JP2019076358A - Image pickup module, endoscope, and method of manufacturing image pickup module - Google Patents

Abstract

To provide an image pickup module with high reliability.SOLUTION: An image pickup module 1 comprises: an image pickup element 10 having a light-receiving surface and a rear surface; a cover glass 20 of which second main surface is bonded to the light-receiving surface; a dummy plate 30 of which third surface is bonded to the rear surface; a thermosetting first adhesive 40 for bonding the image pickup element 10 and the cover glass 20; and a thermosetting second adhesive 50 for bonding the image pickup element 10 and the dummy plate 30. The thermal expansion coefficient of the cover glass 20 is less than 50% or more than 200% of the thermal expansion coefficient of the image pickup element 10. The thermal expansion coefficient of the dummy plate 30 is approximately the same as the thermal expansion coefficient of the cover glass 20. The warpage of a first main surface is less than 0.5 μm/mm.SELECTED DRAWING: Figure 2

Description

  The present invention provides an imaging module in which a transparent plate is adhered to the light receiving surface of the imaging device through a thermosetting adhesive, an endoscope having the imaging module, and a transparent plate on the light receiving surface of the imaging device. The present invention relates to a method of manufacturing an imaging module bonded via a curable adhesive.

  A cover glass is adhered to the light receiving surface of the imaging device via an adhesive for protection of the light receiving unit. In order to improve the reliability, it is preferable to use a thermosetting resin as the adhesive.

  For example, as shown to FIG. 1A, the cover glass 20 is arrange | positioned via the adhesive agent 40 on the light-receiving surface of the image pick-up element 10 in which the light-receiving part 11 was formed. However, as shown in FIG. 1B, after the heat curing treatment of the adhesive 40, concave warpage occurs. This is because the thermal expansion coefficient α20 of the cover glass 20 and the thermal expansion coefficient α10 of the imaging device 10 are different.

  When warpage occurs, disturbance occurs in the image of the imaging device 10. In addition, when the image sensor 10 having a large warpage is pressed against the wiring board 60 and brought into contact with the wiring board 60, there is a possibility that the image sensor 10 may be damaged.

  In addition, as shown in FIG. 1C, when the wiring board 60 is pressed against the back surface of the image pickup device 10 and brought into contact with the back surface of the image pickup device 10 and adhered via the adhesive 65, the warpage is corrected. However, in the imaging module 101, stress is generated at the bonding interface between the imaging element 10 and the cover glass 20. In the imaging module 101, the adhesion interface between the imaging element 10 and the cover glass 20 may be peeled off, and the reliability may be reduced.

  Japanese Patent Application Laid-Open No. 2003-244559 discloses an imaging device in which cover glass is bonded and fixed to both sides of an imaging device to protect both sides of the imaging device.

Unexamined-Japanese-Patent No. 2003-244559

  Embodiments of the present invention aim to provide a reliable imaging module, a reliable endoscope, and a method of manufacturing the reliable imaging module.

  An image pickup module according to an embodiment of the present invention has a light receiving surface and a back surface facing the light receiving surface, and an image pickup element in which a light receiving portion is formed on the light receiving surface, a first main surface and the first A transparent plate having a second main surface opposite to the main surface, wherein the second main surface is bonded to the light receiving surface of the imaging device, a third main surface, and the third main surface A dummy plate having a fourth main surface opposed to the second main surface, the third main surface being bonded to the back surface of the imaging device, the light receiving surface of the imaging device, and the second of the transparent plate First adhesive of the thermosetting type adhering to the main surface of the second adhesive, and the second adhesive of the thermosetting type adhering the rear surface of the imaging device and the third main surface of the dummy plate And the thermal expansion coefficient of the transparent plate is less than 50% or more than 200% of the thermal expansion coefficient of the imaging device, and the dummy plate Expansion coefficient is substantially the same as the thermal expansion coefficient of the transparent plate, warpage of the first main surface is less than 0.5 [mu] m / mm.

  The endoscope according to another embodiment includes an imaging module at the distal end of the insertion portion, the imaging module having a light receiving surface and a back surface facing the light receiving surface, and the light receiving unit is formed on the light receiving surface. A second main surface facing the first main surface and the first main surface, and the second main surface is bonded to the light receiving surface of the image pickup device. Dummy plate having a third main surface and a fourth main surface opposite to the third main surface, wherein the third main surface is bonded to the back surface of the imaging device A thermosetting first adhesive for bonding the light receiving surface of the image sensor to the second main surface of the transparent plate, the back surface of the image sensor, and the third surface of the dummy plate. And a thermosetting second adhesive that adheres to the main surface, and the thermal expansion coefficient of the transparent plate is 5 of the thermal expansion coefficient of the imaging device. % Or more than 200%, the thermal expansion coefficient of the dummy plate is substantially the same as the thermal expansion coefficient of the transparent plate, and the warpage of the first main surface is less than 0.5 μm / mm It is.

  In a method of manufacturing an imaging module according to another embodiment, an imaging device having a light receiving surface and a back surface opposite to the light receiving surface, and a light receiving unit being formed on the light receiving surface, a first main surface, and the first A thermal expansion coefficient of 50 of the thermal expansion coefficient of the image pickup element, having a second main surface opposite to the main surface of 1 and the second main surface being bonded to the light receiving surface of the image pickup device % Or more than 200%, and a third main surface and a fourth main surface facing the third main surface, wherein the third main surface corresponds to the back surface of the imaging device A chip manufacturing process for manufacturing a bonded dummy plate, a first adhesive is provided at an interface between the light receiving surface of the imaging device and the second main surface of the transparent plate, and An adhesive providing step of providing a second adhesive at an interface between the back surface of the imaging device and the third main surface of the dummy plate; A heat treatment step of curing the first adhesive and the second adhesive, the thermal expansion coefficient of the dummy plate being substantially the same as the thermal expansion coefficient of the transparent plate, and after the heat treatment step The amount of warpage of the first main surface is less than 0.5 μm / mm.

  According to an embodiment of the present invention, it is possible to provide a reliable imaging module, a reliable endoscope, and a method of manufacturing a reliable imaging module.

It is sectional drawing of the conventional imaging module. It is sectional drawing of the conventional imaging module. It is sectional drawing of the conventional imaging module. It is a sectional view of an imaging module of a 1st embodiment. It is an exploded view of an imaging module of a 1st embodiment. It is a flowchart for demonstrating the manufacturing method of the imaging module of 1st Embodiment. It is sectional drawing of the imaging module of the modification 1 of 1st Embodiment. It is sectional drawing of the imaging module of the modification 2 of 1st Embodiment. It is an exploded view of an imaging module of modification 2 of a 1st embodiment. It is sectional drawing of the imaging module of the modification 3 of 1st Embodiment. It is sectional drawing of the imaging module of the modification 4 of 1st Embodiment. It is sectional drawing of the imaging module of the modification 5 of 1st Embodiment. It is a perspective view of the endoscope of 2nd Embodiment.

First Embodiment
As shown in FIGS. 2 and 3, the imaging module 1 of the present embodiment includes an imaging device 10, a cover glass 20 which is a transparent plate, a dummy plate 30, a wiring board 60, and a first adhesive 40. , And the second adhesive 50. The chip laminate 2 configured by the imaging element 10, the first adhesive 40, the cover glass 20, the second adhesive 50, and the dummy plate 30 also has a function as an imaging module.

  In addition, it should be noted that the drawings are all schematic, and the relationship between the thickness and width of each part, the ratio of the thickness of each part, etc. are different from actual ones. There are also cases in which there are parts between which dimensional relationships and ratios differ from one another. Moreover, illustration of some components may be omitted.

  The imaging element 10 has a light receiving surface 10SA and a back surface 10SB facing the light receiving surface 10SA, and the light receiving unit 11 is formed on the light receiving surface 10SA. The light receiving unit 11 is a CMOS image sensor circuit, a CCD circuit, or the like. The imaging device 10 is a parallel plate semiconductor element chip having a rectangular cross-sectional shape in the XY plane orthogonal to the optical axis O (Z-axis direction). A connection electrode 12 connected to the light receiving unit 11 is disposed on an outer peripheral portion of the light receiving surface 10SA of the imaging element 10.

  The cover glass 20 has a first main surface 20SA and a second main surface 20SB facing the first main surface 20SA, and the second main surface 20SB is bonded to the light receiving surface 10SA of the imaging device 10 Parallel flat chip. A cover glass 20 for protecting the light receiving unit 11 is positioned and bonded so as to completely cover the light receiving unit 11 and not to cover the connection electrode 12.

  The transparent plate (cover glass 20) may be transparent in the wavelength band of the light to be imaged.

  The dummy plate 30 has a third main surface 30SA and a fourth main surface 30SB facing the third main surface 30SA, and the third main surface 30SA is bonded to the back surface 10SB of the imaging element 10 It is a parallel plate chip.

  As described later, the dummy plate 30 is made of a material whose thermal expansion coefficient α30 is substantially the same as the thermal expansion coefficient α20 of the cover glass 20. The thermal expansion coefficient α is a linear expansion coefficient in units of ppm / ° C. (K). The dummy plate 30 of the present embodiment is a glass chip having the same composition and the same size as the cover glass 20.

  The first adhesive 40 bonds the light receiving surface 10SA of the imaging element 10 and the second main surface 20SB of the cover glass 20. The second adhesive 50 bonds the back surface 10 SB of the imaging element 10 and the third main surface 30 SA of the dummy plate 30.

  The first adhesive 40 and the second adhesive 50 are the same transparent resin, for example, an epoxy resin or an acrylic resin. The liquid or gel-like uncured resin is disposed at the bonding interface and solidified by the curing treatment. The first adhesive 40 and the second adhesive 50 are thermosetting resins in order to ensure bonding reliability.

  The wiring board 60 having the fifth main surface 60SA is a ceramic wiring board. The electric cable 75 joined to the wiring board 60 is electrically connected to the connection electrode 12 of the imaging element 10.

  As long as the wiring board 60 has the flat fifth main surface 60SA, it may not be a parallel flat plate having the sixth main surface 60SB opposite to the fifth main surface 60SA. The fifth main surface 60SA of the wiring board 60 is bonded to the fourth main surface 30SB of the dummy board 30 via the third adhesive 65.

  As described later, in the imaging module 1, the amount of warpage of the first main surface 20SA is 0.05 μm / mm, which is 0.5 μm / mm or less. The amount of warpage is measured on a diagonal line using a three-dimensional measuring device, and is a value obtained by dividing the maximum value of the size of the warpage by the length of the diagonal line.

  The imaging module 1 is highly reliable because no warping occurs.

  Next, a method of manufacturing the imaging module 1 will be described according to the flowchart of FIG. 4.

<Step S10> Chip Production Step Various chips, that is, the imaging device 10, the cover glass 20, and the dummy plate 30 are produced.

  The imaging device 10 is manufactured by cutting an imaging wafer including a plurality of imaging devices 10. That is, an imaging wafer having a plurality of light receiving portions and the like is manufactured on a semiconductor wafer of silicon or the like using semiconductor manufacturing technology, and cut into pieces into imaging elements 10. The imaging device 10 may be either a front side illumination (FSI) type image sensor or a back side illumination (BSI) type image sensor. The cover glass 20 and the dummy plate 30 are produced by singulating a glass wafer.

The thermal expansion coefficient α10 of the imaging device 10 was 3 ppm / ° C., and the thermal expansion coefficient α20 of the cover glass 20 and the thermal expansion coefficient α30 of the dummy plate 30 were 7.8 ppm / ° C. That is, the thermal expansion coefficients α20 and α30 are 260% of the thermal expansion coefficient α10.
<Step S11> Adhesive Placement Step An uncured first adhesive 40 is disposed between the light receiving surface 10SA of the imaging element 10 and the second major surface 20SB of the cover glass 20. An uncured second adhesive is disposed between the back surface 10SB and the third major surface 30SA of the dummy plate 30.

  The cover glass 20 is positioned so as to completely cover the light receiving section 11 and not to cover the connection electrode 12.

<Step S12> Heat Treatment Step The heat treatment cures the first adhesive 40 and the second adhesive 50, which are thermosetting resins. For example, heat treatment is performed at 150 ° C. for 30 minutes using an inert atmosphere heater. The heating temperature is preferably over 100 ° C. for a sufficient curing reaction. The upper limit of the heating temperature is, for example, 300 ° C. of the heat resistant temperature of the imaging device 10.

  Preferably, the chip is temporarily fixed so that the relative position does not change during heat treatment. For example, an ultraviolet thermosetting resin is used as the first adhesive 40 and the second adhesive 50. The ultraviolet thermosetting adhesive is a photocurable and thermosetting resin, which is temporarily cured by irradiation of ultraviolet rays and completely cured by heat treatment. A well-known product can be applied as the ultraviolet heat-curable adhesive.

  Note that as shown in FIG. 1B, in the conventional imaging module 101, warpage occurs in the imaging element 10 to which the cover glass 20 is bonded after the heat treatment step. For example, the imaging element 10 having a thermal expansion coefficient α10 of 3 ppm / ° C. decreases in size by 390 ppm at room temperature (20 ° C.) after the heat treatment step of 150 ° C. On the other hand, the cover glass 20 having a thermal expansion coefficient α 20 of 7.8 ppm / ° C. is reduced in size by 10 14 ppm. Since the image sensor 10 and the cover glass 20 also differ in dimensional change by 624 ppm, the first main surface 20SA (the second main surface 20SB, the light receiving surface 10SA, the back surface 10SB) of the cover glass 20 deforms in a concave shape The amount of warpage was 2.8 μm / mm.

  The imaging device 10 has a thickness of 280 μm and a Young's modulus of 187 GPa. The cover glass 20 has a thickness of 650 μm and a Young's modulus of 710 GPa. The adhesive 40 had a thickness of 7 μm and a small Young's modulus of 2.9 GPa, so the amount of warpage was not significantly affected.

  On the other hand, in the chip stack 2, a dummy plate 30 of the same material as the cover glass 20 is adhered to the back surface 10 </ b> SB of the imaging device 10. The dimensional change of the dummy plate 30 due to the temperature change is 1014 ppm, which is the same as that of the cover glass 20. Therefore, since the first stress acting between the cover glass 20 and the imaging device 10 and the second stress acting between the imaging device 10 and the dummy plate 30 are offset, the imaging module 1 In this case, almost no warpage occurs even after the heat treatment step. For example, the amount of warpage of the first major surface 20SA after the heat treatment step was 0.05 μm / mm.

  For this reason, even when the chip stack 2 is used as an imaging module, since the warp is small, there is no possibility that the image of the imaging element 10 may be disturbed.

<Step S13> Wiring Board Fixing Step The fourth main surface 30SB of the dummy board 30 is pressed so as to abut on the fifth main surface 60SA of the wiring board 60, and is fixed via the adhesive 65. The fifth main surface 60SA is a flat surface, and the amount of warpage is less than 0.01 μm / mm.

  Since the amount of warping of the chip stack 2 is less than 0.5 μm / mm, the image pickup element 10 may be damaged or a large stress may be generated at the lamination interface even if the chip stack 2 is in contact with the fifth main surface 60SA and fixed. There is nothing to do. That is, when the first adhesive 40 is thermally cured, the first stress causes the cover glass 20 having a thermal expansion coefficient larger than that of the imaging device 10 to contract in the surface direction of the light receiving surface 10SA, and the second adhesive When heat curing 50 is performed, the second stress that the dummy plate 30 having a thermal expansion coefficient larger than that of the imaging device 10 tends to contract in the surface direction of the light receiving surface 10SA is equal. For this reason, the imaging module 1 manufactured by the manufacturing method of this embodiment has high reliability.

  In addition, when the thermal expansion coefficient α20 of the cover glass 20 is more than 200% of the thermal expansion coefficient α10 of the imaging device 10, the imaging device 10 to which the cover glass 20 is adhered is Warpage of more than 0.5 μm / mm occurs. When a warp amount of more than 0.5 μm / mm occurs, the reliability of the imaging module is reduced.

  Even when the thermal expansion coefficient α20 of the transparent plate (cover glass 20) is less than 50% of the thermal expansion coefficient α10 of the imaging device 10, the amount of warping is 0. 0 to the imaging device 10 to which the cover glass 20 is adhered. Warpage of more than 5 μm / mm occurs. For example, when quartz glass (thermal expansion coefficient α = 0.4 ppm / ° C.) or single crystal sapphire (thermal expansion coefficient α = 0.5 ppm / ° C.) is used as the transparent plate, the first main surface 20SA is Contrary to 1 B, a large warp occurs in a convex shape. When a warp amount of more than 0.5 μm / mm occurs, the reliability of the imaging module is reduced.

  However, by bonding a dummy plate having a thermal expansion coefficient α substantially the same as that of the transparent plate to the back surface 10SB of the imaging device 10 via the second adhesive 50, the amount of warpage can be reduced to 0.5 μm / mm or less.

  That is, when the thermal expansion coefficient α20 of the cover glass 20 is less than 50% or more than 200% of the thermal expansion coefficient α10 of the imaging device 10, the effect of the present embodiment is remarkable.

  Furthermore, when the thermal expansion coefficient α20 of the cover glass 20 is more than 20% and less than 50%, or more than 200% and less than 400% of the thermal expansion coefficient α10 of the imaging device 10, the effect of the present embodiment is remarkable.

Modification of First Embodiment
Since the imaging module of the modification of the first embodiment is similar to the imaging module 1 and has the same effect, the components having the same functions are indicated by the same reference numerals and the description thereof is omitted.

<Modified Example 1 of First Embodiment>
As shown in FIG. 5, in the imaging module 1 </ b> A of the first modification of the first embodiment, the imaging element 10 </ b> A has a first through wiring 13. The imaging device 10A has an external electrode 14 electrically connected to the light receiving unit 11 via the first through wiring 13 on the back surface 10SB.

  On the other hand, the dummy plate 30A has a second through wire 31. The connection electrode 12 and the second through wiring 31 are connected to each other through the first through wiring 13. Furthermore, the second through wiring 31 is connected to the wiring board 60A. The third adhesive 65 is an underfill resin that protects the joint between the dummy board 30A and the wiring board 60A.

  The imaging module 1A can electrically connect the imaging element and the wiring board more easily than the imaging module 1, and can further reduce the size in the optical axis orthogonal direction.

  A plurality of electronic components 70 such as chip capacitors are mounted on the wiring board 60A, which is a three-dimensional wiring board having a T-shaped cross section.

<Modification 2 of First Embodiment>
As shown in FIGS. 6 and 7, the imaging module 1B of Modification 2 of the first embodiment includes an imaging element 10A having the same configuration as the imaging module 1A. On the other hand, the dummy plate 30B has a frame shape (frame shape). The outer dimension of the dummy plate 30B is the same as the outer dimension of the cover glass 20.

  The imaging module 1B has the same effect as the imaging module 1A.

  That is, the area of the rectangular first adhesive 40 is different from the area of the frame-like second adhesive 50B. However, the magnitude of the thermal stress increases or decreases according to the external size, not the area. Therefore, when the outer periphery of the first adhesive 40 of the light receiving surface 10SA of the imaging device 10 and the outer periphery of the second adhesive 50B of the back surface 10SB of the imaging device 10 extend in the direction orthogonal to the light receiving surface 10SA If so, warpage can be reduced.

  In the imaging module 1B, the electronic component 70 is accommodated in the internal space of the frame-shaped dummy plate 30B. Thus, the imaging module 1B can mount more electronic components 70 than the imaging module 1A.

<Modification 3 of the First Embodiment>
The dummy plate 30C of the imaging module 1C of Modification 3 of the first embodiment shown in FIG. 8 uses the same glass as the cover glass 20 as a base, but has a thickness smaller than that of the cover glass 20.

  However, in the imaging module 1C, the amount of warpage of the first main surface 20SA after the heat treatment step is less than 0.5 μm / mm.

  From the evaluation of the imaging module 1C, the results of experiments conducted separately and stress simulation, the dummy plate has a thermal expansion coefficient substantially equal to that of the cover glass, ie, more than 80% and less than 120% of the thermal expansion coefficient of the cover glass It was found that the amount of warpage of the first main surface 20SA after the heat treatment step is less than 0.5 μm / mm even though the thickness is different.

  That is, if the thermal expansion coefficient of the dummy plate is substantially the same as the thermal expansion coefficient of the cover glass, an imaging module with high reliability can be obtained even if the thicknesses of both are different.

  The imaging module 1C having the thin dummy plate 30C is shorter than the imaging module 1 having the dummy plate 30 having the same thickness as the cover glass 20.

<Modification 4 of First Embodiment>
In the imaging module 1D of the modification 4 of the first embodiment shown in FIG. 9, the cover glass 20D and the dummy plate 30D are larger than the imaging element 10D.

  Although the dummy plate 30D is made of a material different from that of the cover glass 20D and is not transparent, the thermal expansion coefficients of the two are substantially the same.

  In the imaging module 1D, the amount of warpage of the first main surface 20SA after the heat treatment step was less than 0.5 μm / mm.

  From the evaluation of the imaging module 1D, the results of experiments performed separately and stress simulation, the first adhesive is used even if the size of the outer periphery of at least one of the dummy plate and the transparent plate is different from the size of the outer periphery of the imaging device When the outer periphery of the second adhesive extends in a direction perpendicular to the light receiving surface, the warpage of the first main surface 20SA after the heat treatment step is less than 0.5 .mu.m / mm, as long as it overlaps with the outer periphery of the second adhesive. It turned out to be.

<Modification 5 of First Embodiment>
In the imaging module 1E of the modification 5 of the first embodiment shown in FIG. 10, the dummy board 30E has a wiring board function. That is, the dummy plate 30E has the second through wiring 31, the electronic component 70 is mounted, and the electric cable 75 is joined.

  Although the dummy plate 30D is made of a material different from that of the cover glass 20 and is not transparent, the thermal expansion coefficients of both are substantially the same.

  In the imaging module 1E, the amount of warpage of the first main surface 20SA after the heat treatment step was less than 0.5 μm / mm.

Second Embodiment
Next, an endoscope 9 according to a second embodiment will be described.

  As shown in FIG. 11, the endoscope 9 includes an insertion portion 9B in which the imaging modules 1, 1A to 1E are disposed at the distal end portion 9A, and an operation portion 9C disposed on the proximal end side of the insertion portion 9B. , And a universal cord 9D extending from the operation unit 9C.

  The endoscope 9 has high reliability because it has the highly reliable imaging modules 1 and 1A to 1E at the distal end 9A of the insertion portion 9B. Although the endoscope 9 is a soft mirror, it may be a rigid mirror. The endoscope according to the embodiment may be a capsule type, and may be medical or industrial as long as it includes the imaging modules 1 and 1A to 1E.

  The present invention is not limited to the above-described embodiment and modifications, and various changes, modifications, combinations, and the like can be made without departing from the scope of the present invention.

DESCRIPTION OF SYMBOLS 1, 1A-1E ... Imaging module 2 ... Chip laminated body 9 ... Endoscope 9A ... Tip part 10 ... Imaging element 10SA ... Light receiving surface 10SB ... Back surface 11 ... Light reception part 12 ... Connection electrode 13 ... 1st penetration wiring 14 ... Outer electrode 20: cover glass 20SA: first main surface 20SB: second main surface 30, 30A to 30E: dummy plate 30SA: third main surface 30SB: fourth main surface 31: second through wiring 40 ... first adhesive 50 ... second adhesive 60 ... wiring board 60SA ... fifth main surface 60SB ... sixth main surface 65 ... third adhesive 70 ... electronic component 75 ... electric cable 101 ... imaging module

Claims (9)

An imaging element having a light receiving surface and a back surface opposite to the light receiving surface, the light receiving surface being formed on the light receiving surface;
A transparent plate having a first main surface and a second main surface opposite to the first main surface, wherein the second main surface is bonded to the light receiving surface of the imaging device;
A dummy plate having a third main surface and a fourth main surface opposite to the third main surface, wherein the third main surface is bonded to the back surface of the imaging device;
A thermosetting first adhesive that adheres the light receiving surface of the image sensor to the second main surface of the transparent plate;
And a thermosetting second adhesive for bonding the back surface of the imaging device and the third main surface of the dummy plate,
The thermal expansion coefficient of the transparent plate is less than 50% or more than 200% of the thermal expansion coefficient of the imaging device,
The imaging module, wherein the thermal expansion coefficient of the dummy plate is substantially the same as the thermal expansion coefficient of the transparent plate, and the amount of warpage of the first main surface is less than 0.5 μm / mm.   The imaging module according to claim 1, further comprising a wiring board having a fifth main surface, wherein the fifth main surface is bonded to the fourth main surface of the dummy plate. . The outer periphery of the transparent plate is smaller than the outer periphery of the imaging device,
The imaging device has a connection electrode electrically connected to the light receiving unit on the light receiving surface,
The imaging module according to claim 1, wherein the transparent plate does not cover the connection electrode. The image pickup device has a first through wiring, and further has an external electrode electrically connected to the light receiving portion and the first through wiring on the back surface,
The dummy plate has a second through wire,
The imaging module according to claim 1, wherein the connection electrode and the second through wiring are connected via the external electrode and the first through wiring. The image pickup device has a first through wiring, and further has an external electrode electrically connected to the light receiving portion and the first through wiring on the back surface,
The imaging module according to claim 1, wherein the dummy plate has a frame shape.   The imaging module according to any one of claims 1 to 5, wherein the dummy plate is a substrate made of the same glass material as the transparent plate.   An endoscope comprising the imaging module according to any one of claims 1 to 6 at the distal end portion of the insertion portion. An imaging element having a light receiving surface and a back surface opposite to the light receiving surface, and a light receiving portion formed on the light receiving surface, and a first main surface and a second main surface facing the first main surface A transparent plate whose thermal expansion coefficient is less than 50% or more than 200% of the thermal expansion coefficient of the image pickup device, and the second main surface is bonded to the light receiving surface of the image pickup device; A dummy plate having a third main surface and a fourth main surface opposite to the third main surface, wherein the third main surface is bonded to the back surface of the imaging device Manufacturing process,
A first adhesive is disposed at an interface between the light receiving surface of the image sensor and the second main surface of the transparent plate, and the back surface of the image sensor and the third main surface of the dummy plate An adhesive providing step of providing a second adhesive at the interface with the
A heat treatment step of heating and curing the first adhesive and the second adhesive;
The thermal expansion coefficient of the dummy plate is substantially the same as the thermal expansion coefficient of the transparent plate,
A method of manufacturing an imaging module, wherein the amount of warpage of the first main surface after the heat treatment step is less than 0.5 μm / mm. The method further comprises a wiring board fixing step of fixing the fourth main surface of the dummy board in contact with the fifth main surface of the wiring board having a fifth main surface after the heat treatment step,
9. The method for manufacturing an imaging module according to claim 8, wherein an amount of warpage of the first main surface after the wiring board fixing step is less than 0.5 μm / mm.

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