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
• • C—CHEMISTRY; METALLURGY
  • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
  • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
  • C23C18/00—Chemical coating by decomposition of either liquid compounds or solutions of the coating forming compounds, without leaving reaction products of surface material in the coating; Contact plating
  • C23C18/16—Chemical coating by decomposition of either liquid compounds or solutions of the coating forming compounds, without leaving reaction products of surface material in the coating; Contact plating by reduction or substitution, e.g. electroless plating
  • C23C18/1601—Process or apparatus
  • C23C18/1603—Process or apparatus coating on selected surface areas
  • C23C18/1607—Process or apparatus coating on selected surface areas by direct patterning
• • C—CHEMISTRY; METALLURGY
  • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
  • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
  • C23C18/00—Chemical coating by decomposition of either liquid compounds or solutions of the coating forming compounds, without leaving reaction products of surface material in the coating; Contact plating
  • C23C18/16—Chemical coating by decomposition of either liquid compounds or solutions of the coating forming compounds, without leaving reaction products of surface material in the coating; Contact plating by reduction or substitution, e.g. electroless plating
  • C23C18/1601—Process or apparatus
  • C23C18/1633—Process of electroless plating
  • C23C18/1646—Characteristics of the product obtained
  • C23C18/165—Multilayered product
  • C23C18/1653—Two or more layers with at least one layer obtained by electroless plating and one layer obtained by electroplating
• • C—CHEMISTRY; METALLURGY
  • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
  • C25D—PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
  • C25D5/00—Electroplating characterised by the process; Pretreatment or after-treatment of workpieces
  • C25D5/02—Electroplating of selected surface areas
  • C25D5/022—Electroplating of selected surface areas using masking means
• • 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
  • H05K1/0213—Electrical arrangements not otherwise provided for
  • H05K1/0263—High current adaptations, e.g. printed high current conductors or using auxiliary non-printed means; Fine and coarse circuit patterns on one circuit board
  • H05K1/0265—High current adaptations, e.g. printed high current conductors or using auxiliary non-printed means; Fine and coarse circuit patterns on one circuit board characterized by the lay-out of or details of the printed conductors, e.g. reinforced conductors, redundant conductors, conductors having different cross-sections
• • 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
  • H05K3/243—Reinforcing the conductive pattern characterised by selective plating, e.g. for finish plating of pads
• • 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
  • H05K1/03—Use of materials for the substrate
  • H05K1/0306—Inorganic insulating substrates, e.g. ceramic, glass
• • 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
• • 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
  • H05K2201/00—Indexing scheme relating to printed circuits covered by H05K1/00
  • H05K2201/09—Shape and layout
  • H05K2201/09209—Shape and layout details of conductors
  • H05K2201/09654—Shape and layout details of conductors covering at least two types of conductors provided for in H05K2201/09218 - H05K2201/095
  • H05K2201/098—Special shape of the cross-section of conductors, e.g. very thick plated conductors
• • 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
  • H05K2203/0542—Continuous temporary metal layer over metal pattern

Definitions

• the invention relates to a method of providing thick copper conductors for high current applications on ceramic substrates.
• DBC Direct Bonded Copper
• Copper Clad Copper Clad (includes electroplating with subsequent firing)
• PCTF Plated Copper on Thick Films
• the short-circuiting links demand space, which in turn results in a reduction of the packing density on the ceramic substrate, i.e. less circuits per substrate.
• One additional problem is that after the links are removed silver contacts are exposed and the silver might, when exposed to humidity and voltage, start to migrate and short-circuit the circuits on the ceramic substrate. Therefore it demands an extra step of plating with nickel and/or gold in which the exposed silver contacts are covered.
• the object of the invention is to eliminate the above mentioned problems and bring about a method for production of dense circuit boards for high current applications, that allow for a combination of thick copper conductors together with printed resistors and/or other printed components.
• the invention involves printing a circuit pattern by means of a seed layer of silver or the like on the ceramic substrate, on which a layer of autocatalytic copper has good adhesion, instead of firing the final copper pattern to achieve good adhesion to a ceramic substrate, as in the Copper Clad-technology.
• This also makes it possible to include printed components on the substrate without the risk for damage during the otherwise used firing.
• the circuit pattern can be short-circuited by covering the entire surface of the substrate with a thin layer of autocatalytic copper.
• the areas on the ceramic substrate not to be further plated with copper are subsequently covered with a so-called plating resist.
• a subsequent electroplating builds up the copper thickness on the remaining areas.
• One of the advantages of the invention is that it is space-saving since there is no need for temporary short-circuiting connections or a so-called bus bar on the substrate for connection of the circuit prior to the final copper plating.
• Another advantage is that, since no consideration has to be made for current accessing the link system, the invention allows for a larger number of circuits per ceramic substrate, thus enabling the manufacture of denser circuit boards.
• One further advantage is that risk for short-circuiting by unwanted copper treeing is eliminated since no plating resist edge is connecting two conductors.
• the conductors achieve a similar conductor quality as the conductors in the copper clad technology, still keeping the possibility to include standard thick film resistors and crossovers.
• Figs. 1 - 6 schematically illustrate those process steps, according to the invention, that are included, upon manufacture of thick conductors on a ceramic substrate.
• a so-called seed layer of silver in the form of a conductor pattern 2 is printed on a ceramic substrate 1. This is performed in order to provide a layer that has good adhesion both to the substrate 1 and to copper, and to enable the actual plating.
• the process is not limited to just include silver as a seed layer but can include any other material that has good adhesion to the ceramic substrate 1, can act as terminal for printed components and at the same time can bond copper to its surface.
• the substrate 1 is lowered into a chemical bath for a predetermined time in order to apply an approximately 1 ⁇ m thick layer of autocatalytic copper 3 on the substrate 1 and the conductor pattern 2 as illustrated in Fig. 2.
• the autocatalytic copper layer 3 is applied in order to facilitate short-circuiting of the conductor pattern 2 and thereby prepare the ceramic substrate 1 for a further build-up of the thickness of the copper conductors by subsequent electrolytic plating or metallization. It is understood that the autocatalytic copper layer 3 is in contact with the conductor pattern 2.
• a so-called plating resist 4 is applied on the autocatalytic copper layer 3 on the areas of the ceramic substrate 1 outside the conductor pattern 2.
• This plating resist consists of a standard polymer material well known in the plating industry.
• the plating resist 4 is applied in order to protect and cover those areas that are not intended to be plated in a later process step i.e. areas outside the conductor pattern 2.
• copper is applied on the autocatalytic copper layer 3 on the conductor pattern 2 that in the previous step has not been covered by plating resist 4.
• copper conductors 5 are obtained.
• the thickness of the copper conductors 5 is increased to a desired value.
• the application of copper for the copper conductors 5 can be achieved by means of electroplating or metallization. It is understood that other application methods can be utilized.
• the desired value of the thickness of the copper conductors 5 is usually in the interval from 70 ⁇ m to 200 ⁇ m.
• the plating resist 4 is then removed by means of a chemical process, as illustrated by Fig. 5. After that, copper remains only as the thick copper conductors 5 and the short-circuiting autocatalytic copper layer 3 on the substrate 1.
• the chemical process can include a lowering of the ceramic substrate into one or more subsequent chemical baths that dissolve the plating resist.
• the autocatalytic copper layer 3 that is outside the conductor pattern 2 is removed. This can be achieved by etching the entire surface of the substrate.
• a ceramic substrate 1 with thick copper conductors 5 comprising a seed layer in the form of a conductor pattern 2 under the copper conductors 5 and a layer of autocatalytic copper 3 between the conductor pattern 2 and the thick copper conductors 5.
• the ceramic substrate 1 can also include various printed components (not shown) e.g. resistors that are connected to the conductor pattern 2 in Fig.l. When and if such components are included on the substrate 1, the plating resist 4 is applied to these as well.

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• Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Materials Engineering (AREA)
• Metallurgy (AREA)
• Organic Chemistry (AREA)
• Microelectronics & Electronic Packaging (AREA)
• General Chemical & Material Sciences (AREA)
• Mechanical Engineering (AREA)
• Manufacturing & Machinery (AREA)
• Electrochemistry (AREA)
• Manufacturing Of Printed Wiring (AREA)

Applications Claiming Priority (2)

Publications (1)

Family

ID=20284260

Family Applications (1)

Country Status (3)

Cited By (4)

Families Citing this family (1)

Citations (3)

• 2001
  • 2001-05-28 SE SE0101868A patent/SE0101868L/sv not_active Application Discontinuation
  • 2001-08-31 TW TW90121609A patent/TW593778B/zh not_active IP Right Cessation
• 2002
  • 2002-05-27 WO PCT/SE2002/001014 patent/WO2002098193A1/en not_active Application Discontinuation

Patent Citations (3)

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