CN115079397A

CN115079397A - Camera module

Info

Publication number: CN115079397A
Application number: CN202210243826.5A
Authority: CN
Inventors: 浅冈卓郎; 雪入毅司
Original assignee: Fujifilm Corp
Current assignee: Fujifilm Corp
Priority date: 2021-03-16
Filing date: 2022-03-10
Publication date: 2022-09-20
Also published as: JP2022142206A

Abstract

The invention provides a camera module which can prevent an imaging element of the camera module from being damaged by restraining the warping of the imaging element. An imaging module provided with an imaging element includes: a 1 st layer which is disposed on a back surface side of the imaging element opposite to the imaging surface and is composed of a flexible substrate; a 2 nd layer disposed between the imaging element and the 1 st layer and electrically connecting the imaging element and the 1 st layer; and a 3 rd layer disposed on the side opposite to the 2 nd layer side of the 1 st layer, the 3 rd layer having a thermal expansion coefficient closer to that of the image forming element than an average thermal expansion coefficient of the 1 st layer and the 2 nd layer, and the 3 rd layer having an elastic modulus higher than that of the 1 st layer and the 2 nd layer.

Description

Camera module

Technical Field

The present invention relates to a camera module.

Background

An image pickup module having an imaging element, a lens barrel, and the like is disposed at a distal end portion of the endoscope. The imaging element is disposed on the substrate via an electrode layer electrically connected to a solder ball or the like.

A flexible substrate made of a resin such as polyimide or polyethylene terephthalate is expected to be used as the substrate because it is cheaper than a rigid substrate, can be mounted together with other electronic components at one time, has good assemblability, and can be bent to be arranged in a narrow housing three-dimensionally.

For example, patent document 1 describes an endoscope including: a solid-state imaging element that photoelectrically converts imaging light incident on an image receiving surface via an imaging lens; and a circuit board having a connection surface facing a terminal surface which is a surface of the solid-state imaging element opposite to the image receiving surface, wherein the plurality of terminals are arranged in a two-dimensional matrix shape uniformly in both a longitudinal direction and a lateral direction on the terminal surface of the solid-state imaging element, the connection surface of the circuit board and the terminal surface of the solid-state imaging element are connected via the plurality of terminals, and a total area of the plurality of terminals on the terminal surface accounts for 10% or more of an area of an imaging region on the image receiving surface of the solid-state imaging element.

Patent document 1 describes that when an image sensor is mounted on a flexible substrate, the substrate of the image sensor is warped due to deformation of the flexible substrate (particularly, when cooled), and a connection portion between the image sensor and a circuit board may be locally deformed (paragraph [0026 ]).

Patent document 1: japanese patent laid-open publication No. 2018-007714

As such, in the case where a flexible substrate is used as a substrate of an imaging element, there are problems as follows: when each member thermally expands or contracts due to a temperature change, a difference in thermal expansion rate between the imaging element and the electrode layer and the flexible substrate is large, and thus the imaging element is warped. In particular, it was found that there was a problem that the imaging element was warped and damaged when the flexible substrate was used as a substrate because the thermal expansion coefficient of the material used as the flexible substrate was large.

Disclosure of Invention

An object of the present invention is to solve the above-described problems of the conventional art and to provide an image pickup module in which warping of an imaging element of the image pickup module is suppressed and damage to the imaging element can be prevented.

In order to solve the above problems, the present invention has the following configurations.

[1] A camera module is provided with an imaging element, and comprises:

a 1 st layer which is disposed on a back surface side of the imaging element opposite to the imaging surface and is composed of a flexible substrate;

a 2 nd layer disposed between the imaging element and the 1 st layer and electrically connecting the imaging element and the 1 st layer; and

a 3 rd layer disposed on the side opposite to the 2 nd layer side of the 1 st layer,

the thermal expansion rate of layer 3 is closer to the thermal expansion rate of the imaging member than the average thermal expansion rates of layer 1 and layer 2,

the modulus of elasticity of layer 3 is higher than the modulus of elasticity of

layers

1 and 2.

[2] The camera module according to [1], wherein,

the sum of the elastic modulus x thickness of the imaging element and the elastic modulus x thickness of the 3 rd layer is greater than the sum of the elastic modulus x thickness of the 1 st layer and the elastic modulus x thickness of the 2 nd layer.

[3] The camera module according to [1] or [2], wherein,

a cover glass having the same size as the imaging element in a plan view is attached to the imaging surface of the imaging element.

[4] The camera module according to [3], which has a lens and has at least one optical member,

the lens images the incident light on an imaging surface of the imaging element,

the at least one optical component is disposed between the cover glass and the lens,

the light receiving surface side of the cover glass is bonded and fixed with the optical member,

the amount of projection of the 3 rd layer from the side surface of the imaging element in at least one direction of the directions perpendicular to the side surface of the imaging element is not more than half of the total value of the thickness of the cover glass, the thickness of the imaging element, and the thickness of the 2 nd layer.

[5] The camera module according to any one of [1] to [4], which has a lens and has a prism,

the prism is arranged between the lens and the imaging element,

the imaging element is disposed such that the imaging plane is parallel to the optical axis of the lens,

the 3 rd layer forms the outermost layer of the camera module.

[6] The camera module according to [4], which has a prism,

the prism is arranged between the lens and the imaging element,

the 3 rd layer forms the outermost layer of the camera module,

the side of the 3 rd layer protruding from the imaging element is the lens-side.

[7] The camera module according to any one of [1] to [6], wherein,

the 3 rd layer is formed to include ceramic.

[8] The camera module according to any one of [1] to [7], wherein,

the 3 rd layer is formed with a circuit and is electrically connected to the 1 st layer.

[9] The camera module according to any one of [1] to [8], wherein,

layer 2 has solder balls.

[10] The camera module according to [9], wherein,

at least a portion of layer 2 is filled with an underfill material.

Effects of the invention

According to the present invention, it is possible to provide an image pickup module in which warping of an imaging element of the image pickup module is suppressed and damage of the imaging element can be prevented.

Drawings

Fig. 1 is a schematic configuration diagram showing an example of a configuration of an endoscope system using an endoscope including an image pickup module according to the present invention.

Fig. 2 is a perspective view schematically showing an example of the image pickup module of the present invention.

Fig. 3 is a side view of the camera module shown in fig. 2 in a state where the anchor and the cover member are removed.

Fig. 4 is an enlarged perspective view of a part of the camera module of fig. 2.

Fig. 5 is a side view of fig. 4.

Fig. 6 is a side view schematically showing another example of the image pickup module of the present invention.

Fig. 7 is a side view schematically showing another example of the image pickup module of the present invention.

Fig. 8 is a side view schematically showing another example of the image pickup module of the present invention.

Fig. 9 is a side view schematically showing another example of the image pickup module of the present invention.

Fig. 10 is a side view schematically showing another example of the image pickup module of the present invention.

Description of the symbols

1-endoscope system, 2-endoscope, 3-light source unit, 4-processor unit, 10-camera module, 12-lens, 14-lens barrel, 16-imaging element (sensor), 17-cover glass, 18-optical component (prism), 19-2 nd layer, 19 a-solder ball, 19 b-underfill, 20-optical component holding tool, 20 a-flange portion, 22-flexible substrate (1 st layer), 22 a-back surface, 22 b-1 st bend portion, 22 c-2 nd bend portion, 24-anchor, 24 a-arm portion, 24 b-holding portion, 24 c-plate portion, 26-cable, 40-3 rd layer, 42-cover member, 44-adhesive layer.

Detailed Description

Hereinafter, an embodiment of an image pickup module according to the present invention will be described with reference to the drawings.

The following description of the constituent elements may be made in accordance with a representative embodiment of the present invention, but the present invention is not limited to such an embodiment. In the drawings of the present specification, the proportions of the respective portions are appropriately changed for easy visual recognition.

In the present specification, the numerical range expressed by the term "to" means a range including the numerical values described before and after the term "to" as the lower limit value and the upper limit value.

[ Camera Module ]

The imaging module of the present invention includes an imaging element, and includes:

the elastic modulus of layer 3 is higher than the elastic modulus of

layers

1 and 2.

Fig. 1 conceptually shows an example of an endoscope system including an endoscope having an image pickup module according to the present invention.

The endoscope system 1 includes an endoscope 2, a light source unit 3, and a processor unit 4. The endoscope 2 has the same structure as a general endoscope except for a portion of the image pickup module 10 described later.

The endoscope 2 includes an insertion portion to be inserted into a subject, an operation portion connected to the insertion portion, and a universal cable extending from the operation portion, and the insertion portion includes a distal end portion, a bending portion connected to the distal end portion, and a soft portion connecting the bending portion and the operation portion.

The distal end portion is provided with an illumination optical system that emits illumination light for illuminating an observation site, and an image pickup module (camera head) having an imaging element for picking up an image of the observation site, an image pickup optical system, and the like. The bending portion is configured to be bendable in a direction orthogonal to the longitudinal axis of the insertion portion, and the bending operation of the bending portion is operated by the operation portion. The soft portion is configured to be relatively soft to such an extent that it can deform following the shape of the insertion path of the insertion portion.

The operation portion is provided with a button for operating the image pickup operation of the image pickup module at the distal end portion, a knob for operating the bending operation of the bending portion, and the like. The operation portion is provided with an introduction port through which a medical tool such as an electric scalpel is introduced, and the insertion portion is provided with a medical tool channel through which the medical tool such as a forceps is inserted, the medical tool channel extending from the introduction port to the distal end portion.

The distal end of the universal cable is provided with a connector, and the endoscope 2 is connected via the connector to a light source unit 3 that generates illumination light emitted from an illumination optical system at the distal end portion and a processor unit 4 that processes an image signal acquired by an imaging device at the distal end portion.

The processor unit 4 processes the input video signal to generate video data of the observation site, displays the generated video data on a monitor, and records the video data. In addition, the processor unit 4 may be constituted by a processor such as a PC (personal computer).

The light source unit 3 is used for: illumination light such as white light composed of three primary color light such as red light (R), green light (G), and blue light (B) or specific wavelength light is generated and supplied to the endoscope 2, propagates through a light guide or the like in the endoscope 2, and is emitted from an illumination optical system at the distal end portion of the insertion portion of the endoscope 2, thereby illuminating an observation target site in a body cavity, and an image pickup device of the endoscope 2 picks up an image of the observation target site in the body cavity to acquire an image signal.

The optical waveguide and the electric wire group (signal cable) are housed inside the insertion portion, the operation portion, and the universal cable. The illumination light generated in the light source unit 3 is guided to the illumination optical system of the tip portion via the light guide, and signals and/or power are transmitted between the image pickup device of the tip portion and the processor unit 4 via the wire group.

The endoscope system 1 may further include a water supply tank for storing washing water or the like, a suction pump for sucking the suctioned material in the body cavity (the supplied washing water or the like is also included), and the like. Further, a supply pump or the like may be provided for supplying gas such as washing water in the water supply tank or outside air into a pipe (not shown) in the endoscope.

Fig. 2 is a perspective view schematically showing an example of the image pickup module according to the present invention. The side view of fig. 2 is shown in fig. 3. Fig. 3 is a side view of the camera module of fig. 2 with the anchor 24 and the cover member 42 removed.

The image pickup module 10 shown in fig. 2 and 3 includes a lens 12, a lens barrel 14 that holds the lens 12, an imaging element (hereinafter, also referred to as a sensor) 16, a cover glass 17, an optical component 18, an optical component holding tool 20, a layer 2 19, a flexible substrate 22, a layer 3 40, an anchor 24, a cover member 42, and a cable 26.

The example shown in fig. 2 and 3 is an example in which the optical member 18 is a prism and the imaging surface of the imaging element 16 is arranged parallel to the optical axis of the lens 12. In the following description, the optical member 18 is also referred to as a prism 18. Further, since the 3 rd layer 40 is disposed on the rear surface 22a side of the flexible substrate 22, in this structure, the 3 rd layer 40 forms the outermost layer of the camera module 10, and details thereof will be described later.

The lens 12 is an optical system that images incident light on a light receiving surface of the sensor 16. The lens 12 is held by a lens barrel 14.

The lens barrel 14 is a cylindrical member that holds one or more lenses 12. The lens barrel 14 holds the lens 12 such that the optical axis of the lens 12 is perpendicular to the surface of the prism 18 facing the lens 12.

The structures of the lens 12 and the lens barrel 14 are not particularly limited. For example, the configuration may be one lens 12, or may be two or more lenses 12. Each lens 12 may be a convex lens or a concave lens.

The sensor 16 is an imaging element that performs imaging by converting light imaged by the lens 12 into an electric signal by photoelectric conversion. The sensor 16 is a conventionally known imaging element such as a CCD (Charge-Coupled Device) sensor or a CMOS (Complementary metal oxide semiconductor) sensor.

The sensor 16 is disposed on the base end side of the lens barrel 14. As shown in fig. 3, the sensor 16 is mounted on the flexible substrate 22 such that the light-receiving surface is parallel to the optical axis of the lens 12.

The flexible substrate 22 is the layer 1 in the present invention, and is a substrate on which the sensor 16 is mounted. Further, electronic components other than the sensor 16 may be mounted on the flexible substrate 22. The flexible substrate 22 is provided with a plurality of connection terminals for inputting/outputting signals or electric power to/from the sensor 16 and the electronic components. The connection terminals are electrically connected with signal lines of the cable 26 (refer to fig. 3).

In the illustrated example, the flexible substrate 22 has a shape in which a substantially L-shaped plate-like member is bent at two positions. Specifically, the flexible substrate 22 includes a 1 st bent portion 22b bent around a direction orthogonal to the optical axis direction (hereinafter, also referred to as an axial direction) of the lens and a 2 nd bent portion 22c bent around the axial direction, and the sensor 16, the electronic component, and the connection terminal are mounted on three plate-like portions connected by the two bent portions. In the illustrated example, the sensor 16 is attached to the upper surface side of the lower plate-like portion in fig. 3.

The flexible substrate 22 is a flexible substrate. The flexible substrate 22 is not particularly limited, and a conventionally known flexible substrate can be used. For example, a flexible substrate is formed by forming a circuit made of a copper foil or the like on a base film made of a resin material such as polyimide or polyethylene terephthalate (PET).

The flexible substrate 22 may be bent at one or three or more positions. The arrangement of the sensor 16, the electronic components, the connection terminals, and the like on the flexible substrate 22 is not particularly limited.

The sensor 16 and the cable 26 are connected to circuits on the flexible substrate 22. The light is converted into an electrical signal by the sensor 16, and the electrical signal is transmitted to the cable 26 via the circuit of the flexible substrate 22 and transmitted. The cable 26 is inserted into an insertion portion of the endoscope, an operation portion, a universal cable, and the like, and is connected to the processor unit 4.

The cable 26 includes one or more signal lines such as a coaxial cable or a uniaxial cable, a shield line covering the outer periphery of the one or more signal lines, a protective coating (sheath) covering the outer peripheries of the signal lines and the shield line, and the like.

The flexible substrate 22 and the sensor 16 are electrically connected through the layer 2. Fig. 4 and 5 show enlarged views of the vicinity of the sensor 16. In the example shown in fig. 4 and 5, the layer 2 has a plurality of solder balls 19a, and the sensor 16 and the circuit of the flexible substrate 22 are electrically connected by the solder balls 19 a. In the example shown in fig. 4, the space between the solder balls 19a is preferably filled with an underfill 19 b.

As the solder balls 19a, conventionally known solder balls for electrically connecting a sensor and a substrate in an imaging module of an endoscope can be suitably used. For example, a Sn-Ag-Cu alloy can be used as a material of the solder ball.

As the underfill material 19b, conventionally known underfill materials used as an underfill material in an imaging module of an endoscope can be suitably used. For example, as the underfill, a resin material such as an epoxy resin can be used.

The 2 nd layer 19 is not limited to the structure having the solder balls 19a and the underfill 19 b. For example, the 2 nd layer 19 may have only the solder balls 19 a. Alternatively, an Anisotropic Conductive Film (ACF) may be used.

The cover glass 17 is disposed on the light receiving surface of the sensor 16 to protect the light receiving surface. A prism 18 is disposed on the cover glass 17. The size of the cover glass 17 in plan view is substantially the same as the size of the imaging surface of the sensor 16.

The prism 18 is disposed between the lens barrel 14 and the sensor 16 (cover glass 17). The prism 18 bends the light passing through the lens 12 held by the barrel 14 by 90 ° to change the optical path, and guides the light to the light receiving surface of the sensor 16. In the illustrated example, the prism 18 is a rectangular prism having an incident surface orthogonal to an exit surface. The prism 18 is disposed such that an incident surface faces the base end side surface of the lens barrel 14 and an output surface faces the light receiving surface of the sensor 16. The prism 18 may be adhesively secured to the cover glass 17.

The optical component holding tool 20 is a member that holds the lens barrel 14 and the prism 18. The optical component holding tool 20 is a substantially cylindrical member in which the lens barrel 14 is fitted inside a cylindrical portion to hold the lens barrel 14. The inner surface of the optical component holding tool 20 and the outer peripheral surface of the lens barrel 14 are bonded and fixed.

As the adhesive for bonding the optical component holding tool 20 and the lens barrel 14, various known adhesives used in conventional endoscopes can be used. The same applies to the adhesive for bonding the other members to each other at this point.

The optical component holding tool 20 has a polygonal flange portion 20a on the end surface of the cylindrical portion on the base end side, and the incident surface of the prism 18 abuts against the flange portion. Thereby, the prism 18 is positioned. The optical component holding tool 20 holds the lens barrel 14 and the prism 18 at predetermined positions to fix the relative position between the lens barrel 14 and the prism 18, that is, the relative position between the lens barrel 14 and the sensor 16 (light receiving surface).

Here, the relative position of the lens barrel 14 and the optical component holding tool 20 in the optical axis direction (hereinafter also referred to as the axial direction) of the lens 12 is adjusted so as to be in focus on the light receiving surface of the sensor 16, and the lens barrel 14 is thereby fixed to the optical component holding tool 20 by bonding.

The anchors 24 hold the cable 26 relative to the optical component holding tool 20. In the illustrated example, the anchor 24 has two plate-shaped portions 24c extending in the optical axis direction, and an arm portion 24a on the leading end side of each plate-shaped portion 24 c. The arm portion 24a engages with the flange portion 20a of the optical component holding tool 20. As shown in fig. 2, the two plate-like portions 24c are arranged such that the main surfaces thereof are perpendicular to the surface of the flexible substrate 22 (the surface on which the sensor 16 is arranged). The two plate-like portions 24c are arranged to face each other across a connection portion with the cable 26 on the flexible substrate 22.

The anchor 24 has a holding portion 24b that connects two plate-shaped portions 24c at the proximal end side and holds the cable 26. The holding portion 24b is caulked so as to press the cable 26 to hold the cable 26. That is, the holding portion 24b is bent along the outer sheath of the cable 26.

The arm portions 24a of the anchor 24 and the flange portion 20a of the optical component holding tool 20, and the holding portions 24b of the anchor 24 and the sheath of the cable 26 may be fixed by adhesive bonding, respectively.

In this way, since the anchor 24 is connected to the optical component holding tool 20 and the cable 26, the connection between the connection terminal and the signal line is prevented from being broken due to the connection portion between the connection terminal and the signal line on the flexible substrate 22 being pulled when the cable 26 is pulled.

The cover member 42 is a plate-like member disposed on the opposite side of the anchor 24 from the flexible substrate 22. The cover member 42 covers the connecting portions of the connecting terminals and the signal lines on the flexible substrate 22 together with the anchor 24 to protect them.

The material for forming the anchor 24 and the cover member 42 is not particularly limited, and various resin materials and metal materials used as members constituting an imaging module of an endoscope can be used. From the viewpoint of heat dissipation, a metal material is preferable. In consideration of workability, acquisition properties, strength, and the like, stainless steel and copper alloy are preferable as the anchor 24 and the lid member 42.

In addition, the cover member 42 may be formed integrally with the anchor 24. Alternatively, the cover member 42 may not be provided.

In the camera module 10, an observation image captured by the lens 12 on the sensor 16 is formed on a light receiving surface of the sensor 16, converted into an electric signal, output to the processor unit 4 via the cable 26, and converted into a video signal, and the observation image is displayed on a monitor connected to the processor unit 4.

Here, the imaging element is a heat source, and if the temperature of the imaging element rises, the components around the imaging element thermally expand, but if the difference in thermal expansion coefficient between the imaging element and the 2 nd and 1 st layers (flexible substrates) is large, there is a problem that the imaging element warps. In particular, it was found that there was a problem that the imaging element was warped and damaged when the flexible substrate was used as a substrate because the thermal expansion coefficient of the material used as the flexible substrate was large.

In contrast, the camera module of the present invention has the following structure: the 3 rd layer 40 having a surface disposed on the opposite side of the flexible substrate 22 (1 st layer) from the 2 nd layer 19 side has a thermal expansion coefficient closer to that of the imaging element 16 than the average thermal expansion coefficient of the 1 st layer 22 and the 2 nd layer 19, and the 3 rd layer 40 has a higher elastic modulus than the 1 st layer 22 and the 2 nd layer 19. With this structure, the 3 rd layer 40 can suppress thermal expansion of the 1 st layer 22 and the 2 nd layer 19, and prevent the imaging element 16 from warping and breaking.

In general, a CMOS sensor and a CCD sensor used as the imaging element 16 have a structure in which an electrode layer, an insulating film, and the like are formed on a silicon wafer. Therefore, the thermal expansion coefficient of the imaging element 16 is about 2.5 ppm/deg.C to 4 ppm/deg.C.

On the other hand, the flexible substrate 22 is mainly made of a resin material such as polyimide or polyethylene terephthalate. Therefore, the thermal expansion coefficient of the flexible substrate 22 (layer 1) is about 20 ppm/DEG C to 100 ppm/DEG C. The elastic modulus of the flexible substrate 22 is about 5GPa to 30 GPa.

Further, for example, when the 2 nd layer 19 is formed of the solder balls 19a and the underfill 19b, the thermal expansion coefficient of the 2 nd layer 19 is about 20 ppm/deg.C to 80 ppm/deg.C. The elastic modulus of the 2 nd layer 19 is about 5GPa to 50 GPa.

Thus, the average thermal expansion of the 1 st and 2 nd layers 22, 19 is about 20 ppm/deg.C to 90 ppm/deg.C on a volume weighted average.

Examples of the material satisfying the above conditions for the 3 rd layer 40 of the imaging element 16, the 1 st layer (flexible substrate) 22, and the 2 nd layer 19 include invar materials, kovar materials, glass, silicon, stainless steel, and ceramics such as aluminum nitride and silicon nitride. Examples of the thermal expansion coefficient and the elastic modulus of these materials are shown in table 1.

[ Table 1]

Here, the thermal expansion coefficient of the 3 rd layer 40 is preferably 10 ppm/deg.c or less, more preferably 5 ppm/deg.c or less, and still more preferably 2 ppm/deg.c to 4 ppm/deg.c, from the viewpoint of suppressing warpage of the sensor 16.

From the viewpoint of suppressing the warpage of the sensor 16, the elastic modulus of the 3 rd layer 40 is preferably 70GPa or more, more preferably 150GPa or more, and still more preferably 300GPa or more.

From the viewpoint of suppressing the warpage of the sensor 16, the material of the 3 rd layer 40 is preferably a ceramic such as aluminum nitride and silicon nitride, an invar material, or a kovar alloy material, and more preferably a ceramic such as aluminum nitride and silicon nitride.

From the viewpoint of suppressing the warpage of the sensor 16, the total value of the elastic modulus × thickness of the sensor 16 and the elastic modulus × thickness of the 3 rd layer 40 is preferably larger than the total value of the elastic modulus × thickness of the 1 st layer 22 and the elastic modulus × thickness of the 2 nd layer 19. This can prevent the layer 1 and the layer 2 from thermally extending, thereby preventing the sensor 16 from warping.

The thermal expansion coefficient and the elastic modulus of each member were measured as follows.

The thermal expansion coefficient was obtained as a length change rate per unit temperature change by measuring the length between the measurement points of the test piece for each of a plurality of temperatures.

The elastic modulus was determined by applying a load to a test piece by a tensile test, measuring the change in length between measurement points of the test piece, and calculating the stress and strain. Alternatively, a method of obtaining the young's modulus of each material by a nanoindentation method and obtaining the composite elastic modulus from the volume ratio may be used.

Here, the camera module 10 preferably includes an adhesive layer 44 (see fig. 4 and 5) disposed so as to cover at least a part of the side surface of the sensor 16. In the example shown in fig. 4 and 5, the adhesive layer 44 is disposed on the flexible substrate 22 and covers both surfaces of the 2 nd layer 19, the sensor 16, and the side surface of the cover glass 17.

By having the adhesive layer 44 covering at least a part of the side surface of the sensor 16, breakage due to warping of the imaging element can be suppressed. The adhesive layer 44 may have functions such as light shielding, gas barrier (sterilization gas, etc.), moisture protection, and the like.

Adhesive layer 44 preferably covers the entire circumference of sensor 16. At this time, since the adhesive layer 44 is filled between the flexible substrate 22 and the prism 18 and/or the optical component holding jig 20, when the temperature during operation becomes high, the adhesive layer may be peeled off between the prism and the cover glass due to the influence of thermal expansion, but as described later, the amount H of protrusion of the 3 rd layer 40 from the sensor 16 is adjusted by adjusting the amount H of protrusion ₂ And can be suppressed.

As a material of the adhesive layer 44, an adhesive or a sealant can be used.

As the adhesive, various adhesives used in endoscopes can be used. For example, an epoxy adhesive can be used. Further, black epoxy is preferable because of its light-shielding property.

As the sealant, various sealants used in endoscopes can be used.

The adhesive and the sealant preferably have insulation properties, although the higher the thermal conductivity, the better.

Further, the size of the 3 rd layer 40 in a plan view is preferably equal to or larger than the size of the sensor 16, and the 3 rd layer 40 is preferably arranged to include the sensor 16 in a plan view.

For example, in the example shown in fig. 6, the 3 rd layer 40 is configured such that the size (length) in the optical axis direction of the lens 12 is larger than the sensor 16, and includes the sensor 16 in the optical axis direction. I.e. the side of the layer 3 40 protrudes further than the side of the sensor 16. In the example shown in fig. 6, the lens 12 side surface of the 3 rd layer 40 is arranged flush with the lens 12 side surface of the flexible substrate 22.

Here, as shown in fig. 7, the amount H of projection of the 3 rd layer 40 from the sensor 16 ₂ Preferably, the total value H of the thickness of the cover glass 17, the thickness of the sensor 16 and the thickness of the 2 nd layer 19 ₁ Less than half. By setting the projecting amount H of the 3 rd layer 40 ₂ Within this range, peeling between the prism and the cover glass due to the influence of the difference in thermal expansion between the adhesive layer 44 and the cover glass 17, the sensor 16, and the 2 nd layer 19 can be suppressed.

As shown in fig. 7, the side surface of the 3 rd layer 40 on the side of the lens 12 preferably protrudes from the side surface of the sensor 16 by an amount H ₂ Is the sum of the thicknesses H ₁ Less than half.

In the example shown in fig. 7, the projecting amount H of the 3 rd layer 40 is set to be equal to or greater than the projecting amount H of the first layer 40 ₂ Is the sum of the thicknesses H ₁ The amount of protrusion of the flexible substrate 22 is less than or equal to half of the amount of protrusion of the sensor 16 and the 3 rd layer 40, but is not limited thereto. The protruding amount H of the 3 rd layer 40 and the flexible substrate 22 may be configured as shown in the example of fig. 8 ₂ Is the sum of the thicknesses H ₁ Less than half.

In the examples shown in fig. 3 and 6 to 8, the imaging surface of the sensor 16 is arranged parallel to the optical axis of the lens 12, and the optical member 18 arranged between the lens 12 and the sensor 16 is a prism that bends light by 90 °.

Fig. 9 is a side view showing another example of the image pickup module of the present invention.

The image pickup module shown in fig. 9 includes a lens barrel 14 that holds a lens 12, an optical component holding jig 20, an optical component 18, a cover glass 17, a sensor 16, a 2 nd layer 19, a flexible substrate 22, a 3 rd layer 40, and an adhesive layer 44.

In the image pickup module shown in fig. 9, the flexible substrate 22 is bent substantially at 90 °, and has a portion parallel to the optical axis of the lens 12 and a portion perpendicular to the optical axis. The layer 2 19, the sensor 16, and the cover glass 17 are laminated on the surface (the surface on the lens 12 side) of the portion perpendicular to the optical axis of the flexible substrate 22. On the other hand, the 3 rd layer 40 is disposed on the back surface of the portion of the flexible substrate 22 perpendicular to the optical axis. Therefore, the imaging surface of the sensor 16 is arranged perpendicular to the optical axis of the lens 12.

The optical member 18 guides the light passing through the lens 12 to an imaging surface of the sensor 16. The optical member 18 is disposed such that the light incident surface and the light emitting surface are perpendicular to the optical axis. The optical member 18 may transmit only light or may have an effect of condensing light. The optical member 18 has an effect of collecting light, and thus the distance between the lens 12 and the sensor 16 can be made shorter, thereby enabling miniaturization.

The optical component 18 is held by the optical component holding tool 20 so as to be positioned together with the lens barrel 14 held by the optical component holding tool 20.

As described above, even in the case of the image pickup module of the present invention having the structure in which the imaging surface of the sensor 16 is arranged perpendicular to the optical axis of the lens 12, the 3 rd layer 40 can suppress thermal expansion of the 1 st layer 22 and the 2 nd layer 19, thereby preventing the imaging element 16 from being warped and damaged.

Here, even in the case of a configuration in which the imaging surface of the sensor 16 is arranged perpendicular to the optical axis of the lens 12 as shown in fig. 9, the adhesive layer 44 is preferably provided so as to cover at least a part of the side surface of the sensor 16, but more preferably covers the entire circumference.

Further, in the example shown in fig. 9, the adhesive layer 44 is filled between the flexible substrate 22 and the optical component 18, but the present invention is not limited thereto, and the adhesive layer 44 may be filled between the flexible substrate 22 and the optical component holding jig 20 as in the example shown in fig. 10.

For example, in the example shown in fig. 9 and 10, the layer 3 is arranged to have a size (length) in the vertical direction in the figure larger than the sensor 16 and to include the sensor 16. That is, two side surfaces (upper side surface and lower side surface in the figure) of the 3 rd layer 40 protrude from the sensor 16.

Even in the case where the imaging surface of the sensor 16 is arranged perpendicular to the optical axis of the lens 12 as shown in fig. 9 and 10, the amount H of projection of the 3 rd layer 40 from the sensor 16 ₂ The total value H of the thickness of the cover glass 17, the thickness of the sensor 16, and the thickness of the 2 nd layer 19 is also preferably set ₁ Less than half. By projecting the 3 rd layer 40H ₂ Within this range, peeling between the optical member and the cover glass can be suppressed.

In the image pickup module of the present invention, a circuit may be formed on the 3 rd layer 40. The circuit formed on the 3 rd layer 40 can be connected with the circuit of the 1 st layer (flexible substrate) 22 to constitute a multilayer circuit board. When a circuit is formed on the 3 rd layer 40, an insulating material such as ceramic may be used for the 3 rd layer.

While the image pickup module according to the present invention has been described in detail with reference to various embodiments, the present invention is not limited to the above examples, and various modifications and changes can be made without departing from the scope of the present invention.

Claims

1. A camera module is provided with an imaging element, and comprises:

a 1 st layer which is disposed on a back surface side of the imaging element opposite to an imaging surface and is composed of a flexible substrate;

the thermal expansion rate of the 3 rd layer is closer to the thermal expansion rate of the imaging member than the average thermal expansion rate of the 1 st layer and the 2 nd layer,

the 3 rd layer has a higher modulus of elasticity than the 1 st and 2 nd layers.

2. The camera module of claim 1,

a total value of the elastic modulus × thickness of the imaging element and the elastic modulus × thickness of the 3 rd layer is larger than a total value of the elastic modulus × thickness of the 1 st layer and the elastic modulus × thickness of the 2 nd layer.

3. The camera module of claim 1 or 2,

a cover glass having the same size as the imaging element in a plan view is attached to an imaging surface of the imaging element.

4. The camera module of claim 3,

the camera module has a lens and has at least one optical component,

the at least one optical member is disposed between the cover glass and the lens,

the light receiving surface side of the cover glass is bonded and fixed to the optical member,

the amount of projection of the 3 rd layer from the side surface of the imaging element in at least one direction of the directions perpendicular to the side surface of the imaging element is equal to or less than half of the total value of the thickness of the cover glass, the thickness of the imaging element, and the thickness of the 2 nd layer.

5. The camera module of claim 1 or 2,

the camera module has a lens and has a prism,

the prism is disposed between the lens and the imaging element,

the imaging element is configured such that an imaging plane is parallel to an optical axis of the lens,

the 3 rd layer forms an outermost layer of the camera module.

6. The camera module of claim 4,

the camera module is provided with a prism,

the prism is disposed between the lens and the imaging element,

the 3 rd layer forms the outermost layer of the camera module,

the side of the 3 rd layer protruding from the imaging element is the side of the lens side.

7. The camera module of claim 1 or 2,

the 3 rd layer is formed to include ceramic.

8. The camera module of claim 1 or 2,

9. The camera module of claim 1 or 2,

the layer 2 has solder balls.

10. The camera module of claim 9,

at least a portion of the 2 nd layer is filled with an underfill material.