JP4112580B2 - Liquid crystal display - Google Patents

Description

  The present invention relates to a liquid crystal display device, for example, an active matrix type liquid crystal display device.

An active matrix type liquid crystal display device includes: a gate signal line extending in the x direction and arranged in parallel in the y direction on a liquid crystal side surface of one of the transparent substrates opposed to each other through the liquid crystal; Drain signal lines extending in the y direction and juxtaposed in the x direction are formed, and a rectangular region surrounded by these signal lines is defined as a pixel region.
Each of these pixel regions is arranged in a matrix, and a set of them constitutes a liquid crystal display unit.

In each pixel region, a switching element that is operated by a scanning signal from a gate signal line on one side and a pixel electrode that is supplied with a video signal from a drain signal line on one side through the switching element are formed. .
The pixel electrode is configured to generate an electric field with the counter electrode formed on one of the transparent substrates, and to control the light transmittance of the liquid crystal by this electric field.

Further, the scanning signal driving to each gate signal line and the video signal to each drain signal line are respectively connected to each gate signal line and each drain signal line extending to the outside of the liquid crystal display area. It is supplied from a circuit and a video signal driving circuit.
In the case of a scanning signal driving circuit or a video signal driving circuit, there are a plurality of them, and each gate signal or drain signal line is grouped by adjacent ones, and each group has one scanning signal driving circuit or video signal. The signal drive circuit is in charge.

In addition, these drive circuits consist of a semiconductor device formed by a so-called tape carrier system, and a semiconductor chip is mounted on a film-like substrate, and each wiring layer connected to each bump of the semiconductor chip extends over the substrate surface. In some cases, the extending ends are connected to terminals on opposite sides.
In this semiconductor device, solder is used to connect the input side terminal and the printed circuit board terminal, and the output side terminal and the liquid crystal display panel terminal are connected via a so-called anisotropic conductive film. It was.

However, as the number of terminals on the input side and the number of terminals on the output side of the liquid crystal display device have increased in recent years, the number of terminals on the semiconductor device and the printed circuit board has increased. It has been pointed out that inconveniences such as shorting between adjacent terminals occur in connection.
The present invention has been made based on such circumstances, and an object of the present invention is to provide a liquid crystal display device capable of reliable connection between a semiconductor device and a printed board.

Of the inventions disclosed in the present invention, the outline of typical ones will be briefly described as follows.
The liquid crystal display device according to the present invention includes, for example, a liquid crystal display panel, a printed circuit board disposed in the vicinity of the liquid crystal display panel, and a film carrier system disposed between the liquid crystal display panel and the printed circuit board. And connecting each terminal of the semiconductor device and each terminal on a printed circuit board opposed to each terminal through an anisotropic conductive film. To do.
Even if the number of terminals on the input side of the semiconductor device increases and the pitch becomes narrow, the liquid crystal display device configured in this way is short-circuited between adjacent terminals in the connection between the terminals and the terminals of the printed circuit board. Can prevent you from doing.
The diameter of the conductive beads mixed in the anisotropic conductive film is small, and when the semiconductor device is thermocompression bonded to the printed circuit board via the anisotropic conductive film, the conductive beads are arranged adjacent to each other. This is because each terminal to be connected is not electrically connected.
On the other hand, when each terminal of the semiconductor device and the printed board is connected by solder, the solder spreads in the horizontal direction when the semiconductor device is thermocompression bonded to the printed board. This leads to a short circuit of each terminal.

  As is apparent from the above description, according to the liquid crystal display device of the present invention, a reliable connection between the semiconductor device and the printed circuit board can be achieved.

Hereinafter, embodiments of a liquid crystal display device according to the present invention will be described with reference to the drawings.
Example 1.
<< Equivalent circuit >>
FIG. 2 is an equivalent circuit diagram showing an embodiment of the liquid crystal display device according to the present invention. Although this figure is a circuit diagram, it is drawn corresponding to the actual geometric arrangement.
In the figure, there is a transparent substrate SUB1, and this transparent substrate SUB1 is arranged to face another transparent substrate SUB2 via a liquid crystal.

  On the surface of the transparent substrate SUB1 on the liquid crystal side, a gate signal line GL extending in the x direction in the drawing and arranged in parallel in the y direction, and insulated from the gate signal line GL and extending in the y direction, x The drain signal lines DL arranged in parallel to each other are formed, and a rectangular region surrounded by these signal lines becomes a pixel region, and a set of these pixel regions constitutes the liquid crystal display portion AR. .

  Each pixel region is supplied with a thin film transistor TFT driven by supply of a scanning signal (voltage) from a gate signal line GL on one side, and a video signal (voltage) from a drain signal line DL on one side through the thin film transistor TFT. A pixel electrode PX is formed.

  In addition, a capacitive element Cstg is formed between the pixel electrode PX, the one-side gate signal line GL, and a counter voltage signal line CL described later. When the thin film transistor TFT is turned off by the capacitive element Cstg, the pixel electrode The video signal supplied to is stored for a long time.

  The pixel electrode PX in each pixel region generates an electric field between the pixel electrode PX and the counter electrode CT disposed adjacent to the pixel electrode PX, and liquid crystal is generated by an electric field having a component substantially parallel to the transparent substrate SUB1 in the electric field. The light transmittance is controlled.

  One end of each gate signal line GL extends to one side (left side in the figure) of the transparent substrate SUB1 beyond the liquid crystal display part AR, and the terminal GTM which is the extension part has an output terminal of the vertical scanning drive circuit V. To be connected.

  Further, one end of each drain signal line DL is also extended to one side (upper side in the drawing) of the transparent substrate SUB1 beyond the liquid crystal display part AR, and the terminal that is the extended part is an output terminal of the video signal drive circuit He. To be connected.

  A plurality of vertical scanning drive circuits V are arranged in the y direction in the drawing, and each gate signal line GL is grouped by adjacent ones, and one gate signal line GL is provided for each grouped predetermined number of gate signal lines GL. The vertical scanning drive circuit V is assigned.

  Similarly, a plurality of video signal drive circuits He are also arranged in the x direction in the figure, and each drain signal line DL is grouped adjacent to each other, and a predetermined number of these drain signal lines DL are grouped. One video signal drive circuit He is assigned.

FIG. 1 is a plan view showing details of the video signal driving circuit He, for example, and shows two video signal driving circuits He arranged in parallel.
Here, the video signal drive circuit He is composed of a semiconductor device manufactured by a so-called film carrier system, and a semiconductor chip IC is mounted on a film-like substrate SUB0, and its input bumps and output bumps extend over the substrate surface SUB0. They are led out to the input terminal IT and the output terminal OT through the formed wiring layer WL.

The input terminal IT is formed side by side along one side of the substrate SUB0, and the output terminal OT is formed side by side along the other side opposite to the one side of the substrate SUB0.
The number of the input terminals IT is smaller than that of the output terminals OT, and accordingly the terminal width is slightly larger than that of the output terminal OT.

  The video signal driving circuit He configured as described above has its output terminal OT connected to the corresponding terminal DTM of each drain signal line DL via the anisotropic conductive film ACF, and its input terminal IT is also a liquid crystal. Arranged close to the display panel PNL (in this specification, each of the transparent substrates SUB1 and SUB2 arranged with liquid crystal interposed therebetween and a material layer formed on the substrate surface is referred to as a liquid crystal display panel). The corresponding terminals of the printed circuit board are connected via the anisotropic conductive film ACF.

  The printed circuit board PCB is mounted with a circuit for driving the video signal driving circuit He, and a signal including a power source is input to the video signal driving circuit He through the printed circuit board PCB.

Here, the anisotropic conductive film ACF is made of a resin film mixed with a large number of fine conductive beads, and the video signal driving circuit He is positioned with respect to the printed circuit board PCB, for example, via the anisotropic conductive film ACF. The terminals facing each other are electrically connected through the conductive beads by thermocompression bonding.
Also, the vertical scanning drive circuit V has the same configuration as that described above, except that the circuit configuration of the semiconductor chip is different.

<Pixel configuration>
FIG. 3 is a plan view showing one embodiment of a pixel of the liquid crystal display device according to the present invention. 4 is a sectional view taken along line IV-IV in FIG.
FIG. 3 is a configuration diagram of one pixel in a surface on the liquid crystal side of one transparent substrate SUB1 among the transparent substrates arranged to face each other through the liquid crystal, and each pixel is arranged in a matrix. For this reason, the other pixels positioned vertically or horizontally with respect to the pixels in FIG.

First, a gate signal line GL extending in the x direction in the drawing is formed on the surface of the transparent substrate SUB1 and below the pixel region.
The gate signal line GL includes a gate signal line (not shown) corresponding to the pixel region positioned above the pixel region, a drain signal line DL described later, and a drain corresponding to the pixel region positioned on the right side of the pixel region. It is formed so as to surround the pixel region together with the signal line.

  Further, a counter voltage signal line CL extending in the x direction in the drawing is formed in the center of the pixel region. The counter voltage signal line CL is formed, for example, in the same process as the gate signal line GL. In this case, the material of the counter voltage signal line CL is the same as that of the gate signal line GL. become.

The counter voltage signal line CL is formed integrally with the counter electrode CT. The counter electrode CT extends in the vertical direction (y direction in the figure) with the counter voltage signal line CL in between, and is arranged in parallel in the x direction. A plurality are formed.
Each counter electrode CT is formed in a zigzag shape in the extending direction, which will be described in detail later in relation to the pixel electrode PX.

  Thus, the surface of the transparent substrate SUB1 on which the gate signal line GL and the counter voltage signal line CL (counter electrode CT) are formed is covered with the gate signal line GL and the counter voltage signal line CL (counter electrode CT). An insulating film GI made of SiN or the like is formed.

  This insulating film GI functions as an interlayer insulating film with the drain signal line DL described later for the gate signal line GL and the counter voltage signal line CL, and as a gate insulating film for the thin film transistor TFT described later. This function has a function as a dielectric film for a capacitive element Cstg described later.

A semiconductor layer AS made of, for example, amorphous Si (a-Si) is formed on the upper surface of the insulating film GI and in a portion overlapping the gate signal line.
The semiconductor layer AS becomes a semiconductor layer of the thin film transistor TFT, and by forming the drain electrode SD2 and the source electrode SD1 on the upper surface, an inverted staggered MIS transistor having a part of the gate signal line GL as a gate electrode is formed. It has become so.
Here, the drain electrode SD2 and the source electrode SD1 are formed simultaneously with the drain signal line DL, for example.

  That is, a drain signal line DL extending in the y direction in the figure is formed. At this time, a part of the drain signal line DL extends to the upper surface of the semiconductor layer AS, thereby forming a drain electrode SD2. A source electrode SD1 is formed in a portion separated by a distance corresponding to the channel length of the thin film transistor TFT.

  Here, since the source electrode SD1 is connected to the pixel electrode PX via a protective film PSV, which will be described later, the contact portion CN is formed so as to extend slightly to the center side of the pixel region. It has become so.

  Thus, on the surface of the transparent substrate SUB1 on which the thin film transistor TFT is formed, a protective film PSV made of, for example, a resin film (or a SiN film, a sequential laminated body of SiN and a resin film) is formed to cover the thin film transistor TFT. Yes. This protective film PSV is formed mainly to avoid direct contact with the liquid crystal of the thin film transistor TFT.

  A plurality of pixel electrodes PX extending in the y direction and arranged in parallel in the x direction are formed on the upper surface of the protective film PSV. The pixel electrodes PX have gaps with the counter electrodes CT described above. Are alternately arranged.

  Each of the pixel electrodes PX is configured to be electrically connected by a pattern connected to each other in a region overlapping with the counter voltage signal line CL, and a contact formed on the protective film PSV. The hole TH1 is connected to the source electrode SD1 of the thin film transistor TFT.

  Thereby, the video signal from the drain signal line DL is supplied to the pixel electrode PX via the thin film transistor TFT driven by the supply of the scanning signal from the gate signal line GL. The pixel electrode PX generates an electric field between the pixel electrode PX and the counter electrode CT to which a reference signal is supplied.

  Note that a capacitive element Cstg is formed between the connection portions of the pixel electrodes PX and the counter voltage signal line CL. When the thin film transistor TFT is turned off, a video signal is relatively applied to the pixel electrode PX. It has functions such as accumulation for a long time.

  Here, each pixel electrode PX extending in the y direction in the figure is bent in the θ direction (relative to the y direction in the figure) from one end to the other end thereof, and then -θ direction (in the y direction in the figure). ) And further bent in the θ direction (with respect to the y direction in the figure).

  The counter electrode CT is also bent in the same manner as the pixel electrode PX, and is formed in a pattern in which one electrode overlaps the other electrode by shifting in the x direction in the figure.

  The reason why the pixel electrode PX and the counter electrode CT are formed in such a pattern is that a region whose direction is different in the electric field generated between the pixel electrode PX and the counter electrode CT is formed on the display surface. This is because a so-called multi-domain method that cancels changes in color tone when observed from different directions is adopted.

Further, the counter electrode CT (CT2) positioned on both sides (left and right direction) of the pixel region has a pattern different from that of the other counter electrode CT (CT1), and the side on the side of the adjacent drain signal line DL is the drain signal. While being parallel to the line DL, the width thereof is also relatively large.
The counter electrode CT2 has a shield function for reducing the gap with the drain signal line DL to prevent light leakage and preventing the electric field from the drain signal line DL from terminating at the pixel electrode PX. It is.

  Thus, the alignment film ORI1 is formed on the surface of the transparent substrate SUB1 on which the pixel electrode PX is formed so as to cover the pixel electrode PX. This alignment film ORI1 is a film that directly contacts the liquid crystal LC to regulate the initial alignment direction of the molecules of the liquid crystal LC. The rubbing direction is the extending direction of the drain signal line DL when the liquid crystal is p-type. When the liquid crystal is n-type, the gate signal line GL extends.

A black matrix BM is formed on the liquid crystal side surface of the transparent substrate SUB2 opposed to the transparent substrate SUB1 thus configured via the liquid crystal LC so as to define adjacent pixels. A color filter FIL of a corresponding color is formed in an opening (functioning as a substantial pixel area) of the matrix BM.
An alignment film ORI2 is formed covering the black matrix BM and the color filter FIL, and the rubbing direction of the alignment film ORI2 is the same as that of the alignment film on the transparent substrate SUB1 side.

In the configuration described above, both the pixel electrode PX and the counter electrode CT may be formed of an opaque metal made of, for example, Cr (or an alloy thereof), but at least one of them is, for example, ITO (Indium). A transparent metal such as -Tin-Oxide) may be used.
In addition, when the pixel electrode PX and the counter electrode CT are formed of a transparent metal, the so-called pixel aperture ratio is greatly improved.

<Drive circuit configuration>
As shown in FIG. 1, the video signal driving circuit He is disposed between the liquid crystal display panel PNL (more precisely, the transparent substrate SUB1) and the printed circuit board PCB, and has its input terminal as described above. IT and each terminal of the printed circuit board PCB are electrically connected through an anisotropic conductive film ACF.

  Conventionally, the connection at this portion has been made via solder. However, in recent years, with the trend toward higher definition of liquid crystal display devices, as the number of output terminals OT of the video signal drive circuit He increases, the number of input terminals IT also increases, and the distance between the terminals also increases. It is narrowing.

  For this reason, when the video signal driving circuit He is heat-bonded to the printed circuit board PCB, there is a disadvantage that the adjacent terminals are short-circuited by the solder spreading in the horizontal direction.

Even if such inconvenience does not occur, when the remaining solder exists between adjacent terminals, it is pointed out that a short circuit occurs due to external force applied to the terminal or its vicinity. It has been reached.
For this reason, an anisotropic conductive film ACF is used for connection between the input terminal of the video signal driving circuit He and the terminal of the printed circuit board PCB.

  The diameter of the conductive beads mixed in the anisotropic conductive film ACF is small, and when the video signal driving circuit He is thermocompression bonded to the printed circuit board PCB via the anisotropic conductive film ACF, the conductive beads This is because the terminals arranged adjacent to each other by the conductive beads are not electrically connected.

FIG. 5 is a graph showing the short-circuit failure rate at the distance between terminals when solder is used and when an anisotropic conductive film is used.
When solder is used, when the distance between terminals is 0.40 mm or less, the short-circuit defect rate suddenly increases (especially noticeable at 0.32 mm or less), whereas an anisotropic conductive film is used. In some cases, it only rises in a very gentle state.
Therefore, it is effective to use an anisotropic conductive film when the distance between terminals is 0.40 mm or less (or 0.32 mm or less).

Here, the inter-terminal distance refers to the distance between adjacent sides of adjacent terminals arranged in parallel to each other.
Also in the vertical scanning drive circuit V, the connection between the input terminal and each terminal of the printed circuit board PCB is made through the anisotropic conductive film ACF.
In the following description of each embodiment, the video signal drive circuit He is shown as an embodiment, and can be applied to the vertical scanning drive circuit V.

Example 2
In this embodiment, in the video signal driving circuit He shown in the first embodiment, when the distance between the terminals is 0.20 mm or less, the connection between the video signal driving circuit He and the terminals of the printed circuit board PCB is anisotropic. The conductive film ACF is used.
In this case, not only the effects shown in the first embodiment can be obtained, but also the adverse effects caused by the misalignment of the video signal drive circuit He with respect to the liquid crystal display panel PNL can be eliminated.

  That is, when the video signal drive circuit He is positioned with respect to the liquid crystal display panel PNL, a misalignment of about 0.10 mm usually occurs. However, the distance between the terminals is 0.20 mm or less, and each terminal is connected using solder. When it is performed, it is confirmed that the short circuit of each terminal frequently occurs due to the lateral spread in the molten state of the solder.

  Therefore, when the distance between the terminals is 0.20 mm or less, the above-described disadvantage can be avoided by using the anisotropic conductive film ACF for connecting the video signal driving circuit He and the liquid crystal display panel PNL. become.

Example 3
In this embodiment, the video signal driving circuit He and each terminal of the printed circuit board PCB are connected via the anisotropic conductive film ACF, and the anisotropic conductive film ACF is divided for each video signal driving circuit He. There is in being.

  That is, as shown in FIG. 5, the anisotropic conductive film ACF is used in each video signal drive circuit He as being physically independent from other video signal drive circuits He adjacent thereto.

  As described above, the anisotropic conductive film ACF is configured as a resin film in which conductive beads are interspersed. When there is a portion where the conductive beads are not present in the mixture of the conductive beads, one side of this portion is included in this portion. Contact failure occurs between the other terminal and the other terminal.

  When such an anisotropic conductive film ACF is formed in common with each video signal drive circuit ACF, when it is found that a contact failure has occurred in a part of the anisotropic conductive film ACF, Therefore, not only the video signal drive circuit He in the corresponding part but all other video signal drive circuits He must be peeled off, resulting in poor workability.

  Therefore, by using the anisotropic conductive film ACF which is divided for each video signal driving circuit He, for example, the terminal of one video signal driving circuit He and the terminal of the printed circuit board PCB to be connected thereto are used. When a contact failure occurs, the other video signal drive circuit He can be left as it is, and only the one video signal drive circuit He can be removed and repaired using a new anisotropic conductive film ACF.

  From this, it is needless to say that one video signal driving circuit He does not have to be applied to one divided anisotropic conductive film ACF, and may be two or more. .

  On the other hand, in connecting each video signal driving circuit He and the liquid crystal display panel PNL, an anisotropic conductive film ACF common to each video signal driving circuit He is used, in other words, one anisotropic conductive film. Each video signal drive circuit He is preferably connected to the liquid crystal display panel PNL at each different part of the ACF.

  This is because when the liquid crystal display panel of the semiconductor device is thermocompression bonded to the liquid crystal display panel of the semiconductor device through the anisotropic conductive film, the liquid crystal display panel is formed of a glass having a small coefficient of thermal expansion, and the occurrence of the defect is small. This is because it is wise to prioritize workability.

  However, it is needless to say that the anisotropic conductive film ACF may be divided even in the connection between each video signal driving circuit He and the liquid crystal display panel PNL, similarly to the printed circuit board PCB side.

Example 4
In this embodiment, the anisotropic conductive film ACF for connecting each terminal of the liquid crystal display panel PNL and the video signal driving circuit He, and the anisotropic conductive film for connecting each terminal of the printed circuit board PCB and the video signal driving circuit He. The physical properties of the film ACF are different.

  That is, as one example, the anisotropic conductive film ACF for connecting the terminals of the printed circuit board PCB and the video signal driving circuit He connects the terminals of the liquid crystal display panel PNL and the video signal driving circuit He. The anisotropic conductive film ACF is intended to have a lower melting point.

  Thereby, the temperature at the time of thermocompression bonding of the video signal driving circuit He to the printed circuit board PCB via the anisotropic conductive film ACF can be lowered, and the thermal expansion coefficient of the printed circuit board PCB and the video signal driving circuit He can be reduced. The influence by a big difference can be suppressed.

  In the connection between the liquid crystal display panel PNL and the video signal drive circuit He, the thermal expansion coefficient of the liquid crystal display panel PNL is small and correction by expansion is easy, but the connection between the printed circuit board PCB and the video signal drive circuit He is such a connection. This is because the correction is difficult, and the terminal pitch on the other side is larger than the terminal pitch on one side, and the connection failure due to the deviation is prevented.

  In such a case, it is effective to first connect the liquid crystal display panel PNL and the video signal drive circuit He, and then connect the video signal drive circuit He and the printed circuit board PCB.

  If the manufacturing process is reversed, there is a concern that the printed circuit board PCB may be melted by heat at the time of pressure bonding between the liquid crystal display panel PNL and the video signal driving circuit He. This is because the connection using the anisotropic conductive film ACF to the printed circuit board PCB may be disconnected.

  As another embodiment, the dispersion density of the conductive beads mixed in the anisotropic conductive film ACF for connecting the respective terminals of the liquid crystal display panel PNL and the video signal driving circuit He (the conductive beads in the unit area). The number) is higher than that of the anisotropic conductive film ACF for connecting the terminals of the printed circuit board PCB and the video signal driving circuit He.

The terminals on the output side of the video signal driving circuit He (terminals on the liquid crystal display panel side) are formed with a large number and a small width, so that the conductive beads of the anisotropic conductive film ACF are evenly scattered. If the conductive beads are not mixed in a part, contact failure is likely to occur in this part.
Therefore, the amount of conductive beads mixed in the anisotropic conductive film ACF for connecting the liquid crystal display panel PNL and each terminal of the video signal driving circuit He is increased.

  On the other hand, the terminal on the input side of the video signal driving circuit He has a large degree of misalignment with the terminal of the printed circuit board, and the amount of conductive beads of the anisotropic conductive film interposed between them is temporarily increased. In this case, in combination with the misalignment, short-circuiting between adjacent terminals is likely to occur due to lateral movement and aggregation of the conductive beads during thermocompression bonding, so the amount of the conductive beads is small. .

  As another embodiment, the diameter of the conductive beads mixed in the anisotropic conductive film ACF for connecting each terminal of the liquid crystal display panel PNL and the video signal drive circuit He is different from that of the printed circuit board PNL and the video signal drive. It is configured to be smaller than that of the anisotropic conductive film ACF for connecting each terminal of the circuit He.

  The output-side terminals (liquid crystal display panel-side terminals) of the video signal driving circuit He are formed with a large number and a small width. For this reason, the diameter of the conductive beads mixed in the anisotropic conductive film ACF corresponding to the width of the terminal is reduced. If it is configured to be large, the probability that the conductive beads are arranged between the opposing terminals is reduced, and there is a concern that a contact failure may occur.

  On the other hand, the conductive beads mixed in the anisotropic conductive film for connecting the input side terminal of the video signal driving circuit He and the terminal of the printed circuit board PNL have a large diameter, and are taken along the line VII-VII in FIG. As shown in FIG. 7 which is a cross-sectional view, the conductive bead CB after thermocompression bonding is deformed into an ellipse so that the contact area with the opposing terminals can be increased.

  Since power is supplied from the printed circuit board PCB to the video signal drive circuit He, it is extremely effective in terms of characteristics to reduce the resistance at the terminal connection portion in this way.

Example 5 FIG.
This embodiment relates to the size of the diameter of the conductive beads mixed in the anisotropic conductive film ACF that connects each terminal on the input side of the video signal drive circuit He and each terminal of the printed circuit board PCB. is there.

As shown in FIG. 8, the printed circuit board PCB has a conductive film CL formed as a wiring pattern on the surface thereof, and an insulating film IN having an opening in the terminal area.
This insulating film IN is a film-like sheet affixed and has a thickness of about 50 μm.
The diameter of the conductive beads CB mixed in the anisotropic conductive film ACF is set to be equal to or greater than the film thickness of the insulating film IN.

  As a result, the conductive beads CB of the anisotropic conductive film ACF disposed in the opening exposing the terminal portion of the insulating film IN are sufficiently projected from the surface of the insulating film IN, so that the video signal There is an effect that the connection with the terminal of the drive circuit He is performed with high reliability.

  Then, the power is supplied to the terminal on the printed circuit board PCB side, and the conductive beads of the anisotropic conductive film are deformed into an elliptical shape by the thermocompression bonding of the video signal driving circuit He as described above. In consideration of sufficiently reducing the connection resistance between the terminals, the size of the conductive bead CB is determined to be larger than a size sufficient for reliable connection of each terminal of the printed circuit board PCB and the video signal driving circuit He. You can also

Example 6
In this embodiment, an anisotropic conductive film ACF is used to connect each terminal on the input side of the video signal driving circuit He and each terminal of the printed circuit board PCB, and gold (for example) is formed on the surface of each terminal of the printed circuit board PCB. It is configured by plating Au).

  As described above, power is supplied to the terminals on the printed circuit board PCB side, and as shown in FIG. 9, each terminal of the printed circuit board PCB and the video signal drive circuit He is in the anisotropic conductive film ACF. Since current flows through a point contacted with the conductive beads, excessive current concentration tends to occur at this point.

  In addition, since each terminal of the printed circuit board PCB is becoming closer to another terminal adjacent thereto, a current flows through an electrolyte such as water that happens to be between these terminals, and the printed circuit board PCB Terminals are easily corroded by electric corrosion.

  For this reason, by forming a gold (Au) layer (indicated by the symbol PL in the figure) that is not easily oxidized on the surface of each terminal of the printed circuit board PCB, this inconvenience is prevented and connection reliability is ensured. ing.

  For this reason, the material formed on the surface of each terminal of the printed circuit board PCB is not necessarily limited to Au, and other materials, for example, a material that is difficult to oxidize the ITO film may be used. . Needless to say, at least each terminal of the printed circuit board PCB may be formed of the above-described material.

Example 7
In this embodiment, the terminals TM of the printed circuit board PCB are arranged in two rows as shown in FIG. 10, and each terminal in the first row is arranged between the terminals in the second row so-called staggered arrangement. ing.
Accordingly, it goes without saying that the input terminals of the video signal drive circuit He are also arranged corresponding to the respective terminals of the printed circuit board PCB.

  With such an arrangement, even if the terminals are close to each other, adjacent terminals (terminals in the first row and terminals in the second row adjacent thereto) can be prevented from facing each other.

  This can suppress the occurrence of electrolytic corrosion between a certain terminal and another terminal adjacent to the terminal, and even if electrolytic corrosion occurs, the progress until failure of the terminal can be significantly delayed.

  That is, the terminals arranged adjacent to each other with their diagonal lines substantially matched can be sufficiently separated by taking the distance between the first row of terminal groups and the second row of terminal groups. Occurrence can be suppressed.

  For example, even if electrolytic corrosion occurs, the electrolytic corrosion proceeds from one corner to the diagonal, but the distance (the diagonal line extending from one corner to the diagonal) (Corresponding to the length) is relatively large, so that it is possible to greatly delay the progress to the terminal trouble.

By the way, considering the case where the terminals are arranged in only one row, each terminal is adjacent to the other adjacent terminals with their sides facing each other.
In this case, if galvanic corrosion occurs at adjacent terminals, galvanic corrosion proceeds from the side of each terminal to its opposite side, but the width of each terminal is extremely small, so the progression to the trouble of the terminal. Will be accelerated.

  In addition, with the above-described configuration, there is also an effect that it is difficult to cause peeling of the insulating film covering between the terminal and another terminal adjacent to the terminal. This insulating film is formed by sticking a film-like sheet as described above, and when the width between the openings is narrow, the above-described configuration is effective because the portion is likely to peel off. Become.

Further, in this case, the anisotropic conductive film ACF for connecting the video signal driving circuit He of the first row terminal group and the second row terminal group on the printed circuit board PCB is different for each terminal group. It is preferable to use one anisotropic conductive film ACF without using the anisotropic conductive film ACF.
This is because when a plurality of anisotropic conductive films ACF are used, it is easy to form a portion where they are overlapped, which may cause a failure in connection.

It is a principal part top view which shows one Example of the liquid crystal display device by this invention. FIG. 2 is an equivalent circuit diagram illustrating an embodiment of a liquid crystal display device according to the present invention. It is a top view which shows one Example of the pixel of the liquid crystal display device by this invention. It is sectional drawing in the IV-IV line of FIG. It is a graph which shows the effect of the liquid crystal display device by this invention. It is a principal part top view which shows the other Example of the liquid crystal display device by this invention. It is a figure which shows the effect of the liquid crystal display device by this invention. It is principal part sectional drawing which shows the other Example of the liquid crystal display device by this invention. It is principal part sectional drawing which shows the other Example of the liquid crystal display device by this invention. It is a principal part top view which shows the other Example of the liquid crystal display device by this invention.

Explanation of symbols

  PNL ... liquid crystal display panel, V ... vertical scanning drive circuit, He ... video signal drive circuit, ACF ... anisotropic conductive film, PCB ... printed circuit board, GL ... gate signal line, DL ... drain signal line.

Claims (1)

A liquid crystal display panel, a printed circuit board disposed in the vicinity of the liquid crystal display panel, and a plurality of film carrier type semiconductor devices disposed between the liquid crystal display panel and the printed circuit board,
The connection of each terminal of each semiconductor device and the printed circuit board and the connection of each terminal of each semiconductor device and the liquid crystal panel are made through anisotropic conductive films, respectively.
The density of the conductive beads mixed in the anisotropic conductive film that connects each terminal of the liquid crystal display panel and the semiconductor device is that of the anisotropic conductive film that connects each terminal of the printed circuit board and the semiconductor device. A liquid crystal display device characterized by being configured higher than the above.

Images