JP2006163109A - Circuit substrate, electrooptical apparatus, electronic device and manufacturing method of circuit substrate - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a technology capable of reliably sticking substrates together and electrically connecting the substrates, while keeping a uniform gap between the substrates. <P>SOLUTION: Sticking and electrical connection between an organic light emitting device (OLED) substrate 100 and a thin film transistor (TFT) substrate 120 are realized by a solder bump 112. First, the solder bump 112 is formed on an electrode pad 111 which is exposed on a surface of the TFT substrate 120. Next, the TFT substrate 120 on which the solder bump 112 is formed and the OLED substrate 100 are overlapped each other and position alignment is performed. At this time, a gap material 113 and a drying agent etc. are suitably placed between both the substrates. By reflowing the TFT substrate 120 and the OLED substrate 100 which are overlapped each other under reduction atmosphere, both the substrates are firmly fixed to each other and the electrode pad 111 of the TFT substrate 120 and an anode 102 of the OLED substrate 100 are electrically connected. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a circuit board obtained by bonding two substrates, an electro-optical device, an electronic apparatus, and a method for manufacturing the circuit board.

  As one of flat panel displays, there is an organic EL display device using an organic electroluminescence element (hereinafter referred to as an organic EL element) as a light emitting element. Since this organic EL display device is a self-luminous type, it has a feature that a viewing angle is wide. In addition, since the organic EL display device emits light only for necessary pixels, there is an advantage that power consumption is small as compared with a liquid crystal display device which is a backlight type display device.

The organic EL display device having such a feature generally has a structure in which an organic EL element responsible for light emission and a drive circuit for driving the organic EL element are formed on a glass substrate. A structure in which a substrate (hereinafter referred to as an OLED substrate) on which an organic EL element is mounted and a substrate (hereinafter referred to as a TFT substrate) on which a thin film transistor (TFT) or the like for driving the organic EL element is bonded with a conductive adhesive or an insulating adhesive Have been proposed (see, for example, Patent Document 1 below).
According to such a structure, the formation of an organic EL element that requires a relatively low temperature process and the formation of a TFT or the like that requires a relatively high temperature process can be performed independently, thereby simplifying the manufacturing process and reducing the cost. It becomes possible.

Japanese Patent Laid-Open No. 11-3048

  However, with an increase in the size and definition of the display, it is required to dispose the adhesive with high precision, and it is difficult to meet the demand by a conventional method using screen printing or a dispenser. In addition, it is difficult to separate the substrates with a uniform gap by simply bonding the two substrates using an adhesive, and the portion supported by the conductive adhesive has a low withstand pressure against external pressure, so There is also a problem that poor conduction is likely to occur between the organic EL element connected by the adhesive and the drive circuit.

  The present invention has been made in view of the circumstances described above, and it is an object of the present invention to provide a technique capable of reliably performing bonding between substrates and electrical connection between substrates while ensuring a uniform gap. And

  In order to achieve the above object, a circuit board according to the present invention is a circuit board in which two substrates are bonded to each other, and a first substrate on which a driving element having electrode pads is formed, and an electro-optic that constitutes a pixel The second substrate on which the element is formed, the first substrate, and the second substrate are fixed, and the electrode pad exposed on the surface of the first substrate and the electro-optic element are electrically connected. And a gap member sandwiched between the first substrate and the second substrate.

  According to such a configuration, electrical connection and bonding between the first substrate and the second substrate are realized by the solder member. Therefore, unlike the prior art, it is not necessary to consider the margin for the placement accuracy of the conductive adhesive, and the two substrates can be reliably connected even if the electrode pad provided with the solder member is small. As a result, an effect of increasing the degree of freedom in the layout design of both substrates can be obtained.

  Here, in the above configuration, it is preferable that the electro-optical element is an organic EL element, the driving element is a thin film transistor that controls driving of the organic EL element, and the solder member has a melting point. An embodiment formed by a solder material of 150 ° C. or less is preferable. According to such a configuration, it can be applied to a substrate having low heat resistance.

  The circuit board manufacturing method according to the present invention includes a circuit in which a first substrate on which a drive element having electrode pads is formed and a second substrate on which an electro-optic element constituting a pixel is formed are bonded together. A method for manufacturing a substrate, comprising: a pad forming step of forming an electrode pad on the surface of the first substrate; a solder forming step of forming a solder member on the electrode pad; and an electrical connection between the substrates by the solder member. An alignment step of aligning both substrates so that connection is possible, and fixing the first substrate and the second substrate by melting the solder member, And a fixing / connecting step of electrically connecting the electrode pad exposed on the surface and the electro-optic element.

  According to this manufacturing method, the electrical connection and bonding between the first substrate and the second substrate are realized by the solder member. Therefore, unlike the prior art, it is not necessary to consider the margin for the placement accuracy of the conductive adhesive, and the two substrates can be reliably connected even if the electrode pad provided with the solder member is small. As a result, an effect of increasing the degree of freedom in the layout design of both substrates can be obtained.

  Here, in the solder forming step, a mode in which the solder member is formed by a solder jet method is preferable, and in the fixing / connecting step, a mode in which the solder member is melted by reflow is preferable. According to this aspect, it is possible to form the solder member on the electrode pad with high accuracy and to securely fix the substrates.

Moreover, in the said manufacturing method, it is a process performed prior to the said alignment process, Comprising: The aspect which further includes the gap material arrangement | positioning process which arrange | positions a gap material on the said 2nd board | substrate is preferable. According to this aspect, a desired gap between the substrates can be ensured.
Further, it is preferable that the electro-optical element is an organic EL element, and the driving element is a thin film transistor that controls driving of the organic EL element, and the solder member is formed of a solder material having a melting point of 150 ° C. or less. The embodiment is preferred. According to such a configuration, it can be applied to a substrate having low heat resistance.

  Further, the circuit board described above may be applied to an electro-optical device. Here, the electro-optical device refers to a device including a liquid crystal element, an electrophoretic element having a dispersion medium in which electrophoretic particles are dispersed, an EL element, and the like, and a device in which a thin film transistor or the like is applied to a driving circuit.

  Further, such an electro-optical device may be applied to an electronic device. Here, the electronic apparatus refers to a general apparatus having a certain function including the electro-optical device according to the present invention, and includes, for example, an electro-optical device and a memory. The configuration is not particularly limited, but for example, an IC card, a mobile phone, a video camera, a personal computer, a head-mounted display, a rear-type or front-type projector, a fax machine with a display function, a digital camera finder, a portable TV, A DSP device, PDA, electronic notebook, electronic bulletin board, advertising display, etc. are included.

  Hereinafter, an electro-optical device according to an embodiment of the present invention will be described using an organic EL display device (electro-optical device) having a top emission structure as an example.

  FIG. 1 is a diagram (sectional view) showing a configuration of an organic EL display device 200 of the present embodiment. An organic EL display device 200 shown in FIG. 1 has a circuit substrate in which an OLED substrate 100 including a plurality of organic EL elements and a TFT substrate 120 including a plurality of TFTs 110 for driving the organic EL elements are arranged to face each other.

  The OLED substrate (second substrate) 100 includes a transparent substrate 101 such as a glass substrate or a flexible substrate, a transparent electrode (anode) 102 made of ITO or the like and formed on the transparent substrate 101, and the surface of the transparent electrode 102 Are formed on the surface of the transparent electrode 102, the organic layer 104 formed in the opening of the partition wall 103, and the surface of the organic layer 104. And an electrode (cathode) 105 made of aluminum or the like.

  The organic layer 104 has a structure in which, for example, a hole transport layer, a light emitting layer, and an electron transport layer (all not shown) are sequentially laminated. The hole transport layer is a mixture of polyethylene dioxythiophene and polystyrene sulfonic acid. The light emitting layer is formed of a polydialkylfluorene derivative or the like, and the electron transport layer is formed of calcium, lithium, an oxide thereof, fluoride, or the like.

  The organic EL element (electro-optical element) includes an anode 102, an organic layer 104, and a cathode 105, and the light emitting layer of the organic layer 105 emits light by supplying current to the organic layer 104 via the anode 102 and the cathode 105. Then, the emitted light is emitted to the outside through the anode 102 and the transparent substrate 101.

  On the other hand, the TFT substrate (first substrate) 120 includes a TFT 110 used for driving an organic EL element mounted on the OLED substrate 100, other circuit elements, and the like. On the surface of the TFT substrate 120, an electrode pad 111 made of copper, aluminum, or the like connected to the electrode (source electrode or drain electrode) of each TFT 110 is provided. Solder bumps (solder members) 112 are formed on the electrode pads 111 exposed on the surface of the TFT substrate 120. For forming the solder bumps 112, a flow method using a solder jet (solder jet method), a screen printing method, an electrolytic plating method, or the like can be used. The material of the solder bump 112 is preferably a low melting point type Pb-free solder (SnBi-based, InSn-based, InBiSn-based, InSnZn-based solder, etc.), but Pb-containing solder may also be used.

  As shown in FIG. 1, the solder bump 112 is in contact with the electrode pad 111 of the TFT 110 and is also in contact with a part of the anode 102 through a hole 103 ′ provided in the partition wall 103. The solder bump 112 serves not only to fix the OLED substrate 100 and the TFT substrate 120 but also to electrically connect the organic EL element and the TFT 110. An insulating gap material (for example, a substantially spherical spacer) 113 having a predetermined thickness D is provided between the OLED substrate 100 and the TFT substrate 120 connected by the solder bumps 112. The gap material 113 secures a uniform gap between the OLED substrate 100 and the TFT substrate 120. The thickness D of the gap material 113 may be set as appropriate according to the desired size of the gap (for example, 10 μm), and a desiccant for maintaining a good environment in the space 151 formed between the two substrates. (Not shown) may be arranged. Further, an electrode pad for anode connection may be provided on the OLED substrate 100, and this electrode pad and the electrode pad 111 of the TFT 110 may be connected by a solder bump 112.

  FIG. 2 is a diagram for explaining a bonding process between the OLED substrate 100 and the TFT substrate 120. First, solder bumps 112 are formed on the electrode pads 111 exposed on the surface of the TFT substrate 120 by using a solder jet method or the like (see A in FIG. 2). Here, the solder material adheres only to the electrode pad portion exposed on the surface of the TFT substrate 120 and does not adhere to other portions (that is, the insulating film portion). Therefore, it is not necessary to consider a margin for the placement accuracy of the conductive adhesive as in the prior art, and it is possible to reliably form the solder bump 112 on the pad even if the electrode pad 111 is small.

  Next, the TFT substrate 120 on which the solder bumps 112 are formed and the OLED substrate 100 are overlapped and aligned. Specifically, the two substrates are aligned so that the solder bumps 112 enable electrical connection between the substrates. When this alignment is performed, the gap material 113, the desiccant, or the like is disposed on one of the substrates (for example, an OLED substrate). The superposed TFT substrate 120 and OLED substrate 100 are reflowed in a reducing atmosphere (for example, reflowing at about 150 ° C.) to melt the solder bumps 112, thereby fixing both substrates and the electrode pads 111 of the TFT substrate 120. The anode 102 of the OLED substrate 100 is electrically connected (see B in FIG. 2).

  Finally, a sealing agent such as a UV curable resin is applied to the outer peripheral portions (not shown) of both substrates, and the sealing agent is cured by irradiating ultraviolet rays, thereby forming an organic EL display device. The sealing agent may be a thermosetting type in addition to a UV curable resin type. When a thermosetting sealant is used, drawing may be performed using a dispenser or the like before the two substrates are bonded together.

  As described above, according to the present embodiment, electrical connection and bonding between the OLED substrate and the TFT substrate are realized by solder. Therefore, it is not necessary to consider the margin for the placement accuracy of the conductive adhesive as in the prior art, and the two substrates can be reliably connected even if the electrode pad provided with solder is small. As a result, an effect of increasing the degree of freedom in the layout design of both substrates can be obtained. In addition, by using a low melting point type solder, it is possible to reduce thermal damage to the OLED substrate. In the above-described embodiment, the solder bumps 112 are melted by reflow. However, the solder bumps 112 may be melted using a laser, current, ultrasonic waves, or the like.

B. Second Embodiment Next, electronic devices to which the organic EL display device of the above-described embodiment can be applied will be exemplified. In the following description, the organic EL display device 200 is taken as a representative, but the same applies to the other organic EL display devices 200a to 200e.

  3 and 4 are diagrams showing examples of electronic devices to which the above-described organic EL display device can be applied. FIG. 3A shows an application example to a mobile phone. The mobile phone 230 includes an antenna portion 231, an audio output portion 232, an audio input portion 233, an operation portion 234, and the organic EL display device 200 of the present invention. Yes. Thus, the organic EL display device according to the present invention can be used as a display unit. FIG. 3B shows an application example to a video camera. The video camera 240 includes an image receiving unit 241, an operation unit 242, an audio input unit 243, and the organic EL display device 200 of the present invention.

  FIG. 3C shows an application example to a portable personal computer (so-called PDA). The computer 250 includes a camera unit 251, an operation unit 252, and the organic EL display device 200 according to the present invention. FIG. 3D shows an application example to a head mounted display. The head mounted display 260 includes a band 261, an optical system storage unit 262, and the organic EL display device 200 according to the present invention.

  FIG. 4A shows an application example to a television, and the television 300 includes the organic EL display device 200 according to the present invention. It should be noted that the organic EL display device according to the present invention can be similarly applied to a monitor device used in a personal computer or the like. FIG. 4B shows an application example to a roll-up television, and the roll-up television 310 includes the organic EL display device 200 according to the present invention.

  The organic EL display device according to the present invention is not limited to the above-described example, and can be applied to various electronic devices having a display function. For example, in addition to these, it can also be used for a fax machine with a display function, a finder for a digital camera, a portable TV, an electronic notebook, an electric bulletin board, a display for advertisements, and the like.

  The present invention is not limited to the contents of the above-described embodiments, and various modifications can be made within the scope of the gist of the present invention. For example, in the embodiment described above, an organic EL display device has been described as an example of an electro-optical device having a structure in which two substrates are bonded together. However, the present invention can be applied to various other electro-optical devices. Furthermore, the present invention can be applied to all circuit boards in which two substrates are bonded.

It is a figure which shows the structure of the organic electroluminescence display which concerns on 1st Embodiment of this invention. It is a figure which shows the bonding process of the board | substrate which concerns on the same embodiment. It is the figure which illustrated the composition of the electronic equipment concerning a 2nd embodiment. It is the figure which illustrated the composition of the electronic equipment concerning the embodiment.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 100 ... OLED board | substrate, 101 ... Transparent base material, 102 ... Transparent electrode, 103 ... Partition, 103 '... Hole, 104 ... Organic layer, 105 ... Cathode, 110 ... TFT, 111 ... Electrode pad, 112 ... Solder bump, 113 ... Gap Material 120: TFT substrate 151 ... Space 200 ... Organic EL display device

Claims (11)

A circuit board obtained by bonding two substrates together,
A first substrate on which a drive element having an electrode pad is formed;
A second substrate on which an electro-optic element constituting a pixel is formed;
A solder member for fixing the first substrate and the second substrate and electrically connecting the electrode pad exposed on the surface of the first substrate and the electro-optic element;
A circuit board comprising: a gap material sandwiched between the first substrate and the second substrate.   The circuit board according to claim 1, wherein the electro-optical element is an organic EL element, and the driving element is a thin film transistor that controls driving of the organic EL element.   The circuit board according to claim 1, wherein the solder member is made of a solder material having a melting point of 150 ° C. or less. A circuit board manufacturing method in which a first substrate on which a drive element having an electrode pad is formed and a second substrate on which an electro-optic element constituting a pixel is formed are bonded together,
A pad forming step of forming an electrode pad on the surface of the first substrate;
A solder forming step of forming a solder member on the electrode pad;
An alignment step of aligning both substrates so that electrical connection between the substrates is possible by the solder member;
The first substrate and the second substrate are fixed by melting the solder member, and the electrode pad exposed on the surface of the first substrate is electrically connected to the electro-optic element. A method for manufacturing a circuit board, comprising: a fixing and connecting step.   5. The method of manufacturing a circuit board according to claim 4, wherein in the solder formation step, the solder member is formed by a solder jet method.   6. The method of manufacturing a circuit board according to claim 4, wherein in the fixing / connecting step, the solder member is melted by reflow.   The process according to any one of claims 4 to 6, further comprising a gap material arranging step of arranging a gap material on the second substrate, which is performed prior to the alignment step. A method for manufacturing a circuit board according to claim 1.   The circuit according to claim 4, wherein the electro-optical element is an organic EL element, and the driving element is a thin film transistor that controls driving of the organic EL element. A method for manufacturing a substrate.   The method of manufacturing a circuit board according to claim 4, wherein the solder member is made of a solder material having a melting point of 150 ° C. or less.   An electro-optical device comprising the circuit board according to claim 1.   An electronic apparatus comprising the electro-optical device according to claim 10.

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