FI115776B - Method for producing flat wires on a carrier band and a line made by process - Google Patents

Description

1 115776}

METHOD FOR MANUFACTURE THIN WIRES FOR CARRIER TAPE AND METHOD WIRED

The invention relates to a process for producing thin electrical conductors of metal or metal alloy by electrodeposition on a support strip. The surface of the carrier tape is partially covered with an electrically insulating layer and the wires of the desired shape are deposited at the exposed conductive points. The support strip is led to an electrodeposition bath having at least one anode and a cathode. The carrier tape rotates around the support rollers and the cathode, and the wire film precipitated from the brine adheres to the carrier tape. The carrier tape is brought in a coil to electrical precipitation and, after forming separate conductor films, is also wound into a carrier tape roll comprising conductors, which can be further processed at any desired location.

15 Many technical applications require thin conductors with good electrical conductivity. When it comes to fabricating a flexible flat cable (FFC), this is now done by forming a cable from a plurality of parallel copper conductors with an insulator, such as paper or plastic tape, on both sides. Generally, the insulating tape is polyester. Advantages of the conductor 20 are good electrical conductivity, flat shape and good mechanical resistance. Such as are described, for example, in U.S. Patent Publication No. 2002/0062558 and in U.S. Patent No. 6,492,595. The cable is made in the same way as a flexible 'printed circuit (FPC), but in the case of printed circuits, some of the copper is etched to provide a particular circuit pattern. Cable widths are * · 25 today in the order of 0.5 - 3 mm and thickness less than 1 mm. Cables are used eg. automotive, printers, CD-DVD players, TVs, satellite decoders, etc., and their use is growing rapidly.

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A method for producing a thin film by electrolytic doping is known in the art. The method comprises a rotating cathode drum in an electrolysis pool and an arcuate anode of one or more portions at the bottom of the pool. The electrolyte is fed between the anode and the cathode, and as a result, copper foil precipitates on the surface of the cathode drum. When the deposited foil rises above the electrolyte, it is removed from the cathode and subjected to further processing. The method has been developed since the 1930s and is described, for example, in U.S. Patent No. 2,044,415 and U.S. Patent Application Serial No. 5, 2002/5363.

However, electrolytic foil fabrication is focused on producing a single foil from which, for example, antennas and integrated circuits, the excess metal is etched away. The etching occurs after the foil is laminated to, for example, a PVC substrate. A resistor is coated on the copper foil and exposed through a mask of the desired shape. The exposed resist is developed and the portion of the copper foil outside the resist is etched away. The resistor is then removed from the surface of the remaining copper foil product. The foil product is, for example, a microcircuit power cable 15 or a sensor antenna.

U.S. Patent No. 4,053,370 discloses a method for producing patterns of printed circuits electrolytically. In the method, the surface of an endless strip is covered with an electrically insulating layer so that the exposed conductive portions remain in the shape of the desired product. A: The tape is led into an electrolysis pool to rotate around the cathode drum.

The electrolysis pool contains acidic copper salt or electrolyte. Anode is also embedded in the basin, preferably at different distances from the cathode drum: · 'and thus the strip on which the circuit patterns are deposited. The first anode is '···' 25 closer to the ribbon and is used to precipitate the bulk of the pattern as a dense crystal structure. The second anode is located farther from the strip and provides a • • coarser surface layer over the pattern. A coarser surface helps • · *! 'Adhesion of the pattern to the labelstock.

The method described in U.S. Patent No. 4,053,370 is based on: i The endless strip isolation, circuit patterning and pattern removal are all done in the same unit. When the circuit patterns 3 115776 are deposited at the same place where the circuit boards are manufactured, the solution is a good one. Sometimes, however, it is more important that the pattern formed on the carrier can be moved forward and fixed to the carrier only later.

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For the production of very thin electrical conductors of metal or metal alloy by direct electrolytic deposition, a method is now disclosed for direct deposition of the desired shape, functional conductors, on the surface of the support strip. The conductors are made of electrically conductive metals such as copper, silver or gold, but in some cases the metal may also be nickel. The metal or metal alloy is in the metal precipitation pool as a metal salt solution, whereupon electrically conductive conductors are deposited therefrom. The support strip is a conductive thin aluminum foil on which the conductor is deposited. The carrier tape is rolled into an electrolysis and, even after the conductors are formed, is wound into a carrier belt roll comprising the conductors, which can be further processed at the desired location. In the following, when referring to a functional product, only the conductors are referred to, although the desired product may be other. Whenever the text refers to electrodeposition or electrolytic deposition, it means the same thing.

By electrolytic precipitation it is also possible to form non-ribbon electrical conductors. The conductors can be made, for example, in the form of a flat twisted pair cable. The twisted pair cable is an inexpensive form of conductor * · '· * 25 because it differs from parallel cables in that ... in a twin cable, electromagnetic losses and interference are eliminated. Wire • »· • ·! the shape may also be something other than ribbon or twisted pair.

• »'·; The essential features of the invention will be apparent from the appended claims.

• · 4 115776 In the first step of making an electrical conductor, a suitable shape, for example a printing method, is applied to the carrier tape, the aluminum foil, to leave the shape of the incoming conductor unprotected. The insulating treatment of the support strip is carried out either in the same unit as the subsequent electrolytic precipitation or in a separate unit. In the next step, the carrier tape on the coil is rectified and led to an electrodeposition bath, where the conductor precipitates on its surface to the untreated portion of the tape. The applied electric current density and rotational speed of the drum determine the thickness of the metal layer to be produced, whereas the current density and rotational speed can vary within wide limits. The conductor may be further coated with finely divided copper and / or brass or the surface of the conductor may be oxidized by methods known per se. Coating and oxidation increase the adhesion of the conductor to the laminate.

15 Once the conductor has obtained its desired shape and further processing, the carrier tape is wound onto a roll, from which the conductors are secured in a separate operation to the laminate or other substrate. The carrier tape is then removed from the drive tray.

The method of the invention is further described with reference to the accompanying drawings, wherein: Fig. 1 is a schematic drawing of a method according to the invention in which a conductor is formed on a winding carrier tape. Fig. 2 is a schematic drawing of another embodiment of the invention.

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Figure 1 shows that the carrier tape 1 * ♦ * · formed of aluminum foil is subjected to coil 2 for electrolytic precipitation. Prior to this, conductor-like patterns have been formed on the support strip 30 such that the conductor locations remain exposed and an insulating layer is formed on the rest.

*: Of course, if necessary, the insulation treatment can be performed just prior to 5,115,776 electrolysis. The surface insulation can be done, for example, by printing technique, by painting or by gluing the insulating film to the surface of the support tape. The carrier tape is led by means of support rollers 3 to an electrodeposition basin 4 provided with an anode 5 of at least one part and a rotating cathode 6 of roller 5. The electrodes are connected to a power source (not shown in detail). The basin contains electrolyte 7, which in the example case is a copper salt solution, for example a copper sulfate solution with the necessary additives. As stated above, the saline solution may also be a saline solution of another metal or metal compound, the electrolyte being placed in a space between the anode and the cathode, and then back to the pool outside the anode. On the surface of the surface-treated support tape, electrolyte forms conductor-thin conductor films 8, 5 to 500 micrometers thick. The conductor films are marked much larger than they are relative to the manufacturing apparatus. 15 Wire cleaning and drying are known per se and are not illustrated in detail.

It is possible to conduct surface treatment on the conductors formed on the support strip. The surface treatment step may be, for example, electrolytic copper 20 or electrolytic brassing in a pool 9 having a cathode drum 6 of the same type and anodes 5 of the same type as the actual deposition treatment of the conductor v. The electrolyte solution is selected according to the desired coating. Surface treatment of the conductor will make the conductor more secure: its operating base. After further processing, the conductive carrier strip '· **' 25 is wound onto a reel 10 for further processing. When the wires are left on the carrier tape, they are easily delivered in the form of a coil to a processor which; removes the wires from the carrier tape and secures it to the desired substrate.

• · ♦ * • »: The schematic drawing of Figure 2 shows another recycle end of carrier tape 30 in an electrodeposition bath. Over the carrier strip 1 is formed:, '' wire-like patterns so that the points of the wire remain exposed and an insulating layer is formed on the rest. The carrier tape 1 is introduced by a coil 2 115776 into an electrodeposition step. The tank 4 contains electrolyte 7, which in the example case is a copper salt solution, for example a copper sulfate solution with the necessary additives. In this alternative, a plurality of plate-shaped anodes 11 are disposed within the pool.

5 The carrier web passes between the anodes by means of roller cathodes 12 located above the basin and support rollers 13 located in the basin. The anodes are located between the cathode rollers. The electrodes are connected to a power source (not shown in detail). As a result of the treatment, conductor patterns of the desired shape are deposited on the support strip. If surface treatment of wire patterns is desired, it may be done in a manner similar to that described with reference to Figure 1, by means of one or more cathode rolls.

Figure 3 shows a schematic drawing of a conductor 8 made in accordance with the invention. Electrolytically precipitating it is also possible to produce conductors other than straight ribbon. For example, a flat twisted pair cable as shown in the figure can be fabricated directly into a cable shape without the need for separate manufacturing steps such as bonding and etching. The illustration shows only one example of the product being manufactured, since it is clear that the conductor may also be non-twisted-pair.

20 ·: When using low-cost aluminum foil as a carrier tape, the various stages of manufacturing the conductor · * can be distinguished into units that specialize in their field. Thus, one unit may perform surface treatment, the next conductor formation, and a third actual cable formation to the operating substrate. The thickness of the foil is selected as required, but generally the thickness of the foil is in the order of 10 to 500 micrometers. Aluminum foil is advantageous to be re-melted, for example, after disconnecting the conductors. During transport, the foil wrapped in rolls protects the conductors '': from environmental influences.

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Claims (13)

A method for manufacturing flat electrical conductors by means of a carrier strip (1) partially insulated with an electrically insulating 5 layer, wherein the strip is led to an electrodeposition basin (4) provided with an anode (5) and a cathode (6) around which the carrier strip (1) , and a saline solution of a highly conductive metal or alloy is used as the electrolyte, characterized in that the aluminum foil acting as a support strip (1) is subjected to a coil (2) for electrolytic precipitation, whereby the desired wherein the metal is at least one of copper, silver, gold, nickel or an alloy thereof, and the strip (1) on which the functional conductors (8) have been precipitated is wound onto a coil (10) for connection to a processing unit 15. Method according to claim 1, characterized in that the surface treatment and electrolysis of the support strip are carried out in different units. 20 A method according to claim 1, characterized in that! the surface treatment and electrolysis of the support strip are performed in the same unit. Method according to one of Claims 1 to 3, characterized in that the support strip (1) has a thickness of 10 to 500 micrometers. Method according to one of Claims 1 to 4, characterized in that, after the electrodeposition step, the support strip (1) is conducted. 30 surface treatment to the step of coating the guides (8) with copper. * 115776 Method according to one of Claims 1 to 4, characterized in that, after the electrodeposition step, the carrier strip (1) is led to a surface treatment step in which the guides (8) are coated with brass. Method according to one of Claims 1 to 4, characterized in that, after the electrodeposition step, the carrier strip (1) is conducted to a surface treatment step, in which the conductors (7) are oxidized. Method according to one of the preceding claims 1 to 7, characterized in that the electrolytic precipitation is carried out in a basin (4) equipped with a rotating cathode drum (6) and at least one anode (5) located beneath it, wherein the carrier strip (1) rotates around the cathode drum and moves from the coil (2) to the other (10). Method according to one of the preceding claims 1 to 7, characterized in that the electrolytic precipitation is carried out in a basin (4) equipped with at least one plate-like, vertically located anode (11) and at least two roller-type cathodes (12) located above the basin by means of the supporting rollers (13) disposed * ·, · 20 through which the carrier strip (1) passes from the reel (2) to the other (10). 10. Functional electrical conductor, characterized in that the electrically conductive metal or alloy conductor (8) is formed by electrolytically doping the surface of an aluminum carrier strip (1), * which surface is partially insulated with an electrically insulating layer, wherein the metal is at least one of copper; silver, gold, nickel or their alloy; and the conductor (8) of desired shape is deposited on the exposed conductive portion of the tape. . 30 A conductor according to claim 10, characterized in that the conductor (8) is ribbon-like. 9, 115776 A conductor according to claim 10, characterized in that the conductor (8) is a flat pair cable. A conductor according to any one of claims 10 to 12, characterized in that the conductor has a thickness of 5 to 500 micrometers. 10