JP2010205780A - Imaging unit - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an imaging unit quickly radiating heat caused by driving of a solid state imaging element. <P>SOLUTION: The imaging unit 1 is equipped with a printed board 3, in which an opening 3a is formed to face a light receiving part 2a of a solid state imaging element 2, and the solid state imaging element 2 is flip-chip mounted in such manner as the light receiving part 2a faces the opening 3a. A heat receiving part 3c of the printed board 3 faces a drive circuit part 2b of the solid state imaging element 2, to receive the heat generated by the solid state imaging element 2 through an adhesive 4. A heat radiation layer 3d of the printed board 3 radiates the heat of the solid state imaging element 2, which the heat receiving part 3c has received, to the outside of the printed board 3. <P>COPYRIGHT: (C)2010,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 having a heat dissipation structure that enhances the heat dissipation of the solid-state imaging device.

  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 image pickup device includes an image pickup unit including a solid-state image pickup device such as a CCD or a CMOS, and forms an optical image of a subject on a light receiving portion of the solid-state image pickup device by an optical system such as a lens. Image data of the subject is acquired (captured) by the conversion process.

  Note that the solid-state imaging device of the imaging unit can be driven optimally under the temperature conditions specified in the design specifications to capture a high-quality image. However, the heat generated when the solid-state image sensor is driven causes the temperature of the solid-state image sensor to rise, and noise such as dark current is generated as the temperature of the solid-state image sensor rises. This heat noise causes a decrease in the function of the solid-state imaging device such as a reduction in image quality, making it difficult to capture high-quality images with the solid-state imaging device.

  In order to prevent the deterioration of the function due to the temperature rise of such a solid-state image sensor, a heat dissipation structure for radiating heat of the solid-state image sensor inside the image pickup unit has been proposed in recent years. As a heat dissipation structure of such an image pickup unit, for example, the contact surface of the frame is brought into contact with the back surface of the internal solid-state image sensor (that is, the surface opposite to the light receiving portion) through the back opening of the solid-state image sensor package. In some cases, the heat of the solid-state imaging device is conducted to the entire frame through the frame (see Patent Document 1).

JP 2006-345196 A

  By the way, the drive circuit unit of the solid-state image sensor is the part that generates the largest amount of heat when the solid-state image sensor is driven, and is generally arranged around the light receiving unit. However, in the imaging unit having the above-described conventional heat dissipation structure, heat is radiated from the opposite surface of the light receiving unit and the drive circuit unit, that is, from the back side of the solid-state imaging device. When heat is generated, it is difficult to quickly dissipate heat from the solid-state image sensor, and as a result, it is difficult to prevent a functional deterioration due to a temperature rise of the solid-state image sensor. Such problems of the prior art become more prominent as the solid-state imaging device has higher pixels and higher processing speed.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide an imaging unit capable of quickly dissipating heat accompanying driving of a solid-state imaging device.

  In order to solve the above-described problems and achieve the object, an imaging unit according to the present invention has an opening that faces a light receiving portion of a solid-state imaging device, and the light receiving portion and the opening face each other. In an imaging unit including a circuit board on which the solid-state imaging device is mounted, the solid-state imaging device emits at least a heat transfer portion that contacts the driving circuit unit of the solid-state imaging device and the driving circuit unit of the solid-state imaging device. A heat receiving unit that receives heat via the heat transfer unit, and a heat radiating unit that radiates heat of the solid-state imaging device received by the heat receiving unit.

  In the imaging unit according to the present invention as set forth in the invention described above, the heat dissipation part is a heat dissipation layer that is a part of the circuit board and has a larger surface area than the heat receiving part.

  In the imaging unit according to the present invention as set forth in the invention described above, the heat transfer section is a filling member that fills a gap between the circuit board and the solid-state imaging device.

  In the imaging unit according to the present invention as set forth in the invention described above, the filling member is a thermally conductive adhesive that bonds the circuit board and the solid-state imaging device.

  In the imaging unit according to the present invention as set forth in the invention described above, the heat transfer section is a metal member that thermally connects the drive circuit section of the solid-state image sensor and the heat receiving section.

  In the image pickup unit according to the present invention as set forth in the invention described above, at least a part of the heat dissipation layer is exposed to the outside of the circuit board.

  In the imaging unit according to the present invention, the solid-state imaging device is mounted on the circuit board in such a manner that the light-receiving unit of the solid-state imaging element and the opening of the circuit board face each other, and the heat transfer unit drives at least the solid-state imaging element. The heat receiving part is in contact with the circuit part, the heat receiving part is opposed to the drive circuit part of the solid-state image sensor, receives heat generated by the solid-state image sensor through the heat transfer part, and the heat radiating part is received by the heat receiving part. The heat of the solid-state imaging device is dissipated. For this reason, the heat of the solid-state image sensor that has generated heat due to the driving of the drive circuit section can be quickly taken away from the solid-state image sensor after the heat generation, and the heat from the solid-state image sensor can be quickly transmitted to the heat radiating section. There is an effect that heat generated by driving the solid-state imaging device can be quickly dissipated after the heat is generated.

  DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, exemplary embodiments of an imaging unit according to the 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 flexible 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. FIG. 2 is a schematic diagram showing the imaging unit viewed from the direction D1 shown in FIG. FIG. 3 is a schematic diagram illustrating the imaging unit viewed from the direction D2 illustrated in FIG. As shown in FIGS. 1 to 3, the imaging unit 1 according to the first embodiment includes a solid-state imaging device 2 that captures an image of a subject, a printed circuit board 3 on which the solid-state imaging device 2 is flip-chip mounted, and such a solid-state imaging. The adhesive 4 which fixes the element 2 and the printed circuit board 3 and functions as a heat transfer part, and the cover glass 5 which closes the opening part 3a of the printed circuit board 3 facing the light-receiving part 2a of the solid-state image sensor 2 are provided.

  The solid-state imaging device 2 is a bare chip-shaped image sensor 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. FIG. 4 is a schematic diagram illustrating an example of a solid-state imaging element of the imaging unit according to the first embodiment. 4 shows the appearance of the solid-state imaging device 2 as viewed from the front side of the bare chip, that is, from the light receiving unit side. As shown in FIG. 4, the solid-state imaging device 2 includes a driving circuit in which a light receiving unit 2 a that receives light from a subject and a driving circuit for performing an imaging operation are formed on the front side of a chip substrate such as a substrate. And a group of electrodes 11 and 12 electrically connected to the drive circuit unit 2b.

  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 center side of the solid-state imaging device 2. The drive circuit unit 2b is formed around the light receiving unit 2a. The electrode groups 11 and 12 are for electrically connecting the drive circuit unit 2b and the printed circuit board 3, and are connected to the drive circuit unit 2b via wiring (not shown) formed on the chip substrate. This is realized by fixing the metal bump 2c to each of the plurality of electrode pads 2d that are electrically connected. As shown in FIG. 4, the electrode groups 11 and 12 are respectively formed on two opposing sides of the periphery of the drive circuit unit 2b. The necessary number of electrode groups of the solid-state imaging device 2 may be formed on one or more sides of the periphery of the drive circuit unit 2b.

  As shown in FIG. 1, the solid-state imaging device 2 having such a configuration is flip-chip mounted on the printed circuit board 3 so that the opening 3 a and the light receiving unit 2 a of the printed circuit board 3 face each other. In this case, each metal bump 2 c of the solid-state imaging device 2 is electrically connected to the wiring layer 3 b of the printed circuit board 3, and the drive circuit unit 2 b faces the heat receiving unit 3 c formed on the printed circuit board 3. Thus, in the solid-state imaging device 2 mounted on the printed circuit board 3, the light receiving unit 2a receives light from the subject via the cover glass 5 covering the opening 3a of the printed circuit board 3, and the received light is received. The photoelectric conversion process is performed. The drive circuit unit 2b generates an image signal of the subject based on the signal photoelectrically processed by the light receiving unit 2a, and the generated image signal is applied to each metal bump 2c (that is, the electrode groups 11 and 12 described above). To the printed circuit board 3 side.

  The printed circuit board 3 is a multilayer circuit board including a circuit structure for realizing the imaging function of the solid-state imaging device 2 and a heat dissipation structure of the solid-state imaging device 2. Specifically, as shown in FIGS. 1 and 3, the printed circuit board 3 includes a wiring layer 3 b in which circuit wiring and the like necessary for realizing the imaging function of the solid-state imaging device 2 are patterned, and as described above. A heat receiving portion 3c that receives the heat of the solid-state imaging device 2 in a flip-chip mounted state, a heat-dissipating layer 3d that dissipates the heat of the solid-state imaging device 2 transmitted from the heat receiving portion 3c, and the wiring layer 3b and the heat-dissipating layer 3d And an insulating layer 3e that forms an outermost layer of the printed circuit board 3, and an insulating layer 3f that forms an outermost layer of the printed circuit board 3. Further, in the multilayer structure of the printed circuit board 3, an opening 3 a that faces the light receiving portion 2 a of the solid-state imaging device 2 described above is formed. 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 wiring layer 3b is a conductive layer in which circuit wiring and the like necessary for realizing the imaging function of the solid-state imaging device 2 are patterned as described above, and is provided on each electrode of the electrode groups 11 and 12 of the solid-state imaging device 2. A plurality of corresponding electrode pads (not shown) are provided. Each metal bump 2c of the solid-state imaging device 2 is connected to each electrode pad of the wiring layer 3b by a thermocompression bonding technique or an ultrasonic connection technique. An insulating layer 3f is formed on the wiring layer 3b.

  The heat receiving portion 3c is realized by using a metal member having high thermal conductivity, and is formed in a through hole that penetrates the insulating layer 3e and the heat dissipation layer 3d of the printed board 3. Further, the heat receiving surface of the heat receiving unit 3c is formed in a frame shape corresponding to the drive circuit unit 2b of the solid-state imaging device 2, for example (see FIG. 3). The heat receiving portion 3c is opposed to the drive circuit portion 2b of the solid-state image pickup device 2 in the form of being flip-chip mounted on the printed circuit board 3, and heat generated by the solid-state image pickup device 2 due to the drive is passed through the adhesive 4. Receive heat. The heat receiving part 3c transfers the heat received from the solid-state imaging device 2 to the heat radiation layer 3d. In addition, as a metal member which forms this heat receiving part 3c, the alloy etc. which contain aluminum, copper, gold | metal | money, or at least one of these metals are mentioned, for example.

  The heat radiating layer 3d functions as a heat radiating part that radiates the heat of the solid-state imaging device 2 received by the heat receiving part 3c described above to the outside of the printed circuit board 3. Specifically, the heat dissipation layer 3d is a solid pattern metal layer formed on substantially the entire surface of the insulating layer 3g, and has a surface area larger than that of the heat receiving surface of the heat receiving portion 3c described above, as shown in FIG. Have In this case, the surface area of the heat dissipation layer 3d is substantially equal to the surface area of the printed circuit board 3 excluding the opening 3a. The heat radiating layer 3d is thermally connected to the heat receiving portion 3c, receives heat from the solid-state imaging device 2 through the heat receiving portion 3c, and radiates the heat of the received solid imaging device 2 to the outside of the printed board 3. In addition, as a metal member which forms this heat radiating layer 3d, the alloy containing at least one of these metals etc. are mentioned, for example, aluminum, copper, or gold | metal | money.

  The insulating layer 3e is formed between the wiring layer 3b and the heat dissipation layer 3d described above, and insulates the wiring layer 3b and the heat dissipation layer 3d. The insulating layers 3f and 3g form the outermost layer of the printed circuit board 3 as described above. Specifically, the insulating layer 3f is formed so as to cover the wiring layer 3b and protects the wiring layer 3b. On the other hand, the insulating layer 3g is the lowermost layer of the printed circuit board 3, and protects the heat dissipation layer 3d described above.

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

  The adhesive 4 is an example of a filling member that fills the gap between the solid-state imaging device 2 and the printed circuit board 3 described above, and functions as a heat transfer unit that contacts at least the drive circuit unit 2 b of the solid-state imaging device 2. Specifically, as shown in FIGS. 1 and 2, the adhesive 4 is a gap between the solid-state imaging device 2 and the printed circuit board 3 that is flip-chip mounted on the printed circuit board 3. The region other than the region between the portions 3a is filled. Note that the adhesive 4 is applied until a skirt shape is formed along the periphery of the solid-state imaging device 2. The adhesive 4 closes the gap between the solid-state imaging device 2 and the printed circuit board 3 with respect to the outside of the printed circuit board 3, thereby preventing foreign matter from entering the light receiving unit 2a and unnecessary light from entering. At the same time, the adhesive 4 bonds the solid-state imaging device 2 and the printed circuit board 3 to each other so that the mounting strength between the solid-state imaging device 2 and the printed circuit board 3, that is, the bonding strength between each metal bump 2c and the wiring layer 3b. Reinforce. As described above, the adhesive 4 in a mode in which the solid-state imaging device 2 and the printed circuit board 3 are bonded is in a state of being in contact with the drive circuit unit 2b and the heat receiving unit 3c described above, and is generated by heat generated by the drive circuit unit 2b. The heat of the image sensor 2 is transmitted to the heat receiving portion 3c.

  Here, as the adhesive 4 described above, in the first embodiment, for example, a heat conductive adhesive that includes a metal filler such as silver or copper and has improved thermal conductivity is applied. Thereby, the heat conduction efficiency between the solid-state imaging device 2 and the heat receiving portion 3c described above can be increased, and as a result, the heat dissipation effect of the solid-state imaging device 2 can be enhanced. Such an adhesive 4 functions as a heat transfer portion in the present invention. Note that the adhesive 4 is not limited to the above-described material, and may be an adhesive made of a material having a heat conductivity as much as possible, for example, an adhesive using a resin member such as epoxy or urethane. Good.

  The cover glass 5 is an optical 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 imaging device 2, and as shown in FIGS. Is fixed to the printed circuit board 3 so as to be closed. The cover glass 5 transmits light from the subject to the light receiving unit 2a side of the solid-state imaging device 2, and prevents foreign matter from entering through the opening 3a.

  Next, the heat radiation action of the imaging unit 1 according to the first embodiment of the present invention will be described. FIG. 5 is a schematic diagram for explaining the heat radiation action of the imaging unit according to the first embodiment of the present invention. In FIG. 5, the wavy arrow indicates the flow of heat generated by the solid-state imaging device 2.

  As described above, the solid-state imaging device 2 flip-chip mounted on the printed circuit board 3 generates heat as the drive circuit unit 2b is driven each time it receives light from the subject and picks up an image of the subject. As shown in FIG. 5, the heat generated by the solid-state imaging device 2 is transmitted to the adhesive 4 that comes into contact with the drive circuit portion 2b. As described above, the heat of the solid-state imaging device 2 transmitted to the adhesive 4 is transmitted to the heat receiving unit 3c facing the drive circuit unit 2b.

  The heat receiving part 3c receives the heat of the solid-state imaging device 2 through the adhesive 4, and transmits the heat of the received solid-state imaging device 2 to the heat radiation layer 3d. Here, the heat dissipation and heat dissipation properties of the heat dissipation layer 3d increase with an increase in the surface area of the heat dissipation layer 3d, and as described above, the surface area of the heat dissipation layer 3d is approximately the same as the surface area of the entire printed circuit board 3. To the maximum. The heat radiating layer 3d quickly dissipates the heat of the solid-state imaging device 2 transmitted from the heat receiving portion 3c described above, and is solid outside the printed circuit board 3 (on the opposite side to the solid-state imaging device 2) via the insulating layer 3g. The heat of the image sensor 2 is efficiently radiated. Due to the heat radiation action of the heat receiving portion 3c and the heat radiation layer 3d and the like, the heat of the solid-state imaging device 2 is removed, and as a result, the temperature rise of the solid-state imaging device 2 is suppressed. The heat of the solid-state image sensor 2 is also radiated from the back side of the solid-state image sensor 2 as shown in FIG.

  Here, in an imaging unit (not shown) having a conventional heat dissipation structure, a heat dissipation member is disposed on the back side of the solid-state image sensor, and heat is radiated from the back side of the solid-state image sensor via this heat dissipation member. For this reason, the heat generated with the driving of the solid-state image sensor is radiated to the outside through the inside of the chip substrate such as the substrate of the fixed image sensor. There is a time difference from heat generation to heat dissipation of the solid-state imaging device. Due to this, it is difficult for the imaging unit having such a conventional heat dissipation structure to quickly dissipate the heat of the solid-state imaging device. When the solid-state imaging device suddenly generates heat as it is driven, this solid-state imaging It is difficult to suppress the temperature rise of the element.

  In contrast, in the imaging unit 1 according to the first embodiment of the present invention, when the solid-state imaging device 2 generates heat, the drive circuit unit 2b, which is the part that generates the largest amount of heat, and the heat receiving unit 3c face each other. The heat receiving portion 3 c receives heat from the drive circuit portion 2 b through the adhesive 4. Therefore, the heat receiving portion 3c can quickly take away the heat generated by driving the drive circuit portion 2b from the solid-state image pickup device 2 after the heat generation, and the heat taken from the solid-state image pickup device 2 can be removed from the heat dissipation layer. 3d can be promptly transmitted. As a result, the heat of the solid-state imaging device 2 is quickly radiated from the heat-dissipating layer 3d after the heat generation. As a result, even if the solid-state imaging device 2 suddenly generates heat upon driving, the solid-state imaging device 2 2 can be suppressed, and the function deterioration due to the temperature increase of the solid-state imaging device 2 can be prevented.

  The imaging unit 1 having a heat dissipation structure according to the present invention includes various aspects such as a digital camera and a digital video camera, an endoscope for observing the inside of an organ of a subject, a mobile phone having an imaging function, and the like. It can be incorporated in the electronic imaging apparatus. The imaging unit 1 inside the electronic imaging device functions as an imaging function unit of the electronic imaging device, and quickly dissipates heat of the solid-state imaging device 2 as described above, thereby suppressing a temperature rise of the solid-state imaging device 2. In this case, the heat of the solid-state imaging device 2 radiated by the imaging unit 1 is discharged to the outside of the electronic imaging device through, for example, the housing of the electronic imaging device.

  As described above, in the first embodiment of the present invention, the heat receiving unit that receives the heat of the solid-state image sensor at the position in the printed circuit board facing the drive circuit unit of the solid-state image sensor in the flip-chip mounted mode. And the heat of the solid-state imaging device received by the heat receiving portion is radiated to the outside of the printed board through the heat radiating layer in the printed board. For this reason, the heat of the solid-state imaging device that is generated by driving the drive circuit unit can be quickly taken away from the solid-state imaging device after the heat generation, and the heat taken from the solid-state imaging device can be quickly transmitted to the heat dissipation layer. Can do. Thereby, it is possible to realize an imaging unit that can quickly dissipate heat generated by driving the solid-state imaging device after heat generation.

  By using the image pickup unit according to the first embodiment, even when the solid-state image sensor is driven to heat and the heat generation at the time of driving the solid-state image sensor is abrupt with the increase in the number of pixels and the processing speed of the solid-state image sensor. The rapid heat of the image sensor can be dissipated quickly after heat generation, thereby suppressing the temperature rise of the solid-state image sensor within the design range. As a result, the function due to the temperature rise of the solid-state image sensor A decrease can be prevented.

  In Embodiment 1 of the present invention, since the surface area of the heat dissipation layer is made larger than that of the heat receiving surface of the heat receiving portion described above, the heat radiating surface for radiating the heat of the solid-state imaging device should be made as large as possible. As a result, the heat dissipating property and heat dissipating property of the heat dissipating layer can be improved, and as a result, the heat of the solid-state imaging device can be dissipated more rapidly by the heat dissipating layer.

  Furthermore, in Embodiment 1 of the present invention, a heat transfer member such as an adhesive is filled in the gap between the drive circuit portion of the solid-state imaging element and the heat receiving portion of the printed circuit board facing each other, and the solid state is passed through this heat transfer member. Since heat is transmitted from the image sensor to the heat receiving unit, the heat of the solid-state image sensor can be received more quickly by the heat receiving unit, and as a result, the heat of the solid-state image sensor is more effectively dissipated. be able to.

(Embodiment 2)
Next, a second embodiment of the present invention will be described. In the first embodiment described above, the heat of the solid-state imaging device 2 is radiated from the lowermost layer side (that is, the insulating layer 3g side) of the printed circuit board 3 by the heat radiating layer 3d, but in the second embodiment, the solid-state imaging device is radiated. A heat radiating portion is formed on the mounting surface side, and the heat of the solid-state imaging device is radiated from the mounting surface side of the solid-state imaging device by the heat radiating portion.

  FIG. 6 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. 6, the imaging unit 21 according to the second embodiment includes a printed circuit board 23 instead of the printed circuit board 3 of the imaging unit 1 according to the first embodiment described above. The printed circuit board 23 includes a heat dissipation structure necessary for dissipating heat from the solid-state image sensor 2 from the mounting surface side of the solid-state image sensor 2. The wiring layer 3b of the printed board 23 is formed between the insulating layers 3e and 3g, and is electrically connected to the electrode groups 11 and 12 of the solid-state imaging device 2 through through holes or the like. In the second embodiment, the electrode groups 11 and 12 (that is, the plurality of electrode pads 2d and the plurality of metal bumps 2c described above) of the solid-state imaging device 2 are not particularly shown in FIG. 2 is disposed on a chip substrate other than a region facing a heat receiving portion (a heat receiving portion 23c described later) of the printed board 23. Other configurations are the same as those of the first embodiment, and the same reference numerals are given to the same components.

  As described above, the printed circuit board 23 includes a heat dissipation structure necessary for dissipating the heat of the solid-state image sensor 2 from the mounting surface side of the solid-state image sensor 2. Specifically, the printed board 23 includes a heat receiving portion 23c on the insulating layer 3e instead of the heat receiving portion 3c described above, and a heat dissipation layer 3d thermally connected to the heat receiving portion 23c is provided between the insulating layers 3e and 3f. Prepare for. In addition, as described above, the printed circuit board 23 includes the wiring layer 3b electrically connected to the electrode groups 11 and 12 of the solid-state imaging device 2 between the insulating layers 3e and 3g. In the printed circuit board 23, the insulating layer 3g protects the wiring layer 3b, and the insulating layer 3f protects the heat dissipation layer 3d. The printed circuit board 23 has the same structure as the printed circuit board 3 of the imaging unit 1 according to the first embodiment described above, except for the heat dissipation structure and the layer structure associated therewith.

  The heat receiving portion 23c is realized by using a metal member having high thermal conductivity, and is opposed to the drive circuit portion 2b of the solid-state imaging device 2 in a form flip-chip mounted on the printed circuit board 23 and opposed to the electrode groups 11 and 12. Is formed on the insulating layer 3e. The heat receiving unit 23c receives heat accompanying the driving of the solid-state imaging device 2 through the adhesive 4 in a state of being opposed to the drive circuit unit 2b of the solid-state imaging device 2, and the heat from the solid-state imaging device 2 that has received the heat. Is transmitted to the heat dissipation layer 3d. In addition, as a metal member which forms this heat receiving part 23c, the alloy etc. which contain aluminum, copper, or gold | metal | money or at least one of these metals are mentioned, for example.

  Here, the heat dissipation layer 3d of the printed board 23 is a solid metal layer having a larger surface area than the heat receiving surface of the heat receiving portion 23c described above, and is formed on the insulating layer 3e. The heat radiating layer 3d is thermally connected to the heat receiving portion 23c, and radiates the heat of the solid-state imaging device 2 received by the heat receiving portion 23c from the mounting surface side of the solid-state imaging device 2 to the outside of the printed board 23.

  Next, the heat radiation action of the imaging unit 21 according to the second embodiment of the present invention will be described. FIG. 7 is a schematic diagram for explaining the heat radiation action of the imaging unit according to the second embodiment of the present invention. In FIG. 7, a wavy arrow indicates the flow of heat generated by the solid-state imaging device 2.

  The heat generated by the solid-state imaging device 2 when the drive circuit unit 2b is driven is transmitted to the adhesive 4 in contact with the drive circuit unit 2b as in the case of the first embodiment. As shown in FIG. 7, the heat of the solid-state imaging device 2 transmitted to the adhesive 4 is transmitted to the heat receiving portion 23c facing the drive circuit portion 2b.

  The heat receiving part 23c receives the heat of the solid-state imaging device 2 through the adhesive 4, and transmits the heat of the received solid-state imaging device 2 to the heat radiation layer 3d. Here, as described above, the heat dissipating property and heat dissipating property of the heat dissipating layer 3d increase as the surface area of the heat dissipating layer 3d increases, and the surface area of the heat dissipating layer 3d is approximately the same as the surface area of the entire printed circuit board 23. The case will be the largest. The heat radiating layer 3d quickly dissipates the heat of the solid-state imaging device 2 transmitted from the heat receiving portion 23c, and is solid outside the printed circuit board 23 (on the mounting surface side of the solid-state imaging device 2) via the insulating layer 3f. The heat of the image sensor 2 is efficiently radiated.

  Due to the heat radiation action of the heat receiving portion 23c and the heat radiation layer 3d, the heat of the solid-state image sensor 2 is removed, and as a result, the temperature rise of the solid-state image sensor 2 is suppressed. The heat of the solid-state image sensor 2 is also radiated from the back side of the solid-state image sensor 2 as shown in FIG.

  As with the imaging unit 1 according to the first embodiment, the imaging unit 21 having the heat dissipation structure as described above is an endoscope for observing the inside of an organ of a subject, including a digital camera and a digital video camera. It can be incorporated in various types of electronic imaging devices such as a mobile phone having an imaging function. Here, as shown in FIG. 7, the imaging unit 21 radiates the heat of the solid-state imaging device 2 from the mounting surface side of the solid-state imaging device 2. For this reason, in the electronic imaging device, a heat dissipation mechanism such as a heat sink that receives the heat of the solid-state imaging device 2 emitted from the imaging unit 21 is arranged collectively on the mounting surface side of the solid-state imaging device 2 of the imaging unit 21. be able to. As a result, the heat dissipation mechanism of the electronic image pickup apparatus incorporating the image pickup unit 21 can be easily realized.

  As described above, in the second embodiment of the present invention, the driving circuit unit of the solid-state imaging device is formed on the upper layer of the printed circuit board on which the solid-state imaging device is flip-chip mounted, that is, the substrate layer on the mounting surface side of the solid-state imaging device. A heat dissipation layer thermally connected to the heat receiving portion opposite to the heat sink is formed, and the heat of the solid-state imaging device is radiated to the outside of the printed circuit board through this heat dissipation layer, and the others are configured in the same manner as in the first embodiment. . For this reason, while enjoying the effect similar to Embodiment 1 mentioned above, the heat | fever of a solid-state image sensor can be radiated | emitted from the mounting surface side of a solid-state image sensor, Thereby, the heat dissipation mechanism of an electronic imaging device can be performed simply. Can be realized.

(Embodiment 3)
Next, a third embodiment of the present invention will be described. In Embodiment 1 described above, the adhesive 4 that fills the gap between the solid-state imaging device 2 and the printed circuit board 3 is used as the heat transfer portion that transfers heat from the solid-state imaging device 2 to the heat receiving portion 3c. In the third embodiment, a metal member is interposed between the drive circuit unit of the solid-state image sensor and the heat receiving unit of the printed circuit board, and heat is transmitted from the solid-state image sensor to the heat receiving unit by the metal member.

  FIG. 8 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. 8, the imaging unit 31 according to the third embodiment includes a solid-state imaging element 32 instead of the solid-state imaging element 2 of the imaging unit 1 according to the first embodiment described above. The solid-state imaging device 32 further includes a metal member for thermally connecting the drive circuit unit 2b and the heat receiving unit 3c. Other configurations are the same as those of the first embodiment, and the same reference numerals are given to the same components.

  As described above, the solid-state imaging device 32 further includes a metal member for thermally connecting the drive circuit unit 2b and the heat receiving unit 3c. FIG. 9 is a schematic diagram illustrating an example of a solid-state imaging device of the imaging unit according to the third embodiment. FIG. 9 shows the appearance of the solid-state imaging device 32 as viewed from the front side of the bare chip, that is, from the light receiving unit side. As shown in FIG. 9, the solid-state imaging device 32 includes heat transfer unit groups 33 and 34 on the drive circuit unit 2b. Other configurations of the solid-state imaging device 32 are the same as those of the first embodiment, and the same components are denoted by the same reference numerals.

  The heat transfer section groups 33 and 34 are for thermally connecting the heat receiving section 3c and the drive circuit section 2b described above. Specifically, the heat transfer unit groups 33 and 34 are realized by fixing heat transfer bumps 32e made of a metal member to each of the plurality of dummy pads 32f formed on the drive circuit unit 2b. Each dummy pad 32f is a pad for attaching a plurality of heat transfer bumps 32e on the drive circuit portion 2b, and is not electrically connected to the drive circuit portion 2b. Each heat transfer bump 32e is realized by using a metal member having high thermal conductivity, and is attached to each dummy pad 32f by a thermocompression bonding technique or an ultrasonic connection technique.

  The heat transfer unit groups 33 and 34 may be arranged on the drive circuit unit 2b. For example, as shown in FIG. 9, the heat transfer unit groups 33 and 34 may be arranged in the vicinity of the electrode groups 11 and 12 described above. The electrode groups 11 and 12 may be arranged at positions separated by a predetermined distance or more, or may be arranged in a distributed manner in the drive circuit unit 2b. In addition, examples of the metal member that forms the heat transfer bump 32e include copper or gold, or an alloy containing at least one of these metals.

  As shown in FIG. 8, the solid-state imaging device 32 having such a configuration is flip-chip mounted on the printed circuit board 3 so that the opening 3 a and the light receiving unit 2 a of the printed circuit board 3 face each other. In this case, each heat transfer bump 32e of the solid-state imaging device 32 is connected to the heat receiving portion 3c facing the drive circuit portion 2b as described above by a thermocompression bonding technique or an ultrasonic connection technique. Each of the heat transfer bumps 32e thermally connects the drive circuit unit 2b of the solid-state imaging device 32 and the heat receiving unit 3c of the printed circuit board 3.

  Here, the heat transfer bump 32e that thermally connects the drive circuit portion 2b and the heat receiving portion 3c is extremely higher than the adhesive 4 that fills the gap between the solid-state imaging device 2 and the printed board 3 described above. Has thermal conductivity. The heat transfer bumps 32e having high thermal conductivity transfer heat from the solid-state imaging device 2 to the heat receiving portion 3c more efficiently and quickly than the adhesive 4. Thus, the imaging unit 31 having a structure in which the drive circuit unit 2b and the heat receiving unit 3c are thermally connected by the heat transfer bump 32e has the adhesive 4 interposed between the drive circuit unit 2b and the heat receiving unit 3c. As compared with the case, heat can be taken away from the solid-state imaging device 2 more quickly. As a result, the heat of the solid-state imaging device 32 can be radiated more rapidly after the solid-state imaging device 32 generates heat.

  As described above, in the third embodiment of the present invention, the driving circuit unit of the solid-state imaging element and the heat receiving unit of the printed circuit board that are opposed to each other are thermally connected by the metal member, and the solid member is interposed via the metal member. The heat of the image sensor is transmitted to the heat receiving part, and the others are configured in the same manner as in the first embodiment. For this reason, while enjoying the same operation effect as Embodiment 1 mentioned above, compared with the case where a resin member is interposed between this drive circuit part and a heat receiving part, it is heat from a solid-state image sensing device more rapidly. As a result, it is possible to realize an imaging unit that can dissipate heat of the solid-state imaging device more rapidly after the solid-state imaging device generates heat.

  In the first and second embodiments described above, the heat dissipation layer 3d that dissipates the heat generated by the solid-state imaging device 2 is covered with the insulating layer. However, the present invention is not limited thereto, and at least a part of the heat dissipation layer 3d You may expose to the exterior of a printed circuit board. FIG. 10 is a schematic cross-sectional view illustrating a configuration example of the imaging unit according to the modification of the first embodiment of the present invention. As shown in FIG. 10, in the imaging unit 41 according to the modification of the first embodiment, at least a part of the heat dissipation layer 3d is exposed from the lower surface side of the printed circuit board 3, that is, the insulating layer 3g side. Other configurations are the same as those of the first embodiment, and the same reference numerals are given to the same components.

  In such an imaging unit 41, the heat dissipation layer 3d is exposed in a form that forms the lowermost layer of the printed circuit board 3 in cooperation with the insulating layer 3g described above. Since the exposed heat radiation layer 3d can be in direct contact with the outside (gas, etc.) of the printed circuit board 3, it is more efficient and quicker than the case where it is covered with the insulating layer 3g as described above. The heat of the solid-state imaging device 2 can be radiated. The exposed region of the heat dissipation layer 3d may be at least part of the heat dissipation layer 3d, but a wider range is desirable. This is because the contact area between the outside of the printed circuit board 3 and the heat dissipation layer 3d increases as the exposed area of the heat dissipation layer 3d increases, and as a result, the heat dissipation performance of the heat dissipation layer 3d is improved.

  Although not particularly illustrated, the heat dissipation layer 3d in the imaging unit 21 according to the second embodiment described above may be exposed so as to form the uppermost layer of the printed circuit board 23 in cooperation with the insulating layer 3f of the printed circuit board 23. . Also in this case, the same effect as the imaging unit 41 shown in FIG. 10 is obtained.

  On the other hand, in Embodiments 1 to 3 described above, the heat of the solid-state imaging device is radiated from the heat-radiating layer or the heat-radiating portion formed in the printed board. The heat radiation of the solid-state image sensor may be radiated by the heat radiation layer or the heat radiation part in the printed circuit board, and the heat of the solid-state image sensor may be further radiated by the heat radiation plate on the back surface of the solid-state image sensor.

  In the above-described third embodiment, the plurality of heat transfer bumps 32e are fixed in advance on the drive circuit unit 2b of the solid-state imaging device 32. When the solid-state imaging device 32 is flip-chip mounted on the printed circuit board 3 in advance, the heat-transfer bumps 32e on the heat receiving portion 3c and the dummy pads 32f of the solid-state imaging device 32 are respectively fixed. You may connect.

  Furthermore, in Embodiments 1 to 3 described above, the printed circuit board having a five-layer structure is illustrated. However, the multilayer structure of the printed circuit board of the imaging unit according to the present invention is not limited to this, and the heat receiving portion, the heat dissipation layer, or What is necessary is just to include heat dissipation structures, such as a thermal radiation part, and the number of layers is not specifically limited to five layers.

  In Embodiments 1 to 3 described above, the adhesive is filled in the gap between the solid-state imaging device and the printed board. However, the present invention is not limited thereto, and the filling member is filled in the gap between the solid-state imaging element and the printed board. May be a sealing member that seals the gap between the solid-state imaging device and the printed circuit board.

It is a cross-sectional schematic diagram which shows one structural example of the imaging unit concerning Embodiment 1 of this invention. It is a schematic diagram which shows the imaging unit seen from the direction D1 shown in FIG. It is a schematic diagram which shows the imaging unit seen from the direction D2 shown in FIG. 2 is a schematic diagram illustrating an example of a solid-state image sensor of the imaging unit according to the first embodiment; FIG. FIG. 3 is a schematic diagram for explaining a heat radiation action of the imaging unit according to the first embodiment of the present invention. It is a cross-sectional schematic diagram which shows one structural example of the imaging unit concerning Embodiment 2 of this invention. It is a schematic diagram for demonstrating the thermal radiation effect | action of the imaging unit concerning Embodiment 2 of this invention. It is a cross-sectional schematic diagram which shows one structural example of the imaging unit concerning Embodiment 3 of this invention. FIG. 6 is a schematic diagram illustrating an example of a solid-state imaging element of an imaging unit according to a third embodiment. It is a cross-sectional schematic diagram which shows one structural example of the imaging unit concerning the modification of Embodiment 1 of this invention.

1, 21, 31, 41 Imaging unit 2,32 Solid-state imaging device 2a Light receiving portion 2b Drive circuit portion 2c Metal bump 2d Electrode pad 3,23 Printed circuit board 3a Opening portion 3b Wiring layer 3c, 23c Heat receiving portion 3d Heat radiation layer 3e, 3f 3g Insulating layer 4 Adhesive 5 Cover glass 11, 12 Electrode group 32e Heat transfer bump 32f Dummy pad 33, 34 Heat transfer part group

Claims (6)

In an imaging unit comprising a circuit board on which the solid-state imaging element is mounted in an aspect in which an opening facing the light-receiving part of the solid-state imaging element is formed and the light-receiving part and the opening are opposed to each other.
At least a heat transfer section in contact with the drive circuit section of the solid-state imaging device;
A heat receiving unit facing the drive circuit unit of the solid-state image sensor and receiving heat generated by the solid-state image sensor via the heat transfer unit;
A heat dissipating part for dissipating the heat of the solid-state imaging device received by the heat receiving part;
An imaging unit comprising:   The imaging unit according to claim 1, wherein the heat radiating part is a heat radiating layer that is a part of the circuit board and has a larger surface area than the heat receiving part.   The imaging unit according to claim 1, wherein the heat transfer unit is a filling member that fills a gap between the circuit board and the solid-state imaging device.   The imaging unit according to claim 3, wherein the filling member is a heat conductive adhesive that bonds the circuit board and the solid-state imaging device.   The imaging unit according to claim 1, wherein the heat transfer unit is a metal member that thermally connects the drive circuit unit of the solid-state imaging device and the heat receiving unit.   The imaging unit according to claim 2, wherein at least a part of the heat dissipation layer is exposed to the outside of the circuit board.

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