WO2019111778A1 - Pasty adhesive composition and semiconductor device - Google Patents

Abstract

The pasty adhesive composition of an embodiment according to the present invention comprises an epoxy resin and silver particles and, upon a heat treatment, comes to have connected-silver-particle structures each formed therein from two or more of the silver particles with the disappearance of the interfaces therebetween. When the pasty adhesive composition is applied to a copper lead frame in a thickness of 25±10 μm, subsequently a bare silicon wafer having a length of 2 mm and a width of 2 mm is placed on the pasty adhesive composition to obtain a stack, and the stack is heated in the air from 25°C to 175°C over 30 minutes and then held at 175°C for 30 minutes to thereby obtain a cured layer, then the bare silicon and the copper lead frame have a strength in shearing across the cured layer, as measured at a temperature of 260°C, of 5.0-15.0 MPa.

Description

Paste-like adhesive composition and semiconductor device

The present invention relates to a paste-like adhesive composition and a semiconductor device.

Conventionally, two types of paste-like adhesive compositions of a binder type and a sintering type have been used for paste-like adhesive compositions used for bonding of respective members of semiconductor devices and electric and electronic parts.

The binder type paste adhesive composition is a composition in which conductive metal particles such as silver particles are dispersed in a liquid thermosetting resin, and the metal particles are pressure-bonded by curing of the resin by heating. The adhesive composition ensures conductivity and heat conductivity.
In the binder-type paste-like adhesive composition, the liquid thermosetting resin is cured to develop adhesion and adhesion to the adherend. Furthermore, since the paste-like adhesive composition shrinks upon curing, the frequency with which the metal particles come in contact with each other increases, and the contact points between the metal particles increase, as compared to before curing. Thereby, the hardened | cured material of a paste-form adhesive composition expresses electroconductivity and thermal conductivity.
In the binder type paste-like adhesive composition, the thermosetting resin after curing adheres to the adherend. Therefore, such a binder-type paste-like adhesive composition has adhesiveness not only to metals such as copper, silver, gold, nickel, and palladium but also to adherends other than metals such as bare silicon. . On the other hand, in the binder type paste-like adhesive composition, the metal particles are in contact with each other through the cured product of the thermosetting resin. For this reason, the binder type paste-like adhesive composition has a case where the contact area between silver particles is smaller than that of the sintering type and the heat conductivity may be inferior.

The paste type adhesive composition of sintering type is a composition in a form in which metal particles are dispersed in a volatile dispersion medium, and the dispersion medium is volatilized by heat treatment and the metal particles are sintered to ensure continuity. Adhesive composition.
In the sintering type paste-like adhesive composition, volatilization of the dispersion medium by heating causes the metal particles dispersed therein to aggregate. Furthermore, due to the action of heat, the interface between the metal particles in the aggregate disappears, in other words, the metal particles are sintered to form a metal particle connection structure. In the paste type adhesive composition of sintering type, the dispersion medium is not completely volatilized, but the monomer contained in the dispersion medium remains in a small amount without volatilizing, and the remaining monomer is And act to adhere the metal particle connection structure to the adherend. In addition, the volatilization of the dispersion causes an attractive force between the connected structure of metal particles and the adherend, and these are joined. In the case where the adherend is a metal such as silver or gold, the interface between the metal particle and the adherend disappears and adheres firmly.
The paste type adhesive composition of sintering type can express high thermal conductivity compared with the binder type adhesive by forming a metal particle connection structure. On the other hand, when a sintering type paste-like adhesive composition is used as an adhesive, a monomer remains between the metal particle connection structure generated by heating and the adherend, but this monomer Since the amount is small, the adhesion between the metal particle connection structure and the adherend may not be sufficiently obtained. In addition, the adhesion between the adherend and the metal particle is influenced by the type and combination of the metal material and the metal particles that constitute the adherend, so that the compatibility between the material of the adherend and the metal particle is not good. The adhesion between the adherend and the metal particle connection structure is weak, and peeling may occur between them.

For example, Patent Document 1 describes a binder-type pasty adhesive composition. Patent Document 1 contains a specific acrylic resin, a radical initiator, a specific silver fine particle, a specific silver powder, and a solvent, so that the heat dissipation property is excellent, and further, the semiconductor element is good as a metal substrate. A thermosetting resin composition for semiconductor adhesion which can be bonded to the above is described.

Further, for example, Patent Document 2 describes a sintering-type paste-like adhesive composition. Patent Document 2 discloses that the adhesion to a substrate, the solder wettability, the migration resistance, the oxidation resistance, and the electrical bondability can be achieved by using a specific alloy powder, a glass frit, and an organic vehicle. The paste which it has is described.

JP, 2014-074132, A Japanese Patent Application Publication No. 06-139813

The present inventors have demonstrated reliability such as connection reliability and mounting reliability for a semiconductor device in which a lead frame of copper, silver, gold or the like is connected to bare silicon via a paste-like adhesive composition. -The heat dissipation such as Chip thermal diffusivity was examined. As a result, it was found that the thermosetting resin composition for semiconductor adhesion described in Patent Document 1 does not have sufficient heat dissipation, and the paste described in Patent Document 2 does not have sufficient adhesiveness to an adherend.
Therefore, an object of the present invention is to provide a paste-like adhesive composition that can be suitably used to manufacture a semiconductor device in which both reliability and heat dissipation are improved in a well-balanced manner. .

The inventors have found that conventional binder types and sintering types can be used to obtain conductive pastes that have good adhesion to both bare silicon and metal and that the cured product has excellent thermal conductivity. It was considered to make a paste-like adhesive composition of the hybrid type. As a result, it is a paste-like adhesive composition containing an epoxy resin and silver particles, and the silver particles form a silver particle connection structure by heat treatment, and the paste-like adhesive composition is applied at a coating thickness of 25 ±. The laminate is coated to a thickness of 10 μm on a copper lead frame, and then a 2 mm long × 2 mm wide bare silicon wafer is placed on the paste-like adhesive composition to obtain a laminate, and then the laminate is When a cured product is obtained by raising the temperature from 25 ° C. to 175 ° C. over 30 minutes in the atmosphere and then keeping the temperature at 175 ° C. for 30 minutes, the above curing is measured at a temperature of 260 ° C. The inventors have found that the above problems can be solved by using an adhesive composition in which the shear strength between the bare silicon and the copper circuit through the body is within a specific numerical range. Specifically, it has been found that by using such a composition, it is possible to suppress peeling between the cured product of the paste-like adhesive composition and the adherend. Therefore, the hybrid adhesive paste composition can exhibit suitable adhesion to various materials such as bare silicon and metal, like the binder adhesive paste composition.
Moreover, the paste type adhesive agent composition of a hybrid type can improve heat dissipation like a paste type adhesive agent composition of sintering type by forming a silver particle connection structure.
From the above, the inventor has found that the reliability and the heat dissipation can be improved when the shear strength between the bare silicon and the copper circuit falls within a specific numerical range, and a hybrid type paste adhesive composition is used. An invention has been completed.

According to the invention
Epoxy resin,
Containing silver particles,
A paste-like adhesive composition, wherein the silver particles form a silver particle linked structure by heat treatment,
The paste adhesive composition is applied on a copper lead frame so that the coating thickness is 25 ± 10 μm, and then a bare silicon wafer of 2 mm in length × 2 mm in width is disposed on the paste adhesive composition. The laminate is then heated in the atmosphere from temperature 25 ° C. to 175 ° C. over 30 minutes, and then kept at 175 ° C. for 30 minutes to obtain a cured product. A paste-like adhesive composition having a shear strength of 5.0 MPa or more and 15.0 MPa or less between the bare silicon via the cured body and the copper lead frame measured at a temperature of 260 ° C. when obtained. Is provided.

Moreover, according to the present invention,
A substrate,
A semiconductor element mounted on the substrate via an adhesive layer,
A semiconductor device is provided, wherein the adhesive layer is formed by curing the paste adhesive composition.

The present invention provides a paste-like adhesive composition which improves the reliability and heat dissipation of a semiconductor device using the paste-like adhesive composition in a well-balanced manner.

The objects described above, and other objects, features and advantages will become more apparent from the preferred embodiments described below and the following drawings associated therewith.

FIG. 1 is a cross-sectional view showing an example of a semiconductor device according to the present embodiment. FIG. 1 is a cross-sectional view showing an example of a semiconductor device according to the present embodiment. It is a result of cross-sectional observation using a scanning electron microscope about the semiconductor device using the paste-form adhesive composition of Example 1. FIG. It is a result of cross-sectional observation using a scanning electron microscope about the semiconductor device using the paste-like adhesive composition of the comparative example 3. FIG.

Hereinafter, the present embodiment will be described using drawings as appropriate. In all the drawings, the same components are denoted by the same reference numerals and the description thereof will be omitted.

The paste-like adhesive composition according to the present embodiment includes an epoxy resin and silver particles, and is heat-treated to form a silver particle connection structure in which the interface between the plurality of silver particles disappears. An adhesive composition, wherein the paste-like adhesive composition is applied on a copper lead frame so as to have an applied thickness of 25 ± 10 μm, and then a bare silicon wafer of 2 mm in length × 2 mm in width is applied to the paste The laminate is placed on the adhesive composition to obtain a laminate, and then the laminate is heated from 25.degree. C. to 175.degree. C. in the atmosphere over 30 minutes, and further at 175.degree. C. for 30 minutes The shear strength of the above-mentioned bare silicon via the above-mentioned hardening object and the above-mentioned copper circuit which are measured at a temperature of 260 ° C is 5.0MPa or more and 15.0MPa or less. .

The inventor of the present invention has improved the conventional binder type and the sintering type in order to improve the heat dissipating properties such as adhesion reliability, mounting reliability and chip-chip thermal diffusivity in a well-balanced manner for the paste-like adhesive composition. It was considered to make a paste-like adhesive composition of the hybrid type with As a result, when a bare silicon wafer and a copper lead frame are laminated via the paste adhesive composition and the paste adhesive composition forming the silver particle connection structure is cured by heat treatment, the shear strength is specific. It has been found that it is preferable to be within the numerical range. Thereby, when hardening a paste-like adhesive composition, heat dissipation can be improved by forming silver particle connection structure. Furthermore, when the shear strength is within the specific numerical range, it is possible to improve reliability such as adhesion reliability and mounting reliability while improving heat dissipation.
As described above, the paste-like adhesive composition according to the present embodiment can improve the reliability and heat dissipation of the semiconductor device using the paste-like adhesive composition in a well-balanced manner.

In this embodiment, for example, by appropriately selecting the raw material components contained in the paste-like adhesive composition, it is possible to control the shear strength within a specific numerical range while forming a silver particle connection structure. It is. As controlling factors, specifically, the shape and content of silver particles should be properly selected; the particle size profile of silver particles such as average particle diameter, specific surface area, tap density etc. should be appropriately selected; as main agent Containing an epoxy resin; controlling the balance between the content of the main ingredient and the content of the silver particles; a single substance which only volatilizes without causing a curing reaction at all when the paste adhesive composition is cured. The thing which does not contain a monomer etc. is mentioned.
Although the detailed mechanism is not clear, it is presumed that the epoxy resin remains at the interface of silver particles by appropriately controlling the above factors. Thereby, a shear strength can be made into a specific range by interposing the hardened | cured material of an epoxy resin between silver particle connection structure and a to-be-adhered body. In addition, when the epoxy resin is excessively present at the interface of the silver particles of the paste-like adhesive composition, there is a disadvantage that a silver particle linked structure can not be formed. However, the paste-like adhesive composition according to the present embodiment can form a silver particle connection structure by uniformly dispersing an epoxy resin at the interface of silver particles.
Furthermore, by appropriately controlling the above factors, it is presumed that silver particles attract each other appropriately. Thereby, silver particle connection structure can be formed appropriately. In addition, when the content of the epoxy resin in the paste-like adhesive composition is large as in a binder-type paste-like adhesive composition, curing of the paste-like adhesive composition occurs when silver particles attract each other excessively. Things shrink excessively. Thereby, the interface between the cured product of the paste-like adhesive composition and the adherend is broken due to shrinkage, and the shear strength does not fall within the desired numerical range. However, the paste-like adhesive composition according to the present embodiment does not cause breakage of the paste-like adhesive composition due to shrinkage because silver particles attract each other appropriately.

Hereinafter, each raw material component of the paste-like adhesive composition which concerns on this embodiment is demonstrated.

(Silver particles)
The paste-like adhesive composition according to the present embodiment contains silver particles.
In the paste-like adhesive composition according to the present embodiment, when the epoxy resin as a main ingredient described later is cured, attractive force is generated between the silver particles, and the silver particles collide with each other. Thereby, the interface between the silver particles disappears, and the heat radiation property can be improved by forming a silver particle connection structure having high thermal conductivity.
That is, the paste-like adhesive composition according to the present embodiment is, for example, a hybrid that forms a silver particle connection structure by appropriately controlling factors such as the properties of silver particles in a binder-type paste-like adhesive composition. It is a pasty adhesive composition of the type.
In the present embodiment, the silver particle linked structure indicates a structure in which silver particles collide with each other and an interface disappears.

Although the silver particle connection structure is not limited, for example, it is preferable that the lower limit value of the chip-chip thermal diffusivity measured using a gold-plated silicon chip is, for example, 0.27 cm ² / sec or more. , and the are more preferred silver particle coupling structure is made with 0.30 cm ² / sec or more, and the silver particles connection structure is further preferable that the 0.35 cm ² / sec or more, 0.37 cm ² / sec or more The more preferable one is a silver particle linked structure.
Further, the upper limit value of the chip-chip thermal diffusivity measured using a gold-plated silicon chip is not limited, but may be, for example, 1.0 cm ² / sec or less.
In addition, as a measuring method of the chip-chip thermal diffusivity using a gold plating silicon chip, Ti, Ni, and Au were plated in this order with respect to the silicon chip of length 10 mm x width 10 mm x thickness 350 micrometers, for example Two gold-plated silicon chips are prepared, and then the paste adhesive composition is applied to one silicon chip to a thickness of 25 ± 10 μm, the other silicon chip is laminated thereon, and then the temperature is Is raised from 25.degree. C. to 175.degree. C. over 30 minutes and then heat treated at 175.degree. C. for 60 minutes to cure the paste-like adhesive composition into a cured product, and then gold-plated silicon chip, paste-like adhesive Thermal diffusion is performed using a laser flash method on a test piece formed by laminating a cured product of the composition and a gold-plated silicon chip in this order. A method of measuring the coefficients can be used.

Specifically, the shape of the silver particles may include flakes or spheres. The silver particles preferably include, for example, at least those in the form of flakes, and it is more preferable to use, for example, those in the form of flakes and spheres in combination. That is, as silver particles, for example, it is more preferable to include flake-shaped flake-like silver particles and spherical-shaped spherical silver particles together. This is preferable from the viewpoint of attracting silver particles appropriately.

The particle size profiles of the spherical silver particles and the flaky silver particles according to this embodiment will be described below.

(Flake-like silver particles)
The upper limit value of the average particle diameter of the flaky silver particles is, for example, preferably 6.0 μm or less, more preferably 5.0 μm or less, and still more preferably 4.0 μm or less. It is more preferable to set it to 0 μm or less, and it is particularly preferable to set it to 2.5 μm or less. Thereby, the silver particles can be easily attracted to each other, and the silver particle connected structure can be appropriately formed. In addition, the silver particles are not present at the interface between the paste-like adhesive composition and the adherend, and the internal stress is generated at the interface to break the cured product of the paste-like adhesive composition. It is convenient also from the viewpoint that it can control.
The lower limit value of the average particle diameter of the flaky silver particles is, for example, preferably 0.5 μm or more, more preferably 0.7 μm or more, and still more preferably 1.0 μm or more. More preferably, it is 1.5 μm or more. This is advantageous in that the silver particles can be prevented from attracting each other excessively.

In the lower limit of the specific surface area of flaked silver particles, for example, it is preferably 0.40 m ² / g or more, more preferably 0.60 m ² / g or more, 0.80 m ² / g or more more preferably in, more preferably at 1.00 m ² / g or more, and especially preferably 1.09 M ² / g or more. In the conventional paste-like adhesive composition, it was difficult for the flake-like silver particles to attract each other only by the curing shrinkage of the main agent, and it was difficult to form a silver particle connected structure. When the specific surface area is equal to or more than the above lower limit value, the silver particles can be easily attracted to each other, and a silver particle connected structure can be appropriately formed.
Further, the upper limit value of the specific surface area of the flaky silver particles may be, for example, 2.00 m ² / g or less, or 1.50 m ² / g or less.
When both flaked silver particles and spherical silver particles are contained as silver particles, the specific surface area of the flaked silver particles is preferably, for example, larger than that of spherical silver particles. Thereby, silver particles can attract each other appropriately.

The upper limit value of the tap density of the flaky silver particles is, for example, preferably 5.4 g / cm ³ or less, more preferably 5.0 g / cm ³ or less, and 4.5 g / cm ³ or less It is further preferred that Thereby, when it contains together flaky silver particle and spherical silver particle, spherical silver particle can be suitably made to penetrate into the crevice of flaky silver particle. Therefore, the silver particles can be attracted to each other appropriately, and furthermore, the epoxy resin can be suitably retained and dispersed at the interface of the silver particles.
The lower limit value of the tap density of the flaky silver particles may be, for example, 1.0 g / cm ³ or more, 2.0 g / cm ³ or more, or 3.0 g / cm ³ or more.

(Spherical silver particles)
In addition to the flaky silver particles described above, the silver particles according to the present embodiment preferably include, for example, spherical silver particles. Thereby, spherical silver particles can penetrate into the gaps of the flaky silver particles while the main agent and the monomer are present. Therefore, the silver particles can be appropriately attracted to each other while the epoxy resin is uniformly dispersed at the interface of the silver particles.

The lower limit value of the average particle diameter of the spherical silver particles is, for example, preferably 0.1 μm or more, more preferably 0.4 μm or more, and still more preferably 0.7 μm or more. Thereby, it can suppress that silver particles mutually attract excessively.
The upper limit value of the average particle diameter of the spherical silver particles is, for example, preferably 5.0 μm or less, more preferably 4.0 μm or less, and still more preferably 3.0 μm or less. The thickness is more preferably not more than 0 μm, and particularly preferably not more than 1.5 μm. Thus, when the flake-like silver particles and the spherical silver particles are contained together, the spherical silver particles can suitably penetrate between the flake-like silver particles. Therefore, silver particles can be attracted appropriately.

The lower limit of the specific surface area of spherical silver particles, for example, is preferably 0.30 m ² / g or more, more preferably 0.50 m ² / g or more, is 0.70 m ² / g or more Is more preferably 0.90 m ² / g or more. Thereby, silver particles can attract each other appropriately.
The upper limit value of the specific surface area of the spherical silver particles may be, for example, 2.10 m ² / g or less, or 1.60 m ² / g or less.

When the flaked silver particles and the spherical silver particles are both contained as silver particles, the upper limit value of the content of the flaked silver particles in the silver particles is 100 parts by mass in total of the flaked silver particles and the spherical silver particles. For example, the amount is preferably 60 parts by mass or less, more preferably 50 parts by mass or less, still more preferably 40 parts by mass or less, and still more preferably 30 parts by mass or less. Thereby, spherical silver particles infiltrate into the gaps of the flaky silver particles, and the silver particles are attracted to each other suitably.
When the flaked silver particles and the spherical silver particles are both contained as silver particles, the lower limit value of the content of the flaked silver particles in the silver particles is 100 parts by mass in total of the flaky silver particles and the spherical silver particles. On the other hand, for example, the content is preferably 5 parts by mass or more, more preferably 10 parts by mass or more, still more preferably 15 parts by mass or more, and still more preferably 20 parts by mass or more. Thereby, an epoxy resin can penetrate suitably into the interface of silver particles.

The lower limit value of the content of silver particles in the paste adhesive composition is, for example, preferably 50 parts by mass or more, and 60 parts by mass or more with respect to 100 parts by mass of the paste adhesive composition. It is more preferably 70 parts by mass or more, still more preferably 80 parts by mass or more, and particularly preferably 82 parts by mass or more. The attraction between the silver particles produced by the curing of the main agent is, for example, smaller than the attraction among the silver particles produced by the volatilization of the monomer. However, when the content of the silver particles is not less than the above lower limit, even if the attractive force between the silver particles is small, the components of the paste-like adhesive composition do not volatilize, and the silver particle bonded structure is suitably obtained. It can be formed.
The upper limit of the content of silver particles in the paste-like adhesive composition is, for example, preferably 90 parts by mass or less, and 87 parts by mass or less with respect to 100 parts by mass of the paste-like adhesive composition. Is preferred. Thereby, the epoxy resin suitably remains and disperses at the interface of the silver particles.

(Epoxy resin)
The pasty adhesive composition according to the present embodiment contains at least an epoxy resin such as an epoxy oligomer or an epoxy polymer as a main ingredient.
Moreover, the paste-like adhesive composition which concerns on this embodiment may also further contain resin other than an epoxy resin. Specific examples of the resin other than the epoxy resin include acrylic resins such as acrylic oligomers and acrylic polymers; and allyl resins such as allyl oligomers and allyl polymers.
The paste-like adhesive composition according to this embodiment cures and shrinks due to the curing of the main agent. This curing shrinkage can create an attractive force between silver particles to form a silver particle linked structure. Therefore, the heat dissipation can be improved.
The epoxy resin can react with a curing agent described later to cure and shrink. In addition, the curing reaction of an epoxy resin entrains an epoxy monomer, for example, when it contains an epoxy monomer as a monomer.
In addition, the acrylic resin can be polymerized and shrunk by the radical polymerization initiator described later. In addition, polymerization of an acrylic resin, for example, in the case of containing an acrylic monomer as a monomer, occurs by rolling in the acrylic monomer.
The allyl resin can be polymerized and shrunk by a radical polymerization initiator described later, as with the acrylic resin. The polymerization of the allyl resin takes place by incorporating an acrylic resin, an acrylic monomer, and an allyl monomer.
In the present embodiment, among the multimers, those having a weight average molecular weight of less than 10,000 are shown as oligomers, and those having a weight average molecular weight of 10,000 or more as a polymer. In addition, the term "resin" refers to including oligomers and polymers.

〔Epoxy resin〕
As the epoxy resin, a liquid epoxy resin having two or more epoxy groups in one molecule can be used.
Specific examples of the epoxy resin include trisphenol methane epoxy resin; hydrogenated bisphenol A liquid epoxy resin; bisphenol F liquid epoxy resin such as bisphenol-F-diglycidyl ether; ortho cresol novolac epoxy resin, etc. It can be mentioned. As an epoxy resin, it can be used combining 1 type, or 2 or more types among the said specific examples. Among the above specific examples, the epoxy resin preferably contains a hydrogenated bisphenol A liquid epoxy resin or a bisphenol F liquid epoxy resin, and more preferably contains a bisphenol F liquid epoxy resin. Thereby, the handling property of the paste-like adhesive composition can be improved, and the paste-like adhesive composition can be applied uniformly, so that the reliability can be improved. Moreover, since a paste-like adhesive composition can be cure-contracted suitably, it is preferable also from a viewpoint which can form a suitable silver particle connection structure and can improve heat dissipation. Furthermore, it is also preferable from the viewpoint that an epoxy resin suitably remains and disperses at the interface of silver particles.

〔acrylic resin〕
As an acrylic resin, the liquid thing which has 2 or more of acrylic groups in 1 molecule can be used.
Specifically as an acrylic resin, what polymerized or copolymerized the acrylic monomer described in the term of the monomer mentioned later can be used. Here, the method of polymerization or copolymerization is not limited, and a known method using a general polymerization initiator and a chain transfer agent such as solution polymerization can be used. In addition, as an acrylic resin, you may use individually by 1 type, and may use 2 or more types from which a structure differs.

[Allyl resin]
As an allyl resin, the liquid thing which has 2 or more of allyl groups in 1 molecule can be used.
Specific examples of allyl resins include allyl ester resins obtained by reacting a dicarboxylic acid, allyl alcohol, and a compound having an allyl group.
Here, as the dicarboxylic acid, specifically, oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, maleic acid, fumaric acid, phthalic acid, Tetrahydrophthalic acid, hexahydrophthalic acid and the like can be mentioned. As a dicarboxylic acid, it can be used combining 1 type, or 2 or more types among the said specific examples.
Specific examples of the compound having an allyl group include polyethers having an allyl group, polyesters, polycarbonates, polyacrylates, polymethacrylates, polybutadienes, butadiene acrylonitrile copolymers, and the like. As the compound having an allyl group, one or more of the above specific examples can be used in combination.

The lower limit value of the content of the main agent in the paste-like adhesive composition is, for example, preferably 1 part by mass or more, and 3 parts by mass or more with respect to 100 parts by mass of the paste-like adhesive composition. Is more preferable, and more preferably 5 parts by mass or more. As a result, the main agent is suitably cured and shrunk to form a silver particle linked structure, and suitable adhesion to an adherend can be expressed. Therefore, the shear strength can be controlled within the numerical range described later.
In addition, the upper limit value of the content of the main agent in the paste adhesive composition is, for example, preferably 20 parts by mass or less, and 15 parts by mass or less with respect to 100 parts by mass of the paste adhesive composition. The content is more preferably 14 parts by mass or less. Thereby, it is possible to suppress that an excess of the main agent gets in between the silver particles and prevents the formation of the silver particle linked structure.

(Other ingredients)
The paste-like adhesive composition according to the present embodiment contains, for example, a monomer, a radical polymerization initiator, a curing agent, a curing accelerator, a low stress agent, a silane coupling agent and the like in addition to the above-described raw material components. be able to.
The representative components will be described below.

(Monomer)
The pasty adhesive composition according to the present embodiment may further include, for example, a monomer. The monomer which concerns on this embodiment hardens-contracts by heat processing.
Specifically as such a monomer, an acrylic monomer, an epoxy monomer, a maleimide monomer etc. can be mentioned. As the monomer, one or more of the above specific examples can be used in combination.
The acrylic monomer and maleimide monomer are polymerized by a radical polymerization initiator described later.
The epoxy monomer can react with a curing agent described later to cure and shrink.
In the present embodiment, it is important to control the shear strength within a specific numerical range while forming a silver particle linked structure while not polymerizing by heat treatment and containing no volatile monomer. Thereby, the amount of residual resin after curing in the paste-like adhesive composition can be increased, and the shear strength can be improved. Therefore, when containing an acrylic monomer or a maleimide monomer as a monomer, the pasty adhesive composition further contains a radical polymerization initiator. Moreover, when it contains an epoxy monomer as a monomer, a paste-form adhesive composition contains a hardening | curing agent.
In addition, it is preferable to use together the main ingredient mentioned above and a monomer. As a result, the molecular weight of the resin component such as the main agent and the monomer is reduced to improve the dispersibility, and a part of the monomer is cured and a part is volatilized to make the silver particles strong. You can attract each other.

Acrylic monomer
The acrylic monomer according to the present embodiment is a monomer having a (meth) acrylic group in its structure. Here, a (meth) acrylic group shows an acryl group and a methacryl group (methacrylate group).
The acrylic monomer according to the present embodiment may be a monofunctional acrylic monomer having only one (meth) acrylic group in its structure, or a multifunctional having two or more (meth) acrylic groups in its structure. It may be an acrylic monomer.
In the present embodiment, the acrylic group contains an acrylate group.

Specific examples of monofunctional acrylic monomers 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 (meth) acrylate, butoxydiethylene glycol (meth) acrylate, methoxytriethylene glycol (meth) acrylate, 2-ethylhexyl diethylene glycol (meth) acrylate Salts, methoxy polyethylene glycol (meth) acrylate, methoxy dipropylene glycol (meth) acrylate, cyclohexyl (meth) acrylate, tetrahydrofurfuryl (meth) acrylate, benzyl (meth) acrylate, phenoxyethyl (meth) acrylate, phenoxy diethylene glycol ( Meta) acrylate, phenoxy polyethylene glycol (meth) acrylate, nonyl phenol ethylene oxide modified (meth) acrylate, phenyl phenol ethylene oxide modified (meth) acrylate, isobornyl (meth) acrylate, dimethylaminoethyl (meth) acrylate, diethylaminoethyl (meth) acrylate, Dimethylaminoethyl (meth) acrylate quaternary, glycidyl ) Acrylate, neopentyl glycol (meth) acrylic acid benzoate, 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) acryloyloxyethylsuccinic acid, 2- (meth) acryloyloxyethylsuccinic acid, 2- (meth) acryloyloxyethylhexahydro Phthalic acid, 2- (meth) acryloyloxyethyl hexahydrophthalic acid, 2- (meth) acryloyloxyethyl phthalic acid, 2- (meth) acryloyloxyethyl-2-hydroxyethyl phthalic acid, 2- (meth) acryloyl acid Examples include oxyethyl acid phosphate, 2- (meth) acryloyloxyethyl acid phosphate and the like. As a monofunctional acrylic monomer, it can be used combining 1 type, or 2 or more types among the said specific examples.
In the present embodiment, (meth) acrylate indicates acrylate and methacrylate. Moreover, methacrylic acid shows acrylic acid and methacrylic acid. Moreover, (meth) acryloyl shows acryloyl and methacryloyl.

Specific examples of polyfunctional acrylic monomers include ethylene glycol di (meth) acrylate, trimethylolpropane tri (meth) acrylate, propoxylated bisphenol A di (meth) acrylate, hexane-1,6-diol bis (2-methyl) (Meth) acrylate), 4,4′-isopropylidene diphenol di (meth) acrylate, 1,3-butanediol di (meth) acrylate, 1,6-bis ((meth) acryloyloxy) -2,2,2, 3,3,4,4,5,5-octafluorohexane, 1,4-bis ((meth) acryloyloxy) butane, 1,6-bis ((meth) acryloyloxy) hexane, triethylene glycol di (meth) ) Acrylate, neopentyl glycol di (meth) acrylate, neopen Glycol di (meth) acrylate, N, N'-di (meth) acryloyl ethylenediamine, N, N '-(1,2-dihydroxyethylene) bis (meth) acrylamide, or 1,4-bis ((meth) acryloyl) ) Piperazine and the like.

[Epoxy monomer]
The epoxy monomer which concerns on this embodiment equips the structure with an epoxy group.
The epoxy monomer according to the present embodiment may be a monofunctional epoxy monomer having only one epoxy group in its structure, or may be a polyfunctional epoxy monomer having two or more epoxy groups in its structure. Good.

Specific examples of monofunctional epoxy monomers include 4-tert-butylphenyl glycidyl ether, m-cresyl glycidyl ether, p-cresyl glycidyl ether, phenyl glycidyl ether, cresyl glycidyl ether and the like. As a monofunctional epoxy monomer, it can be used combining 1 type, or 2 or more types among the said specific examples.

Specifically as a polyfunctional epoxy monomer, bisphenol compounds, such as bisphenol A, bisphenol F, biphenol, or these derivatives; Hydrogenated bisphenol A, hydrogenated bisphenol F, hydrogenated biphenol, cyclohexanediol, cyclohexane dimethanol, A diol having an alicyclic structure such as dirohexanediethanol or a derivative thereof; an aliphatic diol such as butanediol, hexanediol, octanediol, nonanediol, decanediol or the like, or a bifunctional epoxidized derivative thereof; tri Hydroxyphenylmethane skeleton, trifunctional one having aminophenol skeleton; phenol novolak resin, cresol novolac resin, phenol aralkyl resin, biphenyl Aralkyl resins, and the naphthol aralkyl resin as polyfunctional epoxidized. As a polyfunctional epoxy monomer, it can be used combining 1 type, or 2 or more types among the said specific examples.

[Maleimide monomer]
The maleimide monomer according to the present embodiment has a maleimide ring in its structure.
The maleimide monomer according to the present embodiment may be a monofunctional maleimide monomer having only one maleimide ring in its structure, or a polyfunctional maleimide monomer having two or more maleimide rings in its structure, It is also good.
Specific examples of maleimide monomers include polytetramethylene ether glycol-di (2-maleimidoacetate).

(Radical polymerization initiator)
Specifically as a radical polymerization initiator, an azo compound, a peroxide, etc. can be used. As a radical polymerization initiator, it can be used combining 1 type, or 2 or more types among the said specific examples. Among the above specific examples, it is preferable to use, for example, a peroxide as the radical polymerization initiator.

Specific examples of the peroxide include bis (1-phenyl-1-methylethyl) peroxide, 1,1-bis (1,1-dimethylethylperoxy) cyclohexane, methyl ethyl ketone peroxide, cyclohexane peroxide, and acetylacetone Peroxide, 1,1-di (tert-hexylperoxy) cyclohexane, 1,1-di (tert-butylperoxy) -2-methylcyclohexane, 1,1-di (tert-butylperoxy) cyclohexane, 2 , 2-Di (tert-butylperoxy) butane, n-butyl-4,4-di (tert-butylperoxy) valerate, 2,2-di (4,4-di (tert-butylperoxy) cyclohexane) Propane, p-methane hydroperoxide, dipropyl side Zen hydroperoxide, 1,1,3,3-tetramethylbutyl hydroperoxide, cumene hydroperoxide, tert-butyl hydroperoxide, di (2-tert-butylperoxyisopropyl) benzene, dicumyl peroxide 2,5-dimethyl-2,5-di (tert-butylperoxy) hexane, tert-butylcumyl peroxide, di-tert-butyl peroxide, 2,5-dimethyl 2,5-di (tert-butylperoxy) ) Hexyne, diisobutyl peroxide, di (3,5,5-trimethylhexanoyl) peroxide, dilauryl peroxide, di (3-methylbenzoyl) peroxide, benzoyl (3-methylbenzoyl) peroxide, dibenzoylperoxide Oxa De, di (4-methylbenzoyl) peroxide, di n-p ropir peroxydicarbonate, diisopropyl peroxydicarbonate, di (2-ethylhexyl) peroxydicarbonate, di sec-butyl peroxydicarbonate, cumylper Oxy neodecanate, 1,1,3,3-tetramethylbutyl peroxy neodecanate, tert-hexyl neodecanate, tert-butyl peroxy neoheptanate, tert-hexyl peroxy pivalate, 1,1, 3,3-Tetramethylbutylperoxy-2-ethylhexanate, 2,5-dimethyl-2,5, -di (2-diethylhexoylperoxy) hexane, tert-butylperoxy-2-ethylhexanate , Tert-hexiperoxy isopropyl mo Organic carbonate, tert-butyl peroxymaleic acid, tert-butyl peroxy 3,5,5-trimethylhexanate, tert-butyl peroxyisopropyl monocarbonate, tert-butyl peroxy-2-ethylhexy monocarbonate, tert- Hexylperoxybenzonate, 2,5-dimethyl-2,5-di (benzoylperoxy) hexane, tert-butylperoxyacetonate, tert-peroxy-3-methylbenzonate, tert-butylperoxybenzonate, Examples thereof include tert-butylperoxyallyl monocarbonate, 3,3 ′, 4,4′-tetra (tert-butylperoxycarbonyl) benzophenone and the like. As the peroxide, one or more of the above specific examples can be used in combination.

(Hardening agent)
The paste-like adhesive composition of the present embodiment preferably contains, for example, a curing agent. Thus, the epoxy resin and the epoxy monomer can be cured and shrunk to aggregate the silver particles.
As a curing agent, a phenol curing agent and an imidazole curing agent can be used. Details will be described below.

[Phenol curing agent]
Specific examples of the phenol resin-based curing agent include novolac type phenol resins such as phenol novolac resin, cresol novolac resin, bisphenol novolac resin, phenol-biphenyl novolac resin, etc .; polyvinyl phenol; polyfunctional such as triphenylmethane type phenol resin Type phenolic resin; modified phenolic resin such as terpene modified phenolic resin, dicyclopentadiene modified phenolic resin, etc .; phenol aralkyl type such as phenol aralkyl resin having phenylene skeleton and / or biphenylene skeleton, naphthol aralkyl resin having phenylene and / or biphenylene skeleton Phenolic resin; bisphenol compounds such as bisphenol A, bisphenol F (dihydroxydiphenylmethane); 4,4'-biphenol The compound etc. which have any biphenylene frame | skeleton are mentioned. The phenolic resin-based curing agent can include one or more selected from the above specific examples.
Among the above specific examples, it is preferable to use, for example, a bisphenol compound as the phenolic resin. Moreover, as a bisphenol compound, it is preferable to use bisphenol F, for example. Thus, the epoxy resin can be cured and shrunk to form an appropriate silver particle connection structure.

[Imidazole-based curing agent]
Specific examples of the imidazole-based curing agent include 2-phenyl-1H-imidazole-4,5-dimethanol, 2-phenyl-4-methyl-5-hydroxymethylimidazole, 2-methylimidazole and 2-phenylimidazole. 2,4-diamino-6- [2-methylimidazolyl- (1)]-ethyl-s-triazine, 2-undecylimidazole, 2-heptadecylimidazole, 2,4-diamino-6- [2-methyl Imidazolyl- (1)]-ethyl-s-triazine isocyanuric acid adduct, 2-phenylimidazole isocyanuric acid adduct, 2-methylimidazole isocyanuric acid adduct, 1-cyanoethyl-2-phenylimidazolium trimellitate, 1- Cyanoethyl 2-undecyl imidazolium trimellitate etc It is below. As an imidazole series hardening agent, it can use combining 1 type, or 2 or more types among the said specific examples.

The lower limit of the content of the curing agent in the paste adhesive composition is, for example, 1 part by mass or more with respect to 100 parts by mass of the total amount of the epoxy monomer and the epoxy resin in the paste adhesive composition. Is preferable, and 1.5 parts by mass or more is more preferable. Thereby, the paste-like adhesive composition can be appropriately cured and shrunk to form a suitable silver particle connection structure.
The upper limit of the content of the curing agent in the paste-like adhesive composition is, for example, 10 parts by mass or less with respect to 100 parts by mass of the total amount of the epoxy monomer and epoxy resin of the paste-like adhesive composition. It is preferable that the amount is 5 parts by mass or less. Thus, the polymer component is preferable from the viewpoint of not inhibiting the formation of the silver particle linked structure.

(Hardening accelerator)
The paste-like adhesive composition according to the present embodiment may contain, for example, a curing accelerator that promotes the reaction of an epoxy monomer or an epoxy resin with a curing agent.
Specific examples of curing accelerators include phosphorus atoms-containing compounds such as organic phosphines, tetra-substituted phosphonium compounds, phosphobetaine compounds, adducts of phosphine compounds and quinone compounds, adducts of phosphonium compounds and silane compounds, etc .; dicyandiamide 1,8-diazabicyclo [5.4.0] undecene-7, amidines such as benzyldimethylamine and tertiary amines; nitrogen atom-containing compounds such as the above amidines or quaternary ammonium salts of the above tertiary amines; . As a hardening accelerator, it can be used combining 1 type, or 2 or more types among the said specific examples.

(Low stress agent)
The pasty adhesive composition according to the present embodiment may contain, for example, a low stress agent.
Specific examples of the low stress agent include silicone compounds such as silicone oil and silicone rubber; polybutadiene compounds such as polybutadiene maleic anhydride adduct; and acrylonitrile butadiene copolymer compounds. As the low stress agent, one or more of the above specific examples can be used in combination.

(Silane coupling agent)
The paste-like adhesive composition according to the present embodiment may contain, for example, a silane coupling agent in order to improve the adhesion between the paste-like adhesive composition and the substrate.
Specific examples of the silane coupling agent include vinyltrimethoxysilane, vinylsilane such as vinyltriethoxysilane; 2- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, 3-glycidyloxypropyltrimethoxysilane, 3 -Epoxysilanes such as glycidoxypropylmethyldimethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, 3-glycidoxypropyltriethoxysilane; p-styryltrimethoxysilane Styrylsilanes such as: 3-methacryloxypropylmethyldimethoxysilane, 3-methacryloxypropyltrimethoxysilane, 3-methacryloxypropylmethyldiethoxysilane, 3-methacryloxypropyltriethoxysilane Such as methacryl silane such as acrylic acid; 3- (trimethoxysilyl) propyl methacrylate; acrylic silane such as 3-acryloxypropyl trimethoxysilane; N-2- (aminoethyl) -3-aminopropylmethyldimethoxysilane, N-2 -(Aminoethyl) -3-aminopropyltrimethoxysilane, 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3-triethoxysilyl-N- (1,3-dimethyl-butylidene) propylamine, Aminosilanes such as N-phenyl-γ-aminopropyltrimethoxysilane; isocyanurate silanes; alkylsilanes; ureidosilanes such as 3-ureidopropyltrialkoxysilane; 3-mercaptopropylmethyldimethoxysilane, 3-mercaptopropyltrimethoxysilane Mercaptosilanes such as methoxysilane; and isocyanate silanes such as 3-isocyanatopropyltriethoxysilane can be used. As a silane coupling agent, it can be used combining 1 type, or 2 or more types among the said specific examples.

(Production method of paste-like adhesive composition)
The manufacturing method of the paste-form adhesive composition which concerns on this embodiment is demonstrated.
The method of producing the paste-like adhesive composition includes a mixing step of mixing the above-mentioned raw material components to prepare a mixture, and a defoaming step of removing air contained in the mixture.

(Mixing process)
In the mixing step, the above-described raw material components are mixed to prepare a mixture.
It does not limit as a method to mix, For example, 3 rolls, a mixer, etc. can be used. Thus, the raw material components are mixed to obtain a mixture.

(Defoaming process)
In the defoaming step, the air contained in the mixture is removed.
The method for removing the air contained in the mixture is not limited, and for example, the mixture can be left to stand under vacuum. This gives a paste-like adhesive composition.

(Paste adhesive composition)
As curing conditions of the paste-like adhesive composition according to the present embodiment, for example, the temperature rising rate is 0.5 ° C./min to 30 ° C. from around room temperature (20 ° C. to 30 ° C.) to 100 ° C. to 300 ° C. The temperature is raised at a temperature of at most / min, and heat treatment can be performed for 10 minutes to 2 hours at a temperature after the temperature rise. Thereby, the paste adhesive composition can be sufficiently cured.

The paste-like adhesive composition according to the present embodiment is applied onto a copper lead frame so that the coating thickness becomes 25 ± 10 μm, and then a bare silicon wafer of 2 mm in length × 2 mm in width is applied to the paste-like adhesive composition. Placing on a substrate to obtain a laminate, and then raising the temperature of the laminate from 25 ° C. to 175 ° C. over 30 minutes in the atmosphere, and further keeping the temperature at 175 ° C. for 30 minutes The lower limit value of the shear strength between the bare silicon via the cured body and the copper circuit measured at a temperature of 260 ° C., which is measured at a temperature of 260 ° C., is preferably, for example, 5.0 MPa or more, It is more preferably 0 MPa or more, still more preferably 7.0 MPa or more, still more preferably 7.5 MPa or more, and particularly preferably 8.0 MPa or more. Thereby, the reliability such as the adhesion reliability and the mounting reliability of the paste adhesive composition can be improved. It is also advantageous from the viewpoint of being able to improve the shear strength when bonding a bare silicon wafer to a metal such as a silver-plated lead frame or a pre-plated leadframe (hereinafter also referred to as PPF).
Further, the upper limit value of the shear strength may be, for example, 15.0 MPa or less, or 14.0 MPa or less.

(Use)
The application of the paste-like adhesive composition according to the present embodiment will be described.
The paste-like adhesive composition according to the present embodiment can be in close contact with various adherends, and is further excellent in heat dissipation. Specific examples of the adherend include semiconductor elements such as ICs and LSIs; base materials such as lead frames, BGA substrates, mounting substrates, and semiconductor wafers; and heat dissipation members such as heat spreaders and heat sinks.
Here, the semiconductor device may be, for example, a power device. In the present embodiment, the power device indicates, for example, one having a power consumption of 1.7 W or more.

The paste-like adhesive composition according to the present embodiment is suitably used, for example, in a semiconductor device such as a semiconductor package.
Here, as the type of semiconductor package, specifically, MAP (Mold Array Package), QFP (Quad Flat Package), SOP (Small Outline Package), CSP (Chip Size Package), QFN (Quad Flat Non-leaded) Package, SON (Small Outline Non-leaded Package), BGA (Ball Grid Array), LF-BGA (Lead Flame BGA), FCBGA (Flip Chip BGA), MAPBGA (Molded Array Process BGA), eWLB (Embedded Wafer-Level) BGA), Fan-In type eWLB, Fan-Out type eWLB, etc. Types of

Below, an example of the semiconductor device using the paste-like adhesive composition which concerns on this embodiment is demonstrated.
FIG. 1 is a cross-sectional view showing an example of a semiconductor device according to the present embodiment.
A semiconductor device 100 according to the present embodiment includes a base 30 and a semiconductor element 20 mounted on the base 30 via an adhesive layer 10 which is a cured product of a paste-like adhesive composition. That is, the adhesive layer 10 is formed by curing a paste-like adhesive composition.
The semiconductor element 20 and the base 30 are electrically connected via, for example, a bonding wire 40 or the like. In addition, semiconductor element 20 is sealed by sealing resin 50, for example.

The lower limit of the thickness of the adhesive layer 10 is, for example, preferably 5 μm or more, more preferably 10 μm or more, and still more preferably 20 μm or more. Thereby, the heat capacity of the hardened | cured material of a paste-form adhesive composition can be improved, and heat dissipation can be improved.
Further, the upper limit value of the thickness of the adhesive layer 10 may be, for example, 100 μm or less, or 50 μm or less.

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 30 via the die attach layer 10. In addition, the semiconductor element 20 is electrically connected to the outer lead 34 (base material 30), for example, via the bonding wire 40. The base material 30, which is a lead frame, is made of, for example, a 42 alloy Cu frame.

The substrate 30 may be an organic substrate or a ceramic substrate. As an organic substrate, what is comprised, for example with an epoxy resin, cyanate resin, maleimide resin etc. is preferable.
The surface of the substrate 30 may be coated with a metal such as silver or gold, for example. Thereby, the adhesiveness of 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 semiconductor device 100 according to the present modification, base material 30 is, for example, an interposer. For example, a plurality of solder balls 52 are formed on the other surface of the base material 30 which is an interposer, which is opposite to the one surface on which the semiconductor element 20 is mounted. In this case, the semiconductor device 100 is connected to another wiring board through the solder balls 52.

(Method of manufacturing semiconductor device)
An example of a method of manufacturing a semiconductor device according to the present embodiment will be described.
First, the paste-like adhesive composition is applied on the substrate 30, and then the semiconductor element 20 is disposed thereon. 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 paste-like adhesive composition is not limited, but specifically, dispensing, printing, inkjet, etc. can be used.
Then, the paste adhesive composition is precured and postcured to make the paste adhesive composition a cured product. By heat treatment such as pre-curing and post-curing, the silver particles in the paste-like adhesive composition are aggregated, and a thermally conductive layer in which the interface between the plurality of silver particles disappears is formed in the adhesive layer 10. Thus, the base 30 and the semiconductor element 20 are bonded via the adhesive layer 10. Next, the semiconductor element 20 and the base 30 are electrically connected using the bonding wire 40. Next, the semiconductor element 20 is sealed by the sealing resin 50. Thus, a semiconductor device can be manufactured.

As mentioned above, although this invention was demonstrated based on embodiment, this invention is not limited to the said embodiment, The structure can also be changed in the range which does not change the summary of this invention.

Hereinafter, the present invention will be described in detail using examples, but the present invention is not limited to the description of these examples.

Ingredients
First, details of the raw material components used in Examples and Comparative Examples will be described.

(Main ingredient)
The following were used as main ingredients.
Epoxy oligomer 1: bisphenol-F-diglycidyl ether (manufactured by Nippon Kayaku Co., Ltd., RE-403S, Mw = 236, epoxy equivalent 165 g / eq)
Epoxy oligomer 2: mixture of m-glycidyl ether and p-glycidyl ether (manufactured by Sakamoto Yakuhin Kogyo, m, p-CGE, Mw = 165, epoxy equivalent 165 g / eq)

(Hardening agent)
The following were used as a curing agent.
-Phenol curing agent 1: dihydroxy diphenyl methane (manufactured by DIC, DIC-BPF)
-Imidazole curing agent 1: 2-phenyl-1H-imidazole-4,5-dimethanol (manufactured by Shikoku Kasei Kogyo Co., Ltd., 2PHZ-PW)

(Hardening accelerator)
The following were used as a curing accelerator.
-Hardening accelerator 1: Dicyanamide (manufactured by ADEKA, EH-3636AS)

(Monomer)
The following were used as monomers.
Monofunctional acrylic monomer 1: 1,4-cyclohexanedimethanol monoacrylate (manufactured by Nippon Kasei Kogyo Co., Ltd., CHDMMA)
Monofunctional acrylic monomer 2: 2-phenoxyethyl methacrylate (manufactured by Kyoeisha Chemical, PO)

(Silver particles)
As silver particles, those shown in Table 1 below were used.

Preparation of Paste-Like Adhesive Composition
The paste-like adhesive composition of each Example and each comparative example was produced. As a preparation method, each raw material component of the compounding quantity described in following Table 2 was prepared by knead | mixing with a 3 roll mill at normal temperature.

<Evaluation>
The paste-like adhesive compositions of Examples and Comparative Examples were evaluated by the following methods.

(Shear strength)
The shear strength was evaluated by the following method about the paste-like adhesive composition of each Example and each comparative example. I will explain the details.
First, a copper lead frame (hereinafter also referred to as copper LF) and a silicon chip (length 2 mm × width 2 mm) were prepared. Subsequently, the paste-like adhesive composition of each Example and each comparative example was apply | coated so that it might become application | coating thickness 25 +/- 10 micrometers to a silicon chip, and the copper lead frame was arrange | positioned on it. That is, a laminate obtained by laminating a silicon chip, a paste-like adhesive composition and a copper lead frame in this order was produced. The surface of the copper lead frame in contact with the paste adhesive composition is made of copper.
Next, after raising the temperature from 25 ° C. to 175 ° C. over 30 minutes under the atmosphere, the paste-like adhesive composition of the laminate is cured to a cured product by heat treatment at a temperature of 175 ° C. for 30 minutes. .
Next, the shear strength between the silicon chip bonded via the cured product and the copper lead frame was measured. As measurement conditions, measurement was performed at a temperature of 260 ° C. for 20 seconds. The evaluation results are shown in Table 2 below as a result of the shear strength of Si-copper LF. The unit is MPa.
In addition, the evaluation results of shear strength using a silver-plated lead frame plated with silver on the surface of the copper lead frame instead of the copper lead frame are shown in Table 2 below as the results of shear strength of Si-silver plated LF. The surface of the silver-plated lead frame in contact with the pasty adhesive composition is made of silver.
In addition, evaluation results of shear strength using a pre-plated leadframe (hereinafter also referred to as PPF) instead of the copper lead frame are shown in Table 2 below as a result of shear strength of Si-PPF. PPF is plated with Ni, Pd and Au in this order on a copper lead frame. The surface in contact with the PPF paste adhesive composition is made of gold (Au).

(Residual resin rate)
The resin residual rate was evaluated by the following method about the paste-form adhesive composition of each Example and each comparative example. Thermogravimetry-differential thermal analysis (TG-DTA) was performed on the pasty adhesive compositions of the examples and the comparative examples. As the conditions of thermogravimetric measurement, the temperature is raised from temperature 30 ° C. to 200 ° C. at a heating rate of 10 ° C./min under the atmosphere, then heat treatment is carried out at temperature 200 ° C. for 60 minutes, then temperature 200 ° C. to 450 ° C. The temperature was raised by 10 ° C./min up to the temperature rising time, and then heat treatment was performed at a temperature of 450 ° C. for 10 minutes. The measurement was performed under the atmosphere.
The percentage of weight loss of the paste adhesive composition after heat treatment at 200 ° C. for 60 minutes with respect to the paste adhesive compositions of Examples and Comparative Examples before temperature rising was set to W1 [%] .
In addition, the percentage of weight loss of the paste-like adhesive composition after heat treatment at 450 ° C. for 10 minutes relative to the paste-like adhesive compositions of the respective Examples and Comparative Examples before the temperature rise is W2 [%] And
Next, (W2-W1) / W2 was calculated from the measured W1 and W2. The evaluation results are shown in Table 2 below.
W1 and W2 are positive values or 0 values. For example, when the weight of the paste-like adhesive composition after heat treatment at 200 ° C. for 60 minutes is 90% of the weight of the paste-like adhesive composition before the temperature rise, the weight reduction rate is 10%.
Here, the temperature is raised from 30 ° C. to 200 ° C. at a temperature rising rate of 10 ° C./min, then heat treatment is carried out at a temperature of 200 ° C. for 60 minutes, and then the temperature rising time from 200 ° C. to 450 ° C. is 10 ° C./min. The behavior of the monomer and the main agent when the temperature is raised and then the heat treatment is carried out for 10 minutes at a temperature of 450.degree.
First, the temperature is raised from a temperature of 30 ° C. to a temperature of 200 ° C. at a temperature rising rate of 10 ° C./min, and then the heat treatment is performed at a temperature of 200 ° C. for 60 minutes. Volatilize. In addition, components that cause a curing reaction cure sufficiently.
Next, the temperature is raised from 200 ° C. to 450 ° C. at a temperature rising time of 10 ° C./min, and then heat treatment is carried out at 450 ° C. for 10 minutes to completely decompose the components of the monomer and the main agent that cause curing reaction. Do.
From the above, (W2-W1) of the molecule indicates the mass fraction of the monomer to be cured and the main agent. Further, W2 of the denominator indicates the sum of the mass fraction of the monomer to be cured and the main agent and the mass fraction of the monomer to be volatilized. Therefore, (W2-W1) / W2 indicates the ratio of the monomer to be cured and the main agent among the monomers and the main agent.

(Heat cycle test)
A heat cycle test was performed on the cured products of the pasty adhesive compositions of the examples and the comparative examples to evaluate the adhesion reliability. The detailed method is shown below.
First, a copper lead frame (hereinafter also referred to as copper LF) and a silicon chip (length 2 mm × width 2 mm, thickness 0.35 mm) were prepared. Subsequently, the paste-like adhesive composition of each example and each comparative example was applied to a silicon chip so as to have a coating thickness of 25 ± 10 μm, and a copper lead frame was disposed thereon. That is, a laminate obtained by laminating a silicon chip, a paste-like adhesive composition and a copper lead frame in this order was produced. The surface of the copper lead frame in contact with the pasty adhesive composition is made of copper.
Next, the temperature is raised from 25 ° C. to 175 ° C. over 30 minutes under the atmosphere, and then the paste-like adhesive composition of the laminate is cured by heat treatment at a temperature of 175 ° C. for 60 minutes to prepare a cured product. did.
Next, the cured product was heat treated at a temperature of 160 ° C. for 30 minutes, and further, when the process of heat treating at a temperature of 25 ° C. for 30 minutes was one cycle, a heat cycle test was performed to perform 10 cycles of heat treatment. After the heat cycle test, visually confirm whether peeling has occurred between the cured product of the silicon chip and the paste-like adhesive composition and between the cured product of the copper lead frame and the paste-like adhesive composition, The following criteria were evaluated. The evaluation results are shown in Table 2 below as the results of the heat cycle test of Si-copper LF.
Good: There is no peeling between the silicon chip and the cured product, and no peeling between the copper lead frame and the cured product.
X: Peeling has occurred between the silicon chip and the cured product, or peeling has occurred between the copper lead frame and the cured product.
Further, in place of the copper lead frame, a silver plated lead frame obtained by silver plating the surface of the copper lead frame, and PPF were respectively used, and adhesion to an adherend was evaluated in the same manner as the copper lead frame. The evaluation results are shown in Table 2 below as the results of the heat cycle test of Si-silver plated LF and Si-PPF, respectively.

(Chip-Chip thermal diffusivity)
For the paste-like adhesive compositions of the examples and the comparative examples, the chip-chip thermal diffusivity was evaluated by the following method. Details will be described below.
First, two silicon chips 10 mm long × 10 mm wide × 350 μm thick were prepared. The paste-like adhesive composition was applied to one silicon chip to a thickness of 25 ± 10 μm, and the other silicon chip was laminated thereon. That is, a laminate in which a silicon chip, a paste-like adhesive composition, and a silicon chip were laminated in this order was produced.
Next, the temperature was raised from 25 ° C. to 175 ° C. over 30 minutes, and then the paste-like adhesive composition of the laminate was cured by heat treatment at a temperature of 175 ° C. for 60 minutes to obtain a cured product. Thus, a test piece in which two silicon chips were adhered via the cured product of the pasty adhesive composition was produced.
Next, the thermal diffusion coefficient of the test piece in the thickness direction of the test piece was measured using a laser flash method, and this was used as the evaluation result of the chip-chip thermal diffusivity. The measurement temperature of the thermal diffusion coefficient was 25.degree. The evaluation results are shown in Table 2 below as the results of the thermal diffusivity of the Si-Si Chip-Chip. The unit is cm ² / sec. Here, the higher the chip-chip thermal diffusivity, the better the evaluation results.
Also, instead of a silicon chip, using a gold-plated silicon chip in which Ti, Ni, and Au are plated in this order on a silicon chip 10 mm long × 10 mm wide × 350 μm thick, the chip-chip has a thermal diffusivity of It measured. Here, when producing a laminated body, it laminated | stacked so that a paste-form adhesive composition and the surface which consists of Au may contact. The evaluation results are shown in Table 2 below as the results of the chip-chip thermal diffusivity of Au-Au.
In the case of using a sintering type paste adhesive composition, the gold plated silicon chip is evaluated favorably for the sintering type paste adhesive composition in that the interface between the gold plating and the paste adhesive composition can disappear. It is a method.

(Observation of silver particle connected structure)
The semiconductor device using the paste-like adhesive composition of each example and each comparative example is observed for a cross section using a scanning electron microscope (SEM) to confirm whether a silver particle connection structure is formed. did. The detailed method is shown below.
First, a copper lead frame (hereinafter also referred to as copper LF) and a silicon chip (length 2 mm × width 2 mm, thickness 0.35 mm) were prepared. Subsequently, the paste-like adhesive composition of each example and each comparative example was applied to a silicon chip so as to have a coating thickness of 25 ± 10 μm, and a copper lead frame was disposed thereon. That is, a laminate obtained by laminating a silicon chip, a paste-like adhesive composition and a copper lead frame in this order was produced. The surface of the copper lead frame in contact with the pasty adhesive composition is made of copper.
Next, the temperature is raised from 25 ° C. to 175 ° C. over 30 minutes under the atmosphere, and then the paste-like adhesive composition of the laminate is cured by heat treatment at a temperature of 175 ° C. for 60 minutes to prepare a cured product. did.
Then, the cross section of the cured product was observed using a SEM. The evaluation results are shown in Table 2 below, in which the case where the silver particle linked structure is formed is indicated by “○” and the case where the silver particle connected structure is not formed is indicated by “x”. Moreover, the result of SEM observation of Example 1 and Comparative Example 3 is respectively shown in FIG. 3 and FIG.

(Implementation reliability)
The mounting reliability was evaluated about the semiconductor device using the paste-form adhesive composition of each Example and each comparative example. As evaluation of implementation reliability, MSL (Moisture Sensitivity Level) performance was measured. The MSL performance was performed using MSL Lv2a according to JEDEC STANDARD 22-A113D. The detailed method is shown below.
First, a copper lead frame (hereinafter also referred to as copper LF) and a silicon chip (length 2 mm × width 2 mm, thickness 0.35 mm) were prepared. Subsequently, the paste-like adhesive composition of each example and each comparative example was applied to a silicon chip so as to have a coating thickness of 25 ± 10 μm, and a copper lead frame was disposed thereon. That is, a laminate obtained by laminating a silicon chip, a paste-like adhesive composition and a copper lead frame in this order was produced. The surface of the copper lead frame in contact with the pasty adhesive composition is made of copper.
Next, the temperature is raised from 25 ° C. to 175 ° C. over 30 minutes under the atmosphere, and then the paste-like adhesive composition of the laminate is cured to a cured product by heat treatment at a temperature of 175 ° C. for 60 minutes. .
Next, the cured product is sealed with an epoxy resin composition for semiconductor encapsulation (EME-G700LS manufactured by Sumitomo Bakelite Co., Ltd.) so that the package size becomes 17.9 mm long × 7.2 × width 2.5 mm thick. The semiconductor device was obtained by curing and curing the epoxy resin composition for semiconductor encapsulation at a temperature of 175 ° C. for 4 hours.
The semiconductor device was subjected to moisture absorption treatment for 120 hours under the conditions of 60 ° C. and relative humidity 60%, and then subjected to IR reflow treatment (reflow three times under the conditions of 260 ° C. and 10 seconds). Next, with respect to the semiconductor device after IR reflow processing, the presence or absence of peeling at the interface between the lead frame and the silicon chip was evaluated using a transmission ultrasonic flaw detector. The evaluation was performed on eight semiconductor devices, and the average value thereof was evaluated based on the following criteria. The evaluation results are shown in Table 2 below as a result of the mounting reliability of Si-copper LF.
Good: interface of cured product of copper lead frame and paste adhesive composition, interface of cured product of paste adhesive composition and interface of silicon chip, and cured product of epoxy resin composition for silicon chip and semiconductor sealing For the interface, the area of the interface being peeled was less than 20% with respect to the area of 2 mm × 2 mm.
X: Of the interface of the cured product of the copper lead frame and the paste adhesive composition, the interface of the cured product of the paste adhesive composition and the silicon chip, and the cured product of the silicon chip and the epoxy resin composition for semiconductor encapsulation With respect to the interface, the area of the interface being peeled was 20% or more with respect to the area of 2 mm × 2 mm.
Further, the mounting reliability was evaluated in the same manner as the copper lead frame, using a silver plated lead frame in which the surface of the copper lead frame is silver plated and PPF in place of the copper lead frame. The evaluation results are shown in Table 2 below as the results of the mounting reliability of Si-silver plated LF and Si-PPF, respectively.

As shown in Table 2, compared with the paste-like adhesive composition of each comparative example, the paste-like adhesive composition of each example has reliability such as mounting reliability and adhesion reliability, and Chip-Chip thermal diffusivity. It has been confirmed that heat dissipation such as can be expressed in a well-balanced manner.

Comparative Example 1 is a sintering type paste adhesive composition.
Further, Comparative Example 2 is a paste type adhesive composition of a hybrid type of a binder type and a sintering type. However, in the comparative example 2, the shape of the silver particles is only spherical, and the silver particles are attracted excessively. Thereby, it is thought that the interface of the hardened | cured material of the paste-like adhesive composition of the comparative example 2 and an adherend will be destroyed by shrinkage | contraction of silver particle. Therefore, the paste-like adhesive composition of Comparative Example 2 is considered to be inferior in the reliability of the semiconductor device.
Further, Comparative Example 3 is a binder-type paste-like adhesive composition. The conventional binder-type adhesive is excellent in adhesion to the adherend and is excellent in the reliability of the semiconductor device. However, the paste-like adhesive composition of Comparative Example 3 was inferior to the paste-like adhesive composition of the example in the reliability of the semiconductor device. In order to confirm this reason, the cross section of the hardened | cured material of the laminated body which concerns on the comparative example 3 produced by the heat cycle test mentioned above was observed using the scanning type microscope. As a result, in the cured product of the laminate according to Comparative Example 3, almost no silver particles are present near the interface with the adherend, and silver particles are present near the center in the thickness direction of the cured product of the paste-like adhesive composition. It was confirmed that they were gathering. It is speculated that this is due to the shape of silver particles and the particle size profile of silver particles. The conventional paste-like adhesive composition is one in which silver particles are uniformly dispersed. As a result, it is considered that the cured product of the paste-like adhesive composition of Comparative Example 3 receives an internal stress caused by the contraction of silver particles at the interface with the adherend, and the interface is broken.

This application claims priority based on Japanese Patent Application No. 2017-232247, filed Dec. 4, 2017, the entire disclosure of which is incorporated herein.

Claims (9)

1. Epoxy resin,
   Containing silver particles,
   A paste-like adhesive composition, wherein a silver particle connected structure is formed by heat treatment, in which an interface between a plurality of the silver particles disappears.
   The paste adhesive composition is applied on a copper lead frame so that the coating thickness is 25 ± 10 μm, and then a bare silicon wafer of 2 mm in length × 2 mm in width is disposed on the paste adhesive composition. The laminate is then heated in the atmosphere from temperature 25 ° C. to 175 ° C. over 30 minutes, and then kept at 175 ° C. for 30 minutes to obtain a cured product. A paste-like adhesive composition having a shear strength of 5.0 MPa or more and 15.0 MPa or less between the bare silicon via the cured body and the copper lead frame measured at a temperature of 260 ° C. when obtained. .
2. The paste adhesive composition according to claim 1, wherein
   The paste-like adhesive composition, wherein the silver particles comprise flaky silver particles.
3. The paste adhesive composition according to claim 2, wherein
   The paste-like adhesive composition, wherein the silver particles further comprise spherical silver particles.
4. The paste-like adhesive composition according to claim 3, wherein the content of the flake-like silver particles in the silver particles is 5 parts by mass with respect to the total amount of the flake-like silver particles and the spherical silver particles. The paste-like adhesive composition which is 60 mass parts or less.
5. The paste adhesive composition according to any one of claims 1 to 4, wherein
   The paste-like adhesive composition whose content of the said silver particle is 50 mass parts or more and 90 mass parts or less with respect to the said paste-form adhesive composition whole.
6. The paste adhesive composition according to any one of claims 1 to 5, wherein
   The pasty adhesive composition, wherein the epoxy resin comprises an epoxy oligomer or an epoxy polymer.
7. The paste adhesive composition according to any one of claims 1 to 6, wherein
   A pasty adhesive composition further comprising a curing agent.
8. A substrate,
   A semiconductor element mounted on the substrate via an adhesive layer,
   The said contact bonding layer consists of hardened | cured material of the paste-form adhesive composition of any one of Claims 1-7.
9. The semiconductor device according to claim 8,
   The semiconductor device, wherein the base material is one selected from the group consisting of a lead frame, a BGA substrate, a mounting substrate, a semiconductor wafer, a heat spreader and a heat sink.

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