JP2586296B2 - Solid-state imaging device and method of manufacturing the same - Google Patents

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 a method of manufacturing the same, and more particularly, to a solid-state imaging device having an image sensor mounted on a mold resin package and an assembling method thereof.

[0002]

2. Description of the Related Art FIG. 4 is a cross-sectional view of a conventional solid-state imaging device assembled using a package made of a molded resin. As shown in FIG.
Is formed by integrally molding a lead frame 13 and a mold resin 12 made of an epoxy resin. The method of assembling the solid-state imaging device using the resin package body 11 is as follows. The image sensor 14 is mounted on the island 13a of the lead frame 13 of the resin package body using a silver paste or the like, and the pad of the image sensor and the inner lead portion of the lead frame 13 are made of aluminum or gold using an ultrasonic method. The connection is made by a bonding wire 15. Thereafter, a thermosetting adhesive such as an epoxy resin adhesive is applied to the surface of the package body 11, and the adhesive is cured while pressing a transparent plate 17 made of glass, plastic, hard coat plastic, or the like against the package body 11. To complete the assembly.

[0003]

In the structure of the above-mentioned conventional resin package body, since a hollow portion is formed only in the upper part of the package body, there is a large difference in the amount of resin above and below the lead frame. Therefore, there is a difference between the upper and lower shrinkage of the epoxy resin after the resin molding, and the package after the molding is greatly warped. In this case, the warpage causes the image sensor to be mounted with an inclination, which has an adverse effect on characteristics.

When an image sensor is mounted on the package body and wire bonding is performed, it is necessary to heat the lead frame. However, the lower portions of the islands and the inner leads are covered with epoxy resin having low thermal conductivity. Therefore, when heating is performed at a heating temperature (about 200 ° C.) used in an ultrasonic bonding process of a normal semiconductor device, heating of the image sensor surface and inner leads is insufficient, and good alloy formation is not performed. Non-delivery will occur. To avoid this inconvenience, the temperature of the image sensor and the inner lead surface must be increased to the extent necessary for forming a good alloy, but by increasing the heating temperature to 350 ° C.
It is necessary to set the temperature to about 400 ° C. However, when heating is performed at such a high temperature, defects such as deformation and deterioration of the package body due to heat, and separation of the image sensor and the package bonding surface occur.

Further, when a transparent plate made of glass or plastic is adhered to the surface of an epoxy resin, the conventional transparent plate structure has a flat glass or plastic surface at the light receiving portion, so that a scratch or the like may occur during the assembly operation. It was easy to stick and caused the occurrence of defective products. further,
There is also a problem that positioning is difficult when bonding the transparent plate because the package surface is flat.

[0006]

According to the present invention, there is provided a solid-state imaging device according to the present invention, wherein a hollow portion (2) of a package body (1) formed by integrally molding a mold resin (2) and a lead frame (3).
The image sensor (4) is mounted on a), and the hollow portion of the package body is sealed with a transparent plate (7). The package body (1) includes a lead frame.
It is characterized in that a lightening portion (2b) for exposing the lower surface of the island portion and the inner lead portion is formed. And preferably, the package body (1)
The upper and lower portions of the resin are substantially equal in resin amount with the lead frame (3) as a boundary, and only the lightening portion (2b) is appropriately filled with another resin. Further, a stepped portion (2c) into which the transparent plate (7) is fitted can be formed in the package body (1), and the transparent plate (7) has a central light transmitting portion. (7a) can be formed in the concave portion.

[0007] The manufacturing method is a mold in which a hollow portion (2a) for accommodating an element is formed in an upper portion, and a hollow portion (2b) for exposing a lower surface of a lead frame (3) is formed in a lower portion. The hollow portion (2) of the package body (1) in which the resin (2) and the lead frame (3) are integrated.
a) a die bonding step of mounting an image sensor (4) on the lead frame; (3) a heater plate (6) being brought into contact with the lower surface of the lead frame (3) via the lightening portion (2b); A wire bonding step of connecting the lead portion and the pad of the image sensor with a thin metal wire (5); and applying an adhesive to the package body (1) or the transparent plate (7) to bring the transparent plate into close contact with the package body. And a sealing step of curing the adhesive.

[0008]

Next, embodiments of the present invention will be described with reference to the drawings. FIG. 1A is a cross-sectional view of a resin package body used in a solid-state imaging device according to one embodiment of the present invention, and FIG. 1B is a cross-sectional view for explaining an assembling process of the present embodiment. FIG. 1C is a cross-sectional view of the solid-state imaging device according to the present embodiment.

As shown in FIG. 1A, a resin package body 1 used in the present embodiment is an integrally formed body composed of a mold resin 2 which is an epoxy resin and a lead frame 3. A hollow portion 2a for accommodating the element is formed in the upper center of the mold resin 2, and a hollow portion 2a exposing the lower surface of the lead frame 3 is formed below the hollow portion 2a.
b is formed. A stepped portion 2c for fitting a cap (transparent plate) is formed at the upper end of the resin portion surrounding the hollow portion 2a. The shape of each part of the mold resin 2 is determined so that the upper and lower portions of the mold resin 2 have substantially the same amount of resin with the lead frame 3 as a boundary.

The lead frame 3 has an island 3a for mounting an element at the center thereof, and a portion of each lead near the island 3a is formed as an inner lead portion 3b to which a bonding wire is bonded. The lower surfaces of the island 3a and the inner lead portion 3b are exposed by a lightening portion 2b provided in the mold resin 2.

The resin package body 1 is formed by a transfer molding method using a molding die. The molding temperature is 180 ° C. Resin package body 1 of this embodiment
In this case, since the amount of epoxy resin in the upper portion of the lead frame 3 is equal to that in the lower portion, the package body does not warp.

When assembling, first, the image sensor 4 is mounted on the island 3a of the lead frame 3 using silver paste. Next, the heater plate 6 shaped to fit into the lightening portion 2b of the resin package body 1 is inserted into the resin package body 1, and the heater plate 6 is brought into contact with the island 3a and the inner lead portion 3b of the lead frame. In this state, a bonding wire 5 made of aluminum or gold is used to connect the pad of the image sensor 4 and the inner lead portion 3b of the lead frame 3 by an ultrasonic method.

At this time, the temperature of the heater plate 6 is maintained at 180 ° C. which is the molding temperature of the package body. The temperature of the heater plate is controlled so as not to exceed the molding temperature of the package body. Unlike the conventional resin package, in the package structure of the present invention,
Since the heater plate 6 can be brought into direct contact with the lead frame, a highly reliable connection can be formed even when the temperature of the heater plate is low. Further, since the temperature of the heater plate is low, the mold resin does not deteriorate and the image sensor does not peel off from the island.

After the bonding step is completed, an ultraviolet-curing resin is applied to the stepped portion 2c of the mold resin 2, and the adhesive is cured by irradiating ultraviolet rays with the transparent plate 7 in close contact with the resin. The solid-state imaging device according to the present embodiment shown in FIG. In the resin package body 1 of this embodiment, since the stepped portion 2c is formed in the transparent plate attachment portion, the transparent plate can be easily positioned and can be accurately positioned. FIG. 2 shows a transparent plate 7 used in this embodiment.
It is a perspective view of. As shown in FIG.
The light receiving portion 7a at the center of the surface is mirror-finished in a concave shape,
The outer peripheral portion 7b on the front and back surfaces has a satin finish. Since the transparent plate 7 has a concave light receiving portion as described above,
Opportunities for scratching during assembly work are reduced.

FIG. 3 is a sectional view of a solid-state imaging device according to another embodiment of the present invention. The difference of this embodiment from the previous embodiment is that in the present embodiment, the hollow portion 2b, which has been a space, is filled with the filling resin 8 in this embodiment. With such a configuration, the airtightness of the hollow portion 2a is enhanced, and the reliability of the device can be improved. Further, it is possible to obtain a solid-state imaging device having an outer shape similar to that of the conventional example shown in FIG. This filling resin 8
May be performed after the bonding step of the transparent plate 7, but is preferably performed after the bonding step and before the bonding step of the transparent plate.

Although the preferred embodiment has been described above,
The present invention is not limited to these embodiments, and various changes can be made within the scope of the present invention described in the claims. For example, the filling resin 8 may not be embedded in the entire lightening portion, but may be partially in the lightening portion, and the transparent plate 7 may form a concave portion on the front and back screens. Further, both die bonding (mounting) and wire bonding can be performed in a state where the heater plate 6 and the lead frame 3 are in contact with each other. A law can be adopted.

[0017]

As described above, according to the present invention, a hollow portion is provided at an upper portion of a resin package of a solid-state imaging device, and a hollow portion is provided at a lower portion to equalize the amount of epoxy resin at the upper and lower portions.
A stepped portion is provided at the upper end of the hollow portion, a concave portion is provided at the center of the transparent plate which forms a part of the package, and the periphery thereof is matte-finished. Since the lead frame and the heater plate are brought into contact with each other using the portion, the following effects can be obtained.

Since there is no difference in the amount of epoxy resin between the upper and lower portions of the lead frame, there is no difference in resin shrinkage after resin molding, so that warpage of the package can be prevented. Therefore, according to the present invention, it is possible to mount the image sensor without tilting. Even when the temperature of the heater plate is relatively low, highly reliable bonding can be performed. Therefore, the temperature of the heater plate can be reduced, and thermal stress on the resin package during bonding can be prevented. The light-receiving part of the transparent plate has a concave shape, so that the light-receiving part can be prevented from being damaged during the assembly process, and the outer periphery has a matte finish to improve the bonding strength between the package and the transparent plate. Can be. Since the transparent plate mounting portion of the package is stepped, the positioning of the transparent plate becomes easy, and the positioning accuracy can be improved.

[Brief description of the drawings]

FIG. 1 is a sectional view for explaining one embodiment of the present invention.

FIG. 2 is a perspective view of a transparent plate used in the embodiment of FIG.

FIG. 3 is a sectional view showing another embodiment of the present invention.

FIG. 4 is a sectional view of a conventional example.

[Explanation of symbols]

 1, 11 Resin package body 2, 12 Mold resin 2a Hollow portion 2b Lightening portion 2c Stepped portion 3, 13 Lead frame 3a, 13a Island 3b Inner lead portion 4, 14 Image sensor 5, 15 Bonding wire 6 Heater plate 7, 17 Transparent plate 7a Light receiving part (mirror finish) 7b Outer periphery (matte finish)

Claims (8)

(57) [Claims] 1. A solid-state imaging device in which an image sensor is mounted in a hollow portion of a package body formed by integrally molding a mold resin and a lead frame, and wherein the hollow portion of the package body is sealed with a transparent plate. The package body includes the lead frame island and
A solid-state imaging device, wherein a lightening portion exposing a lower surface of an inner lead portion is formed. 2. The solid-state imaging device according to claim 1, wherein only the lightening portion is embedded with another resin. 3. The solid-state imaging device according to claim 1, wherein the package body has substantially the same amount of resin in the upper part and the lower part with the lead frame as a boundary. 4. The solid-state imaging device according to claim 1, wherein the transparent plate has a light transmitting portion formed in a recess on at least one main surface. 5. The solid-state imaging device according to claim 1, wherein the transparent plate has satin-finished outer peripheral surfaces. 6. The solid-state imaging device according to claim 1, wherein a stepped portion is formed in the package body, and the transparent plate is attached to the stepped portion. 7. A package body in which a mold resin and a lead frame are integrated, wherein a hollow portion for accommodating an element is formed in an upper portion, and a hollow portion exposing a lower surface of the lead frame is formed in a lower portion. A die bonding step of mounting an image sensor in a hollow portion, and a heater plate is brought into contact with the lower surface of the lead frame via the lightening portion, and in that state, an inner lead portion of the lead frame and a pad of the image sensor are connected with a thin metal wire. A method for manufacturing a solid-state imaging device, comprising: a wire bonding step of connecting; and a sealing step of applying an adhesive to the package body or the transparent plate, and bringing the transparent plate into close contact with the package body to cure the adhesive. 8. A package body in which a mold resin and a lead frame are integrated, wherein a hollow portion for accommodating an element is formed in an upper portion, and a hollow portion exposing a lower surface of the lead frame is formed in a lower portion. A die bonding step of mounting an image sensor in a hollow portion, and a heater plate is brought into contact with the lower surface of the lead frame via the lightening portion, and in that state, an inner lead portion of the lead frame and a pad of the image sensor are connected with a thin metal wire. A wire bonding step of connecting; a resin filling step of filling a resin in the lightening portion of the package body; an adhesive applied to the package body or the transparent plate; And a sealing step of curing the agent.