WO1991009511A2 - Conducteurs electriques en resine conductrice - Google Patents

Conducteurs electriques en resine conductrice Download PDF

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Publication number
WO1991009511A2
WO1991009511A2 PCT/GB1990/001973 GB9001973W WO9109511A2 WO 1991009511 A2 WO1991009511 A2 WO 1991009511A2 GB 9001973 W GB9001973 W GB 9001973W WO 9109511 A2 WO9109511 A2 WO 9109511A2
Authority
WO
WIPO (PCT)
Prior art keywords
hole
resin
conductors
conductive
board
Prior art date
Application number
PCT/GB1990/001973
Other languages
English (en)
Other versions
WO1991009511A3 (fr
Inventor
John Michael Lowe
Original Assignee
Technology Applications Company Limited
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 Technology Applications Company Limited filed Critical Technology Applications Company Limited
Publication of WO1991009511A2 publication Critical patent/WO1991009511A2/fr
Publication of WO1991009511A3 publication Critical patent/WO1991009511A3/fr

Links

Classifications

    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
    • H05K3/00—Apparatus or processes for manufacturing printed circuits
    • H05K3/22—Secondary treatment of printed circuits
    • H05K3/24—Reinforcing the conductive pattern
    • H05K3/245—Reinforcing conductive patterns made by printing techniques or by other techniques for applying conductive pastes, inks or powders; Reinforcing other conductive patterns by such techniques
    • H05K3/246—Reinforcing conductive paste, ink or powder patterns by other methods, e.g. by plating
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
    • H05K3/00—Apparatus or processes for manufacturing printed circuits
    • H05K3/22—Secondary treatment of printed circuits
    • H05K3/24—Reinforcing the conductive pattern
    • H05K3/241—Reinforcing the conductive pattern characterised by the electroplating method; means therefor, e.g. baths or apparatus
    • H05K3/242—Reinforcing the conductive pattern characterised by the electroplating method; means therefor, e.g. baths or apparatus characterised by using temporary conductors on the printed circuit for electrically connecting areas which are to be electroplated
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
    • H05K1/00—Printed circuits
    • H05K1/02—Details
    • H05K1/09—Use of materials for the conductive, e.g. metallic pattern
    • H05K1/092—Dispersed materials, e.g. conductive pastes or inks
    • H05K1/095—Dispersed materials, e.g. conductive pastes or inks for polymer thick films, i.e. having a permanent organic polymeric binder
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
    • H05K2201/00—Indexing scheme relating to printed circuits covered by H05K1/00
    • H05K2201/03—Conductive materials
    • H05K2201/0332—Structure of the conductor
    • H05K2201/0335—Layered conductors or foils
    • H05K2201/0347—Overplating, e.g. for reinforcing conductors or bumps; Plating over filled vias
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
    • H05K2203/00—Indexing scheme relating to apparatus or processes for manufacturing printed circuits covered by H05K3/00
    • H05K2203/02—Details related to mechanical or acoustic processing, e.g. drilling, punching, cutting, using ultrasound
    • H05K2203/0257—Brushing, e.g. cleaning the conductive pattern by brushing or wiping
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
    • H05K2203/00—Indexing scheme relating to apparatus or processes for manufacturing printed circuits covered by H05K3/00
    • H05K2203/05—Patterning and lithography; Masks; Details of resist
    • H05K2203/0502—Patterning and lithography
    • H05K2203/054—Continuous temporary metal layer over resist, e.g. for selective electroplating
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
    • H05K3/00—Apparatus or processes for manufacturing printed circuits
    • H05K3/22—Secondary treatment of printed circuits
    • H05K3/28—Applying non-metallic protective coatings

Definitions

  • This invention is concerned with electrical conductors of conductive resin, in particular epoxy resin , and especially methods of providing such electrical conductors on a substrate for example a printed circuit board.
  • Such conductive inks are only able to withstand temperatures of up to about 180°C, above which temperature there is a tendency for the conductors formed of such ink to be destroyed.
  • Electrical conductors can also be printed in desired patterns, e.g. by screen printing, from so-called "conductive resins” and especially conductive epoxy resins.
  • conductive epoxy resins Materials currently available known as conductive epoxy resins are in fact epoxy resin materials loaded with a sufficient quantity of finally divided conductive material, for example finely divided silver, to impart good conductivity to the cured epoxy resin material.
  • Conductive epoxy resins cure from a viscous fluid state to a solid state when exposed to a temperature of about 200°C for about three seconds and will withstand temperatures as high as 300°C for a considerable period of time of up to about two hours and temperatures of about 250°C continuously; conductive epoxy resins cure slowly in any event to a solid condition, for example they will reach a solid condition in about a week at room temperature.
  • the temperatures to which the cured epoxy resins are resistant are sufficient that they will not be damaged by the temperatures normally encountered in manufacture of printed circuits and in particular will not be damaged by contact with molten solder, for example in wave soldering apparatus.
  • Conductive epoxy resins have considerable mechanical strength, in addition, and may be used on substrates for printed circuits which substrates themselves will not withstand soldering temperatures. Conductive epoxy resins may also be used in conjunction with polymer inks which, as mentioned above, likewise will not withstand soldering temperatures. However, solder commonly used in printed circuit manufacture will not adhere satisfactorily to cured conductive epoxy resin materials which can cause problems in the use of printed conductors of conductive epoxy resin so that their utility is much reduced compared with the potential usage.
  • polymer inks may be used and protected against direct contact with solder e.g. in wave-soldering apparatus, by coating them with a suitable protective compound eg. a resist or, where an electrical connection is to be made to the polymer ink, by applying to the connection region a conductive coating for example including carbon black, to protect the polymer ink.
  • a suitable protective compound eg. a resist or, where an electrical connection is to be made to the polymer ink
  • the carbon-including coating is used where an electrical pressure type contact is required.
  • Such protective coatings will only give short-term protection against the effects of excessive heat and the polymer ink conductors axe still destroyed by exposure to elevated temperatures over a period of time. Such coatings will also protect against silver migration.
  • it is essential to make solder connections to silver-loaded polymers it is possible to plate the contact with a suitable metal using an electroless plating process which is extremely difficult to control reliably
  • One of the various objects of the present invention is to provide improved methods of using conductive resin conductors.
  • the invention may be considered to provide a method of making an electrical conductor of conductive resin to which solder connections can be made comprising applying conductive resin to which solder will not normally adhere to a substrate in a desired pattern, applying a layer of electrically insulating material over part of the pattern leaving exposed those areas of the pattern which are to be solderable, applying temporary conductors to the substrate connected with each of said areas, immersing the substrate in an electroplating bath, and passing an electric current through said temporary conductors whereby to cause a conductive layer to which solder will adhere to be deposited on said areas of the pattern.
  • the resin is an epoxy resin and the conductive layer is a suitable metal, for example nickel.
  • the temporary conductors all lead to a connection portion which is also temporary, and to which an electrical supply may be connected to provide one electrode of the electroplating bath.
  • the temporary conductors and connecting portion are formed by printing an electrically conductive ink in a suitable configuration.
  • the temporary conductors are removed from the substrate; conveniently, where the temporary conductors are formed of electrically conductive ink, this is only partially cured before plating and in that event the temporary conductors may readily be wiped from the substrate.
  • the temporary conductors may be removed by exposure to elevated temperatures to destroy them, e.g. when the substrate is passed through a wave-soldering process.
  • the substrate is a printed circuit board.
  • the invention may be considered to provide a method of making an electrical connection between opposite surfaces of a printed circuit board comprising forming a hole through the board, applying a layer of conductive resin to one surface of the board over said hole and, while the conductive resin is in a fluid condition, causing the resin to pass through the hole to provide an electrically conductive path to the opposite face of the board, the resin thereafter curing to a solid condition.
  • a first layer of conductive resin is applied to a first surface of the board and a portion thereof caused to pass into the hole
  • a second layer of conductive resin is applied to the second, opposite, surface of the board and a portion thereof caused to pass into the hole into contact with said portion from the first layer.
  • the resin is caused to pass into the hole either by blowing or sucking it into the hole.
  • the invention may be considered to provide a printed circuit comprising electrical conductors of conductive resin in a desired pattern on at least one surface of a substrate, selected areas of said conductors carrying a conductive metal layer to which solder is adherent.
  • the invention may be considered to provide a printed circuit board comprising electrical conductors of conductive resin on opposite surfaces of the board and at least one hole passing through the board through which conductive resin extends connecting conductors on the opposite surfaces of the board.
  • Figure 1 is a plan view showing part of a printed circuit board
  • Figure 2 is a view in section with part broken away on the line II-II of Figure 1.
  • a substrate 10 which suitably comprises a rigid printed circuit board 12 for example of polymerised epoxy materials containing glass fibres, or paper fibres mixed with synthetic resins, for example phenolic materials to produce a paper bound by impregnated synthetic resin, commonly known as synthetic-resin-bonded paper.
  • the boards may if desired have an initial layer provided by a conventionally deposited copper sheet etched to provide copper conductors and subsequently having further conductive layers applied by printing conductive epoxy resin, or conductive epoxy resin conductors may be printed as a first layer, in a desired pattern by screen or other suitable printing techniques.
  • FIG 1 a number of discrete conductors 14 are shown, each produced by screen printing using a conductive epoxy resin.
  • the resin is cured after having been applied to the surface of the substrate 10 and thereafter a layer of electrically insulating material (commonly known as "resist” - suitable materials include cross-linking polymers sold under the Trade Mark “Photocoat” and various types are flexible, and curable by heat or ultraviolet radiation) is applied over parts of the conductor pattern leaving exposed areas of the pattern, namely contact pads 16.
  • resist 18 indicated in the drawing by stippling
  • a plurality of temporary conductors 20 are applied to the substrate, mainly over the resist layer 18 but each terminating at one of the contact pads 16.
  • the temporary conductors are interconnected and ultimately lead to a connecting portion, namely a plating bar 22.
  • the temporary conductors 20 and plating bar 22 are provided by a silver-loaded polymer ink (of composition known to those skilled in the art - a polymer thick film ink containing silver flakes) applied in a desired pattern by screen printing, so that electrical connections are made to each of the discrete conductors 14 by way of one of the contact pads 16. Where one of the discrete conductors 14 is long, more than one temporary conductor may be connected to that printed conductor 14.
  • the substrate 10 on which the temporary conductors 14 have been printed but only partially cured is then immersed in an electroplating bath, an electrical supply being connected to the plating bar 22 so that the temporary conductors 20 and the contact pads 16 of the pattern provide one electrode in the electroplating process.
  • the electroplating bath comprises a solution (the composition of which is well known to those skilled in the art and which is selected according to the metal to be deposited) which, when an appropriate current is passed, causes a conductive layer of a suitable metal, for example nickel to be deposited on the contact pads 16.
  • a suitable metal for example nickel to be deposited on the contact pads 16.
  • the conductive layer deposited is chosen to be such that solder will adhere to the deposited layer when conventional soldering techniques are used and the deposited layer will not be damaged by exposure to the temperatures and conditions encountered in the manufacture of the printed circuits.
  • the surface of the conductive epoxy resin in the hole will also be plated during the electroplating process to provide a through hole plated connection from a printed circuit on one surface to a further printed circuit on the opposite surface of the board.
  • the method described by way of example provides a simple and efficient way of printing patterns of electrically conductive resin on substrates which are resistant to elevated temperatures, sufficient to permit normal soldering techniques to be used, the conductors so applied having contact pads to which solder will adhere in normal soldering processes and through-hole connection is readily accomplished.

Abstract

Des procédés d'application d'un conducteur électrique en résine époxy conductrice consistent à appliquer la résine à un substrat; à appliquer un agent de réserve sur une partie des conducteurs (14) laissant des plots de contact exposés (16); à appliquer, au moyen par exemple d'une encre polymère d'impression, des conducteurs temporaires (20) au substrat (10) reliés aux zones (16); à immerger le substrat dans un bain électrolytique et à faire passer un courant électrique dans les conducteurs (20) pour déposer une couche métallique conductrice à laquelle la soudure peut adhérer au niveau des plots de contact (16). Les conducteurs (20) sont ensuite enlevés. Lors du placage à travers les trous pour relier les conducteurs de part et d'autre du substrat (10), on applique une première région de résine (26) sur un trou (24), de la résine (26a) est insufflée dans le trou (24) et une deuxième couche de résine (28) est appliquée sur la surface opposée de la carte, et le matériau (28a) provenant de cette deuxième couche est insufflé dans le trou (24) pour venir en contact avec le matériau (26a) afin de créer une voie électriquement conductrice qui traverse le trou (24).
PCT/GB1990/001973 1989-12-19 1990-12-18 Conducteurs electriques en resine conductrice WO1991009511A2 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
GB8928640.5 1989-12-19
GB898928640A GB8928640D0 (en) 1989-12-19 1989-12-19 Electrical conductors of conductive resin

Publications (2)

Publication Number Publication Date
WO1991009511A2 true WO1991009511A2 (fr) 1991-06-27
WO1991009511A3 WO1991009511A3 (fr) 1991-10-03

Family

ID=10668166

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/GB1990/001973 WO1991009511A2 (fr) 1989-12-19 1990-12-18 Conducteurs electriques en resine conductrice

Country Status (3)

Country Link
AU (1) AU6966191A (fr)
GB (1) GB8928640D0 (fr)
WO (1) WO1991009511A2 (fr)

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0903805A2 (fr) * 1997-09-19 1999-03-24 Peter Vernon Antenne plane et procédé de fabrication de conducteurs sur un substrat
WO1999052336A1 (fr) * 1998-04-06 1999-10-14 John Michael Lowe Procede pour doter un circuit imprime de pistes conductrices et appareil pour mettre en oeuvre ce procede
US6939447B2 (en) 1998-04-06 2005-09-06 Tdao Limited Method of providing conductive tracks on a printed circuit and apparatus for use in carrying out the method
EP1713312A3 (fr) * 2001-05-21 2009-01-14 Matsushita Electric Works, Ltd. Procédé de fabrication d'un panneau à circuit imprimé
US9623951B2 (en) 2013-08-21 2017-04-18 Goodrich Corporation Heating elements for aircraft heated floor panels

Citations (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB574946A (en) * 1942-11-05 1946-01-28 Standard Telephones Cables Ltd Improvements in or relating to electrically insulating plates provided with a systemof electrical connections
FR2425790A1 (fr) * 1978-05-08 1979-12-07 Limours Const Meca Elect El Perfectionnements aux circuits imprimes et a leurs procedes de fabrication
GB2038101A (en) * 1978-12-19 1980-07-16 Standard Telephones Cables Ltd Printed circuits
GB2109638A (en) * 1981-11-11 1983-06-02 Greenwoods Electronics Manufac Printed circuit boards
DE3245458A1 (de) * 1982-12-08 1984-06-14 Siemens AG, 1000 Berlin und 8000 München Verfahren zur herstellung von durchkontaktierungen in dickschichttechnik
EP0140585A1 (fr) * 1983-09-30 1985-05-08 Electro Materials Corp. Of America Procédé pour la fabrication d'un film conducteur d'électricité soudable et composition conductrice d'électricité
DE3430290A1 (de) * 1984-08-17 1986-02-27 Licentia Patent-Verwaltungs-Gmbh, 6000 Frankfurt Verfahren zur selektiven metallisierung
US4581301A (en) * 1984-04-10 1986-04-08 Michaelson Henry W Additive adhesive based process for the manufacture of printed circuit boards

Patent Citations (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB574946A (en) * 1942-11-05 1946-01-28 Standard Telephones Cables Ltd Improvements in or relating to electrically insulating plates provided with a systemof electrical connections
FR2425790A1 (fr) * 1978-05-08 1979-12-07 Limours Const Meca Elect El Perfectionnements aux circuits imprimes et a leurs procedes de fabrication
GB2038101A (en) * 1978-12-19 1980-07-16 Standard Telephones Cables Ltd Printed circuits
GB2109638A (en) * 1981-11-11 1983-06-02 Greenwoods Electronics Manufac Printed circuit boards
DE3245458A1 (de) * 1982-12-08 1984-06-14 Siemens AG, 1000 Berlin und 8000 München Verfahren zur herstellung von durchkontaktierungen in dickschichttechnik
EP0140585A1 (fr) * 1983-09-30 1985-05-08 Electro Materials Corp. Of America Procédé pour la fabrication d'un film conducteur d'électricité soudable et composition conductrice d'électricité
US4581301A (en) * 1984-04-10 1986-04-08 Michaelson Henry W Additive adhesive based process for the manufacture of printed circuit boards
DE3430290A1 (de) * 1984-08-17 1986-02-27 Licentia Patent-Verwaltungs-Gmbh, 6000 Frankfurt Verfahren zur selektiven metallisierung

Cited By (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0903805A2 (fr) * 1997-09-19 1999-03-24 Peter Vernon Antenne plane et procédé de fabrication de conducteurs sur un substrat
EP0903805A3 (fr) * 1997-09-19 1999-06-09 Peter Vernon Antenne plane et procédé de fabrication de conducteurs sur un substrat
WO1999052336A1 (fr) * 1998-04-06 1999-10-14 John Michael Lowe Procede pour doter un circuit imprime de pistes conductrices et appareil pour mettre en oeuvre ce procede
AU748566B2 (en) * 1998-04-06 2002-06-06 Tdao Limited Method of providing conductive tracks on a printed circuit and apparatus for use in carrying out the method
US6524462B1 (en) 1998-04-06 2003-02-25 Technology Development Associate Operations Limited Method of providing conductive tracks on a printed circuit and apparatus for use in carrying out the method
US6939447B2 (en) 1998-04-06 2005-09-06 Tdao Limited Method of providing conductive tracks on a printed circuit and apparatus for use in carrying out the method
US6949171B2 (en) 1998-04-06 2005-09-27 Tdao Limited Method of providing conductive tracks on a printed circuit and apparatus for use in carrying out the method
AU748566C (en) * 1998-04-06 2007-03-15 Tdao Limited Method of providing conductive tracks on a printed circuit and apparatus for use in carrying out the method
EP1713312A3 (fr) * 2001-05-21 2009-01-14 Matsushita Electric Works, Ltd. Procédé de fabrication d'un panneau à circuit imprimé
US9623951B2 (en) 2013-08-21 2017-04-18 Goodrich Corporation Heating elements for aircraft heated floor panels
US9630701B2 (en) 2013-08-21 2017-04-25 Goodrich Corporation Direct writing bus bars for screen printed resin-based conductive inks

Also Published As

Publication number Publication date
AU6966191A (en) 1991-07-18
WO1991009511A3 (fr) 1991-10-03
GB8928640D0 (en) 1990-02-21

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