Electrolysis: processes – compositions used therein – and methods – Electrolytic coating – Forming nonelectrolytic coating before forming nonmetal...
Patent
1998-06-05
2000-09-19
Gorgos, Kathryn
Electrolysis: processes, compositions used therein, and methods
Electrolytic coating
Forming nonelectrolytic coating before forming nonmetal...
C23C 2800
Patent
active
061206725
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The invention relates to a process for producing inductively operating counting systems, for example inductively operating phone cards.
The normal phone cards that are currently used may be divided into two different categories. Those used in Europe and the USA employ magnetic layers for information storage. The phones in which the card is to be used accordingly include a device for reading and writing information on the card. Thus, stored information, for example the number of charge units still left, is read and overwritten with new information at specific time intervals.
In a further type of phone cards, as are used for example in Brazil, another, substantially simpler principle of information storage is used. These phone cards consist of a dielectric medium on which a thin structured metallic layer has been applied. The essential feature of this metallic layer is its geometrical shave, which is characterised by a large number of fine, conductor-like webs or ridges. The card functions in the following way: the telephone in which the card is used induces successive induction currents in the card which cause these fine webs or ridges to melt one after another, thereby using up the units on the card. These very fine ridges thus function like a fuse. When all these ridges have melted, the card is used up. Such phone cards and the associated phones are simple in design and construction, inexpensive and robust, since no magnetic writing or reading head is required. Phone cards of this type are hereinafter termed inductively operating phone cards. Naturally, this principle can also be used as a counting system for other units.
According to Brazilian Patent Application 9105585 A, these cards are produced by a process in which a first, conducting layer having a relatively high resistance is first of all applied by chemical means on an impermeable, non-porous substrate. A substantially thicker layer of a metal or metal alloy having a considerably lower resistance than that of the first layer is then applied by electrolytic deposition. The second layer consists for example of a tin-lead alloy, while the first layer consists of a currentless deposited nickel layer.
Plastic substrates, preferably of acrylonitrile-butadiene-styrene (ABS) polymers, polyvinyl chlorides or epoxy resins are employed as starting materials in the production process that is currently used. For example, two films or sheets of the aforementioned materials having the appropriate dimensions, e.g. 400.times.600 mm, are first of all welded together. A so-called "multicopy" is thereby obtained. A preliminary treatment is then performed by etching, brushing or similar processes to roughen and/or hydrophilise the nonconducting surface, so as to ensure a sufficient degree of adhesion of the metallic layer to be applied without using an external current.
This process step is then followed by a catalytic activation, for example by coating the plastic surface with palladium nuclei. A chemically reductive metallisation of the whole surface is then carried out, in practice generally a currentless nickel-plating. These process steps are known per se from the metallisation of plastics.
The next step is the formation of a conductive pattern on the metallic layer, especially the fine metal ridges. For this purpose, in a similar way to the production of printed circuit boards, a photo-structurable layer is applied, for example by laminating a photoresist film. So-called negatively operating dry films are used for this purpose, which are also conventionally known in printed circuit board technology. The illumination and development of the conductive pattern are carried out by conventional methods, i.e. after developing, the resist is removed from those places where the conductive pattern is subsequently to be formed. Finally, the metallic layer applied by metallisation without the use of external current is galvanically reinforced at the bare or exposed sites, i.e. in the resist channel, and in fact preferably with a tin-lead alloy.
REFERENCES:
patent: 4666735 (1987-05-01), Hoover et al.
RCA Technical Notes, No. 768, Apr. 1, 1968, pp. 1-5, XP002031760, R.J. Ryan, "Printed Circuit Techniques", see pp. 1-5.
Desmaison Gonzalo Urrutia
Kohnle Franz
Meyer Heinrich
Atotech Duetschland GmbH
Gorgos Kathryn
Wong Edna
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