AU762686B2 - Process for depositing conducting layer on substrate - Google Patents
Process for depositing conducting layer on substrate Download PDFInfo
- Publication number
- AU762686B2 AU762686B2 AU15746/00A AU1574600A AU762686B2 AU 762686 B2 AU762686 B2 AU 762686B2 AU 15746/00 A AU15746/00 A AU 15746/00A AU 1574600 A AU1574600 A AU 1574600A AU 762686 B2 AU762686 B2 AU 762686B2
- Authority
- AU
- Australia
- Prior art keywords
- substrate
- conducting layer
- layer
- electrically conducting
- ink
- 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.)
- Ceased
Links
- 238000000034 method Methods 0.000 title claims description 54
- 230000008569 process Effects 0.000 title claims description 43
- 239000000758 substrate Substances 0.000 title claims description 37
- 238000000151 deposition Methods 0.000 title claims description 23
- 229920005989 resin Polymers 0.000 claims description 17
- 239000011347 resin Substances 0.000 claims description 17
- 230000008021 deposition Effects 0.000 claims description 15
- 238000010899 nucleation Methods 0.000 claims description 13
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 claims description 12
- 229910052802 copper Inorganic materials 0.000 claims description 12
- 239000010949 copper Substances 0.000 claims description 12
- 238000007639 printing Methods 0.000 claims description 12
- 238000009713 electroplating Methods 0.000 claims description 11
- 239000000203 mixture Substances 0.000 claims description 7
- 229920000642 polymer Polymers 0.000 claims description 7
- PXHVJJICTQNCMI-UHFFFAOYSA-N Nickel Chemical compound [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 claims description 6
- BQCADISMDOOEFD-UHFFFAOYSA-N Silver Chemical compound [Ag] BQCADISMDOOEFD-UHFFFAOYSA-N 0.000 claims description 6
- 239000011236 particulate material Substances 0.000 claims description 6
- 229910052709 silver Inorganic materials 0.000 claims description 6
- 239000004332 silver Substances 0.000 claims description 6
- 229920001577 copolymer Polymers 0.000 claims description 5
- 229910052751 metal Inorganic materials 0.000 claims description 5
- 239000002184 metal Substances 0.000 claims description 5
- KDLHZDBZIXYQEI-UHFFFAOYSA-N Palladium Chemical compound [Pd] KDLHZDBZIXYQEI-UHFFFAOYSA-N 0.000 claims description 4
- 239000000853 adhesive Substances 0.000 claims description 4
- 230000001070 adhesive effect Effects 0.000 claims description 4
- 239000000463 material Substances 0.000 claims description 4
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims description 3
- 229910052799 carbon Inorganic materials 0.000 claims description 3
- 229920001940 conductive polymer Polymers 0.000 claims description 3
- PCHJSUWPFVWCPO-UHFFFAOYSA-N gold Chemical compound [Au] PCHJSUWPFVWCPO-UHFFFAOYSA-N 0.000 claims description 3
- 229910052737 gold Inorganic materials 0.000 claims description 3
- 239000010931 gold Substances 0.000 claims description 3
- 229910052759 nickel Inorganic materials 0.000 claims description 3
- 239000003960 organic solvent Substances 0.000 claims description 3
- 125000003368 amide group Chemical group 0.000 claims description 2
- 229910052763 palladium Inorganic materials 0.000 claims description 2
- 238000005476 soldering Methods 0.000 claims description 2
- BASFCYQUMIYNBI-UHFFFAOYSA-N platinum Chemical compound [Pt] BASFCYQUMIYNBI-UHFFFAOYSA-N 0.000 claims 2
- 229910052697 platinum Inorganic materials 0.000 claims 1
- 239000010410 layer Substances 0.000 description 50
- 238000004519 manufacturing process Methods 0.000 description 8
- 239000002245 particle Substances 0.000 description 7
- 229920000728 polyester Polymers 0.000 description 6
- -1 polyethylene Polymers 0.000 description 6
- 229910000679 solder Inorganic materials 0.000 description 5
- 239000004952 Polyamide Substances 0.000 description 4
- 239000003963 antioxidant agent Substances 0.000 description 4
- 230000003078 antioxidant effect Effects 0.000 description 4
- RRAFCDWBNXTKKO-UHFFFAOYSA-N eugenol Chemical compound COC1=CC(CC=C)=CC=C1O RRAFCDWBNXTKKO-UHFFFAOYSA-N 0.000 description 4
- 238000009472 formulation Methods 0.000 description 4
- 229920002647 polyamide Polymers 0.000 description 4
- 239000002904 solvent Substances 0.000 description 4
- WSFSSNUMVMOOMR-UHFFFAOYSA-N Formaldehyde Chemical compound O=C WSFSSNUMVMOOMR-UHFFFAOYSA-N 0.000 description 3
- 239000004698 Polyethylene Substances 0.000 description 3
- 239000004743 Polypropylene Substances 0.000 description 3
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 description 3
- 229920000180 alkyd Polymers 0.000 description 3
- 239000004020 conductor Substances 0.000 description 3
- 229930195733 hydrocarbon Natural products 0.000 description 3
- 150000002430 hydrocarbons Chemical class 0.000 description 3
- 229920002120 photoresistant polymer Polymers 0.000 description 3
- 229920002492 poly(sulfone) Polymers 0.000 description 3
- 229920000573 polyethylene Polymers 0.000 description 3
- 229920001155 polypropylene Polymers 0.000 description 3
- 239000000243 solution Substances 0.000 description 3
- 239000004215 Carbon black (E152) Substances 0.000 description 2
- NPBVQXIMTZKSBA-UHFFFAOYSA-N Chavibetol Natural products COC1=CC=C(CC=C)C=C1O NPBVQXIMTZKSBA-UHFFFAOYSA-N 0.000 description 2
- 239000005770 Eugenol Substances 0.000 description 2
- 239000004677 Nylon Substances 0.000 description 2
- 239000004642 Polyimide Substances 0.000 description 2
- UVMRYBDEERADNV-UHFFFAOYSA-N Pseudoeugenol Natural products COC1=CC(C(C)=C)=CC=C1O UVMRYBDEERADNV-UHFFFAOYSA-N 0.000 description 2
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 description 2
- ATJFFYVFTNAWJD-UHFFFAOYSA-N Tin Chemical compound [Sn] ATJFFYVFTNAWJD-UHFFFAOYSA-N 0.000 description 2
- 239000000654 additive Substances 0.000 description 2
- 239000012790 adhesive layer Substances 0.000 description 2
- 239000004411 aluminium Substances 0.000 description 2
- 229910052782 aluminium Inorganic materials 0.000 description 2
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 2
- 230000000712 assembly Effects 0.000 description 2
- 238000000429 assembly Methods 0.000 description 2
- 238000009835 boiling Methods 0.000 description 2
- 239000003638 chemical reducing agent Substances 0.000 description 2
- 239000011248 coating agent Substances 0.000 description 2
- 238000000576 coating method Methods 0.000 description 2
- 150000001868 cobalt Chemical class 0.000 description 2
- ARUVKPQLZAKDPS-UHFFFAOYSA-L copper(II) sulfate Chemical compound [Cu+2].[O-][S+2]([O-])([O-])[O-] ARUVKPQLZAKDPS-UHFFFAOYSA-L 0.000 description 2
- 239000002274 desiccant Substances 0.000 description 2
- 238000001035 drying Methods 0.000 description 2
- 238000007772 electroless plating Methods 0.000 description 2
- 238000005530 etching Methods 0.000 description 2
- 229960002217 eugenol Drugs 0.000 description 2
- 239000010408 film Substances 0.000 description 2
- 229910001385 heavy metal Inorganic materials 0.000 description 2
- 229920001778 nylon Polymers 0.000 description 2
- ISWSIDIOOBJBQZ-UHFFFAOYSA-N phenol group Chemical group C1(=CC=CC=C1)O ISWSIDIOOBJBQZ-UHFFFAOYSA-N 0.000 description 2
- 238000007747 plating Methods 0.000 description 2
- 229920001721 polyimide Polymers 0.000 description 2
- 229910052710 silicon Inorganic materials 0.000 description 2
- 239000010703 silicon Substances 0.000 description 2
- 239000000126 substance Substances 0.000 description 2
- 238000004381 surface treatment Methods 0.000 description 2
- 235000015112 vegetable and seed oil Nutrition 0.000 description 2
- 239000008158 vegetable oil Substances 0.000 description 2
- 239000002699 waste material Substances 0.000 description 2
- KCXVZYZYPLLWCC-UHFFFAOYSA-N EDTA Chemical compound OC(=O)CN(CC(O)=O)CCN(CC(O)=O)CC(O)=O KCXVZYZYPLLWCC-UHFFFAOYSA-N 0.000 description 1
- 101100049144 Escherichia phage 186 dhr gene Proteins 0.000 description 1
- NINIDFKCEFEMDL-UHFFFAOYSA-N Sulfur Chemical class [S] NINIDFKCEFEMDL-UHFFFAOYSA-N 0.000 description 1
- HCHKCACWOHOZIP-UHFFFAOYSA-N Zinc Chemical compound [Zn] HCHKCACWOHOZIP-UHFFFAOYSA-N 0.000 description 1
- 230000002378 acidificating effect Effects 0.000 description 1
- 230000004913 activation Effects 0.000 description 1
- 230000000996 additive effect Effects 0.000 description 1
- 239000012670 alkaline solution Substances 0.000 description 1
- 239000003990 capacitor Substances 0.000 description 1
- 239000003054 catalyst Substances 0.000 description 1
- 239000000919 ceramic Substances 0.000 description 1
- 239000002738 chelating agent Substances 0.000 description 1
- 238000010960 commercial process Methods 0.000 description 1
- 150000001879 copper Chemical class 0.000 description 1
- 238000003851 corona treatment Methods 0.000 description 1
- 230000001419 dependent effect Effects 0.000 description 1
- 239000003085 diluting agent Substances 0.000 description 1
- 238000005553 drilling Methods 0.000 description 1
- 239000003792 electrolyte Substances 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 230000007613 environmental effect Effects 0.000 description 1
- 229920006332 epoxy adhesive Polymers 0.000 description 1
- 230000001747 exhibiting effect Effects 0.000 description 1
- 239000003365 glass fiber Substances 0.000 description 1
- 230000002209 hydrophobic effect Effects 0.000 description 1
- 230000006872 improvement Effects 0.000 description 1
- 238000005304 joining Methods 0.000 description 1
- 238000002372 labelling Methods 0.000 description 1
- 239000004922 lacquer Substances 0.000 description 1
- 238000010329 laser etching Methods 0.000 description 1
- 238000011068 loading method Methods 0.000 description 1
- 150000004668 long chain fatty acids Chemical class 0.000 description 1
- 238000004377 microelectronic Methods 0.000 description 1
- 239000002480 mineral oil Substances 0.000 description 1
- 230000006911 nucleation Effects 0.000 description 1
- 239000003921 oil Substances 0.000 description 1
- 235000019198 oils Nutrition 0.000 description 1
- 239000005011 phenolic resin Substances 0.000 description 1
- 229920001568 phenolic resin Polymers 0.000 description 1
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- 238000002360 preparation method Methods 0.000 description 1
- 239000011241 protective layer Substances 0.000 description 1
- 238000006722 reduction reaction Methods 0.000 description 1
- 238000007650 screen-printing Methods 0.000 description 1
- 239000004065 semiconductor Substances 0.000 description 1
- 239000003381 stabilizer Substances 0.000 description 1
- 239000004094 surface-active agent Substances 0.000 description 1
- 239000000725 suspension Substances 0.000 description 1
- 239000010409 thin film Substances 0.000 description 1
- 239000002383 tung oil Substances 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 1
- 229910052725 zinc Inorganic materials 0.000 description 1
- 239000011701 zinc Substances 0.000 description 1
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
- H05K3/10—Apparatus or processes for manufacturing printed circuits in which conductive material is applied to the insulating support in such a manner as to form the desired conductive pattern
- H05K3/12—Apparatus or processes for manufacturing printed circuits in which conductive material is applied to the insulating support in such a manner as to form the desired conductive pattern using thick film techniques, e.g. printing techniques to apply the conductive material or similar techniques for applying conductive paste or ink patterns
- H05K3/1275—Apparatus or processes for manufacturing printed circuits in which conductive material is applied to the insulating support in such a manner as to form the desired conductive pattern using thick film techniques, e.g. printing techniques to apply the conductive material or similar techniques for applying conductive paste or ink patterns by other printing techniques, e.g. letterpress printing, intaglio printing, lithographic printing, offset printing
-
- 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
- H05K2203/00—Indexing scheme relating to apparatus or processes for manufacturing printed circuits covered by H05K3/00
- H05K2203/11—Treatments characterised by their effect, e.g. heating, cooling, roughening
- H05K2203/1173—Differences in wettability, e.g. hydrophilic or hydrophobic areas
-
- 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
- H05K3/10—Apparatus or processes for manufacturing printed circuits in which conductive material is applied to the insulating support in such a manner as to form the desired conductive pattern
- H05K3/18—Apparatus or processes for manufacturing printed circuits in which conductive material is applied to the insulating support in such a manner as to form the desired conductive pattern using precipitation techniques to apply the conductive material
- H05K3/181—Apparatus or processes for manufacturing printed circuits in which conductive material is applied to the insulating support in such a manner as to form the desired conductive pattern using precipitation techniques to apply the conductive material by electroless plating
- H05K3/182—Apparatus or processes for manufacturing printed circuits in which conductive material is applied to the insulating support in such a manner as to form the desired conductive pattern using precipitation techniques to apply the conductive material by electroless plating characterised by the patterning method
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
- Y02E60/10—Energy storage using batteries
Landscapes
- Engineering & Computer Science (AREA)
- Manufacturing & Machinery (AREA)
- Microelectronics & Electronic Packaging (AREA)
- Chemically Coating (AREA)
- Manufacturing Of Printed Wiring (AREA)
- Electroplating Methods And Accessories (AREA)
- Electric Connection Of Electric Components To Printed Circuits (AREA)
Description
WO 00/33625 PCT/GB99/04064 PROCESS FOR DEPOSITING CONDUCTING LAYER ON SUBSTRATE The present invention relates to a process for forming an electrically conductive layer on a substrate, and in particular to a process for forming such a layer on a substrate which can be used as a circuit board in an electrical assembly.
Conventionally, silicon devices are mounted on printed circuit boards (PCB). A printed circuit board generally consists of etched copper on glass fiber laminate, tin plated and possibly carrying further layers of lacquer for protection and labeling.
Many operations of cropping, drilling, etching and plating are involved in its preparation. It is not cheap, and the production processes can have significant environmental impact.
The two major environment hazards posed by PCB manufacture are the waste effluent which is acidic and contains heavy metals (especially copper), and the use of hydrocarbons in photoresist developer and stripper. Stricter pollution limits imposed by water authorities are one driving force to reduce copper in effluent. In theory, waste effluent could be eliminated by a totally additive process for copper deposition, which would also offer considerable cost savings, but a satisfactory process has not yet been developed.
Attempts to avoid the use of a circuit board as such include the use of both thick and thin film techniques, normally associated with higher cost, not lower. Resistors are formed on a ceramic substrate by depositing tracks of a suitable film, sometimes trimmed to precise values by laser etching. A film of higher conductivity is generally used for interconnection.
WO 97/48257, which has common applicants with the present application, the disclosure of which is incorporated herein, discloses an alternative method of forming an electrical circuit board, whereby a conducting ink is lithographically printed onto a substrate in order to form an electrical circuit. The ink comprises electrically WO 00/33625 PCT/G B99/04064 2 conductive particles (such as metallic silver) suspended in an organic resin such as an alkyd resin. The manufacture of electrical components such as resistors, capacitors and antennae is also described.
Although the circuit printing technique disclosed in WO 97/48257 is a significant improvement on previous techniques, it has a number of disadvantages.
First, it is advantageous to electroplate a second conducting layer onto the conductive ink disclosed in WO 97/48257 in order that electrical components can then be soldered on to the substrate and/or to reduce the resistivity of the circuit. The problem is that the ink does not adhere sufficiently well to the substrate to enable electroplating.
Second, in order to prepare a conductive ink, it is necessary to employ particulate conductive material with a particulate surface treatment a coating of a long chain fatty acid) to enable the particles to be dispersed in the resin in such a manner as to render the dried ink electrically conductive. However, this surface treatment precludes further treatment of the dried ink, for example it prevents deposition of a further conductive layer by electroless deposition.
Third, it is difficult to solder electrical components onto an electrical circuit formed from conductive ink layers, because the layers do not contain sufficiently a high metal loading to create a suitable solder join. This means that components must be affixed using conductive polymer adhesive or a mechanical joint. However, it is thought that these joining methods do not age as well as solder, and exhibit higher electrical resistance. Moreover, any increase in the content of conductive particles in the ink is to the detriment of the ink's rheological properties.
According to a first aspect of the present invention, there is provided a process for forming a conductive layer on the substrate, comprising the steps of depositing ink on WO 00/33625 PCT/GB99/04064 3 the substrate by means of lithographic printing to form a seeding layer, and depositing a first electrically conducting layer on the seeding layer by electroless deposition.
Electroless deposition (or plating) is a well-known technique which involves coating an object (or part of an object) by means of a chemical reduction process, which, once initiated, is also-catalytic. The process is similar to electroplating except that no external current is required. In order to electroless plate an object, a seeding layer of suitable geometry and electrical and chemical characteristics must be formed on the object in order to provide nucleation sites for the metal to be deposited. It is thought that the seeding layer acts as a catalyst, in that it reduces the activation energy for the deposition step.
The term "lithographic printing" referred to herein is a printing process which utilizes differences in surface chemistry of the printing plate, including hydrophilic and hydrophobic properties. It does not refer to the commonly used process involving photoresist and etching occurring during the production of etched circuit boards and/or silicon semiconductor micro electronics. The term "ink" is intended to mean any material suitable for printing.
The ink which is employed in the present invention preferably comprises a particulate material suspended in a mixture of a resin and an organic solvent. Most preferably, the particulate material is particulate metal or carbon. Particularly suitable materials include silver, gold, copper, zinc or nickel. The particle size may be from 0.1 to micrometers, and preferably from 0.25 to 1 micrometers, more preferably greater than 0.1 micrometers and less than (but not equal to) 1 micrometer, and most preferably from 0.25 to 0.75 micrometers.
The amount of the particulate material in the ink is preferably from 50 to 90% w/w, and most preferably about 75 w/w.
WO 00/33625 PCT/GB99/04064 4 The resin for use in the ink may be a polymer blended with various oils. Preferably, the resin comprises a polymer having amide groups, for example a nylon-based polymer.
One resin which has been found to be particularly suitable is available commercially Lawter International (of Ketenislaan Ic-Haven 1520, B-9130 Kallow, Belgium) under the trade name "Nypol Nypol 3 comprises a modified polyamide and tung oil and vegetable oil blends.
Other resins which have exhibited acceptable performance include phenolic modified resin and alkyd resins, which are blended with modified mineral oils and vegetable oils.
In order to form the ink, the resin is mixed with a solvent and a suspension of the particulate material is formed. The solvent (or diluent) can be any suitable organic solvent with a boiling point of about 250 0
C.
The substrate onto which the conductive layer is printed is preferably formed from a polymer, and preferably comprises a flexible sheet. Suitable polymers include polyethylene, polypropylene, a polyester, a polyamide, a polyimide or a polysulphone. The substrate may be treated to improve adhesion of the ink to the substrate surface. For example, the substrate may be coated with a copolymer adhesive layer, or the surface may be chemically treated or subjected to corona treatment.
Preferably, the substrate is formed from a polyester, polyethylene, polypropylene or a polyamide, with or without a copolymer adhesive layer. In a particularly preferred embodiment, the substrate is a copolymer coated polyester, such as that available commercially from GBC (UK) Ltd of Rutherford Road, Basingstoke, Hampshire, RG24 8PD.
WO 00/33625 PCT/GB99/04064 It has been discovered that modified polyamide resins work acceptably well with substrates formed from polyethylene, polypropylene, polyamide and polysulphone.
Modified phenolic resins work acceptably well with polyester, polyimide or polysulphone substrates. Alkyd resins adhere reasonable well to polyester substrates.
As described above, the ink is deposited onto a substrate by means of a lithographic printing process in order to form a seeding layer for electroless deposition. The thickness of the seeding layer in the present invention is preferably from 3 to micrometers.
Electroless deposition of a first electrically conductive layer is carried out by conventional means. The conducting layer may be formed from any suitable electrically conductive material which can be deposited by electroless deposition, for example copper, silver, nickel or gold.
The thickness of the first conducting layer may be up to 4 micrometers and is preferably about 1 micrometer (although the thickness will be determined by the required electrical specifications).
The process of the present invention may comprise the step of electroplating a second electrically conducting layer onto the first conducting layer.
Electroplating is a well-known method whereby an object or part of an object is coated by means of electrolytic deposition. In order to be electroplated, the object has to have an electrode which exhibits a suitable geometry and electrical and chemical characteristics. In the case of the present invention, the first conducting layer which is deposited on the seed layer acts as an electrode in the electroplating process, thereby enabling the second conducting layer to be electrolytically deposited onto the first conducting layer.
WO 00/33625 PCT/GB99/04064 6 The addition of a second conducting layer improves the conductivity of the circuit tracks and improves the soldering of electrical components directly onto the substrate in order to form electrical assemblies (components may be soldered directly onto the first conducting layer).
If a second layer is going to be electroplated onto the first, then the first layer does not need to be as much as 1 micrometer thick; a thickness which render the substrate conductive is required, for example from 0.25 to 0.5 pLn.
As with the first conducting layer, the second layer may comprise any suitable electrically conducting material which can be electroplated. The thickness of the second conducting layer may be anything up to 35 micrometers, depending on the required specification of the circuit board.
Although a conducting layer can be electroplated onto an electrical circuit prepared according to the process disclosed in WO 97/48257, the resulting circuit board is structurally unstable due to the poor adhesion of the conducting ink onto the substrate.
By contrast, an electrical component can be soldered directly onto an electrical circuit prepared by the present method, particularly if a second conducting layer is deposited by means of the electroplating step, since by this step sufficient conducting layer can be deposited to which a good solder link can be formed.
One example application of the present invention is in the manufacture of electronic circuit boards. The lithographically deposited seeding layer is printed in the graphical configuration of an electrical or electronic circuit. The seeding layer can then be electrolessly plated with copper and a further layer of tin or other protective layer.
These layers improve the conductivity of the circuit tracks and allow them to be soldered directly onto via existing solder technologies.
WO 00/33625 PCT/GB99/04064 7 The lithographic process of production of seeding layers offers advantages of speed of production and very fine track and gap width resolution.
An embodiment of the present invention is below, by way of illustration only. For ease of understanding, the embodiment is described by way of its component parts.
The ink Ink layers deposited by the preferred lithographic printing process are about micrometers (5 x 10 6 m) thick. This may be compared to about 25 micrometers for conductive layers deposited by screen printing, and 20-75 micrometers of copper typically laminated onto a conventional printed circuit board.
The adopted approach has been to formulate an ink from particles suspended in an organic resin. Manipulation of the resin formulation permits a degree of control over certain mechanical characteristics of the ink viscosity).
As described above, the particulate material should be such as to enable the electroless deposition step. Suitable materials include silver, copper, carbon and palladium.
Hydrocarbon solvents and other suitable additives are used to adjust the printing, wear resistance and drying properties of the printed layer. An antioxidant (such as eugenol) is preferably incorporated to react with free radicals and thereby prevent autooxidation of the resin. In other words, the antioxidant prevents the resin from drying too quickly.
A drying agent such as a cobalt salt can be included to dry the resin once the antioxidant is used up.
An example of a preferred formulation of an ink is: WO 00/33625 PCT/GB99/04064 Component Identity Amount Particulate Silver particles with a mean particle size of 1 micrometer about 75 w/w Resin Nylon based hydrocarbon about 23 w/w Solvent Medium to high boiling point organic about 2% w/w Drying agent Cobalt salt trace Antioxidant Eugenol trace The resulting ink formulation exhibits Newtonian properties, exhibiting a viscosity of about 54 to 104mPaS 25 degrees C. Suitable viscosities of ink formulations are considered to lie in the range 10 3 mPaS 25 degrees C to 10'mPaS 25 0
C.
The substrate The copolymer-coated polyester from GBC (UK) Ltd was used.
Printing process First, the required artwork (that is, the pattern which is to become the electrical circuit) is applied to an anodised aluminium plate using the standard photoresist method used in the lithographic printing process. Second, the aluminium plate is used as a template in a lithographic process to apply the ink to the substrate in the required artwork pattern.
Electroless plating The electroless process involves placing the inked substrate in an electroless bath (such as the bath supplied by Shipley Ronal Limited) which contains a commercially available electroless plating solution. This comprises a solution of a copper salt (such as copper sulphate); a chelating agent e.g. EDTA; stabilisers such as sulphur compounds or heavy metals; an aqueous alkaline solution, for example aqueous WO 00/33625 PCT/G B99/04064 9 sodium hydroxide; a reducing agent for example formaldehyde; and, optionally, a surfactant. This is known under the trade mark "CP78 process".
Typical deposition rates achievable by use of this commercial process are approximately 4 micrometers of metal per hour. Typically therefore for a 1 micrometer layer, the substrate is placed in the electroless bath for ten to fifteen minutes.
As mentioned above, if the substrate is subsequently to be electroplated, then it is not necessary to electroless deposit a 1 micrometer layer. A sufficiently thick layer to act as an electrode in the electroplating process will result from placing the substrate in the electroless bath for about three to seven minutes.
Electroplating process Electroplating processes are well known in the art. For example, copper sulphate solution is used as the electrolyte. The rate of copper deposition is dependent upon the surface area of the cathode and the current density. A typical current density is Amps per square decametre. The anode is copper and the cathode is the item to be plated the conductive tracks).
Manufacture of electrical circuit board As described above, electrical components can be soldered directly onto the conductive layers on substrate formed by the above processes. Alternatively, a conductive polymer adhesive can be used such as an epoxy adhesive.
The present process can be employed to form a variety of devices comprising electrical circuitry. Examples of electrical assemblies which can be created using the above processes include battery interconnect circuitry, microwave integrated circuits, WO 00/33625 PCT/GB99/04064 antennae, such as microwave antennae, planar antennae or contoured antennae structures.
In a further aspect of the present invention, there is provided a method of depositing an electrically conducting layer onto a conducting layer of a substrate prepared by the method disclosed in WO 97/48257 by means of electroplating, electroless deposition, or a combination thereof.
The disclosures in UK patent application numbers GB 9826446.8 and GB9826447.6, from which this application claims priority, and in the abstract accompanying this application, are incorporated herein by reference.
Claims (13)
1. A process for forming a conductive layer on a substrate, comprising the steps of depositing ink on the substrate by means of lithographic printing to form a seeding layer, and depositing a first electrically conducting layer on the seeding layer by electroless deposition.
2. A process as claimed in claim 1, comprising the step of electroplating a second electrically conducting layer onto the first electrically conducting layer.
3. A process as claimed in any preceding claim, wherein the substrate is formed from a polymer into a flexible sheet.
4. A process as claimed in any preceding claim, wherein the substrate is coated with a copolymer adhesive. A process as claimed in any preceding claim, wherein the ink comprises a particulate material suspended in a mixture of a resin and an organic solvent.
6. A process as claimed in claim 5, wherein said material is a metal or carbon.
7. A process as claimed in claim 5 or 6, wherein the resin is a polymer having amide groups.
8. A process as claimed in any preceding claim, wherein the thickness of the seeding layer is from 3 to
9. A process as claimed in any preceding claim, wherein the thickness of the first electrically conducting layer is up to 4.tm. 12 A process as claimed in any preceding claim, wherein the thickness of the first electrically conducting layer is about 0.25pm.
11. A process as claimed in any preceding claim, wherein the first electrically conducting layer is formed from copper, palladium, silver, gold, platinum, nickel.
12. A process as claimed in any preceding claim, including the step of soldering an electrical component on the substrate.
13. A process as claimed in any one of claims I to 11, including the step of attaching an electrical component to the first or second conducting layer by means of a conductive polymer adhesive.
14. An electrical assembly comprising a substrate having at least one electrically conducting layer, which layer has been formed by a process as claimed in any of claims 1 to 13. An interconnect for a battery which is formed by a process as claimed in any of claims 1 to 13.
16. A battery including an interconnect as claimed in claim 0 o°°ooo oO o *o ooo o* *oo** •e.g* ooo* o o°* go
Applications Claiming Priority (5)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
GB9826446 | 1998-12-03 | ||
GB9826447 | 1998-12-03 | ||
GBGB9826447.6A GB9826447D0 (en) | 1998-12-03 | 1998-12-03 | Fabrication of a seeding layer to enable electroplating and electroless platingvia a lithographic printing process |
GBGB9826446.8A GB9826446D0 (en) | 1998-12-03 | 1998-12-03 | Electrical battery interconnect device |
PCT/GB1999/004064 WO2000033625A1 (en) | 1998-12-03 | 1999-12-03 | Process for depositing conducting layer on substrate |
Publications (2)
Publication Number | Publication Date |
---|---|
AU1574600A AU1574600A (en) | 2000-06-19 |
AU762686B2 true AU762686B2 (en) | 2003-07-03 |
Family
ID=26314771
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
AU15746/00A Ceased AU762686B2 (en) | 1998-12-03 | 1999-12-03 | Process for depositing conducting layer on substrate |
Country Status (8)
Country | Link |
---|---|
EP (1) | EP1142456A1 (en) |
JP (1) | JP2002531961A (en) |
CN (1) | CN1242659C (en) |
AU (1) | AU762686B2 (en) |
CA (1) | CA2350506A1 (en) |
HK (1) | HK1042627A1 (en) |
IL (1) | IL143440A0 (en) |
WO (1) | WO2000033625A1 (en) |
Families Citing this family (16)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US6413858B1 (en) | 1999-08-27 | 2002-07-02 | Micron Technology, Inc. | Barrier and electroplating seed layer |
GB0104982D0 (en) | 2001-02-28 | 2001-04-18 | Gill Steven | Electrode |
FR2825228B1 (en) * | 2001-05-25 | 2003-09-19 | Framatome Connectors Int | METHOD FOR MANUFACTURING A PRINTED CIRCUIT AND PLANAR ANTENNA MANUFACTURED THEREWITH |
GB0117431D0 (en) * | 2001-07-17 | 2001-09-12 | Univ Brunel | Method for printing conducting layer onto substrate |
US6828713B2 (en) * | 2002-07-30 | 2004-12-07 | Agilent Technologies, Inc | Resonator with seed layer |
GB2394725A (en) * | 2002-10-04 | 2004-05-05 | Qinetiq Ltd | Method of forming a magnetic information tag by electroless deposition |
US7255782B2 (en) | 2004-04-30 | 2007-08-14 | Kenneth Crouse | Selective catalytic activation of non-conductive substrates |
US20050241951A1 (en) * | 2004-04-30 | 2005-11-03 | Kenneth Crouse | Selective catalytic activation of non-conductive substrates |
GB0413076D0 (en) | 2004-06-11 | 2004-07-14 | Medtronic Inc | Deep brain stimulation of the Zona incerta |
EP2475234A3 (en) * | 2009-04-24 | 2012-09-19 | Sumitomo Electric Industries, Ltd. | Substrate for printed wiring board, printed wiring board, and methods for producing same |
EP2740818B1 (en) * | 2012-12-05 | 2016-03-30 | ATOTECH Deutschland GmbH | Method for manufacture of wire bondable and solderable surfaces on noble metal electrodes |
US10076032B2 (en) | 2014-03-20 | 2018-09-11 | Sumitomo Electric Industries, Ltd. | Substrate for printed circuit board, printed circuit board, and method for producing substrate for printed circuit board |
US10237976B2 (en) | 2014-03-27 | 2019-03-19 | Sumitomo Electric Industries, Ltd. | Substrate for printed circuit board, printed circuit board, and method for producing substrate for printed circuit board |
US10076028B2 (en) | 2015-01-22 | 2018-09-11 | Sumitomo Electric Industries, Ltd. | Substrate for printed circuit board, printed circuit board, and method for producing printed circuit board |
CN105405490A (en) * | 2015-12-23 | 2016-03-16 | 东洋油墨Sc控股株式会社 | Conductive paste for laser processing, conductive sheet, fabrication method of signal layout line and electronic device |
ES2938658T3 (en) | 2018-02-27 | 2023-04-13 | Fund I D Automocion Y Mecatronica | Production method of an offset printing conductive ink and conductive ink thus produced |
Citations (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
EP0664664A1 (en) * | 1994-01-24 | 1995-07-26 | International Business Machines Corporation | Depositing a conductive metal onto a substrate |
WO1997048257A1 (en) * | 1996-06-12 | 1997-12-18 | Brunel University | Electrical circuit |
Family Cites Families (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US3226256A (en) | 1963-01-02 | 1965-12-28 | Jr Frederick W Schneble | Method of making printed circuits |
DE2728465C2 (en) | 1977-06-24 | 1982-04-22 | Preh, Elektrofeinmechanische Werke, Jakob Preh, Nachf. Gmbh & Co, 8740 Bad Neustadt | Printed circuit |
CA1326720C (en) | 1987-12-31 | 1994-02-01 | Michael John Modic | Impact resistant blends of polar thermoplastic polymers and modified block copolymers |
US5158645A (en) | 1991-09-03 | 1992-10-27 | International Business Machines, Inc. | Method of external circuitization of a circuit panel |
-
1999
- 1999-12-03 IL IL14344099A patent/IL143440A0/en unknown
- 1999-12-03 WO PCT/GB1999/004064 patent/WO2000033625A1/en not_active Application Discontinuation
- 1999-12-03 AU AU15746/00A patent/AU762686B2/en not_active Ceased
- 1999-12-03 CA CA002350506A patent/CA2350506A1/en not_active Abandoned
- 1999-12-03 CN CNB998138053A patent/CN1242659C/en not_active Expired - Fee Related
- 1999-12-03 EP EP99958371A patent/EP1142456A1/en not_active Withdrawn
- 1999-12-03 JP JP2000586145A patent/JP2002531961A/en active Pending
-
2002
- 2002-04-08 HK HK02102596.2A patent/HK1042627A1/en unknown
Patent Citations (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
EP0664664A1 (en) * | 1994-01-24 | 1995-07-26 | International Business Machines Corporation | Depositing a conductive metal onto a substrate |
WO1997048257A1 (en) * | 1996-06-12 | 1997-12-18 | Brunel University | Electrical circuit |
Also Published As
Publication number | Publication date |
---|---|
AU1574600A (en) | 2000-06-19 |
HK1042627A1 (en) | 2002-08-16 |
CN1335045A (en) | 2002-02-06 |
IL143440A0 (en) | 2002-04-21 |
CN1242659C (en) | 2006-02-15 |
JP2002531961A (en) | 2002-09-24 |
CA2350506A1 (en) | 2000-06-08 |
EP1142456A1 (en) | 2001-10-10 |
WO2000033625A1 (en) | 2000-06-08 |
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