JP2000058985A - Wiring board, liquid crystal device, and electronic equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a structure which can prevent the breakage of a wiring board having a two-layer structure. SOLUTION: A wiring board 7 is provided with a base layer 1, a metallic film pattern 2 formed directly on the base layer 1, and mounted parts 17 which are mounted on the layer 1. Breakage of the wiring board 7 is prevented by preventing the occurrence of cracks in the circumference of the parts 17, by providing a reinforcing member 22A around the parts 17 on the base layer 1.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a wiring board having a wiring pattern formed directly on a base layer. The present invention also relates to a liquid crystal device including the wiring substrate. The invention also relates to an electronic device including the liquid crystal device.

[0002]

2. Description of the Related Art In recent years, liquid crystal devices have been widely used as a part of portable telephones, portable electronic terminals, electronic organizers, and other electronic devices, for example, image display units. The liquid crystal device is formed, for example, as follows: a pair of substrates (often transparent substrates) each having an electrode (eg, a transparent electrode) are attached to each other and formed between the substrates. It is formed by enclosing liquid crystal in a gap, a so-called cell gap. A polarizing plate is further mounted on the outer surface of the substrate as necessary, and a color filter is provided on the inner surface of one of the pair of substrates as necessary.

In this liquid crystal device, the light supplied to the liquid crystal can be modulated by controlling the orientation of the liquid crystal by controlling the voltage applied to electrodes facing each other with the liquid crystal interposed therebetween. Images such as numbers and patterns can be displayed. In order to control the voltage applied between the opposing electrodes in this way, in a normal liquid crystal device, a liquid crystal driving IC is conductively connected to those electrodes, and the applied voltage is controlled by the liquid crystal driving IC.

Various methods have been known for mounting a liquid crystal driving IC on a substrate. For example,
Taking a mounting method of a TAB (Tape Automated Bonding: Tape Automated Mounting) method, which has been conventionally known, as an example, in this mounting method, first, a TAB (Tape Automated Bonding) method is used.
ding) technology and FPC (Flexible Printed Circuit)
It: A liquid crystal driving IC is bonded on a flexible printed circuit board to form a TCP (Tape Carrier Package), and the TCP is connected to a substrate of the liquid crystal panel, thereby forming an electrode in the liquid crystal panel. Is connected to a liquid crystal driving IC.

[0005] The FPC used in the conventional TAB technology is as follows.
For example, as shown in FIG. 9, it generally has a three-layer structure including a base layer 51, a metal film pattern 52, and an adhesive layer 55 for fixing the metal film pattern 52 to the base layer 51. . The base layer 51 is formed of, for example, PI (polyimide), and a metal film pattern 52 is formed.
Is formed of, for example, Cu (copper). This three-layer FPC has a three-layer structure, so that it is difficult to reduce its thickness, and there is a problem that it is relatively expensive.

In order to solve the above-mentioned problems of the three-layer FPC, recently, as shown in FIG. 8, a two-layer structure in which a metal film pattern 2 is directly formed on a base layer 1 is used. FPC3 has been proposed. In this FPC 3, the metal film pattern 2 is directly fixed on the base layer 1 by a sputtering method, a roll coating method or the like without using an adhesive.

[0007]

The wiring board using the FPC 3 having the two-layer structure as described above can have a smaller thickness and a smaller number of parts than the FPC having the three-layer structure. It has the advantage that it can be manufactured only at low cost.
However, since the FPC 3 having the two-layer structure has a small thickness, the FPC 3 has a problem in that the mechanical strength is weak and thus the FPC 3 is easily cut.

According to the experiment of the inventor, according to the experiment,
When mounting components such as a chip, a chip resistor, and a chip capacitor are mounted, when an external force is applied to the wiring board, a crack is generated around the mounting component, and the wiring board is often damaged. I understand.

The present invention has been made in view of the above problems, and has as its object to prevent a wiring board having a two-layer structure from being damaged.

[0010]

(1) In order to achieve the above object, a wiring board according to the present invention comprises: a base layer; a metal film pattern formed directly on the base layer; In a wiring board having a mounted component mounted thereon, a reinforcing member is provided around the mounted component.

According to this wiring board, the mechanical strength around the mounted components in the wiring board having the two-layer structure is increased by the function of the reinforcing member, and as a result, the wiring board can be reliably prevented from being damaged.

In the above structure, the "base layer" is formed of an insulating material, for example, PI (polyimide).
The “metal film pattern” is, for example, 5
It is formed with a thickness of about 8 μm. "Mounted parts"
Any electronic element, for example, an IC chip, a chip resistor, a chip capacitor, or the like can be considered.

[0013] In the above structure, "forming the metal film pattern directly on the base layer" does not mean that the metal film pattern is fixed to the base layer with an adhesive layer as in the conventional three-layer structure. This means that the metal film pattern is formed directly on the base layer.

Specifically, for example, first, a metal film such as Cu is formed to a uniform thickness on a PI film base layer by using a known film forming method such as a sputtering method or a roll coating method. Then, a wiring board can be manufactured by forming a desired metal film pattern using a known patterning method such as an electrolytic plating method or a photolithography method.

As the “reinforcing member”, any material that can improve the mechanical strength of the base layer can be used, and the material itself can be harder or softer than the base layer. Specifically, metal foil, PET (polyethylene terephthalate), PI (polyimide), and other plastics can be used.

(2) In the wiring board having the above structure, the reinforcing member can be provided on the same side of the base layer as the mounted component, or can be provided on the back side of the base layer as viewed from the mounted component. If the reinforcing member is provided on the same side as the mounted component, the thickness of the mounted component and the reinforcing member will overlap on the same side, so a hole is formed in the reinforcing member to allow the mounted component to escape. If the mounted components are stored in the wiring board, the overall thickness of the wiring board can be reduced.

On the other hand, if the reinforcing member is provided on the back side of the base layer as viewed from the mounted component, the thickness of the reinforcing member and the mounted component is on both the front and back sides of the base layer. The thickness increases. However, in this case, it is not necessary to form a hole for escaping the mounted component in the reinforcing member, and the reinforcing member can be formed with a uniform thickness.
The strength of the wiring board can be increased.

(3) In the wiring board having the above configuration, the length of the reinforcing member at the portion protruding from the mounted component, that is, the protruding length is d, and the total thickness of the base layer and the metal film pattern is When t, it is preferable that d ≧ t. By doing so, the strength of the wiring board can be increased to a practically sufficient level.

(4) In the wiring board having the above structure, the reinforcing member is desirably formed of a conductive material.
In this case, by using the reinforcing member, the electromagnetic shielding effect as well as the reinforcing effect can be achieved. Due to this electromagnetic shielding effect, both noise entering the mounted component from the outside and noise emerging from the mounted component to the outside can be reduced.

(5) In the wiring board having the above structure, the reinforcing member is desirably formed of a light shielding material.
Some mounted components, such as an IC chip, may break internal circuits when exposed to light exceeding a limit. If a light-shielding material is used as a reinforcing member for reinforcing the wiring board on which such a mounted component is mounted, it is possible to prevent the mounted component from being damaged by light.

(6) Next, the liquid crystal device according to the present invention comprises:
A liquid crystal device having a pair of substrates opposed to each other with a gap therebetween and liquid crystal sealed in the gap includes the wiring substrate according to any one of (1) to (5).

According to this liquid crystal device, by providing the reinforcing member around the mounting components constituting the wiring board having the two-layer structure, the mechanical strength of the wiring substrate around the mounting components can be increased. As a result, breakage of the wiring board can be reliably prevented. This means that the wiring board can be prevented from being damaged when the wiring board is assembled as one component of the liquid crystal device to another component.

(7) Next, the electronic device according to the present invention
The liquid crystal device having the above structure and a control unit for controlling the operation of the liquid crystal device are provided. According to this electronic device, since the reinforcing member is provided around the mounting component included in the wiring board of the two-layer structure constituting the liquid crystal device, the mechanical strength around the mounting component in the wiring substrate can be increased. As a result, damage to the wiring board can be reliably prevented. This means that the wiring board can be prevented from being damaged when the wiring board is assembled as one component of the liquid crystal device to another component.

[0024]

(First Embodiment) FIG. 1 shows an embodiment of a liquid crystal device using a wiring board according to the present invention. The liquid crystal device 4 shown here uses an ACF
(Anisotropic Conductive Film) 8 is attached to the liquid crystal panel 6 using an anisotropic conductive film.

The liquid crystal panel 6 has a pair of substrates 11a and 11b bonded to each other by a sealing material 9. These substrates are formed of a light-transmitting material such as glass, plastic, or the like. A polarizing plate 12 is attached to the outer surface of each of the substrates 11a and 11b, and if necessary, an illuminating device such as a backlight, a light reflecting member, or the like is provided corresponding to one of the substrates.

A minute gap, a so-called cell gap, is formed between the substrate 11a and the substrate 11b, and liquid crystal is sealed in the cell gap. A linear transparent electrode 13a is formed on the inner surface of the substrate 11a, and a linear electrode 13b orthogonal to the electrode 13a is formed on the inner surface of the substrate 11b. These electrodes 13a and 13b are, for example, I
It is formed by TO (Indium Tin Oxide: indium tin oxide). The electrode 13a and the electrode 13
The intersection with b constitutes one pixel for displaying an image.
In addition, the electrodes 13a and 13b are not limited to linear electrodes, and may have an appropriate pattern such as a mark or a pattern.

The substrate 11b has a projecting portion projecting outside the mating substrate 11a, and a plurality of substrate-side terminals 14 are formed on the surface of the projecting portion by ITO or the like. These substrate-side terminals 14 include those extending integrally from the electrode 13b and those connected to the electrode 13a via a conductive material.

The electrodes 13a and 13b and the substrate-side terminals 14 are actually provided on the substrate 11a at extremely small intervals.
It is formed on the upper side and on the substrate 11b. In FIG. 1, the interval between them is schematically shown in an enlarged manner for easy understanding of the structure. Also, the substrate side terminal 14 and the electrodes 13a, 13
The connection state with b is also omitted in FIG.

As shown in FIG. 8, the wiring board 7 is formed as a two-layer FPC (Flexible Printed Circuit) by directly forming the metal film pattern 2 on the base layer 1. The base layer 1 is formed of, for example, a PI (polyimide) film, and the metal film pattern 2 is formed of, for example, Cu. Also, metal film pattern 2
The output terminal 2a and the input terminal 2 shown in FIG.
b. Also, chip components 16 such as chip resistors and chip capacitors are mounted in appropriate places on the wiring board 7 as necessary.

A liquid crystal driving IC 17 as a mounting component is provided on the wiring board 7. More specifically, as shown in FIG. 2, the bump 18 of the liquid crystal driving IC 17 is conductively connected to the metal film pattern 2 on the base layer 1. In the embodiment shown in FIG. 2, the liquid crystal driving IC 17 is mounted on the wiring board 7 by gang bonding. That is, the bump 18 and the metal film pattern 2 are heated and pressed in a state where they are overlapped with each other, and they are joined by eutectic. An underfill adhesive 19 is filled in a joint portion between the two, and the underfill adhesive 19 is used for bonding the two and preventing rust.

The liquid crystal driving IC for the base layer 1
For mounting 17, any mounting method other than the gang bonding described above can be adopted. For example, ACF (Anisotropi
c Conductive Film).

In FIG. 1, the input terminal 2b and the liquid crystal driving I
An appropriate metal film pattern connecting the elements such as the C17, the output terminal 2a, and the chip component 16 is formed, but the metal film pattern is omitted in the figure.

When connecting the wiring board 7 to the overhang portion of the substrate 11b of the liquid crystal panel 6, first, an ACF (Anisotropic Conductive Filtration) is provided at the substrate side terminal 14 of the substrate 11b.
m) 8 is attached, and the portion of the output terminal 2a of the wiring board 7 is pressed thereon, and the portion is heated and pressurized, that is, crimped in this state. As a result, the wiring board side terminal 2a and the panel side terminal 14 are conductively connected by the conductive fine particles contained in the ACF 8, and the wiring board 7 and the board 11b are bonded by the adhesive portion of the ACF 8.

After the wiring board 7 is connected to the liquid crystal panel 6 and a predetermined signal for driving the liquid crystal is input to the input terminal 2b of the wiring board 7, the operation of the liquid crystal driving IC 17 causes the liquid crystal panel 6 to operate. A predetermined voltage is selectively applied to the electrodes 13a and 13b, whereby numbers and other images are displayed on the surface of the substrate 11a or 11b of the liquid crystal panel 6.

In this embodiment, a plate-like reinforcing member 22A having a hole 21 slightly larger than the liquid crystal driving IC 17 is provided.
And the reinforcing member 22A is placed on the base layer 1 with an adhesive or an adhesive so that the liquid crystal driving IC 17 fits into the hole 21. In the present embodiment, the liquid crystal driving IC
It is fixed on the base layer 1 on the same side as C17. 2 and 3 show a state in which the reinforcing member 22A is fixed in such a manner. (Similarly to the wiring board 7 of FIG. 1, on the base layer 1 of the wiring board 7, actually, the input terminal 2b,
Liquid crystal drive IC 17 and output terminal 2a and chip component 1
Although an appropriate metal film pattern connecting the elements such as 6 is formed, the metal film pattern is omitted in FIG. In a conventional wiring board having a structure in which the reinforcing member 22A is not provided, when the liquid crystal driving IC 17 which is a hard member is mounted on the soft base layer 1, a crack is formed around the liquid crystal driving IC 17. Therefore, the wiring board 7 is easily damaged from the liquid crystal driving IC 17. On the other hand, if the reinforcing member 22A is provided around the liquid crystal driving IC 17 as in the present embodiment, the mechanical strength of the portion is increased, and as a result, the occurrence of cracks in the portion is prevented. it can.

The reinforcing member 22A can be formed of any material capable of increasing the strength of the base layer 1, for example, the same PI (polyimide) film, metal foil, PET, , Other plastics.

(Second Embodiment) FIGS. 4 and 5 show another embodiment of the wiring board according to the present invention. The wiring board 27 shown here is provided with the metal film pattern 2 on the base layer 1.
2 and 3 are directly formed without using an adhesive layer.
This is the same as the case of the wiring board 7 shown in FIG.

In the wiring board 7 shown in FIGS. 2 and 3, a liquid crystal driving I
A reinforcing member 22A having a hole 21 for allowing C17 to escape is used.
Provided above. On the other hand, in the wiring board 27 of the present embodiment, a reinforcing member 22B having a uniform thickness without such an escape hole is prepared, and this is viewed from the liquid crystal driving IC 17 on the back side of the base layer 1. It is stuck to. As described above, even when the reinforcing member 22B is provided on the back surface side of the base layer 1, the strength of the wiring board 27 can be increased, and as a result, the damage of the wiring board 27 can be prevented.

Particularly, in the present embodiment, the liquid crystal driving IC 17
It is not necessary to form a hole for escape for the reinforcing member 22B, so that the strength of the wiring board around the liquid crystal driving IC 17 can be reduced as compared with the case where a reinforcing member having such a hole for escape is used. It can be even higher.

According to the experiment of the present invention, in FIG. 4, the extension length of the portion of the reinforcing member 22B that extends from the liquid crystal driving IC 17 is d, and the thickness of the base layer 1 and the metal film pattern 2 is When the total thickness is represented by t, it was found that by setting those dimensions as d ≧ t, it is possible to reliably prevent the wiring board 27 from being cracked.

(Third Embodiment) FIG. 6 shows still another embodiment of the wiring board according to the present invention. This wiring board 37 has a two-layer FP in which the metal film pattern 2 is formed directly on the base layer 1 without using an adhesive layer.
C is the wiring board 7 shown in FIG.
This is the same as the case of the wiring board 27 shown in FIG.

This wiring board 37 is different from the wiring board 7 shown in FIG. 3 in that the reinforcing member 22A is provided on the same side as the liquid crystal driving IC 17 with respect to the base layer 1 in the wiring board 7. In the wiring board 37, a reinforcing member 22C is provided on the back side of the liquid crystal driving IC 17 with respect to the base layer 1.

This wiring board 37 is different from the wiring board 27 shown in FIG. 5 in that the reinforcing member 2 is provided only around the liquid crystal driving IC 17 in the wiring board 27.
2B, the liquid crystal driving I
That is, the reinforcing member 22C is provided so as to correspond to both the C17 and the chip component 16. According to the present embodiment, the strength around the chip component 16 can also be increased by the reinforcing member 22C, so that the breakage of the wiring board 37 can be more reliably prevented.

(Fourth Embodiment) FIG. 7 shows a mobile phone as one embodiment of an electronic apparatus according to the present invention. The mobile phone 40 shown here has an antenna 41 and a speaker 4
2, liquid crystal device 4, key switch 43, microphone 44
And the like are stored in the outer case 46. Further, inside the outer case 46, a control circuit board 47 on which a control circuit for controlling the operation of each of the above-described components is provided. Liquid crystal device 4
Is constituted by the liquid crystal device 4 shown in FIG.

In this portable telephone 40, the key switch 4
A signal input through the microphone 3 and the microphone 44 and data received by the antenna 41 are input to the control circuit on the control circuit board 47. Then, the control circuit displays images such as numbers, characters, patterns, etc. on the display surface of the liquid crystal device 4 based on the various input data.
The transmission data is transmitted from the antenna 41.

The liquid crystal device 4 used in the portable telephone 40 is provided with a reinforcing member 22A around the liquid crystal driving IC 17 as shown in FIG. 1, or around the liquid crystal driving IC 17 as shown in FIG. Providing the reinforcing member 22B,
Alternatively, since the reinforcing member 22C is provided around the liquid crystal driving IC 17 and the chip component 16 as shown in FIG. 6, the strengths of the wiring board 7, the wiring board 27, and the wiring board 37 can be increased, respectively. Wiring board 7,
27 and 37 can be reliably prevented.

(Other Embodiments) The present invention has been described with reference to the preferred embodiments. However, the present invention is not limited to the embodiments, and various modifications may be made within the scope of the invention described in the claims. Can be modified.

For example, FIG. 1 shows a case where the wiring board according to the present invention is used as a component of a liquid crystal device. However, the wiring board according to the present invention can be used as a component of any device other than the liquid crystal device. it can.

Further, in the embodiment shown in FIG. 1, a liquid crystal device having a structure in which one wiring board is connected to a liquid crystal panel is exemplified. However, the present invention is applied to a liquid crystal device having a structure in which a plurality of wiring boards are connected to a liquid crystal panel. Of course, the invention can be applied.

Further, in the embodiment of FIG. 7, the case where the liquid crystal device of the present invention is used in a portable telephone as an electronic device is exemplified. However, the liquid crystal device of the present invention is not limited to other electronic devices, such as a portable information terminal and an electronic device. The present invention can also be applied to a notebook, a finder of a video camera, and the like.

[0051]

According to the wiring board, the liquid crystal device, and the electronic apparatus of the present invention, the mechanical strength around the mounted components in the wiring board having the two-layer structure is increased by the function of the reinforcing member. The breakage of the wiring board can be reliably prevented.

[Brief description of the drawings]

FIG. 1 is an exploded perspective view showing one embodiment of a liquid crystal device and a wiring board according to the present invention.

FIG. 2 is an enlarged cross-sectional view showing a cross-sectional structure of a main part of the wiring board shown in FIG.

FIG. 3 is a plan view of the wiring board of FIG. 2;

FIG. 4 is a sectional view showing another embodiment of the wiring board according to the present invention.

FIG. 5 is a plan view of the wiring board of FIG. 4;

FIG. 6 is a plan view showing still another embodiment of the wiring board according to the present invention.

FIG. 7 is a perspective view showing an embodiment of an electronic device according to the present invention.

FIG. 8 is a cross-sectional view schematically showing a two-layer FPC which is a main part of the wiring board according to the present invention.

FIG. 9 shows a three-layer FPC which is a main part of a conventional wiring board.
It is sectional drawing which shows typically.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Base layer 2 Metal film pattern 2a Output side terminal 2b Input side terminal 3 Two-layer FPC 4 Liquid crystal device 6 Liquid crystal panel 7 Wiring board 8 ACF 11a, 11b substrate 13a, 13b Electrode 14 Substrate side terminal 16 Chip component (mounting component) 17) IC for driving liquid crystal (mounting component) 21 hole 22A, 22B, 22C Reinforcing member 27 wiring board 37 wiring board

Claims (7)

[Claims] In a wiring board having a base layer, a metal film pattern formed directly on the base layer, and a mounted component mounted on the base layer, a reinforcing member is provided around the mounted component. A wiring board, comprising: 2. The wiring board according to claim 1, wherein the reinforcing member is provided on a back surface side of the base layer as viewed from the mounted component. 3. The thickness according to claim 1, wherein the extension length of a portion of the reinforcing member projecting from the mounting component is d, and the thickness of the base layer and the metal film pattern is totaled. Where d is t ≧ t. 4. The wiring board according to claim 1, wherein the reinforcing member is formed of a conductive material. 5. The wiring board according to claim 1, wherein the reinforcing member is formed of a light shielding material. 6. A liquid crystal device having a pair of substrates facing each other with a gap therebetween and a liquid crystal sealed in the gap.
A liquid crystal device comprising the wiring substrate described in any one of the above. 7. An electronic apparatus, comprising: the liquid crystal device according to claim 6; and a control unit that controls an operation of the liquid crystal device.