Patent Publication Number: US-2003227593-A1

Title: Liquid crystal display device and manufacturing method of liquid crystal display device

Description:
BACKGROUND OF THE INVENTION  
       [0001] 1. Field of the Invention  
       [0002] The present invention relates to a liquid crystal display device, particularly to a liquid crystal display device in which interconnect wirings are formed of a metal film to improve display performance.  
       [0003] 2. Description of the Related Art  
       [0004] To response to reductions in size and costs of recent electronic devices, such devices have been adopted as two driver ICs for an STN (Super-Twisted Nematic) liquid crystal display device are combined in a single IC. More specifically, two driver ICs connected to each of traditional common and segment transparent electrodes are gathered on one side of a panel, and the two driver ICs are replaced by a single driver IC for driving.  
       [0005]FIG. 14 depicts a perspective view illustrating a traditional liquid crystal display device, and FIG. 15 depicts a plan view illustrating an essential part of the traditional liquid crystal display device.  
       [0006] As shown in FIG. 14, a traditional liquid crystal display device  100  is mainly configured of a pair of transparent substrates (first and second substrates)  101  and  102  facing each other with a liquid crystal layer sandwiched, not shown, and a control IC  103  disposed on an exposed surface  101   a  of the first substrate  101 . The first substrate  101  is formed longer in length than the second substrate  102 , and the portion extending off the second substrate  102  is formed to be the exposed surface  101   a.    
       [0007] On the surfaces of the substrates  101  and  102  on the liquid crystal layer side, common and segment transparent electrodes made of ITO (Indium Tin Oxide) are formed, respectively.  
       [0008] As shown in FIGS. 14 and 15, interconnect wirings  104  for connecting each of the transparent electrodes to the control IC  103  are drawn on the exposed surface  101   a  of the first substrate  101 . The interconnect wiring  104  is formed of a layered product of an ITO film and a metal film in which at least a part of the metal film is overlapped with the ITO film.  
       [0009] As shown in FIG. 15, an island electrode pad  104   a  made of the metal film is formed on the tip end of each of the interconnect wirings  104 , and terminals of the control IC  103  (not shown) are bonded to the electrode pads  104   a.    
       [0010] To form the interconnect wirings  104  including the electrode pads  104   a,  a photomask for use in forming the segment transparent electrodes is fist used to form the ITO film configuring the interconnect wirings  104  at the same time when the transparent electrodes are formed, and then another photomask is used to form the metal film.  
       [0011] As shown in FIGS. 14 and 15, on both sides of the control IC  103  on the exposed surface  101   a,  alignment marks  105 ,  105  are formed that are the reference for positioning the control IC  103  in mounting the control IC  103  on the first substrate  101 . The alignment marks  105 ,  105  are made of ITO, for example, as similar to the transparent electrodes. They are formed by the photomask for the segment transparent electrodes at the same time when the transparent electrodes are formed.  
       [0012] To mount the control IC with the use of the alignment marks  105 , a liquid crystal display device is assembled and then is delivered to a mounting device for the control IC. Subsequently, a sensor inside the mounting device senses the positions of the alignment marks  105 ,  105  from under the first transparent substrate  101 , and the liquid crystal display device is fixed at a predetermined position of a jig inside the mounting device for positioning based on position data at this time. In this state, the control IC  103  is placed on the exposed surface  101   a  through an anisotropic conductive tape, and the terminals of the control IC are positioned and bonded to the electrode pads  104   a  of the exposed surface  101   a.    
       [0013] Therefore, to mount the control IC  103  highly accurately, the relative positions of the alignment marks  105  to the electrode pads  104   a  are required to be highly accurate.  
       SUMMARY OF THE INVENTION  
       [0014] However, in the traditional liquid crystal display device, the alignment marks  105  made of ITO are formed by using the photomask separate from that used for forming the electrode pads  104   a  made of the metal film, as described above. Thus, the alignment marks  105  are sometimes formed at positions (the positions indicated by a dashed line in FIG. 15) slightly shifted from the original positions. There is a problem that the positions of the alignment marks are slightly shifted to cause the position of mounting the control IC  103  to be shifted to the position surrounded by a long dashed double-short dashed line in accordance with this, and the terminals of the control IC  103  cannot be bonded to predetermined electrode pads  104   a.    
       [0015] In addition, since the opaque anisotropic conductive tape is interposed between the terminals of the control IC  103  and the electrode pads  104   a , the terminals cannot be visually recognized from under the substrate  101  directly. Consequently, a bonding state of the terminals to the electrode pads  104   a  cannot be directly observed. Therefore, the bonding state is inspected by testing whether they are electrically connected. On this account, a unit for confirming the bonding state of the terminals to the electrode pads by direct observation is sought.  
       [0016] The invention has been made in view of the circumstances. An object is to provide a liquid crystal display device in which the control IC  103  can be mounted highly accurately and the bonded state of the control IC  103  can be observed easily, and a manufacturing method of the liquid crystal display device.  
       [0017] In order to achieve the object, the-invention adopted the configurations below.  
       [0018] A liquid crystal display device of the invention is characterized by having:  
       [0019] a pair of substrates facing each other with a liquid crystal layer sandwiched;  
       [0020] transparent electrodes disposed on surfaces of the substrates on a side of the liquid crystal layer;  
       [0021] interconnect wirings for drawing each of the transparent electrodes to one of the substrates; and  
       [0022] a control circuit device disposed on the one substrate and connected to the interconnect wirings,  
       [0023] wherein at least a part or all of the interconnect wirings are configured by laminating a metal film on a part or all of an ITO film,  
       [0024] alignment marks to be reference for positioning the control circuit device are formed on both sides of the control circuit device on the substrate, and  
       [0025] the alignment marks are formed of a same component material as that of the metal film of the interconnect wirings.  
       [0026] In addition, a liquid crystal display device of the invention is characterized in that the alignment marks and the metal film of the interconnect wirings are formed at the same time.  
       [0027] Furthermore, a liquid crystal display device of the invention is characterized in that the alignment marks and the metal film of the interconnect wirings are formed by forming the metal film on the one substrate and then patterning the metal film with a same mask.  
       [0028] According to the liquid crystal display device, the alignment marks and the metal film of the interconnect wirings are formed at the same time. Therefore, the relative positions of the alignment marks to the interconnect wirings can be set constant. Accordingly, the position to mount the control circuit device can be determined accurately.  
       [0029] Moreover, the alignment marks are made of the same component material as that of the metal film of the interconnect wirings. Thus, the alignment marks can be recognized along with the control circuit device from the side where the alignment marks are formed, and the control circuit device can be positioned accurately.  
       [0030] In addition, a liquid crystal display device of the invention is the liquid crystal display device as set forth, and is characterized in that an electrode pad made of the metal film to be connected to a terminal of the control circuit device is formed at tip ends of the interconnect wirings, and the alignment marks and the electrode pads are formed at the same time.  
       [0031] According to the liquid crystal display device, the alignment marks and the electrode pads are formed at the same time. Therefore, the relative positions of the alignment marks to the electrode pads can be set constant. Accordingly, the terminals of the control circuit device can be accurately positioned and bonded to the electrode pads.  
       [0032] Furthermore, a liquid crystal display device of the invention is the liquid crystal display device as set forth, and is characterized in that the electrode pads and the alignment marks are formed by forming a metal layer on the one substrate and then patterning the metal layer with a same mask.  
       [0033] According to the liquid crystal display device, the electrode pads and the alignment marks are formed by the same mask. Thus, the relative positions of the alignment marks to the electrode pads can be set constant.  
       [0034] Next, a manufacturing method of a liquid crystal display device of the invention, the liquid crystal display device having a pair of substrates facing each other with a liquid crystal layer sandwiched, transparent electrodes disposed on surfaces of the substrates on a side of the liquid crystal layer, interconnect wirings for drawing each of the transparent electrodes to one of the substrates, and a control circuit device disposed on the one substrate and connected to the interconnect wirings, the manufacturing method is characterized by including:  
       [0035] forming a metal layer on the one substrate and then patterning the metal layer with a same mask to form alignment marks to be reference for positioning the control circuit device on both sides of the control circuit device at the same time when the interconnect wirings are formed.  
       [0036] According to the manufacturing method of the liquid crystal display device, the alignment marks and the metal film of the interconnect wirings are formed at the same time. Therefore, the relative positions of the alignment marks to the interconnect wirings can be set constant. Accordingly, the position to mount the control circuit device can be determined accurately.  
       [0037] Additionally, the alignment marks are made of the metal film. Therefore, the alignment marks can be recognized along with the control circuit device from the side where the alignment marks are formed, and the control circuit device can be positioned accurately.  
       [0038] Furthermore, a manufacturing method of the liquid crystal display device of the invention is the manufacturing method of the liquid crystal display device as set forth, and is characterized in that an electrode pad made of the metal film to be connected to a terminal of the control circuit device is formed at tip ends of the interconnect wirings, and the alignment marks and the electrode pads are formed at the same time.  
       [0039] According to the manufacturing method of the liquid crystal display device, the alignment marks and the electrode pads are formed at the same time. Therefore, the relative positions of the alignment marks to the electrode pads can be set constant. Accordingly, the terminals of the control circuit device can be accurately positioned and bonded to the electrode pads.  
       [0040] Moreover, a liquid crystal display device of the invention is the liquid crystal display device as set forth, and is characterized in that the electrode pads and the alignment marks are formed by patterning the metal layer with the mask.  
       [0041] According to the manufacturing method of the liquid crystal display device, the electrode pads and the alignment marks are formed with the same mask. Therefore, the relative positions of the alignment marks to the electrode, pads can be set constant.  
       [0042] A liquid crystal display device of the invention is characterized by having:  
       [0043] a pair of transparent substrates facing each other with a liquid crystal layer sandwiched;  
       [0044] transparent electrodes disposed on surfaces of the transparent substrates on a side of the liquid crystal layer;  
       [0045] interconnect wirings for drawing each of the transparent electrodes to one of the transparent substrates; and  
       [0046] a control circuit device disposed on the one transparent substrate and connected to the interconnect wirings,  
       [0047] wherein the control circuit device is formed with a dummy terminal not to be connected to the interconnect wiring,  
       [0048] an electrode pad to be connected to an original terminal of the control circuit device is formed at a tip end of each of the interconnect wirings, and  
       [0049] an island transparent dummy pad to be connected to the dummy terminal of the control circuit device is disposed, the island transparent dummy pad is adjacent to the electrode pad but separate from the interconnect wiring.  
       [0050] According to the liquid crystal display device, the island transparent dummy pad to be connected to the dummy terminal of the control circuit device, the island transparent dummy pad is adjacent to the electrode pad but separate from the interconnect wiring. Therefore, a bonding state of the dummy terminal to the transparent dummy pad can be visually recognized from the side where the interconnect wirings are not disposed on the one transparent substrate. Accordingly, the bonding state of the electrode pads to the original terminals can be estimated from a bonding state of the transparent dummy pad to the dummy terminal, and a bonded state of the control circuit device can be visually recognized through the transparent dummy pad.  
       [0051] In addition, a liquid crystal display device of the invention is the liquid crystal display device as set forth. Preferably, at least a part or all of the interconnect wirings are configured by laminating a metal film on a part or all of an ITO film, the electrode pad is formed of at least the metal film, and the transparent dummy pad is formed of ITO.  
       [0052] According to the liquid crystal display device, at least a part or all of the interconnect wirings are formed by laminating the metal film on a part or all of the ITO film. Therefore, the conductivity of the interconnect wirings is improved to prevent display unevenness of the liquid crystal display device from being generated.  
       [0053] Moreover, the electrode pads are formed of the metal film. Therefore, resistance between the interconnect wirings and the control circuit device can be reduced. In addition to this, the transparent dummy pad is formed of ITO. Therefore, a bonding state of the dummy terminal to the transparent dummy pad can be visually recognized from the side where the interconnect wirings are not disposed on the one transparent substrate.  
       [0054] Furthermore, a liquid crystal display device of the invention is the liquid crystal display device as set forth, and is characterized in that alignment marks made of the metal film to be reference for positioning the control circuit device are formed on both sides of the control circuit device on the transparent substrate, and the alignment marks and the electrode pads are formed at the same time.  
       [0055] According to the liquid crystal display device, the alignment marks are formed of the metal film and are formed at the same time with the electrode pads. Therefore, the relative positions of the alignment marks to the electrode pads can be set constant. Accordingly, the terminals of the control circuit device can be accurately positioned and bonded to the electrode pads.  
       [0056] Moreover, a liquid crystal display device of the invention is the liquid crystal display device as set forth, and is characterized in that the electrode pads and the alignment marks are formed by forming a metal layer on the one transparent substrate and then patterning the metal layer with a same mask.  
       [0057] According to the liquid crystal display device, the electrode pads and the alignment marks are formed by the same mask. Therefore, the relative positions of the alignment marks to the electrode pads can be set constant.  
       [0058] Next, a manufacturing method of a liquid crystal display device of the invention, the liquid crystal display device having a pair of transparent substrates each other with a liquid crystal layer sandwiched, transparent electrodes disposed on surfaces of the transparent substrates on a side of the liquid crystal layer, interconnect wirings for drawing each of the transparent electrodes to one of the transparent substrates, and a control circuit device disposed on the one transparent substrate and connected to the interconnect wirings, the manufacturing method is characterized by including:  
       [0059] forming the transparent electrodes, an ITO film to be connected to the transparent electrodes for drawing the transparent electrodes to one side of the one transparent substrate, and a transparent dummy pad made of ITO are formed at the same time; and  
       [0060] forming a metal layer on the one transparent substrate and then patterning the metal layer with a same mask to laminate the metal film on the ITO film to form the interconnect wirings and the electrode pads.  
       [0061] According to the manufacturing method of the liquid crystal display device, the metal film of forming the interconnect wirings and the electrode pads are formed at the same time. Therefore, the relative positions of the interconnect wirings to the electrode pads can be set constant. Accordingly, the position to mount the control circuit device can be determined accurately.  
       [0062] In addition, a manufacturing method of the liquid crystal display device of the invention is the manufacturing method of the liquid crystal display device as set forth, and is characterized in that alignment marks to be reference for positioning the control circuit device are formed on both sides of the control circuit device at the same time when the metal layer is patterned.  
       [0063] According to the manufacturing method of the liquid crystal display device, the alignment marks are formed at the same time when the metal layer is patterned. Therefore, the relative positions of the alignment marks to the electrode pads can be set constant. Accordingly, the terminals of the control circuit device can be accurately positioned and bonded to the electrode pads.  
       [0064] As described above in detail, according to the liquid crystal display device of the invention, the island transparent dummy pad to be connected to the dummy terminal of the control circuit device is disposed, the island transparent dummy pad is adjacent to the electrode pad but separate from the interconnect wiring. Therefore, the bonding state of the dummy terminal to the transparent dummy pad can be visually recognized from the side where the interconnect wirings are not disposed on the one transparent substrate. Accordingly, the bonding state of the electrode pads to the original terminals can be estimated from the bonding state of the transparent dummy pad to the dummy terminal, and the bonded state of the control circuit device can be visually recognized through the transparent dummy pad.  
       [0065] In addition, according to the liquid crystal display device of the invention, the alignment marks and the metal film of the interconnect wirings are formed at the same time. Therefore, the relative positions of the alignment marks to the interconnect wirings can be set constant. Accordingly, the position to mount the control circuit device can be determined accurately.  
       [0066] Furthermore, the alignment marks are made of the metal film. Therefore, the alignment marks can be recognized along with the control circuit device from the side where the alignment marks are formed, and the control circuit device can be positioned accurately.  
       [0067] Accordingly, it leads to improved productivity and enhanced yields in assembly processes. 
     
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
     [0068] The teachings of the invention can be readily understood by considering the following detailed description in conjunction with the accompanying drawings, in which:  
     [0069]FIG. 1 is an exploded perspective view illustrating a liquid crystal display device of the embodiment according to the invention;  
     [0070]FIG. 2 is an enlarged plan view illustrating an exposed surface on one substrate, which is an essential part of the liquid crystal display device of the embodiment according to the invention;  
     [0071]FIG. 3 is a schematic cross-sectional view illustrating the interconnection part of a control IC, which is an essential part of the liquid crystal display device of the embodiment according to the invention;  
     [0072]FIG. 4 is a schematic plan view illustrating the interconnection part of the control IC, which is an essential part of the liquid crystal display device of the embodiment according to the invention;  
     [0073]FIG. 5 is a process drawing illustrating a manufacturing method of a substrate of the liquid crystal display device of the embodiment according to the invention;  
     [0074]FIG. 6 is a cross-sectional view along line  6 - 6  shown in FIG. 5;  
     [0075]FIG. 7 is a cross-sectional view along line  7 - 7  shown in FIG. 5;  
     [0076]FIG. 8 is a process drawing illustrating the manufacturing method of the substrate of the liquid crystal display device of the embodiment according to the invention;  
     [0077]FIG. 9 is a cross-sectional view along line  9 - 9  shown in FIG. 8;  
     [0078]FIG. 10 is a cross-sectional view along line  10 - 10  shown in FIG. 8;  
     [0079]FIG. 11 is a perspective cross-sectional view illustrating one example of interconnect wirings of the liquid crystal display device of the embodiment according to the invention;  
     [0080]FIG. 12 is a cross-sectional view illustrating another example of the interconnect wirings of the liquid crystal display device of the embodiment according to the invention;  
     [0081]FIG. 13 is an enlarged plan view illustrating another example of the exposed surface of one substrate;  
     [0082]FIG. 14 is a perspective view illustrating the traditional liquid crystal display device; and  
     [0083]FIG. 15 is a plan view illustrating an essential part of the traditional liquid crystal display device. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT  
     [0084] Hereafter, an embodiment of the invention will be described with reference to the drawings.  
     [0085]FIG. 1 is a simple matrix liquid crystal display device of an embodiment according to the invention, and FIG. 2 depicts a plan view illustrating an essential part of the liquid crystal display device of the embodiment.  
     [0086] As shown in FIG. 1, a liquid crystal display device  1  of the embodiment is mainly configured of a pair of transparent substrates (first and second transparent substrates)  11  and  12  facing each other with a liquid crystal layer sandwiched, not shown, and a control IC  13  disposed on an exposed surface  11   a  of the first substrate  11 . The first substrate  11  is formed longer in length than the second substrate  12 . The portion extending off the second substrate  12  is the exposed surface  11   a,  and the portion facing the second substrate  12  is a display area surface  11   b.  The entire surface of the second substrate  12  facing the first substrate  11  is a display area surface  12   b.    
     [0087] As shown in FIG. 1, on the display area surfaces  11   b  and  12   b  of the substrates  11  and  12 , segment transparent electrodes  21  and common transparent electrodes  31  are formed, respectively. The transparent electrodes  21  and  31  are that a plurality of flat strips made of a transparent conductive film such as ITO is arranged. They are separately connected to the control IC  13  for driving liquid crystal molecules configuring the liquid crystal layer. The transparent electrodes  21  and  31  are disposed orthogonal to each other when seen in plane, and the liquid crystal display device  1  is a passive matrix type.  
     [0088] Not shown in the drawing, on each of the display area surfaces  11   b  and  12   b  of the first and second substrates  11  and  12 , an overcoat film for planarizing recesses and projections generated by the transparent electrodes  21  and  31  and an alignment layer for controlling the alignment of liquid crystal molecules configuring the liquid crystal layer are formed. In addition to this, a color filter and a reflector are formed on the display area surface  11   b.    
     [0089] On the first substrate  11 , interconnect wirings  14  for connecting the transparent electrodes  21  to the control IC  13  are drawn from the display area surface  11   b  toward the exposed surface  11   a  (a side  11   c ). The interconnect wirings  14  are formed of an ITO film and a metal film in which at least a part of the metal film is overlapped with the ITO film.  
     [0090] On the second substrate  12 , a plurality of upper electrodes  32  is formed in a row along a side  12   c.  Additionally, on the second substrate  12 , second interconnect wirings  33  for connecting the transparent electrodes  31  to the upper electrodes  32  are formed.  
     [0091] On the display area surface  11   b  of the first substrate  11 , lower electrodes  34  are formed. The lower electrodes  34  are formed at positions corresponding to the positions of the upper electrodes  32 . On the first substrate  11 , first interconnect wirings  35  for connecting the lower electrodes  34  to the control IC  13  are drawn from the display area surface  11   b  toward the exposed surface  11   a  (the side  11   c ). An anisotropic conductive resin layer  36  is disposed between the upper electrodes  32  and the lower electrodes  34 . The anisotropic conductive resin layer  36  contains conductive particles made of metal. The conductive particles are sandwiched between the upper and lower electrodes  32  and  34 , and then the upper and lower electrodes  32  and  34  are electrically connected.  
     [0092] Accordingly, the transparent electrodes  31  on the second substrate  12  are electrically connected to the control IC  13  through the second interconnect wirings  33 , the upper electrodes  32 , the anisotropic conductive resin layer  36 , the lower electrodes  34 , and the first interconnect wirings  35 .  
     [0093] The second interconnect wirings  33  and the first interconnect wirings  35  are all formed of the ITO film and the metal film as similar to the interconnect wirings  14  in which at least a part of the metal film is overlapped with the ITO film.  
     [0094] Next, as shown in FIGS. 2 and 3, island electrode pads  14   a  and  35   a  formed by drawing the metal film are disposed at the tip ends of the interconnect wirings  14  and  35 , respectively.  
     [0095] On both sides of the electrode pads  14   a  and  35   a  in the horizontal direction, four transparent dummy pads  20  . . . are formed. The transparent dummy pads  20  are made of a transparent material such as ITO, which are formed into an island shape on the exposed surface  11   a.    
     [0096] As shown in FIGS. 3 and 4, the control IC  13  is configured of a nearly rectangular sealing main part  13   a  having a semiconductor device incorporated therein when seen in plane and terminals  13   b  formed of solder balls formed on the lower surface of the sealing main part  13   a.  The terminals  13   b  include original terminals  13   b   1  electrically connected to the semiconductor device inside the sealing main part  13   a  and dummy terminals  13   b   2  not to be connected to the semiconductor device. The dummy terminals  13   b   2  are disposed at positions corresponding to the transparent dummy pads  20 .  
     [0097] As shown in FIGS. 3 and 4, the terminals  13   b  of the control IC  13  are separately bonded to the electrode pads  14   a  and  35   a  and the transparent dummy pads  20  through the anisotropic conductive resin layer  36 . Among the terminals  13   b,  the original terminals  13   b   1  are electrically connected to the electrode pads  14   a  and  35   a  and the dummy terminals  13   b   2  are connected to the transparent dummy pads  20 .  
     [0098] When the terminals  13   b  are pressed onto the electrode pads  14   a  and  35   a  and the transparent dummy pads  20  through the anisotropic conductive resin layer  36 , the conductive particles contained in the anisotropic conductive resin layer  36  are sandwiched and compressed between the terminals  13   b  and the electrode pads  14   a  and  35   a  and the transparent dummy pads  20 . Consequently, electrical interconnection is secured. The state that the conductive particles are compressed can be visually recognized easily through the transparent dummy pads  20  from under the substrate  11 . Additionally, the bonding state can be confirmed as well by counting the number of the conductive particles bonded to a single transparent dummy pad  20 .  
     [0099] The bonding state of the electrode pads  14   a  and  35   a  to the original terminals  13   b   1  can be estimated to be almost similar to the bonding state of the transparent dummy pads  20  to the dummy terminals  13   b   2 . Accordingly, the bonded state of the control IC  13  can be visually recognized through the transparent dummy pads  20 .  
     [0100] As shown in FIGS.  2  to  4 , on both sides of the control IC  13  on the exposed surface  11   a,  alignment marks  15 ,  15  are formed that are the reference for positioning the control IC  13  in mounting the control IC  13  on the first substrate  11 . The alignment marks  15 ,  15  are formed of an opaque metal film as similar to the electrode pads  14   a  and  35   a,  for example, and are formed by the photomask at the same time when the electrode pads  14   a  and  35   a  are formed.  
     [0101] Therefore, the relative positions of the alignment marks  15 ,  15  to the electrode pads  14   a  and  35   a  are highly accurate, and variations in every liquid crystal display device are reduced.  
     [0102] To use the alignment marks  15  to mount the control IC  13 , a liquid crystal display device is assembled and then delivered to a mounting device for the control IC. Subsequently, a sensor inside the mounting device senses the positions of the alignment marks  15 ,  15  from under the first transparent substrate  11 , and then the liquid crystal display device is positioned at a predetermined position of a jig inside the mounting device based on position data at this time. In this state, the control IC  13  is placed on the exposed surface  11   a  through an anisotropic conductive tape, and the terminals of the control IC  13   b  are positioned and bonded to the electrode pads  14   a  and  35   a  on the exposed surface  11   a.    
     [0103] As shown in FIGS. 3 and 4, in positioning the position of the control IC  13 , sensor C inside the mounting device senses the relative positions of the sealing main part  13   a  of the control IC  13  to the alignment marks  15 ,  15  for positioning as the relative positions are put in contrast with predetermined reference position data of the control IC  13 .  
     [0104] More specifically, distances X1 and X2 between the alignment marks  15 ,  15  and sides  13   c  along the short sides of the sealing main part  13   a  of the control IC  13  and distances Y1 and Y2 between the alignment marks  15 ,  15  and an elongation of a side  13   d  along the long sides of the sealing main part  13   a  are measured and put in contrast with the reference data for positioning.  
     [0105] Since the relative positions of the alignment marks  15 ,  15  to the electrode pads  14   a  and  35   a  are accurately positioned, the relative positions of the sealing main part  13   a  of the control IC  13  to the alignment marks  15 ,  15  are matched to accurately position the terminals  13   b  of the control IC  13  to the electrode pads  14   a  and  35   a.    
     [0106] Next, a manufacturing method of the electrode pads  14   a  and  35   a  and the transparent dummy pads  20  including the alignment marks  15 ,  15  and the interconnect wirings  14  and  35  (a manufacturing method of the liquid crystal display device) will be described.  
     [0107] As shown in FIGS.  5  to  7 , the transparent electrodes  21  made of ITO are formed on the first substrate  11  where the color filter and the reflector have been formed beforehand, and ITO films  141  and  351  forming the interconnect wirings, ITO pads  14   a   1  at the tip ends of the ITO films  141 , ITO lower electrodes  341  at the base ends of the ITO films  351 , and ITO pads  35   a   1  at the tip ends of the ITO film  351  are formed. In addition, the transparent dummy pads  20  made of ITO adjacent to the ITO pads  35   a   1  are formed.  
     [0108] All of them are formed by laminating an ITO layer and a photoresist throughout the surface of the first substrate  11 , layering a photomask for patterning, and exposing them to remove the photomask and the photoresist.  
     [0109] Next, as shown in FIGS.  8  to  10 , metal film M is formed on the ITO films  141  and  351  forming the interconnect wirings, the ITO pads  14   a   1  and  35   a   1 , and the ITO lower electrodes  341 , and the alignment marks  15 ,  15  made of the metal film are formed.  
     [0110] The metal film and the alignment marks  15  are all formed by laminating a metal layer and a mask for patterning throughout the surface of the first substrate  11 , and etching and patterning the metal layer to remove the mask.  
     [0111] Furthermore, the metal film is not formed on the transparent dummy pads  20 .  
     [0112] In this manner, the electrode pads  14   a  and  35   a  and the alignment marks  15  including the transparent electrodes  21  and the interconnect wirings  14  and  35  are formed on the first substrate  11 . The interconnect wirings  14  and  35 , the electrode pads  14   a  and  35   a,  and the lower electrodes  34  are all formed by laminating the ITO film and the metal film. The alignment marks  15  are formed of the metal film separately. The transparent dummy pads  20  are formed of the ITO film separately.  
     [0113] The alignment marks  15 ,  15  are formed by the mask used in forming the metal film at the same time when the metal film is formed. Accordingly, the relative positions of the alignment marks  15  to the electrode pads  14   a  and  35   a  can be positioned accurately.  
     [0114] More specific exemplary configurations of the interconnect wiring  14 ,  35  thus formed are shown in FIGS. 11 and 12.  
     [0115] In an interconnect wiring  14 ,  35  shown in FIG. 11, an ITO film  141 ,  351  is formed on a substrate  11 , metal film M is laminated throughout the surface of the ITO film  141 ,  351 , and the metal film M is formed along the ITO film  141 ,  351 .  
     [0116] In an interconnect wiring  14 ,  35  shown in FIG. 12, an ITO film  141 ,  351  is formed on a substrate  11 , a part of metal film M is laminated on the ITO film  141 ,  351 , and the metal film M is formed along the ITO film  141 ,  351 .  
     [0117] In FIGS. 11 and 12, it is acceptable that the metal film M is formed on the substrate  11  and a part or all of the ITO film  141 ,  351  is laminated on the metal film M.  
     [0118] A part or all of the metal film is laminated on the ITO film, and thus low conductivity of the ITO film can be compensated by the high conductive metal film. Accordingly, resistance of the interconnect wirings  14  and  35  is reduced to prevent display unevenness from being generated in the liquid crystal display device.  
     [0119] In the embodiment, four transparent dummy pads  20  were disposed at four corners of the control IC  13 , but the invention is not limited to this. For example, as shown in FIG. 13, it is fine to dispose them at arbitrary positions between the electrode pads  14   a  and  35   a.  Furthermore, as shown in FIG. 13 the number of the transparent dummy pads  20  is not necessarily four. For example, to dispose three dummy pads is acceptable.