Optical: systems and elements – Lens – With support
Reexamination Certificate
2001-08-16
2002-11-19
Epps, Georgia (Department: 2873)
Optical: systems and elements
Lens
With support
C359S809000, C348S340000
Reexamination Certificate
active
06483652
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a method for producing an imaging device with an integral lens including an optical lens and a solid-state imaging element.
2. Description of the Related Art
FIG. 17A
is a schematic exploded perspective view showing a structure of a conventional solid-state imaging device with an integral lens.
FIG. 17B
is a cross-sectional view of the conventional solid-state imaging device with an integral lens shown in
FIG. 17A
taken along line A-A′ of FIG.
17
A. This solid-state imaging device is conventionally produced as follows. In a first step, a die bond is applied to a supporting mount
101
which is generally referred to as a package, and then a solid-state imaging element
102
is die bond-mounted on the package
101
. In a second step, leads
103
provided on the package
101
are connected to electric signal I/O terminals (not shown) of the solid-state imaging element
102
by a wire bond. In a third step, recess portions
105
provided in a cylindrical member
104
of the package
101
are engaged with projecting members
108
provided on a support member
107
for supporting a lens
106
. The support member
107
is moved toward the package
101
along an axis X and then turned about the axis X, so that the lens
106
is attached to the package
101
. In order to achieve higher airtightness, an O-ring
109
may be provided between the support member
107
and the package
101
. Such a solid-state imaging device with an integral lens is disclosed in, for example, Japanese Laid-Open publication No. 10-301009.
A solid-state imaging device receives light which has passed through an optical lens at a light receiving surface of a solid-state imaging element and outputs an image obtained at the light receiving surface as an electric signal. In order to obtain a satisfactory image, an optical axis of the light incident on the light receiving surface should not deviate from a vertical axis of the light receiving surface.
Referring to
FIGS. 18A
to
18
E, a problem of a conventional method for producing a solid-state imaging device will be described below.
In the above-described conventional art, in order to mount the solid-state imaging element
102
on the package
101
, the solid-state imaging element
102
is required to be bonded to the package
101
as shown in FIG.
18
A. The parallelism of the package
101
and the solid-state imaging element
102
depends on: (i) the parallelism of a surface which is in contact with a die bonding stage (not shown), i.e., a bottom surface of the package
101
(shown as face C in FIG.
18
B), and a bonding tool (not shown); and (ii) a quantity and position of a die bond
110
which is applied to a bonding surface (shown as face B in
FIG. 18B
) of the package
101
. Therefore, in practice, there is great difficulty in placing a light receiving surface
111
(shown as face A in
FIG. 18B
) of the solid-state imaging element
102
in parallel with the bonding surface (face B) and the bottom surface (face C) of the package
101
with high precision.
There is a slight deviation from a vertical axis of the light receiving surface
111
due to tolerance included in each of the angles formed by: an internal surface (shown as face D in
FIG. 18C
) of the cylindrical member
104
of the package
101
in which a lens is attached and the bonding surface (face B shown in
FIG. 18C
) of solid-state imaging element
102
; and a side surface (shown as face E in
FIG. 18D
) of the support member
107
and a center of the lens
112
(in a height direction).
When all these members are combined together, there arises a problem that an angle formed (denoted as F in
FIG. 18E
) by an optical axis
113
of the light passing through the lens
106
and the light receiving surface
111
of the solid-state imaging element
102
is deviated from the right angle.
SUMMARY OF THE INVENTION
According to the present invention, there is provided a method for producing a solid-state imaging device which includes: a first step of mounting a solid-state imaging element on a transparent substrate having a first surface and a second surface opposite to the first surface such that a light receiving surface of the solid-state imaging element is substantially parallel to the first surface and faces the second surface; and a second step of forming a lens holder on the first surface, the lens holder having a lens mounting surface substantially parallel to the first surface.
According to the above method of the present invention, a light receiving-surface of the solid-state imaging element is formed on the second surface of the transparent substrate having the first surface (light receiving surface) and the second surface. The lens is mounted and fixed on the lens mounting surface of the lens holder which is formed on the first surface (light receiving surface) of the transparent substrate. As a result, an angle of an optical axis of light incident on the first surface (light receiving surface) can be prevented from being deviated from an right angle.
In one embodiment of the present invention, the first step is performed by an ultrasonic wave connection technique.
According to the above method of the present invention, high throughput can be achieved even when a low temperature connection is used.
In one embodiment of the invention, the second step is performed by injecting resin into a mold.
According to the above method of the present invention, the lens holder is directly formed on the transparent substrate, thereby providing a smaller solid-state imaging device.
In one embodiment of the invention, the lens holder is formed integrally with a package.
According to the above method of the present invention, the lens holder and the package can be integrally formed, thereby producing a solid-state imaging device with an integral lens at low cost by using a small number of parts.
In one embodiment of the invention, the first surface of the transparent substrate is adsorbed airtight to the mold by vacuum suction.
According to the above method of the present invention, the transparent substrate can be fixed. A degree of vacuum can be measured before injecting the resin. Thus, a degree of inclination of the light receiving surface of the transparent substrate can be determined based on the degree of vacuum, thereby preventing defective molding of the solid-state imaging device. Moreover, there is a vacuum hole for vacuum suction formed in the lower mold, and a cavity is formed in the lens holder so that light passes therethrough.
In one embodiment of the invention, an O-ring is placed in the mold so as to be in contact with the mold and the first surface of the transparent substrate before injecting the resin into the mold.
According to the above method of the present invention, in the case where the vacuum hole is formed in the lower mold, even when the contact area between the transparent substrate and the lower mold is not sufficiently large, higher airtightness between the lower mold and the transparent substrate can be achieved to prevent resin flow.
In one embodiment of the invention, the method for producing a solid-state imaging device further includes the step of covering the solid-state imaging element with a resin between the first step and the second step.
According to the above method of the present invention, the airtightness between the solid-state imaging element and the transparent substrate can be secured for resin molding performed later.
In one embodiment of the invention, the method for producing a solid-state imaging device further includes the step of attaching leads for input and output of an electric signal to the transparent substrate between the first step and the second step.
In one embodiment of the invention, the method for producing a solid-state imaging device further includes the step of attaching leads for input and output of an electric signal to the transparent substrate after the step of covering the solid-state imaging element with the resin but before the s
Edwards & Angell LLP
Epps Georgia
Seyrafi Saeed
Sharp Kabushiki Kaisha
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