WO2012092991A1 - Method for producing an electronic circuit, printing roller and method for producing same - Google Patents

Abstract

Method for producing an electronic circuit comprising a plurality of circuit elements having a predetermined cross section and a functional layer thickness of preferably less than 200 nm on a circuit substrate, using a printing roller, wherein the printing roller has an elastically compliant surface layer or layer near the surface, in such a way that the printing roller surface nestles elastically against unevennesses of the circuit substrate.

Description

 Description title

Method for producing an electronic circuit, pressure roller and method for producing such

The invention relates to a method of manufacturing an electronic circuit comprising a plurality of circuit elements of predetermined cross-section on a circuit substrate.

State of the art

In screen printing, rigid substrates can be printed, but the minimum achievable dry film thicknesses are in the range of 5 μm. By means of gravure far smaller layer thicknesses can be produced, however this process can not be realized with the usual chrome-plated copper cylinders on rigid substrates or only with unsatisfactory quality and high rejection rate. This manifests itself inter alia in an incomplete transfer of material from the impression cylinder to the substrate.

The flexographic printing also allows the required layer thicknesses in the range of a few nm to a few μιη and is also applicable for rigid substrates. A disadvantage of this process is the poor reproducibility of the material transfer in relation to the abovementioned processes and the inhomogeneity within a printed image (called a "squeeze margin") In this case, the ink transfer from the tampon to the substrate by the squeezing of the ink by the surface pressure in this step is critical to the imaging accuracy of the printing form on the substrate over the tampon. An alternative to the printing techniques for rigid substrates are spraying methods. Due to the process, it is possible to apply even thin layers homogeneously. Structuring of this coating can be done by masking, whereby lower limits in terms of structure resolution by the

Masking be set. Above all, however, depending on the structure, large material losses occur on the mask (for example, up to 95% of the surface is not coated in fineline applications, which is uneconomical, especially in the case of expensive functional materials).

Disclosure of the invention

The invention provides a gravure printing method employing a pressure roll having an elastically compliant surface layer or near-surface layer such that the pressure roll surface conforms to unevenness of the circuit substrate elastically.

With this method, in an economical process both a homogeneous generation of thin (functional) layers is possible, as well as the generation of fine (functional) structures. From the current perspective, a resolution for fine structures with line space of 10 pm / 10 μιτι is possible. The disadvantage of incomplete material transfer when using a hard

Pressure cylinder (copper-chrome) is corrected by a change of material to a flexible pressure roller.

In one embodiment of the invention, the pressure roller has a low surface energy cliche material. Suitable z. Example, an ethylene-propylene-Dicn-Monomo (EPDM) with 16 to 18 mN / m surface tension or a silicone rubber with 13 to 15 mN / m surface tension. This ensures a largely complete transfer of material from the printing form to the substrate and thus the generation of an exactly predeterminable thickness and shape of the respective (functional) layer. By avoiding color splitting in the printing form can thus in particular Advantageously, the precision of the material transfer can be improved in relation to the prior art.

In a further embodiment of the invention it is provided that a rigid and / or brittle substrate and / or substrate structured on the surface to be printed, for example a glass, a ceramic or a metal of high hardness, is used as the substrate. Particularly advantageous in this case is the use of a soft impression cylinder, since rigid substrates are usually subject to production-related deviations in form (ripple). As a result, a hard cylinder does not make contact with the substrate in all areas, and the printed image is transferred incompletely. It is furthermore particularly advantageous that even brittle substrates (glass, silicon, etc.) can be printed without destroying them by pressing on a hard pressure roller.

Furthermore, it is also advantageous to print structured, rigid and brittle substrates. By choosing the cylinder hardness, the enclosure of the surface structures can be adjusted. The specific adaptation of the Shore hardness of the printing cylinder depends on the dimension of the surface structure and the desired impression of the impression cylinder. A Shore hardness of 80 ° to 100 ° Shore is to be regarded as A suitable.

In a further embodiment of the invention, a pressure roller having at least one polymeric surface layer or polymeric sheath layer close to the surface is used. A polymer printing cylinder can be adapted to the respective substrate to be printed in terms of material hardness. Preferred polymer materials (examples) are EPDM and silicone rubber.

In a further embodiment, a pressure roller manufactured as a cylindrical sleeve, so-called SIeeve, with a removable elastically compliant surface layer or sheath layer close to the surface is used.

This results in particular cost advantages in terms of direct Printing form costs as well as cost advantages with regard to machine set-up times for printing form change.

In a further embodiment, the method is configured as a method for producing an organic solar cell structure. Especially in the field of organic and thin-film photovoltaics and organic electronics, the invention offers significant processing advantages and thus cost advantages.

The invention is in addition to the method described above, an applicable in this process pressure roller. Their features according to embodiments of the invention will become apparent from the above explanations, so that is omitted from a repetition at this point. drawings

Incidentally, advantages and expediencies of the invention will become apparent from the following description of exemplary embodiments with reference to the figures. From these show:

1 is a schematic cross-sectional view for explaining the prior art,

2 is a schematic cross-sectional view of an embodiment of the invention,

Fig. 3 is a schematic cross-sectional view of another

Embodiment of the invention, Fig. 4 is a schematic cross-sectional view of a pressure roller according to an embodiment of the invention and

Fig. 5 is a schematic cross-sectional view of a pressure roller according to another embodiment of the invention.

Fig. 1 shows a greatly enlarged section of the surface of a hard pressure roller 1 of conventional construction, such as chromium-plated copper, with engraving areas 3a, 3b in a printing process over a relatively hard substrate 5 with uneven or structured surface. It can be seen that the contact between the pressure roller surface and the substrate surface is imperfect and the engraving area 3a is partially and the engraving area 3b completely "suspended in the air", thus making possible no or at least no satisfactory transfer of printing paste to the substrate.

On the other hand, FIG. 2 shows that a pressure roller 1 'with an elastically soft surface layer in the engraving areas 3a' and 3b 'comes into perfect contact with the surface of the uneven substrate 5 and thus a substantially improved transfer of printing paste to the substrate surface If, in particular, the surface energy or stress of the material from which the surface of the pressure roller is made is set to the lowest possible value (in particular based on the surface energy or stress of the substrate material), a substantially complete transmission takes place The aforementioned statements apply to the same extent to the situation illustrated in Fig. 3, where the pressure roller 1 'is shown in the process of printing on a heavily structured substrate 5' Fig. 4 shows in a schematic cross-sectional illustration a multilayered one Pressure roller 10, the next to egg a central mandrel 11 a hard core 13th and at the periphery of which a surface layer 15 made of an elastically yielding material has, which here also serves as a cliché material. It is understood that the material of the surface layer, for example a polymer material, must be selected such that fine engraving in accordance with the structures to be produced on a substrate, in particular reproducibly in a large number of printing operations, is possible.

Fig. 5 shows as an alternative embodiment, a pressure roller 10 ', in which on the mandrel 11 removably a relatively soft core 13' is stretched. The roll core 13 'may have a hardness gradient in the radial direction or (which is not shown in the figure) in turn be composed of a plurality of concentric cylinders made of different materials. He wears a bend-deformable, but relatively hard surface layer 15 'as a cliché. This may be a thin metal layer, which is thick enough to produce the desired engravings and which enables the reproducible production of particularly fine structures on a substrate to be printed (for example of fine circuit traces) on a circuit substrate.

Within the scope of expert action, further refinements and embodiments of the method and apparatus described here by way of example only arise.

Claims

claims A method of making an electronic circuit comprising a plurality of circuit elements of predetermined cross-section and having a functional layer thickness of preferably less than 200 nm on a circuit substrate (5; 5 ') using a pressure roll (10; 10'), said pressure roll having a elastically compliant surface layer (15) or near-surface layer (13 '), such that the pressure roller surface conforms to unevenness of the circuit substrate elastically. Method according to claim 1,  wherein the pressure roller (10; 10 ') comprises a low surface energy printing plate material. Method according to claim 1 or 2,  wherein as the substrate (5, 5 ') a rigid and / or brittle and / or on the surface to be printed textured substrate, such as a glass, a ceramic or a metal of high hardness, is used. Method according to one of the preceding claims,  wherein a pressure roller (10, 10 ') with at least one polymeric surface layer or near-surface cladding layer is used. Method according to one of the preceding claims,  wherein in a cylindrical sleeve, so-called. Sleeve made pressure roller (10; 10 ') with a removable elastically yielding  Surface layer or near-surface cladding layer is used. Method according to one of the preceding claims, designed as a method for producing an organic solar cell structure. 7. pressure roller (10, 10 ') with an elastically compliant surface layer (15) or near-surface cladding layer (13'). A platen (10; 10 ') according to claim 7, comprising a low surface energy cliche material. 9. Pressure roller (10, 10 ') according to claim 7 or 8, with a polymeric surface layer (15) or near-surface cladding layer (13'). 10. A pressure roller according to any one of claims 7 to 9, wherein an elastically compliant surface layer (15) or near-surface cladding layer (13 ') is detachably mounted on a mandrel (11).