Adhesive bonding and miscellaneous chemical manufacture – Methods – Surface bonding and/or assembly therefor
Patent
1995-07-24
1998-05-26
Stemmer, Daniel
Adhesive bonding and miscellaneous chemical manufacture
Methods
Surface bonding and/or assembly therefor
1562755, 156563, 1565831, B30B 702, B32B 3120
Patent
active
057559163
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The invention concerns processes for production of plastic laminates with metal laminae.
Plastic laminates as a rule consist of sheets formed of several layers of plastic materials associated together in a stable manner, generally by pressing, on some kind of base such as paper, fabrics fibreglass or some other material.
The plastic materials may be of phenol, melamine, epoxy, polyester, silicon, fluoride, or others.
When producing printed circuits a metal lamina, usually of copper, is made to adhere to one or both sides during the pressing process
A pile of similar packages is formed; each comprises a number of sheets, impregnated with plastic materials, and two copper laminae, externally, one on each side of the package. A metal sheet, such as stainless steel, is put between each package and the pile so formed goes inside a multi-plate press providing heat and pressure simultaneously.
When each thermic cycle, which includes a cooling stage, has been concluded, a compact and rigid product is obtained the single components of which are closely associated. Presses suited to this kind of production are complex and give a low output; this is due to their having several plates, to the need to provide heat and pressure at the same time in well-defined and accurate sequences, to the need for creating, by conduction, uniform temperatures throughout the various packages in the pile; of these packages clearly only those at the top and bottom will be in contact with the heating plates.
In addition to complicating the structure of the press, the presence of many heating plates makes loading and unloading the packages a slow operation, while problems are created for short production runs due to the difficulty of amortizing costs.
In particular the propagation of calories from heating plates to piled up packages is greatly hindered by heat having to penetrate some distance to reach the innermost packages.
This leads to high costs, both of the system and of running it, to wasted material, to long processing times and, consequently, to an expensive product.
SUMMARY OF THE INVENTION
Accordingly, it is an object of the present invention to provide a process for making plastic laminates, which avoids the disadvantages of the prior art.
When the process is performed in accordance with the present invention, it greatly reduces the above drawbacks at the same time offering considerable advantages as will be explained below.
Subject of the invention is a process for making plastic laminates, especially for printed circuits, by forming piles of packages each one comprising a highly insulated plate of prepreg or something similar and metal laminae, especially copper, on one or both sides of said plate.
Sheets of stainless steel or some other material are placed between one package and another.
The pile so composed is put into a press where heat and pressure combine to form the laminate.
According to the invention heat is generated endothermically inside the pile of packages by means of electric resistances connected in series to a suitably powered generator of electric current.
Pressure on the pile of packages is brought about by placing said pile inside a cold press or in an autoclave. The electric resistances are laminae of copper or another metal, present at the beginning and end of each package.
One lamina is connected to another on one side and on the other side, alternatingly, of the pile of packages. The laminae at the beginning and end of a pile are connected to leads from the generator of electric current. In one version the electric resistances are sheets of steel or some other metal placed between one package and another at the beginning and end of a pile.
One sheet is connected to another on one side, and on the opposite one alternatively of the pile.
The sheets of metal at the beginning and end of the pile are connected to leads from the generator of electric current.
In another version the sheets of stainless steel or another metal are laid in pairs between the packages.
The electric
REFERENCES:
patent: 1945560 (1934-02-01), Meyercord
patent: 4158713 (1979-06-01), Degens
patent: 4666551 (1987-05-01), Soberay
patent: 4854994 (1989-08-01), Breiter
patent: 5160567 (1992-11-01), Konicek
Cedal S.r.l.
Stemmer Daniel
Striker Michael J.
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