JP2003140176A - Liquid crystal display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a liquid crystal display device in which conduction failure caused by the insufficient amount of printing of solder paste is reduced while soldering chip parts to a circuit board. SOLUTION: The liquid crystal display device is provided with a circuit board to which chip parts having a plurality of pair electrodes on both ends are to be packaged and a circuit board to which the plurality of pair electrodes of the chip parts are to be soldered and which has a plurality pair of pad electrodes. Then, if W11 is the electrode width of the electrode pair located at the outermost side of the chip part, W12 is the electrode width of the electrode pairs other than the outermost side of the chip part, W21 is the electrode width of the portion which overlaps with the chip part in the pad electrode pair of the outermost side, W22 is the electrode width of the portion which does not overlap with the chip part, W31 is the electrode width of the portion which overlaps with the chip parts in the pad electrode pair other than the outermost side and W32 is the electrode width of the portion which does not overlap with the chip part, W21>=W11, W31>=W12, W21>W22 and W31<W32 are satisfied.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal display device used in personal computers, workstations, etc., and is particularly applied to productivity improvement of a circuit board used in a liquid crystal display device and productivity. And about effective technology.

[0002]

2. Description of the Related Art A liquid crystal display module of STN (Super Twisted Nematic) system or TFT (Thin Film Transistor) is widely used as a display device for notebook personal computers and the like. These liquid crystal display modules are
It is composed of a liquid crystal display panel around which a drive circuit unit is arranged and a backlight for irradiating the liquid crystal display panel. Further, these liquid crystal display modules include a circuit board (TCON board) on which a display control device for controlling and driving the drive circuit section of the liquid crystal display panel is mounted. Note that such a technique is disclosed in, for example, Japanese Patent Laid-Open No. 25714/1993.
No. 2 publication.

[0003]

As described above, the liquid crystal display module includes the circuit board on which the display control device for controlling and driving the drive circuit section of the liquid crystal display panel is mounted. The substrate includes, for example, a resistance element,
Chip parts such as capacitors are soldered. A solder (Sn-37Pb) containing lead (Pb) has been used for soldering this chip component.
On the other hand, in view of environmental problems, it is required to use a lead (Pb) -free solder instead of the lead (Pb) -containing solder. However, conventional solder (Sn-37
When lead-free (Pb) -free Pb-free solder (for example, Sn-8Zn-3Bi) is used in place of Pb), when soldering a chip component to a circuit board, conduction due to insufficient printing amount of solder paste occurs. There was a problem that defects frequently occurred. The present invention has been made to solve the above-mentioned problems of the prior art, and an object of the present invention is to provide an insufficient printing amount of solder paste when soldering a chip component to a circuit board in a liquid crystal display device. An object of the present invention is to provide a technique capable of reducing the conduction failure associated with the above. The above and other objects and novel features of the present invention will become apparent from the above description of the present specification and the accompanying drawings.

[0004]

Among the inventions disclosed in the present application, a brief description will be given to the outline of typical ones.
It is as follows. According to the present invention, a liquid crystal display panel having two substrates arranged to face each other and a liquid crystal layer sandwiched between the two substrates, and a chip component having a plurality of pairs of electrodes at both ends are mounted. And a circuit board having a plurality of pairs of pad electrodes to which a plurality of pairs of electrodes of the chip component are soldered. Here, the chip component has four pairs of electrodes on both sides, and the electrode widths of the two outermost electrode pairs are made wider than the electrode widths of the two inner electrode pairs. In the present invention, the electrode width of the outermost electrode pair of the chip component is W11, the electrode width of the electrode pair other than the outermost electrode pair of the chip component is W12, and the pad to which the outermost electrode pair of the chip component is soldered The electrode width of the portion of the electrode pair that overlaps with the chip component is W2.
1. Set the electrode width of the part that does not overlap with the chip component to W2
2. When the electrode width of the pad electrode pair to which the electrode pair other than the outermost side of the chip component is soldered is W31, and the electrode width of the portion not overlapping the chip component is W32, W21 is W21. ≧ W11, W31 ≧
It is characterized in that W12, W21> W22 and W31 <W32 are satisfied.

Further, in the present invention, the pad electrode width of the portion of each of the pad electrode pairs which overlaps with the chip component is
The area of the pad electrode of a portion which is equal to or larger than the electrode width of each electrode pair of the chip component to be soldered to each pad electrode pair and which overlaps with the chip component in each pad electrode pair, and the area of the pad electrode which does not overlap with the chip component It is characterized in that the sum of the area of the pad electrodes of a part is constant for each pad electrode pair. Further, in the present invention, each pad electrode pair is arranged at a constant interval from an adjacent pad electrode. Further, in the present invention, the electrode pair of the chip component and each pad electrode pair are soldered with Pb-free solder. According to the above-described means, it is possible to reduce mounting defects due to insufficient application of the solder paste during printing without increasing the area occupied by the pad electrodes on the circuit board.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In all the drawings for explaining the embodiments, the same reference numerals are given to those having the same function, and the repeated description thereof will be omitted. First Embodiment <Basic Configuration of TFT Type Liquid Crystal Display Module to which the Present Invention is Applied> FIG. 1 is an exploded perspective view showing a schematic configuration of a TFT type liquid crystal display module (LCM) to which the present invention is applied. Is. Liquid crystal display module (LCM) shown in FIG.
Is composed of a frame-shaped frame 4 made of a metal plate, a liquid crystal display panel 5, and a backlight. Liquid crystal display panel 5
Are a TFT substrate in which pixel electrodes, thin film transistors, etc. are formed on a transparent insulating substrate (eg, glass), and a filter substrate in which counter electrodes, color filters, etc. are formed on a transparent insulating substrate (eg, glass). Are overlapped with each other with a predetermined gap, and both substrates are bonded together by a seal material provided in the shape of a frame in the vicinity of the peripheral portion between the both substrates, and both substrates are inserted from a liquid crystal sealing port provided in a part of the seal material. Liquid crystal is enclosed and sealed inside the sealing material between them, and polarizing plates are attached to the outside of both substrates.

Here, on the glass substrate of the TFT substrate,
A plurality of drain drivers and gate drivers composed of a semiconductor integrated circuit device (IC) are mounted. The drain driver is supplied with drive power, display data and control signals via the flexible printed wiring board 1, and the gate driver is supplied with drive power and control signals via the flexible printed wiring board 2. . These flexible printed wiring boards (1, 2)
Is connected to a circuit board 3 provided on the back side of the backlight. On the circuit board 3, chip components such as a semiconductor chip, a resistance element, and a capacitance element that form a timing controller are mounted. The backlight of the liquid crystal display module shown in FIG. 1 includes a cold cathode fluorescent lamp 16, a wedge-shaped (side surface is trapezoidal) light guide 9, a diffusion sheet (6, 8), a lens sheet 7, and a reflection sheet 10. In the order shown in FIG. 1, it has a side wall and is fitted in a frame-shaped mold 14. In FIG. 1, 11 is a rubber bush,
12 is a connector and 18 and 19 are cables. The liquid crystal display module shown in FIG. 1 has a liquid crystal display panel 5 in which a plurality of drain drivers and gate drivers are mounted.
Is housed between a frame 4 having a display window and a backlight. Further, as shown in FIG. 1, the circuit board 3 is arranged behind the backlight.

FIG. 2 is a plan view showing an example of the circuit board 3 shown in FIG. As shown in FIG. 2, the circuit board 3 includes a display controller (timing controller) 110 for controlling and driving the drain driver and the gate driver.
Is mounted and, for example, a chip component (CHP) such as a resistance element and a capacitance element is soldered. In FIG. 2, a chip part (hereinafter, referred to as a four-chip chip resistance part) 21 having four resistance elements mounted therein, which is shown in FIG. 3, is soldered to the circled part. The quadruple chip resistor component 21 has electrode pairs (22-
25). Here, as shown in FIG. 4, each electrode pair (22 to 25) is formed such that the gap length (G11) between adjacent electrode pairs is constant, and
The electrode width of the two outermost electrode pairs (22, 25) (W1
1) is formed wider than the electrode width (W12) of the two inner electrode pairs (23, 24). The size of the quadruple chip resistor component 21 is, for example, the length in the long side direction (see FIG.
L11) is 1.9 mm, and the length in the short side direction (L1 in FIG. 4)
2) is 1.0 mm, and the electrode width (W11) is 0.35
mm, the electrode width (W12) is 0.3 mm, and the gap (G11) between adjacent electrode pairs is 0.2 mm.

<Characteristics of TFT type liquid crystal display module of this embodiment> FIG. 5 shows a circuit board 3 to which the quadruple chip resistor component 21 shown in FIGS. 3 and 4 is soldered in this embodiment. It is a figure which shows the electrode shape of a pad electrode pair. As shown in FIG. 5, the pad electrode pairs (32 to 35) of the circuit board 3 to which the quadruple chip resistor component 21 is soldered
Is the gap length between adjacent pad electrode pairs (G2
1) is constant and at a constant interval (G22)
, And each pad electrode pair (32-3
5) is formed such that the electrode width of the portion where the 4-chip chip resistor component 21 is mounted is different from the electrode width of the portion where the 4-chip chip resistor component 21 is not mounted. In this case, the two outermost pad electrode pairs (32, 35) have an electrode width (W21) of a portion where the quadruple chip resistor component 21 is mounted,
The inner two pad electrode pairs (33, 34) are formed wider than the electrode width (W22) of the part where the quadruple chip resistor component 21 is not mounted, and the two inner pad electrode pairs (33, 34) are electrodes of the part where the quadruple chip resistor component 21 is mounted. The width (W31) is formed narrower than the electrode width (W32) of the portion where the quadruple chip resistor component 21 is not mounted.

The pad electrode pair (32
The reason why ~ 35) has the above-described shape will be described later. The pad electrode pairs (32 to 35) are dimensioned, for example, such that the outermost two pad electrode pairs (32, 35) have an electrode width (W21) of 0.4 mm and the outermost two pad electrode pairs (32 to 35). 32, 35) electrode width (W22) is 0.35 mm,
The electrode width (W of the two inner pad electrode pairs (33, 34)
31) is 0.3 mm, and the inner two pad electrode pairs (3
3, 34) has an electrode width (W32) of 0.35 mm.
In addition, the gap length between adjacent pad electrode pairs (G2
1) is 0.2 mm, and the distance (G22) between each pad electrode pair is 0.3 mm, the length of the pad electrode pair (32 to 35) in the long side direction (L21 in FIG. 5) is 2 0.0 m
m, and the length in the short side direction (L22 in FIG. 4) is 1.7 mm. In FIG. 5, L23 indicates a portion on which the 4-chip chip resistor component 21 is mounted, and L23 is 1.0 m.
m, and L24 indicates a portion where the quadruple chip resistor component 21 is not mounted, and this L24 is 0.35 mm.

FIG. 8 is a diagram showing the shape of the pad electrode pair of the circuit board 3 to which the quadruple chip resistor component 21 shown in FIGS. 3 and 4 is soldered in the conventional liquid crystal display module. As shown in FIG. 8, in the circuit board 3 of the conventional liquid crystal display module, the pad electrode pairs (42 to 45) are arranged such that the gap length (G21) between adjacent pad electrode pairs is constant, and , Which are formed at a constant interval (G22), each pad electrode pair (4
2 to 45) are formed such that the electrode width of the portion where the 4-chip chip resistance component 21 is mounted is the same as the electrode width of the portion where the 4-chip chip resistance component 21 is not mounted. The size of the pad electrode pair (42 to 45) is, for example, the length of each electrode (L33 in FIG. 8) is 0.7 mm, and the outermost 2
The electrode width (W5) of each pad electrode pair (42, 45) is 0.4 mm, and the inner two pad electrode pairs (43, 44)
Has an electrode width (W6) of 0.3 mm, a gap length (G21) between adjacent pad electrode pairs is 0.2 mm, and an interval (G22) between each pad electrode pair is 0.3 mm. Further, in the entire pad electrode pair (42 to 45), the length in the long side direction (L31 in FIG. 8) is 2.0 mm, and the length in the short side direction (L32 in FIG. 4) is 1.7 mm. The area occupied by the pad electrode pair in the circuit board is the same in both the liquid crystal display module of this embodiment and the conventional liquid crystal display module.

In the structure of the pad electrode pair (42 to 45) of the conventional circuit board 3 as described above, as described in the above-mentioned "Problems to be solved by the invention", the conventional solder (Sn-3) is used.
7Pb) instead of lead (Pb) -free Pb-free solder (for example, Sn-8Zn-3Bi),
There has been a problem that defective soldering of the quadruple chip resistor component 21 frequently occurs. Hereinafter, this four-series chip resistor component 21
The cause of defective soldering will be described. Sn-
The 8Zn-3Bi solder paste has a defect that the solder itself is easily oxidized, and the wet spread of the solder is poor. Therefore, when the solder paste is printed imperfectly during solder paste printing, poor connection is likely to occur, and the flux is also designed with an emphasis on improving wettability. Therefore, the current Sn-Pb solder is used. Compared with the paste, there is a drawback that the viscosity is likely to increase during use.

As described above, when the Sn-8Zn-3Bi solder paste is used for a long time, the viscosity rises, and when the viscosity rises, the solder paste does not sufficiently wrap around the end face of the fine opening of the solder printing mask, The amount of paste applied tends to be insufficient, and when the viscosity increases, the adhesive strength with the circuit board 3 becomes insufficient, causing a printing failure in which no solder paste is attached to the circuit board.
Therefore, in the circuit board 3 of the conventional liquid crystal display module, when Sn-8Zn-3Bi solder paste is placed in the printing machine and the solder paste is printed on each pad electrode pair (42 to 45) continuously for several hours, The viscosity of the solder paste rises, the solder paste is blurred, and the amount of the solder paste printed is insufficient, so that defective printing frequently occurs on the pad electrode pair (43, 44) inside the circuit board 3. That is, as shown in (a) of FIG. 9, printing failure in which the solder paste does not adhere to the pad electrode, or as shown in (b) of FIG. 9, the amount of the solder paste applied to the pad electrode is insufficient. When the 4-chip chip resistance component 21 is soldered in this state, the solder paste does not adhere to the pad electrode and the conduction failure due to the printing failure or the failure of printing in FIG. As shown in (b), due to the insufficient amount of the solder paste applied to the pad electrodes, conduction failure frequently occurs because the solder does not adhere to the component electrodes.

When the solder paste is printed on the inner pad electrode pair (43, 44), the opening dimension of the fine opening portion of the solder printing mask is 0.3 × 0.7 mm. As the opening dimension of the fine opening portion, if the dimension in the lateral direction of 0.3 mm is enlarged to 0.35 mm, printing failure will be eliminated and printability can be improved. However, if the opening size of the fine opening part of the solder printing mask is enlarged with the conventional electrode size unchanged,
The solder coating amount becomes excessive, and the occurrence rate of short-circuit defects increases between the adjacent pad electrode pairs having good printability at the beginning of use. In order to change the circuit board 3 into the same shape as the opening size of the fine opening portion of the solder printing mask without increasing the occupied area of the pad electrode pair, it is necessary to reduce the gap length (G11) between the pad electrode pairs. However, in this case, a short circuit between adjacent pad electrode pairs is likely to occur.

Therefore, in order to reduce printing defects of the Sn-8Zn-3Bi solder paste without increasing the area occupied by the pad electrode pairs on the circuit board 3 and preventing short-circuit defects between adjacent pad electrodes, The electrode width of the pad electrode pair is widened so that the fine openings for printing the solder pace on the four inner pad electrode pairs in the solder printing mask are made thicker, and conversely, the outer pad electrode having a slightly larger area is formed. It is better to narrow the electrode width of the pair and reduce the area of the outer pad electrode pair. On the other hand, the bottom surface of the electrode pair (22 to 25) of the 4-chip chip resistor component 21 and the circuit board 3
The solder paste printed on the overlapping portion of the pad electrode pair of No. 2 has a role of fixing the quadruple chip resistor component 21 and the circuit board 3 to each other. ~ 25) bottom surface and the circuit board 3
If the area overlapping with the pad electrode pair is reduced, chip standing defects and component misalignment defects frequently occur. Therefore, in the pad electrode pair of the circuit board 3, the pad electrode width in the vicinity of the side surface of the quadruple chip resistance component 21 is equal to or larger than the electrode width of the quadruple chip resistance component 21 to secure the overlapping portion. Better

For the above reason, in the pad electrode pair of the circuit board 3, the electrode pair (22
The electrode width of the part that overlaps with the bottom surface of
The width of the electrode pair (22 to 25) of the quadruple chip resistance component 21 is equal to or larger than the electrode width and does not overlap with the bottom surface of the electrode pair (22 to 25) of the quadruple chip resistance component 21. As for the area, the sum of the area of the area overlapping the bottom surface of the electrode pair (22 to 25) of the quadruple chip resistor component 21 while maintaining the gap length (G21) between the adjacent pad electrodes is the pad electrode. If the electrode area of the pad electrode pair is adjusted so that the pair becomes constant,
Prevents printing defects of Sn-8Zn-3Bi solder paste,
From the viewpoint of chip standing failure, mounting misalignment failure, reduction of the occupied area of the pad electrode area on the printed circuit board, and prevention of short circuit between adjacent electrodes, the pad electrode structure is the most unlikely to cause mounting failure. The present embodiment is characterized in that the electrode shape of the pad electrode pair (42 to 45) is changed to the shape shown in FIG. 5 described above based on the above findings. Accordingly, in the present embodiment, the Sn-8Zn-3Bi solder paste is installed in the printing machine, and the solder paste is printed on each pad electrode pair (42 to 45) continuously for a long time. Even if the viscosity of the solder paste is increased, as shown in FIG. 6, it is possible to prevent printing defects in which the solder paste does not adhere to the pad electrodes or printing defects in which the amount of the solder paste applied to the pad electrodes is insufficient. It becomes possible.

That is, in the present embodiment, the S
Even if the n-8Zn-3Bi solder paste is installed and the solder paste is printed on each pad electrode pair (42 to 45) continuously for a long period of time, the solder paste does not reach the pad electrode pairs (42 to 45) to some extent. As a result, as shown in FIG. 7, each pad electrode pair (42-4
It is possible to reduce the occurrence of conduction failure in the 4-chip resistor component 21 soldered to 5). As described above, according to the present embodiment, when soldering the chip component to the circuit board 3, it is possible to reduce the conduction failure due to the insufficient printing amount of the solder paste. As a result, in the present embodiment, the productivity and the production capacity of the circuit board 3 which is a component of the liquid crystal display module can be improved, and the manufacturing cost can be reduced. In each of the above-described embodiments, an embodiment in which the present invention is applied to a TFT type liquid crystal display module has been mainly described, but the present invention is not limited to this, and the present invention is not limited to the STN type. It goes without saying that it is also applicable to liquid crystal display modules. Although the invention made by the present inventor has been specifically described based on the above-described embodiment, the present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the scope of the invention. Of course,

[0018]

The effects obtained by the typical ones of the inventions disclosed in the present application will be briefly described as follows. (1) According to the liquid crystal display device of the present invention, when soldering a chip component to a circuit board, it is possible to reduce conduction defects due to insufficient print amount of solder paste. (2) According to the liquid crystal display device of the present invention, the productivity and the production capacity of the circuit board, which is a component of the liquid crystal display device, can be improved, and the manufacturing cost can be reduced.

[Brief description of drawings]

FIG. 1 is an exploded perspective view showing a schematic configuration of a TFT type liquid crystal display module (LCM) to which the present invention is applied.

FIG. 2 is a plan view showing an example of the circuit board shown in FIG.

FIG. 3 is a perspective view showing a schematic configuration of a quadruple chip resistor component soldered to a circled portion of FIG.

FIG. 4 is a diagram for explaining an electrode shape of the quadruple chip resistor component shown in FIG.

FIG. 5 is a diagram showing an electrode shape of a pad electrode pair of a circuit board to which the quadruple chip resistor component shown in FIGS. 3 and 4 is soldered in the liquid crystal display module according to the embodiment of the present invention.

FIG. 6 is a view for explaining the solder paste printed on the pad electrode after the solder paste is continuously printed on the pad electrode of the circuit board for 2 hours in the liquid crystal display module according to the embodiment of the present invention. It is a figure.

FIG. 7 is a diagram for explaining a state in which quadruple chip resistor components are soldered in the state shown in FIG.

FIG. 8 is a diagram showing an electrode shape of a pad electrode pair of a circuit board to which the 4-chip chip resistance component shown in FIGS. 3 and 4 is soldered in the conventional liquid crystal display module.

FIG. 9 is a diagram illustrating a solder paste printed on a pad electrode of a conventional liquid crystal display module after the solder paste is continuously printed on the pad electrode of a circuit board for 2 hours.

FIG. 10 is a diagram for explaining a state in which a quadruple chip resistor component is soldered in the state shown in FIG.

[Explanation of symbols]

1, 2 ... Flexible printed wiring board, 3 ... Circuit board, 4 ... Frame, 5 ... Liquid crystal display panel, 6, 8 ... Diffusion sheet, 7 ... Lens sheet, 9 ... Light guide body, 10 ... Reflection sheet, 11 ... Rubber Bush, 12 ... Connector, 13 ... Inserter, 14 ... Mold, 16 ... Cold cathode fluorescent lamp, 1
8, 19 ... Cables, 21 ... 4-chip resistor parts, 22
-25 ... Electrode pairs of 4-chip chip resistance component 21, 32-3
5, 42 to 45 ... Pad electrode pair, 110 ... Display control device, CHP ... Chip component.

   ─────────────────────────────────────────────────── ─── Continued front page    F-term (reference) 2H092 GA32 GA37 GA40 GA45 GA46                       GA53 GA59 GA60 JB21 JB23                       JB26 NA11 NA15 NA16 NA18                       NA29 NA30 PA01 PA06                 5C094 AA32 AA42 AA43 BA43 DB01                       GB10 HA08                 5E319 AA03 AB06 AC01 AC03 AC11                       BB01 BB05 GG05                 5G435 AA17 BB12 EE40 EE43 EE47                       KK05 KK09 LL08

Claims (5)

[Claims] 1. A liquid crystal display panel having two substrates arranged to face each other and a liquid crystal layer sandwiched between the two substrates, and a chip component having a plurality of pairs of electrodes at both ends. A liquid crystal display device having a plurality of pairs of pad electrodes to which a plurality of pairs of electrodes of the chip component are soldered, wherein the circuit substrate is an electrode of an outermost electrode pair of the chip component. The width is W11, the electrode width of the electrode pair other than the outermost part of the chip component is W12,
The electrode width of the pad electrode pair to which the outermost electrode pair of the chip component is soldered is W21, the electrode width of the portion that does not overlap the chip component is W22, and other than the outermost side of the chip component. When the electrode width of the pad electrode pair to which the electrode pair is soldered is W31 and the electrode width of the portion that does not overlap the chip component is W32, W21 ≧ W11, W3
A liquid crystal display device satisfying 1 ≧ W12, W21> W22, and W31 <W32. 2. A liquid crystal display panel having two substrates arranged to face each other and a liquid crystal layer sandwiched between the two substrates, and a chip component having a plurality of pairs of electrodes at both ends is mounted. And a circuit board, wherein the circuit board is a liquid crystal display device having a plurality of pairs of pad electrodes to which a plurality of pairs of electrodes of the chip component are soldered, and the chip component in each of the pad electrode pairs. The pad electrode width of the overlapping portion is not less than the electrode width of each electrode pair of the chip component soldered to each pad electrode pair, and,
It is characterized in that the sum of the area of the pad electrode of the portion of the pad electrode pair that overlaps the chip component and the area of the pad electrode of the portion that does not overlap the chip component is constant for each pad electrode pair. Liquid crystal display device. 3. The liquid crystal display device according to claim 1, wherein each pad electrode pair is arranged at a constant interval from an adjacent pad electrode. 4. The electrode pair of the chip component and each pad electrode pair are soldered with Pb-free solder.
The liquid crystal display device according to item. 5. The chip component has four pairs of electrodes on both sides, and the outermost two electrode pairs have a wider electrode width than the inner two electrode pairs. The liquid crystal display device according to any one of claims 1 to 4.