METHOD AND DEVICE FOR PRODUCING ELECTRICAL COMPONENTS ON A FLEXIBLE SUBSTRATE

Abstract

The invention relates to a method for producing electrical or electronic components or circuits on a flexible, flat or three-dimensional substrate via the application of a liquid or paste-like starting material for a structured or unstructured electrical or electronic functional layer, and subsequent drying, sintering and/or curing of the starting material on the substrate, wherein the step of drying, sintering and/or curing involves a short surface-application of the coated substrate with radiation in the near-infrared range, with an amplitude maximum in a wavelength range between 800 and 1500 nm and with a power density on the surface of the substrate between 50 kW/m.sup.2 and 1000 kW/m.sup.2.

Claims

1. A method for producing electrical or electronic components or circuits on a flexible, flat or three-dimensional substrate via the application of a liquid or paste-like starting material for a structured or unstructured electrical or electronic functional layer, and subsequent drying, sintering and/or curing the starting material on the substrate, wherein the step of drying, sintering and/or curing involves a short surface-application of the coated substrate with radiation of halogen spotlights or IR LEDs in the near-infrared range, with an amplitude maximum in a wavelength range between 800 and 1,500 nm and with a power density on the surface of the substrate between 50 kW/m.sup.2 and 1,000 kW/m.sup.2.

2. The method according to claim 1, wherein the substrate is a temperature-sensitive substrate, such as a polymer film or paper, and the power density and the exposure time of the near-infrared radiation are set such that the temperature does not rise above a material-critical temperature, in particular not above a temperature in the range between 100° C. and 200° C.

3. The method according to claim 1, wherein liquid starting material is selectively applied to the substrate by a printing process, and the power density and exposure time of the near-infrared radiation are set such that within the selective coating, a temperature above a material-specific sintering or curing temperature, in particular above a temperature in the range between 50 and 200° C. is achieved for a short time.

4. The method according to claim 1, wherein a paste-like starting material is applied onto the substrate over the whole surface, in particular by a roller or blade application process, and the power density and exposure time of the near-infrared radiation are set such that within the selective coating, a temperature above a material-specific sintering or curing temperature is achieved for a short time.

5. The method according to claim 2, wherein the exposure time of the near-infrared radiation is chosen to be in the range between 1 s and 30 s, in particular between 2 s and 20 s.

6. The method according to claim 1, wherein the near-infrared radiation is performed within a NIR irradiation zone at a predetermined profile of non-constant power density, and the power density profile in the irradiation zone, in particular, is settable in response to material characteristics of the substrate and/or the starting material.

7. The method according to claim 1, wherein the near-infrared radiation is linked to an air flow at least on one surface of the substrate.

8. The method according to claim 7, wherein the air flow in the irradiation zone and/or a supply of hot air in an optionally provided hot air dryer onto both of the surfaces of the substrate is provided and is in particular settable.

9. The method according to claim 1, wherein subsequent to the near-infrared radiation, the coated substrate is conveyed through a treatment temperature maintaining zone, in particular a hot air dryer.

10. The method according to claim 1, configured as a method for producing a battery electrode or fuel cell electrode, wherein as the substrate, a polymer film having a thickness in the range between 75 μm and 200 μm or a metal film in the range between 3 μm and 10 μm, and as the coating, a viscous paste on the basis of water or based on an organic solvent is used, which has an initial thickness in the range between 10 and 1,000 μm and a solid content in the range between 40% and 80%, and wherein for the drying, sintering and/or curing, near-infrared radiation having a power density in the range between 50 and 200 kW/m.sup.2, in particular 70 and 150 kW/m.sup.2 is used.

11. An arrangement for performing the method according to claim 1, comprising conveyance means for conveying the flexible substrate through the arrangement, coating means for coating the flat substrate with the starting material, in particular during conveyance of the substrate, and means for drying, sintering and/or curing the starting material layer on the substrate, in particular during conveyance of the substrate, which include at least one halogen spotlight or an IR LED for radiation in the range of near infrared, the amplitude maximum of which is in the wavelength range between 800 nm and 1,500 nm, and which is settable such that its power density on the surface of the substrate is in the range between 50 kW/m.sup.2 and 1,000 kW/m.sup.2.

12. The arrangement according to claim 11, wherein the means for drying, sintering and/or curing include a plurality of NIR radiation sources, which are arranged and/or controllable in a NIR irradiation zone such that, within the irradiation zone, a predetermined profile of non-constant power density is producible on the surface of the starting material layer.

13. The arrangement according to claim 11, wherein the means for drying, sintering and/or curing furthermore have a treatment temperature maintaining zone, which is in particular configured as a hot air dryer.

14. The arrangement according to claim 12, wherein the NIR irradiation zone has means assigned for supplying an air flow.

15. The arrangement according to claim 14, wherein the means for supplying an air flow and/or the treatment temperature maintaining zone have control means for controlling the air flow or the temperature in the treatment temperature maintaining zone.

Description

[0029] Advantages and expediencies of the invention incidentally will arise from the following description of exemplary embodiments and aspects, in part on the basis of Figures. Shown are in:

[0030] FIG. 1 a schematic representation of an embodiment of the arrangement according to the invention in the manner of a longitudinal section,

[0031] FIG. 2 a schematic representation of an embodiment of the NIR dryer 1A according to FIG. 1, and

[0032] FIG. 3 a schematic representation of a further embodiment of the NIR dryer of an arrangement according to the invention together with further plant components.

[0033] FIG. 1 shows the concept of a drying plant 1 for functionally coated substrates 2, which are intended to serve as battery or fuel cell electrodes in the finished state. The substrate may be a virtually endless Al film or Cu film, which have been coated in a coater (not shown here) by means of a blade system or a wide slot nozzle with a viscous paste 2a on the basis of water or based on an organic solvent having a typical solid content between 50% and 70%.

[0034] The thickness of the substrate film may be in the range between 5 and 150 μm, and the wet layer thickness of the viscous paste may be in the range between 10 and 1,000 μm. In the illustrated realization, the coating is applied on one side onto the surface of the substrate, however battery components coated on both sides may also be provided in consecutive coating and drying phases. Instead of metal films, polymer films (e.g. PET films) having a significantly larger thickness (e.g. between 100 and 150 μm) may be used as the substrates.

[0035] For drying the mentioned substrates, the drying plant 1 comprises a NIR dryer 1A having NIR radiators (not shown here) provided on both sides of the substrate 2, and an integrated hot air ventilation symbolized by the arrows Vi and Vo. The NIR dryer 1A has a variably settable temperature profile, which is realized by corresponding power controllers of the NIR dryers, and also the hot air flow is settable. In the conveying direction of the substrate 2 downstream of the NIR dryer 1A, a hot air dryer 1B connects directly to it, which likewise has a hot air ventilation Vi/Vo with a variably settable amount of air.

[0036] In a total plant length of several meters, which is considered to be advantageous for space reasons, and with a NIR dryer equipped with commercial NIR radiators having assigned reflectors, while considering the drying process quality requirements, throughput speeds in the range of 1-2 m/min, and thus a drying process may be realized, which offers significant advantages with respect to space requirements and throughput as compared to known drying plants.

[0037] FIG. 2 shows essential components of an exemplary NIR dryer 1A according to FIG. 1 by way of example in the manner of a functional block diagram. The Figure should be understood as a schematic sketch and is not intended to show the real mechanical construction of the NIR dryer. For the purpose of simplification, merely the functional components above the substrate 2 are represented. Corresponding components may also be provided below the substrate; but realizations of the arrangement according to the invention are also possible, in which corresponding means are exclusively provided on one (the coated) side of the substrate.

[0038] The NIR dryer 1A comprises several NIR radiators 11 each having an assigned reflector 12 and each being individually connected to one control output of a power control unit 13. The irradiation power of each individual NIR radiator 11 can thus be separately set via the power control unit 13, and thus a predetermined power density profile of the NIR radiation can be realized on the substrate 2 over the length of the NIR dryer 1A.

[0039] Via an air supply 14, an amount of air, which is controllable via an air amount control unit 15, gets into the input of the NIR dryer 1A, and via an exhaust air output 16, the heated exhaust air, which has adsorbed solvent components of the coating 2a, gets into a heat exchanging and filtering unit 17. In the heat exchanging and filtering unit 17, excessive heat is extracted from the exhaust air of the NIR dryer and provided for being externally used, and the solvent components are filtered out in an environmentally friendly manner and recycled, if necessary.

[0040] FIG. 3 shows an example of an arrangement 1′ for performing the method according to the invention, in which two transport rollers 1C, 1E as conveyance means for conveying the substrate 2 through the arrangement, and a blade device 1D as a coating device are schematically illustrated. For sintering/curing the coating 2a applied onto the substrate 2, a NIR irradiation zone 1A′ is realized by a plurality of NIR radiators 11a-11g each having a reflector 12a-12g fitted.

[0041] It is pointed out that the number and realization of the NIR radiators should be merely understood here as being a conceptual representation. By a set of radiators of different reflector geometry at a different distance, a pre-warming zone 1.1, a main drying zone 1.2 and a temperature maintaining zone 1.3 are realized within the NIR irradiation zone 1A′. This represents an alternative to the individual power setting explained further above in the context of FIG. 2 of NIR radiators that are basically of identical construction.

[0042] In an arrangement according to the invention, preponderantly cost-effective rod-shaped halogen spotlights, which have proven to be successful in drying tasks for a long time, come into question as the NIR radiators. Basically, however, a NIR irradiation zone may also be realized by radiators shaped otherwise or by an LED array having correspondingly high-power IR LEDs. Both realizations are familiar to the expert and therefore do not need any further explanation here.

[0043] As the reflectors, both individual reflectors, each structurally combined with a radiator, and integrated reflector arrangements come into question, which are assigned to several radiators. Also in such coherent reflector assemblies, different reflector geometries for the respective radiators can be realized (as shown in FIG. 3 in the manner of a sketch).

[0044] Arrangements of the kinds shown in the Figures, if necessary, modified in an application-specific way, are also usable for producing products from the field of “printed electronics”. The substrates are in this case, for example, paper or plastic films, which are not allowed to be heated above limit temperature in a range between approximately 80° C. and 140° C. depending on the material characteristics, and the substrates—depending on the function of the corresponding component—may be conductive inks, pastes or else powder. The thermal treatment consequently is targeted to evaporating water or solvents, sintering the paste, melting and, if necessary, sintering a powder, and, if necessary, also to inducing thermochemical reactions and phase transformations in the coating.

[0045] According to the inventors' researches, in these processes as well, the use of a NIR irradiation zone offers substantial acceleration and thus the possibility of significantly increasing the throughput and/or reducing the constructional length of a corresponding dryer.

[0046] The realization is not restricted to the examples and emphasized aspects explained above, but is likewise possible in a plurality of modifications, which are within the scope of the field of the attached claims.