TW201825536A - Die attachment paste and semiconductor device - Google Patents

Abstract

The die attach paste according to the present invention comprises: a (meth)acrylic copolymer (A) having a reactive group; a (meth)acrylic monomer (B); and a filler (C), the reactive group of the (meth)acrylic copolymer (A) being at least one group selected from an epoxy group, an amino group, a vinyl group, a carboxyl group, and a hydroxyl group, the weight average molecular weight of the (meth)acrylic copolymer (A) being 2000-14000, and the particle size D50 of the filler (C) upon 50% accumulation in a volume-basis particle size distribution being 0.3-4.0 [mu]m.

Description

 Die adhesion paste and semiconductor device  

The present invention relates to a die attach paste and a semiconductor device.

As a resin composition for producing a thermally conductive adhesive layer, for example, a paste containing metal particles may be used. As a technique concerning such a paste, the patent document 1 is mentioned, for example. Patent Document 1 discloses a thermosetting resin composition comprising (A) plate-like silver fine particles, (B) silver powder having an average particle diameter of 0.5 to 30 μm, and (C) a thermosetting resin.

Among them, Patent Document 1 describes that the thermal conductivity can be increased by sintering the plate-like silver fine particles more than when only ordinary silver powder is filled.

Further, Patent Document 2 discloses a resin paste composition comprising an acrylate or methacrylate having a specific structure, a butadiene oligomer, and the like.

According to Patent Document 2, it is possible to provide a resin paste which does not cause reflow cracking even when a copper lead frame or an organic substrate is used as a supporting member.

Patent Document 1: Japanese Laid-Open Patent Publication No. 2014-194013

Patent Document 2: Japanese Laid-Open Patent Publication No. 2005-154633

However, in recent years, when a semiconductor package is mounted on a substrate, there is a tendency to use lead-free solder, and the solder reflow temperature may be set high in response to this.

Therefore, the adhesive layer obtained from the die attach paste is also required to have higher heat resistance and reflow resistance than in the past.

The present invention has been made in view of such circumstances, and a first object thereof is to provide a die attach paste which exhibits higher reflow resistance than conventional ones when the adhesive layer is formed.

In addition, the inventors of the present invention have studied the warpage of the semiconductor package when the semiconductor package is formed by bonding the lead frame and the mold to the thermosetting resin composition described in Patent Document 1, and the semiconductor package is mounted. As a result, it was confirmed that the warpage of the semiconductor package using the thermosetting resin composition described in Patent Document 1 is greatly different from the design value. When the warpage after mounting of the semiconductor package is greatly different from the design value, problems such as mechanical damage and poor electrical connection are caused, and the mounting reliability of the semiconductor package is lowered.

Accordingly, a second object of the present invention is to provide a die attach paste which improves the mounting reliability of a semiconductor device such as a semiconductor package.

In the field of conventional die attach pastes, it is considered that the cause of warpage when mounting a semiconductor device is the internal stress generated in the die attach paste by heat treatment. Here, it is considered that the cause of the internal stress is large, and the influence of moisture absorption on the internal stress is not considered. Here, the inventors of the present invention have studied the cause of the warpage of the semiconductor device, and have found that the moisture absorption of the die attach paste contributes to warpage.

For example, a semiconductor package produced by bonding a semiconductor element such as a substrate such as a lead frame and a mold via a die attach paste is stored in a vacuum step to eliminate the influence of moisture absorption. However, in the mounting step of the semiconductor package, the vacuum for holding the package is removed. Thereby, it is considered that the die attach paste applied to the package absorbs moisture from the system in the mounting step of the semiconductor package such as the atmosphere. In addition, it is considered that warpage is affected by moisture absorption in the semiconductor package due to heat treatment such as a reflow step in the mounting step of the semiconductor package or heat generation of the semiconductor device during use of the semiconductor device after the mounting step.

It is difficult to set the production steps of a semiconductor device such as a semiconductor package to a vacuum system. Then, the present inventors have found that it is effective to set the absolute value of the difference between the warpage in the case where the cured product of the die-adhesive paste is not wetted and the warpage in the case where moisture is absorbed, to a specific numerical range. Improve the mounting reliability of semiconductor devices.

As a result of the above, the present inventors have found that the absolute value of the difference between the warpage in the case where the cured product of the die-adhesive paste is not wetted and the warpage in the case where moisture is absorbed is set to a specific numerical range. In the meantime, the effects of the mounting reliability of the semiconductor device are excellent, and the present invention has been completed.

According to the present invention, there is provided a die attach paste comprising: (A) a (meth)acrylic copolymer having a reactive group; (B) a (meth)acrylic monomer; and (C) a filler, as described above ( A) The reactive group of the (meth)acrylic copolymer is one or more selected from the group consisting of an epoxy group, an amine group, a vinyl group, a carboxyl group, and a hydroxyl group, and the (A) (meth)acrylic acid. The weight average molecular weight of the copolymer is 2,000 or more and 14,000 or less, and the particle diameter D ₅₀ at the time of 50% accumulation in the volume-based particle size distribution of the (C) filler is 0.3 μm or more and 4.0 μm or less.

Moreover, according to the present invention, there is provided a semiconductor device comprising: a substrate; and a semiconductor element mounted on the substrate via an adhesive layer of the cured product of the die adhesion paste.

Moreover, according to the present invention, there is provided a die attach paste comprising: silver particles; a monomer; a main agent; and a radical polymerization initiator, wherein the die adhesion paste is applied in a thickness of 35 ± 5 μm. It was applied to a silver-plated copper frame having a length of 15.5 mm and a width of 6.5 mm, and then a tantalum wafer having a length of 15.0 mm, a width of 6.0 mm, and a thickness of 0.2 mm was placed on the die attach paste to obtain a laminate. The laminate was heated from 25 ° C to 175 ° C in a minute, and further heat-treated at 175 ° C for 5 hours to obtain a cured body. The amount of warpage when the cured body was heat-treated at 275 ° C for 1 minute was W1. When the cured body was subjected to heat absorption at 275 ° C for 168 hours at a temperature of 85 ° C and a humidity of 85%, the amount of warpage when the heat treatment was performed at 275 ° C for 1 minute was W2, and |W2-W1| was 20 μm or less.

Wherein, the amount of warpage indicates a diagonal line connecting any two vertices located at opposite corners in the in-plane direction of the tantalum wafer, and a distance from the position of the tantalum wafer in a direction perpendicular to the diagonal line. Maximum value.

Further, according to the invention, there is provided a semiconductor device comprising: a substrate; and a semiconductor element mounted on the substrate via an adhesive layer, wherein the adhesion layer is formed by sintering the die adhesion paste.

According to the present invention, it is possible to provide a die attach paste which exhibits higher reflow resistance than conventional ones when the adhesive layer is formed.

Moreover, according to the present invention, it is possible to provide a die attach paste which improves the mounting reliability of a semiconductor device such as a semiconductor package.

10‧‧‧ die adhesion layer

20‧‧‧Semiconductor components

30‧‧‧Substrate

32‧‧‧ wafer mounting disk

34‧‧‧External pin

40‧‧‧bonding line

50‧‧‧ sealing resin

52‧‧‧ solder balls

100‧‧‧‧‧‧ semiconductor devices

The above object and the other objects, features and advantages will be further clarified by the following description of the preferred embodiments and the accompanying drawings.

Fig. 1 is a cross-sectional view showing a semiconductor device according to a first embodiment and a second embodiment.

Fig. 2 is a cross-sectional view showing a modification of the semiconductor device shown in Fig. 1.

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

<First embodiment>

Hereinafter, the first embodiment of the present invention will be described with reference to the drawings. In the drawings, the same components are denoted by the same reference numerals, and the description thereof will be omitted as appropriate.

In addition, in the present specification, the expression "(meth)acrylic acid" or the like is used in the meaning of "acrylic acid or methacrylic acid".

(grain adhesive paste)

First, the die attach paste of the first embodiment will be described. The die attach paste of the first embodiment is as follows.

A die attach paste comprising: (A) a (meth)acrylic copolymer having a reactive group; (B) a (meth)acrylic monomer; and (C) a filler, the aforementioned (A) (methyl) The reactive group included in the acrylic copolymer is one or more selected from the group consisting of an epoxy group, an amine group, a vinyl group, a carboxyl group, and a hydroxyl group, and the weight average of the (A) (meth)acrylic copolymer is The molecular weight is 2,000 or more and 14,000 or less, and the particle diameter D ₅₀ at the time of 50% accumulation in the volume-based particle size distribution of the (C) filler is 0.3 μm or more and 4.0 μm or less.

The die attach paste of the first embodiment is, for example, a die attach layer (adhesive layer) for bonding a semiconductor element and other structures. Examples of the other structure include a substrate such as a wiring board or a lead frame, a semiconductor element, a heat dissipation plate, and a magnetic shield. Moreover, the die attach paste can also be used, for example, to form an adhesive layer that bonds the other structures to the heat sink.

Further, in the other structure, a film which is in contact with the die attach paste of the first embodiment is preferably provided with a film which promotes adhesion such as silver.

Hereinafter, each component constituting the die attach paste of the first embodiment will be described.

The inventors have studied a method for improving the reflow resistance of a die attach paste. As a result, the following methods were found to be effective, that is, to improve the adhesion of the die attach paste, thereby reducing the interfacial stress at the interface between the die attach paste and the adherend.

Then, the inventors studied the blending composition of the die attach paste in order to improve the adhesion and reduce the interface stress. As a result, important factors are adjusted, for example, by appropriately selecting the following conditions.

(1) reducing the particle size of the (C) filler, and further making the particle size distribution of the (C) filler clear

(2) Balance the hardening shrinkage and crosslink density of (B) (meth)acrylic monomer

(3) imparting flexibility by adding (F) a low stress agent

(4) High molecular weight of (D1) allyl ester resin

(5) A combination of (A) a (meth)acrylic acid copolymer having a reactive group and (B) a (meth)acrylic acid monomer, which is suitable for the properties of the (C) filler

(6) (A) blending ratio of a (meth)acrylic copolymer having a reactive group, (B) a (meth)acrylic monomer, and (C) a filler

(7) (A) a combination of a (meth)acrylic copolymer having a reactive group, (B) a (meth)acrylic monomer, and (C) a filler and other additives

The details will be described later by way of examples.

((A) (meth)acrylic acid copolymer having a reactive group)

The die attach paste of the first embodiment contains (A) a (meth)acrylic copolymer having a reactive group (hereinafter also referred to simply as "(A) (meth)acrylic copolymer").

Here, specific examples of the reactive group include an epoxy group, an amine group, a carboxyl group, a hydroxyl group, and a vinyl group.

(A) The (meth)acrylic copolymer having a reactive group and a component contained in the die attach paste form a strong crosslinked structure by various reactions and polymerization. Therefore, it is considered that high reflow resistance can be exhibited when the adhesive layer is obtained. Further, the adhesiveness to the substrate, the semiconductor element, the heat dissipation plate, and the like can be improved by the reactive group.

Here, as the polymerization of the (meth)acrylic copolymer having a reactive group (A), for example, an acrylic group or a methacrylic group of (A) a (meth)acrylic copolymer having a reactive group, Free radical polymerization of vinyl. The die attach paste has a polymerization initiator, whereby (A) an acrylic group or a vinyl group of a (meth)acrylic copolymer having a reactive group is subjected to radical polymerization. Here, in the radical polymerization, in addition to (A) a (meth)acrylic copolymer having a reactive group, (B) a (meth)acrylic monomer and (D) another resin component are involved (A) The radical polymerization is carried out by using an acrylic group such as an acrylic resin, an allyl ester resin, a maleimide resin, or a polycarbonate resin, or a carbon-carbon double bond C=C.

In addition, examples of the reaction of the (meth)acrylic acid copolymer having a reactive group (A) include a vinyl group, an amine group, a carboxyl group, and a hydroxyl group of (A) a (meth)acrylic copolymer having a reactive group. Radical polymerization, ion polymerization, and the like with (D1) allyl ester resin or (D2) polycarbonate resin.

In addition, examples of the reaction of (A) a (meth)acrylic copolymer having a reactive group include (A) an epoxy group having a reactive group (meth)acrylic copolymer and an amine of a curing accelerator. Base reaction.

In addition, examples of the reaction of the (meth)acrylic acid copolymer having a reactive group (A) include an amine group, a carboxyl group, a hydroxyl group and (D) of a (meth)acrylic copolymer having a reactive group. The reaction of an epoxy group of an epoxy resin of another resin component.

In the die attach paste of the first embodiment, the above reaction and polymerization are initiated by appropriately controlling the blending composition of the component contained therein. As a result, the die attach paste of the first embodiment is hardened and shrunk, and a filler is aggregated, whereby high thermal conductivity can be exhibited.

Further, in the first embodiment, ionic polymerization means cationic polymerization or anionic polymerization.

The (A) (meth)acrylic copolymer of the first embodiment is preferably one having at least one selected from the group consisting of an epoxy group, an amine group, a vinyl group, a carboxyl group and a hydroxyl group at the terminal. Thereby, it is possible to have a soft skeleton and cause hardening shrinkage. Thereby, excessive increase in interface stress and hardening shrinkage can be suppressed.

Regarding the (A) (meth)acrylic copolymer, for example, methyl (meth)acrylate, ethyl (meth)acrylate, butyl (meth)acrylate, cyclohexyl (meth)acrylate can be used. And styrene, hydroxyethyl (meth)acrylate, (meth)acrylic acid, glycidyl (meth)acrylate, etc., and a known polymerization initiator and a chain transfer agent are known by solution polymerization or the like. Technically obtained by copolymerization.

Such a copolymer is sold under the trade name "ARUFON" by TOAGOSEI CO., LTD., and an appropriate functional group can be selected in accordance with the purpose of the present invention.

Further, as a state in which a "vinyl group" is provided at the end, a terminal group containing a vinyl group such as an "acrylic group" or a "methacrylic group" is contained at the end.

In addition, the (A) (meth)acrylic copolymer of the first embodiment has a weight average molecular weight of 2,000 or more and 14,000 or less.

Thereby, the appropriate adhesiveness as the obtained die attach paste can be exhibited, and the reflow resistance as the adhesive layer can be made appropriate.

Further, the weight average molecular weight of the (A) (meth)acrylic copolymer is preferably 2,500 or more, more preferably 3,000 or more, and most preferably 5,000 or more.

Further, the weight average molecular weight of the (A) (meth)acrylic copolymer is preferably 13,000 or less, more preferably 12,500 or less, and most preferably 12,000 or less.

The content of the (A) (meth)acrylic acid copolymer in the die attach paste of the first embodiment is preferably 2% by mass or more based on all the die attach paste systems, and more preferably 2.5% by mass or more. The mass % or more is further preferable. Thereby, the obtained adhesive layer can have an appropriate adhesiveness.

On the other hand, the content of the (A) (meth)acrylic copolymer in the die attach paste is preferably 15% by mass or less based on all the die attach paste systems, and more preferably 12% by mass or less, and 10 mass%. % below is further preferred. Thereby, the viscosity of the paste can be set to an appropriate range, and the workability at the time of coating can be improved.

Further, in the present specification, when the solvent (S) described later is contained, the content of all the die attach paste relative to the content of all the components other than the (S) solvent in the die attach paste is referred to.

((B) (meth)acrylic monomer)

The die attach paste of the first embodiment contains (B) a (meth)acrylic monomer, whereby the viscosity of the appropriate paste and the curability at the time of heating can be exhibited.

The (B) (meth)acrylic monomer can comprise a compound selected from (B1) having only one (meth)acrylic group in the molecule, that is, a monofunctional (meth)acrylic monomer and (B2) One or two or more kinds of compounds having two or more (meth)acrylic groups in the molecule, that is, polyfunctional (meth)acrylic monomers. In addition, (B) (B) is at least (B1) in the molecule as the (B) (meth)acrylic acid monomer in the first embodiment, from the viewpoint of the production of the die attach paste capable of producing the adhesive layer having excellent reflow resistance. It is preferred that each of the compounds having only one (meth)acryl group and (B2) having two or more (meth)acrylic groups in the molecule contain one.

When (B1) a compound having only one (meth)acrylic group in the molecule is reacted with the (A) (meth)acrylic acid copolymer, and (B2) has two or more (meth)acrylic groups in the molecule. The compound has less hardening shrinkage. Thereby, it is possible to increase the molecular weight by polymerization and suppress an increase in interface stress.

When (B2) a compound having two or more (meth)acrylic groups in the molecule is reacted with the (A) (meth)acrylic acid copolymer, the crosslinking density can be increased, and thus the cured product of the die adhesion paste can be obtained. Highly flexible. Thereby, the reflow resistance can be improved.

In the first embodiment, (B1) a compound having only one (meth)acrylic group in the molecule, and (meth)acrylate is preferable. The (meth) acrylate can contain, for example, one or more selected from the group consisting of compounds represented by the following formula (1). Thereby, the viscosity of the paste etc. can be adjusted to an appropriate range.

In the above formula (1), R ₁₁ is hydrogen or a methyl group, and R ₁₂ is a monovalent organic group having 1 to 20 carbon atoms. R ₁₂ may contain one or more of an oxygen atom, a nitrogen atom and a phosphorus atom, and the structure of R ₁₂ may include an -OH group such as a hydroxyl group or a carboxyl group, an epoxy group, or an oxetanyl group. ), an amine group, a guanamine group, and the like.

The compound represented by the above formula (1) is not particularly limited. For example, as the -OH group in the structure of R ₁₂ , a compound selected from 1,4-cyclohexane dimethanol monoacrylate or 2-hydroxyethyl acrylate can be used. Ester, 2-hydroxyethyl methacrylate, 2-hydroxypropyl acrylate, 2-hydroxypropyl methacrylate, 2-hydroxybutyl acrylate, 2-hydroxybutyl methacrylate, 2-hydroxy-3- Phenoxypropyl acrylate, 2-propenyloxyethyl succinic acid, 2-methylpropenyloxyethyl succinic acid, 2-propenyloxyethyl hexahydrophthalic acid, 2-methyl Acryloxyethylhexahydrophthalic acid, 2-propenyloxyethylphthalic acid, 2-propenyloxyethyl-2-hydroxyethylphthalic acid, 2-propenepyrene One or more of oxyethyl acid phosphate and 2-methacryloxyethyl acid phosphate.

Further, in the above formula (1), R ₁₂ may be a group which does not contain an -OH group, and as such a compound, for example, ethyl methacrylate, n-butyl methacrylate or methacrylic acid can be used. Isobutyl ester, butyl methacrylate, isoamyl acrylate, 2-ethylhexyl methacrylate, isodecyl methacrylate, n-dodecyl acrylate, n-dodecyl methacrylate Ester, n-tridecyl methacrylate, n-octadecyl acrylate, n-octadecyl methacrylate, isostearyl acrylate, ethoxy diethylene glycol acrylate, methyl Butyl diethylene glycol acrylate, methoxy triethylene glycol acrylate, 2-ethylhexyl diethylene glycol acrylate, methoxy polyethylene glycol acrylate, methoxy poly methacrylate Glycol ester, methoxydipropylene glycol acrylate, cyclohexyl methacrylate, tetrahydrofurfuryl acrylate, tetrahydrofurfuryl methacrylate, benzyl methacrylate, phenoxyethyl acrylate, benzyl methacrylate Oxyethyl ester, phenoxy diethylene glycol acrylate, phenoxy poly acrylate Ester, nonylphenol ethylene oxide modified acrylate, phenylphenol ethylene oxide modified acrylate, isodecyl acrylate, isodecyl methacrylate, dimethylaminoethyl methacrylate, A One or more of diethylaminoethyl acrylate, dimethylaminoethyl methacrylate quaternary compound, glycidyl methacrylate, and neopentyl glycol acrylate.

In the first embodiment, for example, phenoxyethyl methacrylate or cyclohexyl methacrylate may be used, and a compound having a cyclic structure may be contained in R ₁₂ , and exemplified 2-ethylhexyl methacrylate R ₁₂ such as an ester, n-dodecyl acrylate or n-dodecyl methacrylate comprises a compound having a linear or branched alkyl group.

The (B2) compound having two or more (meth)acrylic groups in the molecule may, for example, be bis(meth)acrylate. Examples of such a bis(meth)acrylate include 4,4'-isopropylidenediphenol di(meth)acrylate, 1,3-butylene glycol di(meth)acrylate, and 1,6. - bis((meth)acryloxy)-2,2,3,3,4,4,5,5-octafluorohexane, 1,4-bis((meth)acryloxy)butyl Alkane, 1,6-bis((meth)acryloxy)hexane, triethylene glycol di(meth)acrylate, neopentyl glycol di(meth)acrylate, N,N'-di (Meth)acryloylethylenediamine, N,N'-(1,2-dihydroxyethylidene)bis(meth)acrylamide or 1,4-bis((meth)acrylonitrile) Piper Wait.

The content of the (B) (meth)acrylic monomer in the die attach paste of the first embodiment is preferably 4% by mass or more based on all the die attach paste systems, and more preferably 6% by mass or more. The mass % or more is further preferable. Thereby, it is possible to have appropriate viscosity and hardenability as the obtained paste.

On the other hand, the content of the (B) (meth)acrylic monomer in the die attach paste is preferably 27% by mass or less based on all the die attach paste systems, and more preferably 20% by mass or less, and 18 mass%. % or less is further preferable, and 15% by mass or less is most preferable. Thereby, it is possible to have appropriate viscosity and hardenability as the obtained paste depending on the type of the filler to be used.

(B) a (meth)acrylic monomer, for example, comprising (B1) a compound having only one (meth)acrylic group in the molecule, that is, a monofunctional (meth)acrylic monomer and (B2) having a molecule Two or more (meth)acrylic-based compounds, that is, polyfunctional (meth)acrylic monomers are preferred.

When the (B) (meth)acrylic monomer contains both a monofunctional (meth)acrylic monomer and a polyfunctional (meth)acrylic monomer, it is monofunctional with respect to the polyfunctional (meth)acrylic monomer (A) The upper limit of the ratio of the content of the acrylic monomer is, for example, preferably 10 or less, more preferably 9 or less, still more preferably 8 or less, further preferably 5 or less, and particularly preferably 4 or less. Thereby, it is possible to suppress generation of the (B) (meth)acrylic monomer which does not contribute to polymerization due to an excess of the polyfunctional (meth)acrylic monomer. Thereby, a strong crosslinked structure can be formed and the reflow resistance can be improved.

Further, when the (B) (meth)acrylic monomer contains both a monofunctional (meth)acrylic monomer and a polyfunctional (meth)acrylic monomer, the polyfunctional (meth)acrylic monomer and the monofunctional (A) The lower limit of the ratio of the content of the acrylic monomer may be, for example, 0.3 or more, and may be 0.5 or more.

((C) filler)

The die attach paste of the first embodiment contains (C) a filler.

(C) The shape of the filler is not particularly limited, and examples thereof include a spherical shape, a flake shape, and the like. In the first embodiment, it is more preferable that the (C) filler contains spherical particles. Thereby, the dispersibility of the (C) filler in the paste can be improved.

Moreover, as for the conductive paste, from the viewpoint of improving conductivity, (C) the filler may contain a sheet-like particle. Further, the (C) filler may further contain both spherical particles and flake particles from the viewpoint of improving the balance between conductivity and dispersibility.

Examples of the (C) filler include inorganic fillers such as cerium oxide or aluminum oxide, organic fillers such as polymethyl sesquioxane (polyoxy siloxane) or polymethyl methacrylate, and Ag powder (silver powder). ), metal fillers such as Au powder (gold powder) and Cu powder (copper powder). These may be used alone or in combination of two or more. As the (C) filler, for example, a metal filler is preferably used. Thereby, the thermal conductivity and electrical conductivity of the adhesive layer obtained by using the die attach paste can be effectively improved. In addition, as the metal filler, a metal component other than silver, gold, and copper may be used for the purpose of cost reduction.

In the first embodiment, from the viewpoint of chemical stability and cost, a more preferable aspect is (C) filler-based silver powder, cerium oxide, aluminum oxide or polymethyl sesquioxanes (polyoxyl oxyalkylene resin). ).

In the first embodiment, the particle diameter D ₅₀ at the time of 50% accumulation in the volume-based particle size distribution of the filler (C) is 0.3 μm or more and 4.0 μm or less. By adjusting the particle size of the (C) filler in this manner and combining it with the specific resin component, the die attach paste of the first embodiment can exhibit higher reflow resistance when the adhesive layer is obtained. Further, the die attach paste of the first embodiment can be adjusted to have such a particle diameter, and it is possible to suppress application of the die attach paste to the substrate, and when the semiconductor device is mounted on the paste, the paste climbs to the component. The side of the situation.

From the same viewpoint, the particle diameter D ₅₀ at the time of cumulative 50% in the volume-based particle size distribution of the (C) filler is _more preferably 0.8 μm or more, and still more preferably 1 μm or more.

Further, the particle diameter D ₅₀ at the time of accumulating 50% in the volume-based particle size distribution of the (C) filler is _more preferably 3.9 μm or less, further preferably 3.5 μm or less.

The particle size of the (C) filler can be determined, for example, by particle image measurement using a flow type particle image analyzer FPIA (registered trademark)-3000 manufactured by Sysmex Corporation. More specifically, the particle size of the (C) filler can be determined by measuring the volume-based median diameter using the above apparatus. Regarding the method of determining the particle diameter, in addition to D ₅₀ , the same conditions can be applied to D ₉₀ shown below.

By using such a condition, for example, when particles having a large particle diameter are present, the influence can be sensitively detected, and even a particle having a narrow particle size distribution can be measured with high precision.

Further, in the first embodiment (C), the width of the particle size distribution of the filler is preferably set to be narrow.

More specifically, when the particle diameter D ₉₀ at the cumulative 90% of the volume-based particle size distribution of the filler is measured (C), and the ratio to the above D ₅₀ (D ₉₀ /D ₅₀ ) is calculated, the ratio is 3.5 or less is preferable, 3 or less is more preferable, and 2.5 or less is further preferable.

Thus, by adjusting the ratio of D ₉₀ to D ₅₀ (D ₉₀ /D ₅₀ ), the dispersibility of the (C) filler in the die attach paste can be further improved, and the reflow resistance can be improved.

Further, the lower limit of the ratio of D ₉₀ to D ₅₀ (D ₉₀ /D ₅₀ ) is not particularly limited, and is, for example, 1.05 or more.

Further, it is preferable that the particle diameter D ₉₀ at the time of 90% accumulation in the volume-based particle size distribution of the filler (C) is 0.8 μm or more, more preferably 1 μm or more, and further preferably 1.5 μm or more.

Further, (C) the particle size D ₉₀ in the volume-based distribution of the volume-based distribution of the filler is preferably 15 μm or less, more preferably 12 μm or less, and still more preferably 7 μm or less. Thereby, the particle size distribution of the (C) filler can be made clear. When the particle size distribution of the (C) filler is sharp, it is easy to aggregate (C) the filler at the interface of the die attach paste. Thereby, the hardening shrinkage in the interface of the die attach paste can be reduced, and the increase in the interface stress can be suppressed. Moreover, it is convenient from the viewpoint of being able to increase the strength of the interface of the die attach paste

By setting the value of D( ₉₀ ) of the filler in (C) as described above, it is possible to more effectively improve the balance between conductivity and coatability in the conductive paste.

The content of the (C) filler in the die attach paste of the first embodiment is preferably, for example, 25 mass% based on all the die attach paste systems, more preferably 50 mass% or more, and further 60 mass% or more. Good, 70% by mass or more is the best. Thereby, it is possible to have appropriate conductivity or absolute properties as the obtained adhesive layer.

On the other hand, the content of the (C) filler in the die attach paste is preferably 90% by mass or less based on all the die attach paste systems, more preferably 85% by mass or less, and most preferably 80% by mass or less. . Thereby, the viscosity of the paste can be set to an appropriate range, and the workability at the time of coating can be improved.

((D) Other resin components)

In the first embodiment, other resin components may be contained in addition to the component (A).

Examples of such a resin component include a cyanate resin, an epoxy resin, a (meth)acrylic resin other than the component (A), a maleimide resin, an allyl ester resin, and a polycarbonate. Resin, etc.

The (D) other resin component is preferably a functional group having a reaction with the (A) (meth)acrylic copolymer as described above. Thereby, the degree of hardening shrinkage of the die attach paste can be controlled. Further, examples of the functional group reactive with the (A) (meth)acrylic copolymer include a group having a carbon-carbon double bond C=C; a maleimide ring; an epoxy group.

(D) The other resin component can also be polymerized and reacted in the same manner as the above component (A) depending on the blending composition. The curing shrinkage caused by the polymerization and reaction of (D) other resin components is smaller than the hardening shrinkage caused by the polymerization or reaction of the component (A). Therefore, the die attach paste can be appropriately hardened and shrunk by adjusting the content of (D) other resin components.

In the first embodiment, it is preferable that the die attach paste contains one or more components selected from the group consisting of (D1) allyl ester resin and (D2) polycarbonate resin.

In the present specification, the (D1) allyl ester resin refers to a resin obtained by transesterification of allyl alcohol with various raw materials or a resin obtained by chemically modifying the resin.

As the (D1) allyl ester resin, an aliphatic group is preferable, and among them, a compound obtained by transesterification of a cyclohexane diallyl ester with an aliphatic polyol is preferable. Further, the weight average molecular weight of the (D1) allyl ester resin is not particularly limited, and is preferably 500 or more and 10,000 or less, and particularly preferably 500 or more and 8,000 or less. When the weight average molecular weight is within the above range, the curing shrinkage can be particularly reduced, and the adhesion can be prevented from being lowered.

As the (D1) allyl ester resin, "DA101" manufactured by SHOWA DENKO K.K., or the like can be used.

(D2) The polycarbonate resin is a resin containing a carbonate bond, and is a polymer or copolymer obtained by reacting a hydroxy compound or a small amount of a polyhydroxy compound with a carbonate precursor.

In the first embodiment, as the (D2) polycarbonate resin, a polycarbonate obtained by reacting 1,4-cyclohexanedimethanol, 1,6-hexanediol, and dimethyl carbonate can be preferably used. An ester diol or a modified polycarbonate compound obtained by reacting the polycarbonate diol with (meth)acrylic acid or a derivative thereof.

The content of the (D) other resin component in the die-adhesive paste of the first embodiment is preferably 2% by mass or more, more preferably 3% by mass or more, and 5% by mass or more, based on 2% by mass or more of all the die attach paste systems. Further preferred. Thereby, the desired adhesiveness derived from the resin can be exhibited.

On the other hand, the content of the (D) other resin component in the die attach paste is preferably 20% by mass or less based on all the die attach paste systems, more preferably 15% by mass or less, and even more preferably 12% by mass or less. Preferably. Thereby, the viscosity of the paste can be reduced, and the workability at the time of coating can be further improved.

((E) decane coupling agent)

The die attach paste of the first embodiment can contain, for example, (E) a decane coupling agent.

Thereby, the adhesion to the base material of the die adhesion paste can be further improved.

As the (E) decane coupling agent, for example, various decane compounds such as epoxy decane, decyl decane, amino decane, alkyl decane, ureido decane, vinyl decane, and (meth) decyl methoxide can be used.

If exemplified, vinyl trichloromethane, vinyl trimethoxy decane, vinyl triethoxy decane, vinyl ginseng (β-methoxyethoxy) decane, γ-methyl propylene oxime Propyltrimethoxydecane, β-(3,4-epoxycyclohexyl)ethyltrimethoxydecane, γ-glycidoxypropyltrimethoxydecane (3-epoxypropoxypropane) Trimethoxydecane), γ-glycidoxypropyltriethoxydecane, γ-glycidoxypropylmethyldimethoxydecane, γ-methacryloxypropylpropyl Diethoxy decane, γ-methyl propylene methoxy propyl triethoxy decane, vinyl triethoxy decane, phenylaminopropyl trimethoxy decane, γ-aminopropyl three Ethoxydecane, γ-anilinopropyltrimethoxydecane, γ-anilinopropylmethyldimethoxydecane, γ-[bis(β-hydroxyethyl)]aminopropyltriethoxy Decane, N-β-(aminoethyl)-γ-aminopropyltrimethoxydecane, N-β-(aminoethyl)-γ-aminopropyltriethoxydecane, N-β -(Aminoethyl)-γ-aminopropylmethyldimethoxydecane, N-phenyl-γ-aminopropyl Trimethoxy decane, γ-(β-aminoethyl)aminopropyl dimethoxymethyl decane, N-(trimethoxymethyl propyl) ethylenediamine, N-(dimethoxymethyl) Ethyl isopropyl) ethylenediamine, methyltrimethoxydecane, dimethyldimethoxydecane, methyltriethoxydecane, N-β-(N-vinylbenzylaminoethyl -γ-aminopropyltrimethoxydecane, γ-chloropropyltrimethoxydecane, hexamethyldioxane, vinyltrimethoxydecane, 3-isocyanatepropyltriethoxydecane, 3-propene醯oxypropyltrimethoxydecane, 3-(trimethoxydecyl)propyl methacrylate, 3-triethoxyindolyl-N-(1,3-dihydroxymethylbutylene)propyl a decane coupling agent such as a sulfhydryl group or a hydrolyzate thereof. These may be used alone or in combination of two or more.

As the decane coupling agent, for example, a decane coupling agent having a (meth)acrylic group is preferred. Thereby, the affinity of the (C) filler and the die attach paste can be improved, and the adhesiveness can be improved.

The content of the (E) decane coupling agent in the die attach paste of the first embodiment is preferably 0.05% by mass or more based on all the die attach pastes, more preferably 0.1% by mass or more, and more preferably 0.15% by mass or more. Further preferred. Thereby, the adhesiveness as a paste can be further improved.

On the other hand, the content of the (E) decane coupling agent in the die attach paste is preferably 5% by mass or less based on all the die attach paste systems, more preferably 3% by mass or less, and still more preferably 2% by mass or less. Preferably. Thereby, the amount of volatilization at the time of curing of the unreacted decane coupling agent can be reduced, and wire bonding can be further improved.

((F) low stress agent)

Further, the die attach paste of the first embodiment can contain (F) a low stress agent.

The (F) low stress agent is not particularly limited as long as it can reduce the stress of the die attach paste of the first embodiment, and examples thereof include acrylic rubber, polyoxyethylene rubber, urethane rubber, and styrene-butyl. Diene rubber, butadiene rubber or modified substances thereof. These may be used alone or in combination of two or more.

The content of the (F) low stress agent in the die attach paste of the first embodiment is preferably 0.5% by mass or more based on all the die attach pastes, more preferably 0.8% by mass or more, and 1% by mass or more. Further preferred. Thereby, it is possible to impart appropriate low stress to the die attach paste of the first embodiment, and it is possible to improve the reflow resistance.

On the other hand, the content of the (F) low stress agent in the die attach paste is preferably 5% by mass or less based on all the die attach paste systems, more preferably 4% by mass or less, and 3% by mass or less is further. Preferably. Thereby, the viscosity of the paste can be reduced, and the workability at the time of coating can be further improved.

As the (F) low stress agent, a functional group having a reaction with the (A) (meth)acrylic copolymer is preferred. Thereby, a soft structure can be introduced into the crosslinked structure. Therefore, it is preferable from the viewpoint of reducing the interface stress.

Further, examples of the functional group reactive with the (A) (meth)acrylic copolymer include a carbon-carbon double bond such as an acryl group, a vinyl group, or a maleimide ring; an epoxy group; an amine group; Carboxyl group, hydroxyl group, and the like.

(F) The low stress agent can be radically polymerized and ion-polymerized together with the (A) (meth)acrylic copolymer, for example, by having a carbon-carbon double bond such as an acrylic group, a vinyl group, or a maleimide ring. .

Further, the (F) low stress agent can be reacted when the (A) (meth)acrylic copolymer has an amine group, a carboxyl group, a hydroxyl group or the like, for example, by providing an epoxy group.

Further, the (F) low stress agent can be reacted when the (A) (meth)acrylic acid copolymer has an epoxy group or the like, for example, by having an amine group, a carboxyl group or a hydroxyl group.

(other ingredients)

In addition to the above-mentioned components, the die attach paste of the first embodiment may further contain a known additive such as a curing agent, a curing accelerator, a polymerization initiator, a polymerization inhibitor, an antifoaming agent, or a surfactant.

The amount of these additions can be arbitrarily set depending on the physical properties imparted.

Hereinafter, the main component will be described.

(hardening accelerator)

The die attach paste of the first embodiment may contain, for example, a hardening accelerator which promotes a curing reaction by an epoxy group of the (A) (meth)acrylic copolymer.

Specific examples of the curing accelerator include an organic phosphine, a tetrasubstituted fluorene compound, a phosphoric acid betaine compound, an adduct of a phosphine compound and an anthracene compound, and a phosphorus atom-containing compound such as an adduct of a hydrazine compound and a decane compound; a decyl group or an amine group such as dicyandiamide, 1,8-diazabicyclo[5.4.0]undecene-7, benzyldimethylamino group; the above thiol group or the above-mentioned tertiary amine group 4 A hydrogen atom-containing compound or the like such as an ammonium salt. As the curing accelerator, one type of the above specific examples or a combination of two or more types can be used.

((S) solvent)

The die attach paste of the first embodiment can contain a (S) solvent as needed. Thereby, the fluidity of the paste can be improved, and the workability can be improved. Further, the (S) solvent means those which do not satisfy the above respective components.

The solvent (S) is not particularly limited, and for example, one or two or more selected from the group consisting of ethanol, propanol, butanol, pentanol, hexanol, heptanol, octanol, decyl alcohol, and decyl alcohol can be contained. Ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monopropyl ether, ethylene glycol monobutyl ether, propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol monopropyl ether, propylene glycol monobutyl ether, methyl methoxy Alcohols such as butanol, α-terpineol, β-terpineol, hexanediol, benzyl alcohol, 2-phenylethanol, isopalmitol, isostearyl alcohol, lauryl alcohol, ethylene glycol, propylene glycol or glycerol Class; acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, diacetone alcohol (4-hydroxy-4-methyl-2-pentanone), 2-octanone, isophorone ( Ketones such as 3,5,5-trimethyl-2-cyclohexen-1-one) or diisobutyl ketone (2,6-dimethyl-4-heptanone); ethyl acetate, butyl acetate Ester, diethyl phthalate, dibutyl phthalate, ethoxylated ethane, methyl butyrate, methyl hexanoate, methyl octanoate, methyl decanoate, methyl cellosolve B Acid ester, ethylene glycol monobutyl ether acetate, propylene glycol monomethyl ether acetate, 1, 2-diethyl hydrazine Esters such as oxyethane, tributyl phosphate, tricresyl phosphate or triamyl phosphate; tetrahydrofuran, dipropyl ether, ethylene glycol dimethyl ether, ethylene glycol diethyl ether, ethylene glycol dibutyl ether, propylene glycol Ethers such as methyl ether, ethoxyethyl ether, 1, 2-bis(2-diethoxy)ethane or 1,2-bis(2-methoxyethoxy)ethane; acetic acid 2-(2) Ester ethers such as -butoxyethoxy)ethane; ether alcohols such as 2-(2-methoxyethoxy)ethanol, toluene, xylene, normal paraffins, isoparaffins, dodecyl Hydrocarbons such as benzene, turpentine, kerosene or light oil; nitriles such as acetonitrile or propionitrile; decylamines such as acetamide or N,N-dimethylformamide; low molecular weight volatile eucalyptus or volatility Organically modified oyster sauce and other oyster sauces.

The die attach paste of the first embodiment can be obtained by mixing the above components.

For example, it can be prepared by pre-mixing each component, kneading using three rolls, and performing defoaming under vacuum.

In the die attach paste of the first embodiment, it is preferable to control the viscosity to a specific range from the viewpoint of improving coatability and workability.

Specifically, the die attach paste of the first embodiment is set to have a viscosity measured at 25° C. and 5.0 rpm using a Brookfield viscometer at a range of 3 Pa·s or more and 30 Pa·s or less. Preferably, the range of 8 Pa ‧ s or more and 28 Pa ‧ s or less is more preferably set, and the range of 10 Pa ‧ or more and 25 Pa ‧ s or less is further preferable.

Further, the viscosity of the die attach paste can be measured, for example, at 25 ° C and 5.0 rpm using a Brookfield viscometer 1.5 degree cone.

(semiconductor device)

Next, an example of the semiconductor device of the first embodiment will be described.

Fig. 1 is a cross-sectional view showing a semiconductor device 100 according to a first embodiment. The semiconductor device 100 of the first embodiment includes a substrate 30 and a semiconductor element 20 which is mounted on the substrate 30 via an adhesive layer (die adhesion layer 10) which is a cured product of a die attach paste. . The semiconductor element 20 and the substrate 30 are electrically connected by, for example, a bonding wire 40 or the like. Further, the semiconductor element 20 is sealed by, for example, the sealing resin 50. The film thickness of the die attach layer 10 is not particularly limited, and is, for example, 5 μm or more and 100 μm or less.

In the example shown in FIG. 1, the substrate 30 is, for example, a lead frame. In this case, the semiconductor element 20 is mounted on a die pad 32 (substrate 30) via the die attach layer 10. Further, the semiconductor element 20 is electrically connected to an outer lead 34 (substrate 30) by, for example, a bonding wire 40. The base material 30 as the lead frame is made of, for example, a 42 alloy or a copper frame. Further, the substrate 30 may be an organic substrate or a ceramic substrate. As the organic substrate, for example, a substrate known to those skilled in the art such as an epoxy resin, a cyanate resin, or a maleimide resin is preferably used. Further, in order to make adhesion to the die attach paste, the surface of the substrate 30 may be covered with silver or the like.

The planar shape of the semiconductor element 20 is not particularly limited, and is, for example, a rectangle. In the first embodiment, for example, a rectangular semiconductor element 20 having a wafer size of 0.5 × 0.5 mm or more and 15 × 15 mm or less can be used.

As an example of the semiconductor device 100 of the first embodiment, for example, a large rectangular wafer having a side of 5 mm or more is used as the semiconductor element 20.

FIG. 2 is a cross-sectional view showing a modification of the semiconductor device 100 shown in FIG. 1. In the semiconductor device 100 of the present modification, the substrate 30 is, for example, an interposer. For example, a plurality of solder balls 52 are formed on the other surface of the substrate 30 as the interposer opposite to the surface on which one surface of the semiconductor element 20 is mounted. In this case, the semiconductor device 100 is connected to another wiring board via the solder ball 52.

The semiconductor device 100 of the first embodiment can be manufactured, for example, as follows. First, the semiconductor element 20 is mounted on the substrate 30 by the die attach paste. Next, the die attach paste is heated. Thereby, the base material 30 is connected to the semiconductor element 20, and the semiconductor device 100 is manufactured.

Hereinafter, a method of manufacturing the semiconductor device 100 will be described in detail.

First, the semiconductor element 20 is mounted on the substrate 30 via the die attach paste. In the first embodiment, for example, after the die attach paste is applied onto the substrate 30, the semiconductor element 20 is mounted on the coating film made of the die attach paste. The method of applying the die attach paste is not particularly limited, and examples thereof include a dispensing method, a printing method, and an ink jet method.

Next, the die attach paste is heat-treated to harden the contained resin component. Thereby, the die attach layer 10 is formed on the substrate 30. In the first embodiment, for example, heat treatment can be performed while pressurizing the die adhesion paste.

The temperature condition of the heat treatment can be appropriately set depending on the composition of the paste or the like.

Next, the semiconductor element 20 is electrically connected to the substrate 30 using the bonding wires 40. Next, the semiconductor element 20 is sealed with a sealing resin 50. In the first embodiment, for example, the semiconductor device 100 can be manufactured in this manner.

In the first embodiment, for example, a heat dissipation plate can be bonded to the semiconductor device. In this case, for example, the heat sink can be bonded to the semiconductor device via the adhesive layer obtained by heat-treating the die attach paste.

The bonding method of the heat sink can be performed, for example, as follows. First, the semiconductor device and the heat dissipation plate are bonded by the die adhesion paste. Next, the die attach paste is heat treated. The conditions for the heat treatment of the die attach paste in this case are, for example, the same as the conditions of the heat treatment in the method of manufacturing the semiconductor device 100 described above, and can be appropriately set depending on the composition of the paste or the like. Thereby, an adhesive layer adhered to the heat dissipation plate is formed. In this way, the heat sink can be bonded to the semiconductor device.

Further, the present invention is not limited to the above-described embodiments, and modifications, improvements, etc. within a scope that can achieve the object of the present invention are included in the present invention.

Hereinafter, an example of a reference form is attached.

A die attach paste comprising: (A) a (meth)acrylic copolymer having a reactive group at a terminal; (B) a (meth)acrylic monomer; and (C) a filler, the aforementioned (A) The reactive group provided in the (meth)acrylic copolymer is one or more selected from the group consisting of an epoxy group, an amine group, a vinyl group, a carboxyl group, and a hydroxyl group, and the (A) (meth)acrylic acid copolymer is copolymerized. The weight average molecular weight of the material is 2,000 or more and 14,000 or less, and the particle diameter D ₅₀ at the time of 50% accumulation in the volume-based particle size distribution of the (C) filler is 0.3 μm or more and 4.0 μm or less.

2. The die attach paste of 1, wherein the (C) filler is silver powder, cerium oxide, aluminum oxide or polymethylsesquioxane.

3. The die attach paste of 1. or 2. further comprising (D1) an allyl ester resin.

4. The die attach paste of 1, or 2. further comprising (D2) a polycarbonate resin.

5. The die attach paste of any one of 1. to 4. further comprising (E) a decane coupling agent.

6. The die attach paste of any one of 1. to 5. further comprising (F) a low stress agent.

7. The die attach paste according to any one of the above aspects, wherein the above-mentioned (C) filler is contained in an amount of 25% by mass or more and 90% by mass or less based on the total of the above-mentioned die attach paste.

8. The die attach paste according to any one of the above aspects, wherein the (C) filler is spherical or flake-shaped.

The die attach paste of any one of the above-mentioned (C) fillers, wherein the particle size D ₅₀ at the cumulative 50% of the volume-based particle size distribution of the aforementioned (C) filler is the same as the aforementioned (C) filler The ratio (D ₅₀ /D ₉₀ ) of the particle diameter D ₉₀ at the cumulative 90% of the volume-based particle size distribution is 1.05 or more and 3.5 or less.

10. The die attach paste according to any one of items 1 to 9, wherein the viscosity of the die attach paste is 3 Pa ‧ or more measured at 25 ° C and 5.0 rpm using a Brookfield viscometer Below 30Pa‧s.

A semiconductor device comprising: a substrate; and a semiconductor element mounted on the substrate via an adhesive layer of a heat-treated body of the die attach paste of any one of 1. to 10.

<Second embodiment>

Hereinafter, the die attach paste of the second embodiment will be described.

According to a second embodiment, there is provided a die attach paste comprising silver particles, a monomer, a main component, and a radical polymerization initiator, wherein the die adhesion paste is applied to a coating thickness of 35 ± 5 μm. On a silver-plated copper frame having a length of 15.5 mm and a width of 6.5 mm, a tantalum wafer having a length of 15.0 mm, a width of 6.0 mm, and a thickness of 0.2 mm was placed on the die attach paste to obtain a laminate, and the laminate was laminated for 30 minutes. The body was heated from 25 ° C to 175 ° C, and further heat-treated at 175 ° C for 5 hours to obtain a cured body. The amount of warpage when the cured body was heat-treated at 275 ° C for 1 minute was W1, and the hardening was performed. After the temperature was 85 ° C and the humidity was 85%, the amount of warpage at the time of heat treatment at 275 ° C for 1 minute was W2, and |W2-W1| was 20 μm or less. Here, the amount of warpage indicates a diagonal line connecting any two vertices located at opposite corners in the in-plane direction of the ytterbium wafer, and a distance from the position where the ruthenium wafer exists in a direction perpendicular to the diagonal line. Maximum value.

Here, the Ag powder (silver powder) of the (C) filler in the first embodiment means the silver particles in the second embodiment.

Further, the (B) (meth)acrylic acid single system in the first embodiment means the acrylic monomer in the second embodiment.

In the first embodiment, the (A) (meth)acrylic copolymer having a reactive group or the (D) other resin component is the main component in the second embodiment.

In addition, the polymerization initiator in the first embodiment is a radical polymerization initiator in the second embodiment.

In the field of conventional die attach pastes, it is considered that the cause of warpage of the semiconductor device at the time of mounting is the internal stress generated in the die attach paste by heat treatment. In the conventional technical standards, it is considered that the heat such as the heat treatment temperature has a large influence on the internal stress, and the moisture absorption of the cured product of the die attach paste is not considered.

Further, in the second embodiment, the cured product means a die attach paste which is cured by heat treatment. Here, as a condition of the heat treatment, for example, it can be set from a room temperature of 25 ° C to a temperature of 100 ° C or more and 300 ° C or less, and the temperature is raised for 10 minutes to 2 hours, and further, at a temperature after the temperature rise, 10 Heat treatment from minute to 2 hours.

The present inventors have studied the reason why the degree of warpage of the semiconductor device is different even when the heat treatment conditions at the time of mounting are the same in the semiconductor device produced by using the conventional die attach paste. As a result, it was found that moisture absorption of the cured product of the die attach paste contributes to warpage of the semiconductor device. Specifically, it is clarified that when the cured product of the die attach paste absorbs moisture as compared with the case where moisture absorption is not performed, the warpage caused by the heat treatment is remarkably small. Although the detailed mechanism is uncertain, the reason is presumed to be as follows: the hardened material of the die attach paste swells due to moisture absorption, and moderates the internal stress generated by the heat treatment.

However, considering the mounting steps of the semiconductor device and the use conditions of the semiconductor device, it is difficult to completely prevent moisture absorption of the die attach paste. Then, the inventors of the present invention considered that the absolute value of the difference between the warpage of the semiconductor device in the case where the cured product of the die-adhesive paste is not moisture-absorbed and the warpage of the semiconductor device in the case where moisture absorption has been performed is set to It will be within the specific numerical range described later. Thereby, the cured product of the die adhesion paste is suppressed from swelling due to moisture absorption, and the amount of warpage is greatly reduced, thereby providing a die attach paste capable of improving the mounting reliability of the semiconductor device.

First, each raw material component of the die attach paste of the second embodiment will be described.

(silver particles)

The die attach paste of the second embodiment contains silver particles.

In the die attach paste of the second embodiment, the silver particles are agglomerated by the curing shrinkage of the monomer or the main component described later, and exhibit excellent thermal conductivity during curing.

The shape of the silver particles is not limited, and may be in the form of a sheet or a sphere. As the silver particles, a sheet or a sphere may be used alone, or a sheet or a sphere may be used at the same time.

The upper limit of the aspect ratio of the silver particles is preferably 20 or less, more preferably 15 or less, and still more preferably 12 or less. Thereby, it is possible to suppress the dispersion of the silver particles with anisotropy. Thereby, when the cured product of the die attach paste has been moisture-absorbing, it is possible to suppress the occurrence of anisotropy in the relaxation of the internal stress.

In addition, the lower limit of the aspect ratio of the silver particles may be, for example, 1.00 or more, or may be 1.05 or more.

Further, in the second embodiment, the aspect ratio of the silver particles can be obtained by (long diameter) / (short diameter) of the silver particles. The long diameter and the short diameter of the silver particles can be evaluated, for example, by direct observation by a scanning electron microscope (SEM) or a transmission electron microscope (TEM). Hereinafter, an evaluation method using a scanning electron microscope will be described. First, silver particles were fixed to a sample stage of a scanning electron microscope, and only one particle having an increased observation magnification entered the maximum limit of the field of view, and the shape was observed, and the direction was observed from the direction of the largest surface of the observation area of the silver particles. Next, the sample stage was rotated, and the surface of the silver particles having the smallest observation area was observed. In the above observation, the maximum surface of the observation area of the silver particles is defined as the "long diameter" of the silver particles with respect to a straight line connecting any two points of the region where the silver particles exist. Further, regarding the smallest surface of the observation area of the silver particles, the interval of the parallel lines drawn so that the two parallel lines are closest to each other and the silver particles are sandwiched is defined as "short diameter". This operation was performed on 100 silver particles arbitrarily extracted, and an average value was calculated to obtain an aspect ratio.

The upper limit of the tap density of the silver particles is preferably, for example, 10.0 g/cm ³ or less, more preferably 8.0 g/cm ³ or less, still more preferably 6.0 g/cm ³ or less, and 5.4 g/cm ^{3 .} The following is further preferred. Thereby, it is possible to suppress the occurrence of density in the silver particles in the cured product of the die attach paste. Therefore, it is possible to suppress the local increase in warpage before and after moisture absorption.

In addition, the lower limit of the tap density of the silver particles is preferably 2.5 g/cm ³ or more, more preferably 3.0 g/cm ³ or more, and still more preferably 3.2 g/cm ³ or more. Thereby, the silver particles can be highly filled, and the heat dissipation property of the cured product of the die adhesion paste can be improved.

The cumulative frequency of the volume-based particle size distribution of the silver particles is 50% of the upper limit of the particle diameter D ₅₀ , and is preferably 20 μm or less, more preferably 10 μm or less. Thereby, it is possible to suppress the occurrence of density in the silver particles in the cured product of the die attach paste by reducing the coarse silver particles. Therefore, it is possible to suppress the local increase in warpage before and after moisture absorption. In addition, the lower limit of the particle diameter D ₅₀ when the cumulative frequency of the volume-based particle size distribution of the silver particles is 50% may be, for example, 0.1 μm or more, or may be 0.5 μm or more.

Further, the D _{50 of the} silver particles can be, for example, a commercially available laser diffraction type particle size distribution measuring device (for example, SALD-7000, manufactured by Shimadzu Corporation) and the particle size distribution of the particles can be measured in accordance with the volume standard, and by accumulating 50%. The particle size was determined.

The upper limit of the average particle diameter of the silver particles is preferably 20 μm or less, more preferably 15 μm or less, and still more preferably 12 μm or less. Thereby, it is possible to suppress the occurrence of density in the silver particles in the cured product of the die attach paste by reducing the coarse silver particles. Therefore, it is possible to suppress the local increase in warpage before and after moisture absorption.

In addition, the lower limit of the average particle diameter of the silver particles may be, for example, 0.1 μm or more, or may be 0.5 μm or more, or may be 1.0 μm or more. Thereby, it is also convenient from the viewpoint of suppressing the aggregation of the small silver particles by the monomer and the main agent, and improving the adhesion of the die attach paste.

The lower limit of the specific surface area of silver particles, for example, based 0.10m ² / g or more is preferred, 0.20m ² / g or more is more preferred, 0.25m ² / g or more is further preferred. Thereby, an appropriate cohesive force is exerted on the silver particles by curing and shrinkage of the monomer and the main agent. Thereby, the mounting reliability of the semiconductor device using the cured product of the die attach paste can be improved.

In addition, the upper limit of the specific surface area of the silver particles can be, for example, 1.50 m ² /g or less, or 1.40 m ² /g or less.

The lower limit of the content of the silver particles in the die attach paste is preferably 50 parts by mass or more based on 100 parts by mass of the die attach paste, more preferably 60 parts by mass or more, and more preferably 65 parts by mass or more. Preferably, 70 parts by mass or more is further preferred. Thereby, the cured product of the die attach paste can exhibit better thermal conductivity.

In addition, the upper limit of the content of the silver particles in the die attach paste may be, for example, 90% by mass or less, or may be 88% by mass or less, based on 100 parts by mass of the die attach paste.

(monomer)

The die attach paste of the second embodiment is largely cured and shrunk by the curing of the monomer. Thereby, the die attach paste can largely agglomerate the silver particles and exhibit high thermal conductivity.

Specific examples of such a monomer include an acrylic monomer, an epoxy monomer, and a maleimide monomer.

The acrylic monomer and the maleimide monomer can be polymerized by a radical polymerization initiator described later, and hardened and shrunk. The epoxy monomer can react with a hardener described later and harden and shrink.

As the monomer, one type of the above specific examples or a combination of two or more types can be used. As the monomer, an acrylic monomer or an epoxy monomer in the above specific examples is preferably used. Thereby, even if the die attach paste contains silver particles, the adhesion to materials other than the metal can be preferably exhibited, and the thermal conductivity can be further improved by the hardening shrinkage.

[acrylic monomer]

The acrylic single system of the second embodiment has a (meth)acrylic group-containing monomer in its structure. Here, the (meth)acrylic group means an acryl group and a methacryl group (methacrylate group).

The acrylic monomer of the second embodiment may be a monofunctional acrylic monomer having only one (meth)acrylic group in its structure, or may have two or more (meth)acrylic groups in its structure. Functional acrylic monomer.

Further, in the second embodiment, the acrylic group contains an acrylate group.

Specific examples of the monofunctional acrylic monomer include 2-phenoxyethyl 2-methacrylate, ethyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, and tertiary butyl methacrylate. , isoamyl acrylate, 2-ethylhexyl methacrylate, isodecyl methacrylate, n-dodecyl acrylate, n-dodecyl methacrylate, n-tridecyl methacrylate , n-octadecyl acrylate, n-octadecyl methacrylate, isostearyl acrylate, ethoxy diethylene glycol acrylate, butoxy diethylene glycol methacrylate, acrylic acid Methoxy triethylene glycol ester, 2-ethylhexyl diethylene glycol acrylate, methoxy polyethylene glycol acrylate, methoxy polyethylene glycol methacrylate, methoxy dipropylene glycol acrylate , cyclohexyl methacrylate, tetrahydrofurfuryl acrylate, tetrahydrofurfuryl methacrylate, benzyl methacrylate, phenoxyethyl acrylate, phenoxyethyl methacrylate, phenoxy bis acrylate Alcohol ester, phenoxy acrylate polyethylene glycol, nonyl phenol ethylene oxide Modified acrylate, phenylphenol ethylene oxide modified acrylate, isodecyl acrylate, isodecyl methacrylate, dimethylaminoethyl methacrylate, diethylaminoethyl methacrylate , dimethylaminoethyl methacrylate quaternary compound, glycidyl methacrylate, neopentyl glycol acrylate, 1,4-cyclohexane dimethanol monoacrylate, 2-hydroxy acrylate Ethyl ester, 2-hydroxyethyl methacrylate, 2-hydroxypropyl acrylate, 2-hydroxypropyl methacrylate, 2-hydroxybutyl acrylate, 2-hydroxybutyl methacrylate, 2-hydroxy-3- Phenoxypropyl acrylate, 2-propenyloxyethyl succinic acid, 2-methylpropenyloxyethyl succinic acid, 2-propenyloxyethyl hexahydrophthalic acid, 2-methyl Acryloxyethylhexahydrophthalic acid, 2-propenyloxyethylphthalic acid, 2-propenyloxyethyl-2-hydroxyethylphthalic acid, 2-propenepyrene Oxyethylethyl phosphate and 2-methylpropenyloxyethyl acid phosphate. As the monofunctional acrylic monomer, one type of the above specific examples or a combination of two or more types can be used.

As the monofunctional acrylic monomer, those selected from the above specific examples are selected from the group consisting of phenoxyethyl 2-methacrylate, 2-ethylhexyl methacrylate, 2-hydroxypropyl methacrylate, and 1,4-cyclohexane. One or more of the group consisting of alkane dimethanol monoacrylate and 2-methacryloxyethyl succinic acid is preferred. Thereby, the acrylic monomer can be preferably polymerized to further harden and shrink the die attach paste.

Specific examples of the polyfunctional acrylic monomer include ethylene glycol dimethacrylate, glycerin dimethacrylate, trimethylolpropane trimethacrylate, and propoxylated bisphenol A diacrylate. , polyethylene glycol di(meth)acrylate, hexane-1,6-diol bis(2-methacrylate), 4,4'-isopropylidene diphenolate (meth)acrylate , 1,3-butylene glycol (meth)acrylate, 1,6-bis((meth)acryloxy)-2,2,3,3,4,4,5,5-octafluoro Hexane, 1,4-bis((meth)acryloxy)butane, 1,6-bis((meth)acryloxy)hexane, triethylene glycol diester (meth)acrylate , neopentyl glycol di(meth)acrylate, neopentyl glycol di(meth)acrylate, N,N'-di(meth)acryloylethylenediamine, N,N'-(1, 2-dihydroxyethylidene bis(methyl)propenylamine or 1,4-bis((meth)acrylinyl)perylene , polycarbonate diol dimethacrylate, 1.6-hexanediol dimethacrylate, tris(2-hydroxyethyl) trimer isocyanate triacrylate, and the like.

As the polyfunctional acrylic monomer, the above specific examples are selected from the group consisting of ethylene glycol dimethacrylate, glycerin dimethacrylate, trimethylolpropane trimethacrylate, and propoxylated bisphenol A. Acrylate, polyethylene glycol di(meth)acrylate, polycarbonate glycol dimethacrylate, 1.6-hexanediol dimethacrylate, and tris(2-hydroxyethyl)trimeric isocyanate One or more of the groups of the acrylate composition are preferred.

Further, in the second embodiment, (meth) acrylate means methacrylate and acrylate.

The lower limit of the content of the acrylic monomer in the die attach paste is preferably 1.0 part by mass or more, more preferably 3.0 parts by mass or more, and even more preferably 5.0 parts by mass or more, based on 100 parts by mass of the die attach paste. 5.8 parts by mass or more is further preferred. Thereby, when the die attach paste is hardened, it can be further hardened and shrunk. Therefore, it is preferable from the viewpoint of improving the thermal conductivity of the cured product of the die attach paste.

The upper limit of the content of the acrylic monomer in the die attach paste is preferably 30 parts by mass or less based on 100 parts by mass of the die attach paste, more preferably 20 parts by mass or less, still more preferably 15 parts by mass or less. Further, 12 parts by mass or less is further preferred. Thereby, the absolute amount of moisture which the hardened material of the die-adhesive paste can absorb can be reduced. Therefore, it is possible to suppress swelling of the cured product of the die-adhesive paste due to moisture absorption, and the amount of warpage after moisture absorption of the cured product of the die-attachment paste is remarkably small as compared with the case of not absorbing moisture.

As the acrylic monomer, a monofunctional acrylic monomer or a polyfunctional acrylic monomer may be used alone, or a monofunctional acrylic monomer and a polyfunctional acrylic monomer may be used at the same time. As the acrylic monomer, for example, a monofunctional acrylic monomer and a polyfunctional acrylic monomer are preferably used at the same time.

When the monofunctional acrylic monomer and the polyfunctional acrylic monomer are used together as the acrylic monomer, the lower limit of the content of the monofunctional acrylic monomer in the die attach paste is, for example, 150 for the polyfunctional acrylic monomer. The mass portion or more is more preferably 200 parts by mass or more, more preferably 250 parts by mass or more. Thereby, the monomer has an appropriate branch shape by polymerization, and it is possible to suppress swelling of the cured product of the die adhesion paste due to moisture absorption. Therefore, it is possible to suppress swelling of the cured product of the die-adhesive paste due to moisture absorption, and the amount of warpage after moisture absorption of the cured product of the die-adhesive paste is remarkably small as compared with the case of not absorbing moisture.

When an acrylic monomer is used together with a monofunctional acrylic monomer and a polyfunctional acrylic monomer, the upper limit of the content of the monofunctional acrylic monomer in the die attach paste is, for example, 650 with respect to 100 parts by mass of the polyfunctional acrylic monomer. The mass portion is preferably 5% or less, more preferably 550 parts by mass or less, still more preferably 550 parts by mass or less, further preferably 500 parts by mass or less, and particularly preferably 400 parts by mass or less. Thereby, it is possible to suppress the occurrence of moisture absorption due to an excessive amount of the polyfunctional acrylic monomer to cause an acrylic group which does not contribute to polymerization.

Further, by using a monofunctional acrylic monomer and an acrylic polymer described later instead of using a monofunctional acrylic monomer and a polyfunctional acrylic monomer, the monomer has an appropriate branch shape by polymerization, thereby suppressing moisture absorption. The hardened material of the die attach paste swells.

[Epoxy monomer]

The epoxy monomer of the second 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. body.

Further, by including a monofunctional epoxy monomer as a monomer, the crosslinking density of the cured product of the die attach paste can be lowered. Thereby, the degree of warpage before moisture absorption can be controlled. Further, the viscosity of the die attach paste can be adjusted to improve the operability.

Specific examples of the monofunctional epoxy monomer include 4-tributylphenyl epoxypropyl ether, m-p-tolyl epoxypropyl ether, phenylepoxypropyl ether, and tolyl. Epoxypropyl ether and the like. As the monofunctional epoxy monomer, one type of the above specific examples or a combination of two or more types can be used.

Specific examples of the polyfunctional epoxy monomer include bisphenol compounds such as bisphenol A, bisphenol F, and bisphenol; hydrogenated bisphenol A, hydrogenated bisphenol F, hydrogenated bisphenol, and cyclohexanediol. a diol having an alicyclic structure such as cyclohexanedimethanol or cyclohexane diethanol; butanediol, hexanediol, octanediol, decanediol, decanediol, 1,4-bis[(oxygen) a bifunctional one obtained by epoxidizing an aliphatic diol such as decan-2-ylmethoxy)methyl]cyclohexane; a trifunctional epoxy monomer having a trihydroxyphenylmethane skeleton; 4-(2) ,3-epoxy-1-yloxy)-N,N-bis(2,3-epoxy-1-yl)-2-methylaniline, N,N-bis(ethylene oxide based a 3-functional epoxy monomer having an aminophenol skeleton such as 4-(oxiranylmethoxy)aniline; a phenol novolak resin, a cresol novolak resin, and an aralkyl resin A polyfunctional epoxidized product such as a biphenyl aralkyl resin or a naphthol aralkyl resin. As the polyfunctional epoxy monomer, one type of the above specific examples or a combination of two or more types can be used.

[m-butyleneimine monomer]

The maleimide monoamine system of the second embodiment has a maleimide ring in its structure.

The maleimide monomer of the second embodiment may be a monofunctional maleimide monomer having a maleimide ring in its structure, or may be attached to the structure. A polyfunctional maleimide monomer having two or more maleimide rings.

Specific examples of the maleimide monomer include polytetramethylene ether glycol-bis(2-maleimide acetate).

(main agent)

The die attach paste of the second embodiment is hardened and shrunk by curing of the main component. The die attach paste contains a main component, whereby the monomer has an appropriate branch shape by polymerization, and it is possible to suppress swelling of the cured product of the die attach paste due to moisture absorption.

Further, the die attach paste of the second embodiment is hardened and shrunk by curing of the main component. Thereby, the die attach paste can largely agglomerate the silver particles and exhibit the thermal conductivity of the paste. Further, the hardening shrinkage caused by the hardening of the main agent is smaller than the hardening shrinkage caused by the hardening of the monomer.

Specific examples of such a main component include acrylic resins such as acrylic oligomers and acrylic polymers; epoxy resins such as epoxy oligomers and epoxy polymers; allyl oligomers and allyl polymerization. An allylic resin or the like. As the main component, one type of the above specific examples or a combination of two or more types can be used.

The acrylic resin, like the acrylic monomer, can be polymerized by a radical polymerization initiator described later and hardened and shrunk. Further, the polymerization of the acrylic resin occurs by entraining the acrylic monomer.

The epoxy resin is the same as the epoxy monomer, and can react with a curing agent described later and harden and shrink. Further, the epoxy resin is entangled in the hardening reaction of the epoxy resin.

The acryl resin is the same as the acrylic resin or the acrylic monomer, and can be polymerized by a radical polymerization initiator described later, and is hardened and shrunk. Further, the polymerization of the acryl resin occurs by entraining the acrylic monomer.

Further, in the second embodiment, a molecular weight of less than 10,000 in the polymer is referred to as an oligomer, and a molecular weight of 10,000 or more is referred to as a polymer. Further, the resin means that an oligomer and a polymer are contained.

〔Acrylic〕

As the acrylic resin, a liquid having two or more acrylic groups in one molecule can be used.

As the acrylic resin, specifically, a polymerization or copolymerization of the above acrylic monomer can be used. Here, the method of polymerization or copolymerization is not limited, and a known method using a usual polymerization initiator and a chain transfer agent such as solution polymerization can be used. In addition, as the acrylic resin, one type may be used alone or two or more types having different structures may be used. As the acrylic resin, specifically, an acrylic polymer, acrylated polybutadiene or the like can be used.

The acrylic resin may be, for example, an epoxy group, an amine group, a carboxyl group or a hydroxyl group in the structure. When the acrylic resin has an epoxy group in its structure, it can react with a hardener described later and harden and shrink. Further, when the acrylic resin has an amine group, a carboxyl group or a hydroxyl group in its structure and contains an epoxy resin as a main component, the acrylic resin and the epoxy resin can react and harden and shrink. Further, as the acrylic resin, for example, a carbon-carbon double bond C=C may be provided in the structure. When the acrylic resin has a carbon-carbon double bond in its structure, the acrylic resin can be entangled in a polymerization reaction caused by a radical polymerization initiator, and hardened and shrunk.

Specific examples of the commercially available acrylic resin include ARUFON UG-4035, ARUFON UG-4010, ARUFON UG-4070, ARUFON UH-2000, ARUFON UH-2041, and ARUFON UH-made by TOAGOSEI CO., LTD. 2170, ARUFON UP-1000, etc.

The upper limit of the weight average molecular weight Mw of the acrylic resin is preferably, for example, 13,000 or less, more preferably 12,000 or less. Thereby, the frequency of molecular chain entanglement can be increased, and the stress relaxation of the acrylic resin by moisture absorption can be reduced. Further, it is also preferable from the viewpoint of improving the workability of the die attach paste.

Moreover, the lower limit of the weight average molecular weight Mw of the acrylic resin may be, for example, 2,000 or more, or may be 2,500 or more.

[epoxy resin]

As the epoxy resin, a liquid having two or more epoxy groups in one molecule can be used.

Specific examples of the epoxy resin include a trisphenol methane type epoxy resin, a hydrogenated bisphenol A type liquid epoxy resin, a bisphenol-F-diepoxypropyl ether, and an o-cresol novolak type epoxy resin. Wait. As the epoxy resin, one type of the above specific examples or a combination of two or more types can be used. As the epoxy resin, bisphenol-F-diglycidyl ether in the above specific examples is preferred. Thereby, the handleability of the die attach paste can be improved, and the die attach paste can be preferably hardened and shrunk.

[Allyl resin]

As the acryl resin, a liquid having two or more allyl groups in one molecule can be used.

Specific examples of the allylic resin include an allyl ester resin obtained by reacting a dicarboxylic acid, an allyl alcohol, and a compound having an allyl group.

Here, specific examples of the dicarboxylic acid include oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, sebacic acid, sebacic acid, and Malay. Acid, fumaric acid, phthalic acid, tetrahydrophthalic acid, hexahydrophthalic acid, and the like. As the dicarboxylic acid, one type of the above specific examples or two or more types can be used in combination.

Further, examples of the compound having an allyl group include a polyether having an allyl group, a polyester, a polycarbonate, a polyacrylate, a polymethacrylate, a polybutadiene, and a butadiene. Acrylonitrile copolymer and the like. As the compound having an allyl group, one type of the above specific examples or two or more types may be used in combination. As the acryl resin, specifically, a polymer of 1,2-cyclohexanedicarboxylic acid bis(2-propenyl) and propane-1,2-diol can be used.

When the main component contains an acrylic resin or an acryl resin, the lower limit of the content of the acrylic resin and the acryl resin in the die attach paste is preferably 85 parts by mass or more based on 100 parts by mass of the acrylic monomer. 90 parts by mass or more is more preferable, 95 parts by mass or more is further more preferable, and 100 parts by mass or more is further more preferable, and 110 parts by mass or more is particularly preferable. Thereby, the monomer is provided with an appropriate branched shape by polymerization with the acrylic resin and the acryl resin, and it is possible to suppress swelling of the cured product of the die adhesion paste due to moisture absorption.

In addition, when the main component contains an acrylic resin or an acryl resin, the upper limit of the content of the acrylic resin and the acryl resin in the die attach paste is preferably 145 parts by mass or less based on 100 parts by mass of the acrylic monomer. More preferably, it is more preferably 140 parts by mass or less, further preferably 135 parts by mass or less, and further preferably 130 parts by mass or less. Thereby, it is possible to suppress the polymerization of the monomer with respect to the polymerization site of the acrylic resin and the acryl resin. Therefore, the molecules of the cured product of the die attach paste have a desired branch shape, and it is possible to suppress swelling of the cured product of the die adhesion paste due to moisture absorption.

(radical polymerization initiator)

As the radical polymerization initiator, specifically, an azo compound, a peroxide, or the like can be used. As the radical polymerization initiator, one type of the above specific examples or a combination of two or more types can be used. As the radical polymerization initiator, for example, a peroxide in the above specific examples is preferably used.

Specific examples of the above-mentioned peroxide include bis(1-phenyl-1-methylethyl) peroxide, dilauroside peroxide, and 1,1-bis(1,1-dimethyl Ethyl peroxy)cyclohexane, methyl ethyl ketone peroxide, cyclohexane peroxide, acetamidine acetone peroxide, 1,1-di(tri-hexylperoxy)cyclohexane, 1, 1-di(tertiary butyl peroxy)-2-methylcyclohexane, 1,1-di(tri-butylperoxy)cyclohexane, 2,2-di(tri-butyl peroxide) Butane, n-butyl-4,4-di(tertiary butyl peroxy) valerate, 2,2-bis(4,4-di(tri-butylperoxy)cyclohexane)propane, Methane hydroperoxide, diisopropylbenzene hydroperoxide, 1,1,3,3-tetramethylbutyl hydroperoxide, cumene hydroperoxide, tertiary butyl hydroperoxide , bis(2-tert-butylperoxyisopropyl)benzene, diisopropylbenzene peroxide, 2,5-dimethyl-2,5-di(tri-butylperoxy)hexane, three Butyl cumene peroxide, di-tertiary butyl peroxide, 2,5-dimethyl 2,5-di(tri-butylperoxy)hexyne, diisobutyl peroxide, Bis(3,5,5-trimethylhexyl) peroxidation , dilauryl peroxide, bis(3-methylbenzhydryl) peroxide, benzamidine (3-methylbenzhydryl) peroxide, benzoyl peroxide, Bis(4-methylbenzhydryl)peroxide, di-n-propylperoxydicarbonate, diisopropylperoxydicarbonate, di(2-ethylhexyl)peroxydicarbonate, Secondary butyl peroxydicarbonate, cumene peroxy neodecanoate, 1,1,3,3-tetramethylbutyl peroxy neodecanoate, tertiary hexyl neodecanoate, tertiary Butyl peroxy neoheptanoate, tertiary hexyl peroxypivalate, 1,1,3,3-tetramethylbutylperoxy-2-hexyl acetate, 2,5-dimethyl-2 , 5-bis(2-diethylhexyl peroxy)hexane, tertiary butyl peroxy-2-hexyl acetate, tertiary hexylperoxy isopropyl monocarbonate, tertiary butyl peroxidation Maleic acid, tertiary butyl peroxy 3,5,5-trimethylhexanoate, tertiary butyl peroxy isopropyl monocarbonate, tertiary butyl peroxy-2-ethylhexyl monocarbonate Ester, tertiary hexylperoxybenzoate, 2,5-dimethyl-2,5-bis(benzhydrylperoxy)hexane, tert-butyl Oxidized acetone, tertiary peroxy-3-methylbenzoate, tertiary butyl peroxybenzoate, tertiary butyl peroxyallyl monocarbonate, 3,3', 4,4' - Tetrakis (tertiary butyl peroxycarbonyl) benzophenone and the like. As the peroxide, one type of the above specific examples or a combination of two or more types can be used.

As the peroxide, 1,1-bis(1,1-dimethylethylperoxy)cyclohexane in the above specific examples is preferably used. Compared with the peroxide used in the conventional die attach paste, these peroxides do not have a strong hydrogen absorption ability during radical polymerization. Thereby, by using the peroxide of the second embodiment, the irregularity of polymerization of the monomer can be reduced. Thereby, the monomer has a preferable crosslinked structure, so that the cured product of the die attach paste can be suppressed from swelling at the time of moisture absorption.

(other ingredients)

In addition to the above-described raw material components, the die attach paste of the second embodiment may further contain, for example, a curing agent, a curing accelerator, a low stress agent, a decane coupling agent, or the like.

The representative components will be described below.

(hardener)

When the die attach paste of the second embodiment contains an epoxy monomer as a monomer or an epoxy resin as a main component, it is preferable to contain a curing agent, for example. Thereby, the monomer and the main agent can be hardened and shrunk, and the silver particles can be aggregated.

As the curing agent, specifically, a phenol curing agent or an imidazole curing agent can be contained. The details will be described below.

[phenol hardener]

Specific examples of the phenol resin-based curing agent include a novolac type phenol resin such as a phenol novolak resin, a cresol novolak resin, a bisphenol novolak resin, and a phenol biphenol novolak resin; polyvinylphenol; triphenylmethane; a polyfunctional phenol resin such as a phenol resin; a modified phenol resin such as a terpene-modified phenol resin or a dicyclopentadiene-modified phenol resin; a phenol aralkyl resin having a phenyl group skeleton and/or a biphenyl skeleton; a phenol aralkyl type phenol resin such as a naphthol aralkyl resin having a phenyl group and/or a biphenyl skeleton; a bisphenol compound such as bisphenol A or bisphenol F (hydroxydiphenylmethane). The phenol resin-based curing agent may be one or more selected from the above specific examples.

[Imidazole hardener]

Specific examples of the imidazole hardener include 2-phenyl-4-methyl-5-hydroxymethylimidazole, 2-methylimidazole, 2-phenylimidazole, and 2,4-diamino-6. -[2-methylimidazolyl-(1)]-ethyl-s-three , 2-undecylimidazole, 2-heptadecylimidazole, 2,4-diamino-6-[2-methylimidazolyl-(1)]-ethyl-s-three Isophthalic acid adduct, 2-phenylimidazolium isocyanurate adduct, 2-methylimidazolium isocyanurate adduct, 1,2,4-benzenetricarboxylic acid 1-cyano Ethyl-2-phenylimidazolium, 1,2,4-benzenetricarboxylic acid 1-cyanoethyl-2-undecylimidazolium, and the like. As the imidazole-based curing agent, one type of the above specific examples or a combination of two or more types can be used.

(hardening accelerator)

The die attach paste of the second embodiment may contain, for example, a hardening accelerator which promotes the reaction of an epoxy monomer or an epoxy resin with a curing agent.

Specific examples of the curing accelerator include an organic phosphine, a tetra-substituted fluorene compound, a phosphoric acid betaine compound, an adduct of a phosphine compound and an anthracene compound, and an phosphorus atom-containing compound such as an adduct of a hydrazine compound and a decane compound. a decyl group or an amine group such as dicyandiamide, 1,8-diazabicyclo[5.4.0]undecene-7, benzyldimethylamino group; the above thiol group or the above-mentioned tertiary amine group A nitrogen atom-containing compound such as a 4-grade ammonium salt or the like. As the curing accelerator, one type of the above specific examples or a combination of two or more types can be used.

(low stress agent)

The die attach paste of the second embodiment may contain, for example, a low stress agent.

Specific examples of the low stress agent include polyfluorene oxide compounds such as polyasoxylated oils and polyfluorene oxide rubbers; polybutadiene compounds such as polybutadiene maleic anhydride adducts; and acrylonitrile butadiene copolymerization. Compounds, etc. As the low stress agent, one type or two or more types of the above specific examples can be blended.

(decane coupling agent)

The die attach paste of the second embodiment may contain a decane coupling agent, for example, in order to improve the adhesion between the die attach paste and the substrate.

As the decane coupling agent, specifically, vinyl decane such as vinyl trimethoxy decane or vinyl triethoxy decane; 3-glycidoxypropyltrimethoxy decane, 2-(3, 4) can be used. -Epoxycyclohexyl)ethyltrimethoxydecane, 3-glycidoxypropylmethyldimethoxydecane, 3-glycidoxypropyltrimethoxydecane, 3-glycidoxypropane Epoxy decane such as propylmethyldiethoxy decane, 3-glycidoxypropyltriethoxydecane; styrene decane such as p-styryltrimethoxydecane; 3-methylpropene oxime Propylmethyldimethoxydecane, 3-methylpropenyloxypropyltrimethoxydecane, 3-methylpropenyloxypropylmethyldiethoxydecane, 3-methylpropene oxime a decyl methacrylate such as oxypropyltriethoxydecane; a decyl acrylate such as 3-(trimethoxydecyl)propyl methacrylate or 3-propenyloxypropyltrimethoxydecane; (Aminoethyl)-3-aminopropylmethyldimethoxydecane, N-2-(aminoethyl)-3-aminopropyltrimethoxydecane, 3-aminopropyltrimethyl Oxydecane, 3-aminopropyltriethoxy Alkyl decane such as alkane, 3-triethoxycarbamido-N-(1,3-dimethyl-butylene) propylamine, N-phenyl-3-aminopropyltrimethoxydecane; Polyisocyanate decane; alkyl decane; ureido decane such as 3-ureidotrialkoxy decane; 3-mercaptopropylmethyldimethoxydecane, decyl decane such as 3-mercaptopropyltrimethoxydecane; - an isocyanate decane such as isocyanate propyl triethoxy decane; a polythioether or a thioether decane such as bis[3-(triethoxymethanealkyl)propyl]. As the decane coupling agent, one type of the above specific examples or a combination of two or more types can be used.

(Method of manufacturing die attach paste)

A method of producing a die attach paste according to the second embodiment will be described.

The method for producing a die attach paste includes a mixing step of mixing the above raw material components to prepare a mixture, and a defoaming step of removing air contained in the mixture.

(mixing step)

In the mixing step, the above raw material components are mixed to prepare a mixture.

There is no limitation as a method of mixing, for example, a 3-roller, a mixer, or the like is used. Thereby, the raw material components are mixed to obtain a mixture.

(debubbing step)

The air contained in the mixture is removed in the defoaming step.

The method for removing the air contained in the mixture is not limited, and can be carried out, for example, by allowing the mixture to stand under vacuum. Thereby, a die attach paste is obtained.

(grain adhesive paste)

In the die attach paste of the second embodiment, the die attach paste is applied to a silver-plated copper frame having a length of 15.5 mm and a width of 6.5 mm so as to have a coating thickness of 35 ± 5 μm, and then the length is 15.0 mm. A tantalum wafer having a width of 6.0 mm and a thickness of 0.2 mm was placed on the die attach paste to obtain a laminate, and the laminate was heated from 25 ° C to 175 ° C over 30 minutes, and further heat-treated at 175 ° C for 5 hours. In the hardened body, the amount of warpage when the cured body was heat-treated at 275 ° C for 1 minute was W1, and the cured body was allowed to absorb moisture at a temperature of 85 ° C and a humidity of 85% for 168 hours, and then at 275 ° C. When the amount of warpage at the time of the heat treatment for 1 minute is W2, the upper limit of |W2-W1| is 20 μm or less, preferably 18 μm or less, more preferably 16 μm or less, and still more preferably 14 μm or less. Thereby, the mounting reliability of the semiconductor device using the semiconductor package of the die attach paste of the second embodiment can be improved.

Further, the lower limit of |W2-W1| may be, for example, 0 μm or more, or may be 0.1 μm or more. The smaller the difference between W1 and W2, the more the warpage of the semiconductor device can be set within a desired numerical range at the time of moisture absorption, and the mounting reliability of the semiconductor device can be improved.

The present inventors conducted research on a method in which |W2-W1| of the die attach paste is set within the above numerical range. As a result, it has been found that it is important to appropriately control the raw material components of the monomer, the main component, the radical polymerization initiator, and the like contained in the die attach paste, and the blending amount thereof. Although the detailed mechanism is not clear, it is presumed that a component containing a monomer, a main component, and the like has an appropriate branch shape by polymerization and hardening reaction. It is considered that it is possible to suppress swelling of the cured product of the die-adhesive paste due to moisture absorption, and to set |W2-W1| within the above numerical range.

In the die attach paste of the second embodiment, the die attach paste is applied to a silver-plated copper frame so as to have a coating thickness of 25 ± 5 μm, and then the length is 2.0 mm × width 2.0 mm × thickness 350 ± A 5 μm tantalum wafer was placed on the die attach paste, heated from 25 ° C to 175 ° C in 30 minutes, and further heat treated at 175 ° C for 5 hours to obtain a hardened body at a temperature of 85 ° C and a humidity of 85%. The test piece was obtained by absorbing moisture for 72 hours, and the lower limit of the die shear strength of the silver-plated copper frame and the tantalum wafer at 260 ° C was 17.0 N/(2 mm × 2 mm) or more. 18.0 N / (2 mm × 2 mm) or more is preferable, 19.0 N / (2 mm × 2 mm) or more is further more preferable, and 26.0 N / (2 mm × 2 mm) or more is further preferable. Thereby, even if the adherend absorbs moisture by exhibiting a certain internal stress, it is possible to suppress a change in the amount of warpage due to moisture absorption. Moreover, it is also convenient from the viewpoint of improving the operational reliability of the semiconductor device when the semiconductor device is fabricated.

Further, the upper limit of the die-cutting strength may be, for example, 50.0 N/(2 mm × 2 mm) or less, or may be 40.0 N/(2 mm × 2 mm) or less.

(use)

The use of the die attach paste of the second embodiment will be described.

The die attach paste of the second embodiment is preferably used, for example, in a semiconductor device such as a semiconductor package.

Here, specific examples of the type of the semiconductor package include a MAP (Mold Array Package), a QFP (Quad Flat Package), and an SOP (Small Outline Package). ), CSP (Chip Size Package), QFN (Quad Flat Non-leaded Package), SON (Small Outline Non-leaded Package), BGA (BGA) Ball Grid Array: LF-BGA (Lead Flame BGA: Lead Frame BGA), FCBGA (Flip Chip BGA: Flip Chip BGA), MAPBGA (Molded Array Process BGA: Molded Array Package BGA), eWLB ( Embedded Wafer-Level BGA: Embedded Wafer Level BGA), Fan-In eWLB, Fan-Out eWLB, etc.

Hereinafter, an example of a semiconductor device using the die attach paste of the second embodiment will be described.

Fig. 1 is a cross-sectional view showing an example of a semiconductor device according to a second embodiment.

The semiconductor device 100 of the second embodiment includes a substrate 30 and a semiconductor element 20 which is mounted on the substrate 30 via an adhesive layer 10 which is a cured product of a die attach paste. That is, the adhesive layer 10 is formed by hardening the die adhesion paste.

The semiconductor element 20 and the substrate 30 are electrically connected, for example, via a bonding wire 40 or the like. Further, the semiconductor element 20 is sealed by, for example, the sealing resin 50.

Here, the lower limit of the thickness of the adhesive layer 10 is preferably 5 μm or more, and more preferably 10 μm or more. Thereby, the die attach paste can exhibit a better adhesive force. Thereby, the operational reliability of the semiconductor device can be improved.

Further, the upper limit of the thickness of the adhesive layer 10 is preferably 50 μm or less, and more preferably 30 μm or less. Thereby, the absolute value of the warpage of the semiconductor device can be reduced. Thereby, it is possible to reduce the change in warpage caused by moisture absorption.

In Fig. 1, the substrate 30 is, for example, a lead frame. In this case, the semiconductor element 20 is mounted on the wafer mounting pad 32 or the substrate 30 via the adhesive layer 10. Moreover, the semiconductor element 20 is electrically connected to the outer lead 34 (substrate 30) via the bonding wire 40, for example. The base material 30 as the lead frame is made of, for example, a 42 alloy or a copper frame.

The substrate 30 may be an organic substrate or a ceramic substrate. The organic substrate is preferably made of, for example, an epoxy resin, a cyanate resin, a maleimide resin or the like.

Further, the surface of the substrate 30 may be covered with, for example, a metal such as silver or gold. Thereby, the adhesiveness of the adhesive layer 10 and the base material 30 can be improved.

FIG. 2 is a cross-sectional view showing an example of the semiconductor device 100 according to the second embodiment.

In the semiconductor device 100 of the present modification, the substrate 30 is, for example, an interposer. For example, a plurality of solder balls 52 are formed on the other surface of the substrate 30 as the interposer opposite to the side on which one surface of the semiconductor element 20 is mounted. In this case, the semiconductor device 100 is connected to another wiring board via the solder balls 52.

(Method of Manufacturing Semiconductor Device)

An example of a method of manufacturing the semiconductor device of the second embodiment will be described.

First, a die attach paste is applied onto the substrate 30, and then the semiconductor element 20 is placed thereon. That is, the substrate 30, the die adhesion paste, and the semiconductor element 20 are laminated in this order. The method of applying the die attach paste is not limited, and specifically, a dispensing method, a printing method, an inkjet method, or the like can be used.

Next, the die attach paste is heat-treated to make the die attach paste a cured product. By the heat treatment described above, the silver particles in the die attach paste are agglomerated, and the thermal conductive layer in which the interface between the plurality of silver particles disappears is formed in the adhesive layer 10. Further, the conditions of the heat treatment can be, for example, from room temperature of 25 ° C to a temperature of 100 ° C or more and 300 ° C or less, and the temperature is raised for 10 minutes to 2 hours, and further heat treatment is performed for 10 minutes to 2 hours at a temperature after the temperature rise. . Thereby, the base material 30 and the semiconductor element 20 are bonded via the adhesive layer 10. Next, the semiconductor element 20 is electrically connected to the substrate 30 using the bonding wires 40. Next, the semiconductor element 20 is sealed with a sealing resin 50. Thereby, a semiconductor device can be manufactured.

The present invention has been described above based on the embodiments, but the present invention is not limited to the embodiments, and the configuration thereof can be modified without departing from the spirit and scope of the invention.

Hereinafter, an example of a reference form is attached.

A die attach paste comprising: silver particles; a monomer; a main agent; and a radical polymerization initiator, wherein the die attach paste is applied to a length of 15.5 in a coating thickness of 35 ± 5 μm. On a silver-plated copper frame having a mm×width of 6.5 mm, a tantalum wafer having a length of 15.0 mm, a width of 6.0 mm, and a thickness of 0.2 mm was placed on the die attach paste to obtain a laminate, and the laminate was obtained in 30 minutes. The temperature was raised from 25 ° C to 175 ° C, and further heat treatment was performed at 175 ° C for 5 hours to obtain a cured body. The amount of warpage when the cured body was heat-treated at 275 ° C for 1 minute was W1, and the temperature was 85 ° C. The humidity was 85%, and when the hardened body was hydrated for 168 hours, the amount of warpage when the heat treatment was performed at 275 ° C for 1 minute was W2, and |W2-W1| was 20 μm or less.

Wherein, the amount of warpage indicates a diagonal line connecting any two vertices located at opposite corners in the in-plane direction of the tantalum wafer, and a distance from the position of the tantalum wafer in a direction perpendicular to the diagonal line. Maximum value.

2. The die attach paste of 1, wherein the die attach paste is applied to a silver-plated copper frame in a coating thickness of 25 ± 5 μm, followed by a length of 2.0 mm × a width of 2.0 mm × thickness A 350±5 μm germanium wafer was placed on the die attach paste, heated from 25 ° C to 175 ° C in 30 minutes, and further heat treated at 175 ° C for 5 hours to obtain a hardened body at a temperature of 85 ° C and humidity. After 8 hours of moisture absorption for 8 hours, a test piece was obtained. With respect to the test piece, the die-cut strength of the silver-plated copper frame and the tantalum wafer at 260 ° C was 17.0 N / (2 mm × 2 mm) or more.

3. The die attach paste of 1. or 2. wherein the silver particle shape is a sheet shape or a spherical shape.

4. The die attach paste according to any one of the above aspects, wherein the silver particles have a tap density of 2.5 g/cm ³ or more and 10.0 g/cm ³ or less.

5. The die attach paste according to any one of the above aspects, wherein the silver particles have an average particle diameter of 0.1 μm or more and 20 μm or less.

6. The die attach paste according to any one of the above aspects, wherein the content of the silver particles in the die attach paste is 50 parts by mass or more and 90 parts by mass based on 100 parts by mass of the die attach paste. the following.

7. The die attach paste of any one of 1. to 6, wherein the single system is selected from the group consisting of an acrylic monomer, an epoxy monomer, and a maleimide monomer. Kind or more than two.

8. The die attach paste of any one of 1. to 7, wherein the aforementioned monomer comprises the aforementioned acrylic monomer.

9. The die attach paste according to 8. The content of the acrylic monomer in the die attach paste is 1.0 part by mass or more and 30 parts by mass or less based on 100 parts by mass of the die attach paste.

10. The die attach paste of 8. or 9. wherein the acrylic monomer comprises a monofunctional acrylic monomer and a polyfunctional acrylic monomer, and the content of the aforementioned monofunctional acrylic monomer in the die attach paste is relative to 100 parts by mass of the above polyfunctional acrylic monomer is 150 parts by mass or more and 650 parts by mass or less.

The die attach paste of any one of the group consisting of an acrylic resin, an epoxy resin, and an allyl resin, or one or more types.

12. The die attach paste according to 11, wherein the main component comprises the acrylic resin, and the weight average molecular weight Mw of the acrylic resin is 2,000 or more and 13,000 or less.

13. The die attach paste of item 11. or 12, wherein the monomer comprises an acrylic monomer, and the main component comprises the acrylic resin or the allylate resin, the acrylic resin in the die attach paste, and the foregoing The content of the acryl resin is 85 parts by mass or more and 145 parts by mass or less based on 100 parts by mass of the acrylic monomer.

The die attach paste according to any one of the above aspects, wherein the radical polymerization initiator is a peroxide.

The die attach paste of any one of 1. to 14. wherein the die attach paste further comprises a hardener.

16. The die attach paste of 15, wherein the hardener comprises a phenol hardener or an imidazole hardener.

A semiconductor device comprising: a substrate; and a semiconductor element mounted on the substrate via an adhesive layer, wherein the adhesive layer is a die attach paste according to any one of 1. to 16. Hardened.

[Examples]

Next, an embodiment of the present invention will be described.

(Preparation of die attach paste)

Regarding each of the examples and the comparative examples, a die attach paste was prepared. This preparation was carried out by uniformly mixing the components in accordance with the ratio shown in Table 1. In addition, the details of the components shown in Table 1 are as follows. Further, the blending ratio of each component in Table 1 indicates the blending ratio (% by mass) of each component with respect to all the die attach pastes.

((A) (meth)acrylic copolymer having a reactive group at the terminal)

. (Meth)acrylic acid copolymer 1: an acrylic copolymer having an epoxy group at the terminal (ARUFON UG-4035 manufactured by TOAGOSEI CO., LTD., weight average molecular weight: 11,000, epoxy equivalent: 556)

. (Meth)acrylic copolymer 2: an acrylic copolymer having an epoxy group at the terminal (ARUFON UG-4010 manufactured by TOAGOSEI CO., LTD., weight average molecular weight: 2900, epoxy equivalent: 714)

. (Meth)acrylic copolymer 3: an acrylic copolymer having an epoxy group at the terminal (ARUFON UG-4070 manufactured by TOAGOSEI CO., LTD., weight average molecular weight: 9700, epoxy equivalent: 714)

. (Meth)acrylic acid copolymer 4: an acrylic copolymer having a hydroxyl group at the terminal (ARUFON UH-2000 manufactured by TOAGOSEI CO., LTD., weight average molecular weight: 11,000, hydroxyl value: 20)

. (Meth)acrylic copolymer 5: an acrylic copolymer having a methacrylic group at the terminal (weight average molecular weight: 12,000, 4 methacrylic groups per molecule)

. (Meth)acrylic copolymer 6: an acrylic copolymer having a hydroxyl group at the terminal (ARUFON UH-2041 manufactured by TOAGOSEI CO., LTD., weight average molecular weight: 2,500, hydroxyl value: 120)

. (Meth)acrylic copolymer 7: an acrylic copolymer having a hydroxyl group at the terminal (ARUFON UH-2170 manufactured by TOAGOSEI CO., LTD., weight average molecular weight: 14,000, hydroxyl value: 88)

((A) '(meth)acrylic acid copolymer having no reactive group)

. (Meth)acrylic copolymer 8: an acrylic copolymer having no reactive group (ARUFON UP-1000 manufactured by TOAGOSEI CO., LTD., weight average molecular weight: 3000)

((B) (meth)acrylic monomer)

. (meth)acrylic acid monomer 1:1,6-bis(acryloxy)hexane (LIGHT ESTER1.6HX manufactured by Kyoeisha Chemical Co., Ltd.)

. (Meth)acrylic acid monomer 2: 2-phenoxyethyl methacrylate (LIGHT ESTERPO, manufactured by Kyoeisha Chemical Co., Ltd.)

((C) filler)

. Silver powder 1: spherical silver powder 1 (specific surface area: 0.98 m ² /g, tap density: 5.03 g/cm ³ , D ₅₀ : 1.03 μm, D ₉₀ : 1.90 μm, ratio of D ₉₀ to D ₅₀ (D ₉₀ / D ₅₀ ): 1.84)

. Silver powder 2: spherical silver powder 2 (specific surface area: 0.71 m ² /g, tap density: 5.88 g/cm ³ , D ₅₀ : 1.26 μm, D ₉₀ : 2.49 μm, ratio of D ₉₀ to D ₅₀ (D ₉₀ / D ₅₀ ): 1.98)

. Silver powder 3: spherical silver powder 3 (specific surface area: 0.19 m ² /g, tap density: 5.56 g/cm ³ , D ₅₀ : 4.19 μm, D ₉₀ : 7.05 μm, ratio of D ₉₀ to D ₅₀ (D ₉₀ / D ₅₀ ): 1.68)

. Silver powder 4: flake silver powder 1 (specific surface area: 1.07 m ² /g, tap density: 3.89 g/cm ³ , D ₅₀ : 2.25 μm, D ₉₀ : 5.20 μm, ratio of D ₉₀ to D ₅₀ (D ₉₀ / D ₅₀ ): 2.31)

. Silver powder 5: flake silver powder 2 (specific surface area: 0.80 m ² /g, tap density: 3.57 g/cm ³ , D ₅₀ : 3.90 μm, D ₉₀ : 8.70 μm, ratio of D ₉₀ to D ₅₀ (D ₉₀ / D ₅₀ ): 2.23)

. Silver powder 6: flake silver powder 3 (specific surface area: 0.25 m ² /g, tap density: 3.51 g/cm ³ , D ₅₀ : 8.10 μm, D ₉₀ : 17.00 μm, ratio of D ₉₀ to D ₅₀ (D ₉₀ / D ₅₀ ): 2.10)

. Inorganic filler 1: spherical yttrium oxide 1 (D ₅₀ : 1 μm, D ₉₀ : 2 μm, ratio of D ₉₀ to D ₅₀ (D ₉₀ / D ₅₀ ): 2)

. Inorganic filler 2: spherical yttrium oxide 2 (D ₅₀ : 4.2 μm, D ₉₀ : 8.5 μm, ratio of D ₉₀ to D ₅₀ (D ₉₀ / D ₅₀ ): 2.02)

. Inorganic filler 3: spherical alumina 1 (D ₅₀ : 3.3 μm, D ₉₀ : 6.8 μm, ratio of D ₉₀ to D ₅₀ (D ₉₀ / D ₅₀ ): 2.06)

. Inorganic filler 4: spherical alumina 2 (D ₅₀ : 4.5 μm, D ₉₀ : 12 μm, ratio of D ₉₀ to D ₅₀ (D ₉₀ / D ₅₀ ): 2.67)

. Organic filler: polymethylsesquioxane (manufactured by Shin-Etsu Chemical Co., Ltd., KMP-590, D ₅₀ : 1.9 μm, D ₉₀ : 2.4 μm, ratio of D ₉₀ to D ₅₀ (D ₉₀ /D ₅₀ ): 1.26)

((D1) allyl ester resin)

. Allyl ester resin 1: Allyl-containing polyester resin (DA101 manufactured by SHOWA DENKO K.K., weight average molecular weight 1000, two allylic groups per molecule)

((D2) polycarbonate resin)

. Polycarbonate resin 1: two-terminal methacrylated polycarbonate resin (UM-90 (1/3) DM, manufactured by UBE INDUSTRIES, LTD., weight average molecular weight 900, two methacrylic groups per molecule)

((E) decane coupling agent)

. Decane coupling agent 1: 3-(trimethoxydecyl)propyl methacrylate (KBM-503P, manufactured by Shin-Etsu Chemical Co., Ltd.)

. Decane coupling agent 2: 3-glycidoxypropyltrimethoxydecane (KBM-403E, manufactured by Shin-Etsu Chemical Co., Ltd.)

((F) low stress agent)

. Low stress agent 1: polybutadiene maleic anhydride adduct (Ricobond 1731, manufactured by Satomer Co., Ltd., number average molecular weight 5400, anhydride equivalent 583)

(other)

. Hardening accelerator: dicyanamide (EH-3636AS, manufactured by ADEKA Co., Ltd.)

. Polymerization initiator: bis(1-phenyl-1-methylethyl) peroxide (Perkadox BC, manufactured by KAYAKU AKZO CO., LTD.)

The above (meth)acrylic copolymer 5 was prepared by the following procedure.

An acrylic oligomer (ARUFON UH-2000, manufactured by TOAGOSEI CO., LTD.), which is obtained by continuous block polymerization of high temperature and high pressure without using a chain transfer catalyst, has an acrylic oligomer having a hydroxyl group. Polymer, hydroxyl value 20 mgKOH/g, molecular weight 11000) 110 g, (meth)acrylic acid 5 g and toluene 500 g were placed in a separable flask, using a Dean-Stark Trap, under reflux The mixture was stirred for 30 minutes to carry out moisture removal treatment. Then, after cooling to room temperature, 10 g of dicyclohexylcarbodiimide was dissolved in 50 ml of ethyl acetate while stirring, and the mixture was added dropwise thereto for 10 minutes, and then reacted at room temperature for 6 hours. After the completion of the reaction, 50 mL of ion-exchanged water was added thereto while stirring to precipitate excess dicyclohexylcarbodiimide, and then the mixture was stirred for 30 minutes under reflux using a Dean-Stark trap. deal with. Then, after cooling to room temperature, the reaction liquid was filtered to remove the solid matter. Subsequently, the liquid separation was performed three times with ion-exchanged water at 70 ° C, and the liquid separation was performed twice with ion-exchanged water at room temperature. Then, the solvent was removed from the filtrate obtained by filtering the obtained solvent layer again using an evaporator and a vacuum dryer to obtain a product (meth)acrylic copolymer 5 (yield: about 98%). The resulting product was in a liquid state at room temperature. Further, as a result of performing GPC measurement on the obtained product, it was confirmed that the weight average molecular weight (in terms of styrene) was about 12,000, and methacrylic acid remained in the product.

Then, as a result of measuring proton NMR using heavy chloroform, the obtained product was observed to have disappeared, and a methacrylic group remained in the product, and an ester bond was formed in the product.

In addition, the particle size of the (C) filler (silver powder) was determined by particle image measurement using a flow particle image analyzer FPIA (registered trademark)-3000 manufactured by Sysmex Corporation. More specifically, the particle size of the silver powder was determined by measuring the volume-based median diameter using the above apparatus.

(Evaluation)

The die attach paste obtained as described above was evaluated in accordance with the following items. The results are shown in Table 1.

(resistance to reflow)

A tantalum wafer (2 x 2 mm, thickness 0.35 mm) was adhered to the lead frame (silver spot plated copper frame) using the obtained die attach paste. Specifically, after the temperature was raised to 175 ° C over 30 minutes, the temperature was maintained for 60 minutes to cure the die attach paste, whereby the tantalum wafer was adhered to the lead frame via the cured product of the die attach paste. Then, after the lead frame was subjected to wafer soldering, the lead frame was sealed by a semiconductor sealing epoxy resin composition (EME-G700LS, manufactured by Sumitomo Bakelite Company Limited) in a package size of 17.9 × 7.2 × 2.5 mm. A semiconductor device (SOP) was obtained by performing post mold cure at 175 ° C for 4 hours. Further, eight of the above semiconductor devices were fabricated by the above method. Next, the obtained eight semiconductor devices were subjected to a moisture absorption treatment for 120 hours under conditions of 60° C. and a relative humidity of 60%, and then subjected to IR reflow treatment (under 260° C. for 10 seconds). Secondary reflow). Next, the presence or absence of peeling at the interface between the lead frame and the ruthenium wafer was measured for each of the eight semiconductor devices after the IR reflow process using an ultrasonic flaw detector (transmissive type). The results are shown in Table 1 as the number of peelings/the number of evaluations.

(viscosity)

For the obtained die attach paste, the viscosity was measured at 25 ° C and 5.0 rpm using a Brookfield viscometer 1.5 degree cone.

[Table 1]

When the adhesion layer was obtained using the die attach paste of each Example as shown in Table 1, the reflow resistance was good.

On the other hand, Comparative Example 1 and Comparative Example 2 in which the D _{50 of the} silver powder is large or Comparative Example 3 which does not include the (meth)acrylic copolymer having a specific reactive group at the terminal, and as the (meth)acrylic copolymer In Comparative Example 4 in which no reactive group was used, there was a result that the reflow resistance was inferior to that of the examples. Further, in Comparative Examples 5 and 6 in which an inorganic filler having a particle diameter D _{50 which} is larger than 4 μm was used, the results of poor solder reflow resistance were inferior to those in Examples.

Further, in order to confirm that the second problem was solved by the die attach paste of the second embodiment, the die attach pastes of the following Examples 23 to 28 and Comparative Examples 7 to 9 were prepared.

<Material ingredients>

First, the raw material components used in Examples 23 to 28 and Comparative Examples 7 to 9 will be described in detail.

(monomer)

As the monomer, the following were used.

. Monofunctional acrylic monomer 1: 2-phenoxyethyl methacrylate (manufactured by Kyoeisha Chemical Co., Ltd., PO)

. Polyfunctional acrylic monomer 1: ethylene glycol dimethacrylate (manufactured by Kyoeisha Chemical Co., Ltd., EG)

. Polyfunctional acrylic monomer 2: trimethylolpropane trimethacrylate (manufactured by Kyoeisha Chemical Co., Ltd., TMP)

. Polyfunctional acrylic monomer 3: propoxylated bisphenol A diacrylate (manufactured by Kyoeisha Chemical Co., Ltd., A-BBP-3)

. Polyfunctional acrylic monomer 4: hexane-1,6-diol bis(2-methacrylate) (manufactured by Kyoeisha Chemical Co., Ltd., 1,6HX)

. Polyfunctional epoxy monomer 1: 1,4-bis[(oxodecane-2-ylmethoxy)methyl]cyclohexane (manufactured by Nippon Steel Chemical Co., Ltd., ZX-1658GS)

(main agent)

As the main agent, the following were used.

. Acrylic Polymer 1: Acrylic Polymer (manufactured by TOAGOSEI CO., LTD., UG-4035, Mw=11000)

. Acrylic oligomer 1: acrylated polybutadiene (manufactured by Osaka Organic Chemical Industry Co., Ltd., BAC-45, Mw=3000)

. Epoxy oligomer 1: bisphenol-F-diglycidyl ether (manufactured by Nippon Kayaku Co., Ltd., RE-403S)

. Epoxy oligomer 2: modified epoxy resin (made by DIC CORPORATION, EXA-4850-1000)

. Allyl oligomer 1:1,2-cyclohexanedicarboxylic acid bis(2-propenyl) and propane-1,2-diol polymer (KANTO CHEMICAL CO., INC.)

(radical polymerization initiator)

. Peroxide 1: bis(1-phenyl-1-methylethyl) peroxide (manufactured by KAYAKU AKZO CO., LTD., PERCADOX BC)

. Peroxide 2:1,1-bis(1,1-dimethylethylperoxy)cyclohexane (manufactured by NOF CORPORATION. PERHEXA C(S))

. Peroxide 3: Dilaurin peroxide (manufactured by ARKEMA Yoshitomi, Ltd., LUPEROX LP)

(hardener)

. Phenol curing agent 1: Hydroxydiphenylmethane (DIC-BPF, manufactured by DIC CORPORATION)

. Imidazole hardener 1: 2-phenyl-4-methyl-5-hydroxymethylimidazole (manufactured by SHIKOKU CHEMICALS CORPORATION., 2P4MHZ)

(hardening accelerator)

. Hardening accelerator 1: dicyandiamide (made by Asahi Denka Kogyo Kabushiki Kaisha., EH-3636AS)

(low stress agent)

. Low stress agent 1: polybutadiene maleic anhydride adduct (manufactured by Cray Valley HSC Asia Limited, Ricobond 1731)

(decane coupling agent)

. Decane coupling agent 1: polysulfide, bis[3-(triethoxy)propyl] (manufactured by Daiso-sangyo, CABRUS4)

. Decane coupling agent 2: 3-glycidoxypropyltrimethoxydecane (manufactured by Shin-Etsu Chemical Co., Ltd., KBM-403E)

. Decane coupling agent 3: 3-(trimethoxydecyl)propyl methacrylate (manufactured by Shin-Etsu Chemical Co., Ltd., KBM-503P)

(silver particles)

As the silver particles, those shown in Table 2 below were used.

<Production of die adhesion paste>

The die attach pastes of Examples 23 to 28 and Comparative Examples 7 to 9 were produced. As a production method, each raw material component of the blending amount described in the following Table 3 was kneaded by a 3-roll mill at normal temperature.

<evaluation>

The die attach pastes of Examples 23 to 28 and Comparative Examples 7 to 9 and the semiconductor device using the die attach paste were evaluated by the following methods.

(warpage amount)

In the die attach pastes of Examples 23 to 28 and Comparative Examples 7 to 9, the amount of warpage when the die pad paste was applied to a semiconductor device and was not moisture-absorbed, and the grain adhesion paste was applied The amount of warpage when heating was performed after the semiconductor device was absorbed, and the amount of warpage was evaluated. The details will be described below.

First, a silver-plated copper lead frame having a length of 15.5 mm and a width of 6.5 mm was prepared. Next, the die attach paste of each of the examples and the comparative examples was applied onto the lead frame by hand. Here, the die attach paste was applied so that the coating thickness became 35±5 μm. Next, a tantalum wafer having a length of 15.0 mm, a width of 6.0 mm, and a thickness of 0.2 mm was placed on the die attach paste coated on the lead frame to obtain a laminate. That is, the laminated system sequentially laminates a lead frame, a die attach paste, and a germanium wafer.

The laminate was heated from 25 ° C to 175 ° C over 30 minutes, and further heat-treated at 175 ° C for 5 hours to obtain a cured body. Further, at the time of heat treatment at 175 ° C for 1 hour, the die attach paste of each of the examples and the comparative examples was hardened. Further, the reason why the heat treatment was carried out at 175 ° C for 4 hours was as follows, that is, it was assumed that the die attach paste was used in the production of a semiconductor device, and the die attach pastes of Examples 23 to 28 and Comparative Examples 7 to 9 were given. The sealing material is molded and hardened for the same thermal history.

The amount of warpage of the hardened body when the cured body was heat-treated at 275 ° C for 1 minute was evaluated as W1. Moreover, after the hardened body was wetted at a temperature of 85 ° C and a humidity of 85% for 168 hours, the amount of warpage of the cured body at the time of heat treatment at 275 ° C for 1 minute was evaluated as W2. Further, |W2-W1| is calculated based on W1 and W2. Wherein, the amount of warpage indicates a diagonal line connecting any two vertices located at opposite corners in the in-plane direction of the tantalum wafer, and a distance from the position of the tantalum wafer in a direction perpendicular to the diagonal line. Maximum value. That is, even if either the hardened body is convex upward or the downwardly convex smile is warped, the amount of warpage indicates a positive value. Here, in each of the examples and the comparative examples, the surface of the lead frame in which the laminate was present was used as the bottom surface, and when the warpage amounts W1 and W2 were measured as the top surface of the wafer surface, the warping was warped.

The evaluation results are shown in Table 3 below. In addition, the unit is μm.

Further, in Examples 23 to 28 and Comparative Examples 7 to 9, the lead frame, the die attach paste, and the tantalum wafer were integrated to cause warpage of the hardened body, and the lead frame and the tantalum wafer were heat-treated at 275 ° C for 1 minute. No peeling occurred before or after.

(installation reliability)

The mounting reliability of the semiconductor device using the die attach pastes of Examples 23 to 28 and Comparative Examples 7 to 9 was evaluated. As an evaluation of the mounting reliability, MSL (Moisture Sensitivity Level) performance was measured. The MSL performance was performed in accordance with JEDEC STANDARD 22-A113D and set to MSL Lv2a. The detailed method is shown below.

First, a lead frame (a silver-plated copper frame) and a tantalum wafer (length 2 mm × width 2 mm, thickness 0.35 mm) were prepared. Next, the die attaching pastes of Examples 23 to 28 and Comparative Examples 7 to 9 were applied to the tantalum wafer so as to have a coating thickness of 25 ± 5 μm, and a lead frame was disposed. That is, a laminate in which a tantalum wafer, a die attach paste, and a lead frame are sequentially laminated is produced. Further, the surface in contact with the die attach paste of the lead frame is formed by silver plating.

Subsequently, the temperature was raised from a temperature of 25 ° C to a temperature of 175 ° C in 30 minutes, and then heat treatment was performed at a temperature of 175 ° C for 60 minutes to cure the layered crystal grain paste, thereby producing a cured product. Next, the cured product was sealed with an epoxy resin composition for semiconductor sealing (EME-G700LS, manufactured by Sumitomo Bakelite Company Limited) so as to have a package size of 17.9 mm, a width of 7.2, and a thickness of 2.5 mm, and the temperature was 175 ° C. The semiconductor device was obtained by heat-treating for 4 hours and curing the epoxy resin composition for semiconductor encapsulation.

This semiconductor device was subjected to an IR reflow treatment under conditions of 60° C. and a relative humidity of 60% for 120 hours, and then subjected to IR reflow treatment (three reflows at 260° C. for 10 seconds). Next, the presence or absence of peeling was evaluated using a transmission type ultrasonic flaw detector for the semiconductor device after the IR reflow process. 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 3 below.

○: interface between the lead frame and the cured product of the die attach paste, the cured product of the die attach paste, the interface of the germanium wafer, the cured product of the germanium wafer and the epoxy resin composition for semiconductor sealing, and the lead frame and the semiconductor seal With the interface of the cured product of the epoxy resin composition, the area of the interface to be peeled is less than 20% with respect to the area of 2 mm × 2 mm.

X: interface between the lead frame and the cured product of the die attach paste, the cured product of the die attach paste and the interface of the germanium wafer, the cured product of the germanium wafer and the epoxy resin composition for semiconductor sealing, and the lead frame and the semiconductor seal At the interface of the cured product of the epoxy resin composition, the area of the interface to be peeled off was 20% or more with respect to the area of 2 mm × 2 mm.

Further, since the peeling of the interface between the lead frame and the cured product of the epoxy resin composition for semiconductor encapsulation is caused by warpage caused by the cured product of the die-adhesive paste, it has been evaluated.

(fillet shape stability)

The rounded shape stability of the semiconductor device using the die attach pastes of Examples 23 to 28 and Comparative Examples 7 to 9 was evaluated. The details will be described below.

First, a lead frame (a silver-plated copper frame) and a tantalum wafer (length 7 mm × width 7 mm, thickness 0.20 mm) were prepared. Next, using a wafer soldering machine (manufactured by SHINKAWA LTD., SPA-400) for the tantalum wafer, the die attach pastes of Examples 23 to 28 and Comparative Examples 7 to 9 were applied to 15 ± 3 mm ³ , and then applied to the tantalum wafer. The germanium wafer is mounted on the lead frame with a load of 8N. Thereby, a laminate in which a tantalum wafer, a die attach paste, and a lead frame are sequentially laminated in the thickness direction is produced. Further, the surface in contact with the die attach paste of the lead frame is formed by silver plating.

The fillet height was measured with an optical microscope on the above laminated body. When the thickness of the rounded corner is observed from the direction perpendicular to the thickness direction, the interface between the tantalum wafer and the die attach paste is used as a starting point, and there is grain adhesion in the thickness direction of the laminated body. The maximum length of the paste. Further, the ruthenium wafer was peeled off from the laminate to confirm the diffusion of the die adhesion paste. Thereby, the fillet shape stability was evaluated according to the following criteria. The evaluation results are shown in Table 3 below.

◎: The fillet height is 150 μm or less. Further, when the tantalum wafer was peeled off from the laminate, the die adhesion paste was spread over the entire surface of the tantalum wafer having a length of 7 mm × a width of 7 mm, and a mark of adhesion was observed.

○: The fillet height is larger than 150 μm and 200 μm or less. Further, when the tantalum wafer was peeled off from the laminate, the die attach paste was spread over the entire surface of the tantalum wafer having a length of 7 mm × a width of 7 mm, and a mark of adhesion was observed.

×: The fillet height is more than 200 μm. Alternatively, when the rounded corner height is 200 μm or less, when the tantalum wafer is peeled off from the laminated body, the crystal grain adhesive paste is not diffused over the entire surface of the tantalum wafer having a length of 7 mm × a width of 7 mm, and no trace of adhesion is observed.

(die cutting strength)

The die-cut strength was evaluated for the semiconductor device using the die attach pastes of Examples 23 to 28 and Comparative Examples 7 to 9. The details will be described below.

First, a lead frame (a silver-plated copper frame) and a tantalum wafer (length 2 mm × width 2 mm, thickness 0.35 mm) were prepared. Next, the die attach pastes of Examples 23 to 28 and Comparative Examples 7 to 9 were applied to the tantalum wafer so as to have a coating thickness of 25 ± 5 μm, and a lead frame was placed. That is, a laminate in which a tantalum wafer, a die attach paste, and a lead frame are sequentially laminated is produced. In addition, the surface of the lead frame that is in contact with the die attach paste is made of silver plated. Subsequently, the temperature was raised from a temperature of 25 ° C to a temperature of 175 ° C over 30 minutes in the atmosphere, and then heat treatment was performed at a temperature of 175 ° C for 60 minutes to cure the crystal grain adhesive of the laminate, thereby producing a cured product.

The cured product was allowed to absorb moisture at a temperature of 85 ° C and a humidity of 85% for 72 hours, and then the die-cut strength between the lead frame at 260 ° C and the cured product of the die attach paste was measured using a universal soldering tester. . The evaluation results are shown in Table 3 below. In addition, the unit is N/(2 mm x 2 mm).

As shown in Table 3, it was confirmed that the semiconductor device using the die attach paste of each of the examples can improve the mounting reliability as compared with the semiconductor device using the die attach paste of each comparative example.

The present application claims priority to Japanese Patent Application No. 2016-161129, filed on Jan.

Claims (40)

A die attach paste comprising: (A) a (meth)acrylic copolymer having a reactive group; (B) a (meth)acrylic monomer; and (C) a filler, the (A) (methyl) The reactive group provided in the acrylic copolymer is one or more selected from the group consisting of an epoxy group, an amine group, a vinyl group, a carboxyl group, and a hydroxyl group, and the weight average of the (A) (meth)acrylic copolymer is The molecular weight is 2,000 or more and 14,000 or less, and the particle diameter D ₅₀ at the time of 50% accumulation in the volume-based particle size distribution of the (C) filler is 0.3 μm or more and 4.0 μm or less, and the volume of the (C) filler is based on The particle diameter D ₉₀ at the time of accumulation of 90% in the particle size distribution is 15 μm or less. The die attach paste of claim 1, wherein the ratio of the particle diameter D ₅₀ to the particle diameter D ₉₀ (D ₅₀ /D ₉₀ ) is 1.05 or more and 3.5 or less.  The die attach paste of claim 1, wherein the (B) (meth)acrylic monomer comprises a monofunctional (meth)acrylic monomer and a polyfunctional (meth)acrylic monomer.    The die attach paste of claim 3, wherein among the (B) (meth)acrylic monomers, the polyfunctional (meth)acrylic monomer and the monofunctional (meth)acrylic acid The ratio of the content of the monomers is 0.3 or more and 10 or less.    The die attach paste of claim 1, comprising (D) a resin having a functional group reactive with the (A) (meth)acrylic copolymer, the (D) resin and The (A) (meth)acrylic acid copolymer has a weight average molecular weight of 500 or more and 10,000 or less.    The die attach paste of claim 5, wherein the (D) resin comprises (D1) allyl ester resin or (D2) polycarbonate resin.    The die attach paste of the fifth aspect of the invention, wherein the content of the (D) resin is 2% by mass or more and 20% by mass or less based on all the die attach paste.    The die attach paste of the first aspect of the invention, wherein the content of the (A) (meth)acrylic copolymer is 2% by mass or more and 15% by mass or less based on the total of the die attach paste.    The die attach paste of the first aspect of the invention, wherein the content of the (B) (meth)acrylic monomer is 4% by mass or more and 27% by mass or less based on the total of the die attach paste.    The die attach paste of claim 1, wherein the (C) filler comprises a conductive filler or a non-conductive filler.    The die attach paste of claim 10, wherein the conductive filler comprises a metal filler.    The die attach paste of claim 11, wherein the metal filler comprises silver powder.    The die attach paste of claim 10, wherein the non-conductive filler comprises an inorganic filler or an organic filler.    The die attach paste of claim 1, wherein the (C) filler comprises a spherical or flake-like filler.    The die attach paste of claim 1, wherein the (C) filler is contained in an amount of 25% by mass or more and 90% by mass or less based on the total of the die attach paste.    A die attach paste according to claim 1, which comprises a hardening accelerator.    The die attach paste of claim 16, wherein the content of the hardening accelerator is 0.01% by mass or more and 1% by mass or less based on the total of the die attach paste.    A die attach paste according to claim 1, which comprises (E) a decane coupling agent.    The die attach paste of claim 18, wherein the (E) decane coupling agent comprises a decane coupling agent having (meth)acrylic acid.    A die attach paste according to claim 1, which comprises (F) a low stress agent.    The die attach paste of claim 20, wherein the (F) low stress agent comprises a low stress agent having a functional group reactive with the (A) (meth)acrylic acid copolymer.    For example, in the grain adhesive paste of claim 1, wherein the viscosity of the die attach paste is more than 3 Pa ‧s and 30 Pa ‧ measured by a Brookfield viscometer at 25 ° C and 5.0 rpm s below.    A semiconductor device comprising: a substrate; and a semiconductor element mounted on the substrate via an adhesive layer of a cured product of the die attach paste of claim 1 of the patent application.    A die attach paste comprising: silver particles; a monomer; a main agent; and a radical polymerization initiator, wherein the die adhesion paste is applied to a length of 15.5 mm in a coating thickness of 35 ± 5 μm. On a silver-plated copper frame having a width of 6.5 mm, a tantalum wafer having a length of 15.0 mm, a width of 6.0 mm, and a thickness of 0.2 mm was placed on the die attach paste to obtain a laminate, and the laminate was removed from the laminate for 30 minutes. The temperature was raised to 175 ° C at 25 ° C, and further heat treatment was performed at 175 ° C for 5 hours to obtain a cured body. The amount of warpage when the cured body was heat-treated at 275 ° C for 1 minute was W1, and the temperature was 85 ° C. When the humidity is 85% and the cured body is hydrated for 168 hours, the amount of warpage when the heat treatment is performed at 275 ° C for 1 minute is W2, and |W2-W1| is 20 μm or less. The diagonal line connecting any two vertices of the diagonal in the in-plane direction of the ytterbium wafer has a maximum value of the distance of the position of the ruthenium wafer in the direction perpendicular to the diagonal.    The die attach paste of claim 24, wherein the die attach paste is applied to the silver plated copper frame in a coating thickness of 25 ± 5 μm, and then the length is 2.0 mm × the width of 2.0 mm. The xenon wafer having a thickness of 350 ± 5 μm was placed on the die attach paste, heated from 25 ° C to 175 ° C in 30 minutes, and further heat treated at 175 ° C for 5 hours to obtain a hardened body at a temperature of 85 ° C and a humidity of 85%. The cured body was allowed to absorb moisture for 72 hours to obtain a test piece, and with respect to the test piece, the die shear strength of the silver-plated copper frame and the tantalum wafer at 260 ° C was 17.0 N / (2 mm × 2 mm). the above.    The die attach paste of claim 24, wherein the silver particles are in the form of a sheet or a sphere.   The die attach paste of claim 24, wherein the silver particles have a tap density of 2.5 g/cm ³ or more and 10.0 g/cm ³ or less.  The die attach paste of claim 24, wherein the silver particles have an average particle diameter of 0.1 μm or more and 20 μm or less.    The grain-adhesive paste of claim 24, wherein the content of the silver particles in the die attach paste is 50 parts by mass or more and 90 parts by mass or less based on 100 parts by mass of the die attach paste.    The die attach paste of claim 24, wherein the monomer is one or more selected from the group consisting of an acrylic monomer, an epoxy monomer, and a maleimide monomer. .    The die attach paste of claim 24, wherein the monomer comprises the acrylic monomer.    The die attach paste according to claim 31, wherein the content of the acrylic monomer in the die attach paste is 1.0 part by mass or more and 30 parts by mass or less based on 100 parts by mass of the die attach paste.    The die attach paste of claim 31, wherein the acrylic monomer comprises a monofunctional acrylic monomer and a polyfunctional acrylic monomer, and the content of the monofunctional acrylic monomer in the die attach paste is relative to the 100 parts by mass of the polyfunctional acrylic monomer is 150 parts by mass or more and 650 parts by mass or less.    The die attach paste of claim 24, wherein the base agent is one or more selected from the group consisting of acrylic resins, epoxy resins, and allyl resins.    The die attach paste of claim 34, wherein the base agent comprises the acrylic resin, and the acrylic resin has a weight average molecular weight Mw of 2,000 or more and 13,000 or less.    The die attach paste of claim 34, wherein the monomer comprises an acrylic monomer, the main agent comprises the acrylic resin or the allyl resin, the acrylic resin in the die attach paste and the olefin The content of the resin is 85 parts by mass or more and 145 parts by mass or less based on 100 parts by mass of the acrylic monomer.    The die attach paste of claim 24, wherein the radical polymerization initiator is a peroxide.    The die attach paste of claim 24, wherein the die attach paste further comprises a hardener.    The die attach paste of claim 38, wherein the hardener comprises a phenol hardener or an imidazole hardener.    A semiconductor device comprising: a substrate; and a semiconductor element mounted on the substrate via an adhesive layer, wherein the adhesive layer is obtained by curing the die attach paste of claim 24 of the patent application.