METHOD OF MANUFACTURING THIN FUNCTIONAL COPPER FOILS FROM A CONTINUOUS COPPER FOIL AND THE MANUFACTURED PRODUCT The present invention relates to a method of manufacturing thin functional copper products from finished copper or copper alloy strip. Functional copper products such as smart label antennas are produced by separating foils from a continuous thin strip before they are fixed on to a carrier substrate, and the remaining part of the strip is recycled to metal melting. The invention also relates to the product manufactured by this method.

Thin foils with good electrical conductivity properties are needed in several technical applications. These include for example inductive sensors and antennas for various kinds of electronic applications. In the present methods, the majority of earlier manufactured metallic foil is etched or cut away in order to obtain the functional form of the foil.

Smart labels (ID tags) are the active (functional) elements of microcircuits, their various memories (ROM, RAM, EPROM etc. ) (microchip) and antenna, which are laminated inside plastic or some other suitable surface material.

They are activated by the effect of an external RF or UF field and therefore do not need a power source, although they may indeed have one in some cases. Smart labels may be used to identify items (products, people, animals <BR> <BR> etc. ) by utilizing the data stored in the memory of the microcircuits.

Identification occurs at a distance, which may vary from a few millimeters to several metres. During identification, the antenna produces an electric current to the microchip in the field of the reader. The labels may be single- use, such as labels on food supply and other consumer goods packaging, and be destroyed after use, or they may be designed for permanent use, such as bank, personal and other ID applications.

The typical smart label antenna is 20-50 Mm thick and has a surface area of 10-50 mm x 10-100 mm. A printed antenna is generally manufactured using the serigraphy technique. Electroconductivity is created with conductive powder, which can be for instance silver, copper or graphite. In addition to printed antennas, antennas are manufactured at present by winding thin copper wire, by vapourizing, electrolytically or chemically. When making the shape of the antenna coil the unnecessary part of the surface metal manufactured in different ways from continuous copper foil is etched away chemically. The part to be etched away can well be over 50%. Since removing the superfluous metal requires a separate work stage, the aim in the industry has always been to achieve a functional antenna, which even in the preliminary stages of production is as NNS (near net shape) as possible.

In the prior art a method is known for producing a thin foil by electrolytic deposition. In the method there is a rotating cathode drum in an electrolysis tank and a curved anode made of one or more parts on the bottom of the tank. The electrolyte is fed between the anode and the cathode and as a result a copper foil is deposited on the surface of the cathode drum. When the efectrodeposited foil rises above the electrolyte, it is removed from the cathode and taken for further processing. The method has been developed since the 1930s and is described for instance in US patent 2,044, 415 and US patent application 2002/5363.

Electrolytic foil manufacture has focused on producing a continuous foil, of which the superfluous metal is etched away for instance in the manufacture of antennas and microcircuits. Etching occurs after the foil has been laminated to for example a PVC substrate. A resist is applied on top of the copper foil, and it is exposed into the desired form through a mask. The exposed resist is developed and the section of copper foil left outside the resist is etched away. After this, the resist is removed from the surface of the remaining copper foil product. The foil product is for example a microcircuit current conductor or a smart label antenna.

Now a method has been developed whereby a thin functional copper foil of the desired form is manufactured directly from a strip-like thin copper foil.

The necessary steps such as surface treatment, for example inhibiting, are carried out on the strip-like copper foil after which functional copper foils are formed from the strip for instance mechanically, such as by die-cutting, or etching. The copper foil products thus formed are freed from the strip and the residue from die-cutting is taken back to metal melting and reforming of the strip. Copper foil products such as antennas are mounted on a suitable substrate on the production line of the final product. The invention also relates to the products manufactured by this method.

The essential features of the invention will be made apparent in the attached claims.

Functional copper foils shall hereinafter be referred to only by the term antenna, although the desired product can be something other than a smart label antenna (for example, the conducting part of a microcircuit).

When the antenna is manufactured directly from a thin metal strip before the strip is fixed to a carrier such as a PVC substrate, it is easy to recycle the remaining piece of strip back to copper melting and so to a new manufacturing cycle. The antennas peeled off from the continuous copper strip are mounted on to a plastic/laminate strip for example with a robot on the smart card production line.

Thin functional copper or copper alloy foil is produced mechanically such as by die-cutting from copper or copper alloy strip, or by etching, before being fixed to the carrier substrate. Functional copper or copper alloy foil is advantageously a smart label antenna.