JP2005108993A - Flexible printed board, mounting structure, electrooptic device equipped therewith, and electronic equipment equipped with electrooptic device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a flexible printed board that can improve the mechanical strength of a packaged IC in which a plurality of solder balls are arranged along a bottom face of the IC when the IC is mounted on the board, and to provide a mounting structure, an electrooptic device equipped with the mounting structure, and electronic equipment equipped with the electrooptic device. <P>SOLUTION: An FPC 10 has a packaged-IC mounting area A for mounting the packaged IC. In the packaged-IC mounting area A, lands 13 are formed for soldering the solder balls of the packaged IC and the width of metallic wiring 14a connected to the lands 13a in the outer peripheral section of the packaged-IC mounting area A is adjusted to 1/2-1 times of the diameters of the lands 13a. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a flexible printed circuit board, a mounting structure, an electro-optical device on which the mounting structure is mounted, and an electronic device on which the electro-optical device is mounted. Specifically, a plurality of solder balls are arranged along the bottom surface of an IC. The present invention relates to a flexible printed circuit board on which a packaged IC is mounted, a mounting structure, an electro-optical device on which the mounting structure is mounted, and an electronic apparatus on which the electro-optical device is mounted.

  A package IC of a type called CSP (Chip Size Package) or BGA (Ball Grid Array) may be employed in response to high-density mounting of electronic components. In this type of package IC, solder balls are arranged in a line along the bottom surface of the IC, and are soldered to a printed circuit board by reflow. Here, the procedure of soldering the package IC will be described. (1) Supply and apply cream solder to the soldered portion of the printed circuit board by screen printing or the like. (2) The cream solder application state is inspected. (3) The package IC is placed on the printed circuit board coated with cream solder. (4) The printed circuit board on which the package IC is placed is placed in a reflow apparatus and the whole is heated. Thereby, the cream solder and the solder balls are melted and soldering is performed. (5) Thereafter, the printed circuit board on which the package IC is placed is taken out of the reflow device and cooled.

  Conventionally, a hard substrate such as a PCB has been used as a printed circuit board on which the above-described package IC is mounted. In recent years, FPC (Flexible Printed Circuits) having a high degree of freedom in design and shape deformation is easy. A flexible printed circuit board such as heat seal is used (see Patent Documents 1 and 2).

JP-A-8-43844 Japanese Patent Laid-Open No. 11-258621

  However, when the package IC is mounted on the flexible printed circuit board, stress is applied to the vicinity of the outer periphery of the package IC in the metal wiring of the flexible printed circuit board due to an impact such as dropping, and this part is disconnected, resulting in poor conduction. There is a problem. A phenomenon in which the metal wiring is disconnected in this way will be described with reference to FIG. FIG. 9A is a bottom view of the package IC, FIG. 9B is a cross-sectional view of the mounting board on which the package IC is mounted on the flexible printed board, and FIG. 9C is a plan view around the package IC mounting area of the flexible printed board. The figure is shown.

  As shown in FIG. 9A, the package IC 100 has a plurality of rows (3 × 3) of solder balls 101 arranged on the bottom surface thereof. In the figure, the solder balls on the outer periphery of the package IC 100 are shown as 101a. As shown in FIGS. 9-2 and 9-3, the flexible printed circuit board 200 is formed with a conductive layer 220 including a land 221 and a metal wiring 222 on an insulating layer 210. Further, a resist 230 for protecting the conductive layer 220 is formed on the outer periphery of the package IC mounting area. The package IC 100 is mounted by melting the solder balls 101 on the lands 221 in the package IC mounting area of the flexible printed board 200. In FIG. 9C, the land on the outer peripheral portion of the package IC mounting area is shown as 221a, and the metal wiring connected to the land 221a on the outer peripheral portion of the package IC mounting area is shown as 222a.

  In the mounting substrate in which the package IC 100 is mounted on the flexible printed circuit board 200, stress is applied to the outer periphery of the package IC mounting area due to an impact such as dropping, and the metal wiring 222a connected to the land 221a in the outer periphery is soldered. There is a problem of disconnection at the boundary.

  The present invention has been made in view of the above, and when a package IC in which a plurality of solder balls are arranged along the bottom surface of an IC is mounted on a flexible printed circuit board, the mechanical strength thereof can be improved. It is an object of the present invention to provide a flexible printed board, a mounting structure, an electro-optical device on which the mounting structure is mounted, and an electronic apparatus on which the electro-optical device is mounted.

  In order to solve the above-described problems, the present invention provides a flexible printed circuit board on which a package IC having a plurality of solder balls arranged on the bottom surface can be mounted, and has a package IC mounting area for mounting the package IC. In the mounting area, lands for soldering the solder balls of the package IC are formed, and the width of the metal wiring connected to the outer peripheral land of the package IC mounting area is set to 1 / of the land diameter. It is characterized by being 2 to 1 times.

  As a result, the strength of the metal wiring connected to the land on the outer periphery of the package IC mounting area can be improved, and even if stress is applied to the outer periphery of the package IC mounting area due to an impact such as dropping, the metal wiring Disconnection at the boundary with the solder on the land can be prevented. As a result, when a package IC having a plurality of solder balls arranged on the bottom surface is mounted on a flexible printed board, a flexible printed board capable of improving the mechanical strength can be provided.

  In order to solve the above-described problems, the present invention provides a flexible printed circuit board on which a package IC having a plurality of solder balls arranged on the bottom surface can be mounted, and has a package IC mounting area for mounting the package IC. In the mounting area, lands for soldering the solder balls of the package IC are formed, and the width of the metal wiring connected to the lands on the outer periphery of the package IC mounting area is substantially the same as the land diameter. It is characterized by that.

  As a result, the strength of the metal wiring connected to the land on the outer periphery of the package IC mounting area can be improved, and even if stress is applied to the outer periphery of the package IC mounting area due to an impact such as dropping, the metal wiring Disconnection at the boundary with the solder on the land can be prevented. As a result, when a package IC having a plurality of solder balls arranged on the bottom surface thereof is mounted on the flexible printed board, a flexible printed board capable of improving the mechanical strength can be provided.

  In order to solve the above-described problems, the present invention provides a flexible printed circuit board on which a package IC having a plurality of solder balls arranged on the bottom surface can be mounted, and has a package IC mounting area for mounting the package IC. In the mounting area, lands for soldering the solder balls of the package IC are formed, and metal wirings connected to the lands on the outer periphery of the package IC mounting area are arranged inside the package IC mounting area. It is characterized by being pulled out after being pulled out.

  As a result, in the metal wiring connected to the land on the outer periphery of the package IC mounting area, the portion that becomes the boundary with the solder formed on the land is not near the outer periphery of the package IC mounting area. The stress is no longer applied to the boundary portion with the solder, and disconnection at the boundary portion with the solder can be prevented.

  According to a preferred aspect of the present invention, it is desirable that a protective layer for protecting the metal wiring is formed outside the package IC mounting area. Thereby, the metal wiring currently formed in the flexible printed circuit board can be protected, and the mechanical strength of a flexible printed circuit board can be improved more.

  In order to solve the above problems, the present invention provides a mounting structure in which a package IC having a plurality of solder balls arranged on the bottom surface is mounted on a flexible printed circuit board, and has a package IC mounting area on which the package IC is mounted. In the package IC mounting area, lands to which solder balls of the package IC are soldered are formed, and metal wirings connected to the lands to which solder balls on the outer periphery of the package IC are soldered are formed. The width is ½ to 1 times the land diameter.

  As a result, the strength of the metal wiring connected to the land on the outer periphery of the package IC mounting area can be improved, and even if stress is applied to the outer periphery of the package IC mounting area due to an impact such as dropping, the metal wiring Disconnection at the boundary with the solder on the land can be prevented. As a result, when a package IC in which a plurality of solder balls are arranged on the bottom surface of the IC is mounted on a flexible printed circuit board, a mounting structure capable of improving the mechanical strength can be provided.

  In order to solve the above problems, the present invention provides a mounting structure in which a package IC having a plurality of solder balls arranged on the bottom surface is mounted on a flexible printed circuit board, and has a package IC mounting area on which the package IC is mounted. In the package IC mounting area, a land to which the solder ball of the package IC is soldered is formed, and the metal wiring connected to the land for soldering the solder ball on the outer periphery of the package IC The width is substantially the same as the land diameter.

  As a result, the strength of the metal wiring connected to the land on the outer periphery of the package IC mounting area can be improved, and even if stress is applied to the outer periphery of the package IC mounting area due to an impact such as dropping, the metal wiring Disconnection at the boundary with the solder on the land can be prevented. As a result, when a package IC in which a plurality of solder balls are arranged on the bottom surface of the IC is mounted on a flexible printed circuit board, a mounting structure capable of improving the mechanical strength can be provided.

  In order to solve the above-described problem, a mounting structure in which a plurality of solder balls are arranged on the bottom surface and mounted with a package IC has a package IC mounting area on which the package IC is mounted, and the package IC mounting area Are formed with lands to which the solder balls of the package IC are soldered, and metal wirings connected to the lands on the outer periphery of the package IC mounting area are drawn from the inner side of the package IC mounting area of the land. Later, it is drawn out of the package IC mounting area.

  As a result, in the metal wiring connected to the land on the outer periphery of the package IC mounting area, the portion that becomes the boundary with the solder formed on the land is not near the outer periphery of the package IC mounting area. The stress is no longer applied to the boundary portion with the solder, and disconnection at the boundary portion with the solder can be prevented. As a result, it is possible to provide a mounting structure capable of improving the mechanical strength when a package IC having a plurality of solder balls disposed on the bottom surface thereof is mounted on an FPC.

  According to a preferred aspect of the present invention, it is desirable that a protective layer for protecting the metal wiring is formed outside the package IC mounting area. Thereby, the metal wiring currently formed in the flexible printed circuit board can be protected, and the mechanical strength of a flexible printed circuit board can be improved more.

  According to a preferred aspect of the present invention, it is desirable to mount the mounting structure of the present invention on an electro-optical device. Thereby, an electro-optical device equipped with a mounting structure having high mechanical strength can be provided.

  According to a preferred aspect of the present invention, it is desirable to mount the electro-optical device of the present invention on an electronic apparatus. Thereby, the electronic device carrying the mounting structure with high mechanical strength can be provided.

  Hereinafter, the present invention will be described in detail with reference to the drawings. Note that the present invention is not limited to the embodiments. In addition, constituent elements in the following embodiments include those that can be easily assumed by those skilled in the art or those that are substantially the same. In the following embodiments, a case where a package IC is mounted on an FPC mounted on a liquid crystal display device will be described as an example. However, the electro-optical device according to the present invention is not limited to this. In the present invention, a CSP type IC is described as the package IC, but the package IC of the present invention is not limited to this.

  FIG. 1 is a plan view showing a schematic configuration of a liquid crystal display device 1 equipped with a mounting structure according to the present invention. As shown in FIG. 1, the liquid crystal display device 1 includes a liquid crystal display panel 2 that can display an image, and an FPC mounting board (mounting structure) 3 that is pressure-bonded to the liquid crystal display panel 2. A driver IC 4 is mounted on the liquid crystal display panel 2. A backlight (not shown) and the like are provided below the liquid crystal display panel. The FPC mounting substrate 3 is configured by mounting a package IC 20 of a power supply circuit and an electrical component 30 such as a resistor or a capacitor on the FPC 10.

  The configuration of the package IC 20 will be described with reference to FIG. FIG. 2A is a bottom view of the package IC 20, and FIG. 2B is a schematic perspective view for explaining the internal structure of the package IC 20. The package IC 20 is a CSP type IC, and has a configuration in which the size of the package is equal to or slightly larger than that of the semiconductor element.

  2A and 2B, 21 is a solder ball, 22 is a sealing layer for sealing the solder ball, 23 is a metal wiring sealed in an insulating resin layer 24, and 24 is a metal wiring 23. An insulating resin layer to be sealed, 25 is a Si chip (semiconductor chip), and 26 is a bonding pad formed on the Si chip 25. Further, as shown in FIG. 2A, the package IC 20 has 3 × 3 solder balls 21 arranged in a lattice shape on the bottom surface thereof. In the drawing, the solder balls on the outer periphery of the package IC 20 are shown as 21a.

  The configuration of the FPC 10 in FIG. 1 will be described with reference to FIGS. 3 and 4. FIG. 3 is a cross-sectional view of the FPC mounting board 3 on which the package IC 20 is mounted on the FPC 10, and FIG. 4 is a plan view of the periphery of the package IC mounting area A of the FPC 10. As shown in FIGS. 3 and 4, the FPC 10 includes an insulating layer 11 made of polyimide or the like, a conductive layer 12 formed on the insulating layer 11 and made of lands 13 and metal wirings 14, and package IC mounting. The resist 15 is provided outside the area A and is a protective layer for protecting the conductive layer 12.

  As shown in FIG. 4, the FPC 10 has a package IC mounting area A in which the package IC 20 is mounted. In the package IC mounting area A, lands 13 for soldering the solder balls 21 of the package IC 20 are formed. A metal wiring 14 is connected to the land 13. The land 13 and the metal wiring 14 can be made of Cu, W, Mo, Ag, Pd, or the like. In the same figure, the land on the outer periphery of the package IC mounting area A is shown as 13a, and the metal wiring connected to the land 13a on the outer periphery of the package IC mounting area is shown as 14a. The package IC 20 is mounted by melting the solder balls 21 on the lands 13 in the package IC mounting area A of the FPC 10 and then melting them with a reflow apparatus.

  In the first embodiment, when the package IC 20 is mounted on the FPC 10, the metal wiring 14a connected to the land 13a on the outer peripheral portion of the package IC mounting area A is a boundary portion with the solder formed on the land 13a. Therefore, the width of the metal wiring 14a connected to the land 13a on the outer periphery of the package IC mounting area A is set to 1/2 to 1 times the land diameter. FIG. 3 shows a case where the width of the metal wiring 14a is substantially the same as the land diameter.

FIG. 5 is a diagram showing a test result of the mechanical strength when the width of the metal wiring 14a is changed.
The test results are shown in which a drop test was performed by attaching the FPC 10 (FPC mounting board 2) with the package IC 20 mounted on a hexahedral housing. Specifically, when the width of the metal wiring 14a is 1/5, 1/3, 1/2, and 1/1 of the land diameter, the height is 1.6 m (the upper limit of the height that is assumed to fall). The drop test was carried out up to 10 cycles with a 6-plane drop as one cycle, and the presence or absence of disconnection was confirmed.

  As shown in FIG. 4, when the width of the metal wiring 14a is 1/5 of the land diameter, the metal wiring 14a is disconnected at the sixth cycle, and the durability is up to five cycles. When the width of the metal wiring 14a is 1/3 of the land diameter, the metal wiring 14a is disconnected in the ninth cycle, and the durability is up to eight cycles. When the width of the metal wiring 14a was 1/2 and 1/1 of the land diameter, the metal wiring 14a was not broken even at the 10th cycle. As this test result shows, it can be seen that the width of the metal wiring 14a is preferably ½ times the land diameter or more in terms of impact strength (mechanical strength).

  According to the first embodiment, the width of the metal wiring 14a connected to the land 13a on the outer periphery of the package IC mounting area A1 is set to 1/2 to 1 times the land diameter. The strength of the metal wiring connected to the peripheral land 13a can be improved, and the solder on the land 13a of the metal wiring 14a can be applied even if stress is applied to the outer peripheral portion of the mounting area of the package IC due to an impact such as dropping. It is possible to prevent disconnection at the boundary between the two. As a result, when a package IC in which a plurality of solder balls are arranged on the bottom surface of the IC is mounted on the FPC, it is possible to provide an FPC capable of improving its mechanical strength.

(Modification)
FIG. 6 is a diagram illustrating a structure around the mounting area of the package IC 20 of the FPC 10 according to the modification of the first embodiment. In the first embodiment, the width of the metal wiring 14a connected to the land 13a on the outer periphery of the package IC mounting area A is set to 1/2 to 1 times the land diameter. In the modified example, the portion where the disconnection occurs in the metal wiring 14a is formed on the land 13a as shown in FIG. 6, paying attention to the disconnection at the boundary with the solder formed on the land 13a. The width of the metal wiring 14a is set to 1/2 to 1 times the land diameter only in the vicinity of the boundary with the solder, while the width is narrowed from a position spaced apart from the mounting area A of the package IC 20 by a predetermined distance L. The width is the same as that of the metal wiring 14. As a result, the area of the metal wiring 14a can be reduced and the cost can be reduced.

  FIG. 7 is a diagram illustrating the structure around the mounting area of the package IC of the FPC 3 according to the second embodiment. In the first embodiment, the mechanical strength is improved by increasing the width of the metal wiring 14a connected to the land 13a on the outer periphery of the package IC mounting area A. On the other hand, in the second embodiment, as shown in FIG. 7, the structure is drawn from the inside of the package IC mounting area A of the land 13a and then drawn to the outside of the package IC mounting area A. With this configuration, the portion of the metal wiring 14a that becomes the boundary with the solder formed on the land 13a is no longer in the vicinity of the outer peripheral portion of the package IC mounting area A. No stress is applied, and disconnection at the boundary with the solder formed on the land 13a can be prevented.

  In the above-described embodiments, the CSP type IC has been described as the package IC. However, the present invention is not limited to this, and the size of the package may be larger than that of the semiconductor chip. Applicable.

(Application example to electronic equipment)
Next, a specific example of an electronic apparatus to which the electro-optical device according to the invention can be applied will be described with reference to FIG. FIG. 8A is a perspective view illustrating an example in which the electro-optical device according to the present invention is applied to a display unit of a portable personal computer (so-called notebook personal computer) 40. As shown in the figure, the personal computer 40 includes a main body 42 having a keyboard 41 and a display unit 43 to which the electro-optical device according to the present invention is applied. FIG. 8B is a perspective view illustrating an example in which the electro-optical device according to the invention is applied to the display unit of the mobile phone 50. As shown in the figure, the cellular phone 50 includes a plurality of operation buttons 51, a receiving mouth 52, a mouthpiece 53, and a display unit 54 to which the electro-optical device according to the present invention is applied.

  The flexible printed circuit board and the mounting structure according to the present invention can be used for various devices on which the flexible printed circuit board is mounted. In addition, the electro-optical device according to the present invention can be used for a transmissive, reflective, and transflective electro-optical device. The electro-optical device according to the present invention is applied to a passive matrix type electro-optical device or an active matrix type electro-optical device (for example, an electro-optical panel including a TFT (thin film transistor) or a TFD (thin film diode) as a switching element). Can be used. Furthermore, the electro-optical device according to the present invention is not limited to a liquid crystal display device, but is an organic electroluminescence device, an inorganic electroluminescence device, a plasma display device, an electrophoretic display device, an electron emission display device (Field Emission Display and Surface-Conduction Electoron). -Emitter Display etc.), LED (Light Emitting Diode) display devices, etc., and can be used for various electro-optical devices that can control the display state for each of a plurality of pixels.

  An electronic device equipped with the electro-optical device according to the present invention includes a mobile phone, a portable information device called PDA (Personal Digital Assistants), a portable personal computer, a personal computer, a workstation, a digital still camera, an in-vehicle monitor, a digital Widely used in electronic devices such as video cameras, LCD TVs, viewfinder type, monitor direct-view type video tape recorders, car navigation devices, pagers, electronic notebooks, calculators, word processors, workstations, video phones, and POS terminals. Can do.

1 is a plan view showing a schematic configuration of a liquid crystal display device according to Embodiment 1; Bottom view of package IC according to embodiment 1 FIG. 3 is a schematic perspective view for explaining an internal structure of the package IC according to the first embodiment. Sectional drawing of the FPC mounting substrate which mounted package IC concerning Example 1 in FPC. FIG. 3 is a plan view of the periphery of the package IC mounting area of the FPC according to the first embodiment. The figure which shows the test result of mechanical strength at the time of changing the width | variety of the metal wiring concerning Example 1. FIG. The top view which shows the structure of the periphery of the mounting area of package IC of FPC concerning a modification. FIG. 6 is a plan view showing a structure around a mounting area of an FPC package IC according to a second embodiment; FIG. 3 is a perspective view of a personal computer including the electro-optical device according to the example. 1 is a perspective view of a mobile phone including an electro-optical device according to an example. The bottom view of package IC. Sectional drawing of the mounting substrate which mounted the package IC on the flexible printed circuit board. The top view of the package IC mounting area periphery of a flexible printed circuit board.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Liquid crystal display device, 2 Liquid crystal display panel, 3 FPC mounting board, 4 Driver IC, 10 FPC, 11 Insulating layer, 12 Conductive layer, 13 Land, 14 Metal wiring, 15 Protective layer, 20 Package IC, 21 Solder ball, 22 Sealing layer, 23 Insulating resin layer, 24 Metal wiring, 25 Si chip (semiconductor chip), 26 Bonding pad, 30 Electrical component, 40 Personal computer, 41 Keyboard, 42 Main body part, 43 Display part, 50 Mobile phone, 51 Operation buttons, 52 Earpiece, 53 Mouthpiece, 54 Display

Claims (10)

In a flexible printed circuit board on which a package IC in which a plurality of solder balls are arranged on the bottom surface can be mounted,
A package IC mounting area for mounting the package IC;
In the package IC mounting area, lands for soldering the solder balls of the package IC are formed,
A flexible printed circuit board, wherein a width of a metal wiring connected to a land on an outer peripheral portion of the package IC mounting area is ½ to 1 times the land diameter. In a flexible printed circuit board on which a package IC in which a plurality of solder balls are arranged on the bottom surface can be mounted,
A package IC mounting area for mounting the package IC;
In the package IC mounting area, lands for soldering the solder balls of the package IC are formed,
A flexible printed circuit board characterized in that a width of a metal wiring connected to a land on an outer peripheral portion of the package IC mounting area is substantially the same as the land diameter. In a flexible printed circuit board on which a package IC in which a plurality of solder balls are arranged on the bottom surface can be mounted,
A package IC mounting area for mounting the package IC;
In the package IC mounting area, lands for soldering the solder balls of the package IC are formed,
A flexible print characterized in that a metal wiring connected to a land on an outer peripheral portion of the package IC mounting area is pulled out from the inner side of the package IC mounting area of the land and then pulled out of the package IC mounting area. substrate.   The flexible printed circuit board according to any one of claims 1 to 3, wherein a protective layer for protecting metal wiring is formed outside the package IC mounting area. In a mounting structure in which a package IC in which a plurality of solder balls are arranged on the bottom surface is mounted on a flexible printed circuit board,
A package IC mounting area on which the package IC is mounted;
In the package IC mounting area, lands to which solder balls of the package IC are soldered are formed,
A mounting structure characterized in that a width of a metal wiring connected to a land to which solder balls on an outer peripheral portion of the package IC are soldered is set to 1/2 to 1 times the land diameter. In a mounting structure in which a package IC in which a plurality of solder balls are arranged on the bottom surface is mounted on a flexible printed circuit board,
A package IC mounting area on which the package IC is mounted;
In the package IC mounting area, lands to which solder balls of the package IC are soldered are formed,
A mounting structure characterized in that a width of a metal wiring connected to a land for soldering a solder ball on an outer peripheral portion of the package IC is substantially the same as the land diameter. In a mounting structure in which a package IC in which a plurality of solder balls are arranged on the bottom surface is mounted,
A package IC mounting area on which the package IC is mounted;
In the package IC mounting area, lands to which solder balls of the package IC are soldered are formed,
A mounting structure in which a metal wiring connected to a land on an outer peripheral portion of the package IC mounting area is pulled out from the inner side of the package IC mounting area of the land and then pulled out of the package IC mounting area. body.   The mounting structure according to claim 5, wherein a protective layer for protecting metal wiring is formed outside the package IC mounting area.   An electro-optical device comprising the mounting structure according to any one of claims 5 to 8.   An electronic apparatus comprising the electro-optical device according to claim 9.

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