WO2012060342A1

WO2012060342A1 - Method for producing wafer lens

Info

Publication number: WO2012060342A1
Application number: PCT/JP2011/075111
Authority: WO
Inventors: 原明子
Original assignee: コニカミノルタオプト株式会社
Priority date: 2010-11-02
Filing date: 2011-10-31
Publication date: 2012-05-10

Abstract

The objective of the present invention is to provide a method that is for producing a wafer lens and that can precisely form a lens unit from a resin transfer mold, even if a photocurable resin is used for forming the lens unit or the resin transfer mold that is a sub-sub-master mold or the like. If the photoinitiator of the photocurable resin of a first and second resin layer (102, 103) has a low sensitivity, the light transmittance of the thickness of the sub-sub-master mold (50) is made relatively higher, and if the photoinitiator of the photocurable resin of the first and second resin layer (102, 103) has a high sensitivity, the light transmittance of the thickness of the sub-sub-master mold (50) is made relatively lower, and so the appropriate amount of light is transmitted for curing the photocurable resin of the first and second resin layers (102, 103). As a result, a first and second optical surface (11d, 12d) can be precisely transferred. Also, since more light than needed is not radiated, it is possible to prevent yellowing of the resin and a deleterious effect on durability in environmental tests and the like.

Description

Wafer lens manufacturing method

The present invention relates to a method for manufacturing a wafer lens, and more particularly to a method for manufacturing a wafer lens for use in an imaging lens or the like.

As a method for producing a wafer lens, there is a method in which a curable resin composition is injected between a glass flat plate and a mold to mold a lens portion (for example, see Patent Document 1). At this time, a resin-made sub master mold is formed from the master mold, and the lens portion is molded using the sub master mold. Alternatively, a resin sub-sub master mold is formed using the sub master mold as a mold, and the lens portion is molded from the sub-sub master mold.

Here, in order to form the lens portion, it is necessary to configure a resin transfer mold such as a sub-submaster mold with a resin that transmits light in a wavelength region necessary for curing the resin composition for forming the lens section. . However, depending on the optical characteristics of the resin transfer mold, the resin transfer mold may absorb light necessary for curing the lens portion, and the light intensity may vary depending on the thickness of the resin transfer mold. . That is, for example, when a convex lens part is molded using a sub-submaster mold, the optical part corresponding to the thin part is ahead of the flange part corresponding to the thick part of the sub-submaster mold in the lens part. Curing starts. Therefore, there is a possibility that stress is generated between the optical part and the flange part due to curing shrinkage of the preceding optical part, and the optical surface shape is distorted. This phenomenon can also occur when, for example, a concave lens part is molded using a sub-submaster mold, that is, the optical part corresponds to the thick part of the sub-submaster mold and the flange part corresponds to the thin part of the sub-submaster mold. It can happen. In this case, stress is generated between the optical part and the flange part due to curing shrinkage of the preceding flange part, and the optical surface shape may be distorted. In order to prevent such problems from occurring, if a resin transfer mold made of a resin that easily transmits light in the wavelength region necessary for curing the resin composition for forming the lens portion is used, a short wavelength light is applied to the lens portion. As a result of irradiating more than necessary, there is a possibility that the thin part of the resin forming the lens part may turn yellow, or the durability may be adversely affected in an environmental test or the like.

JP 2009-226638 A

The present invention provides a method for producing a wafer lens that can accurately mold a lens portion from a resin transfer mold even if a photo-curable resin is used to form a resin transfer mold such as a sub-submaster mold or a lens portion. The purpose is to do.

In order to solve the above-mentioned problems, a first wafer lens manufacturing method according to the present invention includes a substrate and a resin layer having a molding surface formed on one substrate surface of the substrate and including an optical surface. The method includes the step of forming a resin layer having a molding surface using a resin transfer mold having an optical transfer surface having a shape obtained by inverting the optical surface, and the resin layer is formed of a first photocurable resin. The first photocurable resin is obtained by curing the first photocurable resin composition containing the first photopolymerization initiator, and the absorbance of the first photopolymerization initiator is changed to the first photocurable resin. When the absorbance of the first photopolymerization initiator is less than 0.25 at a wavelength of 340 nm when the photopolymerization initiator is dissolved in acetonitrile at a concentration of 0.01% by mass, the resin transfer Light transmission through the thickest part of the resin transfer mold as a mold When the light transmittance of the first photopolymerization initiator is 0.25 or more and less than 1.0, the thickness light transmittance is 7% as a resin transfer mold. When the first photopolymerization curing agent has an absorbance of 1.0 or more, a resin transfer mold having a thickness light transmittance of 1% or more and less than 7% is used.

According to the first wafer lens manufacturing method, when the first photopolymerization initiator of the first photocurable resin forming the resin layer has low sensitivity, specifically, the absorbance is less than 0.25, molding is performed. The thick light transmittance of the thickest part of the resin transfer mold for transferring the surface is made relatively high at 60% or more. Further, when the first photopolymerization initiator of the first photocurable resin has a medium sensitivity, specifically, when the absorbance is 0.25 or more and less than 1.0, the resin-transfer-type thick light transmittance is 7 % Or more and less than 60%. Further, when the first photopolymerization initiator of the first photocurable resin has high sensitivity, specifically, 1.0 or more, the resin light transfer type wall thickness light transmittance is compared with 1% or more and less than 7%. Lower. Thereby, according to the sensitivity of a 1st photoinitiator, the optimal quantity of light can be permeate | transmitted in order to harden 1st photocurable resin. As a result, light efficiently reaches the first photocurable resin, and the optical surface can be transferred with high accuracy. In addition, since the first photocurable resin is not irradiated with light more than necessary, adverse effects on durability such as yellowing of the resin and environmental tests can be prevented.

In order to solve the above-mentioned problems, a second wafer lens manufacturing method according to the present invention includes a substrate and a resin layer having a molding surface formed on one substrate surface of the substrate and having a molding surface including an optical surface. The method includes the step of forming a resin layer having a molding surface using a resin transfer mold having an optical transfer surface having a shape obtained by inverting the optical surface, and the resin layer is formed of a first photocurable resin. The resin transfer mold is formed of the second photocurable resin, and the first photocurable resin is obtained by curing the first photocurable resin composition containing the first photopolymerization initiator. Yes, when the absorbance A of the first photopolymerization initiator is represented by a value measured with the first photopolymerization initiator dissolved in acetonitrile at a concentration of 0.01% by mass, at a wavelength of 340 nm, the resin transfer mold The light transmittance T ( ) Is used to satisfy the following conditional expression (1) as a resin transfer mold.
T = ± 30 + 100 × exp (−2.3026A) (1)

According to the second method for producing a wafer lens, the resin layer of the resin transfer mold for transferring the molding surface satisfies the conditional expression (1), so that the resin layer can be cured with respect to the photocurable resin. Effective light can be delivered more efficiently. Thereby, an optical surface can be accurately transferred. In addition, since the first photocurable resin is not irradiated with light more than necessary, adverse effects on durability such as yellowing of the resin and environmental tests can be prevented.

In order to solve the above-mentioned problems, a third wafer lens manufacturing method according to the present invention includes a substrate and a resin layer having a molding surface molded on one substrate surface of the substrate and including an optical surface. The method includes the step of forming a resin layer having a molding surface using a resin transfer mold having an optical transfer surface having a shape obtained by inverting the optical surface, and the resin layer is formed of a first photocurable resin. The resin transfer mold is formed of the second photocurable resin, and the first photocurable resin is obtained by curing the first photocurable resin composition containing the first photopolymerization initiator. Yes, at the longest wavelength at which the absorbance of the first photopolymerization initiator measured in a state where the first photopolymerization initiator is dissolved in acetonitrile at a concentration of 0.01% by mass is 0.3 or more, the resin transfer mold The light transmittance of the thickest part is 30%. Those of 10% is used as the resin transfer mold.

According to the third wafer lens manufacturing method, the thickness light transmittance of the resin transfer mold for transferring the molding surface is the longest wavelength at which the absorbance of the first photopolymerization initiator is 0.3 or more. By making it into the range, light effective for curing can be more efficiently delivered to the photocurable resin of the resin layer. Thereby, an optical surface can be accurately transferred. In addition, since the first photocurable resin is not irradiated with light more than necessary, adverse effects on durability such as yellowing of the resin and environmental tests can be prevented.

In a specific aspect or aspect of the present invention, in the first to third methods for manufacturing a wafer lens, the resin portion constituting the optical transfer surface of the resin transfer mold includes a second photopolymerization initiator. It is formed with the 2nd photocurable resin which hardened 2 photocurable resin compositions. In this case, the transfer surface can be accurately formed by configuring the resin transfer mold with a photocurable resin.

In another aspect of the present invention, the first photocurable resin is an acrylic resin, an allyl ester resin, a vinyl resin, or an epoxy resin.

In still another aspect of the present invention, the first photocurable resin is an ultraviolet curable resin.

In yet another aspect of the present invention, the resin transfer mold is a sub-sub-master mold formed by transferring twice from a master mold having a transfer surface corresponding to the molding surface. In this case, in order to transfer the convex optical surface, a master mold having a concave optical transfer surface may be manufactured, and the master mold can be easily manufactured.

In yet another aspect of the present invention, the resin transfer mold is a sub-master mold formed by a single transfer from a master mold having a transfer surface corresponding to the molding surface. In this case, in order to transfer the concave optical surface, a master mold having a concave optical transfer surface may be manufactured, and the master mold can be easily manufactured.

In yet another aspect of the present invention, the substrate is made of glass. In this case, the strength of the substrate can be maintained even when the substrate is relatively thin.

In still another aspect of the present invention, the resin transfer mold includes a light-transmitting substrate and a resin portion having a mold surface formed on one substrate surface of the substrate and including a plurality of optical transfer surfaces. In this case, the resin transfer mold has a two-layer structure of the substrate and the resin portion, and the resin transfer mold can be made more stable in strength.

In still another aspect of the present invention, the first photocurable resin and the second photocurable resin are cured at different wavelengths. In this case, when the resin layer is cured, absorption of the curing wavelength by the resin transfer mold can be suppressed.

In still another aspect of the present invention, the photocurable resin composition for obtaining the first photocurable resin has a longer wavelength side than the photocurable resin composition for obtaining the second photocurable resin. Easy to cure. In this case, by setting the curing wavelength of the photocurable resin forming the resin layer to the long wavelength side, the conditions for the thickness light transmittance of the resin transfer mold are changed, so that the photocurable resin of the resin layer is changed. Thus, light that is effective for curing can be delivered more efficiently.

(A) is a plan view of the wafer lens, (B) is a cross-sectional view taken along the line AA of the wafer lens shown in (A), and (C) is a perspective view of the wafer lens shown in (A). is there. (A) to (E) are diagrams for explaining the absorbance, and (F) is a diagram for explaining the light transmittance. It is sectional drawing of the imaging lens cut out by laminating | stacking the wafer lens shown in FIG. (A) is a perspective view explaining the master type | mold used for manufacture of the wafer lens of 1st Embodiment, (B) is a perspective view of a submaster type | mold, (C) is a subsubmaster type | mold. FIG. It is a figure for demonstrating the relationship between a light absorbency and thickness light transmittance. (A) to (F) are diagrams for explaining a manufacturing process of a wafer lens.

[First Embodiment]
The wafer lens according to the first embodiment of the present invention will be described with reference to the structural drawing of the wafer lens.
As shown in FIGS. 1A to 1C, the wafer lens 100 has a disk shape and includes a substrate 101, a first resin layer 102, and a second resin layer 103.

The substrate 101 of the wafer lens 100 is a circular flat plate and is made of glass. The outer diameter of the substrate 101 is substantially the same as the outer diameter of the first and second resin layers 102 and 103. The thickness of the substrate 101 is basically determined by optical specifications, but is such a thickness that the wafer lens 100 is not damaged when the wafer lens 100 is released.

The first resin layer 102 is made of resin, and is formed on one surface 101 a of the substrate 101. The first resin layer 102 has a circular outer shape in plan view. Specifically, in the first resin layer 102, a large number of first lens elements 11 each having the first lens body 11a and the first flange portion 11b as a set are two-dimensionally arranged in the XY plane. These first lens elements 11 are integrally formed through a flat connecting portion 11c. The combined surface of each first lens element 11 and connecting portion 11c is a first molding surface 102a that is collectively molded by transfer. The first lens body 11a is, for example, a convex aspherical lens part, and has a first optical surface 11d. The surrounding first flange portion 11b has a flat first flange surface 11g extending around the first optical surface 11d, and the outer periphery of the first flange portion 11b is also a connecting portion 11c. The first flange surface 11g is disposed in parallel to the XY plane perpendicular to the optical axis OA.

The first resin layer 102 is formed of a photocurable resin (first photocurable resin). In the photocurable resin composition (first photocurable resin composition) for obtaining the first photocurable resin, a photopolymerization initiator (first photopolymerization initiator) for initiating polymerization of the photocurable resin composition is used. Photopolymerization initiator). As the photocurable resin, an acrylic resin, an allyl ester resin, an epoxy resin, a vinyl resin, or the like can be used. When an acrylic resin, an allyl ester resin, or a vinyl resin is used, for example, a radical photopolymerization initiator is included in the resin composition, and the resin composition can be cured by radical polymerization of the photopolymerization initiator. In the case of using an epoxy resin, for example, a cationic photopolymerization initiator may be included in the resin composition, and the resin composition may be reacted and cured by cationic polymerization of the photopolymerization initiator.

The second resin layer 103 is made of resin, like the first resin layer 102, and is formed on the other surface 101b of the substrate 101. The second resin layer 103 has a circular outer shape in plan view. Specifically, in the second resin layer 103, a large number of second lens elements 12 each including the second lens body 12a and the second flange portion 12b are arranged two-dimensionally in the XY plane. These second lens elements 12 are integrally molded through a flat connecting portion 12c. The combined surface of each second lens element 12 and connecting portion 12c is a second molding surface 103a that is collectively molded by transfer. The second lens body 12a is, for example, a concave aspherical lens part, and has a second optical surface 12d. The surrounding second flange portion 12b has a flat second flange surface 12g extending around the second optical surface 12d, and the outer periphery of the second flange portion 12b is also a connecting portion 12c. The second flange surface 12g is disposed in parallel to the XY plane perpendicular to the optical axis OA.

The photocurable resin used for the second resin layer 103 is the same as the photocurable resin of the first resin layer 102. However, both the resin layers 102 and 103 do not need to be formed of the same photocurable resin, and can be formed of different photocurable resins.

In the wafer lens 100, a diaphragm may be provided between the substrate 101 and the first or

second resin layer

102, 103. Further, a resin layer may be provided only on one surface 101a or the other surface 101b of the substrate 101.

The following photo-curable resin will be described in detail photocurable resin used as the first and second resin layers 102 and 103. The photocurable resin is obtained by irradiating and curing a photocurable resin composition containing at least a substrate such as monomers and a photopolymerization initiator. The resin composition before curing may be referred to as a photocurable resin. This photocurable resin can also be used for a submaster type and a subsubmaster type described later.

(1) Acrylic resin There is no restriction | limiting in particular in the (meth) acrylate used for the polymerization reaction of an acrylic resin, The following (meth) acrylate manufactured by the general manufacturing method can be used. Ester (meth) acrylate, urethane (meth) acrylate, epoxy (meth) acrylate, ether (meth) acrylate, alkyl (meth) acrylate, alkylene (meth) acrylate, (meth) acrylate having an aromatic ring, polyfunctional (meth) Examples include acrylate and (meth) acrylate having an alicyclic structure. One or more of these can be used.

Particularly, (meth) acrylate having an alicyclic structure is preferable, and an alicyclic structure containing an oxygen atom or a nitrogen atom may be used. For example, cyclohexyl (meth) acrylate, cyclopentyl (meth) acrylate, cycloheptyl (meth) acrylate, bicycloheptyl (meth) acrylate, tricyclodecyl (meth) acrylate, tricyclodecane dimethanol (meth) acrylate, isoboronyl (meth) ) Acrylate, di (meth) acrylate of hydrogenated bisphenols, and the like. In particular, it preferably has an adamantane skeleton. For example, 2-alkyl-2-adamantyl (meth) acrylate (see Japanese Patent Laid-Open No. 2002-193883), adamantyl di (meth) acrylate (Japanese Patent Laid-Open No. 57-5000785), diallyl adamantyl dicarboxylate (Japanese Patent Laid-Open No. 60-100537) ), Perfluoroadamantyl acrylate (JP 2004-123687), 2-methyl-2-adamantyl methacrylate (manufactured by Shin-Nakamura Chemical), 1,3-adamantanediol diacrylate, 1,3,5-adamantanetriol triacrylate An unsaturated carboxylic acid adamantyl ester (Japanese Patent Laid-Open No. 2000-119220), 3,3′-dialkoxycarbonyl-1,1 ′ biadamantane (see Japanese Patent Laid-Open No. 2001-253835), 1,1′-biadamantane compound ( US Pat. No. 334 880), tetraadamantane (see JP 2006-169177), 2-alkyl-2-hydroxyadamantane, 2-alkyleneadamantane, 1,3-adamantane dicarboxylate di-tert-butyl and the like Curable resins having an adamantane skeleton (see JP-A-2001-322950), bis (hydroxyphenyl) adamantanes and bis (glycidyloxyphenyl) adamantane (JP-A-11-35522, JP-A-10-130371) For example).

It is also possible to contain other reactive monomers. In the case of (meth) acrylate, for example, methyl acrylate, methyl methacrylate, n-butyl acrylate, n-butyl methacrylate, 2-ethylhexyl acrylate, 2-ethylhexyl methacrylate, isobutyl acrylate, isobutyl methacrylate, tert-butyl acrylate Tert-butyl methacrylate, phenyl acrylate, phenyl methacrylate, benzyl acrylate, benzyl methacrylate, cyclohexyl acrylate, cyclohexyl methacrylate and the like.

Examples of the polyfunctional (meth) acrylate include trimethylolpropane tri (meth) acrylate, pentaerythritol tetra (meth) acrylate, pentaerythritol tri (meth) acrylate, dipentaerythritol hexa (meth) acrylate, dipentaerythritol penta (meth) ) Acrylate, dipentaerythritol tetra (meth) acrylate, dipentaerythritol tri (meth) acrylate, tripentaerythritol octa (meth) acrylate, tripentaerythritol septa (meth) acrylate, tripentaerythritol hexa (meth) acrylate, tripenta Erythritol penta (meth) acrylate, tripentaerythritol tetra (meth) acrylate, tripentaerythritol Tri (meth) acrylate.

(2) Allyl ester resin An allyl ester resin is a resin having an allyl group and cured by radical polymerization. Examples thereof include the following, but are not particularly limited to the following.

Bromine-containing (meth) allyl ester resin containing no aromatic ring (see JP-A-2003-66201), allyl (meth) acrylate resin (see JP-A-5-286896), allyl ester resin (JP-A-5-286896). For example, Japanese Patent Laid-Open No. 2003-66201).

(3) Epoxy resin The epoxy resin is not particularly limited as long as it has an epoxy group and is polymerized and cured by light or light and heat, and an acid anhydride, a cation generator or the like is used as a curing initiator. Can do. Epoxy resins are preferred in that they can be made into lenses with excellent molding accuracy because of their low cure shrinkage.

Examples of the epoxy resin include novolak phenol type epoxy resin, biphenyl type epoxy resin, and dicyclopentadiene type epoxy resin. Examples include bisphenol F diglycidyl ether, bisphenol A diglycidyl ether, 2,2′-bis (4-glycidyloxycyclohexyl) propane, 3,4-epoxycyclohexylmethyl-3,4-epoxycyclohexanecarboxylate, vinyl Cyclohexene dioxide, 2- (3,4-epoxycyclohexyl) -5,5-spiro- (3,4-epoxycyclohexane) -1,3-dioxane, bis (3,4-epoxycyclohexyl) adipate, 1,2 -A polymer obtained by polymerizing bisglycidyl ester of cyclopropanedicarboxylic acid.

(4) Vinyl-based resin The vinyl-based resin is not particularly limited as long as it is a material that forms a transparent resin by being cured, and a vinyl-based resin manufactured by a general manufacturing method can be used.

Any vinyl-based resin may be used as long as the vinyl group (CH ₂ ═CH—) contributes to the crosslinking reaction.

The monomer of the polyvinyl resin is represented by the general formula CH ₂ ═CH—R. Examples of the polyvinyl resin include polyvinyl chloride, polystyrene and the like, and an aromatic vinyl resin containing an aromatic in R is particularly preferable. In particular, a divinyl resin having two or more vinyl groups in one molecule is more preferable. These vinyl resins can be used alone or in combination of two or more by using two or more monomers.

The following photoinitiators, details of the photopolymerization initiator is described for use in the photocurable resin composition for forming the first and second resin layers 102 and 103.

The photopolymerization initiator is basically selected in combination with a photocurable resin. Furthermore, in selecting the photopolymerization initiator, consideration is given so as not to lower the transmittance of the wafer lens 100 in the use wavelength region, and consideration is given so that the absorbance to the curing light becomes appropriate. More specifically, a photopolymerization initiator that is activated by irradiation with ultraviolet rays (UV) is used. As the photopolymerization initiator, a photopolymerization initiator that is sensitive to the wavelength of UV light irradiated from a light source and generates active species such as radicals by irradiation with UV light having the wavelength is used. For example, a photopolymerization initiator having sensitivity at least in the wavelength range of 250 nm to 340 nm can be used. Specific examples of radical photopolymerization initiators include α-hydroxyalkylphenone (manufactured by Ciba Japan, DAROCUR1173, IRGACURE184, etc.). The addition amount of the photopolymerization initiator is 0.001 to 5% by mass, preferably 0.01 to 3% by mass, and more preferably 0.05 to 1% by mass with respect to the photocurable resin. In addition, when using an epoxy-type resin, the photoinitiator which generate | occur | produces a cation is used as a photoinitiator which has the same optical characteristic as the above, for example. Examples of the cationic photopolymerization initiator include iodonium-based cationic polymerization initiators (manufactured by Ciba Japan, IRGACURE250, etc.).

2A is a diagram showing the absorbance of DAROCUR 1173, FIG. 2B is a diagram showing the absorbance of IRGACURE184, and FIG. 2C is a diagram showing the absorbance characteristics of IRUGACURE250. The absorbance of the photopolymerization initiator is measured in a state where it is dissolved in a 0.01% by mass acetonitrile solution.

Imaging Lens and Compound Lens The imaging lens 200 shown in FIG. 3 includes a first compound lens 10 and a second compound lens 20.
The first compound lens 10 includes the first lens element 11, the second lens element 12, and the flat plate portion 13 sandwiched between them. The flat plate portion 13 is a portion obtained by cutting out the substrate 101. In the first compound lens 10, the shapes of the first and

second lens elements

11, 12 may be the same or different.

Similarly to the first compound lens 10, the second compound lens 20 includes a first lens element 21, a second lens element 22, and a flat plate portion 23 sandwiched therebetween.

In order to produce the imaging lens 200 shown in FIG. 3, two wafer lenses 100 are used. The two wafer lenses 100 are fixed with an adhesive or the like in a stacked state. The two stacked wafer lenses 100 are finally cut out by dicing to form the imaging lens 200 shown in FIG. The imaging lens 200 is a member having a rectangular outline when viewed from the optical axis OA direction. The imaging lens 200 is housed in, for example, a separately prepared holder, and is bonded to the imaging circuit board as an imaging lens.

Molding Mold An example of a molding mold for manufacturing the wafer lens 100 shown in FIG. 1 (A) will be described below with reference to FIGS. 4 (A) to 4 (C).

For molding the wafer lens 100, a master mold 30, a sub master mold 40, and a sub sub master mold 50 are used as molds.

As shown in FIG. 4A, the master mold 30 has a first transfer surface 31 for forming a second transfer surface 43 of a sub-master mold 40 to be described later on its end surface 30a. The first transfer surface 31 corresponds to the first molding surface 102a of the first resin layer 102 of the wafer lens 100 finally obtained. The first transfer surface 31 includes a first optical transfer surface 31a for forming the first optical surface 11d of the first molding surface 102a and a first flange transfer surface 31b for forming the first flange surface 11g. Including. A plurality of first optical transfer surfaces 31a are arranged in an array and are formed in a substantially hemispherical concave shape.

The master mold 30 is generally formed of a metal material. Examples of the metal material include iron-based materials, iron-based alloys, and non-ferrous alloys. Examples of iron-based materials include hot dies, cold dies, plastic dies, high-speed tool steel, general structural rolled steel, carbon steel for mechanical structures, chrome / molybdenum steel, and stainless steel. Among these, examples of the plastic mold include pre-hardened steel, quenched and tempered steel, and aging treated steel. Examples of the pre-hardened steel include SC, SCM, and SUS. An example of the SC system is PXZ. Examples of the SCM system include HPM2, HPM7, PX5, and IMPAX. Examples of the SUS system include HPM38, HPM77, S-STAR, G-STAR, STAVAX, RAMAX-S, and PSL. Examples of the iron-based alloy include alloys disclosed in JP-A-2005-113161 and JP-A-2005-206913. As the non-ferrous alloys, copper alloys, aluminum alloys, and zinc alloys are well known, and examples include alloys disclosed in JP-A-10-219373 and JP-A-2000-176970. The master mold 30 may be made of metal glass or amorphous alloy. Examples of the metallic glass include PdCuSi and PdCuSiNi. Metallic glass has high machinability in diamond cutting and less tool wear. Examples of the amorphous alloy include electroless or electrolytic nickel phosphorous plating, and have good machinability in diamond cutting. These highly machinable materials may constitute the entire master mold 30 or may cover only the surface of the optical transfer surface, in particular, by a method such as plating or sputtering.

As shown in FIG. 4B, the sub-master mold 40 has a sub-master molding part 41 that is a resin part and a light-transmissive sub-master substrate 42. The sub master molding part 41 and the sub master substrate 42 have a laminated structure. The sub master molding part 41 has a second transfer surface 43 that forms a third transfer surface 53 of a sub sub master mold 50 to be described later on its end surface 41a. The second transfer surface 43 corresponds to the positive mold of the first molding surface 102a of the first resin layer 102 of the wafer lens 100 finally obtained, and forms the first optical surface 11d of the first molding surface 102a. A second optical transfer surface 43a for forming the first flange surface 11g, and a second flange transfer surface 43b for forming the first flange surface 11g. The second optical transfer surface 43a is transferred by the first optical transfer surface 31a, and a plurality of second optical transfer surfaces 43a are arranged in an array, and are formed in a substantially hemispherical convex shape.

The sub master molding part 41 is made of resin. Any resin can be used as the resin, such as a photo-curing resin, a thermosetting resin, and a thermoplastic resin, as long as it can mold the first lens element 11 and the sub-sub master mold 50 described later. However, a photocurable resin (second photocurable resin) is particularly preferable. As the photocurable resin, the same acrylic resin, allyl ester resin, epoxy resin, vinyl resin, or the like as the first resin layer 102 of the wafer lens 100 can be used. Moreover, as said resin, resin with favorable mold release property, especially transparent resin are preferable, and resin which can be released without applying a mold release agent is good.

The sub-master substrate 42 is formed of a smooth material such as quartz, glass, silicon wafer, metal, or resin. In consideration of transparency or light transmission (the point that light can be irradiated from above or from below), the sub master substrate 42 is preferably made of quartz, glass, or the like.

As shown in FIG. 4C, the sub-sub master mold 50 includes a sub-sub master molding portion 51 that is a resin portion and a light-transmitting sub-sub master substrate 52. The sub-sub master molding part 51 and the sub-sub master substrate 52 have a laminated structure. The sub-sub master molding unit 51 has a third transfer surface 53 that forms the first molding surface 102a of the wafer lens 100 on the end surface 51a. The third transfer surface 53 corresponds to the first molding surface 102a of the first resin layer 102 of the wafer lens 100, and the third optical transfer surface 53a for forming the first optical surface 11d of the first molding surface 102a. And a third flange transfer surface 53b for forming the first flange surface 11g. That is, the sub-submaster mold 50 functions as a resin transfer mold for forming the first molding surface 102 a of the first resin layer 102. The third optical transfer surface 53a is transferred by the second optical transfer surface 43a as described above, and a plurality of the third optical transfer surfaces 53a are arranged in an array, and are formed in a substantially hemispherical concave shape.

The sub-sub master molding part 51 is made of resin. As this resin, the same resin as the first resin layer 102 can be used, and the resin may be formed of the same material as the first resin layer 102 of the wafer lens 100. The sub-submaster substrate 52 is formed of the same material as the sub-master substrate 42. Note that the sub master molding part 41 and the sub sub master molding part 51 are not necessarily formed of the same material. Further, the sub-master substrate 42 and the sub-sub-master substrate 52 are not necessarily formed of the same material, and may be formed of different materials.

In the sub-submaster molding part 51, the thick light transmittance, which is the light transmittance of the thickest part, is 60% or more at a wavelength of 340 nm. Here, the thickness light transmittance of the resin transfer mold is represented by a value at 340 nm in order to cure the photocurable resin composition for forming the first resin layer 102 in the vicinity of and around 340 nm. A UV light source that irradiates light in the wavelength range of a large number of times, a general UV polymerization initiator has sensitivity at least in the vicinity of 340 nm, and when a resin transfer mold is formed of a photocurable resin composition, the light Photopolymerization initiators at 340 nm include many curable resin compositions having a property that the light transmittance is low on the short wavelength side and the light transmittance is high on the long wavelength side at a predetermined wavelength. This is because an appropriate combination of the two can be defined by defining the light absorption characteristics of the resin and the light transmittance of the resin transfer mold. From another point of view, this means that the photopolymerization initiator contained in the photocurable resin composition for forming the first resin layer 102 has a predetermined light transmission at the longest wavelength at which the photopolymerization initiator exhibits a predetermined absorbance or more. This corresponds to the use of a resin showing the rate for the resin transfer mold. More specifically, in the absorbance characteristics of the photopolymerization initiator contained in the photocurable resin composition for forming the first resin layer 102, a wavelength in the vicinity of rising on the longest wavelength side (for example, the absorbance is A resin transfer mold having a thick light transmittance of about 30% at the longest wavelength when 0.3) is used. Actually, since the light transmittance of the resin transfer type often has a rise in the ultraviolet region, the thick light transmittance is preferably 30% ± 10%. In order to set the light transmittance to 60%, the absorption maximum of the photopolymerization initiator of the photocurable resin that forms the sub-submaster molding part 51 has a short wavelength (specifically, a wavelength of 250 nm or less). It is preferable to use it. For example, if the reaction wavelength of the photopolymerization initiator of the sub-submaster molding part 51 is shorter than the reaction wavelength of the photopolymerization initiator of the first and second resin layers 102 and 103, the meat of the sub-submaster molding part 51 This is advantageous for increasing the light transmittance. As described above, the sub-master molding portion 51 has a desired thickness light transmittance with respect to the absorbance at the wavelength of the irradiation light for curing the photocurable resin of the first resin layer 102. As such, it is adjusted by changing the type of the photopolymerization initiator or changing the thickness of the resin transfer mold. Further, the sub-sub master molding portion 51 may be made thin as long as there is no hindrance to molding or mold release. In the case of the present embodiment, the absorbance of the photocurable resin of the first resin layer 102 at a wavelength of 340 nm of irradiation light is less than 0.25, so that the curing of the photocurable resin of the first resin layer 102 is optimized. In addition, a photopolymerization initiator is used such that the thickness light transmittance of the sub-submaster molding part 51 is 60% in order not to absorb much irradiation light.

FIG. 5 shows a photopolymerization initiator (first photocurable resin composition) for forming the first resin layer 102 in the present embodiment and each embodiment to be described later. The resin composition used for the first resin layer 102 and the sub-submaster mold 50 is variously changed to obtain good characteristics for the absorbance of the first photopolymerization initiator) and the thick light transmittance of the sub-submaster mold 50. A combination of the two is selected, and the relationship between the two calculated experimentally based on them is shown. As shown in FIG. 5, the thickness light transmittance of the sub-submaster mold 50 at a wavelength of 340 nm is T%, and the photopolymerization initiator contained in the photocurable resin composition for forming the first resin layer 102 is 0.01. When the absorbance at a wavelength of 340 nm when dissolved in a mass% acetonitrile solution is A, the thick light transmittance T and the absorbance A satisfy the following conditional expression (1). That is, the thick light transmittance T is determined within a range satisfying the conditional expression (1) in the absorbance A.
T = ± 30 + 100 × exp (−2.3026A) (1)

FIG. 2 (F) is a diagram showing the light transmittance of the sub-sub master molding part 51. In FIG. 2 (F), L3 is the photocurable resin of this embodiment. Correspondingly, for the photopolymerization initiator for forming the first resin layer 102, the absorbance at a wavelength of 340 nm is, for example, less than 0.25 in a 0.01% by mass solution of acetonitrile.

The master mold 30, the sub master mold 40, and the sub sub master mold 50 used for molding the first resin layer 102 of the wafer lens 100 have been described above. The same applies to the molding of the second resin layer 103. Use a mold. In this case, for example, a master die 30 having a concave first transfer surface 31 is used, and a sub master die 40 having a convex second transfer surface 43 is used. At this time, the sub master mold 40 corresponds to a resin transfer mold and has the same light transmittance as the sub sub master mold 50 described above. Thereby, the second molding surface 103 a of the second resin layer 103 is formed by the sub master mold 40. The second resin layer 103 may be formed by the sub-submaster mold 50.

Manufacturing Method of Wafer Lens With reference to FIGS. 6A to 6F, a manufacturing process of the wafer lens 100 performed using the master mold 30, the sub master mold 40, and the sub sub master mold 50 described above will be described. . Hereinafter, the molding of the first resin layer 102 will be described, but the same process is performed for the molding of the second resin layer 103.

First, the master mold 30 corresponding to the final shape of the first resin layer 102 is produced by grinding or the like. Next, as shown in FIG. 6A, the resin composition 41 b is disposed on the master mold 30, and ultraviolet rays are irradiated from a UV generator (not shown) while pressing the sub-master substrate 42 from above the master mold 30. The resin composition 41b sandwiched therebetween is cured. At this time, the first transfer surface 31 of the master mold 30 is transferred to the cured resin and has a second transfer surface 43 (second optical transfer surface 43a and second flange transfer surface 43b shown in FIG. 4B). A sub master molding part 41 is formed. Examples of the light source used in the UV generator include xenon arc lamps, high-pressure mercury lamps, metal halide lamps, UV lasers, xenon flash lamps, LEDs, G-lamps, black lights, and the like that generate light in the ultraviolet region. . In particular, it is preferable to use a xenon flash lamp having a wide emission wavelength region in an ultraviolet region including 365 nm and 340 nm.

Next, as shown in FIG. 6 (B), the sub-master mold 40 is fabricated by releasing the sub-master molding part 41 and the sub-master substrate 42 as a single unit from the master mold 30.

Next, as shown in the master FIG. 6C, the resin composition 51b is arranged on the sub master mold 40, and a UV generator (not shown) is used while pressing the sub sub master substrate 52 from above the sub master mold 40. The resin composition 51b sandwiched therebetween is cured by irradiating with ultraviolet rays. At this time, the second transfer surface 43 of the sub-master mold 40 is transferred to the cured resin, and the third transfer surface 53 (the third optical transfer surface 53a and the third flange transfer surface 53b shown in FIG. 4C) is transferred. The sub-sub-master molding part 51 is formed. As the exposure apparatus equipped with the UV generator, the same exposure apparatus as that used when forming the sub-master mold 40 can be used.

Next, as shown in FIG. 6 (D), the sub-sub master mold part 51 and the sub-sub master substrate 52 are integrally released from the sub-master mold 40, and the sub-sub master mold 50 is completed.

Next, the wafer lens 100 is manufactured. As shown in FIG. 6E, a resin composition 102b (a photocurable resin composition for forming the first resin layer 102) is disposed on the sub-submaster mold 50, and a substrate is formed from above the sub-submaster mold 50. While pressing 101, ultraviolet rays are irradiated by a UV generator (not shown) to cure the resin composition 102b sandwiched therebetween. At this time, the third transfer surface 53 of the sub-submaster mold 50 is transferred to the cured resin, and the first molding surface 102a (the first optical surface 11d and the first flange surface 11g shown in FIG. 1B) is provided. One resin layer 102 is formed. Note that the second resin layer 103 may be formed on the other surface 101b of the substrate 101 in the same process as described above. As the exposure apparatus on which the UV generator is mounted, the same exposure apparatus used when forming the sub master mold 40 and the sub sub master mold 50 can be used. In curing the resin composition to form the first resin layer 102 and the second resin layer 103, the

lens elements

11 and 12 of the resin layers 102 and 103 can exhibit the intended optical performance. Therefore, it is preferable to set the exposure conditions appropriately so as not to cause yellowing of the resin and deterioration of durability after molding. Moreover, after exposure or in parallel with exposure, heating may be performed to promote curing.

Thereafter, as shown in FIG. 6 (F), the first resin layer 102 and the substrate 101 are integrally released from the sub-submaster mold 50. When the second resin layer 103 has already been formed, the wafer lens 100 is completed. When the second resin layer 103 is not formed, the second resin layer 103 is formed by performing the same process, and the wafer lens 100 is completed by releasing the sub-sub master mold 50.

Note that the wafer lens 100 manufactured by the above method is laminated and cut out by dicing so that the outer shape becomes a square shape with the first lens body 11a and the like as the center, thereby forming the compound lens 10 shown in FIG. When stacking a plurality of wafer lenses 100, a diaphragm may be provided between the wafer lenses 100. In this case, the aperture of the stop is arranged in alignment with each first lens body 11a and the like.

According to the manufacturing method of the wafer lens 100 described above, when the photopolymerization initiator of the photocurable resin forming the first and second resin layers 102 and 103 has low sensitivity, the first and second molding surfaces 102a, The light transmittance of the photocurable resin in the thickest part of the sub-submaster mold 50, which is a resin transfer mold for transferring 103a, is relatively high, and the photocurable resin for forming the first and second resin layers 102 and 103 is used. When the photopolymerization initiator has high sensitivity, the light transmittance of the photocurable resin in the thickest portion of the sub-submaster mold 50 that transfers the first and

second molding surfaces

102a and 103a is relatively low, so that the first In addition, an optimal amount of light can be transmitted to cure the photocurable resin of the second resin layers 102 and 103. Thereby, light efficiently reaches the photocurable resins of the first and second resin layers 102 and 103, and the first and second

optical surfaces

11d and 12d can be accurately transferred. In addition, since unnecessary light is not irradiated, adverse effects such as yellowing of the resin and environmental tests can be prevented.

[Example 1]
An ultraviolet curable resin composition is arranged on an 8-inch diameter glass substrate, and a spherical recess having a diameter of 3 mm and a depth of 0.5 mm corresponding to the first lens element 11 shown in FIG. 1 is an 8 × 8 matrix. The procedure of releasing the mold after pressing with a metal master mold arranged in a shape and irradiating ultraviolet rays with a xenon flash lamp through the glass substrate to cure the resin composition is repeated while changing the position on the glass substrate. As a result, a submaster mold having transfer portions corresponding to about 1000 first lens elements 11 on a glass substrate was produced. An ultraviolet curable resin composition obtained by adding 0.5% by mass of a photopolymerization initiator to an acrylic resin monomer as a resin composition for a sub-submaster molded part was disposed on the submaster mold thus obtained. . Then, the resin composition was pressed with a glass substrate, irradiated with ultraviolet rays with a xenon flash lamp to cure the resin composition, and then released to form a sub-submaster molding part made of resin and having a transfer surface. In this way, a sub-submaster type was produced.

As the sub-sub master type, three types satisfying the following conditions (i) to (iii) were produced for comparison. Conditions (i) to (iii) correspond to L1, L2, and L3 of the photocurable resin shown in FIG. 2 (F), respectively. The thick light transmittance of the sub-submaster molded part was changed mainly by changing the type of photopolymerization initiator added to the resin composition. Specifically, IRGACURE907 was used in (i), IRGACURE2959 was used in (ii), and IRGACURE184 was used in (iii) (both manufactured by Ciba Japan).
(I) At a wavelength of 340 nm, the thickest part has a thick light transmittance of 6%.
(Ii) At the wavelength of 340 nm, the thickest part has a thick light transmittance of 40%.
(Iii) The light transmittance of the thickest part is 70% at a wavelength of 340 nm.

A resin composition for forming the first resin layer 102 shown in FIG. 1 was disposed on the thus obtained sub-submaster mold. As a resin composition for forming the 1st resin layer 102, the cationic photoinitiator IRGACURE250 (made by Ciba Japan) was used for hydrogenated bisphenol A type epoxy resin as a photoinitiator. This cationic photopolymerization initiator has an absorbance at a wavelength of 340 nm of about 0.05 when dissolved in an acetonitrile solution so as to be 0.01% by mass. A glass substrate was pressed against the resin composition on the sub-submaster mold, and the resin composition was cured by irradiating ultraviolet rays with a xenon flash lamp so that the integrated exposure amount at 365 nm was 6000 mJ / cm ² .

The second resin layer 103 has substantially the same procedure, and a resin composition similar to L1 to L3 is arranged on an 8-inch diameter glass substrate, and the diameter corresponds to the second lens element 12 shown in FIG. 3mm and 0.5mm deep spherical concave parts are pressed with a metal master mold arranged in an 8x8 matrix, and the resin composition is cured by irradiating ultraviolet rays with a xenon flash lamp through a glass substrate. Then, by repeating the mold release procedure, three types of sub-master molds having transfer portions corresponding to about 1000 lens elements on a glass substrate were produced. A resin composition similar to the resin composition for forming the first resin layer is disposed on each of the submaster molds thus obtained, and the back surface of the glass substrate on which the first resin layer 102 is formed is opposed to the submaster mold. After aligning the optical axis of the lens element with the center of each transfer part of the sub-master type, press the back of the glass substrate and the sub-master type, and irradiate ultraviolet rays with a xenon flash lamp to resin composition The product was cured to form a second resin layer 103. Thereafter, the wafer lens was produced by releasing the mold.

Table 1 shows the performance test results of the wafer lens 100 under the above conditions.
In Table 1, the item of optical surface shape indicates the measurement result of the surface shape of the first and

second lens elements

11 and 12 of the wafer lens 100. The surface shape was measured using a contact-type ultra-high precision three-dimensional measuring machine. The accuracy of the surface shape was evaluated by the difference (hereinafter referred to as the PV value) between the portion having the largest shape error (Peak) and the portion having the smallest shape (Valley) from the lens design value of the first optical transfer surface 31a. When the PV value was less than 500 nm, ◎, when the PV value was 500 nm or more and less than 1 μm, ◯, when the PV value was 1 μm or more and less than 3 μm, Δ, when it was 3 μm or more, ×.

The coloring item indicates the measurement result of the total light transmittance with respect to the incident light amount of the visible light of the first and

second lens elements

11 and 12 of the wafer lens 100. The total light transmittance was measured using a spectrophotometer. When the absolute value of the total light transmittance was 88% or more, it was rated as ◯, when it was 80% or more and less than 88%, it was marked as Δ, and when it was less than 80%, it was marked as x.

The item of the environmental test indicates a durability test result of the imaging lens 200 obtained by dicing the wafer lens 100 into pieces. The environmental test was performed by subjecting the imaging lens 200 to reflow treatment three times and then applying a thermal shock. Specifically, after 30 minutes in an environment of −40 ° C., 30 minutes in an environment of 85 ° C. was defined as one cycle, and this was performed for 50 cycles. The environmental test was performed on 100 imaging lenses 200. In the imaging lens 200, the number of peeled from the glass / resin interface was 0 when it was 0, Δ when it was 1 or more and less than 10, and x when it was 10 or more.

As shown in Table 1, in this example, a good lens element surface shape could be obtained when the resin for the sub-submaster type was in condition (iii). In this case, the lens elements of the first and second resin layers were not colored and withstood environmental tests.

On the other hand, when the resin for molding the sub-submaster was in the condition (i), the photocurable resin composition for forming the first and second resin layers was uncured. In addition, when the resin for molding the sub-submaster was in the condition (ii), the photocurable resin for forming the first and second resin layers was partially uncured.

[Example 2]
As the resin composition for forming the first resin layer 102, except that 2-alkyl-2-adamantyl- (meth) acrylate was added with a radical photopolymerization initiator IRGACURE184 as a photopolymerization initiator. A wafer lens was produced in the same procedure as in Example 1. The radical photopolymerization initiator used in this example has an absorbance at a wavelength of 340 nm of about 0.05 when dissolved in an acetonitrile solution so as to be 0.01% by mass.

The resin composition for forming the sub-sub master mold 50 for forming the first resin layer and the resin composition for forming the sub-master mold for forming the second resin layer are the same as those in Example 1. Same as conditions (i) to (iii). Conditions (i) and (ii) are comparative examples.
In this Example 2, the result of the performance test was the same as that of Example 1.

[Second Embodiment]
Hereinafter, a method for manufacturing a wafer lens according to the second embodiment will be described. The wafer lens manufacturing method according to the second embodiment is a modification of the wafer lens manufacturing method according to the first embodiment, and parts not specifically described are the same as those in the first embodiment.

The photopolymerization initiator contained in the photocurable resin composition for forming the first and second resin layers 102 and 103 has an absorbance of 0.25 or more in a 0.01 mass% acetonitrile solution at a wavelength of 340 nm. Use less than 1.0. This photopolymerization initiator is a UV polymerization initiator that has a sensitivity on the short wavelength side, for example, a wavelength of 300 nm to 380 nm and generates radicals at a short wavelength. Specific examples include α-aminoalkylphenone (manufactured by Ciba Japan, IRGACURE907, etc.).

FIG. 2D is a graph showing the absorbance of IRGACURE907. In addition, the light absorbency of a photoinitiator is measured in the state melt | dissolved in the 0.01 mass% acetonitrile solution.

In the sub-submaster molding part 51, the thick light transmittance, which is the light transmittance of the thickest part, is 7% or more and less than 60% at a wavelength of 340 nm. In order to make the wall thickness light transmittance 7% or more and less than 60%, the absorption maximum of the photopolymerization initiator of the photocurable resin forming the sub-submaster molded part 51 has a short wavelength (specifically, a wavelength of 300 nm or less). Use one. That is, the reaction wavelength of the photopolymerization initiator of the sub-submaster molding part 51 is shorter than the reaction wavelength of the photopolymerization initiator of the first and second resin layers 102 and 103.

In FIG. 2 (F), L2 is the photocurable resin of this embodiment. In the case of the present embodiment, the absorbance of the photocurable resin of the first resin layer 102 at a wavelength of 340 nm of irradiation light for curing the photocurable resin composition for forming the first resin layer 102 is 0.25. In order to optimize the curing of the photocurable resin of the first resin layer 102 in order to optimally absorb the irradiation light, the sub-master molding portion 51 has a thick light transmittance of 7%. An appropriate photopolymerization initiator is selected so as to be less than 60% and the thickness of the sub-submaster molding part 51 is adjusted. As in the first embodiment described above, the thickness light transmittance of the sub-submaster molding part 51 is the absorbance of the photopolymerization initiator contained in the photocurable resin composition for forming the first resin layer 102. In the characteristics, it is preferable to use the longest wavelength when the absorbance is 0.3, which is 30% ± 10%. In addition, it is preferable to use one that satisfies the conditional expression (1) described above.

Example 3
As in Example 1, except that a radical polymerization initiator IRGACURE907 (manufactured by Ciba Japan) was used as a photopolymerization initiator used in the resin composition for forming the first resin layer 102 and the second resin layer 103. A wafer lens was prepared according to the procedure described above. This polymerization initiator has an absorbance at a wavelength of 340 nm of about 0.25 when dissolved in an acetonitrile solution so as to be 0.01% by mass.

The resin composition for forming the sub-master mold for forming the first resin layer and the resin composition for forming the sub-master mold for forming the second resin layer are the same as those in Example 1. Same as (i) to (iii). Conditions (i) and (iii) are comparative examples.

As shown in Table 2, in this example, when the resin for the sub-sub master mold is in the condition (ii), a good surface shape of the first and second lens elements can be obtained. In this case, the lens elements of the first and second resin layers were not colored and withstood environmental tests.

On the other hand, when the resin for molding the sub-submaster was in the condition (i), the photocurable resin composition for forming the first and second resin layers was uncured. In addition, when the resin for forming the sub-submaster is in the condition (iii), although the photocurable resin for forming the first and second resin layers is cured, coloring occurs, and the durability in the environmental test is also adversely affected. Occurred.

[Third Embodiment]
Hereinafter, a method for manufacturing a wafer lens according to the third embodiment will be described. The wafer lens manufacturing method according to the third embodiment is a modification of the wafer lens manufacturing method according to the first embodiment, and parts not specifically described are the same as those in the first embodiment.

The photopolymerization initiator contained in the photocurable resin composition for forming the first and second resin layers 102 and 103 has an absorbance of 1.0 or more in a 0.01 mass% acetonitrile solution at a wavelength of 340 nm. Use one. This photopolymerization initiator is a UV polymerization initiator that has a sensitivity on the short wavelength side, for example, a wavelength of 320 nm to 430 nm, and generates radicals at a short wavelength. Specifically, α-aminoalkylphenone (manufactured by Ciba Japan, IRGACURE 369, etc.) and the like can be mentioned.

FIG. 2 (E) is a graph showing the absorbance of IRGACURE369. In addition, the light absorbency of a photoinitiator is measured in the state melt | dissolved in the 0.01 mass% acetonitrile solution.

In the sub-submaster molding part 51, the thick light transmittance, which is the light transmittance of the thickest part, is less than 7% at a wavelength of 340 nm. In order to make the wall thickness light transmittance less than 7%, the absorption maximum of the photopolymerization initiator of the photocurable resin forming the sub-submaster molded portion 51 is a short wavelength (specifically, a wavelength of 320 nm or less). Use. That is, the reaction wavelength of the photopolymerization initiator of the sub-submaster molding part 51 is shorter than the reaction wavelength of the photopolymerization initiator of the first and second resin layers 102 and 103. The thick light transmittance can be reduced to less than 7% by making the sub-submaster molding portion 51 relatively thick.

In FIG. 2 (F), L1 is the photocurable resin of the present embodiment. In the case of this embodiment, the absorbance of the photocurable resin of the first resin layer 102 at a wavelength of 340 nm of the irradiation light for curing the photocurable resin of the first resin layer 102 is 1.0 or more, and the first In order to optimize the curing of the photo-curing resin of the resin layer 102, a photopolymerization initiator in which the thickness light transmittance of the sub-submaster molding part 51 is less than 7% in order to absorb a relatively large amount of irradiation light. Is used. As in the first embodiment described above, the thickness light transmittance of the sub-submaster molding part 51 is the absorbance of the photopolymerization initiator contained in the photocurable resin composition for forming the first resin layer 102. In the characteristics, it is preferable to use the longest wavelength when the absorbance is 0.3, which is 30% ± 10%. In addition, it is preferable to use one that satisfies the conditional expression (1) described above.

Example 4
Example 1 except that a radical photopolymerization initiator IRGACURE369 (manufactured by Ciba Japan) was used as the photopolymerization initiator used in the resin composition for forming the first resin layer 102 and the second resin layer 103. A wafer lens was produced in the same procedure. This polymerization initiator has an absorbance at a wavelength of 340 nm of about 2.5 when dissolved in an acetonitrile solution so as to be 0.01% by mass.

The resin composition for forming the sub-master mold for forming the first resin layer and the resin composition for forming the sub-master mold for forming the second resin layer are the same as those in Example 1. Same as (i) to (iii). Conditions (ii) and (iii) are comparative examples.

As shown in Table 3, in the present example, when the resin for the sub-sub master mold was in the condition (i), good surface shapes of the first and second lens elements could be obtained. In this case, the lens elements of the first and second resin layers were not colored and withstood environmental tests.

On the other hand, when the resin for molding the sub-submaster was in the conditions (ii) and (iii), although the photocurable resin composition was cured, coloring occurred, and the durability in the environmental test was also adversely affected.

The wafer lens manufacturing method according to the present embodiment has been described above, but the wafer lens manufacturing method according to the present invention is not limited to the above. For example, in the above embodiment, the shapes and sizes of the first and second

optical surfaces

11d and 12d can be changed as appropriate according to the application and function.

In the above embodiment, the wafer lens 100 does not have to be disk-shaped and can have various contours such as an ellipse. For example, the dicing process can be simplified by forming the wafer lens 100 into a square plate shape from the beginning.

Further, in the above embodiment, the number of the first and

second lens elements

11 and 12 formed in the wafer lens 100 is not limited to four as illustrated, and may be two or more. At this time, the arrangement of the first and

second lens elements

11 and 12 is preferably on a lattice point for convenience of dicing. Further, the interval between the

adjacent lens elements

11 and 12 is not limited to the illustrated one, and can be set as appropriate in consideration of workability and the like.

In the above-described embodiment, the resin is disposed on the sub-submaster mold 50 third transfer surface 53, but the resin may be disposed on one surface 101a and the other surface 101b of the substrate 101.

In the above embodiment, a coupling agent may be applied in advance to the one surface 101a and the other surface 101b of the substrate 101. Further, a release agent may be applied in advance to each

transfer surface

31, 43, 53 of each

mold

30, 40, 50.

Claims

A wafer lens manufacturing method comprising a substrate and a resin layer formed on one substrate surface of the substrate and having a molding surface including an optical surface,
The step of molding the resin layer having the molding surface using a resin transfer mold having an optical transfer surface having a shape obtained by inverting the optical surface,
The resin layer is formed of a first photocurable resin,
The first photocurable resin is obtained by curing the first photocurable resin composition containing the first photopolymerization initiator,
When the absorbance of the first photopolymerization initiator is represented by a value measured in a state where the first photopolymerization initiator is dissolved in acetonitrile at a concentration of 0.01% by mass, the first photopolymerization initiator has a wavelength of 340 nm. When the absorbance of the photopolymerization initiator is less than 0.25, the resin transfer mold having a thickness light transmittance of 60% or more, which is the light transmittance of the thickest part of the resin transfer mold, is used. When the absorbance of the photopolymerization initiator 1 is 0.25 or more and less than 1.0, the resin transfer mold having a thickness light transmittance of 7% or more and less than 60% is used, and the first photopolymerization start is started. When the absorbance of the agent is 1.0 or more, a method for producing a wafer lens, wherein the resin transfer mold has a thickness light transmittance of 1% or more and less than 7%.
A wafer lens manufacturing method comprising a substrate and a resin layer formed on one substrate surface of the substrate and having a molding surface including an optical surface,
The step of molding the resin layer having the molding surface using a resin transfer mold having an optical transfer surface having a shape obtained by inverting the optical surface,
The resin layer is formed of a first photocurable resin, the resin transfer mold is formed of a second photocurable resin,
The first photocurable resin is obtained by curing the first photocurable resin composition containing the first photopolymerization initiator,
The resin transfer at the longest wavelength at which the absorbance of the first photopolymerization initiator is 0.3 or more measured in a state where the first photopolymerization initiator is dissolved in acetonitrile at a concentration of 0.01% by mass. What is claimed is: 1. A wafer lens manufacturing method comprising using a resin transfer mold having a thickness light transmittance of 30% ± 10%, which is a light transmittance of a thickest part of a mold.
The resin portion constituting the optical transfer surface of the resin transfer mold is formed of a second photocurable resin obtained by curing a second photocurable resin composition containing a second photopolymerization initiator. The manufacturing method of the wafer lens as described in any one of Claim 1 and Claim 2.
The said 1st photocurable resin uses any one of an acrylic resin, an allyl ester resin, a vinyl-type resin, and an epoxy-type resin, It is any one of Claim 1 to 3 characterized by the above-mentioned. Wafer lens manufacturing method.
The method for producing a wafer lens according to any one of claims 1 to 4, wherein the first photocurable resin is an ultraviolet curable resin.
6. The resin transfer mold according to claim 1, wherein the resin transfer mold is a sub-sub-master mold formed by transferring twice from a master mold having a transfer surface corresponding to the molding surface. The manufacturing method of the wafer lens as described in any one of Claims 1-3.
6. The resin transfer mold according to claim 1, wherein the resin transfer mold is a sub-master mold formed by one transfer from a master mold having a transfer surface corresponding to the molding surface. The manufacturing method of the wafer lens as described in any one of Claims 1-3.
The method for manufacturing a wafer lens according to any one of claims 1 to 7, wherein the substrate is made of glass.
The resin transfer mold includes a light-transmitting substrate and a resin portion having a mold surface formed on one substrate surface of the substrate and including a plurality of the optical transfer surfaces. Item 9. The method for producing a wafer lens according to any one of Items 8 to 8.
The wafer lens according to any one of claims 3 to 9, wherein the first photocurable resin and the second photocurable resin are cured at different wavelengths. Production method.
The photocurable resin composition for obtaining the first photocurable resin is more easily cured on the longer wavelength side than the photocurable resin composition for obtaining the second photocurable resin. The method for producing a wafer lens according to any one of claims 3 to 10.