WO2011055623A1 - Image pickup lens, image pickup device, and method for manufacturing electronic apparatus - Google Patents

Abstract

Disclosed is an image pickup lens wherein generation of cracks and wrinkles in a reflection preventing film is eliminated, and entry of unnecessary reflected light into an image pickup element is suppressed, said entry of unnecessary reflected light being the cause of ghost. The image pickup lens (2) has the following disposed therein, in the following order from the object side to the image side: a first lens group (8), which has a glass substrate (12), a resin convex lens section (16a) configuring the surface (S1), i. e., the object side optical surface, and a resin concave lens section (22a) configuring the surface (S2), i. e., the image side optical surface; a second lens group (10), which has a glass substrate (30), a resin concave lens section (32a) configuring the surface (S3), i.e., the object side optical surface, and a resin convex lens section (34a) configuring the surface (S4), i. e., an image side optical surface. In the image pickup lens (2), the reflection preventing film (36) is formed at least on the surface (S4), and at least the concave lens section (34a) is configured of a resin wherein inorganic particles are dispersed.

Description

Imaging lens, imaging apparatus, and electronic device manufacturing method

The present invention relates to an imaging lens, an imaging device, and an electronic device manufacturing method.

2. Description of the Related Art Conventionally, an imaging device called a camera module has been mounted on a portable terminal which is a compact and thin electronic device such as a mobile phone or a PDA (Personal Digital Assistant). In addition to this, image information can be transmitted mutually.

As an image pickup device used in these image pickup devices, a solid-state image pickup device such as a CMOS (Complementary Metal Oxide Semiconductor) type image sensor is used. As an imaging lens, a resin lens that can be mass-produced at low cost and can be easily added with an aspheric surface is used for cost reduction and size reduction. An imaging apparatus is configured by combining such an imaging element and an imaging lens.

In recent portable terminals, a reflow soldering process is employed as a method for mounting an imaging device on which an imaging lens is mounted on a printed wiring board. In the reflow process, solder is placed in advance on the printed circuit board where electronic components are to be placed, the electronic components are placed thereon, heated to melt the solder, and then cooled to cool the electronic components. It mounts on a printed wiring board (for example, refer patent document 1). Electronic components are automatically mounted inside the furnace for the reflow process. By adopting such a reflow process, the mounting cost of components on a printed wiring board is low, and it has become possible to maintain a constant manufacturing quality, so the imaging lens has excellent heat resistance that can withstand the reflow process. Is required.

One of the manufacturing methods for imaging lenses with mass productivity, miniaturization, and high heat resistance is that a large number of lens parts made of high heat-resistant curable resin are simultaneously formed on a parallel plate of several inches of glass substrate. There is a replica method to form. A method has been proposed in which a large number of lens elements are simultaneously molded using a replica method, a glass substrate (wafer lens) on which a large number of these lens elements are formed is combined with a sensor wafer and then separated to mass-produce camera modules.

In such an imaging apparatus, in order to further improve optical performance such as light collection performance and chromatic aberration correction, a wafer lens having lens portions provided on both surfaces of at least two glass substrates is used as an imaging lens. Technology is being considered. According to such an imaging lens, for example, the lens unit provided closest to the object side is a lens unit having positive power, and the second or third lens unit viewed from the object side is negative. Excellent focusing performance and chromatic aberration correction by making the lens part with power different from the Abbe number of the object side lens part with positive power and the second or third lens part with negative power Can have a function.

Although it is possible to improve the optical performance by combining the imaging lens with a plurality of wafer lenses as described above, such an imaging device is mounted on a wiring board by reflow soldering processing. , A new problem to be solved has occurred.

In the imaging apparatus, reflected light is generated at the interface between the lens unit and the air layer or at the interface between the imaging element and the air layer. For example, in an imaging lens in which a lens portion is provided on each surface of two glass substrates and laminated, the first lens portion, the second lens portion, the third lens portion, and the fourth lens portion are formed from the object side. In this case, reflected light is generated on the optical surfaces and imaging device surfaces of the first lens unit and the third lens unit, respectively.

In this case, since the reflected light generated on the surface of the first lens unit does not enter the image sensor, the reflected light generated on the surface of the third lens unit hardly affects the image, and the second lens is again used. Although it is reflected by the light and emitted in the image side direction (image pickup device direction), it does not directly enter the image pickup device, so the influence is slight.

However, the reflected light generated on the surface of the image sensor is reflected on the surface of the fourth lens part and is incident on the surface of the image sensor again, thereby forming a ghost and increasing the influence on the image.

As one means for preventing such reflection of light, a method of forming an antireflection film on the lens surface can be considered. However, the antireflection film is usually formed by laminating an inorganic layer such as a metal oxide layer, and since the coefficient of linear expansion is significantly different from that of the resin used as the base material, high-temperature heat treatment such as reflow soldering treatment However, since the optical performance deteriorates due to the problem that cracks or wrinkles occur in the antireflection film, it is difficult to form the antireflection film on the resin lens portion.

In order to solve the above-described problems, a technique for performing a film forming temperature in an appropriate temperature range with respect to a reflow temperature when an antireflection film is formed by vapor deposition has been studied. It was possible to suppress the occurrence of cracks in the antireflection film to some extent (see, for example, Patent Document 2).

JP 2001-24320 A JP 2009-244583 A

However, adjusting the deposition temperature of the antireflection film as in the technique of Patent Document 2 is not sufficient to suppress the occurrence of cracks. The lens part of the lens may expand and contract, and wrinkles may occur in the antireflection film.

On the other hand, when the antireflection film is not formed, the problem of the ghost caused by the reflected light on the surface of the image sensor cannot be solved, and improvement has been desired.

Therefore, the main object of the present invention is to suppress the occurrence of ghosts due to reflected light on the surface of the image sensor, and to reflect even when exposed to high heat such as reflow soldering processing or due to temperature fluctuations during use. An object of the present invention is to provide an imaging lens capable of preventing optical performance from being deteriorated due to cracks and wrinkles in a prevention film.

In order to solve the above problems, according to the present invention,
A first glass substrate,
A resin-made first lens portion that is disposed on the object-side surface of the first glass substrate and constitutes an S1 surface that is an object-side optical surface; and
A first lens group that is disposed on the image side surface of the first glass substrate and has a second lens portion made of a resin that constitutes an S2 surface that is an image side optical surface;
A second glass substrate,
A resin-made third lens portion that is disposed on the object-side surface of the second glass substrate and forms an S3 surface that is an object-side optical surface; and
A second lens group that is disposed on the image side surface of the second glass substrate and has a resin-made fourth lens portion that forms the S4 surface that is an image side optical surface is disposed in this order from the object side to the image side. An imaging lens,
An antireflection film is formed on at least the S4 surface,
At least the fourth lens portion is formed of a resin in which inorganic particles are dispersed, and an imaging lens is provided.

According to the present invention, since the antireflection film is provided on the S4 surface, that is, the optical surface of the fourth lens unit, the reflected light reflected by the surface of the imaging element is transmitted to the object side through the S4 surface, It is possible to suppress the generation of ghosts that are generated by entering the image sensor again.

In addition, by configuring the fourth lens portion with a resin in which inorganic particles are dispersed, the inorganic particles generally have a lower linear expansion coefficient than the resin material, and reduce the difference in the linear expansion coefficient from the antireflection film. Therefore, even when the imaging lens is placed in a high temperature environment by the reflow soldering process, the occurrence of cracks and wrinkles in the antireflection film can be prevented.

It is sectional drawing which shows schematic structure of an imaging device and the imaging lens used for it. It is drawing which shows the modification of FIG. 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 the lens for imaging.

Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings.

As shown in FIG. 1, the imaging device 1 includes an imaging lens 2, an optical low-pass filter 4, an imaging element 6, and the like, and the optical low-pass filter 4 and the imaging element 6 are disposed below the imaging lens 2. ing. For example, a CMOS type image sensor is used as the image sensor 6.

The imaging lens 2 is composed of two lens groups 8 and 10.

The first lens group 8 has a glass substrate 12. A resin portion 16 is formed on the upper surface of the glass substrate 12. A diaphragm 18 is 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 and has a positive refractive power. The diaphragm 18 is covered with a non-lens portion 16b.

A resin portion 22 is formed on the lower surface of the glass substrate 12. 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 and has negative refractive power (power).

The first lens group 8 is composed of a glass substrate 12, resin portions 16 and 22, and a diaphragm 18, and has a positive refractive power as a whole.

The second 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 aspheric surface, and has negative refractive power.

A resin portion 34 is formed on the lower surface of the glass substrate 30. 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 and has a positive refractive power.

The second lens group 10 includes a glass substrate 30 and resin portions 32 and 34, and has a negative refractive power (power) as a whole.

In the above description, the second lens unit and the third lens unit have negative power, but at least one lens unit may have negative power.

The resin parts 16 and 22 of the first lens group 8 and the resin parts 32 and 34 of the second lens group 10 are made of a known photocurable resin. As the photocurable resin, for example, acrylic resins, allyl ester resins, epoxy resins and the like as shown below can be used.

When acrylic resin or allyl ester resin is used, it can be cured by reaction by radical polymerization, and when epoxy resin is used, it can be cured by reaction by cationic polymerization.

The types of resins constituting each part of the first and second lens groups 8 and 10 may be the same or different. Details of the resin are as follows (1) to (3).

(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.

(Meth) acrylate having an alicyclic structure is particularly 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) ) 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 (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. 60-60) No. 100537), perfluoroadamantyl acrylate (JP 2004-123687), Shin-Nakamura Chemical Co., Ltd. 2-methyl-2-adamantyl methacrylate, 1,3-adamantanediol diacrylate, 1,3,5-adamantane Triol triacrylate, unsaturated carboxylic acid adamantyl ester (JP 2000-119220 A), 3,3′-dialkoxycarbonyl-1,1 ′ biadamantane (JP 2001-253835 A), 1,1′- Biadamantane compounds U.S. Pat. No. 3,342,880), tetraadamantane (Japanese Patent Laid-Open No. 2006-169177), 2-alkyl-2-hydroxyadamantane, 2-alkyleneadamantane, 1,3-adamantane dicarboxylate di-tert-butyl and the like Curable resins having an adamantane skeleton having no ring (Japanese Patent Laid-Open No. 2001-322950), bis (hydroxyphenyl) adamantanes and bis (glycidyloxyphenyl) adamantanes (Japanese Patent Laid-Open Nos. 11-35522 and 10-130371) No. gazette).

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 And tri (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 (Japanese Patent Laid-Open No. 2003-66201), allyl (meth) acrylate (Japanese Patent Laid-Open No. 5-286896), allyl ester resin (Japanese Patent Laid-Open No. 5-286896), No. 2003-66201), a copolymer compound of an acrylate ester and an epoxy group-containing unsaturated compound (JP-A 2003-128725), an acrylate compound (JP-A 2003-147072), an acrylic ester compound (JP-A No. 2005-2064).

(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 and the like.

The curing agent is used for constituting the curable resin material and is not particularly limited. Moreover, in this invention, when comparing the transmittance | permeability of the curable resin material and the optical material after adding an additive, a hardening | curing agent shall not be contained in an additive. As the curing agent, an acid anhydride curing agent, a phenol curing agent, or the like can be preferably used. Specific examples of acid anhydride curing agents 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, and methyl nadic anhydride.

Moreover, a curing accelerator is contained as necessary. 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 thermosetting resin. For example, 2-ethyl-4-methylimidazole is not limited. Imidazoles such as (2E4MZ), tertiary amines, quaternary ammonium salts, bicyclic amidines such as diazabicycloundecene and their derivatives, phosphines, phosphonium salts, etc. can be used, Two or more kinds may be mixed and used.

In the imaging lens 2, an adhesive is applied between the non-lens portion 22 b of the first lens group 8 and the non-lens portion 32 b of the second lens group 10, and the first lens group 8 and the second lens group 10 are connected. It is glued. The non-lens portions 22b and 32b correspond to the flange portions of the concave lens portions 22a and 32a.

In the present embodiment, the non-lens portion 22b and the non-lens portion 32b are directly bonded via an adhesive, but a separate spacer is provided between the resin portion 22 and the resin portion 32, and the spacer You may adhere | attach through.

In the imaging lens 2, the convex lens portion 16a, the concave lens portion 22a, the concave lens portion 32a, and the convex lens portion 34a have aspherical surfaces, and the optical axes coincide with each other. In particular, in the imaging lens 2, the convex lens portion 16a of the first lens group 8 is disposed on the object side, and the convex lens portion 34a of the second lens group 10 is disposed on the image side.

From the object side to the image side, the convex lens portion 16a (first lens portion) is the “S1 surface” that is the object-side optical surface of the first lens group 8, and the concave lens portion 22a (second lens portion) is the first lens. The “S2 surface” that is the image side optical surface of the group 8 is used, and the “S3 surface” that is the object side optical surface of the second lens group 10 is the “S3 surface” that is the concave lens portion 32a (the fourth lens). Part) constitutes the “S4 surface” which is the image side optical surface of the second lens group 10.

Subsequently, a method for manufacturing the imaging device 1 (including a method for manufacturing the imaging lens 2) will be briefly described.

First, 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 18. As the light shielding photoresist, a photoresist mixed with carbon black can be used.

Thereafter, a photocurable resin is dropped on the mold, and one of the mold and the wafer-shaped glass substrate 12 is pressed against the other to fill the space between the mold and the glass substrate 12 with the photocurable resin. 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.

Next, the glass substrate 12 is turned over, and a plurality of concave lens portions 22a are formed on the glass substrate 12 in the same manner as described above.

When forming the IR cut coats 14 and 20, before forming the aperture 18, a known vacuum deposition method, sputtering, CVD (Chemical Vapor Deposition) method or the like is used for each of the front and back surfaces of the glass substrate 12. IR cut coats 14 and 20 are formed (see FIG. 2).

Thereafter, a plurality of concave lens portions 32a and convex lens portions 34a are formed on the glass substrate 30 in the same manner as the plurality of convex lens portions 16a and concave lens portions 22a are formed on the glass substrate 12. In the case of forming the convex lens portion 34a, a photocurable resin containing inorganic particles is used.

Subsequently, an antireflection film 36 is formed on the resin portion 34. The second lens group 10 (second lens group 10 without the antireflection film 36) is mounted in the vacuum deposition apparatus, and the pressure in the apparatus is reduced to a predetermined pressure (for example, 2 × 10 ⁻³ Pa), The second lens group 10 is heated by a heater at the upper part of the vacuum evaporation apparatus until the temperature reaches a predetermined temperature (for example, 240 ° C.).

Thereafter, the first layer 36a is formed by using a vapor deposition source constituting the first layer 36a. In this case, the film forming temperature is preferably kept within a range of −40 to + 40 ° C. with respect to the melting temperature of the conductive paste to be melted by the reflow process.

For example, when a (Ta ₂ O ₅ + 5% TiO ₂ ) film is formed as the first layer 36a, OA600 manufactured by Optran Co., Ltd. may be used as the evaporation source, and the evaporation source may be evaporated by electron gun heating. During vapor deposition, it is preferable to form a film while introducing O ₂ gas up to a pressure of 1.0 × 10 ⁻² Pa inside the vacuum vapor deposition apparatus and controlling the vapor deposition rate at 5 Å / sec. When the melting temperature of the conductive paste to be melted by the reflow process is 240 ° C., for example, the film forming temperature (temperature in the vapor deposition apparatus) is maintained within the range of 200 to 280 ° C.

Then, following the first layer 36a, the second layer 36b is formed using a vapor deposition source constituting the second layer 36b. Also in this case, preferably, as in the case of forming the first layer 36a, the film forming temperature is kept within the range of −40 to + 40 ° C. with respect to the melting temperature of the conductive paste to be melted by the reflow process. .

For example, when an SiO ₂ film is formed as the second layer 36b, O ₂ gas is introduced up to a pressure of 1.0 × 10 ⁻² Pa inside the vacuum vapor deposition apparatus, and the vapor deposition rate is set to 5 Å / sec. It is better to deposit while controlling. When the melting temperature of the conductive paste to be melted by the reflow process is 240 ° C., for example, the film forming temperature (temperature in the vapor deposition apparatus) is maintained within the range of 200 to 280 ° C.

Thereafter, an adhesive is applied to at least one of the non-lens portions 22b and 32b, and the lens groups 8 and 10 are bonded to each other to manufacture the wafer lens laminate 50 (see FIG. 3).

Finally, using a dicer or the like, as shown in FIG. 3, 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 for each set. Cut (dicing) at line 60 and fragment. As a result, a plurality of imaging lenses 2 are manufactured.

When dicing the resin parts 16, 22, 32, 34, for example, it is preferable to use a dicer that uses an endless blade (rotary blade) by cutting with abrasive grains, and the rotation 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 portion is preferably cut while flowing pure water for dust prevention (jetting).

Thereafter, the imaging lens 2 is assembled and bonded to the casing (not shown), and the optical low-pass filter 4 and the imaging element 6 are installed, whereby the imaging device 1 is manufactured.

In the present embodiment, the optical low-pass filter 4 and the image sensor 6 are installed after the imaging lens 2 is manufactured by dicing. However, the wafer lens stack 50 and the plurality of image sensors 6 are provided. It is also possible to obtain the imaging device 1 by dicing after stacking the substrates.

As an example of a method for manufacturing an electronic device, when the imaging device 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 device 1 and the electronic component 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 device 1 and the electronic component can be simultaneously mounted on the printed wiring board.

As shown in the enlarged portion in FIG. 1, in the present embodiment, an antireflection film 36 is formed on the surface of the resin portion 34. Here, the antireflection film 36 is provided only on the surface of the resin portion 34, but may be provided on all surfaces of the resin portions 16, 22, 32, 34.

The antireflection film 36 is effectively provided on the surface of the resin portion 34 in order to suppress the occurrence of ghost in the image pickup device 6 which is one of the objects of the present invention, and the antireflection film 36 and the resin portion 34 are effective. It is preferable to provide the antireflection film 36 only on the resin part 34 containing inorganic particles in order to suppress problems such as the generation of cracks at the interface with the resin.

The antireflection film 36 has a two-layer structure. A first layer 36a is formed directly on the resin portion 34, and a second layer 36b is formed thereon.

The first layer 36a is a layer made of a high refractive index material having a refractive index of 1.7 or more, and is preferably a mixture of Ta ₂ O ₅ , Ta ₂ O ₅ and TiO ₂ , ZrO ₂ , ZrO ₂ and TiO _2. And is composed of any mixture. The first layer 36a may be composed of TiO ₂ , Nb ₂ O ₃ , and HfO ₂ .

The second layer 36b is a layer comprised of a low refractive index material is less than the refractive index of 1.7, preferably composed of SiO _2.

The antireflection film 36 has both the first layer 36a and the second layer 36b formed by a technique such as vapor deposition. Preferably, the film formation temperatures of the first layer 36a and the second layer 36b are subjected to a reflow process. It 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 conductive paste such as solder.

In the imaging device 1, the first layer 36a and the second layer 36b may be alternately stacked on the first layer 36a and the second layer 36b, and the antireflection film 36 may have a 2-7 layer structure as a whole.

In this case, the layer in direct contact with the resin portion 34 may be a high refractive index material layer (first layer 36a) or a low refractive index material layer (second layer 36b) depending on the type of resin. Good. Here, the layer in direct contact with the resin portion 34 is a layer of a high refractive index material.

In the present embodiment, among the four resin portions 16, 22, 32, 34, a photocurable resin containing inorganic particles is used in the resin portion 34 closest to the image side.

Inorganic particles may be contained not only in the resin part 34 but also in the resin parts 16, 22, 32. However, it is preferable to include inorganic particles only in the resin parts 22, 32, 34, more preferably to include inorganic particles only in the resin parts 32, 34, and most preferable to include inorganic particles only in the resin part 34. preferable.

The reason is as follows. That is, as described above, when the imaging lens 2 is manufactured, the wafer lens stack 50 needs to be cut by dicing. During dicing, dust is generated in the vicinity of the cut portion, and therefore it is preferable to cut while flowing pure water for dust prevention. At that time, if the resin parts 16, 22, 32, and 34 contain inorganic particles, the water absorption may increase due to the inorganic particles. When the imaging lens 2 is manufactured, dicing may be performed in a state of being bonded to the imaging element (group) in the state of the wafer lens stack 50, and therefore dicing is performed from the object side (resin portion 16 side). Since pure water is jetted from the resin part 16 side, the resin part on the object side is exposed to pure water for a longer time. When a resin containing inorganic particles is exposed to pure water for a long time, expansion due to water absorption occurs, and problems such as peeling from the glass substrates 12 and 30 may occur. It is preferable to use a resin that does not contain inorganic particles in the resin portion.

In addition, when inorganic particles are contained in the resin, the toughness may be decreased and brittleness may be increased, and it is easy to break in the course of the dicing process. .

In addition, the resin portions 22 and 32 are preferably concave lenses. In this case, the non-lens portions ( non-lens portions 22b and 32b) are thicker than the lens portions ( concave lens portions 22a and 32a). There is a high possibility that it will continue to be received for a long time, and it will be easier to break.

Therefore, it is preferable to use a resin containing inorganic particles only in the resin portion 34. Since at least the resin portion 34 is provided with an antireflection film 36 in order to suppress the occurrence of ghost caused by the reflected light entering the image sensor 6, cracks due to stress between the antireflection film and the resin portion are generated. In order to suppress, the resin part 34 needs to use resin containing inorganic particles.

According to the above embodiment, since the resin part 34 arranged closest to the image among the resin parts 16, 22, 32, 34 of the imaging lens 1 contains inorganic particles, the resin part 34. Has a lower linear expansion coefficient (thermal expansion coefficient) than the other resin parts 16, 22, 32. Therefore, even when the resin of the convex lens portion 34a is subjected to a high temperature, expansion and contraction of the resin can be suppressed, and cracks and wrinkles can be prevented from occurring in the antireflection film 36.

The inorganic particles that can be contained / dispersed in the resin parts 16, 22, 32, and 34 are optically transparent (having optical transparency), such as oxide particles, sulfide particles, and selenide particles. And telluride particles.

More specifically, for example, silicon oxide particles, aluminum oxide particles, aluminum phosphate particles, titanium oxide particles, zinc oxide particles, zinc sulfide particles, etc. can be mentioned, preferably silicon oxide particles (silica particles), carbonic acid Calcium particles. As these particles, one kind of inorganic particles may be used, or a plurality of kinds of inorganic particles may be used in combination.

The mixing ratio of inorganic particles to the photocurable resin (volume ratio of inorganic particles in the composite material) is 1 to 50% by volume, preferably 10 to 40% by volume, more preferably 20 to 30% by volume. .

The shape of the inorganic particles may be any shape such as a spherical shape, an elliptical shape, a flat shape, or a rod shape, but the lens function can be effectively exhibited particularly when it is spherical.

The particle size distribution is not particularly limited, but in order to exhibit the lens function more efficiently, those having a relatively narrow distribution are preferably used rather than those having a wide distribution.

Inorganic particles having an average particle diameter of 1 to 30 nm are used. The inorganic particles preferably have an average particle diameter of 1 to 20 nm, more preferably 1 to 10 nm. If the average particle size is less than 1 nm, it may be difficult to disperse the inorganic particles, so that the desired performance may not be obtained. If the average particle size exceeds 30 nm, the resulting composite material becomes turbid and transparent. The light transmittance may be less than 70%.

The average particle diameter of the inorganic particles represents the diameter when the volume of the inorganic particles is converted into a sphere. As for the number of particles to be measured, 100 or more particles of an electron micrograph of inorganic particles are selected indiscriminately, and the arithmetic average of the particle sizes of the individual inorganic particles is defined as the average particle size.

The method for producing the inorganic particles is not particularly limited, and any known method can be used. For example, methods such as thermal decomposition of metal salts and hydrolysis of metal salts and metal alkoxides are well known. The thermal decomposition of the metal salt can be obtained by spraying the metal salt or a solution thereof and thermally decomposing it. The hydrolysis of the metal salt or metal alkoxide can be obtained by preparing a metal salt or metal alkoxide solution in advance and adding water to the solution to advance hydrolysis polymerization.

The surface of inorganic particles is preferably surface-treated. The method for surface treatment is not particularly limited, and any known method can be used.

Examples of the surface treatment agent used for the surface treatment of inorganic particles include tetramethoxysilane, tetraethoxysilane, tetraisopropoxysilane, tetraphenoxysilane, methyltrimethoxysilane, ethyltrimethoxysilane, propyltrimethoxysilane, and methyltriethoxy. Silane, methyltriphenoxysilane, ethyltriethoxysilane, phenyltrimethoxysilane, 3-methylphenyltrimethoxysilane, dimethyldimethoxysilane, diethyldiethoxysilane, diphenyldimethoxysilane, diphenyldiphenoxysilane, trimethylmethoxysilane, triethylethoxysilane , Triphenylmethoxysilane, triphenylphenoxysilane, cyclopentyltrimethoxysilane, cyclohexyltriethoxysilane, Dildimethylethoxysilane, octyltriethoxysilane, vinyltriacetoxysilane, vinyltrichlorosilane, vinyltriethoxysilane, γ-chloropropyltrimethoxysilane, γ-chloropropylmethyldichlorosilane, γ-chloropropylmethyldimethoxysilane, γ- Chloropropylmethyldiethoxysilane, γ-aminopropyltriethoxysilane, N- (β-aminoethyl) -γ-aminopropyltrimethoxysilane, N- (β-aminoethyl) -γ-aminopropylmethyldimethoxysilane, γ -Mercaptopropyltrimethoxysilane, γ-mercaptopropylmethyldimethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropylmethyldimethoxysilane, γ-methacryloxypropylto Methoxysilane, γ-methacryloxypropylmethyldimethoxysilane, γ- (2-aminoethyl) aminopropyltrimethoxysilane, γ-isocyanatopropyltriethoxysilane, γ- (2-aminoethyl) aminopropylmethyldimethoxysilane, γ- Anilinopropyltrimethoxysilane, vinyltrimethoxysilane, N-β- (N-vinylbenzylaminoethyl) -γ-aminopropyltrimethoxysilane / hydrochloride, aminosilane compound and the like, and in place of silane Aluminum, titanium, zirconia, or the like can also be used, and in this case, for example, aluminum triethoxide, aluminum triisoproxide, or the like.

Also, fatty acids such as isostearic acid, stearic acid, cyclopropane carboxylic acid, cyclohexane carboxylic acid, cyclopentane carboxylic acid, cyclohexane propionic acid, octylic acid, palmitic acid, behenic acid, undecylenic acid, oleic acid, hexahydrophthalic acid and the like Any surface treatment agent such as a metal salt of the above, or an organic phosphate surface treatment agent can be used, and these can be used alone or in admixture of two or more.

These compounds have different characteristics such as reaction rate, and compounds suitable for surface treatment conditions can be used. Further, only one type may be used or a plurality of types may be used in combination. Furthermore, the properties of the surface-treated fine particles obtained may vary depending on the compound used, and the affinity with the photocurable resin used to obtain the composite material can be achieved by selecting the compound used for the surface treatment. is there.

The ratio of the surface treatment agent is not particularly limited, but is preferably 10 to 99% by mass, more preferably 30 to 98% by mass with respect to the inorganic particles after the surface treatment.

When the resin parts 16, 22, 32, and 34 contain inorganic particles, the organic-inorganic composite material may be prepared (produced) as follows.

The organic-inorganic composite material may be prepared by adding and kneading inorganic particles to the molten photocurable resin, or after mixing the photocurable resin and inorganic particles dissolved in a solvent. It may be produced by removing the organic solvent.

In this embodiment, it is desirable that the organic-inorganic composite material is produced by a melt-kneading method. Although it is possible to polymerize a photocurable resin in the presence of inorganic particles or to produce inorganic particles in the presence of a photocurable resin, there are special conditions for polymerization of the photocurable resin and preparation of inorganic particles. Because it becomes necessary.

In the melt-kneading method, since an organic-inorganic composite material can be prepared by mixing a photocurable resin or inorganic particles prepared by an existing method, it is usually possible to produce an inexpensive organic-inorganic composite material.

In the melt kneading, an organic solvent can be used. By using an organic solvent, the temperature of melt kneading can be lowered, and deterioration of the photocurable resin can be easily suppressed. In this case, it is preferable to devolatilize after melt-kneading to remove the organic solvent from the organic-inorganic composite material.

Examples of the apparatus that can be used for melt kneading include a closed kneading apparatus such as a lab plast mill, a Brabender, a Banbury mixer, a kneader, and a roll, or a batch kneading apparatus. Further, a continuous melt kneader such as a single screw extruder or a twin screw extruder can be used.

As a mixing method of the inorganic particles after the treatment and the photocurable resin, as a specific kneader, KRC kneader (manufactured by Kurimoto Iron Works), polylab system (manufactured by HAAKE), nanocon mixer (Toyo Seiki Seisakusho) ), Nauta Mixer Bus Co. Kneader (Buss), TEM extruder (Toshiba Machine), TEX twin-screw kneader (Nihon Steel Works), PCM kneader (Ikegai Iron Works) ), Three roll mill, mixing roll mill, kneader (manufactured by Inoue Mfg. Co., Ltd.), kneedex (manufactured by Mitsui Mining Co., Ltd.), MS-type pressure kneader, nider ruder (manufactured by Moriyama Mfg. Co., Ltd.), Banbury mixer (manufactured by Kobe Steel) Is mentioned.

In the method for producing an organic-inorganic composite material, when melt kneading is used, the photocurable resin and the inorganic particles may be added and kneaded all at once, or may be added in stages and kneaded. In this case, in a melt-kneading apparatus such as an extruder, it is possible to add the components to be added step by step from the middle of the cylinder.

In the case of compounding by melt kneading, the inorganic particles can be added in a powder or agglomerated state, or can be added in a dispersed state in the liquid. When adding in the state disperse | distributed in the liquid, it is preferable to perform devolatilization after kneading | mixing.

As shown in the modification of FIG. 2, IR cut coats 14 and 20 (infrared shielding films) may be formed on the glass substrate 12. The IR cut coats 14 and 20 are films for shielding infrared rays.

The IR cut coat 14 is an alternating multilayer film in which a plurality of low refractive index layers 14a made of a low refractive index material and high refractive index layers 14b made of a high refractive index material are alternately stacked. The IR cut coat 20 is also an alternating multilayer film of low refractive index layers 20a and high refractive index layers 20b. In the IR cut coats 14 and 20, the low refractive index layers 14 a and 20 a are preferably in direct contact with the glass substrate 12.

As the low refractive index material constituting the low refractive index layers 14a and 20a, SiO ₂ or the like is used. On the other hand, TiO ₂ , Ta ₂ O ₅ , Nb ₂ O ₃ , ZrO ₂ or the like is used as the high refractive index material constituting the high refractive index layers 14b and 20b. In the IR cut coats 14 and 20, the low refractive index layers 14a and 20a may be made of different materials, and the high refractive index layers 14b and 20b may be made of different materials.

The IR cut coats 14 and 20 are usually composed of about 10 to 40 layers, preferably 20 layers each. Either one of the IR cut coats 14 and 20 is sufficient, but since the glass substrate 12 may be bent under the stress of the IR cut coats 14 and 20, both IR cut coats 14 and 20 existed. Is preferred. The number of layers of the IR cut coats 14 and 20 may be the same or different.

The symbols used in this example 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: spacing between upper surfaces of axis Nd: refractive index of lens material with respect to d-line νd: Abbe number of lens material In this embodiment, the aspherical shape has the vertex of the surface as the origin and the optical axis direction as the X axis In the orthogonal coordinate system, the vertex curvature is C, the conic constant is K, and the aspherical coefficients are A4, A6, A8, A10, A12, A14, and A16, expressed by “Equation 1”.

(1) Production of Sample Basically, an imaging lens having the same configuration as that shown in FIG. 1 was produced according to the production method described in the embodiment, and this was used as a sample.

This imaging lens is assumed to be used for an imaging element of 1/5 inch type, pixel pitch of 1.75 μm, and 1600 × 1200 pixels.

As the resin constituting each resin part, an epoxy resin (specifically, 4% by mass of UVI-6992 was added as a UV curing initiator to a hydrogenated bisphenol A type epoxy resin) was used.

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

In the imaging lens as described above, inorganic particles were variously contained in each resin portion, and “samples 1 to 5” were obtained by combinations thereof (see Table 2).

In all the samples, an antireflection film (Anti-Reflector-Coat) was formed on the most image-side convex lens portion constituting the S4 surface.

As the inorganic particles, silica (RX300 manufactured by Nippon Aerosil Co., Ltd., particle size: 7 nm) was used, and the amount of the inorganic particles added was 50% by mass with respect to the resin part.

As the antireflection film, a two-layer antireflection film was formed on the lens group on the image side (resin portion constituting the S4 surface).

First, the lens group was mounted in a vacuum deposition apparatus, the pressure in the apparatus was reduced to 2 × 10 ⁻³ Pa, and the lens group was heated to 200 ° C. by a heater at the top of the vacuum deposition apparatus.

Thereafter, a 20 nm (Ta ₂ O ₅ + 5% TiO ₂ ) film was formed directly on the surface of the resin portion as the first layer film. In this case, OA600 manufactured by Optran Co., Ltd. was used as the evaporation source, and the evaporation source was evaporated by electron gun heating to form a (Ta ₂ O ₅ + 5% TiO ₂ ) film. During the vapor deposition, the O ₂ gas was introduced until the pressure inside the vacuum vapor deposition apparatus reached 1.0 × 10 ⁻² Pa, and the film was formed while controlling the vapor deposition rate at 5 liters / sec.

Thereafter, as the second layer film, a 110 nm SiO ₂ film was formed following the first layer film. In this case, O ₂ gas was introduced until the pressure inside the vacuum vapor deposition apparatus was 1.2 × 10 ⁻² Pa, and the film was formed while controlling the vapor deposition rate at 5 Å / sec.

In Table 2, the resin part containing inorganic particles is described as “P (Particle)”.

(2) Evaluation of samples (2.1) Presence or absence of cracks after reflow A heat resistance test assuming IR reflow treatment was performed on each sample.

In the heat resistance test, each sample was introduced into an IR furnace and heated at 260 ° C. for 6 minutes as one cycle, and this was performed for 3 cycles.

The surface state (presence or absence of cracks) of the antireflection film after the heat test was observed with an optical microscope. The observation results are shown in Table 2. In Table 2, the criteria for ◯, Δ, and X are as follows.
“○”… There are no cracks.
“△”: There are 1 to 10 cracks.
“X”: There are 11 or more cracks.

(2.2) Presence or absence of wrinkles under vapor deposition conditions Each sample was placed and evacuated inside a vacuum vapor deposition apparatus, and then heated at 200 ° C. to cool to room temperature. The surface state (presence or absence of wrinkles) of the antireflection film after cooling was observed with an optical microscope. The observation results are shown in Table 2. In Table 2, the criteria for ◯ and × are as follows.
“○”… No wrinkles.
“×”… There are wrinkles.

(2.3) Presence / absence of peeling of resin part after dicing Wafer lens laminated body during sample manufacturing process (see FIG. 3, a wafer lens in which 1000 lens parts are formed on both front and back surfaces of one glass substrate is used. .) Was diced (mechanically cut), and the state of the resin part (existence of peeling or cracking) was observed.

In the dicing process, a dicer using an endless blade (rotating blade) by cutting with abrasive grains was used, and the rotation speed of the endless blade was set to 3 to 7 mm / sec. During dicing, pure water was flowed around the endless blade to prevent frictional heat.

Table 2 shows the observation results after dicing. In Table 2, the criteria for ◯, Δ, and X are as follows.
“◯”: The resin part is peeled off at less than 10% (100) lens parts.
“Δ”: There is peeling of the resin part in the lens part in the range of 10% or more and less than 30% (300).
“×”: There is peeling of the resin part in the lens part of 30% or more.

(2.4) Presence / absence of cracking of resin part after dicing The same dicing process as in item (2.3) was performed, and the state of the resin part after dicing process (presence of cracking) was observed. The observation results are shown in Table 2. In Table 2, the criteria for ◯, Δ, and X are as follows.
“◯”: There is a crack in the resin portion at a lens portion of less than 10% (100 pieces).
“Δ”: There is a crack in the resin portion in the lens portion in the range of 10% or more and less than 30% (300 pieces).
“×”: There is a crack in the resin part in the lens part of 30% or more.

(3) Summary As shown in Table 2, cracks and wrinkles were formed in the antireflection film in sample 1 (comparative example) in which the convex lens portion constituting the S4 surface did not contain inorganic particles, whereas in samples 2-5 Such a phenomenon was not observed.

From this, it can be seen that the inclusion of inorganic particles in the convex lens portion constituting the S4 surface is useful for preventing the occurrence of cracks and wrinkles in the antireflection film.

Among samples 2 to 5, in sample 2 (comparative example) in which inorganic particles are contained in the convex lens portion constituting the S1 surface, peeling and cracking of the resin portion after dicing were particularly remarkable. In Samples 3 to 5, this phenomenon was reduced.

From this, it can also be seen that it is useful to prevent the resin portion from peeling or cracking if the lens portion other than the lens portion constituting the S4 surface does not contain inorganic particles.

DESCRIPTION OF SYMBOLS 1 Imaging device 2 Imaging lens 4 Optical low-pass filter 6 Imaging element 8, 10 Lens group 12 Glass substrate 14 IR cut coat 14a Low refractive index layer 14b High refractive index layer 16 Resin part 16a Convex lens part 16b Non-lens part 18 Aperture 20 IR cut coat 20a Low refractive index layer 20b High refractive index layer 22 Resin part 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 36 Antireflection film 36a First layer 36b Second layer 40 Spacer 42, 44 IR cut coat 50 Wafer lens laminate 60 Dicing line

Claims (9)

1. A first glass substrate,
   A resin-made first lens portion that is disposed on the object-side surface of the first glass substrate and constitutes an S1 surface that is an object-side optical surface; and
   A first lens group that is disposed on the image side surface of the first glass substrate and has a second lens portion made of a resin that constitutes an S2 surface that is an image side optical surface;
   A second glass substrate,
   A resin-made third lens portion that is disposed on the object-side surface of the second glass substrate and forms an S3 surface that is an object-side optical surface; and
   A second lens group that is disposed on the image side surface of the second glass substrate and has a resin-made fourth lens portion that forms the S4 surface that is an image side optical surface is disposed in this order from the object side to the image side. An imaging lens,
   An antireflection film is formed on at least the S4 surface,
   At least the fourth lens portion is made of a resin in which inorganic particles are dispersed.
2. The imaging lens according to claim 1,
   At least the first lens unit has a positive power,
   At least one of the second lens unit and the third lens unit has a negative power.
3. The imaging lens according to claim 1 or 2,
   The second lens unit and the third lens unit both have negative power.
4. The imaging lens according to claim 3,
   The second lens portion and the third lens portion each have a flange portion provided on the outer periphery of the optical surface,
   The imaging lens, wherein the flange portion of the second lens portion and the flange portion of the third lens portion are directly bonded to each other.
5. The imaging lens according to any one of claims 1 to 4,
   The imaging lens, wherein the first lens portion is made of a resin that does not contain inorganic particles.
6. The imaging lens according to any one of claims 1 to 5,
   The imaging lens, wherein the second lens portion and the third lens portion are made of a resin not containing inorganic particles.
7. The imaging lens according to any one of claims 1 to 6,
   The imaging lens, wherein the antireflection film is formed only on a lens portion made of a resin in which inorganic particles are dispersed.
8. An imaging lens according to any one of claims 1 to 7;
   An image sensor;
   An image pickup apparatus, wherein the fourth lens unit is disposed so as to face the image pickup element.
9. The imaging device and the electronic component according to claim 8 are placed on a wiring board on which solder is previously disposed, and the solder is melted by heating, whereby the imaging device and the electronic component are connected to the wiring board. A method for manufacturing an electronic device, which is mounted on the electronic device.

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