C) removes deposits on the surface of the silver powder and promotes contact / sintering between the silver powders, thereby improving the thermal conductivity and electrical conductivity, while the disulfide bond part (-S- S-) is considered to dissociate and generate radicals due to heat during curing, thereby improving the adhesive strength with the substrate (particularly the copper substrate).

  (C) preferably has a boiling point higher than the curing temperature. When the boiling point of (C) is higher than the curing temperature, (C) volatilizes and becomes a void during curing. Examples of (C) include dithiodiglycolic acid, 3,3′-dithiodipropionic acid, 4,4′-dithiodibutyric acid, dithiodilactic acid and the like, among which dithiodiglycolic acid, 3,3′-dithio. Dipropionic acid is preferred.

  (C) may be used alone or in combination of two or more.

  The die attach agent of the present invention contains (D) a silane coupling agent. By blending (D), it is possible to further improve the adhesive strength.

  (D) is not particularly limited, and vinyl group-containing silanes such as vinyltrichlorosilane, vinyltrimethoxysilane, and vinyltriethoxysilane, 2- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, and 3-glycidoxy Epoxy group-containing silanes such as propyltrimethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, and 3-glycidoxypropyltriethoxysilane, styryl group-containing silanes such as p-styryltrimethoxysilane, and 3-methacryloxypropyl Methacryloxy group-containing silanes such as methyldimethoxysilane, 3-methacryloxypropyltrimethoxysilane, 3-methacryloxypropylmethyldiethoxysilane, 3-methacryloxypropyltriethoxysilane, 3-acryloxypropyltrimethoxysila Acryloxy group-containing silane such as N-2- (aminoethyl) -3-aminopropylmethyldimethoxysilane, N-2- (aminoethyl) -3-aminopropyltrimethoxysilane, N-2- (aminoethyl)- 3-aminopropyltriethoxysilane, 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3-triethoxysilyl-N- (1,3-dimethyl-butylidene) propylamine, N-phenyl-3- Examples include amino group-containing silanes such as aminopropyltrimethoxysilane. Among them, 3-methacryloxypropyltrimethoxysilane, 2- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, which has a reactive group that reacts with the epoxy resin and has a high boiling point from the viewpoint of void generation due to adhesive strength and volatilization during curing. 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, 3-glycidoxypropyltriethoxysilane, and the like can be preferably used. The silane coupling agent may be a sulfur-containing silane coupling agent such as bis (ethoxysilylpropyl) disulfide or bis (ethoxysilylpropyl) disulfide, but from the viewpoint of securing good volume resistivity and thermal conductivity. Is preferably a sulfur-free silane coupling agent.

  (D) A component may be individual or may use 2 or more types together.

  In the present invention, when the total mass of the die attach agent is 100% by mass, (C) in the die attach agent is 0.08 to 0.65% by mass. If it is this range, both adhesive strength and thermal conductivity can be improved. (C) is more preferably 0.09 to 0.55% by mass, and particularly preferably 0.1 to 0.35% by mass.

In the die attach agent, (A) is preferably 3.5 to 19% by mass, more preferably 4 to 12% by mass, from the viewpoint of paste viscosity, adhesive strength, and thermal conductivity.
In the die attach agent, (B) is preferably 80 to 96% by mass, more preferably 88 to 95% by mass, from the viewpoint of viscosity and thermal conductivity.
In the die attach agent, (D) is preferably 0.05 to 0.5 mass%, more preferably 0.05 to 0.3 mass%, from the viewpoint of adhesive strength and voids.

  The die attach agent of this invention can contain additives, such as a hardening | curing agent, a hardening accelerator, a coloring agent, an antifoamer, surfactant, and a polymerization inhibitor, in the range which does not impair the effect of this invention.

  If a hardening | curing agent is a hardening | curing agent of an epoxy resin, it will not specifically limit, A well-known thing can be used. Examples include aliphatic amines, aromatic amines, dicyandiamide, dihydrazide compounds, acid anhydrides, and phenol resins.

Examples of aliphatic amines include aliphatic polyamines such as diethylenetriamine, triethylenetetraamine, tetraethylenepentamine, trimethylhexamethylenediamine, m-xylenediamine, and 2-methylpentamethylenediamine, isophoronediamine, and 1,3-bisamino. Cycloaliphatic polyamines such as methylcyclohexane, bis (4-aminocyclohexyl) methane, norbornenediamine, 1,2-diaminocyclohexane, N-aminoethylpiperazine, 1,4-bis (2-amino-2-methylpropyl) piperazine And piperazine type polyamines such as Aromatic amines include diaminodiphenylmethane, m-phenylenediamine, diaminodiphenylsulfone, diethyltoluenediamine, trimethylenebis (4-aminobenzoate), and polytetramethylene oxide-di-p-aminobenzoate. Can be mentioned.
Examples of the dihydrazide compound include carboxylic acid dihydrazides such as adipic acid dihydrazide, dodecanoic acid dihydrazide, isophthalic acid dihydrazide, and p-oxybenzoic acid dihydrazide.
Examples of acid anhydrides include phthalic anhydride, tetrahydrophthalic anhydride, hexahydrophthalic anhydride, endomethylenetetrahydrophthalic anhydride, dodecenyl succinic anhydride, a reaction product of maleic anhydride and polybutadiene, and a combination of maleic anhydride and styrene. A polymer etc. are mentioned.
As a phenol resin, the compound which has two or more phenolic hydroxyl groups in 1 molecule from the point of hardened | cured material characteristic is preferable. For example, 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), cyclohexylene Reacts formaldehyde with bisphenols such as denbisphenol and biphenol and their derivatives, trifunctional phenols such as tri (hydroxyphenyl) methane and tri (hydroxyphenyl) ethane and their derivatives, phenols such as phenol novolac and cresol novolac. Examples of the compound obtained by the above method include a main compound having a binuclear body or a trinuclear body and a derivative thereof. A liquid novolak phenol resin is particularly preferred from the viewpoint that the viscosity of the composition can be lowered and the content of the component (B) can be increased. A hardening | curing agent may be individual or may use 2 or more types together. It is preferable that a hardening | curing agent is 0.01-3 mass% in a die attach agent, More preferably, it is 0.05-2 mass%.

  A hardening accelerator will not be specifically limited if it is a hardening accelerator of an epoxy resin, A well-known thing can be used. For example, an amine hardening accelerator, a phosphorus hardening accelerator, etc. are mentioned.

  Examples of amine-based curing accelerators include imidazoles such as 2-methylimidazole, 2-undecylimidazole, 2-heptadecylimidazole, 2-ethyl-4-methylimidazole, 2-phenylimidazole, and 2-phenyl-4-methylimidazole. Compounds, triazine compounds such as 2,4-diamino-6- [2′-methylimidazolyl- (1 ′)] ethyl-s-triazine, 1,8-diazabicyclo [5,4,0] undecene-7 (DBU) And tertiary amine compounds such as triethylenediamine, benzyldimethylamine, and triethanolamine. Of these, 2,4-diamino-6- [2'-methylimidazolyl- (1 ')] ethyl-s-triazine and 2-phenyl-4-methylimidazole are preferable. Examples of the phosphorus curing accelerator include triphenylphosphine, tributylphosphine, tri (p-methylphenyl) phosphine, tri (nonylphenyl) phosphine, and the like. A hardening accelerator may be individual or may use 2 or more types together.

  The die attach agent of the present invention may contain a diluent in order to improve applicability and the like. Diluents include ethers such as butyl carbitol acetate, ethylene glycol monoethyl ether, ethylene glycol monoethyl ether acetate, ethylene glycol monobutyl ether, ethylene glycol monomethyl ether, diethylene glycol monobutyl ether, and ketones such as methyl ethyl ketone and methyl isobutyl ketone. , Aromatic solvents such as toluene and xylene, high boiling solvents such as dioctyl phthalate and dibutyl phthalate, monofunctional aromatic glycidyl ethers such as γ-butyrolactone, phenyl glycidyl ether and cresyl glycidyl ether, aliphatic glycidyl ethers, etc. Is mentioned. The usage-amount of a diluent is not specifically limited, For example, it can be 0.5-10 mass% in die attach agents.

  The die attach agent of the present invention can have a viscosity of 8 to 60 Pa · s, preferably 8 to 50 Pa · s, and more preferably 9 to 40 Pa · s. In this specification, the viscosity is a value measured using an E-type viscometer (3 ° cone) at 25 ° C. and at a rotation speed of 5 rpm.

  The die attach agent of the present invention can be applied to a lead frame, a substrate, etc., and a semiconductor element, a heat radiating member, etc. can be mounted, heat cured, and bonded. Conditions for heat curing can be appropriately selected, and for example, heating can be performed at a peak temperature of 100 to 200 ° C. Next, the semiconductor device can be obtained by sealing through wire bonding. This semiconductor device can be mounted on a printed wiring board by soldering to form various electronic components. The die attach agent of this invention is excellent in adhesive strength. Furthermore, even when the support member is a copper lead frame or a copper substrate, these effects can be further exhibited and the utility is high.

  Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples. Unless otherwise indicated, parts and% represent parts by mass and% by mass. The present invention is not limited by these examples.

The measurement methods in the examples are as follows.
(Specific surface area)
It measured with the BET specific surface area measuring apparatus.
(Tap density)
Measured according to JIS Z 2512 metal powder-tap density measurement method.
(viscosity)
This is a value measured at 25 ° C. at a predetermined rotational speed using an E-type viscometer (3 ° cone).
(Volume resistivity)
The paste was applied to a slide glass with a width of 3 mm and a thickness of 50 μm, heated from room temperature (25 ° C.) to 160 ° C. in 30 minutes and held in an oven at 160 ° C. for 60 minutes to cure, and then the volume resistance of the cured product The rate is a value measured by the 4-terminal method.
(Thermal conductivity)
Each agent of Examples and Comparative Examples was heated from room temperature (25 ° C.) to 160 ° C. in 30 minutes, and kept in an oven at 160 ° C. for 60 minutes to cure to produce a film-like cured product. NETZSCH It is a value measured by a laser flash method using a manufactured LFA447 Nanoflash device.
(Die shear strength)
A silicon chip of 5 mm × 5 mm was mounted on a copper lead frame using each of the examples and comparative examples, heated from room temperature (25 ° C.) to 160 ° C. in 30 minutes, and placed in a 160 ° C. oven. Hold for minutes to cure. It is the value measured at room temperature (25 ° C.) using a Dage shear tester manufactured by Dage after curing.

  In Examples and Comparative Examples, additives, imidazole curing accelerators, and diluents were added to a container in the amounts shown in Table 1, and stirred for 2 minutes with a rotating / revolving stirrer (Shinky Awatori Nertaro). Add the epoxy resin, curing agent and silane coupling agent to this solution and stir and mix for about 1 minute with a rotating / revolving stirrer until the solution becomes a completely transparent liquid. The resin component of was adjusted. Silver powder was added to this resin component and dispersed with a self-revolving stirrer for 30 seconds, and then degassed under reduced pressure to prepare a paste-like die attach agent. The properties were measured for each agent. The results are shown in Table 1.

  A die attach paste was prepared in the same manner as in Example 1 except that the amount of the additive dithiodipropionic acid was changed, and the additive amount, volume resistivity, thermal conductivity, and die shear strength were determined. FIG. 1 is a diagram showing the relationship between the addition amount and volume resistivity / thermal conductivity, and FIG. 2 is a diagram showing the relationship between the addition amount and die shear strength.

  As is clear from the comparison between Examples 1 to 6 and Comparative Examples 1 to 3, each agent of Examples containing dithiodiglycolic acid and dithiodipropionic acid in specific amounts has low volume resistivity and thermal resistivity. In addition, it had high die share strength. On the other hand, Comparative Examples 4 and 5 using an aliphatic dicarboxylic acid having no sulfide bond as an additive had a high volume resistivity, and Comparative Example 4 had a low die shear strength. Comparative Examples 6 and 7 using an aliphatic dicarboxylic acid having a sulfide bond (-S-) instead of a disulfide bond as an additive also had a low die shear strength, and Comparative Example 6 did not reach the examples in volume resistivity. . The comparative example 8 which used the aliphatic monocarboxylic acid which has a sulfide bond (-S-) instead of a disulfide bond as an additive did not reach the Example in the point of volume resistivity and die shear strength. Comparative Example 9 using an aromatic dicarboxylic acid having a disulfide bond had an extremely high volume resistivity and a low thermal conductivity. Comparative Examples 10 to 13 using a sulfur-containing silane coupling agent instead of the additive did not reach the examples in terms of volume resistivity, and the thermal conductivity was generally low, and as shown in Comparative Example 11 When dithiodipropionic acid was used in combination, the thermal conductivity decreased rather. Comparative Example 14 lacking the silane coupling agent had a low die shear strength.

  According to the die attach agent of the present invention, while maintaining a low volume resistivity, it is possible to improve both the adhesive strength, in particular, the adhesive strength at the time of reflow and the thermal conductivity. high.

Claims (7)

(A) epoxy resin,
(B) Silver powder,
A die attach agent comprising (C) an aliphatic dicarboxylic acid compound containing a disulfide bond, and (D) a silane coupling agent, wherein (C) is 0.08 to 0.65% by mass in the die attach agent.   The die attach agent according to claim 1, wherein (C) is dithiodiglycolic acid and / or dithiodipropionic acid.   In a die attach agent, (A) is 3.5-19 mass%, (B) is 80-96 mass%, and (D) is 0.05-0.5 mass%. The die attach agent according to 1 or 2.   The die attach agent according to any one of claims 1 to 3, further comprising a curing agent.   The die attach agent of Claim 4 whose hardening | curing agent is 0.01-2 mass% in a die attach agent.   The semiconductor device produced using the die attach agent of any one of Claims 1-5.   The semiconductor device of Claim 6 whose surface to which the die attach agent of any one of Claims 1-5 is applied is copper.

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