JP2001292378A - Solid-state imaging apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a solid-state imaging apparatus by which a stable connection state between a device substrate and its external wiring is secured irrespective of change of external environment. SOLUTION: In the solid-state imaging apparatus constituted by providing the device substrate 1 to be formed by providing electrode pads 12 around an imaging area 11, a flexible substrate 2 with an opening 22 to face the image pickup area 11 at a state that wiring 21 is connected with bump electrodes 13 on the electrode pads 12 via a conductive paste 4, a transparent substrate 3 to be arranged to face the side of the imaging area 11 of the device substrate 1 in a state that the inside of the opening 22 is made to be hollow and struck to the rear side of the flexible substrate 2 via an adhesive agent 5' and a sealing resin 6 filled between the element substrate 1 and the transparent 3 around the opening 22, the adhesive agent 5' between the flexible substrate 2 and the transparent substrate 3 is provided outside a pad area 14 on which the electrode pads 12 are arranged.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a solid-state imaging device, and more particularly, to a solid-state imaging device having a hollow portion on an imaging area.

[0002]

2. Description of the Related Art Generally, in a solid-state image pickup device, an on-chip lens is provided on a light receiving surface of an image pickup area so as to concentrate incident light on the light receiving surface so as to collect light efficiently. I have to. In such a solid-state imaging device, the upper portion of the imaging region has a hollow structure in order to maintain sensitivity during imaging.

[0003] As such a solid-state imaging device, conventionally,
For example, those shown in the plan view of FIG. 4A and the cross-sectional view of FIG. 4B are known. The solid-state imaging device shown in these figures includes an element substrate 1, a flexible printed substrate (hereinafter, referred to as a flexible substrate) 2, and a transparent substrate 3.

The element substrate 1 has an imaging area (for example, a CCD area sensor) 11 in which light receiving sensors are arrayed on the surface side thereof, and electrode pads 12 are arrayed around the imaging area 11. On the electrode pad 12, a protruding electrode 13 (shown only in a sectional view) such as an Au (gold) ball bump is formed.

[0005] The flexible substrate 2 is formed by wiring 21 (shown only in a sectional view) on a flexible insulating film.
And, in particular, the imaging region 11 of the element substrate 1.
Has an opening 22 corresponding to. The wiring 21 is formed, for example, by applying Ni (nickel) plating or Au plating to a Cu wiring. The flexible substrate 2 is electrically connected to one end of the wiring 21 via the conductive paste 4 such as a thermosetting Ag paste (shown only in a cross-sectional view). The opening 22 is arranged to face the imaging region 11. One end of the flexible substrate 2 extends outside the element substrate 1, and the other end of the wiring 21 serves as an external lead for connection with an external circuit substrate that performs signal processing. Also extend outward.

The transparent substrate 3 covers the imaging region 1 of the element substrate 1 so as to cover the opening 22 of the flexible substrate 2.
1 so that a hollow portion a is formed above the imaging area 11. The transparent substrate 3 is made of, for example, optical glass and has an adhesive (for example, a thermosetting epoxy resin).
5 is attached to the entire surface of the flexible substrate 2 except for the opening 22.

Further, in order to seal a hollow portion a formed between the element substrate 1 and the transparent substrate 3, the entire periphery of the opening 22 is provided between the element substrate 1 and the flexible substrate 2. The transparent resin 3 is filled with a sealing resin (for example, a thermosetting epoxy resin) 6 while covering the outer periphery of the flexible substrate 2.

In the solid-state imaging device configured as described above,
Since the inside of the hollow portion a is sealed, it is possible to prevent the occurrence of dew condensation due to the intrusion of moisture into the hollow portion a.

[0009]

However, in the solid-state imaging device having the structure described with reference to FIG. 4, the internal pressure of the hollow portion a in the closed state is increased due to a change in the external environment (for example, an increase in temperature and humidity). As it rises, the sealing resin 6 thermally expands. As a result, as indicated by arrows in the cross-sectional view, stress is applied to the element substrate 1 and the transparent substrate 3 in a direction in which they are pushed outward. (Hereinafter, referred to as peeling stress).

In particular, as shown in an enlarged cross-sectional view of a main part of FIG.
Is small, and peeling is likely to occur due to repeated application of the peeling stress. Among the,
Between the conductive paste 4 and the wiring 21, compared to the wettability of the conductive paste 4 to the bump electrode 13 such as an Au bump, the wiring 21 formed by applying Ni plating or Au plating to the surface of the copper wiring Since the wettability of all the conductive pastes 4 was poor, peeling was likely to occur when the above-mentioned peeling stress was applied.

For this reason, in a severe use environment,
There is a problem that the connection state between the electrode pad 12 of the element substrate 1 and the wiring 21 of the flexible substrate 2 becomes unstable, so that long-term reliability of the solid-state imaging device cannot be obtained.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a solid-state imaging device capable of securing a stable connection state between an electrode pad of an element substrate and a wiring on a flexible substrate for a long time regardless of an external environment.

[0013]

According to the present invention, there is provided a solid-state image pickup device comprising: an element substrate having an electrode pad provided around an image pickup area; And a transparent substrate on which a wiring is formed. An opening facing the imaging region is provided on the flexible substrate arranged so that wiring is connected to the electrode pads of the element substrate, thereby forming a hollow portion in the opening. Further, the flexible substrate and the transparent substrate are adhered by an adhesive, and a space between the element substrate and the transparent substrate around the opening is filled with a sealing resin. In particular, the adhesive between the flexible substrate and the transparent substrate is provided on the outer peripheral side of the pad area where the electrode pads are arranged.

In the solid-state imaging device having such a configuration, only the flexible substrate portion corresponding to the outer peripheral side of the pad region on the element substrate is bonded to the transparent substrate with an adhesive,
The portion of the flexible substrate corresponding to the opening side from the pad region is not bonded to the transparent substrate but is bonded only to the element substrate side. For this reason, due to a change in the external environment, the internal pressure of the hollow portion formed between the element substrate and the transparent substrate was increased, or the sealing resin was expanded and a stress was generated to push the element substrate and the transparent substrate outward. In this case, the flexible substrate is curved such that the portion of the flexible substrate corresponding to the pad region follows the element substrate. Then, due to this curvature, the peeling stress applied to the portion corresponding to the pad region is released. Therefore, no peeling stress is applied to the connection portion between the wiring on the flexible substrate and the electrode pad on the surface of the element substrate, and the connection state between the wiring and the electrode pad is ensured.

Further, in the solid-state imaging device having the above configuration,
The flexible substrate may be provided with a cut portion along the pad region from the inner peripheral side of the opening.

By providing such notches, the bendability of the flexible substrate corresponding to the pad area is improved.

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a solid-state imaging device according to the present invention will be described.
This will be described in detail with reference to the drawings. The same components as those described with reference to FIGS. 4 and 5 in the related art are denoted by the same reference numerals, and redundant description will be omitted.

(First Embodiment) FIG. 1A is a plan view of the solid-state imaging device according to the first embodiment with a part cut away, and FIG. 1B corresponds to an AA 'portion thereof. It is sectional drawing.
FIG. 2 is an enlarged sectional view of a main part in the sectional view of FIG.

The solid-state imaging device shown in FIGS. 1 and 2 has an element substrate 1 having an electrode pad 12 and a protruding electrode 13 provided around an imaging region 11, a wiring 21 and an opening, similarly to the conventional solid-state imaging device. 22 and a transparent substrate 3 provided with the transparent substrate 3, and a hollow portion a is provided on the imaging region 11. Further, the protruding electrode 13 and the wiring 2
1 are electrically and mechanically connected by a conductive paste 4, and the flexible substrate 2 and the transparent substrate 3 are bonded by an adhesive 5 '. Further, between the element substrate 1 and the transparent substrate 3 around the opening 22, that is,
A sealing resin 6 is filled on the transparent substrate 3 so as to cover the space between the element substrate 1 and the flexible substrate 2 and the outer periphery of the flexible substrate 2.

The solid-state image pickup device shown in these figures differs from the solid-state image pickup devices shown in FIGS. 4 and 5 in the arrangement of the adhesive 5 '. That is, an adhesive 5 ′ for bonding the flexible substrate 2 and the transparent substrate 3
Is provided on the outer peripheral side of the pad region 14 of the element substrate 1 where the electrode pads 12 are provided. The pad region 14 is a region in which regions in which a plurality of electrode pads are arranged are put together.

For example, as shown in the plan view of FIG. 1A, when a plurality of electrode pads 12 are arranged in a row on both sides of the image pickup area 11, both sides of the image pickup area 11 are provided in the pad areas 14 respectively. And The adhesive 5 ′ is provided continuously between the transparent substrate 3 and the flexible substrate 2 over the entire periphery of the opening a on the outer peripheral side of the pad region 14. That is, the portion of the flexible substrate 2 extending from the inner periphery of the opening a to the pad region 14 is adhered only to the element substrate 1 by the sealing resin 6 and the conductive paste 4 without being adhered to the transparent substrate 3. Will be. However, the width of each part of the adhesive 5 ′ is maintained to such an extent that the adhesive force between the transparent substrate 3 and the flexible substrate 2 is secured.

Further, the solid-state imaging device has an electrode pad 1
The space W between the adhesive 2 and the adhesive 5 ′ in plan view is designed to be maintained at about 100 μm, so that the adhesive 5 ′ does not overlap the electrode pad 12. To

According to the solid-state imaging device having such a configuration,
Only the portion of the flexible substrate 2 corresponding to the outer peripheral side of the pad area 14 where the electrode pads 12 are disposed is the adhesive 5 ′.
Thus, the pad region 14 and the portion of the flexible substrate 2 corresponding to the opening 22 side are bonded only to the element substrate 1 side. Therefore, the element substrate 1 and the transparent substrate 3 are pushed outward as indicated by arrows in the cross-sectional view due to an increase in the internal pressure of the hollow portion a and a thermal expansion of the sealing resin 6 due to a change in the external environment. When a large stress is generated, as shown in FIG.
The flexible substrate 2 is curved such that the portion of the flexible substrate 2 corresponding to the element follows the element substrate 1 side.

Therefore, in the portion corresponding to the pad region 14, the peeling stress applied to each member due to the generation of the above-mentioned stress is released by the curvature of the flexible substrate 2, so that the conductive area having a small bonding area and a weak bonding force is reduced. The peel stress can be prevented from being applied to the conductive paste 4. As a result, the wiring 21 connected via the conductive paste 4
The connection state between the flexible substrate 2 and the protruding electrode 13 is stabilized, and the connection state between the flexible substrate 2 and the element substrate 1 can be secured.

In particular, the wiring 21 formed by plating the surface of the copper wiring with Ni plating or Au plating has a lower wettability of the conductive paste 4 than the protrusion electrode 13 such as an Au bump. Peeling was likely to occur between the conductive paste 4 and the wiring 21 due to the above-mentioned peeling stress. However, since a peeling stress is prevented from being applied to the conductive paste 4, a connection state between the conductive paste 4 and the wiring 21 can be secured, and as a result, a connection state between the wiring 21 and the electrode pad 12 is stabilized. It becomes possible. As a result, it is possible to improve the long-term reliability of the solid-state imaging device regardless of the use environment.

(Second Embodiment) FIG. 3 is a partially cutaway plan view showing the configuration of a solid-state imaging device according to a second embodiment.
The difference between the solid-state imaging device shown in this figure and the solid-state imaging device of the first embodiment lies in the configuration of the flexible substrate 2 ', and the other configurations are the same.

That is, the flexible substrate 2 'of the solid-state imaging device shown in this figure has a configuration in which the flexible substrate (2) of the first embodiment is provided with the cutout portion 23.
The cutout portion 23 is provided to have a length extending from the inner peripheral side of the opening 22 to the portion where the adhesive 5 ′ is provided along the pad region 14. For this reason, the flexible substrate 2 'is provided with a total of four cut portions 23 at both ends of the two rows of pad regions 14, respectively.

The cut portion 23 may have a width or may not have a width.

In the solid-state imaging device having such a configuration, the curving property of the portion of the flexible substrate 2 'corresponding to the pad region 14 is improved by providing the cut portion 23 along the pad region 14. For this reason, compared with the solid-state imaging device of the first embodiment, the hollow part a
When the sealing resin 6 expands and a stress is generated that pushes the element substrate 1 and the transparent substrate 3 outward, the peeling stress applied to the portion corresponding to the pad region 14 is further easily released. Therefore, the connection state between the element substrate 1 and the flexible substrate 2 can be stabilized more reliably than in the first embodiment.

In the first and second embodiments described above, the case where the pad regions 14 are provided on both sides of the imaging region 11 has been described. However, the solid-state imaging device of the present invention is not limited to this.
The solid-state imaging device in which the pad region 14 is arranged over the entire circumference of the solid-state imaging device and the solid-state imaging device in which the pad region 14 is arranged on one side of the imaging region 11 are widely applicable. in this case,
The adhesive 5 ′ is provided outside these pad regions 14, and when the cut portions 23 are provided, the cut portions 23 are provided at respective portions along the respective pad regions 14.

[0031]

As described above, according to the solid-state imaging device of the present invention, in a solid-state imaging device having a hollow portion on the imaging area, the internal pressure of the hollow portion increases or the sealing resin around the hollow portion expands. When a stress is generated that pushes the element substrate and the transparent substrate outward by doing so, the flexible substrate can be curved so that the flexible substrate portion corresponding to the pad region of the element substrate follows the element substrate side. It is possible to prevent separation stress from being applied between the wiring on the flexible substrate and the electrode pad on the surface of the element substrate, and it is possible to secure a connection state between the wiring and the electrode pad. As a result, a stable connection state between the electrode pads of the element substrate and the wiring of the flexible substrate can be ensured regardless of the external environment, and it is possible to provide a solid-state imaging device with high long-term reliability even in a severe use environment. .

[Brief description of the drawings]

FIG. 1 is a plan view and a cross-sectional view illustrating a configuration of a solid-state imaging device according to a first embodiment.

FIG. 2 is an enlarged sectional view of a main part for describing a configuration of the solid-state imaging device according to the embodiment;

FIG. 3 is a plan view illustrating a configuration of a solid-state imaging device according to a second embodiment.

FIG. 4 is a plan view and a cross-sectional view for explaining a configuration of a conventional solid-state imaging device.

FIG. 5 is an enlarged sectional view of a main part for describing a conventional problem.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Element board, 2 and 2 '... Flexible board, 3 ... Support board, 5 ... Adhesive, 6 ... Sealing resin, 11 ... Imaging area, 1
2 ... electrode pad, 14 ... pad area, 21 ... wiring, 22
... opening, 23 ... cut, a ... hollow

Claims (2)

[Claims] 1. A flexible printed wiring comprising: an element substrate having an electrode pad provided around an imaging region; and an opening opposed to the imaging region in a state where a wiring on a front surface side is connected to the electrode pad. A substrate, a transparent substrate that is disposed to face the imaging area side of the element substrate in a state where the inside of the opening is hollow, and is attached to the back side of the flexible printed wiring board via an adhesive; A solid-state imaging device comprising a sealing resin filled between the element substrate and the transparent substrate around the adhesive substrate, wherein an adhesive between the flexible printed wiring board and the transparent substrate is provided on the electrode pad. A solid-state imaging device, which is provided on an outer peripheral side of a pad region in which is disposed. 2. The solid-state imaging device according to claim 1, wherein a cutout portion is provided in the flexible printed circuit board from the inner peripheral side of the opening along the pad region. apparatus.