Thermosetting sheet and cutting chip bonding film

Abstract

The present application provides a thermosetting sheet and a cutting chip bonding film. The thermosetting sheet of the present application is a thermosetting sheet containing a thermosetting resin, a thermoplastic resin, and electrically conductive particles, the electrically conductive particles containing silver particles having an average particle diameter D 50 of 0.01 μm or more and 10 μm or less and a circularity of a cross section of 0.7 or more, the thermosetting sheet having a viscosity of 20 kPa·s or more and 3000 kPa·s or less at 100°C.

Description

[0001] Cross-referencing of related applications

[0002] This application claims priority to Japanese Patent Application Nos. 2020-109065 and 2021-007112, which are incorporated herein by reference. Technical Field

[0003] This invention relates to thermosetting sheets and chip-cut bonding films. Background Technology

[0004] As a method for bonding semiconductor elements to a metal lead frame or other bonded object in the manufacture of semiconductor devices (chip bonding method), the use of thermosetting sheets has been known (e.g., Patent Document 1).

[0005] Patent Document 1 discloses a thermosetting sheet comprising conductive particles and a thermosetting resin.

[0006] In such a method, for example, the semiconductor wafer and the aforementioned thermosetting sheet are cut with a thermosetting sheet attached to one side of the semiconductor wafer (the side opposite to the circuit formation surface) to obtain a plurality of thermosetting sheets with semiconductor elements attached to one side.

[0007] Then, after one side of the thermosetting sheet with the semiconductor element attached is temporarily bonded to a substrate such as a metal lead frame at a specified temperature (e.g., 70°C), it is thermosetting at a higher temperature (e.g., 200°C), thereby bonding it to the substrate. That is, the semiconductor element is bonded to the substrate with the thermosetting sheet sandwiched between it.

[0008] Existing technical documents

[0009] Patent documents

[0010] Patent Document 1: Japanese Patent Application Publication No. 2019-21813 Summary of the Invention

[0011] The problem the invention aims to solve

[0012] On the other hand, when a thermosetting sheet with a semiconductor element attached to one side is bonded to the aforementioned adhesive, the semiconductor element may sometimes peel off from the thermosetting sheet. When such peeling occurs, the electrical and thermal conduction via the aforementioned conductive particles becomes insufficient, which is therefore undesirable.

[0013] Furthermore, when the aforementioned semiconductor wafer and the aforementioned thermosetting sheet are cut, the aforementioned peeling will occur more significantly (the aforementioned semiconductor element will detach more noticeably from the aforementioned thermosetting sheet).

[0014] However, it is difficult to say that sufficient research has been conducted on suppressing the peeling of the aforementioned semiconductor elements from the aforementioned thermosetting sheet.

[0015] Furthermore, when power semiconductor elements are used in semiconductor devices, they generate a large amount of heat because they are used at high power levels of several MVA or more.

[0016] Therefore, when using the thermosetting sheet as described above in power semiconductor devices, it is preferable that the thermosetting sheet bonded to the substrate, i.e., the cured thermosetting sheet, has high heat dissipation.

[0017] The aforementioned heat generation problem also occurs when using semiconductor components other than power semiconductor components. However, it is difficult to say that sufficient research has been conducted on improving the heat dissipation of cured thermosetting sheets.

[0018] Therefore, the objective of this invention is to provide a thermosetting sheet that can relatively suppress the peeling of semiconductor elements and has high heat dissipation after curing, and a die bonding film having the thermosetting sheet.

[0019] Solution for solving the problem

[0020] The thermosetting sheet of the present invention is a thermosetting sheet comprising a thermosetting resin, a thermoplastic resin, and conductive particles.

[0021] The aforementioned conductive particles include an average particle size D 50 Silver particles with a diameter of 0.01 μm or larger and a diameter of 10 μm or smaller, and a cross-sectional circularity of 0.7 or larger.

[0022] The aforementioned thermosetting sheet has a viscosity of 20 kPa·s or higher and 3000 kPa·s or lower at 100°C.

[0023] Of the aforementioned thermosetting sheets, the preferred type is...

[0024] The particle filling rate P of the aforementioned conductive particles in the cured thermosetting sheet is 30% or more by volume.

[0025] Of the aforementioned thermosetting sheets, the preferred type is...

[0026] The thermal conductivity after curing is above 3 W / m·K.

[0027] Of the aforementioned thermosetting sheets, the preferred type is...

[0028] The peel strength relative to silicon wafers at room temperature is above 1 N / 10 mm.

[0029] Of the aforementioned thermosetting sheets, the preferred type is...

[0030] Contains volatile components,

[0031] The aforementioned volatile components contain more than one hydroxyl group and have a boiling point of 250°C or higher.

[0032] Of the aforementioned thermosetting sheets, the preferred type is...

[0033] The aforementioned volatile components are terpenoid compounds.

[0034] The chip bonding film of the present invention comprises:

[0035] Substrate layer

[0036] Cut strips with adhesive layers are laminated on the substrate layer, and

[0037] A thermosetting sheet is laminated on the adhesive layer of the aforementioned cutting strip.

[0038] The aforementioned thermosetting sheet is any of the thermosetting sheets mentioned above. Attached Figure Description

[0039] Figure 1 This is a cross-sectional view showing the structure of a die-cutting bonding film according to one embodiment of the present invention.

[0040] Explanation of reference numerals in the attached figures

[0041] 1. Substrate layer

[0042] 2 Adhesive layer

[0043] 3. Thermosetting sheets

[0044] 10 Cutting strip

[0045] 20 Cut chip bonding film Detailed Implementation

[0046] Hereinafter, one embodiment of the present invention will be described.

[0047] [Thermosetting sheets]

[0048] The thermosetting sheet of this embodiment comprises thermosetting resin, thermoplastic resin, and conductive particles.

[0049] In this specification, conductive particles refer to particles with a conductivity of less than 100 μS / cm as measured according to JIS K 0130 (2008).

[0050] In the aforementioned thermosetting sheet, the mass percentage of the aforementioned thermosetting resin in 100% by mass (parts by mass) is preferably 1% by mass or more and 30% by mass or less, more preferably 3% by mass or more and 15% by mass or less.

[0051] The thermoplastic resin in the aforementioned thermosetting sheet is preferably 0.5% or more and 10% or less by mass, more preferably 1% or more and 7% or less by mass.

[0052] The aforementioned conductive particles account for 60% or more and 95% or less of the aforementioned 100% by mass of the thermosetting sheet, and more preferably 80% or more and 93% or less by mass.

[0053] Furthermore, the mass percentage of the aforementioned thermosetting resin in 100% by mass of the resin (thermosetting resin and thermoplastic resin) is preferably 30% by mass or more and 90% by mass or less, more preferably 50% by mass or more and 80% by mass or less.

[0054] Examples of thermosetting resins include epoxy resins, phenolic resins, amino resins, unsaturated polyester resins, polyurethane resins, silicone resins, and thermosetting polyimide resins. Among these, epoxy resins are preferred.

[0055] 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, phenolic varnish type, cresolic varnish type, o-cresolic varnish type, trihydroxyphenylmethane type, tetrahydroxyphenylethane type, hydantoin type, triglycidyl isocyanurate type, and glycidylamine type epoxy resins. Preferably, at least one of bisphenol A type epoxy resin and cresolic varnish type epoxy resin is used, and more preferably, a combination of bisphenol A type epoxy resin and cresolic varnish type epoxy resin is used.

[0056] As examples of bisphenol A type epoxy resins, aliphatic modified bisphenol A type epoxy resins can be cited.

[0057] Phenolic resins used as curing agents for epoxy resins include, for example, phenolic varnish-type phenolic resins, methyl phenolic resins, biphenyl-type phenolic resins, and polyhydroxystyrene such as poly(p-hydroxystyrene). Among the above-mentioned phenolic resins, biphenyl-type phenolic resins are preferred.

[0058] Furthermore, thermoplastic resins having thermosetting functional groups can also be used as thermosetting resins. Examples of thermoplastic resins having thermosetting functional groups include acrylic resins containing thermosetting functional groups. Among acrylic resins containing thermosetting functional groups, resins comprising monomer units derived from (meth)acrylates can be cited as examples.

[0059] In thermoplastic resins with thermosetting functional groups, the curing agent is selected according to the type of thermosetting functional group.

[0060] Thermoplastic resins function as adhesives.

[0061] Since the thermosetting sheet of this embodiment contains a thermoplastic resin as a binder, the viscosity of the thermosetting sheet at 100°C can be easily adjusted to 20 kPa·s or more and 3000 kPa·s or less, as described later.

[0062] Examples of thermoplastic resins include natural rubber, butyl rubber, isoprene rubber, chloroprene rubber, ethylene-vinyl acetate copolymer, ethylene-acrylic acid copolymer, ethylene-acrylate copolymer, polybutadiene resin, polycarbonate resin, thermoplastic polyimide resin, polyamide 6, polyamide 6,6 and other polyamide resins, phenoxy resins, acrylic resins, saturated polyester resins such as PET and PBT, polyamide-imide resins, and fluoropolymers. One of these thermoplastic resins may be used, or two or more may be used in combination. From the viewpoint that acrylic resins have fewer ionic impurities and higher heat resistance, thus easily ensuring the bonding reliability of thermosetting sheets, acrylic resins are preferred.

[0063] The aforementioned acrylic resin is preferably a polymer in which monomer units derived from (meth)acrylates constitute the majority of the monomer units by mass. Examples of (meth)acrylates include alkyl (meth)acrylates, cycloalkyl (meth)acrylates, and aryl (meth)acrylates. The aforementioned acrylic resin may also contain monomer units derived from other components that can copolymerize with (meth)acrylates. Examples of such other components include, for instance, carboxyl-containing monomers, anhydride monomers, hydroxyl-containing monomers, glycidyl-containing monomers, sulfonic acid-containing monomers, phosphate-containing monomers, acrylamide, acrylonitrile, and other functionalized monomers, as well as various multifunctional monomers.

[0064] The aforementioned acrylic resin is preferably a carboxyl-containing acrylic rubber.

[0065] The aforementioned conductive particles include an average particle size D 50 Silver particles with a diameter of 0.01 μm or larger and 10 μm or smaller, and a circularity of 0.7 or larger in the cross-section along the thickness direction.

[0066] The aforementioned conductive particles contain an average particle size D 50 Silver particles smaller than 10 μm can be melted at a temperature (e.g., 200°C) that is sufficient to cure the aforementioned thermosetting resin to sinter the outer surface of the silver particles.

[0067] Furthermore, by making the average particle size D of the aforementioned silver particles 50With a diameter of 0.01 μm or larger, the aforementioned silver particles are not only more easily dispersed in the aforementioned thermosetting sheet, but also the surface of the aforementioned silver particles is easily oxidized due to their large specific surface area, thus ensuring sufficient conductivity of the aforementioned silver particles.

[0068] Therefore, it is possible to have sufficient conductivity and melt in a relatively dispersed state to the extent that the outer surface of the aforementioned silver particles can be sintered. Thus, it is possible to use the aforementioned silver particles to sinter the aforementioned conductive particles together (or, in the case where the aforementioned conductive particles are only silver particles, silver particles together).

[0069] Furthermore, since the sphericity of the silver particles at the cross-section is 0.7 or higher, the silver particles can be more fully dispersed in the thermosetting sheet. Therefore, the conductive particles (or silver particles themselves if the conductive particles are only silver particles) can be sintered together using the silver particles that are fully dispersed in the thermosetting sheet.

[0070] Therefore, after curing, the thermosetting sheet of the present invention has sufficient electrical conductivity and high heat dissipation.

[0071] The average particle size D of the aforementioned silver particles 50 Preferably, the micrometer is 0.1 μm or more and 5 μm or less, more preferably 0.5 μm or more and 2 μm or less.

[0072] Furthermore, the roundness of the aforementioned silver particles in the cross-section in the thickness direction is preferably 0.8 or higher.

[0073] It should be noted that the upper limit for roundness is 1.

[0074] The average particle size D of silver particles 50 For example, a laser diffraction / scattering particle size distribution measuring device (manufactured by MicrotracBEL Corp., Microtrac MT3000II series) can be used to measure it according to a volumetric standard.

[0075] Circularity is an index of shape complexity based on the area and perimeter. When the area is set to S and the perimeter to L, the circularity is expressed as 4πS / L. 2 The value of circularity is used to represent the shape. A circularity value of 1 indicates a perfect circle, and the smaller the circularity value is, the further it deviates from the shape of a circle.

[0076] The roundness can be obtained as follows: the aforementioned thermosetting sheet is cut along the thickness direction, and a SEM image of the cut surface is taken. The SEM image is then analyzed using a powder image analysis device (manufactured by SEISHIN ENTERPRISE Co., Ltd., PITA-3) (specifically, using image analysis software such as "Image J").

[0077] The analysis was performed using a powder image analysis device on 10 randomly selected silver particles in the SEM image. The roundness was calculated by taking the arithmetic mean of the roundness values ​​obtained for the 10 silver particles.

[0078] It should be noted that when the aforementioned thermosetting sheet contains conductive particles other than silver particles, the silver particles can be distinguished from the conductive particles other than silver particles by using reflective electron imaging, which observes the difference in brightness due to the difference in composition.

[0079] Silver particles can be composed of silver and other elements (metallic elements, etc.) that are unavoidable impurities, or they can be silver particles that have undergone surface treatment (e.g., silane coupling treatment). Examples of surface treatment agents for silver particles include fatty acid-based, amine-based, and epoxy-based coatings. Examples of silver particles surface-treated with fatty acid-based coatings include HP02 and HP02A manufactured by Mitsui Metals & Mining Co., Ltd., and examples of silver particles treated with epoxy-based coatings include modified versions of HP02A (epoxy-coated products) manufactured by Mitsui Metals & Mining Co., Ltd.

[0080] In this embodiment of the thermosetting sheet, silver particles that have undergone surface treatment with an epoxy-based coating agent are preferably used. As described above, the thermosetting sheet of this embodiment contains a thermosetting resin. Therefore, when silver particles that have undergone surface treatment with an epoxy-based coating agent are used as silver particles, these silver particles exhibit a higher affinity with the thermosetting resin in the thermosetting sheet, making them easier to disperse in the thermosetting sheet. Furthermore, the easier it is to disperse in the thermosetting sheet, the more likely the aforementioned silver particles are to be contained in the thermosetting sheet, thus improving the thermal conductivity (heat dissipation) of the thermosetting sheet. It should be noted that when the surface treatment agent for the silver particles is an epoxy-based coating agent, the thermosetting resin contained in the thermosetting sheet is preferably an epoxy resin. This further improves the affinity between the aforementioned silver particles and the aforementioned thermosetting resin, thus further dispersing the aforementioned silver particles in the thermosetting sheet. As a result, the thermal conductivity (heat dissipation) of the thermosetting sheet can be further improved.

[0081] In addition to silver particles, the aforementioned conductive particles may also include nickel particles, copper particles, aluminum particles, carbon black, carbon nanotubes, particles formed by coating the surface of metal particles that form the core (core) with metals such as gold or silver (hereinafter also referred to as plated metal particles), and particles formed by coating the surface of resin particles that form the core (core) with metal (hereinafter also referred to as metal-coated resin particles). These conductive particles may be used in combination or in combination of two or more types.

[0082] As for the plated metal particles, for example, particles made by using nickel or copper particles as a core and plating the surface of the core with precious metals such as gold or silver can be used.

[0083] As metal-coated resin particles, for example, particles formed by using resin particles as a core and coating the surface of the core with metals such as nickel or gold can be used.

[0084] In this embodiment, when the thermosetting sheet contains conductive particles other than silver particles, plated metal particles are preferably used as the conductive particles. Among these, particles with a copper core and silver plating on the surface of the core (silver-coated copper particles) are preferred. Commercially available silver-coated copper particles include those manufactured by Mitsui Metals Industry Co., Ltd. under the trade name 1200YP, and those manufactured by DOWA ELECTRONICS MATERIALS CO.LTD. under the trade name AOP-TCY-2(EN).

[0085] In this embodiment, when the thermosetting sheet contains conductive particles other than silver particles, the mass percentage of silver particles in 100% by mass of conductive particles is preferably 10% by mass or more and 95% by mass or less, more preferably 20% by mass or more and 90% by mass or less.

[0086] For the shape of conductive particles other than silver, for example, flake-shaped, needle-shaped, filament-shaped, spherical, and flat (including scale-like) particles can be used. Among these, from the viewpoint of increasing the contact area with the aforementioned silver particles by increasing the specific surface area, flat particles are preferred. It should be noted that the product 1200YP manufactured by Mitsui Metals Industry Co., Ltd. is a flat conductive particle.

[0087] The preferred conductive particles, other than silver particles, have an average particle size D. 50 The size is 0.01 μm or more and 20 μm or less, more preferably 0.05 μm or more and 10 μm or less.

[0088] The average particle size D of conductive particles other than silver particles 50 It can also be compared with the average particle size D of the above silver particles. 50 The same procedure is used to determine this.

[0089] From the viewpoint of ensuring sufficient curing reaction of the resin components or increasing the curing reaction rate, the thermosetting sheet of this embodiment may contain a thermosetting catalyst. Examples of thermosetting catalysts include imidazole compounds, triphenylphosphine compounds, amine compounds, and trihaloborane compounds.

[0090] The viscosity of the thermosetting sheet in this embodiment at 100°C is 20 kPa·s or more and 3000 kPa·s or less.

[0091] By making the viscosity at 100°C above 20 kPa·s and below 3000 kPa·s, the wettability to the adherend (e.g., semiconductor wafer) can be improved, thereby ensuring sufficient adhesion to the aforementioned adherend.

[0092] Therefore, it is possible to relatively suppress the stripping of semiconductor components.

[0093] In particular, when the aforementioned thermosetting sheet is cut in a state of being attached to one side of a semiconductor wafer to obtain multiple thermosetting sheets with semiconductor elements attached to one side, the peeling of the aforementioned semiconductor elements from the aforementioned thermosetting sheet can be relatively suppressed.

[0094] Viscosity at 100°C can be evaluated using a rheometer (HAAKE MARS rotary rheometer manufactured by Thermo Fisher Scientific Inc.). Specifically, when heating from 30°C to 180°C at a heating rate of 10°C / min, the viscosity can be obtained by reading the value indicated at 100°C.

[0095] The thermosetting sheet of this embodiment may also contain volatile components.

[0096] The thermosetting sheet of this embodiment preferably contains 5% by mass and less than 50% by mass of the aforementioned volatile components relative to the total mass of the organic components (thermosetting resin, thermoplastic resin, volatile components) contained in the aforementioned thermosetting sheet, and more preferably contains 10% by mass and less than 40% by mass.

[0097] As volatile components, examples include organic compounds containing one or more hydroxyl groups and having a boiling point of 250°C or higher. The boiling point of such organic compounds is preferably 350°C or lower. Terpenes are examples of such organic compounds. Among terpenes, isobornylcyclohexanol, represented by formula (1), is preferred as a volatile component. It should be noted that isobornylcyclohexanol is an organic compound with a boiling point of 308–318°C. When heated from room temperature (23 ± 2°C) to 600°C under a nitrogen flow of 200 mL / min at a heating rate of 10°C / min, it exhibits the property of significant weight reduction from above 100°C, volatilization at 245°C (further weight reduction cannot be confirmed), and extremely high viscosity of 1,000,000 mPa·s at 25°C, but relatively low viscosity of less than 1,000 mPa·s at 60°C. It should be noted that the weight reduction is the value assuming a weight reduction rate of 0% at the initial measurement temperature (room temperature).

[0098] As described above, isobornylcyclohexanol exhibits extremely high viscosity at 25°C, thus maintaining its sheet shape at room temperature, but exhibits lower viscosity at 60°C, thus becoming viscous. In other words, thermosetting sheets containing isobornylcyclohexanol exhibit excellent sheet shape retention at room temperature and become viscous at temperatures above 60°C.

[0099] Here, when mounting a semiconductor element attached to one side of a thermosetting sheet to a metal lead frame or the like, the semiconductor element is typically temporarily bonded (temporarily fixed) to the metal lead frame or the like at a temperature of 60–80°C using the thermosetting sheet. However, since isoborneol has adhesive properties above 60°C as described above, in this embodiment, when the thermosetting sheet contains isoborneol as a volatile component, the temporary adhesion of the thermosetting sheet to the metal lead frame or the like is further improved. That is, in the temporarily bonded state, it is possible to prevent the semiconductor element from shifting out of its mounting position or the thermosetting sheet from lifting off the like.

[0100] Therefore, when using thermosetting sheets to heat-cure semiconductor components to bond them to the substrate, bonding can be performed with high reliability.

[0101]

[0102] For the thermosetting sheet of this embodiment, the particle filling rate P of the aforementioned conductive particles in the aforementioned 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.

[0103] The aforementioned particle filling rate P is preferably 70% by volume or less, more preferably 60% by volume or less.

[0104] By ensuring that the particle filling rate P meets the aforementioned numerical range, the heat dissipation of the cured thermosetting sheet can be further improved.

[0105] The aforementioned particle filling rate P can be calculated using the following steps.

[0106] (1) Mechanically grind the cured thermosetting sheet to expose the cross section, and then perform ion polishing on the exposed cross section using an ion polishing device (e.g., Nippon Electric Co., Ltd., trade name: Cross section polisher SM-09010).

[0107] (2) Using a field emission scanning electron microscope (e.g., Hitachi High Technology Co., Ltd., trade name SU8020), SEM images (images obtained by scanning electron microscope) are captured in any cross-sectional area of ​​the exposed section after ion polishing, and the reflected electron images are obtained as image data. The imaging conditions can be set to an accelerating voltage of 5kV and a magnification of 5000x.

[0108] (3) For the obtained image data, use image analysis software (such as ImageJ) to perform automatic binarization processing to divide the metal part and the resin part.

[0109] (4) Calculate the total area of ​​the conductive particles and the total area of ​​the whole (conductive particles + resin) from the binarized image. Divide the total area of ​​the conductive particles by the total area of ​​the whole to calculate the particle filling rate P of the conductive particles on the cured thermosetting sheet.

[0110] It should be noted that the particle filling rate P of the conductive particles is preferably calculated by taking the arithmetic mean of the filling rates of five cross-sectional areas in the exposed cross-section that has undergone ion polishing.

[0111] The thickness of the thermosetting sheet in this embodiment is preferably 5 μm or more, more preferably 10 μm or more, and even more preferably 20 μm or more. Furthermore, the thickness of the thermosetting sheet is preferably 150 μm or less, more preferably 100 μm or less, and even more preferably 80 μm or less.

[0112] By reducing the thickness of the thermosetting sheet to less than 150 μm, thermal conductivity (heat dissipation) can be further improved.

[0113] The thickness of a thermosetting sheet can be calculated, for example, by measuring the thickness at five randomly selected points using a dial indicator (manufactured by PEACOCK, model R-205) and then taking the arithmetic mean of these thicknesses.

[0114] The thermosetting sheet of this embodiment preferably has a thermal conductivity of 3 W / m·K or higher after curing, more preferably 10 W / m·K or higher.

[0115] By ensuring that the thermal conductivity after curing meets the above-mentioned value range, the electrical conductivity of the aforementioned thermosetting sheet after curing can be further improved.

[0116] It should be noted that in the thermosetting sheet of this embodiment, the upper limit of the thermal conductivity after curing is usually 100 W / m·K.

[0117] The thermal conductivity after curing can be calculated as follows: The thermosetting sheet of this embodiment is heat-cured by applying a pressure of 0.5 MPa to the edge of a pressure cooker device and treating it at 200°C for 1 hour. The thermally cured thermosetting sheet is calculated using the following formula.

[0118] Thermal conductivity (W / m·K) = thermal diffusivity (m 2 / s)×Specific heat (J / g·℃)×Specific gravity (g / cm³) 3 )

[0119] The thermal diffusivity (m) in the above formula 2 / s) can be measured using the TWA method (Temperature Wave Thermal Analysis, measuring device: ai-Phase Mobile, manufactured by ai-Phase Co.).

[0120] Furthermore, the specific heat (J / g·℃) in the above formula can be determined by the DSC method. The specific heat determination can be carried out using a DSC6220 manufactured by SIINanotechnology at a heating rate of 10℃ / min and a temperature range of 20–300℃. Based on the obtained data, the specific heat is calculated using the method described in the JIS manual (Specific Heat Capacity Determination Method K-7123).

[0121] Furthermore, the specific gravity in the above formula can be determined using the Archimedes method.

[0122] In this embodiment, the peeling force of the thermosetting sheet relative to the silicon wafer at room temperature (23±2℃) is preferably 1N / 10mm or more, more preferably 5N / 10mm or more, and even more preferably 10N / 10mm or more.

[0123] Furthermore, the peeling force of the thermosetting sheet relative to the silicon wafer at room temperature (23±2°C) in this embodiment is preferably 20N / 10mm or less, more preferably 15N / 10mm or less.

[0124] By ensuring that the peeling force relative to the silicon wafer meets the above-mentioned numerical range, it is possible to further suppress the peeling of semiconductor components during dicing.

[0125] Peel force relative to silicon wafers at room temperature can be determined using a tensile testing machine (trade name: Autograph AG-X, manufactured by Shimadzu Corporation) by a peel test under the conditions of room temperature (23±2℃), peel angle of 180°, and tensile speed of 300 mm / min.

[0126] Specifically, the following steps can be taken to determine this.

[0127] (1) A thermosetting sheet is superimposed on one surface of a silicon wafer (bare wafer) to obtain a laminate.

[0128] (2) The laminate is placed on a hot plate heated to 70°C. It should be noted that the aforementioned laminate is arranged such that the surface of the silicon wafer is in contact with the surface of the hot plate.

[0129] (3) Press the aforementioned laminate using a pressing roller (2kg) to form a state in which the silicon wafer and the thermosetting sheet are bonded together, and place it on a hot plate for 2 minutes.

[0130] (4) Remove the aforementioned laminate from the hot plate and place it at room temperature (23±2℃) for 20 minutes to obtain the test body.

[0131] (5) For the aforementioned test specimen, a peel test was performed using the aforementioned tensile testing machine under the aforementioned conditions, thereby determining the peel force relative to the silicon wafer at room temperature.

[0132] The thermosetting sheet of this embodiment may also contain one or more other components as needed. Examples of other components include filler dispersants, flame retardants, silane coupling agents, and ion trapping agents.

[0133] [Cutting chip bonding film]

[0134] Next, refer to Figure 1 The die-cutting bonding film 20 will be described below. It should be noted that in the following description, parts that overlap with thermosetting sheets will not be repeated.

[0135] like Figure 1 As shown, the chip bonding film 20 of this embodiment includes a substrate layer 1, a cutting strip 10 on which an adhesive layer 2 is stacked, and a thermosetting sheet 3 on the adhesive layer 2 of the cutting strip 10.

[0136] A die bonding film 20 is cut and attached to a semiconductor device on a thermosetting sheet 3. The semiconductor device can be a bare wafer.

[0137] The bare wafer attached to the die bonding film 20 of this embodiment is cut into multiple bare chips by blade cutting, DBG (Dicing Before Grinding), or SDBG (Stealth Dicing Before Grinding). Furthermore, during the cutting process as described above, the thermosetting sheet 3 is also cut along with the bare wafer. The thermosetting sheet 3 is cut to a size comparable to the dimensions of the multiple monolithically formed bare chips. Thus, multiple bare chips with thermosetting sheets 3 can be obtained.

[0138] The thermosetting sheet 3 of the chip bonding film 20, as described above, is a thermosetting sheet comprising a thermosetting resin, a thermoplastic resin, and conductive particles, wherein the conductive particles have an average particle size D.50 Silver particles with a size of 0.01 μm or larger and 10 μm or smaller, a cross-sectional roundness of 0.7 or larger, and a viscosity of 20 kPa·s or larger and 3000 kPa·s or smaller.

[0139] The substrate layer 1 supports the adhesive layer 2 and the thermosetting sheet 3 laminated on the adhesive layer 2. The substrate layer 1 contains resin. Examples of resins include: olefin resins such as polyethylene (PE), polypropylene (PP), and ethylene-propylene copolymer; copolymers with ethylene as a monomer component such as ethylene-vinyl acetate copolymer (EVA), ionomer resin, ethylene-(meth)acrylic acid copolymer, and ethylene-(meth)acrylic acid (random, alternating) copolymer; polyesters such as polyethylene terephthalate (PET), polyethylene naphthalate (PEN), and polybutylene terephthalate (PBT); acrylic resins; polyvinyl chloride (PVC); polyurethane; polycarbonate; polyphenylene sulfide (PPS); amide resins such as polyamide and fully aromatic polyamide (aramid); polyetheretherketone (PEEK); polyimide; polyetherimide; polyvinylidene chloride; ABS (acrylonitrile-butadiene-styrene copolymer); cellulose resins; silicone resins; fluoropolymers, etc.

[0140] Among these, polyethylene terephthalate is preferred.

[0141] The substrate layer 1 may contain one of the aforementioned resins or two or more of the aforementioned resins.

[0142] Examples of materials for the substrate layer 1 include polymers such as crosslinked resins (e.g., plastic films). These plastic films can be used without stretching, or films that have undergone unidirectional or bidirectional stretching as needed. By using a resin sheet that has been given heat-shrinkability through stretching or similar processes, and by heat-shrinking the substrate layer 1 after cutting, the bonding area between the adhesive layer 2 and the thermosetting sheet 3 can be reduced, thereby facilitating the recycling of the semiconductor chip (semiconductor element).

[0143] For the surface of substrate layer 1, conventional surface treatments can be performed to improve adhesion and retention with adjacent layers. Examples of such surface treatments include chemical or physical treatments such as chromic acid treatment, ozone exposure, flame exposure, high-voltage electric shock exposure, and ionizing radiation treatment, as well as coating treatments using a primer.

[0144] The thickness of the substrate layer 1 is preferably 1 μm or more and 1000 μm or less, more preferably 10 μm or more and 500 μm or less, even more preferably 20 μm or more and 300 μm or less, and particularly preferably 30 μm or more and 200 μm or less.

[0145] The thickness of the substrate layer 1 can be determined using a dial indicator (PEACOCK R-205) in the same way as the thickness of the thermosetting sheet 3.

[0146] The substrate layer 1 may contain various additives. Examples of such additives include: colorants, fillers, plasticizers, antioxidants, surfactants, flame retardants, etc.

[0147] There are no particular limitations on the adhesive used to form adhesive layer 2; for example, conventional pressure-sensitive adhesives such as acrylic adhesives and rubber adhesives can be used. However, from the viewpoint of the cleanability of semiconductor wafers, glass, and other electronic components susceptible to contamination using ultrapure water, organic solvents such as alcohols, acrylic adhesives with acrylic polymers as the base polymer are preferred as the aforementioned pressure-sensitive adhesive.

[0148] Examples of the aforementioned acrylic polymers include acrylic polymers that use one or more of alkyl (meth)acrylates and cycloalkyl (meth)acrylates as monomer components. Examples of alkyl (meth)acrylates include methyl esters, ethyl esters, propyl esters, isopropyl esters, butyl esters, isobutyl esters, sec-butyl esters, tert-butyl esters, pentyl esters, isopentyl esters, hexyl esters, heptyl esters, octyl esters, 2-ethylhexyl esters, isooctyl esters, nonyl esters, decyl esters, isodecanyl esters, undecyl esters, dodecyl esters, tridecyl esters, tetradecyl esters, hexadecyl esters, octadecyl esters, and eicosyl esters, which are straight-chain or branched alkyl esters with 1 to 30 carbon atoms, particularly 4 to 18 carbon atoms. Examples of cycloalkyl (meth)acrylates include cyclopentyl esters and cyclohexyl esters.

[0149] It should be noted that (meth)acrylate refers to at least one of acrylate and methacrylate, and the (methyl) in this invention has the same meaning as described above.

[0150] The aforementioned acrylic polymers are intended to modify cohesion, heat resistance, etc., and may, as needed, contain units corresponding to other monomer components that can be copolymerized with the aforementioned alkyl methacrylates or cycloalkyl methacrylates. Examples of such monomeric components include: acrylic acid, methacrylic acid, carboxyethyl methacrylate, carboxypentyl methacrylate, itaconic acid, maleic acid, fumaric acid, crotonic acid, and other carboxyl-containing monomers; maleic anhydride, itaconic anhydride, and other anhydride monomers; 2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate, 4-hydroxybutyl methacrylate, 6-hydroxyhexyl methacrylate, 8-hydroxyoctyl methacrylate, 10-hydroxydecyl methacrylate, 12-hydroxylauryl methacrylate, methyl methacrylate (4-hydroxymethylcyclohexyl) methacrylate, and other hydroxyl-containing monomers; styrene sulfonic acid, allyl sulfonic acid, 2-(meth)acrylamide-2-methylpropanesulfonic acid, (meth)acryloyloxynaphthalene sulfonic acid, (meth)acrylic acid sulfopropyl ester, (meth)acryloyloxynaphthalene sulfonic acid, and other sulfonic acid monomers; 2-hydroxyethylacryloyl phosphate and other phosphate-containing monomers; acrylamide, acrylonitrile, etc. One or more copolymerizable monomers may be used. The amount of these copolymerizable monomers is preferably less than 40% by mass of all monomer components.

[0151] Furthermore, to facilitate crosslinking, the aforementioned acrylic polymers may, as needed, include multifunctional monomers as copolymerizing monomers. Examples of such multifunctional monomers include: hexanediol dimethacrylate, polyethylene glycol dimethacrylate, polypropylene glycol dimethacrylate, neopentyl glycol dimethacrylate, pentaerythritol dimethacrylate, trimethylolpropane trimethacrylate, pentaerythritol trimethacrylate, dipentaerythritol hexamethacrylate, epoxy methacrylate, polyester methacrylate, and urethane methacrylate. One or more of these multifunctional monomers may be used. From the viewpoint of adhesive properties, the amount of multifunctional monomer used is preferably 30% by mass or less of the total monomer composition.

[0152] The aforementioned acrylic polymers can be obtained by polymerizing a single monomer or a mixture of two or more monomers. Polymerization can be carried out by any method, such as solution polymerization, emulsion polymerization, bulk polymerization, or suspension polymerization. From the viewpoint of preventing contamination of the clean adherend, it is preferable to have a lower content of low molecular weight substances. Therefore, the number average molecular weight of the acrylic polymer is preferably 300,000 or higher, and more preferably around 400,000 to 3,000,000.

[0153] Furthermore, in the aforementioned adhesives, an external crosslinking agent can be appropriately added to increase the number-average molecular weight of the acrylic polymer or similar base polymer. Specific methods for external crosslinking include reacting with crosslinking agents such as polyisocyanate compounds, epoxy compounds, aziridine compounds, and melamine-based crosslinking agents. When using an external crosslinking agent, its dosage is appropriately determined considering the balance with the base polymer to be crosslinked and its intended use as an adhesive. Generally, the external crosslinking agent is preferably mixed in at least about 5 parts by weight relative to 100 parts by weight of the aforementioned base polymer, more preferably in the form of 0.1 to 5 parts by weight.

[0154] In addition to the aforementioned components, adhesives may also contain various known tackifiers, antioxidants, and other additives as needed.

[0155] The adhesive layer 2 can be formed from a radiation-curing adhesive. Radiation-curing adhesives can increase their cross-linking degree by irradiation with radiation such as ultraviolet light, thereby easily reducing their adhesive strength. That is, by forming the adhesive layer 2 with a radiation-curing adhesive, the thermosetting sheet 3 is fully bonded to the adhesive layer 2 without irradiating it before cutting, and after cutting, the adhesive layer 2 is irradiated with radiation to reduce its adhesive strength, thereby making it easy to pick up (recycle) the semiconductor chip (semiconductor device).

[0156] Radiation-curing adhesives can be used without particular restrictions as long as they possess radiation-curing functional groups such as carbon-carbon double bonds and exhibit adhesive properties. Examples of radiation-curing adhesives include additive-type radiation-curing adhesives obtained by blending radiation-curing monomeric components and oligomer components into conventional pressure-sensitive adhesives such as acrylic adhesives and rubber adhesives.

[0157] Examples of the aforementioned radiation-curable monomer components 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. Furthermore, examples of the aforementioned radiation-curable oligomer components include: various oligomers such as urethane-based, polyether-based, polyester-based, polycarbonate-based, and polybutadiene-based oligomers, preferably with a molecular weight in the range of approximately 100 to 30,000. The mixing amounts of the aforementioned radiation-curable monomer components and the aforementioned radiation-curable oligomer components are preferably chosen to appropriately reduce the adhesive strength of the adhesive layer 2 after irradiation with radiation. Generally speaking, relative to 100 parts by weight of the base polymer such as acrylic polymer constituting the adhesive, the mixing amount of the aforementioned radiation-curable monomer component and the aforementioned radiation-curable oligomer component is preferably 5 to 500 parts by weight, more preferably 40 to 150 parts by weight.

[0158] Furthermore, in addition to the aforementioned additive-type radiation-curing adhesives, intrinsic radiation-curing adhesives can also be cited as examples of radiation-curing adhesives. These intrinsic radiation-curing adhesives use polymers with carbon-carbon double bonds in the polymer side chains or main chains, or at the ends of the main chains, as the base polymer. The aforementioned intrinsic radiation-curing adhesives do not need to contain oligomer components that are low molecular weight components, or the content of such oligomer components is relatively low. Therefore, when using the aforementioned intrinsic radiation-curing adhesives, the migration of such oligomer components within the adhesive layer 2 over time can be suppressed. As a result, the adhesive layer 2 can have a more stable layer structure.

[0159] The aforementioned base polymers with carbon-carbon double bonds can be used without particular restrictions as long as they possess carbon-carbon double bonds and adhesive properties. Polymers with acrylic polymers as their basic backbone are preferred as such base polymers. Examples of acrylic polymers mentioned above can be cited as examples of basic acrylic polymer backbones.

[0160] There are no particular limitations on the methods for introducing carbon-carbon double bonds into the aforementioned acrylic polymers; various methods can be used. However, if the method of introducing carbon-carbon double bonds into the polymer side chains is adopted, molecular design becomes easier. For example, the following method can be listed: after copolymerizing the acrylic polymer with a monomer having a functional group, a compound having a functional group that can react with that functional group and a carbon-carbon double bond is subjected to a condensation reaction or an addition reaction while maintaining the radiation-curable nature of the carbon-carbon double bond.

[0161] Examples of combinations of these functional groups include: carboxylic acid group and epoxy group, carboxylic acid group and aziridinyl group, hydroxyl group and isocyanate group, etc. Among these combinations of functional groups, the combination of hydroxyl group and isocyanate group is preferable from the perspective of ease of reaction tracking. Furthermore, as long as the combination of these functional groups results in the formation of the aforementioned acrylic polymer having carbon-carbon double bonds, any functional group can be located on the acrylic polymer side or the aforementioned compound having carbon-carbon double bonds side. However, in the case of the preferred combination described above, it is preferable that the acrylic polymer has a hydroxyl group and the aforementioned compound having carbon-carbon double bonds has an isocyanate group. In this case, examples of isocyanate compounds having carbon-carbon bonds include: methacryloyl isocyanate, 2-methacryloyloxyethyl isocyanate, and m-isopropenyl-α,α-dimethylbenzyl isocyanate, etc. Furthermore, as the acrylic polymer, polymers obtained by copolymerizing the aforementioned hydroxyl-containing monomers, 2-hydroxyethyl vinyl ether, 4-hydroxybutyl vinyl ether, diethylene glycol monovinyl ether, etc., can be used.

[0162] The aforementioned intrinsic radiation-curing adhesive can be made using the aforementioned base polymer (especially acrylic polymers) with carbon-carbon double bonds alone, or it can be blended with the aforementioned radiation-curing monomer components and the aforementioned radiation-curing oligomer components to a degree that does not degrade the properties. Typically, the aforementioned radiation-curing oligomer components, etc., are included in the range of 30 parts by weight or less relative to 100 parts by weight of the base polymer, preferably in the range of 1 to 10 parts by weight.

[0163] In the aforementioned radiation-curing adhesives, a photopolymerization initiator is contained when curing is performed using ultraviolet light or the like. Examples of photopolymerization initiators include: α-keto alcohol compounds such as 4-(2-hydroxyethoxy)phenyl(2-hydroxy-2-propyl) ketone, α-hydroxy-α,α'-dimethylacetophenone, 2-methyl-hydroxyacetophenone, and 1-hydroxycyclohexylphenyl ketone; acetophenone compounds such as methoxyacetophenone, 2,2-dimethoxy-2-phenylacetophenone, 2,2-diethoxyacetophenone, and 2-methyl-1-[4-(methylthio)-phenyl]-2-morpholinylpropane-1; benzoin ether compounds such as benzoin ethyl ether, benzoin isopropyl ether, and anisole methyl ether; and benzoin dimethyl ketal. Ketal compounds; aromatic sulfonyl chloride compounds such as 2-naphthalenesulfonyl chloride; photoactive oxime compounds such as 1-benzophenone-1,1-propanedione-2-(O-ethoxycarbonyl)oxime; benzophenone compounds such as benzoylbenzoic acid and 3,3'-dimethyl-4-methoxybenzophenone; thioxanthone compounds such as 2-chlorothioxanthone, 2-methylthioxanthone, 2,4-dimethylthioxanthone, isopropylthioxanthone, 2,4-dichlorothioxanthone, 2,4-diethylthioxanthone, and 2,4-diisopropylthioxanthone; camphorquinone; halogenated ketones; acylphosphine oxides; acylphosphonates, etc. The amount of photopolymerization initiator mixed with the base polymer, such as the acrylic polymer constituting the adhesive, is, for example, 0.05 to 20 parts by weight.

[0164] Furthermore, examples of radiation-curing adhesives include rubber-based adhesives and acrylic adhesives disclosed in Japanese Patent Application Publication No. 60-196956. These rubber-based adhesives and acrylic adhesives contain addition polymerizable compounds having two or more unsaturated bonds, photopolymerizable compounds such as alkoxysilanes with epoxy groups, and photopolymerization initiators such as carbonyl compounds, organosulfur compounds, peroxides, amines, and onium salt compounds.

[0165] When radiation is applied, if oxygen-induced curing inhibition occurs, it is ideal to block oxygen (air) from the surface of the radiation-curing adhesive layer 2 using some method. Examples include: coating the surface of the adhesive layer 2 with an isolator, or irradiating it with ultraviolet radiation in a nitrogen atmosphere.

[0166] The thickness of the adhesive layer 2 is not particularly limited, but from the viewpoint of balancing the prevention of chip cutting surface defects and the fixation 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.

[0167] The matters disclosed in this specification include the following. (1)

[0169] A thermosetting sheet comprising a thermosetting resin, a thermoplastic resin, and conductive particles.

[0170] The aforementioned conductive particles include an average particle size D 50 Silver particles with a diameter of 0.01 μm or larger and a diameter of 10 μm or smaller, and a cross-sectional circularity of 0.7 or larger.

[0171] The aforementioned thermosetting sheet has a viscosity of 20 kPa·s or higher and 3000 kPa·s or lower at 100°C.

[0172] Using this configuration, the aforementioned conductive particles, due to their average particle size D 50 Since the silver particles are less than 10 μm, they can be melted at a temperature (e.g., 200°C) that is sufficient to cure the aforementioned thermosetting resin to the point that the outer surface of the aforementioned silver particles can be sintered.

[0173] Furthermore, due to the average particle size D of the aforementioned silver particles 50 With a diameter of 0.01 μm or larger, the silver particles are not only more easily dispersed in the thermosetting sheet, but also the surface of the silver particles is more susceptible to oxidation due to excessively large specific surface area, thus ensuring sufficient conductivity of the silver particles.

[0174] Therefore, it is possible to melt the silver particles in a state that is sufficiently conductive and sufficiently dispersed to the extent that the outer surface of the silver particles can be sintered. Thus, it is possible to use the aforementioned silver particles to sinter the aforementioned conductive particles together.

[0175] Furthermore, since the sphericity of the silver particles at the cross-section is 0.7 or higher, the silver particles can be more fully dispersed in the thermosetting sheet. Therefore, by utilizing the silver particles that are fully dispersed in the thermosetting sheet, the conductive particles can be sintered together.

[0176] As described above, after curing, the thermosetting sheet of the present invention has sufficient electrical conductivity and high heat dissipation.

[0177] Furthermore, since the viscosity at 100°C is above 20 kPa·s and below 3000 kPa·s, the wettability to the adhered object (e.g., semiconductor wafer) can be improved, thereby ensuring sufficient adhesion to the aforementioned adhered object.

[0178] Furthermore, since it contains thermoplastic resin, it can be easily adjusted to achieve the viscosity within the aforementioned range at 100°C, and it can also achieve lower elasticity after curing.

[0179] Therefore, it is possible to relatively suppress the stripping of semiconductor components.

[0180] Based on the above, the thermosetting sheet of the present invention can relatively suppress the peeling of semiconductor elements, and has high heat dissipation after curing. (2)

[0182] According to the thermosetting sheet described in (1) above, the particle filling rate P of the aforementioned conductive particles in the cured thermosetting sheet is 30% by volume or more.

[0183] This configuration can further improve the heat dissipation of the aforementioned thermosetting sheet after curing. (3)

[0185] According to the thermosetting sheet described in (2) above, the particle filling rate P of the aforementioned conductive particles in the cured thermosetting sheet is less than 70% by volume. (4)

[0187] The thermosetting sheet according to any one of (1) to (3) above, wherein the thermal conductivity after curing is 3 W / m·K or higher.

[0188] This configuration can further improve the electrical conductivity of the aforementioned thermosetting sheet after curing. (5)

[0190] According to the thermosetting sheet described in (4) above, the thermal conductivity after curing is less than 100 W / m·K. (6)

[0192] The thermosetting sheet according to any one of (1) to (5) above, wherein the peeling force relative to the silicon wafer at room temperature is 1 N / 10 mm or more.

[0193] This configuration can further suppress the stripping of semiconductor components. (7)

[0195] According to the thermosetting sheet described in (6) above, the peeling force relative to the silicon wafer at room temperature is less than 20 N / 10 mm. (8)

[0197] The thermosetting sheet according to any one of (1) to (7) above contains volatile components.

[0198] The aforementioned volatile components contain more than one hydroxyl group and have a boiling point of 250°C or higher.

[0199] This configuration can further improve the heat dissipation of the aforementioned thermosetting sheet after curing. (9)

[0201] According to the thermosetting sheet described in (8) above, the aforementioned volatile component is a terpene compound.

[0202] This configuration can further improve the heat dissipation of the aforementioned thermosetting sheet after curing. (10)

[0204] According to the thermosetting sheet described in (9) above, the aforementioned terpene compound is isobornylcyclohexanol represented by the following formula (1).

[0205]

[0206] This configuration further enhances temporary adhesion to substrates such as metal lead frames. Specifically, in a temporary bonded state, it prevents misalignment of semiconductor components or the thermosetting sheet from lifting off the substrate.

[0207] Therefore, when thermosetting sheets are thermosetting to bond semiconductor components to the substrate, bonding can be performed with high reliability. (11)

[0209] A chip bonding film comprising:

[0210] Substrate layer

[0211] A cutting strip with an adhesive layer is laminated on the substrate layer, and

[0212] A thermosetting sheet is laminated on the adhesive layer of the aforementioned cutting strip.

[0213] The aforementioned thermosetting sheet is any one of (1) to (10) above.

[0214] Using this configuration, the aforementioned chip bonding film has the ability to relatively suppress the peeling of semiconductor elements and has high heat dissipation after curing.

[0215] It should be noted that the thermosetting sheet and the die-cutting chip bonding film of the present invention are not limited to the foregoing embodiments. Furthermore, the thermosetting sheet and the die-cutting chip bonding film of the present invention are not limited by the aforementioned effects. Various modifications can be made to the thermosetting sheet and the die-cutting chip bonding film of the present invention without departing from the spirit of the present invention.

[0216] Example

[0217] Next, embodiments will be given to illustrate the invention in more detail. The following embodiments are examples used to illustrate the invention in more detail and do not limit the scope of the invention.

[0218] [Example 1]

[0219] Using a mixing mixer (Keyence Corporation, trade name: HM-500), the mixture containing each material was stirred for 3 minutes according to the mass ratio shown in Example 1 of Table 1 below to prepare a varnish. This varnish was then applied to one side of a release film (Mitsubishi Chemical Corporation, trade name: MRA38, thickness 38 μm) and dried at 100°C for 2 minutes to obtain a thermosetting sheet with a thickness of 30 μm.

[0220] It should be noted that the following substances are used as the materials shown in Table 1 below.

[0221] ·Phenolic resin

[0222] MEHC-7851S (biphenyl-type phenolic resin, phenol equivalent 209 g / eq) manufactured by Meiwa Chemical Co., Ltd.

[0223] Solid epoxy resin

[0224] KI-3000-4 (cresol phenolic varnish type multifunctional epoxy resin, epoxy equivalent 200g / eq) manufactured by Nippon Steel & Sumitomo Chemical Co., Ltd.

[0225] Liquid epoxy resin

[0226] EXA-4816 (Aliphatic modified bisphenol A type epoxy resin (2-functional), epoxy equivalent 403 g / eq) manufactured by DIC Corporation

[0227] Silver (Ag) coated copper (Cu) particles

[0228] Mitsui Metals & Mining manufactures 1200YP (particles formed by coating flat copper particles with 10% by mass of silver particles, average particle size 3.5μm, amorphous).

[0229] Silver (Ag) particles

[0230] HP02A (silver particles with a surface treatment using a fatty acid-based coating agent) manufactured by Mitsui Metals & Mining Co., Ltd.

[0231] • Volatile material (Isoborneol (MTPH))

[0232] MTPH manufactured by Nippon Terpene Chemicals, Inc.

[0233] Acrylic resin solutions

[0234] Teisan Resin SG-70L, manufactured by Nagase ChemteX Corporation (contains MEK and toluene as a solvent, 12.5% ​​solids, glass transition temperature -13°C, mass-average molecular weight 900,000, acid value 5 mg / KOH, a carboxyl-containing acrylic copolymer).

[0235] Coupling agents

[0236] KBE-846 (bis(triethoxysilylpropyl)tetrasulfide) manufactured by Shin-Etsu Chemical Co., Ltd.

[0237] ·catalyst

[0238] TPP-K (tetraphenylborone tetraphenylphosphine) manufactured by Hokuko Chemical Industry Co., Ltd.

[0239] Solvent

[0240] Methyl ethyl ketone (MEK)

[0241] Furthermore, the mass percentages of the conductive particles (silver-coated copper particles and silver particles) in 100 parts by mass, the mass percentages of the epoxy resin (solid and liquid) in 100 parts by mass of the thermosetting sheet, the mass percentages of the phenolic resin in 100 parts by mass of the thermosetting sheet, the mass percentages of the acrylic resin in 100 parts by mass of the thermosetting sheet, and the mass percentages of the isoborneol in 100 parts by mass of the organic components (phenolic resin, epoxy resin (solid and liquid), acrylic resin solution, isoborneol) are shown in Table 2 below.

[0242] [Example 2]

[0243] Using a modified coating (epoxy coating) of HP02A manufactured by Mitsui Metal Mining Co., Ltd. with silver particles, TPP-K as a catalyst, and a mixture of materials containing each material in the mass ratio shown in one of the items in Example 2 of Table 1 below, the same procedure as in Example 1 was followed to obtain the thermosetting sheet of Example 2.

[0244] [Example 3]

[0245] Using a mixture of materials containing TPP-K (which does not contain a catalyst) in the mass proportions shown in one of the items in Example 3 of Table 1 below, the thermosetting sheet of Example 3 was obtained in the same manner as in Example 1.

[0246] [Example 4]

[0247] Using HP02 manufactured by Mitsui Metal Mining Co., Ltd. as silver particles, without TPP-K as a catalyst, and a mixture containing each material in the mass ratio shown in Example 4 of Table 1 below, the thermosetting sheet of Example 4 was obtained in the same manner as in Example 1.

[0248] [Example 5]

[0249] Using AG-2-8F (silver particles surface-treated with a fatty acid-based coating agent) manufactured by DOWA ELECTRONICS MATERIALS CO.LTD., and AOP-TCY-2(EN) manufactured by DOWA ELECTRONICS MATERIALS CO.LTD., a mixture of the materials was prepared in the same mass ratio as shown in Example 5 of Table 1 below, except that the process was the same as in Example 1 to obtain the thermosetting sheet of Example 5.

[0250] [Comparative Example 1]

[0251] Thermosetting sheet of Comparative Example 1 was obtained by using a mixture of silver particles manufactured by Mitsui Metal Mining Co., Ltd. (SPH02J, aggregated nano-Ag particles, amorphous, with an average particle size of 1.8 μm), without TPP-K as a catalyst, and containing each material in the mass proportions shown in Comparative Example 1 of Table 1 below, except that the operation was the same as in Example 1.

[0252] [Comparative Example 2]

[0253] Using SPH02J manufactured by Mitsui Metal Mining Co., Ltd. as the silver particles, and a mixture of the materials containing each material in the mass ratio shown in Comparative Example 2 of Table 1 below, the same procedure as in Example 1 was followed to obtain the thermosetting sheet of Comparative Example 1.

[0254] [Comparative Example 3]

[0255] Thermosetting sheet of Comparative Example 3 was obtained by using SPH02J manufactured by Mitsui Metal Mining Co., Ltd. as the silver particles, a mixture containing no volatile material (isoborneol cyclohexanol) and each material in the mass proportions shown in Comparative Example 3 in Table 1 below, except that the procedure was the same as in Example 1.

[0256] [Table 1]

[0257] unit Example 1 Example 2 Example 3 Example 4 Example 5 Comparative Example 1 Comparative Example 2 Comparative Example 3 Phenolic resin Quality 1.58 0.98 0.98 1.05 0.74 1.16 1.85 2.03 solid epoxy resin Quality 1.02 0.65 0.65 0.69 0.49 0.92 1.49 1.64 Liquid epoxy resin Quality 0.44 0.28 0.28 0.3 0.21 0.39 0.64 0.7 Ag-coated Cu particles Quality 2.7 12.8 10.5 3.6 13.3 2.5 7.2 22.7 Ag particles Quality 23.9 30 24.6 32.2 30.9 22.7 64.6 7.18 Volatile materials Quality 1.08 1.17 1.17 1.26 0.72 1.52 4.28 - acrylic resin solution Quality 10.4 6.55 6.55 7.01 11.6 8.49 47.89 15 Coupling agent Quality 0.17 0.12 0.12 0.13 0.11 0.15 0.44 0.16 catalyst Quality 0.01 - - - 0.01 - 0.01 0.01 MEK Quality 7.5 17 13 13 9.50 8.5 2.5 13

[0258] <average particle size D of silver (Ag) particles 50 >

[0259] Before mixing, particle size distribution was measured using a laser diffraction / scattering particle size analyzer (manufactured by MicrotracBEL Corp., Microtrac MT3000II series).

[0260] The average particle size D of the silver particles contained in each example of thermosetting sheet was determined. 50 The measurement results are shown in Table 2 below.

[0261] <Sphericity of silver (Ag) particles>

[0262] Each thermosetting sheet was cut along its thickness direction, and SEM images of the cut surfaces were taken. The SEM images were then analyzed using a powder image analysis device (manufactured by SEISHIN ENTERPRISE Co., Ltd., PITA-3) to obtain the results.

[0263] The analysis performed using the powder image analysis device was performed on 10 silver particles randomly selected from the aforementioned SEM image. The roundness can be calculated by taking the arithmetic mean of the roundness values ​​obtained for the 10 silver particles.

[0264] It should be noted that in each example of thermosetting sheet, silver particles and silver (Ag) coated copper (Cu) particles are distinguished by observing the difference in brightness due to the difference in composition using reflective electron imaging.

[0265] The results of the roundness of the silver particles obtained for each example of thermosetting sheet are shown in Table 2 below.

[0266] <Filling rate of conductive particles>

[0267] The particle filling rate P for each thermosetting sheet is determined by following these steps.

[0268] (1) Mechanically grind the cured thermosetting sheet to expose the cross section, and then perform ion polishing on the exposed cross section using an ion polishing device (e.g., Nippon Electric Co., Ltd., trade name: Cross section polisher SM-09010).

[0269] (2) Using a field emission scanning electron microscope SU8020 (manufactured by Hitachi High Technology Co., Ltd.), SEM images (images obtained by scanning electron microscope) were captured in any cross-sectional area of ​​the exposed section after ion polishing. The reflected electron images were used as image data. The imaging conditions can be set to an accelerating voltage of 5kV and a magnification of 5000x.

[0270] (3) For the obtained image data, use the image analysis software ImageJ to perform automatic binarization processing to divide the metal part and the resin part.

[0271] (4) Calculate the total area of ​​the metal part and the area of ​​the whole (metal part + resin part) from the binarized image. Divide the total area of ​​the metal part by the area of ​​the whole to calculate the particle filling rate P of the conductive particles for the cured thermosetting sheet.

[0272] It should be noted that the particle filling rate P of the conductive particles is calculated by taking the arithmetic mean of the particle filling rates obtained from five cross-sectional areas in the exposed cross-section that has undergone ion polishing.

[0273] The particle filling rate P of the conductive particles obtained for each example of thermosetting sheet is shown in Table 2 below.

[0274] <Viscosity of thermosetting sheets at 100°C>

[0275] The viscosity of each thermosetting sheet at 100°C was evaluated using a rheometer (HAAKE MARS rotary rheometer manufactured by Thermo Fisher Scientific Inc.). Specifically, the viscosity was evaluated by reading the value at 100°C while heating from 30°C to 180°C at a heating rate of 10°C / min.

[0276] The viscosity results at 100°C obtained for each example of thermosetting sheet are shown in Table 2 below.

[0277] <Thermosetting sheet thermal conductivity>

[0278] Each thermosetting sheet was heat-cured by applying a pressure of 0.5 MPa to the edges of a pressure cooker and treating it at 200°C for 1 hour. The thermal conductivity of each heat-cured thermosetting sheet was calculated using the following formula.

[0279] Thermal conductivity (W / m·K) = thermal diffusivity (m 2 / s)×Specific heat (J / g·℃)×Specific gravity (g / cm³) 3 )

[0280] Thermal diffusivity α(m) 2 / s) is measured using the TWA method (Temperature Wave Thermal Analysis, measuring device: ai-Phase Mobile, manufactured by ai-Phase Co.).

[0281] Specific heat C pThe specific heat (J / g·℃) was determined by DSC. The specific heat was measured using a DSC6220 manufactured by SII Nanotechnology at a heating rate of 10℃ / min and a temperature range of 20–300℃. Based on the obtained data, the specific heat was calculated using the method described in the JIS manual (Specific Heat Capacity Determination Method K-7123).

[0282] Specific gravity can be determined using the Archimedes method.

[0283] For each example of cured thermosetting sheet, the results of the obtained thermal conductivity are shown in Table 2 below.

[0284] <Peeling force relative to silicon wafers>

[0285] For each thermosetting sheet, the adhesion force relative to the silicon wafer was measured. The peel force relative to the silicon wafer was measured at room temperature (23±2℃). The peel force relative to the silicon wafer was measured using a tensile testing machine (trade name: Autograph AG-X, manufactured by Shimadzu Corporation) under the conditions of room temperature (23±2℃), peel angle of 180°, and tensile speed of 300 mm / min.

[0286] Specifically, the following steps can be taken to determine this.

[0287] (1) A thermosetting sheet is superimposed on one surface of a silicon wafer (bare wafer) to obtain a laminate.

[0288] (2) The laminate is placed on a hot plate heated to 70°C. It should be noted that the aforementioned laminate is arranged such that the surface of the silicon wafer is in contact with the surface of the hot plate.

[0289] (3) Press the aforementioned laminate using a pressing roller (2kg) to form a state in which the silicon wafer and the thermosetting sheet are bonded together, and place it on a hot plate for 2 minutes.

[0290] (4) Remove the aforementioned laminate from the hot plate and place it at room temperature (23±2℃) for 20 minutes to obtain the test body.

[0291] (5) For the aforementioned test specimen, a peel test was performed using the aforementioned tensile testing machine under the aforementioned conditions, thereby determining the peel force relative to the silicon wafer at room temperature.

[0292] The results obtained from measuring the peel force of the thermosetting sheet relative to the silicon wafer for each example are shown in Table 2 below.

[0293] <Peelability during cutting>

[0294] The evaluation of peelability during dicing is performed using a die bonding film and a bare wafer on which a thermosetting sheet is laminated on the adhesive layer of the dicing tape.

[0295] In detail, follow these steps.

[0296] (1) Using a pressing method (pressing roller), press the edge of the bare Si wafer with a thickness of 100μm and a diameter of 8 inches (200mm) onto the aforementioned thermosetting sheet to make it adhere.

[0297] (2) Using a fully automatic cutting saw (DISCO, FULLY AUTOMATIC DICING SAW, DFD6361), with a spindle speed of 45000 rpm (min). -1 Under conditions of a conveying speed of 30 mm / s and a spacing of 5 mm, the aforementioned thermosetting sheets and the aforementioned bare Si wafers are cut with blades to obtain multiple thermosetting sheets with stacked bare chips. At this time, if no practical problems are found in the bare chips when peeling them from the thermosetting sheets, the peelability during cutting is evaluated as good. If even one bare chip is found to peel off to the level of practical problems (chip scattering), the peelability during cutting is evaluated as poor.

[0298] It should be noted that the aforementioned adhesive layer, dicing tape, and die bonding film are fabricated as follows.

[0299] (Creating the adhesive layer)

[0300] Synthesis of acrylic polymers

[0301] The following raw materials were added to a reaction vessel equipped with a condenser, a nitrogen inlet pipe, a thermometer, and a stirrer at a monomer concentration of approximately 55% by mass. The polymerization reaction was carried out at 60°C for 10 hours under a nitrogen atmosphere. This resulted in the synthesis of an acrylic polymer intermediate.

[0302] • 2-Ethylhexyl acrylate (2HEA): 100 parts by weight

[0303] • 2-Hydroxyethyl acrylate (HEA): 20 parts by weight

[0304] • Polymerization initiator: appropriate amount

[0305] Polymerization solvent: Toluene

[0306] An acrylic polymer was synthesized by reacting 100 parts by mass of the synthesized acrylic polymer intermediate with 1.4 parts by mass of 2-methacryloyloxyethyl isocyanate (MOI) in an air stream at 50°C for 60 hours in the presence of dibutyltin dilaurate (0.1 parts by mass).

[0307] Fabrication of adhesive layer

[0308] (1) Obtain a solution containing the following raw materials, and appropriately add toluene to the solution to prepare an adhesive solution with a viscosity of 500 mPa·s.

[0309] • Synthetic acrylic polymers: 100 parts by weight

[0310] Polyisocyanate compounds

[0311] (Manufactured by Nippon Polyurethane Co., Ltd., trade name "CORONATE L"): 1.1 parts by weight

[0312] Photopolymerization initiator

[0313] (Manufactured by Ciba Specialty Chemicals Co., Ltd., trade name "Irgacure 184"): 3 parts by weight

[0314] (2) A PET-based 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. It should be noted that an organosilicon treatment, serving as a release agent, is performed on the aforementioned one side of the release sheet (PET-based film). After coating, the film is heated at 120°C for 2 minutes to perform a drying process, thereby creating an adhesive layer with a thickness of 30 μm on the aforementioned release sheet.

[0315] (Fabrication of diced tape and diced chip bonding film)

[0316] Production of cutting strip

[0317] Using a laminator, a support substrate made of polyethylene film with a thickness of 80 μm is bonded to the exposed surface of the adhesive layer made on the release sheet at room temperature to create a cutting strip.

[0318] It should be noted that for the predetermined attachment portion of the 8-inch diameter bare Si wafer in the adhesive layer of the dicing tape, a strength of 300 mJ / cm is required. 2 Irradiate with ultraviolet light to cure the aforementioned pre-attached portion.

[0319] Fabrication of chip bonding films

[0320] A thermosetting sheet is placed on the adhesive layer of the aforementioned cutting tape after UV curing, with the side of the release liner opposite to the stacked side. The thermosetting sheet is then bonded to the aforementioned cutting tape by passing it through a laminator at a speed of 0.8 mm / min. After that, the release liner is removed, thereby producing a cutting chip bonding film with the aforementioned thermosetting sheet stacked on the aforementioned cutting tape.

[0321] The results obtained from evaluating the peelability during cutting of each thermoset sheet are shown in Table 2 below.

[0322] [Table 2]

[0323]

[0324] As shown in Table 2, the thermosetting sheets in each embodiment contain conductive particles with an average particle size D. 50 The silver particles are 0.01 μm or larger and 10 μm or smaller, with a cross-sectional roundness of 0.7 or larger, and the viscosity at 100°C is in the range of 20 kPa·s or larger and 3000 kPa·s or smaller.

[0325] Furthermore, the thermal conductivity of the cured thermosetting sheets in each embodiment is 3 W / m·K or higher, which demonstrates sufficient heat dissipation in practical applications. Moreover, the peel force relative to the silicon wafer is 1.0 N / 10 mm or higher, which is a relatively high value, and the peel performance during cutting is rated as good.

[0326] In contrast, it can be seen that in the thermosetting sheets of Comparative Examples 1 and 2, the silver particles, which contain silver particles with a cross-sectional sphericity of less than 0.7, have a viscosity of more than 3000 kPa·s at 100°C.

[0327] Furthermore, the thermal conductivity of the thermosetting sheets in Comparative Examples 1 and 2 after curing is above 3 W / m·K, which shows sufficient heat dissipation in practical applications. However, the peel force relative to the silicon wafer is less than 1.0 N / 10 mm, and the peel performance during cutting is rated as poor.

[0328] Furthermore, it is known that in the thermosetting sheet of Comparative Example 3, the silver particles included silver particles with a cross-sectional roundness of less than 0.7 and a viscosity at 100°C in the range of 20 kPa·s or more and 3000 kPa·s or less.

[0329] Furthermore, the peel strength of the thermosetting sheet in Comparative Example 3 relative to the silicon wafer was 7.63 N / 10 mm, which is a relatively high value. Although the peel strength during cutting was rated as good, the thermal conductivity was 1.5 W / m·K, which does not show sufficient heat dissipation in practical applications.

[0330] The results show that by making the thermosetting sheet contain an average particle size D 50 Using silver particles with a diameter of 0.01 μm or larger and a diameter of 10 μm or smaller, and a cross-sectional roundness of 0.7 or larger as conductive particles, and having a viscosity at 100°C in the range of 20 kPa·s or larger and 3000 kPa·s or smaller, can relatively suppress the peeling of semiconductor components during cutting and can achieve high heat dissipation after curing.

Claims

1. A thermosetting sheet comprising a thermosetting resin, a thermoplastic resin, and conductive particles. The conductive particles have an average particle size D 50 Silver particles with a diameter of 0.01 μm or larger and a diameter of 10 μm or smaller, and a cross-sectional circularity of 0.7 or larger. The conductive particles constitute 83% to 95% of the total mass of the thermosetting sheet (100% by mass). The thermosetting sheet has a viscosity of 20 kPa·s or higher and 3000 kPa·s or lower at 100°C.

2. The thermosetting sheet according to claim 1, wherein, The particle filling rate P of the conductive particles in the cured thermosetting sheet is 30% or more by volume.

3. The thermosetting sheet according to claim 1 or 2, wherein, The thermal conductivity after curing is above 3 W / m·K.

4. The thermosetting sheet according to claim 1 or 2, wherein, The peel strength relative to silicon wafers at room temperature is above 1 N / 10 mm.

5. The thermosetting sheet according to claim 1 or 2, comprising volatile components. The volatile component contains one or more hydroxyl groups and has a boiling point of 250°C or higher.

6. The thermosetting sheet according to claim 5, wherein, The volatile components are terpenoid compounds.

7. A chip bonding film, comprising: Substrate layer A cutting strip with an adhesive layer is laminated on the substrate layer. Thermosetting sheets are laminated on the adhesive layer of the cut strip. The thermosetting sheet is the thermosetting sheet according to any one of claims 1 to 6.

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