GB2207669A - Providing metallised pads on transparent electrically conductive tracks on glass substrates - Google Patents

Providing metallised pads on transparent electrically conductive tracks on glass substrates Download PDF

Info

Publication number
GB2207669A
GB2207669A GB08718625A GB8718625A GB2207669A GB 2207669 A GB2207669 A GB 2207669A GB 08718625 A GB08718625 A GB 08718625A GB 8718625 A GB8718625 A GB 8718625A GB 2207669 A GB2207669 A GB 2207669A
Authority
GB
United Kingdom
Prior art keywords
substrate
electrically conductive
pads
solderable
paste
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Granted
Application number
GB08718625A
Other versions
GB2207669B (en
GB8718625D0 (en
Inventor
Barbara Needham
Stephen Rolt
Christopher Geoffrey Tanner
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
STC PLC
Original Assignee
STC PLC
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by STC PLC filed Critical STC PLC
Priority to GB8718625A priority Critical patent/GB2207669B/en
Publication of GB8718625D0 publication Critical patent/GB8718625D0/en
Publication of GB2207669A publication Critical patent/GB2207669A/en
Application granted granted Critical
Publication of GB2207669B publication Critical patent/GB2207669B/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

Links

Classifications

    • GPHYSICS
    • G02OPTICS
    • G02FOPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
    • G02F1/00Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
    • G02F1/01Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour 
    • G02F1/13Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  based on liquid crystals, e.g. single liquid crystal display cells
    • G02F1/133Constructional arrangements; Operation of liquid crystal cells; Circuit arrangements
    • G02F1/1333Constructional arrangements; Manufacturing methods
    • G02F1/1343Electrodes
    • G02F1/13439Electrodes characterised by their electrical, optical, physical properties; materials therefor; method of making
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B23MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
    • B23KSOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
    • B23K1/00Soldering, e.g. brazing, or unsoldering
    • B23K1/20Preliminary treatment of work or areas to be soldered, e.g. in respect of a galvanic coating
    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
    • H01LSEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L31/00Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
    • H01L31/02Details
    • H01L31/0224Electrodes
    • H01L31/022466Electrodes made of transparent conductive layers, e.g. TCO, ITO layers
    • H01L31/022475Electrodes made of transparent conductive layers, e.g. TCO, ITO layers composed of indium tin oxide [ITO]
    • HELECTRICITY
    • H05ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05KPRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
    • H05K3/00Apparatus or processes for manufacturing printed circuits
    • H05K3/22Secondary treatment of printed circuits
    • H05K3/24Reinforcing the conductive pattern
    • H05K3/245Reinforcing conductive patterns made by printing techniques or by other techniques for applying conductive pastes, inks or powders; Reinforcing other conductive patterns by such techniques
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B23MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
    • B23KSOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
    • B23K2101/00Articles made by soldering, welding or cutting
    • B23K2101/36Electric or electronic devices
    • B23K2101/38Conductors
    • HELECTRICITY
    • H05ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05KPRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
    • H05K1/00Printed circuits
    • H05K1/02Details
    • H05K1/03Use of materials for the substrate
    • H05K1/0306Inorganic insulating substrates, e.g. ceramic, glass
    • HELECTRICITY
    • H05ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05KPRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
    • H05K1/00Printed circuits
    • H05K1/02Details
    • H05K1/09Use of materials for the conductive, e.g. metallic pattern
    • H05K1/092Dispersed materials, e.g. conductive pastes or inks
    • HELECTRICITY
    • H05ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05KPRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
    • H05K2201/00Indexing scheme relating to printed circuits covered by H05K1/00
    • H05K2201/03Conductive materials
    • H05K2201/032Materials
    • H05K2201/0326Inorganic, non-metallic conductor, e.g. indium-tin oxide [ITO]
    • HELECTRICITY
    • H05ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05KPRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
    • H05K2201/00Indexing scheme relating to printed circuits covered by H05K1/00
    • H05K2201/03Conductive materials
    • H05K2201/0332Structure of the conductor
    • H05K2201/0335Layered conductors or foils
    • H05K2201/035Paste overlayer, i.e. conductive paste or solder paste over conductive layer
    • HELECTRICITY
    • H05ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05KPRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
    • H05K2203/00Indexing scheme relating to apparatus or processes for manufacturing printed circuits covered by H05K3/00
    • H05K2203/10Using electric, magnetic and electromagnetic fields; Using laser light
    • H05K2203/107Using laser light

Landscapes

  • Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • Nonlinear Science (AREA)
  • Microelectronics & Electronic Packaging (AREA)
  • General Physics & Mathematics (AREA)
  • Optics & Photonics (AREA)
  • Crystallography & Structural Chemistry (AREA)
  • Chemical & Material Sciences (AREA)
  • Mathematical Physics (AREA)
  • Manufacturing & Machinery (AREA)
  • Mechanical Engineering (AREA)
  • Condensed Matter Physics & Semiconductors (AREA)
  • Electromagnetism (AREA)
  • Computer Hardware Design (AREA)
  • Power Engineering (AREA)
  • Liquid Crystal (AREA)

Abstract

Transparent electrically conductve indium tin oxide tracks (2) upon a glass substrate (1) are provided with solderable metallised pads (3) using a conventional screen printed metal-loaded paste which is fired by local heating with a CO2 laser in order to avoid degrading the conductivity of the rest of the tracks. <IMAGE>

Description

PROVIDING METALLISED PADS ON TRANSPARENT ELECTRICAL > Y CONDUCTIVE TRACKS ON GLASS SUBSTRATES This invention relates to the providing of solderable pads upon selected regions of transparent electrically conductive coating supported upon a substrate, and finds a particular application in the provision of terminal pads for mounting integrated circuits upon the transparent conductor tracks of a liquid crystal display cell.
Liquid crystal cells have a number of transparent electrode tracks to which terminal connection needs to be made. Typically such tracks are made of indium tin oxide (ITO), and these tracks may be provided with metal pads to which such connection may be made by means of soldering. Particularly in the case of relatively small cells having relatively few tracks these pads can satisfactorily be provided by conventional screen printing of a metal-loaded paste which is subsequently fired in a belt-furnace to produce a metallic pad that is readily solderable.In the case of other types of liquid crystal cell, particularly large area matrix addressed cells with closely spaced long firm tracks, this method is not satisfactory in view of the not insubstantial increase in sheet resistivity of the ITO that is found to occur as the result of the firing. Accordingly, an alternative method of providing these pads has been sought.
In principle, one solution to this problem is provided by depositing a layer of copper over the ITO layer before the ITO has been patterned to create the electrode tracks. The copper and the ITO is next patterned to form these tracks, and then the remaining copper is removed from the display area to leave the transparent ITO. A significant drawback of this approach is the cost of depositing the copper having particular regard to the fact that most of it is then going to have to be removed. Less copper would need to be deposited if it could be selectively electroless plated upon already patterned ITO, but difficulties with this approach include the fact that electroless copper plating solutions tend to etch ITO and also tend to fail the selectivity requirement for plating on the ITO without plating on the intervening regions from which.
the ITO has been removed.
An alternative approach would be to use electroless plating of nickel which has the advantage that the plating solution does not appear to attack the ITO. However, the disadvantage of this approach is that if the electroless nickel deposit is made thick enough to be reliable for soldering purposes the coating tends to be stressed and in consequence poorly adhering to the underlying ITO. This problem of stress can be avoided by changing the deposition method, but this raises different problem, namely that etchants designed to remove the electroless nickel deposit from the ITO in the display area tend to be insufficiently selective and remove not only the nickel but also the underlying ITO.
The present invention is concerned with a method of providing solderable pads on transparent conductor tracks that on the one hand avoids the electrical conductivity degradation problem encountered with oven firing of screen printed metal-loaded paste, and on the othet hand also avoid the adhesion and selectivity problems associated with electroless plating.
According to the present invention there is provided a method of providing one or more solderable metallised pads on selected regions of one or more areas of electrically conductive transparent coating supported upon a substrate, which method includes the step of applying a metal-loaded glass frit paste to one or more localised regions of the conductive coating, and the step of selectively heating the or each localised region, so as to fire the paste to render it solderable, while leaving substantially unheated one or more other regions of the conductive coating to which the paste has not been applied.
There follows a description of the provision of solderable pads upon the ends of electrically conductive tracks formed Dy the patterning of an ITO layer deposited upon a glass substrate which is to for part of a large area liquid crystal display device. The description refers to the accompanying drawing whicr depicts a perspective view of a portion of the electroded substrate.
A glass sheet 1, which may typically be a soda lime float glass such as that made by Pilkington under the designation PERMABLOC or an alumino borosilicate glass such as Corning 7059, is provided with a pattern of transparent electrically conductive ITO tracks 2.
Typically such tracks are formed by photolithographic selective etching of an ITO layer that initially covered the whole surface of the glass sheet 1. Localized regions at the end of these tracks need to be metallised in order to enable electrical connection to be made between the tracks and associated drive circuitry by means of soldering. To this end pads 3 of a metal-loaded low firing temperature conductor paste, for instance the silver-loaded paste marketed by Electro Science Laboratories under the designation 590G or that marketed by Du Pont under the designation 7713, are applied by screen printing. The thickness of the paste is typically that which upon conventional firing would produce a metallisation 15 to 20.
The conventional process for firing such a paste involves heating the paste for a short period at about 0 100 C to drive off the printing vehicle, and then baking the residue first to drive off the binder and then to sinter the glass frit. Typically such sintering requires a temperature of about 5500C.However baking at a temperature even only as high as about 4500C has a marked effect upon ITO, typically increasing its sheet resistance about fourfold. (Baking at temperatures lower than 450 0C also increase sheet resistance : but by smaller factors.) Having regard to the effect of resistance upon the time constant involved in the addressing of the pixels, and also having regard to the length and slenderness of the tracks, some of which for an A size display are over 300mm long and, depending upon the resolution required, typically between 0.1 and 0.4mm wide, an increase in sheet resistance of anything approaching a factor of four can be quite unacceptable.
Such an increase can in principle be avoided by ensuring that the baking is in a tcompletely oxygen-free atmosphere, but this is not a practical way round the problem since conventional glass frit pastes require oxygen to drive off the binder satisfactorily.
This problem is resolved by localised heating to bake the paste. This localised heating may produce an equivalent increase in sheet resistivity, but any such increase is confined to the area heated which is a small proportion of the total area of the tracks.
A convenient heat source for this localised heating is a CO2 laser operational at 10.6 microns.
Using an 80 watt CO2 laser, satisfactory baking was found to result from the use of a 500ms pulse with the laser beam defocussed to provide a spot size of about 1cam. A much shorter pulse length, for instance of about 10ms, with a corresponding reduction in spot size in order to attain the same temperature, can give rise to problems of crazing. This crazing is believed to result from the sharper temperature gradients believed to be set up in the glass when using the shorter duration pulses. With the 500ms pulse and a laser beam spot size of lcm the resulting temperature distribution is sufficient to produce an adequate firing of the paste over less than the whole area of the spot, typically providing a satisfactorily metallised spot size of about half the diameter of the laser beam spot size.
It should be appreciated that the energy density requirements for baking the paste are not so high as to make it necessary to use coherent light for this purpose, and there may well be applications for which the use of non-coherent light from an infra-red lamp or lamp array may be preferred. Another alternative is to provide localised heating by means of a jet of hot gas.
A further advantage of this localised heating is that it speeds total processing time. Thus baking the paste in a furnace typically takes up to 40 minutes, whereas, with a single CO2 80 watt laser, the pads for mounting about 40 dual-in-line integrated circuit chips can be metallised in about one minute. With this saving in time the invention finds application not only in the metallising transparent electrically conductive tracks formed in ITO, but also those formed in other materials, such as tin oxide or zinc oxide, for which heating to the paste firing temperature presents no particular problem. Successful trials have also been conducted in which a YAG-laser has been substituted for the CO2 laser.

Claims (8)

CLAIMS :
1. A method of providing one or more solderable metallised pads on selected regions of one or more areas of electrically conductive transparent coating supported upon a substrate, which method includes the step of applying a metal-loaded glass frit paste to one or more localised regions of the conductive coating, and the step of selectively heating the or each localised region, so as to fire the paste to render it solderable, while leaving substantially unheated one or more other regions of the conductive coating to which the paste has not been applied.
2. A method as claimed in claim 1, wherein the electrically conductive transparent coating is made of indium tin oxide.
3. A method as claimed in claim 1 or 2, wherein coherent radiation from a laser is used for the step of selective heating.
4. A method as claimed in claim 1 or 2, wherein radiation from one or more infra red lamps is used for the step of selective heating.
5. A method of providing one or more solderable metallised pads on selected regions of one or more areas of electrically conductive transparent coating supported upon a substrate, which method is substantially as hereinbefore described with reference to the accompanying drawing.
6. A substrate supporting one or more areas of transparent electrically conductive coating selective regions of which have been provided with one or more solderable metallisd pads by the method claimed in any preceding claim.
7. A substrate as claimed in claim 6, which substrate is made of glass.
8. A glass substrate as claimed in claim 7, which substrate constitutes a part of a liquid crystal cell.
GB8718625A 1987-08-06 1987-08-06 Providing metallised pads on transparent electrically conductive tracks on glass substrates Expired - Lifetime GB2207669B (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
GB8718625A GB2207669B (en) 1987-08-06 1987-08-06 Providing metallised pads on transparent electrically conductive tracks on glass substrates

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
GB8718625A GB2207669B (en) 1987-08-06 1987-08-06 Providing metallised pads on transparent electrically conductive tracks on glass substrates

Publications (3)

Publication Number Publication Date
GB8718625D0 GB8718625D0 (en) 1987-09-09
GB2207669A true GB2207669A (en) 1989-02-08
GB2207669B GB2207669B (en) 1991-05-15

Family

ID=10621904

Family Applications (1)

Application Number Title Priority Date Filing Date
GB8718625A Expired - Lifetime GB2207669B (en) 1987-08-06 1987-08-06 Providing metallised pads on transparent electrically conductive tracks on glass substrates

Country Status (1)

Country Link
GB (1) GB2207669B (en)

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2690597A1 (en) * 1992-04-27 1993-10-29 Futaba Denshi Kogyo Kk Transparent conductive film wiring board mfr. - by dry process, esp. for display device front panel prodn.
US20120321821A1 (en) * 2009-11-27 2012-12-20 Luoyang Landglass Technology Co., Ltd Method for Sealing Vacuum Glass and Vacuum Glass Product
US20130292038A1 (en) * 2011-01-31 2013-11-07 Luoyang Landglass Technology Co., Ltd Method for Vacuum Acquisition during Manufacturing of Vacuum Glass Component
US20140050867A1 (en) * 2010-12-10 2014-02-20 Luoyang Landglass Technology Co., Ltd Vacuum Glass Component

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US10717671B2 (en) 2015-07-07 2020-07-21 Agc Glass Europe Glass substrate with increased weathering and chemical resistance

Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2104058A (en) * 1981-08-03 1983-03-02 Avx Corp Silver-filled glass metallizing paste

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2104058A (en) * 1981-08-03 1983-03-02 Avx Corp Silver-filled glass metallizing paste

Cited By (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2690597A1 (en) * 1992-04-27 1993-10-29 Futaba Denshi Kogyo Kk Transparent conductive film wiring board mfr. - by dry process, esp. for display device front panel prodn.
US20120321821A1 (en) * 2009-11-27 2012-12-20 Luoyang Landglass Technology Co., Ltd Method for Sealing Vacuum Glass and Vacuum Glass Product
US20120321822A1 (en) * 2009-11-27 2012-12-20 Luoyang Landglass Technology Co., Ltd Compound Sealing Method for Vacuum Glass
US20130004685A1 (en) * 2009-11-27 2013-01-03 Luoyang Landglass Technology Co., Ltd Method for Sealing Curved Vacuum Glass and Curved Vacuum Glass
US20130202820A1 (en) * 2009-11-27 2013-08-08 Luoyang Landglass Technology Co., Ltd Method for Sealing Tempered Vacuum Glass and Tempered Vacuum Glass
US8840007B2 (en) * 2009-11-27 2014-09-23 Luoyang Landglass Technology Co., Ltd Compound sealing method for vacuum glass
US8899472B2 (en) * 2009-11-27 2014-12-02 Luoyang Landglass Technology Co., Ltd Method for sealing vacuum glass and vacuum glass product
US8899471B2 (en) * 2009-11-27 2014-12-02 Luoyang Landglass Technology Co., Ltd Method for sealing curved vacuum glass and curved vacuum glass
US20140050867A1 (en) * 2010-12-10 2014-02-20 Luoyang Landglass Technology Co., Ltd Vacuum Glass Component
US9815737B2 (en) * 2010-12-10 2017-11-14 Luoyang Landglass Technology Co., Ltd Vacuum glass component
US20130292038A1 (en) * 2011-01-31 2013-11-07 Luoyang Landglass Technology Co., Ltd Method for Vacuum Acquisition during Manufacturing of Vacuum Glass Component

Also Published As

Publication number Publication date
GB2207669B (en) 1991-05-15
GB8718625D0 (en) 1987-09-09

Similar Documents

Publication Publication Date Title
EP1275153B2 (en) Carrier substrate for electronic components
US4864106A (en) Electrical component
US4478690A (en) Method of partially metallizing electrically conductive non-metallic patterns
US5312643A (en) Method of producing a transparent conductive film provided with supplementary metal lines
GB2207669A (en) Providing metallised pads on transparent electrically conductive tracks on glass substrates
US6208404B1 (en) Black matrix
US20140306382A1 (en) Making multi-layer micro-wire structure
US4385976A (en) Solderable layer system, its use and method for manufacturing same
US4824693A (en) Method for depositing a solderable metal layer by an electroless method
DE3664932D1 (en) Process for metallizing transparent conducting strips
CA2343386A1 (en) Method for assembling metal printed conductors as electrodes on a channel plate for ultrawide flat screens
JP4592151B2 (en) COMPOUND FOR FORMING ELECTRODE AND METHOD FOR PRODUCING ELECTRODE
GB2068834A (en) Coating vitreous or ceramic supports
JPS6441194A (en) Manufacture of thin film electroluminescent element
US3666639A (en) Method for coating metals or insulating substrates having a vitreous binder
JPS60245781A (en) Plating method onto transparent conductive film pattern
US4475682A (en) Process for reducing series resistance of solar cell metal contact systems with a soldering flux etchant
JPS60245782A (en) Plating method onto transparent conductive film pattern
KR102490505B1 (en) Transpaparent glass display substrate, transpaparent led display device and method for fabricating the same
JPH06180443A (en) Substrate and its production thereof
WO1991018757A1 (en) Method for applying electrical bus bars to a substrate
CN1169014C (en) Device and method for stripping electric parts
KR900006976B1 (en) Electrically condcutive circuit board and method of producing the same
WO1997033311A1 (en) Method for making electrical connections
NO860985L (en) ELECTRICAL CIRCUIT DEVICE AND PROCEDURE FOR ITS MANUFACTURING.

Legal Events

Date Code Title Description
732 Registration of transactions, instruments or events in the register (sect. 32/1977)
732E Amendments to the register in respect of changes of name or changes affecting rights (sect. 32/1977)
732E Amendments to the register in respect of changes of name or changes affecting rights (sect. 32/1977)
732E Amendments to the register in respect of changes of name or changes affecting rights (sect. 32/1977)
PE20 Patent expired after termination of 20 years

Effective date: 20070805