阅读说明：本技术 膜状烧成材料及带支撑片的膜状烧成材料 (Film-like fired material and film-like fired material with support sheet ) 是由 市川功 中山秀一 于 2018-03-15 设计创作，主要内容包括：本发明的膜状烧成材料为含有烧结性金属颗粒(10)及粘结剂成分(20)的膜状烧成材料(1),在大气氛围下以10℃/分钟的升温速度于40℃～600℃测定的热重曲线(TG曲线)中的、负斜率最大的升温开始后的时间(A1),及将氧化铝颗粒作为参考试样、在大气氛围下以10℃/分钟的升温速度于40℃～600℃测定的差热分析曲线(DTA曲线)中的、升温开始后0秒～2160秒的时间范围内的最大峰值时间(B1)满足A1＜B1＜A1+200秒的关系,且A1＜2000秒。(A film-shaped fired material (1) comprising sinterable metal particles (10) and a binder component (20), wherein the time (A1) after the start of temperature rise with the maximum negative slope in a thermogravimetric curve (TG curve) measured at 40-600 ℃ at a temperature rise rate of 10 ℃/min in an atmospheric atmosphere, and the maximum peak time (B1) in a time range of 0-2160 seconds after the start of temperature rise in a differential thermal analysis curve (DTA curve) measured at 40-600 ℃ at a temperature rise rate of 10 ℃/min in an atmospheric atmosphere using alumina particles as a reference sample satisfy the relationship A1 < B1 < A1+200 seconds, and A1 < 2000 seconds.)

1. A film-like fired material comprising sinterable metal particles and a binder component, wherein,

A time (A1) after the start of temperature rise with the maximum negative slope in a thermogravimetric curve (TG curve) measured at 40 ℃ to 600 ℃ at a temperature rise rate of 10 ℃/min in an atmospheric atmosphere, and

In a differential thermal analysis curve (DTA curve) measured at 40-600 ℃ at a temperature rise rate of 10 ℃/min in an atmospheric atmosphere using alumina particles as a reference sample, the maximum peak time (B1) in the time range of 0-2160 seconds after the start of temperature rise satisfies

a1 < B1 < A1+200 seconds, and A1 < 2000 seconds.

2. The film-like fired material according to claim 1,

A time (A1') after the start of temperature rise with the largest negative slope in a thermogravimetric curve (TG curve) measured at 40 to 600 ℃ at a temperature rise rate of 10 ℃/min in an atmospheric atmosphere for components other than the sinterable metal particles in the film-shaped fired material, and

Among peaks observed in a time range of 960 seconds to 2160 seconds after the start of temperature rise in a differential thermal analysis curve (DTA curve) in which alumina particles are used as a reference sample and which is measured at 40 ℃ to 600 ℃ at a temperature rise rate of 10 ℃/minute in an atmospheric atmosphere, a peak time (B1') observed in the shortest time satisfies the requirement that

B1 '< A1'.

3. The film-like fired material according to claim 1 or 2,

The film-like fired material has no endothermic peak in a time range of 0 seconds to 2160 seconds after the start of temperature rise in a differential thermal analysis curve (DTA curve) in which alumina particles are used as a reference sample and the temperature rise is measured at 40 ℃ to 600 ℃ at a temperature rise rate of 10 ℃/minute in an atmospheric atmosphere.

4. A film-like fired material comprising sinterable metal particles and a binder component, wherein,

A temperature (A2) at which the negative slope is the greatest in a thermogravimetric curve (TG curve) measured at a temperature rise rate of 10 ℃/min under a nitrogen atmosphere, and

The peak temperature (B2) in the temperature range of 25-400 ℃ in a differential thermal analysis curve (DTA curve) measured by using alumina particles as a reference sample at a temperature rise rate of 10 ℃/min in a nitrogen atmosphere satisfies the requirement

A2 < B2 < A2+60 ℃.

5. The film-like fired material according to claim 4,

A temperature (A2') having the largest negative slope in a thermogravimetric curve (TG curve) measured at a temperature increase rate of 10 ℃/min under a nitrogen atmosphere for components other than the sinterable metal particles in the film-like sintered material, and

among peaks observed in a differential thermal analysis curve (DTA curve) in which alumina particles are used as a reference sample and which is measured at a temperature rise rate of 10 ℃/min in a nitrogen atmosphere and which is observed in a temperature range of 200 ℃ to 400 ℃, a peak temperature (B2') observed at the lowest temperature satisfies the requirement of

B2 '< A2'.

6. The film-like fired material according to claim 4 or 5,

The film-like fired material has no endothermic peak in a temperature range of 25 to 400 ℃ in a differential thermal analysis curve (DTA curve) measured at a temperature rise rate of 10 ℃/min under a nitrogen atmosphere using alumina particles as a reference sample.

7. The film-like fired material according to any one of claims 1 to 6, wherein the sinterable metal particles are silver nanoparticles.

8. A film-shaped fired material with a support sheet, comprising the film-shaped fired material according to any one of claims 1 to 7 and a support sheet provided on at least one side of the film-shaped fired material.

9. The film-like fired material with support sheet according to claim 8,

The support sheet is provided with an adhesive layer on a base material film,

The adhesive layer is provided with the film-like fired material.

Technical Field

The present invention relates to a film-like fired material and a film-like fired material with a support sheet.

The present application claims priority based on japanese patent application No. 2017-090714 filed in japan on 28 th.4 th.2017, japanese patent application No. 2017-179797 filed in japan on 9 th.20 th.2017, and japanese patent application No. 2017-192821 filed in japan on 10 th.2 th.2017, the contents of which are incorporated herein by reference.

Background

In recent years, with the increase in voltage and current of automobiles, air conditioners, computers, and the like, there has been an increasing demand for power semiconductor devices (also referred to as power units) mounted on these articles. Due to the characteristic that the power semiconductor element is used under high voltage and high current, heat generation of the semiconductor element is likely to be a problem.

Conventionally, a heat sink is sometimes attached around a semiconductor element in order to dissipate heat generated by the semiconductor element. However, if the thermal conductivity of the joint portion between the heat sink and the semiconductor element is poor, effective heat dissipation is hindered.

As a bonding material having excellent thermal conductivity, for example, patent document 1 discloses a paste-like metal fine particle composition in which specific heat sinterable metal particles, a specific polymer dispersant, and a specific volatile dispersion medium are mixed. It is considered that when the composition is sintered, a solid metal having excellent thermal conductivity is formed.

Disclosure of Invention

Technical problem to be solved by the invention

However, when the fired material is in the form of a paste as in patent document 1, it is difficult to make the thickness of the applied paste uniform, and the thickness stability tends to be poor.

The present invention has been made in view of the above circumstances, and an object thereof is to provide a film-like fired material which is excellent in thickness stability and thermal conductivity and exhibits excellent shear adhesion after firing. Further, another object of the present invention is to provide a film-like fired material with a support sheet, which is provided with the film-like fired material.

Means for solving the problems

Conventionally, it is considered that a lower thermal decomposition temperature of a material other than metal particles contained in a fired material is better. However, the inventors of the present application have studied the sintering mechanism from the viewpoint of the thermal physical properties, and have found that a film-shaped fired material having a specific relationship between the thermogravimetric curve (TG curve) and the differential thermal analysis curve (DTA curve) is excellent in thickness stability and thermal conductivity and can exhibit excellent shear adhesion after firing, and have completed the present invention.

that is, the present invention includes the following forms.

[1] A film-like fired material comprising sinterable metal particles and a binder component, wherein,

a time (A1) after the start of temperature rise with the maximum negative slope in a thermogravimetric curve (TG curve) measured at 40 ℃ to 600 ℃ at a temperature rise rate of 10 ℃/min in an atmospheric atmosphere, and

In a differential thermal analysis curve (DTA curve) measured at 40-600 ℃ at a temperature rise rate of 10 ℃/min in an atmospheric atmosphere using alumina particles as a reference sample, the maximum peak time (B1) in the time range of 0-2160 seconds after the start of temperature rise satisfies

A1 < B1 < A1+200 seconds, and A1 < 2000 seconds.

[2] The film-like fired material according to the above [1], wherein,

A time (A1') after the start of temperature rise with the largest negative slope in a thermogravimetric curve (TG curve) measured at 40 to 600 ℃ at a temperature rise rate of 10 ℃/min in an atmospheric atmosphere for components other than the sinterable metal particles in the film-shaped fired material, and

Among peaks observed in a time range of 960 seconds to 2160 seconds after the start of temperature rise in a differential thermal analysis curve (DTA curve) in which alumina particles are used as a reference sample and which is measured at 40 ℃ to 600 ℃ at a temperature rise rate of 10 ℃/minute in an atmospheric atmosphere, a peak time (B1') observed in the shortest time satisfies the requirement that

B1 '< A1'.

[3] The film-shaped fired material according to the above [1] or [2], wherein the film-shaped fired material has no endothermic peak in a time range of 0 seconds to 2160 seconds after the start of temperature rise in a differential thermal analysis curve (DTA curve) in which alumina particles are used as a reference sample and which is measured at a temperature rise rate of 10 ℃/minute at 40 ℃ to 600 ℃ in an atmospheric atmosphere.

[4] a film-like fired material comprising sinterable metal particles and a binder component, wherein,

A temperature (A2) at which the negative slope is the greatest in a thermogravimetric curve (TG curve) measured at a temperature rise rate of 10 ℃/min under a nitrogen atmosphere, and

the peak temperature (B2) in the temperature range of 25-400 ℃ in a differential thermal analysis curve (DTA curve) measured by using alumina particles as a reference sample at a temperature rise rate of 10 ℃/min in a nitrogen atmosphere satisfies the requirement

A2 < B2 < A2+60 ℃.

[5] The film-like fired material according to the above [4], wherein,

A temperature (A2') having the largest negative slope in a thermogravimetric curve (TG curve) measured at a temperature increase rate of 10 ℃/min under a nitrogen atmosphere for components other than the sinterable metal particles in the film-like sintered material, and

Among peaks observed in a differential thermal analysis curve (DTA curve) in which alumina particles are used as a reference sample and which is measured at a temperature rise rate of 10 ℃/min in a nitrogen atmosphere and which is observed in a temperature range of 200 ℃ to 400 ℃, a peak temperature (B2') observed at the lowest temperature satisfies the requirement of

b2 '< A2'.

[6] The film-shaped fired material according to the above [4] or [5], wherein the film-shaped fired material has no endothermic peak in a temperature range of 25 ℃ to 400 ℃ in a differential thermal analysis curve (DTA curve) measured at a temperature increase rate of 10 ℃/min under a nitrogen atmosphere with alumina particles as a reference sample.

[7] The film-like fired material according to any one of the above [1] to [6], wherein the sinterable metal particles are silver nanoparticles.

[8] a film-shaped fired material with a supporting sheet, comprising the film-shaped fired material according to any one of [1] to [7] and a supporting sheet provided on at least one side of the film-shaped fired material.

[9] The film-like fired material with a support sheet according to the above [8], wherein,

The support sheet is provided with an adhesive layer on a base material film,

The adhesive layer is provided with the film-like fired material.

effects of the invention

according to the present invention, a film-shaped fired material which is excellent in thickness stability and thermal conductivity and exhibits excellent shear adhesion after firing can be provided. Further, it is also possible to provide a film-like firing material with a support sheet for use in sintering and bonding a semiconductor element, which is provided with the film-like firing material.

Drawings

Fig. 1 is a cross-sectional view schematically showing a film-like fired material according to an embodiment of the present invention.

Fig. 2 is a cross-sectional view schematically showing an estimated form of a film-like fired material before and after firing according to an embodiment of the present invention.

FIG. 3 is a sectional view schematically showing an estimated form of another fired material before and after firing.

Fig. 4 is a cross-sectional view schematically showing a state where a film-like fired material with a support sheet according to an embodiment of the present invention is attached to a ring frame.

Fig. 5 is a cross-sectional view schematically showing a state where a film-like fired material with a support sheet according to an embodiment of the present invention is attached to a ring frame.

Fig. 6 is a perspective view schematically showing a state where a film-like fired material with a support sheet according to an embodiment of the present invention is attached to a ring frame.

Fig. 7 is a graph of a TG curve and a DTA curve obtained by measurement in an atmospheric atmosphere.

Fig. 8 is a graph of a TG curve and a DTA curve obtained by measurement in an atmospheric atmosphere.

Fig. 9 is a graph of a TG curve and a DTA curve obtained by measurement in an atmospheric atmosphere.

fig. 10 is a graph of a TG curve and a DTA curve obtained by measurement in an atmospheric atmosphere.

fig. 11 is a graph of a TG curve and a DTA curve obtained by measurement in a nitrogen atmosphere.

Fig. 12 is a graph of a TG curve and a DTA curve obtained by measurement in a nitrogen atmosphere.

Fig. 13 is a graph of a TG curve and a DTA curve obtained by measurement in a nitrogen atmosphere.

Fig. 14 is a graph of a TG curve and a DTA curve obtained by measurement in a nitrogen atmosphere.

Detailed Description

Hereinafter, embodiments of the present invention will be described with reference to the drawings as appropriate.

For the sake of easy understanding of the features of the present invention, important parts of the drawings used in the following description may be enlarged for convenience, and the dimensional ratios of the respective components are not necessarily the same as the actual ones.

Film-like firing Material

The film-shaped fired material of the first embodiment is a film-shaped fired material containing a sinterable metal particle and a binder component, and satisfies the relationship of A1 < B1 < A1+200 seconds and A1 < 2000 seconds in the time (A1) after the start of temperature rise with the maximum negative slope in a thermogravimetric curve (TG curve) measured at 40 to 600 ℃ at a temperature rise rate of 10 ℃/min in an atmospheric atmosphere, and the maximum peak time (B1) in the time range of 0 to 2160 seconds after the start of temperature rise in a differential thermal analysis curve (DTA curve) measured at 40 to 600 ℃ at a temperature rise rate of 10 ℃/min in an atmospheric atmosphere using an alumina particle as a reference sample.

The film-shaped fired material of the second embodiment is a film-shaped fired material containing a sinterable metal particle and a binder component, and satisfies the relationship of A2 < B2 < A2+60 ℃ in a thermogravimetric curve (TG curve) measured at a temperature rise rate of 10 ℃/min under a nitrogen atmosphere, at a temperature (A2) at which the negative slope is the largest, and a differential thermal analysis curve (DTA curve) measured at a temperature rise rate of 10 ℃/min under a nitrogen atmosphere using an alumina particle as a reference sample, at a maximum peak temperature (B2) within a temperature range of 25 ℃ to 400 ℃.

Fig. 1 is a cross-sectional view schematically showing a film-like fired material according to a first embodiment and a second embodiment. Film-like sintered material 1 contains sintered metal particles 10 and binder component 20.

The film-like firing material may be composed of one layer (single layer), or may be composed of a plurality of 2 or more layers. When the film-like fired material is composed of a plurality of layers, the plurality of layers may be the same or different from each other, and the combination of the plurality of layers is not particularly limited as long as the effect of the present invention is not impaired.

In the present specification, the phrase "a plurality of layers may be the same or different from each other" means "all the layers may be the same or different from each other, or only a part of the layers may be the same", and "a plurality of layers are different from each other" means "at least one of the constituent materials, the blending ratio of the constituent materials, and the thickness of each layer are different from each other".

The thickness of the film-like fired material before firing is not particularly limited, but is preferably 10 to 200. mu.m, preferably 20 to 150. mu.m, and more preferably 30 to 90 μm.

Here, the "thickness of the film-like fired material" refers to the thickness of the entire film-like fired material, and for example, the thickness of the film-like fired material composed of a plurality of layers refers to the total thickness of all the layers constituting the film-like fired material.

In the present specification, "thickness" is a value represented by an average of thicknesses measured at arbitrary 5 points, and can be obtained using a constant-pressure thickness gauge based on JIS K7130.

(Release film)

The film-like fired material may be provided in a state of being laminated on the release film. In use, the release film is peeled off and placed on an object to which the film-like fired material is to be sintered and bonded. The release film also functions as a protective film for preventing damage or adhesion of dirt to the film-like fired material. The release film may be provided on at least one side of the film-like fired material, or may be provided on both sides of the film-like fired material.

as the release film, for example, a transparent film such as a polyethylene film, a polypropylene film, a polybutylene film, a polybutadiene film, a polymethylpentene film, a polyvinyl chloride film, a vinyl chloride copolymer film, a polyethylene terephthalate film, a polyethylene naphthalate film, a polybutylene terephthalate film, a polyurethane film, an ethylene vinyl acetate copolymer film, an ionomer resin film, an ethylene- (meth) acrylic acid copolymer film, an ethylene- (meth) acrylate copolymer film, a polystyrene film, a polycarbonate film, a polyimide film, a fluororesin film, or the like can be used. In addition, a crosslinked film of these transparent films may also be used. Further, a laminated film of these transparent films is also possible. In addition, a film obtained by coloring these transparent films, an opaque film, or the like can be used. Examples of the release agent include silicone-based, fluorine-based, alkyd-based, olefin-based, and long-chain alkyl group-containing carbamates.

The thickness of the release film is usually 10 to 500. mu.m, preferably 15 to 300. mu.m, and particularly preferably about 20 to 250. mu.m.

< sintered Metal particle >

The sinterable metal particles are metal particles that can be formed into a sintered body by performing a heat treatment that is firing of a film-like firing material to fuse and bond the particles to each other. By forming a sintered body, the film-like sintered material can be sintered and joined to an article to be sintered in contact therewith.

examples of the metal species of the sinterable metal particles include silver, gold, copper, iron, nickel, aluminum, silicon, palladium, platinum, titanium, barium titanate, and oxides or alloys thereof, and silver oxide are preferred. The sintering metal particles may be blended only one kind, or may be blended in a combination of two or more kinds.

The sinterable metal particles are preferably silver nanoparticles as nanoscale silver particles.

The particle diameter of the sinterable metal particles contained in the film-like firing material is not particularly limited as long as the sinterability is exhibited, and may be 100nm or less, 50nm or less, or 30nm or less. The particle size of the metal particles contained in the film-like sintered material means a projected area circle-equivalent diameter of the particle size of the metal particles observed by an electron microscope.

Metal particles having the above particle diameter range are preferable because they are excellent in sinterability.

The particle size of the sinterable metal particles contained in the film-like firing material may be 0.1 to 95nm, 0.3 to 50nm, or 0.5 to 30nm in number average (number average) of particle sizes determined for particles having a diameter of 100nm or less as a circle of a projected area of the particle size of the metal particles observed with an electron microscope. The number of metal particles to be measured is 100 or more selected at random for each film-like sintered material.

Since the sinterable metal particles are made to be free of an inner polymer before being mixed with the binder component and other additive components, they can be dispersed in a high boiling point solvent having a relatively high boiling point, such as isobornyl hexanol (isobornyl hexanol) or decanol. The boiling point of the high boiling point solvent may be, for example, 200 to 350 ℃. In this case, since the high boiling point solvent is not almost volatilized at normal temperature, the concentration of the sinterable metal particles can be prevented from increasing, and the workability can be improved, and the quality can be improved by preventing the re-agglomeration of the sinterable metal particles in some cases.

Examples of the dispersion method include a kneader, a three-roll mill, a bead mill, and ultrasonic waves.

In the present specification, "normal temperature" refers to a temperature at which cooling or heating is not particularly performed, that is, a normal temperature, and examples thereof include a temperature of 15 to 25 ℃.

In the film-like firing material of the above embodiment, in addition to the metal particles (sintered metal particles) having a particle diameter of 100nm or less, non-sintered metal particles having a particle diameter of more than 100nm, which are not included in the metal particles, may be further blended. The number of particle diameters determined for particles having a particle diameter of more than 100nm, which is a circle of a projected area of the particle diameters of the metal particles observed with an electron microscope and which corresponds to the particle diameter of more than 100nm, may be more than 150nm and 50000nm or less, may be 150 to 10000nm, or may be 180 to 5000 nm.

The metal species of the non-sintered metal particles having a particle diameter of more than 100nm include those exemplified above, and silver, copper and oxides thereof are preferable.

The metal particles having a particle diameter of 100nm or less and the non-sintered metal particles having a particle diameter of more than 100nm may be the same metal species or different metal species. For example, the metal particles having a particle size of 100nm or less may be silver particles, and the non-sintered metal particles having a particle size of more than 100nm may be silver or silver oxide particles. For example, the metal particles having a particle size of 100nm or less may be silver or silver oxide particles, and the non-sintered metal particles having a particle size of more than 100nm may be copper or copper oxide particles.

In the film-shaped fired material of the above embodiment, the content of the metal particles having a particle diameter of 100nm or less may be 20 to 100 parts by mass, 30 to 99 parts by mass, or 50 to 95 parts by mass, based on 100 parts by mass of the total of all the metal particles.

At least one surface of the sintered metal particles and the non-sintered metal particles may be covered with an organic substance. By having the coating film of an organic substance, the compatibility with the binder component is improved. Further, the particles can be prevented from agglomerating with each other and uniformly dispersed.

When at least one surface of the sinterable metal particles and the non-sinterable metal particles is covered with an organic substance, the mass of the sinterable metal particles and the non-sinterable metal particles is a value including a covering.

< Binder component >

By blending the binder component, the fired material can be formed into a film shape, and adhesiveness can be imparted to the film-shaped fired material before firing. The binder component may have thermal decomposability that is thermally decomposed by a heat treatment for firing as a film-like firing material.

the binder component is not particularly limited, and a preferred example of the binder component is a resin. Examples of the resin include acrylic resins, polycarbonate resins, polylactic acids, and polymers of cellulose derivatives, and acrylic resins are preferred. The acrylic resin contains a homopolymer of a (meth) acrylate compound, a copolymer of two or more (meth) acrylate compounds, and a copolymer of a (meth) acrylate compound and another copolymerizable monomer.

The content of the structural unit derived from the (meth) acrylate compound in the resin constituting the binder component is preferably 50 to 100% by mass, more preferably 80 to 100% by mass, and still more preferably 90 to 100% by mass, based on the total amount of the structural units.

By "derived" herein is meant that the monomer undergoes the structural change required for polymerization.

Specific examples of the (meth) acrylate compound include methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, isopropyl (meth) acrylate, butyl (meth) acrylate, isobutyl (meth) acrylate, t-butyl (meth) acrylate, pentyl (meth) acrylate, isopentyl (meth) acrylate, hexyl (meth) acrylate, heptyl (meth) acrylate, octyl (meth) acrylate, isooctyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, nonyl (meth) acrylate, decyl (meth) acrylate, isodecyl (meth) acrylate, undecyl (meth) acrylate, dodecyl (meth) acrylate, lauryl (meth) acrylate, and mixtures thereof, Alkyl (meth) acrylates such as stearic (meth) acrylate and isostearic (meth) acrylate;

hydroxyalkyl (meth) acrylates such as hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate, and 3-hydroxybutyl (meth) acrylate; phenoxyalkyl (meth) acrylates such as phenoxyethyl (meth) acrylate and 2-hydroxy-3-phenoxypropyl (meth) acrylate; alkoxyalkyl (meth) acrylates such as 2-methoxyethyl (meth) acrylate, 2-ethoxyethyl (meth) acrylate, 2-propoxyethyl (meth) acrylate, 2-butoxyethyl (meth) acrylate, and 2-methoxybutyl (meth) acrylate; polyalkylene glycol (meth) acrylates such as polyethylene glycol (meth) acrylate, ethoxydiethylene glycol (meth) acrylate, methoxypolyethylene glycol (meth) acrylate, phenoxypolyethylene glycol (meth) acrylate, nonylphenoxypolyethylene glycol (meth) acrylate, polypropylene glycol mono (meth) acrylate, methoxypolypropylene glycol (meth) acrylate, ethoxypolypropylene glycol (meth) acrylate, and nonylphenoxypolypropylene glycol (meth) acrylate; cycloalkyl (meth) acrylates such as cyclohexyl (meth) acrylate, 4-butylcyclohexyl (meth) acrylate, dicyclopentanyl (meth) acrylate, dicyclopentenyl (meth) acrylate, dicyclopentadienyl (meth) acrylate, bornyl (meth) acrylate, isobornyl (meth) acrylate, and tricyclodecanyl (meth) acrylate;

Benzyl (meth) acrylate, tetrahydrofurfuryl (meth) acrylate, and the like. The (meth) acrylic acid alkyl ester or the (meth) acrylic acid alkoxyalkyl ester is preferable, and particularly preferable (meth) acrylic acid ester compounds include butyl (meth) acrylate, ethylhexyl (meth) acrylate, lauryl (meth) acrylate, isodecyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, and 2-ethoxyethyl (meth) acrylate.

In the present specification, "(meth) acrylic acid" is a concept including both "acrylic acid" and "methacrylic acid", and "(meth) acrylate" is a concept including both "acrylate" and "methacrylate".

As the acrylic resin, methyl acrylate is preferable. By making the binder component contain a methyl acrylate-derived structural unit, a film-like fired material having a relationship of A1 < B1 < A1+200 seconds and A1 < 2000 seconds between the time (A1) and the time (B1) can be easily obtained. Further, by making the binder component contain a structural unit derived from methyl acrylate, a film-like fired material having a relationship of A2 < B2 < A2+60 ℃ between the temperature (A2) and the temperature (B2) can be easily obtained.

In the resin constituting the binder component, the content of the structural unit derived from methyl acrylate is preferably 50 to 100% by mass, more preferably 80 to 100% by mass, and still more preferably 90 to 100% by mass, based on the total amount of the structural units.

The other copolymerizable monomer is not particularly limited as long as it is a compound copolymerizable with the (meth) acrylic acid ester compound, and examples thereof include unsaturated carboxylic acids such as (meth) acrylic acid, vinylbenzoic acid, maleic acid, and vinylphthalic acid; vinyl group-containing radically polymerizable compounds such as vinylbenzyl methyl ether, vinylglycidyl ether, styrene, α -methylstyrene, butadiene, and isoprene.

The weight average molecular weight (Mw) of the resin constituting the binder component is preferably 1,000 to 1,000,000, more preferably 10,000 to 800,000. When the weight average molecular weight of the resin is in the above range, sufficient film strength as a film can be easily obtained and flexibility can be imparted.

In the present specification, unless otherwise specified, "weight average molecular weight" is a polystyrene equivalent value measured by a Gel Permeation Chromatography (GPC) method.

The glass transition temperature (Tg) of the resin constituting the binder component can be calculated by using the following Fox formula, and the glass transition temperature (Tg) is preferably-60 to 50 ℃, more preferably-30 to 10 ℃, and further preferably-20 ℃ or higher and less than 0 ℃. When Tg of the resin, which is obtained by the Fox equation, is not more than the upper limit, the adhesion between the film-like fired material and an adherend (for example, a semiconductor element, a chip, a substrate, or the like) before firing is improved. On the other hand, when Tg of the resin obtained by the Fox equation is equal to or higher than the lower limit value, the film shape can be maintained, and the film-like fired material can be more easily separated from the support sheet or the like.

According to the Fox formula, the Tg of the acrylic polymer and the weight ratio of the monomers of each polymer portion show the following relationship:

1/Tg＝(W1/Tg1)+(W2/Tg2)+…+(Wm/Tgm)

W1+W2+…+Wm＝1

in the formula, Tg represents the glass transition temperature of the polymer portion, and Tg1, Tg2, … and Tgm represent the glass transition temperature of each of the polymerized monomers. W1, W2, … and Wm denote the weight ratios of the respective monomers to be polymerized.

The glass transition temperature of each of the polymerizable monomers in the Fox formula can be a value described in a polymer data manual and an adhesion manual.

The binder component may have thermal decomposability that is thermally decomposed by a heat treatment for firing as a film-like firing material. It can be confirmed that the binder component is thermally decomposed by the decrease in mass of the binder component caused by firing. Further, although the components blended as the binder component are substantially thermally decomposed by firing, it is not necessary that the total mass of the components blended as the binder component is thermally decomposed by firing.

The binder component may be contained in an amount of 10 mass% or less, 5 mass% or less, or 3 mass% or less, based on 100 mass% of the binder component before firing.

The film-shaped fired material of the above embodiment may contain, in addition to the above-described sinterable metal particles, non-sinterable metal particles, and binder component, other additives not belonging to the sinterable metal particles, non-sinterable metal particles, and binder component, within a range not impairing the effects of the present invention.

Examples of other additives that can be contained in the film-shaped firing material of the above embodiment include a solvent, a dispersant, a plasticizer, a thickener, a storage stabilizer, an antifoaming agent, a thermal decomposition accelerator, an antioxidant, and the like. The additive may contain only one kind or two or more kinds. These additives are not particularly limited, and additives commonly used in the art can be appropriately selected.

< composition >

The film-shaped fired material of the embodiment may be formed of sinterable metal particles, a binder component, and other additives, and the sum of the contents (mass%) of these components may be 100 mass%.

When the film-like sintered material of the above embodiment contains non-sinterable metal particles, the film-like sintered material may be formed of sinterable metal particles, non-sinterable metal particles, a binder component and other components, and the sum of the contents (mass%) of these components may be 100 mass%.

In the film-like firing material, the content of the sinterable metal particles is preferably 10 to 98 mass%, more preferably 15 to 90 mass%, and still more preferably 20 to 80 mass% with respect to 100 mass% of the total content of all components (hereinafter referred to as "solid components") except the solvent.

When the film-like sintered material contains non-sinterable metal particles, the total content of the sinterable metal particles and the non-sinterable metal particles is preferably 50 to 98 mass%, more preferably 70 to 95 mass%, and still more preferably 80 to 90 mass%, relative to 100 mass% of the total content of the solid components in the film-like sintered material.

The content of the binder component is preferably 2 to 50% by mass, more preferably 5 to 30% by mass, and still more preferably 10 to 20% by mass, based on 100% by mass of the total solid content in the film-like fired material.

In the film-like firing material, the mass ratio of the sinterable metal particles to the binder component (sinterable metal particles: binder component) is preferably 50:1 to 1:5, more preferably 20:1 to 1:2, and still more preferably 10:1 to 1: 1. When the film-like sintered material contains non-sinterable metal particles, the mass ratio of the sinterable metal particles and non-sinterable metal particles to the binder component ((sinterable metal particles + non-sinterable metal particles): binder component) is preferably 50:1 to 1:1, more preferably 20:1 to 2:1, and still more preferably 9:1 to 4: 1.

[ film-like fired Material of the first embodiment ]

By providing the film-shaped fired material of the first embodiment with the composition described above, it is easy to obtain a film-shaped fired material in which the time (a1) and the time (B1) have a relationship of a1 < B1 < a1+200 seconds and a1 < 2000 seconds.

The film-like sintered material of the first embodiment may contain a high boiling point solvent used when mixing the sinterable metal particles, the non-sinterable metal particles, the binder component and other additive components. The content of the high boiling point solvent is preferably 20 mass% or less, more preferably 15 mass% or less, and still more preferably 10 mass% or less, based on 100 mass% of the total mass of the film-shaped fired material according to the first embodiment. By setting the content of the high-boiling solvent to the upper limit or less, a film-like fired material having a relationship of A1 < B1 < A1+200 seconds and A1 < 2000 seconds between the time (A1) and the time (B1) can be easily obtained. Further, it is easy to obtain a film-like fired material having no endothermic peak in the time range of 0 seconds to 2160 seconds after the start of temperature rise in the differential thermal analysis curve (DTA curve) obtained by measurement in an atmospheric atmosphere.

< time (A1) > "time (B1) >

The film-shaped firing material of the first embodiment satisfies the relationship of a1 < B1 < a1+200 seconds, a1 < 2000 seconds, in a thermogravimetric curve (TG curve) measured at a temperature rise rate of 10 ℃/minute under an atmospheric atmosphere at 40 to 600 ℃, a time (a1) after the start of the temperature rise at which the negative slope is the largest, and a maximum peak time (B1) in a differential thermal analysis curve (DTA curve) measured at a temperature rise rate of 10 ℃/minute under an atmospheric atmosphere at 40 to 600 ℃ in a differential thermal analysis curve (DTA curve) in which alumina particles are used as a reference sample and in which the time ranges from 0 seconds to 2160 seconds after the start of the temperature rise.

The TG curve shows the change in weight of the film-shaped fired material in the course of the heat treatment of the film-shaped fired material in the atmospheric atmosphere.

The DTA curve shows a differential thermal change of the film-shaped fired material in the process of heat-treating the film-shaped fired material in the atmospheric atmosphere.

Hereinafter, the form of the film-shaped fired material in the firing process estimated from the TG curve and the DTA curve obtained by measurement in the atmospheric atmosphere will be described with reference to the drawings as appropriate.

fig. 2 is a cross-sectional view schematically showing an estimated form of the film-like fired material 1 before firing (fig. 2 (a)), during firing (fig. 2 (B)), and after firing (fig. 2 (c)) that satisfies the relationship of a1 < B1 < a1+200 seconds and a1 < 2000 seconds.

The weight of the binder component 20 contained in the film-like sintered material (fig. 2 (a)) before sintering is reduced by heating (fig. 2 (b) to (c)), and this phenomenon appears as a negative slope in the TG curve.

The binder component 20 contained in the film-shaped fired material before firing (fig. 2 (a)) is thermally decomposed by absorbing heat during heating, and the sinterable metal particles 10 contained in the film-shaped fired material before firing (fig. 2 (a)) are melted by absorbing heat during heating (fig. 2 (b)), and then fired while being released from heat (fig. 2 (c)). The heat absorption and release process is observed as a DTA curve, and when the sintering process is sufficiently performed, the heat release amount is large and far exceeds the heat absorption amount by the thermal decomposition of the binder component 20 contained in the film-like sintered material (fig. 2 (a)) and the melting of the sinterable metal particles 10. That is, only positive differential heat due to heat release was observed in the DTA curve obtained by the measurement, and the curve appeared as a peak.

It is considered that the time (A1) and the time (B1) satisfy the relationship of A1 < B1 < A1+200 seconds, and A1 < 2000 seconds means that the melting and sintering of the sinterable metal particles are completed within the heating time immediately following the decrease of the binder component. It is generally known that the firing temperature is related to the size of the metal particles, and the smaller the metal particles, the lower the firing temperature tends to be. Therefore, it is estimated that the film-like sintered material 1 satisfying the relationship of A1 < B1 < A1+200 seconds and A1 < 2000 seconds is sintered with each other in the state that agglomeration or fusion of the sinterable metal particles is not observed at the start of sintering, and the sinterable metal particles 10m in which fine particles are directly melted are sintered.

FIG. 3 is a cross-sectional view schematically showing the estimated forms of the fired material 1c before firing (FIG. 3 (a)), during firing (FIG. 3 (B)), and after firing (FIG. 3 (c)) which do not satisfy the relationship of A1 < B1 < A1+200 seconds and in which the time of B1 is longer than A1+200 seconds. The weight of the binder component 21 contained in the film-like sintered material (fig. 3 (a)) before sintering is also reduced by heating (fig. 3 (b) to (c)), and this phenomenon appears as a negative slope in the TG curve.

the binder component 21 contained in the film-shaped fired material before firing (fig. 3 (a)) is also thermally decomposed by absorbing heat during heating, and thereafter, the sinterable metal particles 11 contained in the film-shaped fired material before firing (fig. 3 (a)) are melted by the absorption of heat and sintered by the release of heat ((c) of fig. 3). In the heat absorption and release process of the sinterable metal particles 11, the binder component 21 is not present or is present in a trace amount if present, and therefore, although the heat absorption and release process occurs almost simultaneously, the heat release amount by sintering is large, and therefore, only a positive peak indicating the heat release process appears in the DTA curve.

The relationship that the time (a1) and the time (B1) do not satisfy a1 < B1 < a1+200 seconds is considered to mean that the sintering of the sinterable metal particles is not completed in the heating time immediately following the decrease in the binder component. The firing temperature is related to the size of the metal particles, and tends to be higher as the metal particles are larger. Therefore, for example, it is assumed that the sintered metal particles in the sintered material 1c having a time of B1 longer than A1+200 seconds are large in size, and do not satisfy the relationship of A1 < B1 < A1+200 seconds in the sintering stage. This is considered to be due to the fact that the reduction of the binder component by heating is performed before the melting and sintering peaks of the sinterable metal particles, and therefore, at the sintering start stage, the sinterable metal particles 11 form blocks of a certain size, and the metal particles in the blocks are sintered, which leads to an increase in the time (B1).

The inventors of the present application have found that the time (a1) and the time (B1) satisfy the relationship of a1 < B1 < a1+200 seconds, and that the film-like fired material of a1 < 2000 seconds is excellent in shear adhesion after firing.

It is considered that, in a sintered material in which the relationship of a1 < B1 < a1+200 seconds is not satisfied and the time of B1 is longer than a1+200 seconds, the sintered metal particles in a lump form are sintered, and thus sintering is insufficient, or a large number of unsintered portions remain, and the bond strength (shear bond strength) of the sintered material is insufficient. Alternatively, it is considered that voids are likely to be generated at the adhesion interface with the adherend, and the adhesion area is reduced, thereby reducing the adhesion strength.

Further, even if the relationship of A1 < B1 < A1+200 seconds is satisfied, it is considered that the film-like fired material having an A1 or more than 2000 seconds is deteriorated in productivity due to the extension of tact time (tact time), and the temperature required for firing is excessively high, which adversely affects the equipment members.

In contrast, it is considered that a film-like sintered material satisfying the relationship of a1 < B1 < a1+200 seconds and a1 < 2000 seconds sinters sintered metal particles directly melted in fine particles in the presence of a binder component, and therefore the sintered metals form uniform and close metal bonds with each other, resulting in an improvement in the adhesive strength of the sintered material.

The shear adhesion of the film-shaped fired material after firing can be measured by the method described in examples.

The above-mentioned time (A1) and the above-mentioned time (B1) of the film-like sintered material of the first embodiment satisfy the relationship of A1 < B1 < A1+200 seconds, for example, the relationship of A1 < B1 < A1+100 seconds, the relationship of A1 < B1 < A1+60 seconds, or the relationship of A1 < B1 < A1+30 seconds.

In a differential thermal analysis curve (DTA curve) measured at 40 to 600 ℃ in an atmospheric atmosphere at a temperature rise rate of 10 ℃/min using alumina particles as a reference sample, the maximum peak time (B1) in the time range of 0 to 2160 seconds after the start of temperature rise preferably has a maximum peak time in the range of 960 to 2160 seconds after the start of temperature rise, more preferably has a maximum peak time in the range of 1080 to 2100 seconds after the start of temperature rise, and still more preferably has a maximum peak time in the range of 1260 to 2040 seconds after the start of temperature rise.

< time (A1 '), "time (B1') >)

In the film-shaped fired material of the first embodiment, it is preferable that the peak time (B1 ') observed in the shortest time satisfies the relationship of B1' < a1 'among the time (a 1') after the start of temperature rise with the largest negative slope in a thermogravimetric curve (TG curve) measured at a temperature rise rate of 10 ℃/min at 40 to 600 ℃ in an atmospheric atmosphere for components other than the sinterable metal particles in the film-shaped fired material, and the peak observed in a differential thermal analysis curve (DTA curve) measured at a temperature rise rate of 10 ℃/min at 40 to 600 ℃ in an atmospheric atmosphere for the sinterable metal particles in the time range of 960 seconds to 2160 seconds after the start of temperature rise.

The above-mentioned TG curve shows the weight change of the components other than the sinterable metal particles in the film-like sintered material during the heat treatment for sintering in the atmospheric atmosphere.

The DTA curve shows the differential thermal change of the sinterable metal particles during the heat treatment for firing in the atmospheric atmosphere.

In the film-shaped fired material of the first embodiment when the film-shaped fired material of the first embodiment contains non-sinterable metal particles, the film-shaped fired material contains components other than the sinterable metal particles and the non-sinterable metal particles, a time (A1') after the start of temperature rise with the largest negative slope in a thermogravimetric curve (TG curve) measured at a temperature rise rate of 10 ℃/min under an atmospheric atmosphere at 40 ℃ to 600 ℃, and a method for producing a sintered metal particle and a non-sintered metal particle, in a peak observed in a time range of 960 seconds to 2160 seconds after the start of temperature rise in a differential thermal analysis curve (DTA curve) in which alumina particles are used as a reference sample and which is measured at 40 ℃ to 600 ℃ at a temperature rise rate of 10 ℃/minute in an atmospheric atmosphere, the peak time (B1 ') observed in the shortest time preferably satisfies the relationship of B1 ' < A1 '.

The phenomenon is expressed as a negative slope in the TG curve, in which the weight of components other than the sintered metal particles and the non-sintered metal particles in the film-shaped sintered material containing the binder component, which are contained in the film-shaped sintered material before sintering, decreases by heating in an atmospheric atmosphere.

The sinterable metal particles contained in the film-like sintered material before firing are melted and sintered by heating in the atmospheric atmosphere, and the melting phenomenon appears as a negative peak in the DTA curve and the sintering phenomenon appears as a positive peak in the DTA curve.

It is considered that the relationship that the time (a1 ') and the time (B1') satisfy B1 '< a 1' means that the melting and sintering of the sinterable metal particles start earlier than the timing at which the weight of the components of the film-like sintering material distributed around the sinterable metal particles is reduced during the heat treatment. Therefore, the film-like sintering material satisfying the relationship of B1 ' < a1 ' is in a state where it is isolated from each other by the components distributed around the sinterable metal particles, and easily melts directly in fine particles, and at the time point when the time (a1 ') is reached, the collision frequency thereof sharply increases, and the sinterable metal particles melted directly in fine particles are easily sintered to each other. As a result, it is considered that in the film-like sintered material satisfying the relationship of B1 '< a 1', the sinterable metals form metal bonds uniformly close to each other, and the adhesive strength of the sintered material is improved.

The time (a1 ') and the time (B1') can be determined from the TG curve and the DTA curve for each separated sample by separating the sinterable metal particles and the components other than the sinterable metal particles from the film-like sintered material before firing.

The separation of the sinterable metal particles and the remaining components other than the sinterable metal particles in the film-like sintered material before firing can be performed by, for example, the following method.

First, a film-shaped firing material before firing is mixed with a sufficient amount of an organic solvent, and then the mixture is allowed to stand for a sufficient time until the sinterable metal particles settle. The supernatant liquid is taken out by a syringe or the like, and the residue after drying at 120 ℃ for 10 minutes is collected, whereby components other than the sinterable metal particles can be separated from the film-like sintered material. Further, a sufficient amount of the organic solvent is mixed again into the solution containing the sinterable metal particles after the supernatant liquid is taken out by the above-mentioned syringe or the like, and then the mixture is left to stand for a sufficient time until the sinterable metal particles settle, and the supernatant liquid is taken out by the syringe or the like.

The mixing and standing of the organic solvent and the removal of the supernatant were repeated 5 or more times, and the residue obtained by drying the residual liquid at 120 ℃ for 10 minutes was recovered, whereby sinterable metal particles could be separated.

This point is the same in the case where the film-shaped sintered material of the first embodiment contains non-sinterable metal particles, and the time (a1 ') and the time (B1') can be determined from the TG curve and the DTA curve for each of the separated samples by separating the sinterable metal particles and the non-sinterable metal particles, and components other than the sinterable metal particles and the non-sinterable metal particles, from the film-shaped sintered material before firing.

The separation of the sinterable metal particles and non-sinterable metal particles in the film-like sintered material before firing and the remaining components other than the sinterable metal particles and non-sinterable metal particles can be performed by, for example, the following method.

First, a film-shaped firing material before firing is mixed with a sufficient amount of an organic solvent, and then the mixture is allowed to stand for a sufficient time until the sinterable metal particles and non-sinterable metal particles settle. The components other than the sinterable metal particles and non-sinterable metal particles can be separated from the film-like sintered material by taking out the supernatant liquid with a syringe or the like and recovering the residue after drying at 120 ℃ for 10 minutes. Further, a sufficient amount of the organic solvent is mixed again into the solution containing the sinterable metal particles and the non-sinterable metal particles after the supernatant liquid is taken out by the above-mentioned syringe or the like, and then the mixture is left to stand for a sufficient time until the sinterable metal particles and the non-sinterable metal particles settle, and the supernatant liquid is taken out by the syringe or the like. The mixing and standing of the organic solvent and the removal of the supernatant are repeated 5 or more times, and the residue obtained by drying the residual liquid at 120 ℃ for 10 minutes is collected, whereby sinterable metal particles and non-sinterable metal particles can be separated.

The solvent used here is capable of dissolving the binder component, and is preferably capable of being volatilized under the drying conditions of 120 to 250 ℃ for 10 minutes, and the preferred solvent may be appropriately used depending on the kind of the binder component and the like. Examples thereof include hydrocarbons such as toluene and xylene; alcohols such as methanol, ethanol, 2-propanol, isobutanol (2-methylpropane-1-ol), and 1-butanol; esters such as ethyl acetate; ketones such as acetone and methyl ethyl ketone; ethers such as tetrahydrofuran; amides (compounds having an amide bond) such as dimethylformamide and N-methylpyrrolidone.

< endothermic peak >

In the film-like fired material of the first embodiment, it is preferable that the film-like fired material has no endothermic peak in a time range of 0 seconds to 2160 seconds after the start of temperature rise in a differential thermal analysis curve (DTA curve) in which alumina particles are used as a reference sample and the temperature rise rate is 10 ℃/min and the temperature is measured at 40 ℃ to 600 ℃ in an atmospheric atmosphere.

The DTA curve represents a change in the differential heat of the film-like sintered material during the heating treatment of the film-like sintered material by the sintering.

When an endothermic peak is observed in the DTA curve, it is considered that the film-shaped fired material contains a component having a property that changes (for example, evaporates) by absorbing heat from the film-shaped fired material within 0 seconds to 2160 seconds after the start of temperature rise. That is, it is considered that evaporation of the components occurs, and evaporation heat associated therewith is required. Or a large amount of a component that absorbs heat and thermally decomposes, exceeding the amount of heat released by sintering.

Therefore, it is preferable that the content of a component having a property of evaporating from the film-shaped firing material within 0 seconds to 2160 seconds after the start of temperature increase in the film-shaped firing material of the first embodiment is small or not. In addition, it is preferable that the content of a component which absorbs much heat in thermal decomposition and interferes with the exothermic process based on sintering is small or not.

Here, before the DTA curve is measured for the film-shaped fired material, the film-shaped fired material is subjected to pretreatment such as drying, and it is recommended that moisture absorbed as impurities is not measured. The drying conditions include 110 ℃ for 4 minutes.

In the DTA curve, since there is no endothermic peak in the time range of 0 to 2160 seconds after the start of temperature rise, the components distributed around the sintered metal particles are not reduced, and the particles are easily isolated from each other by the components distributed around the sintered metal particles. As a result, in the film-like sintered material having no endothermic peak in the time range of 0 to 2160 seconds after the start of temperature rise in the DTA curve, the sinterable metals form metal bonds that are uniformly tight, and the strength of the sintered material is likely to be improved. Further, the loss of energy required for firing is reduced, and firing in a favorable environment can be achieved. Further, it is considered that the shear adhesion of the film-like fired material after firing is improved.

The film-shaped fired material according to the first embodiment has excellent thickness stability because it is in a film shape. In addition, the film-shaped firing material of the first embodiment contains the sinterable metal particles, and therefore has excellent thermal conductivity. Further, the film-like fired material of the first embodiment satisfies the relationship of A1 < B1 < A1+200 seconds and A1 < 2000 seconds, and exhibits excellent shear adhesion after firing.

[ film-like fired Material according to the second embodiment ]

By making the film-shaped fired material of the second embodiment have the composition shown above, a film-shaped fired material having a relationship of a2 < B2 < a2+60 ℃ between the temperature (a2) and the temperature (B2) can be easily obtained.

The film-shaped fired material of the second embodiment may contain a high boiling point solvent used for mixing the sinterable metal particles, the non-sinterable metal particles, the binder component and other additive components. The content of the high boiling point solvent is preferably 20 mass% or less, more preferably 15 mass% or less, and still more preferably 10 mass% or less, based on 100 mass% of the total mass of the film-shaped fired material according to the second embodiment. By setting the content of the high-boiling solvent to the upper limit or less, a film-like fired material having a relationship of A2 < B2 < A2+60 ℃ between the temperature (A2) and the temperature (B2) can be easily obtained. Further, it is easy to obtain a film-like fired material having no endothermic peak in the temperature range of 25 to 400 ℃ in the differential thermal analysis curve (DTA curve) obtained by measurement in a nitrogen atmosphere.

< temperature (A2) < "> temperature (B2) >

The film-shaped fired material of the second embodiment satisfies the relationship of A2 < B2 < A2+60 ℃ in the temperature range of 25 ℃ to 400 ℃ in the thermogravimetric curve (TG curve) measured at the temperature rise rate of 10 ℃/min under a nitrogen atmosphere at the temperature (A2) at which the negative slope is the largest and in the differential thermal analysis curve (DTA curve) measured at the temperature rise rate of 10 ℃/min under a nitrogen atmosphere at which alumina particles are used as a reference sample.

The TG curve shows the change in weight of the film-shaped fired material during the heat treatment of the film-shaped fired material in the nitrogen atmosphere.

The DTA curve shows a differential thermal change of the film-shaped fired material in the process of heat-treating the film-shaped fired material in a nitrogen atmosphere.

Hereinafter, the form of the film-shaped fired material during firing estimated from the TG curve and the DTA curve obtained by measurement in a nitrogen atmosphere will be described with reference to the drawings as appropriate.

Fig. 2 is a cross-sectional view schematically showing the estimated forms of the film-like sintered material 1 before (fig. 2 (a)), during (fig. 2 (B)), and after (fig. 2 (c)) sintering, which satisfy the relationship of a2 < B2 < a2+60 ℃.

The weight of the binder component 20 contained in the film-like sintered material (fig. 2 (a)) before sintering is reduced by heating (fig. 2 (b) to (c)), and this phenomenon appears as a negative slope in the TG curve.

The binder component 20 contained in the film-shaped fired material before firing (fig. 2 (a)) is thermally decomposed by absorbing heat during heating, and the sinterable metal particles 10 contained in the film-shaped fired material before firing (fig. 2 (a)) are melted by absorbing heat during heating (fig. 2 (b)), and then fired while being released from heat (fig. 2 (c)). The heat absorption and release process is observed as a DTA curve, and when the sintering process is sufficiently performed, the heat release amount is large and far exceeds the heat absorption amount by the thermal decomposition of the binder component 20 contained in the film-like sintered material (fig. 2 (a)) and the melting of the sinterable metal particles 10. That is, only positive differential heat due to heat release was observed in the DTA curve obtained by the measurement, and the curve appeared as a peak.

It is considered that the temperature (a2) and the temperature (B2) satisfying the relationship of a2 < B2 < a2+60 ℃ means that the melting and sintering of the sinterable metal particles are completed at the heating temperature immediately following the decrease in the binder component. It is generally known that the firing temperature is related to the size of the metal particles, and the smaller the metal particles, the lower the firing temperature tends to be. Therefore, it is estimated that the film-like sintered material 1 satisfying the relationship of a2 < B2 < a2+60 ℃ does not show the aggregation or fusion of the sinterable metal particles at the start of sintering, and sinterable metal particles 10m which are directly melted in fine particles are sintered.

FIG. 3 is a cross-sectional view schematically showing the estimated forms of the fired material 1c before firing (FIG. 3 (a)), during firing (FIG. 3 (B)), and after firing (FIG. 3 (c)) which do not satisfy the relationship of A2 < B2 < A2+60 ℃ and in which the temperature of B2 is higher than A2+60 ℃. The weight of the binder component 21 contained in the film-like sintered material (fig. 3 (a)) before sintering is also reduced by heating (fig. 3 (b) to (c)), and this phenomenon is also expressed as a negative slope in the TG curve.

The binder component 21 contained in the film-shaped fired material before firing (fig. 3 (a)) is also thermally decomposed by absorbing heat during heating, and thereafter, the sinterable metal particles 11 contained in the film-shaped fired material before firing (fig. 3 (a)) are melted by the absorption of heat and sintered by the release of heat ((c) of fig. 3). In the heat absorption and release process of the sinterable metal particles 11, the binder component 21 is not present or is present in a trace amount if present, and therefore, although the heat absorption and release process occurs almost simultaneously, the heat release amount by sintering is large, and therefore, only a positive peak indicating the heat release process appears in the DTA curve.

The relationship that the temperature (a2) and the temperature (B2) do not satisfy a2 < B2 < a2+60 ℃ is considered to mean that the sintering of the sinterable metal particles is not completed at the heating temperature immediately after the decrease of the binder component. The firing temperature is related to the size of the metal particles, and tends to be higher as the metal particles are larger. Therefore, for example, it is assumed that the sinterable metal particles in the fired material 1c having a temperature of B2 higher than A2+60 ℃ do not satisfy the relationship of A2 < B2 < A2+60 ℃ at the sintering stage, and have a large size. This is considered to be largely because the reduction of the binder component by heating is performed before the melting and sintering peaks of the sinterable metal particles, and therefore, at the sintering start stage, the sinterable metal particles 11 form blocks of a certain size, and the metal particles in the blocks are sintered, thereby raising the temperature (B2).

The inventors of the present application have also found that a film-like fired material having a temperature (a2) and a temperature (B2) satisfying the relationship of a2 < B2 < a2+60 ℃ is excellent in shear adhesion after firing.

It is considered that in a fired material which does not satisfy the relationship of a2 < B2 < a2+60 ℃ and in which the temperature of B2 is higher than a2+60 ℃, the sintered metal particles in a lump form are sintered, and therefore, the sintering is insufficient, or a large number of unsintered portions remain, and the bond strength (shear bond strength) of the sintered material is insufficient. Alternatively, it is considered that voids are likely to be generated at the adhesion interface with the adherend, and the adhesion area is reduced, thereby reducing the adhesion strength.

In contrast, it is considered that a film-like sintered material satisfying the relationship of a2 < B2 < a2+60 ℃ sinters sinterable metal particles directly melted in fine particles, and therefore the sinterable metals form metal bonds uniformly close to each other, resulting in an improvement in the adhesive strength of the sintered material.

The shear adhesion of the film-shaped fired material after firing can be measured by the method described in examples.

The temperature (a2) and the temperature (B2) of the film-like sintered material according to the second embodiment satisfy the relationship of a2 < B2 < a2+60 ℃, for example, may satisfy the relationship of a2 < B2 < a2+50 ℃, may satisfy the relationship of a2 < B2 < a2+40 ℃, or may satisfy the relationship of a2 < B2 < a2+30 ℃.

In a differential thermal analysis curve (DTA curve) in which alumina particles are used as a reference sample and are measured at a temperature rise rate of 10 ℃/min under a nitrogen atmosphere, the peak temperature (B2) in the temperature range of 25 ℃ to 400 ℃ preferably has a peak temperature within the range of 200 ℃ to 400 ℃, more preferably has a peak temperature within the range of 220 ℃ to 390 ℃, and still more preferably has a peak temperature within the range of 250 ℃ to 380 ℃.

< temperature (A2 ') > "temperature (B2') >)

In the film-shaped fired material of the second embodiment, it is preferable that the peak temperature (B2 ') observed at the lowest temperature among the temperatures (a 2') at the maximum negative slopes in the thermogravimetric curve (TG curve) measured at the temperature increase rate of 10 ℃/min under a nitrogen atmosphere for the components other than the sinterable metal particles in the film-shaped fired material and the peaks observed in the temperature range of 200 to 400 ℃ in the differential thermal analysis curve (DTA curve) measured at the temperature increase rate of 10 ℃/min under a nitrogen atmosphere using alumina particles as a reference sample for the sinterable metal particles satisfy the relationship of B2 '< a 2'.

The above-mentioned TG curve shows the weight change of the components other than the above-mentioned sinterable metal particles in the film-like sintered material during the heat treatment for sintering in a nitrogen atmosphere.

The DTA curve shows a temperature change of differential heat of the sinterable metal particles during the heat treatment performed as firing in a nitrogen atmosphere.

In the film-like sintered material of the second embodiment when the film-like sintered material of the second embodiment contains non-sinterable metal particles, the peak temperature (B2 ') observed at the lowest temperature preferably satisfies the relationship of B2' < a2 'among the temperatures (a 2') at the maximum negative slopes in the thermogravimetric curve (TG curve) measured at the temperature increase rate of 10 ℃/min under nitrogen atmosphere for the components other than the sinterable metal particles and the non-sinterable metal particles in the film-like sintered material, and the peaks observed in the temperature range of 200 to 400 ℃ in the differential thermal analysis curve (DTA curve) measured at the temperature increase rate of 10 ℃/min under nitrogen atmosphere with alumina particles as reference samples for the sinterable metal particles and the non-sinterable metal particles.

The phenomenon is expressed as a negative slope in the TG curve, in which the weight of components other than the sintered metal particles and the non-sintered metal particles in the film-shaped sintered material containing the binder component, which are contained in the film-shaped sintered material before sintering, is reduced by heating in a nitrogen atmosphere.

The sinterable metal particles contained in the film-like sintered material before firing are melted and sintered by heating in a nitrogen atmosphere, and the melting phenomenon appears as a negative peak in the DTA curve and the sintering phenomenon appears as a positive peak in the DTA curve.

It is considered that the relationship that the temperature (a2 ') and the temperature (B2') satisfy B2 '< a 2' means that the melting and sintering of the sinterable metal particles start earlier than the timing at which the weight of the components of the film-like sintering material distributed around the sinterable metal particles decreases during the heat treatment. Therefore, the film-like firing materials satisfying the relationship of B2 ' < a2 ' are in a state of being isolated from each other by the components distributed around the sinterable metal particles, and are easily melted directly in fine particles, and at the time point when the temperature reaches (a2 '), the collision frequency thereof is sharply increased, and the sinterable metal particles melted directly in fine particles are easily sintered to each other. As a result, it is considered that in the film-like sintered material satisfying the relationship of B2 '< a 2', the sinterable metals form metal bonds uniformly close to each other, and the adhesive strength of the sintered material is improved.

The temperature (a2 ') and the temperature (B2') can be determined from the TG curve and the DTA curve for each separated sample by separating the sinterable metal particles and the components other than the sinterable metal particles from the film-like sintered material before firing.

The separation of the sinterable metal particles and the remaining components other than the sinterable metal particles in the film-like sintered material before firing can be performed by, for example, the following method.

First, a film-shaped firing material before firing is mixed with a sufficient amount of an organic solvent, and then the mixture is allowed to stand for a sufficient time until the sinterable metal particles settle. The supernatant liquid is taken out by a syringe or the like, and the residue after drying at 120 ℃ for 10 minutes is collected, whereby components other than the sinterable metal particles can be separated from the film-like sintered material. Further, a sufficient amount of the organic solvent is mixed again into the solution containing the sinterable metal particles after the supernatant liquid is taken out by the above-mentioned syringe or the like, and then the mixture is left to stand for a sufficient time until the sinterable metal particles settle, and the supernatant liquid is taken out by the syringe or the like.

The mixing and standing of the organic solvent and the removal of the supernatant were repeated 5 or more times, and the residue obtained by drying the residual liquid at 120 ℃ for 10 minutes was recovered, whereby sinterable metal particles could be separated.

This is the same in the case where the film-shaped sintered material of the second embodiment contains non-sinterable metal particles, and the temperature (a2 ') and the temperature (B2') can be determined from the TG curve and the DTA curve for each of the separated samples by separating the sinterable metal particles and the non-sinterable metal particles, and components other than the sinterable metal particles and the non-sinterable metal particles, from the film-shaped sintered material before firing.

The separation of the sinterable metal particles and non-sinterable metal particles in the film-like sintered material before firing and the remaining components other than the sinterable metal particles and non-sinterable metal particles can be performed by, for example, the following method.

First, a film-shaped firing material before firing is mixed with a sufficient amount of an organic solvent, and then the mixture is allowed to stand for a sufficient time until the sinterable metal particles and non-sinterable metal particles settle. The components other than the sinterable metal particles and non-sinterable metal particles can be separated from the film-like sintered material by taking out the supernatant liquid with a syringe or the like and recovering the residue after drying at 120 ℃ for 10 minutes. Further, a sufficient amount of the organic solvent is mixed again into the solution containing the sinterable metal particles and the non-sinterable metal particles after the supernatant liquid is taken out by the above-mentioned syringe or the like, and then the mixture is left to stand for a sufficient time until the sinterable metal particles and the non-sinterable metal particles settle, and the supernatant liquid is taken out by the syringe or the like. The mixing and standing of the organic solvent and the removal of the supernatant are repeated 5 or more times, and the residue obtained by drying the residual liquid at 120 ℃ for 10 minutes is recovered, whereby sinterable metal particles and non-sinterable metal particles can be separated.

The solvent used here is capable of dissolving the binder component, and is preferably capable of being volatilized under the drying conditions of 120 to 250 ℃ for 10 minutes, and the preferred solvent may be appropriately used depending on the kind of the binder component and the like. Examples thereof include hydrocarbons such as toluene and xylene; alcohols such as methanol, ethanol, 2-propanol, isobutanol (2-methylpropane-1-ol), and 1-butanol; esters such as ethyl acetate; ketones such as acetone and methyl ethyl ketone; ethers such as tetrahydrofuran; amides (compounds having an amide bond) such as dimethylformamide and N-methylpyrrolidone.

< endothermic peak >

In the film-like fired material of the second embodiment, it is preferable that the film-like fired material does not have an endothermic peak in a temperature range of 25 to 400 ℃ in a differential thermal analysis curve (DTA curve) measured at a temperature increase rate of 10 ℃/minute in a nitrogen atmosphere using alumina particles as a reference sample.

the DTA curve indicates a temperature change of the film-like sintered material as a difference heat in the process of heating the film-like sintered material by sintering.

When an endothermic peak is observed in the DTA curve, it is considered that the film-shaped fired material contains a component having a property of changing (for example, evaporating) by absorbing heat from the film-shaped fired material at 25 to 400 ℃. That is, it is considered that evaporation of the components occurs, and evaporation heat associated therewith is required. Or a component which is thermally decomposed by absorbing heat in a large amount, and which exceeds the amount of heat released by sintering.

Therefore, it is preferable that the film-shaped fired material of the second embodiment contains a component having a property of evaporating from the film-shaped fired material at 25 to 400 ℃ in a small amount or does not contain such a component. In addition, it is preferable that the content of a component which absorbs much heat in thermal decomposition and interferes with the exothermic process based on sintering is small or not.

Here, before the DTA curve is measured for the film-shaped fired material, the film-shaped fired material is subjected to pretreatment such as drying, and it is recommended that moisture absorbed as impurities is not measured. The drying conditions include 110 ℃ for 4 minutes.

In the DTA curve, since there is no endothermic peak in the temperature range of 25 to 400 ℃, the components distributed around the sintered metal particles are not reduced, and the particles are easily isolated from each other by the components distributed around the sintered metal particles. As a result, in the film-like sintered material having no endothermic peak in the temperature range of 25 to 400 ℃ in the DTA curve, the sinterable metals form uniformly close metal bonds with each other, and the strength of the sintered material is likely to be improved. Further, the loss of energy required for firing is reduced, and firing in a favorable environment can be achieved. Further, it is considered that the shear adhesion of the film-like fired material after firing is improved.

The film-shaped fired material according to the second embodiment has excellent thickness stability because it is in a film shape. In addition, the film-like firing material of the second embodiment contains the sinterable metal particles, and therefore has excellent thermal conductivity. Furthermore, the film-like fired material of the second embodiment satisfies the relationship of A2 < B2 < A2+60 ℃, and exhibits excellent shear adhesion after firing.

Method for producing film-like fired Material

The film-like fired material can be formed using a fired material composition containing the constituent materials.

For example, a film-shaped binder can be formed at a target site by applying a firing material composition containing components constituting the film-shaped firing material and a solvent to a surface to be formed with the film-shaped firing material, drying the composition as needed, and volatilizing the solvent.

The solvent is preferably a solvent having a boiling point of less than 250 ℃ and more preferably a solvent having a boiling point of less than 200 ℃, and examples thereof include n-hexane (boiling point: 68 ℃), ethyl acetate (boiling point: 77 ℃), 2-butanone (boiling point: 80 ℃), n-heptane (boiling point: 98 ℃), methylcyclohexane (boiling point: 101 ℃), toluene (boiling point: 111 ℃), acetylacetone (boiling point: 138 ℃), n-xylene (boiling point: 139 ℃), dimethylformamide (boiling point: 153 ℃) and butyl carbitol (boiling point: 230 ℃). These solvents may be used alone, or may also be used in combination.

The surface to be formed of the film-like fired material may be the surface of a release film.

The coating of the fired material composition may be carried out by a known method, and examples thereof include methods using various coaters such as a knife coater, a blade coater, a bar coater, a gravure coater, a roll coater, a Comma (registered trademark) coater, a roll coater, a curtain coater, a die coater, a knife coater, a screen coater, a meyer bar coater, and a kiss coater.

The drying conditions for the fired material composition are not particularly limited, but when the fired material composition contains a solvent, it is preferably dried by heating, and in this case, it is preferably dried at 70 to 250 ℃, for example, 80 to 180 ℃ for 10 seconds to 10 minutes.

Film-like fired Material with supporting sheet