Multilayer sheet for mold bottom filling sealing, mold bottom filling sealing method, electronic component mounting substrate, and method for manufacturing electronic component mounting substrate

Abstract

The objective of this invention is to provide a multilayer sheet for sealing the bottom of a mold with good inter-electrode penetration. To solve the above-mentioned problem, a multilayer sheet for sealing the bottom of a mold is provided, characterized in that it comprises an outermost layer (A) of a resin composition having a maximum tanδ (loss tangent) value of 3 or more at a measurement temperature of 125°C and a measurement time of 0 to 100 seconds.

Description

Technical Field

[0001] This invention relates to a multilayer sheet for filling and sealing the bottom of a mold, and a method for filling and sealing the bottom of a mold. Background Technology

[0002] With the miniaturization and thinning of electronic devices, space-saving is required for integrated circuits mounted on circuit boards. Furthermore, high density is needed to achieve rapid transmission of multiple signals. Due to this high density for rapid signal transmission, the connection between semiconductor chips and other electronic components (hereinafter referred to as "electronic components") and packaging substrates has largely adopted flip-chip interconnects in recent years, which are easier to implement with multiple pins and offer higher speeds. To protect against external dust and moisture, electronic components are sealed with sealing resins or similar materials. For sealing electronic components connected using flip-chip interconnects, the conventional method is to first fill the gap between the electronic component and the packaging substrate with a fluid liquid or paste-like sealing material, and then overmold it using other liquid or paste-like sealing materials or sealing films.

[0003] The process of performing these underfilling and then overcapsulation is complicated and time-consuming. Therefore, a mold underfill encapsulation material that can perform underfilling and overcapsulation at the same time has been proposed (Patent Document 1).

[0004] Existing technical documents

[0005] Patent documents

[0006] Patent Document 1: Japanese Patent Application Publication No. 2015-71670 Summary of the Invention

[0007] The problem the invention aims to solve

[0008] However, in recent years, integrated circuits used in IoT, autonomous driving, and other applications have adopted multiple electrodes to connect to substrates and other components in order to further achieve high-density electronic components. As a result, the distance between electrodes in a chip or similar device is too narrow, and existing mold bottom filling sealant cannot fully penetrate between the electrodes.

[0009] Therefore, the objective of this invention is to provide a multilayer sheet for sealing the bottom of a mold with good inter-electrode penetration.

[0010] means for solving problems

[0011] The inventors conducted in-depth research on the above-mentioned problems and found that a multilayer sheet having an (A) layer composed of a resin composition having a specific tanδ (loss tangent) as the outermost layer can solve the above-mentioned problems, thus completing the present invention.

[0012] That is, the present invention is a multilayer sheet.

[0013] The multilayer sheet of the present invention for solving the above-mentioned problems is characterized in that it has an outermost layer consisting of a resin composition having a maximum value of tanδ (loss tangent) of 3 or more at a measurement temperature of 125°C and a measurement time of 0 to 100 seconds.

[0014] tanδ (loss tangent) represents the ratio of the elasticity to the viscosity of the resin composition. When bottom-filling electronic components such as semiconductor chips with narrow electrode spacing, low viscosity alone is insufficient for deep penetration. To further achieve deep penetration, a force, i.e., elastic force, is needed to expel the penetrated material from the rear. The multilayer sheet of the present invention, containing a (A) layer composed of a resin composition defining the maximum value of the aforementioned tanδ (loss tangent), exhibits excellent penetration when bottom-filling electronic components with even narrower electrode spacing in molds.

[0015] Furthermore, since it is sheet-like, there is no need to inject resin or liquids during the bottom filling and sealing process of the mold. Therefore, compared with the bottom filling and sealing process of transfer molding, electronic component mounting substrates with fewer voids can be obtained.

[0016] In addition, as one embodiment of the multilayer sheet of the present invention, the (A) layer is characterized in that the filler has a maximum particle size of 20 μm or less.

[0017] Based on this feature, it can achieve better penetration into electronic components with narrower distances between electrodes.

[0018] In addition, as an embodiment of the multilayer sheet of the present invention, the (A) layer is characterized in that the curing accelerator contains a median particle size (D50) (hereinafter referred to as "median particle size") of 10 μm or less when the cumulative volume of the volume particle size distribution is 50%.

[0019] Based on this feature, it can achieve better penetration into electronic components with narrower distances between electrodes.

[0020] In addition, as one embodiment of the multilayer sheet of the present invention, the thickness of layer (A) is 10 to 500 μm.

[0021] Based on this characteristic, warping of electronic components can be suppressed. Furthermore, the resin easily penetrates beneath the electronic components, exhibiting superior penetration properties.

[0022] In addition, as one embodiment of the multilayer sheet of the present invention, it is characterized by having a (B) layer composed of a resin composition satisfying the following formula (1).

[0023] In the following formula (1), “α” represents the coefficient of thermal expansion α [Ppm / K] of the thermocure after heat curing at 175℃ for 1 hour at temperatures below 80℃. “E’” represents the storage modulus E’ [GPa] of the thermocure at 25℃.

[0024] 40000≦α×E'≦250000[Pa / K](1)

[0025] Electronic components can sometimes deform due to the heat during resin curing, but multilayer sheets with a (B) layer composed of a resin composition satisfying formula (1) can follow the shape changes of the electronic components, exhibiting excellent penetration and suppressing warping.

[0026] Specifically, the coefficient of thermal expansion represents the proportion by which the length of the sheet changes as the temperature rises, and the storage modulus represents the rigidity of the sheet. For example, within the numerical range of Equation (1), a large coefficient of thermal expansion α results in a small storage modulus E', which reduces the rigidity of the sheet. Thus, the sheet can follow the shape changes of the electronic components, thereby mitigating the stress generated by the heat of the electronic components. This helps to suppress the warping of the electronic components.

[0027] In addition, as one embodiment of the multilayer sheet of the present invention, the multilayer sheet is characterized by having a (B) layer containing 70% or more of filler by mass, and the ratio of the thickness of the (B) layer to the thickness of the (A) layer (B / A) is 1.0 to 80.

[0028] Based on this feature, it is possible to achieve better sealing performance for electronic components with narrower electrode spacing, and further improve the low warpage performance of sealed electronic components.

[0029] The mold bottom filling and sealing method of the present invention for solving the above-mentioned problems is a mold bottom filling and sealing method for electronic component mounting substrate, characterized by comprising the following steps: a step of preparing a substrate, wherein an electronic component is flip-mounted, the electronic component having electrodes having an electrode height (h) of 5 to 250 μm and an electrode spacing (w) of 5 to 500 μm; a step of preparing a multilayer sheet having an (A) layer; a step of placing the multilayer sheet in contact with the electronic component and the substrate in a manner that the (A) layer is in contact with the substrate; and a step of heating and compressing the placed multilayer sheet.

[0030] It should be noted that the above-mentioned layer A is a layer composed of a resin composition in which the maximum value of tanδ (loss tangent) is 3 or more when the measurement temperature is 125°C and the measurement time is 0 to 100 seconds.

[0031] The mold bottom filling and sealing method of the present invention uses a multilayer sheet having the above-mentioned (A) layer, thus enabling more efficient penetration into the electrode space of the electronic component mounting substrate and improving the sealing method.

[0032] In addition, as an embodiment of the mold bottom filling and sealing method of the present invention, the (A) layer is characterized in that the maximum particle size of the filler is less than or equal to the height (h) of the electrode and the width (w) between the electrodes.

[0033] Based on this feature, since the maximum particle size of the filler in layer (A) is less than the height (h) of the electrode and the width (w) between the electrodes, the multilayer sheet containing layer (A) can be more efficiently penetrated into the electrode space of the electronic component mounting substrate, and the warping of the electronic component mounting substrate can be suppressed.

[0034] The electronic component mounting substrate of the present invention for solving the above-mentioned problems is characterized in that the bottom filling seal of the mold is achieved by a multilayer sheet having a (A) layer as the outermost layer.

[0035] It should be noted that the above-mentioned layer A is a layer composed of a resin composition in which the maximum value of tanδ (loss tangent) is 3 or more when the measurement temperature is 125°C and the measurement time is 0 to 100 seconds.

[0036] Based on this feature, by having a multilayer sheet having the above-mentioned (A) layer, it is possible to penetrate more efficiently into the electrode space of the electronic component mounting substrate on which electronic components are mounted, thus providing an electronic component mounting substrate with excellent heat resistance and moisture resistance.

[0037] The method for manufacturing an electronic component mounting substrate according to the present invention for solving the above-mentioned problems is characterized by comprising the following steps: a step of preparing a substrate on which electronic components are flip-chip mounted; a step of preparing a multilayer sheet having a (A) layer as the outermost layer; a step of placing the multilayer sheet in contact with the electronic components and the substrate in a manner whereby the (A) layer is in contact with the substrate; and a step of heating and compressing the placed multilayer sheet.

[0038] It should be noted that the above-mentioned layer A is a layer composed of a resin composition in which the maximum value of tanδ (loss tangent) is 3 or more when the measurement temperature is 125°C and the measurement time is 0 to 100 seconds.

[0039] Based on this feature, by using a multilayer sheet having the above-mentioned (A) layer, it is possible to penetrate more efficiently into the electrode space of the electronic component mounting substrate, and to provide a manufacturing method for an electronic component mounting substrate with excellent heat resistance and moisture resistance.

[0040] Invention Effects

[0041] According to the present invention, a multilayer sheet for filling and sealing the bottom of a mold with good penetration between electrodes can be provided. Attached Figure Description

[0042] Figure 1 This is a schematic diagram illustrating the multilayer sheet of the present invention.

[0043] Figure 2 This is a schematic diagram illustrating the mounting substrate for electronic components.

[0044] Figure 3 This is a schematic diagram illustrating the state in which the multilayer sheet of the present invention is placed on an electronic component mounting substrate.

[0045] Figure 4 This is a schematic diagram illustrating an electronic component mounting substrate for filling and sealing the bottom of a mold using the multilayer sheet of the present invention. Detailed Implementation

[0046] The preferred embodiments of the present invention will be described below. However, the present invention is not limited to the following embodiments.

[0047] [Multi-layer sheet for sealing the bottom of the mold]

[0048] The multilayer sheet for filling and sealing the bottom of the mold of the present invention is characterized in that it has an outermost layer (A) composed of a resin composition having a maximum value of tanδ (loss tangent) of 3 or more at a measurement temperature of 125°C and a measurement time of 0 to 100 seconds.

[0049] Bottom filling seal is one of the methods for sealing electronic components connected to a substrate via flip-chip bonding or similar methods. It refers to a sealing method that combines bottom filling seal, which seals the electrode portion, with overmolding seal, which seals the entire electronic component.

[0050] <(A) layer>

[0051] The multilayer sheet of the present invention comprises an outermost layer (A) of a resin composition having a maximum value of 3 or more of tanδ (loss tangent) at a measurement temperature of 125°C and a measurement time of 0 to 100 seconds.

[0052] The multilayer sheet of the present invention, which has a (A) layer as the outermost layer, composed of a resin composition having a maximum value of tanδ (loss tangent), exhibits excellent penetration when filling the bottom of a mold for electronic components with narrower inter-electrode distances.

[0053] Here, the outermost layer refers to the outermost layer of the multilayer sheet, such as the layer that is in contact with air or other atmosphere. In this case, the release film or sheet is not referred to as the outermost layer. Moreover, layer (A) of the present invention is a layer that is placed in direct contact with electronic components and substrate during the filling and sealing of the bottom of the mold.

[0054] Furthermore, since it has layer (A) as the outermost layer, it can achieve excellent sealing performance by placing it in contact with electronic components and substrates through layer (A) for sealing.

[0055] The maximum value of tanδ (loss tangent) is preferably 5 or more, more preferably 7 or more. There is no particular upper limit to the maximum value of tanδ (loss tangent), but it is preferably 60 or less, more preferably 50 or less.

[0056] The maximum tanδ value of the resin composition constituting layer (A) can be controlled by adjusting the filler content, the type of thermosetting resin, or the type of curing agent. For example, increasing the filler content will decrease the maximum value, while decreasing the filler content will increase the maximum value. Furthermore, by using a thermosetting resin such as a crystalline epoxy resin or liquid epoxy resin that becomes low-viscosity upon heating, and by using a low-viscosity curing agent such as low-molecular-weight phenol, crystalline anhydride, or liquid phenol, a maximum tanδ value of 3 or higher can be achieved.

[0057] In this invention, the maximum value of tanδ of the resin composition constituting layer (A) is the value obtained by measuring a specimen with a diameter of 25 mmΦ using a viscoelasticity measuring device (e.g., ARES-LS2 manufactured by TA Instruments) under the conditions of a measuring temperature of 125°C, a measuring time of 0 to 100 seconds, and a frequency of 1 Hz.

[0058] Furthermore, layer (A) preferably contains filler. The filler used in layer (A) is not particularly limited, and examples include fused silica, crystalline silica, alumina, talc, calcium carbonate, titanium dioxide, red lead, silicon carbide, boron nitride (BN), and glass beads. These can be used individually or in combination of two or more.

[0059] From the perspective of improving inter-electrode penetration, silica powder is preferred, and fused silica powder is more preferably used. Examples of fused silica powder include spherical fused silica powder and broken fused silica powder. From the viewpoint of flowability, spherical fused silica powder is particularly preferred, and fused silica powder with high sphericity is more preferably used.

[0060] In addition, by including fillers, warping of electronic components can be suppressed.

[0061] Furthermore, the filler described above can also be a filler whose surface has been pre-reacted with a silane coupling agent. By using a filler whose surface has been reacted with a silane coupling agent, the dispersibility in the resin composition can be improved. The amount of silane coupling agent used is preferably 0.05 to 5 parts by weight relative to 100 parts by weight of filler, more preferably 0.1 to 3 parts by weight.

[0062] In layer (A), the filler content is preferably 30% by mass or more. As a lower limit, it is more preferably 73% by mass or more, and even more preferably 76% by mass or more. As an upper limit, it is more preferably 93% by mass or less, and even more preferably 85% by mass or less. By making the filler content within the above range, the maximum value of tanδ (loss tangent) can reach 3 or more. It should be noted that when the filler content is 30% or more, the processability of the resin composition tends to improve.

[0063] The median particle size of the filler is preferably 0.1 to 30 μm. As a lower limit, it is more preferably 0.1 μm or more, and even more preferably 0.5 μm or more. As an upper limit, it is more preferably 20 μm or less, and even more preferably 10 μm or less.

[0064] Furthermore, the maximum particle size of the filler in layer (A) is, for example, smaller than the electrode height or electrode width, preferably 20 μm or less. As an upper limit, it is more preferably 15 μm or less, and even more preferably 10 μm or less.

[0065] By making the maximum particle size of the filler in layer (A) below 20 μm, the permeability between electrodes can be further improved.

[0066] It should be noted that the aforementioned median and maximum particle sizes are, for example, values ​​derived by measuring a sample arbitrarily selected from the population using a laser diffraction scattering type particle size distribution measuring device.

[0067] Furthermore, the material constituting layer (A) is not particularly limited, but is preferably a resin, and more preferably a thermosetting resin.

[0068] Examples of thermosetting resins include epoxy resins, (meth)acrylic resins, phenolic resins, melamine resins, silicone resins, urea resins, polyurethane resins, vinyl ester resins, unsaturated polyester resins, diallyl phthalate resins, and polyimide resins. These can be used individually or in combination of two or more. To control the maximum tanδ value of the resin composition constituting layer (A) to 3 or higher, epoxy resins are preferred, and epoxy resins that become low-viscosity upon heating are more preferred, such as crystalline epoxy resins like naphthalene-type epoxy resins or liquid epoxy resins like liquid bisphenol A-type epoxy resins.

[0069] Epoxy resins are not particularly limited, but can include, for example, bisphenol-type epoxy resins such as bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol AD ​​type epoxy resin, hydrogenated bisphenol A type epoxy resin, and hydrogenated bisphenol F type epoxy resin; alicyclic aliphatic epoxy resins such as biphenyl type or tetramethylbiphenyl type epoxy resin, phenol novolac type epoxy resin, naphthalene type epoxy resin, and dicyclopentadiene type epoxy resin; glycidylamine type epoxy resin, and glycidyl ethers of organic carboxylic acids, etc. These can be used alone or in combination of two or more. Epoxy resins can be prepolymers or copolymers of epoxy resins such as polyether-modified epoxy resins and organosilicon-modified epoxy resins with other polymers. Among these, bisphenol-type epoxy resins, biphenyl-type epoxy resins, dicyclopentadiene type epoxy resins, glycidylamine type epoxy resins, naphthalene type epoxy resins, and polyether-modified epoxy resins are preferred.

[0070] To adjust the viscosity of the resin composition, it may contain approximately 0.1 to 30% by mass of a monofunctional epoxy resin having one epoxy group in its molecule, relative to the total epoxy resin. Such monofunctional epoxy resins include phenyl glycidyl ether, 2-ethylhexyl glycidyl ether, ethyl diethylene glycol glycidyl ether, dicyclopentadiene glycidyl ether, and 2-hydroxyethyl glycidyl ether. These can be used alone or in combination of two or more.

[0071] The content of the thermosetting resin in layer (A) is not particularly limited, but is preferably 5 to 50% by mass.

[0072] Furthermore, the epoxy resin content in layer (A) is not particularly limited and can be 5% by mass or more and 50% by mass or less. As a lower limit, it is preferably 5% by mass or more, more preferably 10% by mass or more. As an upper limit, it is preferably 40% by mass or less, more preferably 30% by mass or less.

[0073] Furthermore, layer (A) may contain a curing agent for a thermosetting resin. The type of curing agent is not particularly limited; examples include phenolic curing agents such as solid phenol, solid phenolic varnish, or liquid phenolic varnish; dicyandiamide curing agents (such as dicyandiamide); urea curing agents; organic acid hydrazine curing agents; polyamine salt curing agents; amine adduct curing agents; acid anhydride curing agents such as solid or liquid acid anhydrides; and imidazole curing agents. To control the maximum tanδ value of layer (A) to above 3, low-viscosity curing agents such as liquid phenolic varnish or liquid acid anhydrides are preferred. These can be used alone or in combination of two or more. The type of curing agent can be appropriately selected based on the thermosetting resin.

[0074] The amount of curing agent varies depending on the type of curing agent. When using epoxy resin, it is preferable to use a curing agent in which the number of functional groups of the curing agent is 0.001 to 2 equivalents per 1 equivalent of epoxy group, and more preferably 0.005 to 1.5 equivalents.

[0075] Furthermore, layer (A) preferably contains a curing accelerator. Examples of curing accelerators include amine compounds such as imidazole compounds, phosphorus compounds, basic compounds such as organometallic compounds, and microencapsulated curing accelerators.

[0076] Examples of the aforementioned imidazole compounds include imidazole, 2-methylimidazolium, 2-ethylimidazolium, 1-isobutyl-2-methylimidazolium, 2-ethyl-4-methylimidazolium, 2-phenylimidazolium, 2-phenyl-4-methylimidazolium, 1-benzyl-2-methylimidazolium, 1-benzyl-2-phenylimidazolium, 1,2-dimethylimidazolium, 1-cyanoethyl-2-methylimidazolium, 1-cyanoethyl-2-ethyl-4-methylimidazolium, 1-cyanoethyl-2-undecylimidazolium, 1-cyanoethyl-2-phenylimidazolium and other 2-substituted imidazole compounds, 1-cyanoethyl-2-undecylimidazolium tribenzoate, 1-cyanoethyl-2-phenylimidazolium trimellitate and other trimellitates. Triazine adducts such as acid salts, 2,4-dicyano-6-[2'-methylimidazolyl-(1')]-ethyl-s-triazine, 2,4-dicyano-6-[2'-undecylimidazolyl-(1')]-ethyl-s-triazine, 2,4-dicyano-6-[2'-ethyl-4'-methylimidazolyl-(1')]-ethyl-s-triazine, 2,4-dicyano-6-[2'-methylimidazolyl-(1')]-ethyl-s-triazine isocyanuric acid adducts, 2-phenylimidazolyl isocyanuric acid adducts, 2-methylimidazolyl isocyanuric acid adducts, 2-phenyl-4,5-dihydroxymethylimidazolium and 2-phenyl-4-methyl-5-dihydroxymethylimidazolium, etc.

[0077] Examples of the aforementioned phosphorus compounds include trialkylphosphine compounds such as tributylphosphine and triarylphosphine compounds such as triphenylphosphine.

[0078] Examples of the aforementioned amine compounds include 2,4,6-tris(dimethylaminomethyl)phenol, diethylamine, triethylamine, diethylenetetramine, triethylenetetramine, and 4,4-dimethylaminopyridine. Amine compounds can be amine adducts.

[0079] Examples of such organometallic compounds include zinc naphthenate, cobalt naphthenate, tin octoate, cobalt octoate, cobalt diacetylacetonate (II), and cobalt triacetylacetonate (III).

[0080] As the aforementioned microencapsulated curing accelerator, a particulate composition in which an amine compound powder is dispersed in an epoxy resin can be used, for example. The amine compound can be selected from the following examples based on the desired thickening ratio. Examples of the amine compounds include aliphatic primary amines, alicyclic primary amines, aromatic primary amines, aliphatic secondary amines, alicyclic secondary amines, aromatic secondary amines, imidazole compounds, imidazoleline compounds, or reaction products of these compounds with carboxylic acids, sulfonic acids, isocyanates, epoxy resins, etc. One or more of these can be used in combination. For example, aliphatic primary amines, alicyclic primary amines, aromatic primary amines, aliphatic secondary amines, alicyclic secondary amines, aromatic secondary amines, imidazole compounds are preferred, or imidazoleline compounds and reaction products of these compounds with the aforementioned carboxylic acids, sulfonic acids, isocyanates, epoxy resins, etc., can be used in combination. Furthermore, from the viewpoint of suppressing thickening at 25°C, the aforementioned amine compound powder preferably has a melting point or softening point of 60°C or higher.

[0081] Furthermore, the curing accelerator contained in layer (A) preferably has a median particle size of 10 μm or less. By containing a curing accelerator with a median particle size of 10 μm or less, superior penetration into electronic components with narrower inter-electrode distances can be achieved. That is, since it does not contain large particles, poor penetration into narrow inter-electrode distances can be suppressed. In addition, because the median particle size is small, there is no distinction between large and small particles in the system, which can suppress localized poor curing after penetration.

[0082] The upper limit of the median particle size of the above-mentioned curing accelerator is more preferably 5 μm or less, and even more preferably 3 μm or less. The lower limit is preferably 0.1 μm or more.

[0083] In layer (A), the content of the curing accelerator is, for example, 0.1 parts by mass or more and 40 parts by mass or less relative to 100 parts by mass of the thermosetting resin. As a lower limit, it is preferably 1 part by mass or more, more preferably 5 parts by mass or more. As an upper limit, it is preferably 30 parts by mass or less, more preferably 20 parts by mass or less. By setting the curing accelerator to the above content, the occurrence of poor curing can be suppressed, and warping can be suppressed.

[0084] Furthermore, when epoxy resin is used in layer (A), the content of the curing accelerator is, for example, 0.1 parts by mass or more and 40 parts by mass or less relative to 100 parts by mass of epoxy resin. As a lower limit, it is preferably 1 part by mass or more, more preferably 5 parts by mass or more. As an upper limit, it is preferably 30 parts by mass or less, more preferably 20 parts by mass or less. By setting the curing accelerator to the above-mentioned content, the occurrence of poor curing and warping can be suppressed.

[0085] Other additives may be used in layer (A) of the present invention, provided that they do not impede the purpose of the present invention. Examples of such additives include thermoplastic resins, silane coupling agents, carbon black, and ion scavengers.

[0086] Examples of thermoplastic resins include non-reactive silicone oils or reactive silicone oils, acrylic resins, phenoxy resins, polyolefins, polyurethanes, end-capped isocyanates, polyethers, polyesters, polyimides, polyvinyl alcohol, butyraldehyde resins, polyamides, vinyl chloride, cellulose, thermoplastic epoxy resins, and thermoplastic phenolic resins.

[0087] Examples of non-reactive silicone oils include polysiloxane, polyether-modified silicone oils, and alkyl-modified silicone oils. Examples of reactive silicone oils include epoxy-modified silicone oils, carboxyl-modified silicone oils, and amino-modified silicone oils.

[0088] Examples of silane coupling agents include 3-epoxypropoxypropyltrimethoxysilane, 3-epoxypropoxypropyltriethoxysilane, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, 2-(3,4-epoxycyclohexyl)ethyltriethoxysilane, vinyltrimethoxysilane, and vinyltriethoxysilane. When using silica whose surface has been pre-reacted with a silane coupling agent, the above-mentioned silane coupling agents may also be appropriately incorporated.

[0089] The content of the silane coupling agent in layer (A) is preferably 0.1 to 10% by mass, more preferably 2 to 6% by mass.

[0090] The content of the aforementioned carbon black in layer (A) is preferably 0.1 to 5% by mass, more preferably 0.5 to 3% by mass.

[0091] The aforementioned ion-scavenging agent is an additive capable of capturing impurity ions in the sealing composition, as long as it can improve the reliability of the sealed electronic components. Examples of ion-scavenging agents include inorganic ion exchangers.

[0092] There is no particular limitation on the content of the ion scavenger, but it is preferably 0.05% by mass or more in layer (A), and more preferably 3% by mass or less.

[0093] Furthermore, in the multilayer sheet of the present invention, the thickness of layer (A) is preferably 10 to 500 μm. As a lower limit, it is more preferably 20 μm or more, and even more preferably 40 μm or more. As an upper limit, it is more preferably 400 μm or less, and even more preferably 300 μm or less.

[0094] By making the thickness of layer (A) within the aforementioned range, warping of electronic components can be suppressed. Furthermore, the resin can easily penetrate beneath the electronic components, exhibiting superior penetration properties.

[0095] <(B) layer>

[0096] In addition to layer (A), the multilayer sheet of the present invention preferably includes layer (B). By including layer (B), the multilayer sheet of the present invention can suppress warping in the multilayer sheet. In the multilayer sheet of the present invention, layer (B) is preferably the outermost layer or an intermediate layer on the side opposite to layer (A). In addition, the release film or sheet is not referred to as the outermost layer in this case.

[0097] Furthermore, even if layer (B) is the outermost layer, the multilayer sheet of the present invention will not be placed in direct contact with electronic components and substrates during the filling and sealing of the bottom of the mold.

[0098] Layer (B) is preferably a layer containing filler. There is no particular limitation on the type of filler, and the same filler as described in the description of layer (A) above can be used.

[0099] In layer (B), the filler content is preferably 70% by mass or more. As a lower limit, it is more preferably 75% by mass or more, and even more preferably 80% by mass or more. As an upper limit, it is preferably 93% by mass or less, and more preferably 90% by mass or less. By ensuring the filler content is within the above range, warping of the sealed electronic components can be suppressed.

[0100] The median particle size of the filler is preferably 0.1 to 30 μm. As a lower limit, it is more preferably 1 μm or more, and even more preferably 3 μm or more. As an upper limit, it is more preferably 20 μm or less, and even more preferably 15 μm or less.

[0101] The coefficient of thermal expansion of the filler is not particularly limited, but is preferably 1 ppm / K or higher, more preferably 2 ppm / K or higher. As an upper limit, it is preferably 15 ppm / K or lower, more preferably 10 ppm / K or lower.

[0102] By using fillers with a thermal expansion coefficient within the above range, it is possible to suppress the thermal expansion coefficient of layer (B) below 80°C.

[0103] Furthermore, the material constituting layer (B) is not particularly limited, but is preferably a resin, and more preferably a thermosetting resin. As the thermosetting resin, the same resin as described for layer (A) above can be used, and epoxy resin is preferred.

[0104] Epoxy resins are not particularly limited, and examples include bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol AD ​​type epoxy resin, hydrogenated bisphenol A type epoxy resin, hydrogenated bisphenol F type epoxy resin, bisphenol modified epoxy resin, biphenyl type or tetramethylbiphenyl type epoxy resin, phenolic varnish type epoxy resin, naphthalene type epoxy resin, alicyclic aliphatic epoxy resin, phenolphthalein type epoxy resin, and organic carboxylic acid glycidyl ether, etc. These can be used alone or in combination of two or more. Epoxy resins can be prepolymers or copolymers of epoxy resins such as polyether modified epoxy resin, organosilicon modified epoxy resin, and other polymers. By using biphenyl type epoxy resin, phenolic varnish type epoxy resin, phenolphthalein type epoxy resin, and bisphenol modified epoxy resin as epoxy resins with a rigid skeleton, the coefficient of thermal expansion of the (B) layer below 80°C can be reduced. Furthermore, by using polyether-modified epoxy resins with a soft backbone, the energy storage modulus E' of layer (B) at 25°C can be reduced.

[0105] To adjust the viscosity of the resin composition, the epoxy resin may contain approximately 0.1 to 30% by mass of a monofunctional epoxy resin having one epoxy group in its molecule, relative to the total epoxy resin. Such monofunctional epoxy resins may include phenyl glycidyl ether, 2-ethylhexyl glycidyl ether, ethyl diethylene glycol glycidyl ether, dicyclopentadiene glycidyl ether, 2-hydroxyethyl glycidyl ether, etc. These can be used alone or in combination of two or more.

[0106] In layer (B), the content of the above-mentioned thermosetting resin is not particularly limited, but is preferably 2 to 30% by mass.

[0107] Furthermore, the content of epoxy resin in layer (B) is not particularly limited, but is 2% by mass or more and 30% by mass or less. As a lower limit, it is preferably 3% by mass or more, more preferably 5% by mass or more. As an upper limit, it is preferably 25% by mass or less, more preferably 20% by mass or less.

[0108] In addition, layer (B) may contain a curing agent and a curing accelerator of a thermosetting resin, and the types of curing agent and curing accelerator may be the same as those described in the description of layer (A).

[0109] The amount of curing agent varies depending on the type of curing agent. When using epoxy resin, for example, per 1 epoxy group equivalent, it is preferable to use a curing agent with an equivalent number of functional groups of 0.001 to 2 equivalents, more preferably 0.005 to 1.5 equivalents. In particular, by using a phenolic curing agent such as a solid phenolic varnish resin, preferably a biphenyl-type phenolic varnish resin, the storage modulus of the (B) layer can be reduced.

[0110] In layer (B), the content of the curing accelerator is preferably 0.1 parts by mass or more and 40 parts by mass or less relative to 100 parts by mass of the thermosetting resin. As a lower limit, it is more preferably 1 part by mass or more, and even more preferably 5 parts by mass or more. As an upper limit, it is more preferably 30 parts by mass or less, and even more preferably 20 parts by mass or less. By using the above-mentioned content of the curing accelerator, the occurrence of poor curing can be suppressed, and warping can also be suppressed.

[0111] Furthermore, when epoxy resin is used in layer (B), the content of the curing accelerator is preferably 0.1 parts by weight or more and 40 parts by weight or less relative to 100 parts by weight of epoxy resin. As a lower limit, it is more preferably 1 part by weight or more, and even more preferably 5 parts by weight or more. As an upper limit, it is more preferably 30 parts by weight or less, and even more preferably 20 parts by weight or less. By using the above-mentioned content of curing accelerator, the occurrence of poor curing can be suppressed, and warping can also be suppressed.

[0112] Other additives may be used in layer (B) as long as they do not impede the purpose of this invention. Examples of such additives include thermoplastic resins, silane coupling agents, carbon black, and ion scavengers, which are the same additives described in layer (B) above.

[0113] Examples of thermoplastic resins include non-reactive or reactive silicone oils, acrylic resins, phenoxy resins, polyolefins, polyurethanes, end-capped isocyanates, polyethers, polyesters, polyimides, polyvinyl alcohol, butyraldehyde resins, polyamides, vinyl chloride, cellulose, thermoplastic epoxy resins, and thermoplastic phenolic resins. Among these, the storage modulus of layer (B) can be reduced by using resins such as polyesters, acrylic resins, silicone oils, polyethers, polyvinyl alcohol, and polyamides.

[0114] Examples of silane coupling agents include 3-epoxypropoxypropyltrimethoxysilane, 3-epoxypropoxypropyltriethoxysilane, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, 2-(3,4-epoxycyclohexyl)ethyltriethoxysilane, vinyltrimethoxysilane, and vinyltriethoxysilane. When using silica whose surface has been pre-reacted with a silane coupling agent, the above-mentioned silane coupling agents may also be appropriately incorporated.

[0115] The content of the silane coupling agent in layer (B) is preferably 0.1 to 10% by mass, more preferably 2 to 6% by mass.

[0116] The content of the aforementioned carbon black in layer (B) is preferably 0.1 to 5% by mass, more preferably 0.5 to 3% by mass.

[0117] The aforementioned ion-scavenging agent is an additive capable of capturing impurity ions in the sealing composition, as long as it can improve the reliability of the sealed electronic components. Examples of ion-scavenging agents include inorganic ion exchangers.

[0118] There is no particular limit to the content of the ion scavenger, but it is preferably 0.05% by mass or more in layer (B), and more preferably 3% by mass or less.

[0119] Furthermore, the thickness of layer (B) in the multilayer sheet of the present invention is preferably 50 to 800 μm. As a lower limit, it is more preferably 100 μm or more, and even more preferably 200 μm or more. As an upper limit, it is more preferably 700 μm or less, and even more preferably 600 μm or less.

[0120] By making the thickness of layer (B) within the above range, warping of electronic components can be suppressed.

[0121] Furthermore, the (B) layer of the multilayer sheet of the present invention preferably comprises a (B) layer composed of a resin composition having a coefficient of thermal expansion α [Ppm / K] of less than 80°C and a storage modulus E' [GPa] of the thermosetting material at 25°C that satisfies the following formula (1).

[0122] 40000≦α×E'≦250000[Pa / K](1)

[0123] The lower limit of α×E' for layer (B) is more preferably 40,000 or more, and even more preferably 50,000 or more. The upper limit is more preferably 220,000 or less, and even more preferably 180,000 or less.

[0124] The multilayer sheet of the present invention, by having a (B) layer composed of a resin composition satisfying the above formula (1), can mitigate the stress caused by heat during curing, and thus can suppress the warping of electronic components.

[0125] The lower limit of the coefficient of thermal expansion α of the resin composition constituting layer (B) at 80°C is preferably 3 ppm / K or more, more preferably 5 ppm / K or more. The upper limit is preferably 15 ppm / K or less, more preferably 10 ppm / K or less.

[0126] By making the coefficient of thermal expansion α within the above range, the sheet material can follow the shape changes of electronic components.

[0127] The coefficient of thermal expansion of the resin composition constituting layer (B) can be controlled by adjusting the coefficient of thermal expansion of the added filler, the amount of filler added, the chemical structure of the thermosetting resin, and the glass transition temperature. For example, the coefficient of thermal expansion can be reduced by adding a large amount of filler with a low coefficient of thermal expansion or by using an epoxy resin with a rigid skeleton. Furthermore, by increasing the glass transition temperature of layer (B), the coefficient of thermal expansion below the glass transition temperature can be reduced.

[0128] The method for determining the coefficient of thermal expansion α is as follows: After heat curing a resin sheet consisting only of layer (B) at 150°C for 1 hour, a test sample with a length of 20 mm × width of 5 mm × thickness of 5 μm is prepared from the heat-cured material. The test sample is fixed in the compression measurement fixture of a thermomechanical analyzer (TMA7100), and subjected to a load of 5 g and a heating rate of 2.5°C / min within a temperature range of -50 to 300°C. The coefficient of thermal expansion α is calculated based on the expansion rate at 50°C to 70°C.

[0129] The lower limit of the storage modulus E' of the resin composition constituting layer (B) at 25°C is preferably 3 GPa or more, more preferably 10 GPa or more. The upper limit is preferably 50 GPa or less, more preferably 30 GPa or less.

[0130] By making the energy storage modulus E' within the above range, the shape change of the electronic components can be suppressed by the rigidity of the sheet, thereby suppressing the warping of the electronic components.

[0131] The storage modulus of the resin composition constituting layer (B) can be controlled by adjusting the amount of filler added, the skeleton of the thermosetting resin or curing agent, and the type of thermoplastic resin. For example, the storage modulus can be reduced by increasing the amount of filler added, using epoxy resin with a flexible skeleton such as a polyether structure, or mixing thermoplastic resins such as biphenyl-type phenolic varnish resin or acrylic resin.

[0132] The method for determining the energy storage modulus E' is as follows:

[0133] (1) After heat curing the resin sheet consisting only of layer (B) at 150°C for 1 hour, a test sample with a length of 50 mm × width of 10 mm × thickness of 2 mm is prepared from the heat-cured material.

[0134] (2) Fix the test sample to the bending test fixture and use a viscoelasticity test device (DMA6100, manufactured by Hitachi High Technology Co., Ltd.) to measure the bending storage modulus in the temperature range of -50 to 300°C at a frequency of 1 Hz and a heating rate of 2.5°C / min.

[0135] (3) Read the energy storage modulus (E') at 25℃ from the above measurement results.

[0136] Furthermore, the resin composition constituting layer (B) of the multilayer sheet of the present invention preferably has a glass transition temperature of 80°C or higher after heat curing treatment at 175°C for 1 hour. Since the glass transition temperature of the heat-cured product after heat curing treatment at 175°C for 1 hour is 80°C or higher, the sealant sealed by the multilayer sheet can have excellent thermal stability.

[0137] In order to make the glass transition temperature of the thermosetting material of layer (B) above 80°C, the rigidity of the thermosetting material can be increased, for example, by increasing the content of epoxy groups in the epoxy resin or increasing the number of reactive groups in the curing agent.

[0138] Furthermore, the overall thickness of the multilayer sheet of the present invention is not particularly limited, but is preferably 100 μm or more. As a lower limit, it is more preferably 150 μm or more, and even more preferably 200 μm or more. As an upper limit, it is more preferably 1000 μm or less, and even more preferably 800 μm or less.

[0139] By making the thickness of layer (B) within the above range, warping of electronic components can be suppressed.

[0140] Furthermore, in the multilayer sheet of the present invention, the ratio of the thickness of layer (B) to the thickness of layer (A) (B / A) is preferably 1.0 to 80, more preferably 2.0 to 10.

[0141] By setting the ratio of the thickness of layer (B) to the thickness of layer (A) within the aforementioned range, it is possible to achieve superior sealing performance for electronic components with narrower electrode spacing, and further enhance the low warpage performance of the sealed electronic components.

[0142] In addition to layers (A) and (B) described above, the multilayer sheet of the present invention may also include other layers. Preferably, these other layers contain the thermosetting resin described in layers (A) and (B) above, but may also contain fillers, etc.

[0143] In addition, other layers can be one layer or two or more layers.

[0144] When the multilayer sheet of the present invention contains other layers, for example, if the other layer is layer (C), it can be configured as layer (A) / layer (C) / layer (B) or layer (A) / layer (B) / layer (C).

[0145] Furthermore, in the multilayer sheet of the present invention, the maximum value of the tanδ (loss tangent) of the resin composition constituting layer (A) at a measurement temperature of 125°C and a measurement time of 0 to 100 seconds is preferably below the maximum value of the tanδ (loss tangent) of the resin composition constituting layers other than layer (A) at a measurement temperature of 125°C and a measurement time of 0 to 100 seconds.

[0146] For example, when the sheet is a double-layer sheet consisting of layer (A) and layer (B) or a triple-layer sheet consisting of layer (A) / layer (C) / layer (B), by making the maximum value of the tanδ of the resin composition constituting layer (A) below the maximum value of the tanδ of the resin composition constituting layer (B), it is possible to prevent the (A) layer and layer (B) from melting and mixing, and to efficiently perform bottom filling and overmolding sealing.

[0147] Furthermore, when the structure is, for example, layer (A) / layer (B) / layer (C), the maximum value of tanδ (loss tangent) of the resin composition constituting layer (A) at a measurement temperature of 125°C and a measurement time of 0 to 100 seconds is preferably below the maximum value of tanδ (loss tangent) of layer (C) at a measurement temperature of 125°C and a measurement time of 0 to 100 seconds.

[0148] By ensuring that the maximum value of the tanδ (loss tangent) of the resin composition constituting layer (A) at a measurement temperature of 125°C and a measurement time of 0–100 seconds is lower than the maximum value of the tanδ (loss tangent) of the layers other than layer (A) at a measurement temperature of 125°C and a measurement time of 0–100 seconds, it is possible to prevent layer (A) from melting and mixing with the layers other than layer (A), thereby enabling efficient bottom filling and overmolding sealing.

[0149] Figure 1 A schematic diagram illustrating the multilayer sheet of the present invention. Figure 1 The multilayer sheet shown is a double-layer multilayer sheet composed of (A) layer 11 and (B) layer 12.

[0150] Figure 1 The multilayer sheet shown is a sheet with (A) layer 11 and (B) layer 12 as the outermost layers, but as mentioned above, it can also be made into a multilayer sheet with other layers besides (A) layer and (B) layer.

[0151] [Manufacturing methods for multilayer wafers]

[0152] The manufacturing method of the multilayer sheet of the present invention can be, for example, by calendering film formation, casting film formation, expansion extrusion, T-die extrusion, dry lamination, etc., to form each layer into a film and then laminate them together, or by using co-extrusion, etc. to manufacture the multilayer sheet.

[0153] Alternatively, multiple layers can be formed on the substrate, and the substrate can be peeled off for use.

[0154] There are no particular limitations on the substrate; examples include plastic film, paper, non-woven fabric, and metal. Examples of plastic films include polyolefin films, ethylene halide polymer films, acrylic resin films, rubber films, cellulose films, polyester films, polycarbonate films, polystyrene films, polyphenylene sulfide films, and cycloolefin polymer films. Additionally, substrates treated with silicone or similar materials for mold release can also be used.

[0155] The thickness of the substrate is not particularly limited, but is preferably less than 500 μm.

[0156] [Sealing method for the bottom of the mold for mounting substrates of electronic components]

[0157] Next, the method for filling and sealing the bottom of the mold for mounting electronic components will be explained.

[0158] The mold bottom filling and sealing method for the electronic component mounting substrate of the present invention is characterized by comprising the following steps: a step of preparing a substrate on which an electronic component is flip-chip mounted, the electronic component having electrodes with an electrode height (h) of 5 to 250 μm and an electrode spacing (w) of 5 to 500 μm; a step of preparing a multilayer sheet having an (A) layer as the outermost layer with a maximum value of 3 or more of tanδ (loss tangent) at a measurement temperature of 125°C and a measurement time of 0 to 100 seconds; a step of placing the multilayer sheet in contact with the electronic component and the substrate by the (A) layer; and a step of heating and compressing the placed multilayer sheet.

[0159] As electronic components, integrated circuits (ICs) are formed by integrating transistors, capacitors, resistors, etc. on a single chip; large-scale integrated circuits (LSIs) are semiconductor chips that contain more than 1,000 components on a single chip in order to further improve the integration of ICs.

[0160] Furthermore, the shape of the electrode is not particularly limited, and examples include spherical, cylindrical, tubular, and other shapes. The material of the electrode is also not particularly limited; examples include solders such as Sn-Pb, Pb-Sn-Sb, Sn-Sb, Sn-Pb-Bi, lead-free Sn-Ag, Sn-Ag-Cu, Bi-Sn, Sn-Cu, Sn-Ag-Bi-In, and Sn-Zn-Bi; gold-based metals; copper-based metals; and copper alloys. Additionally, the electrode height (h) is 5–250 μm, and the electrode spacing (w) is 5–500 μm.

[0161] Examples of substrates include printed circuit boards with printed circuits.

[0162] Next use Figures 2-4 The method for filling and sealing the bottom of the mold is explained.

[0163] Figure 2 This is a schematic diagram illustrating an electronic component mounting substrate (mounting substrate) 20 formed by connecting electronic component 21 and substrate 22 via electrodes 23. Electronic component 21 and substrate 22 are electrically connected via electrodes 23. In this case, the height (h) between the electrodes is 5–250 μm, and the width (w) is 5–500 μm. Furthermore, the diameter of the electrodes is preferably 10 μm–1000 μm.

[0164] Figure 3 This is a schematic diagram illustrating the state in which the multilayer sheet 10 is placed on the electronic component mounting substrate (mounting substrate) 20 in such a way that layer (A) is in contact with the electronic component 21 and the substrate 22.

[0165] At this point, the maximum particle size of the filler contained in the multilayer sheet is preferably less than or equal to the height (h) and width (w) between the electrodes.

[0166] Next, the bottom of the electronic component mounting substrate can be filled and sealed by heating and compressing the multilayer sheet 10.

[0167] The heating temperature is not particularly limited at this point, but is preferably 70 to 150°C. As a lower limit, it is more preferably 80°C or higher, and even more preferably 90°C or higher. As an upper limit, it is more preferably 140°C or lower, and even more preferably 130°C or lower.

[0168] The compression pressure is not particularly limited, but is preferably 0.5 to 10 MPa. As a lower limit, it is more preferably 1 MPa or more, and even more preferably 1.5 MPa or more. As an upper limit, it is more preferably 8 MPa or less, and even more preferably 6 MPa or less.

[0169] Furthermore, there are no particular limitations on the method of heat compression; for example, a method can be used to heat and press the edges of multilayer sheets simultaneously using a pressure plate. Additionally, heat compression can also be performed under reduced pressure conditions.

[0170] Furthermore, when the material used for multilayer sheets contains a thermosetting resin, a post-curing process is preferably included. This post-curing process is a heat-curing process.

[0171] The heating temperature is preferably 90 to 200°C. As a lower limit, it is more preferably 120°C or higher, and even more preferably 140°C or higher. Furthermore, the heating time is preferably 30 to 240 minutes, and more preferably 60 to 180 minutes.

[0172] Figure 4This is a schematic diagram illustrating an electronic component mounting substrate for which the bottom of the mold is filled and sealed using a multilayer sheet 10. The multilayer sheet 10 contains an (A) layer with a maximum tanδ (loss tangent) value of 3 or more at a measurement temperature of 125°C and a measurement time of 0 to 100 seconds. Therefore, it can penetrate more efficiently into the electrode spaces of the electronic component mounting substrate, resulting in an electronic component mounting substrate with excellent heat resistance and moisture resistance.

[0173] Example

[0174] The following examples illustrate the invention in further detail, but the invention is not limited thereto.

[0175] <Multi-layer film production>

[0176] (1) Creation of Layer A

[0177] According to the proportions shown in Tables 1-1 to 1-4, epoxy resin, curing agent, filler (fused silica FB510MDX1: manufactured by DENKA Corporation), carbon black (particle size 24 nm), silane coupling agent (KBM503: manufactured by Shin-EtsuSilicone), ion trap (inorganic ion exchanger), and curing accelerator were mixed and heated at 120°C for 30 minutes using a roller mixer, followed by melt mixing to prepare a compound. All values ​​in the tables are parts by weight. The obtained compound was then coated onto a release film using a T-die extrusion method at 100°C to form a sheet, creating layer (A) with a thickness of 20–300 μm, a longitudinal dimension of 500 mm, and a transverse dimension of 500 mm. A 50 μm thick polyethylene terephthalate film treated with silicone release agent was used as the release film.

[0178] (2)(B) Layer Creation

[0179] 100 parts by weight of biphenyl-type epoxy resin, 50 parts by weight of solid phenolic varnish resin, 1360 parts by weight of filler (fused silica FB510MDX1: manufactured by DENKA Corporation), 2 parts by weight of carbon black (particle size 24 nm), 2 parts by weight of silane coupling agent (KBM503: manufactured by Shin-Etsu Silicone), 5 parts by weight of ion scavenger (inorganic ion exchanger), and 10 parts by weight of curing accelerator (triarylphosphine compound) were mixed and heated at 120°C for 30 minutes using a roller mixer, followed by melt mixing to prepare a compound. The resulting compound was then coated onto a release film using a T-die extrusion method at 100°C to form a sheet, creating a (B) layer with a thickness of 50–800 μm, a longitudinal dimension of 500 mm, and a transverse dimension of 500 mm. As the above-mentioned release film, a polyethylene terephthalate film with a thickness of 50 μm that has undergone silicone release treatment is used.

[0180] (3) Fabrication of the multi-layer sheet for die bottom filling and sealing

[0181] Stack the above-prepared (A) layer and (B) layer in contact with each other, and use a laminator to bond them at a temperature of 60 °C to fabricate the die bottom filling and sealing sheet.

[0182] <Measurement of the maximum value of tanδ (loss tangent)>

[0183] Measure tanδ of the resin composition constituting the above-obtained (A) layer. The measurement uses a specimen with a diameter of 25 mmΦ, and a viscoelasticity measuring device (manufactured by TA Instruments, ARES-LS2) is used for measurement under the conditions of a measurement temperature of 125 °C, a measurement time of 0 to 100 seconds, and a frequency of 1 Hz. The measurement results are shown in Tables 1-1 to Tables 1-4.

[0184] <Die bottom filling test 1>

[0185] (Interpenetration test between electrodes)

[0186] Place the above-prepared die bottom filling and sealing sheet on a test chip with a bump height of 30 μm mounted on glass and a size of 25 mm in length and 25 mm in width in such a way that the (A) layer of the sheet is in contact. After pre-curing under the conditions of a molding pressure of 3 MPa, 125 °C, and 10 minutes, post-cure is carried out under the conditions of 150 °C and 60 minutes. The evaluation of the interpenetration is carried out by directly observing from the peeled back and according to the following criteria.

[0187] 【Interpenetration evaluation criteria】

[0188] ◎: The size of the non-interpenetrated part is 500 μm or less.

[0189] 〇: The size of the non-interpenetrated part is greater than 500 μm and 1000 μm or less.

[0190] ×: The size of the non-interpenetrated part is greater than 1000 μm.

[0191] 【Table 1-1】

[0192]

[0193] 【Table 1-2】

[0194]

[0195] 【Table 1-3】

[0196]

[0197] 【Table 1-4】

[0198]

[0199] Based on the results in Tables 1-1 to 1-4, it can be seen from the comparison between the examples and the comparative examples that if the maximum value of tanδ of the resin composition constituting layer (A) is 3 or more at a measurement temperature of 125°C and a measurement time of 0 to 100 seconds, a sealing sheet with excellent inter-electrode penetration can be obtained.

[0200] Furthermore, a comparison of Example 1 and Example 9 shows that the sheet using a curing accelerator with a median particle size of less than 10 μm exhibits superior interelectrode penetration.

[0201] <Mold Bottom Filling Test 2>

[0202] The components were mixed according to the proportions shown in Table 2, heated at 120°C for 30 minutes using a roller mixer, and then melt-mixed to prepare a compound. The resulting compound was then coated onto a release film using a T-die extrusion method at 100°C to form a sheet, creating a (B) layer with a thickness of 200–800 μm, a longitudinal dimension of 500 mm, and a transverse dimension of 500 mm. A 50 μm thick polyethylene terephthalate film treated with silicone release agent was used as the release film.

[0203] Layers (A) and (B) used in Example 1 of Table 1-1 are laminated in a contact manner and bonded using a laminator at a temperature of 60°C to create a bottom filling sealing sheet for the mold.

[0204] Next, the obtained mold bottom filling sealing sheet was used to conduct the same inter-electrode penetration test as described above. The evaluation criteria were the same as described above.

[0205] The warpage was then evaluated using the following method.

[0206] (Warpage Assessment)

[0207] The mold bottom filling sealing sheet was placed on a silicon wafer with a diameter of 12 inches and a thickness of 775 μm. After pre-curing at a molding pressure of 3 MPa, 125°C and 10 minutes, it was post-cured at 150°C and 60 minutes.

[0208] [Warpage Assessment Criteria]

[0209] After post-curing and cooling to room temperature, the warpage is evaluated according to the following criteria. The measurement method is as follows: The average height difference between two points, the center of the substrate side and the edge of the wafer, is measured using a laser displacement meter. This value is taken as the warpage and evaluated according to the following criteria.

[0210] 〇: Warpage is less than 12mm.

[0211] ×: Warping greater than 12mm.

[0212] Table 2

[0213]

[0214] According to the results in Table 2, the sheet composed of layer (B) of the resin composition having a coefficient of thermal expansion α [Ppm / K] below 80°C and a storage modulus E' [GPa] of the thermosetting material at 25°C that satisfies formula (1) can exhibit excellent low warpage effect.

[0215] Furthermore, by comparing Examples 29 and Examples 31-33, it can be seen that if the thickness ratio (B / A) is 1.0 or higher, an excellent low warpage effect can be achieved. On the other hand, if the thickness ratio (B / A) is less than 1.0, a low warpage effect cannot be achieved.

[0216] Industrial availability

[0217] The multilayer sheet for bottom filling and sealing of the mold of the present invention can simultaneously fill the narrow gap under the flip chip and seal the entire structure. Therefore, it is applicable to the sealing of integrated circuits and large-scale integrated circuits used in IoT, autonomous driving, and other applications.

[0218] Explanation of icon numbers

[0219] 10… multilayer wafer, 11… (A) layer, 12… (B) layer, 20… mounting substrate, 21… electronic component, 22… substrate, 23… electrode, 100… electronic component mounting substrate sealed by multilayer wafer.

Claims

1. A multi-layer sheet for sealing the bottom of a mold, characterized in that, Having layer (A) as the outermost layer, The (A) layer is a resin composition having a maximum value of 3 or more of tanδ (loss tangent) at a measurement temperature of 125°C and a measurement time of 0 to 100 seconds.

2. The multilayer sheet according to claim 1, characterized in that, The (A) layer contains filler, the maximum particle size of which is less than 20 μm.

3. The multilayer sheet according to claim 1 or 2, characterized in that, The (A) layer contains a curing accelerator with a median particle size (D50) of less than 10 μm when the cumulative volume of the volumetric particle size distribution is 50%.

4. The multilayer sheet according to claim 1 or 2, characterized in that, The thickness of layer (A) is 10–500 μm.

5. The multilayer sheet according to claim 1 or 2, characterized in that, It also has a (B) layer. Layer (B) is a layer composed of a resin composition satisfying the following formula (1). In the following formula (1), "α" represents the coefficient of thermal expansion α [ppm / K] of the thermocure after heat curing at 175°C for 1 hour at temperatures below 80°C, and "E'" represents the storage modulus E' [GPa] of the thermocure at 25°C. 40000≦α×E'≦250000[Pa / K](1).

6. The multilayer sheet according to claim 5, characterized in that, The ratio of the thickness of layer (B) to the thickness of layer (A) (B / A) is 0.1 to 80.

7. A method for filling and sealing the bottom of a mold for mounting an electronic component substrate, characterized in that, It has the following processes: The process of preparing a substrate, wherein electronic components are flip-chip mounted on the substrate, and the electronic components have electrodes with an electrode height (h) of 5 to 250 μm and an electrode spacing (w) of 5 to 500 μm; The process of preparing a multilayer wafer, wherein the multilayer wafer has layer (A) as the outermost layer; The process of mounting the multilayer wafer in such a way that layer (A) contacts the electronic components and the substrate; and The process of heating and compressing the loaded multilayer sheet. The (A) layer is a resin composition having a maximum value of 3 or more for tanδ (loss tangent) at a measurement temperature of 125°C and a measurement time of 0 to 100 seconds.

8. The mold bottom filling and sealing method according to claim 7, characterized in that, The (A) layer contains filler, the maximum particle size of which is smaller than the height (h) of the electrode and the width between the electrodes (w).

9. An electronic component mounting substrate that is filled and sealed at the bottom of a mold, characterized in that, The bottom of the mold is sealed using a multi-layer sheet with layer (A) as the outermost layer. The (A) layer is a resin composition having a maximum value of 3 or more for tanδ (loss tangent) at a measurement temperature of 125°C and a measurement time of 0 to 100 seconds.

10. A method for manufacturing an electronic component mounting substrate that is filled and sealed at the bottom of a mold, characterized in that, It has the following processes: The process of preparing a substrate, wherein electronic components are flip-chip mounted on the substrate; The process of preparing a multilayer wafer, wherein the multilayer wafer has layer (A) as the outermost layer; The process of mounting the multilayer wafer in such a way that layer (A) contacts the electronic components and the substrate; and The process of heating and compressing the loaded multilayer sheet. The (A) layer is a resin composition having a maximum value of 3 or more for tanδ (loss tangent) at a measurement temperature of 125°C and a measurement time of 0 to 100 seconds.

Images