7/15/85
`
`0?
`
`4,600,275
`
`United States Patent
`Ohno
`
`[193
`
`[11] Patent Number:
`
`4,600,273
`
`{45] Date of Patent:
`
`Jul. 15, 1986
`
`[54] DISPLAY PANEL HAVING CONDUCTIVE
`CONTACT MEDIA
`
`[75]
`
`Inventor: Yoshihiro Ohno, Suwa, Japan
`
`[73] Assignee:
`
`Seiko Epson Corporation, Tokyo,
`Japan
`
`[21]
`
`' App]. No.: 486,608
`
`[22] Filed:
`
`Apr. 19, 1983
`
`Foreign Application Priority Data
`[30]
`Apr. 20, 1982 [JP]
`Japan .................................. 57-65698
`
`Int. Cl.“ ................................................ G02F 1/13
`[5]]
` [52] US. Cl. .................. 350/336; 350/343;
`350/344
`[58] Field of Search ........................ 350/336, 344, 343
`
`[56]
`
`References Cited
`U.S. PATENT DOCUMENTS
`
`4,308,533 12/1981 Schmidt .......................... 350/343 X
`4,362,771 12/1982 Umeda et al.
`.................. 350/344 X
`
`FOREIGN PATENT DOCUMENTS
`
`2602183
`2034095
`
`3/1977 Fed. Rep. of Germany ...... 350/344
`5/1980 United Kingdom ................ 350/344
`
`Primary Examiner—John K. Corbin
`Assistant Examiner—Richard F. Gallivan
`Attorney, Agent, or Firm—Blum Kaplan Friedman
`Silberman and Beran
`
`ABSTRACT
`[57]
`A liquid crystal display panel comprising opposed sub-
`strates, electrodes on the inside opposed surfaces of said
`substrates and arranged opposite to each other to sand-
`wich a display layer, a contact media for electrically
`connecting an electrode on one substrate with an elec-
`trode on the other substrate and disposed between said
`electrodes of said substrates, and a binder between said
`substrates and fixably engaging said contact media with
`said electrodes, the diameter of said contact media se-
`lected to be substantially the same as the thickness of a
`liquid crystal cell layer. The contact media comprises a
`non-conductive core electroless plated with a conduct-
`ing metal.
`
`15 Claims, 8 Drawing Figures
`
`/fl6
`
`
`
`Exhibit 1005 - page 1
`
`Exhibit 1005 - page 1
`
`

`

`US. Patent
`
`Jul. 15, 1986
`
`Sheet 1 of3
`
`4,600,273
`
`FIG?
`
`
`
`Exhibit 1005 - page 2
`
`Exhibit 1005 - page 2
`
`

`

`U.S. Patent
`
`Jul. 15, 1986
`
`Sheet 2 of3
`
`4,600,273
`
` mT\‘\‘\““““\‘\‘\‘
`
`7‘76???
`
`2.197205”)
`;‘\“““\\\\\\\\\w
`22 '24
`
`F/G.5
`
`F/G.6
`
`-\"\\‘\‘\\\\\\\‘.\\‘\\\‘
`
`
`I V/Ilizf/A‘I'Iiz'
`
`4 V9}; \9
`
`
`
`Exhibit 1005 - page 3
`
`Exhibit 1005 - page 3
`
`

`

`US. Patent
`
`Jul. 15,1986
`
`Sheet3 0f3
`
`4,600,273
`
`
`
`Exhibit 1005 - page 4
`
`Exhibit 1005 - page 4
`
`

`

`1
`
`DISPLAY PANEL HAVING CONDUCTIVE
`CONTACT MEDIA
`
`BACKGROUND OF THE INVENTION
`
`This invention relates to a display panel having con-
`ductive contact media disposed between upper and
`lower electrodes which function as the gap material
`between the electrodes and more particularly to a liquid
`crystal display panel having improved electrical
`contacts between the upper and lower electrodes, and
`improved display quality, speed and color.
`Conventional
`liquid crystal display panels have a
`spacing, or gap, between upper and lower electrode
`bearing substrates. A common electrode, generally of a
`metal, is in electrical contact with the electrodes of each
`substrate. In general, a soft metal, e.g. indium, is utilized
`as the electrical connection between the upper and
`lower substrates. In order to provide this connection,
`the soft metal is placed into a gap created in one sub-
`strate and then the two substrates are forced into paral-
`lel, opposed alignment, spaced apart by the soft metal.
`One disadvantage of this structure and method is the
`tendency toward contact failure between the soft metal
`and the electrodes. To overcome this defect resinous
`adhesive agent including a conductive metal, e.g. silver,
`has been printed on either the upper or lower substrate
`prior to construction ofthe panel. This resinous agent is
`generally applied in the form of a paste. However, unac-
`ceptably high proportions of electrical contact failure
`betweenthe upper and lower electrodes when using
`such pastes are known. These failures occur during the
`necessary steps undertaken in the process of manufac-
`turing a liquid crystal panel. To manufacture a panel, a
`matrix of panel substrates is formed on a master sub-
`strate and then each panel substrate is separated by
`mechanical means. In a conventional construction, a
`conductive resinous adhesive silver paste is positioned
`on each individual substrate panel prior to the separa—
`tion step, When the force necessary to separate each
`individual panel is applied, the silver paste in the adhe-
`sive material tends to disassociate itselftherefrom. As a
`result, when the individual substrates are brought into
`opposition, contact failure sometimes occurs between
`the upper and lower substrates. The contact failure can
`be adhesive or electrical in nature. When the adhesive
`resin content of the silver paste is increased, it becomes
`difficult
`to maintain the silver particles in electrical
`contact with each other. This results in unacceptable
`levels of contact failure between the upper and lower
`electrodes. Conversely, if the concentration of the sil-
`ver particles in the silver paste is increased to overcome
`this drawback, the adhesive properties of the paste are
`diminished, thereby also causing unacceptable rates of
`contact
`failure. Optimum ratios of resins and silver
`particles, even when mixed properly, do not exist, since
`variations in conditions such as humidity and tempera-
`ture of manufacture, as well as drying temperature, all
`cause variations in the properties of the silver paste
`product. Furthermore, the average particle diameter of
`the silver particles in the silver paste varies. It is gener-
`ally more than about seven microns, although particles
`smaller than this size do regularly appear. Additionally,
`the shape of the particles also varies. Thus, two particles
`can be generally of the same size, but differ enough in
`shape to effect the alignment of the opposed display
`panels. This variation in particle sizes and shapes causes
`
`4,600,273
`
`2
`great difficulty in aligning in parallel the opposed sub-
`strate plates.
`SUMMARY OF THE INVENTION
`
`5
`
`10
`
`15
`
`20
`
`25
`
`30
`
`35
`
`40
`
`45
`
`50
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`55
`
`60
`
`65
`
`The disadvantages of the art can be overcome by
`providing a contact media which generally comprises a
`non-conductive core material disposed between the
`upper and lower electrodes of the display panel. The
`core material is made conductive by electroless plating
`thereon of one or more conductive materials. The diam-
`eter of the coated core materials is selected to be almost
`the same as, or slightly larger than, the gap between the
`upper and lower liquid crystal panel electrodes of the
`display. The non-conductive core particles, such as
`glass beads, glass fibers, or plastic balls, can be formed
`by injection-molding or by cooling after
`they are
`melted and passed through an orifice, having a fixed
`diameter. It is, therefore, possible to mass-produce par-
`ticles having a uniform diameter. As a result, cell thick-
`ness can be made uniform and the cost of manufacture
`can be reduced.
`In accordance with the invention, a conductive
`contact media is disposed between the upper and lower
`electrodes to provide electrical contact and consistent
`spacing between the electrodes on the upper and lower
`panels. The media has a relatively uniform, predeter-
`mined thickness. The contact media acts as a gap mate-
`rial, providing uniformity to the thickness of the display
`cell. It also imparts effective, reliable electrical contact
`between the upper and lower electrodes. The contact
`media includes a non-conductive core material, such as
`glass fiber, glass beads, inorganic glass beads or plastic
`fiber or beads. These core materials are electroless
`plated with a conductive metal. The contact media also
`includes alumina fiber and beads. They are then dis-
`posed in a resinous adhesive material. The material is
`sandwiched between the electrodes on the upper and
`lower substrate panels.
`cores
`The
`adhesive
`containing the metallized
`(contact media) is placed on the contact portion be-
`tween the upper and lower electrodes of the liquid
`crystal panel by printing or dropping onto an electrode
`before it is incorporated into the liquid crystal panel
`Generally, glass is utilized as the substrate of the
`liquid crystal panel. However,
`it is possible to use a
`plastic film wherein a transparent electrode (SnOz, In-
`203, etc.) is patterned. When using plastic film,
`the
`contact portion of the contact media between the upper
`and lower electrodes is depressed by pressure when the
`liquid crystal panel is assembled. The contact area of the
`electrodes with the contact media between upper and
`lower electrodes increases, which results in increased
`adhesion.
`When the non-conductive core comprises a relatively
`hard material, such as glass fibers, glass beads or hard
`plastic fibers or beads, its diameter should be about that
`of the cell thickness. When the core comprises a soft
`plastic its diameter should be no more than about 1.0 to
`about 1.3 times the thickness of the cell.
`
`Accordingly, it is an object of the invention to pro-
`vide an improved liquid crystal panel.
`Another object of the invention is to provide an im-
`proved contact media between the upper and lower
`electrodes of a liquid crystal panel.
`A further object of the invention is to provide contact
`media between the upper and lower electrodes which
`are made conductive by providing a non-conductive
`core and thereupon electroless plating to the core a
`
`Exhibit 1005 - page 5
`
`Exhibit 1005 - page 5
`
`

`

`3
`conductive material, while providing predetermined
`diameters for the core material to enable the conductive
`contact media between the upper and lower electrode
`of the liquid crystal panel to have a relatively uniform
`thickness.
`Yet another object of the invention is to provide a
`conductive contact media which also functions as a gap
`material for the cell.
`Still other objects and advantages of the invention
`will in part be obvious and will in part be apparent from 10
`the specification.
`The invention accordingly comprises an article of
`manufacture possessing the features, properties and
`relation of elements which will be exemplified in the
`article hereinafter described, and the scope of the inven- 15
`tiOn will be indicated in the claims.
`
`5
`
`BRIEF DESCRIPTION OF THE DRAWINGS
`
`For a fuller understanding of the invention, reference
`is had to the following description taken in connection 20
`with the accompanying drawings, in which:
`FIG. 1 is a sectional view of a conventional display
`panel incorporating a soft metal contact between a com-
`mon electrode and a lead terminal;
`FIG. 2 is a sectional view of a conventional display 25
`panel including a silver paste contact media;
`FIG. 3 is a plan view of a matrix comprising rows and
`columns of display panel substrates;
`FIG. 4 is a sectional View of a portion of a display
`panel using silver paste as the electrically conductive 3O
`connective media;
`FIG. 5 is a sectional view of a portion of an electrical
`contact area of a display panel using an electroless
`plated hard core according to the invention;
`FIG. 6 is a sectional View of an electrical contact area 35
`of a display panel using an electroless plated soft core
`according to an alternate embodiment of the invention;
`FIG. 7 is a sectional View of a display panel including
`a liquid crystal display area and an electrical contact
`area in accordance with the invention; and
`FIG. 8 is a sectional view of a display panel including
`a liquid crystal display area and an electrical contact
`area according to an alternate embodiment ofthe inven-
`tion.
`
`40
`
`DESCRIPTION OF THE PREFERRED
`EMBODIMENTS
`
`45
`
`FIG. 1 is a sectional view of a conventional liquid
`crystal display panel having a soft metal contact be-
`tween the upper and lower substrates. A soft metal, 50
`such as indium 6,
`is utilized to conductively connect
`upper substrate 1 and lower substrate 2 through com-
`mon electrode 3 and lead terminal 5. The soft metal 6 is
`positioned by first locating an aperture 1a in the upper
`substrate 1. Soft metal contact 6 is inserted through the 55
`aperture 1a. Substrates 1 and 2 are compressed toward
`each other so that common electrode 3 is conductively
`connected to lead terminal 5 by soft metal 6. A gap
`spacing material 7,
`is disposed between the upper and
`lower substrates to help position them in a parallel 60
`spaced apart relation. Liquid crystal 8 is disposed gener-
`ally between the upper substrate 1 and lower substrate
`2.
`
`FIG. 2 discloses another conventional embodiment of
`a liquid crystal display panel. A resinous silver paste 9 is 65
`employed as the electrical contact media between the
`common electrode 3 and lead terminal 5. In this em-
`bodiment, there is no need for soft metal contact 6, or
`
`4,600,273
`
`4
`for an aperture la in substrate 1. Gap material 7 is dis-
`posed between upper substrate 1 and lower substrate 2.
`FIG. 3 discloses a matrix of liquid crystal display
`panels 10 in contiguous relationship. Each panel 10 is
`defined by rows 10a and columns 101) of scorelines. The
`respective panels 10 will be separated from each other,
`when appropriate force is applied at the score lines.
`FIG. 4 is a sectional view of the conductive portion
`ofa conventional display panel which uses a silver paste
`including silver particles 11, in an adhesive resin 12. The
`respective silver particles 11 are not uniform in size or
`shape. This lack of uniformity prevents the respective
`electrodes 21, 22 and substrate panels 23 and 24 from
`being properly aligned in parallel.
`With reference to FIG. 5, glass fiber core 13 is elec-
`troless plated with electrically conductive metal 130 to
`form a metallized glass fiber 50. Metallized fibers 50 are
`disposed in adhesive matrix 14. Matrix 14 acts as a
`binder between the metallized glass fibers 50 and elec-
`trodes 3] and 32 on substrates 33 and 34.
`If an elastic or soft core is to be used, e.g. a plastic
`bead or fiber, it is generally necessary to utilize a core
`having a diameter between I and 1.3 times as large as
`the thickness T of the gap between the upper and lower
`electrodes of the liquid crystal panels.
`The core to be electroless plated should be prepared
`for plating as follows. The surface should undergo al-
`kali-degreasing and then acid-neutralizing. Thereafter,
`the core should be sensitized in a SnClz solution in order
`to absorb Sn2+ ions onto its surface. The sensitized core
`material should then be subjected to an activation step.
`This activation is undertaken by contacting the sensi‘
`tized core with a PdClz solution to cause Pd0 to be
`present during electroless plating according to the fol-
`lowing formula.
`
`Sn2+ +Pd2+—>Sn‘+ + Pdo
`
`The Pd will act as a catalyst on the surface of the core
`for electroless plating.
`An electroless plating bath consists of a plating bath
`using at least one of the metals selected from the group
`consisting of gold, nickel, copper, silver, cobalt and tin.
`The metal having the best adhesive strength of this
`group is nickel, and accordingly an electroless nickel
`bath is most suitable for coating the core material. The
`actual electroless plating steps are undertaken in a hot
`electroless platingobath, accqrding to well-known steps.
`A layer of 200 A to 5000 A thickness is preferable for
`metallizing the core material of the liquid crystal panel.
`If the plating layer is under 200 A thick,
`it
`is of no
`practical use since the non-plated portion comes out on
`the core material and the resistance increases. If the
`plating layer is over 5000 A thick, the distance between
`the contact portions at the upper and lower electrodes
`and the thickness of the gap of liquid crystal panel can
`become more than 1 pm. When this occurs the liquid
`crystal
`layer becomes irregular and its color is non‘
`uniform, as a result of unevenness and the interference
`with light.
`A plating 200 A to 4 pm thick is preferable for metal-
`lizin a plastic ball or plastic fiber. If the plating is under
`200
`in thickness, it is of no practical use for the same
`reason as the case of the gap material. If the plating
`layer is over 4 pm thickness, the metal layer is too easily
`cracked when constructing the liquid crystal panel.
`This causes contact failure. It also becomes difficult to
`
`Exhibit 1005 - page 6
`
`Exhibit 1005 - page 6
`
`

`

`5
`control the gap thickness of the liquid crystal panel
`when plating layer is over 4 p.111 thick.
`If the resistance value is unacceptable when an elec-
`troless layer, such as a nickel, is deposited on the core
`material, a layer of precious metal having excellent
`electrical conductivity properties, such as silver or
`gold. can be electroless plated on the surface of the
`nickel. The layer of precious-metal plating is preferably
`between 50 A and l um thickness.
`The plated core material is added to the adhesive
`agent and dispersed uniformly therein prior to applica-
`tion to the substrate. Suitable compositions for the adhe-
`sive agent are epoxy resin, silicon resin, phenol resin,
`vinyl acetate resin, urea resin, vinyl chloride resin, re—
`sorcinol resin, acrylic resin, or other like synthetic res-
`ms.
`
`The amount of the metalized insulating material in
`the adhesive agent is preferably in the range of 0.1 wt.%
`to 50 wt%. If this amount is less than 0.1 wt%, resis-
`tance is too easily increased or uncontrollably varied. If
`the amount is more than 50 wt%, the adhesion proper-
`ties are decreased. The metallized core materials are
`preferably dispersed in the adhesive agent
`in plural,
`preferably in the range of 5 pieces to 500 pieces on one
`conductive, contact portion between the upper and
`lower electrodes of the liquid crystal panel. Amounts
`not in this range are generally unsuitable since conduc-
`tivity and adhesion cannot be properly controlled. The
`acceptable range will vary somewhat according to the
`diameter of the conducting material.
`FIG. 6 illustrates an embodiment of the invention
`including an elastic core 15, such as a plastic ball or a
`plastic fiber. Core 15 has a diameter larger than the
`thickness T] of the liquid crystal and is electroless
`plated with electrically conductive metal 15a to form
`metallized core 51. The metallized core 51 can be elasti-
`cally deformed if the thickness of the display panel
`varies. Thus, when the diameter of core 15 is greater
`than that of the gap T‘, the metallic surfaces 15a firmly
`contact the upper and lower electrodes 41 and 42 on
`substrates 43 and 44.
`If the diameter ofelastic core 15 is greater than about
`1.3 times as large as the thickness of the liquid crystal
`T1 the core will be substantially compressed upon con-
`struction of the display panel. This compression can
`cause a stress fracture of metal layer 15a, resulting in
`electrical contact
`failure. Therefore,
`the preferred
`range of diameters for an elastic core 15 to be electro-
`less plated with metal conductor is from about 1.1 to
`about 1.3 times as large as the thickness of the liquid
`crystal.
`
`EXAMPLE 1
`
`5
`
`IO
`
`15
`
`20
`
`25
`
`30
`
`35
`
`40
`
`45
`
`50
`
`55
`
`Glass fiber particles 5 pm in diameter were dipped in
`a ION solution of sodium hydroxide for 5 minutes, fil-
`tered, neutralized after being rinsed, and filtered again.
`When filtering these particles, a micro filter with a
`diameter of 1 pm is preferably used. The particles were
`then dispersed in a mixed solution of l g/lit. of SnClz
`and 1 cc/lit. HCl, filtered, rinsed and further dispersed
`in a water solution 0.5 g/lit. Pd C12, 1 cc/lit. 37% HO
`and stabilizer,
`(RED SUMER solution of JAPAN -
`KANIGEN Co., Ltd.), which was prepared according
`to known processes, filtered and rinsed again. Then, the
`glass fiber particles were dispersed for 6 minutes in a
`mixed solution of 20 g/lit. NiSOx; 25 g/lit. NaHzPOZ;
`30 g/liter of complexing agent of sodium malate, so-
`dium acetate
`and
`sodium citrate
`and
`15 g/lit.
`
`65
`
`4,600,273
`
`6
`(NH4)ZSO4 buffing agent, (S~680 solution of JAPAN
`KANIGEN Co., Ltd.), at 45° C., which was prepared
`according to known processes,1filtered and then rinsed.
`Electroless nickel--phosphorous plating formed a con‘
`ductive layer 3500 A thick on the glass fiber. The glass
`fiber particles with the electroless nickel-phosphorous
`plating layer were then dispersed in an epoxy resin in an
`amount of about 25 weight percent. This mixture was
`used as contact media between upper and lower elec-
`trodes ofa liquid crystal panel having a gap thickness of
`10 um and made of borosilicate glass. The resistance
`value was 9 KO. when measured through NESA glass to
`which the transparent conductive layer was attached.
`The resistance value remained unchanged after aging.
`EXAMPLE 2
`
`Following the procedures of Example 1, glass fiber
`particles of 7 pm in diameter were electroless plated
`with a nickel-phosphorus layer 2000 A thick. Then a
`layer of the nickel phosphorous 500 A thick was re-
`placed by goldin an ATOMEX electroless gold plating
`bath of NIPPON ENGELHARD Ltd. These glass
`fiber particles with a gold layer 500 A thick and a nick-
`el-phosphorus layer 1500 A thick were dispersed in
`epoxy resin in an amount of 5 weight percent. When
`using this mixture as the contact media between upper
`and lower electrodes for a liquid crystal panel, the resis-
`tance value was 8 K0. This value remained unchanged
`after performing a fixed aging test. Atomex bath in-
`cludes 5 g/L potassium gold cyanide and 20 g/L car-
`boxylic acid or carboxylic acid salt.
`EXAMPLE 3
`
`Glass fiber particles 7 11m in diameter coated follow-
`ing the procedures of Example 2 were dispersed in
`ultraviolet curing acrylic-resin in an amount of 15
`weight percent. The mixture was used as the contact
`media between upper and lower electrodes in a liquid
`crystal panel made of polyethylene film. The resistance
`value was 7 K0, which remained unchanged after the
`aging test.
`
`EXAMPLE 4
`
`Glass fiber particles 10 pm in diameter coated follow-
`ing the procedures of Example 2 were dispersed in
`silver paste in an amount of about 2 weight percent. The
`mixture was used as the contact media between upper
`and lower electrodes of a liquid crystal panel. The resis-
`tance value was smaller than that ofthe silver paste and
`remained unchanged after the aging test.
`EXAMPLE 5
`
`Following the procedures of Example 4, the glass
`fiber particles 12 pm in diameter were dispersed in the
`silver paste in an amount of about 10 weight percent and
`used as contact media between upper and lower elec-
`trodes for the liquid crystal panel. The same results as
`that of Example 4 were obtained.
`EXAMPLE 6
`
`Following the procedure of Example 1, alumina par-
`ticles 10 1.1m in diameter were electroless coated with a
`3000 A thickness of nickel-phosphous. Following the
`procedure of Example 2 a 600 A thickness of electro-
`less gold plate was formed on the 2400 A thickness of
`the nickel--phosphorus layer These alumina particles
`having a nickel-phosphorus layer and a gold layer were
`dispersed in an epoxy resin in an amount of about 10
`
`Exhibit 1005 - page 7
`
`Exhibit 1005 - page 7
`
`

`

`4,600,273
`
`8
`EXAMPLE 11
`
`7
`weight percent. This mixture was used as contact media
`between upper and lower electrodes. The resistance
`value was 8 K0, which value remained unchanged after
`the aging test.
`
`EXAMPLE 7
`
`10
`
`Styrene balls 12 pm in diameter were dipped in a
`chromic acid mixture for 5 minutes, filtered with a
`micro filter with pore diameters of 2 pm and rinsed.
`The styrene balls were dispersed in a mixed solution of
`l g/liter of SnClz and l cc/liter of HCl, filtered, rinsed
`and then dispersed in RED SUMER which was pre-
`pared according to known processes, filtered and rinsed
`again. After than, the styrene balls were dispersed for 6 [5
`minutes in 8-680 solution (45" C.) of JAPAN KANI-
`GEN Co., Ltd., which was prepared according to
`known steps; filtered and rinsed. A nickel—phosphorus
`layer 3500 A thick was formed on the styrene balls. The
`styrene balls with the nickel-phosphorus layer were 20
`dispersed in an epoxy resin in an amount of about 20
`weight percent. When using the mixture as contact
`media between upper and lower electrodes for the liq-
`uid crystal panel with a gap thickness of 10 pm, the
`resistance value at the contact portion of the upper and 25
`lower electrodes was 8 K0. That value remained un-
`changed after the fixed aging test.
`EXAMPLE 8
`
`Styrene balls coated following the procedures of 30
`Example 1, were dispersed in an ultraviolet curing acry-
`lic-resin in an amount of about 10 weight percent. The
`mixture was used as the contact media between upper
`and lower electrodes for the same liquid crystal panel as
`that of Example 1, which had a gap thickness of 10 pm,
`the resistance value at the contact portion between
`upper and lower electrodes was 9 K0. The value re-
`mained unchanged after the fixed again test.
`
`35
`
`EXAMPLE 9
`
`40
`
`Nylon balls of 10 pm in diameter were electroless
`nickle-phosphorus plated to a thickness of 2500 A fol-
`lowing the procedures of Example 1. Next, a portion of
`the nickel-phosphorus layer 500 A thick was replaced 45
`by gold in an ATOMEX electroless gold plating bath of
`NIPPON ENGELHARD Ltd. These nylon balls hav-
`ing a gold layer 500 A thick and a nickel-phosphorus
`layer 2000 A thick were dispersed in an epoxy resin in
`an amount of about 5 weight percent. The mixture was 50
`used as the contact media between upper and lower
`electrodes for a liquid crystal panel having a 10 pm
`thick gap. The resistance value at the contact portion
`between the upper and lower electrodes was 6 K0. The
`value remained unchanged after the fixed aging test.
`EXAMPLE 10
`
`55
`
`Following the procedures of Example 3, styrene balls
`10 pm in diameter were electroless nickel-plated to a 60
`thickness of 2000 A and electroless gold-plated to a
`thickness of 600 A. These styrene balls were dispersed
`in silver paste. The mixture was used as contact media
`between upper and lower electrodes for a liquid crystal
`panel having a gap thickness of 7 pm. The resistance 65
`value at the contact portion between upper and lower
`electrodes was 6 K0. The value remained unchanged
`after the fixed aging test.
`
`Styrene balls coated following the procedures of
`Example 4 were dispersed in ultraviolet curing acrylic-
`resin in an amount of about 10 weight percent. This
`mixture was used as contact media between upper and
`lower electrodes for a liquid crystal panel having a gap
`thickness of 10 pm. The resistance value at the contact
`portion between the upper and lower electrodes was 8
`K0. The value remained unchanged after the fixed
`aging test.
`
`EXAMPLE 12
`
`Substrates of a liquid crystal panel were formed of
`quartz glass. The contact portion between upper and
`lower electrodes was masked with resist material after
`
`fixed transparent electrodes were patterned on the sub-
`strates. Using a sputtering device, a 4000 A thick layer
`of SiOz was formed to insulate the transparent elec-
`trodes, except for the contact portion between the
`upper and lower electrodes. After removing the resist
`material, the contact media between upper and lower
`electrodes obtained in the foregoing embodiments 1 to 6
`were dispersed in an epoxy resin in an amount of about
`15 weight percent. The epoxy materials including the
`contact media were used as a conductive seal and pro.
`vided liquid crystal panels of simple construction
`wherein the contact portions between the upper and
`lower electrodes were of uniform dimension. Use of this
`liquid crystal panel decreased the number of process
`steps in preparing a panel and increased the yields of
`acceptable panels. Performance characteristics of the
`liquid crystal panels wherein the contact media doubled
`as the seal portion were no less than that of the liquid
`crystal panel wherein the seal portion and the contact
`portion between the upper and lower electrodes were
`separated.
`When using display panels with contact media be-
`tween upper and lower electrodes according to the
`embodiments in FIGS. 1 to 12, the rate of contact fail-
`ure was reduced to about one-tenth when compared
`with the contact media of the prior art.
`EXAMPLE l3
`
`FIG. 7 shows an embodiment ofa liquid crystal dis-
`play panel according to the invention. Glass panels
`1000, 10% are used for the upper and lower substrates
`and ITO transparent electrodes are used for electrodes
`104 and 105 on the upper and lower substrates 100a.
`100b. Conductive particles 101 include non-conductive
`plastic balls 121. The plastic balls 12] are about 5 pm in
`diameter and electroless plated with a nickel layer 122
`of about 0.1 pm thickness. The nickel layer is formed
`after the surface of the plastic ball 12] is activated as
`described above. The diameters of the plastic balls were
`about the same as the thickness Tl ofliquid crystal layer
`102. A thermoset epoxy adhesive 103 was used as the
`binder.
`In this embodiment, where more than 5 particles 101
`are located in contact portion 106,
`it
`is preferable to
`employ about 0.1 to about 50.0 weight percent of con-
`ductive particles 101 and about 99.9 to about 50 weight
`percent binder. If the concentration of the conductive
`particles 101 is under 5 wt.%, the number of conductive
`particles 101 in the contact portion 106 of at least about
`0.2 mm in diameter becomes less than 5 pieces. This
`results in unsatisfactory conductive reliability. On the
`other hand, if the concentration is over 50 weight per-
`
`Exhibit 1005 - page 8
`
`Exhibit 1005 - page 8
`
`

`

`4,600,273
`
`9
`cent then conductive particles 101 overlap each other
`and the contact portion 106 will be thicker than the
`liquid crystal layer 102 and display panel fabrication
`and reliability will be adversely affected.
`Conductive particles 101 were dispersed in the resin
`103 prior to hardening to form a mixture which was
`then coated on the electrode 104 by screen process
`printing. The two substrates 100a, 10% were then con-
`tact-bonded with hardening of binder 103,
`thereby
`forming contact portion 106. The thickness of liquid
`crystal layer 102 was determined by a non-conductive
`spacer 107 of glass fiber 5 pm in diameter. The spacers
`107 were located in a portion of the liquid crystal layer
`102 other than the contact portion 106.
`Table 1 shows the result of a reliability test, using a
`liquid crystal panel including contact media according
`to the invention. The concentration of the conductive
`particles is 15 weight percent.
`TABLE 1
`FRACTION DEFECTIVE
`60° C.;
`120” C.;
`90% Relative Hum.
`90% Relative Hum.
`200 Hours
`200 Hours
`
`Test Condition
`
`Embodiment according
`to this invention
`Prior an embodiment
`
`0/30 pieces
`
`18/30 pieces
`
`0/30 pieces
`
`3/30 pieces
`
`it can be seen that the conductive
`From Table 1,
`reliability is remarkably improved in comparison with
`the prior art. Contact portion 106 was 4.6 to 4.9 pm
`thick, which value was almost the same as the average
`thickness, 4.6 pm, of the liquid crystal layer 102. When
`a similar contact portion was formed by conventional
`methods, its thickness was about 7 pm, the liquid crystal
`layer 102 adjacent contact portion 106 became thicker
`than average, the display speed was not uniform and the
`color in the display region varied with the light. In the
`embodiment according to this invention, the liquid crys-
`tal layer 102 placed near contact portion 106 is 4.6 to 4.9
`pm thick, so the display speed is uniform and there are
`no differences in color in the display region.
`EXAMPLE 14
`
`FIG. 8 shows another embodiment of a liquid crystal
`panel according to this invention. Conductive particle
`109 comprises glass fiber 123, having a diameter which
`is almost the same as the thickness ofliquid crystal layer
`102. a nickel layer 124 of about 0.1 pm thick on its
`surface and a gold layer 125 of about 0.1 pm thickness
`on the nickel layer. The thickness of the liquid crystal
`layer 102 was 5 um:0.5 um. Glass fibers 123 of5:0.5
`um diameter and 20 to 100 pm length were used. Glass
`fibers 123 having a uniform diameter are made by pass-
`ing, drawing or extruding melted glass through the
`orifice of a spinneret type tool having openings of about
`5 pm in diameter, cooling, and then cutting to length of
`20 to lOO pm. This is similar to the method for making
`filaments of polymer resin, such as nylon, which have
`uniform diameters. Filaments of polymer resin are
`formed by melting the thermoplastic polymer resin,
`passing it through the orifices of a tool having fixed
`small diameters, and then cooling.
`Glass fiber 123 was provided with nickel layer 124 by
`electroless nickel plating, after activation of its surface. -
`Then, 0.1 pm thick of gold layer 125 was formed on the
`nickel layer by electroless gold plating. Binder 103 is an
`epoxy adhesive. The concentration of conductive parti-
`cles 109 is preferably between 3 to 30 weight percent
`
`10
`and the contention of epoxy is between about 97 to 70
`weight percent. In a quality control test 10 weight per-
`cent of the plated glass fiber 109 was mixed with 90
`weight percent binder 103. Liquid crystal panel was
`prepared as in Example 13 and the same type of reliabil-
`ity test as in Example 13 was performed. Tests were
`conducted at 120” C. for 200 hours, and at 60° C. and
`90% relative humidity for