Thermosetting sheets and dicing die bond films

Abstract

To provide a thermosetting sheet which can comparatively suppress peeling of a semiconductor element and has comparatively high heat radiation property after curing, and a dicing die-bonding film.SOLUTION: In a dicing die-bonding film 20 having a base material layer 1, a dicing tape 10 in which an adhesive layer 2 is laminated on the base material layer and a thermosetting sheet 3 laminated on the adhesive layer of the dicing tape 10, the thermosetting sheet contains a thermosetting resin, a thermoplastic resin, and conductive particles. The conductive particles contain silver particles having an average particle diameter D50 of 0.01 μm or more and 10 μm or less and circularity in a cross section of 0.7 or more, and have viscosity at 100°C of 20 kPa s or more and 3,000 kPa s or less.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a thermosetting sheet and a dicing die bond film. [Background technology]

[0002] 2. Description of the Related Art Conventionally, in the manufacture of semiconductor devices, a method for bonding a semiconductor element to an adherend such as a metal lead frame (die bonding method) has been known in which a thermosetting sheet is used (for example, Patent Document 1). Patent Document 1 discloses a thermosetting sheet that contains conductive particles and a thermosetting resin.

[0003] In such a method, for example, a thermosetting sheet is attached to one side of a semiconductor wafer (the side opposite to the circuit-forming surface), and the semiconductor wafer and the thermosetting sheet are diced to obtain a plurality of thermosetting sheets each having a semiconductor element attached to one side. The thermosetting sheet having the semiconductor element attached to one side thereof is temporarily attached to an adherend such as a metal lead frame at a predetermined temperature (e.g., 70° C.) on the other side thereof, and then is thermally cured at a higher temperature (e.g., 200° C.) to be bonded to the adherend. In other words, the semiconductor element is bonded to the adherend with the thermosetting sheet interposed therebetween. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2019-21813 A Summary of the Invention [Problem to be solved by the invention]

[0005] However, when a thermosetting sheet having a semiconductor element attached to one side thereof is adhered to the adherend, the semiconductor element may peel off from the thermosetting sheet. If such peeling occurs, electrical conduction and thermal conduction via the conductive particles become insufficient, which is undesirable. The above-described peeling occurs more significantly when the semiconductor wafer and the thermosetting sheet are diced (the semiconductor element is more likely to fly off the thermosetting sheet). However, it cannot be said that sufficient research has been conducted yet on preventing the peeling of the semiconductor element from the thermosetting sheet.

[0006] Furthermore, when a power semiconductor element is used in a semiconductor device, the power semiconductor element is used at a large power of several MVA or more, and generates a large amount of heat. Therefore, when the above-mentioned thermosetting sheet is used for a power semiconductor element, it is preferable that the thermosetting sheet after being adhered to an adherend, that is, the thermosetting sheet after being cured, has high heat dissipation properties.

[0007] Although the above-mentioned heat generation problem occurs similarly when semiconductor elements other than power semiconductor elements are used, it cannot be said that sufficient research has yet been conducted into improving the heat dissipation properties of the thermosetting sheet after curing.

[0008] Therefore, an object of the present invention is to provide a thermosetting sheet that can relatively suppress peeling of a semiconductor element and has relatively high heat dissipation properties after curing, and a dicing die bond film that includes the thermosetting sheet. [Means for solving the problem]

[0009] As a result of intensive research by the present inventors, it has been found that the thermosetting sheet contains a thermosetting resin, a thermoplastic resin, and conductive particles, and the conductive particles have an average particle diameter D 50The inventors have discovered that by making the thermosetting sheet contain silver particles having a diameter of 0.01 μm or more and 10 μm or less and a cross-sectional circularity of 0.7 or more, and further making the viscosity of the thermosetting sheet 20 kPa·s or more and 3000 kPa·s or less at 100°C, peeling of the semiconductor element is relatively suppressed and the heat dissipation properties after curing are relatively high, which has led to the invention.

[0010] That is, the thermosetting sheet according to the present invention is A thermosetting sheet comprising a thermosetting resin, a thermoplastic resin, and conductive particles, The conductive particles have an average particle diameter D 50 The silver particles have a diameter of 0.01 μm or more and 10 μm or less and a circularity of 0.7 or more in cross section, The viscosity at 100°C is 20 kPa s or more and 3000 kPa s or less.

[0011] According to this configuration, the conductive particles have an average particle diameter D 50 Since the resin contains silver particles having a size of 10 μm or less, the outer surfaces of the silver particles can be melted to a degree that allows sintering at a temperature (for example, 200° C.) sufficient to cure the thermosetting resin. The average particle diameter D of the silver particles 50 is 0.01 μm or more, the silver particles are relatively easily dispersed in the thermosetting sheet. In addition, the specific surface area of ​​the silver particles is prevented from becoming excessively large, which would make the surfaces of the silver particles more susceptible to oxidation, thereby ensuring sufficient electrical conductivity for the silver particles. This allows the outer surfaces of the silver particles to be melted to a degree that allows them to be sintered while still having sufficient conductivity and being sufficiently dispersed, so that the conductive particles can be sintered together by the silver particles. In addition, since the circularity of the silver particles in the cross section is 0.7 or more, the silver particles can be more thoroughly dispersed in the thermosetting sheet, and therefore the conductive particles can be sintered together by the silver particles thoroughly dispersed in the thermosetting sheet. As a result, after curing, the thermosetting sheet according to the present invention has high heat dissipation properties while maintaining sufficient electrical conductivity. Furthermore, since the viscosity at 100°C is 20 kPa·s or more and 3000 kPa·s or less, the wettability to an adherend (e.g., a semiconductor wafer) can be improved, thereby ensuring relatively sufficient adhesion to the adherend. Furthermore, since it contains a thermoplastic resin, the viscosity at 100°C can be relatively easily adjusted to be within the above numerical range, and it can also have relatively low elasticity after curing. Therefore, peeling of the semiconductor element can be relatively suppressed. As described above, the thermosetting sheet according to the present invention can relatively prevent peeling of the semiconductor element, and has relatively high heat dissipation properties after curing.

[0012] In the thermosetting sheet, It is preferable that the particle filling rate P of the conductive particles in the thermosetting sheet after curing is 30 volume % or more.

[0013] According to this configuration, the heat dissipation property of the thermosetting sheet after curing can be further improved.

[0014] In the thermosetting sheet, It is preferable that the thermal conductivity after curing is 3 W / m·K or more.

[0015] With this configuration, the electrical conductivity of the thermosetting sheet after curing can be further increased.

[0016] In the thermosetting sheet, It is preferable that the peeling force against a silicon wafer at room temperature is 1 N / 10 mm or more.

[0017] With this configuration, peeling of the semiconductor element can be further suppressed.

[0018] In the thermosetting sheet, Contains volatile components, The volatile component preferably contains one or more hydroxyl groups and has a boiling point of 250° C. or higher.

[0019] According to this configuration, the heat dissipation property of the thermosetting sheet after curing can be further improved.

[0020] In the thermosetting sheet, The volatile component is preferably a terpene compound.

[0021] According to this configuration, the heat dissipation property of the thermosetting sheet after curing can be further improved.

[0022] The dicing die bond film according to the present invention is A base layer; a dicing tape having a pressure-sensitive adhesive layer laminated on the base layer; a thermosetting sheet laminated on the adhesive layer of the dicing tape; The thermosetting sheet is any one of the thermosetting sheets described above.

[0023] According to such a configuration, the dicing die bond film can relatively suppress peeling of the semiconductor element, and is provided with a thermosetting sheet that has relatively high heat dissipation properties after curing. Effect of the Invention

[0024] According to the present invention, it is possible to provide a thermosetting sheet that can relatively suppress peeling of a semiconductor element and has relatively high heat dissipation properties after curing, and a dicing die bond film that includes the thermosetting sheet. [Brief description of the drawings]

[0025] [Figure 1] 1 is a cross-sectional view showing a configuration of a dicing die bond film according to one embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0026] Hereinafter, one embodiment of the present invention will be described.

[0027] [Thermosetting sheet] The thermosetting sheet according to this embodiment contains a thermosetting resin, a thermoplastic resin, and conductive particles. In this specification, the conductive particles refer to particles having an electrical conductivity of 100 μS / cm or less as measured in accordance with JIS K 0130 (2008).

[0028] The mass % of the thermosetting resin in 100 mass % (mass parts) of the thermosetting sheet is preferably 1 mass % or more and 30 mass % or less, and more preferably 3 mass % or more and 15 mass % or less. The mass % of the thermoplastic resin in 100 mass % of the thermosetting sheet is preferably 0.5 mass % or more and 10 mass % or less, and more preferably 1 mass % or more and 7 mass % or less. The mass % of the conductive particles in 100 mass % of the thermosetting sheet is preferably 60 mass % or more and 95 mass % or less, and more preferably 80 mass % or more and 93 mass % or less. The mass proportion of the thermosetting resin in 100 mass% of resins (thermosetting resin and thermoplastic resin) is preferably 30 mass% or more and 90 mass% or less, and more preferably 50 mass% or more and 80 mass% or less.

[0029] Examples of the thermosetting resin include epoxy resin, phenol resin, amino resin, unsaturated polyester resin, polyurethane resin, silicone resin, and thermosetting polyimide resin, etc. Among these, it is preferable to use epoxy resin.

[0030] Examples of epoxy resins include bisphenol A type, bisphenol F type, bisphenol S type, brominated bisphenol A type, hydrogenated bisphenol A type, bisphenol AF type, biphenyl type, naphthalene type, fluorene type, phenol novolac type, cresol novolac type, orthocresol novolac type, trishydroxyphenylmethane type, tetraphenylolethane type, hydantoin type, trisglycidyl isocyanurate type, and glycidylamine type epoxy resins. Among these, it is preferable to use at least one of bisphenol A type epoxy resin and cresol novolac type epoxy resin, and it is more preferable to use a combination of bisphenol A type epoxy resin and cresol novolac type epoxy resin. The bisphenol A type epoxy resin includes an aliphatic modified bisphenol A type epoxy resin.

[0031] Examples of phenolic resins as a curing agent for epoxy resins include novolac-type phenolic resins, resol-type phenolic resins, biphenyl-type phenolic resins, and polyoxystyrenes such as polyparaoxystyrene. Among the above phenolic resins, it is preferable to use biphenyl-type phenolic resins.

[0032] In addition, as the thermosetting resin, a thermoplastic resin having a thermosetting functional group can also be used. As the thermoplastic resin having a thermosetting functional group, for example, a thermosetting functional group-containing acrylic resin can be mentioned. As the acrylic resin in the thermosetting functional group-containing acrylic resin, a monomer unit derived from a (meth)acrylic acid ester can be mentioned. In the case of a thermoplastic resin having a thermosetting functional group, a curing agent is selected depending on the type of the thermosetting functional group.

[0033] The thermoplastic resin functions as a binder. Since the thermosetting sheet according to this embodiment contains a thermoplastic resin as a binder, the viscosity of the thermosetting sheet at 100°C can be relatively easily adjusted to be in the range of 20 kPa s to 3000 kPa s, as described below. Examples of the thermoplastic resin include natural rubber, butyl rubber, isoprene rubber, chloroprene rubber, ethylene-vinyl acetate copolymer, ethylene-acrylic acid copolymer, ethylene-acrylic acid ester copolymer, polybutadiene resin, polycarbonate resin, thermoplastic polyimide resin, polyamide resin such as polyamide 6 and polyamide 6,6, phenoxy resin, acrylic resin, saturated polyester resin such as PET and PBT, polyamideimide resin, fluororesin, etc. Only one type of the thermoplastic resin may be used, or two or more types may be used in combination. As the thermoplastic resin, acrylic resin is preferable from the viewpoint that it has a small amount of ionic impurities and has high heat resistance, so that it is easy to ensure the connection reliability by the thermosetting sheet.

[0034] The acrylic resin is preferably a polymer containing a monomer unit derived from a (meth)acrylic acid ester as the monomer unit having the largest mass ratio. Examples of the (meth)acrylic acid ester include an alkyl (meth)acrylic acid ester, a cycloalkyl (meth)acrylic acid ester, and an aryl (meth)acrylic acid ester. The acrylic resin may contain a monomer unit derived from another component copolymerizable with the (meth)acrylic acid ester. Examples of the other component include a functional group-containing monomer such as a carboxyl group-containing monomer, an acid anhydride monomer, a hydroxyl group-containing monomer, a glycidyl group-containing monomer, a sulfonic acid group-containing monomer, a phosphoric acid group-containing monomer, an acrylamide, and an acrylonitrile, and various polyfunctional monomers. The acrylic resin is preferably a carboxyl-containing acrylic rubber.

[0035] The conductive particles have an average particle diameter D 50The silver particles have a diameter of 0.01 μm or more and 10 μm or less and a circularity of 0.7 or more in a cut section in the thickness direction. The conductive particles have an average particle diameter D 50 By including silver particles having a size of 10 μm or less, the outer surfaces of the silver particles can be melted to a degree that allows sintering at a temperature (e.g., 200° C.) sufficient to cure the thermosetting resin. The average particle diameter D of the silver particles 50 When the specific surface area of ​​the silver particles is 0.01 μm or more, the silver particles can be dispersed relatively easily in the thermosetting sheet. In addition, the specific surface area of ​​the silver particles can be prevented from becoming excessively large, which would make the surfaces of the silver particles more susceptible to oxidation, thereby ensuring sufficient electrical conductivity for the silver particles. This allows the outer surfaces of the silver particles to be melted to a degree that allows them to be sintered while still having sufficient conductivity and remaining relatively dispersed, thereby allowing the silver particles to sinter the conductive particles together (or to sinter the silver particles together if the conductive particles are only silver particles). In addition, since the circularity of the silver particles in cross section is 0.7 or more, the silver particles can be more thoroughly dispersed in the thermosetting sheet, and therefore the conductive particles can be sintered together (if the conductive particles are only silver particles, then the silver particles can be sintered together) by the silver particles thoroughly dispersed in the thermosetting sheet. As a result, after curing, the thermosetting sheet according to the present invention has high heat dissipation properties while maintaining sufficient electrical conductivity.

[0036] The average particle diameter D of the silver particles 50 is preferably 0.1 μm or more and 5 μm or less, and more preferably 0.5 μm or more and 2 μm or less. In addition, the circularity of the silver particles in a cross section taken along the thickness direction is preferably 0.8 or more. The upper limit of the circularity is 1.

[0037] Average particle size of silver particles D 50can be measured on a volume basis using, for example, a laser diffraction / scattering type particle size distribution measuring device (Microtrac MT3000II series, manufactured by Microtrac Bell).

[0038] Circularity is an index that determines the complexity of a shape based on the area and perimeter values. Circularity is calculated as 4πS / L, where S is the area and L is the perimeter. 2 A circularity value of 1 results in a perfect circle, and the smaller the circularity value is below 1, the further away the shape becomes from a circle. The circularity can be obtained by cutting the thermosetting sheet in the thickness direction, taking an SEM image of the cut surface, and analyzing the SEM image using a powder image analyzer (PITA-3, manufactured by Seishin Enterprise Co., Ltd.) (specifically, by analyzing it with image analysis software such as "Image J"). Analysis using the powder image analyzer is performed on 10 randomly selected silver particles in the SEM image, and the circularity can be calculated by taking the arithmetic average of the circularity values ​​obtained for the 10 silver particles. In addition, when the thermosetting sheet contains conductive particles other than silver particles, the silver particles can be distinguished from the conductive particles other than silver particles by observing the reflected electron images so that light and dark appear due to differences in composition.

[0039] The silver particles may be silver particles composed of silver element and other elements (metal elements, etc.) contained as unavoidable impurity elements, or may be silver particles that have been subjected to a surface treatment (for example, silane coupling treatment). Examples of the surface treatment agent for silver particles include fatty acid-based, amine-based, and epoxy-based coating agents. Examples of silver particles surface-treated with a fatty acid-based coating agent include HP02 and HP02A manufactured by Mitsui Mining & Smelting Co., Ltd., and examples of silver particles treated with an epoxy-based coating agent include a modified coating agent (epoxy-coated product) of HP02A manufactured by Mitsui Mining & Smelting Co., Ltd. In the thermosetting sheet according to the present embodiment, it is preferable to use silver particles surface-treated with an epoxy-based coating agent. As described above, the thermosetting sheet according to the present embodiment contains a thermosetting resin. Therefore, when silver particles surface-treated with an epoxy-based coating agent are used as silver particles, the silver particles show a relatively high affinity with the thermosetting resin in the thermosetting sheet, and are more easily dispersed in the thermosetting sheet. And, since the silver particles are more easily dispersed in the thermosetting sheet, the heat conductivity (heat dissipation) of the thermosetting sheet can be improved because the silver particles can be contained in a larger amount in the thermosetting sheet. In addition, when the surface treatment agent of the silver particles is an epoxy-based coating agent, the thermosetting resin contained in the thermosetting sheet is preferably an epoxy resin. In this way, the affinity between the silver particles and the thermosetting resin can be further increased, so that the silver particles can be further dispersed in the thermosetting sheet. As a result, the heat conductivity (heat dissipation) of the thermosetting sheet can be further improved.

[0040] The conductive particles may include, in addition to silver particles, nickel particles, copper particles, aluminum particles, carbon black, carbon nanotubes, particles in which the surface of a metal particle serving as a core (nucleus) is plated with a metal such as gold or silver (hereinafter also referred to as plated metal particles), and particles in which the surface of a resin particle serving as a core (nucleus) is coated with a metal (hereinafter also referred to as metal-coated resin particles), etc. Only one of these conductive particles may be used, or two or more types may be used in combination.

[0041] As the plated metal particles, for example, particles having a nickel particle or copper particle as a core, the surface of which is plated with a noble metal such as gold or silver, can be used. As the metal-coated resin particles, for example, particles having a resin particle as a core, the surface of which is coated with a metal such as nickel or gold, can be used. When the thermosetting sheet according to the present embodiment contains conductive particles other than silver particles, it is preferable to use plated metal particles as the conductive particles, and it is preferable to use particles (silver-coated copper particles) in which a copper particle is used as a core and the surface of the core is plated with silver as the plated metal particles. Commercially available products of silver-coated copper particles include 1200YP (trade name) manufactured by Mitsui Mining & Smelting Co., Ltd. and AOP-TCY-2(EN) (trade name) manufactured by DOWA Electronics Co., Ltd. When the thermosetting sheet according to this embodiment contains conductive particles other than silver particles, the mass percentage of silver particles in 100 mass% of the conductive particles is preferably 10 mass% or more and 95 mass% or less, and more preferably 20 mass% or more and 90 mass% or less.

[0042] The shape of the conductive particles other than silver may be, for example, flake-shaped, needle-shaped, filament-shaped, spherical, or flat (including scale-shaped), but among these, flat particles are preferred from the viewpoint of increasing the contact area with the silver particles due to the large specific surface area. The above-mentioned product name 1200YP manufactured by Mitsui Smelting & Co., Ltd. is a flat conductive particle.

[0043] Conductive particles other than silver particles have an average particle diameter D 50 is preferably 0.01 μm or more and 20 μm or less, and more preferably 0.05 μm or more and 10 μm or less. Average particle size D of conductive particles other than silver particles 50 The average particle diameter D of the silver particles mentioned above 50 It can be measured in the same manner as above.

[0044] The thermosetting sheet according to the present embodiment may contain a thermosetting catalyst in order to sufficiently advance the curing reaction of the resin component and to increase the curing reaction rate. Examples of the thermosetting catalyst include imidazole-based compounds, triphenylphosphine-based compounds, amine-based compounds, and trihalogen borane-based compounds.

[0045] The thermosetting sheet according to this embodiment has a viscosity at 100° C. of 20 kPa·s or more and 3000 kPa·s or less. By ensuring that the viscosity at 100°C is 20 kPa·s or more and 3000 kPa·s or less, the wettability to an adherend (e.g., a semiconductor wafer) can be improved, thereby ensuring relatively sufficient adhesion to the adherend. Therefore, peeling of the semiconductor element can be relatively suppressed. In particular, when the thermosetting sheet is attached to one side of a semiconductor wafer and diced to obtain multiple thermosetting sheets with semiconductor elements attached to one side, peeling of the semiconductor elements from the thermosetting sheet can be relatively suppressed.

[0046] The viscosity at 100° C. can be evaluated using a rheometer (HAAKE MARS rotational rheometer manufactured by Thermo Fisher Scientific Co., Ltd.) Specifically, the viscosity can be obtained by reading the indicated value at 100° C. when the temperature is increased from 30° C. to 180° C. at a rate of 10° C. / min.

[0047] The thermosetting sheet according to this embodiment may contain a volatile component. The thermosetting sheet according to this embodiment preferably contains 5% by mass or more and 50% by mass or less of the volatile components relative to the total mass of the organic components (thermosetting resin, thermoplastic resin, volatile components) contained in the thermosetting sheet, and more preferably contains 10% by mass or more and 40% by mass or less of the volatile components. The volatile component may be an organic compound having one or more hydroxyl groups and a boiling point of 250°C or higher. The boiling point of the organic compound is preferably 350°C or lower. Such an organic compound may be a terpene compound. Among terpene compounds, the volatile component is preferably isobornylcyclohexanol represented by the following formula (1). Isobornylcyclohexanol is an organic compound having a boiling point of 308 to 318°C. When heated from room temperature (23±2°C) to 600°C under a nitrogen gas flow of 200mL / min and at a temperature increase rate of 10°C / min, it has the property of undergoing a large weight loss from 100°C or higher and volatilizing and disappearing at 245°C (no further weight loss is observed). It also has the property of exhibiting an extremely high viscosity of 1,000,000 mPa·s at 25°C, but a relatively low viscosity of 1,000 mPa·s or lower at 60°C. The weight loss is a value when the weight loss rate at the measurement start temperature (room temperature) is set to 0%. Thus, isobornylcyclohexanol exhibits extremely high viscosity at 25° C. as described above, and is therefore capable of maintaining a sheet shape at room temperature, but exhibits relatively low viscosity at 60° C. as described above, and thus becomes tacky. In other words, a thermosetting sheet containing isobornylcyclohexanol exhibits excellent sheet shape retention at room temperature, and becomes tacky at temperatures of 60° C. or higher. Here, when mounting a semiconductor element attached to one side of a thermosetting sheet on a metal lead frame or the like, the semiconductor element is usually temporarily attached (temporarily fixed) to an adherend such as a metal lead frame via the thermosetting sheet at a temperature of 60 to 80° C., but since isobornylcyclohexanol has tackiness at 60° C. or higher as described above, when the thermosetting sheet according to this embodiment contains isobornylcyclohexanol as a volatile component, the thermosetting sheet has improved temporary adhesion to an adherend such as a metal lead frame. In other words, in the temporarily attached state, the mounting position of the semiconductor element is not shifted and the thermosetting sheet is prevented from lifting off the adherend. Therefore, when the thermosetting sheet is thermally cured to bond the semiconductor element to the adherend, the semiconductor element can be bonded to the adherend with high reliability.

[0048] [ka]

[0049] In the thermosetting sheet according to this embodiment, the particle filling rate P of the conductive particles in the thermosetting sheet before curing is preferably 30% by volume or more, more preferably 40% by volume or more, and even more preferably 50% by volume or more. The particle packing ratio P is preferably 70% by volume or less, and more preferably 60% by volume or less. When the particle filling rate P falls within the above range, the heat dissipation properties of the cured thermosetting sheet can be further improved.

[0050] The particle packing ratio P can be determined according to the following procedure. (1) The cured thermosetting sheet is mechanically polished to expose a cross section, and the exposed cross section is subjected to ion polishing using an ion polishing device (for example, product name: Cross Section Polisher SM-09010, manufactured by JEOL Ltd.). (2) An SEM image (scanning electron microscope image) of an arbitrary cross-sectional area of ​​the exposed cross-section that has been ion-polished is taken using a field emission scanning electron microscope (e.g., Hitachi High-Technologies Corporation, product name SU8020), and a backscattered electron image is obtained as image data. The imaging conditions can be an acceleration voltage of 5 kV and a magnification of 5000 times. (3) The obtained image data is subjected to an automatic binarization process using image analysis software (e.g., ImageJ) to binarize the metal parts and the resin parts. (4) The total area of ​​the conductive particle parts and the total area (conductive particle parts + resin part) are calculated from the binarized image, and the total area of ​​the conductive particle parts is divided by the total area to calculate the particle filling rate P of the conductive particles for the cured thermosetting sheet. The particle packing ratio P of the conductive particles is preferably determined by arithmetically averaging the packing ratios determined for five cross-sectional regions on the exposed cross-section subjected to ion polishing.

[0051] The thickness of the thermosetting sheet according to this embodiment is preferably 5 μm or more, more preferably 10 μm or more, and even more preferably 20 μm or more, and is preferably 150 μm or less, more preferably 100 μm or less, and even more preferably 80 μm or less. When the thickness of the thermosetting sheet is 150 μm or less, the thermal conductivity (heat dissipation) can be further improved. The thickness of the thermosetting sheet can be determined, for example, by measuring the thickness at five randomly selected points using a dial gauge (manufactured by PEACOCK, model R-205) and calculating the arithmetic average of these thicknesses.

[0052] The thermosetting sheet according to this embodiment preferably has a thermal conductivity of 3 W / m·K or more, and more preferably 10 W / m·K or more, after curing. When the thermal conductivity after curing is within the above range, the electrical conductivity of the thermosetting sheet after curing can be further increased. In the thermosetting sheet according to this embodiment, the upper limit of the thermal conductivity after curing is usually 100 W / m·K. The thermal conductivity after curing can be calculated by subjecting the thermosetting sheet according to this embodiment to heat curing at 200°C for 1 hour in a pressure cooker while applying a pressure of 0.5 MPa, and using the following formula for the heat-cured thermosetting sheet.

[0053]

number

[0054] In the above formula, thermal diffusivity (m 2 / s) can be measured by a TWA method (temperature wave thermal analysis, measuring device: iPhase Mobile, manufactured by iPhase Corporation). The specific heat (J / g°C) in the above formula can be measured by the DSC method. Specific heat measurement is performed using a DSC6220 manufactured by SII Nanotechnology, Inc., at a heating rate of 10°C / min and in the temperature range of 20 to 300°C. Based on the obtained data, the specific heat can be calculated using the method described in the JIS Handbook (specific heat capacity measurement method K-7123). Furthermore, the specific gravity in the above formula can be measured by Archimedes' method.

[0055] The thermosetting sheet according to this embodiment preferably has a peel strength against a silicon wafer at room temperature (23±2°C) of 1 N / 10 mm or more, more preferably 5 N / 10 mm or more, and even more preferably 10 N / 10 mm or more. Furthermore, the thermosetting sheet according to this embodiment preferably has a peel strength against a silicon wafer at room temperature (23±2° C.) of 20 N / 10 mm or less, and more preferably 15 N / 10 mm or less. By ensuring that the peeling force against the silicon wafer satisfies the above numerical range, peeling of the semiconductor element during dicing can be further suppressed. The peel force against a silicon wafer at room temperature can be measured by a peel test using a tensile tester (product name: Autograph AG-X, manufactured by Shimadzu Corporation) under conditions of room temperature (23±2°C), a peel angle of 180°, and a tensile speed of 300 mm / min. Specifically, it can be measured as follows. (1) A thermosetting sheet is laminated on one surface of a silicon wafer (bare wafer) to obtain a laminate. (2) The laminate is placed on a hot plate heated to 70° C. The laminate is placed so that the surface of the silicon wafer is in contact with the surface of the hot plate. (3) The laminate is pressed with a pressure roller (roller mass: 2 kg) to bond the silicon wafer and the thermosetting sheet together, and then the laminate is left on a hot plate for 2 minutes. (4) The laminate that has been left standing is removed from the hot plate and left at room temperature (23±2° C.) for 20 minutes to obtain a test specimen. (5) A peel test is carried out on the test specimen under the above conditions using the above tensile tester to measure the peel force against a silicon wafer even at room temperature.

[0056] The thermosetting sheet according to the present embodiment may contain one or more other components as required, such as a filler dispersant, a flame retardant, a silane coupling agent, and an ion trapping agent.

[0057] [Dicing die bond film] Next, the dicing die bond film 20 will be described with reference to Fig. 1. In the following description, the description of the parts that overlap with the thermosetting sheet will not be repeated.

[0058] As shown in FIG. 1, the dicing die bond film 20 of this embodiment comprises a base layer 1, a dicing tape 10 having an adhesive layer 2 laminated on the base layer 1, and a thermosetting sheet 3 laminated on the adhesive layer 2 of the dicing tape 10. In the dicing die bond film 20, a semiconductor element is attached onto a thermosetting sheet 3. The semiconductor element may be a bare wafer. The bare wafer attached to the dicing die bond film 20 according to this embodiment is cleaved into a plurality of bare chips by blade dicing, DBG (Dicing Before Grinding), SDBG (Stealth Dicing Before Grinding), or the like. During the cleaving process, the thermosetting sheet 3 is also cleaved together with the bare wafer. The thermosetting sheet 3 is cleaved into pieces of a size corresponding to the size of the individual bare chips. This allows a plurality of bare chips with the thermosetting sheet 3 to be obtained.

[0059] As described above, the thermosetting sheet 3 of the dicing die bond film 20 is a thermosetting sheet containing a thermosetting resin, a thermoplastic resin, and conductive particles, and the conductive particles have an average particle diameter D 50 The thermosetting sheet contains silver particles having a diameter of 0.01 μm or more and a circularity of 0.7 or more in cross section, and has a viscosity of 20 kPa·s or more and 3000 kPa·s or less.

[0060] The base layer 1 supports the adhesive layer 2 and the thermosetting sheet 3 laminated on the adhesive layer 2. The base layer 1 contains a resin. Examples of the resin include olefin-based resins such as polyethylene (PE), polypropylene (PP), and ethylene-propylene copolymers; copolymers containing ethylene as a monomer component, such as ethylene-vinyl acetate copolymers (EVA), ionomer resins, ethylene-(meth)acrylic acid copolymers, and ethylene-(meth)acrylic acid ester (random, alternating) copolymers; polyesters such as polyethylene terephthalate (PET), polyethylene naphthalate (PEN), and polybutylene terephthalate (PBT); acrylic resins; polyvinyl chloride (PVC); polyurethane; polycarbonate; polyphenylene sulfide (PPS); amide-based resins such as polyamide and fully aromatic polyamide (aramid); polyether ether ketone (PEEK); polyimide; polyetherimide; polyvinylidene chloride; ABS (acrylonitrile-butadiene-styrene copolymer); cellulose-based resins; silicone resins; and fluororesins. Among these, it is preferable to use polyethylene terephthalate.

[0061] The substrate layer 1 may contain one type of the above-mentioned resin, or may contain two or more types of the above-mentioned resin.

[0062] Materials for the base layer 1 include polymers such as crosslinked bodies of the resins (e.g., plastic films). The plastic films may be used without stretching, or may be uniaxially or biaxially stretched as necessary. When a resin sheet is provided with heat shrinkability by stretching or the like, the base layer 1 is heat-shrunk after dicing to reduce the adhesion area between the pressure-sensitive adhesive layer 2 and the thermosetting sheet 3, facilitating the recovery of the semiconductor chips (semiconductor elements).

[0063] The surface of the base layer 1 may be subjected to a general surface treatment in order to improve adhesion to adjacent layers, retention, etc. Examples of such surface treatments include chemical or physical treatments such as chromate treatment, ozone exposure, flame exposure, high-voltage shock exposure, and ionizing radiation treatment, as well as coating treatment with a primer.

[0064] The thickness of the base layer 1 is preferably from 1 μm to 1000 μm, more preferably from 10 μm to 500 μm, further preferably from 20 μm to 300 μm, and particularly preferably from 30 μm to 200 μm. The thickness of the base layer 1 can be determined using a dial gauge (Model R-205, manufactured by PEACOCK) in the same manner as the thickness of the thermosetting sheet 3 described above.

[0065] The base layer 1 may contain various additives, such as colorants, fillers, plasticizers, antioxidants, antioxidants, surfactants, and flame retardants.

[0066] The adhesive used to form the adhesive layer 2 is not particularly limited, and may be, for example, a general pressure-sensitive adhesive such as an acrylic adhesive or a rubber-based adhesive. As the pressure-sensitive adhesive, an acrylic adhesive having an acrylic polymer as a base polymer is preferred from the viewpoint of cleaning and washing properties with ultrapure water or organic solvents such as alcohol for electronic components that are sensitive to contamination, such as semiconductor wafers and glass.

[0067] Examples of the acrylic polymer include acrylic polymers using one or more of (meth)acrylic acid alkyl esters and (meth)acrylic acid cycloalkyl esters as monomer components. Examples of the (meth)acrylic acid alkyl esters include methyl esters, ethyl esters, propyl esters, isopropyl esters, butyl esters, isobutyl esters, s-butyl esters, t-butyl esters, pentyl esters, isopentyl esters, hexyl esters, heptyl esters, octyl esters, 2-ethylhexyl esters, isooctyl esters, nonyl esters, decyl esters, isodecyl esters, undecyl esters, dodecyl esters, tridecyl esters, tetradecyl esters, hexadecyl esters, octadecyl esters, and eicosyl esters, and the like, which are linear or branched alkyl esters having 1 to 30 carbon atoms, particularly 4 to 18 carbon atoms. Examples of the (meth)acrylic acid cycloalkyl esters include cyclopentyl esters and cyclohexyl esters. The (meth)acrylic acid ester means at least one of an acrylic acid ester and a methacrylic acid ester, and all (meth) in the present invention have the same meanings as those described above.

[0068] The acrylic polymer may contain units corresponding to other monomer components copolymerizable with the (meth)acrylic acid alkyl ester or (meth)acrylic acid cycloalkyl ester, if necessary, for the purpose of modifying the cohesive strength, heat resistance, etc. Examples of such monomer components include carboxyl-containing monomers such as acrylic acid, methacrylic acid, carboxyethyl (meth)acrylate, carboxypentyl (meth)acrylate, itaconic acid, maleic acid, fumaric acid, and crotonic acid; acid anhydride monomers such as maleic anhydride and itaconic anhydride; 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 6-hydroxyhexyl (meth)acrylate, 8-hydroxyoctyl (meth)acrylate, and 10-hydroxydecyl (meth)acrylate. Examples of the copolymerizable monomers include hydroxyl group-containing monomers such as 12-hydroxylauryl (meth)acrylate, (4-hydroxymethylcyclohexyl)methyl (meth)acrylate, etc.; styrenesulfonic acid, allylsulfonic acid, 2-(meth)acrylamido-2-methylpropanesulfonic acid, (meth)acryloyloxynaphthalenesulfonic acid, sulfopropyl (meth)acrylate, (meth)acryloyloxynaphthalenesulfonic acid, etc.; phosphoric acid group-containing monomers such as 2-hydroxyethylacryloylphosphate, etc.; acrylamide, acrylonitrile, etc. These copolymerizable monomer components can be used alone or in combination. The amount of these copolymerizable monomers used is preferably 40% by mass or less of the total monomer components.

[0069] Furthermore, the acrylic polymer may contain a polyfunctional monomer as a copolymerization monomer component for crosslinking, if necessary. Examples of such polyfunctional monomers include hexanediol di(meth)acrylate, (poly)ethylene glycol di(meth)acrylate, (poly)propylene glycol di(meth)acrylate, neopentyl glycol di(meth)acrylate, pentaerythritol di(meth)acrylate, trimethylolpropane tri(meth)acrylate, pentaerythritol tri(meth)acrylate, dipentaerythritol hexa(meth)acrylate, epoxy(meth)acrylate, polyester(meth)acrylate, and urethane(meth)acrylate. These polyfunctional monomers may be used alone or in combination. The amount of the polyfunctional monomer used is preferably 30% by mass or less of the total monomer components in terms of adhesion properties, etc.

[0070] The acrylic polymer can be obtained by polymerizing a single monomer or a mixture of two or more monomers. The polymerization may be carried out by any method such as solution polymerization, emulsion polymerization, bulk polymerization, suspension polymerization, etc. From the viewpoint of preventing contamination of clean adherends, it is preferable that the content of low molecular weight substances is small. From this viewpoint, the number average molecular weight of the acrylic polymer is preferably 300,000 or more, and more preferably about 400,000 to 3,000,000.

[0071] In addition, an external crosslinking agent can be appropriately added to the adhesive in order to increase the number average molecular weight of the base polymer, such as an acrylic polymer. Specific means for the external crosslinking method include a method of adding a crosslinking agent such as a polyisocyanate compound, an epoxy compound, an aziridine compound, or a melamine crosslinking agent and reacting it. When using an external crosslinking agent, the amount of the agent is appropriately determined in consideration of the balance with the base polymer to be crosslinked and the intended use as an adhesive. In general, the external crosslinking agent is preferably blended in an amount of about 5 parts by mass or less, more preferably 0.1 to 5 parts by mass, per 100 parts by mass of the base polymer.

[0072] In addition to the above components, the pressure-sensitive adhesive may contain various known additives such as a tackifier and an antiaging agent, if necessary.

[0073] The adhesive layer 2 can be formed from a radiation-curable adhesive. The degree of crosslinking of a radiation-curable adhesive can be increased by irradiation with radiation such as ultraviolet light, and the adhesive strength can be easily reduced. That is, by forming the adhesive layer 2 from a radiation-curable adhesive, the adhesive layer 2 can be sufficiently adhered to the thermosetting sheet 3 without being irradiated with radiation before dicing, and after dicing, the adhesive layer 2 can be irradiated with radiation to reduce the adhesive strength of the adhesive layer 2, allowing the semiconductor chip (semiconductor element) to be easily picked up (recovered).

[0074] The radiation curable adhesive can be used without any particular limitation as long as it has a radiation curable functional group such as a carbon-carbon double bond and exhibits adhesive properties. Examples of the radiation curable adhesive include additive-type radiation curable adhesives in which a radiation curable monomer component or oligomer component is blended with a general pressure-sensitive adhesive such as an acrylic adhesive or a rubber adhesive.

[0075] Examples of the radiation-curable monomer component include urethane (meth)acrylate, trimethylolpropane tri(meth)acrylate, tetramethylolmethane tetra(meth)acrylate, pentaerythritol tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, dipentaerythritol monohydroxypenta(meth)acrylate, dipentaerythritol hexa(meth)acrylate, and 1,4-butanediol di(meth)acrylate. Examples of the radiation-curable oligomer component include various oligomers such as urethane-based, polyether-based, polyester-based, polycarbonate-based, and polybutadiene-based oligomers, and those having a molecular weight in the range of about 100 to 30,000 are preferred. The amount of the radiation-curable monomer component or the radiation-curable oligomer component is preferably an amount that can suitably reduce the adhesive strength of the adhesive layer 2 after radiation irradiation. In general, the amount of the radiation-curable monomer component or the radiation-curable oligomer component is, for example, preferably 5 to 500 parts by mass, and more preferably 40 to 150 parts by mass, per 100 parts by mass of the base polymer, such as an acrylic polymer, that constitutes the pressure-sensitive adhesive.

[0076] In addition to the above-mentioned additive-type radiation-curable adhesives, examples of the radiation-curable adhesive include internal-type radiation-curable adhesives using a base polymer having a carbon-carbon double bond in the polymer side chain, in the main chain, or at the end of the main chain. The internal-type radiation-curable adhesive does not need to contain low molecular weight oligomer components or the like, or the content of the oligomer components or the like is relatively small. Therefore, when the internal-type radiation-curable adhesive is used, the oligomer components or the like are prevented from moving over time in the adhesive layer 2. As a result, the adhesive layer 2 can have a relatively stable layer structure.

[0077] The base polymer having a carbon-carbon double bond can be used without any particular limitation as long as it has a carbon-carbon double bond and has adhesiveness. As such a base polymer, it is preferable that the base polymer has an acrylic polymer as a basic skeleton. As the basic skeleton of the acrylic polymer, the above-mentioned acrylic polymer can be mentioned.

[0078] The method of introducing a carbon-carbon double bond into the acrylic polymer is not particularly limited, and various methods can be adopted, but the adoption of a method of introducing a carbon-carbon double bond into a polymer side chain makes molecular design easier. For example, a method of copolymerizing a monomer having a functional group with an acrylic polymer in advance, and then carrying out a condensation reaction or addition reaction with a compound having a functional group and a carbon-carbon double bond that can react with the functional group while maintaining the radiation curability of the carbon-carbon double bond can be mentioned.

[0079] Examples of combinations of these functional groups include a carboxylic acid group and an epoxy group, a carboxylic acid group and an aziridyl group, and a hydroxyl group and an isocyanate group. Among these combinations of functional groups, a combination of a hydroxyl group and an isocyanate group is preferred from the viewpoint of ease of reaction tracking. In addition, as long as the combination of these functional groups produces an acrylic polymer having a carbon-carbon double bond, either of the functional groups may be on the acrylic polymer side or on the compound having a carbon-carbon double bond side. In the case of the above preferred combination, it is preferred that the acrylic polymer has a hydroxyl group and the compound having a carbon-carbon double bond has an isocyanate group. In this case, examples of the isocyanate compound having a carbon-carbon bond include methacryloyl isocyanate, 2-methacryloyloxyethyl isocyanate, m-isopropenyl-α,α-dimethylbenzyl isocyanate, and the like. As the acrylic polymer, a copolymer of the above-mentioned hydroxyl group-containing monomers or ether compounds such as 2-hydroxyethyl vinyl ether, 4-hydroxybutyl vinyl ether, and diethylene glycol monovinyl ether can be used.

[0080] The inherent type radiation-curable adhesive can use the base polymer having a carbon-carbon double bond (particularly, an acrylic polymer) alone, but can also contain the radiation-curable monomer component or the radiation-curable oligomer component to the extent that the properties are not deteriorated. The radiation-curable oligomer component is usually contained in an amount of 30 parts by mass or less, and preferably 1 to 10 parts by mass or less, per 100 parts by mass of the base polymer.

[0081] The radiation-curable adhesive contains a photopolymerization initiator when curing with ultraviolet light or the like. Examples of the photopolymerization initiator include α-ketol-based compounds such as 4-(2-hydroxyethoxy)phenyl(2-hydroxy-2-propyl)ketone, α-hydroxy-α,α'-dimethylacetophenone, 2-methyl-hydroxypropiophenone, and 1-hydroxycyclohexylphenylketone; acetophenone-based compounds such as methoxyacetophenone, 2,2-dimethoxy-2-phenylacetophenone, 2,2-diethoxyacetophenone, and 2-methyl-1-[4-(methylthio)-phenyl]-2-morpholinopropane-1; benzoin ether-based compounds such as benzoin ethyl ether, benzoin isopropyl ether, and anisoin methyl ether; and ketal-based compounds such as benzyl dimethyl ketal. Examples of the photopolymerization initiator include aromatic sulfonyl chloride compounds such as 2-naphthalenesulfonyl chloride; photoactive oxime compounds such as 1-phenone-1,1-propanedione-2-(o-ethoxycarbonyl)oxime; benzophenone compounds such as benzophenone, benzoylbenzoic acid, and 3,3'-dimethyl-4-methoxybenzophenone; thioxanthone compounds such as thioxanthone, 2-chlorothioxanthone, 2-methylthioxanthone, 2,4-dimethylthioxanthone, isopropylthioxanthone, 2,4-dichlorothioxanthone, 2,4-diethylthioxanthone, and 2,4-diisopropylthioxanthone; camphorquinone; halogenated ketones; acylphosphinoxides; and acylphosphonates. The amount of the photopolymerization initiator is, for example, 0.05 to 20 parts by mass relative to 100 parts by mass of the base polymer such as an acrylic polymer constituting the adhesive.

[0082] Examples of radiation-curable adhesives include rubber-based adhesives and acrylic-based adhesives that contain a photopolymerizable compound, such as an addition-polymerizable compound having two or more unsaturated bonds or an alkoxysilane having an epoxy group, and a photopolymerization initiator, such as a carbonyl compound, an organic sulfur compound, a peroxide, an amine, or an onium salt compound, as disclosed in JP-A-60-196956.

[0083] In cases where curing is inhibited by oxygen during radiation irradiation, it is desirable to use some method to block oxygen (air) from the surface of the radiation-curable pressure-sensitive adhesive layer 2. Examples of such methods include a method of covering the surface of the pressure-sensitive adhesive layer 2 with a separator, and a method of irradiating the pressure-sensitive adhesive layer 2 with radiation such as ultraviolet light in a nitrogen gas atmosphere.

[0084] The thickness of the adhesive layer 2 is not particularly limited, but from the viewpoint of preventing chipping of the cut surface of the chip and at the same time maintaining the fixing and retention of the thermosetting sheet 3, it is preferably 1 to 50 μm, more preferably 2 to 30 μm, and even more preferably 5 to 25 μm.

[0085] The thermosetting sheet and dicing die bond film according to the present invention are not limited to the above-mentioned embodiment. The thermosetting sheet and dicing die bond film according to the present invention are not limited by the above-mentioned action and effect. The thermosetting sheet and dicing die bond film according to the present invention can be modified in various ways without departing from the gist of the present invention. EXAMPLES

[0086] The present invention will now be described in more detail with reference to examples. The following examples are provided to further explain the present invention in detail, and are not intended to limit the scope of the present invention.

[0087] [Example 1] A mixture containing each material in the mass ratio shown in the section of Example 1 in Table 1 below was stirred for 3 minutes using a hybrid mixer (Keyence Corporation, product name: HM-500) to prepare a varnish. This varnish was applied to one side of a release-treated film (Mitsubishi Chemical Corporation, product name: MRA38, thickness 38 μm) and then dried at a temperature of 100° C. for 2 minutes to obtain a thermosetting sheet with a thickness of 30 μm. The materials used in the following Table 1 are as follows: Phenolic resin MEHC-7851S (biphenyl-type phenolic resin, phenol equivalent: 209 g / eq) manufactured by Meiwa Kasei Co., Ltd. Solid epoxy resin Nippon Steel & Sumikin Chemical's KI-3000-4 (cresol novolac type multifunctional epoxy resin, epoxy equivalent 200g / eq) Liquid epoxy resin DIC EXA-4816 (aliphatic modified bisphenol A type epoxy resin (bifunctional type), epoxy equivalent 403g / eq) ·Silver (Ag) coated copper (Cu) particles Mitsui Mining & Smelting Co., Ltd. 1200YP (flat copper particles coated with 10% silver particles by mass, average particle size 3.5 μm, irregular shape) ·Silver (Ag) particles HP02A manufactured by Mitsui Mining & Smelting Co., Ltd. (silver particles surface-treated with a fatty acid-based coating agent) · Volatile material (isobornylcyclohexanol (MTPH)) MTPH manufactured by Nippon Terpene Chemical Acrylic resin solution Nagase Chemitec's Teisan Resin SG-70L (contains MEK and toluene as solvents, solids content 12.5%, glass transition temperature -13°C, mass average molecular weight 900,000, acid value 5mg / KOH, carboxyl group-containing acrylic copolymer) Coupling Agent Shin-Etsu Chemical Co., Ltd.'s KBE-846 (bis(triethoxysilylpropyl)tetrasulfide) ·catalyst TPP-K (Tetraphenylphosphonium tetraphenylborate) manufactured by Hokko Chemical Industry Co., Ltd. ·solvent Methyl ethyl ketone (MEK) In addition, the mass proportions of the silver-coated copper particles and silver particles in 100 parts by mass of the conductive particles (silver-coated copper particles and silver particles), the mass proportions of the epoxy resin (solid and liquid) in 100 parts by mass of the thermosetting sheet, the mass proportions of the phenolic resin in 100 parts by mass of the thermosetting sheet, the mass proportions of the acrylic resin in 100 parts by mass of the thermosetting sheet, and the mass proportion of isobornylcyclohexanol in 100 parts by mass of the organic components (phenolic resin, epoxy resin (solid and liquid), acrylic resin solution, isobornylcyclohexanol) are shown in Table 2 below.

[0088] [Example 2] A thermosetting sheet according to Example 2 was obtained in the same manner as in Example 1, except that the silver particles were a modified coating (epoxy-coated) version of HP02A manufactured by Mitsui Mining & Smelting Co., Ltd., no TPP-K was added as a catalyst, and a mixture containing each material in the mass ratio shown in the Example 2 section of Table 1 below was used.

[0089] [Example 3] A thermosetting sheet according to Example 3 was obtained in the same manner as in Example 1, except that TPP-K was not used as a catalyst and a mixture containing each material in the mass ratio shown in the Example 3 section of Table 1 below was used.

[0090] [Example 4] A thermosetting sheet of Example 4 was obtained in the same manner as in Example 1, except that the silver particles were HP02 manufactured by Mitsui Mining & Smelting Co., Ltd., TPP-K was not used as a catalyst, and a mixture containing each material in the mass ratio shown in the Example 4 section of Table 1 below was used.

[0091] [Example 5] A thermosetting sheet according to Example 5 was obtained in the same manner as in Example 1, except that the silver particles were AG-2-8F (silver particles surface-treated with a fatty acid-based coating agent) manufactured by Dowa Electronics Co., Ltd., the silver (Ag)-coated copper (Cu) particles were AOP-TCY-2(EN) manufactured by Dowa Electronics Co., Ltd., and a mixture containing each material in the mass ratio shown in the section for Example 5 in Table 1 below was used.

[0092] [Comparative Example 1] A thermosetting sheet according to Comparative Example 1 was obtained in the same manner as in Example 1, except that the silver particles were SPH02J (aggregated nano Ag particles, irregular shape, average particle size of the aggregates: 1.8 μm) manufactured by Mitsui Mining & Smelting Co., Ltd., no TPP-K was used as a catalyst, and a mixture containing each material in the mass ratio shown in the Comparative Example 1 section of Table 1 below was used.

[0093] [Comparative Example 2] A thermosetting sheet according to Comparative Example 1 was obtained in the same manner as in Example 1, except that the silver particles were SPH02J manufactured by Mitsui Mining & Smelting Co., Ltd., and a mixture containing each material in the mass ratio shown in the Comparative Example 2 section of Table 1 below was used.

[0094] [Comparative Example 3] A thermosetting sheet for Comparative Example 3 was obtained in the same manner as in Example 1, except that the silver particles were SPH02J manufactured by Mitsui Mining & Smelting Co., Ltd., no volatile agent (isobornylcyclohexanol) was added, and a mixture containing each material in the mass ratio shown in the Comparative Example 3 section of Table 1 below was used.

[0095] [Table 1]

[0096] <Average particle size of silver (Ag) particles D 50 > Before blending, the particle size distribution was measured using a laser diffraction / scattering particle size distribution measuring device (Microtrac-Bell, Microtrac MT3000II series). The average particle diameter D of the silver particles contained in the heat-cured sheet according to each example 50 The results of the measurements are shown in Table 2 below.

[0097] <Circularity of silver (Ag) particles> The thermosetting sheet of each example was cut in the thickness direction, and an SEM image of the cut surface was taken. The SEM image was then analyzed using a powder image analyzer (PITA-3, manufactured by Seishin Enterprise Co., Ltd.). The analysis using the powder image analyzer was performed on 10 silver particles randomly selected in the SEM image, and the circularity was calculated by taking the arithmetic average of the circularity values ​​obtained for the 10 silver particles. In the thermosetting sheets according to each example, the silver particles and the silver (Ag)-coated copper (Cu) particles were distinguished by observing backscattered electron images so that light and dark areas were observed due to the difference in composition. The circularity of the silver particles in the thermosetting sheets according to each example was measured, and the results are shown in Table 2 below.

[0098] <Conductive particle filling rate> The particle packing ratio P was determined for the thermosetting sheet according to each example according to the following procedure. (1) The cured thermosetting sheet is mechanically polished to expose a cross section, and the exposed cross section is subjected to ion polishing using an ion polishing device (manufactured by JEOL Ltd., product name: Cross Section Polisher SM-09010). (2) An SEM image (image taken by a scanning electron microscope) of an arbitrary cross-sectional area of ​​the exposed cross-section that has been ion-polished is taken using a field emission scanning electron microscope SU8020 (manufactured by Hitachi High-Technologies Corporation), and a backscattered electron image is obtained as image data. The imaging conditions are an acceleration voltage of 5 kV and a magnification of 5000 times. (3) The obtained image data is subjected to automatic binarization processing using the image analysis software ImageJ to binarize the metal parts and the resin parts. (4) The total area of ​​the metal parts and the total area (metal parts + resin parts) are calculated from the binarized image, and the total area of ​​the metal parts is divided by the total area to calculate the particle filling rate P of the conductive particles for the cured thermosetting sheet. The particle packing ratio P of the conductive particles was determined by arithmetically averaging the particle packing ratios determined for five cross-sectional regions on the exposed cross-section that had been ion-polished. The particle filling rate P of the conductive particles was determined for each of the thermosetting sheets according to the examples, and the results are shown in Table 2 below.

[0099] <Viscosity of thermosetting sheet at 100℃> The viscosity of the thermosetting sheet of each example at 100°C was evaluated using a rheometer (a rotational rheometer, HAAKE MARS, manufactured by Thermo Fisher Scientific Co., Ltd.) by reading the indicated value at 100°C when the temperature was increased from 30°C to 180°C at a rate of 10°C / min. The viscosity at 100° C. of the thermosetting sheets of each example was measured, and the results are shown in Table 2 below.

[0100] <Thermal conductivity of thermosetting sheets> The thermosetting sheet according to each example was heat-cured in a pressure cooker at 200° C. for 1 hour while applying a pressure of 0.5 MPa. The thermal conductivity of the heat-cured thermosetting sheet according to each example was calculated according to the following formula.

[0101]

number

[0102] Thermal diffusivity α(m 2 / s) was measured by the TWA method (temperature wave thermal analysis, measuring device: iPhase Mobile, manufactured by iPhase Corporation). Specific heat C p The specific heat capacity (J / g·°C) was measured by the DSC method. Specific heat measurements were performed using a DSC6220 manufactured by SII Nanotechnology, Inc., at a heating rate of 10°C / min and in the temperature range of 20 to 300°C. Based on the data obtained, the specific heat was calculated using the method described in the JIS Handbook (specific heat capacity measurement method K-7123). The specific gravity was measured by the Archimedes method. The thermal conductivity of the cured thermosetting sheets of each example was calculated and the results are shown in Table 2 below.

[0103] <Peeling force against silicon wafer> The adhesive strength of the thermosetting sheet according to each example to a silicon wafer was measured. The peeling strength against the silicon wafer was measured at room temperature (23±2°C). The peeling strength against the silicon wafer was measured by a peeling test using a tensile tester (product name: Autograph AG-X, manufactured by Shimadzu Corporation) under the conditions of room temperature (23±2°C), a peeling angle of 180°, and a pulling speed of 300 mm / min. Specifically, the measurements were carried out as follows. (1) A thermosetting sheet is laminated on one surface of a silicon wafer (bare wafer) to obtain a laminate. (2) The laminate is placed on a hot plate heated to 70° C. The laminate is placed so that the surface of the silicon wafer is in contact with the surface of the hot plate. (3) The laminate is pressed with a pressure roller (roller mass: 2 kg) to bond the silicon wafer and the thermosetting sheet together, and then the laminate is left on a hot plate for 2 minutes. (4) The laminate that has been left standing is removed from the hot plate and left at room temperature (23±2° C.) for 20 minutes to obtain a test specimen. (5) A peel test is carried out on the test specimen under the above conditions using the above tensile tester to measure the peel force against a silicon wafer even at room temperature. The peel strength of the thermosetting sheet according to each example against a silicon wafer was measured, and the results are shown in Table 2 below.

[0104] <Peeling during dicing> The evaluation of the peelability during dicing was performed using a dicing die bond film in which a thermosetting sheet was laminated on the adhesive layer of a dicing tape, and a bare wafer. In detail, the following steps were followed: (1) A Si bare wafer having a thickness of 100 μm and a diameter of 8 inches (200 mm) is attached onto the thermosetting sheet while being pressed using a pressing means (pressure roller). (2) A fully automatic dicing saw (DISCO, FULLY AUTOMATIC DICING SAW, DFD6361) was used, and the spindle speed was 45,000 rpm (min -1 ), a feed rate of 30 mm / s, and a pitch of 5 mm, the thermosetting sheet and the Si bare wafer are subjected to blade dicing to obtain a plurality of thermosetting sheets on which bare chips are stacked. If no bare chips are found to have peeled off from the thermosetting sheet to a level that would be a practical problem, the peelability during dicing is evaluated as ◯, and if even one bare chip is found to have peeled off to a level that would be a practical problem (chip flying), the peelability during dicing is evaluated as ×.

[0105] The pressure-sensitive adhesive layer, dicing tape, and dicing die bond film were prepared as follows.

[0106] (Preparation of adhesive layer) Synthesis of acrylic polymer The following raw materials were placed in a reaction vessel equipped with a cooling tube, a nitrogen inlet tube, a thermometer, and a stirrer so that the monomer concentration was about 55% by mass, and a polymerization reaction was carried out at 60°C for 10 hours under a nitrogen stream, thereby synthesizing an acrylic polymer intermediate. 2-Ethylhexyl acrylate (2HEA): 100 parts by weight 2-Hydroxyethyl acrylate (HEA): 20 parts by weight Polymerization initiator: appropriate amount Polymerization solvent: toluene An acrylic polymer was synthesized by carrying out an addition reaction between 100 parts by mass of the synthesized acrylic polymer intermediate and 1.4 parts by mass of 2-methacryloyloxyethyl isocyanate (MOI) in the presence of dibutyltin dilaurate (0.1 part by mass) at 50°C in an air stream for 60 hours to synthesize an acrylic polymer. Preparation of adhesive layer (1) Obtain a solution containing the following raw materials, and add toluene to the solution appropriately to prepare an adhesive solution with a viscosity of 500 mPa·s. Synthesized acrylic polymer: 100 parts by weight Polyisocyanate compounds (manufactured by Nippon Polyurethane Co., Ltd., product name "Coronate L"): 1.1 parts by mass Photopolymerization initiator (manufactured by Ciba Specialty Chemicals, product name "Irgacure 184"): 3 parts by weight (2) A PET film is prepared as a release sheet. The adhesive solution prepared as described above is applied to one side of the release sheet using an applicator. The one side of the release sheet (PET film) is treated with silicone as a release treatment. After application, the solution is dried by heating at 120°C for 2 minutes to form an adhesive layer with a thickness of 30 μm on the release sheet.

[0107] (Preparation of dicing tape and dicing die bond film) Preparation of dicing tape A supporting substrate made of a polyethylene film having a thickness of 80 μm was attached to the exposed surface of the pressure-sensitive adhesive layer prepared on the release sheet at room temperature using a laminator to prepare a dicing tape. In addition, the adhesive layer of the dicing tape was exposed to ultraviolet light at an intensity of 300 mJ / cm2 on the part of the tape where the 8-inch diameter Si bare wafer was to be attached. 2 The portion to be attached was cured with ultraviolet light. Preparation of dicing die bond film A thermosetting sheet was placed on the adhesive layer of the dicing tape after UV curing, so that the side opposite the laminated side of the release sheet was in contact with it, and the dicing tape was passed through a laminator at a speed of 0.8 mm / min to bond the thermosetting sheet to the dicing tape, and then the release sheet was removed to produce a dicing die bond film in which the thermosetting sheet was laminated to the dicing tape.

[0108] The thermosetting sheets according to the respective examples were evaluated for releasability during dicing, and the results are shown in Table 2 below.

[0109] [Table 2]

[0110] As shown in Table 2, the thermosetting sheets according to each Example all have conductive particles with an average particle diameter D 50 It was found that the silver particles contained had a diameter of 0.01 μm or more and 10 μm or less and a circularity of 0.7 or more in cross section, and further had a viscosity at 100°C in the range of 20 kPa·s or more and 3000 kPa·s or less. The thermosetting sheets of each Example had a thermal conductivity of 3 W / m K or more after curing, which means that they have sufficient heat dissipation for practical use. In addition, they had a relatively high peel force against the silicon wafer of 1.0 N / 10 mm or more, and the peelability during dicing was evaluated as good.

[0111] In contrast, the thermosetting sheets of Comparative Examples 1 and 2 contained silver particles with a cross-sectional circularity of less than 0.7, and were found to have a viscosity at 100°C of more than 3000 kPa·s. The thermosetting sheets of Comparative Examples 1 and 2 had a thermal conductivity of 3 W / m K or more after curing, and thus exhibited sufficient heat dissipation for practical use. However, the peel force required to peel the sheets off the silicon wafer was less than 1.0 N / 10 mm, and the peelability during dicing was evaluated as poor. Furthermore, it was found that the thermosetting sheet of Comparative Example 3 contained silver particles having a cross-sectional circularity of less than 0.7 and had a viscosity at 100°C in the range of 20 kPa·s to 3000 kPa·s. The thermosetting sheet in Comparative Example 3 had a relatively high peel force from the silicon wafer of 7.63 N / 10 mm, and was evaluated as having good releasability during dicing. However, the thermal conductivity was 1.5 W / m K, which did not provide sufficient heat dissipation for practical use.

[0112] From these results, the thermosetting sheet is used as the conductive particles with an average particle diameter D 50It was found that by containing silver particles having a diameter of 0.01 μm or more and 10 μm or less and a cross-sectional circularity of 0.7 or more, and having a viscosity at 100°C in the range of 20 kPa·s or more and 3000 kPa·s or less, peeling of the semiconductor element during dicing can be relatively suppressed, and the heat dissipation properties after hardening can be relatively high. [Explanation of symbols]

[0113] 1 Base material layer 2 Adhesive layer 3 Thermosetting Sheet 10 Dicing tape 20 Dicing die bond film

Claims

1. A thermosetting sheet comprising a thermosetting resin, a thermoplastic resin, and conductive particles, the thermosetting resin includes an epoxy resin, The conductive particles have an average particle diameter D ５０ The silver particles have a diameter of 0.01 μm or more and 10 μm or less and a circularity of 0.7 or more in cross section, the mass % of the conductive particles is 83 mass % or more and 95 mass % or less based on 100 mass % of the thermosetting sheet; Viscosity at 100°C is 20 kPa·s or more and 3000 kPa·s or less Thermosetting sheet.

2. The mass percentage of the conductive particles in 100 mass percentage of the thermosetting sheet is 89 mass% or more and 95 mass% or less. The thermosetting sheet according to claim 1 .

3. The particle filling rate P of the conductive particles in the thermosetting sheet after curing is 30 volume % or more. The thermosetting sheet according to claim 1 or 2.

4. The thermal conductivity after curing is 3 W / m.K or more and 100 W / m.K or less. The thermosetting sheet according to claim 1 .

5. The peeling force against silicon wafers at room temperature is 1N / 10mm to 20N / 10mm. The thermosetting sheet according to claim 1 .

6. Contains volatile components, The volatile component contains one or more hydroxyl groups and has a boiling point of 250° C. or more and 350° C. or less. The thermosetting sheet according to claim 1 .

7. The volatile component is a terpene compound. The thermosetting sheet according to claim 6.

8. A base layer; a dicing tape having a pressure-sensitive adhesive layer laminated on the base layer; a thermosetting sheet laminated on the adhesive layer of the dicing tape; The thermosetting sheet is the thermosetting sheet according to any one of claims 1 to 7. Dicing die bond film.

Images