JP2004079779A - Solid state imaging device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a thin type solid state imaging device which prevents a warping of an FPC in a mounting region of a lens assembly and a solid state imaging device without using a reinforcing plate. <P>SOLUTION: The lens assembly is disposed on an upper surface at one end of an FPC 1. The solid state imaging device 2 is disposed on a lower surface at one end of the FPC 1 so that an opening 1a provided at the one end of the FPC 1 is located between the lens assembly and the solid state imaging device 2. The FPC 1 is bent so as to face the one end to form a crevice 15, so that adhesives 7 are injected into the crevice 15 and are solidified corresponding to a disposition region of the lens assembly. A peripheral circuit element 6 is provided at a position facing the solid state imaging device 2 in the crevice 15, and the peripheral circuit element 6 is connected to a circuit pattern 12 of the FPC 1 via a bump electrode 6b. An exposure part of the circuit pattern 12 is coated with a protection material 14 having a smaller coefficient of linear expansion than the adhesives 7. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a solid-state imaging device using a solid-state imaging device.
[0002]
[Prior art]
In a conventional device of this type, a solid-state imaging device is usually connected using a hard camera circuit board. In this case, a flexible printed circuit board (hereinafter, referred to as FPC) is used as the hard camera circuit board. And connected to a circuit on the main body side via the FPC. However, the FPC is used in a bent state, and the connection portion between the camera circuit board and the FPC is easily peeled off by the bending of the FPC, and the circuit pattern of the FPC is easily broken. Therefore, a solid-state imaging device or the like may be directly mounted on the FPC so that the FPC does not need to be connected to a hard camera circuit board.
[0003]
An example is shown in FIGS. 3 and 4, in which an opening 10 a is provided at one end of the FPC 10, and the opening 10 a is arranged between the imaging surface 20 a and the lens assembly 30 on the back side of the FPC 10. The solid-state imaging device 20 is mounted via a bump electrode 20b. Further, the FPC 10 is bent, and the drive circuit 60 of the solid-state imaging device 20 or an image processing device (not shown) is mounted on the back of the solid-state imaging device 20 using the bump electrode 60b. On the front side of the FPC 10, a lens assembly 30 that holds the lens 40 is arranged around the opening 10a so that a subject image is formed on the imaging surface 20a. The other end of the FPC 10 is connected to a main circuit board (not shown). Since the FPC 10 is a soft material, the FPC 10 is bent when the solid-state imaging device 20 is mounted. For this reason, the lens assembly 30 cannot be fixed to the FPC 10 as it is, and a hard reinforcing plate 50 for improving the rigidity of the FPC 10 needs to be interposed at a position on the FPC 10 where the lens assembly 30 is fixed. Was.
[0004]
[Problems to be solved by the invention]
In such a conventional configuration, it is necessary to provide the hard reinforcing plate 50 on the FPC 10, so that there is a limit to the size reduction by the thickness of the reinforcing plate 50. Further, since the reinforcing plate 50 is used, the number of components increases, the number of manufacturing steps increases, and the manufacturing operation becomes complicated.
[0005]
Therefore, the present invention provides a thin solid-state imaging device that prevents bending of an FPC at a mounting portion of a lens assembly without using a reinforcing plate.
[0006]
[Means for Solving the Problems]
The solid-state imaging device of the present invention includes a solid-state imaging device and a lens assembly that holds a lens for forming a subject image on the solid-state imaging device. The lens assembly is disposed on one side of one end of a flexible printed board, and the solid-state imaging device is provided at one end of the flexible printed board between the solid-state imaging device and the lens assembly. As the opening is located, it is arranged on the other surface of the one end of the flexible printed board, and the flexible printed board is bent near the one end, and the part facing the one end and the one end are A gap is formed between the lens assemblies, and an adhesive is interposed in the gap corresponding to a position where the lens assembly is disposed. As described above, since the adhesive is interposed in the space formed by bending the flexible printed circuit board in accordance with the position of the lens assembly, the solidification of the adhesive allows the lens assembly to be used without using a reinforcing plate. It is possible to prevent the FPC from bending at the mounting portion, and to provide a thin solid-state imaging device.
[0007]
It is preferable that the adhesive covers the entirety of the gap. The adhesive preferably has a water absorption of 0.1 to 1% from the viewpoint of preventing the adhesive from absorbing moisture and expanding, thereby preventing the resistance value of the circuit pattern of the FPC from increasing.
[0008]
At a portion facing the one end of the flexible printed board, a peripheral circuit element located in the gap is provided, and between the peripheral circuit element and the circuit pattern of the flexible printed board, And an exposed portion of the circuit pattern is covered with a protective material having a smaller linear expansion coefficient than the adhesive. By using a protective material having a smaller coefficient of linear expansion than the adhesive, thermal expansion due to external heat can be reduced, an external force exerted on the circuit pattern of the flexible printed circuit board is reduced, and damage to the circuit pattern can be prevented.
[0009]
It is preferable that the peripheral circuit element is provided at a position facing the solid-state imaging device. Further, it is preferable that the protective material is a synthetic resin and is provided so as to extend from an exposed portion of the circuit pattern to the peripheral circuit element. Preferably, the protective material has a coefficient of linear expansion of 5 to 50 ppm / ° C.
[0010]
BEST MODE FOR CARRYING OUT THE INVENTION
An embodiment of the present invention will be described with reference to the drawings.
[0011]
As shown in FIG. 1, a flexible printed circuit board 1 is used as a camera circuit board. An opening 1a is formed at one end of a flexible printed circuit board (hereinafter, referred to as FPC) 1. In the solid-state imaging device 2 having an imaging surface 2a formed on the surface, the circuit pattern around the opening 1a is exposed so that the opening 1a is arranged between the imaging surface 2a and the lens assembly 3. It is mounted on the back side of the FPC 1 by a flip chip method via 2b. Further, the FPC 1 is bent in a U-shape near one end thereof, and a peripheral circuit element 6 such as a drive circuit of the solid-state imaging element 2 is placed at a position facing the back surface of the solid-state imaging element 2 in the same manner as before. Are exposed and mounted on the back surface of the FPC 1 by a flip chip method via the bump electrodes 6b. A lens assembly 3 holding a lens 4 is fixed to the front side of the FPC 1 so that a subject image is formed on an imaging surface 2a around the opening 1a. The other end of the FPC 1 is connected to a main circuit board (not shown).
[0012]
The lens assembly 3 is formed by fitting the first lens barrel 31 to the second lens barrel 32, and optical members such as the lens 4 are held in the first lens barrel 31. The filter 5 is mounted in the second lens barrel 32, and is fixed to the surface of the FPC 1 with the lower end surface 3a of the second lens barrel 32 centered on the opening 1a. The first lens barrel 31 is provided so as to advance and retreat toward the solid-state imaging device 2 with respect to the second lens barrel 32, and adjusts the distance between the lens 4 and the imaging surface 2a to move the lens 4 and the filter 5 together. Focusing is enabled so that a subject image is formed on the imaging surface 2a of the solid-state imaging device 2 by the transmitted incident light.
[0013]
A gap 15 is formed between the FPCs 1 bent in a U-shape, and the solid-state imaging device 2 and the peripheral circuit element 6 are mounted on the FPC 1 in the gap 15 in opposition. The adhesive 7 is injected into the space 15 over the entire space 15, thereby filling and solidifying the space 15. Although the adhesive 7 is provided corresponding to the position where the lens assembly 3 is disposed, it is also preferable that the adhesive 7 be provided over the entire gap 15 as in this embodiment.
[0014]
By injecting and solidifying the adhesive 7 into the space 15, the solid-state imaging device 2 and the peripheral circuit device 6 are connected to the FPC 1 by the bump electrodes 2b and 6b, the lens assembly 3 and the like. The rigidity of the entire area around the arrangement site is improved, so that the periphery is hardened regardless of the use of the soft FPC 1, and the solid-state image sensor 2, the peripheral circuit element 6, and the lens assembly 3 are arranged at the arrangement area. No bending of the FPC 1 occurs.
[0015]
As the adhesive 7, an adhesive having a water absorption of about 0.1 to 1% is used. This is to prevent the increase in the resistance value of the circuit pattern of the FPC 1 and the breakage of the circuit pattern by reducing the hygroscopic expansion of the adhesive 7.
[0016]
FIG. 2 shows another embodiment of the present invention. As described with reference to FIG. 1, when the adhesive 7 is injected and solidified into the gap 15 formed by bending the FPC 1, for example, the solid-state imaging device of the present invention is mounted on a camera or the like. If the temperature is increased by heating when the camera is used, the adhesive 7 thermally expands and stress is generated in the bump electrode portion, and there is a risk that the circuit pattern of the FPC 1 to which the bump electrodes 2b and 6b are connected is broken.
[0017]
FIG. 2 shows an example of a configuration for preventing such a problem from occurring. That is, the FPC 1 has a configuration in which a circuit pattern 12 is formed on a base 11, and the circuit pattern 12 is protected by covering the circuit pattern 12 with a coverlay 13. The circuit pattern 12 is exposed by removing the coverlay 13 around the opening 1a, and the solid-state imaging device 2 is connected to the exposed circuit pattern 12 via the bump electrode 2b. Next, an underfill 8, which is a sealing agent mainly composed of an epoxy resin or a silicon resin mixed with a liquid sealing material, is applied around the solid-state imaging device 2. The underfill 8 stably fixes the bump electrode 2b, suppresses the stress even if stress is generated in the bump electrode when the temperature is increased by use, and allows the bump electrode 2b to be separated from the circuit pattern 12. Is preventing. Further, the exposed portion of the circuit pattern 12 is covered to protect the bump electrode 2b and the circuit pattern 12 from the influence of moisture and other environments.
[0018]
Further, in the portion of the FPC 1 facing the back surface of the solid-state imaging device 2, the coverlay 13 is removed to connect the peripheral circuit device 6, and the connection portion of the circuit pattern 12 to which the bump electrode 6 b of the peripheral circuit device 6 connects is formed. It is exposed. A sheet-shaped anisotropic conductive film (hereinafter, referred to as ACF) 9 is disposed on the exposed portion of the circuit pattern 12 and the base 11 exposed inside the circuit pattern 12. The peripheral circuit element 6 is connected to the ACF 9 by heating and pressurizing via the bump electrode 6b. Thereby, the interface sealing of the connection portion and the electrical connection by the bump electrode 6b can be simultaneously performed. Next, a protective material 14 is applied around the peripheral circuit element 6. As the protective material 14, a synthetic resin such as an epoxy resin can be used, and it is particularly preferable to use the protective material 14 having a linear expansion coefficient of 5 to 50 ppm / ° C. The protective member 14 is provided so as to extend from the exposed portion of the circuit pattern 12 to the peripheral circuit element 6.
[0019]
At the time of assembling the solid-state imaging device of the present invention, after connecting the solid-state imaging device 2 and the peripheral circuit device 6 to a predetermined position of the FPC 1, the FPC 1 is bent, and the internal space of the FPC 1 bent as described above is bent. The adhesive 7 is injected into the portion 15 and solidified.
[0020]
As described above, since the exposed portion of the circuit pattern 12 is covered with the protective material 14 having a small coefficient of linear expansion, even if the periphery of the solid-state imaging device is heated and heated, heat is applied to the protective material 14 via the adhesive 7. Is transmitted, the thermal expansion of the protective material 14 can be reduced, no large stress is generated in the bump electrode portion, and the circuit pattern of the FPC 1 to which the bump electrode 6b is connected does not break.
[0021]
The adhesive 7, the underfill 8, and the protective material 14 are used to arrange the periphery of the portion where the solid-state imaging device 2 and the peripheral circuit device 6 are connected to the FPC 1 via the bump electrodes 2b and 6b, and the arrangement of the lens assembly 3. Since the rigidity of the entire periphery of the part is improved, even when the soft FPC 1 is used, the periphery is hardened, and the FPC 1 is bent at the position where the solid-state imaging device 2, the peripheral circuit element 6 and the lens assembly 3 are arranged. Absent. Further, since the underfill 8 and the protective material 14 cover the exposed portions of the circuit pattern 12, the adhesive 7 does not directly contact the circuit pattern 12.
[0022]
【The invention's effect】
As described above, according to the present invention, the adhesive is interposed in the gap formed by bending the flexible printed circuit board. It is possible to provide a thin solid-state imaging device without bending. Also, since the exposed portion of the circuit pattern is covered with a protective material having a smaller linear expansion coefficient than the adhesive, even if thermal expansion due to external heat occurs, the external force exerted on the circuit pattern is reduced, and Damage can be prevented.
[Brief description of the drawings]
FIG. 1 is a sectional view showing an embodiment of the present invention.
FIG. 2 is an enlarged sectional view of a main part showing another embodiment of the present invention.
FIG. 3 is a sectional view showing a conventional configuration.
FIG. 4 is a plan view of FIG. 3;
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Flexible printed board 1a Opening 12 Circuit pattern 2 Solid-state image sensor 3 Lens assembly 6 Peripheral circuit element 6b Bump electrode 7 Adhesive 14 Protective material 15 Void

Claims (8)

A solid-state imaging device and a lens assembly that holds a lens for forming a subject image on the solid-state imaging device;
The lens assembly is disposed on one side of one end of the flexible printed circuit board,
The solid-state imaging device is arranged on the other surface of one end of the flexible printed circuit board such that an opening provided at one end of the flexible printed circuit is located between the solid-state imaging device and the lens assembly. And
The flexible printed board is bent in the vicinity of the one end, forming a gap between the portion facing the one end and the one end,
A solid-state imaging device, wherein an adhesive is interposed in the gap corresponding to a position where the lens assembly is disposed. The solid-state imaging device according to claim 1, wherein the adhesive covers the entire space. 3. The solid-state imaging device according to claim 1, wherein the adhesive has a water absorption of 0.1 to 1%. In any one of claims 1 to 3, a peripheral circuit element located in the gap is provided in a portion of the flexible printed circuit board facing the one end,
Between the peripheral circuit element and the circuit pattern of the flexible printed board, a bump electrode for connecting both is provided,
The solid-state imaging device according to claim 1, wherein an exposed portion of the circuit pattern is covered with a protective material having a smaller linear expansion coefficient than the adhesive. The solid-state imaging device according to claim 4, wherein the peripheral circuit element is provided at a position facing the solid-state imaging element. The solid-state imaging device according to claim 4, wherein the protection member is a synthetic resin. 7. The solid-state imaging device according to claim 4, wherein the protection member is provided so as to extend from an exposed portion of the circuit pattern to the peripheral circuit element. The solid-state imaging device according to claim 4, wherein the protective material has a linear expansion coefficient of 5 to 50 ppm / ° C. 9.

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