JP2022142206A - Imaging module - Google Patents

Abstract

To provide an imaging module capable of preventing breakage of an image pick-up device by suppressing warpage of the image pick-up device of the imaging module.SOLUTION: An imaging module having an image pick-up device includes: a first layer composed of a flexible board disposed on a rear side opposite to an imaging face of the image pick-up device; a second layer disposed between the image pick-up device and the first layer, which electrically connects the image pick-up device and the first layer together; and a third layer disposed on a side opposite to a second layer side of the first layer. The thermal expansion coefficient of the third layer is closer to the thermal expansion coefficient of the image pick-up device than the average thermal expansion coefficient of the first layer and the second layer, and the elastic modulus of the third layer is higher than the elastic modulus of the first layer and the second layer.SELECTED DRAWING: Figure 2

Description

The present invention relates to imaging modules.

An imaging module having an imaging element, a lens barrel, and the like is arranged at the distal end of the endoscope. The imaging element is arranged on the substrate via an electrode layer for electrical connection such as a solder ball.

Reasons for this include: it is cheaper than a rigid board, it is easy to assemble as other electronic components can be mounted together, and it is bendable so that it can be placed three-dimensionally in a narrow housing. Therefore, it is considered to use flexible substrates made of resins such as polyimide and polyethylene terephthalate as substrates.

For example, in Japanese Unexamined Patent Application Publication No. 2002-100000, a solid-state image pickup device that photoelectrically converts photographing light incident on an image receiving surface through a photographing lens and a terminal surface opposite to the image receiving surface of the solid-state image pickup device are connected to each other. and a circuit board having a surface, and a plurality of terminals are evenly arranged in a two-dimensional matrix on the terminal surface of the solid-state image pickup device, and the connection surface of the circuit board and the solid-state image pickup device. The terminal surface of is connected via a plurality of terminals, and the total area of the plurality of terminals on the terminal surface occupies 10% or more of the area of the imaging area on the image receiving surface of the solid-state imaging device. It is

In Patent Document 1, when an image sensor is mounted on a flexible substrate, warping occurs in the substrate of the image sensor due to deformation of the flexible substrate that occurs particularly during cooling, and the connecting portion between the image sensor and the circuit substrate (paragraph [0026]).

JP 2018-007714 A

In this way, when a flexible substrate is used as the substrate of the imaging element, when each member thermally expands or contracts due to temperature changes, the difference in thermal expansion coefficient between the imaging element, the electrode layer, and the flexible substrate is large. , there is a problem that the imaging element is warped. In particular, since the material used for the flexible substrate has a large coefficient of thermal expansion, it has been found that when a flexible substrate is used as the substrate, the imaging element warps and is damaged.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-described problems of the prior art and to provide an imaging module capable of suppressing warping of an imaging element of the imaging module and preventing damage to the imaging element.

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

[1] In an imaging module having an imaging element,
a first layer composed of a flexible substrate arranged on the back side of the imaging device opposite to the imaging surface;
a second layer disposed between the imaging element and the first layer and electrically connecting the imaging element and the first layer;
a third layer disposed on the side opposite to the second layer side of the first layer;
The coefficient of thermal expansion of the third layer is closer to the coefficient of thermal expansion of the imaging device than the average coefficient of thermal expansion of the first and second layers,
The imaging module, wherein the modulus of elasticity of the third layer is higher than the modulus of elasticity of the first and second layers.
[2] The sum of the elastic modulus x thickness of the imaging device and the elastic modulus x thickness of the third layer is the sum of the elastic modulus x thickness of the first layer and the elastic modulus x thickness of the second two layers The imaging module according to [1], which is greater than the value.
[3] The imaging module according to [1] or [2], wherein a cover glass having the same size in plan view as the imaging element is attached to the imaging surface of the imaging element.
[4] having a lens that forms an image of incident light on the imaging surface of the imaging device;
having at least one optical component positioned between the cover glass and the lens;
The light-receiving surface side of the cover glass is adhesively fixed to the optical component,
The amount of protrusion of the third layer from the side surface of the image sensor in at least one direction out of the directions perpendicular to the side surface of the image sensor is the sum of the thickness of the cover glass, the thickness of the image sensor, and the thickness of the second layer. The imaging module according to [3], which is less than or equal to half the value.
[5] having a lens that forms an image of incident light on the imaging surface of the imaging element;
Having a prism disposed between the lens and the image sensor,
The imaging device has an imaging surface arranged parallel to the optical axis of the lens,
The imaging module according to any one of [1] to [4], wherein the third layer forms the outermost layer of the imaging module.
[6] having a prism disposed between the lens and the imaging element;
The imaging device has an imaging surface arranged parallel to the optical axis of the lens,
a third layer forms the outermost layer of the imaging module;
The imaging module according to [4], wherein the side surface where the third layer protrudes from the imaging element is the side surface on the lens side.
[7] The imaging module according to any one of [1] to [6], wherein the third layer is made of ceramic.
[8] The imaging module according to any one of [1] to [7], wherein a circuit is formed on the third layer and electrically connected to the first layer.
[9] The imaging module according to any one of [1] to [8], wherein the second layer has solder balls.
[10] The imaging module according to [9], wherein the second layer is at least partially filled with an underfill.

According to the present invention, it is possible to provide an imaging module capable of suppressing warpage of an imaging element of the imaging module and preventing damage to the imaging element.

1 is a schematic configuration diagram showing an example of configuration of an endoscope system using an endoscope having an imaging module according to the present invention; FIG. 1 is a perspective view schematically showing an example of an imaging module of the present invention; FIG. 3 is a side view of the imaging module shown in FIG. 2 with the anchor and the cover member removed; FIG. FIG. 3 is a perspective view showing an enlarged part of the imaging module of FIG. 2; 5 is a side view of FIG. 4; FIG. FIG. 4 is a side view schematically showing another example of the imaging module of the present invention; FIG. 4 is a side view schematically showing another example of the imaging module of the present invention; FIG. 4 is a side view schematically showing another example of the imaging module of the present invention; FIG. 4 is a side view schematically showing another example of the imaging module of the present invention; FIG. 4 is a side view schematically showing another example of the imaging module of the present invention;

An embodiment of an imaging module of the present invention will be described below with reference to the drawings.
The description of the constituent elements described below may be made based on representative embodiments of the present invention, but the present invention is not limited to such embodiments. In the drawings of this specification, the scale of each part is appropriately changed to facilitate visual recognition.
In this specification, a numerical range represented by "-" means a range including the numerical values before and after "-" as lower and upper limits.

[Imaging module]
The imaging module of the present invention is
In an imaging module equipped with an imaging element,
a first layer composed of a flexible substrate arranged on the back side of the imaging device opposite to the imaging surface;
a second layer disposed between the imaging element and the first layer and electrically connecting the imaging element and the first layer;
a third layer disposed on the side opposite to the second layer side of the first layer;
The coefficient of thermal expansion of the third layer is closer to the coefficient of thermal expansion of the imaging device than the average coefficient of thermal expansion of the first and second layers,
The imaging module, wherein the modulus of elasticity of the third layer is higher than the modulus of elasticity of the first and second layers.

FIG. 1 conceptually shows an example of an endoscope system including an endoscope having an imaging module of the present invention.

An endoscope system 1 includes an endoscope 2 , a light source unit 3 and a processor unit 4 . The endoscope 2 has a configuration similar to that of a general endoscope, except for an imaging module 10, which will be described later.

The endoscope 2 has an insertion portion to be inserted into the subject, an operation portion connected to the insertion portion, and a universal cord extending from the operation portion. and a flexible portion that connects the bending portion and the operating portion.

The distal end portion is provided with an imaging module (camera head) having an illumination optical system for emitting illumination light for illuminating the observation site, an imaging device for imaging the observation site, an imaging optical system, and the like. The bending section is configured to be bendable in a direction orthogonal to the longitudinal axis of the insertion section, and the bending operation of the bending section is operated by the operation section. Also, the flexible portion is configured to be relatively flexible so as to be deformable following the shape of the insertion path of the insertion portion.

The operation unit includes a button for operating the imaging operation of the imaging module at the distal end, a knob for operating the bending operation of the bending unit, and the like. In addition, the operating portion is provided with an introduction port into which a treatment tool such as an electric scalpel is introduced, and a treatment tool such as forceps is inserted into the insertion portion from the introduction port to the distal end. A fixture channel is provided.

A connector is provided at the end of the universal cord, and the endoscope 2 is acquired by a light source unit 3 that generates illumination light emitted from an illumination optical system at the distal end and an imaging device at the distal end via the connector. It is connected to a processor unit 4 for processing video signals.

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

The light source unit 3 emits red light (R), green light (G), blue light (B), and the like in order to acquire an image signal by capturing an image of an observation target site in the body cavity with the imaging device of the endoscope 2. Illumination light such as white light composed of three primary colors and light of a specific wavelength is generated, supplied to the endoscope 2, propagated through a light guide or the like in the endoscope 2, and illuminated at the insertion portion of the endoscope 2. The light is emitted from the illumination optical system at the distal end to illuminate the site to be observed within the body cavity.

A light guide and a group of electric wires (signal cables) are accommodated inside the insertion portion, the operation portion, and the universal cord. Illumination light generated by the light source unit 3 is guided to the illumination optical system at the tip through the light guide, and signals and/or power are transmitted between the imaging device at the tip and the processor unit 4 via the wire group. transmitted through

In addition, the endoscope system 1 may further include a water supply tank that stores wash water and the like, a suction pump that sucks aspirated substances (including the supplied wash water and the like) in the body cavity, and the like. Furthermore, a supply pump or the like may be provided for supplying cleaning water in the water supply tank or gas such as external air to a conduit (not shown) in the endoscope.

FIG. 2 shows a perspective view schematically showing an example of the imaging module of the present invention. FIG. 3 shows a side view of FIG. 3 is a side view of the imaging module of FIG. 2 with the anchor 24 and the cover member 42 removed.

The imaging module 10 shown in FIGS. 2 and 3 includes a lens 12, a lens barrel 14 holding the lens 12, an imaging element (hereinafter also referred to as a sensor) 16, a cover glass 17, an optical member 18, an optical member holder 20, a It has two layers 19 , flexible substrate 22 , third layer 40 , anchors 24 , cover member 42 and cable 26 .

The examples shown in FIGS. 2 and 3 are examples in which the optical member 18 is a prism and the imaging surface of the imaging device 16 is arranged parallel to the optical axis of the lens 12 . In the following description, the optical member 18 is also called prism 18 . Further, as will be described later in detail, the third layer 40 is arranged on the back surface 22a side of the flexible substrate 22, so in this configuration, the third layer 40 forms the outermost layer of the imaging module 10. .

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

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

The configurations of the lens 12 and the lens barrel 14 are not particularly limited. For example, a configuration having one lens 12 may be used, or a configuration having two, or four or more lenses 12 may be used. Further, each lens 12 may be a convex lens or a concave lens.

The sensor 16 is an imaging device that takes an image by photoelectrically converting the light imaged by the lens 12 into an electric signal. The sensor 16 is a conventionally known imaging device such as a CCD (Charge-Coupled Device) sensor, a CMOS (Complementary MOS) sensor, or the like.

The sensor 16 is arranged closer to the proximal side than the lens barrel 14 . Further, as shown in FIG. 3, the sensor 16 is mounted on the flexible substrate 22 so that the light receiving surface is parallel to the optical axis of the lens 12. As shown in FIG.

Flexible substrate 22 is the first layer in the present invention and is the substrate on which sensor 16 is mounted. Also, electronic components other than the sensor 16 may be mounted on the flexible substrate 22 . In addition, 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 electronic components. A signal line of the cable 26 is electrically connected to the connection terminal (see 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 points. Specifically, the flexible substrate 22 includes a first curved portion 22b curved around a direction perpendicular to the optical axis direction of the lens (hereinafter also referred to as an axial direction) and a second curved portion 22b curved around the axial direction. The sensor 16, electronic components, and connection terminals are mounted on three plate-shaped portions connected by the two curved portions 22c. In the illustrated example, the sensor 16 is mounted on the upper surface side of the plate-like portion on the lower side in FIG.

The flexible substrate 22 is a flexible substrate. The flexible substrate 22 is not particularly limited, and conventionally known flexible substrates can be used. As an example, a flexible substrate is obtained by forming a circuit made of 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 point or at three or more points. Moreover, there is no particular restriction on the arrangement of the sensor 16, electronic components, connection terminals, and the like on the flexible substrate 22. FIG.

A sensor 16 and a cable 26 are connected to the circuit on the flexible substrate 22, respectively. Light is converted into an electrical signal by the sensor 16, which is transmitted through the circuitry of the flexible substrate 22 to the cable 26 for transmission. The cable 26 is passed through the insertion portion, operation portion, universal cord, etc. of the endoscope and connected to the processor unit 4 .
The cable 26 includes one or more signal wires such as a coaxial cable or a uniaxial cable, a shield wire covering the outer circumference of the one or more signal wires, and a protective coating (sheath) covering the outer circumferences of the signal wire and the shield wire.

Flexible substrate 22 and sensor 16 are electrically connected by second layer 19 . 4 and 5 show enlarged views of the vicinity of the sensor 16. FIG. In the example shown in FIGS. 4 and 5, the second layer 19 has a plurality of solder balls 19a, which electrically connect the circuits of the flexible substrate 22 and the sensor 16 with the solder balls 19a. Further, in the example shown in FIG. 4, as a preferred mode, the space between the solder balls 19a is filled with the underfill 19b.

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

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

It should be noted that the second layer 19 is not limited to the structure having the solder balls 19a and the underfill 19b. For example, the second layer 19 may have only solder balls 19a. Alternatively, it may be an anisotropic conductive film (ACF).

A cover glass 17 is arranged on the light receiving surface of the sensor 16 to protect the light receiving surface. A prism 18 is arranged 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 .

A prism 18 is arranged 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 lens barrel 14 by 90°, changes 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 right-angle prism whose entrance surface and exit surface are perpendicular to each other. The prism 18 is arranged with its entrance surface facing the base end side surface of the lens barrel 14 and with its exit surface facing the light receiving surface of the sensor 16 . The prism 18 may be adhesively fixed to the cover glass 17 .

The optical member holder 20 is a member that holds the lens barrel 14 and the prism 18 . The optical member holder 20 is a substantially tubular member, and holds the lens barrel 14 by fitting the lens barrel 14 inside the tubular portion. The inner surface of the optical member holder 20 and the outer peripheral surface of the lens barrel 14 are adhesively fixed.

As the adhesive for bonding the optical member holder 20 and the lens barrel 14, various known adhesives used in conventional endoscopes can be used. This point also applies to adhesives that bond other members together.

The optical member holder 20 has a polygonal flange portion 20a on the proximal end face of the cylindrical portion, and the incident surface of the prism 18 is brought into contact with the polygonal flange portion 20a. This positions the prism 18 . By holding the lens barrel 14 and the prism 18 at predetermined positions, the optical member holder 20 can adjust the relative position of the lens barrel 14 and the prism 18, that is, the relative position of the lens barrel 14 and the sensor 16 (light receiving surface). fixed.

Here, the lens barrel 14 is adjusted relative to the optical member holder 20 in the direction of the optical axis of the lens 12 (hereinafter also referred to as the axial direction) so that the light receiving surface of the sensor 16 is in focus. It is adhesively fixed to the member holder 20 .

Anchor 24 holds cable 26 to optical member holder 20 . In the illustrated example, the anchor 24 has two plate-like portions 24c extending in the optical axis direction, and an arm portion 24a on the tip side of each plate-like portion 24c. The arm portion 24 a is engaged with the flange portion 20 a of the optical member holder 20 . Further, as shown in FIG. 2, the two plate-like portions 24c are arranged such that their main surfaces are perpendicular to the surface of the flexible substrate 22 (the surface on which the sensor 16 is arranged). In addition, the two plate-like portions 24c are arranged to face each other with the connecting portion to the cable 26 on the flexible substrate 22 interposed therebetween.

In addition, the anchor 24 has a holding portion 24b that holds the cable 26 while connecting the two plate-like portions 24c on the proximal end side. The holding portion 24 b holds the cable 26 by being crimped so as to press the cable 26 . That is, the holding portion 24b is bent along the outer skin of the cable 26. As shown in FIG.

The arm portion 24a of the anchor 24 and the flange portion 20a of the optical member holder 20, and the holding portion 24b of the anchor 24 and the outer sheath of the cable 26 may be adhesively fixed with an adhesive.

In this way, the anchors 24 are connected to the optical member holder 20 and the cable 26, respectively, so that when the cable 26 is pulled, the connection point between the connection terminal on the flexible substrate 22 and the signal line is pulled. This prevents disconnection between the connection terminal and the signal line.

The cover member 42 is a plate-like member arranged on the side of the anchor 24 opposite to the flexible substrate 22 . The cover member 42 , together with the anchor 24 , covers and protects the connection points between the connection terminals on the flexible substrate 22 and the signal lines.

Materials for forming the anchor 24 and the cover member 42 are not particularly limited, and various resin materials and metal materials used as parts constituting the imaging module of the endoscope can be used. A metal material is preferable from the viewpoint of heat dissipation. Considering workability, availability, strength, etc., stainless steel and copper alloy are preferable for the anchor 24 and the cover member 42 .

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

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

Here, the imaging element is a heat source, and when the temperature of the imaging element rises, the members around the imaging element thermally expand. If there is a large difference in , there is a problem that the imaging device warps. In particular, since the material used for the flexible substrate has a large coefficient of thermal expansion, it has been found that when a flexible substrate is used as the substrate, the imaging element warps and is damaged.

On the other hand, the imaging module of the present invention has the third layer 40 arranged on the surface of the flexible substrate 22 (first layer) opposite to the second layer 19 side. The coefficient of thermal expansion of the layer 40 is closer to the coefficient of thermal expansion of the imaging element 16 than the average coefficient of thermal expansion of the first layer 22 and the second layer 19, and the elastic modulus of the third layer 40 is It has a higher elastic modulus than the first layer 22 and the second layer 19 . With this configuration, the third layer 40 can suppress thermal expansion of the first layer 22 and the second layer 19 and prevent the imaging element 16 from being warped and damaged.

In general, a CMOS sensor and a CCD sensor used as the imaging device 16 have a structure in which electrode layers, insulating films, etc. are formed on a silicon wafer. Therefore, the coefficient of thermal expansion of the imaging element 16 is approximately 2.5 ppm/°C to 4 ppm/°C.

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

Further, for example, when the second layer 19 is composed of the solder balls 19a and the underfill 19b, the coefficient of thermal expansion of the second layer 19 is approximately 20 ppm/°C to 80 ppm/°C. The elastic modulus of the second layer 19 is approximately 5 GPa to 50 GPa.

Therefore, the average coefficient of thermal expansion of the first layer 22 and the second layer 19 is about 20 ppm/° C. to 90 ppm/° C. as a volume weighted average.

Materials that satisfy the conditions described above for the third layer 40 for the imaging element 16, the first layer (flexible substrate) 22, and the second layer 19 include invar, kovar, and glass. , silicon, stainless steel, and ceramics such as aluminum nitride and silicon nitride. Table 1 shows examples of the coefficient of thermal expansion and modulus of elasticity of these materials.

Here, from the viewpoint of suppressing warping of the sensor 16, the coefficient of thermal expansion of the third layer 40 is preferably 10 ppm/°C or less, more preferably 5 ppm/°C or less, and even more preferably 2 ppm/°C to 4 ppm/°C.

From the viewpoint of suppressing warping of the sensor 16, the elastic modulus of the third layer 40 is preferably 70 GPa or higher, more preferably 150 GPa or higher, and even more preferably 300 GPa or higher.

From the viewpoint of suppressing warping of the sensor 16, the material of the third layer 40 is preferably ceramics such as aluminum nitride and silicon nitride, invar materials, and kovar materials, and more preferably ceramics such as aluminum nitride and silicon nitride. .

In addition, from the viewpoint of suppressing warping of the sensor 16, the total value of the elastic modulus×thickness of the sensor 16 and the elastic modulus×thickness of the third layer 40 is equal to the elastic modulus×thickness of the first layer 22 and the third layer 40. It is preferably larger than the sum of the elastic modulus of the second layer 19 and the thickness. This restricts the expansion of the first layer and the second layer due to heat, and prevents the sensor 16 from warping.

The method for measuring the thermal expansion coefficient and elastic modulus of each member is as follows.
The coefficient of thermal expansion is obtained by measuring the length between measurement points of the test piece at each of a plurality of temperatures and obtaining the rate of change in length per unit temperature change.
The modulus of elasticity is obtained by applying a load to the test piece in a tensile test, measuring the change in length between measurement points on the test piece, and calculating the stress and strain. Alternatively, there is also a method of determining the Young's modulus of each material by the nanoindentation method and determining the composite elastic modulus from the volume ratio.

Here, the imaging module 10 has, as a preferred embodiment, an adhesive layer 44 arranged to cover at least part of the side surface of the sensor 16 (see FIGS. 4 and 5). In the example shown in FIGS. 4 and 5, the adhesive layer 44 is placed on the flexible substrate 22 and covers two of the sides of the second layer 19, the sensor 16 and the cover glass 17. FIG.

By having the adhesive layer 44 covering at least part of the side surface of the sensor 16, it is possible to suppress damage due to warpage of the imaging element. In addition, the adhesive layer 44 may have functions such as light shielding, gas barrier (such as sterilization gas), and moisture resistance.

Adhesive layer 44 preferably covers the entire perimeter of sensor 16 . At this time, the adhesive layer 44 is filled between the flexible substrate 22 and the prism 18 and/or the optical member holder 20, so that when the temperature rises during operation, the prism and the cover glass are bonded together due to the effect of thermal expansion. Although the problem of peeling of the agent layer may occur, it can be suppressed by adjusting the protrusion amount H ₂ of the third layer 40 from the sensor 16 as described later.

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

Various adhesives used in endoscopes can be used as the adhesive. For example, an epoxy resin-based adhesive can be used. Also, black epoxy is preferred because of its light-shielding properties.

Various sealing agents used in endoscopes can be used as the sealing agent.
The higher the thermal conductivity of the adhesive and sealant, the better, but it is preferable that they have insulating properties.

In addition, the size of the third layer 40 in plan view is preferably equal to or larger than the size of the sensor 16, and the third layer 40 is arranged so as to encompass the sensor 16 in plan view. is preferred.

For example, in the example shown in FIG. 6, the third layer 40 is arranged so that the size (length) of the lens 12 in the optical axis direction is larger than the sensor 16 and includes the sensor 16 in the optical axis direction. ing. That is, the side surface of the third layer 40 protrudes from the side surface of the sensor 16 . In the example shown in FIG. 6 , the lens 12 side surface of the third layer 40 is flush with the lens 12 side surface of the flexible substrate 22 .

Here, as shown in FIG. 7, the protrusion amount H ₂ of the third layer 40 from the sensor 16 is the total value H ₁ of the thickness of the cover glass 17, the thickness of the sensor 16, and the thickness of the second layer 19. is preferably half or less. By setting the protrusion amount H ₂ of the third layer 40 within this range, the difference in thermal expansion between the adhesive layer 44 and the cover glass 17, the sensor 16, and the second layer 19 causes the prism and the cover glass to separate. It is possible to suppress peeling in between.

Also, as shown in FIG. 7, the side surface of the third layer 40 on the lens 12 side protrudes from the side surface of the sensor 16, and the amount of protrusion H2 is preferably less _{than half} of the total thickness H1. .

In the example shown in FIG. 7, the protrusion amount H ₂ of the third layer 40 is less than half of the total thickness H ₁ , and the protrusion amount of the flexible substrate 22 is larger than that of the sensor 16 and the third layer 40. Although it is configured to protrude outward, it is not limited to this. As in the example shown in FIG. 8, the protrusion amount H2 of the third layer 40 and the flexible substrate 22 may be _half or less of the _total thickness H1.

Here, in the examples shown in FIGS. 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 light source. is a prism that bends by 90°, but it is not limited to this.

FIG. 9 is a side view showing another example of the imaging module of the present invention.
The image pickup module shown in FIG. , a third layer 40 and an adhesive layer 44 .

In the image pickup module shown in FIG. 9, the flexible substrate 22 is bent at approximately 90°, and has a portion parallel to the optical axis of the lens 12 and a portion perpendicular to the optical axis. A second layer 19 , a sensor 16 , and a cover glass 17 are laminated on the surface (surface on the lens 12 side) of the portion of the flexible substrate 22 perpendicular to the optical axis. On the other hand, a third layer 40 is arranged on the back surface of the flexible substrate 22 at a portion perpendicular to the optical axis. Accordingly, the imaging plane of sensor 16 is arranged perpendicular to the optical axis of lens 12 .

The optical member 18 guides the light that has passed through the lens 12 to the imaging surface of the sensor 16 . The optical member 18 has a light entrance surface and a light exit surface arranged perpendicular to the optical axis. The optical member 18 may simply transmit light, or may have the effect of condensing light. Since the optical member 18 has the effect of condensing light, the distance between the lens 12 and the sensor 16 can be made closer, and the size can be reduced.

The optical member 18 is held by an optical member holder 20 and positioned with the lens barrel 14 held by the optical member holder 20 .

Thus, in the imaging module of the present invention, even when the imaging surface of the sensor 16 is arranged perpendicular to the optical axis of the lens 12, the third layer 40 is the same as the first layer 22 and the second layer. It is possible to suppress the thermal expansion of the layer 19 and prevent the imaging device 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. It is preferred to have 44, but more preferred to cover 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 member 18, but is not limited to this. 44 may be filled between the flexible substrate 22 and the optical member holder 20 .

For example, in the examples shown in FIGS. 9 and 10 , the third layer 40 is larger in size (length) in the vertical direction than the sensor 16 and is arranged to encompass the sensor 16 . That is, two sides (an upper side and a lower side in the figure) of the third layer 40 each protrude from the sensor 16 .

9 and 10 in which the imaging surface of the sensor 16 is arranged perpendicular to the optical axis of the lens 12, the protrusion amount H ₂ of the third layer 40 from the sensor 16 is It is preferably half or less of the total value H ₁ of the thickness of the cover glass 17 , the thickness of the sensor 16 and the thickness of the second layer 19 . By setting the protrusion amount H ₂ of the third layer 40 within this range, it is possible to suppress peeling between the optical component and the cover glass.

Further, in the imaging module of the present invention, a circuit may be formed on the third layer 40 . Circuits formed on the third layer 40 may be connected to circuits on the first layer (flexible substrate) 22 to form a multilayer circuit board. When a circuit is formed on the third layer 40, the third layer may be made of an insulating material such as ceramic.

Although various embodiments of the imaging module according to the present invention have been described in detail above, the present invention is not limited to the above examples, and various improvements and modifications can be made without departing from the gist of the present invention. It is of course possible to perform

Reference Signs List 1 endoscope system 2 endoscope 3 light source unit 4 processor unit 10 imaging module 12 lens 14 lens barrel 16 imaging element (sensor)
17 cover glass 18 optical member (prism)
19 Second layer 19a Solder ball 19b Underfill 20 Optical member holder 20a Flange 22 Flexible substrate (first layer)
22a rear surface 22b first curved portion 22c second curved portion 24 anchor 24a arm portion 24b holding portion 24c plate-like portion 26 cable 40 third layer 42 cover member 44 adhesive layer

Claims (10)

In an imaging module equipped with an imaging element,
a first layer composed of a flexible substrate arranged on the back surface side opposite to the imaging surface of the imaging device;
a second layer disposed between the imaging device and the first layer and electrically connecting the imaging device and the first layer;
a third layer arranged on the side opposite to the second layer side of the first layer;
the coefficient of thermal expansion of the third layer is closer to the coefficient of thermal expansion of the imaging element than the average coefficient of thermal expansion of the first layer and the second layer;
The imaging module, wherein the elastic modulus of the third layer is higher than the elastic moduli of the first layer and the second layer. The sum of the elastic modulus×thickness of the imaging element and the elastic modulus×thickness of the third layer is the sum of the elastic modulus×thickness of the first layer and the elastic modulus×thickness of the second two layers. 2. The imaging module of claim 1, greater than the sum. 3. The imaging module according to claim 1, wherein a cover glass having the same size in plan view as the imaging element is attached to the imaging surface of the imaging element. Having a lens that forms an image of incident light on the imaging surface of the imaging device,
at least one optical component positioned between the cover glass and the lens;
The light-receiving surface side of the cover glass is adhesively fixed to the optical component,
In at least one direction perpendicular to the side surface of the imaging device, the amount of protrusion of the third layer from the side surface of the imaging device is equal to the thickness of the cover glass, the thickness of the imaging device, and the second thickness. 4. The imaging module according to claim 3, which is half or less of the total value with the layer thickness. Having a lens that forms an image of incident light on the imaging surface of the imaging device,
Having a prism arranged between the lens and the imaging device,
The imaging device has an imaging surface arranged parallel to the optical axis of the lens,
The imaging module according to any one of claims 1 to 4, wherein the third layer forms the outermost layer of the imaging module. Having a prism arranged between the lens and the imaging device,
The imaging device has an imaging surface arranged parallel to the optical axis of the lens,
the third layer forms the outermost layer of the imaging module;
5. The imaging module according to claim 4, wherein the side surface from which the third layer protrudes from the imaging element is the side surface on the lens side. The imaging module according to any one of claims 1 to 6, wherein said third layer is made of ceramic. The imaging module according to any one of claims 1 to 7, wherein a circuit is formed in said third layer and electrically connected to said first layer. The imaging module according to any one of claims 1 to 8, wherein said second layer comprises solder balls. 10. The imaging module of claim 9, wherein the second layer is at least partially filled with an underfill.

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