TWI659058B - Epoxy resin composition and electrostatic capacitive fingerprint sensor - Google Patents

Abstract

The epoxy resin composition of the present invention is used to form an insulating film (105) constituting a capacitance type fingerprint sensor (100). The capacitance type fingerprint sensor includes: a substrate (101); a detection electrode (103), It is disposed on the substrate (101); and an insulating film (105) which seals the detection electrode (103). The epoxy resin composition of the present invention contains an epoxy resin (A) and an inorganic filler (B).

Description

Epoxy resin composition and electrostatic capacitance type fingerprint sensor

The invention relates to an epoxy resin composition and a electrostatic capacitance type fingerprint sensor.

The industry is researching various technologies for fingerprint sensors. For example, in Patent Document 1, a semiconductor fingerprint sensor that detects fingerprint information by a capacitance method is studied.

Patent Document 1 describes a fingerprint reading sensor in which an electrode is arranged in an array through an interlayer film on a substrate such as silicon, and an upper surface thereof is covered with an insulating film.

[Prior technical literature]

[Patent Literature]

Patent Document 1: Japanese Patent Application Laid-Open No. 2004-234245

A capacitive fingerprint sensor having a substrate, a detection electrode provided on the substrate, and an insulating film sealing the detection electrode is required to improve its sensitivity.

According to the present invention, there is provided an epoxy resin composition for forming an insulating film constituting a capacitance type fingerprint sensor. The capacitance type fingerprint sensor includes a substrate, a detection electrode disposed on the substrate, and insulation. A film that seals the detection electrode; and the epoxy resin composition contains: an epoxy resin (A) and an inorganic filler (B).

In addition, according to the present invention, there is provided a electrostatic capacitance type fingerprint sensor including: a substrate; a detection electrode provided on the substrate; and an insulating film that seals the detection electrode and uses the epoxy resin composition. Hardened.

According to the present invention, the sensitivity of the electrostatic capacitance type fingerprint sensor can be improved.

100‧‧‧Capacitive fingerprint sensor

101‧‧‧ substrate

103‧‧‧detection electrode

105‧‧‧ insulating film

107‧‧‧ interlayer film

D‧‧‧thickness

The above-mentioned object and other objects, features, and advantages can be made clearer by the preferred embodiments described below and the following drawings attached thereto.

FIG. 1 is a cross-sectional view schematically showing a capacitive fingerprint sensor according to this embodiment.

Hereinafter, embodiments will be described using drawings. In addition, in all drawings, the same constituent elements are marked with the same symbols, and descriptions thereof are appropriately omitted.

FIG. 1 is a cross-sectional view schematically showing a capacitive fingerprint sensor 100 according to this embodiment.

The capacitive fingerprint sensor 100 according to this embodiment includes a substrate 101, a detection electrode 103 provided on the substrate 101, and an insulating film 105 that seals the detection electrode 103. The insulating film 105 is formed of a cured product of an epoxy resin composition. The epoxy resin composition contains an epoxy resin (A) and an inorganic filler (B).

The present inventors have newly learned that by forming a hardened product of an epoxy resin composition containing an epoxy resin (A) and an inorganic filler (B) to form an insulating film that seals a detection electrode, the capacitance type can be improved. The sensitivity of the fingerprint sensor completes the structure of this embodiment.

According to this embodiment, the insulating film 105 that seals the detection electrode 103 is made of a hardened epoxy resin composition containing an epoxy resin (A) and an inorganic filler (B). Such a cured product is excellent in dielectric properties. Therefore, the sensitivity of the electrostatic capacitance type fingerprint sensor 100 can be improved. Here, in this embodiment, excellent dielectric characteristics means that, for example, the relative dielectric constant and dielectric loss tangent are high, and the electrostatic capacitance is large.

Hereinafter, the epoxy resin composition of this embodiment is demonstrated in detail.

The epoxy resin composition is used to form an insulation sealing the detection electrode 103 provided on the substrate 101. Rim membrane 105. The sealing molding using the epoxy resin composition is not particularly limited, and can be performed by, for example, a transfer molding method or a compression molding method. The epoxy resin composition is, for example, an ingot or a powder. When the epoxy resin composition is in the shape of an ingot, the epoxy resin composition can be molded using, for example, a transfer molding method. When the epoxy resin composition is a powder or a granule, the epoxy resin composition can be molded using, for example, a compression molding method. The case where the epoxy resin composition is a powder system means either a powder form or a granular form.

(Epoxy (A))

As the epoxy resin (A), all monomers, oligomers, and polymers having two or more epoxy groups in one molecule can be used, and the molecular weight or molecular structure is not particularly limited.

In this embodiment, examples of the epoxy resin (A) include a biphenyl epoxy resin; a bisphenol A epoxy resin, a bisphenol F epoxy resin, and a tetramethylbisphenol F epoxy resin. Bisphenol-type epoxy resins such as resins; 茋 -type epoxy resins; novolac-type epoxy resins such as phenol novolac-type epoxy resins, cresol novolac-type epoxy resins; triphenol methane-type epoxy resins, alkyl modification Polyfunctional epoxy resins such as triphenol methane epoxy resins; phenol aralkyl epoxy resins with phenylene skeleton, aralkyl epoxy resins with phenol aralkyl epoxy resin Epoxy resins; dihydroxynaphthalene-type epoxy resins, naphthol-type epoxy resins such as epoxy resins obtained by glycidyl etherification of dimers of dihydroxynaphthalene; triglycidyl isocyanurate, isocyanuric acid Monoallyl diglycidyl ester Core epoxy resin; dicyclopentadiene modified phenol type epoxy resin and other crosslinked cyclic hydrocarbon compounds modified phenol type epoxy resin; these can be used alone or in combination of two or more.

Among these, from the viewpoint of improving the balance between moisture resistance reliability and moldability, it is more preferable to contain a bisphenol type epoxy resin, a novolac type epoxy resin, a biphenyl type epoxy resin, and a phenol aralkyl group. It is particularly preferred that at least one of the epoxy resin of the type epoxy resin and the triphenol methane epoxy resin contains at least one of a biphenyl epoxy resin and a phenol aralkyl epoxy resin.

As the epoxy resin (A), it is particularly preferable to use an epoxy resin containing an epoxy resin represented by the following formula (1), an epoxy resin represented by the following formula (2), and a formula (3). At least one of the group consisting of epoxy resin.

(In the formula (1), Ar ¹ represents a phenylene group or a naphthyl group. When Ar ¹ is a naphthyl group, a glycidyl ether group may be bonded to any one of an α position and a β position; Ar ² represents a phenylene, biphenyl or extension extending either in the naphthyl group; R _a and R _b each independently represent a hydrocarbon group having 1 to 10 carbon atoms of; G is an integer of 0 to 5, h is 0 to 8 of Integer; n ³ represents the degree of polymerization, and its average value is 1 ~ 3)

(In formula (2), there are a plurality of R _c each independently representing a hydrogen atom or a hydrocarbon group having 1 to 4 carbon atoms; n ⁵ represents a degree of polymerization, and an average value thereof is 0 to 4)

(In the formula (3), there are a plurality of R _d and R _e each independently represent a hydrogen atom or a hydrocarbon group having 1 to 4 carbon atoms; n ⁶ represents a degree of polymerization, and an average value thereof is 0 to 4)

In the present embodiment, when the entire epoxy resin composition is 100% by mass, the content of the epoxy resin (A) in the epoxy resin composition is preferably 2% by mass or more, and more preferably 3% by mass. The above is particularly preferably 4% by mass or more. By setting the content of the epoxy resin (A) to be equal to or more than the above-mentioned lower limit value, sufficient fluidity can be achieved at the time of molding, and filling properties or moldability can be improved.

On the other hand, when the entire epoxy resin composition is 100% by mass, the content of the epoxy resin (A) in the epoxy resin composition is preferably 30% by mass or less, and more preferably 20% by mass or less. Especially preferably, it is 10 mass% or less. By setting the content of the epoxy resin (A) to be equal to or less than the above-mentioned upper limit value, it is possible to improve the humidity resistance reliability or the resistance of the capacitive fingerprint sensor 100 using the hardened material of the epoxy resin composition as the insulating film 105. Weldability.

(Inorganic filler (B))

The constituent material of the inorganic filler (B) is not particularly limited, and examples thereof include titanium oxide, tantalum pentoxide, niobium pentoxide, barium titanate, silicon dioxide, aluminum oxide, kaolin, talc, clay, mica, Rock wool, wollastonite, glass powder, glass flakes, glass beads, glass fiber, silicon carbide, silicon nitride, aluminum nitride, carbon black, graphite, titanium dioxide, calcium carbonate, calcium sulfate, barium carbonate, magnesium carbonate, sulfuric acid Magnesium, barium sulfate, cellulose, aromatic polyamide, wood, or pulverized powder obtained by pulverizing hardened material of phenol resin molding material or epoxy resin molding material, etc., can be used Any one of these.

Among these, an inorganic filler having a relative dielectric constant (1 MHz) of 5 or more is preferable, and from the viewpoint of improving the relative dielectric constant of the hardened body of the obtained epoxy resin composition, it is more preferable. One or two or more selected from titanium oxide, aluminum oxide, tantalum pentoxide, niobium pentoxide, and barium titanate are used, and one or two selected from alumina, titanium oxide, and barium titanate is further preferably used. It is more preferable to use one or two or more kinds selected from titanium oxide and barium titanate. From the viewpoint of suppressing oxidative degradation of the resin, rutile titanium oxide is particularly preferably used.

In this embodiment, when the entire epoxy resin composition is 100% by mass, the content of the inorganic filler (B) in the epoxy resin composition is preferably 50 masses relative to the entire epoxy resin composition. % Or more, more preferably 70% by mass or more, and even more preferably 80% by mass or more. By setting the content of the inorganic filler (B) above the above-mentioned lower limit value, the dielectric characteristics of the epoxy resin composition can be further improved, and the sensitivity of the electrostatic capacitance type fingerprint sensor 100 can be further improved.

On the other hand, when the entire epoxy resin composition is 100% by mass, the content of the inorganic filler (B) in the epoxy resin composition is preferably 97% by mass or less, and more preferably 95% by mass or less. By setting the content of the inorganic filler (B) to be equal to or less than the above-mentioned upper limit value, the flowability or filling property of the epoxy resin composition during molding can be more effectively improved.

The average particle diameter D _{50 of the} inorganic filler (B) is preferably 0.01 μm or more and 50 μm or less, and more preferably 0.1 μm or more and 30 μm or less. By setting the average particle diameter D ₅₀ to be at least the above-mentioned lower limit value, the fluidity of the epoxy resin composition can be made relatively good, and the moldability can be improved more effectively. Further, by setting the average particle diameter D ₅₀ to be equal to or less than the above-mentioned upper limit value, it is possible to reliably suppress the occurrence of gate blocking and the like. When the thickness D of the insulating film 105 on the substrate 101 (for example, a silicon wafer) is set to be as thin as 50 μm or less in order to improve the sensitivity of the fingerprint sensor, in order to suppress the unfilled epoxy resin composition, Defective, the average particle diameter D _{50 of the} inorganic filler (B) is preferably 10 μm or less, and more preferably 5 μm or less. The average particle diameter D ₅₀ can be measured using a commercially available laser particle size distribution meter (for example, SALD-7000 manufactured by Shimadzu Corporation) on a volume basis, and the median diameter (D ₅₀ ) Is set to an average particle diameter D ₅₀ .

As the titanium oxide, those known to those skilled in the art can be used.

The content of titanium oxide in the inorganic filler (B) is not particularly limited. For example, it is preferably 1% by mass or more and 100% by mass or less, more preferably 2% by mass or more and 80% with respect to the entire inorganic filler (B). Mass% or less, particularly preferably 5 mass% or more and 50 mass% or less.

By setting the content of titanium oxide to the above lower limit value, the dielectric characteristics of the epoxy resin composition can be further improved, and the sensitivity of the electrostatic capacitance type fingerprint sensor 100 can be further improved. In addition, by setting the content of titanium oxide to be equal to or less than the above-mentioned upper limit value, the fluidity of the epoxy resin composition can be made relatively good, and the moldability can be improved more effectively.

The average particle diameter D _{50 of the} titanium oxide is preferably 0.01 μm or more and 20 μm or less, and more preferably 0.1 μm or more and 15 μm or less. By setting the average particle diameter D ₅₀ to be at least the above-mentioned lower limit value, the fluidity of the epoxy resin composition can be made relatively good, and the moldability can be improved more effectively. Further, by setting the average particle diameter D ₅₀ to be equal to or less than the above-mentioned upper limit value, it is possible to reliably suppress the occurrence of gate blocking and the like. When the thickness D of the insulating film 105 on the substrate 101 (for example, a silicon wafer) is set to be as thin as 50 μm or less in order to improve the sensitivity of the fingerprint sensor, in order to suppress the unfilled epoxy resin composition, Defective, the average particle diameter D _{50 of the} titanium oxide is preferably 10 μm or less, and more preferably 5 μm or less.

As the barium titanate, those known to those skilled in the art can be used.

The content of barium titanate in the inorganic filler (B) is not particularly limited. The entire charge (B) is preferably 10 mass% or more and 100 mass% or less, more preferably 25 mass% or more and 90 mass% or less, and even more preferably 40 mass% or more and 75 mass% or less.

By setting the content of barium titanate to be above the lower limit, the dielectric characteristics of the epoxy resin composition can be further improved, and the sensitivity of the electrostatic capacitance type fingerprint sensor 100 can be further improved. In addition, by setting the content of barium titanate to be equal to or less than the above-mentioned upper limit value, the fluidity of the epoxy resin composition can be made relatively good, and the moldability can be improved more effectively.

The average particle diameter D _{50 of} barium titanate is preferably 0.01 μm or more and 20 μm or less, and more preferably 0.1 μm or more and 15 μm or less. By setting the average particle diameter D ₅₀ to be at least the above-mentioned lower limit value, the fluidity of the epoxy resin composition can be made relatively good, and the moldability can be improved more effectively. Further, by setting the average particle diameter D ₅₀ to be equal to or less than the above-mentioned upper limit value, it is possible to reliably suppress the occurrence of gate blocking and the like. When the thickness D of the insulating film 105 on the substrate 101 (for example, a silicon wafer) is set to be as thin as 50 μm or less in order to improve the sensitivity of the fingerprint sensor, in order to suppress the unfilled epoxy resin composition, Defective, the average particle diameter D _{50 of} barium titanate is preferably 10 μm or less, and more preferably 5 μm or less.

From the viewpoint of improving the sensitivity of the obtained fingerprint sensor and suppressing the warpage of the fingerprint sensor, the inorganic filler (B) is preferably used in combination with a material selected from the group consisting of titanium oxide, aluminum oxide, tantalum pentoxide, and pentoxide. One or two or more inorganic fillers of niobium and barium titanate and silicon dioxide, more preferably one or two or more inorganic fillers selected from the group consisting of alumina, titanium oxide, and barium titanate and dioxide The silicon particles are particularly preferably a combination of one or more inorganic fillers selected from titanium oxide and barium titanate and silicon dioxide particles.

In this embodiment, the inorganic filler (B) contains an average particle diameter of 1 μm from the viewpoint of improving the filling property of the epoxy resin composition or the viewpoint of suppressing the warpage of the fingerprint sensor. The following situation of fine powdered silica is one of the preferred aspects.

(Hardener (C))

The epoxy resin composition may contain a hardener (C), for example. The curing agent (C) is not particularly limited as long as it reacts with and cures the epoxy resin (A), and examples thereof include ethylenediamine, trimethylenediamine, tetramethylenediamine, Linear aliphatic diamines with 2 to 20 carbon atoms, such as hexamethylene diamine, m-phenylenediamine, p-phenylenediamine, p-xylylenediamine, 4,4'-diaminodiphenylmethane, 4 , 4'-diaminodiphenylpropane, 4,4'-diaminodiphenyl ether, 4,4'-diaminodiphenylphosphonium, 4,4'-diaminodicyclohexane, Bis (4-aminophenyl) phenylmethane, 1,5-diaminonaphthalene, m-xylylenediamine, p-xylylenediamine, 1,1-bis (4-aminophenyl) cyclohexane And amines such as dicyandiamide; soluble phenolic resins such as aniline modified phenolic resin or dimethyl ether soluble phenolic resin; phenol novolac resin, cresol novolac resin, third butylphenol Novolac resins such as novolac resins, nonylphenol novolac resins, triphenol methane-type phenol novolac resins; phenol aralkyl resins with a phenylene skeleton, and phenol aralkyl resins with a phenylene skeleton Isophenol aralkyl resin; with naphthalene Phenol resin with condensed polycyclic structure such as anthracene skeleton; polyhydroxystyrene such as polyparahydroxystyrene; including hexahydrophthalic anhydride (HHPA), methyltetrahydrophthalic anhydride (MTHPA), etc. Acid anhydrides such as alicyclic acid anhydrides, trimellitic anhydride (TMA), pyromellitic dianhydride (PMDA), benzophenone tetracarboxylic acid (BTDA), and other aromatic anhydrides; polysulfides, thioesters, sulfur Polythiol compounds such as ethers; isocyanate compounds such as isocyanate prepolymers and blocked isocyanates; organic acids such as carboxylic acid-containing polyester resins. These may be used individually by 1 type, and may be used in combination of 2 or more type.

The content of the hardener (C) in the epoxy resin composition is not particularly limited. For example, when the entire epoxy resin composition is 100% by mass, it is preferably 0.5% by mass or more and 20%. Mass% or less, more preferably 1.5 mass% or more and 20 mass% or less, still more preferably 2 mass% or more and 15 mass% or less, and even more preferably 2 mass% or more and 10 mass% or less.

(Coupling agent (D))

The epoxy resin composition may contain a coupling agent (D), for example. As the coupling agent (D), for example, various silane compounds such as epoxy silane, mercapto silane, amino silane, alkyl silane, ureido silane, vinyl silane, etc., titanium compounds, aluminum chelate compounds, aluminum / Known coupling agents such as zirconium-based compounds.

Examples of these include vinyltrichlorosilane, vinyltrimethoxysilane, vinyltriethoxysilane, vinyltri (β-methoxyethoxy) silane, and γ-formaldehyde. Allyl propyl methoxypropyltrimethoxysilane, β- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-glycidyloxy Propyltriethoxysilane, γ-glycidoxypropylmethyldimethoxysilane, γ-methacryloxypropylmethyldiethoxysilane, γ-methacryloxysilane Propyltriethoxysilane, vinyltriethoxysilane, γ-mercaptopropyltrimethoxysilane, γ-aminopropyltriethoxysilane, γ-anilinepropyltrimethoxysilane, γ-anilinepropylmethyldimethoxysilane, γ- [bis (β-hydroxyethyl)] aminopropyltriethoxysilane, N-β- (aminoethyl) -γ-amine Propyltrimethoxysilane, N-β- (aminoethyl) -γ-aminopropyltriethoxysilane, N-β- (aminoethyl) -γ-aminopropylmethyl Dimethoxysilane, N-phenyl-γ-aminopropyltrimethoxysilane, γ- ( β-aminoethyl) aminopropyldimethoxymethylsilane, N- (trimethoxysilylpropyl) ethylenediamine, N- (dimethoxymethylsilylisopropyl) ethyl Diamine, methyltrimethoxysilane, dimethyldimethoxysilane, methyltriethoxysilane, N-β- (N-vinylbenzylaminoethyl) -γ-aminopropyl Trimethoxysilane, γ-chloropropyltrimethoxysilane, Hexamethyldisila, vinyltrimethoxysilane, γ-mercaptopropylmethyldimethoxysilane, 3-isocyanatopropyltriethoxysilane, 3-propenyloxypropyltrimethoxysilane , 3-triethoxysilyl-N- (1,3-dimethyl-butylene) propylamine hydrolysate, and other silane-based coupling agents; isopropyltriisostearylfluorenyl titanate, isopropyl Propyltri (dioctylpyrophosphinooxy) titanate, isopropyltris (N-aminoethyl-aminoethyl) titanate, tetraoctylbis (di-tridecylidene) Phosphoniumoxy) titanate, tetra (2,2-dienyloxymethyl-1-butyl) bis (di-tridecylphosphoniumphosphoniumoxy) titanate, bis (dioctyl) Pyrophosphoryloxy) glycolic acid titanate, bis (dioctylpyrophosphinooxy) ethylene titanate, isopropyltrioctylfluorenyl titanate, isopropyldimethylpropenylisostearate Fluorenyl titanate, isopropyl tri-dodecylbenzenesulfonyl fluorinated titanate, isopropyl isostearyl fluorenyl dipropenyl fluorenyl titanate, isopropyl tris (dioctylphosphonium phosphonium oxide) Group) titanates such as titanate, isopropyltricumylphenyl titanate, tetraisopropylbis (dioctylphosphinofluorenyloxy) titanate, etc. Mixture. These may be used individually by 1 type, and may be used in combination of 2 or more type.

The content of the coupling agent (D) in the epoxy resin composition is not particularly limited. For example, when the entire epoxy resin composition is 100% by mass, it is preferably 0.01% by mass or more and 3% by mass or less, and particularly preferably It is 0.1 mass% or more and 2 mass% or less. When the content of the coupling agent (D) is at least the above lower limit value, the dispersibility of the inorganic filler (B) in the epoxy resin composition can be made relatively good. In addition, by setting the content of the coupling agent (D) to be equal to or lower than the above-mentioned upper limit value, the fluidity of the epoxy resin composition can be made relatively good, and the moldability can be improved.

(Other ingredients (E))

The epoxy resin composition may contain phosphorus, such as an organic phosphine, a tetra-substituted phosphonium compound, a phosphate betaine compound, an addition product of a phosphine compound and a quinone compound, or an addition product of a phosphonium compound and a silane compound, in addition to the above components Atomic compounds, or 1,8-diazabicyclo (5.4.0) undecene -7, hardening accelerators such as ammonium compounds such as imidazole, tertiary amines such as benzyldimethylamine, or sulfonium or ammonium salts such as the quaternary onium salts of the above compounds; nitrogen black compounds; And other coloring agents; polybutadiene compounds, acrylonitrile butadiene copolymers, natural waxes, synthetic waxes, higher fatty acids or their metal salts, paraffin, polyethylene oxide and other release agents; silicone oil, polysilicone Low-stress agents such as oxygen rubber; ion trapping agents such as hydrotalcite; flame retardants such as aluminum hydroxide; various additives such as antioxidants.

The relative dielectric constant (ε _r ) of the hardened body of the epoxy resin composition at 1 MHz is preferably 5 or more, more preferably 7 or more, and even more preferably 8 or more. By setting the relative dielectric constant (ε _r ) to be above the lower limit value, the dielectric characteristics of the epoxy resin composition can be further improved, and the sensitivity of the electrostatic capacitance type fingerprint sensor 100 can be further improved.

When the epoxy resin composition is in the form of an ingot, the hardened body of the epoxy resin composition is injected, for example, by using a transfer molding machine at a mold temperature of 175 ° C, an injection pressure of 9.8 MPa, and a curing time of 300 seconds. An epoxy resin composition is obtained by molding. The hardened body has, for example, a diameter of 50 mm and a thickness of 3 mm.

In the case where the epoxy resin composition is a powder or a granule, the hardened body of the epoxy resin composition is, for example, by using a compression molding machine at a mold temperature of 175 ° C, a molding pressure of 9.8 MPa, and a curing time of 300 seconds , Obtained by injecting and molding the epoxy resin composition. The hardened body has, for example, a diameter of 50 mm and a thickness of 3 mm.

The relative dielectric constant (ε _r ) of the hardened body can be measured using, for example, Q-METER 4342A manufactured by YOKOGAWA-HEWLETT PACKARD.

The upper limit of the relative dielectric constant (ε _r ) is not particularly limited, and is, for example, 300 or less.

The dielectric loss tangent of the hardened body of the epoxy resin composition at 1 MHz (tan δ) is preferably 0.005 or more, more preferably 0.006 or more, and even more preferably 0.007 or more.

By making the dielectric loss tangent (tan δ) above the above-mentioned lower limit value, the dielectric characteristics of the epoxy resin composition can be further improved, and the sensitivity of the electrostatic capacitance type fingerprint sensor 100 can be further improved.

When the epoxy resin composition is in the form of an ingot, the hardened body of the epoxy resin composition is injected, for example, by using a transfer molding machine at a mold temperature of 175 ° C, an injection pressure of 9.8 MPa, and a curing time of 300 seconds. An epoxy resin composition is obtained by molding. The hardened body has, for example, a diameter of 50 mm and a thickness of 3 mm.

In the case where the epoxy resin composition is a powder or a granule, the hardened body of the epoxy resin composition is, for example, using a compression molding machine under conditions of a mold temperature of 175 ° C, a molding pressure of 9.8 MPa, and a curing time of 300 seconds. , Obtained by injecting and molding the epoxy resin composition. The hardened body has, for example, a diameter of 50 mm and a thickness of 3 mm.

The dielectric loss tangent (tan δ) of the hardened body can be measured using, for example, Q-METER 4342A manufactured by YOKOGAWA-HEWLETT PACKARD.

The upper limit of the dielectric loss tangent (tan δ) is not particularly limited, and is, for example, 0.07 or less.

The above-mentioned relative dielectric constant (ε _r ) and the above-mentioned dielectric loss tangent (tan δ) can be controlled by appropriately adjusting the kind or blending ratio of each component constituting the epoxy resin composition. In this embodiment, a case where the type of the inorganic filler (B) is appropriately selected is cited as a factor for controlling the relative dielectric constant (ε _r ) and the dielectric loss tangent (tan δ). For example, the more the inorganic filler with a larger dielectric constant is used, the more the relative dielectric constant (ε _r ) and the dielectric loss tangent (tan δ) of the hardened body of the epoxy resin composition can be improved. .

The epoxy resin composition is preferably an example of the flow length measured by cyclone measurement. If it is 30 cm or more and 200 cm or less, it is more preferably 40 cm or more and 150 cm or less. Thereby, the moldability of an epoxy resin composition can be improved. In this embodiment, the swirl measurement of the epoxy resin composition is based on, for example, using a transfer molding machine under conditions of a mold temperature of 175 ° C, an injection pressure of 9.8 MPa, an injection time of 15 seconds, and a curing time of 120 to 180 seconds An epoxy resin composition was poured into a mold for swirl measurement of EMMI-1-66, and the flow length was measured.

In this embodiment, the glass transition temperature of the hardened body of the epoxy resin composition is preferably 100 ° C or higher, and more preferably 120 ° C or higher. Thereby, the heat resistance of the fingerprint sensor can be improved more effectively. On the other hand, the upper limit of the glass transition temperature is not particularly limited, and may be, for example, 250 ° C.

In this embodiment, the linear expansion coefficient (CTE1) of the hardened body of the epoxy resin composition below the glass transition temperature is preferably 3 ppm / ° C or more, and more preferably 6 ppm / ° C or more. The coefficient of linear expansion (CTE1) below the glass transition temperature is, for example, preferably 50 ppm / ° C or less, and more preferably 30 ppm / ° C or less. By controlling CTE1 in this manner, it is possible to more surely suppress the warpage of the fingerprint sensor caused by the difference in linear expansion coefficient between the substrate 101 (for example, a silicon wafer) and the insulating film 105.

In this embodiment, the linear expansion coefficient (CTE2) of the hardened body of the epoxy resin composition when it exceeds the glass transition temperature is preferably 10 ppm / ° C or more. The linear expansion coefficient (CTE2) when the glass transition temperature is exceeded is, for example, preferably 100 ppm / ° C or lower. By controlling the CTE2 in this manner, it is possible to more surely suppress the warpage of the fingerprint sensor caused by the difference in linear expansion coefficient between the substrate 101 (for example, a silicon wafer) and the insulating film 105 in a high temperature environment.

The glass transition temperature and the linear expansion coefficients (CTE1, CTE2) of the cured body of the epoxy resin composition can be measured, for example, as follows.

First, when the epoxy resin composition is in the form of an ingot, the hardened body of the epoxy resin composition is, for example, by using a transfer molding machine at a mold temperature of 175 ° C, an injection pressure of 9.8 MPa, and a curing time of 300 seconds. It is obtained by injecting and shaping the above-mentioned epoxy resin composition. The hardened body has, for example, a length of 10 mm, a width of 4 mm, and a thickness of 4 mm.

In the case where the epoxy resin composition is a powder or a granule, the hardened body of the epoxy resin composition is, for example, using a compression molding machine under conditions of a mold temperature of 175 ° C, a molding pressure of 9.8 MPa, and a curing time of 300 seconds. , Obtained by injecting and molding the epoxy resin composition. The hardened body has, for example, a length of 10 mm, a width of 4 mm, and a thickness of 4 mm.

Then, the obtained hardened body was post-cured at 175 ° C for 4 hours, and then a thermomechanical analysis device (TMA100 manufactured by Seiko Instruments Industries Co., Ltd.) was used to measure the temperature range from 0 ° C to 320 ° C and the heating rate to 5 ° C / The measurement was performed under the condition of min. Based on the measurement results, the glass transition temperature, the linear expansion coefficient (CTE1) below the glass transition temperature, and the linear expansion coefficient (CTE2) when the glass transition temperature was exceeded were calculated.

The glass transition temperature, the coefficient of linear expansion (CTE1) below the glass transition temperature, and the coefficient of linear expansion (CTE2) above the glass transition temperature can be adjusted by appropriately adjusting the type or blending ratio of each component constituting the epoxy resin composition. Take control. In this embodiment, a case where the type of the inorganic filler (B) is appropriately selected is cited as a factor for controlling CTE1 and CTE2. For example, by using silicon dioxide particles having a smaller linear expansion coefficient as the inorganic filler (B), the CTE1 and CTE2 of the hardened body of the epoxy resin composition can be reduced.

Hereinafter, the configuration of the electrostatic capacitance type fingerprint sensor 100 according to this embodiment will be described in detail.

The electrostatic capacitance type fingerprint sensor 100 of this embodiment is A fingerprint sensor that reads fingerprint information by the electrostatic capacitance method of the finger. Here, the fingerprint sensor reads the unevenness of a finger placed on the fingerprint sensor. For example, the electrostatic capacitance type fingerprint sensor 100 is provided with a detection electrode 103 which is smaller than the unevenness of the fingerprint. Furthermore, a two-dimensional image showing the unevenness of the fingerprint is produced using the electrostatic capacitance stored between the unevenness of the fingerprint and the detection electrode 103. For example, since the electrostatic capacitance measured at the convex portion and the concave portion of the fingerprint is different, a two-dimensional image representing the unevenness of the fingerprint can be produced based on the difference in the electrostatic capacitance. The fingerprint information can be read from the two-dimensional image.

FIG. 1 is a cross-sectional view schematically showing a capacitive fingerprint sensor 100 according to this embodiment.

The capacitive fingerprint sensor 100 according to this embodiment includes a substrate 101, a detection electrode 103 provided on the substrate 101, and an insulating film 105 that seals the detection electrode 103.

In this embodiment, the insulating film 105 is formed of a cured product of an epoxy resin composition. As the epoxy resin composition, for example, the above components can be mixed by a known means, and further melt-kneaded by a kneading machine such as a roll, a kneader, or an extruder, and pulverized after cooling; and pulverized by ingot molding Those who are in the shape of a tablet; and those who appropriately adjust the degree of dispersion or fluidity as needed.

In order to improve the sensitivity of the fingerprint sensor, the thickness D of the insulating film 105 on the substrate 101 (for example, a silicon wafer) is, for example, 100 μm or less, more preferably 75 μm or less, and even more preferably 50 μm or less.

The substrate 101 is, for example, a wafer-shaped silicon substrate. The detection electrodes 103 are formed of, for example, an Al film, and are arranged in a one-dimensional or two-dimensional array shape on the substrate 101 via an interlayer film 107. The interlayer film 107 is formed of, for example, SiO ₂ .

The upper surface of the detection electrode 103 is covered with an insulating film 105. For example, the detection electrode 103 is Line bonding.

The capacitive fingerprint sensor 100 of this embodiment can be manufactured based on known information. For example, it manufactures as follows.

First, an interlayer film 107 is provided on the substrate 101, and then a detection electrode 103 is formed on the interlayer film 107. Then, the detection electrode 103 is hermetically sealed with an epoxy resin composition. Examples of the molding method include a transfer molding method, a compression molding method, and a cast molding method. Then, the epoxy resin composition is thermally cured to form an insulating film 105. Thereby, the electrostatic capacitance type fingerprint sensor 100 of this embodiment is obtained.

Next, the effect of this embodiment will be described.

According to this embodiment, the insulating film 105 of the sealed detection electrode 103 is made of a cured product of an epoxy resin composition containing an epoxy resin (A) and an inorganic filler (B). Since the hardened material of the epoxy resin composition has excellent dielectric properties, the sensitivity of the electrostatic capacitance type fingerprint sensor 100 can be improved.

[Example]

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

(Preparation of epoxy resin composition)

Regarding Examples 1 to 9, an epoxy resin composition was prepared as follows. First, each component blended in accordance with Table 1 was mixed at room temperature using a high-speed mixer. Next, the obtained mixture was subjected to roll kneading (high-temperature side roll surface temperature: 90 ° C, low-temperature side roll surface temperature: 25 ° C), and then cooled and pulverized with a mixer to obtain an epoxy resin composition. The details of each component in Table 1 are as follows.

(A) Epoxy resin

Epoxy resin 1: Biphenyl type epoxy resin (YX-4000K manufactured by Mitsubishi Chemical Corporation)

(B) inorganic filler

Inorganic filler 1: Alumina (DAB-45SI manufactured by Denka Kogyo Co., Ltd., D ₅₀ = 17 μm)

Inorganic filler 2: Silicon dioxide (FB105, D ₅₀ = 10 μm, manufactured by Denka Kogyo Co., Ltd.)

Inorganic filler 3: Silicon dioxide (REOLOSIL CP-102 manufactured by Tokuyama, D ₅₀ = 1 μm or less)

Inorganic filler 4: Silicon dioxide (SO-25R manufactured by Admatechs, D ₅₀ = 0.5 μm)

Inorganic filler 5: Titanium oxide (IV) (PF-726 manufactured by Ishihara Industries, D ₅₀ = 1 μm, rutile type, and the content of titanium oxide having a particle diameter of 32 μm or more is 5% by mass or less)

Inorganic filler 6: Barium titanate (Palceram BT-UP2 manufactured by Nippon Chemical Industry Co., D ₅₀ = 2 μm, and the content of barium titanate with a particle diameter of 32 μm or more is 5% by mass or less)

Inorganic filler 7: alumina (AX3-15R manufactured by Micron, the content of alumina having a particle size of 15 μm or more is 5% by mass or less, D ₅₀ = 4 μm)

(C) Hardener

Hardener 1: Triphenol methane type phenol novolac resin (MEH-7500, manufactured by Meiwa Chemical Co., Ltd.)

Hardener 2: Triphenol methane type phenol novolac resin (HE910-20, manufactured by Air Water)

(D) Coupling agent

Coupling agent 1: N-phenyl-γ-aminopropyltrimethoxysilane (CF4083 manufactured by Toray Dow Corning)

(E) Other ingredients

Hardening accelerator 1: Hardening accelerator represented by the following formula (4)

[Synthesis method of hardening accelerator 1]

A separable flask equipped with a stirring device was charged with 37.5 g of 4,4'-bisphenol S (0.15 mol) and 100 ml of methanol, and the mixture was stirred at room temperature to dissolve the mixture. A solution of 4.0 g (0.1 mol) of sodium hydroxide was dissolved in 50 ml of methanol. Then, a solution in which 41.9 g (0.1 mol) of tetraphenylphosphonium bromide was dissolved in 150 ml of methanol in advance was added. Stirring was continued for a while, after adding 300 ml of methanol, the solution in the flask was added dropwise to a large amount of water while stirring, to obtain a white precipitate. The precipitate was filtered and dried to obtain a white crystal hardening accelerator 1.

Hardening accelerator 2: Hardening accelerator represented by the following formula (5)

[Synthesis method of hardening accelerator 2]

In a flask containing 1800 g of methanol, 249.5 g of phenyltrimethoxysilane and 384.0 g of 2,3-dihydroxynaphthalene were added and dissolved, followed by dropwise addition of 231.5 g of a 28% sodium methoxide-methanol solution under stirring at room temperature . When further stirring at room temperature, 503.0 g of tetraphenylphosphonium bromide prepared in advance is dissolved in A solution of 600 g of methanol was added dropwise thereto, and crystals were precipitated. The precipitated crystals were filtered, washed with water, and dried under vacuum to obtain a hardening accelerator 2 for peach white crystals.

Low stress agent 1: acrylonitrile butadiene rubber (carboxy-terminated butadiene acrylic rubber manufactured by Ube Kosan Co., Ltd., CTBN1008SP)

Low Stress Agent 2: Polysiloxane

Colorant: carbon black

Release Agent: Carnauba Wax

Ion trapping agent: Hydrotalcite

(Measurement of Relative Dielectric Constant and Dielectric Loss Tangent)

With respect to Examples 1 to 9, the relative dielectric constant and the dielectric loss tangent of the epoxy resin composition were measured as follows. Using a low-pressure transfer molding machine ("KTS-30" manufactured by Kohtaki Precision Machine Co., Ltd.), the above-mentioned epoxy resin composition was injected into a mold at a mold temperature of 175 ° C, an injection pressure of 9.8 MPa, and a curing time of 300 seconds. Then, it is shaped to obtain a hardened body of the epoxy resin composition. This hardened body has a diameter of 50 mm and a thickness of 3 mm.

Then, with respect to the obtained hardened body, Q-METER 4342A manufactured by YOKOGAWA-HEWLETT PACKARD was used to measure the relative dielectric constant and dielectric loss tangent at 1 MHz and room temperature (25 ° C). The results are shown in Table 1.

(Determination of Swirl)

Regarding Examples 1 to 9, the swirl measurement of the epoxy resin composition was performed as follows. Using a low-pressure transfer molding machine ("KTS-15" manufactured by Kohtaki Precision Machine Co., Ltd.), the mold temperature was 175 ° C, the injection pressure was 9.8 MPa, the injection time was 15 seconds, and the hardening time was 180 seconds. -66 Injecting epoxy resin into the mold for swirl measurement As a result, the flow length was measured. The unit in Table 1 is cm. The results are shown in Table 1.

(Glass transition temperature, linear expansion coefficient)

For each example, the glass transition temperature (Tg) and linear expansion coefficients (CTE1, CTE2) of the hardened body of the epoxy resin composition were measured as follows. Using a low-pressure transfer molding machine ("KTS-30" manufactured by Kohtaki Precision Machine Co., Ltd.), the above-mentioned epoxy resin composition was injected into a mold at a mold temperature of 175 ° C, an injection pressure of 9.8 MPa, and a curing time of 300 seconds. Then, it is shaped to obtain a hardened body of the epoxy resin composition. The hardened body has a length of 10 mm, a width of 4 mm, and a thickness of 4 mm.

Then, the obtained hardened body was post-cured at 175 ° C for 4 hours, and then a thermomechanical analysis device (TMA100 manufactured by Seiko Instruments Industries Co., Ltd.) was used to measure the temperature range from 0 ° C to 320 ° C and the heating rate to 5 ° C / The measurement was performed under the condition of min. Based on the measurement results, the glass transition temperature (Tg), the linear expansion coefficient (CTE1) below the glass transition temperature, and the linear expansion coefficient (CTE2) when the glass transition temperature was exceeded were calculated. The results are shown in Table 1.

(Sensitivity measurement of electrostatic capacitance type fingerprint sensor)

Regarding each of Examples 1 to 9, the electrostatic capacitance type fingerprint sensor shown in FIG. 1 was produced using the obtained epoxy resin composition. Then, a two-dimensional image showing the unevenness of the fingerprint is produced using the obtained electrostatic capacitance type fingerprint sensor.

The electrostatic capacitance type fingerprint sensors obtained in Examples 1 to 9 all clearly displayed a two-dimensional image of the fingerprint, and showed a result of good sensitivity. Among these, Examples 2 to 9 having particularly excellent dielectric characteristics obtained a clearer two-dimensional image of the fingerprint compared with Example 1 and showed excellent sensitivity. In addition, Examples 1 to 3, 6 to 7, and 9 showed excellent results in the formability test.

In addition, with regard to the capacitive fingerprint sensors obtained in Examples 1 to 9, warpage was suppressed. In addition, the CTE1 of the hardened bodies of the epoxy resin compositions obtained in Examples 1 to 9 were all within a range of 3 ppm / ° C or more and 50 ppm / ° C or less. Moreover, the CTE2 of the hardened | cured material of the epoxy resin composition obtained by Example 1-9 was in the range of 10 ppm / C or more and 100 ppm / C or less.

In addition, making the thickness D of the insulating film 105 thinner is related to the sensitivity of the fingerprint sensor. Therefore, it is preferable that the inorganic filler (B) is formed by cutting coarse particles to prevent non-filling during molding. Regarding the epoxy resin composition of Examples 7 to 9, even if the thickness D of the insulating film 105 is set to 50 μm, the fingerprint sensor can be formed without being filled, which is similar to the epoxy resin composition of Examples 1 to 6. Excellent specific moldability. In addition, regarding the epoxy resin compositions of Examples 7 to 9, even if the thickness D of the insulating film 105 was set to 50 μm, no warpage of the fingerprint sensor occurred. That is, the epoxy resin compositions of Examples 7 to 9 clearly showed a two-dimensional image of a fingerprint, showed good sensitivity, and exhibited more excellent moldability.

This application claims priority based on Japanese Patent Application No. 2014-062446 filed on March 25, 2014, the entire contents of which are incorporated herein.

Claims (9)

An epoxy resin composition is used to form an insulating film constituting a capacitance type fingerprint sensor. The capacitance type fingerprint sensor includes: a substrate; a detection electrode disposed on the substrate; and an insulating film that seals the above. A detection electrode; and the epoxy resin composition contains: an epoxy resin (A) and an inorganic filler (B); the inorganic filler (B) contains one or two or more kinds selected from titanium oxide and barium titanate , And silica particles. For example, the epoxy resin composition according to item 1 of the patent application scope, wherein the relative dielectric constant (ε _r ) of the hardened body of the epoxy resin composition at 1 MHz is 8 or more. For example, the epoxy resin composition of the first or second patent application range, wherein the dielectric loss tangent (tan δ) of the hardened body of the above epoxy resin composition at 1 MHz is 0.006 or more. For example, the epoxy resin composition according to item 1 of the patent application range, wherein the inorganic filler (B) contains the titanium oxide, and the titanium oxide is a rutile type. For example, the epoxy resin composition in the first or second scope of the patent application, wherein the flow length measured by swirl measurement under the conditions of a mold temperature of 175 ° C, an injection pressure of 9.8 MPa, and an injection time of 15 seconds is 30 cm or more And below 200cm. For example, the epoxy resin composition of the scope of application for item 1 or 2, wherein the glass transition temperature of the hardened body of the epoxy resin composition is 100 ° C or higher. For example, the epoxy resin composition of the first or second patent application range, wherein the linear expansion coefficient (CTE1) of the hardened body of the above epoxy resin composition below the glass transition temperature is 3 ppm / ° C or more and 50 ppm / ° C or less. For example, the epoxy resin composition of the first or second patent application range, wherein the linear expansion coefficient (CTE2) of the hardened body of the above epoxy resin composition when it exceeds the glass transition temperature is 10 ppm / ° C or more and 100 ppm / ° C or less . A capacitive fingerprint sensor includes: a substrate; a detection electrode disposed on the substrate; and an insulating film that seals the detection electrode, and passes a ring in any of claims 1 to 8 of the scope of patent application. It is formed by a cured product of an oxygen resin composition.