JP2005045635A - Solid-state imaging apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a solid-state imaging apparatus excellent in shading at a low cost. <P>SOLUTION: When a recessed part 1a is provided on a circuit board 1 to contain an imaging element 2 in the recessed part in order to make the profile of the solid-state imaging apparatus small, since the plate of the recessed part is made thin, this causes deterioration in shading. Then shading under fills are filled in an inner circumferential face of the recessed part 1a disclosed herein to enhance the shading and to reinforce the circuit board. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a solid-state imaging device mounted on a portable electronic device such as a cellular phone.

  As mobile electronic devices typified by mobile phone devices are becoming thinner, solid-state imaging devices mounted thereon are also required to be thinner. Among the components of the solid-state imaging device, as the camera printed circuit board for fixing the optical unit including the lens and the lens holder, an insulating plate having a thickness of about 0.6 mm is used, and the imaging device is fixed to the upper surface. The light transmitted through the lens can be received by the light receiving element.

However, in order to further reduce the thickness of the solid-state imaging device, a concave portion having a shape slightly larger than the outer shape of the imaging device is provided on the upper surface of the printed circuit board, and the imaging device is placed and stored therein. . In this case, if the depth of the concave portion is 0.3 to 0.4 mm, the thickness of the bottom surface of the concave portion is as thin as 0.2 to 0.3 mm, and light is transmitted from the thin portion to block light. There has been a problem of lowering. As a countermeasure, the present applicant has previously proposed that when a circuit pattern is formed on the bottom surface side of the printed board, a light shielding pattern is also formed on the back surface side of the concave portion to ensure the light shielding property. It has also been proposed to provide a light-shielding resist on the inner surface of the recess together with the light-shielding pattern or independently. A black resist is employed as the resist having a light shielding property (Patent Document 1).
JP 2003-60948 A

  Any of the above-described light shielding means is in accordance with the object of the invention. However, the circuit pattern and the electrode may be broken if stress is generated due to deformation because the printed circuit board is thinned. This tendency is particularly remarkable when the circuit board for portable equipment is a flexible printed circuit board. Therefore, the present invention aims to improve the quality of the solid-state imaging device by further improving the light shielding property and providing a reinforcing effect.

  According to the present invention, an imaging optical device unit is fixed to the upper surface of a camera substrate to which an imaging device is connected, and a solid that can form an image on a light receiving portion of the imaging device through light transmitted through the lens of the optical device unit. The following means are adopted for the imaging apparatus. That is, after the image sensor is placed and positioned in the image sensor housing recess provided on the upper surface of the substrate, a predetermined height position is provided between the inner surface of the recess and the outer periphery of the image sensor. It is characterized in that the image pickup element is fixed to the concave portion of the substrate by filling the underfill having a light shielding property.

  By adopting the above means, the thinned portion of the circuit board is covered with a light-shielding underfill, so that sufficient light shielding is possible. In addition, since a sufficient amount of underfill is used for light shielding, the bonding force between the image sensor and the circuit board is further enhanced. In addition, since the underfill filling operation is easy, the manufacturing cost can be reduced. Furthermore, since the underfill is cured, the bending strength of the circuit board is reinforced, so that a solid-state imaging device having high durability against external forces can be provided at low cost.

  Next, as an embodiment of the present invention, a solid-state imaging device applied to a portable electronic device such as a cellular phone will be described with reference to the drawings. FIG. 1 shows the bottom surface side of the camera substrate 1. As shown in FIG. 1, a large number of connection terminal portions 11 are aligned and formed on each end surface of the camera substrate 1 having a substantially square shape. . The connection terminal portion 11 is formed with a wiring pattern on the front surface and the back surface, an end surface through hole 11a composed of a semicircular recess is formed at an end portion of the wiring pattern, and a conductive member is formed in the end surface through hole 11a. For example, a copper paste 11b is embedded, and a plating layer (not shown) such as gold or an alloy of gold and nickel is formed on the front and back wiring patterns and the surface of the copper paste 11b to form the connection terminal portion 11. (See FIG. 2). For this reason, the connection terminal portion is formed in alignment with a flat surface instead of a recess at the end surface of the camera substrate 1.

  Further, as shown in FIG. 1, holes 1 b and 1 c for fixing the optical device unit 3 are provided at the diagonal corners of the camera substrate 1. The hole 1c is formed as a long hole that is slightly longer in the direction along the diagonal line so that a slight dimensional error can be absorbed.

  FIG. 2 is a cross-sectional view showing the configuration of the solid-state imaging device according to the present invention. As shown in FIG. 2, a concave portion 1 a for accommodating the image sensor 2 is formed on the upper surface (front surface) of the camera substrate 1. The light receiving portion 2a is located at the center of the upper surface of the image pickup device 2 housed in the recess 1a, and the terminal portion (not shown) of the image pickup device 2 and the connection terminal portion 11 are connected by a circuit pattern not shown. Has been. The camera substrate 1 is fitted in the socket portion 5a of the main body circuit board 5 of the portable device. As a result, the connection terminal portion 11 of the camera substrate 1 and the connection terminal portion formed on the inner surface of the socket portion 5a come into contact with each other so that the camera substrate 1 and the main body circuit substrate 5 are connected.

  As shown in FIG. 2, the optical device unit 3 holds an optical member such as a lens 32. The lens unit 31 holds the lens 32, and the connecting piece 31 a protrudes upward from the upper surface of the lens holder 31. The concave portion 33a of the lens presser 33 is fitted and locked together, thereby pressing the lens 32 so that it cannot escape. A diaphragm portion 33 b is provided at the center of the upper surface of the lens retainer 33. A cylindrical portion 31b protrudes downward from the outer peripheral portion of the lens holder 31, and an internal thread portion 31c is formed on the inner peripheral surface of the cylindrical portion 31b. The outer peripheral shape of the lens holder 31 is slightly larger than the outer peripheral shape of the lens retainer 33.

  The holder 34 is for holding the lens holder 31, and is provided so as to project the cylindrical portion 34a upward, and a female screw portion 34b that is screwed to the female screw portion 31c is formed on the outer peripheral surface of the cylindrical portion 34a. . The distance between the lens 32 and the light receiving portion 2a can be adjusted by adjusting the screwing amount of the female screw portion 31c of the lens holder 31 and the female screw portion 34b of the holder 34, and so-called focusing is possible. It is. An infrared cut filter 35 is held inside the holder 34 so as to face the lens 32.

  The lower end surface of the cylindrical portion 34c projecting downward from the holder 34 is bonded to the upper surface of the camera substrate 1 using an adhesive 36, whereby the optical device unit 3 is coupled to the camera substrate 1 to constitute a fixed imaging device. Is done. As a positioning means between the holder 34 and the camera substrate 1, the diagonal portions of the cylindrical portion 34 c can be fitted into holes 1 b and 1 c (see FIG. 1) provided at the diagonal positions of the camera substrate 1. A positioning projection (not shown) is projected downward at the position. The holder 34 is positioned by fitting these positioning protrusions into the holes 1b and 1c, and then fixed by the adhesive 36.

  Here, the structure of the circuit board 1 will be described. A recess 1a for accommodating the image sensor 2 is formed on the front surface of the circuit board 1, but the recess 1a is slightly more than the planar shape of the image sensor 2 as shown in the perspective view of FIG. A large planar recess is formed. The four corners 1a1 of the recess 1a are formed in an arc shape so as to escape from the corners of the image sensor. Further, the depth is substantially equal to the thickness of the image sensor 2, but the peripheral portion 1a2 is formed deeper than this. Such a configuration of the recess 1a makes it easy to incorporate the image sensor 2 into the recess 1a.

  Since the lens holder 31, the lens retainer 33, and the holder 34 constituting the optical device unit 3 are all formed of dark plastic that is a so-called dark color having light shielding properties, only the light incident from the aperture 33b is an image sensor. Reach 2 If the materials used for the camera substrate 1 and the mobile device circuit substrate 5 are inorganic base materials such as metal substrates and ceramic substrates, they are low in light transmittance. As described above, light transmission that causes a problem from the side or the side does not occur, and only the light from the upper side that is incident from the diaphragm 33b reaches the image sensor 2 and high-quality imaging is obtained. However, since the inorganic base material is expensive, an organic base substrate with a low price may be used because of the cost. In such a case, the organic base substrate has light transmittance. In addition, inconvenience may occur that light from below or from the side wraps around and reaches the image sensor 2.

  In this embodiment, the camera substrate 1 is an organic base substrate, and what is usually called a glass / epoxy substrate is used. This is made of a mixed material of epoxy resin and glass fiber or glass filler, which is advantageous in terms of low price. However, as the thickness decreases, the light transmission increases, so a light shielding measure as described below is required. It is.

  As shown in FIG. 2, the portable device circuit board 5 fixed inside the portable device case is provided with a socket portion 5a into which the camera substrate 1 can be fitted. On the inner surface of the socket portion 5a, a terminal portion (not shown) that is in contact with the connection terminal portion 11 and is conductive is provided. In a state where the camera substrate 1 is fitted to the socket portion 5a and the connection terminal portion 11 and the terminal portion of the socket portion 5a are conducted, the direction of conduction is the surface direction of the camera substrate 1 and the portable device circuit board 5. is there. The present invention is not limited to the case in which the socket portion 5a is provided on the main circuit board 5 and the camera substrate 1 is fitted and connected to the main body circuit board 5, and the main body is formed by using solder or the like on the end surface of the connection terminal portion 11. It may be connected to a predetermined terminal of the circuit board.

  In this embodiment, as a measure against light shielding described above, the underfill 37 having light shielding properties is filled in the gap between the concave portion in the concave portion 1a of the circuit board 1 and the image pickup device 2 to thereby reduce the thickness of the bottom surface of the concave portion 1a. The light shielding property is high. The underfill 37 is attached to the bottom surface of the image sensor 2 and then mounted on the recess 1a so that a uniform gap is formed around it. After injecting the fill resin 37, the imaging element 2 is fixed in the recess 1a by heating and curing. Since the underfill resin 37 has a remarkably high bending elastic modulus and bending strength due to thermosetting, it has a substrate reinforcing function.

In this embodiment, a solder ball is previously attached to the bottom of the image pickup device 2 and fixed to the recess 1a of the circuit board 1, and then the underfill resin 37 is placed at the bottom of the recess 1a and at least half the height of the depth. Fill to position. The filling amount of the underfill resin 37 is an amount that covers at least the entire bottom surface of the recess 1a, and is an amount that does not exceed the upper surface (front surface) of the image sensor 2 at most. When the imaging device 2 is fixed to the recess 1a, the upper surface of the imaging device 2 and the upper surface of the circuit board 1 are adjusted in parallel. Next, the mounting of the imaging element 2 is completed by heating and curing the underfill resin 37. Since the underfill resin 37 has a good function as a solder flux agent, the solder ball forms a circuit pattern of the image pickup device 2 and a circuit pattern in the recess 1 a of the circuit board 1 when the underfill resin 37 is heated. Connect securely. A black paste epoxy resin is used as the underfill resin 37, which is injected into the recess 1a of the circuit board 1 and then heated at 250 ° C. for about 3.5 minutes to bend the elastic modulus 2300 N / mm ² and the bending strength 130 N. / Mm ² (JISK-6911) cured product is obtained. As shown in FIGS. 1 and 2, the bottom surface of the recess 1 a of the circuit board 1 is covered with the black underfill 37, so that the light shielding property of the circuit board 1 is improved.

  In this embodiment, first, a predetermined amount of underfill resin 37 is applied to the concave portion 1a of the circuit board 1, and the image pickup element 2 with a solder ball previously attached to the bottom portion is placed thereon and heated while being pressurized. As a result, the underfill resin 37 is solidified. The underfill resin 37 is the same as in Example 1, and the same bending strength can be obtained by heating at 250 ° C. for 3 minutes and a half. Since the number of steps is smaller than that in the first embodiment, the manufacturing cost can be reduced.

  The present invention can be applied not only as a camera mounted on a portable electronic device such as a mobile phone but also as an interphone device, a camera for various monitoring devices, and the like.

It is a top view of a circuit board. It is sectional drawing which shows the whole structure. It is a perspective view which shows the shape of a circuit board.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Camera substrate 1a Concave part 2 Image pick-up element 2a Light-receiving part 3 Optical equipment unit 32 Lens 37 Underfill

Claims (1)

A solid-state imaging device in which an imaging optical device unit is fixed to the upper surface of a camera substrate to which an imaging device is connected, and light transmitted through a lens of the optical device unit can be imaged on a light receiving portion of the imaging device. There,
The image sensor is placed in an image sensor storage recess provided on the upper surface of the substrate,
The solid-state imaging device, wherein the imaging element is fixed to the recess by a light-shielding underfill filled up to a predetermined height position between the inner surface of the recess and the outer periphery of the imaging element .

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