JP3600147B2 - Mounting method of solid-state image sensor - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a mounting method for mounting a solid-state imaging device containing a semiconductor chip in a surface mount type package on a circuit board.
[0002]
[Prior art]
In a solid-state imaging device having a semiconductor configuration such as a CCD image sensor, an image of a subject needs to be projected on the surface of a sensor chip. Therefore, an opening is formed corresponding to the light receiving surface of the semiconductor chip. For this reason, in the case of a solid-state imaging device, a ceramic package in which an opening is easily formed is used more often than before.
[0003]
FIG. 4 is a perspective view showing a structure of a conventional solid-state imaging device using a ceramic package.
[0004]
The ceramic package 1 has a box shape having a concave portion with a predetermined depth, and the sensor chip 2 is housed in the concave portion. The sensor chip 2 has a plurality of light receiving pixels formed on a semiconductor substrate such as silicon by a known semiconductor process and a shift register for transferring information charges generated in each light receiving pixel. Attached to. The leads 3 are embedded in the ceramic package 1 in advance, the external leads are arranged along the side surface of the ceramic package 1, and the internal leads are arranged around the sensor chip 2 in the recess. Electrode pads provided as input / output terminals on the periphery of the sensor chip 2 are connected to the internal leads of the leads 3 by wire bonding. The transparent plate 4 is made of glass or acrylic resin, and is mounted on the ceramic package 1 so as to cover the recess. As a result, the sensor chip 2 is sealed, and the wiring connecting the sensor chip 2 and the leads 3 to the sensor chip 2 is protected.
[0005]
FIG. 5 is an exploded perspective view illustrating a mounting method of the solid-state imaging device.
[0006]
The solid-state imaging device 10 has a structure shown in FIG. 4, and a plurality of leads 3 are arranged on a side surface of a ceramic package 1 containing a sensor chip 2. The circuit board 5 is made of an insulating material such as a glass epoxy board, and has a wiring pattern formed on one or both sides by copper foil. A through hole 6 corresponding to the lead 3 of the solid-state imaging device 10 is formed on the circuit board 5, and the solid-state imaging device 10 is mounted at a predetermined position by passing the lead 3 through the through hole 6. A drive circuit for supplying various drive signals to the solid-state imaging device 10 and a signal processing circuit for taking in the output of the solid-state imaging device 10 and performing predetermined processing are provided on the circuit board 5. Is connected to the solid-state imaging device 10 via a wiring pattern.
[0007]
The lens unit 7 includes a mount 8 and a lens barrel 9. The mount section 8 has a concave portion on the rear surface side in which the solid-state imaging device 10 can be stored, and is mounted on the circuit board 5 so as to cover the solid-state imaging device 10. The lens barrel 9 is provided with a lens for forming a subject image on the light receiving surface of the solid-state imaging device 10, and is mounted on the surface of the mount unit 8 facing the light receiving surface of the solid-state imaging device 10. The lens unit 7 is positioned, for example, such that the side surface of the concave portion is in contact with the side surface of the ceramic package 1 of the solid-state imaging device 10.
[0008]
[Problems to be solved by the invention]
In a solid-state imaging device using a ceramic package, there is a problem that processing of ceramic is difficult and the package itself is expensive, so that the manufacturing cost required for assembling the device is increased. When such a solid-state imaging device is mounted together with a lens unit on a circuit board, a lens mount that covers the solid-state imaging device is required. It is an obstacle to miniaturization.
[0009]
Accordingly, an object of the present invention is to reduce the manufacturing cost of a solid-state imaging device and efficiently mount the solid-state imaging device on a circuit board.
[0010]
[Means for Solving the Problems]
The present invention has been made in order to solve the above-described problem, and a solid-state imaging device in which a sensor chip in which a plurality of light receiving pixels are arranged in a matrix is housed in a surface mount type package is mounted on a circuit board together with an optical lens. In the mounting method for mounting on a circuit board, an opening window that is larger than the light receiving surface of the sensor chip of the solid-state imaging device and smaller than the package is formed on the circuit board, and an optical lens is attached to one surface of the circuit board over the opening window. And mounting the solid-state imaging device on the other surface of the circuit board while closing the opening window.
[0011]
Thus, since the solid-state imaging device can be connected to the circuit board after fixing the lens mount, the positioning of the lens mount with respect to the circuit board and the positioning of the solid-state imaging device with respect to the circuit board can be performed independently. Therefore, the alignment of the solid-state imaging device and the lens mount with reference to the circuit board becomes easy. Further, since it is not necessary to mount the lens mount so as to cover the solid-state imaging device, the protrusion from the circuit board is reduced.
[0012]
BEST MODE FOR CARRYING OUT THE INVENTION
FIG. 1 is an exploded perspective view showing the structure of the solid-state imaging device of the present invention.
[0013]
The sensor chip 11 has a plurality of light receiving pixels and a shift register formed on a silicon substrate by a known semiconductor process, and has a light receiving surface 12 in which the plurality of light receiving pixels are arranged in a matrix. The bottom member 13 is made of an insulating material such as a glass epoxy substrate, and the sensor chip 11 is mounted on a central portion of one surface. Further, a plurality of leads 14 extending from a peripheral portion of the mounting position of the sensor chip 11 to a side portion are formed of a conductive material such as a copper foil. The ends of the plurality of leads 14 at the center are connected to electrode pads formed as input / output terminals on the periphery of the sensor chip 11 by wire bonding. Further, a pair of positioning holes 15 are formed inside the two opposing sides of the bottom member 13. The frame member 16 is formed of the same material and the same size as the bottom member 13, and has an opening 17 for forming a recess for receiving the sensor chip 11 in the center. Positioning holes 18 are also formed inside the two opposing sides of the frame member 16 similarly to the bottom member 13. The bottom member 13 is bonded on the frame member 16, and a concave portion is formed by the bottom member 13 and the opening 17 of the frame member 16. Further, after the bottom member 13 and the frame member 16 are bonded to each other, electrodes connected to the leads 14 are formed on their side surfaces, as shown by broken lines in FIG. Thereby, a surface mount type package is formed. The bonding of the bottom member 13 and the frame member 16 is performed before the sensor chip 11 is attached to the bottom member 13, and the formation of the positioning hole 15 of the bottom member 13 and the positioning hole 18 of the frame member 16 are performed as follows. It is performed simultaneously after the bottom member 13 and the frame member 16 are bonded. The transparent plate 19 is made of a material transparent to visible light, such as an acrylic resin, and is mounted on the surface of the frame member 16 so as to straddle two opposite sides of the opening 17 of the frame member 16. This transparent plate 19 is formed such that the length of one side is longer than the width of two opposing sides of the opening 17, and the length of the other side is the length of the other opposing side of the opening 17. It is formed shorter than the width of the side. Thus, when the transparent plate 19 is mounted so as to straddle between two opposing sides of the opening 17, a part of the opening 17 is kept open. Here, the transparent plate 19 is mounted so as to cover at least the light receiving surface 12 of the sensor chip 11. The space between the sensor chip 11 and the transparent plate 19 is filled with a transparent resin having substantially the same refractive index as that of the transparent plate 19 to protect the sensor chip 11 and the wiring.
[0014]
Here, the transparent resin filled between the sensor chip 11 and the transparent plate 19 is formed in the opening 17 of the frame member 16 immediately after the sensor chip 11 is mounted on the bottom member 13 in an actual manufacturing process. Filled to fill the recess. Then, before the transparent resin is cured, it is mounted so as to straddle between two opposing sides of the opening 17. As a result, when the amount of the transparent resin to be filled is large, the portion of the opening 17 that is not covered with the transparent plate 19 rises, so that the transparent plate 19 does not float. Conversely, if the amount of the transparent resin to be filled is small, dents occur in portions of the opening 17 which are not covered with the transparent plate 19, so that air bubbles are generated between the light receiving surface 12 of the sensor chip 11 and the transparent plate 19. Is not mixed.
[0015]
According to such a solid-state imaging device, since a surface-mount type package can be formed of an easy-to-process and inexpensive material, the manufacturing cost can be significantly reduced as compared with a case where a ceramic package is used. it can. Further, by mounting a transparent plate 19 for protecting the light receiving surface 12 of the sensor chip 11 by opening a part of the opening 17 of the frame member 16, the transparent resin filled between the sensor chip 11 and the transparent plate 19 is filled. The quantity can be easily controlled, and the working efficiency of the manufacturing process can be improved.
[0016]
By the way, in the case of a solid-state imaging device employing such a surface mount type package, it is difficult to align the position with a circuit board or an optical system. That is, in a surface mount type package, since it is impossible to connect the solid-state imaging device to the circuit board after the lens unit is mounted over the solid-state imaging device, the solid-state imaging device is previously soldered to wiring on the circuit board. After connection, the lens unit must be mounted. However, in a surface mount type package, unevenness due to soldering is generated around the package, so that the lens unit cannot be positioned with reference to the side surface of the package.
[0017]
FIG. 2 is an exploded perspective view illustrating a mounting method of a solid-state imaging device using a surface-mount type package as shown in FIG. 1, and FIG. 3 shows a case where the solid-state imaging device and a lens unit are mounted on a circuit board. FIG.
[0018]
The solid-state imaging device 20 has the structure shown in FIG. 1, and a plurality of electrodes 21 connected to the leads 14 are formed on a side surface of a package including the bottom member 13 and the frame member 16. The circuit board 22 is made of an insulating material such as a glass epoxy board, and has a wiring pattern formed of copper foil on one or both surfaces. A driving circuit for driving the solid-state imaging device 20 and a solid-state imaging device 20 are formed through these wiring patterns. A signal processing circuit or the like that takes in the output of is connected. The circuit board 22 is provided with an opening 23 corresponding to the light receiving surface of the solid-state imaging device 20, and the solid-state imaging device 20 is mounted so that the transparent plate 19 is accommodated in the opening 23. That is, the solid-state imaging device 20 is mounted with the light receiving surface facing the circuit board 22 so as to receive a subject image through the opening window 23 of the circuit board 22. In the circuit board 22, through holes 24 corresponding to the positioning holes 18 of the solid-state imaging device 20 are provided on both sides of the opening window 23. The lens unit 25 includes a mount 26 and a lens barrel 27. The mounting portion 26 has a positioning pin 28 provided on the back surface side corresponding to the through hole 24 of the circuit board 22. The positioning pin 28 is passed through the through hole 24, and is opposite to the surface on which the solid-state imaging device 20 is mounted. It is mounted so as to cover the opening window 23 on the surface. At this time, the positioning pins 28 protrude to the back side of the circuit board 22, and the positioning holes 18 of the solid-state imaging device 20 are fitted into the protruding portions. The lens barrel 27 is provided with a lens 28 for forming an image of a subject on the light receiving surface 12 of the sensor chip 11 of the solid-state imaging device 20, and is mounted on a portion of the mount 26 facing the solid-state imaging device 20.
[0019]
Since the lens unit 25 only needs to cover the opening window 23 of the circuit board 22 and does not need to house the solid-state imaging device 20, it can be formed smaller than the lens unit 7 shown in FIG. Since the solid-state imaging device 20 is exposed even after the lens unit 25 is mounted, the position of the solid-state imaging device 20 with respect to the lens unit 25 is determined, and then the solid-state imaging device 20 is soldered to the wiring pattern of the circuit board 22. Can be fixed. Therefore, the positioning of the solid-state imaging device 20 and the lens unit 25 with respect to the circuit board 22 is facilitated.
[0020]
In the above embodiment, the case where the positioning holes 15, 18 and the through-hole 24 are provided in the solid-state imaging device 20 and the circuit board 24 has been illustrated, but these holes 15, 18 and 24 are provided with the positioning pins of the lens unit 25. It may be a notch corresponding to 28.
[0021]
【The invention's effect】
ADVANTAGE OF THE INVENTION According to this invention, when mounting the solid-state imaging device which employ | adopted the surface mount type package on a circuit board, positioning of a solid-state imaging device and a lens unit with respect to a circuit board becomes easy, and simplification of an assembly process can be expected. . Further, since the lens unit itself can be made smaller, there is no large protrusion from the circuit board, which is advantageous for miniaturization.
[Brief description of the drawings]
FIG. 1 is an exploded perspective view showing a structure of a solid-state imaging device according to the present invention.
FIG. 2 is an exploded perspective view illustrating a mounting method of the solid-state imaging device of the present invention.
FIG. 3 is a cross-sectional view illustrating a method for mounting the solid-state imaging device of the present invention.
FIG. 4 is a perspective view showing the structure of a conventional solid-state imaging device.
FIG. 5
FIG. 10 is an exploded perspective view for explaining a mounting method of a conventional solid-state imaging device.
[Explanation of symbols]
1: package 2, 11: sensor chip 3, 14: lead 4, 19: transparent plate 5, 22: circuit board 6: through hole 7, 25: lens unit 8, 26: mount 9, 27: lens barrel 12 : Light receiving surface 13: bottom members 15, 18: positioning hole 16: frame member 17: opening 20: solid-state imaging device 21: electrode 23: opening window 24: through hole 28: positioning pin

Claims (2)

In a mounting method of mounting a solid-state imaging device in which a plurality of light-receiving pixels are arranged in a matrix form on a circuit board together with an optical lens and a sensor chip housed in a surface-mount type package, the sensor chip of the solid-state imaging device is mounted on the circuit board. An opening window that is larger than the light receiving surface and smaller than the package is formed, a lens mount for mounting an optical lens is mounted on one surface of the circuit board over the opening window, and the opening is closed to cover the other side of the circuit board. Mounting the solid-state imaging device on a surface of the solid-state imaging device. A pair of through-holes are formed in the vicinity of the opening window of the circuit board, and a pair of positioning pins are formed on a surface of the lens mount in contact with the circuit board corresponding to the pair of through-holes, and the solid-state imaging device is formed. Forming a pair of positioning holes in a peripheral region of the package, positioning the lens mount with respect to the circuit board by passing the positioning pins of the lens mount through the through holes of the circuit board, and determining the other surface of the circuit board. 2. The method according to claim 1, wherein the position of the solid-state image sensor with respect to the circuit board is determined by passing a positioning pin of the lens mount protruding through a positioning hole of the solid-state image sensor.

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