PRINTING DEVICE, PRINTING METHOD AND METHOD FOR MAKING A PRINTING DEVICE

Abstract

A printing device comprises a carrier with a pressure side. A plurality of cavities are formed on the pressure side. An electrically conductive heating layer is also arranged on the pressure side. Within each cavity, the heating layer comprises a wall section that is positioned against one wall of the respective cavity. An electrical voltage can be applied to the heating layer, causing a current to flow through the wall sections.

Description

[0001] The present invention relates to a printing device, a method for printing and a method for manufacturing a printing device.

[0002] Various methods for printing electrically conductive pastes are known in the art. Examples of such methods include screen and stencil printing and various needle dispensing methods.

[0003] One object of the present invention is to provide a printing device. Another object of the present invention is to specify a method for printing using such a printing device. Another object of the present invention is to specify a method for manufacturing such a printing device. These objects are achieved by a printing device, by a method for printing, and by a method for manufacturing a printing device having the features of the independent claims. Various developments are specified in the dependent claims.

[0004] A printing device comprises a carrier with a printing side. A plurality of cavities are formed on the printing side. Furthermore, an electrically conductive heating layer is arranged on the printing side. The heating layer comprises a wall section in the region of each cavity, which is arranged on a wall of the respective cavity. An electrical voltage can be applied to the heating layer, causing a current to flow through the wall sections.

[0005] This printing device allows for the simultaneous printing of a plurality of structures formed from a single printing material. For this purpose, the printing material can be arranged in the cavities on the printing side of the printing device's carrier and then transferred to a target substrate by heating. Heating is achieved by a current flowing through the heating layer. This enables fast and cost-effective printing.

[0006] In one embodiment of the printing device, a plurality of cavities parallel to the current flow direction and / or a plurality of cavities arranged one behind the other in the current flow direction are formed on the printing side. Advantageously, the printing device thus enables a flexible design of the pattern to be printed by the printing device.

[0007] In one embodiment of the printing device, the distance between two adjacent cavities is less than 100 µm. The distance can even be less than 50 µm or less than 20 µm. Advantageously, the printing device thus enables the printing of structures with very fine pitches.

[0008] In one embodiment of the printing device, the heating layer has a taper encompassing at least one of the wall sections. A cross-sectional area of ​​the heating layer oriented perpendicular to the current flow direction is reduced in the region of the taper compared to other sections of the heating layer. This results in a current flow through the heating layer in the region of the taper having a higher current flow density than other sections of the heating layer. As a result, the current flow in the region of the taper causes increased heating of the heating layer, which also leads to increased heating in the wall section of the heating layer. This supports the removal of the printing material arranged in the associated cavity from the cavity.

[0009] In one embodiment of the printing device, the taper is formed by a recess in the heating layer arranged between two adjacent cavities. This advantageously represents a particularly simple way of forming the taper.

[0010] In one embodiment of the printing device, cavities are formed between the wall section of the heating layer and the wall of the cavity in at least one cavity. These cavities can reduce thermal coupling between the heating layer and the wall of the cavity, thereby reducing the flow of heat from the heating layer into the carrier. This can enable particularly rapid and effective heating of the heating layer in the region of the wall section.

[0011] In one embodiment of the printing device, at least one cavity has a diameter of less than 100 µm in a direction parallel to the printing side. The diameter can even be less than 50 µm or less than 20 µm. Advantageously, in this case, the printing device enables printing of particularly fine structures.

[0012] In one embodiment of the printing device, two of the cavities have different shapes or different depths. This allows the printing device to print differently shaped structures.

[0013] In one embodiment of the printing device, the carrier has a viewing window that allows a view between a side of the carrier opposite the printing side and the printing side. This viewing window can make it possible to align the printing device with a mark formed on a target substrate, thereby advantageously enabling particularly simple and precise positioning of the printing device.

[0014] In one embodiment of the printing device, a protective layer is arranged on the heating layer. The protective layer comprises Mo, Wo, a silicon oxide, a silicon nitride, tungsten carbide, Al2O3, or diamond. This protective layer can advantageously protect the heating layer from damage. In particular, the protective layer can facilitate the damage-free introduction of a printing material into the cavities formed on the printing side.

[0015] In one embodiment of the printing device, an anti-adhesion layer is arranged on the heating layer in at least one cavity. Advantageously, the anti-adhesion layer can facilitate the removal of a printing material arranged in the cavity.

[0016] In one embodiment of the printing device, the printing side has a flat central section. The cavities are arranged at the central section. A first step and a second step are formed on two opposite outer edges of the central section. A first electrical contact to the heating layer is formed at the first step. A second electrical contact to the heating layer is formed at the second step. The electrical voltage can be applied to the heating layer by means of the first electrical contact and the second electrical contact. This advantageously represents a particularly simple design of the printing device. The steps formed at the outer edges of the central section make it possible to bring the printing side of the printing device close to a target substrate.

[0017] In another embodiment of the printing device, the carrier is designed as a roller. The printing side is formed by a peripheral surface of the roller. This variant of the printing device can advantageously enable continuous printing.

[0018] A method for printing using a printing device of the aforementioned type comprises steps of arranging a printing material in at least one of the cavities, arranging the printing side over a target substrate, and applying an electrical voltage to the heating layer to cause a current flow through the wall sections, whereby the printing material is heated and released from the cavity. This method advantageously enables rapid and cost-effective printing of structures formed from the printing material. The shape and arrangement of the structures can be predetermined by the shape and arrangement of the cavities of the printing device. The method can enable structures to be printed with very fine resolution.

[0019] In one embodiment of the method, the printing side is positioned above the target substrate such that the distance between the printing side and the target substrate is between 50 µm and 500 µm. Advantageously, such a distance between the printing side and the target substrate enables high precision in the transfer of the printing material from the printing device to the target substrate.

[0020] In one embodiment of the method, the printing device has a viewing window of the aforementioned type. The method comprises arranging the viewing window over a mark located on the target substrate. Advantageously, the method thereby enables particularly precise positioning of the printing device over the target substrate.

[0021] In one embodiment of the method, the carrier is designed as a roller in the manner described above. Arranging the printing side over the target substrate involves rolling the outer surface of the roller over the target substrate. Advantageously, in this case, the method can enable continuous operation of the printing device and serial printing on a plurality of target substrates.

[0022] A method for producing a printing device of the type described above comprises steps of providing a carrier with a printing side, forming the cavities on the printing side, and arranging the heating layer on the printing side. The cavities can be formed, for example, using an etching process. The heating layer can be arranged on the printing side, for example, by vapor deposition or by a cathode sputtering process. This method advantageously enables cost-effective production of the printing device.

[0023] In one embodiment of the method, the printing device is manufactured in the manner described above with a printing side having a flat central section. The method comprises further steps for forming the first step and the second step and for forming the first electrical contact and the second electrical contact. The formation of the first step and the second step can, for example, be carried out together with the formation of the cavities. The formation of the first electrical contact and the second electrical contact can, for example, comprise applying a copper layer and soldering power leads.

[0024] In one embodiment of the method, this comprises a further step of forming cavities between the wall section of the heating layer and the wall of the cavity in at least one cavity. The cavities are formed using a sacrificial layer. Advantageously, forming the cavities requires only minimal additional effort.

[0025] The above-described properties, features and advantages of this invention, as well as the manner in which they are achieved, will become clearer and more clearly understandable in connection with the following description of the embodiments, which are explained in more detail in connection with the drawings. In each case, in a schematic representation Fig. 1 is a sectional side view of a first processing stage during manufacture of a printing device; Fig. 2 a second processing stage during the manufacture of the printing device; Fig. 3 a third processing stage during the manufacture of the printing device; Fig. 4 a sectional side view of a variant of a printing device; Fig. 5 is a view of a printing side of the printing device; Fig. 6 a sectional side view of a first method step during printing by means of the printing device; Fig. 7 a second step of the printing process; Fig. 8 a third step of the printing process; Fig. 9 a view of the printing side of another variant of the printing device; Fig. 10 is a view of the printing side of another variant of the printing device; Fig. 11 a sectional side view of another variant of the printing device; Fig. 12 a sectional side view of another variant of the printing device; Fig. 13 a sectional side view of another variant of the printing device; Fig. 14 is a sectional side view of another variant of the printing device; and Fig. 15 a sectional side view of another variant of the printing device.

[0026] Fig. Figure 1 shows a schematic representation of a sectional side view of a portion of a carrier 100 in an unfinished processing stage during the manufacture of a printing device. The carrier 100 can be formed, for example, from glass. The carrier 100 has a printing side 101 and a side 102 opposite the printing side 101. The printing side 101 has a flat central section 110. The central section 110 can, for example, have a rectangular shape.

[0027] A plurality of cavities 200 are formed in the central portion 110 of the printing side 101. The cavities 200 can, for example, have a regular matrix arrangement or an irregular two-dimensional pattern in the central portion 110. The cavities 200 form depressions extending into the material of the carrier 100 and can, for example, each have a conical shape. It is possible for different cavities 200 to have different shapes.

[0028] A distance 240 between two adjacent cavities 200 can be less than 100 µm, in some variants even less than 50 µm or even less than 20 µm. It is possible for the distances between adjacent cavities 200 to be designed differently for different cavities 200. For one, several, or all of the cavities 200, a diameter 220 measured in a direction 105 parallel to the printing side 101 can be less than 100 µm, in some variants even less than 50 µm or less than 20 µm. It is possible for different cavities 200 to have different diameters 220. A depth 230 measured in a direction 106 perpendicular to the printing side 101 can, for example, have a similar size to the diameter 220 for the cavities 200. The depth 230 can vary by 200 for different cavities.

[0029] The cavities 200 may, for example, have been formed on the printing side 101 of the carrier 100 by an etching process. Subsequently, a grinding process may have been performed to increase the flatness of the printing side 101.

[0030] A first step 123 is formed on a first outer edge 120 of the central section 110. A second step 133 is formed on a second outer edge 130 of the central section 110, opposite the first outer edge 120. In the region of the first step 123 and the second step 133, the surface of the carrier 100 is set back from the central section 110 in the direction 106 perpendicular to the printing side 101. The first step 123 and the second step 133 can be formed, for example, by an etching process, for example, together with the cavities 200.

[0031] Fig. Figure 2 shows a schematic sectional side view of the carrier 100 in one of the representations of Fig. 1 chronologically subsequent processing stage. An electrically conductive heating layer 300 has been arranged on the print side 101 of the carrier 100. The heating layer 300 comprises an electrically conductive material, for example, a metal. It is expedient for the material of the heating layer 300 to have a high electrical resistance, so that a current flow through the heating layer 300 causes the heating layer 300 to heat up considerably. The heating layer 300 can comprise platinum, for example. The heating layer 300 can be applied, for example, by vapor deposition or by a cathode sputtering process. The heating layer 300 can have a thickness of 100 nm, for example.

[0032] In the example shown, the heating layer 300 completely covers the printing side 101 of the carrier 100. This means that the heating layer 300 covers both the central section 110 of the printing side 101 and the first step 123 and the second step 133. The heating layer 300 also includes a wall section 310 in the area of ​​each cavity 200, which is arranged on a wall 210 of the respective cavity 200.

[0033] Fig. Figure 3 shows a schematic sectional side view of the carrier 100 in one of the representations of Fig. 2 temporally subsequent processing stage. A metallization 140 has been formed on each of the first step 123 and the second step 133. The metallization 140 can comprise copper, for example. The application and structuring of the metallization 140 can include, for example, a galvanic process, a vapor deposition process, a cathode sputtering process, a lithographic process, and the use of a shadow mask. The metallizations 140 are electrically conductively connected to the heating layer 300.

[0034] Fig. Figure 4 shows a schematic sectional side view of the carrier 100 in one of the representations of Fig. 3 subsequent processing stage. By soldering electrical conductors 145 to the metallizations 140, a first electrical contact 127 to the heating layer 300 was formed at the first step 123, and a second electrical contact 137 to the heating layer 300 was formed at the second step 133.

[0035] An electrical voltage can be applied to the heating layer 300 by means of the first electrical contact 127 and the second electrical contact 137. An electrical voltage applied via the electrical contacts 127, 137 causes a current flow through the heating layer 300, which flows through the wall sections 310 of the heating layer 300. Such a current flow can cause heating of the heating layer 300, in particular heating of the wall sections 310 of the heating layer 300.

[0036] The first electrical contact 127 and the second electrical contact 137 can also be arranged differently than in Fig. 4. It is only essential that the first electrical contact 127 and the second electrical contact 137 enable an electrical voltage to be applied to the heating layer 300 in such a way that a current flow through the wall sections 310 is effected.

[0037] In Fig. 4, the production of a variant of a printing device 10 is completed. Fig. Figure 5 shows a schematic view of a part of the printing side 101 of the carrier 100 of the printing device 10. Further below, the Fig. 6 to 8 describe a printing method that can be carried out with the printing device 10.

[0038] In Fig. In the example shown in Figure 5, several cavities 200 are formed on the print side 101 of the carrier 100. An electrical voltage applied to the heating layer 300 via the electrical contacts 127, 137 causes a current flow in a current flow direction 305. In the Fig. In the example shown in Figure 5, several cavities 200 are arranged parallel to one another in the current flow direction 305. Furthermore, several cavities 200 are also arranged one behind the other (in series) in the current flow direction 305. In other variants of the printing device 10, however, all cavities 200 can be arranged parallel or serially in the current flow direction 305.

[0039] Fig. 6 shows a schematic sectional side view of a portion of the printing device 10 during the execution of a first method step of a printing process. In the illustrated method step, a printing material 500 is arranged in at least one of the cavities 200. In most variants of the method, it is expedient to arrange the printing material 500 in all cavities 200 of the printing device 10.

[0040] The printing material 500 can be formed, for example, as a paste. The printing material 500 can be electrically conductive or electrically non-conductive. The printing material 500 can, for example, contain a solvent or another component that can be vaporized by heating.

[0041] The printing material 500 can be introduced into the cavities 200, for example, using a squeegee 510. It is expedient if the cavities 200 are completely filled by the printing material 500.

[0042] Fig. Figure 7 shows a schematic sectional side view of one of the representations of the Fig. 6 temporally subsequent method step. In this case, the printing side 101 of the printing device 10 is arranged over a top side 601 of a target substrate 600 and aligned in a desired manner. It is expedient to arrange the printing side 101 of the carrier 100 as parallel as possible to the top side 601 of the target substrate 600. A distance 610 between the printing side 101 and the target substrate 600 can be, for example, between 50 µm and 500 µm.

[0043] Fig. Figure 8 shows a schematic sectional side view of one of the representations of the Fig. 7 chronologically subsequent process stage. After arranging and aligning the print side 101 of the printing device 10 over the top side 601 of the target substrate 600, an electrical voltage was applied to the heating layer 300 of the printing device 10 via the first electrical contact 127 and the second electrical contact 137. This electrical voltage caused a current flow running in the current flow direction 305 through the wall sections 310 of the heating layer 300, which heated the heating layer 300, particularly in the region of its wall sections 310. As a result, the printing material 500 arranged in the cavities 200 was heated, released from the cavities 200, and transferred to the top side 601 of the target substrate 600, where it now forms printed structures 520.

[0044] It is expedient if the heating of the heating layer 300 and the printing material 500 arranged in the cavities 200 occurs very quickly. For this purpose, the electrical voltage applied to the heating layer 300 can, for example, comprise one or more short pulses with a large amplitude. The pulse duration can, for example, be in the range of nanoseconds. It is possible to regulate the temperature of the heating layer 300 using a control loop, for which a temperature measurement can be carried out, for example, via a resistance measurement.

[0045] Heating the printing material 500 arranged in the cavities 200 can, for example, cause parts of the printing material 500 to evaporate, causing the printing material 500 arranged in the cavities 200 to be ejected from the cavities 200 and shot toward the top side 601 of the target substrate 600. The printing material 500 can, for example, be heated at least in sections to a temperature of more than 200°C.

[0046] The printing device 10 can subsequently be reused, and the process can be repeated, beginning with a refill of the cavities 200 with printing material 500. Under certain circumstances, cleaning of the printing side 101 of the printing device 10 may be necessary beforehand.

[0047] Based on the Fig. 9 to 14, further variants of the printing device 10 are described below. These each have additional features compared to the previously described variant of the printing device 10. These additional features can be incorporated individually or in combination with one another into the previously described variant of the printing device 10.

[0048] Fig. 9 shows a plan view of the printing side 101 of a variant of the printing device 10, in which the heating layer 300 has a plurality of tapers 320, each of which comprises one or more wall sections 310 of the heating layer 300.

[0049] In the region of the tapers 320, a cross-sectional area 340 of the heating layer 300 oriented perpendicular to the current flow direction 305 is reduced compared to other sections of the heating layer 300. This means that the cross-sectional area 340 in the region of the wall sections 310 is reduced such that an electric current flowing through the heating layer 300 in the current flow direction 305 has an increased current flow density in these regions. This results in Fig. 9, the variant of the printing device 10 leads to a particularly strong heating of the heating layer 300 in the areas of the wall sections 310.

[0050] The tapers 320 are in the Fig. 9 is formed by recesses 330 arranged between adjacent cavities 200 in the heating layer 300. The heating layer 300 covers in the Fig. In the variant of the printing device 10 shown in Figure 9, the printing side 101 of the carrier 100 is therefore not complete, but is structured.

[0051] Fig. 10 shows a top view of the printing side 101 of a further variant of the printing device 10. In this variant, the carrier 100 has a viewing window 150 that allows a view between the side 102 opposite the printing side 101 and the printing side 101. As a result, the viewing window 150 allows a view of a portion of the top side 601 of the target substrate 600 while the printing side 101 of the printing device 10 is being arranged over the top side 601 of the target substrate 600. This makes it possible to arrange the viewing window 150, for example, over a mark located on the target substrate 600 in order to align the printing device 10 with the target substrate 600 in a desired manner. It is of course possible to provide multiple viewing windows 150.

[0052] Fig. 11 shows a schematic sectional side view of a variant of the printing device 10, in which the carrier 100 comprises a first section 160 and a second section 170. The first section 160 and the second section 170 are arranged flat on one another in such a way that the second section 170 forms the printing side 101 of the carrier 100 and the first section 160 forms the side 102 opposite the printing side 101.

[0053] The first section 160 and the second section 170 can be formed from different materials. For example, the first section 160 of the carrier 100 can be formed from glass. The second section 170 can be formed from a plastic, for example, and can be produced, for example, by an injection molding process or by a 3D printing process. The first section 160 can serve, for example, for stabilization and can expediently have a high level of flatness and low thermal expansion. The second section 170 can enable cost-effective production and provide good thermal insulation for the heating layer 300.

[0054] Fig. 12 shows a schematic sectional side view of a variant of the printing device 10, in which different cavities 200 have different shapes. For example, the diameter 220, the depth 230, the distance 240 between the cavities 200, or the overall shape of the respective cavity 200 may differ for different cavities 200. It is also possible for a cavity 200 to comprise several sections of different depths 230 or different diameters 220.

[0055] Fig. 13 shows a schematic sectional side view of a variant of the printing device 10, in which a protective layer 350 is arranged on the heating layer 300. The protective layer 350 thus partially or completely covers the heating layer 300. The protective layer 350 can, for example, comprise Mo, Wo, a silicon oxide, a silicon nitride, tungsten carbide, Al2O3, or diamond. The protective layer 350 serves to protect the heating layer 300 from damage caused by mechanical influences. For example, the protective layer 350 can protect the heating layer 300 from damage caused by the doctor blades 510 used to introduce the printing material 500 into the cavities 200.

[0056] In the Fig. In the variant shown in Figure 13, a non-stick layer 360 is also arranged on the heating layer 300. In the example shown, the non-stick layer 360 is arranged on the protective layer 350, which in turn is arranged on the heating layer 300. If the protective layer 350 is omitted, the non-stick layer 360 can also be arranged directly on the heating layer 300. However, the non-stick layer 360 can also be omitted.

[0057] The non-stick layer 360 can completely cover the heating layer 300 or the protective layer 350. However, the non-stick layer 360 can also be limited to sections of the heating layer 300, in particular, for example, to the wall sections 310 of the heating layer 300 arranged on the walls 210 of the cavities 200.

[0058] The anti-adhesive layer 360 can serve to facilitate the removal of the printing material 500 from the cavities 200.

[0059] Fig. 14 shows a schematic sectional side view of a variant of the printing device 10, in which, in at least one cavity 200, cavities 250 are formed between the wall section 310 of the heating layer 300 and the wall 210 of the cavity 200. It is expedient if such cavities 250 are present in all cavities 200. The cavities 250 can be filled, for example, with air or another gas. The cavities 250 can reduce thermal coupling between the wall section 310 of the heating layer 300 and the wall 210 of the cavity 200, so that heat flow from the heating layer 300 into the carrier 100 is reduced. This can enable even more effective and faster heating of the wall sections 310 of the heating layer 300.

[0060] To produce the cavities 250, a sacrificial layer can be used, for example, which is arranged and structured on the walls 210 of the cavities 200 before the heating layer 300 is applied. After the subsequent application of the heating layer 300, the sacrificial layer is removed, for example, by means of an etching process. For this purpose, openings can be provided in the heating layer 300 through which an etching medium can penetrate to the sacrificial layer. The cavities 250 are formed by removing the sacrificial layer.

[0061] Fig. Figure 15 shows a schematic sectional side view of another variant of the printing device 10. In this variant, the carrier 100 is designed as a roller 400. The printing side 101 of the carrier 100 is formed by a lateral surface 410 of the roller 400.

[0062] The heating layer 300 arranged on the pressure side 101 of the carrier 100 is in the Fig. 15, the heating layer 300 is divided into several sections 370 in the circumferential direction of the roller 400. Each section 370 of the heating layer 300 comprises one or more wall sections 310 that cover the walls 210 of one or more cavities 200 formed on the printing side 101.

[0063] The individual sections 370 of the heating layer 300 can be separately supplied with electrical voltage to cause a current flow through the respective section 370 of the heating layer 300 and through the wall sections 310 of the respective section 370 of the heating layer 300. For this purpose, the electrical contacts 127, 137 in Fig. 15, they are designed as contact needles, each of which contacts a section 370 of the heating layer 300.

[0064] A printing process using the Fig.A 15-variant of the printing device 10 also comprises arranging the printing material 500 in at least one of the cavities 200, arranging the printing side 101 over the target substrate 600, and applying an electrical voltage to a section 370 of the heating layer 300 to cause a current flow through the wall sections 310 of this section 370, by which current flow the printing material 500 is heated and released from the at least one cavity 200. However, arranging the printing side 101 over the target substrate 600 comprises rolling the outer surface 410 of the roller 400 over the target substrate 600. For example, the printing method can be carried out such that the roller 400 rotates stationary about its longitudinal axis. At the same time, a plurality of target substrates 600 are guided past the roller 400 and each printed. At a location in the circumferential direction of the roller 400, the cavities 200 are filled with printing material 500 by means of the doctor blade 510.At another location in the circumferential direction of the roller 400, the electrical contacts 127, 137 contact a section 370 of the heating layer 300, each arranged just above the upper side 601 of one of the target substrates 600, whereby the printing material 500 is transferred from the cavities 200 assigned to this section 370 of the heating layer 300 to the upper side 601 of the target substrate 600. At another location in the circumferential direction of the roller 400, the printing side 101 can be cleaned, for example by spraying a cleaning material 430. Correct alignment of the printing device 10 and the target substrates 600 can be ensured by means of an adjustment camera 420.

[0065] The invention has been illustrated and described in more detail using the preferred embodiments. However, the invention is not limited to the disclosed examples. Other variations may be devised by those skilled in the art. LIST OF REFERENCE SYMBOLS 10 Printing device 100 carriers 101 printed pages 102 opposite page 105 direction parallel to the print side 106 direction perpendicular to the print side 110 middle section 120 first outer edge 123 first gradation 127 first electrical contact 130 second outer edge 133 second gradation 137 second electrical contact 140 Metallization 145 electrical conductor 150 viewing windows 160 first section 170 second section 200 cavities 210 wall 220 diameter 230 depth 240 distance 250 cavity 300 heating layer 305 Direction of current flow 310 wall section 320 Rejuvenation 330 recess 340 cross-sectional area 350 protective layer 360 non-stick coating Section 370 400 roller 410 lateral surface 420 adjustment camera 430 cleaning materials 500 printing materials 510 Squeegee 520 printed structure 600 Target substrate 601 top 610 distance

Claims

[1] Printing device (10) with a carrier (100) with a printing side (101), wherein a plurality of cavities (200) are formed on the pressure side (101), wherein an electrically conductive heating layer (300) is arranged on the pressure side (101), wherein the heating layer (300) comprises in the region of each cavity (200) a wall section (310) which is arranged on a wall (210) of the respective cavity (200), wherein an electrical voltage can be applied to the heating layer (300), which causes a current flow through the wall sections (310). [2] Printing device (10) according to claim 1, wherein a plurality of cavities (200) parallel in the current flow direction (305) are formed on the printing side (101) and / or a plurality of cavities (200) are formed one behind the other in the current flow direction (305) on the printing side (101). [3] Printing device (10) according to one of the preceding claims, wherein a distance (240) between two adjacent cavities (200) is less than 100 µm, in particular less than 50 µm, in particular less than 20 µm. [4] Printing device (10) according to one of the preceding claims, wherein the heating layer (300) has a taper (320) comprising at least one of the wall sections (310), wherein a cross-sectional area (340) of the heating layer (300) oriented perpendicular to the current flow direction (305) is reduced in the region of the taper (320) compared to other sections of the heating layer (300). [5] Printing device (10) according to claim 4, wherein the taper (320) is formed by a recess (330) in the heating layer (300) arranged between two adjacent cavities (200). [6] Printing device (10) according to one of the preceding claims, wherein in at least one cavity (200) cavities (250) are formed between the wall section (310) of the heating layer (300) and the wall (210) of the cavity (200). [7] Printing device (10) according to one of the preceding claims, wherein at least one cavity (200) has a diameter (220) of less than 100 µm, in particular less than 50 µm, in particular less than 20 µm, in a direction (105) parallel to the printing side (101). [8] Printing device (10) according to one of the preceding claims, wherein two of the cavities (200) have different shapes or different depths (230). [9] Printing device (10) according to one of the preceding claims, wherein the carrier (100) has a viewing window (150) which allows a view between a side (102) of the carrier (100) opposite the printing side (101) and the printing side (101). [10] Printing device (10) according to one of the preceding claims, wherein a protective layer (350) is arranged on the heating layer (300), wherein the protective layer (350) comprises Mo, Wo, a silicon oxide, a silicon nitride, tungsten carbide, Al2O3 or diamond. [11] Printing device (10) according to one of the preceding claims, wherein an anti-adhesive layer (360) is arranged on the heating layer (300) in at least one cavity (200). [12] Printing device (10) according to one of the preceding sayings, wherein the pressure side (101) has a flat central section (110), wherein the cavities (200) are arranged at the central portion (110), wherein a first step (123) and a second step (133) are formed on two opposite outer edges (120, 130) of the central section (110), wherein a first electrical contact (127) to the heating layer (300) is formed on the first step (123) and a second electrical contact (137) to the heating layer (300) is formed on the second step (133), wherein the electrical voltage can be applied to the heating layer (300) by means of the first electrical contact (127) and the second electrical contact (137). [13] Printing device (10) according to one of claims 1 to 11, wherein the carrier (100) is designed as a roller (400), wherein the printing side (101) is formed by a lateral surface (410) of the roller (400). [14] Printing process by means of a printing device (10) according to one of the preceding claims, the method comprising the following steps: - arranging a printing material (500) in at least one of the cavities (200); - arranging the print side (101) over a target substrate (600); - applying an electrical voltage to the heating layer (300) to cause a current flow through the wall sections (310), whereby the printing material (500) is heated and released from the cavity (200). [15] The method according to claim 14, wherein the printing side (101) is arranged over the target substrate (600) such that a distance (610) between the printing side (101) and the target substrate (600) is between 50 µm and 500 µm. [16] Method according to one of claims 14 and 15, wherein the printing device (10) is designed according to claim 9, wherein the viewing window (150) is arranged over a mark located on the target substrate (600). [17] Method according to one of claims 14 to 16, wherein the printing device (10) is designed according to claim 13, wherein arranging the printing side (101) over the target substrate (600) comprises rolling the outer surface (410) of the roller (400) over the target substrate (600). [18] Method for producing a printing device (10), wherein the printing device (10) is designed according to one of claims 1 to 13, the method comprising the following steps: - Providing a carrier (100) with a print side (101); - forming the cavities (200) on the pressure side (101); - Arranging the heating layer (300) on the pressure side (101). [19] Method according to claim 18, wherein the printing device (10) is designed according to claim 12, the method comprising the following further steps: - forming the first gradation (123) and the second gradation (133); - forming the first electrical contact (127) and the second electrical contact (137). [20] Method according to claim 18, wherein the printing device (10) is designed according to claim 6, the method comprising the following further step: - forming the cavities (250) by means of a sacrificial layer.

Images