JP2005153276A - Manufacturing method of optical element and optical element - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a manufacturing method of an optical element capable of ensuring characteristics necessary as a molded product and capable of enhancing productivity. <P>SOLUTION: This manufacturing method of the optical element has a resin liquid supply process for casting a thermosetting resin liquid in a mold part composed of one mold 2 constituted of a light pervious material and another mold 1 constituted of a mold having a light absorbing layer 3b, of which the absorptivity is higher than that of a mold material, provided to its surface and a resin liquid curing process for irradiating the thermosetting resin liquid with visible light or near infrared rays from the side of one mold constituted of the light pervious material to cure the same. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a method for manufacturing an optical element and an optical element, and more particularly to a method for manufacturing an optical element and an optical element obtained by transferring an uneven shape on a mold surface to a resin.

  Conventionally, there is an optical element formed by transferring a fine uneven surface formed on a separation-type surface onto a base material made of a light-transmitting thermosetting resin. In addition, as a technique for resin-sealing the functional element, a thermosetting resin such as a molten epoxy resin that becomes a mold member is injected into the space of the casting mold recess, and the injected thermosetting resin is In some cases, after curing, the thermosetting resin becomes a mold member and the functional element is integrated.

  In this method of manufacturing a functional element, the functional element is mounted on a substrate as necessary and inserted into a casting mold. Next, a molten thermosetting resin serving as a mold member is injected into the space between the substrate and the casting mold, and the injected thermosetting resin is heated and cured from around the mold. Thereafter, the functional element integrated with the mold member formed by curing the thermosetting resin is taken out from the casting mold. Thereby, an optical element in which the mold member and the functional element are integrated is formed.

  In the element manufacturing method as described above, as a method for curing the mold member, a method in which thermal energy is applied to the resin by heat conduction from the outside to induce a radical reaction and curing is generally performed. However, in that method, it is necessary to heat the entire casting mold (mold) in order to heat the resin, which not only requires a lot of energy, but also in terms of durability and environmental / safety of the mold. Have any problems.

Therefore, for example, as disclosed in Japanese Patent Laid-Open No. 62-5819, a photocurable resin composition is injected into a mold made of a material that transmits high energy rays, and then irradiated with high energy rays to cure the resin. There is also a method of curing.
JP-A-62-5819

  However, even when the resin is cured by irradiating with high energy rays, the resin composition is not selected for the purpose of absorbing the energy rays, so it is necessary to prepare energy rays according to the resin composition. Moreover, since the heat absorption efficiency is not high, a large facility is required. Also, the energy range in which the curing reaction can be initiated without degrading the polymer is very narrow.

  On the other hand, in the case of a photo-curing resin, since energy rays are fixed, the type and characteristics of the resin are limited, and there is a problem that characteristics required as a molded product cannot be ensured.

  The present invention has been made in view of these problems, and an object of the present invention is to provide a method of manufacturing an optical element that can ensure the necessary characteristics as a molded product and can improve productivity.

  The method for producing an optical element according to claim 1 of the present invention is a method for producing an optical element obtained by transferring a fine uneven surface formed on a mold surface to a base material made of a light-transmitting thermosetting resin. One mold is made of a light-transmitting material, and the other mold is made up of a mold having a light absorption layer having a light absorption rate larger than that of the mold material on the surface. A resin liquid supply process for pouring the resin liquid, and a resin liquid curing process for curing the thermosetting resin liquid by irradiating visible or near-infrared light from the one side of the mold made of a translucent material. It is characterized by having.

  According to a second aspect of the present invention, there is provided an optical element manufacturing method according to the first aspect, wherein the other mold having the light absorption layer has a fine uneven surface. To do.

  A method for manufacturing an optical element according to a third aspect of the present invention is the method for manufacturing an optical element according to the first aspect, wherein the thickness of the light absorption layer is 10 μm to 0.05 μm.

  A method for manufacturing an optical element according to a fourth aspect of the present invention is the method for manufacturing an optical element according to the first aspect, wherein the light absorption layer is a carbide of titanium or chromium.

  A method for manufacturing an optical element according to a fifth aspect of the present invention is the method for manufacturing an optical element according to any one of the first to fourth aspects, wherein a heat insulating layer is provided on the back surface of the light absorption layer.

  A method for manufacturing an optical element according to a sixth aspect of the present invention is the method for manufacturing an optical element according to the first aspect, wherein a single layer film of magnesium fluoride is formed on the surface of one of the molds made of a translucent material. And an antireflection film such as a silica film, a zirconia film, or an alumina film.

  A method for manufacturing an optical element according to a seventh aspect of the present invention is the method for manufacturing an optical element according to the first aspect, wherein the refractive index of the light transmitting material is substantially the same as that of the thermosetting resin liquid.

  The optical element manufacturing method according to the present invention described in claim 8 is the optical element manufacturing method according to claim 2, wherein the light-absorbing layer disposed around the uneven portion is irradiated with light, and then the uneven portion. The light-absorbing layer disposed on the substrate is irradiated with light.

  The method for manufacturing an optical element according to the present invention described in claim 9 is the method for manufacturing an optical element according to claim 2, wherein the light absorption rate of the light absorption layer disposed around the uneven portion is that of the uneven portion. A light absorption layer having a higher light absorption rate is used.

  A method for manufacturing an optical element according to a tenth aspect of the present invention is the method for manufacturing an optical element according to the second aspect, comprising a mechanism for controlling the temperature of the separation mold to be equal to or lower than the curing temperature of the thermosetting resin liquid. ing.

  An optical element manufacturing method according to an eleventh aspect of the present invention is the optical element manufacturing method according to the first aspect, wherein pressure is applied to at least one of the molds between the resin liquid supply step and the resin liquid curing step. Is loaded with a resin liquid compression step of applying a compressive force to the thermosetting resin liquid in the mold.

  An optical element according to a twelfth aspect of the present invention is manufactured by the method for manufacturing an optical element according to the first to eleventh aspects.

  According to the optical element manufacturing method of the first aspect, by converting light energy into heat in the light absorption layer, local heating can be performed without heating the entire mold. Therefore, the curing rate of the resin can be accelerated and the productivity is excellent. Further, as compared with the conventional curing method, it is not necessary to consider the combination of the type of resin to be molded and the wavelength of light to be used, so that the degree of freedom in material selection is expanded.

  According to the optical element manufacturing method of the second aspect of the present invention, in addition to the effect of the first aspect, since there is no restriction on the properties of the mold material, a material capable of high-precision processing is used as the mold material for forming the uneven surface. You can choose.

  According to the method for manufacturing an optical element according to claim 3 of the present invention, when the thickness of the light absorption layer exceeds 10 μm, the shape accuracy of the mold is lowered and the optical element cannot be used. Further, if the thickness of the light absorption layer is less than 0.05 μm, the heat capacity of the light absorption layer becomes small, so the amount of heat generation becomes small, and a portion where the resin is not cured occurs.

  According to the method for manufacturing an optical element described in claim 4 of the present invention, in addition to the effect of claim 1, since the hardness is high, the life of the mold can be extended.

  According to the method for manufacturing an optical element according to claim 5 of the present invention, in addition to the effect of claim 1, the heat insulating layer prevents heat from flowing out of the light absorption layer. Outflow to the mold side can be prevented, and heating efficiency is improved.

  According to the method for manufacturing an optical element according to claim 6 of the present invention, in addition to the effect of claim 1, it is possible to prevent attenuation due to reflection when light is emitted from a mold made of a translucent material, Light energy can be used efficiently.

  According to the method for manufacturing an optical element according to claim 7 of the present invention, in addition to the effect of claim 1, when irradiated with light, a mold made of a translucent material, a thermosetting resin liquid, Since the deviation of the irradiation position accuracy due to light refraction at the interface can be prevented, light can be irradiated with high accuracy.

  According to the method for manufacturing an optical element according to claim 8 of the present invention, in addition to the effect of claim 2, the position accuracy of the outer shape can be ensured when cured from the outer periphery, and the position is a few mm inside the outer periphery. The deformation position is concentrated, and the internal distortion of the uneven portion can be improved.

According to the method for manufacturing an optical element of the ninth aspect of the present invention, in addition to the effect of the second aspect, it is possible to prevent the fine shape from being deformed by curing shrinkage in the non-shaped portion.

  According to the method for manufacturing an optical element according to claim 10 of the present invention, in addition to the effect of claim 1, the hardened portion due to heat propagation in the mold does not spread more than necessary. It can be cured at the timing. Moreover, since the thermal characteristics of the thermosetting resin liquid can be stabilized, it becomes possible to prevent molding defects at the time of removal and to stabilize the quality.

  According to the method for manufacturing an optical element according to the eleventh aspect of the present invention, in addition to the effect of the first aspect, the occurrence of defects such as sink marks can be suppressed by applying pressure compensation for the specific volume decrease due to the curing shrinkage. .

  According to the optical element of the twelfth aspect of the present invention, it is possible to obtain a good optical element that is not deformed with a fine shape and has no molding defects.

  The method of manufacturing an optical element is a method of manufacturing an optical element obtained by transferring a fine uneven surface formed on a separation mold surface to a base material made of a light-transmitting thermosetting resin, and one mold is A resin liquid supply step in which the other mold is composed of a mold having a light absorption layer with a light absorption rate larger than that of the mold material on the surface, and a thermosetting resin liquid is poured into the mold portion. And a resin liquid curing step of curing the thermosetting resin liquid by irradiating visible or near infrared light from one side of the mold made of a translucent material. This enables local heating without heating the entire mold, accelerates the curing speed of the resin, has excellent productivity, and considers the combination of the type of resin to be molded and the wavelength of light used The effect of not having to do was able to be acquired.

  FIG. 1 is a view showing a casting mold according to a first embodiment for explaining one process of a method for producing an optical element of the present invention. FIG. 1 (a) is a cross-sectional view taken along a horizontal line, and FIG. It is sectional drawing which follows the BB line of (). FIG. 2 is a diagram illustrating a resin curing step in the manufacturing method.

  The casting mold used to manufacture the optical element according to the present invention includes a lower mold (the other mold) 1 in which one side of the box is opened and a recess is formed, and an upper covering the opening of the lower mold 1. The mold (one mold) 2 is separable from the mold.

  The bottom of the lower mold 1 has a fine uneven shape 3a, and a light absorbing layer 3b that absorbs light of 0.05 to 10 μm is formed, thereby having light absorption. If the thickness of the light absorption layer 3b of the separation mold 3 exceeds 10 μm, the shape accuracy of the mold deteriorates and cannot be used as an optical element. On the other hand, if the thickness is less than 0.05 μm, the heat capacity of the light absorption layer 3b is reduced, so that the amount of heat generation is reduced, and a portion where the resin is not cured occurs.

Further, as the material of the light absorption layer 3b, black nickel plating, titanium, chromium carbide or the like is used. If the carbide of titanium or chromium is used, the mold has a long life because of its high hardness.
The upper mold 2 is made of a translucent member such as quartz glass. Further, an antireflection film 2a such as a magnesium fluoride single layer film, a silica film, a zirconia film, or an alumina film may be provided on the surface of the upper mold 2 made of a translucent material. If it does so, the attenuation | damping by reflection when light radiate | emits from the type | mold comprised with the translucent material can be prevented, and it will become possible to use optical energy efficiently.

  A method of manufacturing an optical element using this casting mold will be described with reference to FIG. First, the upper mold 2 covers and seals the opening of the lower mold 1 and the thermosetting resin 4 is injected while degassing (FIG. 2A).

  Next, visible light or near-infrared light L is passed through the upper mold 2 to irradiate the thermosetting resin liquid, and the temperature of the light absorption layer is increased to heat and cure the thermosetting resin (FIG. 2B). ). Irradiation with visible light or near infrared light L is performed over the entire surface of the optical element (FIG. 2C). Then, it molds and performs a required process and obtains an optical element.

(Example 1)
As shown in FIG. 1, the mold for carrying out the manufacturing method was configured as follows, and an optical element was manufactured under the following conditions.
Type:
The outer width W was 40 mm, the depth outer dimension D was 70 mm, and the height H was 30 mm.
Lower mold (non-translucent) material: Nickel light absorption layer: Black nickel plating (Black zinc-nickel alloy plating)
Light absorption layer thickness: 0.5 μm
Fine shape: Convex upper mold (translucent) having a cross section with a height of 10 μm and a width of 10 μm: Quartz glass resin:
Main agent: Urethane acrylate resin (Praglas # 8000, manufactured by Dainippon Paint Co., Ltd.)
Curing agent: Bisperoxy dicarnate and dibutyl phthalate mixture Filling method: Injection laser condition:
Laser type: Semiconductor laser (Spectra Physics) Wavelength: 795 nm
Spot diameter: 1.5mm diameter
Energy density: 2.5W
Scan speed: 2.5m / sec
Oscillation method: Continuous oscillation.

  Under the above conditions, as shown in FIG. 2, the thermosetting resin 4 is injected into a mold part having a fine concavo-convex surface disposed on the light absorption layer 3. The injection resin is cured by irradiating laser light L from the light-transmissive upper mold 2. As a result, a cured product having a width substantially equal to the spot diameter was formed. From this result, it was found that local heating was possible. Moreover, from this result, the curing rate of the resin can be accelerated, and the productivity can be improved.

Moreover, it has a fine uneven surface on the mold side provided with the light absorption layer. With such a configuration, there is no restriction on the properties of the mold material, and therefore a material capable of high-precision machining can be selected as the mold material for forming the uneven surface.
(Example 2)
An optical element was manufactured in the same manner as in Example 1 except that the thickness of the light absorption layer was changed to 0.05 to 10 μm.

  As a comparative example, the mold accuracy and curing quality were examined when the thickness of the light absorption layer was less than 0.05 μm and when the thickness exceeded 10 μm. The results are shown in Table 1 below.

As is apparent from Table 1, when the thickness of the light absorption layer exceeds 10 μm, the resin was cured well, but the shape accuracy of the mold was lowered. Further, when the thickness of the light absorbing layer was less than 0.05 μm, the resin was not cured well, but the shape accuracy of the mold was good. This is considered to be because the heat capacity of the light absorption layer is reduced, so that the amount of heat generation is reduced, and a portion where the resin is not cured is generated.
(Example 3)
An optical element was manufactured in the same manner as in Example 1 except that the light absorbing layer was made of chromium carbide and titanium carbide instead of black nickel plating.

  Then, the number of shots reaching the altitude and life of the light absorption layer was measured. The results are shown in Table 2 below.

As is apparent from Table 2, in the case of the chromium carbide light absorption layer, a life approximately twice that of the black nickel plating light absorption layer is obtained. In the titanium carbide light absorption layer, a life approximately three times that of the black nickel plating light absorption layer is obtained.
Example 4
As shown in FIG. 3, a ceramic heat insulation layer 5 having a thickness of 5 mm was provided in the lower mold 1 and the laser scan speed was 3.1 m / sec. An optical element was manufactured.

  The laser scanning speed at which good resin curing can be obtained was examined and shown in Table 3 below.

As shown in Table 3, even when the laser scan speed was 3.1 m / sec, the resin was cured uniformly. Thereby, it was possible to prevent the amount of heat absorbed by the light absorption layer from flowing out to the mold side, and the heating efficiency was improved.
(Example 5)
As shown in FIG. 4, the optical element is manufactured in the same manner as in Example 1 except that the anti-reflection film 2a is provided on the upper die and the laser scan speed is 2.8 to 3.1 m / sec. did.
The antireflection film on the surface of the mold made of a translucent material was formed of a magnesium fluoride single layer film, a silica film, a zirconia film, an alumina film, or the like.

  For each antireflection film, the laser scan speed at which good resin curing can be obtained was examined and shown in Table 4 below.

As can be seen from Table 4, since attenuation due to reflection when light is emitted from a mold made of a translucent material can be prevented, the amount of heat absorbed by the light absorption layer can be prevented from flowing out to the mold side. it can. Thereby, it became possible to use light energy efficiently and the heating efficiency was improved. As a result, in the absence of the antireflection film, it was possible to accelerate the slowness from 2.5 m / sec to 2.8 to 3.1 m / sec.
(Example 6)
Germanium glass whose refractive index of the upper light-transmitting material is approximately the same as that of thermosetting resin liquid (acrylic resin (refractive index = 1.6)) of 1.45 of quartz glass; CORNING 9754 (refractive index = 1.6) And an optical element was manufactured in the same manner as in Example 1 except that the laser scanning speed was 3.1 m / sec.

  In this case, the laser scanning speed at which good resin curing can be obtained was examined and shown in Table 5 below.

Thus, when light is irradiated, light refraction at the interface between the mold made of a translucent material and the thermosetting resin liquid can be prevented, so that light can be irradiated with high accuracy.
(Example 7)
As shown in FIG. 5, the optical element was manufactured in the same manner as in Example 1 except that the lower mold was changed so that laser scanning was performed sequentially from the periphery of the lower mold so that laser scanning was performed from the periphery of the uneven portion.
The results of examining the state of resin curing in this case are shown in Table 6 below.

As a result of observing the transfer state of the fine shape of the end portion, there was a defect when scanning from the uneven portion to the periphery. When scanning from the periphery to the concavo-convex portion, no defect occurred.
When cured from the outer periphery, the position accuracy of the outer shape could be ensured, and the minimal deformation position was concentrated at a few mm inside the outer periphery, and the internal distortion of the concavo-convex part could be improved.
(Example 8)
As shown in FIG. 6, the same as in Example 1 except that the light absorption rate of the light absorption layer 3c disposed around the uneven portion is higher than that of the light absorption layer 3b disposed in the uneven portion. Thus, an optical element was manufactured.

  The results of examining the state of resin curing in this case are shown in Table 7 below.

As a result of this observation, it was possible to prevent the fine shape of the shape portion from being deformed by curing shrinkage in the non-shape portion around the shape portion.
Example 9
As shown in FIG. 7, a pipe for flowing cooling water is installed as a cooling mechanism 6 on the back side of the light absorption layer of the lower mold 2, and the temperature of the separation mold is controlled by the cooling mechanism below the curing temperature of the thermosetting resin liquid. Except for the above, an optical element was manufactured in the same manner as in Example 1. By cooling the mold, the resin temperature can be controlled to be equal to or lower than the curing temperature, and the cured portion around the laser irradiated portion due to heat conduction can be reduced.
As a result, the hardened portion due to heat propagation in the mold does not spread more than necessary, so that the desired portion can be hardened at a desired timing. Moreover, since the thermal characteristics of the thermosetting resin liquid can be stabilized, it becomes possible to prevent molding defects at the time of removal and to stabilize the quality.
(Example 10)
As shown in FIG. 8, in the same manner as in Example 1 except that a load load mechanism 7 is provided to load at least one of the molds between the resin liquid supply process and the resin liquid curing process. An optical element was manufactured.

  Table 8 below shows the results of examining the surface shape of the cured resin and the state of shrinkage in this case.

  As a result, the occurrence of defects such as sink marks can be suppressed by applying pressure compensation to the specific volume reduction due to curing shrinkage.

  In the above description, the optical element formed by transferring the concavo-convex shape has been described, but the present invention is not limited to this. For example, a case where a chip for a CCD linear sensor or a CCD area sensor, an LED chip, a semiconductor laser chip, or the like having a light absorption layer having a light absorption rate larger than that of the mold material is sealed may be used.

BRIEF DESCRIPTION OF THE DRAWINGS It is a figure explaining the casting type | mold of 1st Example of the optical element of this invention, A figure (a) is sectional drawing in alignment with a horizontal line (AA line of figure (b)), A figure (b) is a figure (a). It is sectional drawing which follows the BB line of (). It is a figure explaining the resin hardening process in the manufacturing method which concerns on this invention, A figure (a) is sectional drawing which shows the state which inject | poured thermosetting resin, A figure (b) has started the irradiation of the laser beam FIG. 2C is a cross-sectional view showing a state in which laser light is further irradiated. It is sectional drawing explaining the structure of the light absorption layer of 4th Example based on the optical element of this invention. It is sectional drawing explaining the structure of the light absorption layer of 6th Example based on the optical element of this invention. It is sectional drawing explaining the manufacturing process of 7th Example based on the optical element of this invention, FIG. (A) is sectional drawing in alignment with the horizontal line in the process of an irradiation initial stage, FIG. (B) is B- of FIG. Cross-sectional view taken along line B, FIG. 5C is a cross-sectional view taken along the horizontal line in the final stage of irradiation, and FIG. 4D is a cross-sectional view taken along line BB in FIG. It is sectional drawing explaining the structure of the light absorption layer of the 8th Example based on the optical element of this invention, (a) is sectional drawing which follows a horizontal line, (b) is BB line of FIG. (A). It is sectional drawing which follows. Sectional drawing explaining the structure of the lower mold | type of 9th Example which concerns on the optical element of this invention, (a) is sectional drawing which follows a horizontal line, (b) is sectional drawing which follows the BB line of (a). is there. It is a figure explaining the process of loading the thermosetting resin of 10th Example which concerns on the optical element of this invention.

Explanation of symbols

1 Lower mold (the other mold)
2 Upper mold (one mold)
2a Antireflection layer 3a Concave and convex shape 3b Light absorption layer 3c Light absorption layer with high light absorption rate 4 Thermosetting resin 4a Cured thermosetting resin 5 Heat insulation layer 6 Cooling mechanism 7 Load application mechanism L Laser light

Claims (12)

A method for producing an optical element formed by transferring a fine uneven surface formed on a mold surface to a base material made of a light-transmitting thermosetting resin,
One mold is composed of a translucent material, and the other mold is composed of a mold having a light absorption layer having a light absorption rate larger than that of the mold material on the surface, and a thermosetting resin liquid is poured into the mold portion. A resin liquid supply step;
A resin liquid curing step of curing the thermosetting resin liquid by irradiating visible or near-infrared light from the one side of the mold made of a translucent material;
An optical element manufacturing method comprising: The method of manufacturing an optical element according to claim 1, wherein the other mold having the light absorption layer has a fine uneven surface. The method of manufacturing an optical element according to claim 1, wherein the light absorption layer has a thickness of 10 μm to 0.05 μm. The method of manufacturing an optical element according to claim 1, wherein the light absorption layer is a carbide of titanium and chromium. The method for manufacturing an optical element according to claim 1, wherein a heat insulating layer is provided on the back surface of the light absorption layer. 2. The optical element according to claim 1, wherein an antireflection film such as a magnesium fluoride single layer film, a silica film, a zirconia film, or an alumina film is provided on the surface of one of the molds made of a translucent material. Method. The method of manufacturing an optical element according to claim 1, wherein a refractive index of the translucent material is substantially the same as that of the thermosetting resin liquid. The method of manufacturing an optical element according to claim 2, wherein the light absorption layer disposed around the uneven portion is irradiated with light, and then the light absorption layer disposed on the uneven portion is irradiated with light. The manufacturing method of the optical element of Claim 2 using the light absorption layer whose light absorption rate of the said light absorption layer distribute | arranged around the said uneven | corrugated | grooved part is higher than the light absorption rate of this uneven | corrugated | grooved part. The method for manufacturing an optical element according to claim 1, further comprising a mechanism for controlling the temperature of the separation mold to be equal to or lower than a curing temperature of the thermosetting resin liquid. A resin liquid compression step of applying a compressive force to the thermosetting resin liquid in the mold by applying pressure to at least one of the molds between the resin liquid supply step and the resin liquid curing step; The method for manufacturing an optical element according to claim 1. The optical element manufactured by the manufacturing method of the optical element of the said Claims 1-11.

Images