Camera module and method for manufacturing camera module

Abstract

To suppress deformation or breakage of an imaging element due to a stress buffer member in a camera module.SOLUTION: The camera module 100 includes a pedestal 1 having a curved concave surface 2, an imaging element 40 that converts received light into an electric signal, a stress buffering member 30, and a first bonding material 10 that bonds the pedestal and the stress buffering member to each other, wherein the first bonding material, the stress buffering member, and the imaging element are disposed on the pedestal in this order, a coefficient of thermal expansion of the stress buffering member is smaller than a coefficient of thermal expansion of the pedestal and is larger than a coefficient of thermal expansion of the imaging element.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to a camera module and a method for manufacturing the camera module. [Background technology]

[0002] Patent Document 1 discloses an imaging device in which an imaging element is disposed on a support member having a curved concave surface. The imaging element is curved by being disposed on the concave surface. This curvature suppresses field curvature. In this imaging device, a flexible sheet is sandwiched between the support member and the imaging element to absorb thermal stress between the support member and the imaging element. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2005-45151 Summary of the Invention [Problem to be solved by the invention]

[0004] The imaging device disclosed in Patent Document 1 does not take into consideration the thermal expansion coefficient of each component. In particular, since the extensible sheet is made of a material with a relatively high thermal expansion coefficient, there is a risk that the imaging element may be deformed or damaged due to thermal deformation of the extensible sheet in a relatively low or high temperature environment. [Means for solving the problem]

[0005] The present disclosure can be realized in the following forms.

[0006] According to one embodiment of the present disclosure, there is provided a camera module (100). The camera module includes a base (1) having a curved concave surface (2), an imaging element (40) that converts received light into an electrical signal, a stress buffering member (30), and a first bonding material (10) that bonds the base and the stress buffering member, the first bonding material, the stress buffering member, and the imaging element being arranged on the base in this order, and the thermal expansion coefficient of the stress buffering member being smaller than that of the base and larger than that of the imaging element.

[0007] According to the camera module of the above embodiment, the thermal expansion coefficient of the stress buffering member is smaller than that of the base and larger than that of the image sensor, so that the difference in thermal deformation between the base and the stress buffering member and the difference in thermal deformation between the stress buffering member and the image sensor can be reduced compared to a configuration that does not have such a relationship in thermal expansion coefficients. Therefore, even in a relatively high or low temperature environment, deformation or damage to the image sensor due to the difference in thermal deformation between the respective members can be suppressed. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a cross-sectional view of a camera module according to an embodiment of the present disclosure. [Figure 2] 1 is a flowchart showing steps in a manufacturing method of a camera module. DETAILED DESCRIPTION OF THE INVENTION

[0009] A. Implementation: A1. Camera module 100 configuration: The camera module 100 shown in FIG. 1 is a device for converting light captured through a lens (not shown) into an electrical signal. The camera module 100 in this embodiment is used in an imaging device mounted on a vehicle. The camera module 100 includes a base 1, a stress buffering member 30, an imaging element 40, a first bonding material 10, and a second bonding material 20. The first bonding material 10, the stress buffering member 30, the second bonding material 20, and the imaging element 40 are arranged on the base 1 in layers in this order.

[0010] The base 1 supports the stress buffer member 30 and the imaging element 40. The base 1 has a curved concave surface 2. The base 1 is made of resin or metal. The base 1 is placed on the substrate of the imaging device. The thermal expansion coefficient of the base 1 is, for example, 20 ppm / °C or higher.

[0011] The stress buffering member 30 buffers thermal stress on the base 1 and the imaging element 40. In this embodiment, the stress buffering member 30 is made of glass. The stress buffering member 30 is curved due to plastic deformation. The thickness of the stress buffering member 30 is, for example, 10 μm to 30 μm. In this embodiment, the thermal expansion coefficient of the stress buffering member 30 is smaller than that of the base 1 and larger than that of the imaging element 40. The thermal expansion coefficient of the stress buffering member 30 is, for example, 10 ppm / °C or higher.

[0012] The imaging element 40 converts the received light into an electrical signal. The imaging element 40 is made of silicon. The imaging element 40 is curved so as to follow the curved shapes of the concave surface 2 of the base 1 and the stress buffer member 30. The coefficient of thermal expansion of the imaging element 40 is, for example, 5 ppm / °C or less.

[0013] The first bonding material 10 bonds the base 1 and the stress buffer member 30. The first bonding material 10 is, for example, an adhesive or double-sided tape. The adhesive is, for example, an epoxy-based or silicone-based adhesive. The thickness of the first bonding material 10 is, for example, 30 μm to 100 μm. The first bonding material 10 in this embodiment is thicker than the second bonding material 20 described below. The elastic modulus of the first bonding material 10 is, for example, several tens of MPa to several hundreds of MPa. The elastic modulus of the first bonding material 10 in this embodiment is smaller than the elastic modulus of the second bonding material 20 described below. The elastic modulus is measured, for example, by a method in accordance with JIS K 7161.

[0014] The second bonding material 20 bonds the stress buffer member 30 and the imaging element 40. The second bonding material 20 is, for example, an adhesive or double-sided tape. The adhesive is, for example, an epoxy-based adhesive. The thickness of the second bonding material 20 is, for example, 2 μm to 3 μm. The elastic modulus of the second bonding material 20 is, for example, 1 GPa to 3 GPa.

[0015] A2. Manufacturing method of camera module 100: The manufacturing method of the camera module 100 shown in Fig. 2 is carried out as one step for manufacturing an imaging device. As shown in Fig. 2, the first bonding material 10 is attached to the base 1 in step P10.

[0016] In step P20, the stress buffering member 30 is placed on the base 1 to which the first bonding material 10 is attached. The stress buffering member 30 is plastically deformed into a curved shape. As a result, the base 1 and the stress buffering member 30 are bonded together via the first bonding material 10.

[0017] In step P30, the second bonding material 20 is attached to the imaging element 40. In step P30 in Fig. 2, the imaging element 40 has a curved shape, but in reality, it has an external shape like a flat sheet.

[0018] In process P40, the imaging element 40 is placed on the stress buffering member 30. As a result, the stress buffering member 30 and the imaging element 40 are bonded via the second bonding material 20. At this time, the imaging element 40 may be pressed against the stress buffering member 30 by a rod-shaped tool. Alternatively, the imaging element 40 may be pressed against the stress buffering member 30 by gas pressure. This pressing causes the imaging element 40 to bend.

[0019] The camera module 100 manufactured through the above steps P10, P20, P30, and P40 is used to manufacture an imaging device.

[0020] According to the camera module 100 of the embodiment described above, since the stress buffering member 30 is provided, the thermal stress between the base 1 and the imaging element 40 can be buffered.

[0021] Furthermore, according to the camera module 100 of this embodiment, the thermal expansion coefficient of the stress buffering member 30 is smaller than that of the base 1 and larger than that of the imaging element 40. In other words, the thermal expansion coefficients of the base 1, the stress buffering member 30, and the imaging element 40 decrease in this order. Therefore, compared to a configuration without such a relationship in thermal expansion coefficients, the difference in thermal deformation between the base 1 and the stress buffering member 30 and the difference in thermal deformation between the stress buffering member 30 and the imaging element 40 can be reduced. Therefore, even in a relatively high-temperature or low-temperature environment, deformation or damage to the imaging element 40 due to the difference in thermal deformation of each member can be suppressed. This allows an imaging device using the camera module 100 to be installed in a vehicle that is placed in a relatively high-temperature or low-temperature environment.

[0022] Furthermore, according to the camera module 100 of the embodiment, since the first bonding material 10 is provided, the thermal stress between the base 1 and the stress buffering member 30 can be buffered better than in a configuration that does not include the first bonding material 10. Furthermore, misalignment between the base 1 and the stress buffering member 30 can be suppressed.

[0023] Furthermore, according to the camera module 100 of the embodiment, since the second bonding material 20 is provided, misalignment between the stress buffer member 30 and the imaging element 40 can be suppressed compared to a configuration that does not include the second bonding material 20 .

[0024] Furthermore, according to the camera module 100 of the embodiment, the stress buffering member 30 is curved by plastic deformation, which can improve the precision of the curved shape of the imaging element 40 placed on the stress buffering member 30. Specifically, if the stress buffering member 30 is not curved by plastic deformation, unevenness or wrinkles may occur on the surface of the stress buffering member 30 due to variations in the thickness of the first bonding material 10, etc. Such unevenness or wrinkles cause distortion in the shape of the imaging element 40 placed on the stress buffering member 30. In contrast, because the stress buffering member 30 is curved by plastic deformation as in the embodiment, the imaging element 40 placed on the stress buffering member 30 can be deformed into a desired curved shape with high precision.

[0025] Whether the stress buffering member 30 has undergone plastic deformation can be determined by whether the stress buffering member 30 maintains its curved shape when the camera module 100 is disassembled into its constituent parts. Specifically, in the case of elastic deformation, the curved shape is not maintained and the stress buffering member 30 returns to the shape before deformation processing, such as a flat shape, or a shape close to that. In contrast, in the case of plastic deformation, even when the force applied to the stress buffering member 30 is removed, the stress buffering member 30 does not return to its original shape and maintains its curved shape.

[0026] Furthermore, according to the camera module 100 of the embodiment, the stress buffering member 30 is formed from glass, and therefore, compared to when the stress buffering member 30 is formed from a material other than glass, the stress buffering member 30 can be processed more easily and the cost required for the stress buffering member 30 can be reduced.

[0027] Furthermore, according to the camera module 100 of the embodiment, the elastic modulus of the first bonding material 10 is higher than the elastic modulus of the second bonding material 20. Therefore, the first bonding material 10 can buffer the thermal stress between the base 1, which has a relatively high thermal expansion coefficient, and the stress buffering member 30, and can suppress a decrease in the curvature accuracy of the imaging element 40. Specifically, the first bonding material 10 is relatively soft, and therefore can better buffer the thermal stress between the base 1 and the stress buffering member 30 compared to a configuration in which the first bonding material 10 is relatively hard. The second bonding material 20 is relatively hard, and therefore can maintain the curved shape of the imaging element 40 compared to a configuration in which the second bonding material 20 is relatively soft.

[0028] Furthermore, according to the camera module 100 of the embodiment, the first bonding material 10 is thicker than the second bonding material 20, and therefore can better buffer the thermal stress between the base 1, which has a relatively high coefficient of thermal expansion, and the stress buffering member 30. Furthermore, the second bonding material 20 is thinner than the first bonding material 10, and therefore can prevent a decrease in the curvature accuracy of the imaging element 40 even if the second bonding material 20 has a non-uniform thickness distribution due to manufacturing errors. Specifically, even if the relatively thin second bonding material 20 has a non-uniform thickness distribution, the difference between the protrusions and recesses is small, and therefore the impact on the curvature accuracy of the imaging element 40 is small.

[0029] Furthermore, according to the camera module 100 of the embodiment, the base 1 is made of resin or metal, and therefore can be processed relatively easily. This allows the concave surface 2 to be easily formed on the base 1. Furthermore, resin and metal have relatively large coefficients of thermal expansion. This increases the options for materials for the stress buffering member 30, which has a smaller coefficient of thermal expansion than the base 1 but a larger coefficient of thermal expansion than the imaging element 40.

[0030] B. Other Embodiments: (B1) In the above embodiment, the second bonding material 20 may be omitted. That is, the imaging element 40 may be disposed so as to be in contact with the stress buffering member 30. Even in such a configuration, the thermal expansion coefficient of the stress buffering member 30 is smaller than that of the base 1 and larger than that of the imaging element 40, thereby preventing deformation or damage to the imaging element 40.

[0031] (B2) In the above embodiment, the stress buffering member 30 does not have to be curved by plastic deformation. The stress buffering member 30 may be, for example, a flat, sheet-like member. Even in such a configuration, the stress buffering member 30 can buffer the thermal stress between the base 1 and the imaging element 40.

[0032] (B3) In the above embodiment, the stress buffering member 30 may be made of any material other than glass, such as resin or rubber.

[0033] (B4) In the above embodiment, the elastic modulus of the first bonding material 10 may be lower than or the same as the elastic modulus of the second bonding material 20.

[0034] (B5) In each of the above embodiments, the thickness of the first bonding material 10 may be smaller than or the same as the thickness of the second bonding material 20.

[0035] (B6) In the above embodiment, the base 1 may be made of any material other than resin or metal, such as rubber.

[0036] (B7) In step P10 of the above embodiment, the first bonding material 10 is attached to the base 1, but the present disclosure is not limited to this. In step P10, the first bonding material 10 may be attached to the stress buffering member 30. Furthermore, the first bonding material 10 may be attached to both the base 1 and the stress buffering member 30.

[0037] (B8) In step P30 of the above embodiment, the second bonding material 20 is attached to the imaging element 40, but the present disclosure is not limited to this. In step P30, the second bonding material 20 may be attached to the stress buffering member 30. Furthermore, the second bonding material 20 may be attached to both the stress buffering member 30 and the imaging element 40.

[0038] The present disclosure is not limited to the above-described embodiments and can be realized in various configurations without departing from the spirit thereof. For example, the technical features in each embodiment corresponding to the technical features in the embodiments described in the Summary of the Invention section can be appropriately replaced or combined to solve some or all of the above-described problems or achieve some or all of the above-described effects. Furthermore, if a technical feature is not described as essential in this specification, it can be deleted as appropriate. The present disclosure may be realized, for example, in the following forms: [Explanation of symbols]

[0039] REFERENCE SIGNS LIST 1... base, 2... concave surface, 10... first bonding material, 20... second bonding material, 30... stress buffer member, 40... imaging element, 100... camera module

Claims

1. A camera module (100), a base (1) having a curved concave surface (2); an imaging element (40) that converts received light into an electrical signal; A stress buffer member (30); a first bonding material (10) that bonds the base and the stress buffer member; Equipped with the first bonding material, the stress buffering member, and the imaging element are arranged on the base in this order; the thermal expansion coefficient of the stress buffering member is smaller than that of the base and larger than that of the imaging element; Camera module.

2. 2. The camera module according to claim 1, The camera module further comprises a second bonding material (20) that bonds the imaging element and the stress buffer member.

3. 3. The camera module according to claim 2, The camera module, wherein the stress buffering member is curved due to plastic deformation.

4. 4. The camera module according to claim 3, The camera module, wherein the stress buffer member is made of glass.

5. 5. The camera module according to claim 4, A camera module, wherein the first bonding material has a higher elastic modulus than the second bonding material.

6. 6. The camera module according to claim 5, The camera module, wherein the first bonding material is thicker than the second bonding material.

7. The camera module according to any one of claims 1 to 6, The camera module, wherein the base is made of resin or metal.

8. A method for manufacturing a camera module, comprising: a step (P10) of attaching a first bonding material to at least one of the base having a concave surface and the stress buffering member plastically deformed into a curved shape; a step (P20) of placing the stress buffering member on the base and bonding the stress buffering member and the base via the first bonding material; a step (P30) of attaching a second bonding material to at least one of an imaging element that converts received light into an electrical signal and the stress buffer member bonded to the base; a step (P40) of placing the imaging element on the stress buffering member and bonding the stress buffering member and the imaging element via the second bonding material; A method for manufacturing a camera module, comprising:

Images