JP7162238B2 - Solid-state imaging device - Google Patents

Description

The present disclosure relates to a compact solid-state imaging device provided in an electronic endoscope or the like.

BACKGROUND ART Conventionally, in the medical field, by inserting an elongated insertion portion into a body cavity, a medical endoscope has been used that allows observation of internal organs in a body cavity, and various therapeutic treatments using a treatment instrument inserted through a treatment instrument channel. A viewing scope is provided. In the industrial field, industrial endoscopes are provided that can observe or inspect internal flaws, corrosion, etc. of boilers, turbines, engines, chemical plants, and the like.

Such an endoscope (electronic endoscope) includes, for example, a solid-state imaging device such as a charge-coupled device (abbreviated as CCD) or a solid-state imaging device equipped with electronic components at the distal end of the insertion section. be. A solid-state imaging device receives reflected light from an object to be imaged, photoelectrically converts the light, and transmits the photoelectrically converted signal to an information processing device having a monitor device via a signal cable. The information processing device processes a signal received from the solid-state imaging device, and displays an object captured by the solid-state imaging device in color on a monitor device.

An endoscope with a built-in solid-state imaging device is inserted into, for example, a narrow and tortuous lumen, and therefore, it is desired to reduce the diameter of the insertion portion. In addition, solid-state imaging devices are desired to be compact and small in diameter in order to realize an endoscope that can turn in a small radius and have good operability.

Patent Literature 1 discloses a solid-state imaging device arranged at the distal end of an endoscope. FIG. 5 is a cross-sectional view of the solid-state imaging device described in Patent Document 1, and FIG. 6 is a plan view of the solid-state imaging device described in Patent Document 1. As shown in FIG.

In the solid-state imaging device described in Patent Document 1, a cover glass 102 is adhered onto the light-receiving surface of a solid-state image sensor 101, and leads 104 of a flexible circuit board 103 are connected to projecting electrodes 2b formed on the light-receiving surface. . In addition, in the solid-state imaging device of Patent Document 1, the peripheral portion of the cover glass 102 and the connecting portions of the leads 104 of the solid-state imaging element 101 and the flexible circuit board 103 are sealed with the second sealing resin 5 . According to the solid-state imaging device disclosed in Patent Document 1, the size of the entire structure can be reduced by minimizing the size of the sealing and fixing portion formed by the sealing resin.

Further, Japanese Patent Laid-Open No. 2002-200002 discloses a fixed image pickup device that enables the downsizing of the image pickup unit and further reduction in the diameter of the distal end portion of an electronic endoscope or the like.

FIG. 7 is a perspective view of the solid-state imaging device described in Patent Document 2. FIG. In the solid-state imaging device disclosed in Patent Document 2, bonding pads 25 provided on the outer periphery of the solid-state imaging device 18 and bonding pads 26 provided on a vertically oriented substrate 20a coupled to the back surface of the solid-state imaging device 18. are connected by a flexible circuit board 29, and a horizontally oriented board 20b is coupled to the rear surface of the board 20a. A signal cable 30 is connected to a terminal portion 27 formed at the end of the. According to the form of Patent Document 2, the substrates 20a and 20b, the electronic component 19 mounted on the substrate 20b, and the terminal portion 27 of the signal cable can be accommodated within the projected area of the solid-state imaging device 18, and the tip of the endoscope can be accommodated. It is said that it is possible to further reduce the diameter of the part.

Japanese Unexamined Patent Application Publication No. 2001-17389 JP-A-2000-199863

Endoscopes are required to have solid-state imaging devices with higher resolution and further miniaturization.

In Japanese Unexamined Patent Application Publication No. 2002-100001, the area of the sealing fixing portion 106 formed by the sealing resin 105 is widened, which hinders the miniaturization of the solid-state imaging device. For example, when the solid-state imaging device is viewed from the light-receiving surface side of the solid-state imaging device 101 , the sealing fixing portion 106 protrudes from the outer edge of the solid-state imaging device 101 . Therefore, the size of the solid-state imaging device viewed from the light-receiving surface side is determined by the size of the sealing fixing portion 106, which prevents further miniaturization.

Further, according to the method of Patent Document 2, the solid-state imaging device 18 and the circuit board 20 must be connected by the flexible circuit board 29, and the size of the solid-state imaging device viewed from the light-receiving surface side is the same as that of the solid-state imaging device. 18, which poses a problem that prevents further miniaturization.

An object of the present disclosure is to provide a further miniaturized solid-state imaging device in a solid-state imaging device with increasing resolution.

In order to solve the above problems, a solid-state imaging device having a light-receiving surface and a rewiring layer formed on a surface opposite to the light-receiving surface, a main substrate fixed to the solid-state imaging device, and the solid-state imaging device a projecting electrode for electrically connecting a connection terminal provided in a rewiring layer of an element and a connection terminal on the main substrate; a first sealing resin covering the projecting electrode; and at least one electronic component, wherein the main substrate has a base portion and a protrusion laminated on the base portion.

According to the present disclosure, it is possible to provide a more compact solid-state imaging device.

1 is a cross-sectional view schematically showing the configuration of a solid-state imaging device according to an embodiment of the present disclosure; FIG. 1 is a side view schematically showing the configuration of a solid-state imaging device according to an embodiment of the present disclosure; FIG. 1 is a plan view schematically showing the configuration of a solid-state imaging device according to an embodiment of the present disclosure; FIG. (a1) to (d2) Cross-sectional views schematically showing manufacturing steps of the solid-state imaging device according to the embodiment of the present invention. FIG. 2 is a cross-sectional view schematically showing the shape of the main substrate according to the embodiment of the present invention; 1 is a cross-sectional view schematically showing the structure of a solid-state imaging device according to an embodiment of the present invention; FIG. 2 is a cross-sectional view schematically showing the shape of the main substrate according to the embodiment of the present invention; Cross-sectional view of the solid-state imaging device described in Patent Document 1 A plan view of the solid-state imaging device described in Patent Document 1 A perspective view of the solid-state imaging device described in Patent Document 2.

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described with reference to the drawings.
(Structure of solid-state imaging device)
FIG. 1A is a cross-sectional view schematically showing the configuration of a solid-state imaging device according to an embodiment of the present disclosure.

<Solid-state image sensor 3>
As shown in FIG. 1A, the solid-state imaging device according to the embodiment of the present invention has a rectangular solid-state imaging device 3. As shown in FIG. FIG. 1B is a side view of FIG. 1A, and is a side view schematically showing the configuration of the solid-state imaging device according to the embodiment of the present disclosure.

The solid-state imaging device 3 has a light receiving surface 3a on one surface and a rewiring layer 3c on the other surface.

Wirings on both surfaces of the solid-state imaging device 3 are electrically connected to each other by through vias 3b. Here, the solid-state imaging device 3 is a device that detects light and converts it into an electric signal and an image, such as a CCD image sensor or a CMOS image sensor. The solid-state imaging device 3 is made of a base material such as Si, InGaAs, InP, and InAs, for example.

The number of pixels on the light receiving surface 3a is, for example, 1 to 4 million pixels, and the pixel size is, for example, 1 to 2 μm.

The through vias 3b are made of a metal film, metal plating, or the like, such as Cu, W, Au, or the like.

Here, the inside of the rewiring layer 3c is wired three-dimensionally, and the through vias 3b and the plurality of connection terminals 9 on the surface of the rewiring layer 3c are electrically connected. Therefore, after processing an electrical signal of one or more pixels received by the light receiving surface 3a, it can be transmitted to the connection terminal 9 through the rewiring layer 3c via the through via 3b. Here, the rewiring layer 3c is composed of a wiring layer made of a metal film such as Cu, Al or Au and an insulating layer such as epoxy, polyimide, acryl, SiN or SiO2.

The connection terminal 9 is made of a circular or polygonal metal film such as Au, Al, or Cu.

A transparent rectangular parallelepiped cover glass 1 is arranged on the light receiving surface 3 a of the solid-state image sensor 3 , and the cover glass 1 is fixed to the solid-state image sensor 3 with an adhesive 2 . Here, for the cover glass 1, a transparent material having a refractive index of 1.3 to 1.8, such as borosilicate, quartz, sapphire, or crystal, is used. The adhesive 2 is, for example, a transparent material such as acrylic, epoxy, silicone, etc., which has a transmittance of 90% or more and a refractive index of 1.3 to 1.8. Attaching a cover glass to the solid-state imaging device not only prevents dust and foreign matter from adhering directly to the light-receiving surface during the assembly process, but also prevents moisture from entering and foreign matter from adhering in the operating environment. can.

<Main board 8>
A main substrate 8 is arranged so as to face the rewiring layer 3c of the solid-state imaging device 3 . The main board 8 is a multistage board consisting of at least two stages. The main substrate 8 includes a rectangular parallelepiped projection 8a and a rectangular parallelepiped base 8b larger than the projection 8a. Both are laminates or one piece. A connection terminal 14, a connection terminal 15, and a connection terminal 16 are provided on the upper surface of the protrusion 8a, the upper surface, the side surface, and the rear surface of the base portion 8b, respectively. They are electrically connected by wiring and vias.

Here, the main board 8 is a relay board for connecting electric signal terminals output from the solid-state imaging device 3 and cables for connecting to externally connected devices (not shown) with capacitors, coils, and resistors.

The main substrate 8 is, for example, a ceramic multilayer substrate made of alumina, glass, or the like, or an organic multilayer substrate made of glass epoxy, aramid, or the like. The connection terminals on the main board 8 are made of a sintered conductive adhesive, a plating film on a sputter film, or the like.

A plurality of connection terminals 11 are provided on the upper surface of the protrusion 8a of the main substrate 8 at positions facing the connection terminals 9 of the solid-state imaging device 3. are electrically connected by Here, the projecting electrodes 10 are made of, for example, Au, Cu, solder, AuSn, conductive adhesive, nanopaste, plating, or the like.

Further, a first sealing resin 4 is provided between the solid-state imaging device 3 and the main substrate 8 and sealed so as to cover the projecting electrodes 10 . The first sealing resin 4 is a thermosetting or ultraviolet-curing one-liquid adhesive composed of a base resin, a curing agent, an inorganic filler, and the like. For example, epoxy, acrylic, and silicone resins are used.

On the other hand, a plurality of connection terminals 14 are formed on the upper surface of the base portion 8b of the main substrate 8, and the electronic components 6 are mounted on the connection terminals 14. The connection terminals 14 and the electronic components 6 are connected by a bonding material 13 are electrically connected by

The electronic parts 6 are, for example, capacitors, resistors, and coils, and parts with dimensions such as 0603, 0402, and 0201 are used. Also, the bonding material 13 is made of, for example, solder, AuSn, a conductive adhesive, or the like.

A plurality of connection terminals 15 for cables are formed on the side surface of the base portion 8b of the main substrate 8. As shown in FIG. The cable connection terminal 15 is made of, for example, Au--Ni, Au--Pd--Ni, Cu, etc., and can be electrically connected to wiring of a connection cable (not shown) via solder or a conductive adhesive. .

FIG. 1C is a plan view schematically showing the configuration of the solid-state imaging device 3 according to the embodiment of the present disclosure.

A light-receiving surface 3a formed on the solid-state imaging device 3 is provided in a rectangular shape, and a plurality of through vias 3b are arranged in the outer peripheral portion so as to surround the light-receiving surface 3a. A pitch interval of the through vias 3b is set at, for example, 10 to 100 μm. Since the adhesive 2 and the cover glass 1 provided to cover the light receiving surface 3a of the solid-state imaging device 3 are transparent materials, the light receiving surface and the electrode pads on the through vias 3b can be observed through them.

<effect>
According to the structure of the embodiment of the present invention, in a compact solid-state imaging device with high image quality, since the solid-state imaging device can be stacked in a three-dimensional direction while maintaining the external dimensions within the projected area of the solid-state imaging device, the solid-state imaging device can be miniaturized. and the outer shape of the distal end of the endoscope can be reduced.

<Manufacturing Method of Solid-State Imaging Device>
2A1 to 2D2 are cross-sectional views schematically showing manufacturing steps of the solid-state imaging device according to the embodiment of the present invention.

First, in the bump forming step shown in FIG. 2(a1), a bump electrode 10 is formed on the connection terminal 11 of the protrusion 8a of the main substrate 8 using a bump forming means such as a stud bump bonder. In the electronic component mounting process shown in FIG. 2(b1), the electronic component 6 is mounted after the bonding material 13, which is solder paste, is applied to the connection terminal 14 using a material supply means such as a dispenser or a needle transfer device. Then, they are soldered using a solder melting means such as a reflow furnace.

Although the electronic component process has been described after the bump forming process, the order is not limited to this. The bump formation process may be performed after the electronic component process.

Further, in the sealing resin application step shown in FIG. 2(c1), the projection 8a of the main substrate 8 is coated with the first sealing resin 4 using a material supplying means such as a dispenser or a needle transfer device. Here, the second sealing resin 5 may be applied in advance so as to fill the gap between the protrusion 8a of the main substrate 8 and the electronic component 6. Next, as shown in FIG. Since the bonding area is increased by the second sealing resin 5, the reliability can be improved.

Next, in the step of mounting the solid-state imaging device shown in FIG. 2(d1), the first sealing resin 4 is cured while bonding the protruding electrodes 10 and the connection terminals 9 by using heating/pressurizing means. For example, the junction temperature should be 120-180.degree. Moreover, you may apply an ultrasonic wave simultaneously with heating and pressurization. It can be joined at a low temperature and can be applied to the solid-state imaging device 3 with low heat resistance. Further, heating may be performed using a heating means such as a curing furnace or a reflow furnace. A plurality of solid-state imaging devices can be cured at once, and the production lead time can be shortened.

FIGS. 2(a2)-(d2) are side views of FIGS. 2(a1)-(d1).

<Shape, Notch, and Chamfering of Main Board 8>
FIG. 3A is a cross-sectional view schematically showing the shape of the main board 8 according to the embodiment of the invention. A first notch 8c is provided in the vicinity of at least one vertex of the projection 8a of the main substrate 8. As shown in FIG. Further, it is preferable to provide a second notch portion 8d near at least one vertex of the base portion of the main substrate 8. As shown in FIG.

FIG. 3B is a cross-sectional view schematically showing the structure of the solid-state imaging device according to the embodiment of the invention. The first first sealing resin 4 between the solid-state imaging device 3 and the protrusion 8a of the main substrate 8 spreads along the first notch 8c before spreading to the outer periphery of the rewiring layer 3c. It spreads wet. Therefore, the first notch 8 c is filled with the first sealing resin 4 . As a result, the first sealing resin 4 does not wet and spread on the side surfaces of the solid-state imaging device 3 .

On the other hand, the second sealing resin 5 between the base portion 8b and the projection portion 8a of the main substrate 8 wets and spreads within the second notch portion 8d. However, the side surface of the main board 8 is not wetted.

Here, when the application amounts of the first sealing resin 4 and the second sealing resin 5 are small and the gap between the solid-state imaging device 3 and the main substrate 8 is large, the bonding strength between the solid-state imaging device 3 and the main substrate 8 is , the influence of the bonding strength of the bump electrode 10 becomes dominant. As a result, the bonding strength between the solid-state imaging device 3 and the main substrate 8 becomes so low that it cannot withstand the vibration during transportation in the assembly process and the impact when the solid-state imaging device is dropped, resulting in failure of destruction. occurs. In particular, when the number of connection terminals 11 on the protrusion 8a of the main substrate 8 is small, for example, from several pins to several tens of pins, or when the connection terminals 11 are arranged only in the central portion of the main substrate 8, this problem may occur. The problem becomes noticeable.

For the above reasons, it is necessary that the sealing resin does not protrude from the outer shape of the solid-state imaging device 3 and sufficiently fills the gap with the sealing resin.

<Shape>
Here, the shapes of the first notch portion 8c and the second notch portion 8d in FIGS. 3A and 3B will be described. The notch shape is a concave shape and has a half-dome shape. It is preferable that the width is the same in the width direction and the depth direction of FIGS. 3A and 3B, and the depth is the same from 1/2 of the width.

The end face of the chipped portion may have a smooth dome shape, and more preferably has fine unevenness or a certain surface roughness. Since the surface area increases, the surface tension of the sealing resin increases, which has the effect of suppressing wetting and spreading to the side surfaces.

Further, regarding the depth, w1 is the width of the main substrate 8, w2 is the width of the top of the head, w4 is the width of the first notch 8c, and w3 is the width of the second notch 8d. .

The width w4 of the first notch 8c is preferably 5% or more and 50% or less of the width w2 of the top of the head. If it is less than 5%, the first first sealing resin 4 wets and spreads over the entire back surface of the rewiring layer 3c, causing a problem of protruding to the side surfaces. On the other hand, if it is 50% or more, the first notch 8c can be provided only on one side of the top of the head, resulting in a fillet shape of the encapsulating resin that is non-uniform on the left and right sides.

On the other hand, as the width w4 of the first notch increases, the effect of guiding the first sealing resin 4 toward the base portion 8b increases, and the flow of the sealing resin to the side surface of the solid-state imaging device 3 can be suppressed. can. Furthermore, it is more preferable that the angle between the first notch 8c and the top of the head is 30 degrees or more and 60 degrees or less. It becomes possible to flow the first sealing resin 4 toward the base portion 8b.

On the other hand, it is desirable that the width w3 of the second notch be 2% or more and 30% or less of the width w1 of the main substrate 8. As shown in FIG. If it is less than 2%, the second sealing resin 5 protrudes from the main substrate 8, and the projected dimension from the upper surface of the cover glass exceeds the solid-state imaging device 3, which causes a problem that downsizing cannot be achieved. If it is more than 30%, the mounting area cannot be ensured, and furthermore, there arises a problem that the sealing resin flows out to the end surface of the main board 8 .

<effect>
By forming the first cutout portion 8c and the second cutout portion 8d as described above in at least one corner, it is possible to prevent spreading of the sealing resin and wetting of the end face. As a result, the expansion of the first sealing resins 4 and 5 can be suppressed within the range of the projected area of the solid-state imaging device 3, and miniaturization can be achieved.

Furthermore, by providing the first notch portion 8c and the second notch portion 8d at the four corners, the spreading shape can be made uniform, and there is also an effect of alleviating the stress distribution after bonding. In addition to the first cutout 8c and the second cutout 8d, a plurality of cutouts may be provided in the intermediate portion of the side, or the entire side may be provided with cutouts.

<Method of forming notch>
Next, a method for forming the first notch 8c and the second notch 8d will be described.

After the main substrate 8 made of ceramic is sintered and singulated, it is placed in a chemical-resistant mesh all at once, and vibration is applied for a predetermined period of time. When the adjacent main substrates 8 collide with each other, stress is concentrated on the corners and impact exceeding the breaking strength is applied.

As a result, the corners are dropped to form the first notch 8c and the second notch 8d. After that, the net is placed in a plating bath and electroless plating is applied to form a connection terminal with plating. Note that the notch portion may be formed by applying vibration when the plating bath is introduced or during cleaning. Production time can be shortened.

According to the above embodiment, a ceramic substrate having a size of 0.90 to 0.98 mm×0.90 to 0.98 mm and a height of 0.85 to 0.95 mm was formed, and as a result of forming the notch, the first notch The width of the cutout portion 8c and the second cutout portion 8d was formed to be 0.05 to 0.20 mm.

Two 0603 are mounted as the electronic parts 6, and the first sealing resin 4 and the second sealing resin 5 are applied to the top of the main substrate 8, and the solid-state imaging device 3 of 1.0 mm x 1.0 mm x 0.4 mm is mounted. is mounted with a mounting accuracy of ±5 μm by thermocompression, the first sealing resin 4 and the second sealing resin 5 can be sealed without protruding from the main substrate 8 and without voids. can be suppressed within 1.0×1.0 mm, which is equivalent to the size of the solid-state imaging device 3 .

Although the net in the above embodiment has been described as being able to accommodate a plurality of main substrates 8, it is not limited to this. A partition may be provided inside the net so that each main substrate 8 can be accommodated, and a protrusion or a grinding blade may be provided inside the partition. According to this method, the shape of the notch can be further stabilized.

Alternatively, after fixing the individual main substrates 8 without using a net, the notches may be formed by using a machining means such as grinding or a router. Even if the material of the main substrate 8 is an organic substrate such as glass epoxy having high breaking strength, the notch portion can be formed.

<Tilted Main Board 8>
FIG. 4 is a cross-sectional view schematically showing the shape of the main board 8 according to the embodiment of the invention. This embodiment differs from the above embodiment in that the side surface of the main board 8 is inclined.

Let θ1 be the angle formed by the top surface of the top of the main substrate 8 and the side surface thereof, and θ2 be the angle formed by the top surface of the base portion 8b of the main substrate 8 and the side surface thereof.

Here, θ1 and θ2 are preferably less than 90°. If the angle is less than 90°, it is possible to prevent the first sealing resin 4 in a liquid state from spreading to the outer peripheral portion and then flowing out to the side surface.

On the other hand, if the angle is 90° or more, the side surfaces are wetted and spread, which not only increases the outer shape, but also causes a problem of hindering the solder joint of the connecting terminal 15 for the cable.

Furthermore, by setting θ2 to be less than 90°, when a cable is connected to the cable connection terminal 15, even if the solder fillet amount is increased, it becomes easy to keep it within the projected area of the solid-state imaging device 3. It also has the effect of achieving both miniaturization and reliability of the cable connection terminal.

The solid-state imaging device of the present disclosure can be widely used as a compact solid-state imaging device. For example, it can be used for a solid-state imaging device for an endoscope.

1 cover glass 2 adhesive 2b projecting electrode 3 solid-state imaging element 3a light receiving surface 3b through via 3c rewiring layer 4 first sealing resin 5 second sealing resin 6 electronic component 8 main board 8a projection 8b base 8c first Notch 8d Second notch 9 Connection terminal 10 Projection electrode 11 Connection terminal 13 Bonding material 14 Connection terminal 15 Connection terminal 16 Connection terminal 18 Solid-state imaging device 19 Electronic component 20 Circuit board 20a Board 20b Board 25 Bonding pad 26 Bonding pad 27 terminal part 29 flexible circuit board 30 signal cable 101 solid-state imaging element 102 cover glass 103 flexible circuit board 104 lead 105 sealing resin 106 sealing fixing part

Claims (6)

a solid-state imaging device comprising a light receiving surface and a rewiring layer formed on a surface opposite to the light receiving surface;
a main substrate fixed to the solid-state imaging device;
a projecting electrode electrically connecting a first connection terminal provided on a rewiring layer of the solid-state imaging device and a second connection terminal on the main substrate;
a first sealing resin covering the projecting electrode;
at least one electronic component mounted on the main board,
The main substrate has a base portion and a protrusion laminated on the base portion and having a width smaller than that of the base portion ,
In the main board, the second connection terminal is arranged on the projection, and the at least one electronic component is mounted on the base so as to be positioned between the solid-state imaging device and the base. A solid-state imaging device. 2. A solid-state imaging device according to claim 1, wherein a corner of said protrusion has a concave first notch. 3. The solid-state imaging device according to claim 2 , wherein the first sealing resin does not protrude from the first notch to the side surface of the solid-state imaging device. 4. The solid-state imaging device according to claim 1, wherein the corner of the base portion has a concave second notch portion. The electronic component is arranged on the base, and there is a second sealing resin that seals the electronic component, and the second sealing resin does not protrude from the second notch to the side surface of the solid-state imaging device. 5. The solid-state imaging device according to claim 4 . 3. The solid-state imaging device according to claim 1, wherein at least one of the angle formed by the upper surface and the side surface of the protrusion and the angle formed by the upper surface and the side surface of the base portion is less than 90 degrees.

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