Two-pack curable resin composition, method for manufacturing camera module, and camera module

Abstract

A two-pack type curable resin composition according to one embodiment of the present invention is filled in a space on the rear surface side of an imaging substrate of a camera module having an imaging substrate on the surface of which an imaging element is mounted and a case for accommodating the imaging substrate, the two-pack type curable resin composition containing a main agent and a curing agent, the main agent contains: a first matrix resin comprising a polysiloxane in which a vinyl group is bonded to silicon; and a first thermally conductive filler; the curing agent contains: a second matrix resin comprising a polysiloxane in which a vinyl group is bonded to silicon at the terminal; a second thermally conductive filler; and a crosslinking agent comprising a polysiloxane in which hydrogen is bonded to silicon at the terminal, the shear rate of the main agent and the curing agent being 10 s-1, the viscosity at a temperature of 23 DEG C being 10 Pa.s to 50 Pa.s, the thermal conductivity after curing being 1.5 W / m.K to 5.0 W / m.K, and the Asker C hardness after curing being 8 to 50.

Description

Technical Field

[0001] The present invention relates to a two-component curable resin composition, a method for producing a camera module, and a camera module. Background Art

[0002] Camera modules are installed in a wide variety of devices. Furthermore, as camera modules become smaller and offer higher image quality, heat dissipation from imaging elements has become increasingly important. A known technique involves placing a soft heat sink on the backside of a substrate on which an imaging element is mounted, dissipating heat to components located on the backside of the substrate (see, for example, Patent Document 1).

[0003] Prior art literature

[0004] Invention patent documents

[0005] Patent Document 1: Japanese Patent Application Publication No. 2020-155985 Summary of the Invention

[0006] Problems to be solved by the invention

[0007] When using a heat sink, a member with excellent thermal conductivity that receives heat from the substrate through the heat sink must be placed opposite the substrate. This may result in insufficient heat dissipation using the heat sink or complicate the device configuration.

[0008] An object of the present invention is to provide a camera module with high heat dissipation performance.

[0009] Means for solving problems

[0010] The inventors of the present invention have devised a method for producing a camera module with high heat dissipation properties by filling the interior of a camera module with a curable resin composition having high thermal conductivity instead of a heat sink, and have completed the present invention.

[0011] A two-component curable resin composition according to one embodiment of the present invention is filled in a space on the back side of an imaging substrate of a camera module. The camera module includes the imaging substrate on which an imaging element is mounted and a housing for accommodating the imaging substrate. The two-component curable resin composition comprises a main component and a curing agent. The main component comprises: a first matrix resin composed of polysiloxane having vinyl groups bonded to silicon; and a first thermally conductive filler. The curing agent comprises: a second matrix resin composed of polysiloxane having vinyl groups bonded to silicon terminals; a second thermally conductive filler; and a crosslinking agent composed of polysiloxane having hydrogen bonded to silicon terminals. The shear rate of the main component and the curing agent is 10 s -1The viscosity at a temperature of 23° C. is 10 Pa·s or more and 50 Pa·s or less, the thermal conductivity after curing is 1.5 W / m·K or more and 5.0 W / m·K or less, and the Asker C hardness after curing is 8 or more and 50 or less.

[0012] In the two-component curable resin composition, the first base resin and the second base resin may be dimethylpolysiloxane having a vinyl group bonded to the silicon terminal.

[0013] In the two-component curable resin composition, the total content of the first thermally conductive filler and the second thermally conductive filler in the entire composition may be 75% by mass or more and 95% by mass or less.

[0014] Another embodiment of the present invention is a method for manufacturing a camera module, wherein the camera module includes an imaging substrate having an imaging element mounted on its surface and a housing for accommodating the imaging substrate. The method for manufacturing the camera module includes: a step of filling the above-mentioned two-component curable resin composition into the space on the back side of the imaging substrate; and a step of heating the two-component curable resin composition.

[0015] A camera module according to another embodiment of the present invention includes an imaging substrate having an imaging element mounted on its surface and a housing for accommodating the imaging substrate. A thermally conductive resin composition is filled in a space on the back side of the imaging substrate. The thermally conductive resin composition contains a matrix resin composed of polysiloxane and a thermally conductive filler, has a thermal conductivity of 1.5 W / m·K to 5.0 W / m·K, and an Asker C hardness of 8 to 50.

[0016] The camera module may further include a back substrate disposed at a distance from the back side of the imaging substrate, and the outer periphery of the gap between the imaging substrate and the back substrate may be sealed by the housing.

[0017] Effects of the Invention

[0018] According to the present invention, a camera module with high heat dissipation performance can be provided. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 This is a schematic cross-sectional view showing the configuration of a camera module according to one embodiment of the present invention.

[0020] Explanation of symbols

[0021] 1 Camera module, 10 Lens unit, 11, 12 Lenses, 13 Lens barrel, 20 Image pickup substrate, 21 Image pickup element, 30 Back substrate, 31 Opening, 40 Housing, 41 Outer wall, 42 Substrate seat, 43 Opening, 50 Thermally conductive resin composition. DETAILED DESCRIPTION

[0022] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. Figure 1 It is a schematic cross-sectional view showing the configuration of a camera module 1 according to one embodiment of the present invention.

[0023] The camera module 1 includes a lens unit 10 , an imaging substrate 20 , a back substrate 30 , a housing 40 , and a thermally conductive resin composition 50 .

[0024] The lens unit 10 is an optical system that includes one or more lenses 11 and 12 and forms an image of light incident from a subject. The lens unit 10 can be formed by lenses directly held in the housing 40, or it can include a lens barrel 13 as shown in the figure, which holds the lenses 11 and 12 and is attached to the housing 40.

[0025] An imaging element 21 is mounted on the surface of the imaging substrate 20. The imaging element 21 converts the image of the subject formed by the lens unit 10 into an electrical signal (image data). As the imaging element 21, a two-dimensional imaging element such as a CMOS image sensor is preferably used.

[0026] The imaging substrate 20 is held perpendicular to the optical axis of the lens unit 10 by the housing 40 and is positioned so that the lens unit 10 forms an image of the subject on the imaging surface of the imaging element 21. To efficiently transfer heat generated in the imaging element 21 to the rear surface, the imaging substrate 20 is preferably a substrate with high thermal conductivity, such as a metal substrate, or a substrate having a heat transfer structure, such as a heat dissipation hole.

[0027] While the back substrate 30 is not particularly limited, it can be a substrate having, for example, a drive circuit for driving the imaging element 21, a signal processing circuit for processing image data generated by the imaging element 21, and the like. The back substrate 30 is arranged with a gap between it and the imaging substrate 20. Preferably, the back substrate 30 and the imaging substrate 20 are held parallel to each other. Furthermore, preferably, the back substrate 30 has an outer diameter substantially identical to that of the imaging substrate 20 and is arranged side by side in the optical axis direction. The lens unit 10 including the imaging substrate 20 and the back substrate 30 can reduce its own occupied area when viewed in the optical axis direction.

[0028] The back substrate 30 may also have an opening 31 for filling the space between the back substrate 30 and the imaging substrate 20 with the thermally conductive resin composition 50. The diameter of the opening 31 of the back substrate 30 can be set to, for example, 2 mm or more and 4 mm or less. This allows a tubular nozzle to be inserted into the opening 31 to fill the space between the imaging substrate 20 and the back substrate 30 with the thermally conductive resin composition 50.

[0029] The housing 40 houses the imaging substrate 20 and the back substrate 30. To release internal heat to the environment, the housing 40 is preferably formed of an aluminum alloy, a magnesium alloy, or the like having high thermal conductivity.

[0030] The housing 40 includes an outer wall portion 41 that surrounds the outer periphery of the imaging substrate 20 and the rear substrate 30 and seals the outer periphery of the gap between the imaging substrate 20 and the rear substrate 30. The housing 40 may also include a substrate seat portion 42 that abuts the outer periphery of the surface of the imaging substrate 20 and positions the imaging substrate 20. Furthermore, by enabling screw fastening, the imaging substrate 20 is pressed against the substrate seat portion 42, thereby accurately positioning the imaging substrate 20 and, consequently, the imaging element 21. Furthermore, to prevent the thermally conductive resin composition 50 from flowing toward the surface of the imaging substrate 20, the substrate seat portion 42 preferably abuts the imaging substrate 20 continuously throughout its entire circumference. Furthermore, the housing 40 may also include an opening 43 concentric with the opening 31 for filling the space between the imaging substrate 20 and the rear substrate 30 with the thermally conductive resin composition 50.

[0031] The thermally conductive resin composition 50 fills the space behind the imaging substrate 20. More specifically, the thermally conductive resin composition 50 preferably fills the entire space defined by the imaging substrate 20, the back substrate 30, and the outer wall 41. It can also fill at least a portion of the space behind the back substrate 30. The thermally conductive resin composition 50 primarily conducts heat from the imaging substrate 20 to the outer wall 41. As a result, the camera module 1 can efficiently dissipate heat generated by the imaging element 21 from the housing 40 to the environment.

[0032] The thermally conductive resin composition 50 can be formed by curing a two-component curable resin composition comprising a low-viscosity base and a curing agent. The two-component curable resin composition preferably reacts completely with heating. Specifically, the camera module 1 can be manufactured using a camera module manufacturing method comprising the following steps: filling the space on the back side of the imaging substrate 20 with the two-component curable resin composition; and heating the filled two-component curable resin composition.

[0033] The filling rate of the two-component curable resin composition during the manufacturing process of the camera module 1 is preferably 0.1 g / s to 0.8 g / s. Furthermore, the heating temperature of the two-component curable resin composition is preferably 80°C to 150°C, and the heating time of the two-component curable resin composition is preferably 15 minutes to 60 minutes.

[0034] The two-component curable resin composition that forms the thermally conductive resin composition 50 upon curing is one embodiment of the two-component curable resin composition of the present invention. The main component of the two-component curable resin composition includes a first matrix resin composed of a polysiloxane having vinyl groups bonded to silicon, and a first thermally conductive filler. Furthermore, the curing agent of the two-component curable resin composition includes a second matrix resin composed of a polysiloxane having vinyl groups bonded to silicon, a second thermally conductive filler, and a crosslinking agent composed of a polysiloxane having hydrogen bonded to the silicon terminals.

[0035] The first and second base resins may be the same resin or different resins that are compatible. Preferably, the first and second base resins have a polysiloxane backbone and a vinyl group at one end (at least one end) that is reactive with a crosslinking agent. Preferably, the backbone of the first and second base resins is dimethylpolysiloxane. Including such a base resin can improve the filling properties of the two-component curable resin composition.

[0036] The main chain of the crosslinking agent is preferably dimethylpolysiloxane, similarly to the first and second matrix resins. The content of the crosslinking agent in the total of the first and second matrix resins can be, for example, 0.5% by mass or more and 2.0% by mass or less.

[0037] The base component of a two-component curable resin composition preferably further contains a catalyst to accelerate the reaction of the crosslinking agent contained in the curing agent. On the other hand, the curing agent preferably contains a stabilizer to inhibit the crosslinking reaction during storage. Furthermore, the base component and curing agent may further contain additives such as a surface treatment agent, such as dimethylpolysiloxane having three methoxysilyl groups bonded to the terminal silicon.

[0038] Alumina, aluminum nitride, boron nitride, and the like can be used as the thermally conductive fillers (first and second thermally conductive fillers) in the thermally conductive resin composition 50. The first and second thermally conductive fillers may be the same filler or different fillers. The lower limit of the thermally conductive filler content in the thermally conductive resin composition 50 (the total content of the first and second thermally conductive fillers relative to the total amount of the two-component curable resin composition) is preferably 75% by mass, more preferably 80% by mass. On the other hand, the upper limit of the thermally conductive filler content in the thermally conductive resin composition 50 is preferably 95% by mass, more preferably 90% by mass. By setting the thermally conductive filler content above this lower limit, sufficient thermal conductivity can be ensured. Furthermore, by setting the thermally conductive filler content below this upper limit, the thermally conductive resin composition 50 can be properly filled into the space on the back side of the imaging substrate 20.

[0039] The lower limit of the thermal conductivity of the thermally conductive resin composition 50 after curing is preferably 1.5 W / m·K, and more preferably 2.0 W / m·K. On the other hand, the upper limit of the thermal conductivity of the thermally conductive resin composition 50 is preferably 5.0 W / m·K, and more preferably 4.0 W / m·K. By setting the thermal conductivity of the thermally conductive resin composition 50 to be greater than the lower limit, the heat of the imaging element 21 can be efficiently transferred to the housing 40. In addition, by setting the thermal conductivity of the thermally conductive resin composition 50 to be less than the upper limit, a decrease in filling property can be prevented. It should be noted that the thermal conductivity is measured in accordance with ASTM-E1530 (steady-state heat flow meter method). As a specific example, the thermal conductivity can be measured at 30°C using a thermal conductivity measuring device "GH-1" manufactured by ULVAC RIKEN Co., Ltd. on a test piece having a thickness of 4 mm and a size of 25×25 mm.

[0040] The lower limit of the Asker C hardness of the cured thermally conductive resin composition 50 is preferably 8, more preferably 10. On the other hand, the upper limit of the Asker C hardness of the thermally conductive resin composition 50 is preferably 50, more preferably 30, and even more preferably 20. By setting the Asker C hardness of the thermally conductive resin composition 50 to be greater than or equal to the lower limit, the thermally conductive resin composition 50 can be prevented from flowing out of the space on the back side of the imaging substrate 20. Furthermore, by setting the Asker C hardness of the thermally conductive resin composition 50 to be less than or equal to the upper limit, it should be noted that "Asker C hardness" is measured in accordance with ASTM-D2240.

[0041] The main component and curing agent of the two-component curable resin composition are each subjected to a shear rate of 10s -1 , the lower limit of the viscosity at a temperature of 23°C is preferably 10 Pa·s, more preferably 15 Pa·s. On the other hand, the upper limit of the viscosity of the main agent and the curing agent of the two-component curable resin composition is preferably 50 Pa·s, more preferably 40 Pa·s. By setting the viscosity of the main agent and the curing agent of the two-component curable resin composition to be above the lower limit, it is possible to prevent the two-component curable resin composition from flowing out of the space on the back side of the imaging substrate 20 or the sedimentation of the filler. In addition, by setting the viscosity of the main agent and the curing agent of the two-component curable resin composition to be below the upper limit, it becomes easy to fill the space on the back side of the imaging substrate 20 with the two-component curable resin composition. It should be noted that the "viscosity" can be measured at a gap distance of 100 μm using a modular compact rheometer "MCR-102e" from Anton Paar Japan.

[0042] By providing a thermally conductive resin composition 50 that fills the space surrounded by the outer wall portion 41 on the back side of the imaging substrate 20 with the two-liquid curable resin composition described above and solidifies it, even if a back substrate 30 that hinders heat transfer is arranged on the back side of the imaging substrate 20, the camera module 1 can transfer heat efficiently from the imaging substrate 20 to the outer wall portion 41, thereby having excellent heat dissipation and preventing overheating of the imaging element 21.

[0043] While the embodiments of the present invention have been described above, the present invention is not limited to these embodiments and is capable of various modifications and variations. For example, while an embodiment of a camera module including a back substrate has been described as an example of a significant heat dissipation effect based on the present invention, a back substrate is not essential for the camera module of the present invention.

[0044] Example

[0045] Hereinafter, the present invention will be specifically described based on examples, but the present invention is not limited to the following examples.

[0046] Using two-component curable resin compositions with different components, a trial was made with Figure 1 The researchers examined the relationship between the viscosity of the two-component curable resin composition, the thermal conductivity of the cured thermally conductive resin composition, and the Asker C hardness of the cured thermally conductive resin composition, as well as the filling and non-leaching properties of the two-component curable resin composition, the heat dissipation properties of the camera module, and the adhesion between the cured thermally conductive resin composition and the imaging substrate. In this example, the curing conditions were all set at 100°C for 60 minutes.

[0047] The viscosity of the two-component curable resin composition was adjusted by the molecular weight of the matrix resin, the thermal conductivity of the cured thermally conductive resin composition was adjusted by the content of the thermally conductive filler, and the Asker C hardness of the cured thermally conductive resin composition was adjusted by the content of the crosslinking agent.

[0048] The filling performance of the two-component curable resin composition was evaluated by injecting the composition into the housing through a nozzle with an inner diameter of 0.84 mm using a dispenser "TSP-150-T02" from SOSEY and a static mixer "MBH-05-16T" from Sulzer. Filling at a rate of 0.1 g / s or higher was rated as "0" and filling at a rate of less than 0.1 g / s was rated as "X." The non-leaching performance of the two-component curable resin composition was evaluated by heat curing at 100°C for 60 minutes. If the composition did not flow into the gap between the imaging substrate and the housing, the composition was rated as "0"; if it did flow into the gap between the imaging substrate and the housing, the composition was rated as "X." To assess the heat dissipation of the camera module, the module was placed in an ESPEC thermal shock tester, "TSA-203ES." A thermal shock cycle consisting of a low-side temperature of -40°C (holding time 30 minutes) and a high-side temperature of 85°C (holding time 30 minutes) was repeated for 3000 cycles. Samples that maintained the imaging element temperature below 50°C were rated as "0," while samples that exceeded 50°C were rated as "X." To assess the adhesion between the thermally conductive resin composition and the imaging substrate, the module was placed in an ESPEC thermal shock tester, "TSA-203ES." A thermal shock cycle consisting of a low-side temperature of -40°C (holding time 30 minutes) and a high-side temperature of 125°C (holding time 30 minutes) were repeated for 500 cycles. Samples that showed no delamination were rated as "0," while samples that exhibited delamination were rated as "X." Table 1 below summarizes the evaluation conditions and results for the two-component curable resin composition.

[0049] [Table 1]

[0050] Prototype number 1 2 3 4 5 6 Viscosity [Pa·s] 20 60 5 10 80 20 Thermal conductivity [W / m·K] 2.3 2.3 2.3 1.0 6.0 2.3 Asker C hardness 15 15 15 10 25 60 Filling 〇 × 〇 〇 × 〇 Non-leachable 〇 〇 × 〇 〇 〇 heat dissipation 〇 〇 〇 × 〇 〇 Tightness 〇 〇 〇 〇 〇 ×

[0051] As shown above, it was confirmed that by setting the viscosity of the two-component curable resin composition, the thermal conductivity of the cured thermally conductive resin composition, and the Asker C hardness of the cured thermally conductive resin composition within appropriate ranges, and filling the space on the back side of the imaging substrate with the two-component curable resin composition to form a thermally conductive resin composition, a camera module with excellent heat dissipation properties can be obtained.

Claims

1. A two-component curable resin composition, wherein the two-component curable resin composition is filled in a space on the back side of an imaging substrate of a camera module, wherein the camera module comprises the imaging substrate having an imaging element mounted on its surface and a housing for accommodating the imaging substrate. The two-component curable resin composition comprises a main agent and a curing agent. The main agent contains: a first matrix resin composed of polysiloxane having vinyl groups bonded to silicon; and a first thermally conductive filler; and The curing agent contains: a second base resin composed of polysiloxane having vinyl groups bonded to the silicon terminals; a second thermally conductive filler; and A crosslinking agent composed of polysiloxane with hydrogen bonded to the silicon terminal. The shear rate of the main agent and the curing agent is 10s -1 , the viscosity at a temperature of 23°C is 10 Pa·s or more and 50 Pa·s or less, The thermal conductivity after curing is 1.5W / m·K or more and 5.0W / m·K or less. The Asker C hardness after curing is 8 or more and 50 or less.

2. The two-component curable resin composition according to claim 1, wherein The first base resin and the second base resin are dimethylpolysiloxane having a vinyl group bonded to the silicon terminal.

3. The two-component curable resin composition according to claim 1 or 2, wherein The total content of the first thermally conductive filler and the second thermally conductive filler in the entire two-component curable resin composition is 75% by mass or more and 95% by mass or less.

4. A method for manufacturing a camera module, the camera module comprising an imaging substrate having an imaging element mounted on a surface thereof and a housing for accommodating the imaging substrate. The manufacturing method of the camera module comprises: a step of filling the space on the back side of the imaging substrate with the two-component curable resin composition according to claim 1 or 2; and A step of heating the two-component curable resin composition.

5. A camera module comprising: An imaging substrate having an imaging element mounted on its surface; and a housing for accommodating the imaging substrate, The thermally conductive resin composition is filled in the space on the back side of the imaging substrate. The thermally conductive resin composition, Contains a matrix resin composed of polysiloxane and a thermally conductive filler. Thermal conductivity is 1.5 W / m·K or higher and 5.0 W / m·K or lower. The Asker C hardness is 8 or more and 50 or less.

6. The camera module according to claim 5, wherein: The camera module further includes a back substrate disposed at a distance from the back side of the imaging substrate. The outer periphery of the gap between the imaging substrate and the back substrate is closed by the housing.

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