JP2011240651A - Molding die for wafer lens and method for manufacturing the molding die for wafer lens - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a molding die for a wafer lens in which surface transferability to a concave lens surface is improved, and service life of the molding die itself can be made longer, and a method for manufacturing the molding die for the wafer lens.SOLUTION: In the molding die (sub-sub-master 230) for the wafer lens for molding the wafer lens 51 in which a plurality of concave lens parts 22a made of photocurable resin are formed on at least one surface of a substrate (glass substrate 12) for a lens. The molding die includes: a substrate 234 for a molding die in which a plurality of protrusion parts 240 are formed on one surface; and a negative-shaped resin molding part 232 corresponding to the optical surface shape of the concave lens part 22a which is formed so as to cover a plurality of the protrusion parts 240 in the one surface of the substrate 234 for the molding die. Light transmittance to light with a wavelength of 365 nm when the thickness of the substrate 234 for a molding die is 1 mm is ≥90%, and also, light transmittance to light with a wavelength of 365 nm when the thickness of the resin molding part 232 is 1 mm is 20 to 80%.

Description

  The present invention relates to a wafer lens mold and a method for manufacturing a wafer lens mold.

  Conventionally, in the field of manufacturing optical lenses, a technique for obtaining an optical lens having high heat resistance by providing a lens portion (optical member) made of a curable resin such as a thermosetting resin on a glass plate has been studied ( For example, see Patent Document 1).

Furthermore, as a method of manufacturing an optical lens to which this technology is applied, by forming a so-called “wafer lens” in which a cured resin is integrated with a glass flat plate, a plurality of lenses are molded simultaneously in an integrated state. A method of cutting a glass flat plate portion after molding has been developed. According to this manufacturing method, the manufacturing cost of the optical lens can be reduced.
As a specific method for manufacturing an optical lens, when creating a positive sub-master mold from a negative master mold (hereinafter referred to as a master) corresponding to the lens portion, a sub-master for backing such as flat glass Sub-master molding die (hereinafter referred to as sub-master) is formed by molding the sub-master molding part on the substrate, and flat glass or the like is used when creating a negative sub-sub-master molding die from this sub master. A sub-submaster molding die (hereinafter referred to as a sub-submaster) is formed by molding a sub-submaster molding portion on the sub-submaster substrate for backing the substrate, and an optical lens is molded using the sub-submaster. In the present invention, the shape of the optical surface finally used as an optical lens (hereinafter also simply referred to as a lens surface) is used as a reference, that is, when the lens surface has a convex lens shape. The convex lens shape is referred to as “positive shape”, and when the inverted shape, that is, the shape of the optical surface of the optical lens is a convex lens, the concave lens shape is described as “negative shape”. Therefore, when the shape is transferred sequentially from the master to the sub master, the sub sub master, and the optical lens as described above, the sub sub master has a negative shape, the sub master has a positive shape, and the master has a negative shape.
In some cases, the sub master is molded by the master and the lens surface of the optical lens is molded by the sub master. In this case, the sub master has a negative shape and the master has a positive shape.
In this way, when transferring and molding from the master to the submaster, subsubmaster, and optical lens in order, or when transferring from the master to the submaster and optical lens, and molding, the sub The master molded part and the sub-submaster molded part are usually formed of a resin having good mold release properties such as a fluororesin, a silicone resin, and a thermoplastic olefin resin.
However, the above-mentioned resin having good releasability is soft, has poor surface transfer to the lens surface, and has a problem of large variations in accuracy within the wafer surface.
Accordingly, it is known that the surface accuracy is improved by using a lens resin for forming a lens surface as a material for the sub-master molded portion and the sub-sub-master molded portion. However, since the resin for lenses is poor in releasability, the releasability is improved by performing a release treatment on the surface of the sub master molding part or the sub sub master molding part.

Japanese Patent No. 3926380

Although the mold release property is improved by performing the mold release treatment as described above, the resin for the lens is used as the material of the molding part of the mold for molding the lens surface, and the concave lens surface is used as the optical lens. When molded, that is, when the molding surface of the mold is convex, there is a problem that the optical surface shape is not stable.
This is because most of the ultraviolet curable resin as a lens resin has an absorption wavelength of the initiator shorter than 365 nm. Therefore, when the molding part of the convex mold that molds the concave lens surface is formed of a lens resin, the light having a wavelength of 365 nm or less used when the lens resin is cured is projected on the mold. The portion (center portion) absorbs most of the resin, and the outer portion transmits relatively without being absorbed, so that the intensity of the transmitted UV light depends on the thickness of the resin provided in the molding portion of the mold. I knew that it would vary. In other words, when the lens surface is molded by irradiating UV light, the resin of the molding part of the mold is thin, and curing starts from the outside of the lens surface (also referred to as the flange part). This is thought to be caused by the fact that the resin that forms the lens surface is pulled outward. Further, since the thick resin forming the molding part of the mold absorbs UV light, the UV light does not efficiently reach the corresponding lens resin, and the important surface shape is not stable.
Furthermore, when the molding part of the molding die forming the lens surface is irradiated with UV light for a long time, there is a problem that it is yellowed by absorbing the UV light and the life is shortened.
The present invention has been made in view of the above circumstances, and is capable of improving the surface transfer property to the concave lens surface and prolonging the life of the mold itself, and the production of the mold for the wafer lens. It aims to provide a method.

According to one aspect of the present invention, there is provided a wafer lens mold for molding a wafer lens in which a plurality of concave lenses made of a photocurable resin are formed on at least one surface of a lens substrate,
A mold substrate having a plurality of convex portions formed on one surface;
A negative-shaped resin molding portion formed on the one surface of the mold substrate so as to cover the plurality of convex portions, and corresponding to the optical surface shape of the concave lens portion,
The light transmittance for light having a wavelength of 365 nm when the thickness of the mold substrate is 1 mm is 90% or more, and the light transmittance for light having a wavelength of 365 nm when the thickness of the resin molding portion is 1 mm is 20 to 20%. There is provided a wafer lens mold characterized by being 80%.

According to another aspect of the present invention, there is provided a method for producing a wafer lens mold for molding a wafer lens in which a plurality of photo-curing resin concave lens portions are formed on at least one surface of a lens substrate. There,
A plurality of convex portions are formed on one surface of the mold substrate,
On the one surface of the mold substrate, a negative resin molding portion corresponding to the optical surface shape of the concave lens portion is formed so as to cover the plurality of convex portions,
The light transmittance for light having a wavelength of 365 nm when the thickness of the mold substrate is 1 mm is 90% or more, and the light transmittance for light having a wavelength of 365 nm when the thickness of the resin molding portion is 1 mm is 20 to 20%. A method for producing a wafer lens mold, characterized by being 80%, is provided.

According to the present invention, a negative shape (convex shape) corresponding to the optical surface shape of the concave lens portion is formed by the plurality of convex portions formed on the mold substrate having a high light transmittance (90% or more) with respect to light having a wavelength of 365 nm. The thickness of the resin molded portion is reduced, and variations in the intensity of UV light transmitted through the resin molded portion can be prevented. Therefore, the UV light efficiently reaches the resin portion that forms the concave lens portion. That is, the curing timing of the resin forming the concave lens part and the other flange part can be made uniform, and the surface transferability of the concave lens part can be improved.
Further, yellowing due to absorption of UV light can be suppressed, and the life of the wafer lens mold itself can be improved.
In addition, since the plurality of convex portions formed on the mold substrate are resin-molded portions for covering the periphery with resin and molding the optical surface, high accuracy is not required for the shape of the convex portions. The convex part formed on the mold substrate can be etched with such an accuracy that it is not exposed from the resin molded part. Compared to the case where all of the wafer lens mold is formed of glass, the labor of glass processing is reduced. This eliminates the need for manufacturing.
In addition, since the resin molding portion of the wafer lens mold is thin, any resin having a difficult surface transfer property can be used. Furthermore, since the amount of resin in the resin molded portion can be reduced, the cost can be reduced.

It is sectional drawing which shows schematic structure of an imaging module and the imaging lens used for it. It is drawing for demonstrating roughly the mode at the time of cut | disconnecting the wafer lens laminated body manufactured in the manufacture process of an imaging lens. It is a perspective view which shows schematic structure of a wafer lens. It is a perspective view which shows schematic structure of a master, a submaster, and a subsubmaster. It is drawing for demonstrating the manufacturing method of a wafer lens. It is drawing for demonstrating the manufacturing method of a wafer lens.

Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings.
[Imaging module]
As shown in FIG. 1, the imaging module 1 includes an imaging lens 2, an imaging device cover glass 4, an imaging device 6, and the like. The imaging device cover glass 4 and the imaging device 6 are disposed below the imaging lens 2. Has been. For example, a CMOS type image sensor is used as the image sensor 6.

The imaging lens 2 includes two lens groups 8 and 10 and a spacer 7.
The lens group 8 has a glass substrate 12.
A resin portion 16 is formed on the upper surface of the glass substrate 12. An IR cut coat 14 and a diaphragm 18a are formed between the glass substrate 12 and the resin portion 16. The resin portion 16 is composed of a convex lens portion 16a and a non-lens portion 16b at the periphery thereof, and these are integrally molded. The convex lens portion 16a has an aspheric surface. The stop 18a is covered with a non-lens portion 16b.
A resin portion 22 is formed on the lower surface of the glass substrate 12. An IR cut coat 20 and a diaphragm 18b are formed between the glass substrate 12 and the resin portion 22. The resin portion 22 is composed of a concave lens portion 22a and a non-lens portion 22b in the periphery thereof, and these are integrally molded. The concave lens portion 22a has an aspherical surface. The stop 18b is covered with a non-lens portion 22b.
The lens group 8 includes a glass substrate 12, IR cut coats 14 and 20, resin portions 16 and 22, and apertures 18a and 18b.

The lens group 10 has a glass substrate 30.
A resin portion 32 is formed on the upper surface of the glass substrate 30. The resin portion 32 is composed of a concave lens portion 32a and a non-lens portion 32b in the periphery thereof, and these are integrally molded. The concave lens portion 32a has an aspherical surface.
A resin portion 34 is formed on the lower surface of the glass substrate 30. A diaphragm 18 c is formed between the glass substrate 30 and the resin portion 34. The resin portion 34 is composed of a convex lens portion 34a and a non-lens portion 34b in the periphery thereof, and these are integrally molded. The convex lens portion 34a has an aspheric surface. The stop 18c is covered with a non-lens portion 34b.
The lens group 10 includes a glass substrate 30, resin portions 32 and 34, and a diaphragm 18c.

The resin parts 16 and 22 of the lens group 8 and the resin parts 32 and 34 of the lens group 10 are made of a known photocurable resin.
As the photocurable resin, for example, acrylic resins, allyl ester resins, epoxy resins, vinyl resins and the like as shown below can be used.
When acrylic resin, allyl ester resin, or vinyl resin is used, it can be cured by radical polymerization, and when epoxy resin is used, it can be cured by cationic polymerization.
The types of resins constituting each part of the lens groups 8 and 10 may be the same or different.
Details of the resin are as follows (1) to (4).

(1) Acrylic resin The (meth) acrylate used for the polymerization reaction is not particularly limited, and the following (meth) acrylate produced by a general production 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, alicyclic structure The (meth) acrylate which has is mentioned. One or more of these can be used.
In particular, (meth) acrylate having an alicyclic structure is preferable, and may be an alicyclic structure containing an oxygen atom or a nitrogen atom. For example, cyclohexyl (meth) acrylate, cyclopentyl (meth) acrylate, cycloheptyl (meth) acrylate, bicycloheptyl (meth) acrylate, tricyclodecyl (meth) acrylate, tricyclodecane dimethanol (meth) acrylate, isoboronyl (meth) ) Acrylates, di (meth) acrylates 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 Application Laid-Open No. 2002-193883), adamantyl di (meth) acrylate (Japanese Patent Application Laid-Open No. 57-5000785), diallyl adamantyl dicarboxylate (Japanese Patent Application Laid-Open No. 60-100537). ), Perfluoroadamantyl acrylate (JP 2004-123687), Shin-Nakamura Chemical 2-methyl-2-adamantyl methacrylate, 1,3-adamantanediol diacrylate, 1,3,5-adamantanetriol triacrylate, Saturated carboxylic acid adamantyl ester (JP 2000-119220), 3,3′-dialkoxycarbonyl-1,1 ′ biadamantane (see JP 2001-253835), 1,1′-biadamantane compound (US Patent) No. 3342880), Tet Curing having an adamantane skeleton having no aromatic ring such as adamantane (see JP-A-2006-169177), 2-alkyl-2-hydroxyadamantane, 2-alkyleneadamantane, di-tert-butyl 1,3-adamantanedicarboxylate Resin (see JP-A-2001-322950), bis (hydroxyphenyl) adamantanes and bis (glycidyloxyphenyl) adamantane (JP-A-11-3)
No. 5522 and JP-A-10-130371).
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 (Meth) acrylate.

(2) Allyl ester resin 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 not containing an aromatic ring (see JP 2003-66201 A), allyl (meth) acrylate (see JP 5-286896 A), allyl ester resin (JP 5-286896 A) , JP 2003-66201 A), a copolymer compound of an acrylate ester and an epoxy group-containing unsaturated compound (see JP 2003-128725 A), an acrylate compound (see JP 2003-147072 A), acrylic Examples include ester compounds (see JP 2005-2064 A).

(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 heat, and an acid anhydride, a cation generator, or the like can be used as a curing initiator. Epoxy resin is preferable in that it has a low cure shrinkage and can be a lens with excellent molding accuracy.
Examples of the epoxy 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 -Cyclopropanedicarboxylic acid bisglycidyl ester etc. can be mentioned.

(4) Vinyl-based resin The vinyl-based resin used in the polymerization reaction is not particularly limited as long as it is a product that forms a transparent resin composition by curing, and a vinyl-diameter resin manufactured by a general manufacturing method is used. can do.
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 include polyvinyl chloride, polystyrene and the like, and aromatic vinyl resins containing an aromatic group in R are particularly preferable. One or more vinyl groups may be contained in one molecule, and a divinyl resin having two or more vinyl groups is more preferable. These vinyl resins can be used alone or in combination of two or more.

  A hardening | curing agent is used when comprising curable resin material, and there is no limitation in particular. As the curing agent, an acid anhydride curing agent, a phenol curing agent, or the like can be preferably used. Specific examples of the acid anhydride curing agent include phthalic anhydride, maleic anhydride, trimellitic anhydride, pyromellitic anhydride, hexahydrophthalic anhydride, 3-methyl-hexahydrophthalic anhydride, 4-methyl-hexahydrophthalic anhydride. Examples thereof include an acid, a mixture of 3-methyl-hexahydrophthalic anhydride and 4-methyl-hexahydrophthalic anhydride, tetrahydrophthalic anhydride, nadic anhydride, methyl nadic anhydride and the like. Moreover, a hardening accelerator is contained as needed. The curing accelerator is not particularly limited as long as it has good curability, is not colored, and does not impair the transparency of the curable resin. For example, 2-ethyl-4-methylimidazole ( 2E4MZ) and other imidazoles, tertiary amines, quaternary ammonium salts, bicyclic amidines such as diazabicycloundecene and derivatives thereof, phosphines, phosphonium salts, and the like. You may mix and use a seed | species or more.

In the imaging lens 2, an adhesive is applied between the non-lens portion 22 b of the lens group 8 and the non-lens portion 32 b of the lens group 10, and the lens group 8 and the lens group 10 are bonded. In FIG. 1, the lens group 8 and the lens group 10 are illustrated as separated from each other, but may be directly bonded via an adhesive, and a spacer member (not illustrated) is interposed between the non-lens portion 22 b and the non-lens portion 32 b. It may be provided and bonded by an adhesive. The non-lens portions 22b and 32b correspond to the flange portions of the concave lens portions 22a and 32a.
A spacer 7 is bonded to the lens group 10 so as to be in contact with the non-lens portion 34 b, and is bonded to the upper surface of the optical low-pass filter 4 via the spacer 7. An opening 7a is formed in the spacer 7, and a convex lens portion 34a is disposed in the opening 7a.

In the imaging lens 2, each surface of the convex lens portion 16a, the concave lens portion 22a, the concave lens portion 32a, and the convex lens portion 34a has an aspherical shape, and the optical axes coincide with each other.
In particular, in the imaging lens 2, the convex lens portion 16a of the lens group 8 is disposed on the object side, and the convex lens portion 34a of the lens group 10 is disposed on the image side.
From the object side to the image side, the convex lens portion 16a defines the “S1 surface” that is the object-side optical surface of the lens group 8, and the concave lens portion 22a defines the “S2 surface” that is the image-side optical surface of the lens group 8. The portion 32a constitutes the “S3 surface” that is the object-side optical surface of the lens group 10, and the convex lens portion 34a constitutes the “S4 surface” that is the image-side optical surface of the lens group 10.

[Method for Manufacturing Imaging Module (Wafer Lens)]
Next, a method for manufacturing the imaging module 1 (including a method for manufacturing the wafer lens 51) will be briefly described.
First, IR cut coats 14 and 20 are formed on the glass substrate 12 as necessary. The IR cut coat is formed on each of the front and back surfaces of the glass substrate 12 using a known vacuum deposition method, sputtering, CVD (Chemical Vapor Deposition) method, or the like. The IR cut coat (infrared shielding film) is a film for shielding infrared rays, and has a transmittance of 50% or more for light with a wavelength of 365 nm.

  Next, for example, a light-shielding photoresist is applied to the glass substrate 12 and patterned into a predetermined shape to form a plurality of apertures 18a. The light-shielding photoresist can be used without any particular limitation, such as a photoresist in which carbon black is mixed into a resin or a metal photoresist.

Thereafter, a photocurable resin is dropped onto the mold, and one of the mold and the wafer-like glass substrate 12 is pressed against the other to fill the space between the mold and the glass substrate 12. The photocurable resin is cured by light irradiation. As a result, a plurality of convex lens portions 16a are formed on the glass substrate 12. Here, when the photocurable resin is an epoxy resin in particular, the reaction does not proceed completely even when irradiated with light, so that the glass substrate 12 is unlikely to warp when released.
Thereafter, the glass substrate 12 is turned over, and a plurality of apertures 18b and a plurality of concave lens portions 22a are formed on the glass substrate 12 in the same manner as described above. Details of the formation of the concave lens portion 22a will be described later.

After forming the lens portions 16a and 22a, the mold is released from the glass substrate 12. The mold release may be performed after the formation of the convex lens portion 16a and after the formation of the concave lens portion 22a, or may be performed collectively after the formation of the lens portions 16a and 22a on both sides. .
And after a mold release process, it post-cures and heat-processes with respect to the lens parts 16a and 22a of both surfaces of the glass substrate 12. FIG. Post-curing may be performed collectively for the lens portions 16a and 22a on both sides in a thermostatic bath, or may be performed for each lens portion after the lens portions 16a and 22a are released from each other. . Thus, the wafer lens 51 (refer FIG. 2, FIG. 3) which has several lens parts 16a and 22a is manufactured by releasing. Considering the suppression and efficiency of the warp of the wafer lens 51, the post cure is preferably performed collectively after the lens portions 16a and 22a are provided and released.

  Thereafter, in the same manner as the wafer lens 51 is manufactured, a plurality of apertures 18c, a plurality of concave lens portions 32a, and a convex lens portion 34a are formed on the glass substrate 30 and released. After the mold release, the above-mentioned post cure is performed. The glass substrate 30 may not be IR cut coated.

Further, it is preferable to form an antireflection film (not shown) on the resin portion 34 as necessary. As the antireflection film, a known configuration in which a plurality of layers having different refractive indexes can be employed, and at least a two-layer structure of a high refractive index layer and a low refractive index layer is provided. In the case of the two-layer structure, the first layer is formed directly on the resin portion 34, and the second layer is formed thereon.
In this case, the first layer may be a layer composed of a high refractive index material having a refractive index of 1.7 or more, preferably Ta ₂ O ₅ , a mixture of Ta ₂ O ₅ and TiO ₂ , ZrO ₂ , ZrO _2. And a mixture of TiO ₂ . The first layer may be composed of TiO ₂ , Nb ₂ O ₃ , and HfO ₂ .
The second layer is a layer made of a low refractive index material having a refractive index of less than 1.7, and is preferably made of SiO ₂ .

  The first layer and the second layer are formed by a technique such as vapor deposition in the antireflection film. Preferably, the first layer and the second layer are made of conductive materials such as solder whose film forming temperature is subjected to reflow processing. The paste is formed while being kept in the range of −40 to + 40 ° C. (preferably −20 to + 20 ° C.) with respect to the melting temperature of the adhesive paste.

  In the present embodiment, the first layer and the second layer may be alternately stacked on the first layer and the second layer, and the antireflection film may have a 2 to 7 layer structure as a whole. In this case, the layer that is in direct contact with the resin portion may be a high refractive index material layer (first layer) or a low refractive index material layer (second layer) depending on the type of resin. Here, the layer in direct contact with the resin portion is a layer of a high refractive index material.

Further, although the antireflection film is formed only on the surface of the resin portion 34, it may be formed on all surfaces of the resin portions 16, 22, 32, 34.
In order to suppress the occurrence of ghost in the image pickup device 6, it is effective to provide the antireflection film on the surface of the resin portion 34, and problems such as the generation of cracks at the interface between the antireflection film and the resin portion 34. In order to suppress this, it is preferable to provide an antireflection film only on the resin portion 34.
The antireflection film may be provided after performing the above-described post-cure process, or may be performed before the post-cure process.

  In this way, a wafer lens 52 (see FIG. 2) having a plurality of lens portions 32a and 34a is manufactured.

Thereafter, an adhesive is applied to at least one of the non-lens portions 22b and 32b to bond the wafer lenses 51 and 52 to each other (see FIG. 2). In FIG. 2, the non-lens portions 22 b and 32 b are illustrated as being separated from each other, but may be directly bonded via an adhesive, or may be bonded via a spacer (not illustrated). Also good.
Further, an adhesive is applied to at least one of the spacer 7 and the non-lens group 34b of the lens group 10 to bond the spacer 7 and the lens group 10 to each other.
As a result, the wafer lens laminate 50 is manufactured (see FIG. 2).

Thereafter, using a dicer or the like, as shown in FIG. 2, a set of convex lens portion 16a, concave lens portion 22a, concave lens portion 32a, and convex lens portion 34a is taken as a unit, and wafer lens laminate 50 is diced to each set. Cut (dicing) at 60 to fragment (dicing step).
As a result, a plurality of imaging lenses 2 are manufactured.
Here, the plurality of wafer lenses 51 and 52 are stacked to form the wafer lens stack 50, and then cut to form the imaging lens 2. However, when the imaging lens is composed of a single lens group, the wafer lenses are stacked. The imaging lens can be obtained by cutting without cutting.
When dicing the resin parts 16, 22, 32, and 34, for example, it is preferable to use a dicer that uses an endless blade (rotary blade) by cutting with abrasive grains, and the rotational speed of the endless blade is 3 to 7 mm / sec. .
When dicing the resin parts 16, 22, 32, 34, it is preferable to cut from the resin part 16 on the object side toward the resin part 34 on the image side. During dicing, the dust flies at the dicing portions of the resin portions 16, 22, 32, and 34. Therefore, the dicing portions are preferably cut while flowing (spouting) dust-proof pure water.

Thereafter, the imaging lens 2 is incorporated into (attached to) the casing (not shown), the optical low-pass filter 4 and the imaging element 6 are installed, and the imaging module 1 is manufactured.
In this embodiment, after the imaging lens 2 is manufactured by dicing, the optical low-pass filter 4 and the imaging element 6 are installed. However, the substrate on which the wafer lens stack 50 and the plurality of imaging elements 6 are provided. It is also possible to obtain the imaging module 1 by dicing after stacking.

  As an example of a method for manufacturing an electronic device, when the imaging module 1 and other electronic components are mounted on a printed wiring board, solder is placed on the printed wiring board in advance, and the imaging module 1 and the electronic components are placed there. By placing and heating in an IR reflow furnace after placement, the solder is melted and then cooled, so that the imaging module 1 and the electronic component can be simultaneously mounted on the printed wiring board.

Next, a method for forming the concave lens portion 22a of the wafer lens 51 will be described in detail.
When molding the concave lens portion 22a, a master 180, a sub master 200, and a sub sub master 230 as shown in FIG. 4 are used as a mold for molding.

(Master)
The master 180 has a plurality of convex portions 182 formed in an array with respect to a rectangular parallelepiped base portion. The convex part 182 is a part corresponding to the concave lens part 22a of the wafer lens 51, and is formed in a substantially hemispherical shape.
The master 180 is generally made of metal.
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, chromium / molybdenum steel, and stainless steel. Among them, plastic molds include pre-hardened steel, quenched and tempered steel, and aging treated steel. Examples of pre-hardened steel include SC, SCM, and SUS. There is PXZ in SC system. Examples of SCM systems 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 JP-A-2005-113161 and JP-A-2005-206913.
As the non-ferrous alloys, mainly copper alloys, aluminum alloys and zinc alloys are well known, for example, alloys shown in JP-A-10-219373 and JP-A-2000-176970.

The master 180 may be made of metallic 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.
Amorphous alloys include electroless or electrolytic nickel phosphorus plating, and have good machinability in diamond cutting.
These highly machinable materials may constitute the entire master 180, or may cover only the surface of the optical transfer surface, in particular, by a method such as plating or sputtering.

(Submaster)
The sub master 200 includes a sub master molding unit 202 and a sub master substrate 204. A plurality of recesses 206 are formed in the sub master molding portion 202 in an array. The surface (molding surface) shape of the concave portion 206 is a positive shape corresponding to the concave lens portion 22a in the wafer lens 51, and is concave in a substantially hemispherical shape in this figure.

The sub master molding part 202 is formed of a resin 208.
Examples of the resin 208 include a photo-curable resin, and the same acrylic resin, allyl ester resin, epoxy resin, vinyl resin, and the like as the resin parts 16, 22, 32, and 34 can be used. The resin 208 is preferably a resin having good releasability, particularly a transparent resin, and is preferably a resin that can be released without applying a release agent.

The sub master substrate 204 is made of a smooth material such as quartz, silicone wafer, metal, glass, or resin.
In consideration of transparency (light irradiation can be performed from above or below the sub master 200), the sub master substrate 204 is preferably made of quartz or glass.

(Sub-submaster)
The sub-sub master 230 includes a sub-sub master molding unit 232 and a sub-sub master substrate 234.
The sub-sub master molding part 232 is made of the same resin 238 as the resin 208 of the sub-master molding part 202 (may be different), and the sub-sub master board 234 is made of the same material as the sub-master board 204 (different) May be).
A plurality of convex portions 240 are formed on the surface of the sub-sub master substrate 234. For example, the plurality of convex portions 240 can be formed by etching or dropping the sub-sub-master substrate 234.

Here, the etching is a technique in which, for example, when the sub-submaster substrate 234 is a glass substrate, the glass substrate is chemically corroded and a desired pattern is engraved on the substrate. In addition to chemical etching using a photoresist and a 0.1 wt% hydrofluoric acid aqueous solution, dry processing such as sandblasting and microblasting is also available. In the present invention, any method may be used, and convex portions 240 having a height of 60 to 100 μm and a diameter of 0.4 to 0.8 mm are regularly formed on the sub-submaster substrate 234.
On the other hand, as a droplet, a glass molded body produced by press molding a glass material with a molding die is often used as an optical element for various optical devices. The glass molded body used as such an optical element is required to have an increasingly higher level as the optical product has been downsized and increased in accuracy in recent years. As one method for producing such a glass molded body, the molten glass droplet is dropped on a molding die held at a predetermined temperature lower than the temperature of the molten glass droplet, and the dropped molten glass droplet is cooled and solidified. There has been known a method of performing pressure molding with a molding die before (hereinafter, also referred to as “droplet molding method”) (see, for example, Japanese Patent Application Laid-Open Nos. 2007-186358 and 2002-234740). In the present invention, the convex portions 240 are regularly formed on the sub-submaster substrate 234 using this droplet forming method. Since the convex portion 240 is not the final optical element, high accuracy is not required. Therefore, it is only necessary to drop the molten glass in a regular arrangement on the glass substrate without using the upper mold and the lower mold, which are necessary in a normal droplet forming method.

In the sub-submaster molding portion 232, a plurality of convex portions 236 are formed in an array so as to cover the plurality of convex portions 240 formed on the sub-submaster substrate 234. The convex part 236 is a part corresponding to the concave lens part 22a of the wafer lens 51, and is formed in a substantially hemispherical shape.
Further, the light transmittance with respect to light with a wavelength of 365 nm when the thickness of the sub-submaster substrate 234 is 1 mm is 90% or more, and the light transmittance with respect to light with a wavelength of 365 nm when the thickness of the sub-submaster molding part 232 is 1 mm is 20%. ~ 80%.
Here, if the light transmittance of the sub-submaster substrate 234 is less than 90%, the substrate itself absorbs UV light, and even the convex substrate does not improve the surface accuracy of the concave lens, and the effect of the present invention is obtained. I can't. If the light transmittance of the sub-submaster molding part 232 is less than 20%, the sub-submaster absorbs almost no UV light, and the lens resin is not cured under desired conditions, and is an object of the present invention exceeding 80%. Although there is no variation in the accuracy of the lens surface, when the same resin material as that of the lens is used for the purpose of improving transferability from the resin molding portion of the mold to the lens surface, the transmittance is inevitably 80% or less. End up.

Next, a method for forming the concave lens portion 22a using the above-described master 180, sub master 200, and sub sub master 230 will be described.
As shown in FIG. 5 (a), the resin 208 is applied on the master 180, and as shown in FIG. 5 (b), the resin 208 is cured while pressing the glass substrate 204 from above, and the convex portion 182 of the master 180 is obtained. Is transferred to the resin 208, and a plurality of recesses 206 are formed in the resin 208. Thereby, the sub master molding part 202 is formed.

Thereafter, as shown in FIG. 5C, the sub master molding unit 202 and the sub master substrate 204 are released from the master 180, and the sub master 200 is manufactured.
Thereafter, as shown in FIG. 5 (d), a resin 238 is applied onto the sub master 200, and as shown in FIG. 5 (e), the sub-sub having a plurality of convex portions 240 with respect to the sub-sub master molding portion 232 from above. The resin 238 is cured while pressing the master substrate 234, the concave portion 206 of the sub master 200 is transferred to the resin 238, and a plurality of convex portions 236 are formed on the resin 238. Thereby, the sub-sub master molding part 232 is formed.

  As shown in FIG. 6 (f), the sub-submaster 230 is fabricated by releasing the sub-submaster molding part 232 and the sub-submaster substrate 234 from the submaster 200.

As shown in FIG. 6 (g), the convex portion 236 of the sub-submaster 230 is filled with resin 22A (resin constituting the resin portion 22), and the glass substrate 12 is pressed from above as shown in FIG. 6 (h). Then, the resin 22A is cured. As a result, the resin portion 22 (concave lens portion 22a) is formed from the resin 22A.
Thereafter, as shown in FIG. 6 (i), the resin part 22 and the glass substrate 12 are released from the sub-submaster 230.

  In addition, the resin part 16 of the other surface of the glass substrate 12 prepares a master (not shown) having a plurality of negative molding surfaces (concave parts) corresponding to the optical surface shape of the convex lens part 16a, and uses this master. Then, a sub master (not shown) having a positive molding surface (convex portion) is formed, and further, a sub sub master (not shown) having a negative molding surface (concave portion) is formed using this sub master. . Then, after filling resin (resin which comprises the resin part 16) between a sub submaster and the glass substrate 12, the said resin is hardened and the resin part 16 should just be shape | molded on the other surface of the glass substrate 12. FIG. In this way, the wafer lens 51 is manufactured.

  In the above embodiment, the concave lens portion 22a (resin portion 22) is molded using the master 180, the sub master 200, and the sub sub master 230. However, without using the sub sub master, the concave lens portion 22a (resin portion 22) is positive with respect to the concave lens portion 22a. From a master (not shown) having a (concave) shaped molded part, a submaster (not shown) having a negative (convex) shaped molded part may be molded, and the concave lens part 22a may be molded from the submaster. . In this case, a convex portion similar to the convex portion 240 is formed on the submaster substrate of the submaster, and the light transmittance with respect to light having a wavelength of 365 nm when the thickness of the submaster substrate is 1 mm is 90% or more. The light transmittance for light with a wavelength of 365 nm when the thickness of the master molded part is 1 mm is 20 to 80%.

Symbols used in this embodiment are as follows.
f: Focal length of the entire imaging lens system fB: Back focus F: F number 2Y: Diagonal length of the imaging surface of the solid-state imaging device ENTP: Entrance pupil position (distance from the first surface to the entrance pupil position)
EXTP: exit pupil position (distance from imaging surface to exit pupil position)
H1: Front principal point position (distance from the first surface to the front principal point position)
H2: Rear principal point position (distance from the final surface to the rear principal point position)
R: radius of curvature D: axial distance between surfaces Nd: refractive index of lens material with respect to d-line νd: Abbe number of lens material

  In this embodiment, the shape of the aspheric surface is such that the vertex curvature is C, the conic constant is K, the aspheric coefficient is A4, A6, A8, in an orthogonal coordinate system in which the vertex of the surface is the origin and the optical axis direction is the X axis. A10, A12, A14, and A16 are represented by “Equation 1”.

(1) Sample configuration <Samples 1 to 12>
Basically, the following imaging lens having the same configuration as that shown in FIG. 1 was prepared as a sample.
This imaging lens is assumed to be used for an imaging element having a 1/5 inch type, a pixel pitch of 1.75 μm, and 1600 × 1200 pixels.

Table 1 shows lens data of the imaging lens. In Table 1, a power of 10 (for example, 2.5 × 10 ⁻³ ) is represented using E (for example, 2.5 × E-3).

Presence / absence of convex part on the surface of the sub-submaster substrate (with convex part or flat), transmittance of the sub-submaster molding part, shape of the sub-submaster molding part (concave or convex), shape of the lens part (concave or convex), lens part With respect to the resin material, imaging lenses of “Samples 1 to 12” were produced according to the conditions shown in Table 2 below.
As the sub-submaster substrate, a glass substrate having a transmittance of 365 nm at t = 1 mm of 90% or more was used. Specifically, TEMPAX manufactured by Schott was used. Then, a convex portion having a height of 80 μm and a diameter of 0.6 mm was formed on the glass substrate having a thickness of 10 mm by the above-described etching or droplet.
Moreover, an epoxy resin or an acrylic resin was used as the resin material for the lens portion. Specifically, the epoxy resin used was 4% by mass of UVI-6992 manufactured by Dow Chemical Co. as a UV curing initiator added to hydrogenated bisphenol A type epoxy resin. As for the acrylic resin, 1 mass of IRGACURE907 manufactured by Ciba Vision Co., Ltd. is used as a UV curing initiator with respect to 2-alkyl-2-adamantyl- (meth) acrylate as a curable resin prepared according to the method disclosed in JP-A-2002-193883. % Added.
In Table 2, “A” and “B” in the column of “Transmittance of sub-submaster molding part” represent the types of sub-submaster molding parts. Here, two types of A and B are shown. I am using it.

(2) Evaluation of sample Here, it is assumed that there is a practical problem under the condition that the back focus (fB) of the imaging lens moves by 10 μm from the design value. The deviation of fB at that time is the design of the surface shape of the S1 surface. When the error PV value from the value fluctuates by 400 nm, fB fluctuates by −10 μm. When the error PV value from the design value of the surface shape of the S2 surface varies by 600 nm, fB varies by −10 μm. Based on this, the following evaluation was performed.
<Surface shape variation>
For the obtained “Samples 1 to 12” imaging lenses, the shape of the S1 surface (16a) or the S2 surface (22a) was measured with a Panasonic “UA3P” (ultra-high precision three-dimensional measuring device) to obtain a PV value. (The difference between the largest (Peak) and smallest (Valley) of the shape error from the design value of the sub-submaster is calculated and the initial value is called PV value). However, the results are as shown in Table 1 below.
PV value is less than 400 nm ... ◎
PV value is 400nm or more and less than 600nm.
PV value is 600nm or more and less than 3μm ・ ・ ・ △
PV value is 3μm or more ・ ・ ・ ×

  From the above results, Samples 3, 4, 9, and 10 produced using sub-submasters having a plurality of convex portions are compared to Samples 1, 2, 7, and 8 produced using flat sub-submasters. It can be seen that the surface transferability of the concave lens portion is excellent.

<Transmission deterioration of sub-submaster>
When the sub-submaster used in the manufacture of the imaging lenses of Samples 1 to 4 was repeatedly used, the life that can be used as a mold increased twice as much as the sub-submaster in Samples 3 and 4 compared to the sub-submaster in Samples 1 and 2 .
In addition, when the sub-submaster used in the manufacture of the imaging lenses of Samples 7 to 10 was repeatedly used, the lifetime that can be used as a mold was 2.5 for the sub-submasters of Samples 9 and 10 and 2.5 for the sub-submasters of Samples 7 and 8. Doubled.

DESCRIPTION OF SYMBOLS 1 Imaging module 2 Imaging lens 4 Optical low-pass filter 6 Imaging element 7 Spacer 8, 10 Lens group 9 Carbon dioxide cleaning apparatus 12 Glass substrate (lens substrate)
14 IR cut coat 16 Resin part 16a Convex lens part 16b Non lens part 18a, 18b, 18c Aperture 20 IR cut coat 22 Resin part 22A Resin 22a Concave lens part 22b Non lens part 30 Glass substrate 32 Resin part 32a Concave lens part 32b Non lens part 34 Resin part 34a Convex lens part 34b Non-lens part 50 Wafer lens laminate 51, 52 Wafer lens 60 Dicing line 180 Master 182 Convex part 200 Sub master 202 Sub master molding part 204 Sub master substrate 206 Concave part 208 Resin 230 Sub sub master (for wafer lens) Mold)
232 Sub-sub master molding part (resin molding part)
234 Sub-submaster substrate (molding die substrate)
236 Convex part 238 Resin 240 Convex part

Claims (4)

A wafer lens mold for molding a wafer lens in which a plurality of concave lenses made of a photocurable resin is formed on at least one surface of a lens substrate,
A mold substrate having a plurality of convex portions formed on one surface;
A negative-shaped resin molding portion formed on the one surface of the mold substrate so as to cover the plurality of convex portions, and corresponding to the optical surface shape of the concave lens portion,
The light transmittance for light having a wavelength of 365 nm when the thickness of the mold substrate is 1 mm is 90% or more, and the light transmittance for light having a wavelength of 365 nm when the thickness of the resin molding portion is 1 mm is 20 to 20%. A mold for a wafer lens, characterized by being 80%. A method for producing a wafer lens mold for molding a wafer lens having a plurality of photo-curing resin concave lens portions formed on at least one surface of a lens substrate,
A plurality of convex portions are formed on one surface of the mold substrate,
On the one surface of the mold substrate, a negative resin molding portion corresponding to the optical surface shape of the concave lens portion is formed so as to cover the plurality of convex portions,
The light transmittance for light having a wavelength of 365 nm when the thickness of the mold substrate is 1 mm is 90% or more, and the light transmittance for light having a wavelength of 365 nm when the thickness of the resin molding portion is 1 mm is 20 to 20%. 80. A method for producing a wafer lens mold, characterized by being 80%.   The method for producing a wafer lens mold according to claim 2, wherein the plurality of convex portions are formed by etching the one surface of the mold substrate. The plurality of convex portions is formed by dropping a droplet obtained by melting the same material as the molding die substrate onto the one surface of the molding die substrate and performing pressure molding before cooling and solidifying the droplet. The method for producing a wafer lens mold according to claim 2, wherein:

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