JP5467524B2 - Manufacturing method of small electronic unit, camera module, and portable terminal - Google Patents

Description

The present invention relates to a method for manufacturing a small electronic unit in which a flexible substrate is connected to a rigid substrate or a flexible substrate using ACF. The present invention also relates to a camera module including a small electronic unit manufactured by the manufacturing method and a portable terminal including the camera module .

  Conventionally, ultra-small camera modules have been installed in small and thin mobile terminals such as mobile phones and PDAs (Personal Digital Assistants), which enables not only voice communication but also image capture and communication. It has become.

  The camera module forms a subject image on an image sensor using an imaging lens. The imaging device is composed of a CCD (Charge Coupled Device) type image sensor, a CMOS (Complementary Metal-Oxide Semiconductor) type image sensor, or the like. The image sensor is mounted on a rigid board.

  A flexible substrate is connected to the rigid substrate for electrical connection with the portable terminal. For this connection, an anisotropic conductive film (hereinafter referred to as ACF) is interposed between the connection terminal of the flexible substrate and the connection terminal of the rigid substrate, and the flexible substrate is thermocompression bonded to the rigid substrate with a crimping head. To do.

  ACF is a film for electrical joining made of a heat resistant resin and having a thickness of about 20 to 35 μm. A plurality of conductive particles are dispersed inside the heat resistant resin, and the conductive particles are formed in a sphere of 5 to 10 μm in which the resin is coated with nickel or the like. When the ACF is thermocompression bonded, the conductive particles come into contact with each other, and thus have conductivity in the thickness direction. However, since no pressure is applied in the surface direction, the insulating property is maintained by the heat resistant resin. Therefore, when connecting a plurality of connection terminals provided on two printed circuit boards, the opposing connection terminals are conducted, and adjacent connection terminals are not conducted.

  The following patent documents are known as a method of thermocompression bonding a printed circuit board using such an ACF.

  For example, when a flexible substrate is thermocompression bonded to a rigid substrate of a plurality of camera modules using an ACF, an electronic device that prevents the camera module from floating when the tape temporarily bonded to the rigid substrate and attached to the ACF is removed. An assembly jig for a unit is described in a patent publication (see Patent Document 1).

  Moreover, in an electronic module in which a flexible substrate is thermocompression bonded using ACF as a rigid substrate, the portion of the electrode terminal of the flexible substrate other than the portion in contact with the conductive connection member is branched into two, thereby reducing the low resistance value of the joint portion. An electronic module that enables measurement is described in a patent publication (see Patent Document 2).

JP 2007-31314 A JP 2008-78628 A

  FIG. 7 shows a configuration in which the connection terminal of the flexible substrate is connected to the connection terminal of the rigid substrate in the camera module by the ACF.

  7A is a plan view of the rigid substrate 61 as viewed from the connection terminals 61b and 61c, and FIG. 7B is a cross-sectional view of the rigid substrate 61. FIG. A plurality of connection terminals 61b and 61c are disposed on the base 61a of the rigid substrate 61, and are disposed on the left and right as shown in FIG. A coverlay 61d is disposed between the connection terminals 61b and 61c.

  In addition, an image sensor 62 made up of a CCD type image sensor or the like is mounted at the center of the back surface side with respect to the surface on which the connection terminals 61b and 61c are arranged. Since the image pickup device 62 is mounted substantially at the center of the rigid substrate 61 and the image pickup device 62 has a large number of leads, the number of connection terminals 61b and 61c is also large. Therefore, it is difficult to arrange the connection terminals 61b and 61c only at one end of the rigid substrate 61. The connection terminals 61b are arranged at the left end and the connection terminals 61c are arranged at the right end to be dispersed.

  The left view of FIG. 7A is a plan view of the flexible substrate 63 as seen from the back side with respect to the surface on which the connection terminals 63b and 63c are arranged, and FIG. 7B shows a cross-sectional view of the flexible substrate 63. A plurality of connection terminals 63b and 63c are arranged on the base 63a of the flexible substrate 63, and are arranged on the left and right as shown in FIG. A coverlay 63d is disposed between the connection terminals 63b and 63c.

  FIG. 7B is a diagram in which the flexible substrate 63 is connected to the rigid substrate 61 by ACF. Note that FIG. 7B is partially exaggerated for clarity of explanation.

  A rigid board 61 is arranged on a predetermined pedestal 72, and the connection terminals 61b and 61c of the flexible board 63 are positioned so as to face the connection terminals 61b and 61c of the rigid board 61, and the connection terminals 61b and 61c and the connection terminal 63b are placed. , 63c, an ACF 65 is interposed. Then, the flexible substrate 63 is pressed by the pressure-bonding head 71 and is thermally bonded to the rigid substrate 61.

  At this time, the cover lay 61d is thicker than the connection terminals 61b and 61c of the rigid board 61, and the cover lay 61d protrudes from the surfaces of the connection terminals 61b and 61c. The same applies to the flexible substrate 63, and the cover lay 63d protrudes from the surfaces of the connection terminals 63b and 63c.

  Therefore, when the flexible substrate 63 is pressed toward the rigid substrate 61 by the crimping head 71, the cover lay 63d is pressed against the cover lay 61d, but the connection terminals 63b and 63c are sufficiently connected to the connection terminals 61b and 61c via the ACF 65. It cannot be pressed. Of course, the flexible substrate 63 is thin and deforms, and the connection terminals 63b and 63c come into contact with the connection terminals 61b and 61c through the ACF 65. However, the connection cannot be reliably conducted and a conduction failure tends to occur.

The present invention has been made in view of such a problem. An ACF is interposed between a connection terminal of a flexible board and a rigid board or a connection terminal of the flexible board, and the connection terminal of the flexible board is connected to the connection board of the rigid board by a crimping head. It is an object of the present invention to propose a method of manufacturing a small electronic unit configured so that both connection terminals can be reliably conducted via an ACF when pressed against each other. Also, an object of the invention to propose a camera module equipped with a small electronic unit manufactured by the manufacturing method, and a mobile terminal end with the camera module.

  Note that Patent Documents 1 and 2 do not describe any problem that causes a conduction failure due to the thickness of the coverlay when the connection terminal of the flexible substrate and the connection terminal of the rigid substrate are connected by the ACF, or a solution to the problem.

  The above object is achieved by the invention described below.

1. A plurality of first connection terminals arranged at a predetermined interval on a first printed board made of a rigid board or a flexible board, and a plurality of second terminals arranged at a predetermined interval on a second printed board made of a flexible board. Of an electronic unit for connecting the second connection terminal to the first connection terminal by interposing an anisotropic conductive film between the connection terminal and pressing the second printed circuit board with a crimping head. A manufacturing method comprising:
A first cover lay is disposed between the plurality of first connection terminals on the first printed circuit board, and the first cover lay protrudes from the surface of the first connection terminal at a height A,
A second coverlay is disposed between the plurality of second connection terminals on the second printed circuit board, and the second coverlay protrudes at a height B from the surface of the second connection terminal. When
A convex portion having a height obtained by adding B to A is provided at a portion corresponding to the portion where the second connection terminal is located on the surface of the crimping head facing the second printed circuit board. A method of manufacturing a small electronic unit, wherein the second printed circuit board is pressed by a portion.

2. A plurality of first connection terminals arranged at a predetermined interval on a first printed board made of a rigid board or a flexible board, and a plurality of second terminals arranged at a predetermined interval on a second printed board made of a flexible board. Of an electronic unit for connecting the second connection terminal to the first connection terminal by interposing an anisotropic conductive film between the connection terminal and pressing the second printed circuit board with a crimping head. A manufacturing method comprising:
A first cover lay is disposed between the plurality of first connection terminals on the first printed circuit board, and the first cover lay protrudes from the surface of the first connection terminal at a height A,
A second coverlay is disposed between the plurality of second connection terminals on the second printed circuit board, and the second coverlay protrudes at a height B from the surface of the second connection terminal. When
A convex portion having a height obtained by adding B to A is provided at a portion corresponding to a portion where the second connection terminal is located on a surface of the second printed board facing the crimping head. A method of manufacturing a small electronic unit, wherein the second printed circuit board is pressed by a portion.

  3. 3. The method for manufacturing a small electronic unit according to 2, wherein the convex portion is a cover lay or a dummy pattern.

  4). 4. The method for manufacturing a small electronic unit according to any one of 1 to 3, wherein a dimension in the surface direction of the second cover lay is smaller than a dimension in the surface direction of the first cover lay.

  5. 5. A camera module comprising a small electronic unit manufactured by the method for manufacturing a small electronic unit according to any one of 1 to 4 above.

  6). A portable terminal comprising the camera module according to 5 above.

A method of manufacturing a small electronic unit of the present invention, a camera module, and according to the portable terminal end, is interposed an ACF between the connection terminals of the connection terminals and the rigid substrate or a flexible substrate of the flexible substrate, the connection of the flexible substrate in compression head When the terminal is press-contacted to the connection terminal of the rigid substrate, both connection terminals are reliably conducted through the ACF.

It is an external view of a mobile phone. It is a longitudinal cross-sectional view of an imaging device. It is a bottom view of an imaging device. It is a block diagram which connects the connection terminal of a flexible substrate to the connection terminal of a rigid board | substrate by ACF. It is sectional drawing which made the dimension of the coverlay of a rigid board | substrate different from the dimension of the coverlay of a flexible substrate. It is a figure of a different structure which connects the connection terminal of a flexible substrate to the connection terminal of a rigid board | substrate by ACF. It is the conventional block diagram which connects the connection terminal of a flexible substrate to the connection terminal of the rigid board | substrate in a camera module by ACF.

  First, a mobile phone as an example of a mobile terminal will be described based on an external view of FIG. 1A is a view of the folded mobile phone when viewed from the inside, and FIG. 1B is a view of the folded mobile phone when viewed from the outside.

  In FIG. 1, in the mobile phone T, an upper housing 101 as a case having display screens D <b> 1 and D <b> 2 and a lower housing 102 having operation buttons B are connected via a hinge 103. The imaging device is built under the display screen D2 in the upper casing 101, and the imaging lens L is exposed on the outer surface of the upper casing 101.

  Note that the position of the imaging device may be disposed above or on the side of the display screen D2 in the upper housing 101. Further, the mobile phone T is not limited to a folding type.

  Next, an example of an embodiment of an imaging device built in the above-described mobile phone or the like will be described with reference to the drawings. 2 is a longitudinal sectional view of the image pickup apparatus, and FIG. 3 is a bottom view of the image pickup apparatus.

  First, the configuration of the imaging apparatus will be described mainly with reference to FIG.

  The imaging optical system includes an imaging lens L and an infrared cut filter F that are formed from a plurality of lenses (not shown) from the subject side, and subject light passes through the imaging optical system and is transmitted from a CCD type image sensor, a CMOS type image sensor, or the like. The image is formed on the imaging device 11.

  In the following description, the subject side is referred to as the upper side or the upper side, and the opposite side is referred to as the lower side or the lower side.

  The imaging lens L is held by an inner lens frame 21 in which a male screw 21 a is formed. The male screw 21 a is screwed with a female screw 22 a formed in the outer lens frame 22. The outer mirror frame 22 is engaged with the AF actuator 23 by means (not shown), and the AF actuator 23 is fixed to the outer cylinder 24.

  The infrared cut filter F is held by the holding frame 25.

  The outer cylinder 24 is joined to the holding frame 25 on the upper side, and the rigid substrate 12 on which the image pickup device 11 and the like are mounted is joined to the lower side.

  The rigid substrate 12 has a flexible substrate 13 in close contact with the lower surface, and is mechanically and electrically connected. The flexible substrate 13 has a connector 13h for connecting to an external circuit.

  Further, the outer cylinder 24 and the holding frame 25 are covered with a shield case 27 formed of a conductive metal plate such as stainless steel or aluminum, and are electromagnetically shielded except for the bottom of the imaging device. The shield case 27 is formed in a cylindrical shape, and a hole through which a light beam to the imaging lens L passes is formed in the upper part.

  In the above configuration, the focus adjustment of the imaging lens L is performed because the male screw 21a and the female screw 22a are screwed together, so that the inner lens frame 21 is moved with respect to the outer lens frame 22 while the inner lens frame 21 is rotated. Move along O. Further, based on information measured by a distance measuring unit (not shown), the AF actuator 23 moves the imaging lens L along the optical axis O together with the outer lens frame 22 to perform focus adjustment.

  Next, FIG. 4 shows a configuration in which the connection terminal of the flexible substrate 13 is connected to the connection terminal of the rigid substrate 12 by ACF.

  4A is a plan view of the rigid substrate 12 (first printed circuit board) viewed from the connection terminals 12b and 12c (first connection terminal) side, and FIG. 4B is a rigid substrate. 12 is a cross-sectional view. On the base 12a of the rigid substrate 12, a plurality of connection terminals 12b and 12c that have been subjected to gold plating for reducing contact resistance and preventing rust are disposed, and are disposed on the left and right as shown in FIG. . A cover lay 12d (first cover lay) made of an insulating material and protecting the wiring circuit is arranged between the connection terminals 12b and 12c.

  In addition, the image sensor 11 is mounted at the center of the back surface side with respect to the surface on which the connection terminals 12b and 12c are arranged. Since the image pickup device 11 is mounted at substantially the center of the rigid board 12 and the image pickup device 62 has a large number of leads, the number of connection terminals 12b and 12c is also large. Therefore, it is difficult to arrange the connection terminals 12b and 12c only at one end of the rigid substrate 12, and the connection terminals 12b are arranged at the left end and the connection terminals 12c are arranged at the right end to be dispersed.

  4A is a plan view of the flexible substrate 13 (second printed circuit board) as viewed from the back side with respect to the surface on which the connection terminals 13b and 13c (second connection terminals) are arranged. A sectional view of the flexible substrate 13 is shown in FIG. On the base 12a of the flexible substrate 13, a plurality of connection terminals 13b and 13c subjected to gold plating for reducing contact resistance and preventing rust are arranged. As shown in FIG. 4A, the connection terminals 12b and 12c are connected to the connection terminals 12b and 12c. It is arrange | positioned in the position which opposes on either side. A cover lay 13d (second cover lay) made of an insulating material and protecting the wiring circuit is disposed between the connection terminals 13b and 13c.

  FIG. 4B is a diagram in which the flexible substrate 13 is connected to the rigid substrate 12 by ACF. Note that FIG. 4B is partially exaggerated for clarity of explanation.

  The rigid board 12 is arranged on a predetermined pedestal 32, and is positioned so that the connection terminals 13b and 13c of the flexible board 13 face the connection terminals 12b and 12c of the rigid board 12, and the connection terminals 12b and 12c are connected to the connection terminals 13b. , 13c, ACF15 (anisotropic conductive film) is interposed. Then, the flexible substrate 13 is pressed by the crimping head 31 and thermocompression bonded to the rigid substrate 12.

  At this time, the cover lay 12d is thicker than the connection terminals 12b and 12c of the rigid board 12, and the cover lay 12d protrudes from the surfaces of the connection terminals 12b and 12c. The same applies to the flexible substrate 13, and the cover lay 13d protrudes from the surfaces of the connection terminals 13b and 13c. Specifically, the protruding amount of the cover lay 12d and the cover lay 13d is 10 to 30 μm, and the thickness of the ACF 15 is 20 to 35 μm.

  For this reason, when the flexible substrate 13 is pressed by a crimping head having a flat bottom surface, the cover lay 13d is pressed against the cover lay 12d, but the connection terminals 13b and 13c are sufficiently pressed against the connection terminals 12b and 12c via the ACF 15. I can't. Of course, the flexible substrate 13 is thin and deforms, and the connection terminals 13b and 13c come into contact with the connection terminals 12b and 12c through the ACF 15. However, the connection cannot be reliably conducted, and a conduction failure tends to occur.

  Therefore, a convex portion 31a having a height C is provided at a portion corresponding to the portion where the connection terminals 13b and 13c are located on the surface of the crimping head 41 facing the flexible substrate 13. The height C is a value obtained by adding the height B at which the cover lay 13d protrudes from the surface of the connection terminals 13b and 13c to the height A at which the cover lay 12d protrudes from the surface of the connection terminals 12b and 12c.

  By using the crimping head 31 having the convex portion 31a having such a height, the connection terminals 13b and 13c are surely pressed against the connection terminals 12b and 12c via the ACF 15 even when the cover lays 12d and 13d protrude. Conduction does not occur and conduction failure does not occur.

  When the dimensions of the cover lay 12d and the cover lay 13d in the surface direction are equal, the attachment positions of the cover lays 12d and 13d are shifted from each other, or the set position of the flexible substrate 13 with respect to the rigid substrate 12 is shifted. The convex portion 41a of the crimping head 41 presses the cover lay 13d, and the pressing force is not uniform. For this reason, there exists a possibility that a conduction defect may occur in the connection terminal 13b and the connection terminal 12b or in the connection terminal 13c and the connection terminal 12c.

  Therefore, as shown in FIG. 5, if the dimension N in the surface direction of the cover lay 13d is made smaller than the dimension M in the surface direction of the cover lay 12d, the convex portion 31a of the crimping head 31 presses the cover lay 13d. Therefore, there is no risk of poor conduction.

  Further, as shown in FIG. 6, the height B is added to the above-described height A at the portion corresponding to the portion where the connection terminals 12b and 12c are located on the surface of the flexible substrate 13 facing the crimping head 41. A convex portion 13e having a height C may be provided. As a result, even if the surface of the crimping head 41 facing the flexible substrate 13 is a flat surface, the connection terminals 13b and 13c are reliably pressed and connected to the connection terminals 12b and 12c via the ACF 15 to cause poor contact. There is no. Even if the crimping head 41 is displaced in the horizontal direction with respect to the flexible substrate 13, the connection terminals 13 b and 13 c are reliably pressed against the connection terminals 12 b and 12 c via the ACF 15.

  In addition, the convex part 13e may be formed with a thick cover lay, or may be formed with a dummy pattern that is thick and does not conduct with others.

  The embodiment described above is for electrically connecting a flexible substrate to a rigid substrate via an ACF, but the present invention can be applied in the same manner even if the flexible substrate is electrically connected to a flexible substrate.

  Further, the present invention is not limited to the printed circuit board of the camera module, but can be applied to printed circuit boards of various small electronic units.

12, 61 Rigid substrate 12b, 12c, 13b, 13c, 61b, 61c, 63b, 63c Connection terminal 12d, 13d, 61d, 63d Coverlay 11, 62 Imaging element 13, 63 Flexible substrate 15, 65 ACF
31, 41, 71 Crimp head 13e, 31a Convex part L Imaging lens O Optical axis

Claims (6)

A plurality of first connection terminals arranged at a predetermined interval on a first printed board made of a rigid board or a flexible board, and a plurality of second terminals arranged at a predetermined interval on a second printed board made of a flexible board. Of an electronic unit for connecting the second connection terminal to the first connection terminal by interposing an anisotropic conductive film between the connection terminal and pressing the second printed circuit board with a crimping head. A manufacturing method comprising:
A first cover lay is disposed between the plurality of first connection terminals on the first printed circuit board, and the first cover lay protrudes from the surface of the first connection terminal at a height A,
A second coverlay is disposed between the plurality of second connection terminals on the second printed circuit board, and the second coverlay protrudes at a height B from the surface of the second connection terminal. When
A convex portion having a height obtained by adding B to A is provided at a portion corresponding to the portion where the second connection terminal is located on the surface of the crimping head facing the second printed circuit board. A method of manufacturing a small electronic unit, wherein the second printed circuit board is pressed by a portion. A plurality of first connection terminals arranged at a predetermined interval on a first printed board made of a rigid board or a flexible board, and a plurality of second terminals arranged at a predetermined interval on a second printed board made of a flexible board. Of an electronic unit for connecting the second connection terminal to the first connection terminal by interposing an anisotropic conductive film between the connection terminal and pressing the second printed circuit board with a crimping head. A manufacturing method comprising:
A first cover lay is disposed between the plurality of first connection terminals on the first printed circuit board, and the first cover lay protrudes from the surface of the first connection terminal at a height A,
A second coverlay is disposed between the plurality of second connection terminals on the second printed circuit board, and the second coverlay protrudes at a height B from the surface of the second connection terminal. When
A convex portion having a height obtained by adding B to A is provided at a portion corresponding to a portion where the second connection terminal is located on a surface of the second printed board facing the crimping head. A method of manufacturing a small electronic unit, wherein the second printed circuit board is pressed by a portion.   The method of manufacturing a small electronic unit according to claim 2, wherein the convex portion is a cover lay or a dummy pattern.   The method for manufacturing a small electronic unit according to any one of claims 1 to 3, wherein a dimension in the surface direction of the second coverlay is smaller than a dimension in the surface direction of the first coverlay. .   A camera module comprising a small electronic unit manufactured by the method for manufacturing a small electronic unit according to claim 1.   A portable terminal comprising the camera module according to claim 5.

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