JP2003289456A - Small-sized imaging module - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a small-sized imaging module with a structure of employing a plastic lens that can be surface-mounted by solder reflow. <P>SOLUTION: An IR cut filter 23 is fitted to an upper face of a case 22 to shut off an infrared ray from an upper part in a reflow furnace. The IR cut filter may be kept attached even after mount on a circuit board. A cylinder part 22c for containing a lens 6 is configured to be suspended from a ceiling part 22b of a case upper end into the inside the case so as to extend a thermal conduction path from the board to the lens through bypass of the board, a case side wall, the ceiling, the cylinder and the lens thereby reducing the thermal conduction. The case of a double structure in the lateral direction of the lens permits heat prevention effect. A shelf 22a in the inner circumference of the cylinder is not a continuous annular shape but divided into several parts to reduce the contact area between the lens and the case thereby decreasing the thermal conduction. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a compact image pickup module incorporated in a video camera, a surveillance camera, an industrial camera, a personal computer, a telephone or the like and used for taking an image.

[0002]

2. Description of the Related Art FIGS. 3A and 3B show an example of a small-sized image pickup module as described above. FIG. 3A is a top view and FIG.
It is a B sectional view. 4 is an exploded perspective view thereof.
As shown in these drawings, the substrate 1 made of ceramics or epoxy resin containing glass and the plastic case 2 are
It is a package that houses each component. The IC (3) is die-bonded to the substrate 1 and wire-bonded with the wires 4. The IC (3) is formed with an image pickup circuit in which a large number of detection elements each of which combines a photoelectric conversion element such as a photodiode and a MOS transistor or a CCD element are arranged in a matrix.

As is apparent from FIG. 4, the case 2 has a box-like shape on the lower side and a cylindrical shape on the upper side. As shown in FIG. 3B, the case 2 faces the IC (3) on the substrate 1. IR inside the bottom
The (infrared) cut filter 7 is fixed to prevent the electric charge from being saturated in an environment with a large amount of infrared rays, such as outdoors, and the image from becoming pure white. There is a shelf 2a on the inner wall of the upper cylindrical portion of the case 2, and the lens 6 is attached to this. The lens 6 is made of transparent plastic, and a convex lens 6b is formed on the lower surface of a disk-shaped base 6a.
The outer periphery of is placed on the shelf 2a, and the upper surface is pressed by the diaphragm 5 to support it. The aperture 5 has a hole 5a as an optical path. An adhesive such as epoxy is used to bond these parts to each other. With such a configuration, an image of the outside world is formed on the surface of the IC (3) through the lens 6, converted into an electric signal and processed.

Around the substrate 1, there are a plurality of depressions 1a,
The inner wall of the depression 1a is coated with a conductive material, and this conductive material connects the conductive patterns on the upper and lower surfaces of the substrate 1, and although not shown, the land portion of the conductive material around the depression 1a on the lower surface of the substrate 1 is formed. , Which is a terminal electrode for connection to the circuit board to be assembled. Therefore, this small-sized image pickup module is suitable for surface mounting on a circuit board of an electronic device by using the terminal electrodes on the lower surface of the board 1.

[0005]

In order to surface-mount circuit components on a circuit board of an electronic device, it is convenient to use solder reflow, but it is difficult for the above-mentioned small-sized image pickup module to do so. There are circumstances. That is, the transparent plastic lens 6 is not able to withstand the reflow temperature of 230 ° C. or higher and is deformed. FIG. 5 is a cross-sectional view of the upper end of the case 2 of the small image pickup module in which the lens 6 is housed. As shown in FIG. 3A, the base 6a of the lens 6 is placed on the shelf 2a on the inner wall of the case 2 and the diaphragm 5
Press and hold with the squeeze 5 on the top of the case 2 with adhesive 8
It is joined with. When the small-sized image pickup module is surface-mounted and is temporarily attached to a circuit board and put in a reflow furnace and heated, the lens 6 tries to thermally expand as shown by an arrow in FIG. Or, it is pressed by the diaphragm 5 to be distorted, or in extreme cases, it is melted, deformed and solidified, so that a normal image is not formed after mounting.

Therefore, when mounting a small image pickup module on a circuit board, a solder is manually attached one by one, or a package in which a case 2 is fixed to the board 1 but no lens is attached is mounted on the circuit board. It will be mounted by reflow, and the lens and diaphragm will be attached in a later process.
It takes man-hours. A heat-resistant glass lens can withstand the reflow temperature, but the glass lens is more expensive than a plastic lens and is disadvantageous in terms of cost. The present invention solves the above problems and is a structure using a plastic lens,
Provided is a small-sized image pickup module which can be surface-mounted by reflowing solder.

[0007]

In order to solve the above-mentioned problems, the present invention takes measures to prevent reflow heat from being transmitted to the lens as much as possible. As is well known, heat transfer occurs by conduction, convection, and radiation.In the reflow furnace, heat conduction from the circuit board to the mounting parts, convection of heated air in the furnace, and heat radiation from the infrared heater occur. Realize a structure to deal with these.

That is, 1. By arranging an IR cut filter above the lens in addition to the IR cut filter for adjusting the sensitivity arranged below the lens, heat radiation from above due to infrared rays in the furnace is prevented. 2. By extending the path from the board through the side wall of the case to the lens at the top of the case by detouring it, the thermal conductivity from the circuit board on which the small imaging module is mounted is reduced, and the amount of heat transferred to the lens is reduced. . 3. By reducing the contact area between the case and the lens at the lens mounting portion to the case, the thermal conductivity of this portion is reduced. The above means can be used in combination.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. Since the basic structure of the small-sized image pickup module in the embodiment is the same as that shown in FIGS. 3 and 4, corresponding parts and portions are designated by the same reference numerals, and detailed description thereof will be omitted.

FIG. 1 is a sectional view of an embodiment of the present invention, and FIG. 2 is an exploded perspective view thereof. In the compact image pickup module shown in FIGS. 3 and 4, the case 2 has a shape in which the cylindrical portion for housing the lens 6 is placed on the lower part of the box shape. However, in the embodiment of FIG. It has a rectangular box shape. Then, a cylindrical portion 22c extending from the central portion of the ceiling portion 22b of the upper end surface toward the inside of the case 22 is provided.

A shelf 22a is provided in the middle of the inner circumference of the cylindrical portion 22c, a lens 6 is placed on the shelf 22a, and the diaphragm 5 presses it. The diaphragm 5 is joined to the case 22 by an adhesive or ultrasonic welding. At the lower end of the cylindrical portion 22c, I for adjusting the incident light to the IC (3)
The R cut filter 7 is fixed. Further, in the present embodiment, the IR cut filter 23 is joined to the upper end surface of the case 22.

With this structure, the following effects are obtained. First, by covering the upper end of the case 22 with the IR cut filter 23, infrared rays from above are blocked in the reflow furnace to prevent the temperature of the case 22 from rising. On the other hand, the IR cut filter 7 inside the case 22 is originally intended to adjust the sensitivity of the imaging IC (3), but the substrate 1
Also, when there is an infrared ray that passes through the wall of the case 22 and is incident, it also has the function of blocking the heating of the lens from below. That is, the upper and lower surfaces of the lens 6 are protected from infrared rays by the IR cut filters 7 and 31. After mounting on the circuit board, the IR cut filter 23 is not necessary and may be removed. However, the IR cut filter 23 may be attached to the case 22 without removing it.

An IR cut filter 23 may be arranged between the diaphragm 5 and the lens 6 to prevent infrared rays from above, but it is better to mount the IR cut filter 23 on the upper surface of the case 22 as shown in FIG. It has a heat insulating effect and is effective.

The case 22 is box-shaped, and the ceiling portion 2 at the upper end is formed.
With the configuration in which the cylindrical portion 22c is hung from 2b, when the small-sized imaging module of the embodiment is placed on the circuit board of the installation destination and placed in the reflow furnace, the heat conduction path from the lower circuit board (not shown) is as shown in FIG. As indicated by a thick line 24 with an arrow on the side wall of the case 22, the ceiling portion 22b, the cylindrical portion 22
c, through the ledge 22a to the lens 6, which is longer than in the miniature imaging module of FIG.

When the cross-sectional shape of the case 2 is as shown in FIG. 3B, the heat conduction path from the lower circuit board (not shown) is simply from the side wall of the lower box-shaped portion of the case 2 to the upper side. When it reaches the lens 6 through the cylindrical part of FIG. 1 and this path is overlaid on FIG. 1, it becomes a path from the middle of the thick line 24 with an arrow to the broken line 25. Therefore, the solid line route 24 is longer than the route including the broken line 25 by detouring by a distance corresponding to twice the depth from the ceiling portion 22b of the case 22 to the shelf 22a. This reduces heat transfer from the lower circuit board to the lens 6. Further, in FIG. 3, when the side surface of the cylindrical portion of the case 2 accommodating the lens is heated, the heat is immediately transmitted to the lens 6,
In the embodiment of FIG. 1, the lens 6 is doubly surrounded by the cylindrical portion 22c of the case 22 and the outer wall of the case in the lateral direction, and an air layer is interposed to reduce heat conduction.

In the small image pickup module shown in FIG. 4, the outer circumference of the lens 6 is placed and supported on an annular shelf 2a provided on the inner wall of the cylindrical portion of the case 2. In the embodiment of the present invention, FIG.
As shown in FIG. 2, the shelves 2 on the inner wall of the cylindrical portion 22c of the case 22
2a is not a continuous annular shape, but is divided and provided at three locations. As a result, the contact area between the lens 6 and the shelf 22a is reduced, and the thermal conductivity from the case 22 can be reduced.

The arrangement of the IR cut filter on the upper end of the case and the division of the shelves on which the lenses are placed can be applied to the conventional small-sized image pickup module as shown in FIGS.

[0018]

In a conventional small-sized image pickup module using a plastic lens, the lens is deformed by heat during reflow, so that it cannot be mounted on a circuit board using solder reflow, while heat resistance is high. Since glass lenses with lenses are expensive, we are forced to use inefficient manufacturing methods such as soldering manually by hand or mounting the lensless package on the circuit board by reflow before mounting the lens. Was there. According to the present invention, by adopting an appropriate heat transfer suppressing means, it is possible to prevent the adverse effect on the plastic lens and efficiently surface mount the small imaging module on the circuit board by reflowing the solder.
Thus, costs are reduced and product reliability is improved.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of an embodiment of the present invention.

2 is an exploded perspective view of the embodiment of FIG. 1. FIG.

3A and 3B are drawings of a conventional small-sized image pickup module, where FIG. 3A is a top view and FIG. 3B is a sectional view taken along line BB of FIG.

FIG. 4 is an exploded perspective view of the compact imaging module of FIG.

5 is a cross-sectional view showing a state around a lens of the small-sized image pickup module in FIG. 3 before and after heating.

[Explanation of symbols]

1 substrate 1a hollow 2,22 cases 2a, 22a shelves 22b ceiling 22c cylindrical part 3 IC 5 aperture 6 lenses 7,23 IR cut filter 8 adhesive

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) G02B 7/02 G02B 7/02 H H01L 27/14 H04N 5/335 V H04N 5/335 H01L 27/14 D (72) Inventor Akito Watanabe 2 6663 Funatsu, Kawaguchiko-cho, Minamitsuru-gun, Yamanashi Prefecture F-term inside Kawaguchiko Precision Co., Ltd. (reference) 2H044 AA04 AA12 AD00 AE06 AG01 4M118 AA08 AA10 AB01 BA10 BA14 FA06 GC11 GD02 HA22 HA23 HA24 5C022 AC42 AC54 AC55 AC70 AC78 5C024 CY47 EX22 EX23 EX24 EX26 EX42 EX51 GY01 GY31

Claims (4)

[Claims] 1. A substrate, a case, an IC, a diaphragm, a lens, and an I.
In a small-sized imaging module that accommodates and packages an R cut filter, etc., and mounts it on a circuit board, an IR cut filter for sensitivity adjustment is placed below the lens, and an IR cut filter is also placed above the lens. A small-sized image pickup module characterized by blocking heat radiation. 2. An IC, a diaphragm, a lens, and an I on a substrate and a case.
A small-sized image pickup module, which is housed and packaged with an R-cut filter and mounted on a circuit board, and has a case structure in which a heat conduction path from the board to the lens is detoured and lengthened. 3. The compact image pickup module according to claim 2, wherein the case structure in which the heat conduction path from the substrate to the lens is diverted and lengthened is configured such that a cylinder for housing the lens from a ceiling portion of an upper end supported by an outer wall of the case. A small-sized imaging module, characterized in that the part is hung inside the case. 4. An IC, a diaphragm, a lens, and an I on a substrate and a case.
In a small-sized imaging module that houses an R-cut filter and the like and is mounted on a circuit board to be used, the shelf portion in the case that supports the lens is divided into three or more pieces instead of a continuous shape, and A compact imaging module characterized by reducing the contact area.