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
  • H05K3/02—Apparatus or processes for manufacturing printed circuits in which the conductive material is applied to the surface of the insulating support and is thereafter removed from such areas of the surface which are not intended for current conducting or shielding
  • H05K3/022—Processes for manufacturing precursors of printed circuits, i.e. copper-clad substrates
  • H05K3/025—Processes for manufacturing precursors of printed circuits, i.e. copper-clad substrates by transfer of thin metal foil formed on a temporary carrier, e.g. peel-apart copper
• • C—CHEMISTRY; METALLURGY
  • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
  • C25D—PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
  • C25D1/00—Electroforming
  • C25D1/04—Wires; Strips; Foils
• • 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
  • H05K2203/01—Tools for processing; Objects used during processing
  • H05K2203/0147—Carriers and holders
  • H05K2203/0152—Temporary metallic carrier, e.g. for transferring material
• • 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
  • H05K2203/07—Treatments involving liquids, e.g. plating, rinsing
  • H05K2203/0703—Plating
  • H05K2203/0726—Electroforming, i.e. electroplating on a metallic carrier thereby forming a self-supporting structure
• • 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
  • H05K2203/15—Position of the PCB during processing
  • H05K2203/1545—Continuous processing, i.e. involving rolls moving a band-like or solid carrier along a continuous production path
• • 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
  • H05K3/38—Improvement of the adhesion between the insulating substrate and the metal
  • H05K3/382—Improvement of the adhesion between the insulating substrate and the metal by special treatment of the metal

Definitions

• the invention relates to apparatus and a process for producing copper-clad dielectric material.
• US Patent 2 433 441 describes a method of manufacturing an extremely thin metal foil, in which an endless stainless steel band passes round a roller in a metal plating bath, then passes round a roller in a washing bath, and subsequently passes round a roller in a bath containing a film-forming material; finally the film is dried and the composite strip of metal and reinforcing tilra is mechanically stripped from the endless band.
• US Patent 4 113 576 describes a method of making a thin copper (oil plastics composite, in which a chromium-plated stainless steel belt passes round rollers guiding it on a sinuous path through various copper deposition and treatment baths. On a horizontal run of the belt fusible solid plastics particles are deposited on the copper and heated to form a plastics layer, which is then removed together with the copper.
• German Offenlegungschrift DE-A1-35 15 629 describes a process in which resin-impregnated sheets are passed through a double belt press whose belts are coated with copper by electrodeposition, so a copper-coated laminate separates from the press belts after the resin curing zone. This process has also not achieved practical utility, owing to the difficulty of depositing a copper layer of suitable quality on a press belt.
• the aim of the present invention is to provide a process and apparatus which are relatively uncomplicated and which can produce good quality copper-clad dielectric material.
• the invention provides apparatus for producing copper-clad dielectric material, comprising:
• (h) means for removing the resulting copper-clad dielectric material from the belt as it passes from the second run to the return run.
• the invention provides a process for producing copper-clad dielectric materia, comprising:
• the belt remains substantially horizontal during copper deposition and treatment, flexing of the belt is avoided during these steps, thereby avoiding damage to the copper layer or premature separation of the copper layer from the belt.
• the second run may be in alignment with the first, although this would require much space, but preferably it is either substantially vertical, extending upwards (or downwards) from the first run, or substantially horizontal and parallel to the first run.
• the belt is preferably a polished metallic belt (e.g. stainless steel, titanium, or chromium-plated steel) and is preferably polished on the return run of its path.
• a copper layer substantially free of micro-pores is directly deposited on the belt and is then provided with a matte surface of copper of dendritic structure, for instance by the techniques disclos-ed in WO 85/02969.
• the matte surface may be subjected to further treatment before bonding to the dielectric material.
• Bonding preferably involves the application of heat and pressure followed by cooling, the forces generated at the interface of the polished belt and the treated copper layer, owing to the penetration of the dielectric material into the dendritic structure under pressure and the subsequent cooling of the dielectric material, preferably being sufficient to overcome the adhesion of the copper layer to the polished belt.
• the depositing and treating means preferably comprise a series of electrolytic baths through which the first run of the belt passes. It may be possible to arrange for the liquid level in each bath to substantially coincide with the outer surface of the belt, but it is preferable for the belt to be immersed in the liquid in each bath and to enter and leave each bath via sealing means.
• sealing means preferably comprise rollers in contact with the outer surface of the belt, to minimise friction on the deposit and avoid abrasion.
• the inner surface of the belt may be contacted by rolling or fixed sealing members.
• the outer surface of the belt is preferably washed between each electrolytic bath, e.g. by a water spray.
• Cathodic electrical contact with the belt is preferably made between at least two of the electrolyticbaths.
• the contact is preferably with the inner surface of the belt, to avoid damaging the outer surface and/or the deposit, and is preferably made by a spring-loaded contact element.
• the outer surface is preferably supported by a roller or rollers, to prevent distortion of the belt by the force of the electrical contact.
• two endless belts with corresponding depositing and treatment means are arranged with their second runs substantially parallel to each other, with the path of the dielectric material running between them.
• Figure 1 shows apparatus for producing copper-clad dielectric material, utilizing two endless belts
• Figure 2 shows electrolytic deposition and treatment baths associated with the lower horizontal run of one of the baths; and Figure 3 shows part of two adjacent baths, on an enlarged scale.
• the apparatus illustrated has two endless polished stainless steel belts 1 which pass continuously around guide rollers 2 on a roughly square path including a first, horizontal run 3 and a second, vertical run 4 connected by a convex transition section 6.
• Each belt 1 is driven at a constant speed in the direction of the arrow 7 by suitable drive means (not shown).
• the first run 3 of each belt 1 passes through an electroplating plant 8 in which a copper layer is applied to the outer, lower surface of the belt 1 and is treated to enhance its bonding to dielectric material.
• the second runs 4 of the belt 1 pass through a vertically arranged double belt press 10 (the press belts are not shown) in which the treated copper layers on the facing outer surfaces of the belts 1 are bonded to dielectric material supplied in the form of continuous sheets 9 (e.g of epoxy resin impregnated glass cloth) from supply rolls 11.
• the resulting two-sided copper-clad laminate 12 separates easily from the belts 1 as they pass from the vertical to a horizontal stretch of a return run 13.
• the laminate 12 is withdrawn vertically and cut into sheets.
• the belts 1 are thinner than the press belts but are sufficiently thick (e.g. 1 or 2 mm) to carry the current necessary for electroplating.
• the electroplating plant 3 is illustrated in more detail in Figure 2.
• the horizontal run 3 of the stainless steel belt 1 passes through a series of electrolytic baths 16-21 in which the surface 22 of the electrolyte is above the level of the belt and an anode 23 is arranged immediately below the lower surface of the belt.
• the belt 1 enters and leaves each bath through a sealing device 24 comprising idle rubber-faced rollers 26 and 27 engaging the respective upper and lower surfaces of the belt 1 and engaging respective resilient rubber sealing strips 28 and 29 fixed to a wall of the bath.
• Some electrolyte will inevitably escape through the sealing device 24 and is caught by a trap 31 having a drain outlet 32.
• Electrolyte is wiped off the upper surface of the belt 1 by rubber wipers 33.
• Fresh electrolyte is supplied to each bath through a suitably positioned inlet pipe 34 having an outlet 36 (a slit or aperture) directing the electrolyte between the belt 1 and the anode 23.
• a slit or aperture directing the electro
• a first, pore-free copper layer 1 to 2 ⁇ m thick is deposited from an electrolyte containing copper pyrophosphate.
• the copper layer is built up to a thickness of 3 to 12 ⁇ m and treated in a well-known manner so that its exposed surface has a dendritic structure suitable for bonding to the dielectric material.
• the electrolyte contains zinc sulphate
• a very thin layer of zinc which is insufficient to reduce the bond strength appreciably, is applied in order to prevent chemical reaction between the copper and the epoxy resin.
• the plated layer is passivated in a weak chromic acid solution.
• the time of each deposition or treatment step in the baths 16-21 depends, of course, on the length of the bath and the speed of travel of the stainless steel belt 1.
• the dimensions of the belt are determined by the output required and the nature of the copper-clad laminate to be produced.
• the anodes 23 are perforated.
• this enables air to be blown up through the anode, allowing the current density to be increased.
• gases produced in the gap between anode and belt can escape through the perforations, enhancing uniformity of deposition. Consequently, using perforated anodes, an increase in plating speed by a factor of 2 or 3 may be achieved.
• the belt runs 4 pass between a pair of endless press belts (not shown) while heat and pressure are applied followed by cooling under pressure.
• Such double-belt presses are already known in the art of laminating and are, for example, made by the German company, Hymmen GmbH.
• the electroplating plant may be associated with an upper horizontal run of the belt and for the plated belt to descend through a vertical run, the dielectric material being supplied from above and the resulting laminate being discharged below the apparatus; the anodes 23 will in that case be above the belt.
• each belt 1 passes round large-diameter rollers and travels in a generally vertical direction from the first run to the second run.

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• Engineering & Computer Science (AREA)
• Chemical & Material Sciences (AREA)
• Manufacturing & Machinery (AREA)
• Microelectronics & Electronic Packaging (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Electrochemistry (AREA)
• Materials Engineering (AREA)
• Metallurgy (AREA)
• Organic Chemistry (AREA)
• Electroplating Methods And Accessories (AREA)
• Laminated Bodies (AREA)

Applications Claiming Priority (2)

Publications (1)

Family

ID=10613176

Family Applications (1)

Country Status (4)

Family Cites Families (4)

• 1987
  • 1987-03-02 GB GB878704828A patent/GB8704828D0/en active Pending
• 1988
  • 1988-03-02 EP EP19880905566 patent/EP0347430A1/de not_active Withdrawn
  • 1988-03-02 WO PCT/GB1988/000157 patent/WO1988006647A1/en not_active Ceased
  • 1988-03-02 JP JP63502041A patent/JPH02502617A/ja active Pending

Non-Patent Citations (1)

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