JP2011066091A - Imaging unit - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce warpage of a solid-state imaging element by suppressing difference in thermal contraction between a circuit board after mounting and the solid-state imaging element. <P>SOLUTION: An imaging unit 1 includes a solid-state imaging element 2, a circuit board 3, and a corrective substrate 7. In the solid-state imaging element 2, a plurality of through-holes 2d are formed outside a light receiving part 2a. On the circuit board 3, an opening part 3a corresponding to the light receiving part 2a and a plurality of substrate through-holes 3b corresponding to the plurality of through-holes 2d are formed, and the solid-state imaging element 2 is mounted with the light receiving part 2a and the opening part 3a being faced to each other. A plurality of engagement pins 7a which penetrate a pair of through-hole 2d and the substrate through-hole 3b are fixed to the corrective substrate 7. The corrective substrate 7 has a high rigidity against thermal contraction force of the circuit board 3, for correcting warpage of the solid-state imaging element 2. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an imaging unit including a solid-state imaging device such as a CCD or a CMOS, and more particularly to an imaging unit capable of reducing warpage of a solid-state imaging device in a bare chip state.

  2. Description of the Related Art Conventionally, various types of electronic imaging devices such as a digital camera and a digital video camera, an endoscope for observing the inside of an organ of a subject, and a mobile phone having an imaging function have appeared. An electronic imaging device includes an imaging unit including a solid-state imaging device such as a CCD or CMOS image sensor, and forms an optical image of a subject on a light-receiving portion of the solid-state imaging device by an optical system such as a lens. The image data of the subject is picked up by the photoelectric conversion process.

  A solid-state image sensor of such an image pickup unit is generally a bare chip state element in which metal bumps are respectively fixed on a plurality of electrode pads formed on a substrate on the light receiving unit side, and is heated on a circuit board by a heat treatment or the like. Are flip-chip mounted and electrically connected to the circuit wiring of the circuit board through the metal bumps. Further, a cover glass is attached to the circuit board after mounting the solid-state imaging element with an adhesive or the like so as to cover the light receiving portion of the solid-state imaging element. As a result, the light receiving portion of the solid-state image sensor on the circuit board is sealed inside the cover glass.

  On the other hand, a lead frame in which a die pad having conductivity such as metal and a lead are integrated is formed, a semiconductor chip is die-bonded to the die pad, and the semiconductor chip on the die pad and the lead of the lead frame are electrically connected by wire bonding. There is also a semiconductor device in which this semiconductor chip is packaged by a base that is connected to each other and then formed of a thermoplastic plastic (see, for example, Patent Document 1).

JP 2005-93590 A

  By the way, when a solid-state image sensor is mounted on a circuit board by a mounting technique such as flip-chip mounting, or when a solid-state image sensor is mounted on a circuit board using a thermosetting adhesive such as a silver paste material, By the heat treatment, the circuit board and the solid-state imaging element are joined together while thermally expanding. Thereafter, the circuit board and the solid-state imaging device in such a bonded state are both thermally contracted while the temperature is lowered to room temperature. However, there is a difference in thermal expansion coefficient between such a circuit board and a solid-state image sensor, resulting in a difference in thermal contraction between the two, resulting in warping of the solid-state image sensor after mounting. There is a problem of doing.

  Note that the above-described warpage of the solid-state imaging device may cause a reduction in imaging function of the solid-state imaging device, such as impairing the flatness of the light receiving unit of the solid-state imaging device and making it difficult to focus on the subject. In addition, problems caused by such warpage of the solid-state imaging device become more conspicuous as the solid-state imaging device becomes larger and thinner.

  The present invention has been made in view of the above circumstances, and provides an imaging unit capable of reducing the warp of the solid-state imaging device by suppressing the thermal contraction difference between the mounted circuit board and the solid-state imaging device. For the purpose.

  In order to solve the above-described problems and achieve the object, an imaging unit according to the present invention includes a solid-state imaging device in which a plurality of through holes are formed outside a light receiving unit, an opening corresponding to the light receiving unit, and a plurality of openings. A plurality of substrate through-holes corresponding to the through-holes, a circuit board on which the solid-state imaging device is mounted with the light receiving portion and the opening facing each other, a pair of the through-holes and the substrate through-holes A plurality of rod-like members that pass through the substrate, and a correction substrate that has a rigidity higher than the thermal contraction force of the circuit board and corrects the warp of the solid-state imaging device.

  In the imaging unit according to the present invention as set forth in the invention described above, the rod-shaped member maintains a relative positional relationship between the pair of through holes and the substrate through holes against the heat shrinkage force of the circuit board. It is characterized by.

  Moreover, the imaging unit according to the present invention is characterized in that, in the above invention, the correction substrate press-penetrates the plurality of rod-shaped members into the plurality of through holes and relatively fixes the solid-state imaging device. To do.

  In the imaging unit according to the present invention, in the above invention, a difference in thermal expansion coefficient between the correction substrate and the solid-state imaging element is smaller than a difference in thermal expansion coefficient between the solid-state imaging element and the circuit board. It is characterized by that.

  In the imaging unit according to the present invention, the thermal expansion coefficient of the correction substrate is the same as the thermal expansion coefficient of the solid-state imaging device.

  In the imaging unit according to the present invention as set forth in the invention described above, the coefficient of thermal expansion of the correction board is smaller than the coefficient of thermal expansion of the circuit board.

  Further, in the imaging unit according to the present invention, in the above invention, the plurality of rod-shaped members that are formed with a plurality of fitting holes corresponding to the plurality of substrate through-holes and project through the plurality of substrate through-holes. A support member that supports the correction of the warp of the solid-state imaging device by the correction substrate by forming a three-dimensional structure including the correction substrate and the plurality of rod-shaped members by fitting and fixing the plurality of fitting holes into the plurality of fitting holes. It is further provided with a feature.

  In the imaging unit according to the present invention as set forth in the invention described above, the support member is a translucent member that closes an opening of the circuit board.

  In the imaging unit according to the present invention as set forth in the invention described above, the support member is a frame having an opening communicating with the opening of the circuit board.

  In the imaging unit according to the present invention, in the above invention, the rod-shaped member penetrates the pair of through holes and the substrate through holes when both the circuit board and the solid-state imaging element are thermally expanded. It is characterized by.

  In the imaging unit according to the present invention, in the above invention, the rod-shaped member may pass through the pair of through holes and the substrate through holes before the circuit board and the solid-state imaging element are thermally expanded. Features.

  In the imaging unit according to the present invention, in the above invention, the solid-state imaging device includes a plurality of protruding electrodes that are electrically connected to the circuit board on the outside of the light receiving unit, and a plurality of the through holes. Is formed outside the plurality of protruding electrodes.

  In the imaging unit according to the present invention, the solid-state imaging device in which a plurality of through holes are formed outside the light receiving unit includes an opening corresponding to the light receiving unit and a plurality of substrate through holes corresponding to the plurality of through holes. The light receiving portion and the opening are mounted to face each other on the formed circuit board, and a plurality of rod-shaped members that pass through the pair of through holes and the substrate through holes are fixed. The warpage of the solid-state imaging device is corrected by a correction substrate having a relatively high rigidity. For this reason, the effect that the curvature of a solid-state image sensor can be reduced by suppressing the thermal contraction difference between the circuit board after mounting and the solid-state image sensor is produced.

FIG. 1 is a schematic cross-sectional view illustrating a configuration example of an imaging unit according to the first embodiment of the present invention. FIG. 2 is a flowchart illustrating an example of a manufacturing method of the imaging unit according to the first embodiment of the present invention. FIG. 3 is a schematic diagram illustrating a state in which the solid-state imaging device, the circuit board, and the cover glass are sequentially attached to the correction substrate. FIG. 4 is a schematic diagram showing a state in which a solid-state imaging device is flip-chip mounted on a circuit board. FIG. 5 is a schematic diagram showing a state in which a cover glass is attached to a circuit board on which a solid-state imaging device is flip-chip mounted. FIG. 6 is a schematic diagram illustrating a state in which the warpage of the solid-state imaging device is reduced by the correction substrate. FIG. 7 is a schematic cross-sectional view illustrating a configuration example of an imaging unit according to the second embodiment of the present invention. FIG. 8 is a flowchart illustrating an example of a manufacturing method of the imaging unit according to the second embodiment of the present invention. FIG. 9 is a schematic diagram illustrating a state in which the correction substrate is attached to the solid-state imaging device in a thermal expansion state. FIG. 10 is a schematic cross-sectional view illustrating a configuration example of an imaging unit according to the third embodiment of the present invention. FIG. 11 is a flowchart illustrating an example of a manufacturing method of the imaging unit according to the third embodiment of the present invention. FIG. 12 is a schematic diagram showing a state in which the solid-state imaging device, the circuit board, and the frame are sequentially attached to the correction board. FIG. 13 is a schematic diagram illustrating a state in which the warpage of the solid-state imaging device is reduced by the three-dimensional structure including the correction substrate and the frame.

  Hereinafter, embodiments of an imaging unit according to the present invention will be described in detail with reference to the drawings. Hereinafter, as an example of the imaging unit according to the present invention, an imaging unit including a solid-state imaging device flip-chip mounted on a circuit board is illustrated, but the present invention is not limited to this embodiment.

(Embodiment 1)
FIG. 1 is a schematic cross-sectional view illustrating a configuration example of an imaging unit according to the first embodiment of the present invention. As shown in FIG. 1, the imaging unit 1 according to the first embodiment includes a solid-state imaging device 2 that captures an image of a subject, a circuit board 3 on which the solid-state imaging device 2 is flip-chip mounted, a solid-state imaging device 2, and the like. An adhesive 4 for reinforcing the mounting strength with the circuit board 3, a cover glass 5 for sealing the solid-state imaging device 2 flip-chip mounted on the circuit board 3, and an adhesive 6 for bonding the cover glass 5 to the circuit board 3 And a correction substrate 7 that corrects the warpage of the solid-state imaging device 2.

  The solid-state imaging device 2 is a bare chip-shaped semiconductor device exemplified by a CCD or CMOS image sensor and has an imaging function of receiving light from a subject and capturing an image of the subject. Specifically, the solid-state imaging device 2 includes a light receiving unit 2a that receives light from a subject on a chip substrate such as a substrate, and a drive circuit unit 2b in which a drive circuit for performing an imaging operation is formed. And a plurality of protruding electrodes 2c electrically connected to the drive circuit portion 2b. Further, the solid-state imaging device 2 is formed with a plurality of through holes 2d into which the fitting pins 7a of the correction substrate 7 are press-fitted.

  The light receiving unit 2a is realized using a pixel group and a color filter that are arranged in a predetermined shape such as a lattice shape, and is formed on the chip substrate of the solid-state imaging device 2. The drive circuit unit 2b is formed around the light receiving unit 2a. Each of the plurality of protruding electrodes 2c is formed on each of a plurality of electrode pads that are electrically connected to the drive circuit unit 2b via wiring (not shown) formed on the chip substrate of the solid-state imaging device 2. . A plurality of electrode pads that connect the plurality of protruding electrodes 2c are formed around the drive circuit portion 2b (for example, two or four sides facing each other).

  The protruding electrode 2c may be a gold or copper stud bump formed by a wire bonding method, or a metal bump such as gold, silver, copper, indium or solder formed by a plating method. Also good. In addition, the protruding electrode 2c may be a metal ball or a resin ball having a surface plated with metal, or may be a conductive adhesive patterned by printing or the like.

  As described above, the through holes 2d are for press-fitting the fitting pins 7a of the correction substrate 7, and a plurality of the through holes 2d are formed outside the light receiving portion 2a of the solid-state imaging device 2. Specifically, the plurality of through holes 2d are formed outside the plurality of protruding electrodes 2c disposed outside the light receiving portion 2a. In this case, it is desirable that the plurality of through holes 2d be formed between the protruding electrode 2c and the outer edge portion of the solid-state imaging device 2 as shown in FIG. This is because a plurality of through-holes 2d are formed at such positions, so that a plurality of correction substrates 7 on a portion of the solid-state imaging device 2 that is easily affected by thermal deformation (particularly thermal contraction) of the circuit board 3 are provided. This is because the fitting pin 7a can be press-fitted, and this makes it easy to reduce the warpage of the solid-state imaging device 2 due to thermal deformation of the circuit board 3.

  As shown in FIG. 1, the solid-state imaging device 2 having the above-described configuration is flip-chip mounted on the circuit board 3 with the opening 3 a and the light receiving part 2 a of the circuit board 3 facing each other. By this flip chip mounting, the plurality of protruding electrodes 2 c of the solid-state imaging device 2 are electrically connected to circuit wiring (not shown) of the circuit board 3. In the solid-state imaging device 2 mounted on the circuit board 3 in this way, the light receiving unit 2a receives light from the subject via a cover glass 5 or the like described later, and performs photoelectric conversion processing on the received light. The drive circuit unit 2b generates an image signal of the subject based on the signal subjected to the photoelectric conversion process by the light receiving unit 2a, and outputs the generated image signal to the circuit board 3 side through the plurality of protruding electrodes 2c.

  The circuit board 3 is a circuit board having a single layer structure or a multilayer structure in which a circuit for realizing the imaging function of the solid-state imaging device 2 described above is patterned. Specifically, as shown in FIG. 1, the circuit board 3 includes an opening 3 a corresponding to the light receiving portion 2 a of the solid-state imaging element 2 and a plurality of substrate through holes 3 b corresponding to the plurality of through holes 2 d. Is formed. In addition, the circuit board 3 has a plurality of electrode pads (not shown) for electrically connecting such a pattern-formed circuit and the protruding electrode 2 c of the solid-state imaging device 2.

  The opening 3a has an opening dimension designed to correspond to the light receiving part 2a of the solid-state imaging device 2, and allows light from a subject to enter the light receiving part 2a. The plurality of substrate through-holes 3b are through-holes that are paired with the plurality of through-holes 2d formed in the solid-state imaging device 2 and penetrate the plurality of fitting pins 7a of the correction substrate 7. Each of the plurality of substrate through holes 3b is flip-chip mounted on the circuit board 3 on the outside of an electrode pad (not shown) formed outside the opening 3a, for example, as shown in FIG. It is formed at a position facing each through hole 2d of the solid-state imaging device 2 in the state. In this case, each substrate through-hole 3b and each through-hole 2d are paired with each other facing each other. The plurality of substrate through-holes 3b may be formed to have a diameter enough to press-fit each fitting pin 7a of the correction substrate 7 as in the case of each through-hole 2d of the solid-state imaging device 2 described above. Each fitting pin 7a may be formed to have a diameter that can be slidably inserted.

  As shown in FIG. 1, the solid-state imaging device 2 is flip-chip mounted on the circuit board 3 in such a manner that the light receiving portion 2a and the opening 3a of the solid-state imaging device 2 face each other. In the flip-chip mounting of the solid-state image pickup device 2, each protruding electrode 2c of the solid-state image pickup device 2 is connected to each electrode pad (not shown) of the circuit board 3 by a thermocompression bonding technique or an ultrasonic connection technique. .

  The circuit board 3 described above may be a flexible flexible circuit board that can be easily deformed by application of an external force, or may be a rigid circuit board that is less likely to be deformed than a flexible circuit board. FIG. 1 shows a part of the imaging unit 1 according to the first embodiment, specifically, a solid-state imaging device 2 and the vicinity thereof. That is, the outer shape of the circuit board 3 described above is designed to have a desired outer shape such as a plate shape or a belt shape.

  The adhesive 4 is for securely fixing the solid-state imaging device 2 and the circuit board 3 described above. Specifically, the adhesive 4 is an insulating adhesive such as epoxy, phenol, silicon, urethane, or acrylic. As shown in FIG. 1, the adhesive 4 does not enter the gap between the light receiving part 2 a of the solid-state image sensor 2 and the opening 3 a of the circuit board 3, and the solid-state image sensor 2 and the circuit after flip-chip mounting. The gap with the substrate 3 is filled. Further, the adhesive 4 is applied until a skirt shape is formed along the periphery of the solid-state image pickup device 2 on the circuit board 3, whereby the gap between the solid-state image pickup device 2 and the circuit board 3 is reduced. Block. The adhesive 4 filled and applied in this way is cured by heat treatment or ultraviolet irradiation treatment. As a result, the adhesive 4 bonds the solid-state image pickup element 2 and the circuit board 3 to each other, so that the mounting strength between the solid-state image pickup element 2 and the circuit board 3, i.e., each protruding electrode 2 c of the solid-state image pickup element 2 and each circuit board 3. Reinforce the bonding strength with the electrode pad. Furthermore, the adhesive 4 prevents foreign matter from entering the light receiving unit 2a and the incidence of unnecessary light through the gap between the solid-state imaging device 2 and the circuit board 3 as described above.

  Note that the adhesive 4 is not limited to the insulating adhesive described above, and may be an anisotropic conductive adhesive. In this case, the adhesive 4 bonds the solid-state imaging device 2 and the circuit board 3 in the above-described flip-chip mounting of the solid-state imaging device 2, and the protruding electrodes 2 c of the flip-chip-mounted solid-state imaging device 2. The electrode pads of the circuit board 3 are electrically connected to each other.

  The cover glass 5 seals the light receiving part 2a without impairing light transmittance to the light receiving part 2a of the solid-state imaging device 2. Specifically, the cover glass 5 is a plate-like translucent member that is transparent to the light from the subject, that is, the light that should be received by the light receiving portion 2a of the solid-state image sensor 2, and flips the solid-state image sensor 2 The opening 3a of the circuit board 3 in a chip-mounted state is closed. That is, as shown in FIG. 1, the cover glass 5 is fixed to the circuit board 3 by the adhesive 6 so as to close the opening 3 a of the circuit board 3. Thus, the cover glass 5 fixed on the circuit board 3 hermetically seals the light receiving portion 2a of the solid-state imaging device 2 after flip chip mounting, and as a result, the light transmission to the light receiving portion 2a is improved. Without impairing, foreign matter from the opening 3a side of the circuit board 3 is prevented.

  The cover glass 5 is formed with a plurality of fitting holes 5a corresponding to the plurality of substrate through holes 3b formed in the circuit board 3 as described above. The plurality of fitting holes 5a are through holes that press-fit the plurality of fitting pins 7a of the correction board 7 in pairs with the plurality of board through holes 3b described above. Each of the plurality of fitting holes 5a is formed at a position facing each substrate through hole 3b of the circuit board 3 in a state where the solid-state imaging device 2 is flip-chip mounted, for example, as shown in FIG. In this case, each fitting hole 5a and each substrate through-hole 3b make a pair with each other facing each other. The cover glass 5 in which the plurality of fitting holes 5a are formed is fitted and fixed by press-fitting the plurality of fitting pins 7a protruding through the plurality of substrate through holes 3b described above into the plurality of fitting holes 5a. By doing so, a three-dimensional structure including the correction substrate 7 and the plurality of fitting pins 7a is formed.

  The plurality of fitting holes 5a may be formed with a diameter enough to press-fit each fitting pin 7a of the correction substrate 7 as in the case of each through-hole 2d of the solid-state imaging device 2 described above. When the circuit board 3 and the cover glass 5 are bonded to each other by the adhesive 6, the diameter is such that each fitting pin 7a can be slidably inserted as in the case of each board through hole 3b of the circuit board 3 described above. May be formed. Further, when the circuit board 3 and the cover glass 5 are fixed by fitting and fixing the plurality of fitting pins 7a in the plurality of fitting holes 5a, the gap between the circuit board 3 and the cover glass 5 is set. May be filled with a sealing material (sealing material) for closing the gap instead of the adhesive 6. On the other hand, the adhesive 6 for bonding the cover glass 5 and the circuit board 3 may be a thermosetting adhesive such as epoxy, phenol, silicon, urethane or acrylic, or UV curable adhesive. An agent may be used.

  The correction board 7 is for reducing the warp of the solid-state imaging device 2 on which the circuit board 3 is mounted. Specifically, the correction substrate 7 has a plurality of fittings penetrating through the plurality of through holes 2d in the solid-state imaging device 2 described above, the substrate through holes 3b in the circuit board 3, and the plurality of fitting holes 5a in the cover glass 5. A pin 7a is provided. The correction board 7 is a flat plate member having a rigidity higher than the thermal deformation force (particularly the heat shrinkage force) of the circuit board 3, and a plurality of fitting pins 7 a are provided in the solid-state image sensor 2 as shown in FIG. 1. The solid-state image sensor 2 is relatively fixed in a state of being in surface contact with the solid-state image sensor 2 by being press-fitted into the through-hole 2d. Such a correction board 7 maintains a flat state against the thermal contraction force of the circuit board 3 received through the plurality of fitting pins 7a penetrating the plurality of board through holes 3b of the circuit board 3, thereby Then, the warpage of the solid-state imaging device 2 in the surface contact state is corrected.

  As described above, the fitting pins 7a are rod-like members that penetrate at least a pair of the through holes 2d and the substrate through holes 3b that are paired with each other, and are fixed to the flat plate portion of the correction substrate 7. . Specifically, each of the plurality of fitting pins 7a is formed at a position facing each through-hole 2d of the solid-state imaging device 2 in a state of being flip-chip mounted on the circuit board 3 as shown in FIG. The Each of the plurality of fitting pins 7a has a rigidity higher than the thermal deformation force (especially thermal contraction force) of the circuit board 3, and each through-hole 2d of the solid-state imaging device 2 and each board of the circuit board 3 In a state of penetrating through the through hole 3b, the relative positional relationship between the pair of through holes 2d and the substrate through hole 3b is maintained against the thermal contraction force of the circuit board 3. On the other hand, each fitting pin 7a protruding through the substrate through hole 3b is fitted into each fitting hole 5a of the cover glass 5 as shown in FIG. Thus, the plurality of fitting pins 7 a that have passed through the through-hole 2 d and the board through-hole 3 b and fitted into the fitting hole 5 a function as a three-dimensional structure column including the cover glass 5 and the correction board 7 described above.

  Here, the difference between the thermal expansion coefficient of the flat plate portion of the correction substrate 7 and the thermal expansion coefficient of the solid-state imaging device 2 is smaller than the thermal expansion coefficient difference between the solid-state imaging device 2 and the circuit board 3. Furthermore, it is desirable that the difference in thermal expansion coefficient between the correction substrate 7 and the solid-state imaging device 2 is substantially zero, that is, the thermal expansion coefficient of the correction substrate 7 is the same as the thermal expansion coefficient of the solid-state imaging device 2. . Thereby, the correction substrate 7 can easily reduce the warpage of the solid-state imaging device 2 due to the thermal contraction of the circuit board 3 to the warpage within the allowable range. Further, it is desirable that the thermal expansion coefficient of the correction substrate 7 is smaller than the thermal expansion coefficient of the circuit board 3. As a result, the correction substrate 7 can more easily reduce the warpage of the solid-state imaging device 2 due to the thermal contraction of the circuit board 3 to the warpage within the allowable range.

  In addition, as a combination of the materials of the solid-state imaging device 2 and the correction substrate 7 having the difference in thermal expansion coefficient as described above, for example, a combination of silicon and ceramic (alumina or the like), or the same material such as silicon and silicon or ceramic and ceramic are used. And the like.

  Next, a method for manufacturing the imaging unit 1 according to the first embodiment of the present invention will be described. FIG. 2 is a flowchart illustrating an example of a manufacturing method of the imaging unit according to the first embodiment of the present invention. FIG. 3 is a schematic diagram illustrating a state in which the solid-state imaging device, the circuit board, and the cover glass are sequentially attached to the correction substrate. FIG. 4 is a schematic diagram showing a state in which a solid-state imaging device is flip-chip mounted on a circuit board. FIG. 5 is a schematic diagram showing a state in which a cover glass is attached to a circuit board on which a solid-state imaging device is flip-chip mounted.

  In the imaging unit 1 according to the first embodiment of the present invention, the solid-state imaging device 2, the circuit board 3, the cover glass 5, and the correction board 7 described above are prepared in advance as components of the imaging unit 1, and the adhesives 4, 6 Etc. are used to combine these components.

  That is, as shown in FIG. 2, first, the solid-state imaging device 2 is attached to the correction substrate 7 (step S101). In this step S101, as shown in FIG. 3, the correction board 7 has a plurality of fitting pins 7a in a plurality of through holes 2d formed in the solid-state image pickup device 2 in a bare chip state before flip chip mounting on the circuit board 3. Are finally brought into surface contact with the solid-state image sensor 2, and as a result, the solid-state image sensor 2 is relatively fixed.

  Next, the solid-state imaging device 2 and the circuit board 3 on the correction substrate 7 are temporarily mounted (step S102). In this step S102, as shown in FIGS. 3 and 4, the circuit board 3 makes the light receiving portion 2a of the solid-state imaging device 2 after the correction substrate 7 is attached and the opening 3a of the circuit board 3 face each other. Each fitting pin 7a of the correction board 7 is passed through each board through hole 3b of the circuit board 3 paired with each through hole 2d of the solid-state imaging device 2. Positioning of each protruding electrode 2c of this solid-state image pickup device 2 and each electrode pad of the circuit board 3 is achieved by passing through the respective fitting pins 7a into the respective board through holes 3b. The circuit board 3 is temporarily attached to the solid-state imaging device 2 by passing the fitting pins 7a through the substrate through holes 3b until the protruding electrodes 2c come into contact with the electrode pads of the circuit board 3.

  In step S102, the solid-state imaging device 2 and the circuit board 3 are further subjected to a pressing process or an ultrasonic process, and the protruding electrodes 2c of the solid-state imaging element 2 are temporarily attached to the electrode pads of the circuit board 3. You may join.

  Thereafter, the solid-state imaging device 2 and the circuit board 3 are mounted on the main body (step S103). In step S103, the temporary mounting body 10 on which the solid-state imaging device 2 and the circuit board 3 on the correction substrate 7 are temporarily mounted as shown in FIG. 4 is put into a predetermined heating device such as a reflow furnace, and this heating is performed. Heat treatment is performed by the apparatus. By this heat treatment, each protruding electrode 2 c of the solid-state imaging device 2 is welded and bonded to each electrode pad of the circuit board 3. As a result, the flip-chip mounting of the solid-state imaging device 2 and the circuit board 3 is truly achieved, and the solid-state imaging device 2 is connected to the circuit board 3 with the opening 3a and the light receiving portion 2a of the circuit board 3 facing each other. Electrically connected.

  Here, in the state after the main mounting (that is, after the true flip chip mounting), each fitting pin 7a of the correction substrate 7 is opposed to the pair of through holes 2d against the thermal contraction force of the circuit substrate 3. The relative positional relationship with the substrate through-hole 3b is maintained. At the same time, the correction substrate 7 corrects the warpage of the solid-state image sensor 2 with a rigidity higher than the thermal contraction force of the circuit board 3, and as a result, maintains the solid-state image sensor 2 in a flat state. .

  Next, the adhesive 4 is filled between the solid-state imaging device 2 and the circuit board 3 after the main mounting process in step S103 (step S104). In this step S104, the adhesive 4 is filled in the gap between the solid-state imaging device 2 and the circuit board 3 so as not to enter the gap between the light receiving portion 2a of the solid-state imaging device 2 and the opening 3a of the circuit board 3. Then, it is applied in a skirt shape along the periphery of the solid-state image pickup device 2 on the circuit board 3 until the gap between the solid-state image pickup device 2 and the circuit board 3 is closed (see FIG. 5). As a result, the bonding strength between the protruding electrodes 2 c of the solid-state imaging device 2 and the electrode pads of the circuit board 3 is reinforced by the adhesive 4. The adhesive 4 may be cured at room temperature by UV irradiation or the like, or may be cured by heat treatment.

  Thereafter, the solid-state imaging device 2 that has been mounted on the circuit board 3 is sealed (step S105). In this step S105, as shown in FIGS. 3 and 5, in the cover glass 5, the fitting pins 7a protruding through the board through holes 3b of the circuit board 3 after the main mounting are projected to the fitting holes 5a. While fitting, the circuit board 3 is brought into surface contact so as to cover the opening 3a of the circuit board 3. At this time, an adhesive 6 is interposed between the circuit board 3 and the cover glass 5 (see FIG. 1), and the circuit board 3 and the cover glass 5 are bonded by the adhesive 6 and the circuit board 3 and the cover glass 5 are bonded. To close the gap. The cover glass 5 attached to the circuit board 3 in this way seals the light receiving portion 2a inside while allowing light to enter the light receiving portion 2a of the solid-state imaging device 2. The adhesive 6 that bonds the circuit board 3 and the cover glass 5 may be cured at room temperature by UV irradiation or the like, or may be thermally cured by heat treatment.

  The imaging unit 1 having the configuration shown in FIG. 1 can be manufactured by sequentially performing the manufacturing steps of steps S101 to S105 described above. The imaging unit 1 manufactured in this manner is used in various types of electronic imaging devices such as a digital camera and a digital video camera, an endoscope for observing the inside of an organ of a subject, and a mobile phone having an imaging function. Can be built in.

  Next, the warp reducing action of the solid-state imaging device 2 by the correction substrate 7 described above will be described. FIG. 6 is a schematic diagram illustrating a state in which the warpage of the solid-state imaging device is reduced by the correction substrate. As described above, the correction board 7 of the imaging unit 1 according to the first embodiment includes a plurality of fitting pins 7a penetrating the pair of through holes 2d and the board through holes 3b. Strong rigidity compared to Each of the fitting pins 7a of the correction board 7 passes through the pair of through holes 2d and the board through holes 3b before the circuit board 3 and the solid-state imaging device 2 are thermally expanded in the above-described steps S101 and S102. Then, the correction substrate 7 relatively fixes the solid-state image sensor 2 in a state of being in surface contact with the solid-state image sensor 2. As a result, the temporary mounting body 10 shown in FIG. 4 is assembled.

  Here, the circuit board 3 in the temporary mounting body 10 is thermally expanded by the heat treatment in step S103 described above, and then thermally contracted while the temperature is lowered to room temperature. In this state, as shown in FIG. 6, the correction board 7 in the temporary mounting body 10 receives the thermal expansion force F1 of the circuit board 3 through the fitting pins 7a, and then passes through the fitting pins 7a. The thermal contraction force F2 of the circuit board 3 is received. Such a correction board 7 has a rigidity higher than the thermal deformation force of the circuit board 3 as described above, and this correction board 7 has its own resistance to the circuit board 3 and the solid-state imaging device 2 that are thermally deformed in this way. Reaction forces F11 and F12 based on rigidity are applied.

  One reaction force F11 generated on the correction substrate 7 is a force that opposes the thermal expansion force F1 of the circuit board 3 and the solid-state imaging device 2, and the other reaction force F12 is the circuit substrate 3 and the solid-state imaging device. 2 is a force that opposes the thermal contraction force F2.

  The correction substrate 7 suppresses the thermal expansion deformation of the solid-state imaging device 2 due to the thermal expansion deformation of the circuit board 3 during the heat treatment by the reaction force F11 that opposes the thermal expansion force F1 of the circuit board 3 described above. The stress resulting from the thermal expansion of the solid-state imaging device 2 is sufficiently absorbed. As a result, the correction substrate 7 reduces the warpage of the solid-state imaging device 2 caused by such stress. Furthermore, the correction substrate 7 suppresses the heat shrink deformation of the solid-state imaging device 2 due to the heat shrink deformation of the circuit board 3 when the temperature is lowered by the reaction force F12 that opposes the heat shrink force F2 of the circuit board 3 described above. As a result, the stress caused by the thermal contraction of the solid-state imaging device 2 is sufficiently absorbed. As a result, the correction substrate 7 reduces the warpage of the solid-state imaging device 2 caused by such stress. As described above, the correction substrate 7 corrects the warp of the solid-state imaging element 2 after the heat treatment, specifically, after the flip chip mounting on the circuit board 3. By such an action of the correction substrate 7, the solid-state imaging device 2 on the circuit substrate 3 can maintain the light receiving portion 2 a in a flat state. In such a correction substrate 7, the plurality of fitting pins 7 a are formed between the plurality of through holes 2 d and the plurality of substrate through holes 3 b against the thermal expansion force F 1 or the thermal contraction force F 2 of the circuit board 3. Each relative positional relationship is maintained for each pair.

  The correction substrate 7 is similarly subjected to thermal deformation of the circuit board 3 before and after the heat treatment (for example, thermosetting treatment of the adhesives 4 and 6) after the flip-chip mounting process of the solid-state imaging device 2 described above. As a result, the warpage of the solid-state imaging device 2 due to the thermal contraction of the circuit board 3 can be reduced.

  As described above, in the first embodiment of the present invention, a plurality of fitting pins fixed to a correction board having rigidity higher than that of a circuit board on which a solid-state imaging device is mounted by heat treatment. Is passed through each through-hole of the solid-state imaging device and each substrate through-hole of the circuit board, the solid-state imaging device and the correction board are relatively fixed, and the solid-state imaging accompanying the thermal contraction deformation of the circuit board The warp of the element is configured to be corrected by the correction substrate. For this reason, the thermal contraction deformation of the solid-state imaging device due to the thermal contraction deformation of the circuit board can be suppressed by the reaction force based on the rigidity of the correction board, which counters the thermal contraction force of the circuit board, and thereby this solid-state imaging The stress resulting from the thermal contraction of the element can be sufficiently absorbed. As a result, the warp of the solid-state image sensor can be reduced by suppressing the thermal contraction difference between the circuit board after mounting by the heat treatment and the solid-state image sensor.

  In the first embodiment described above, the difference between the thermal expansion coefficient of the correction substrate and the thermal expansion coefficient of the solid-state image sensor is made smaller than the difference in thermal expansion coefficient between the solid-state image sensor and the circuit board. More preferably, the thermal expansion coefficient of the correction substrate and the thermal expansion coefficient of the solid-state imaging device are adjusted to be equal. For this reason, the correction board can easily reduce the warpage of the solid-state imaging device due to the thermal contraction of the circuit board to the warpage within the allowable range. Furthermore, by making the coefficient of thermal expansion of the correction substrate smaller than the coefficient of thermal expansion of the circuit board, the warpage of the solid-state imaging device due to the thermal contraction of the circuit board can be made easier to the warp within the allowable range. Can be reduced.

(Embodiment 2)
Next, a second embodiment of the present invention will be described. In the first embodiment described above, each fitting pin 7a of the correction substrate 7 is made to penetrate the circuit board 3 and the solid-state imaging device 2 before the heat treatment (that is, before thermal expansion), but in this second embodiment, Each fitting pin 7a of the correction board 7 is made to penetrate the circuit board 3 and the solid-state imaging device 2 in a state of being thermally expanded by the heat treatment.

  FIG. 7 is a schematic cross-sectional view illustrating a configuration example of an imaging unit according to the second embodiment of the present invention. As shown in FIG. 7, the imaging unit 21 according to the second embodiment includes a correction board 27 instead of the correction board 7 of the imaging unit 1 according to the first embodiment described above. The correction substrate 27 is relatively fixed to the solid-state image pickup device 2 by passing a plurality of fitting pins 7a through the solid-state image pickup device 2 and the circuit board 3 in a thermally expanded state by heat treatment. Other configurations are the same as those of the first embodiment, and the same reference numerals are given to the same components.

  The correction board 27 is attached to the solid-state imaging device 2 on the circuit board 3 in a state of being thermally expanded by the heat treatment, and the solid-state imaging generated due to thermal contraction deformation accompanying the temperature drop of the circuit board 3 in the state of thermal expansion. The warping of the element 2 is corrected. Specifically, the correction substrate 27 is structurally designed in accordance with the solid-state imaging device 2 that has been thermally expanded when it is flip-chip mounted on the circuit board 3 by heat treatment or the like. That is, the outer shape and dimensions of the flat plate portion of the correction substrate 7 are set in accordance with the outer shape and dimensions of the solid-state imaging device 2 in a state of being thermally expanded by heat treatment for flip chip mounting on the circuit board 3. Further, the plurality of fitting pins 7a are fixed to the flat plate portion of the correction substrate 27 corresponding to the positions after displacement of the plurality of through holes 2d that are displaced when the solid-state imaging device 2 is thermally expanded by such heat treatment. Be placed. The plurality of fitting pins 7a are fixedly arranged on the flat plate portion of the correction board 27 corresponding to the respective positions after displacement of the plurality of board through holes 3b that are displaced when the circuit board 3 is thermally expanded by heat treatment. May be.

  Such a correction substrate 27 presses the solid-state image pickup device 2 in surface contact with the solid-state image pickup device 2 by press-fitting a plurality of fitting pins 7a into the plurality of through holes 2d of the solid-state image pickup device 2 in a thermally expanded state. Fix relatively. Further, each fitting pin 7a protruding through the board through hole 3b penetrates the plurality of board through holes 3b of the circuit board 3 in a thermally expanded state on which the solid-state imaging device 2 is flip-chip mounted. The correction board 27 maintains a flat state against the thermal contraction force of the circuit board 3 received through the plurality of fitting pins 7a penetrating the plurality of board through holes 3b of the circuit board 3 in the thermally expanded state. Thus, the warpage of the solid-state imaging device 2 in the surface contact state is corrected. The correction board 27 including the plurality of fitting pins 7a has the same rigidity as the correction board 7 according to the first embodiment described above, except for the structure designed for the solid-state imaging device 2 in the thermally expanded state. It has the function and structure.

  Next, a method for manufacturing the imaging unit 21 according to the second embodiment of the present invention will be described. FIG. 8 is a flowchart illustrating an example of a manufacturing method of the imaging unit according to the second embodiment of the present invention. FIG. 9 is a schematic diagram illustrating a state in which the correction substrate is attached to the solid-state imaging device in a thermal expansion state. The imaging unit 21 according to the second embodiment of the present invention prepares the solid-state imaging device 2, the circuit board 3, the cover glass 5, and the correction substrate 27 in advance as components of the imaging unit 21, and adhesives 4 and 6. Etc. are used to combine these components.

  That is, as shown in FIG. 8, first, the solid-state imaging device 2 is mounted on the circuit board 3 (step S201). In this step S201, the circuit board 3 makes the light receiving portion 2a of the solid-state imaging device 2 and the opening 3a of the circuit substrate 3 face each other, and positioning each substrate through-hole 3b with respect to each through-hole 2d of the solid-state imaging device 2. For each pair. Subsequently, the circuit board 3 and the solid-state imaging device 2 in which the positioning of each pair of the through-holes 2d and the substrate through-holes 3b is temporarily attached, and the temporarily attached circuit board 3 and the solid-state imaging device 2 are temporarily attached. And this implementation. That is, the temporary mounting body which is the circuit board 3 and the solid-state imaging device 2 temporarily attached to each other in this manner is put into a predetermined heating device such as a reflow furnace, and the temporary mounting body is heated by the heating device. By this heat treatment, each protruding electrode 2c of the solid-state imaging device 2 is welded and bonded to each electrode pad of the circuit board 3, and as a result, flip-chip mounting between the solid-state imaging device 2 and the circuit board 3 is achieved. In this case, the solid-state imaging device 2 is electrically connected to the circuit board 3 with the opening 3a of the circuit board 3 and the light receiving unit 2a facing each other.

  In the temporary mounting in step S201, the solid-state imaging device 2 and the circuit board 3 after the positioning process as described above are further subjected to a pressing process, an ultrasonic process, or the like, and applied to each electrode pad of the circuit board 3. Each protruding electrode 2c of the solid-state imaging device 2 may be temporarily joined.

  Next, the correction substrate 27 is attached to the solid-state imaging device 2 and the circuit board 3 in the thermally expanded state by the heat treatment in the flip-chip mounting in step S201 described above (step S202). In this step S202, as shown in FIG. 9, the correction substrate 27 is a flip-chip mounting body (hereinafter simply referred to as a mounting body) of the solid-state imaging device 2 and the circuit board 3 that are in a thermally expanded state by the heat treatment in step S201. ) A plurality of fitting pins 7a are press-fitted into the plurality of through holes 2d in the solid-state image pickup device 2 in 15, and finally come into surface contact with the solid-state image pickup device 2. Thereby, the correction substrate 27 relatively fixes the solid-state imaging device 2 in the thermal expansion state. Further, as shown in FIG. 9, the correction board 27 includes a plurality of fitting pins 7 a protruding through the plurality of through holes 2 d in the plurality of board through holes 3 b in the circuit board 3 in the mounting body 15. It penetrates through the plurality of substrate through holes 3b in the circuit board 3 in a thermally expanded state. As a result, the correction board 27 relatively fixes the mounting body 15 including the solid-state imaging element 2 and the circuit board 3 in the thermally expanded state.

  Here, in the state after the flip-chip mounting, each fitting pin 7a of the correction board 27 resists the thermal contraction force of the circuit board 3 in the mounting body 15 and each pair of the through holes 2d and the board through holes. The relative positional relationship with 3b is maintained. At the same time, the correction substrate 27 corrects the warp of the solid-state image sensor 2 with a rigidity higher than the thermal contraction force of the circuit board 3 in the mounting body 15, and as a result, the solid-state image sensor 2 is in a flat state. To maintain.

  Next, the adhesive 4 is filled between the solid-state imaging device 2 and the circuit board 3 after the correction substrate 27 is attached in step S202 (step S203). In this step S203, the adhesive 4 is filled in the gap between the solid-state imaging device 2 and the circuit board 3 as in the case of the first embodiment, and further, the gap between the solid-state imaging element 2 and the circuit board 3 is filled. Is applied in the shape of a skirt along the periphery of the solid-state imaging device 2 on the circuit board 3 until it is closed. Note that such a filling operation of the adhesive 4 may be performed on the mounting body 15 in a thermally expanded state, for example, on the mounting body 15 in a state in which the temperature is reduced to about room temperature and thermally contracted. Also good.

  Thereafter, as in the case of step S105 of the first embodiment described above, the solid-state imaging device 2 that has been flip-chip mounted on the circuit board 3 is sealed (step S204). By this step S204, the cover glass 5 is attached to the mounting body 15 described above, and as a result, the imaging unit 21 having the configuration shown in FIG. 7 is manufactured. The imaging unit 21 manufactured in this way is used in various types of electronic imaging devices such as a digital camera and a digital video camera, an endoscope for observing the inside of an organ of a subject, and a mobile phone having an imaging function. Can be built in.

  Here, as described above, the correction board 27 described above is attached to the mounting body 15 in the thermally expanded state by the heat treatment in step S202. The circuit board 3 in the mounting body 15 in the thermally expanded state is lowered to room temperature while maintaining a state in which the plurality of fitting pins 7a of the correction board 27 are passed through the plurality of board through holes 3b. Accompanied by heat shrinkage. In this state, the correction board 27 receives the thermal contraction force F2 (see FIG. 6) of the circuit board 3 through each fitting pin 7a. Such a correction board 27 has a rigidity higher than the thermal deformation force of the circuit board 3 as described above, and this correction board 27 has its own resistance to the circuit board 3 and the solid-state imaging device 2 that are thermally deformed in this way. A reaction force F12 (see FIG. 6) based on rigidity is applied.

  The correction substrate 27 suppresses the thermal contraction deformation of the solid-state imaging device 2 due to the thermal contraction deformation of the circuit board 3 at the time of the temperature decrease by the reaction force F12 that opposes the thermal contraction force F2 of the circuit board 3 as described above. As a result, the stress caused by the thermal contraction of the solid-state imaging device 2 is sufficiently absorbed. As a result, the correction substrate 27 reduces the warpage of the solid-state imaging device 2 caused by such stress. In this way, the correction substrate 27 corrects the warp of the solid-state imaging device 2 after the heat treatment, specifically, after flip chip mounting on the circuit board 3. By such an action of the correction substrate 27, the solid-state imaging device 2 on the circuit board 3 can maintain the light receiving unit 2a in a flat state as in the case of the first embodiment. In such a correction board 27, the plurality of fitting pins 7 a have the relative positional relationship between the plurality of through holes 2 d and the plurality of board through holes 3 b against the thermal contraction force F 2 of the circuit board 3. Keep pairwise.

  The correction substrate 27 is similarly subjected to thermal deformation of the circuit board 3 before and after the heat treatment (for example, thermosetting treatment of the adhesives 4 and 6) after the flip-chip mounting process of the solid-state imaging device 2 described above. As a result, the warpage of the solid-state imaging device 2 due to the thermal contraction of the circuit board 3 can be reduced.

  As described above, in the second embodiment of the present invention, a correction board is attached to a mounted body after flip chip mounting in a thermally expanded state, that is, a solid-state imaging device and a circuit board in a thermally expanded state. Thus, the warp of the solid-state imaging device due to the thermal contraction deformation of the circuit board is corrected, and the others are configured in the same manner as in the first embodiment. For this reason, even if the circuit board in a thermally expanded state after flip-chip mounting is thermally shrunk as the temperature drops, the correction board forcibly causes the circuit board and the thermal contraction of the solid-state imaging device accompanying the heat shrinking of the circuit board. As a result, it is possible to realize an imaging unit that enjoys the same effects as those of the first embodiment described above with fewer work steps.

(Embodiment 3)
Next, a third embodiment of the present invention will be described. In the first embodiment described above, the solid-state imaging device 2 and the circuit board 3 are sandwiched by the three-dimensional structure of the correction substrate 7 and the cover glass 5 via the plurality of fitting pins 7a. In this third embodiment, A three-dimensional structure that reduces warpage of the solid-state imaging device 2 is formed by using the frame body in which the opening communicating with the opening 3 a of the circuit board 3 is formed and the correction substrate 7 described above.

  FIG. 10 is a schematic cross-sectional view illustrating a configuration example of an imaging unit according to the third embodiment of the present invention. As shown in FIG. 10, the imaging unit 31 according to the third embodiment includes a cover glass 35 instead of the cover glass 5 of the imaging unit 1 according to the first embodiment described above, and the cover glass 35 and the circuit board. 3 is provided with a frame 38. In the third embodiment, the correction board 7 and the frame body 38 have a three-dimensional structure that sandwiches the solid-state imaging device 2 and the circuit board 3 with a plurality of fitting pins 7a as columns. Other configurations are the same as those of the first embodiment, and the same reference numerals are given to the same components.

  The cover glass 35 seals the light receiving part 2a without impairing the light transmittance to the light receiving part 2a of the solid-state imaging device 2. Specifically, the cover glass 35 is a plate-like translucent member that is transparent to light from a subject, that is, light that should be received by the light receiving unit 2a of the solid-state imaging device 2. The cover glass 35 is not formed with the plurality of fitting holes 5a illustrated in the first embodiment. As shown in FIG. 10, such a cover glass 35 is fixed to the frame 38 by the adhesive 6 so as to close the opening 38 a of the frame 38 communicating with the opening 3 a of the circuit board 3. The cover glass 35 fixed on the frame 38 in this manner hermetically seals the light receiving portion 2a of the solid-state imaging device 2 after flip chip mounting. As a result, the light transmission to the light receiving portion 2a is improved. Without impairing, foreign matter contamination from the opening 38a side of the frame 38 is prevented.

  The frame 38 is a frame-like member that forms a part of a three-dimensional structure that realizes a reduction in warpage of the solid-state imaging device 2, and functions as a support member that supports correction of warpage of the solid-state imaging device 2 by the correction substrate 7 described above. . Specifically, as shown in FIG. 10, the frame body 38 has an opening 38 a corresponding to the opening 3 a of the circuit board 3 and a plurality of fittings corresponding to the plurality of substrate through holes 3 b of the circuit board 3. A hole 38b is formed.

  The opening 38a of the frame 38 has an opening dimension designed corresponding to the light receiving part 2a of the solid-state imaging device 2 in the same manner as the opening 3a of the circuit board 3 described above. Enables the incidence of light. As shown in FIG. 10, such a frame 38 is attached to the circuit board 3 so that the opening 3a of the circuit board 3 and the opening 38a of the circuit board 3 communicate with each other. In this case, a plurality of fitting pins 7 a protruding through the circuit board 3 are fitted and fixed in the plurality of fitting holes 38 b formed in the frame 38.

  The plurality of fitting holes 38b are through holes that press-fit the plurality of fitting pins 7a of the correction board 7 in pairs with the plurality of board through holes 3b described above. Each of the plurality of fitting holes 38b is formed at a position facing each board through hole 3b of the circuit board 3 through which each fitting pin 7a passes, for example, as shown in FIG. In this case, each fitting hole 38b and each substrate through-hole 3b make a pair with each other facing each other. The frame 38 formed with the plurality of fitting holes 38b is press-fitted into the plurality of fitting holes 38b with the plurality of fitting pins 7a protruding through the plurality of substrate through-holes 3b described above. By doing so, a three-dimensional structure including the correction substrate 7 and the plurality of fitting pins 7a is formed. In this case, as shown in FIG. 10, the plurality of fitting pins 7 a that pass through the solid-state imaging device 2 and the circuit board 3 and are fitted into the frame body 38 have a three-dimensional structure formed by the correction board 7 and the frame body 38. Functions as a body support. Such a three-dimensional structure sandwiches the solid-state imaging device 2 and the circuit board 3 in a surface contact state as shown in FIG. 10, and as a result, the warpage of the solid-state imaging device 2 is strongly reduced. The frame body 38 supports the warp correction action of the solid-state imaging device 2 by the correction board 7 which is a rigid board that forms the base of the three-dimensional structure.

  The plurality of fitting holes 38b may be formed to have a diameter enough to press-fit each fitting pin 7a of the correction substrate 7 as in the case of each through-hole 2d of the solid-state imaging device 2 described above. Similarly to the case of each board through hole 3b of the circuit board 3, each fitting pin 7a may be formed with a diameter that can be slidably inserted. When the respective fitting pins 7a are slidably inserted into the respective fitting holes 38b, the frame body 38 may be bonded to the circuit board 3 with an adhesive. Further, when the circuit board 3 and the frame body 38 are fixed by fitting and fixing the plurality of fitting pins 7a into the plurality of fitting holes 38b, the gap between the circuit board 3 and the frame body 38 is set. A sealing material (sealing material) for closing the gap may be filled.

  Next, a method for manufacturing the imaging unit 31 according to the third embodiment of the present invention will be described. FIG. 11 is a flowchart illustrating an example of a manufacturing method of the imaging unit according to the third embodiment of the present invention. FIG. 12 is a schematic diagram showing a state in which the solid-state imaging device, the circuit board, and the frame are sequentially attached to the correction board. The imaging unit 31 according to the third embodiment of the present invention prepares the solid-state imaging device 2, the circuit board 3, the cover glass 35, the correction substrate 7, and the frame body 38 as constituent parts of the imaging unit 31 in advance, and an adhesive. It is manufactured by combining these components using 4, 6, etc.

  That is, as shown in FIG. 11, first, the solid-state imaging device 2 is attached to the correction substrate 7 in the same manner as in step S101 in the first embodiment (step S301), and then in the case of step S102 in the first embodiment. Similarly, the solid-state imaging device 2 and the circuit board 3 on the correction substrate 7 are temporarily mounted (step S302).

  Next, the solid-state imaging device 2 and the circuit board 3 temporarily mounted in step S302 are sandwiched between the correction board 7 and the frame body 38 (step S303). In step S303, the frame 38 is attached to the circuit board 3 so as to communicate the opening 3a of the circuit board 3 after the temporary mounting of the solid-state imaging device 2 and the opening 38a of the frame body 38 itself. In this case, the plurality of fitting holes 38b of the frame body 38 sequentially pass through the through holes 2d of the solid-state imaging device 2 after provisional mounting and the board through holes 3b of the circuit board 3 as shown in FIG. Then, a plurality of fitting pins 7a protruding from the circuit board 3 are press-fitted. As a result, the frame body 38 is fixed in surface contact with the circuit board 3 with the openings 3a and 38a facing each other. The frame body 38 and the correction board 7 have a plurality of fitting pins 7a as support columns. The solid-state imaging device 2 and the circuit board 3 after temporary mounting are sandwiched inside the three-dimensional structure to be performed.

  Thereafter, the solid-state imaging device 2 and the circuit board 3 sandwiched between the three-dimensional structures are fully mounted (step S304). In step S304, the temporary mounting body inside the above-described three-dimensional structure, that is, the solid-state imaging device 2 and the circuit board 3 temporarily mounted in the temporary mounting process in step S302 are the three-dimensional structure formed by the correction substrate 7 and the frame body 38 described above. While maintaining the state of being sandwiched between the body, it is put into a predetermined heating device such as a reflow furnace and heat-treated by this heating device. By this heat treatment, each protruding electrode 2 c of the solid-state imaging device 2 is welded and bonded to each electrode pad of the circuit board 3. As a result, the flip-chip mounting of the solid-state imaging device 2 and the circuit board 3 is truly achieved, and the solid-state imaging device 2 is connected to the opening 38 a and the light receiving unit 2 a of the frame 38 through the opening 3 a of the circuit board 3. Are electrically connected to the circuit board 3 in a state of facing each other.

  Here, in the state after the main mounting (that is, after the true flip chip mounting), each fitting pin 7a of the correction substrate 7 cooperates with the frame body 38 to resist the thermal contraction force of the circuit substrate 3. Thus, the relative positional relationship between each pair of through holes 2d and the substrate through holes 3b is maintained. At the same time, the correction board 7 corrects the warp of the solid-state image pickup device 2 by the rigidity that is stronger than the thermal contraction force of the circuit board 3 and the support rigidity of the frame body 38, and as a result, the solid-state image pickup element 2. Is kept flat.

  Next, the adhesive 4 is filled between the solid-state imaging device 2 and the circuit board 3 after the main mounting process in step S304 (step S305). In this step S305, the adhesive 4 is filled in the gap between the solid-state image sensor 2 and the circuit board 3 as in the case of step S104 in the first embodiment, and further, the solid-state image sensor 2 on the circuit board 3 is filled. It is applied in the shape of a skirt along the periphery (see FIG. 10).

  Thereafter, the solid-state imaging device 2 that has been mounted on the circuit board 3 is sealed (step S306). In this step S306, as shown in FIG. 10, the cover glass 35 is fixed to the frame 38 so as to cover the opening 38a of the frame 38 communicating with the opening 3a of the circuit board 3 after the main mounting. . At this time, the adhesive 6 is interposed between the frame body 38 and the cover glass 35, and the frame body 38 and the cover glass 35 are bonded by the adhesive 6 and the gap between the frame body 38 and the cover glass 35 is closed. To do. The cover glass 35 attached to the frame body 38 in this manner seals the light receiving portion 2a inside while allowing light to enter the light receiving portion 2a of the solid-state imaging device 2 as in the case of the first embodiment. To do.

  The imaging unit 31 having the configuration shown in FIG. 10 can be manufactured by sequentially performing the manufacturing steps of steps S301 to S306 described above. As with the imaging unit 1 according to the first embodiment, the imaging unit 31 manufactured in this way includes a digital camera and a digital video camera, an endoscope for observing the inside of the organ of the subject, and imaging. It can be incorporated in various types of electronic imaging devices such as a mobile phone having a function.

  Next, the warp reducing action of the solid-state imaging device 2 by the three-dimensional structure including the correction substrate 7 and the frame body 38 described above will be described. FIG. 13 is a schematic diagram illustrating a state in which the warpage of the solid-state imaging device is reduced by the three-dimensional structure including the correction substrate and the frame.

  As shown in FIG. 13, the correction substrate 7 of the imaging unit 31 according to the third embodiment forms a three-dimensional structure 18 including a plurality of fitting pins 7a as columns in cooperation with the frame body 38. The three-dimensional structure 18 maintains a state in which the solid-state imaging device 2 and the circuit board 3 (that is, the temporary mounting body) after temporary mounting are sandwiched inside. The three-dimensional structure 18 sandwiching such a temporary mounting body is subjected to heat treatment in the main mounting process of step S304 described above.

  Here, the circuit board 3 in the three-dimensional structure 18 is thermally expanded by the heat treatment in step S304, and then thermally contracted while the temperature is lowered to room temperature. In this state, the three-dimensional structure 18 receives the thermal expansion force of the circuit board 3 and then receives the thermal contraction force of the circuit board 3 as shown in FIG. Such a three-dimensional structure 18 causes reaction forces F11 and F12 to act on the circuit board 3 and the solid-state imaging device 2 that are thermally deformed in this manner. Specifically, the correction board 7 and the frame body 38 in the three-dimensional structure 18 receive the thermal expansion force of the circuit board 3 through the fitting pins 7a, and then the circuit through the fitting pins 7a. The thermal contraction force of the substrate 3 is received. As described above, the correction board 7 has a rigidity higher than the thermal deformation force of the circuit board 3, and the frame body 38 against the circuit board 3 and the solid-state imaging device 2 that are thermally deformed in this way. Reaction forces F11 and F12 are applied based on the rigidity and the own rigidity.

  One reaction force F11 generated in the three-dimensional structure 18 is a force that opposes the thermal expansion force of the circuit board 3 and the solid-state imaging device 2, and the other reaction force F12 is the circuit board 3 and the solid-state imaging device. This is a force that opposes the heat shrinkage force of 2.

  The three-dimensional structure 18 suppresses the thermal expansion deformation of the solid-state imaging device 2 due to the thermal expansion deformation of the circuit board 3 during the heat treatment by the reaction force F11 that opposes the thermal expansion force of the circuit board 3 described above. The stress resulting from the thermal expansion of the solid-state imaging device 2 is sufficiently absorbed. As a result, the three-dimensional structure 18 reduces the warpage of the solid-state imaging device 2 caused by such stress. In this case, the correction substrate 7 in the three-dimensional structure 18 reduces the warpage of the solid-state imaging device 2 in cooperation with the frame body 38.

  On the other hand, the three-dimensional structure 18 suppresses the thermal contraction deformation of the solid-state imaging device 2 due to the thermal contraction deformation of the circuit board 3 when the temperature is lowered by the reaction force F12 that opposes the thermal contraction force of the circuit board 3 described above. As a result, the stress caused by the thermal contraction of the solid-state imaging device 2 is sufficiently absorbed. As a result, the three-dimensional structure 18 reduces the warpage of the solid-state imaging device 2 caused by such stress. In this case, the correction substrate 7 in the three-dimensional structure 18 reduces the warpage of the solid-state imaging device 2 in cooperation with the frame body 38.

  As described above, the correction substrate 7 corrects the warpage of the solid-state imaging device 2 after the heat treatment, specifically, after flip-chip mounting on the circuit substrate 3, with the support of the frame body 38. By such an action of the correction substrate 7 and the frame 38, the solid-state imaging device 2 on the circuit substrate 3 can maintain the flat state of the light receiving portion 2a more firmly. In the above-described three-dimensional structure 18, the plurality of fitting pins 7 a are respectively opposed to the plurality of through holes 2 d and the plurality of substrate through holes 3 b against the thermal expansion force or thermal contraction force of the circuit board 3. Maintain positional relationships for each pair.

  Note that the three-dimensional structure 18 is similarly heated before and after the heat treatment (for example, thermosetting treatment of the adhesives 4 and 6) after the flip chip mounting process of the solid-state imaging device 2 described above. Deformation can be suppressed, and as a result, warpage of the solid-state imaging device 2 due to thermal contraction of the circuit board 3 can be reduced.

  As described above, in the third embodiment of the present invention, the plurality of fitting pins protruding through the circuit board on which the solid-state imaging device is temporarily mounted are fitted into the plurality of fitting holes formed in the frame. The circuit board and the frame are relatively fixed to each other, and a solid structure accompanying the thermal contraction deformation of the circuit board is formed by a three-dimensional structure formed by the frame and the correction board using the plurality of fitting pins as support columns. The warp of the image sensor is corrected, and the rest is configured in the same manner as in the first embodiment. For this reason, while enjoying the same operation effect as Embodiment 1 mentioned above, such a correction board and a frame cooperate with each other, and heat contraction deformation of a solid-state image sensing device accompanying heat contraction deformation of a circuit board is carried out. As a result, the thermal contraction difference between the circuit board after mounting by the heat treatment and the solid-state image sensor can be more firmly suppressed, and the warpage of the solid-state image sensor can be surely reduced.

  In Embodiments 1 to 3 described above, the cover glass is attached after the mounting of the solid-state imaging device on the circuit board. However, the present invention is not limited thereto, and the cover glass is attached before the mounting of the solid-state imaging device on the circuit board is completed. The mounting step of mounting the circuit board and the solid-state imaging device may be performed with the cover glass attached.

  Specifically, in Embodiment 1 described above, the cover glass 5 is attached to the temporary mounting body 10 after the temporary mounting process of Step S102, for example, the process before the main mounting process of Step S103, and the cover glass 5 is attached. The temporary mounting body 10 may be used to perform the main mounting process of step S103. On the other hand, in the above-described second embodiment, before the solid-state imaging device 2 is actually mounted in step S201, that is, after the temporary mounting step of the solid-state imaging device 2 in step S102, the provisional connection between the solid-state imaging device 2 and the circuit board 3 is performed. The cover glass 5 may be attached to the mounting body, and the mounting (heat treatment) of the solid-state imaging device 2 and the circuit board 3 may be performed using the temporary mounting body to which the cover glass 5 is attached.

  Here, in the first and second embodiments, the cover glass 5 is fixed to the circuit board 3 with the plurality of fitting pins 7a fitted in the plurality of fitting holes 5a. A three-dimensional structure including the correction substrates 7 and 27 and the cover glass 5 is formed using the combination pin 7a as a support. This three-dimensional structure can reduce the warpage of the solid-state imaging device 2 in the same manner as the three-dimensional structure 18 in the third embodiment described above. Here, the cover glass 5 is formed with a plurality of fitting holes 5a corresponding to the plurality of substrate through-holes 3b as described above, and a plurality of substrate through-holes as in the case of the frame 38 in the third embodiment. A plurality of fitting pins 7a protruding through 3b are fitted and fixed in the plurality of fitting holes 5a to form a three-dimensional structure including the correction substrates 7 and 27 and the plurality of fitting pins 7a. The cover glass 5 in such a three-dimensional structure functions as a support member that supports correction of the warp of the solid-state imaging device 2 by the correction substrates 7 and 27.

  On the other hand, in the above-described third embodiment, the cover glass 35 is attached to the three-dimensional structure 18 after the main mounting process of step S304, for example, the process of step S303, and the three-dimensional structure 18 to which the cover glass 35 is attached. May be used to perform the main mounting process of step S304.

  In Embodiments 1 to 3 described above, the cover glass is attached to seal the solid-state image sensor 2, but the translucent member used to seal the solid-state image sensor 2 is the cover described above. It is not limited to glass, but may be a resin such as acrylic, a low-pass filter, an IR cut filter, a plate-like optical member such as a lens or a prism.

  In the first to third embodiments described above, the case where the solid-state imaging device 2 is flip-chip mounted on the circuit board 3 is exemplified. However, the present invention is not limited thereto, and the solid-state imaging device 2 is attached to the circuit board 3 with a silver paste material. The circuit board 3 and the solid-state imaging device 2 may be electrically connected by a metal wire bonding technique.

  Further, in the first to third embodiments described above, each through hole 2d of the solid-state imaging device 2 and each substrate through hole 3b of the circuit board 3 are disposed to face each other. Each pair of through-holes 2d and substrate through-holes 3b may not face each other. In this case, each fitting pin 7a penetrating each pair of through-holes 2d and substrate through-holes 3b may be bent or curved according to this non-opposing arrangement.

  In the first to third embodiments described above, each through-hole 2d of the solid-state imaging device 2 is formed outside the plurality of protruding electrodes 2c. Further, it may be formed at the same column or in the same row as the protruding electrode 2c, or may be formed between the light receiving portion 2a and the protruding electrode 2c.

  As described above, the imaging unit according to the present invention is useful for an imaging unit including a solid-state imaging device such as a CCD or a CMOS, and particularly reduces the warpage of the solid-state imaging device due to thermal contraction of the circuit board. Suitable for imaging units that can

1, 2, 31 Image pickup unit 2 Solid-state image pickup device 2a Light receiving portion 2b Drive circuit portion 2c Projection electrode 2d Through hole 3 Circuit board 3a Opening portion 3b Substrate through hole 4, 6 Adhesive 5,35 Cover glass 5a Fitting hole 7, 27 Correction board 7a Fitting pin 10 Temporary mounting body 15 Mounting body 18 Three-dimensional structure 38 Frame body 38a Opening portion 38b Fitting hole

Claims (12)

A solid-state imaging device in which a plurality of through holes are formed outside the light receiving unit;
An opening corresponding to the light receiving portion and a plurality of substrate through holes corresponding to the plurality of through holes; a circuit board on which the solid-state imaging device is mounted with the light receiving portion and the opening facing each other;
A plurality of rod-shaped members that pass through the pair of through-holes and the substrate through-holes, and a correction substrate that has a rigidity higher than the thermal contraction force of the circuit board and corrects the warp of the solid-state imaging device; ,
An imaging unit comprising:   2. The imaging unit according to claim 1, wherein the rod-shaped member maintains a relative positional relationship between the pair of through holes and the substrate through holes against a thermal contraction force of the circuit board.   3. The imaging unit according to claim 1, wherein the correction substrate press-fits the plurality of rod-shaped members into the plurality of through holes and relatively fixes the solid-state imaging device.   The thermal expansion coefficient difference between the correction substrate and the solid-state imaging device is smaller than the thermal expansion coefficient difference between the solid-state imaging device and the circuit board. The imaging unit described in 1.   The imaging unit according to claim 4, wherein a thermal expansion coefficient of the correction substrate is the same as a thermal expansion coefficient of the solid-state imaging device.   The imaging unit according to claim 4, wherein a thermal expansion coefficient of the correction board is smaller than a thermal expansion coefficient of the circuit board.   A plurality of fitting holes corresponding to the plurality of substrate through holes are formed, and the plurality of rod-shaped members protruding through the plurality of substrate through holes are fitted and fixed to the plurality of fitting holes. 7. A support member for forming a three-dimensional structure including a correction substrate and a plurality of the rod-shaped members, and further assisting correction of warpage of the solid-state imaging device by the correction substrate. The imaging unit according to any one of the above.   The imaging unit according to claim 7, wherein the support member is a translucent member that closes an opening of the circuit board.   The imaging unit according to claim 7, wherein the support member is a frame having an opening communicating with the opening of the circuit board.   The rod-shaped member penetrates the pair of through-holes and the substrate through-holes when both the circuit board and the solid-state imaging element are thermally expanded. The imaging unit described.   The said rod-shaped member penetrates a pair of said through-hole and the said board | substrate through-hole before the said circuit board and the said solid-state image sensor thermally expand, The any one of Claims 1-9 characterized by the above-mentioned. Imaging unit. The solid-state imaging device includes a plurality of protruding electrodes that are electrically connected to the circuit board on the outside of the light receiving unit,
The imaging unit according to claim 1, wherein the plurality of through holes are formed outside the plurality of protruding electrodes.

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