Adhesive bonding and miscellaneous chemical manufacture – Methods – Surface bonding and/or assembly therefor
Patent
1994-05-27
1995-12-05
Simmons, David A.
Adhesive bonding and miscellaneous chemical manufacture
Methods
Surface bonding and/or assembly therefor
156252, 156265, 156297, 29 172, 29831, B32B 3110, B32B 3118
Patent
active
054725461
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The invention relates to a method for making printed circuit boards.
BACKGROUND TO THE INVENTION
Printed circuit boards are usually made by an etching method. A resin-impregnated insulating base, lined with a metal foil, is used. The desired conductor paths are covered by lacquer on the metal foil and those areas of the metal foil which are not covered are then caustically removed.
Printed circuit boards made in this way are relatively expensive. The base both insulates and constitutes a carrier for the conductor paths and is, therefore, usually made relatively thick. Generally, a phenolic resin is used to impregnate the insulating base. If several printed circuit boards are arranged one above the other, relatively thick and heavy packs result. It is of particular importance that printed circuit boards of this type must be treated as separate waste during disposal.
DE-PS 47 86 66 describes a method for making printed circuit boards by affixing conducting structures stamped out of sheet metal to an insulating base. In order to enable the stamped conductor paths to be held together, metal connecting straps are left between the conductor paths and are removed after the conducting structure has been fastened to the insulating base. Due to the fact that these connecting straps are removed, the mechanical stability of the printed circuit boards is determined solely by the insulating base, so that these must also be made relatively thick when using this method.
SUMMARY OF THE INVENTION
It is an object of the invention to provide a method such that inexpensive and thin insulating bases can be used.
In accordance with an embodiment of the invention, a method for making printed circuit boards comprised of a conductor pattern formed from a metal foil or sheet metal is comprised of the steps of inserting openings at predetermined locations of the metal foil or sheet metal in areas to be subsequently removed between conductor paths of the conductor pattern, filling the openings with adhesive, forming the conductor pattern by removing the metal foil or sheet in the areas while leaving connecting bridges comprised of the adhesive to mechanically stabilize the conductor pattern, and affixing the formed conductor pattern mechanically stabilized by the connecting bridges to an insulating base.
Embodiments of the invention are described in greater detail in the
following with reference to the drawings, showing:
FIG. 1 is a perspective view of a metal foil to illustrate a first procedural step;
FIG. 2 is a perspective view of the conductor paths to illustrate a second and third procedural step;
FIG. 3 is a perspective view of the printed circuit board to illustrate a fourth procedural step; and
FIG. 4 is a perspective view of two printed circuit boards for making a multilayer printed circuit board.
DETAILED DESCRIPTION OF THE INVENTION
Metal foil or sheet metal 1 shown in of FIG. 1 is, for example, a copper foil having a thickness of 0.4 mm. Conductor paths to be made, such as, e.g. conductor paths 2, 3, 4, are shown by broken lines. The conductor paths 2, 3, 4 to be made are separated from one another by the areas 5 to be subsequently removed.
Recesses 6 are made at those points where these areas 5 are to be located. When openings 6 have a circular cross-section, these are produced by boring. However, rectangular stamped openings 6A are preferably provided. The sizes of these openings 6, 6A are such that they come in contact with the edges 7 of the conductor paths 2, 3, 4 which are to be subsequently made adjacent to one another.
In a next procedural step, openings 6, 6A are filled with an adhesive, resin or cement. After the adhesive or resin or cement has hardened, the conductor paths, e.g. conductor paths 2, 3, 4, are isolated by treating the metal areas 5, not required, between conductor paths. This isolation can, for example, be achieved by etching, that is, by covering the conductor paths and caustically removing areas 5. Connecting bridges 8, connecting the conductor paths 2, 3, 4 w
REFERENCES:
patent: 2508030 (1950-05-01), Karns
Mayes M. Curtis
Simmons David A.
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