JP3973345B2 - Plasma display device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a heat dissipation mounting structure for a driver IC, and more particularly to a heat dissipation mounting structure for a driver IC for a plasma display device.
[0002]
[Prior art]
Display devices that use plasma display panels are the most promising display candidates for next-generation large-sized TVs due to the wide viewing angle and the ability to create large screens, in addition to the small depth that is a common feature of flat displays. It is attracting attention as.
However, unlike a device using a liquid crystal panel, which is the same flat display, a plasma display panel consumes a large amount of power because it is a display due to a discharge phenomenon. Therefore, there is a problem that the power consumption of the driver IC that guides the display signal to the panel is large.
[0003]
Conventionally, the mounting structure of the driver IC has been wire bonding, but as with the preceding liquid crystal, the productivity of wire bonding is becoming a problem as the production volume increases. Therefore, a flip chip method suitable for mass production is being sought, but unlike liquid crystal, a structure that pursues heat dissipation is required even in flip chip mounting.
Japanese Patent Application Laid-Open No. 10-260641 proposes a structure in which a single aluminum plate supporting a plasma display panel is stretched more than usual and a driver IC is attached to the stretched portion as an example of the method. Although this structure is reasonable, a method for fixing the driver IC for ensuring heat conduction is not specifically disclosed.
On the other hand, although heat conduction is not the purpose, Japanese Patent Application Laid-Open No. 9-27515 discloses an example of a structure that maintains contact by applying pressure from the outside.
[0004]
Further, a conventional plasma display panel will be described with reference to FIG.
[0005]
2 (a) and 2 (c) are cross-sectional views of a part of a conventional plasma display panel, and FIGS. 2 (b) and 2 (d) are views of FIGS. 2 (a) and 2 (c), respectively. It is a partially expanded sectional view. Although this cross-sectional view is a partial cross-sectional view of the panel, the relationship with the whole is apparent with reference to FIG.
In FIG. 2, the address IC module is a combination of the address IC 201 and the flexible wiring board 202. The address IC 201 is connected to the flexible wiring board 202 in a flip chip structure. That is, the electrical connection is realized by bonding the gold bump 205 formed on the circuit forming surface of the address IC 201 to the copper wiring 209 formed on the surface of the flexible wiring board 202.
[0006]
In this structure, in order to release the heat generated in the address IC 201, it is necessary to use a surface opposite to the circuit formation surface. The reason is that the gold bump 205 having good thermal conductivity is used on the circuit forming surface side of the address IC 201, but since the area of the gold bump 205 is small, it is ACF (differently different) that transmits heat to the flexible wiring board 202. However, since the thermal conductivity of the ACF 206 is small, it is difficult for heat to be transmitted to the flexible wiring board 202, and furthermore, the thermal conductivity of the flexible wiring board 202 itself is small.
Therefore, heat is released to the aluminum chassis 204 by using the heat conductive sheet 203 which is an adhesive member having good heat conductivity. The heat conductive sheet 203 is a resin, but is a sticky sheet using a material having a thermal conductivity of 1 to 10 W / m · K, which is improved in heat conductivity by an order of magnitude compared to ordinary resins.
[0007]
[Problems to be solved by the invention]
However, when a high thermal conductivity powder (for example, boron nitride) is mixed with the resin in order to increase the thermal conductivity, it is difficult to improve the adhesive performance of the thermal conductive sheet 203. Initially, even when bonded as shown in FIGS. 2A and 2B, when the bonding surface of the aluminum chassis 204 is enlarged, as shown in the enlarged view of FIG. There are irregularities on the surface of which the air layer is formed. Even if the aluminum chassis 204 and the heat conductive sheet 203 are initially bonded by this air layer, the heat conductive sheet 203 and the aluminum chassis 204 are peeled off as time passes, as shown in FIGS. 2 (c) and 2 (d). Come.
Further, as is clear from FIG. 2B, the thermal conductivity is deteriorated due to the air layer generated by the unevenness of the bonding surface between the aluminum chassis 204 and the heat conductive sheet 203. That is, since air has poor heat conductivity, even if the heat conductive sheet 203 with good heat conductivity is used, sufficient heat is not transmitted to the air layer.
As described above, there is no disclosure in the prior art regarding a structure for effectively releasing heat generated in a driver IC having a flip chip structure.
[0008]
An object of the present invention provides the plasma display device is to provide a mounting structure for guiding the effective external heat generated in the driver IC of the flip chip structure.
[0009]
[Means for Solving the Problems]
In order to solve the above problems , in the present invention , as a plasma display device, a plasma display panel, a chassis in which the plasma display panel is arranged, a logic circuit, and a driver IC that drives the plasma display are included in the logic display device. A mounting structure mounted by flip-chip mounting on a flexible wiring board electrically connected to a circuit, a thermally conductive member disposed between the mounting structure and the chassis, and the mounting structure A pressing member disposed on a side different from the side connected to the chassis via the heat conductive member, and an elastic member disposed between the pressing member and the mounting structure. The mounting structure is pressed against the chassis via the thermally conductive member by pressing the mounting structure via an elastic member. Further, as a plasma display device, a plasma display panel, a chassis in which the plasma display panel is disposed, a logic circuit, a driver IC and a flexible wiring board on which the driver IC is mounted are electrically connected to the logic circuit A mounting structure having a thermal conductive member disposed in contact with the chassis, and a pressing member that is fixed to the chassis and disposed so as to have a distance from the chassis, The mounting structure is sandwiched and fixed between the pressing member and the heat conductive member, and the pressing member is in contact with the pressing member via an elastic member .
[0013]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings using examples. The present invention is not limited to these examples.
First, the principle of the present invention will be described with reference to FIGS.
FIG. 1 is a perspective view of an embodiment of a plasma display panel according to the present invention as viewed from the back side.
In the figure, reference numeral 101 denotes a front panel serving as a front surface of a product such as a television. The material is glass. The screen size of this example is 42 type, and the diagonal dimension of the screen is less than 1 m10 cm. A rear panel 102 is provided behind the front panel 101, and a small chamber (cell) for plasma emission is provided by reducing the pressure of about 0.1 mm between the front panel 101 and the rear panel 102. The number is 480 in the vertical direction and 2556 in the horizontal direction (852 × 3 primary colors), which are arranged in a lattice pattern. The two glass panels 101 and 102 are mechanically supported by an aluminum plate having a thickness of 1 mm. The aluminum plate is, for example, a single plate or a plate obtained by connecting another aluminum plate to this, and is shown as an aluminum chassis 103. The aluminum chassis 103 also mechanically supports the driving circuit board of the plasma display device 100.
[0014]
The driving circuit board of the plasma display apparatus 100 includes a power supply circuit board 104 located at the upper center part, a Y-side sustain circuit board 106 and an X-side sustain circuit board 107 located on the left and right, and a logic circuit board 105 located below the center part. It is composed of The power supply circuit board 104 generates a voltage required internally by using a voltage supplied from the outside. The Y side sustain circuit board 106 and the X side sustain circuit board 107 are paired and supply power for plasma emission. The logic circuit board 105 converts the image signal into a signal for plasma emission and supplies it to each pixel.
[0015]
The plasma display panel which is the subject of the present invention has, for example, three electrodes in one pixel. The front panel 101 is provided with X and Y electrodes, and the rear panel 102 is provided with A (address) electrodes. The image signal is stored by the Y electrode and the A electrode, and displayed by the X electrode and the Y electrode. A driver IC is used to store the image signal in each pixel. Of the driver ICs, one that leads to the A electrode is called an address IC module 113, and one that leads to the Y electrode is called a scan IC module 111. The X electrode is directly connected from the X-side sustain circuit board 107 by the X flexible wiring board 112 without using an IC. Between the address IC module 113 and the logic circuit board 105 is an address bus board 108 as a relay board, and between the scan IC module 111 and the Y-side sustain circuit board 106 is a Y bus board 109 as a relay board. In addition, there is an X bus board 110 as a relay board between the X flexible wiring board 112 and the X side sustain circuit board 107.
[0016]
The scan IC module 111 and the address IC module 113 generate a large amount of heat. Therefore, a heat dissipation structure is indispensable. In the figure, the Y presser plate 114 and the address presser plate 115 are visible as part of the heat dissipation structure.
The present embodiment relates to a heat dissipation structure of the scan IC module 111 and the address IC module 113. Basically, there is no difference between the scan IC module 111 and the address IC module 113, and the address IC module 113 generates more heat, so the address IC module 113 will be described.
[0017]
The principle for simultaneously solving the problem of peeling of the thermal conductive sheet 203 described with reference to FIG. 2 and the deterioration of thermal conductivity due to the air layer will be described with reference to FIG.
3A is a cross-sectional view showing a part of the AA cross section of FIG. 1 for explaining the principle of the present invention, and FIG. 3B is a partially enlarged cross-sectional view of FIG. 3A.
As shown in the figure, an address pressing plate 115 is used in this embodiment. As a result, the peeling problem as shown in FIG. 3 (b) is solved, and at the same time, the air layer ratio is shown in FIG. 3 (b) as shown in FIGS. 3 (a) and 3 (b). And the heat conduction is greatly improved.
[0018]
More specifically, it is necessary to sandwich the elastic member 308 for buffering between the address pressing plate 115 and the flexible wiring board 304. As shown in FIG. 1, a large number of address IC modules 113 are provided and arranged in a line. It is practical not to fix these individually but to fix a plurality of them together. For this reason, the distance between the flexible wiring board 304 and the aluminum chassis 103 differs between the address IC module in the vicinity of the fixed part such as a bolt and the address IC far from the fixed part. In addition, the aluminum chassis 103 is generally a single plate and is bent or distorted, so the distance between the flexible wiring board 304 and the aluminum chassis 103 is not constant. On the other hand, it is desirable to make the thickness of the heat conductive sheet 306 substantially uniform among the address ICs. Therefore, in order to absorb the difference in distance between the flexible wiring board 304 and the aluminum chassis 103, the elastic member 308 is required. Of course, even in the case of individual fixing, the elastic member 308 is indispensable because the fixing pressure is more stable when the elastic member 308 is present.
[0019]
4 is a cross-sectional view taken along the line AA of FIG. 1 showing an embodiment of a driver IC heat dissipation mounting structure according to the present invention. FIG. 4 is an enlarged view of the periphery of the address IC module 113 and shown in more detail than FIG. . FIG. 1 also shows a fine structure that cannot be displayed. Further, portions not directly related to the present embodiment are omitted. The address IC module 113 includes an address IC 301, an ACF (anisotropic conductive film) 303, a flexible wiring board 304, a gold bump 302 of the address IC 301 inserted in the ACF 303, and a copper wiring 309 of the flexible wiring board 304.
[0020]
The address IC 301 is electrically connected to the copper wiring 309 of the flexible wiring board 304 through a gold bump 302 formed on the circuit forming surface. Here, the ACF 303 is used for connection. The ACF 303 is obtained by dispersing conductive particles in an insulating resin, and exhibits conductivity when pressed against the copper wiring 309 of the flexible wiring board 304 by the gold bump 302. A connector 305 is used to connect the flexible wiring board 304 and the address bus board 108. Note that the address bus board 108 is supported by an insulating rod 307 so that the address bus board 108 (specifically, a printed board) does not come into contact with the aluminum chassis 103.
[0021]
In this embodiment, heat is released from the surface of the address IC 301 opposite to the circuit forming surface, and a heat conductive sheet 306 is used. At that time, as described with reference to FIG. 3, it is important to appropriately deform the heat conductive sheet 306 to increase the area contributing to heat conduction. That is, it is necessary to increase the contact area so as to be able to make contact with the unevenness of the aluminum chassis 204 to increase the thermal conductivity. Further, it is necessary to keep the thickness of the heat conductive sheet 306 to some extent. That is, as shown in FIGS. 2C and 2D, the address IC 201 and the aluminum chassis 204 are not necessarily parallel, and a part of the corner of the peripheral edge of the address IC 201 bites into the heat conductive sheet 203. Since the heat conductive sheet 203 may be broken and come into contact with the aluminum chassis 204, the thickness of the heat conductive sheet 306 needs to be maintained to some extent in order to prevent this.
[0022]
For that purpose, it is necessary to pressurize the heat conductive sheet 306 portion appropriately. As a pressure for maintaining a sufficient thickness of the heat conductive sheet 306 while sufficiently reducing the thermal resistance, 30 g / cm 2 to 100 g / cm 2 is required. However, the heat conductive sheet 306 must be made as thin as possible in order to keep the thermal resistance small. In this embodiment, it is 0.5 mm. When the above-described conditions are converted into the deformation amount of the heat conductive sheet 306, a small value of 0.1 mm to 0.2 mm is obtained. It is important and difficult to control the pressure applied to the heat conductive sheet 306, in other words, the amount of deformation of the heat conductive sheet 306. As shown in FIG. 1, there are a large number of address IC modules 113. It is virtually impossible to adjust the deformation amount of the heat conductive sheet 306 one by one. Furthermore, the address pressing plate 115 is one in this embodiment, and pressurizes all the address IC modules 113 in common. The fixing method is realized by passing a screw 119 through a screw hole provided at a corresponding location in the aluminum chassis 103 using a hole (not shown) provided in the address holding plate 115 as appropriate. A screw 119 may be provided for each address IC 301 as shown in FIG. 1, but in general, a plurality of address ICs 301 are fixed by two screws 119.
[0023]
Therefore, the property of the elastic member 308 becomes important. In this embodiment, an elastic resin 308a is provided as the elastic member. The elastic resin needs to have such a property that even if the address pressing plate 115 is fixed to some extent rough, the target pressing force is applied to all the heat conductive sheets 306. From our experience, when one plasma display device 100 is covered by one address pressing plate 115, the difference in the pressing distance of the address pressing plate 115 depending on the location of the heat conductive sheet 306 is 5 mm. In other words, if the required minimum pressure is applied to the heat conductive sheet 306 when the elastic resin 308 is deformed by 1 mm, the maximum pressure of the heat conductive sheet 306 must be applied by the deformation of the elastic resin 308 by 6 mm. Don't be. Therefore, a material having a softness of about 1/50 of the heat conductive sheet 306 was selected as the elastic resin 308. This material is, for example, rubbery silicone.
[0024]
Hereinafter, another embodiment of the present invention will be described with reference to FIG.
FIG. 5 is a cross-sectional view taken along the line AA of FIG. 1 showing another embodiment of the heat dissipation mounting structure of the driver IC according to the present invention. The basic structure of this embodiment is the same as that of the embodiment shown in FIG. 4, and heat generated by the address IC 301 mounted on the flexible wiring board 304 connected to the connector 305 of the address bus board 108 is a heat conductive sheet. It is guided to the aluminum chassis 103 through 306. At that time, in order to supply an appropriate pressing force to the heat conductive sheet 306, it is pushed by the address holding plate 115.
[0025]
In this embodiment, a metal spring 308b is used instead of the elastic resin 308a used in the embodiment shown in FIG. Strictly speaking, when the resin is used for a long period of time, plastic deformation tends to occur. There is also a problem of deterioration due to temperature environment and humidity environment. Therefore, in this embodiment, a metal spring material (specifically, phosphor bronze) was used. By using a spring, the structure was superior in long-term reliability compared to the examples using resin. Further, a clip (not shown) is used for the fixing structure of the address pressing plate 115. In order to clip between a plurality of address IC modules 113 arranged in the horizontal direction, the address pressing plate 115 and the aluminum chassis 103 are sandwiched between U-shaped clips. When the portion where the address IC module 113 is arranged is clipped, the flexible wiring board 304 is bent in a U-shape, one surface thereof is brought into contact with the aluminum chassis 103 side, and the flexible wiring board 304 bent in the U-shape. The U and the address presser plate 411 are sandwiched and fixed by U-shaped clips. Since the clip has elasticity, it is further added to the elasticity of the spring 308b, and the flexibility of the entire structure increases.
[0026]
In the present invention, considering the bending or distortion of the aluminum chassis 103, it is desirable that the elastic member be deformed by 1 mm to 10 mm with respect to the pressing force pressing the aluminum chassis 103 on the non-circuit forming surface of the address IC 301.
In the present invention, an elastic resin or a spring may be disposed opposite to the flexible wiring board after being adhered to the position of the address pressing plate corresponding to the interval at which the address IC is disposed.
[0027]
【The invention's effect】
As described above, according to the present invention, the heat generated from the driver IC can be efficiently led to the outside.
[Brief description of the drawings]
FIG. 1 is a perspective view of an embodiment of a plasma display panel according to the present invention as viewed from the back side.
FIG. 2 is a partial sectional view and a partially enlarged sectional view of a conventional plasma display panel.
FIGS. 3A and 3B are a cross-sectional view and a partially enlarged cross-sectional view showing a part of the AA cross section of FIG. 1 for explaining the principle of the present invention. FIGS.
4 is a cross-sectional view taken along line AA of FIG. 1 showing an embodiment of a heat dissipation mounting structure for a driver IC according to the present invention.
5 is a cross-sectional view taken along the line AA of FIG. 1 showing another embodiment of the heat dissipation mounting structure of the driver IC according to the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 100 ... Plasma display apparatus, 101 ... Front panel, 102 ... Back panel, 103 ... Aluminum chassis, 104 ... Power supply circuit board, 105 ... Logic circuit board, 106 ... Y side sustain circuit board, 107 ... X side sustain circuit board, 108 ... Address bus board, 109 ... Y bus board, 110 ... X bus board, 111 ... Scan IC module, 112 ... X flexible wiring board, 113 ... Address IC module, 114 ... Y presser board, 115 ... Address presser board, 201 ... Address IC, 202 ... Flexible wiring board, 203 ... Thermal conductive sheet, 204 ... Aluminum chassis, 205 ... Gold bump, 206 ... ACF, 207 ... Address holding plate, 208 ... Resilient member, 301 ... Address IC, 302 ... Gold bump 303 ... ACF 304 ... Fure Reluctant wiring board, 305 ... connector 306 ... heat conductive sheet, 307: insulating rod, 308 ... elastic member, 308a ... resilient resin, 308b ... spring.

Claims (7)

A plasma display panel;
A chassis in which the plasma display panel is disposed ;
Logic circuit;
A mounting structure in which a driver IC for driving the plasma display is mounted by flip chip mounting on a flexible wiring board electrically connected to the logic circuit;
A thermally conductive member disposed between the mounting structure and the chassis ;
A holding member disposed on a side different from the side connected to the chassis via the thermally conductive member of the mounting structure;
An elastic member disposed between the pressing member and the mounting structure;
Have
The plasma display device , wherein the pressing member presses the mounting structure through the elastic member, whereby the mounting structure is pressed against the chassis through the heat conductive member . A plasma display panel;
A chassis in which the plasma display panel is disposed;
Logic circuit;
A mounting structure electrically connected to the logic circuit and having a driver IC and a flexible wiring board on which the driver IC is mounted;
A thermally conductive member disposed in contact with the chassis;
A holding member fixed to the chassis and disposed so as to have a distance from the chassis ;
With
Said mounting structure, said fixed sandwiched between the pressing member and the heat conductive member, the pressing and member, a plasma display apparatus characterized by contacting through the elastic member. The plasma display device according to claim 1 or 2,
The plasma display apparatus according to claim 1, wherein the pressing member is one for a plurality of driver ICs . The plasma display device according to claim 1 or 2 ,
The plasma display apparatus according to claim 1, wherein the elastic member is deformed by 1 mm to 10 mm when a necessary pressure is applied to the driver IC by the pressing member. The plasma display device according to claim 1 or 2 ,
A plasma display device, wherein the pressing member is screwed to the chassis . The plasma display device according to claim 1 or 2 ,
A plasma display device characterized in that a clip is fixed between the chassis and the pressing member . The plasma display device according to claim 1 or 2 ,
The plasma display device, wherein the elastic member is a metal spring .

Images