Method of and apparatus for protecting thin copper foil and other shiny substrates during handling and rigorous processing, as in PCB manufacture and the like, by electric-charge adherence thereto of thin release-layered plastic films and the like, and improved products produced thereby

Abstract

An improved method of and apparatus for producing preferably thin plastic protective film layers for thin shiny copper foils and the like, as for PCB applications, with electric-charge adhering of the same to the foil and with peel-off releasable properties to provide the same original pristine, shiny copper foil surface without contamination, marring or other physical, chemical or other residue despite handling and other processing procedures.

What is claimed is:  
     
         1 . A method of protecting a smooth high finish shiny thin conducting copper foil as for PCB and copper clad laminate use, that comprises, electrostatically permanently charging a protective masking insulating plastic film pre-treated with a release surface; laminating the film to the foil to charge-adhere the film release surface against the foil; and subsequently, after the protection is no longer required, stripping the film from the foil.  
     
     
         2 . A method of protecting a smooth high finish shiny surface substrate, that comprises, electrostatically permanently charging a protective masking insulating plastic or paper film pre-treated with or without a release surface; applying the film upon the shiny substrate surface to charge-adhere the film release treated or untreated surface against said shiny substrate surface; and subsequently, after the protection is no longer required, stripping the film from the substrate surface.  
     
     
         3 . The method as claimed in  claim 1  wherein the plastic film is provided in rolls and unwound and fed through a web-charging station, and then rewound as charged-film rolls available for laminating to roll-fed foil.  
     
     
         4 . The method of  claim 3  wherein the film after charging is slit prior to the rewinding.  
     
     
         5 . The method of  claim 1  wherein the film is a polyester plastic laminate having a coating of a thin release layer of a cured release acrylated/epoxy/urethane oligomer and/or oligomer blended resin on at least one side of the film.  
     
     
         6 . The method of  claim 5  wherein said coating is applied to both sides of the film.  
     
     
         7 . The method of  claim 5  wherein the film side that is charge-adhered to the foil is smooth and the other side is relatively rougher.  
     
     
         8 . The method of  claim 3  wherein the film is substantially transparent.  
     
     
         9 . The method of  claim 3  wherein the film is selected from the group consisting of polyester, polypropylene, biaxially oriented polypropylene, polyvinylidine fluoride, polyethylene, paper and silicone TPX (polymethylpentene) and co-extruded films with releasable surface properties treated films.  
     
     
         10 . The method of  claim 2  wherein the substrate surface is selected from the group consisting of copper, stainless steel, chrome, glass, acrylics, Lucite, plexiglass and high finish furniture surfaces.  
     
     
         11 . The method of  claim 1  wherein the film-release peel strength is less than about 25 grams, per lineal inch.  
     
     
         12 . The method of  claim 1  wherein the charge-adhered film remains releasable after exposure to process temperatures of up to about 400° F. and pressures of up to about 700 pounds per square inch for periods of time up to several hours.  
     
     
         13 . Apparatus for producing a protective smooth high finish thin conducting copper foil as for PCB use, having, in combination, a plastic film web roll unwinding station; an electrostatic web-charging station; means for passing the unwinding film web through the web-charging station; a film-web roll rewinding station; and means for conveying the charged film web from the web-charging station to the roll rewinding station.  
     
     
         14 . The apparatus of  claim 13  wherein the film-web roll rewinding station is provided with a plurality of roll rewinders, and a web slitter is interposed prior to the rewinders for slitting the charged film web into a plurality of charged film webs for conveying to the respective of the reminders.  
     
     
         15 . The apparatus of  claim 13  wherein means is provided for laminating the charged film from the rewind roll(s) to a web of thin copper foil.  
     
     
         16 . A protected copper foil laminate product comprising a thin copper foil as for PCB use, having laminated on a surface of the foil, a substantially permanently electrostatically charge-attached protective plastic film.  
     
     
         17 . The product of  claim 16  wherein the plastic film is a polyester film having a coating of a thin release layer of a cured release acrylated acrylated/epoxy/urethane oligomer and/or oligomer-blended resin on at least one side of the film.  
     
     
         18 . The product of  claim 17  wherein said coating is applied to both sides of the film.  
     
     
         19 . The product of  claim 17  wherein the film side that is charge-adhered to the foil is smooth and the other side is relatively rough.  
     
     
         20 . The product of  claim 16  wherein the film is substantially transparent.  
     
     
         21 . The product of  claim 16  wherein the film is selected from the group consisting of polyester, polypropylene, biaxially oriented polypropylene, polyethylene, polyvinylidene fluoride, paper and silicone TPX (polymethylpentene) and co-extruded films with releasable surface properties treated films.  
     
     
         22 . The product of  claim 16  wherein the film-release peel strength is less than about 25 grams per lineal inch.  
     
     
         23 . The product of  claim 16  wherein the charge-adhered film remains releasable after exposure to process temperatures of up to about 400° F. and pressures of up to about 700 pounds per square inch, for periods of several hours.  
     
     
         24 . A rolled web of permanently electrostatically surface-charged polyester plastic film laminate having a coating of a thin release layer of a cured release acrylated/epoxy, urethane oligomer and/or oligomer-blended resin on at least one side of the film.  
     
     
         25 . The rolled web of  claim 24  wherein said coating is applied to both sides of the film.  
     
     
         26 . The rolled web of  claim 25  wherein the film side that is charged is smooth and the other side is relatively rough.  
     
     
         27 . The rolled web of  claim 24  wherein the film is substantially transparent.