JP2006173248A - Manufacturing process of solid state imaging device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a manufacturing process of a solid state imaging device in which an image sensor can be mounted precisely on a substrate. <P>SOLUTION: In the manufacturing process of a solid state imaging device 1 including a substrate 2 mounting an image sensor 9 on one side and mounting an electronic component 30 on the opposite side, the image sensor 9 is mounted on the substrate 2 and then the electronic component 30 is mounted thus manufacturing a solid state imaging device. Since the image sensor 9 is mounted on the substrate 2 prior to the electronic component 30, a solid state imaging device where the image sensor 9 is mounted with high positional precision can be manufactured. The electronic component 30 is preferably connected with the substrate 2 by using conductive adhesive 31. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a method for manufacturing a solid-state imaging device. More specifically, the present invention relates to a method for manufacturing a solid-state imaging device by mounting an imaging element on a substrate with high positional accuracy.

  A solid-state imaging device is used by being incorporated in an electronic device such as a mobile phone, and generally has a structure in which a lens, an optical unit that holds the lens, an imaging device on which a captured image is formed by the lens, and the like are mounted on a substrate. It has become. In such a solid-state imaging device, it is required to mount the imaging element on the substrate with high accuracy. In addition, since an image pickup device such as a CCD has a microlens that is easily damaged, it is necessary to manufacture the microlens in consideration of not damaging the microlens.

  Therefore, for example, as disclosed in Patent Document 1, a conventional solid-state imaging device prepares a substrate having an opening in a portion where an imaging element is arranged, and after mounting an electronic component on one side of the substrate, the imaging element is placed on the opposite surface. Are joined.

Japanese Patent Laid-Open No. 11-354769

  However, if an image sensor is to be mounted later on a substrate on which electronic components are already arranged, the electronic components become an obstacle. For this reason, there arises a problem that the image pickup device cannot be mounted on the substrate with high positional accuracy and the image pickup device is inclined. This problem is particularly noticeable when the substrate is a flexible printed circuit board (hereinafter simply referred to as FPC) or when an electronic component is disposed close to the image sensor.

  Therefore, an object of the present invention is to provide a method for manufacturing a solid-state imaging device by mounting an imaging element on a substrate with high accuracy.

  The object is a method of manufacturing a solid-state imaging device including a substrate on which an image sensor is mounted on one surface and an electronic component is mounted on the opposite surface, and after mounting the image sensor on the substrate, This can be achieved by a method for manufacturing a solid-state imaging device on which the electronic component is mounted. According to the present invention, since the imaging device is mounted on the substrate before the electronic component, a solid-state imaging device in which the imaging device is mounted with high positional accuracy can be manufactured.

  Further, the electronic component can be bonded to the substrate using a conductive adhesive. And a step of providing a bump for connection at a predetermined position of the circuit pattern formed on the substrate, abutting the terminal of the image sensor on the bump, and bonding the bump and the terminal by ultrasonic bonding. But you can. The substrate may be provided with an opening, and the imaging element may be mounted on the substrate such that an imaging region faces the opening. The electronic component may be mounted at a position corresponding to the image sensor on the substrate. Furthermore, the substrate may be a flexible printed circuit board.

  According to the present invention, it is possible to manufacture a solid-state imaging device in which an imaging element is mounted on a substrate with high positional accuracy.

  Hereinafter, a method for manufacturing a solid-state imaging device according to an embodiment of the present invention will be described with reference to the drawings. 1A to 1D are diagrams sequentially illustrating manufacturing steps of the solid-state imaging device 1. Description will be made sequentially from FIG. The FPC 2 serving as a substrate has an imaging opening 2c formed in a portion where the imaging element 9 is mounted. The imaging element 9 is mounted on the lower surface side of the FPC 2 with the imaging region 9a facing the opening 2c. For example, it is bonded to a circuit pattern (not shown) formed on the FPC 2 using a flip chip mounting technique and fixed with an adhesive 10a such as underfill.

  Next, in the step shown in FIG. 1B, the electronic component 30 is mounted at a position corresponding to the image sensor 9 on the upper surface of the FPC 2 (the surface opposite to the surface on which the image sensor 9 is mounted). A circuit pattern (not shown) is also formed on the upper surface of the FPC 2. The electronic component 30 is mounted by applying a conductive adhesive 31 (for example, silver paste) to a predetermined terminal portion (electrode). Thus, with the imaging device 9 and the electronic component 30 mounted on the FPC 2, for example, by heating at about 130 ° C. for about 1 hour, the conductive adhesive 31 is melted and solidified to firmly bond the electronic component 30 to the FPC 2. To do.

  In the step shown in FIG. 1A, since there is no electronic component that obstructs the FPC 2 as in the prior art, the image sensor 9 can be mounted with high positional accuracy. Further, in the process shown in FIG. 1B, since the electronic component 30 is connected to the FPC 2 using the conductive adhesive 31, the processing temperature can be kept lower than when solder is used. In general, electronic components are bonded to a substrate using solder. When electronic components are joined with solder, the substrate is exposed to a high temperature of about 250 ° C. or higher. If the image pickup device is mounted on such a substrate, the microlens of the image pickup device may be damaged by the soldering processing temperature. Therefore, it has been common to mount an image sensor on a substrate after mounting an electronic component on the substrate as in Patent Document 1 described above. However, when the conductive adhesive 31 is used as in the process of this embodiment, the electronic component 30 can be bonded to the FPC 2 at a lower processing temperature than in the case of solder. Therefore, it is possible to realize a manufacturing process in which the image sensor 9 is mounted on the FPC 2 before the electronic component 30.

  When solder bonding is employed, solder balls and flux may scatter during the bonding process and adhere to the imaging region 9a of the imaging element 9 through the opening 2c of the FPC 2. In order to prevent this problem, it is conceivable to fix the translucent member at a position where the opening 2c on the upper surface of the FPC 2 is closed as in Patent Document 1, but in this case, a separate process of fixing the translucent member is necessary. Thus, the manufacturing process becomes complicated. In contrast, when the conductive adhesive 31 is used as in the process of the present embodiment, the electronic component 30 can be bonded to the FPC 2 at a lower processing temperature than in the case of solder. It can prevent adhering to the region 9a. Therefore, it is possible to realize a manufacturing process in which the image sensor 9 is mounted on the FPC 2 before the electronic component 30.

  Thereafter, as shown in FIG. 1C, an adhesive 10 b is applied to the holder 3, and the FPC 2 is bonded in the leg 3 </ b> BT formed at the lower part of the holder 3. Then, the lens holder 4 and the holder 3 to which the lenses 5, 6 and 7 are bonded in advance are screwed at the CN portion to adjust the focus, and a fixing adhesive is applied to the screwed portion to fix the holder 3 and the lens holder 4. And fix. In the last step shown in FIG. 1D, the solid-state imaging device 1 is completed by applying another adhesive 10c from the inner peripheral surface of the leg 3BT to the side surface of the adhesive 10a and the imaging element 9. .

  The structure in which the image sensor 9 is mounted on the FPC 2 shown in FIG. 1A can be manufactured by, for example, the steps shown in FIGS. In the step shown in FIG. 2, an FPC 2 having a diced imaging element 9 and an imaging opening 2 c is prepared. Bumps (for example, gold bumps) 11 are provided at predetermined positions on a circuit pattern (not shown) on the FPC 2. The pad 9PA of the image sensor 9 is brought into contact with the bump 11 of the FPC 2, and ultrasonic waves are applied from the image sensor 9 side to bond the bump 11 and the pad 9PA of the image sensor 9. Thereafter, underfill 10a is applied to fix both. In the method shown in FIG. 2, the bump 11 is formed on the FPC 2, so that the imaging of the image sensor 9 is performed when the bump 11 is formed or when the bump 11 is transported for forming the bump 11. It is possible to prevent the region 9a from becoming dusty or scratched. In addition, since it is not necessary to clean the imaging element 9, the structure shown in FIG. 1A can be manufactured with a simplified process.

  The structure shown in FIG. 1A can also be manufactured by the process shown in FIG. In the step shown in FIG. 3, bumps 11 are provided (bumped) on the pads 9PA of the wafer-like image pickup device 9 (image pickup device chip) before dicing. The image sensor 9 is separated into individual pieces in a dicing process. The imaging device 9 is washed by a known process, and an FPC 2 having an imaging opening 2c is prepared. The bumps 11 of the image sensor 9 are brought into contact with the pattern of the FPC 2 and ultrasonic waves are applied from the image sensor 9 side to bond the bumps 11 and the pattern. Thereafter, an underfill 10a is applied between the image sensor 9 and the FPC 2 to fix them. The method shown in FIG. 3 includes a cleaning process for removing dust when the bumps 11 are formed. Therefore, the method shown in FIG. 3 is more complicated than the process shown in FIG. 2, but the chip is easily positioned when the bumps 11 are formed. The structure shown in 1 (A) can be manufactured.

  Even in the step shown in FIG. 4, the structure shown in FIG. 1A can be manufactured. In the step shown in FIG. 4, bumps 11 are provided on the pads 9PA of the diced image sensor 9. The imaging device 9 is washed, and an FPC 2 having an imaging opening 2c is prepared. The pattern of the FPC 2 is brought into contact with the bump 11 of the image sensor 9 and ultrasonic waves are applied from the image sensor 9 side to bond the bump 11 and the pattern. An underfill 10a is applied between the image sensor 9 and the FPC 2 to fix them. The method shown in FIG. 4 includes a cleaning step for removing dust when the bumps 11 are formed, and it takes a long time to position the chip when the bumps 11 are formed. There is. Therefore, although more complicated than the steps shown in FIGS. 2 and 3, the structure shown in FIG. 1A can be manufactured. From the above, the structure shown in FIG. 1A can be manufactured by the steps shown in FIGS. 2 to 4, but it is desirable to adopt the step shown in FIG.

  Below, the specific structural example of the solid-state imaging device 1 which can be manufactured with the manufacturing method demonstrated above is demonstrated. 5A and 5B are views showing the appearance of the solid-state imaging device 1. FIG. 5A is a plan view of the solid-state imaging device 1, FIG. 5B is a side view, and FIG. 6 is a cross-sectional view taken along the line AA in FIG. 5A, and FIG. 7 is a cross-sectional view taken along the line BB in FIG.

  In FIG. 5, the solid-state imaging device 1 is electrically connected to an external unit (circuit), an optical unit including a lens holder 4 that holds the lens 5 and the like, a holder 3 that supports the lens holder 4, and the like. The FPC 2 is provided. As shown in FIG. 6, the lens holder 4 holds three lenses 5, 6, and 7 therein. The lens holder 4 is supported by the holder 3. The holder 3 is formed of a rectangular tube-shaped base 3a and a cylindrical head 3b formed integrally on the base 3a. Although not shown in the figure, screw portions are formed on the outer peripheral surface of the lens holder 4 and the inner peripheral surface of the cylindrical head 3b, and are screwed together (see CN in FIG. 6).

  The holder 3 holds an optical filter 8 such as an IR filter that cuts infrared light below the lenses 5, 6, and 7 (on the side opposite to the subject). Further, the holder 3 holds the FPC 2 on which the image sensor 9 is mounted below the optical filter 8.

  Here, the relationship between the FPC 2 and the holder 3 will be described in more detail. As shown in FIG. 5C, the FPC 2 employed in the solid-state imaging device 1 includes a connecting portion 2b and an imaging element 9 that are extended to the outside of the holder 3 in order to connect to the circuit side of an external device (for example, a camera). Includes an element mounting portion 2a. The element mounting portion 2a of the FPC 2 is reduced in size (area) to substantially the same size as the imaging element 9. The lower end side (the side opposite to the lenses 5 to 7) of the base portion 3a of the holder 3 is a leg portion 3BT having a peripheral wall shape. A surface 3 c perpendicular to the optical axis of the lenses 5 to 7 of the holder 3 is in contact with the upper surface of the element mounting portion 2 a of the FPC 2 at a position facing the connection portion with the imaging element 9. Thereby, the image pick-up element 9 and the lenses 5-7 can be positioned in the optical axis direction of the lenses 5-7. The element mounting portion 2a of the FPC 2 is in the lower part of the holder 3 and is housed in a space surrounded by the leg portions 3BT. And the connection part 2b becomes the form pulled out from the holder 3 outside. The leg 3BT is formed with a notch 3DE for pulling out the connecting portion 2b. A connector 21 for connection with an external device is fixed to the end of the connection portion 2b. Thus, since the element mounting portion 2a and the connection portion 2b are formed on the same substrate 2, the configuration can be simplified. Moreover, since the notch 3DE is formed in the holder 3, the connection part 2b can be easily pulled out of the holder 3.

  The element mounting portion 2a is formed in a shape corresponding to the size in the leg portion 3BT of the holder 3, and the outer periphery is in contact with the inner peripheral surface of the leg portion 3BT. Therefore, the element mounting part 2a is just fitted inside the leg part 3BT and positioned. In the above configuration, the holder 3 holds the lenses 5 to 7 at a fixed position via the lens holder 4, and the element mounting portion 2a holds the image sensor 9 at a predetermined position. The element mounting portion 2a is fitted and aligned in the leg portion 3BT of the holder 3. Therefore, the solid-state imaging device 1 has a structure in which the lenses 5 to 7 and the imaging element 9 are accurately positioned in a direction orthogonal to the optical axis.

  In the solid-state imaging device 1, as shown in FIGS. 6 and 7, a circuit pattern (not shown) is formed on the lower surface side of the element mounting portion 2a, and this pattern and the imaging element 9 are flip-chip connected, for example. Yes. Thus, if the image sensor 9 is arranged on the lower side of the substrate, the size in the height direction can be reduced. An imaging opening 2c is formed at the center of the element mounting portion 2a on which the imaging element 9 is mounted, corresponding to the imaging area 9a of the imaging element 9. The electronic component 30 can be mounted on the upper surface (the surface on the lens 5-7 side) of the element mounting portion 2a.

  Further, the lower end of the leg portion 3BT of the holder 3 is formed so as to protrude from the lower surface of the image sensor 9 to the side opposite to the lenses 5-7. Thus, if the leg 3BT of the holder 3 is provided long, it is possible to realize a structure in which the image pickup device 9 is completely accommodated in the space surrounded by the leg 3BT. With such a structure, it is possible to protect the image sensor 9 by preventing the image sensor 9 from being damaged due to contact with other components.

  FIG. 8 is an enlarged view of the inside of the circle CR in FIG. Here, the FPC 2 and the image sensor 9 are fixed to the inner surface of the leg 3BT of the holder 3 using the adhesive 10c. An underfill 10a serving as a first adhesive is applied from the periphery of the connection portion of the image pickup device 9 mounted on the FPC 2 to the side surface, and the FPC 2 and the image pickup device 9 are connected. It is preferable to select an underfill (first adhesive) 10a having a viscosity that does not flow into the imaging region 9a of the imaging element 9 due to a capillary phenomenon or the like.

  Further, a second adhesive 10 c for reliably preventing the image sensor 9 from peeling from the inner peripheral surface of the leg 3BT to the underfill 10 a and the side surface of the image sensor 9 is applied. FIG. 5C illustrates the adhesive 10c applied to the inner surface of the leg 3BT. If an adhesive 10c having a high viscosity is used, the adhesive 10c protrudes downward (on the opposite side to the lenses 5 to 7) from the lower end of the leg 3BT of the holder 3 when solidified in a raised state. When the adhesive 10c protrudes in this manner, another component hits the adhesive 10c, and an external force is applied to the image sensor 9 through the adhesive 10c. Therefore, it is preferable to use an adhesive 10c having a relatively low viscosity. By using an adhesive having a low viscosity, it becomes easy to flow into the lenses 5 to 7, so that if there is a gap between the underfill and the holder 3, this gap can be filled. Moreover, it is more preferable to employ a material having elasticity, for example, a rubber-based material, as the adhesive 10c. When a rubber-based adhesive is used, it is possible to reduce a load applied to the image pickup element 9 from the leg portion 3BT by an elastic force.

  In addition, a third adhesive 10b is applied to the contact surface between the surface 3c of the holder 3 and the upper surface of the element mounting surface 2a of the FPC 2 and is adhered to each other. In addition, it is preferable to use the 3rd adhesive agent 10b with a comparatively high viscosity so that it may not flow into the effective area | region of incident light required for imaging.

  In the manufacturing method of the solid-state imaging device 1 described above, since the imaging element 9 is mounted before the electronic component 30 is mounted on the FPC 2, the mounting accuracy of the imaging element 9 on the FPC 2 is improved. In addition, since the electronic component 30 is connected to the FPC 2 using the conductive adhesive 31 having a low processing temperature, it is possible to avoid the problem that occurs due to the image sensor 9 being mounted first. Further, when mounting the image pickup device 9 on the FPC 2, the connection bump 11 is first provided on the FPC 2, and the terminal of the image pickup device 9 is brought into contact with the bump 11 to be ultrasonically bonded, thereby simplifying the process. .

  In the above, the case where the flexible FPC 2 is used is illustrated as an example of the substrate, but a hard printed circuit board (PCB: Printed Circuit Board) formed of an epoxy resin or the like may be used. Moreover, although the said Example demonstrated the case where a solid-state imaging device was manufactured using a silver paste as a conductive adhesive, you may use a gold paste. Further, in the above embodiment, the case where the conductive adhesive is used as a more preferable embodiment has been described. However, the electronic component is mounted on the substrate using ACF (anisotropic conductive film), ACP (anisotropic conductive paste), solder, or the like. You may connect to. As described above, when solder is used, solder balls and flux are generated as dust. Therefore, in order to prevent dust from entering the imaging region 9a of the image sensor 9, the opening 2c of the substrate 2 is covered with a translucent cover. What is necessary is just to manufacture by shielding with a member.

  The preferred embodiment of the present invention has been described in detail above, but the present invention is not limited to the specific embodiment, and various modifications can be made within the scope of the gist of the present invention described in the claims.・ Change is possible.

(A)-(D) are the figures which showed the manufacturing step of the solid-state imaging device in order. It is the figure which showed the manufacturing process of the structure with which the image pick-up element is mounted on FPC shown in FIG. 1 (A). It is the figure which showed the other manufacturing process of the structure in which the image pick-up element is mounted on FPC shown in FIG. 1 (A). It is the figure which showed the other manufacturing process of the structure in which the image pick-up element is mounted on FPC shown in FIG. 1 (A). It is the figure which showed the external appearance of the solid-state imaging device which can be manufactured with the manufacturing method of an Example, (A) is a top view of a solid-state imaging device, (B) is the same side view, (C) is the bottom view. It is AA arrow sectional drawing in FIG. 5 (A). It is BB arrow sectional drawing in FIG. 5 (A). It is the figure which expanded and showed the inside of the circle CR of FIG.

Explanation of symbols

1 Solid-state imaging device 2 FPC (substrate)
3 Holder (Lens holding member)
3a Square cylindrical base 3b Round cylindrical head 3BT Leg 4 Lens holder (lens holding member)
5, 6, 7 Lens 8 Filter 9 Image sensor 10 Adhesive 10a Underfill (adhesive)
10b, 10c Adhesive 30 Electronic component 31 Conductive adhesive

Claims (6)

A method of manufacturing a solid-state imaging device including a substrate on which an imaging element is mounted on one surface and an electronic component is mounted on the opposite surface,
A method of manufacturing a solid-state imaging device, wherein the electronic component is mounted after mounting the imaging element on the substrate. The method of manufacturing a solid-state imaging device according to claim 1, wherein the electronic component is bonded to the substrate using a conductive adhesive. Providing a bump for connection at a predetermined position of the circuit pattern formed on the substrate, contacting a terminal of the imaging device to the bump, and bonding the bump and the terminal by ultrasonic bonding. The method for manufacturing a solid-state imaging device according to claim 1, wherein the solid-state imaging device is manufactured. The solid-state imaging according to any one of claims 1 to 3, wherein the substrate is provided with an opening, and the imaging element is mounted on the substrate so that an imaging region faces the opening. Device manufacturing method. 5. The method for manufacturing a solid-state imaging device according to claim 1, wherein the electronic component is mounted at a position corresponding to the imaging element of the substrate. 6. The method for manufacturing a solid-state imaging device according to claim 1, wherein the substrate is a flexible printed circuit board.

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