JP2004260082A - Mounting structure of imaging device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a mounting structure of an imaging device, which can provide a shield effect to a bare chip mounting part by making the circumference of a signal land the ground level when mounting and can prevent interference with other signals. <P>SOLUTION: A conductive sheet film 14 with a conductive particle 15 is held and thermally compressed in a bare chip mounting part between an image sensing element 1 with a gold bump fixed on a land 4 and a GND land 5 and a multilayer substrate 13. The conductive sheet film 14 melts and the conductive particle 15 attaches between a gold bump 16 and lands 11, 12, thus realizing energization between the lands 11, 4 and between GND lands 12, 5. When the GND lands 12 and 5 are connected, the lands 4, 11 are airtightly shielded three-dimensionally by a solid GND land layer 20 and thereby interference of other signals from the outside and superposition of noises are prevented. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a mounting structure of an imaging device, and more particularly, to a structure in which a semiconductor bare chip substrate such as a CCD imaging device is mounted on a circuit board.
[0002]
[Prior art]
FIG. 9 is a cross-sectional view for explaining a mounting example of a conventional imaging device (Patent Document 1).
In this imaging apparatus, a lens section is mounted after the imaging element 32 is mounted on a ceramic substrate 36 as a bare chip.
A bump 34 is mounted on a gold-plated portion 32a, which is a land of the imaging device 32 having a light-receiving portion 33, and is thermocompression-bonded to a land arranged on the back surface of a ceramic substrate 36 to be bare-chip mounted. ing. Thereafter, the IR cut filter 38 is placed in the groove 41 of the ceramic substrate 36, and the lens holder 30 is mounted on the upper surface thereof. The lens 39 is mounted by screwing a screw 39a of the lens barrel 39 holding the lens 31 to a screw 30a of the lens holder 30 and fixing the screw.
[0003]
FIG. 10 is a diagram illustrating an example of a land arrangement of the imaging device in FIG. 9.
On the image sensor 32, a storage unit 43 is provided in addition to the light receiving unit 42, and lands such as a signal line and a power supply line are arranged on both sides of the storage unit 43.
Each land is a terminal as shown in FIG. 5, and in addition to the P-well and N-substrate connection terminals, terminals (six) for supplying a clock to the imaging unit and the storage unit, terminals (two) for supplying a horizontal clock, It has a power line terminal, a reset gate terminal, a reset drain terminal, and a terminal for taking out a CCD output.
[Patent Document 1]
Japanese Patent Application No. 2002-188942.
[0004]
[Problems to be solved by the invention]
Now, in such a bare chip mounting structure, the signal level taken out of the CCD output among the signal lines of the image sensor is very small, so that it is easily affected by noise and other signal lines.
Therefore, by mounting a bare chip between the ceramic substrate 36 and the image sensor 32 and minimizing the length of wiring to reduce the exposed portion and reduce the inductance component, noise is superimposed on a weak signal, And avoids interference from other signals as much as possible.
However, in practice, as shown in FIG. 8A, noises 21a and 21b are superimposed on a weak video signal or the like, and the S / N ratio cannot be increased.
[0005]
That is, the bare chip mounting of the ceramic substrate 36 and the image sensor 32 improves the S / N ratio but is not sufficient, and further measures are required.
The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a shielding effect on a bare chip mounting portion by setting the periphery of a signal land to a ground level at the time of mounting, thereby preventing interference from other signal lines. It is an object of the present invention to provide a mounting structure of an imaging device capable of performing the above.
[0006]
[Means for Solving the Problems]
In order to achieve the above object, the present invention provides an image pickup apparatus that flip-chip mounts a semiconductor element bare chip substrate such as a CCD on which lands such as signal lines and power supply lines are arranged on a mother board. Around a land such as a signal line or a power supply line, a GND land surrounding the land, and a land such as a signal line or a power supply line disposed on the mother substrate at a position corresponding to the land of the semiconductor element bare chip substrate. , A conductive land film surrounding the land, a conductive sheet film having conductive particles, the conductive particles being attached between the lands when pressed and heated to conduct, the substrate serving as the mother, and the semiconductor element A bare GND substrate and a three-dimensional GND land layer formed by flip-chip mounting the conductive sheet film; Lands such as power lines and power lines are sealed and electrically shielded by a solid GND land layer.
According to the present invention, each of the GND lands surrounding the lands such as the signal line and the power supply line is formed by an integral conductor pattern. Further, the present invention is characterized in that, in the first aspect of the present invention, the mother substrate is a multilayer substrate or a flexible substrate.
[0007]
[Action]
According to the above configuration, since the flip chip mounting portion of each land of the semiconductor element bare chip substrate is surrounded by the three-dimensional GND land layer, the level of a weak signal transmitted and received between the semiconductor element bare chip substrate and the mother substrate is stable. And the S / N ratio is improved.
[0008]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
FIG. 1 is a plan view showing an embodiment of an imaging device according to the present invention.
The image pickup device 1 has a light receiving portion 2 and a storage portion 3 formed on an image pickup device bare chip substrate 6, and gold-plated lands 4 a to 4 n such as signal lines and power supply lines are provided near both ends of the substrate 6. Seven gold-plated lands 4a to 4g are arranged on the left end, and seven gold-plated lands 4h to 4n are arranged in one line on the right end. The quadrangular loop-shaped GND lands 5a to 5n are formed so as to surround the gold plated lands 4a to 4n.
[0009]
FIG. 2 is a plan view showing another embodiment of the imaging device according to the present invention.
In this example, the GND lands 7 surrounding the gold-plated lands 4a to 4n are patterned and integrated.
As compared with FIG. 1, the shielding effect is larger than that of each of the gold-plated lands 4a to 4n. Each of the gold-plated lands 4a to 4n in FIGS. 1 and 2 is electrically connected to the light-receiving unit 2 and the storage unit 3 in the inner layer of the image sensor bare chip substrate 6.
[0010]
FIG. 3 is a bottom view showing the land arrangement on the back surface of the multilayer substrate.
The multilayer substrate 13 on which the image pickup element bare chip substrate 6 is mounted as a bare chip has a through-hole 13 for taking incident light into the light receiving section 2, and gold-plated at a position corresponding to each of the gold-plated lands 4 a to 4 n of the image pickup element bare chip substrate 6. Lands 11h to 11g are arranged. The quadrangular loop-shaped GND lands 12a to 12n are formed so as to surround the gold plating lands 11h to 11g. The gold-plated lands 11a to 11n are electrically connected to other circuit portions in the inner layer of the multilayer board. The GND lands 12a to 12n are electrically connected to each other in another layer of the multilayer substrate.
[0011]
FIG. 4 is a diagram illustrating an example of the arrangement of signal line terminals of the image sensor, and FIG. 5 is a diagram illustrating each terminal of the image sensor.
The imaging unit clocks P12, P13, and P14 are input to the imaging unit 17 serving as the light receiving unit 2. Further, a VPW terminal is connected to the P well of the imaging element bare chip substrate 6, and an NSUB terminal is connected to the substrate.
The storage unit clocks PS1, PS2, and PS3 are input to the storage unit 18.
Horizontal part clocks PH1 and PH2 are input to the horizontal shift registers arranged side by side in the accumulation unit 18, and the output of the horizontal shift register is connected to the output unit 19.
The output unit 19 is connected to a reset gate PR, a reset drain VRD, and a power supply voltage VDD, and outputs a CCD output VOUT.
[0012]
The gold-plated lands 4a to 4n include imaging unit clocks P12, P13, P13, reset gate PR, reset drain VRD, CCD output VOUT, substrate NSUB, storage unit clocks PS1, PS2, PS3, horizontal unit clocks PH1, PH2, and power supply voltage. VDD.
[0013]
FIG. 6 is a diagram for explaining a mounting process of the multilayer substrate and the imaging element substrate.
The conductive sheet film 14 having the conductive particles 15 is sandwiched between bare wrap mounting portions between the image pickup device 1 having the gold bumps mounted on the lands 4 and the GND lands 5 and the multilayer substrate 13, and thermocompression-bonded. Is melted and the conductive particles 15 adhere between the gold bumps 16 and the lands 11 and 12, and current flows between the lands 11 and 4 and between the GND lands 12 and 5.
When the GND lands 12 and 5 are connected by flip-chip mounting in this manner, the lands 4 and 11 are three-dimensionally sealed and shielded by the GND lands 12 and 5, so that other signals from the outside can be obtained. Interference and superimposition of noise can be prevented.
[0014]
FIG. 7 is a flowchart showing a mounting process of the imaging device according to the present invention.
By flip chip mounting using an ACF (Anisotropic Conductive Film, anisotropic conductive film) method, a portion where the load is applied is selectively brought into a conductive state by sandwiching the film and applying heat and a load. As shown in FIG. 6, the film of the land portion is melted by heat, conduction between the land and the gold bump is made by the melted conductive particles 15, and the other portions are maintained in an insulated state. This is effective for flip-chip mounting when the pitch between lands is very narrow (fine pitch: 40 to 60 microns).
[0015]
First, gold bumps are formed on signal lands and GND lands on the image sensor bare chip substrate (steps (hereinafter referred to as “S”) 001 and S002). Next, a multi-layer substrate is prepared, an ACF is attached thereto, and provisionally press-bonded (S003, S004, S005).
An image sensor bare chip substrate provided with gold bumps is mounted on a multilayer substrate on which AFC has been temporarily press-bonded, and flip chip bonding is performed by applying heat and a load (S006). Thereafter, it is checked whether the lands and the GND lands are normally electrically connected (S007), and the mounting of the image sensor on the multilayer substrate is completed.
[0016]
FIG. 8 is a diagram illustrating a comparative example of signals of the imaging device.
This signal is extracted from the CCD output 4g, is a weak signal, and is easily affected by interference of other signals and noise.
FIG. 8A shows a case of a normal flip-chip mounting structure, in which a video signal 21 of a CCD output 4g includes noises 21a and 21b.
However, with the flip mounting structure according to the present invention, noise can be prevented as shown in FIG.
In the above embodiment, an example is described in which a multilayer substrate is used as a mother substrate. However, a similar effect can be obtained by using a flexible substrate.
[0017]
【The invention's effect】
As described above, according to the present invention, the GND lands are provided so as to surround the lands on the image sensor side and the corresponding lands on the mother board in flip-chip mounting of the imaging apparatus, and the GND lands are electrically connected. By doing so, signals and other lands are three-dimensionally shielded, interference with adjacent lands and superposition of noise can be prevented, and a highly reliable flip-chip mounted imaging device can be obtained.
[Brief description of the drawings]
FIG. 1 is a plan view showing an embodiment of an imaging device according to the present invention.
FIG. 2 is a plan view showing another embodiment of the imaging device according to the present invention.
FIG. 3 is a bottom view showing a land arrangement on the back surface of the multilayer substrate.
FIG. 4 is a diagram illustrating an example of the arrangement of signal line terminals of an image sensor.
FIG. 5 is a diagram for explaining each terminal of the image sensor.
FIG. 6 is a diagram for explaining a mounting process of the multilayer substrate and the imaging element substrate.
FIG. 7 is a flowchart showing a mounting process of the imaging device according to the present invention.
FIG. 8 is a diagram illustrating a comparative example of signals of the imaging apparatus.
FIG. 9 is a cross-sectional view illustrating a mounting example of a conventional imaging device.
FIG. 10 is a diagram illustrating an example of a land arrangement of the image sensor of FIG. 9;
[Explanation of symbols]
1 imaging device 2, 17 light receiving unit (imaging unit)
3, 18 storage unit 4, 4a to 4n, 11, 11a to 11n land 5, 5a to 5n, 12, 12a to 12n GND land 6 imaging element bare chip substrate 7 GND pattern 13 multilayer substrate 14 conductive sheet film 15 conductive particles 16 gold Bump 17 Imaging section 19 Output section 20 Solid GND land layer 21 Analog signal

Claims (3)

In an imaging apparatus in which a semiconductor element bare chip substrate such as a CCD in which lands such as signal lines and power supply lines are arranged is flip-chip mounted on a mother substrate.
A GND land surrounding the land such as a signal line and a power supply line of the semiconductor element bare chip substrate;
A GND land surrounding the land around a land such as a signal line and a power supply line arranged at a position corresponding to a land of the semiconductor element bare chip substrate on the mother substrate;
A conductive sheet film having conductive particles, and the conductive particles adhere between the lands when pressed and heated to conduct electricity,
A three-dimensional GND land layer formed by flip-chip mounting the mother substrate and the semiconductor element bare chip substrate with the conductive sheet film;
A mounting structure for an image pickup device, wherein lands such as the signal lines and the power supply lines are hermetically sealed and electrically shielded by a solid GND land layer. 2. The mounting structure according to claim 1, wherein each of the GND lands surrounding the lands such as the signal line and the power supply line is formed by an integral conductor pattern. The mounting structure according to claim 1, wherein the mother board is a multilayer board or a flexible board.

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