US2964587A - Tape conductor - Google Patents

Description

0. N. MINOT TAPE CONDUCTOR Filed Nov.

Dec. 13, 19 0 Fig. l

mxaysax INVENTQR. OTIS N. MINOT ATTORNEYS United States Patent TAPE CONDUCTOR Otis N. Minot, 22 Eliot Road, Lexington 73, Mass.

Filed NOV. 16, 1956, S91. N0. 622,574

8 Claims. (Cl. 174-117) This invention relates in general to electrical conductors and consists in a novel conductor in the form of a thin flat tape or strip useful in many types of electrical circuits.

An insulated electrical conductor in the form of a tape offers numerous advantages. In particular, circuits may be easily run from one place to another over supporting surfaces in a manner requiring minimum space and facilitating concealment. Where a circuit must pass through a wall or partition, thin flat conductors require only a slit or crack, and may frequently pass between a door and its jam. A further advantage of the tape form of conductor arises from the greater surface-to-cross-sectional-area ratio it provides over a circular conductor, by which the dissipation of heat is greatly increased, and the current carrying capacity of a given size conductor is enhanced.

A tape conductor providing these advantages should be such that circuit connections may be made and then covered so as to be concealed and protected easily. Not only should the conductor be readily exposed, it should also be accessible in a manner that permits the making of a connection to it. Preferably, therefore, the conductor is separable from the insulation so that a solder, crimp or pressure connection can be made without destroying the insulation, and the insulation is advantageously such that it may be reapplied to the conductor after the connection has been made. A tape having these features should moreover be a rugged, flexible, easily installed item with which few, if any, special tools or techniques are required, and must above all be inexpensive.

In general the tape form conductor of this invention consists in a thin flat conductive strip which is sandwiched between layers of flexible insulating sheet material. These layers of sheet material form an insulating covering for the conductive strip which also conceals and physically protects the strip. The layers are of width greater than the strip so as to project beyond its edge.

The insulating layers of the tape conductor are adhesively bonded together in a manner permitting them to be peeled apart. The strip is arranged to be carried by one of the layers when they are separated so as to be easily accessible. The conductive strip is accordingly adhesively bonded to only one of the layers, or, alternatively, to both of the layers with the adhesion toone being sufliciently stronger'than the adhesion to the other that the strip is carried entirely by the one when the layers are separated. The strip is preferably bonded to the insulating layer in a manner permitting it to be peeled from the layer.

The layer carrying the conductor will usually be the cover layer which when peeled from the other, or base, layer raises the conductor to an accessible location. The conductor strip may then be peeled from the cover layer so that contact to it may be made.

The conductive strip may be any of numerous conductive materials in the form of a strip of foil or in the 2,964,587 Patented Dec. 13, 1960 form of particles arranged sufficiently densely as to carry a current. The numerous varieties of material and structure make it possible to form the strip of varied electrical characteristics. Similarly the insulating layers may be formed of any flexible insulating sheet material and the adhesive combining the layers with each other and with the strip and having the desired characteristics may be any of those well-known in the art as suitable for combining the particular materials in the proper manner. In this connection the adhesive is preferably one characterized as being normally tacky and pressure sensitive, and it is applied in a manner to be non-offsetting.

The tape conductor of this invention may include any of numerous modifications. In its simplest embodiment it consists of a single conductive strip located between two insulating layers, but in more complex forms two or more strips may be present. The outer layers of insulating material may carry an adhesive coating, e.g. of pressure-sensitive adhesive, to facilitate mounting the tape conductor on a supporting surface over which it is to be run. One or both of the outer layers may also be per forated so that a part of the layer may be torn from the rest and peeled away to expose the conductive strip only in selected areas. To simplify the separation of the two layers, or the tearing of part of one layer from the rest, a cord may also be run between the layers such that when stripped out the layer is cut or separated from the other layer. Alternatively separation of the layers may be facilitated by offsetting the layers or by inserting between them an outwardly extending tab or strip having a surface of low adhesive attraction.

The tape conductors of this invention are Well-suited for many types of circuits such as control circuits useful for lighting or as a power supply for small motors, relay circuits, and circuits in electronic devices. It should be of course recognized that a tape conductor, as any conductor, is limited in its current carrying capacity by the cross-sectional area of the conductor, and in its voltage by the amount of insulation. In some cases the tape conductor will employ a thin foil of metal having low power capacity while in other cases the metal will be thicker. The construction of tapes of this invention permits considerable latitude in the dimensions of the conductor; for any particular use well-known circuit design standards may be applied in designing or selecting a proper conductor. It is also contemplated that in some cases the tape conductor of this invention may be used to introduce resistance into a circuit. It may accordingly be desired that the conductive strips be moderately, or even poorly, conductive, and it may for such uses be formed of a resistance material such as carbon or Nichrome. The improved heat dissipating qualities of the tape conductor are advantageously utilized in such embodiments.

A conductor of this invention may readily be run over supporting surfaces and through small openings in a manner permitting very simple establishment of any desired circuit layout with a minimum of cutting of partitions and without separate fasteners. The making of electrical connections, either to the apparatus or equipment with the tape conductors are used, or in joining one tape conductor with another, is easily accomplished. As has been pointed out, the conductive strip may be exposed and brought to an accessible location by peeling the insulating layers apart, and the strip may, if desired, be stripped from the layer carrying it. Where thus exposed it may be joined to almost any type of connection, as a post and thumbscrew, clip, or it may be crimped, soldered, or cold-pressure welded to make an electrical connection.

Special sheet metal connectors formed with outward projections are also very useful in connecting one tape to another easily and with a minimum of .special equipment. A connector need only be placed between two conductors which are to be connected, and the conductors are then pressed together so as to be pierced by the projections which then bend around the conductors and assure good electrical contact. The same purpose may be served by the insertion of various other metal pieces having sharp points or edges which will make positive contact with the conductors.

The manufacture of the conductors of this invention is preferably carried out by applying the adhesive to one or more of the insulating layers and then assembling them under pressure with the conductive strip between them. The non-adhesive surfaces of the insulating layers may be treated in well known manner to facilitate the peeling of the adhesive coated face from them, so that the layers may be readily peeled apart to expose the conductive strip or to peel the tape conductor from a roll. Where the tape conductor is to be adherent to a supporting surface the base layer will carry an adhesive coating, preferably one that is pressure-sensitive, on its outer surface, and the inner surface of either the cover layer or the base layer will also carry a coating of adhesive by which the cover and base layers are adhered together and by which the metallic strip is adhered to one of them. Since there are now commercially available many pressure-sensitive insulating tapes, these may Well be used in fabricating the tape conductors of this invention, by assembling one as the base layer and another as the cover layer with the conductive strip between them. The adhesive of the cover layer serves to combine the assembly.

Commercially available tapes of this type are generally treated at their back surfaces to reduce the adhesion of the adhesive layer to them. Because of this reduced adhesion to the back surface, the cover layer may be peeled from the base layer more easily than the base layer is peeled from a supporting surface to which it is applied. This facilitates the making of connections to the tape conductor after it has been applied to its supporting surface, since the cover layer may be easily removed from the base layer without pulling the base layer from its supporting surface. Moreover, since the cover layer carries the adhesive which holds the conductive strip, peeling away the cover layer from the base layer also carries the conductive strip from the base layer to an accessible location.

The invention is described in detail below with reference to preferred embodiments and modifications shown in the accompanying drawings in which:

Fig. 1 is a transverse cross-section of one embodiment of this invention;

Fig. 2 is a view in perspective of the embodiment shown in Fig. 1 showing the cover layer peeled back with the metallic strip peeled from it;

Fig. 3 is a schematic perspective view, partly cut away to reveal structural details, of a second embodiment of this invention;

Figs. 4 and 5 are respectively a perspective view and a side elevation illustrating a connection of two tape conductors utilizing a metallic insert to join the strips.

In the embodiment the tape conductor consists of a conductive strip 10, of e.g. copper or aluminum foil, assembled between a base layer 12 and a cover layer 14, each of an insulating sheet material. The cover layer 14 is bonded by an adhesive coating 15 to the base layer 12 and the strip 11) is adhesively bonded to the cover layer 14 but is unbonded to the base layer 10. Thus when the cover layer 14 is stripped from the base layer 12, as shown in Fig. 2, the strip 10 is carried by the cover layer from which it may be stripped, separately.

Both the cover layer 14 and the base layer 12 may be of any insulating sheet material Well known to the art, e.g., coated paper, fabric, or plastic sheet materials such as cellulose, vinyl plastics, rubber or the like. The adhesive material is most preferably one of those well known in the art as a non-offsetting, tacky, pressure-sensitive adhesive so as to form a layer which will adhere securely to its carrying surface and provide a peelable bond which retains its tackiness. The layers may thus be separated from each other and from the conductive strip, while being subject to reassembly simply by pressing the components together again.

Where two like materials are adhesively combined face to face, as are the base layer and cover layer, it may be necessary to treat the surface that does not carry the adhesive to reduce its affinity for the adhesive and to prevent the adhesive from off-setting to it by means well-known in the art. Both the base layer and cover layer may conveniently be formed from a commercial, pressure-sensitive, insulating tape material obtainable in roll form. The back surface of such tape is generally of reduced affinity for the adhesive layer carried on the other side, to permit easy unrolling of the tape without off-setting the adhesive. Such a tape is well suited for use in this invention because of its non-offsetting properties.

In the embodiment shown in Figs. 1 and 2 the base layer 12 is provided with an adhesive coating 16 on its outer surface. This coating permits the tape conductor to be applied to a supporting surface such as a wall or assembly panel. In this form, the tape conductor may conveniently be formed by combining two lengths of an electrical insulating tape each having a non-off-setting, tacky, pressure-sensitive adhesive coating, with the adhesive layer 15 of the cover layer 14 being applied to the back (non-adhesive) surface of the base layer 12 and with a narrow conductive strip 10 inserted between the layers. When assembled, the cover layer 14 is peelably adhered to the base layer 12 and to the strip 10, and may readily be separated to provide access to the strip. Tape of this form may be packaged in the form of rolls, from which running lengths may be removed as needed. Advantageously the back of the cover layer or the adhesive of the base layer may be such that the adhesive affinity of one for the other is reduced so as to reduce the possibility of separating the cover layer from the base layer when the tape is unrolled. Or, alternatively, a liner of low adhesive affinity may be inserted, at any convenient stage of assembly, so that it lies between base adhesive 16 and the cover layer 14.

In the embodiment shown in Fig. 3, the insulated tape conductor carries a pair of conductive strips 10 between the base layer 12 and the cover layer 14. Selective access to either or both strips is provided for by dividing the cover layer 14 into both longitudinal and transverse hands by perforations and by placing the adhesive in a manner that facilitates separation of the plies only in selected rows or columns.

As shown the cover layer 14 is divided into six longitudinal bands 14a-f by five lines of perforations 18, so that there is a band generally overlying each strip 10 and a band on each side. These perforations 18 make it possible to raise only the band over the strip together with the underlying strip, as in the manner shown at A. Alternatively where complete separation of the conductors is desired, the tape may be ripped at the center row of perforations. A rip cord 19 underlying this row may be provided to facilitate this separation.

The cover layer is also divided into transverse hands by lines of perforations 20 so that access may be had to one or both of the conductors at a location other than at the ends of a length of tape conductor. A transverse band of the cover layer 14 may thus be separated from the base layer 12 to expose either or both of the conductive strips, as shown in Fig. 3 at B.

The arrangement of the adhesive in this embodiment, as outlined by the dash lines, is designed to facilitate separation of the cover layer 14 in certain of the bands while rendering separation more difficult in others.

The adhesive is arranged so that the conductive strips 10 are adhesively bonded to only the cover ply 14 and only in the regions of alternate transverse bands, as in dicated at C. The regions of the other transverse bands, which are designated to be most easily raised, are not bonded to the conductive strips. Similarly, the adhesive bonding of the cover layer 14 to the base layer 12 alternates between a strong bond and a weak bond (as suggested by the varying areas over which the adhesive is shown to be applied) with the latter occurring in the transverse bands designed for easy separation. These bands are thus most readily separated from the base layer as at B and from the conductive strip while the bordering bands are held securely down.

The application of adhesive in the embodiment illustrated in Fig. 3 is shown as being in a varying pattern to provide greater or lesser adhesive attachment in the desired manner. Where stronger attachment is desired, the adhesive is applied in a wide pattern, and where weaker attachment is desired, the pattern is narrower. Alternatively, however, different adhesives may be applied in a non-varient strip to achieve the same result, or the adhesive may be applied as discrete dots which are of high frequently and densely grouped where strong adhesion is desired, and sparsely grouped where the adhesion is to be weaker.

In Figs. 4 and 5 is shown one of several possible forms of a metallic connector element useful in joining the metallic strips of two conductor tapes. The connector 32 is in the form of a thin flat ductile metal plate from which pointed projections 33 are punched out and raised. By stripping the metallic strips from between their base layers 12 and cover layers 14 and then assembling the strips one on each side of the connector, a secure electrical contact may be made, with the spikes firmly embedded in the strips. The cover and base layers may then be reapplied to form a covering of double thickness at the location of the splice. As shown in Fig. 5, the projections are advantageously inclined to form an acute angle with the body of the connector 32 so that they will bend flat against the connector under compression. Preferably the projections 33 are inclined in opposite directions outwardly toward the ends of the connector. When pressed flat, the projections lie divergently and anchor the connector firmly in place.

The manufacture of tape conductor of this invention is preferably carried out by applying the adhesive in any well-known manner to the cover layer, and, if desired, also to the base layer. The opposite surfaces of these layers are advantageously treated in known manner to reduce the adhesion of the adhesive to them and to facilitate the peeling away of the overlying layers. The cover layer 14 is then assembled with the conductive strip 10, such as a strip of aluminum, copper or other foil, and with the base layer. The cover layer, conductive strip and base layer may be assembled simultaneously, as by feeding them together into the nip of a pair of pressure rollers, or by combining the components in succession.

Conveniently the cover layer and base layer are formed of ordinary pressure-sensitive adhesive tape commercially available in rolls and manufacture of the tape conductor consists simply in assembling the conductive strip between the back side of one tape (the base layer) and the adhesive side of another tape (the cover layer) and pressing the assembly together. The conductive strip is then adhered to the cover layer in peelable manner and that layer becomes peelably secured to the base layer. Since the back side of the base layer is generally treated to be of reduced attraction of the adhesive to facilitate separation from the roll of tape, the assembly may be readily peeled apart, or re-rolled, without blocking or oflsetting.

A further modification consists in forming the conductive strip from particles of conductive or partially conductive material. This may be done by applying a pow- '6 der of conductive particles as a strip to one of the outer insulating layers, and then combining that layer with the other. The particles may for instance be applied to the adhesive surface 15 of the cover ply 14, or an adhesive surface to receive and hold them may be applied specially for that purpose. v I I The conductive particles may similarly be incorporated in a liquid vehicle and applied to one of the insulating layers as a conductive ink or paint which will dry or 'set to form the conductive strip.

Where a tape of extreme flexibility is desired, the tape conductor of this invention may be creped to permit lateral bending. The assembled tape conductor may be creped by well-known means after it has been assembled, or alternatively component, base and cover layers and conductive strip may be creped before assembly.

From the foregoing disclosure it is believed apparent that this invention provides a novel tape form of conductor which lends itself to a great variety of modifications, a representative few of which are described herein in detail. It is contemplated that other modifications will readily occur to those skilled in the art and that such modifications may be made without departing from this invention.

Having thus disclosed my invention and described in detail preferred embodiments thereof, I claim and desire to secure by Letters Patent:

1. An insulated electrical conductor comprising a long narrow tape-like base layer of flexible insulating sheet material and an overlying long narrow tape-like cover layer of flexible insulating sheet material, a thin flat conductive strip between the inside surfaces of said layers extending longitudinally the full length of said layers, said strip being bonded to said cover layer in selected regions and unbonded to said cover layer in other regions and substantially less securely bonded to said base layer, pressure sensitive adhesive peelably bonding said layers together, adhesive on the outer side of said base layer, and parallel rows of perforations extending across said cover layer defining a tab crossing said strip Where said cover layer is unbonded to said strip such that said tab may be removed to expose a portion of said strip.

2. An insulated electrical conductor comprising a long narrow tape-like base layer of flexible insulating sheet material and an overlying long narrow tape-like cover layer of flexible insulating sheet material, a thin flat conductive strip between the inside surfaces of said layers extending longitudinally the length of said layers, pressure sensitive adhesive peelably adhering said layers together, pressure sensitive adhesive peelably adhering said strip to said cover layer with the adhesion thereto being greater than to the base layer, and at least one pair of rows of perforations extending across said cover layer defining a tab which may be raised to expose the portion of said strip between said rows.

3. An insulated electrical conductor comprising a long narrow tape-like base layer of flexible insulating sheet material and an overlying long narrow tape-like cover layer of flexible insulating sheet material, a strip of metal foil between the inside surfaces of said layers extending longitudinally the length of said layers, pressure sensitive adhesive peelably adhering said layers together, pressure sensitive adhesive peelably adhering said strip to said cover layer with the adhesion thereto being greater than to the base layer, and at least one pair of rows of perforations extending across said cover layer defining a tab which may be raised to expose the portion of said strip between said rows.

4. An insulated electrical conductor comprising a long narrow tape-like base layer of flexible insulating sheet material and an overlying long narrow tape-like cover layer of flexible insulating sheet material, a strip of metal foil between the inside surfaces of said layers extending longitudinally the length of said layers, pressure sensitive adhesive on the inside surface of said cover layer peelably adhering said cover layer to said base layer and to said strip, said strip being substantially less securely bonded to said base layer than to said cover layer, adhesive on the outer side of said base layer, and at least one pair of rows of perforations extending across said cover layer defining a tab which may be raised to expose the portion of said strip between said rows.

5. An insulating electrical conductor comprising a long narrow tape-like base layer of flexible insulating sheet material and an overlying long narrow tape-like cover layer of flexible insulating sheet material, a strip of metal foil between the inside surfaces of said layers extending the length of said layers, pressure sensitive adhesive peelably adhering said layers together, pressure sensitive adhesive peelably adhering said strip to said cover layer in selected regions, said strip being substantially unbonded to said cover layer in other regions and being substantially less securely bonded to said base layer than to said cover layer, and rows of perforations extending across said cover layer defining a tab crossing said strip at said other regions whereby said tab may be raised to expose a portion of said strip.

6. An insulated electrical conductor comprising a long narrow tape-like base layer of flexible insulating sheet material and an overlying long narrow tape-like cover layer of flexible insulating sheet material, at least two parallel strips of metal foil between the inside surfaces of said layers extending the length of said layers, pressure sensitive adhesive peelably adhering said layers together, pressure sensitive adhesive peelably adhering said strips to said cover layer in selected regions, said strips being substantially unbonded to said cover layers in other regions and being substantially less securely bonded to said base layer than to said cover layer, and rows of perforations extending across said cover layer defining a tab crossing said strips at said other regions whereby said tab may be raised to expose a portion of said strips.

7. The conductor defined by claim 6 wherein at least one row of perforations is provided in the cover strip extending longitudinally between the strips of foil.

8. An insulated electrical conductor comprising a long narrow tape-like base layer of flexible insulating sheet material and an overlying long narrow tape-like cover layer of flexible insulating sheet material, at least two parallel strips of metal foil between the inside surfaces of said layers extending longitudinally the length of said layers, pressure sensitive adhesive on the inside surface of said cover layer peelably adhering said cover layer to said base layer and to said strips, said strips being substantially less securely bonded to said base layer than to said cover layer, at least one pair of rows of perforations extending across said cover layer defining a tab which may be raised to expose the portion of said strips between said rows, and a row of perforations extending longitudinally of said cover layer between said strips.

References (lit ed in the file of this patent UNITED STATES PATENTS 2,495,734 Katzman et al Ian. 31, 1950 2,771,385 Hunphner Nov. 20, 1956- 2,804,416 Phillipsen Aug. 27, 1957' FOREIGN PATENTS 198,739 Great Britain June 1,. 1923 403,688 Great Britain Dec. 18,. 1933 850,915 France Sept. 25, 1939 920,487 France Jan. 4, 1947 700,459 Great Britain Dec. 2, 1953 933,943 Germany Oct. 6, 1955

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