Webs and methods of making same

There are disclosed methods of making RFID transponder webs and intermediate webs such as RFID strap webs and antenna webs, as well as such webs per se.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to methods of making webs including antenna webs and RFID transponder webs and to RFID antenna webs.

2. Brief Description of the Prior Art

The following prior art is made of record: U.S. Pat. No. 4,910,499 and published U.S. Patent Application 2004/0215350A1.

In the field of radio frequency identification (RFID) to which this invention relates, an RFID chip is connected to an antenna to form a transponder into which data can be written and from which data can be read. It is known to make labels, tags, business forms, packaging and the like which incorporate such transponders. The chips are very small and require connection to antennas. To facilitate this connection, straps including chips are connected to the antennas. A strap includes an RFID chip and a pair of strap contacts or connecting elements used to connect the chip to an antenna. It is common to provide the straps in a wide web, wherein the straps are arranged close to each other in parallel columns and transversely extending rows. These wide strap webs have some residual adhesive on their electrically conductive side resulting from the manufacturing process and accordingly these wide strap webs are co-wound with an adhesive. The straps have a high density along and across the web. In order to use the narrow webs of straps, the straps must eventually be separated as by cutting them from the narrow strap web prior to connection to antennas. Alternately, an electrically conductive tape can be co-wound with the strap web.

SUMMARY OF THE INVENTION

The invention relates to improved methods of making RFID transponder webs and intermediate webs such as patterned adhesive webs and antenna webs.

The invention relates to the methods of making webs of antennas. One embodiment of the method involves providing a composite antenna web having a first carrier web and a second carrier web between which are transverse rows of first and second antennas, wherein the first antennas are adhesively adhered to the first carrier web and the second antennas are adhesively adhered to the second carrier web, and delaminating the first and second carrier webs from each other to provide first and second antenna webs, and thereafter slitting the first wide antenna web into narrow first antenna webs each having a single column of first antennas and slitting the second wide antenna web into narrow second antenna webs each having a single column of second antennas.

It is preferred to form the antennas by providing a web of a flexible electrically conductive metal, forming slots in the metal web along longitudinally extending columns and lateral rows, and cutting the metal web generally transversely into rows of side-by-side antennas.

According to an improved method of making antenna webs, there is provided a composite antenna web having a first carrier web and a second carrier web between which are transverse rows of alternate first and second antennas, the first antennas being adhesively adhered to the first carrier web and the second antennas being adhesively adhered to the second carrier web, separating the first and second carrier webs from each other to provide first and second antenna webs, and thereafter slitting the first antenna web into narrow first antenna webs each having a single column of antennas and slitting the second antenna web into narrow second antenna webs each having a single column of antennas.

As an intermediate to the making of antenna webs, a longitudinally extending carrier web is provided, and applying a patterned adhesive coating to the carrier web in transversely extending rows or lines corresponding in shape generally similar to rows of first antennas spaced by non-adhesive or non-tacky areas corresponding in shape generally similar to rows of transversely offset second antennas and scrap.

As an intermediate to the making of antenna webs, a longitudinally extending carrier web is provided, and applying a patterned adhesive coating to the carrier web in transversely extending rows or lines in a shape generally similar to rows of second antennas and scrap spaced by non-adhesive or non-tacky areas corresponding in shape generally similar to rows of transversely offset first antennas.

The invention includes a method of making a transponder web which includes providing a web of antennas, passing the antenna web partially around a heated first drum, providing a web of RFID straps, separating the straps one-by-one from the strap web, applying the straps one-by-one to a heated, vacuum, second drum, moving the heated drums to bring the straps and the antenna web together to connect the straps to the antennas to provide a web of RFID transponders.

The invention also relates to an antenna web including a flexible web of electrically conductive metal, slots in the metal web along longitudinally extending columns and lateral rows, and the metal web being cut generally transversely into slotted antennas.

The invention also relates to an antenna web including a flexible, electrically conductive metal web cut into longitudinally extending columns with alternate end-to-end first and second rows of side-by-side first antennas and side-by-side second antennas, a first film adhered to the first antennas of the first rows, and a second film adhesively adhered to the second antennas of the second rows.

The invention also relates to a web including a longitudinally extending carrier web, a patterned adhesive coating on the carrier web having longitudinally spaced adhesive areas with non-linear or cascading or variable transversely extending edges in transversely extending rows longitudinally spaced apart by rows of non-adhesive or non-tacky areas, and wherein the adhesive areas and the non-adhesive or non-tacky areas are similar in shape but are laterally offset with respect to each other.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

With reference toFIG. 1, there is shown a roll R of a web W of radio frequency identification (RFID) transponders T. The web W includes a carrier web CW on which the transponders T are carried. The roll R typically has a core25or a coreless central opening by which the roll R can be mounted for rotation.

With reference toFIG. 2, one RFID transponder T on the left side ofFIG. 2is shown in greater detail. Each transponder T is comprised of an antenna A and a strap S having an RFID chip C. No strap S is shown on the antenna A on the right side ofFIG. 2for clarity. The antennas A are generally bow-tie shaped, but they can have other shapes. The antenna A has a slot26shown to have a generally T-shaped configuration. The top or horizontal part27of the slot26and a stem or vertical part28of the slot26define a pair of contacts or attachment elements29to which a strap S can be attached.

FIG. 3illustrates a wide strap web WSW of RFID straps S on a carrier web31comprised of flexible plastics film. The web31is common to all the straps S. The straps S are arranged in columns C1through CN and rows R1, R2, R3and so forth. Commercially available strap webs WSW as depicted inFIG. 3can be purchased with multiple columns of straps S across the strap web.

FIG. 4shows the construction of one form of strap S. The strap S has a non-electrically conductive plastics film or carrier31with a recess32for receiving an RFID chip C as shown. Covering the film31is a non-electrically conductive plastics film34having a pair of holes35for each strap S. A suitable conductor such as electrically conductive silver printing36is applied over the film34and the silver printing36passes into the holes35in contact with connections on the chip C. Following application of the printing36, the printing36hardens. The printing36is large enough in area so it can easily form contacts or contact elements37. The upper surface of the contacts37as shown inFIG. 4is the electrically conductive side of the strap S and the lower surface31′ of the non-conductive film31is the non-electrically conductive side of the strap S. The straps S have their contacts37facing upwardly as viewed inFIGS. 3 and 4.

It is inconvenient to attempt to apply straps S to antennas A while the straps S are in a wide web having columns of straps S. With reference toFIG. 5, it is preferred to start with a commercially available roll of a wide web of straps having columns and rows of closely spaced straps each with an electrically conductive side as seen at block39. The wide strap web WSW is unwound from a roll and the conductive side of the straps is exposed. Next, the wide strap web WSW is provided with a coating over the transponder straps S with a material which not only has adhesive properties and is therefore referred to as an adhesive40shown inFIGS. 6 and 7, and this adhesive40also contains electrically conductive metal particles41shown by stippling inFIGS. 6 and 7. The adhesive40may or may not be tacky. For clarity, the straps S are shown in solid lines inFIGS. 6 and 7even though the straps S are beneath the adhesive40. Although it is possible to selectively coat only contacts37of the straps S using a patterned adhesive, it is preferred to coat the entire strap web WSW with the conductive particle-containing adhesive40. The adhesive40is preferably an anisotropic adhesive. The coating of the strap web WSW is shown at block42inFIGS. 6 and 7. Next, if the adhesive40is tacky, a release liner43(FIGS. 6 and 7) having a release coating such as silicone is laminated into contact with the adhesive40. The adhesive40is against and between the release-coated side of the liner43and the conductive side of the contacts37to provide a wide composite strap web CSW as depicted in block44. Next, as shown at block45the wide web CSW is slit into narrow composite strap webs NCSW. Thereafter, the narrow composite strap webs NCSW are wound into rolls as indicated at block46for future use in making transponders.

FIG. 6shows the wide strap web WSW as being unwound from a roll47and moved into cooperation with an adhesive coating head48supplied with a heat seal adhesive through a conduit49. The coating head48preferably applies a uniform continuous coating or layer of the conductive particle-containing adhesive40to the surface of the strap web WSW. In that the conductive side of the contacts37face upwardly as viewed inFIG. 6, the adhesive40and the particles41it contains are in direct contact with the contacts37. A roll50of release liner43with its silicone-coated side on the outside of the roll50, is passed partially around a laminating roll52to effect lamination of the coated strap web WSW. The resulting composite strap web CSW passes between rolls52and53. Downstream of the rolls52and53, the composite strap web CSW is slit into a plurality of narrow composite strap webs NCSW having a single column of straps S (or one-up) by knives51, and rewound into rolls54,55and56. Although only three-wide rows of transponder straps S are illustrated, strap webs having any desired number of straps per row can be provided, coated, slit and rewound.

FIG. 7shows a narrow composite strap web NCSW with its liner43broken away to show the straps S coated with the adhesive40containing conductive particles41.

With reference toFIG. 8, there is illustrated a method of making antenna webs. The starting material is a roll57of a flexible electrically conductive metal web58which is unwound and passed to between a punch roll59and a die roll60. The web58is preferably comprised of aluminum. The punch roll59and die roll60cooperate to punch out slots AT from the metal web58in a pattern best shown inFIGS. 9,11and12. The roll60can be a vacuum roll by which metal chads (not shown) resulting from the punch out operation can be removed. Simultaneously with movement of the web58to the punch roll59and the cooperating die roll60, a web61of a flexible transparent plastic material is paid out of a roll62and passed between a patterned roll63and a back-up roll64. The web58is referred to for convenience as a “first web”. The pattered roll63coats or prints a pattern of an ultraviolet (UV) curable adhesive A′ (FIG. 11) onto the upper surface of the web61according to a pattern illustrated in greater detail inFIG. 10. The conductive web58which has been slotted and the web61are laminated together as they pass between rolls65and66. Thus, the lamination occurs downstream of the place the slots AT are made in the web58. The combined webs58and61are shown in greater detail inFIG. 11. From there, these combined webs58and61pass over an ultraviolet (UV) light source67which cures the UV-curable adhesive A′ on the web61applied by the roll63. Once cured, the adhesive A′ is dry and non-tacky. Next the combined webs with the cured adhesive A′ holding them together pass between a cutter roll68having cutting blades69and a plain back-up roll70. The cutter blades69cut the web58transversely along cascading non-linear lines or cuts71as best shown inFIG. 12without cutting into the web61. It is readily apparent that the slots AT and the cuts71together separate the web58into rows of side-by-side and end-to-end antennas A. As the combined webs58and61travel, a film or web72of flexible transparent plastics material is unwound from a supply roll72′ and is passed between a pair of rolls73and74. The roll73is a patterned roll that coats or prints adhesive A′ in a pattern best shown inFIG. 13to the upper side of the web72. The web72is then passed partially around a roll75and from there partially around a roll76. Combined webs58,61and72referred to as AW pass between the roll76and a back up roll77and from there they pass beneath an ultraviolet (UV) light source67′. The webs61and72being transparent or sufficiently so that the UV light can readily cure the adhesive A′. To reiterate, the electrically conductive material web is cut generally transversely non-rectilinearly at longitudinally spaced apart intervals, such that each slot intersects with only two cut lines, to provide completed identical antennas in alternating first and second rows.

FIG. 14is a side view of the sandwich or composite web AW comprised of the patterned adhesive-coated webs61and72and the intervening slotted and cut conductive metal web58.

From there, the combined webs58,61and72pass beneath an ultraviolet light source78which cures the adhesive A′ on the web72. From there, the combined webs58,61and72pass between a pair of rolls79and80, and from there the webs61and72pass in the directions of arrows89and90and are wound into rolls91and92.

With reference toFIG. 9, the left-hand portion83of the conductive web58shows the unslotted web as it comes off the roll57. When the web58passes between the punch roll59and the die roll60the slots AT are formed in the web58. The slots AT extend in laterally spaced columns in patterns that alternate from column-to-column. The slots AT of the outer columns and the slots AT of every other column between the outer columns extend in the same direction. Intervening or alternate columns of slots AT extend in the opposite direction. The metal chads (not shown) removed by the punch roll59and the die roll60are T-shaped and, therefore, all of the conductive material within the periphery of each slot AT is removed. Each slot AT is comprised of the horizontal cut out27(FIG. 2) and a long vertical cut out84. Together the slot portions27and84form the slots AT depicted inFIG. 9.

FIG. 10depicts the pattered adhesive A′ applied by the roll63(FIG. 8) to the first web61. The two rows of zones or areas85of adhesive A′ are shown to be identical in shape. The non-adhesive or non-tacky zones or areas86between the adhesive areas85are similar but not identical in size and shape to the areas85as will be seen and described with reference toFIG. 12. The areas86are laterally offset from the areas85as is also seen inFIGS. 11 and 12.

FIG. 11shows the relationship of the slots AT through the conductive web58to the adhesive A′ on the web61. The left side ofFIG. 11shows the adhesive A′ by broken lines because the adhesive on that side ofFIG. 11is beneath the conductive web58.

FIG. 12shows that the adhesive A′ has non-linear edges85′ spaced inwardly from the non-linear lateral edges71of the antennas A, as is preferred. It is to be noted that the slots AT and the cuts71define antennas A and waste or scrap SC. In the illustrated composite antenna web ofFIG. 12, first rows 1st have three antennas A and second rows 2nd have two antennas A and scrap SC. Even though the wide web shown inFIG. 12is only three antennas wide in rows 1st, the scrap amounts to only a small portion of the overall web, the greater the number of antennas across the web the less the percentage of scrap SC to the overall amount of metal material in the web58. It is noted that the number of antennas A in the first rows 1st is greater than the number of antennas A in the second rows 2nd. Generally, the numbers of first antennas A will exceed the number of second antennas A by one, thus first row 1st is shown to have three antennas A and second row 2nd is shown to have two antennas A.

FIG. 13shows the pattern of adhesive A′ in the web72for registration with the second antennas A of the conductive web58. Adhesive zones87(FIG. 13) are identical to adhesive zones85(FIG. 11), and non-adhesive or non-tacky zones88(FIG. 13) are identical to non-adhesive or non-tacky zones86(FIG. 11).

With reference toFIGS. 10,11and13, it is apparent that the areas85and87of adhesive A′ have the same size and shape. The areas85and87are continuous as is preferred, yet they are referred to as “rows”. There are shown three antennas A over each area85. Similarly, there are shown two antennas A and two pieces of scrap SC under each area87. So even though the areas85and87are considered rows, each row85corresponds to three antennas A, and each row87corresponds to two antennas A and two pieces of scrap SC. Each adhesive area85is considered to include adhesive area sections85(1),85(2) and85(3), shown to be identical to each other, and each area section85(1),85(2) and85(3) corresponds to and underlies an antenna A and adhesively secures the web61to one of the antennas A in row 1st. Each adhesive area87includes adhesive sections87(1),87(2) and87(3) shown to be identical to each other and identical in size and shape to adhesive sections85(1),85(2) and85(3). However, the sections85(1),85(2) and85(3) are in row 1st, and the sections87(1),87(2) and87(3) are in row 2nd. The rows 2ndof adhesive A′ can also be considered to have adhesive sections87(A) which have generally the shape as the antennas A and areas87(SC) which have generally the shape as the scrap SC. The adhesive sections87(A) adhesively secure the antennas A in row 2ndto the web72and the adhesive sections87(SC) adhesively secure the scrap SC in row 2ndto the web72. Thus, although the adhesive areas85and87have the same appearance, the adhesive sections87(1),87(2) and87(3) on the web61are laterally offset or staggered with respect to adhesive sections87(A). By having the antennas A in row 1stoffset or staggered from the antennas A in row 2ndthere is no waste of the metal web58between antennas A in the end-to-end antennas of rows 1stand 2nd, except for waste SC that occurs only at the marginal sides of the web AW at every other antenna row.

With reference toFIGS. 8 and 15, the first antenna web AW1to which the first antennas A are adhesively adhered passes in the direction of arrow89following separation and the second antenna web AW2to which second antennas A are adhesively adhered passes in the direction of arrow90following separation. From there the first web AW1is rewound into a roll91and the second antenna web AW2is rewound into a roll92.

As shown inFIG. 16, the first wide antenna web roll AW1is next slit into three narrow antenna webs61′ using slitter blades93from which the one-up or single antenna column wide, narrow antenna webs61′ can be wound into narrow rolls94,95and96. The side edges of the web61can have excess material which can be trimmed, if desired.

With reference toFIG. 17, the second wide antenna web roll AW2is slit by knife97into narrow antenna webs99and100and trimmed by knives98to remove waste or scrap SC, and thereafter wound into narrow antenna web rolls101and102.

FIG. 18is a simplified flow chart depicting a method according to the invention of making transponder webs. In block103, a flexible, conductive metal web is provided as a starting material. Next as shown in block104, antennas are partially formed by partially cutting the metal web at first and second rows. Also, a wide first plastic film web is provided as another starting material as indicated at block105. At the same time as the antennas A are partially formed at block104, an adhesive pattern of adhesive areas85in first rows 1st is printed or coated onto the first plastic web61for registration with the first antenna rows 1st as indicated at block106. Next, as depicted at block107, the metal web58with first partially cut antenna rows registered with first rows 1stof adhesive A′ on the first plastic web61and the web61are laminated to each other. The preferably UV curable adhesive A′ is then cured as depicted at block108. Thereafter, the metal web58is cut into first and second rows of antennas A as depicted at block109. While the webs58and61are moving or traveling, a wide roll of a second plastic film72provided at block110is printed with an adhesive pattern of rows87of adhesive A′ for registration with second antenna rows 2ndas indicated at block111. Next, the metal web58and the second plastic web72are laminated on the side of the metal web58opposite the first plastic web61to provide a composite antenna web AW per block112. Thereafter, the UV curable adhesive A′ on the web72is cured as indicated at block113. Next the first and second plastics webs58and72are separated to provide a first wide antenna web AW1with first antenna rows 1st and a second wide antenna web AW2with second antenna rows 2nd as per block114. Next the first antenna web AW1is wound into a wide roll as depicted at block115and the second antenna web AW2is wound with a wide roll as depicted at block116. Next, the first antenna web AW1is slit into narrow antenna webs61′ one antenna wide or one-up and rewound into rolls94,95and96as shown at block117, and the second antenna web AW2is slit into narrow antenna webs99and100one antenna wide or one-up and rewound into rolls101and102as shown at block118. Because the antenna web AW2contains the scrap SC, it is preferred to trim the web AW2of the scrap SC using outboard knives98as shown inFIG. 17. If desired, after block114, the first antenna web AW1and the second antenna web AW2can be slit and rewound without the steps indicated at blocks115and116.

With reference toFIG. 19, the one-up linered strap web NCSW in a roll R′ is paid out and travels over a defective strap detector119which attempts to read and/or write to the chip C in each strap S. The strap web NCSW is advanced by feed roller120and121, one of which is motor-driven, and the strap web NCSW passes to a cutter and applicator assembly122shown in greater detail inFIG. 20. The assembly122includes a block123with a knife or cutter element124and an applicator125in the form of a resilient elastomeric pad125′. The block123is suitably actuated as by a piston/cylinder device, a solenoid, or the like indicated at126inFIG. 19. The knife or cutter124cooperates with an inclined edge127of a knife or cutter blade128so that the strap web NCSW is progressively cut laterally as the knives124and128cooperate. The separated leading strap S is either applied to a heated vacuum drum129by the descending action of the applicator125, or in the case of a defective strap S, the defective strap S is removed by vacuum through a duct130.

The drum129can be considered to be a transfer drum because it transfers a separated strap S to the antenna web AW1and applies a strap S to an antenna A. The illustrated first antenna web AW1is paid out of the roll94for example and passes partially around a roll131and partially around a heated drum132which can be a vacuum drum. The drums129and132rotate at the same peripheral speed and the straps S are applied precisely to the contacts29(FIG. 2) to form the transponders T. It is noted that the conductive particle-containing adhesive40(FIG. 7) heated by the heated drum129is activated. In addition, the heated drum132heats the antennas A. When a strap S and an antenna A are between and in pressure contact with the drums129and132the contacts37on the straps are electrically connected to the contacts29on the antenna, and the conductive particles41help make good contact. The transponder web W thus formed passes to a cooling surface of a cooling drum133and from there is rewound into a roll R. It is preferred that while the web W is wound into the roll R, a liner134is co-wound so that each wrap of the web W is separated from the adjacent wrap by liner material. The web W can be wound transponder-side-in as shown inFIG. 19or transponder-side-out as shown inFIG. 1, as desired.

With reference toFIG. 21, there is shown, a simplified flow chart of the method of making a web of transponders depicted inFIGS. 19 and 20. At block135a one-up strap web NCSW is passed to an inspection station119and at block136the leading straps S are separated on-by-one from the strap web NCSW. Defective straps S are removed as they are separated by the knives124and128through a duct130by the assistance of vacuum as indicated at block137. The remaining straps S are progressively applied to the first heated transfer drum129to which they are held as the drum129rotates (counterclockwise inFIG. 19) until the leading strap S on the drum129is in a position opposed to the drum132at which time the vacuum to that strap S is interrupted, as summarized at block138. While the transfer drum129is rotating, antenna web AW1is passed partly around the heated drum132as indicated at block139. The drum129moves to apply straps S to the antennas on the second drum to form a transponder web W as shown at block140. Next the web W preferably passes partly around a cooling drum to cool the transponder web W as shown at block141. It is preferred to optionally apply a liner134along the entire surface of the transponder web W as indicated at block142and to wind the linered transponder web W into a roll R as indicated at block143.

It should be noted inFIG. 15in particular that the slots26in the antennas A of web AW1extend in the opposite direction from the slots26in the antennas A of web AW2, although the antennas A per se of each web AW1and AW2are identical. Accordingly, in the event it is desired to use the antenna web AW2in the arrangement ofFIG. 19, the registration of the straps S and the antenna web AW2should be adjusted so that the contacts37on the straps S meet the contacts29on the antennas A. Alternatively, the antenna web AW2needs to be rewound again before loading it into the position occupied by the roll94inFIG. 19so that the web AW2can be used the same way the web AW1is used inFIG. 19.

In the embodiment ofFIG. 22the same reference characters are used to designate identical components having the same construction and function. The differences in the embodiment ofFIG. 22over the embodiment ofFIGS. 19 and 20are as follows in this paragraph: Referring toFIG. 22, roll R″ is comprised of a narrow strap web USW which may have been slit from a wide strap web as shown ifFIG. 3. The web USW does not have any adhesive coating like the coating of adhesive40shown inFIGS. 6 and 7. The strap web USW is feed to the defective strap detector station119to the cutting station where the straps S are separated on-by-one from the strap web USW. Defective straps S are removed through the duct130and acceptable straps S are transferred to the drum129. The web AW1is paid out of roll94for example passed partially around the roll131and partially around the heated drum132. An adhesive applicator head144supplied with adhesive through a conduit145applies an electrically conductive particle-containing, heat softenable and heat curable adhesive146to the contacts29on the antennas A. When the straps S adhered by vacuum to the transfer drum129are applied in registration to the antennas A, the contacts37on the straps are electrically connected to the contacts29on the antennas A, thereby forming transponders T. The heat from the drum132softens and cures the adhesive146. After the straps S have been connected to the web AW1, the web AW1becomes a transponder web W which is then passed partially about the cooling surface of the cooling drum133. The web W is then passed beneath a printing transponder detector146which reads and/or writes to each transponder T and prints a mark on or near a defective transponder T. From there, the web W is wound into a roll R.

FIG. 23is a simplified flow chart illustrating mainly the differences in the embodiment ofFIG. 22over the embodiment ofFIGS. 19 through 21. As in the embodiment ofFIGS. 19 through 21,FIG. 23shows that antenna web AW1is passed partly around heated drum129at block148and an uncoated one-up strap web USW is passed to a defective strap detection station at block149. Adhesive146is applied to the antennas A for connection to the straps S as indicated at block150. After the good and the bad or defective straps S are separated from the strap web USW and applied to the heated transfer drum129as indicated at block151, the straps S are connected to the antennas A using heat and pressure applied to the conductive adhesive146as indicated at block152. The antennas A and straps S continue to be heated so long as the web W is in contact with the drum132. From there the web W is passed to a cooling drum133. From there, all the transponders are tested by writing to and/or reading from each transponder T at a defective transponder detection station147as the web W moves, and a mark is printed on the transponder web W at or near the defective transponders T. Next the transponder web W is wound into a roll R.

It is apparent that when registering the various webs58,61,72, NCSW, USW, AW1and AW2registration marks can be provided on these webs.

It is apparent that instead of using antenna webs AW1and AW2in the methods depicted inFIGS. 19 through 23, the antenna webs can instead be made by other and different methods utilizing printing, etching, deposition, and so on.

By example, not limitation, the wide strap webs WSW are available from Alien Technology Corporation, Morgan Hill, Calif. under Model No. ALC-140-AS, and the overall dimensions of each strap Sx is 3.5 mm by 7 mm by 0.2 mm thick. The plastics film webs61and72of plastics material are available from Multi-Plastics Corporation, Mount Pleasant, S.C., and are transparent and known in the trade as Mylar preferably of the heat stabilized version known as Type LCF-4000. This plastics film is comprised of clear polyester and has a thickness of 0.05 mm. The conductive metal web58is comprised of aluminum having a thickness of 0.012 mm and is 457 mm wide. The adhesive40is a product of Forbo Adhesives Corporation, Durham, N.C., a subsidiary of Forbo International S.A, Zurich Switzerland, type Swift heat seal adhesive #82681 mixed with about five percent by weight of Ames Goldsmith Corporation, Glens Falls, N.Y., type LCP15 0.015 mm diameter silver particles. The ultraviolet curable adhesive A′ is a product of RAD-CURE Corp., Fairfield, N.J., known under the designation TYPE X 4002138B. The conductive adhesive146is a product of Emerson & Cuming Corp., Billericz, Mass., a National Starch & Chemical Company, Bridgewater, N.J., and is sold under the formula XCA-90216.

Other embodiments and modifications of the invention will suggest themselves to those skilled in the art, and all such of these as come within the spirit of this invention are included within its scope as best defined by the appended claims.