Image pickup apparatus

This application is a continuation application of PCT/JP2015/061867 filed on Apr. 17, 2015, the entire contents of which are incorporated herein by this reference.

1. Field of the Invention

The present invention relates to an image pickup apparatus including: an image pickup device including convex electrodes on an opposing surface facing a light receiving surface; and a wiring board including edge electrodes bonded to the convex electrodes.

2. Description of the Related Art

A CSP (chip size package) type image pickup apparatus with a size in plan view substantially equivalent to a size in plan view of an image pickup device is small, and particularly, the diameter is small. Therefore, the CSP type image pickup apparatus is used in a distal end portion of an electronic endoscope.

As shown in FIG. 1 , Japanese Patent Application Laid-Open Publication No. 2000-199863 discloses an image pickup apparatus 101 including an image pickup device 130 , a pattern film 150 , a wiring board 140 , and a signal cable 160 . Electrodes 132 are disposed on a light receiving surface provided with a light receiving section 131 of the image pickup device 130 . The electrodes 132 are electrically connected to the wiring board 140 through the flexible pattern film 150 . The signal cable 160 is bonded to electrodes 146 behind the wiring board 140 provided with electronic components 145 .

As shown in FIG. 2 , the wiring board 140 is made of a T-shaped multilayer ceramic plate including a vertical substrate 140 A and a horizontal substrate 140 B orthogonal to the substrate 140 A. The pattern film 150 is bonded to the vertical substrate 140 A and electrically connected to bonding pads 141 . The horizontal substrate 140 B is adhered such that bonding pads 142 are adjacent to the bonding pads 141 . It is disclosed that bond strength of the substrate 140 A and the substrate 140 B can be improved by using a solder 143 across the bonding pads 141 and the bonding pads 142 .

An embodiment of the present invention provides an image pickup apparatus including: an image pickup device including: a light receiving section configured to receive light entering from a light receiving surface; and a plurality of convex electrodes disposed on an opposing surface that faces the light receiving surface; and a wiring board including a plurality of first edge electrodes on a first main surface and a plurality of second edge electrodes on a second main surface, wherein the wiring board is disposed in an upright state on the opposing surface of the image pickup device, the plurality of convex electrodes include first convex electrodes and second convex electrodes, the first convex electrodes are bonded to the first edge electrodes, the second convex electrodes are bonded to the second edge electrodes, and the wiring board is held between the first convex electrodes and the second convex electrodes.

FIG. 1 is a perspective view of a conventional image pickup apparatus;

FIG. 2 is a perspective view of a wiring board of the conventional image pickup apparatus;

FIG. 3 is an exploded view of an image pickup apparatus according to an embodiment;

FIG. 4 is a cross-sectional view of the image pickup apparatus according to the embodiment;

FIG. 5A is a partial cross-sectional view for describing a manufacturing method of the image pickup apparatus according to the embodiment;

FIG. 5B is a partial cross-sectional view for describing the manufacturing method of the image pickup apparatus according to the embodiment;

FIG. 5C is a partial cross-sectional view for describing the manufacturing method of the image pickup apparatus according to the embodiment;

FIG. 6 is a schematic diagram of an image pickup apparatus observed from behind according to modification 1 of the embodiment;

FIG. 7 is a schematic diagram of an image pickup apparatus observed from behind according to modification 2 of the embodiment;

FIG. 8 is a schematic diagram of an image pickup apparatus observed from behind according to modification 3 of the embodiment;

FIG. 9 is a schematic diagram of an image pickup apparatus observed from behind according to modification 4 of the embodiment;

FIG. 10 is a schematic diagram of an image pickup apparatus observed from behind according to modification 5 of the embodiment;

FIG. 11 is a schematic diagram of an image pickup apparatus observed from behind according to modification 6 of the embodiment;

FIG. 12 is a partial cross-sectional view of an image pickup apparatus according to modification 7 of the embodiment;

FIG. 13 is a partial cross-sectional view of an image pickup apparatus according to modification 8 of the embodiment; and

FIG. 14 is a cross-sectional view of an image pickup apparatus according to modification 9 of the embodiment.

Embodiment

As shown in FIGS. 3 and 4 , an image pickup apparatus 1 according to an embodiment of the present invention includes an image pickup device 30 and a wiring board 40 as basic constituent elements. Note that in the following description, drawings based on respective embodiments are schematic drawings, and a relationship between thickness and width of each part, a ratio of thickness and a relative angle of respective parts, and the like are different from the reality. The relationship or the ratio of dimensions between the drawings may be different in some parts of the drawings.

The image pickup device 30 constituted by a semiconductor made of silicon or the like includes: a light receiving section 31 configured to receive light entering from a light receiving surface 30 SA; and a plurality of convex electrodes 32 disposed on an opposing surface 30 SB facing the light receiving surface 30 SA and connected to the light receiving section 31 . Note that the surroundings of the convex electrodes 32 provided with wiring and the like (not shown) are insulated and sealed by insulating/sealing thin films (not shown) made of silicon oxide, silicon nitride, a resin, or the like. The image pickup device 30 may be front-side illumination (FSI) or may be back-side illumination (BSI).

The plurality of convex electrodes 32 include first convex electrodes 32 A ( 32 A 1 to 32 A 3 ) and second convex electrodes 32 B ( 32 B 1 to 32 B 3 ). Note that one character at the end of reference sign will be omitted in some cases to refer to each of a plurality of constituent elements with a same function. For example, each of the first convex electrodes 32 A 1 to 32 A 3 will be referred to as 32 A, and each of the convex electrodes 32 A and 32 B will be referred to as convex electrodes 32 .

In the image pickup apparatus 1 , a distance T 32 between the first convex electrode 32 A and the second convex electrode 32 B, such as a distance T 32 between the first convex electrode 32 A 1 and the second convex electrode 32 B 1 , is substantially the same as a thickness T 40 of the wiring board 40 .

Note that a cover member 20 is adhered to the light receiving surface 30 SA of the CSP-type image pickup device 30 to protect the light receiving section 31 in a manufacturing process. The cover member 20 protects the image pickup device 30 without inhibiting the light reception of the light receiving section 31 . The cover member 20 is made of a light-transmitting member such as a light-transmitting glass or resin.

An optical system 10 is further disposed on the cover member 20 . The optical system 10 includes: a lens 11 configured to condense light from an object on the light receiving section 31 ; and a frame member 12 configured to hold the lens 11 . The lens 11 condenses the light from the object and forms an image on the light receiving section 31 . Note that the lens 11 included in the optical system 10 may be a single lens or may be a combination of a plurality of lenses. In addition, the cover member 20 may have a convex upper surface and function as a lens of the optical system 10 .

The wiring board 40 is made of one of a rigid wiring board and a flexible substrate or a combination of the rigid wiring board and the flexible substrate. The wiring board 40 includes a plurality of first edge electrodes 42 A ( 42 A 1 to 42 A 3 ) on a first main surface 40 SA and a plurality of second edge electrodes 42 B ( 42 B 1 to 42 B 3 ) on a second main surface 40 SB. An electronic component 45 is mounted on the surface of the wiring board 40 . In addition, electrode pads 43 , to which a signal cable (not shown) is bonded, are disposed on a rear edge portion.

A side of the wiring board 40 comes into contact with the opposing surface 30 SB of the image pickup device 30 , and the first main surface 40 SA and the second main surface 40 SB are disposed in an upright state with respect to the opposing surface 30 SB. The first convex electrodes 32 A are bonded to the first edge electrodes 42 A, and the second convex electrodes 32 B are bonded to the second edge electrodes 42 B. The wiring board 40 is held between the first convex electrodes 32 A and the second convex electrodes 32 B. Note that a width W 40 of the wiring board 40 can be equal to or smaller than a width W 30 of the image pickup device 30 .

Technically, the thickness T 40 of the wiring board 40 is a thickness including the edge electrodes 42 A and 42 B as shown in FIG. 5A . The distance T 32 between the first convex electrode 32 A and the second convex electrode 32 B does not have to be completely the same as the thickness T 40 of the wiring board 40 , and the distance T 32 may be slightly smaller than the thickness T 40 as long as the wiring board 40 can be held. For example, 0.95×T 40 ≤T 32 ≤T 40 holds.

As shown in FIG. 5B , the wiring board 40 is held between the first convex electrode 32 A and the second convex electrode 32 B. When, for example, the convex electrodes 32 made of solder melt, the convex electrodes 32 are bonded to the edge electrodes 42 as shown in FIG. 5C .

The image pickup device is connected to the wiring board 140 through the pattern film 150 . Therefore, bonding reliability of the image pickup apparatus is not higher than bonding reliability of an image pickup apparatus in which the image pickup device and the wiring board are bonded without using another member between the image pickup device and the wiring board. In addition, the substrate is adhered to the image pickup device 130 , and a length of the image pickup apparatus is extended by a thickness of the substrate. In addition, the pattern film 150 is disposed on an upper side of the image pickup device 130 , and an external dimension of the image pickup apparatus is larger than the image pickup device.

In contrast, in the image pickup apparatus 1 , the convex electrodes 32 of the image pickup device 30 and the edge electrodes 42 of the wiring board 40 are directly bonded. Therefore, bonding reliability of the image pickup apparatus 1 is high. In addition, the wiring board 40 is disposed to be upright with respect to the opposing surface 30 SB of the image pickup device 30 . Therefore, the electrode pads 43 and the signal cable can be easily bonded in the image pickup apparatus 1 . Furthermore, the length of the image pickup apparatus 1 is shorter than the conventional image pickup device. In addition, the configuration of the wiring board 40 of the image pickup apparatus 1 is simpler than the wiring board 140 of the conventional image pickup device, and the wiring board 40 can be easily manufactured.

Particularly, when convex portions of the convex electrodes 32 are made of solder, the plurality of convex electrodes 32 and the plurality of edge electrodes 42 can be simultaneously and surely bonded just by heating the convex portions while the wiring board 40 is held.

For stable holding of the wiring board 40 , it is preferable that the height of the convex electrodes 32 be 10 μm or more, particularly, 25 μm or more, including the thickness of the electrode pads 33 . It is preferable that the height of the convex electrodes 32 be, for example, 200 μm or less from the viewpoint of manufacturing technology.

Note that for the stable holding of the wiring board 40 , it is preferable that the number of convex electrodes 32 be four or more, particularly, six or more. When the number of electrically required convex electrodes 32 is small in the specifications of the image pickup device 30 , the plurality of convex electrodes 32 may include dummy electrodes not connected to the light receiving section 31 or dummy electrodes with the same potential as other convex electrodes. In this case, it is obvious that dummy edge electrodes are also disposed on the wiring board 40 .

For example, when the image pickup device 30 is a four-terminal type, it is preferable to dispose the convex electrodes 32 A 1 and 32 B 1 as dummy electrodes to provide six convex electrodes.

Modifications

Next, image pickup apparatuses according to modifications of the embodiment will be described. The image pickup apparatuses of the modifications are similar to the image pickup apparatus 1 of the embodiment and have the same advantageous effects. Therefore, the same reference signs are provided to the constituent elements with the same functions, and the description will not be repeated.

Modification 1

As shown in FIG. 6 , in an image pickup apparatus 1 A of modification 1, the plurality of convex electrodes 32 of an image pickup device 30 A include a plurality of convex electrodes 32 AX and 32 BX in a shape different from the convex electrodes 32 A and the convex electrodes 32 B.

Like the convex electrodes 32 AX and 32 BX, the shape of the convex electrodes 32 may be an elongated shape, such as a semi-circular shape, along an end side of the wiring board 40 . That is, the plurality of convex electrodes 32 may include convex electrodes in different shapes. Note that it is obvious that a wiring board 40 A is also provided with edge electrodes in an elongated shape according to the shape of the convex electrodes 32 AX and 32 BX.

Modifications 2 to 6

In image pickup apparatuses 1 B to 1 F of modifications 2 to 6, the wiring board includes a branch section including a third main surface 40 SC and a fourth main surface 40 SD orthogonal to the first main surface 40 SA, and the cross-sectional shape is L-shaped, T-shaped, cross-shaped (X-shaped), angled-U-shaped, or U-shaped. The branch section includes third edge electrodes 42 C on the third main surface 40 SC and fourth edge electrodes 42 D on the fourth main surface 40 SD, and third convex electrodes 32 C and fourth convex electrodes 32 D are disposed on the opposing surface 30 SB of the image pickup device. The third convex electrodes 32 C are bonded to the third edge electrodes 42 C, and the fourth convex electrodes 32 D are bonded to the fourth edge electrodes 42 D. The third convex electrodes 42 C and the fourth convex electrodes 42 D hold the branch section.

For example, in the image pickup apparatus 1 B of modification 2 shown in FIG. 7 , a wiring board 40 B has a T shape including a branch section 40 T provided with the third main surface 40 SC and the fourth main surface 40 SD orthogonal to the first main surface 40 SA. The third convex electrodes 32 C are bonded to the third edge electrodes 42 C, and the fourth convex electrodes 32 D are bonded to the fourth edge electrodes 42 D. The branch section 40 T is held between the third convex electrodes 32 C and the fourth convex electrodes 32 D.

In the image pickup apparatus 1 C of modification 3 shown in FIG. 8 , a wiring board 40 C has an L shape including a branch section 40 L provided with the third main surface 40 SC and the fourth main surface 40 SD orthogonal to the first main surface 40 SA.

Note that as shown in FIG. 8 , the distance T 32 between the plurality of convex electrodes holding the wiring board may be arranged independently of the thickness T 40 of the wiring board 40 as long as the wiring board 40 is held. That is, two convex electrodes holding the wiring board may not face each other across the wiring board 40 . In addition, there may be a convex electrode without an opposing partner across the wiring board 40 as shown in FIG. 7 .

In the image pickup apparatus 1 D of modification 4 shown in FIG. 9 , a wiring board 40 D has an X shape including: a branch section 40 X 1 provided with the third main surface 40 SC and the fourth main surface 40 SD orthogonal to the first main surface 40 SA; and a branch section 40 X 2 provided with a fifth main surface 40 SE and a sixth main surface 40 SF orthogonal to the first main surface 40 SA.

In the image pickup apparatus 1 E of modification 5 shown in FIG. 10 , a wiring board 40 E has a square-U shape including: a branch section 40 V 1 provided with the third main surface 40 SC and the fourth main surface 40 SD orthogonal to the first main surface 40 SA; and a branch section 40 V 2 provided with the fifth main surface 40 SE and the sixth main surface 40 SF orthogonal to the first main surface 40 SA.

In the image pickup apparatus 1 F of modification 6 shown in FIG. 11 , a wiring board 40 F has a U shape including: a branch section 40 U 1 provided with the third main surface 40 SC and the fourth main surface 40 SD orthogonal to the first main surface 40 SA; and a branch section 40 U 2 provided with the fifth main surface 40 SE and the sixth main surface 40 SF orthogonal to the first main surface 40 SA.

In the image pickup apparatuses 1 B to 1 F of modifications 2 to 6, the image pickup device and the wiring board are more firmly bonded than in the image pickup apparatus 1 of the embodiment.

Modification 7

As shown in FIG. 12 , an image pickup apparatus 1 G of modification 7 includes a heat transfer member 50 between the opposing surface 30 SB of the image pickup device 30 and an end surface of the wiring board 40 . The heat transfer member 50 is made of a resin containing powder with a high thermal conductivity in which the thermal conductivity is 0.1 W/(mK) or more, preferably, 5 W/(mK) or more.

In the image pickup apparatus 1 G including the heat transfer member 50 between the opposing surface 30 SB and the end surface of the wiring board 40 coming into contact with each other, the heat generated by the image pickup device 30 is efficiently transferred to the wiring board 40 through the insulating/sealing thin film formed on the opposing surface 30 SB of the image pickup device 30 . Therefore, the image pickup apparatus 1 G is highly reliable.

Modification 8

As shown in FIG. 13 , in an image pickup apparatus 1 H of modification 8, a base material (core material) 40 M of a wiring board 40 H is made of a material with a high thermal conductivity in which the thermal conductivity is 10 W/(mK) or more, preferably, 20 W/(mK) or more.

For example, the base material 40 M is made of metal, such as copper (398 W/(mK)) and aluminum (236 W/(mK)), and ceramics, such as alumina (20 W/(mK)), silicon carbide (200 W/(mK)), silicon nitride (27 W/(mK)), and aluminum nitride (170 W/(mK)).

When the base material 40 M is a conductor, the wiring board 40 H is provided with edge electrodes 42 and the like through insulating layers 40 I made of polyimide or the like.

In the image pickup apparatus 1 H, the wiring board 40 efficiently transfers the heat generated by the image pickup device 30 . Therefore, the image pickup apparatus 1 H is highly reliable.

Modification 9

As shown in FIG. 14 , in an image pickup apparatus 1 I of modification 9, both edge portions of a wiring board 40 I are respectively held between the first convex electrodes 32 A and the second convex electrodes 32 B of the image pickup device 30 . The first convex electrodes 32 A and the second convex electrodes 32 B are respectively disposed on the same electrode pads 33 and have the same potential. That is, the first convex electrodes 32 A of the first main surface 40 SA and the second convex electrodes 32 B of the second main surface 40 SB holding the wiring board 40 I may be electrically connected.

A signal cable 60 is bonded to a rear section of the wiring board 40 I. In the image pickup apparatus 1 I, the flexible wiring board 40 I is bent, and both edge portions are held between the convex electrodes. Therefore, the configuration is simple.

Note that the present invention is not limited to the embodiment described above and can be appropriately modified without opposing the gist or idea of the invention read form the scope of claims and the entire description, and the illumination device system accompanied by such a modification is also included in the technical scope of the present invention.