WO1998004106A1

WO1998004106A1 - Method for making printed circuits and resulting printed circuit

Info

Publication number: WO1998004106A1
Application number: PCT/CH1996/000263
Authority: WO
Inventors: François Droz
Original assignee: Droz Francois
Priority date: 1996-07-18
Filing date: 1996-07-18
Publication date: 1998-01-29
Also published as: CA2260885A1; CA2260885C

Abstract

A method for making a multilayer printed circuit from a dielectric substrate (1) coated with at least one metal layer (2) is disclosed. In the first step, the various conductive paths (8, 8') are marked out by means of a first swaging punch (30) which permanently stamps portions (33) of the substrate and the conductive layer and thus defines two sets of conductive paths on two different levels (A, B). In an additional marking step, notches (7) are formed between adjacent conductive paths, particularly in the areas (41) where the conductive paths change levels (A, B). The notches are formed, e.g., by means of a swaging punch (5) or a cutting table. The method is also suitable for making multilayer circuits and is particularly useful for producing flexible printed circuits, connectors, etc., as well as inductance coils (23) such as those used in smart cards.

Description

Method of manufacturing printed circuits and printed circuit manufactured by this method.

Technical area

The present invention relates to a method of manufacturing printed circuits according to the preamble of claim 1 In addition, the present invention also relates to a printed circuit, for example an inductor whose turns are formed by printed circuit tracks, manufactured according to this process

Prior art

In the chip card and transponder technique, it is often desired to associate an inductance coil with an electronic circuit, for example an integrated circuit, mounted on a printed circuit board. Such a configuration is described for example in WO-91 / 19302 The coil is generally produced by winding a wire around a core. Such coils are complex to produce, and therefore relatively expensive. Furthermore, the connection between the printed circuit and the coil causes certain additional mounting difficulties and poses problems. reliability especially when these elements are integrated into a smart card which generally does not offer optimal protection against deformations and mechanical stresses On the other hand, the thickness of the coil also often poses a problem when it must be integrated in a miniaturized device or in a smart card for which it is desired to keep the standardized thickness of 0.76mm

To overcome these difficulties, devices are also known in which the inductance turns are formed directly by the conductive tracks of the printed circuit. The tracks of the printed circuit are generally produced by photochemical means, which requires numerous expensive operations and uses polluting products

US-4,555,291 describes a method of manufacturing a coil in the form of a printed circuit essentially comprising mechanical steps A film fine metal is precut beforehand in the form of a circuit with multiple turns, leaving interconnection regions between turns to stiffen the sheet thus cut. This sheet is then laminated on a sheet of dielectric material, then a second cutting device applied to this laminate makes it possible to eliminate the interconnections by leaving only the turns of the inductance.

This solution is complex to implement and in particular requires two cutting operations. The thickness of the precut metal film must be sufficient so that it can be transported without tearing; similarly, the width of the turns and of the intervals cut between the turns must be sufficient to ensure a minimum of rigidity in the film before lamination on the dielectric support.

Other known methods for manufacturing a printed circuit from a synthetic film coated with a surface conductive layer include an operation of demarcation of the various conductive tracks constituting the printed circuit by milling the surface layer of the printed circuit (cf. DE-3 330 738 and US-4 138 924). The interstices between conductive tracks therefore necessarily have a fairly large width corresponding at least to the width of the milling tool. It is therefore not possible to obtain an optimal density of tracks. In addition, milling produces chips which must be carefully removed to avoid possible short circuits between tracks. When the surface metal layer is made of an expensive material, for example silver, there is waste of material.

DE-2 758204 describes a method of manufacturing a circuit, in particular an inductance in the form of a printed circuit, in which the different tracks constituting the turns of the coil are demarcated by thermomechanical machining of a synthetic film coated with a surface metal layer. A heated metal tip (3) penetrates into the surface metal layer and simultaneously melts part of the synthetic layer under the metal. This process is more particularly suitable for producing different kinds of devices or for coils whose thickness is not critical. The thickness of the synthetic layer (1) must be thick enough to be cut by the tip (3) and simultaneously heated without being completely traversed. Regulation of the tip temperature poses additional difficulties; in addition, the metal tip (3) must move slowly enough so that the synthetic material has time to melt. This method is therefore unsuitable for manufacturing coils which must be integrated, for example, into smart cards, and the thickness of which as well as the cost and time of manufacture must be minimized.

Other methods of manufacturing a printed circuit are known from a synthetic film coated with a surface conductive layer, in which the various conductive tracks are demarcated by mechanical stamping of said conductive layer carried out by means of a punch. stamping. FR-2 674 724, GB-1138628, or US-4 356 627 for example describe variants of such a method. For example, in US Pat. No. 4,356,627, a dielectric substrate is laminated with a metallic layer, then compressed by a stamping punch, the bearing surface of which against the substrate comprises a bas-relief pattern defining the topology of the tracks of the circuit. . The stamping punch permanently repels portions of the substrate and the metal laminate. The repelled metal portions are separated and electrically insulated from the non-repelled portions along shear lines defined by the stamping punch, rather than by an insulating space extending laterally on the surface of the printed circuit. In this way, by distributing the conductive tracks on different levels pushed back by the punch to different depths, it is possible to use the entire surface of the circuit and therefore to increase the density of the tracks.

However, it is difficult to obtain conductive tracks of very small width by stamping. These methods are therefore not suitable for manufacturing printed circuits with high track density, for example for high inductance coils which must be housed in a reduced volume such as that of a smart card. An object of the present invention is therefore to propose an improved printed circuit manufacturing method, in particular when it is used to manufacture inductors for a smart card whose turns are formed by the conductive tracks of the printed circuit.

Statement of the invention

According to one aspect of the invention, this object is achieved by means of a printed circuit manufacturing method as specified by claim 1.

This method makes it possible to avoid the drawbacks mentioned of the methods of the prior art.

In particular, it is possible with this method to manufacture printed circuits whose conductive tracks are distributed over two or more levels but can nevertheless have a very reduced width.

Thanks to the additional step of demarcating neighboring conductive tracks by cutting with a sharp cutting tool, it is possible to fabricate very high density circuits without the risk of unwanted contacts between neighboring conductive tracks at critical locations.

In particular, according to a preferred characteristic, it is possible to manufacture circuits with very high density without the risk of unwelcome contacts between neighboring conductive tracks at the places where the tracks change level.

The invention also relates to printed circuits produced by this process, in particular coils or connectors produced by this process. The invention further relates to smart cards incorporating a coil made by this process and / or a printed circuit made by this process.

Variants of the invention, in particular specified by the dependent claims, further make it possible to further increase the density of the circuits obtained and / or the inductance of the coils obtained. Brief description of the drawings.

Other aspects and advantages of the invention will emerge from the description and the appended figures which illustrate:

FIG. 1, a sectional view of a dielectric film coated with a surface conductive layer suitable for use with the present invention,

FIG. 2, a sectional view of a stamping punch and of a dielectric film coated with a surface conductive layer before demarcation of the conductive tracks,

FIG. 3, a sectional view of a dielectric film coated with a surface conductive layer after a first operation of demarcating the conductive tracks by repelling conductive material,

FIG. 4, a sectional view of a second stamping punch and of a dielectric film coated with a surface conductive layer between the two operations for demarcating the conductive tracks,

FIG. 5, a sectional view of a dielectric film coated with a surface conductive layer after the additional operation of demarcating the conductive tracks by cutting by means of the second stamping punch,

FIG. 6, a perspective view of the second stamping punch and of a portion of the dielectric film coated with a surface conductive layer after the first operation of demarcating the conductive tracks,

FIG. 7, a perspective view of a dielectric film and of a surface conductive layer machined before rolling according to a variant of the invention, FIG. 8, a sectional view of a dielectric film coated on one face with several surface conductive layers, after the two operations of demarcating the conductive tracks,

FIG. 9, a perspective view of a smart card comprising a printed circuit according to the invention,

FIG. 10, a perspective view of a printed circuit before folding, produced according to a variant of the invention comprising a folding step,

Figure 1 illustrates a sectional view of a dielectric film 1 coated with a surface conductive layer 2. The film 1 consists of any dielectric material, preferably a sufficiently ductile synthetic material. Depending on the application, a flexible film will be chosen or, on the contrary, a more rigid substrate. The film 1 can also be made of a composite or multilayer material, for example a laminate comprising several layers of synthetic material, cardboard and / or metal.

The surface conductive layer 2 is applied by a known method to the film 1 and held for example by welding or by means of glue 4. The glue 4 can for example be a hot glue or a cold glue; it is also possible to use as adhesive 4 a double-sided adhesive sheet or a fusible film. Layer 2 is made of a suitable metal, for example copper, aluminum, silver or a conductive alloy.

The laminate of FIG. 1 can for example be manufactured according to one of the methods and with the materials described in the various examples of US Pat. No. 4,356,627.

2 shows a sectional view of a first stamping punch 30 above the printed circuit before the first operation of demarcation of the conductive tracks. The bearing surface of the stamping punch 30 facing the circuit has a low relief pattern 31, 32 corresponding to the topology of the conductive tracks of the printed circuit. The stamping punch 30 is lowered by means not shown, with sufficient pressure so that the protruding portions 31 of the punch push the surface metal layer 2. Then it is raised, preferably just before or just after the recessed portions 32 of the punch do not touch the surface layer 2.

FIG. 3 shows the film in section after this first demarcation operation of the conductive tracks 8. The protruding portions 31 of the stamping punch 30 have permanently repelled portions 33 of the surface metal layer 2 leaving the other portions 34 intact. - your. The surface metal layer 2 is therefore divided by this first operation into two sets of conductive tracks 8, respectively 8 ′, distributed over two different levels A, respectively B. If necessary, it is possible to distribute the tracks over more than two different levels using a stamping punch 30 with protrusions 32 of variable height.

To guarantee effective insulation between the tracks 8, 8 ′, the dielectric material 1 must withstand abrupt depressions and allow the metal 2 to tear cleanly on the level change line. It is however very difficult to prevent any short circuit between tracks 8, 8 ′ when the width of these tracks is very reduced, or when the depth of repulsion between levels A and B is limited by the maximum thickness to be given to the circuit.

These problems are solved according to the invention thanks to an additional operation of demarcating the tracks. In this example, this additional operation is performed after the first demarcation operation described above. We will see below a preferred variant in which this additional demarcation operation is carried out before the first demarcation operation.

To separate the neighboring conductive tracks 8, 8 ′ at the critical locations - for example at the locations where the width of the tracks is reduced, or at other particular locations discussed below in connection with FIG. 6, a second stamping punch 5 (figure 4) is used. The second punch stamping 5 has cutting contact surfaces 6 with the surface layer 2 on the synthetic film 1.

The second stamping punch 5 is lowered by means not shown, with a pressure just sufficient for the cutting contact surfaces 6 to perforate and cut the surface metal layer 2. The profile of the surfaces 6 is sufficiently sharp so that the punch cutting fine cuts 7 (Figure 5) in layer 2, without removal of conductive material as in milling processes or pushing back to depth. The metallic material is here incised by the surfaces 6.

We see that the notches 7 are just deep enough to pass through the metal layer 2 and the possible adhesive layer 4 and possibly touch the synthetic dielectric layer 1. In a variant, the notches 7 completely pass through only the surface metal layer, the bottom notches being in the middle of the adhesive layer 4. In this way, the synthetic film 1 is as little weakened as necessary by the machining of the notches 7; it is thus possible to give it a minimum thickness.

To optimize the density of the conductive tracks 8 on the printed circuit, the width of the notches 7 is chosen to be as fine as possible. If the substrate 1 is particularly flexible, the width will however be sufficient to avoid any risk of short-circuiting of the conductive tracks 8.

The second punch 5 preferably has insulated points 6 intended to locally cut notches 7 at critical locations. In a variant particularly suitable for the production of smaller series or of prototypes, the notches 7, 7 ′, 7 "can be cut by means of a conventional cutting table known for example in the field of cutting self-adhesive films for advertising or other realizations. In this case, the pattern of demarcations between conductive tracks is drawn beforehand using suitable software on a computer, then stored in an electronic memory. This drawing is then used to control the sequential movement of a blade on the cutting table. Some cutting tables allow control of the direction of the blade in the rounding and / or back and forth movements of the blade. The shape of the blade will be chosen accordingly and according to the thickness of the metal layer to be cut. The blade is sharp enough to cut the surface layer without removing conductive material or pushing it back to depth. Its width is minimal in order to allow conductive tracks 8 of maximum width to remain. The depth is just sufficient to pass through the surface metal layer without weakening the dielectric layer 1 too much, which may thus have a minimum thickness. If notches of various depths are necessary, for example to make multilayer circuits with variable patterns on the different layers, it is necessary to replace the blade at each desired change in depth. It is also possible to use a cutting table provided with several blade holders equipped with blades of different depths, or to provide means for controlling the penetration depth of the blade.

FIG. 6 illustrates a perspective view of the second stamping punch 5 and of a portion of the dielectric film 1 coated with a surface conductive layer after the first operation of demarcation of the conductive tracks. FIG. 6 more particularly illustrates an area 40 of the circuit after stamping in which the conductive tracks 8, 8 ′ change level. In the lower part of the circuit portion shown, the conductive tracks 8, 8 ′ are distributed alternately over the two levels A and B defined by the first stamping punch 30 used in the first operation. In the middle part 40, the tracks 8, 8 'then change level; the tracks 8 which occupied the upper level (not pushed back) A progressively descend to the lower level (pushed back) B and vice versa. The slope of the transition zone 40 is determined by the shape given to the first stamping punch 30.

At the location 41 where two neighboring tracks 8, 8 'simultaneously change level A, B, an electrical contact remains between these tracks, which cannot be removed by simple pushing of material. These residual contact points are separated before or after by cutting, either by means of the second stamping punch 5 with cutting surfaces, either by means of a traditional cutting table, as explained above.

The additional operation of demarcating the tracks by cutting by means of a second punch 5 or a cutting table can also be used to create several sets of tracks on the same level A or B, or to share tracks 8, 8 'obtained by prior stamping and pushing and thus further increase the density of the tracks on the printed circuit.

Instead of carrying out the additional operation of demarcating tracks by cutting after the first operation of demarcation by stamping-pushing back, as described above, it is also possible to reverse the order of these two operations. FIG. 7 describes a variant of the process in which a metal film 2 is pre-machined even before lamination on the dielectric substrate 1. Holes or slots 7 are previously machined by any known method, for example by cutting, by photochemical operation or by drilling or milling, at determined locations in the conductive film 1. These holes make it possible to demarcate the neighboring conductive tracks locally at the critical locations 41 where a contact would remain if a single stamping-repelling operation was carried out. The conductive film 2 is then assembled in the manner indicated above on the dielectric substrate 1, then the laminate thus obtained is placed under the first punch 30 and stamped with material repulsion, in the manner described above.

In a variant, it is naturally also possible to machine notches in the conductive layer after rolling. These three variants (machining before rolling, after rolling or after embossing) can also be combined, notches or separations being carried out at different stages.

In a variant not illustrated, the two operations of demarcation of conductive tracks by cutting and by stamping-repelling are carried out successively with a single punch. For this purpose, stamping punches are used comprising both cutting surfaces 6 first incising the conductive layer 2 and flat surfaces 31, less prominent. tes, then pushing back the material when the punch is further lowered. To avoid a depth of incision (through surfaces 6) much greater than the depth of repulsion (through surfaces 31), it is possible to make the cutting surfaces 6 retractable, for example by means of springs. In this way, when the punch is lowered beyond a certain depth, the cutting surfaces 6 retract into the punch, without sinking further into the material when the punch continues to be lowered.

Those skilled in the art will understand that it is naturally possible to manufacture double-sided printed circuits with the method of the invention, the method described above being applied to each face of a printed circuit.

FIG. 8 illustrates a variant of the method applied to dielectric films coated on one face with several surface conductive layers. The dielectric film 1 is coated in this example with a first metallic film 2 fixed by a first layer of adhesive 4. A second metallic film 2 'is fixed on the first film 2 by a second layer of adhesive 4'. The second layer of adhesive 4 'also acts as an insulator between the two metal layers 2 and 2'. If necessary, it is also possible to insert an additional layer of insulation between the two metal layers, for example an additional synthetic layer. It is also naturally possible to superimpose more than two metal layers 2, 2 'one above the other.

The first stamping punch used has permanently repelled portions 33 of the surface metal layer 2, leaving the other portions 34 of the layer intact. The surface metal layers 2 are therefore displaced by this first operation on at least two different levels A, respectively B. In this example, a portion 33 ′ is pushed back by the stamping punch to an intermediate level, so that the upper metal layer 2 'is pushed back into this portion 33' to a depth corresponding approximately to the position of a lower metal layer 2 not pushed back. To avoid electrical contact between this partially repelled portion 33 ′ and the adjacent non repelled portions 34, separation notches 7 must be machined during the second operation of demarcating the tracks by cutting as described above.

By connecting the different layers together at the appropriate places, for example with metallized holes, this arrangement makes it possible to produce high inductance circuits. By combining the operations of demarcating tracks by stamping-embossing and by cutting to variable depth on a multi-layer and possibly double-sided circuit, it is possible to obtain a very great freedom of topology and an optimal density of tracks. This freedom of topology can be further increased by machining notches 7 in the lower metal layers 2 before rolling the upper metal layers 2 '.

This process is particularly suitable for the manufacture of printed circuits, the thickness and possibly the weight of which must be minimized. For example, this method is suitable for manufacturing printed circuits intended for smart cards.

FIG. 9 illustrates a printed circuit for a smart card according to the invention.

The smart card consists of a single-sided printed circuit 21 according to the invention, corresponding for example to one of the variants illustrated in FIGS. 5, 7 or 8, and of an upper protective sheet 22. The printed circuit 21 is formed of a sufficiently rigid substrate 1 and of one or more conductive surface layers 2, 2 ′, etc. The underside of the printed circuit 21, not occupied by the conductive tracks, can be printed .

A spiral conductive track 8, 8 ', constituting an inductive element

23, is machined by stamping-embossing according to the method described above in the conductive layer. The number of turns is chosen according to the desired inductance. The machining process of the invention makes it possible to place tracks 8, 8 ′ over the entire surface of the printed circuit and therefore to accommodate on a given surface a maximum of turns and therefore to obtain a high inductance. vee. To further increase the inductance, a circuit with several conductive layers 2, 2 ′, etc. will preferably be chosen. according to the example of Figure 8, and / or a double-sided circuit.

At each turn of the turn, it is necessary for the tracks 8, 8 'to change level A, B to avoid any electrical contact with the neighboring turn. A level change zone 40, similar to that discussed in connection with FIG. 6, is therefore provided. Notches 7 or partitions must be made in this zone 40 during a second demarcation operation to cut the electrical connections which would remain between neighboring spiers.

A housing 24 is provided in a portion of the lower sheet 21 not occupied by the conductive tracks 8, 8 ', in this example inside the inductive element 23. An integrated circuit 25 is fixed in this housing 24 and connected at both ends of the inductive element 23. The connection between the circuit 25 and the internal portion of the inductive element 23 can be made directly. The connection with the external portion of the inductive element 23 must however be made by means of a bridge 26 over the turns 8, 8 '. The bridge 26 can for example be constituted by a single wire welded over or under the conductive tracks 8, 8 '. In the case of a circuit with several conductive layers, it is also possible to use one of the metallized layers to make the bridge 26. Finally, the bridge can be integrated into the substrate 1 before the conductive layers 2 are laminated.

Depending on the desired application and the residual space available on the card, other components than the integrated circuit 25 and the inductive element 23 can be integrated on the printed circuit 21. It is for example possible to place on the circuit an accumulator (not shown) which can be recharged from the outside by means of the inductive element 23. These other components will ideally be connected to each other and with the elements 23 and 25 by means of conductive tracks machined in the manner described above in the or the surface conductive layers 2. After machining the notches 7 and connecting the various components to each other, the upper protective sheet 22 is placed on the lower sheet 21 and assembled by known means, for example by gluing, then optionally printed. For example, a hot glue will be chosen which, by melting, fills the notches 7 and thus prevents any risk of short circuits between neighboring conductive tracks. The glue also makes it possible to compensate for the unevenness of the surface of the printed circuit and therefore to obtain an external surface of the smart card remarkably flat and easy to print.

The housing 24 for the integrated circuit 25 in the lower sheet 21 may if necessary be supplemented by a corresponding housing in the upper sheet 22. It is also possible to give up the housing 24 in the lower sheet 21, and to use a corresponding housing deeper in the upper sheet 22. In a variant, the upper sheet 22 and / or the lower sheet 21 are provided with a window instead of a housing, revealing on the outside of the card the circuit 25, connection lugs for circuit 25 or contacts linked to circuit 25.

Alternatively, the card could also consist of a printed circuit, for example a double-sided printed circuit, assembled between a lower protective sheet and an upper protective sheet assembled to the printed circuit by any known means. , for example by gluing.

FIG. 10 illustrates a printed circuit in an intermediate manufacturing step, according to an alternative method intended to facilitate the connection between the circuit 25 and the external portion 26 of the inductive element 23. This variant is for example intended for security labels to protect goods, but can also be applied to smart cards or other devices. A printed circuit comprising a portion in the form of an inductive element 23 is machined in the manner described above on a flexible substrate 1, for example on a cardboard support. The inductive element 23 occupies only about half of the total surface of the substrate 1. One of the ends 26 of the inductive element 23 extends over the other half of the sheet 21. This end can for example be formed by a discreet wire welded with the portion external of the inductive element 23. In a variant, this end 26 is machined by incision in the surface conductive layer 2, in the manner described above. The rest of the surface layer 2 on this half of the sheet 21 can then be peeled off, leaving only the end 26.

An electronic or electrical element 25 is assembled in a zone of the sheet 21 not occupied by the conductive tracks, in this example inside the inductive element 23. The element 25 can for example be an integrated circuit or a fuse . It is connected to the internal portion of the inductive element 23 via a conductive contact pad 51. In addition, the element 25 is connected to a second contact pad 52 intended to establish the connection with the end 26 of the inductive element 23.

After machining of the conductive tracks constituting the coil and assembly of the element 25, half of the sheet 21 occupied by the conductive tracks is covered with an insulating layer (not shown). For this, the inductive element 23 can for example be covered with an insulating lacquer layer or an insulating adhesive sheet. The contact area 52 is however not covered by the insulating layer.

The sheet 21 is then folded back on itself along a folding axis 53, so that the two halves mentioned overlap. The end 26 of the inductive element 23 is thus brought into electrical contact with the contact pad 52. A connection is thus very simply formed between the external portion of the inductive element 23 and the element 25. The two folded halves of the sheet 21 can be fixed to each other for example by gluing.

This process is also perfectly suited for the manufacture of flexible printed circuits. Such circuits are used, for example, to manufacture flexible connectors. In addition, the method is perfectly suited whenever a maximum density of the tracks on the surface of the printed circuit must be obtained.

Those skilled in the art will further realize that this method can also be used in combination with any other known method of manufacturing cation of printed circuits. It is for example possible to produce cards on which part of the conductive tracks are produced or demarcated by electrochemical means for example, the rest being machined in the manner specified in the claims.

Those skilled in the art will realize that the expression printed circuit is used in this description and in the claims by convention, although the invention applies especially to circuits and cards produced without a printing step in the usual sense.

Claims

claims

1. Method for manufacturing a printed circuit (21; 31) from a dielectric substrate (1) coated with at least one surface conductive layer (2, 2 ′), comprising a first step of demarcating conductive tracks by stamping of said conductive layer (2) by means of a first stamping punch (30), the bearing surface of which comprises a pattern in low relief defining the topology of the conductive tracks (8, 8 ') of the printed circuit, so permanently repelling portions (33, 33 ') of said dielectric substrate (1) and of said surface conductive layer (2, 2') and thus defining a first set of conductive tracks (8) on a first level (A ) and at least one second set of conductive tracks (8 ') on at least one second level (B) pushed back by said stamping punch (30),

characterized in that it further comprises

an additional step of demarcating neighboring conductive tracks by cutting by means of a sharp cutting tool (5).

2. Method according to claim 1, characterized in that said additional demarcation step is performed only locally at the locations (41) where said conductive tracks (8, 8 ') change level (A, B).

3. Method according to one of the preceding claims, characterized in that said additional demarcation step is carried out before said first step.

4. Method according to one of the preceding claims, characterized in that said additional demarcation step is carried out after said first step.

5. Method according to one of the preceding claims, characterized in that said additional step of demarcating neighboring conductive tracks (8, 8 ') is carried out by means of a second stamping punch (5) having cutting contact surfaces (6) with said surface conductive layer (2) and simultaneously cutting notches (7) separating said conductive tracks.

6. Method according to one of the preceding claims, characterized in that said cutting tool is a knife or a blade sequentially cutting notches (7) separating the neighboring conductive tracks (8, 8 ') according to a pattern previously recorded in a electronic memory.

7. Method according to one of claims 1 to 5, characterized in that said additional step of demarcation of adjacent conductive tracks (8, 8 ') is carried out by means of a drilling or milling tool.

8. Method according to the preceding claim, characterized in that said dielectric substrate (1) is coated with several superimposed conductive layers (2, 2 ') insulated from each other, all of said conductive layers being repelled simultaneously by said first stamping punch (30 ).

9. Method according to one of the preceding claims, characterized in that each face of said dielectric substrate is coated with one or more surface conductive layers (2), different conductive tracks (8, 8 ') being demarcated by stamping on each face .

10. Method according to one of the preceding claims, characterized in that it further comprises a step of machining in said film a housing (24) intended to house an electronic component (25) connected to said conductive tracks (8 , 8 ').

11. Method according to one of the preceding claims, characterized in that it further comprises a step of covering part of the conductive tracks (8) with an insulating layer, and a step of folding said electrical film along an axis folding (53), so as to create at least one electric bridge (26) between portions (26, 52) of the electric tracks (8) not covered by said insulating layer.

12. Printed circuit (21; 31) manufactured according to the method of one of claims 1 to 11.

13. Coil (23) whose turns are formed by the conductive tracks of a printed circuit (21; 31) manufactured according to the method of one of claims 1 to 11.

14. Chip card (20; 30) incorporating a coil (23) according to claim 13 and / or a printed circuit (21; 31) according to claim 12.

15. Chip card (20) according to the preceding claim, characterized in that said printed circuit (21) is a circuit comprising conductive tracks on a first face only, said face being covered by a protective sheet (22), the face of the printed circuit (21) opposite said face being an external face of said chip card.

16. Chip card (30) according to the preceding claim, characterized in that said printed circuit (31) is assembled between a lower protective sheet and an upper protective sheet.

17. Connector incorporating a printed circuit (21; 31) according to claim 12.