WO2005009092A1 - Flexible strip conductor structure and method for producing and using the same - Google Patents

Abstract

The invention relates to a flexible strip conductor structure consisting of an electrically non-conductive, essentially flat substrate comprising a partially electroconductive coating (1,5). The aim of the invention is to improve the flexibility, robustness and producibility of said structure. To this end, the substrate is a textile-type fabric (G) which is three-dimensionally assembled from electrically non-conductive threads (4) in such a way that it has a larger thickness than that of the thread, and the partially electroconductive coating (5) adheres to the threads and penetrates the fabric (G) at least in sections up to at least part (2) of the thickness of the fabric. The inventive structure is produced by partial activation by means of precious metal germination and electroconductive coating of the activated regions, an activator paste having a defined viscosity being provided and penetrating the fabric to a certain coating depth by means of air pressure.

Description

 Flexible interconnect structure and method of making and using the same

The invention relates to a flexible conductor track structure, consisting of an electrically non-conductive, essentially flat substrate with partial electrically conductive coating, and also to a method for producing such a structure, wherein an electrically non-conductive, essentially flat substrate is partially coated with noble metal. Germination activated and then the areas activated in this way are coated in an electrically conductive manner, and advantageous uses of such structures. Structures of the type mentioned and also their production in the manner described are known for example from EP 256 395 A or also DE 196 24 071 A and are used, for example, for the production of printed circuits, membrane keyboards, switch mats and the like. Like. Used, wherein the conductor tracks subsequently generated by electrically conductive coating are defined by the partial activation in the form of patterns. The substrates used mostly consist of flexible plastic films (for example made of PES or the like), papers, or even dense tiles, which are provided with two-dimensionally “printed” conductor tracks by the surface activation and subsequent electrically conductive coating. The flexibility of such substrates, which in any case can only be used to a limited extent without the risk of permanent damage, is further limited by the additional risk of damage or detachment of these printed conductor tracks, so that in practice an initial warping when attaching such a structure or occasional rolling up (e.g. a membrane keyboard) is permitted. Furthermore, especially in connection with electronic devices (wearable computers) that can be worn on the body, textiles with woven-in, electrically conductive wires or threads have become known, via which electrically conductive connections between energy sources, input aids, processing units, output and display devices and the like be made in the fabrics or clothing can, with which the previously customary or necessary separate cabling can be omitted. Such fabrics, however, are only correspondingly expensive and difficult to manufacture with very thin and therefore non-disturbing wires - the use of thicker wires naturally goes at the expense of flexibility and thus handling. The electrically conductive wires, which are relatively inflexible compared to the other tissue environment, must also be carefully insulated so that, for example, a crumpling of the garment during wear cannot lead to short circuits. The object of the present invention is to improve a flexible interconnect structure of the type mentioned at the outset in such a way that the disadvantages mentioned of the known structures of this type are avoided and that in particular the manufacture can be simplified and highly flexible but nevertheless robust interconnect structures can be provided. The above-mentioned object is achieved in a conductor track structure of the type mentioned at the outset in that the substrate consists of a three-dimensional textile-like fabric made of electrically non-conductive threads with a greater thickness than the thread thickness, and in that the partially electrically conductive coating adheres to the threads and that Tissue penetrates at least in regions up to at least part of the thickness. This creates a flexible structure made of a textile-like fabric with a partially electrically conductive coating (based on the fabric surface), this coating (based on the individual threads in the coated area) surrounding the threads as thinly as possible. As a result of the individual threads in such a fabric that are actually only touching in certain areas, the flexibility of the fabric is largely retained even in the coated areas, the actually available wire cross-section being simply varied over the width and depth of the respective coating web, which in the In contrast, for example, to the above-mentioned co-woven threads, large line cross sections and thus large currents are also possible. In the simplest embodiment of the invention, the substrate is only partially electrically conductively coated, and its thickness (relative to the fabric thickness) can be varied via the manner of producing or applying this coating, which is described in more detail below. Depending on the requirements or application, the electrically conductive coating can only reach a few thread thicknesses deep into the fabric or penetrate it entirely. In a further preferred embodiment of the invention, however, the partial electrically conductive coating is applied to both sides of the fabric, preferably in a different structure, and preferably through-plated through in certain areas. In this way, conductor tracks (possibly also different) can be formed on both sides of the fabric, which are only contacted by the fabric at desired locations. This contact can be made either by means of correspondingly thick coating webs on both sides, which are touching the inside of the fabric, or - in a further preferred embodiment of the invention - can be implemented in such a way that the coatings on both sides of the fabric are spaced apart on the inside and for through-contacting in areas separate contact elements penetrating the tissue, such as electrically conductive eyelets, seams, push buttons or the like, are provided. Overall, both enable the construction of relatively complicated conductor track structures without significantly impairing flexibility. In a preferred further embodiment of the invention, the textile-like fabric used for the substrate can consist of threads of a polymer from the following group: polyester, polyamide, polyvinyl derivatives, polyurethane, polypropylene and acrylonitrile-butadiene-styrene copolymer (ABS) or natural fibers or a mixed fabric, wherein the thread thickness is preferably in the range from 20 to 80 μm. In an advantageous embodiment of the invention, the electrically conductive coating in the area of the provided conductor tracks consists of a metal from the group: Cu, Ni, Ag, Au, or their alloys or layer combinations. NEN, the layer thickness is preferably in the range of 0.01 to 10 microns. Such conductor track structures are highly flexible and yet robust and are ideally suited for a wide variety of uses - according to the invention, preferably as a current conducting structure between at least one power source and a consumer in or on clothing or textile surfaces in the home, in advertising or in decoration. For example, so-called “smart fabrics” for supplying energy or operating electronic devices installed in clothing items can be realized, or textiles that can be used as curtains or fabrics with light displays realized by LEDs or the like, for example. In a method of the type mentioned at the outset for producing structures of this type, in order to achieve the above-mentioned object according to the invention it is provided that a fabric made of electrically non-conductive threads three-dimensionally with a greater thickness than the thread thickness is used as the substrate, the fabric after preferably chemical roughening The surface of the thread is selectively provided on one side with an activator paste with a defined viscosity, the activator paste is pressed into the tissue with the aid of air pressure to the intended coating depth, the partially three-dimensionally activated tissue is dried, and the partially three-dimensionally activated and dried tissue is electrically conductively coated in the activated area. A polymer from the group consisting of: polyester, polyamide, polyvinyl derivatives, polyurethanes, polypropylene and acrylonitrile-butadiene-styrene copolymer (ABS) or natural fibers or a mixed fabric, with a thread thickness preferably in the range from 20 to 80 μm, is preferably used as the fabric material , In a preferred embodiment of the invention, the activator paste contains organometallic compounds of elements of the 1st or 8th subgroup of the periodic table and of olefins, α, β-unsaturated carbonyl compounds, crown ethers or nitriles, dissolved or finely dispersed, embedded in a matrix made of paint-typical binders and solvents, and is preferably applied in a layer thickness in the range from 10 to 50 μm, particularly preferably 20 to 30 μm. Further features of the structure according to the invention and of the production method according to the invention can be found in the patent claims and the following description of the production method and individual exemplary embodiments. 1, 2 and 3 show examples of the conductor track structure according to the invention in a schematic cross section, and FIGS. 4 and 5 are top views of conductor track structures designed according to the invention on flat substrates. Fig. 6 is a schematic section along the line VI-VI in Fig. 5. It is known that the metal deposition on non-conductive surfaces, in particular surfaces of plastics, from chemically reductive metallizing baths by ionic or on the surfaces to be coated in previous process steps colloidally fixed noble metal nuclei can be catalyzed. In order to produce an adherent coating, these surfaces generally have to be roughened beforehand. This can be done mechanically or chemically, for example in the case of acrylonitrile-butadiene-styrene copolymers (ABS) by pickling in chromosulfuric acid. For the selective coating of plastic carriers for the purpose of producing circuit carriers and flexible printed circuit boards, a printing paste formulation is proposed, for example, in EP 0 256 395 which uses organometallic compounds of the 1st or 8th subgroup of the periodic table and of olefins, α, β-unsaturated carbonyl compounds as activators , Crown ethers or nitriles. These activators or metallization catalysts are dissolved or finely dispersed embedded in a matrix of paint-typical binders and suitable solvents. Surprisingly, it has now been found that such formulations, after modification of their viscosities to defined values in combination with special application techniques, weave very well in three dimensions for surface and depth selective activation Textile surfaces are suitable and these fabrics, pretreated in this way, can be three-dimensionally metallized after a thermal conditioning step in chemical-reductive metallizing baths. The special design technique of selective coating in screen printing consists in that the fabrics to be coated are partially printed in conventional screen printing machines, which are equipped with a vacuum printing table, the suction effect of which can be regulated. The printing table on which the tissues to be printed are placed advantageously also has a porous open-cell suction plate. The amount of activator deposited in the screen printing process on the fabric surface can be controlled by a suitable choice of the emulsion layer thickness of the printing screen, the mesh size of the screen fabric used and the viscosity of the activation solution. Immediately after the printing process, the activator solution is sucked into the tissue depth by applying negative pressure to the printing table. The spatial penetration depth and therefore the wetting of the fibers inside the fabric is dependent on the viscosity of the activator solution and on the level of the negative pressure applied. The penetration depth of the activator solution can be influenced within a wide range (from the surface wetting to the complete soaking of the tissue within the printed areas) by the following key data:

Mesh size: 80 - 27 μm, preferably 44 - 56 μm

Emulsion layer thickness: 10 - 50 μm, preferably 20 - 30 μm

Viscosity of the activator solution: depending on the application process, in screen printing in the range of 1000 - 8000 mPas, preferably 2000 - 6000 mPas In the ink jet process: 100 - 1000 mPas, preferably 150 - 500 mPas

Negative pressure: 720 - 1000 mbar, preferably 700 - 500 mbar In addition, the depth of penetration is still dependent on the fabric thickness (thick fabrics can no longer be completely soaked with the activator pressure from only one side, but are then suitable for circuit printing on both sides).

Working Example:

An activation solution consisting of 44.3 g of a commercially available aliphatic isocyanate (Desmodur N 100), 0.80 g of 4-cyclohexene-1, 2-dicarboxylic acid palladium (II) chloride, 250 ml of methoxypropyl acetate and 100 ml of butyl glycolate is dispersed through The addition of highly disperse silica adjusted to a viscosity of 2500 mPas at 23 ° C. The activator paste thus produced is printed on a polyester-containing three-dimensionally woven fabric with a thickness of approx. 0.9 mm using a sieve structured using conventional manufacturing techniques with a mesh size of 56 μm and an emulsion thickness in the closed (i.e. non-printable areas) of 20 μm , immediately afterwards the vacuum pressure table provided with a microporous table support is subjected to a negative pressure of 520 mbar for 4 seconds. After air-drying the partially activated tissue and subsequent thermal storage for 1 hour at 130 ° C, the metallization is carried out in a commercially available chemical-reductive copper bath. Copper baths which work with formalin as reducing agent have preferably proven successful. After a dwell time of 30 - 40 minutes, the individual fibers of the areas previously printed with the activation solution are covered on all sides with a closed copper layer with a layer thickness of approx. 2 μm (half the depth of the fabric). The back, i.e. the inactive side, of the fabric remains uncoated and therefore has an insulating effect. The starting material is a single (uniform pattern) or multiple (several patterns with different densities in one textile) structured textile (woven, knitted, crocheted, lace or the like), the 3-D is selectively provided with noble metal germination, the germinated areas then being coated with metal. The coating can be carried out according to different methods, which differ in whether the textile is structured in a single or multiple way. In the case of simply structured textiles, the selectivity is achieved through the type of coating process. In the case of textiles with multiple structures, the selectivity is achieved by the different patterns (density of the textile fibers). The coating process always consists of 2 sub-processes, the activation step, in which the textile is selectively germinated, and the metallization step, in which the metallization takes place.

The activation step can be carried out using the following methods: a) screen printing, b) spraying process with suction device, c) micro-spraying process (ink-jet), or d) offset printing (gravure printing process)

The metallization step is preferably always carried out using the electroless metallization method. The 3-D selective metallization of simply structured textiles is achieved when the activation is carried out in the a) screen printing process with various masks (screens) in which the penetration depth of the activator is varied by varying the suction rate and / or changing the viscosity of the liquid activator he follows. b) spraying process with suction device with different masks is carried out, in which the penetration depth of the activator is carried out by varying the suction rate and / or changing the viscosity of the liquid activator c) microspray process (ink-jet) process as b) d) open pressure with different Masks are carried out, in which the penetration depth of the activator takes place by varying the suction rate and / or changing the viscosity of the liquid activator.

The 3-D selective metallization of multi-structured textiles is achieved on the one hand by the design of the textile (dense and less dense areas, see FIGS. 2 and 3), which is activated. The activation is carried out in a) screen printing in a step in which the penetration depth of the activator is determined by setting the suction rate and / or its viscosity. b) Spraying process carried out with a suction device with a mask, the depth of penetration of the activator being determined by varying the suction rate and / or by changing its viscosity. c) micro-spray process (ink-jet) process as b) d) offset printing carried out with a mask, the depth of penetration of the activator being determined by varying the suction rate and / or changing its viscosity.

In principle, the tissue can be activated on one (eg 1 circuit) or on both sides (eg 2 circuits). When activating on one side, full penetration of the textile or partial penetration and isolating areas from metallized areas are obtained on opposite sides. When activated on both sides, full penetration is obtained on opposite sides or, with less penetration, an electrically insulating core inside the textile. The manufacturing process consists of repeating the one-sided activation (see above) on the opposite side of the textile. The conductor tracks on the opposite sides can be electrically connected to one another by conductive sewing, eyelets, crimping, piercing or the like. The flexibility of the fabric is retained even after coating. The thickness of the coating is only set in the metallization process. The textile, selectively metallized in this way, is used, for example, as a power supply for the mains-independent supply of various small consumers (sensors, switches, transistors, diodes, resistors, capacitors, displays, LEDs, in various small portable devices) with battery power. The current carrying capacity of the individual conductor tracks is designed as required. Depending on the conductor layout and heat dissipation, it can also be up to 100 amperes or more. 1 shows the conductor track structure according to the invention in a schematic cross section of a detail area of the fabric (G) which has already been partially electrically conductively coated. The self-electrically non-conductive flexible threads 4 are individually provided with a thin layer 5 of a conductive metal, such as copper, in the area of the partial electrically conductive coating 1 forming a conductor track, this coating 1 up to the thickness 2 of the fabric (G) is enough and thus an insulating layer 3 remains on the back. In FIGS. 2 and 3, regions a, b, c and d are used to denote regions of different weave densities in the fabric (G) each shown in a schematic partial section. From Fig. 2 it can be seen that the treatment with the activator (as described above) can lead to a selective coating with different penetration depths; Depending on the viscosity and the duration of exposure, complete penetration can already be achieved in the less dense areas. The one-sided treatment with the activator results in an asymmetrical pattern (in cross-section). According to FIG. 3, treatment with the activator on both sides results in a symmetrical pattern of the coating (in cross section) - opposite coated areas can still be conductively connected at individual points in a manner not shown here by means of a push button or the like. Apart from the symmetrical treatment of both surface sides of the fabric (G) shown here, a different pattern could of course also be applied to both sides. 4 shows, as an example of the use of a flexible conductor structure according to the invention, the inner part of a so-called "helmet apron", for example of a fire helmet. It is a multi-layer flexible part that can be fastened to attachment points 6 at the rear at the bottom of a helmet, which does not further illustrate, which protects the neck and neck area of the helmet wearer from heat and also prevents ashes and embers or extinguishing water from penetrating into this area , Using a flexible conductor structure according to the invention as the middle part of a, for example, three-layer textile part (outside, for example, heat-repellent, waterproof, completely or partially reflective, or similarly constructed and inside, for example, heat-insulating, skin-friendly, sweat-absorbent or the like), this helmet apron can now additionally function as an energy supply or signal connection or electrical control of various electrical devices arranged on the helmet or in the neck or shoulder area shear or electronic devices such as flashlights, radios, microphones, headphones, night vision devices, signal switches, dialing keyboards and the like, also with different requirements for supply voltage or current to be provided. A corresponding single or multi-part battery with multiple taps can be carried on the back, for example, and connected in the illustrated example with five push buttons at positions 7 (+) and 8 (-). At positions 9 to 12, the various devices with two different voltages (9 and 12, for example 6 volts and 10 and 11, for example 12 volts) can also be connected, for example, via push buttons. The conductor tracks 13 are formed according to the examples discussed in FIGS. 1 to 3 in the fabric and do not or hardly hinder its flexibility. 5 and 6 is a multi-layer flexible fabric structure for use, for example, as a so-called "star curtain" in the decoration. Between each of the conductor tracks 13, which are again designed, as discussed in accordance with FIGS. 1 to 3, and produced by electrically conductive coating 1, LEDs 14 are arranged here, which are connected to the conductor tracks 13 in an electrically conductive manner using conventional connection techniques, for example by means of clamping connections, Gluing, partial soldering or the like. The darker outer conductor tracks are thicker as current busbars and are completely penetrating the substrate and, in the illustration according to FIG. 5, lead to connections 15, 16 to the outside. The only hatched conductor tracks 13 between them do not penetrate completely through the substrate according to FIG. 6, so that the rear side remains insulating. Also in the example according to FIGS. 5 and 6, the conductor track structure according to the invention is usually sandwiched between outer cover layers, so that the conductor tracks themselves are protected inside.

Claims

claims: 1. Flexible conductor track structure, consisting of an electrically non-conductive, substantially flat substrate with partial electrically conductive coating (1,5), characterized in that the substrate consists of an electrically non-conductive thread (4) three-dimensionally with larger than the thread thickness There is a thick textile-like fabric (G), and the partial electrically conductive coating (1,5) adheres to the threads (4) and the fabric (G) penetrates at least in regions up to at least a part (2) of the thickness. 2. Conductor structure according to claim 1, characterized in that the partial electrically conductive coating (1,5) on both sides of the fabric (G), preferably in a different structure, is applied and preferably plated through in areas. 3. trace structure according to claim 2, characterized in that the coatings (1) on both sides of the fabric (G) continuously spaced inside and for the region-specific through-contacting separate, fabric penetrating contact elements such as eyelets, seams, push buttons or the like. , are provided. 4. conductor structure according to one of claims 1 to 3, characterized in that the fabric (G) consists of threads (4) of a polymer of the following group: polyester, polyamide, polyvinyl derivatives, polyurethane, polypropylene and acrylonitrile-butadiene-styrene copolymer (ABS) or natural fibers or a mixed fabric, the thread thickness preferably being in the range from 20 to 80 μm. 5. trace structure according to one or more of claims 1 to 4, characterized in that the partial electrically conductive coating (1,5) from a measurement tall of the group: Cu, Ni, Ag, Au or their alloys or layer combinations and preferably has a layer thickness in the range of 0.01 to 10 microns. 6. Method for producing a flexible conductor track structure, wherein an electrically non-conductive, essentially flat substrate is partially activated by means of noble metal nucleation and then the regions activated in this way are coated in an electrically conductive manner, so that a fabric (G) made up of three dimensions with electrically non-conductive threads (4) and having a greater thickness than the thread thickness is used as the substrate, - After preferably chemical roughening of the thread surfaces, the fabric (G) is selectively provided on one surface with an activator paste with a defined viscosity, - the activator paste is pressed into the tissue with the aid of air pressure to the intended coating depth, - The partially three-dimensionally activated tissue (G) is dried, and - The partially three-dimensionally activated and dried fabric (G) is coated in an electrically conductive manner in the activated areas. 7. The method according to claim 6, characterized in that the fabric material is a polymer from the group: polyester, polyamide, polyvinyl derivatives, polyurethanes, polypropylene and acrylonitrile-butadiene-styrene copolymer (ABS) or natural fibers or a Mixed fabric, with a thread size preferably in the range of 20 to 80 microns, is used. 8. The method according to claim 6 or 7, characterized in that the activator paste organometallic compounds of elements of the 1st or 8th subgroup of the periodic table and of olefins, α, β-unsaturated carbonyl compounds, crown ethers or nitriles, dissolved or finely dispersed embedded in a Contains matrix of lacquer-type binders and solvents, and is preferably applied in a layer thickness in the range from 10 to 50 μm, particularly preferably 20 to 30 μm. 9. The method according to claim 8, characterized in that the viscosity of the activator paste used in the screen printing process in the range of 1000 to 8000 mPas, preferably 2000 to 6000 mPas, and in the ink jet process in the range of 100 to 1000 mPas preferably 150 to 500 mPas. 10. The method according to one or more of claims 6 to 9, characterized in that for pressing the applied activator paste into the tissue (G) on the side opposite the coated side, negative pressure in the range from 500 to 1000 mbar, preferably over a time range of 2 up to 10 sec. 11. The method according to one or more of claims 6 to 10, characterized in that the electrically conductive coating (1,5) of the activated thread surfaces by means of electroless, chemical-reductive metallization with a metal from the group: Cu, Ni, Ag, Au or their alloys or layer combinations. 12. The method according to one or more of claims 6 to 11, characterized in that both sides of the fabric (G), preferably with a different structure, are partially electrically conductively coated and plated through in regions. 13. The method according to claim 12, characterized in that the two coatings (1), which are continuously spaced apart in the interior of the fabric, are subsequently connected in regions, preferably by conductive sewing, eyelets, crimping or piercing. 14. Use of a flexible conductor track structure according to one of claims 1 to 5, or manufactured according to one of claims 6 to 13, as a current conducting structure between at least one power source and a consumer in or on clothing or textile surfaces in the home, in advertising or the decoration.