JP6658508B2 - Epoxy resin composition and capacitance type fingerprint sensor - Google Patents

Description

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

Various technologies are being studied for fingerprint sensors. For example, Patent Document 1 discusses a semiconductor fingerprint sensor that detects fingerprint information by a capacitance method.
Patent Document 1 describes a fingerprint reading sensor in which electrodes are arranged in an array on a substrate such as silicon via an interlayer film, and the upper surface thereof is overcoated with an insulating film.

JP 2004-234245 A

  It is required to improve the sensitivity of a capacitance type fingerprint sensor including a substrate, a detection electrode provided on the substrate, and an insulating film for sealing the detection electrode.

According to the present invention,
Board and
A detection electrode provided on the substrate,
An insulating film for sealing the detection electrode,
An epoxy resin composition used for forming the insulating film constituting a capacitance type fingerprint sensor comprising:
Epoxy resin (A),
An inorganic filler (B),
A curing agent (C),
Including
The amount of the inorganic filler (B) is 50% by mass or more and 97% by mass or less with respect to the entire epoxy resin composition;
Wherein the inorganic filler (B) comprises at least one kind selected from titanium oxide and barium titanate, and silica particles,
An epoxy resin composition is provided.

According to the present invention,
Board and
A detection electrode provided on the substrate,
Sealing the detection electrode, and an insulating film formed of a cured product of the epoxy resin composition,
A capacitive fingerprint sensor comprising:

  ADVANTAGE OF THE INVENTION According to this invention, the sensitivity of a capacitance-type fingerprint sensor can be improved.

  The above and other objects, features and advantages will become more apparent from the preferred embodiments described below and the accompanying drawings.

FIG. 1 is a cross-sectional view schematically illustrating a capacitance type fingerprint sensor according to an embodiment.

  Hereinafter, embodiments will be described with reference to the drawings. In all the drawings, the same components are denoted by the same reference numerals, and description thereof will not be repeated.

FIG. 1 is a sectional view schematically showing a capacitance type fingerprint sensor 100 according to the present embodiment.
The capacitance type fingerprint sensor 100 according to the present embodiment includes a substrate 101, a detection electrode 103 provided on the substrate 101, and an insulating film 105 sealing the detection electrode 103. The insulating film 105 is formed of a cured product of an epoxy resin composition. Further, the epoxy resin composition contains an epoxy resin (A) and an inorganic filler (B).

The present inventor provides a capacitance type fingerprint sensor by forming an insulating film for sealing a detection electrode with a cured product of an epoxy resin composition containing an epoxy resin (A) and an inorganic filler (B). Has newly found that the sensitivity of the present invention can be improved, and has arrived at the configuration of the present embodiment.
According to the present embodiment, the insulating film 105 for sealing the detection electrode 103 is made of a cured product of the epoxy resin composition containing the epoxy resin (A) and the inorganic filler (B). Such a cured product has excellent dielectric properties. Therefore, the sensitivity of the capacitance type fingerprint sensor 100 can be improved. Here, in the present embodiment, “excellent in dielectric properties” means that, for example, the relative dielectric constant and the dielectric loss tangent are high, and the capacitance is large.

Hereinafter, the epoxy resin composition according to the present embodiment will be described in detail.
The epoxy resin composition is used to form an insulating film 105 that seals the detection electrode 103 provided on the substrate 101. The sealing molding using the epoxy resin composition is not particularly limited, but can be performed by, for example, a transfer molding method or a compression molding method. The epoxy resin composition is, for example, in the form of a tablet or powder. When the epoxy resin composition is in the form of a tablet, the epoxy resin composition can be molded using, for example, a transfer molding method. When the epoxy resin composition is a granular material, the epoxy resin composition can be molded by, for example, a compression molding method. The phrase “the epoxy resin composition is in the form of a powder” refers to a case where the epoxy resin composition is in a powdery or granular form.

(Epoxy resin (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 and molecular structure are not particularly limited.
In the present embodiment, as the epoxy resin (A), for example, a biphenyl type epoxy resin; a bisphenol type epoxy resin such as a bisphenol A type epoxy resin, a bisphenol F type epoxy resin, a tetramethyl bisphenol F type epoxy resin; a stilbene type epoxy resin; Novolak type epoxy resins such as phenol novolak type epoxy resin and cresol novolak type epoxy resin; polyfunctional epoxy resins such as triphenolmethane type epoxy resin and alkyl-modified triphenolmethane type epoxy resin; phenol aralkyl type epoxy resin having a phenylene skeleton; Aralkyl-type epoxy resins such as phenol-aralkyl-type epoxy resins having a biphenylene skeleton; dihydroxynaphthalene-type epoxy resins, dimer of dihydroxynaphthalene Naphthol type epoxy resin such as epoxy resin obtained by glycidyl etherification of epoxy resin; triazine nucleus containing epoxy resin such as triglycidyl isocyanurate and monoallyl diglycidyl isocyanurate; bridged cyclic hydrocarbon such as dicyclopentadiene-modified phenol type epoxy resin Compound-modified phenolic epoxy resins may be mentioned, and these may 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, bisphenol-type epoxy resins, novolak-type epoxy resins, biphenyl-type epoxy resins, phenol-aralkyl-type epoxy resins, and triphenolmethane-type epoxy resins It is more preferable to include at least one, and particularly preferable to include at least one of a biphenyl type epoxy resin and a phenol aralkyl type epoxy resin.

  The epoxy resin (A) is selected from the group consisting of an epoxy resin represented by the following formula (1), an epoxy resin represented by the following formula (2), and an epoxy resin represented by the following formula (3). It is particularly preferable to use one containing at least one of the following.

（式（１）中、Ａｒ^１はフェニレン基またはナフチレン基を表し、Ａｒ^１がナフチレン基の場合、グリシジルエーテル基はα位、β位のいずれに結合していてもよい。Ａｒ^２はフェニレン基、ビフェニレン基またはナフチレン基のうちのいずれか１つの基を表す。Ｒ_ａおよびＲ_ｂは、それぞれ独立に炭素数１〜１０の炭化水素基を表す。ｇは０〜５の整数であり、ｈは０〜８の整数である。ｎ^３は重合度を表し、その平均値は１〜３である）

(In the formula (1), Ar ¹ represents a phenylene group or a naphthylene group. When Ar ¹ is a naphthylene group, the glycidyl ether group may be bonded to either the α-position or the β-position. Ar ² is a phenylene group. , A biphenylene group or a naphthylene group, wherein R _a and R _b each independently represent a hydrocarbon group having 1 to 10 carbon atoms, g is an integer of 0 to 5, and h Is an integer of 0 to 8. n3 represents the degree of polymerization, and the average value is 1 to ^3. )

（式（２）中、複数存在するＲ_ｃは、それぞれ独立に水素原子または炭素数１〜４の炭化水素基を表す。ｎ^５は重合度を表し、その平均値は０〜４である）

(In the formula (2), a plurality of R _c independently represent a hydrogen atom or a hydrocarbon group having 1 to 4 carbon atoms. N ⁵ represents a degree of polymerization, and the average value thereof is 0 to 4)

（式（３）中、複数存在するＲ_ｄおよびＲ_ｅは、それぞれ独立に水素原子又は炭素数１〜４の炭化水素基を表す。ｎ^６は重合度を表し、その平均値は０〜４である）

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

In this embodiment, 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 or more when the entire epoxy resin composition is 100% by mass. It is more preferable that the content be 4% by mass or more. By setting the content of the epoxy resin (A) to the above lower limit or more, sufficient fluidity can be realized at the time of molding, and the filling property and moldability can be improved.
On the other hand, 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, when the entire epoxy resin composition is 100% by mass. It is more preferable that the content be 10% by mass or less. By setting the content of the epoxy resin (A) to the above upper limit or less, the moisture resistance reliability and the reflow resistance of the capacitance type fingerprint sensor 100 using the cured product of the epoxy resin composition as the insulating film 105 are improved. be able to.

(Inorganic filler (B))
The constituent material of the inorganic filler (B) is not particularly limited. For example, titanium oxide, tantalum pentoxide, niobium pentoxide, barium titanate, silica, alumina, kaolin, talc, clay, mica, rock wool, wollast Knight, glass powder, glass flake, glass beads, glass fiber, silicon carbide, silicon nitride, aluminum nitride, carbon black, graphite, titanium dioxide, calcium carbonate, calcium sulfate, barium carbonate, magnesium carbonate, magnesium sulfate, barium sulfate, cellulose , Aramid, wood, or pulverized powder obtained by pulverizing a cured product of a phenol resin molding material or an epoxy resin molding material, and any one or more of these can be used.
Among these, inorganic fillers having a relative dielectric constant (1 MHz) of preferably 5 or more are preferable, and titanium oxide, alumina, pentoxide, and the like can be particularly improved from the viewpoint of improving the relative dielectric constant of a cured product of the obtained epoxy resin composition. It is more preferable to use one or more selected from tantalum, niobium pentoxide, barium titanate, and it is more preferable to use one or more selected from alumina, titanium oxide and barium titanate, It is more preferable to use one or two or more selected from titanium and barium titanate. From the viewpoint of suppressing the oxidative deterioration of the resin, it is particularly preferable to use rutile type titanium oxide.

In the present embodiment, the content of the inorganic filler (B) in the epoxy resin composition is 50% by mass or more based on the entire epoxy resin composition, when the entire epoxy resin composition is 100% by mass. Is preferably 70% by mass or more, and particularly preferably 80% by mass or more. By setting the content of the inorganic filler (B) to the above lower limit or more, the dielectric properties of the epoxy resin composition can be further improved, and the sensitivity of the capacitance type fingerprint sensor 100 can be further improved.
On the other hand, 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 when the entire epoxy resin composition is 100% by mass. Is more preferred. When the content of the inorganic filler (B) is equal to or less than the above upper limit, it is possible to more effectively improve the fluidity and the filling property during molding of the epoxy resin composition.

The average particle diameter _{D 50} of the inorganic filler (B) is preferably 0.01μm or more 50μm or less, more preferably 0.1μm or 30μm or less. By the average particle diameter D ₅₀ of less than the above lower limit, the fluidity of the epoxy resin composition is made excellent, it is possible to improve the formability more effectively. Further, by the average particle diameter D ₅₀ and more than the above upper limit can reliably prevent the gate clogging occurs. In addition, when the thickness D of the insulating film 105 on the substrate 101 (for example, a silicon chip) is made as thin as 50 μm or less to improve the sensitivity of the fingerprint sensor, unfilling failure of the epoxy resin composition is suppressed. to, it is preferable that the average particle size D ₅₀ of the inorganic filler (B) is 10μm or less, more preferably 5μm or less. The average particle diameter _{D 50} is a commercially available laser particle size distribution analyzer (e.g., manufactured by Shimadzu Corporation, SALD-7000) was used to measure the particle size distribution of the particles on a volume basis, the median diameter (D ₅₀ ) can be taken as the average particle size 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, but is, for example, preferably 1% by mass or more and 100% by mass or less, and more preferably 2% by mass or more based on the entire inorganic filler (B). The content is more preferably 80% by mass or less, particularly preferably 5% by mass or more and 50% by mass or less.
When the content of titanium oxide is equal to or more than the lower limit, the dielectric properties of the epoxy resin composition can be further improved, and the sensitivity of the capacitance fingerprint sensor 100 can be further improved. When the content of the titanium oxide is equal to or less than the upper limit, the fluidity of the epoxy resin composition can be improved, and the moldability can be more effectively improved.
The average particle diameter _{D 50} of the titanium oxide is preferably 0.01μm or more 20μm or less, more preferably 0.1μm or 15μm or less. By the average particle diameter D ₅₀ of less than the above lower limit, the fluidity of the epoxy resin composition is made excellent, it is possible to improve the formability more effectively. Further, by the average particle diameter D ₅₀ and more than the above upper limit can reliably prevent the gate clogging occurs. In addition, when the thickness D of the insulating film 105 on the substrate 101 (for example, a silicon chip) is made as thin as 50 μm or less to improve the sensitivity of the fingerprint sensor, unfilling failure of the epoxy resin composition is suppressed. to an average particle diameter D ₅₀ of titanium oxide is preferably 10μm or less, more preferably 5μm 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, but is preferably, for example, from 10% by mass to 100% by mass, and more preferably 25% by mass, based on the entire inorganic filler (B). The content is more preferably 90% by mass or less, and particularly preferably 40% by mass or more and 75% by mass or less.
When the content of barium titanate is equal to or more than the above lower limit, the dielectric properties of the epoxy resin composition can be further improved, and the sensitivity of the capacitance type fingerprint sensor 100 can be further improved. When the content of barium titanate is not more than the above upper limit, the fluidity of the epoxy resin composition can be improved, and the moldability can be more effectively improved.
The average particle diameter _{D 50} of Barium titanate is preferably 0.01μm or more 20μm or less, more preferably 0.1μm or 15μm or less. By the average particle diameter D ₅₀ of less than the above lower limit, the fluidity of the epoxy resin composition is made excellent, it is possible to improve the formability more effectively. Further, by the average particle diameter D ₅₀ and more than the above upper limit can reliably prevent the gate clogging occurs. In addition, when the thickness D of the insulating film 105 on the substrate 101 (for example, a silicon chip) is made as thin as 50 μm or less to improve the sensitivity of the fingerprint sensor, unfilling failure of the epoxy resin composition is suppressed. to, it is preferable that the average particle size D ₅₀ of barium titanate is 10μm or less, more preferably 5μm or less.

In addition, from the viewpoint of suppressing the warpage of the fingerprint sensor while improving the sensitivity of the obtained fingerprint sensor, the inorganic filler (B) is selected from titanium oxide, alumina, tantalum pentoxide, niobium pentoxide, and barium titanate. One or more inorganic fillers and silica are preferably used in combination, and one or more inorganic fillers selected from alumina, titanium oxide and barium titanate, and silica particles are used in combination. More preferably, it is particularly preferable to use one or more inorganic fillers selected from titanium oxide and barium titanate together with silica particles.
In the present embodiment, the inorganic filler (B) contains finely divided silica having an average particle diameter of 1 μm or less from the viewpoint of improving the filling property of the epoxy resin composition and suppressing the warpage of the fingerprint sensor. As one of preferred embodiments.

(Curing agent (C))
The epoxy resin composition can include, for example, a curing agent (C). The curing agent (C) is not particularly limited as long as it cures by reacting with the epoxy resin (A). For example, the curing agent (C) has 2 to 20 carbon atoms such as ethylenediamine, trimethylenediamine, tetramethylenediamine, and hexamethylenediamine. Linear aliphatic diamine, metaphenylenediamine, paraphenylenediamine, paraxylenediamine, 4,4'-diaminodiphenylmethane, 4,4'-diaminodiphenylpropane, 4,4'-diaminodiphenylether, 4,4'-diaminodiphenyl Sulfone, 4,4'-diaminodicyclohexane, bis (4-aminophenyl) phenylmethane, 1,5-diaminonaphthalene, metaxylenediamine, paraxylenediamine, 1,1-bis (4-aminophenyl) cyclohexane, dicyano Amid such as diamide Phenolic resins such as aniline-modified resole resins and dimethyl ether resole resins; phenol novolak resins, cresol novolak resins, tert-butylphenol novolak resins, nonylphenol novolak resins, and trisphenolmethane phenol novolak resins; Phenol aralkyl resins such as skeleton-containing phenol aralkyl resins and biphenylene skeleton-containing phenol aralkyl resins; phenol resins having a condensed polycyclic structure such as a naphthalene skeleton or an anthracene skeleton; polyoxystyrenes such as polyparaoxystyrene; hexahydrophthalic anhydride (HHPA) ), Alicyclic acid anhydrides such as methyltetrahydrophthalic anhydride (MTHPA), trimellitic anhydride (TMA) , Pyromellitic anhydride (PMDA), benzophenone tetracarboxylic acid (BTDA) and other acid anhydrides including aromatic acid anhydrides, etc .; polysulfides, thioesters, polymercaptan compounds such as thioethers; isocyanate prepolymers, blocked isocyanates, etc. Isocyanate compounds; and organic acids such as carboxylic acid-containing polyester resins. These may be used alone or in combination of two or more.

  The content of the curing agent (C) in the epoxy resin composition is not particularly limited, but may be, for example, 0.5% by mass or more and 20% by mass or less when the entire epoxy resin composition is 100% by mass. Preferably, the content is 1.5% by mass or more and 20% by mass or less, further preferably 2% by mass or more and 15% by mass or less, particularly preferably 2% by mass or more and 10% by mass or less.

(Coupling agent (D))
The epoxy resin composition can include, for example, a coupling agent (D). Examples of the coupling agent (D) include known silane compounds such as epoxy silane, mercapto silane, amino silane, alkyl silane, ureido silane, and vinyl silane, titanium compounds, aluminum chelates, and aluminum / zirconium compounds. A ring agent can be used.
Examples thereof include vinyltrichlorosilane, vinyltrimethoxysilane, vinyltriethoxysilane, vinyltris (β-methoxyethoxy) silane, γ-methacryloxypropyltrimethoxysilane, and β- (3,4-epoxycyclohexyl) ethyltrimethoxy. Silane, γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropyltriethoxysilane, γ-glycidoxypropylmethyldimethoxysilane, γ-methacryloxypropylmethyldiethoxysilane, γ-methacryloxypropyltriethoxysilane , Vinyltriacetoxysilane, γ-mercaptopropyltrimethoxysilane, γ-aminopropyltriethoxysilane, γ-anilinopropyltrimethoxysilane, γ-anilinopropylmethyldimethoxysilane, -[Bis (β-hydroxyethyl)] aminopropyltriethoxysilane, N-β- (aminoethyl) -γ-aminopropyltrimethoxysilane, N-β- (aminoethyl) -γ-aminopropyltriethoxysilane, N-β- (aminoethyl) -γ-aminopropylmethyldimethoxysilane, N-phenyl-γ-aminopropyltrimethoxysilane, γ- (β-aminoethyl) aminopropyldimethoxymethylsilane, N- (trimethoxysilylpropyl) ) Ethylenediamine, N- (dimethoxymethylsilylisopropyl) ethylenediamine, methyltrimethoxysilane, dimethyldimethoxysilane, methyltriethoxysilane, N-β- (N-vinylbenzylaminoethyl) -γ-aminopropyltrimethoxysilane, γ- Chloropropyl trime Xysilane, hexamethyldisilane, vinyltrimethoxysilane, γ-mercaptopropylmethyldimethoxysilane, 3-isocyanatopropyltriethoxysilane, 3-acryloxypropyltrimethoxysilane, 3-triethoxysilyl-N- (1,3-dimethyl Silane coupling agents such as hydrolysates of -butylidene) propylamine, isopropyl triisostearoyl titanate, isopropyl tris (dioctyl pyrophosphate) titanate, isopropyl tri (N-aminoethyl-aminoethyl) titanate, tetraoctyl bis (ditriethyl) (Decyl phosphite) titanate, tetra (2,2-diallyloxymethyl-1-butyl) bis (ditridecyl) phosphite titanate, bis (dioctyl pyrophosphate) Oxyacetate titanate, bis (dioctyl pyrophosphate) ethylene titanate, isopropyl trioctanoyl titanate, isopropyl dimethacryl isostearyl titanate, isopropyl tridodecyl benzenesulfonyl titanate, isopropyl isostearyl diacryl titanate, isopropyl tri (dioctyl phosphate) titanate, isopropyl tric Titanate coupling agents such as millphenyl titanate and tetraisopropyl bis (dioctyl phosphite) titanate. These may be used alone or in combination of two or more.

  The content of the coupling agent (D) in the epoxy resin composition is not particularly limited, but may be, for example, 0.01% by mass or more and 3% by mass or less when the entire epoxy resin composition is 100% by mass. It is particularly preferred that the content be 0.1% by mass or more and 2% by mass or less. By setting the content of the coupling agent (D) to the above lower limit or more, the dispersibility of the inorganic filler (B) in the epoxy resin composition can be improved. When the content of the coupling agent (D) is equal to or less than the above upper limit, the fluidity of the epoxy resin composition can be improved, and the moldability can be improved.

(Other components (E))
The epoxy resin composition contains, in addition to the above components, a phosphorus atom-containing compound such as an organic phosphine, a tetra-substituted phosphonium compound, a phosphobetaine compound, an adduct of a phosphine compound and a quinone compound, or an adduct of a phosphonium compound and a silane compound. Compounds or amidine compounds such as 1,8-diazabicyclo (5.4.0) undecene-7 and imidazole; tertiary amines such as benzyldimethylamine; and amidinium salts which are quaternary onium salts of the above compounds, or ammonium salts A curing accelerator such as a nitrogen atom-containing compound, etc .; a coloring agent such as carbon black; a polybutadiene compound, an acrylonitrile butadiene copolymer compound, a natural wax, a synthetic wax, a higher fatty acid or a metal salt thereof, paraffin, polyethylene oxide, and the like. Type agents; can contain various additives such as antioxidants; ion scavenger, such as hydrotalcite; flame retardants such as aluminum hydroxide silicone oil, low-stress agent such as silicone rubber.

The relative permittivity (ε _r ) at 1 MHz of the cured product of the epoxy resin composition is preferably 5 or more, more preferably 7 or more, and particularly preferably 8 or more. When the relative dielectric constant (ε _r ) is equal to or greater than the lower limit, the dielectric properties of the epoxy resin composition can be further improved, and the sensitivity of the capacitance fingerprint sensor 100 can be further improved.
When the epoxy resin composition is in the form of a tablet, the cured product of the epoxy resin composition is prepared, for example, using a transfer molding machine under the conditions of a mold temperature of 175 ° C., an injection pressure of 9.8 MPa, and a curing time of 300 seconds. It is obtained by injection molding of an epoxy resin composition. This cured product has, for example, a diameter of 50 mm and a thickness of 3 mm.
When the epoxy resin composition is a powder, the cured body of the epoxy resin composition is, for example, molded 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. It is obtained by injecting and molding the above epoxy resin composition under the following conditions. This cured product has, for example, a diameter of 50 mm and a thickness of 3 mm.
The relative dielectric constant (ε _r ) of the cured product can be measured by, for example, Q-METER 4342A manufactured by YOKOGAWA-HEWLETT PACKARD.
The upper limit of the relative dielectric constant (ε _r ) is not particularly limited, but is, for example, 300 or less.

The dielectric loss tangent (tan δ) at 1 MHz of the cured product of the epoxy resin composition is preferably 0.005 or more, more preferably 0.006 or more, and further preferably 0.007 or more.
When the dielectric loss tangent (tan δ) is equal to or more than the lower limit, the dielectric properties of the epoxy resin composition can be further improved, and the sensitivity of the capacitance type fingerprint sensor 100 can be further improved.
When the epoxy resin composition is in the form of a tablet, the cured product of the epoxy resin composition is prepared, for example, using a transfer molding machine under the conditions of a mold temperature of 175 ° C., an injection pressure of 9.8 MPa, and a curing time of 300 seconds. It is obtained by injection molding of an epoxy resin composition. This cured product has, for example, a diameter of 50 mm and a thickness of 3 mm.
When the epoxy resin composition is a powder, the cured body of the epoxy resin composition is, for example, molded 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. It is obtained by injecting and molding the above epoxy resin composition under the following conditions. This cured product has, for example, a diameter of 50 mm and a thickness of 3 mm.
The dielectric loss tangent (tan δ) of the cured product can be measured by, for example, Q-METER 4342A manufactured by YOKOGAWA-HEWLETT PACKARD.
The upper limit of the dielectric loss tangent (tan δ) is not particularly limited, but is, for example, 0.07 or less.

The relative dielectric constant (ε _r ) and the dielectric loss tangent (tan δ) can be controlled by appropriately adjusting the types and mixing ratios of the components constituting the epoxy resin composition. In the present embodiment, in particular, appropriately selecting the type of the inorganic filler (B) can be 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 having a large dielectric constant is used, the more the relative dielectric constant (ε _r ) and the dielectric loss tangent (tan δ) of the cured product of the epoxy resin composition can be improved.

  The epoxy resin composition preferably has a flow length measured by spiral flow measurement of, for example, 30 cm or more and 200 cm or less, and more preferably 40 cm or more and 150 cm or less. Thereby, the moldability of the epoxy resin composition can be improved. In the present embodiment, the spiral flow of the epoxy resin composition is measured, for example, using a transfer molding machine in a mold for spiral flow measurement according to EMMI-1-66 at a mold temperature of 175 ° C. and an injection pressure of 9.8 MPa. This is performed by injecting the epoxy resin composition under the conditions of an injection time of 15 seconds and a curing time of 120 to 180 seconds, and measuring the flow length.

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

  In the present embodiment, the cured product of the epoxy resin composition preferably has a linear expansion coefficient (CTE1) of 3 ppm / ° C. or higher at a glass transition temperature or lower, and more preferably 6 ppm / ° C. or higher. The coefficient of linear expansion (CTE1) at or below the glass transition temperature is, for example, preferably 50 ppm / ° C. or less, and more preferably 30 ppm / ° C. or less. By controlling the CTE 1 in this manner, the warpage of the fingerprint sensor due to the difference in the linear expansion coefficient between the substrate 101 (for example, a silicon chip) and the insulating film 105 can be more reliably suppressed.

  In the present embodiment, the cured product of the epoxy resin composition preferably has a linear expansion coefficient (CTE2) of 10 ppm / ° C. or higher when the glass transition temperature is exceeded. Further, the coefficient of linear expansion (CTE2) at a temperature exceeding the glass transition temperature is preferably, for example, 100 ppm / ° C. or less. By controlling the CTE 2 in this manner, it is possible to more reliably suppress the warpage of the fingerprint sensor due to the difference in the linear expansion coefficient between the substrate 101 (for example, a silicon chip) and the insulating film 105, particularly in a high-temperature environment. it can.

The glass transition temperature and the linear expansion coefficients (CTE1, CTE2) of the cured product of the epoxy resin composition can be measured, for example, as follows.
First, when the epoxy resin composition is in the form of a tablet, a cured body of the epoxy resin composition is prepared, for example, using a transfer molding machine under the conditions of a mold temperature of 175 ° C., an injection pressure of 9.8 MPa, and a curing time of 300 seconds. And the above-mentioned epoxy resin composition is obtained by injection molding. This cured product has, for example, a length of 10 mm, a width of 4 mm, and a thickness of 4 mm.
When the epoxy resin composition is a powder, the cured body of the epoxy resin composition is, for example, molded 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. It is obtained by injecting and molding the above epoxy resin composition under the following conditions. This cured product has, for example, a length of 10 mm, a width of 4 mm, and a thickness of 4 mm.
Next, after the obtained cured body was post-cured at 175 ° C. for 4 hours, the measurement temperature range was 0 ° C. to 320 ° C. using a thermomechanical analyzer (TMA100, manufactured by Seiko Instruments Inc.), and the rate of temperature increase. The measurement is performed at 5 ° C./min. From this measurement result, the glass transition temperature, the coefficient of linear expansion below the glass transition temperature (CTE1), and the coefficient of linear expansion above the glass transition temperature (CTE2) are calculated.

  The above-mentioned glass transition temperature, the coefficient of linear expansion below the glass transition temperature (CTE1), and the coefficient of linear expansion above the glass transition temperature (CTE2) are determined by appropriately adjusting the types and mixing ratios of the components constituting the epoxy resin composition. Can be controlled by In the present embodiment, in particular, appropriately selecting the type of the inorganic filler (B) can be cited as a factor for controlling CTE1 and CTE2. For example, by using silica particles having a small linear expansion coefficient as the inorganic filler (B), CTE1 and CTE2 of the cured product of the epoxy resin composition can be reduced.

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

  The capacitance-type fingerprint sensor 100 according to the present embodiment is a fingerprint sensor that reads fingerprint information by, for example, a capacitance method of detecting capacitance with a finger. Here, the fingerprint sensor reads unevenness of a finger placed on the fingerprint sensor. For example, the capacitance type fingerprint sensor 100 is provided with a detection electrode 103 finer than the unevenness of the fingerprint. Then, a two-dimensional image representing the irregularities of the fingerprint is created by the capacitance accumulated between the irregularities of the fingerprint and the detection electrode 103. For example, since the detected capacitance is different between the convex part and the concave part of the fingerprint, a two-dimensional image representing the irregularities of the fingerprint can be created from the difference in the capacitance. Fingerprint information can be read from this two-dimensional image.

FIG. 1 is a sectional view schematically showing a capacitance type fingerprint sensor 100 according to the present embodiment.
The capacitance type fingerprint sensor 100 according to the present embodiment includes a substrate 101, a detection electrode 103 provided on the substrate 101, and an insulating film 105 sealing the detection electrode 103.

  In the present embodiment, the insulating film 105 is formed of a cured product of the epoxy resin composition. As the epoxy resin composition, for example, the above-mentioned components are mixed by a known means, further melt-kneaded by a kneader such as a roll, a kneader or an extruder, cooled, and then pulverized. Tablet-formed ones, or ones whose dispersity, fluidity, and the like are appropriately adjusted as necessary can be used.

  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 chip) is, for example, 100 μm or less, more preferably 75 μm or less, and further preferably 50 μm or less.

The substrate 101 is, for example, a chip-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 on the substrate 101 via an interlayer film 107. The interlayer film 107 is formed of, for example, SiO ₂ or the like.
The upper surface of the detection electrode 103 is covered with an insulating film 105. The detection electrode 103 is, for example, subjected to wire bonding.

The capacitance type fingerprint sensor 100 according to the present embodiment can be manufactured based on known information. For example, it is manufactured as follows.
First, after the interlayer film 107 is provided on the substrate 101, the detection electrode 103 is formed on the interlayer film 107. Next, the detection electrode 103 is molded by sealing with an epoxy resin composition. Examples of the molding method include a transfer molding method, a compression molding method, and a casting method. Next, the epoxy resin composition is thermally cured to form an insulating film 105. Thereby, the capacitance type fingerprint sensor 100 according to the present embodiment is obtained.

Next, effects of the present embodiment will be described.
According to the present embodiment, the insulating film 105 for sealing the detection electrode 103 is made of a cured product of the epoxy resin composition containing the epoxy resin (A) and the inorganic filler (B). Since the cured product of the epoxy resin composition has excellent dielectric properties, the sensitivity of the capacitance-type fingerprint sensor 100 can be improved.

  Next, examples of the present invention will be described.

(Preparation of epoxy resin composition)
About an Example and a reference example , the epoxy resin composition was adjusted as follows. First, the components blended according to Table 1 were mixed at room temperature using a high-speed mixer. Next, the obtained mixture was roll-kneaded (high-temperature roll surface temperature 90 ° C., low-temperature roll surface temperature 25 ° C.), cooled, and pulverized by a blender 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 Denki Kagaku Kogyo Co., Ltd., D ₅₀ = 17 μm)
Inorganic filler 2: silica (FB105, D ₅₀ = 10 μm, manufactured by Denki Kagaku Kogyo Co., Ltd.)
Inorganic filler 3: silica (manufactured by Tokuyama Corporation, REOLOSIL CP-102, D ₅₀ = 1 μm or less)
Inorganic filler 4: silica (AD-25, SO-25R, D ₅₀ = 0.5 μm)
Inorganic filler 5: titanium oxide (IV) (PF-726, manufactured by Ishihara Sangyo Co., Ltd., D ₅₀ = 1 μm, rutile type, content of titanium oxide having a particle diameter of 32 μm or more 5% by mass or less)
Inorganic filler 6: Barium titanate (Nippon Chemical Industrial Co., Paruseramu _{BT-UP2, D 50 = 2μm} , less content of 5 wt% of the barium titanate particle size of more than 32μm acid)
Inorganic filler 7: Alumina (manufactured by Micron, AX3-15R, content of alumina having a particle diameter of 15 μm or more, 5% by mass or less, D ₅₀ = 4 μm)
(C) Curing agent Curing agent 1: Trisphenolmethane type phenol novolak resin (MEH-7500, manufactured by Meiwa Kasei Co., Ltd.)
Curing agent 2: Trisphenolmethane type phenol novolak resin (HE910-20, manufactured by Air Water)
(D) Coupling agent Coupling agent 1: N-phenyl-γ-aminopropyltrimethoxysilane (CF4083, manufactured by Dow Corning Toray)
(E) Other component curing accelerator 1: a curing accelerator represented by the following formula (4)

[Synthesis method of curing accelerator 1]
A separable flask equipped with a stirrer was charged with 37.5 g (0.15 mol) of 4,4'-bisphenol S and 100 ml of methanol, and dissolved by stirring at room temperature, and 4.0 g of sodium hydroxide was previously added to 50 ml of methanol while stirring. (0.1 mol) was added. Next, 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, and after adding 300 ml of methanol, the solution in the flask was dropped into a large amount of water while stirring to obtain a white precipitate. The precipitate was filtered and dried to obtain a hardening accelerator 1 as white crystals.

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

[Synthesis method of curing 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, and then 231.5 g of a 28% sodium methoxide-methanol solution was added dropwise with stirring at room temperature. Further, a solution prepared by dissolving 503.0 g of tetraphenylphosphonium bromide prepared in advance in 600 g of methanol was added dropwise thereto with stirring at room temperature to precipitate crystals. The precipitated crystals were filtered, washed with water, and dried under vacuum to obtain a hardening accelerator 2 of pink white crystals.

Low stress agent 1: Acrylonitrile butadiene rubber (manufactured by Ube Industries, carboxyl-terminated butadiene acrylic rubber, CTBN1008SP)
Low stress agent 2: Silicone oil Colorant: Carbon black Release agent: Carnauba wax Ion scavenger: Hydrotalcite

(Measurement of relative permittivity and dielectric loss tangent)
About the Example and the reference example , 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 Kotaki Seiki Co., Ltd.), the epoxy resin composition was molded into a mold under the conditions of a mold temperature of 175 ° C., an injection pressure of 9.8 MPa, and a curing time of 300 seconds. By injection molding to obtain a cured product of the epoxy resin composition. This cured product had a diameter of 50 mm and a thickness of 3 mm.
Next, the obtained cured product was measured for relative dielectric constant and dielectric loss tangent at 1 MHz and room temperature (25 ° C.) using Q-METER 4342A manufactured by YOKOGAWA-HEWLETT PACKARD. Table 1 shows the results.

(Measurement of spiral flow)
For the examples and the reference examples , the spiral flow of the epoxy resin composition was measured as follows. Using a low-pressure transfer molding machine (“KTS-15” manufactured by Kotaki Seiki Co., Ltd.), mold temperature 175 ° C., injection pressure 9.8 MPa, injection into a die for spiral flow measurement according to EMMI-1-66. The epoxy resin composition was injected under the conditions of a time of 15 seconds and a curing time of 180 seconds, and the flow length was measured. The unit in Table 1 is cm. Table 1 shows the results.

(Glass transition temperature, linear expansion coefficient)
About each Example and the reference example , the glass transition temperature (Tg) and the coefficient of linear expansion (CTE1, CTE2) of the cured body of the epoxy resin composition were measured as follows. Using a low-pressure transfer molding machine (“KTS-30” manufactured by Kotaki Seiki Co., Ltd.), the epoxy resin composition was molded into a mold under the conditions of a mold temperature of 175 ° C., an injection pressure of 9.8 MPa, and a curing time of 300 seconds. By injection molding to obtain a cured product of the epoxy resin composition. This cured product had a length of 10 mm, a width of 4 mm, and a thickness of 4 mm.
Next, after the obtained cured body was post-cured at 175 ° C. for 4 hours, the measurement temperature range was 0 ° C. to 320 ° C. using a thermomechanical analyzer (TMA100, manufactured by Seiko Instruments Inc.), and the rate of temperature increase. The measurement was performed under the condition of 5 ° C./min. From the measurement results, the glass transition temperature (Tg), the coefficient of linear expansion below the glass transition temperature (CTE1), and the coefficient of linear expansion above the glass transition temperature (CTE2) were calculated. Table 1 shows the results.

(Sensitivity measurement of capacitance type fingerprint sensor)
For each of the examples and reference examples, the capacitance type fingerprint sensor shown in FIG. 1 was produced using the obtained epoxy resin composition. Next, a two-dimensional image showing the unevenness of the fingerprint was created using the obtained capacitance fingerprint sensor.

Capacitive fingerprint sensor obtained Ri by example, both the two-dimensional image of the fingerprint is clearly displayed, the sensitivity showed good results. Among these, Examples 2 to 6 and 8 to 9, which have particularly excellent dielectric properties, provided clearer two-dimensional images of fingerprints as compared with Reference Example 1, and exhibited excellent sensitivity. In Examples 2-3, 6 Contact and 9 showed excellent results in the formability test.
Further, the electrostatic capacitance type fingerprint sensor more obtained in the examples, any warping was suppressed. Incidentally, CTE1 of the cured product of more obtained epoxy resin composition in the examples, were each in the range of 3 ppm / ° C. or higher 50 ppm / ° C. or less. Further, CTE2 of the cured product of more obtained epoxy resin composition in the examples, were each in the range of 10 ppm / ° C. or higher 100 ppm / ° C. or less.
Further, since reducing the thickness D of the insulating film 105 leads to the sensitivity of the fingerprint sensor, the use of the inorganic filler (B) obtained by cutting coarse particles suppresses unfilling during molding. It is preferable because it is possible. The epoxy resin compositions of Examples 8 to 9 can be molded without filling the fingerprint sensor even when the thickness D of the insulating film 105 is 50 μm, and have better moldability than the epoxy resin compositions of Examples 2 to 6 and Reference Example 1. It was excellent. Also, the epoxy resin compositions of Examples 8 to 9 did not warp the fingerprint sensor even when the thickness D of the insulating film 105 was 50 μm. That is, the epoxy resin compositions of Examples 8 to 9 clearly displayed a two-dimensional image of a fingerprint, and exhibited excellent moldability while exhibiting good sensitivity.

This application claims priority based on Japanese Patent Application No. 2014-062446 filed on March 25, 2014, and incorporates the entire disclosure thereof.
Hereinafter, examples of the reference embodiment will be additionally described.
1. Board and
A detection electrode provided on the substrate,
An insulating film for sealing the detection electrode,
An epoxy resin composition used for forming the insulating film constituting a capacitance type fingerprint sensor comprising:
Epoxy resin (A),
An inorganic filler (B),
An epoxy resin composition containing:
2. 1. In the epoxy resin composition according to the,
An epoxy resin composition, wherein the cured product of the epoxy resin composition has a relative dielectric constant (ε _r ) at 1 MHz of 5 or more.
3. 2. In the sealing resin composition according to the,
An epoxy resin composition wherein the cured product of the epoxy resin composition has a relative dielectric constant (ε _r ) at 1 MHz of 8 or more.
4. 1. To 3. The epoxy resin composition according to any of the above,
An epoxy resin composition wherein the cured product of the epoxy resin composition has a dielectric loss tangent (tan δ) at 1 MHz of 0.005 or more.
5. 1. To 4. The epoxy resin composition according to any of the above,
An epoxy resin composition in which the inorganic filler (B) contains one or more selected from alumina, titanium oxide, and barium titanate.
6. 5. In the epoxy resin composition described,
The inorganic filler (B) contains the titanium oxide,
An epoxy resin composition wherein the titanium oxide is a rutile type.
7. 5. Or 6. In the epoxy resin composition according to the,
An epoxy resin composition wherein the inorganic filler (B) further contains silica particles.
8. 1. To 7. The epoxy resin composition according to any of the above,
An epoxy resin composition having a flow length of 30 cm or more and 200 cm or less as measured by spiral flow measurement at a mold temperature of 175 ° C, an injection pressure of 9.8 MPa, and an injection time of 15 seconds.
9. 1. To 8. The epoxy resin composition according to any of the above,
An epoxy resin composition wherein the cured product of the epoxy resin composition has a glass transition temperature of 100 ° C. or higher.
10. 1. To 9. The epoxy resin composition according to any of the above,
An epoxy resin composition wherein the cured product of the epoxy resin composition has a linear expansion coefficient (CTE1) at a glass transition temperature or lower of 3 ppm / ° C. or more and 50 ppm / ° C. or less.
11. 1. To 10. The epoxy resin composition according to any of the above,
An epoxy resin composition in which a cured product of the epoxy resin composition has a linear expansion coefficient (CTE2) at a temperature exceeding the glass transition temperature of 10 ppm / ° C or more and 100 ppm / ° C or less.
12. Board and
A detection electrode provided on the substrate,
Sealing the detection electrode; To 11. An insulating film formed of a cured product of the epoxy resin composition according to any of the above,
Capacitive fingerprint sensor with.

Claims (9)

Board and
A detection electrode provided on the substrate,
An insulating film for sealing the detection electrode,
An epoxy resin composition used for forming the insulating film constituting a capacitance type fingerprint sensor comprising:
Epoxy resin (A),
An inorganic filler (B),
A curing agent (C),
Including
The amount of the inorganic filler (B) is 50% by mass or more and 97% by mass or less with respect to the entire epoxy resin composition;
Wherein the inorganic filler (B) comprises at least one kind selected from titanium oxide and barium titanate, and silica particles,
Epoxy resin composition. The sealing resin composition according to claim 1,
An epoxy resin composition wherein the cured product of the epoxy resin composition has a relative dielectric constant (ε _r ) at 1 MHz of 8 or more. The epoxy resin composition according to claim 1 or 2,
An epoxy resin composition wherein the cured product of the epoxy resin composition has a dielectric loss tangent (tan δ) at 1 MHz of 0.006 or more. The epoxy resin composition according to claim 1,
The inorganic filler (B) contains the titanium oxide,
An epoxy resin composition wherein the titanium oxide is a rutile type. The epoxy resin composition according to any one of claims 1 to 4,
An epoxy resin composition having a flow length of 30 cm or more and 200 cm or less as measured by spiral flow measurement at a mold temperature of 175 ° C, an injection pressure of 9.8 MPa, and an injection time of 15 seconds. The epoxy resin composition according to any one of claims 1 to 5,
An epoxy resin composition wherein the cured product of the epoxy resin composition has a glass transition temperature of 100 ° C. or higher. The epoxy resin composition according to any one of claims 1 to 6,
An epoxy resin composition wherein the cured product of the epoxy resin composition has a linear expansion coefficient (CTE1) at a glass transition temperature or lower of 3 ppm / ° C. or more and 50 ppm / ° C. or less. The epoxy resin composition according to any one of claims 1 to 7,
An epoxy resin composition, wherein a cured product of the epoxy resin composition has a linear expansion coefficient (CTE2) at a temperature exceeding the glass transition temperature of 10 ppm / ° C or more and 100 ppm / ° C or less. Board and
A detection electrode provided on the substrate,
An insulating film formed by curing the epoxy resin composition according to any one of claims 1 to 8, which seals the detection electrode, and
Capacitive fingerprint sensor with.

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