Lens module manufacturing method and thermosetting adhesive

Abstract

To provide a method for manufacturing a lens module and a thermosetting adhesive which can sufficiently obtain adhesive strength after temporary curing.SOLUTION: A method for manufacturing a lens module 1 includes: a step A1 of coating thermosetting adhesives 10d and 10e containing a colorant between a circuit board 3 mounted with an image sensor 4 and a sensor frame 8, and / or between the sensor frame 8 and an optical unit 11 including a lens 5 and a lens housing 13; a step B1 of forming a joined body 15 in which focuses of the lens 5 and the image sensor 4 are matched with each other; a step C1 of temporarily curing the thermosetting adhesives 10d and 10e using heating means 16 capable of heating the thermosetting adhesives 10d and 10e from the vicinity in a spotlight manner; and a step D1 of heating the joined body 15, and further curing the thermosetting adhesives 10d and 10e.SELECTED DRAWING: Figure 4

Description

Technical Field

[0001] This technology relates to a method for manufacturing a lens module and a thermosetting adhesive.

Background Art

[0002] In order to improve the lens fixing accuracy of a camera module, an active alignment method is applied. The active alignment method is a method in which temporary curing is performed in seconds using an ultraviolet curing component, and then main curing is performed by heat curing. In order to realize the active alignment method, a one-component adhesive that combines two different curing systems, for example, ultraviolet curing and heat curing or moisture curing, is widely used. Considering the production tact time, in the active alignment method, it is important to obtain sufficient fixing accuracy with a tact time in seconds when performing temporary curing using ultraviolet curing. Also, in the active alignment method, usually, since temporary curing is performed with ultraviolet rays, it is necessary to use an adhesive having permeability in the ultraviolet region.

[0003] For example, in Patent Document 1, in an in-vehicle camera including a lens including an optical component, a lens barrel that holds the optical component inside, an imager including an image sensor, and a lens holder, the lens barrel is bonded by a cured adhesive, the adhesive is first curable in an initial curing process including exposure to UV light, the first-cured adhesive is further curable in a secondary curing process, and the secondary curing process includes introducing heat to the first-cured adhesive.

[0004] In the technology described in Patent Document 1, since the initial curing process includes exposure to UV light, it is necessary to use an adhesive having permeability in the ultraviolet wavelength region. Therefore, in the technology described in Patent Document 1, depending on the design of the camera (for example, miniaturization of the camera), external light may enter from the location where the adhesive is used (the adhesive part of the camera), and there is a risk of occurrence of image defects called ghost and flare, and light shielding properties may be required.

[0005] In current active alignment methods, it is difficult to provide complete light shielding in order to ensure UV curing. For example, in the technology described in Patent Document 1, if an adhesive with low transmittance in the UV wavelength range (e.g., a blackened adhesive) is used, the adhesive may not pre-cur sufficiently, resulting in insufficient adhesive strength after pre-curing, and consequently, insufficient accuracy may not be achieved. [Prior art documents] [Patent Documents]

[0006] [Patent Document 1] Publication US8542451B1 [Overview of the project] [Problems that the invention aims to solve]

[0007] This technology was proposed in light of the conventional situation described above, and provides a method for manufacturing lens modules and a thermosetting adhesive that can obtain sufficient adhesive strength after partial curing. [Means for solving the problem]

[0008] The manufacturing method for a lens module according to this technology includes the steps of: A, applying a thermosetting adhesive containing a coloring agent to at least one of the following: between a circuit board on which an image sensor is mounted and a sensor frame; between a circuit board on which an image sensor is mounted and a housing; between the sensor frame and an optical unit including a lens and a lens housing; and between the housing and a lens barrel that holds the lens; B, forming a joint in which the lens and the image sensor are in focus; C, pre-curing the thermosetting adhesive using a heating means capable of spot heating the thermosetting adhesive from nearby; and D, heating the joint to further cure the thermosetting adhesive.

[0009] This technology provides a thermosetting adhesive for fixing at least one of the following: between a circuit board on which an image sensor is mounted and a sensor frame; between a circuit board on which an image sensor is mounted and a housing; between a sensor frame and an optical unit including a lens and a lens housing; and between a housing and a lens barrel that holds a lens, comprising a cationic curable compound, a thermo-cationic curing agent, and a coloring agent, and satisfying at least one of the following conditions 1 to 3. Condition 1: The thermosetting adhesive has a light transmittance of 3.0% or less at a wavelength of 800 nm when it is 0.5 mm thick. Condition 2: The thermosetting adhesive has a light transmittance of 0.3% or less at a wavelength of 500 nm when it is 0.5 mm thick. Condition 3: The thermosetting adhesive has a light transmittance of 0.008% or less at a wavelength of 300 nm when it is 0.5 mm thick. [Effects of the Invention]

[0010] This technology provides a method for manufacturing lens modules and a thermosetting adhesive that can achieve sufficient adhesive strength after partial curing. [Brief explanation of the drawing]

[0011] [Figure 1] Figure 1 is a cross-sectional view showing an example of a lens module obtained by the lens module manufacturing method according to this technology. [Figure 2] Figure 2 is a cross-sectional view illustrating an example of step A1 in the manufacturing method of a lens module. [Figure 3] Figure 3 is a cross-sectional view illustrating an example of step B1 in the manufacturing method of a lens module. [Figure 4] Figure 4 is a cross-sectional view illustrating an example of step C1 in the manufacturing method of a lens module. [Figure 5] Figure 5 is a perspective view illustrating an example of step D1 in the manufacturing method of a lens module. [Figure 6] Figure 6 is a cross-sectional view showing an example of a lens module obtained by the lens module manufacturing method according to this technology. [Figure 7] FIG. 7 is a perspective view for explaining an example of step A2 of the method for manufacturing a lens module. [Figure 8] FIG. 8 is a cross-sectional view for explaining an example of step A2 of the method for manufacturing a lens module. [Figure 9] FIG. 9 is a cross-sectional view for explaining an example of step C2 of the method for manufacturing a lens module. [Figure 10] FIG. 10 is a perspective view for explaining a method for evaluating the temporary curability of the compositions of Experimental Examples Ⅰ to 10. [Figure 11] FIG. 11 is a graph showing the measurement results of the transmittance of the compositions of Experimental Examples 6, 7, and 10. MODE FOR CARRYING OUT THE INVENTION

[0012] <Method for Manufacturing a Lens Module> [First Embodiment] FIG. 1 is a cross-sectional view showing an example of a lens module 1 obtained by the method for manufacturing a lens module according to the present technology. The lens module 1 includes, for example, a flexible substrate 2 (FPC: Flexible Printed Circuits), a circuit board 3, an image sensor 4, a lens 5, a lens barrel 6, a housing 7, a sensor frame 8, and an IR cut filter 9. In the lens module 1, the focal length between the lens 5 and the image sensor 4 disposed on the circuit board 3 is fixed by cured products 14d and 14e of a thermosetting adhesive.

[0013] Hereinafter, the lens 5, the lens barrel 6, and the housing 7 are collectively referred to as an optical unit 11. Also, the flexible substrate 2, the circuit board 3, and the image sensor 4 are collectively referred to as a sensor unit 12. Further, the lens barrel 6 and the housing 7 are collectively referred to as a lens housing 13.

[0014] Examples of the flexible substrate 2 include glass substrates and plastic substrates. The flexible substrate 2 has terminals for connecting to the circuit board 3. The flexible substrate 2 may have a single-layer structure or a multi-layer structure.

[0015] The circuit board 3 is a board on which the image sensor 4, sensor frame 8, etc., are mounted. Wiring for transmitting signals from the image sensor 4 and other components is arranged on the circuit board 3. The circuit board 3 is made up of, for example, a printed circuit board (PCB). The circuit board 3 has terminals for connecting to the flexible board 2 and is connected to the terminals of the flexible board 2 via a cured connecting material (for example, adhesive).

[0016] The image sensor 4 receives light focused by the lens and converts it into an electrical signal. The image sensor 4 is composed of, for example, a charge-coupled device (CCD) or a complementary metal oxide semiconductor (CMOS). The image sensor 4 is placed on the circuit board 3. The image sensor 4 is connected to a pad formed on the circuit board 3, for example, by bonding wires. This pad is connected to the wiring of the circuit board 3.

[0017] Lens 5 is for focusing light from the subject. Lens 5 is mounted on the lens barrel 6 at a predetermined position to focus the light (image) onto the light-receiving surface of the image sensor 4. Lens 5 comprises multiple optical elements arranged along the lens barrel 6. For example, as shown in Figure 1, lens 5 is fixed to the lens barrel 6 by a cured product 14a of a thermosetting adhesive. Lens 5 can be made of, for example, glass, plastic, or the like.

[0018] The lens barrel 6 is a lens barrel for holding the lens 5 and is configured, for example, in a cylindrical shape. The lens barrel 6 is fixed to the housing 7 by a cured product 14b of a thermosetting adhesive.

[0019] The housing 7 is a casing for holding the lens barrel 6. The housing 7 is fixed to the lens barrel 6 by a cured product 14b of a thermosetting adhesive and to the sensor frame 8 by a cured product 14d of a thermosetting adhesive.

[0020] The sensor frame 8 is fixed to the housing 7 by a cured product 14d of a thermosetting adhesive, and also fixed to the circuit board 3 by a cured product 14e of a thermosetting adhesive.

[0021] The IR cut filter 9 is a filter that transmits visible light contained in the light that has passed through the lens 5 while cutting out infrared rays. The IR cut filter 9 is positioned between the sensor frame 8 and the lens 5. The IR cut filter 9 is fixed to the sensor frame 8 by a cured product 14c of a curing adhesive.

[0022] In lens module 1, incident light from the outside passes sequentially through lens 5 and IR cut filter 9 before reaching image sensor 4.

[0023] The manufacturing method for lens module 1 comprises the following steps A1, B1, C1, and D1.

[0024] [Process A1] Figure 2 is a cross-sectional view illustrating an example of step A1 of a method for manufacturing a lens module. Step A1 involves applying a thermosetting adhesive between the circuit board 3 on which the image sensor 4 is mounted and the sensor frame 8, and / or between the sensor frame 8 and the optical unit 11, which includes the lens 5 and the lens housing 13. For example, as shown in Figure 2, step A1 includes at least one of applying a thermosetting adhesive 10e to the surface of the circuit board 3 on which the image sensor 4 is mounted, and applying a thermosetting adhesive 10d to the surface of the sensor frame 8 placed on the circuit board 3 on which the image sensor 4 is mounted.

[0025] Furthermore, if the circuit board 3 on which the image sensor 4 is mounted and the sensor frame 8 are fixed together beforehand, in step A1, only the thermosetting adhesive 10d needs to be applied. Also, if, for example, the circuit board 3 on which the image sensor 4 is mounted and the sensor frame 8 are not fixed together beforehand, in step A1, both the thermosetting adhesives 10d and 10e should be applied. Also, if, for example, the sensor frame 8 and the optical unit 11 are fixed together beforehand, in step A1, only the thermosetting adhesive 10e needs to be applied.

[0026] The following explanation will use the case where both thermosetting adhesives 10d and 10e are applied in step A1 as an example. Specifically, in this example step A1, the process includes applying thermosetting adhesive 10e between the circuit board 3 on which the image sensor 4 is mounted and the sensor frame 8, and applying thermosetting adhesive 10d between the sensor frame 8 and the optical unit 11.

[0027] The application method for the thermosetting adhesives 10d and 10e is not particularly limited and includes, for example, roll coating, doctor knife method, die coating, dip coating, bar coating, inkjet method, and jet dispensing method.

[0028] [Process B1] Figure 3 is a cross-sectional view illustrating an example of step B1 in the manufacturing method of a lens module. Step B1 involves forming a composite body 15 comprising a circuit board 3 on which an image sensor 8 is mounted, a sensor frame 8, and an optical unit 11, with the lens 5 and image sensor 4 in focus. For example, in step B1, the optical unit 11 is placed on a thermosetting adhesive 10d to form a composite body 15 with the lens 5 constituting the optical unit 11 and the image sensor 4 in focus. In this way, step B1 is used to align the lens 5 and the image sensor 4.

[0029] In step B1, the optical axis of the optical unit 11 is adjusted. The optical axis of the optical unit 11 can be adjusted, for example, by displacing the optical unit 11 using the active alignment method. The adjustment of the optical axis of the optical unit 11 includes, for example, adjustments in the x, y, and z axes, and adjustments in the rotation angle.

[0030] [Process C1] Figure 4 is a cross-sectional view illustrating an example of step C1 in the manufacturing method of a lens module. In step C1, the thermosetting adhesives 10d and 10e in the joint 15 are partially cured using a heating means 16 that can heat them spot by spot from nearby. In this way, step C1 temporarily fixes the joint 15 formed in step B1 in the correct position, that is, with the lens 5 and the image sensor 4 in focus.

[0031] Conventional lens module manufacturing methods involve pre-curing the adhesive (an adhesive that is transparent to the ultraviolet wavelength region) with ultraviolet light. For example, in the technology described in Patent Document 1, after aligning the lens and the image sensor, the ultraviolet-curable and thermosetting adhesives are pre-cured with ultraviolet light, and then the adhesive is thermo-cured by batch processing. In such conventional lens module manufacturing methods, since the adhesive is pre-cured by ultraviolet irradiation, it is necessary to use an adhesive that is transparent to the ultraviolet wavelength region. Furthermore, in conventional lens module manufacturing methods, ultraviolet light tends to be easily absorbed at the surface of the adhesive, which may prevent the adhesive from being sufficiently pre-cured inside. In addition, because conventional lens module manufacturing methods require the use of an adhesive that is transparent to the ultraviolet wavelength region, external light may penetrate from the adhesive application site, potentially causing image defects such as ghosting and flare.

[0032] On the other hand, in the lens module manufacturing method according to this technology, since the thermosetting adhesive is partially cured using a heating means 16 which is a heat source, it is not necessary to use an adhesive that is transparent to the ultraviolet wavelength region, as in conventional methods. Furthermore, in the lens module manufacturing method according to this technology, an adhesive with low transparency in the ultraviolet wavelength region can be used as the thermosetting adhesive, and by using such a thermosetting adhesive, for example, the heating time by the heating means 16 can be controlled to allow heat to reach deeper parts such as the thermosetting adhesives 10d and 10e. In addition, since it is not necessary to use an adhesive that is transparent to the ultraviolet wavelength region in the lens module manufacturing method according to this technology, it is possible to impart light-shielding properties to the thermosetting adhesive.

[0033] In step C1, pre-curing the thermosetting adhesives 10d and 10e means curing them to the extent that the focus between the lens 5 and the image sensor 4 of the joint 15 formed in step B1 does not shift. For example, the adhesive strength of the thermosetting adhesives 10d and 10e constituting the joint 15 after pre-curing in step C1 should be 0.3 MPa or higher, or it may be 2.0 MPa or higher.

[0034] In step C1, a heating means 16 is used to heat the thermosetting adhesives 10d and 10e in the joint 15 in a spot-like manner from nearby. By using such a heating means 16, sufficient adhesive strength can be obtained after the pre-curing of the thermosetting adhesives 10d and 10e in the connecting body 15, and damage to the components constituting the connecting body 15 can be reduced.

[0035] The heating means 16 can be one that can heat an area within a few centimeters in diameter from a short distance to the thermosetting adhesives 10d and 10e in the bonded body 15. The heating means 16 can be, for example, a spot heater, specifically an irradiation device using an infrared lamp as a spot light source, or a linear irradiation device using a xenon lamp as a spot light source. Here, "short distance" means, for example, the irradiation distance of the heating means 16, that is, it is preferable that the distance between the light source of the heating means 16 and the thermosetting adhesives 10d and 10e is within a few centimeters. As an example, in step C1, when an irradiation device using a xenon lamp as a spot light source is used as the heating means 16, it is preferable to irradiate the bonded body 15 from the outside with light from the xenon lamp so that the distance between the xenon lamp and the thermosetting adhesives 10d and 10e is within 5 cm.

[0036] The spot diameter of the heating means 16 can be appropriately selected according to the application of the lens module 1, and can be, for example, within a few centimeters. For example, the spot diameter of the heating means 16 can be about 0.5 to 2 cm for automotive lens modules (camera modules) and about 0.5 to 1 cm for smartphone lens modules.

[0037] As one embodiment of step C1, as shown in Figure 4, a method is used in which the thermosetting adhesives 10d and 10e constituting the joint 15 are spot-heated and partially cured by irradiating them with light from an irradiation device using a xenon lamp as a spot light source from the outside (side) of the joint 15.

[0038] Here, the xenon lamp is a light source (UV-IR light source) with wavelengths in the ultraviolet and infrared regions. By using a xenon lamp as the heating means 16, even when heating is performed from the outside of the connector 15, the infrared rays (heat) irradiated from the xenon lamp can sufficiently reach the inside of the thermosetting adhesives 10d and 10e (the thermosetting adhesives 10d and 10e on the image sensor 4 side in Figure 4). In addition, the ultraviolet rays contained in the light irradiated from the xenon lamp are easily absorbed by the surface of the thermosetting adhesives 10d and 10e, which can promote the thermal reaction on the surface of the thermosetting adhesive 10d. Therefore, by using an irradiation device with a xenon lamp as a spot light source, the surface and interior of the thermosetting adhesives 10d and 10e can be heated more, thereby further improving the adhesive strength of the thermosetting adhesives 10d and 10e after partial curing.

[0039] The irradiation conditions of the xenon lamp, such as applied voltage, pulse width, irradiation time, irradiation distance (distance between the light source and the thermosetting adhesives 10d and 10e), and irradiation energy, can be arbitrarily set.

[0040] In step C1, when a xenon lamp is used as the heating means 16, it is preferable to use blackened thermosetting adhesives 10d and 10e in order to increase the efficiency of absorbing light from the xenon lamp into the thermosetting adhesives 10d and 10e.

[0041] As shown in Figure 4, when using an irradiation device with a xenon lamp as a spot light source to spot-heat the thermosetting adhesives 10d and 10e in the joint 15 from the vicinity, for example, it is possible to cure the thermosetting adhesive 10d on the heated side (outer side) until sufficient temporary fixing strength is obtained, while leaving the thermosetting adhesive 10d on the opposite side from the heated side almost uncured.

[0042] The heating conditions in step C1 can be appropriately set according to, for example, the components of the thermosetting adhesive 10d, the desired curing rate, the type of heating means 16, etc. The heating temperature in step C1 can be, for example, 80°C or higher, 90°C or higher, or 100°C or higher. The heating time in step C1 can be, for example, 1 second or more, 2 seconds or more, 3 seconds or more, 4 seconds or more, 8 seconds or more, or 12 seconds or more.

[0043] [Process D1] Figure 5 is a perspective view illustrating an example of step D1 in the manufacturing method of a lens module. In step D1, the bonded body 15 obtained in step C1 is heated to further cure the curable adhesives 10d and 10e. In step D1, for example, the thermosetting adhesives 10d and 10e are completely cured. The heating in step D1 can be carried out using an oven 17, for example, as shown in Figure 5. By performing step D1, a lens module 1 as shown in Figure 1 is obtained.

[0044] The heating conditions in step D1 can be appropriately set according to, for example, the components of the thermosetting adhesives 10d and 10e, the desired curing rate, etc. The heating conditions in step D1 can be, for example, 70°C or higher, 80°C or higher, 90°C or higher, or 100°C or higher. The heating time in step D1 can be determined according to the heating temperature, and can be shortened as the heating temperature increases. The heating conditions in step D1 can be, for example, 80°C for 1 hour, 100°C for 30 minutes, or 120°C for 5 minutes.

[0045] As described above, in the lens module manufacturing method according to this technology, in step C1, for example, the thermosetting adhesives 10d and 10e in the joint 15 are partially cured using a heating means 16 that can heat them spot by proximity, thereby obtaining sufficient adhesive strength of the thermosetting adhesives 10d and 10e after partial curing.

[0046] In the above explanation, it was assumed that the thermosetting adhesives 10d and 10e were pre-cured using the heating means 16, but the method is not limited to this example. The thermosetting adhesive 10d may be pre-cured only, or the thermosetting adhesive 10e may be pre-cured only. In step C1, when pre-curing the thermosetting adhesives 10d and 10e, multiple heating means 16 may be used to pre-cure the thermosetting adhesives 10d and 10e simultaneously, or the thermosetting adhesives 10d and 10e may be pre-cured sequentially, or the degree of pre-curing of the thermosetting adhesives 10d and 10e may be varied.

[0047] Furthermore, the cured products 14a to 14c of the thermosetting adhesive shown in Figure 1, and the thermosetting adhesives 10a to 10c shown in Figures 2 to 4, are not limited to thermosetting adhesives. For example, UV-curing adhesives or UV-curable and thermosetting one-component adhesives may also be used.

[0048] [Second Embodiment] Figure 6 is a cross-sectional view showing an example of a lens module obtained by the manufacturing method of the lens module according to this technology. The lens module 31 comprises a flexible substrate 2, a circuit board 3, an image sensor 4, a lens 32, a lens barrel 33, and a housing 34. In the lens module 31, the focal length between the lens 32 and the image sensor 4 placed on the circuit board 3 is fixed by cured thermosetting adhesive products 14f and 14g. In the lens module 31, components identical to those in the lens module 1 described above are denoted by the same reference numerals and their descriptions are omitted.

[0049] Lens 32, like lens 5, has multiple optical elements and is designed to collect light from the subject. Lens 32 is mounted on lens barrel 33. Lens 32 can be made of, for example, glass, plastic, or the like.

[0050] The lens barrel 33 is a lens barrel for holding the lens 32 and is configured, for example, in a cylindrical shape. The lens barrel 33 is fixed to the housing 34 by a cured product 14g of thermosetting adhesive. The maximum diameter of the lens barrel 33 is approximately the same as the maximum diameter of the housing 34. In addition, a portion of the lens barrel 33 is formed to be smaller than the diameter of the housing 34. This portion of the lens barrel 33 that is formed to be smaller than the diameter of the housing 34 is located inside the housing 34.

[0051] The housing 34 is a casing for holding the lens barrel 33 and is cylindrical in shape. One end of the housing 34 is fixed to the lens barrel 33 by a cured product 14g of thermosetting adhesive, and the other end of the housing 34 is fixed to the circuit board 3 by a cured product 14f of thermosetting adhesive.

[0052] An example of a method for manufacturing the lens module 31 will be described. The method for manufacturing the lens module 31 includes the following steps A2, B2, C2, and D2.

[0053] [Process A2] Figure 7 is a perspective view illustrating an example of step A2 of the manufacturing method of the lens module 31. Figure 8 is a cross-sectional view illustrating an example of step A2 of the manufacturing method of the lens module 31. Step A2 involves applying a thermosetting adhesive between the circuit board 3 on which the image sensor 4 is mounted and the housing 34, and / or between the housing 34 and the lens barrel 33 that holds the lens 32. For example, step A2 includes at least one of applying a thermosetting adhesive 10f to the surface of the circuit board 3 on which the image sensor 4 is mounted, and applying a thermosetting adhesive 10g to the surface of the housing 34 placed on the circuit board 3 on which the image sensor 4 is mounted.

[0054] Furthermore, if the circuit board 3 on which the image sensor 4 is mounted and the housing 34 are fixed in place beforehand, only 10g of thermosetting adhesive needs to be applied in step A2. Also, if, for example, the circuit board 3 on which the image sensor 4 is mounted and the housing 34 are not fixed in place beforehand, both 10f and 10g of thermosetting adhesive should be applied in step A2. Also, if, for example, the housing 34 and the lens barrel 33 that holds the lens 32 are fixed in place beforehand, only 10f of thermosetting adhesive needs to be applied in step A2. The following explanation will use the case where both 10f and 10g of thermosetting adhesive are applied in step A2 as an example. That is, in one example of step A2, the application of 10f of thermosetting adhesive between the circuit board 3 on which the image sensor 4 is mounted and the housing 34, and the application of 10g of thermosetting adhesive between the housing 34 and the lens barrel 33 that holds the lens 32, are included.

[0055] The preferred conditions for the application method of the thermosetting adhesives 10f and 10g are the same as those for the application method of the thermosetting adhesives 10d and 10e in step A1 described above.

[0056] [Process B2] Step B2 involves forming a composite body 30 in which the lens 32 and the image sensor 4 are focused, comprising a circuit board 3 on which the image sensor 4 is mounted, a housing 34, and a lens barrel 33 that holds the lens 32. In Step B2, for example as shown in Figures 7 and 8, the lens barrel 33 that holds the lens 32 is placed on the housing 34 to which 10 g of thermosetting adhesive has been applied, thereby forming a composite body 30 in which the lens 32 and the image sensor 4 are focused. In this way, Step B2 aligns the lens 32 and the image sensor 4.

[0057] [Process C2] Figure 9 is a cross-sectional view illustrating an example of step C2 in the manufacturing method of the lens module 31. In step C2, the thermosetting adhesives 10f and 10g are partially cured using a heating means 16 that can heat them spot by spot from nearby. In this way, step C2 temporarily fixes the joint 30 formed in step B2 in the correct position, that is, with the lens 32 and the image sensor 4 in focus.

[0058] [Process D2] In step D2, the bonded body 30 is heated to further cure the thermosetting adhesives 10f and 10g. By performing step D2, the lens module 31 shown in Figure 6 above is obtained. The preferred range of heating conditions in step D2 is the same as that for step D1 above.

[0059] As described above, the manufacturing method of the lens module according to this technology includes: step A, applying a thermosetting adhesive 10 containing a coloring agent to at least one of the following: between the circuit board 3 on which the image sensor 4 is mounted and the sensor frame 8; between the circuit board 3 on which the image sensor 4 is mounted and the housing 34; between the sensor frame 8 and the optical unit 11 including the lens 5 and the lens housing 13; and between the housing 34 and the lens barrel 33 that holds the lens 32; step B, forming a joint 15 (or joint 30) in which the lens 5 and the image sensor 4 are focused; step C, pre-curing the thermosetting adhesive 10 using a heating means 16 capable of spot heating the thermosetting adhesive 10 from nearby; and step D, heating the joint 15 (or joint 30) to further cure the thermosetting adhesive 10.

[0060] <Thermosetting adhesive> The thermosetting adhesive relating to this technology preferably comprises a cationic curable compound, a thermal cationic curing agent, and a coloring agent, and satisfies at least one of the following conditions 1 to 3. Such a thermosetting adhesive can be used, for example, as the thermosetting adhesive 10d to 10g in the lens module manufacturing method described above. Hereinafter, the thermosetting adhesives 10d to 10g may be collectively referred to as thermosetting adhesive 10.

[0061] Condition 1: The thermosetting adhesive has a light transmittance of 3.0% or less at a wavelength of 800 nm when it is 0.5 mm thick. Condition 2: The thermosetting adhesive has a light transmittance of 0.3% or less at a wavelength of 500 nm when it is 0.5 mm thick. Condition 3: The thermosetting adhesive has a light transmittance of 0.008% or less at a wavelength of 300 nm when it is 0.5 mm thick.

[0062] If the thermosetting adhesive satisfies at least one of conditions 1 to 3, for example, in steps C1 and C2 of the lens module manufacturing method described above, the efficiency of absorbing the heat rays from the heating means 16 into the thermosetting adhesive 10 can be increased, and the heat rays can reach the interior of the thermosetting adhesive 10 more effectively. As a result, for example, in steps C1 and C2 described above, the thermosetting adhesive 10 can be pre-cured more effectively using the heating means 16. Furthermore, by controlling the heating time by the heating means 16 in steps C1 and C2 described above, the thermosetting adhesive 10 can be pre-cured to a deeper level.

[0063] Furthermore, because thermosetting adhesives satisfy at least one of conditions 1 to 3, they have low transmittance in the ultraviolet wavelength range. Therefore, thermosetting adhesives can prevent external light from entering the application area and causing image defects such as ghosting and flare, thus providing good light shielding. In this way, thermosetting adhesives provide good light shielding at the application area and achieve sufficient adhesive strength after partial curing.

[0064] Regarding condition 1, for thermosetting adhesives, the lower the light transmittance at a wavelength of 800 nm when the thickness is 0.5 mm, the more desirable it is in terms of light shielding properties and adhesive strength after partial curing. For example, the light transmittance at a wavelength of 800 nm when the thickness of the thermosetting adhesive is 0.5 mm may be 3.0% or less, 2.0% or less, 1.0% or less, 0.60% or less, 0.50% or less, 0.30% or less, 0.20% or less, or 0.10% or less. Also, the lower limit of the light transmittance at a wavelength of 800 nm when the thickness of the thermosetting adhesive is 0.10% or more, or 0.20% or more.

[0065] Regarding condition 2, for thermosetting adhesives, the lower the light transmittance at a wavelength of 500 nm when the thickness is 0.5 mm, the more desirable it is in terms of light shielding properties and adhesive strength after partial curing. For example, the light transmittance at a wavelength of 500 nm when the thickness of the thermosetting adhesive is 0.3% or less, 0.25% or less, 0.20% or less, 0.15% or less, 0.10% or less, or 0.05% or less when the thickness is 0.5 mm. Also, the lower limit of the light transmittance at a wavelength of 500 nm when the thickness of the thermosetting adhesive is 0.03% or more, or 0.04% or more.

[0066] Regarding condition 3, for thermosetting adhesives, a lower light transmittance at a wavelength of 300 nm when the thickness is 0.5 mm is desirable in terms of light shielding properties and adhesive strength after partial curing. For example, the light transmittance at a wavelength of 300 nm when the thickness of the thermosetting adhesive is 0.008% or less, or even 0.005% or less. Furthermore, the lower limit of the light transmittance at a wavelength of 300 nm when the thickness of the thermosetting adhesive is 0.001% or more.

[0067] From the viewpoint of light shielding properties and adhesive strength after partial curing, thermosetting adhesives preferably satisfy at least two of conditions 1 to 3, and preferably satisfy all of the above conditions 1 to 3. In particular, from the viewpoint of light shielding properties and adhesive strength after partial curing, thermosetting adhesives preferably satisfy all of the following conditions 1A to 3A. Condition 1A: The thermosetting adhesive has a light transmittance of 0.60% or less at a wavelength of 800 nm when it is 0.5 mm thick. Condition 2A: The thermosetting adhesive has a light transmittance of 0.10% or less at a wavelength of 500 nm when it is 0.5 mm thick. Condition 3A: The thermosetting adhesive has a light transmittance of 0.008% or less at a wavelength of 300 nm when it is 0.5 mm thick.

[0068] The method for measuring the light transmittance of thermosetting adhesives is as described in the examples below.

[0069] The thermosetting adhesive is preferably blackened, for example, to satisfy at least one of conditions 1 to 3. Specifically, the thermosetting adhesive may further contain carbon black as a coloring agent, in addition to the cationic curable compound and the thermo-cationic curing agent.

[0070] [Cationic curable compounds] Cationic curable compounds are used as film-forming components. For example, epoxy resins can be used as cationic curable compounds. The epoxy resin may be a monofunctional epoxy compound having one epoxy group per molecule, a difunctional epoxy compound having two epoxy groups per molecule, or a polyfunctional epoxy compound having three or more epoxy groups per molecule.

[0071] The epoxy resin may be solid at room temperature or liquid at room temperature. Room temperature refers to the range of 15 to 25°C as defined in JIS K 0050:2019 (General Rules for Chemical Analysis Methods). The epoxy groups in the epoxy resin may be alicyclic epoxy groups or non-alicyclic epoxy groups.

[0072] Specific examples of epoxy resins include glycidyl ether type epoxy resins and alicyclic epoxy resins. Glycidyl ether type epoxy resins can be appropriately selected depending on the purpose, and for example, bisphenol A type epoxy resin, bisphenol F type epoxy resin, phenol novolac type epoxy resin, cresol novolac type epoxy resin, and ester type epoxy resin can be used. Cyclic epoxy resins can be appropriately selected depending on the purpose, and for example, 3,4-epoxycyclohexylmethyl-3',4'-epoxycyclohexanecarboxylate can be used.

[0073] From the viewpoint of resin properties, it is preferable to use a combination of glycidyl ether type epoxy resin (particularly bisphenol A type epoxy resin) and alicyclic epoxy compound as the epoxy resin.

[0074] The epoxy equivalent of the epoxy resin can be, for example, in the range of 150 to 300 g / eq, or it may be in the range of 180 to 220 g / eq.

[0075] The viscosity of the epoxy resin at 25°C may be 1,000 mPa·s or more, 2,000 mPa·s or more, 5,000 mPa·s or more, 8,000 mPa·s or more, or 10,000 mPa·s or more. Furthermore, the viscosity of the epoxy resin at 25°C may be 20,000 mPa·s or less, 15,000 mPa·s or less, 13,000 mPa·s or less, or 11,000 mPa·s or less.

[0076] Examples of epoxy resin products include Epiclon 850CRP (manufactured by DIC Corporation) and CEL2021P (manufactured by Daicel Corporation). Epoxy resins may be used individually or in combination of two or more types.

[0077] The content of cationic curable compounds in thermosetting adhesives is not particularly limited, but from the viewpoint of adhesive strength after partial curing, it can be, for example, 25% by mass or more, 30% by mass or more, or 35% by mass or more. Furthermore, the upper limit of the content of cationic curable compounds in thermosetting adhesives can be 60% by mass or less, 45% by mass or less, 40% by mass or less, or 38% by mass or less. When thermosetting adhesives contain two or more epoxy resins, it is preferable that the total amount of epoxy resins satisfies the above numerical range.

[0078] Furthermore, when using a combination of a glycidyl ether type epoxy resin and an alicyclic epoxy compound as cationic curable compounds, it is preferable that the amount of glycidyl ether type epoxy resin in the thermosetting adhesive is greater than the amount of alicyclic epoxy compound.

[0079] [Thermal cation curing agent] The thermal cationic curing agent is a curing agent for cationic curable compounds, and it is preferable to use an aluminum chelate-based latent curing agent (aluminum chelate-based curing agent). By using an aluminum chelate-based latent curing agent in this way, the storage stability of the thermosetting adhesive can be improved even if it is a one-component type.

[0080] Examples of aluminum chelating latent curing agents include those in which the aluminum chelating agent has been latently encapsulated by a microencapsulation method. Another example of an aluminum chelating latent curing agent is one in which an aluminum chelating agent is held in a porous resin obtained by interfacial polymerization of a polyfunctional isocyanate compound. Yet another example is one in which an aluminum chelating agent is held in a porous resin obtained by interfacial polymerization of a polyfunctional isocyanate compound and simultaneously by radical polymerization of a polyfunctional radical polymerizable compound in the presence of a radical polymerization initiator. More specifically, an example is one in which the aluminum chelating agent is held in a structure in which a large number of fine pores present in the porous resin matrix.

[0081] The shape of the aluminum chelate-based latent curing agent is, for example, spherical. From the viewpoint of curability and dispersibility, the particle size of the aluminum chelate-based latent curing agent can be 0.5 to 100 μm. Furthermore, from the viewpoint of curability and latent properties, the pore size of the aluminum chelate-based latent curing agent can be 5 to 150 nm.

[0082] Examples of aluminum chelating agents include complex compounds in which three β-ketoenolate anions are coordinated to aluminum, as represented by the following formula A.

[0083] (Formula A) [ka]

[0084] In formula A, R 1 , R 2 and R 3 Each of these independently represents an alkyl group or an alkoxyl group. Examples of alkyl groups include methyl and ethyl groups. Examples of alkoxyl groups include methoxy, ethoxy, and oleyloxy groups.

[0085] Examples of compounds represented by formula A include aluminum tris(acetylacetonate), aluminum tris(ethylacetoacetate), aluminum monoacetylacetonate bis(ethylacetoacetate), and aluminum monoacetylacetonate bis(oleylacetoacetate).

[0086] Details of the aluminum chelate-based latent curing agent can be found, for example, in Japanese Patent Publication No. 2009-197206, which is incorporated herein by reference.

[0087] The amount of thermal cationic curing agent in a thermosetting adhesive can be appropriately selected depending on the purpose. For example, when the total amount of cationic curable compounds in the thermosetting adhesive is 100 parts by mass, the amount can be 1 part by mass or more, 2 parts by mass or more, 3 parts by mass or more, or 4 parts by mass or more. The upper limit of the amount of thermal cationic curing agent can also be 10 parts by mass or less, 8 parts by mass or less, 6 parts by mass or less, or 5 parts by mass when the total amount of cationic curable compounds in the thermosetting adhesive is 100 parts by mass. Furthermore, the amount of thermal cationic curing agent can be in the range of 1 to 10 parts by mass, 2 to 6 parts by mass, or 3 to 5 parts by mass when the total amount of cationic curable compounds in the thermosetting adhesive is 100 parts by mass.

[0088] [Silanol compounds] From the viewpoint of further accelerating the curing reaction of the cationic curable compound, it is preferable for the thermosetting adhesive to contain a silanol compound in addition to the thermocation curing agent. For example, when the thermosetting adhesive contains a glycidyl ether type epoxy resin as the cationic curable compound, using a silanol compound, preferably a sterically hindered silanol compound, allows the thermosetting adhesive to undergo cationic polymerization at a lower temperature and faster curing rate.

[0089] Unlike conventional silane coupling agents that have a trialkoxy group, it is preferable to use a silanol compound that is highly sterically hindrance, specifically an arylsilanol represented by the following formula B.

[0090] (Ar) m Si(OH) n (B)

[0091] In formula B, m is 2 or 3, and the sum of m and n is 4. Therefore, the silanol compound in formula B is either a mono or a diol. The Ar in formula B is an unsubstituted aryl group or a substituted aryl group. Examples of aryl groups include phenyl, naphthyl, anthracenyl, azlenyl, fluorenyl, thienyl, furyl, pyrrolyl, imidazolyl, and pyridyl groups, and the phenyl group is preferred from the viewpoint of availability and cost. The m Ars in formula B may be the same or different, but from the viewpoint of availability, it is preferable that they are all the same.

[0092] If the aryl group in formula B has substituents, it may have 1 to 3 substituents. Also, in formula B, only some of the aryl groups may have substituents. Examples of substituents include electron-donating groups and electron-withdrawing groups. Examples of electron-donating groups include halogen groups such as chloro and bromo; trifluoromethyl group; nitro group; sulfo group; alkoxycarbonyl groups such as carboxyl group, methoxycarbonyl group, and ethoxycarbonyl group; and formyl group. Examples of electron-donating groups include alkyl groups such as methyl, ethyl, and propyl groups; alkoxy groups such as methoxy and ethoxy groups; hydroxyl group; amino group; monoalkylamino group such as monomethylamino group; and dialkylamino group.

[0093] Specific examples of silanol compounds represented by formula B include triphenylsilanol and diphenylsilanol, with triphenylsilanol being preferred.

[0094] Furthermore, if the thermal cationic curing agent is an aluminum chelate-based latent curing agent held in a porous resin obtained by interfacial polymerization of a polyfunctional isocyanate compound and simultaneously radical polymerization of a polyfunctional radical polymerizable compound in the presence of a radical polymerization initiator, then a porous resin in which a silanol compound represented by formula B is held may be used. Details of this embodiment can be found, for example, in the contents of Japanese Patent Application Publication No. 2010-168449, which is incorporated herein by reference.

[0095] The content of silanol compounds in thermosetting adhesives can be appropriately selected depending on the purpose. For example, when the total amount of cationic curable compounds in the thermosetting adhesive is 100 parts by mass, the content can be 1 part by mass or more, 3 parts by mass or more, 5 parts by mass or more, or 6 parts by mass or more. The upper limit of the silanol compound content can be 20 parts by mass or less, 15 parts by mass or less, 10 parts by mass or less, or 8 parts by mass when the total amount of cationic curable compounds in the thermosetting adhesive is 100 parts by mass. The content of silanol compounds can also be in the range of 3 to 10 parts by mass, 3 to 9 parts by mass, or 5 to 8 parts by mass when the total amount of cationic curable compounds in the thermosetting adhesive is 100 parts by mass. One type of silanol compound may be used alone, or two or more types may be used in combination.

[0096] [Other ingredients] In addition to the components described above, the thermosetting adhesive may further contain, as needed, fillers such as silane coupling agents, silica, and mica, and colorants other than carbon black (pigments, dyes). Furthermore, from the viewpoint of light shielding and adhesive strength after partial curing, it is preferable that the thermosetting adhesive has a low content of ultraviolet curing components (e.g., ultraviolet curing resins such as acrylic monomers and photopolymerization initiators). For example, the amount of ultraviolet curing components in the thermosetting adhesive may be 1% by mass or less, 0.1% by mass or less, or substantially 0%. Furthermore, from the viewpoint of preventing the risk of metal corrosion, it is preferable that the amount of organic acid (e.g., photoacid generator) in the thermosetting adhesive is low. For example, it is preferable that the concentration of organic acid in the thermosetting adhesive is less than 100 ppm. The method for measuring the concentration of organic acid in the thermosetting adhesive is the same as the method described in the examples described later.

[0097] Silane coupling agents have the function of initiating cationic polymerization of cationic curable compounds (e.g., epoxy resins) in cooperation with aluminum chelating agents, which are used as thermal cationic curing agents. Therefore, when a thermosetting adhesive contains an aluminum chelating latent curing agent as a thermal cationic curing agent, the curing of the cationic curable compound can be more effectively promoted by using a silane coupling agent in combination.

[0098] The silane coupling agent may have 1 to 3 lower alkoxy groups in its molecule and may also have a group in its molecule that is reactive to the functional group of the cationic curable compound, such as a vinyl group, styryl group, acryloyloxy group, methacryloyloxy group, epoxy group, amino group, mercapto group, etc.

[0099] Specific examples of silane coupling agents include vinyltris(β-methoxyethoxy)silane, vinyltriethoxysilane, vinyltrimethoxysilane, γ-styryltrimethoxysilane, γ-methacryloxypropyltrimethoxysilane, γ-acryloxypropyltrimethoxysilane, β-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane (e.g., 3-glycidoxypropyltrimethoxysilane), γ-glycidoxypropylmethyldiethoxysilane, N-β-(aminoethyl)-γ-aminopropyltrimethoxysilane, N-β-(aminoethyl)-γ-aminopropylmethyldimethoxysilane, γ-aminopropyltriethoxysilane, N-phenyl-γ-aminopropyltrimethoxysilane, γ-mercaptopropyltrimethoxysilane, and γ-chloropropyltrimethoxysilane.

[0100] When a thermosetting adhesive contains a silane coupling agent, the amount of silane coupling agent in the thermosetting adhesive can be in the range of 1 to 300 parts by mass, 1 to 250 parts by mass, 30 to 200 parts by mass, or 60 to 200 parts by mass, based on the total amount of aluminum chelate-based latent curing agent in the thermosetting adhesive being 100 parts by mass. By setting the amount of silane coupling agent within the above ranges, the effects of this technology tend to be more easily obtained. The silane coupling agent may be used alone or in combination of two or more types.

[0101] The silica that can be included in thermosetting adhesives can take various forms, such as spherical or crushed. Specific examples of silica include TS-720 (manufactured by Cabot Carbon Co., Ltd.) and Crystallite VX-S2 (manufactured by Ryusen Co., Ltd.). When a thermosetting adhesive contains silica, the amount of silica in the adhesive can be, for example, in the range of 30-70% by mass, 40-65% by mass, or 50-65% by mass. Silica may be used alone or in combination of two or more types.

[0102] The viscosity of the thermosetting adhesive at 25°C is not particularly limited and may be, for example, 10,000 mPa·s or more, 22,000 mPa·s or more, 23,000 mPa·s or more, 30,000 mPa·s or more, or 35,000 mPa·s or more. Furthermore, the upper limit of the viscosity of the thermosetting adhesive at 25°C may be, for example, 45,000 mPa·s or less, 40,000 mPa·s or less, or 39,000 mPa·s or less. The viscosity of the thermosetting adhesive can be measured by the method described in the examples below.

[0103] The thixotropy ratio of the thermosetting adhesive is not particularly limited, but is preferably in the range of 1.5 to 6. The thixotropy ratio of the thermosetting adhesive can be measured by the method described in the examples below. [Examples]

[0104] The following describes examples of this technology. This technology is not limited to these examples.

[0105] <Manufacturing of aluminum chelate latent curing catalysts> 800 parts by mass of distilled water, 0.05 parts by mass of surfactant (Newlex RT, manufactured by NOF Corporation), and 4 parts by mass of polyvinyl alcohol (PVA-205, manufactured by Kuraray Co., Ltd.) as a dispersant were placed in an interfacial polymerization container equipped with a thermometer and mixed uniformly. To this mixture, an oil phase was added in which 100 parts by mass of ethyl acetate dissolved 100 parts by mass of a 24% by mass isopropanol solution of aluminum monoacetylacetonate bis(ethyl acetoacetate) (Aluminum Chelate D, Kawaken Fine Chemicals Co., Ltd.), 70 parts by mass of a trimethylolpropane (1 mole) adduct of methylenediphenyl-4,4'-diisocyanate (3 moles) as a polyfunctional isocyanate compound (D-109, manufactured by Mitsui Chemicals, Inc.), 30 parts by mass of divinylbenzene (Merck) as a radical polymerizable compound, and 0.3 parts by mass of a radical polymerization initiator (Perloyl L, manufactured by NOF Corporation) was dissolved. After emulsification and mixing using a homogenizer (10000 rpm / 5 min: T-50, manufactured by IKA Japan Co., Ltd.), interfacial polymerization and radical polymerization were carried out at 80°C for 6 hours. After the reaction was complete, the polymerization reaction solution was allowed to cool to room temperature, the polymerization particles were filtered off, and the mixture was air-dried to obtain spherical aluminum chelate latent curing catalysts with a particle size of approximately 2 μm.

[0106] The compounds used in this example are as follows: Epiclon 850CRP: Bisphenol A type epoxy resin, manufactured by DIC Corporation. Epiclon 830CRP: Bisphenol F type epoxy resin, manufactured by DIC Corporation. CEL2021P: Alicyclic epoxy resin, manufactured by Daicel Corporation. Aluminum chelate latent curing catalyst obtained by the method described in paragraph 0105 Amicure PN-23: Curing catalyst (imidazole, anion), manufactured by Ajinomoto Fine Techno Co., Ltd. Triphenylsilanol SR444: Acrylic monomer (trifunctional) PI2074: 4-Methylphenyl-4-(1-methylethyl)phenyliodonium tetrakis(pentafluorophenyl)borate, UV-curing catalyst (cationic type), manufactured by Rhodey Corporation. Irgacure 184D: UV curing catalyst (radical type), manufactured by BASF. KBM-403: Silane coupling agent (3-glycidoxypropyltrimethoxysilane) TS-720: Hydrophobic fine silica powder (manufactured by Cabot Carbon Co., Ltd.) Carbon black (Product name: Carbon 3050B, manufactured by Mitsubishi Chemical Corporation) Crystallite VX-S2: Crystalline silica (crushed), manufactured by Ryusen Co., Ltd. Crystalline silica (spherical), manufactured by Ryusensha.

[0107] The compositions for Experimental Examples 1 to 10 (adhesive 20, described later) were prepared by uniformly mixing each component to the proportions shown in Table 4. In the table, "parts" refers to parts by mass, and "mixing ratio" refers to the proportion (%) of each component in the composition.

[0108] <Viscosity> The viscosity (mPa·s) at 25°C was measured for each composition shown in Table 4. Specifically, compositions were prepared by uniformly mixing each component, and the viscosity at 25°C was measured using a rheometer (instrument name: HAAKE MARS60). The results are shown in Table 4.

[0109] <Chikiso ratio> The thixotropic ratio of each composition shown in Table 4 was determined using the following formula 1.

[0110] V1rpm / V 10 rpm (formula 1)

[0111] In Equation 1, V1rpm represents the viscosity of the composition at 25°C, measured using a rotational viscometer at a rotational speed of 1 rpm. 10The rpm value represents the viscosity of the composition at 25°C, measured at a rotational speed of 10 rpm using a rotational viscometer. More specifically, a "HAAKE MARS60" rotational viscometer manufactured by Thermo ELECTRON CORPORATION was used, and the viscosity of the composition was measured at 25°C using a C20 / 2° cone at a predetermined rotational speed. The results are shown in Table 4. <Temporarily hardening> The adhesive strength of each composition shown in Table 2 during pre-curing was evaluated. Specifically, the adhesive strength during pre-curing by UV irradiation and the adhesive strength during pre-curing by heat (UV-IR) were evaluated.

[0112] (Evaluation of pre-hardening properties due to heat) Figure 10 is a perspective view illustrating the evaluation method for the pre-curing properties of each composition. First, a pair of rectangular adherends (LCP: Liquid Crystal Polymer) 19a and 19b were prepared. As shown in Figure 10(A), 3 mg of adhesive 20 was applied to each side of a pair of opposing sides on the surface of one adherend 19a, and a joint 21 was obtained by placing the other adherend 19b on top of the adherend 19a to which the adhesive 20 had been applied. Next, as shown in Figure 10(B), light was irradiated onto the adhesive 20 from an irradiation device (device name: SPIR (manufactured by USHIO), output 50%) 22 with a xenon lamp as a spot light source from a distance of 2 cm. Since the purpose was to evaluate the pre-curing properties by heat, UV-IR light was irradiated onto the adhesive 20 through a long-pass filter (manufactured by Tokai Corporation) that transmits light in the wavelength range of 900 to 1800 nm. Then, as shown in Figure 10(C), the adhesive strength between adherends 19a and 19b in the joint 21 was measured using a test probe (device name: dage4000Plus, manufactured by Nordson) 23. The results are shown in Table 2.

[0113] (Evaluation of temporary curing properties by UV irradiation) As shown in Figure 10(A), 3 mg of adhesive 20 was applied to each of two opposing sides of the surface of the adherend 19a, and a bonded body 21 was obtained by placing the other adherend 19b on top of the adherend 19a to which the adhesive 20 had been applied. Next, as shown in Figure 10(B), light with a wavelength of 365 nm was applied to the adhesive 20 from an LED irradiation device, with an integrated light intensity of 2000 mW / cm². 2 The adhesive 20 was partially cured by irradiation in such a manner. Then, as shown in Figure 10(C), the adhesive strength between adherends 19a and 19b in the joint 21 was measured using a test probe (device name: dage4000Plus, Nordson) 23. The results are shown in Table 2.

[0114] (Evaluation of hardening properties) For a joint 21 in which adhesive 20 was pre-cured by heat or UV irradiation, the adhesive strength between adherends 19a and 19b after full curing was measured using the same method as for pre-curing. Full curing was performed for 30 minutes using an oven at 100°C. The results are shown in Table 2.

[0115] <Hardness> The hardness of each composition in its cured state was measured. Specifically, the durometer D hardness was measured using a durometer hardness tester (Type D) in accordance with the method compliant with JIS K 6253. The results are shown in Table 4. In Table 4, for example, D90 indicates that the measured durometer D hardness was 90.

[0116] <Transmittance> The transmittance of each composition was measured. Specifically, the transmittance at wavelengths of 800 nm, 500 nm, and 300 nm was measured when the composition was 0.5 mm thick. The results are shown in Table 1. Figure 11 is a graph showing the measured transmittance results for compositions in Experimental Examples 6, 7, and 10 of Table 1. In Figure 11, the horizontal axis represents wavelength (nm), and the vertical axis represents transmittance (%). In Figure 11, the solid line A represents the measured transmittance results for compositions in Experimental Examples 6 and 7, and the dashed line B represents the measured transmittance results for composition in Experimental Example 10.

[0117] <Metal corrosion (effect of organic acids)> The risk of metal corrosion due to organic acids was evaluated for each composition. The results are shown in Table 3. In Table 3, "○" indicates that the risk of metal corrosion due to organic acids is low and the organic acid concentration is less than 100 ppm (OK), while "×" indicates that there is a risk of metal corrosion due to organic acids and the organic acid concentration is 100 ppm or higher (NG). Specifically, samples were prepared by irradiating each composition for 4 seconds using an irradiation device with a xenon lamp as a spot light source (device name: SPIR, manufactured by USHIO, output 50%), and then curing it in a constant temperature bath at 100°C for 30 minutes. Approximately 0.2 g of this sample was scraped off, placed in a 50 ml PP (polypropylene) container with 10 mL of ultrapure water, and left in a 100°C oven for 20 hours to obtain the sample. The organic acid concentration of this sample was analyzed by ion chromatography.

[0118] [Table 1]

[0119] [Table 2]

[0120] [Table 3]

[0121] [Table 4]

[0122] As shown in Table 1, the compositions of Experimental Examples 6-8 were found to satisfy conditions 1-3 described above. On the other hand, as shown in Table 1, the compositions of Experimental Examples 9 and 10 were found not to satisfy conditions 1-3 described above. From the results shown in Table 1, it was found that the light transmittance of the thermosetting adhesive can be adjusted by changing the amount of coloring agent (carbon black) in the thermosetting adhesive, and that a thermosetting adhesive that satisfies conditions 1-3 described above can be obtained.

[0123] As shown in Table 2, it was found that the compositions of Experimental Examples 3, 5-9 achieved sufficient adhesive strength after pre-curing when a heating method capable of spot heating from nearby was used. On the other hand, it was found that the compositions of Experimental Examples 1, 2, and 10 did not achieve sufficient adhesive strength after pre-curing when a heating method capable of spot heating from nearby was used. Furthermore, the adhesive strength of the composition of Experimental Example 9 can be increased after pre-curing by irradiating it with light for a long time from an irradiation device 22 using a xenon lamp as a spot light source. In other words, when using the composition of Experimental Example 9, it is necessary to irradiate it with light for a long time from an irradiation device 22 using a xenon lamp as a spot light source, which raises concerns about increased damage to the adherend and longer cycle times, but it was found that sufficient adhesive strength can be obtained after pre-curing.

[0124] As shown in Table 3, the compositions of Experimental Examples 5-10 were found to have a low risk of metal corrosion. This is likely because the compositions of Experimental Examples 5-10 did not contain cationic UV curing catalysts.

[0125] As shown in Table 4, the compositions of Experimental Examples 3, 5 to 9 were found to have a viscosity in the range of 23,000 to 38,000 mPa·s at 25°C, satisfy the thixotropy ratio range of 1.5 to 6 mentioned above, and have a durometer D hardness of 94. [Explanation of Symbols]

[0126] 1 Lens module, 2 Flexible substrate, 3 Circuit board, 4 Image sensor, 5 Lens, 6 Lens barrel, 7 Housing, 8 Sensor frame, 9 IR cut filter, 10d, 10e, 10f, 10g Thermosetting adhesive, 11 Optical unit, 12 Sensor unit, 13 Lens housing, 14 Cured product of thermosetting adhesive, 15 Assembled body, 16 Heating means, 17 Oven, 19 Adhesion substrate, 20 Adhesive, 21 Assembled body, 22 Irradiation device, 23 Test probe, 30 Assembled body, 31 Lens module, 32 Lens, 33 Lens barrel, 34 Housing

Claims

1. Step A involves applying a thermosetting adhesive containing a coloring agent to at least one of the following: between the circuit board on which the image sensor is mounted and the sensor frame; between the circuit board on which the image sensor is mounted and the housing; between the sensor frame and the optical unit including the lens and the lens housing; and between the housing and the lens barrel that holds the lens. Step B involves forming a composite body in which the above lens and the above image sensor are in focus, Step C involves pre-curing the above-mentioned thermosetting adhesive using a xenon lamp having wavelengths in the ultraviolet and infrared regions, as a heating means that allows for spot heating from nearby, Step D involves heating the above-mentioned joint to further cure the thermosetting adhesive. A method for manufacturing a lens module having

2. Step A involves applying a thermosetting adhesive containing a coloring agent to at least one of the following: between the circuit board on which the image sensor is mounted and the sensor frame; between the circuit board on which the image sensor is mounted and the housing; between the sensor frame and the optical unit including the lens and the lens housing; and between the housing and the lens barrel that holds the lens. Step B involves forming a composite body in which the above lens and the above image sensor are in focus, Step C involves pre-curing the above-mentioned thermosetting adhesive using a heating means that allows for spot heating from nearby, Step D involves heating the above-mentioned joint to further cure the thermosetting adhesive. It has, The above thermosetting adhesive is a method for manufacturing a lens module that satisfies all of the following conditions 1A to 3A. Condition 1A: The above thermosetting adhesive has a light transmittance of 0.60% or less at a wavelength of 800 nm when it is 0.5 mm thick. Condition 2A: The above thermosetting adhesive has a light transmittance of 0.10% or less at a wavelength of 500 nm when it is 0.5 mm thick. Condition 3A: The above thermosetting adhesive has a light transmittance of 0.008% or less at a wavelength of 300 nm when it is 0.5 mm thick.

3. The above thermosetting adhesive satisfies at least one of the following conditions 1 to 3, the method for manufacturing a lens module according to claim 1. Condition 1: The above thermosetting adhesive has a light transmittance of 3.0% or less at a wavelength of 800 nm when it is 0.5 mm thick. Condition 2: The above thermosetting adhesive has a light transmittance of 0.3% or less at a wavelength of 500 nm when it is 0.5 mm thick. Condition 3: The above thermosetting adhesive has a light transmittance of 0.008% or less at a wavelength of 300 nm when it is 0.5 mm thick.

4. The above thermosetting adhesive satisfies all of the following conditions 1A to 3A, the method for manufacturing a lens module according to claim 1. Condition 1A: The above thermosetting adhesive has a light transmittance of 0.60% or less at a wavelength of 800 nm when it is 0.5 mm thick. Condition 2A: The above thermosetting adhesive has a light transmittance of 0.10% or less at a wavelength of 500 nm when it is 0.5 mm thick. Condition 3A: The above thermosetting adhesive has a light transmittance of 0.008% or less at a wavelength of 300 nm when it is 0.5 mm thick.

5. In step C described above, the thermosetting adhesive is partially cured by irradiating the outside of the joint with light from an irradiation device using a xenon lamp as a spot light source, according to any one of claims 1 to 4.

6. A method for manufacturing a lens module according to any one of claims 1 to 5, wherein the spot diameter of the heating means is in the range of 0.5 to 2.0 cm.

7. In step C described above, the distance between the xenon lamp and the thermosetting adhesive is 5 cm or less, and light from an irradiation device using the xenon lamp as a spot light source is irradiated from the outside of the bonded body, as described in claim 5.

8. A method for manufacturing a lens module according to any one of claims 1 to 7, wherein the adhesive strength of the thermosetting adhesive after pre-curing in step C is 0.3 MPa or more.

9. A method for manufacturing a lens module according to any one of claims 1 to 8, wherein the above-mentioned coloring agent is carbon black.

10. Step A above is step A2, in which a thermosetting adhesive is applied between the circuit board on which the image sensor is mounted and the housing, and / or between the housing and the lens barrel that holds the lens. The method for manufacturing a lens module according to claim 1 or 2, wherein step B is step B2 of forming a composite body comprising a circuit board on which an image sensor is mounted, a housing, and a lens barrel for holding a lens, wherein the lens and the image sensor are in focus.

11. A thermosetting adhesive for fixing at least one of the following: between a circuit board on which an image sensor is mounted and a sensor frame; between a circuit board on which an image sensor is mounted and a housing; between a sensor frame and an optical unit including a lens and a lens housing; and between a housing and a lens barrel that holds a lens, Cationic curable compounds, Thermal cation curing agent, Contains coloring agents, A thermosetting adhesive that satisfies at least one of the following conditions 1 to 3. Condition 1: The thermosetting adhesive has a light transmittance of 3.0% or less at a wavelength of 800 nm when it is 0.5 mm thick. Condition 2: The thermosetting adhesive has a light transmittance of 0.3% or less at a wavelength of 500 nm when it is 0.5 mm thick. Condition 3: The thermosetting adhesive has a light transmittance of 0.008% or less at a wavelength of 300 nm when it is 0.5 mm thick.

12. A thermosetting adhesive for fixing at least one of the following: between a circuit board on which an image sensor is mounted and a sensor frame; between a circuit board on which an image sensor is mounted and a housing; between a sensor frame and an optical unit including a lens and a lens housing; and between a housing and a lens barrel that holds a lens, Cationic curable compounds, Thermal cation curing agent, Contains coloring agents, A thermosetting adhesive that satisfies all of the following conditions 1A to 3A. Condition 1A: The thermosetting adhesive has a light transmittance of 0.60% or less at a wavelength of 800 nm when it is 0.5 mm thick. Condition 2A: The thermosetting adhesive has a light transmittance of 0.10% or less at a wavelength of 500 nm when it is 0.5 mm thick. Condition 3A: The thermosetting adhesive has a light transmittance of 0.008% or less at a wavelength of 300 nm when it is 0.5 mm thick.

13. The thermosetting adhesive according to claim 11 or 12, wherein the coloring agent is carbon black.

14. The thermosetting adhesive according to any one of claims 11 to 13, wherein the cationic curable compound comprises a bisphenol A type epoxy resin and an alicyclic epoxy resin.

15. The thermosetting adhesive according to any one of claims 11 to 14, wherein the above-mentioned thermal cationic curing agent includes an aluminum chelating curing agent.

16. A thermosetting adhesive according to any one of claims 11 to 15, further comprising a silanol compound.

17. A thermosetting adhesive according to any one of claims 11 to 16, further comprising a silane coupling agent.

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