WO2010142271A2

WO2010142271A2 - Screen printing frame

Info

Publication number: WO2010142271A2
Application number: PCT/DE2010/000637
Authority: WO
Inventors: Mike Becker; Dietmar LÜTKE-NOTARP
Original assignee: Nb Technologies Gmbh
Priority date: 2009-06-09
Filing date: 2010-06-09
Publication date: 2010-12-16
Also published as: WO2010142271A3; TW201105517A; CN102458856A; DE102009024874A1; DE202010007771U1; CN201824659U

Abstract

The invention relates to a screen printing frame comprising: a screen printing template carrier designed as a foil provided with first cavities, which are designed such that they reach from an upper side to a bottom side of the foil, a screen printing template designed as a masking layer, which is rigidly connected to the bottom side of the screen printing template carrier, wherein the masking layer is provided with second cavities which at least partially overlap the first cavities of the screen printing template carrier such that a printing medium can be guided through the first cavities of the screen printing template carrier from the upper side thereof through the second cavities of the masking layer in the direction of the bottom side and onto a substrate placed beneath. Said screen printing template carrier and/or the masking layer is/are designed in such a way that a projection projects into the region of at least one first and one second cavity thus reducing the passage surface thereof for a printing medium, the height of the projection in the region of the first cavity being lower than the height of the screen printing template carrier, and/or the height of the projection in the second cavity being lower than the height of the screen printing template.

Description

screen printing forme

The invention relates to a screen printing form with a screen printing stencil carrier and a screen printing stencil, which is attached to the underside of the screen printing stencil carrier.

In the case of screen printing or throughprinting, a printing medium is applied to a screen printing form, the printing medium then being conveyed into recesses of the screen printing form by means of a doctor blade guided along the upper side or very close to the upper side of the screen printing form. There are screen printing forms having a screen printing stencil carrier with first recesses which are formed so as to extend from an upper side to the lower side of the screen stencil carrier. On the underside of the screen printing stencil carrier can then be mounted a screen printing stencil, which is provided with second recesses, wherein the second recesses at least partially with the first recesses of the

Screen printing stencil carrier lie in coverage. By a single or multiple blade movement over the screen printing stencil carrier, it is possible to convey the printing medium through the first recesses and second recesses on a substrate arranged underneath. At the areas covered by the screen printing stencil no pressure medium, so that on the substrate a

Printed image arises, which essentially corresponds to the recesses of the screen printing stencil.

Screen printing and the use of screen printing forms have long been known and proven. With increasing miniaturization of webs to be printed, for example, for a solar cell, however, the difficulty arises to be able to convey the printing medium through the then narrow recesses through a screen printing form. The printing medium may no longer reach the substrate and remain suspended within the recess, so that as a result no pressure is achieved on the substrate.

If narrow webs are to be printed, one possibility is to introduce the print medium onto the screen-recessed stencil carrier provided with narrow recesses by means of a doctor blade, which is guided with high force on top of the screen-printing stencil carrier. The print medium can then with a higher probability also penetrate narrow and narrow recesses and thus reach the substrate to be printed. However, this has the disadvantage that the top of the screen printing stencil carrier wears out in a short time and the life of the screen printing plate is relatively short.

Thus, an object of the invention is to provide a screen printing form with which even narrow printing webs can be reliably produced, wherein the screen printing form has a long service life. It is a further object of the invention to provide a method for producing such a screen printing form.

The objects are achieved by the subject matter of the independent claims. Advantageous developments of the invention are the subject of the dependent claims.

The screen printing form according to the invention comprises: a screen printing stencil carrier, which is designed as a film, which is provided with first

Recesses is provided, which are formed so that they extend from an upper side to the bottom of the film, a screen printing stencil, which is formed as a masking layer, which is firmly connected to the underside of the screen stencil carrier, wherein the masking layer is provided with second recesses, which at least partially coincide with the first recesses of the screen printing stencil carrier in such a way that a printing medium can be conveyed through the first recesses of the screen stencil carrier from its upper side through the second recesses of the masking layer toward the underside and onto a substrate which can be placed underneath, the screen printing stencil carrier and / or the masking layer is / are formed so that a projection projects into the region of at least one of the first or second recess and reduces its passage area for a pressure medium, wherein the height of the projection in the region of the first Ausneh is lower than the height of the screen stencil carrier and / or the height of the projection in the second recess is lower than the height of the screen stencil.

A projection in a recess causes the recess is not reduced over its entire length in its cross-section, but only in a small Area. The recess may be formed wide outside this area, but by the projection but a cross-sectional reduction of the recess for a through this recess to be conveyed through pressure medium is achieved. This allows the production of fine printing webs, although the recess may have a generous cross section except for the projection. The high cost of the exact

Positioning of a screen printing stencil carrier with respect to the screen printing stencil in order to bring at least partially into coincidence a first recess with a relatively small cross section and a second recess with a likewise small cross section thus does not occur. Rather, you can work with conventional manufacturing accuracy. In addition, the force for introducing the pressure medium in a relatively wide recess with a projecting into the recess projection is smaller than in a recess having a continuously small cross-section. In addition, a projection in a screen printing stencil or screen stencil carrier increases its flexural rigidity and tensile strength. As a squeegee moves along the surface of the screen stencil carrier, the screen form is thus less stretched so that its geometry is maintained with greater reliability. Such a screen printing form thus achieves a relatively long service life.

The masking layer may comprise metal and preferably comprise nickel. The masking layer may also be made of photosensitive material. For the

Preparation of such masking layers are, for example, emulsions based on polyvinyl alcohol, capillary films or solid resists.

Preferably, the projection extends along the recess wall, so that a uniform reduction of the passage area and uniform loading of the projection when pushing through the pressure medium can be achieved. The projection then acts like a diaphragm.

Preferably, the projection has a surface with a radius of curvature. The radius of curvature causes in the recess a reduction of the friction resistance of the pressure medium when passing within the recess, so that a pushing through with relatively little effort is possible. If the screen printing stencil has a height of less than 30 micrometers and the projection has a height of 1 to 25 micrometers, the above-mentioned advantages can be realized well. Preferably, the passage area is reduced by the projection by at least 5%.

The screen printing stencil carrier and the screen printing stencil can be formed from metallic materials. The screen-printing stencil can be designed as a masking layer which comprises nickel. Such a material can be easily applied by electrodeposition.

The process for producing the aforementioned screen printing form comprises the steps:

- Providing a substrate

Producing a first mold on the substrate structured plating a first metal layer on the substrate - producing a second mold on the first metal layer

structured plating of a second metal layer on the first metal layer, wherein the first metal layer forms the screen printing stencil carrier and the second metal layer forms the screen printing stencil,

Detaching the first metal layer from the substrate, and removing the first and second molds, whereby first recesses are formed in the first metal layer and second recesses in the second metal layer,

-. wherein the first metal layer is at least partially plated over the first mold and / or the second metal layer is at least partially plated over the second mold to form at least one protrusion.

By the electrodeposition, it is possible to achieve the growth of the projection and a reduction in the cross-sectional area in one step without further structuring. An etching is not required. The galvanic deposition also makes it possible to form a projection, which has an almost arbitrarily small passage area for a recess result. In the limiting case, the projection can even completely close a recess. The formation of the projections has a positive effect on the mechanical stability of the screen printing form since a "T-element" is formed Galvanically produced screen printing forms having the same opening widths and layer thicknesses are far less tensile than the stencil according to the invention with such a "T-element".

Further advantages and features of the invention will be explained with reference to the following figures, in which:

1 shows a cross section of a first embodiment of the screen printing form according to the invention.

Fig. 2 shows a cross section of a second embodiment of the invention

Screen printing form and associated printed substrate;

3 shows a cross section of a device during a method step for producing the screen printing form.

FIG. 1 shows a first embodiment of the screen printing form 1 according to the invention. The screen printing plate has a screen printing stencil carrier 2 and a screen printing stencil 3, which is fixedly connected to the screen stencil carrier 2. The screen printing stencil carrier 2 is provided with first recesses 4 having projections 6 at one end. The projections 6 extend within the recesses 4 and along the wall, so that a uniform reduction in the cross-sectional area of the first recesses 4 is achieved. The first recesses 4 open into a second recess 5, which is provided below the first recesses 4 and within the screen printing stencil 3. The second recess 5 has no projection in this embodiment. The screen printing stencil 3 may comprise metal or be made of a photosensitive material, e.g. from an emulsion layer, a capillary film or a solid resist.

In the embodiment of the invention shown in Fig. 2, a Siebdruckschablo- nenträger 2 is shown with a screen printing stencil 3, which are fixedly connected to each other, wherein the screen printing stencil carrier 2 in a first recess 4 has a projection 6. The screen printing stencil 3, which in this embodiment is higher than the screen printing stencil carrier 2, is provided at one end with a projection 7 which reduces the width 9 of the second recess 5 in such a way that only one passage width 8 is available. If a printing medium 30 is applied to the upper side of the screen printing stencil carrier 2 and introduced into the first recess 4 with a squeegee moved sideways along the upper side, the first recess 4 fills and penetrates to the second recess 5. The cavity available there is also filled with pressure medium 30 and pushed past the projection 7 with the passage width 8 in the direction of the underside of the screen printing stencil 3. In the embodiment of the screen printing plate 1 shown in Fig. 2, the projection 7 is attached to one end of the second recess 5 and has a height 11 which is smaller than the height 12 of the screen printing stencil 3. Further, the projection 7 has a radius of curvature 10, which allows easy removal of the screen form from the printed substrate 20 without damaging the print job 31.

The projection 6 and projection 7 further cause that when removing the screen printing form from the substrate, a portion of the printing medium 30 remain in the first and second recess at the undercuts and only a significantly narrower

Core area remains as a print job 31 on the underlying substrate 20 remains. The projection 7 acts in this embodiment as a scraping edge, so that a very narrow print job can still be achieved at considerable height 13. The ratio of height 13 to passage width 8 of the print job 31 can thus be more than 1: 2, 1: 1 to 2: 1 and is thus significantly above the ratio that can be achieved with electroplated screen printing plates according to the prior art.

In Fig. 3 is shown a cross section of an intermediate product in the production of a screen printing plate. On the substrate 21, a first paint form 14 has been formed, whereupon in a subsequent process step, a first metal layer 15 has been galvanized patterned. The plating process was carried out until the first metal layer 15 had reached a height which was above the height of the first paint mold 14. In this case, the plating process was controlled such that the first metal layer 15 could laterally overgrow on the first lacquer mold 14, see reference numeral 18, whereby individual regions formed with a T-shaped cross-section. Subsequently, a second paint mold 16 was applied to the first metal layer 15 and a second metal layer 17 was electroplated in a structured manner. This plating process was controlled in the same manner as in the first metal layer 15 such that overgrowth of the second Metal layer 17 on the second paint form 16 was carried out. The state after these process steps is shown in FIG.

When the first metal layer 15 and the first paint mold 14 are subsequently separated from the substrate 21 and the first paint mold 14 and second paint mold 16 are removed, first recesses 4 with protrusions 6 and second recesses 5 with protrusions 7 are formed, as shown for example in FIG 2 are shown. The first metal layer 15 can then act as a screen printing stencil carrier 2 and the second metal layer 17 as a screen printing stencil 3.

Claims

claims

A screen printing stencil comprising: a screen printing stencil carrier formed as a film provided with first recesses formed to be separated from one

Range from top to bottom of the film, a screen printing stencil, which is designed as a masking layer, which is fixedly connected to the underside of the screen printing stencil carrier, wherein the masking layer is provided with second recesses which at least partially with the first recesses of

Screen printing stencil carrier are so overlapping that a printing medium through the first recesses of the screen stencil carrier from the top through the second recesses of the masking layer through towards the bottom and on a platzierbares substrate is conveyed, wherein the screen printing stencil carrier and / or the masking layer are formed / in that a projection protrudes into the region of at least one of the first or second recess and reduces its passage area for a printing medium, wherein the height of the projection in the region of the first recess is lower than the height of the screen stencil carrier and / or the height of the screen

Projection in the second recess is lower than the height of the screen printing stencil.

2. Screen printing form according to claim 1, wherein the projection extends along the recess wall.

3. screen printing form according to one of the preceding claims, wherein the projection a

Surface having a radius of curvature.

4. A screen printing form according to claim 2 or 3, wherein the screen printing stencil has a height of less than 30 micrometers and the projection has a height of 1 to 25 micrometers.

5. Screen printing form according to one of the preceding claims, wherein the passage area is reduced by the projection by at least 5%.

6. Screen printing form according to one of the preceding claims, wherein the masking layer comprises metal or is machined out of a photosensitive material.

7. Screen printing form according to one of the preceding claims, wherein the masking layer comprises nickel or Polyvenylalkhohol or consists of a capillary film or a solid resist.

A method of making a screen printing form according to any one of claims 1 to 7, said method comprising the steps of:

Providing a substrate

- Making a first shape on the substrate

- Structured galvanizing a first metal layer on the substrate

Forming a second mold on the first metal layer, patterned plating a second metal layer on the first metal layer, wherein the first metal layer forms the screen printing stencil carrier and the second metal layer forms the screen printing stencil,

- detachment of the first metal layer from the substrate

Removing the first and second molds, whereby first recesses are formed in the first metal layer and second recesses in the second metal layer,

- Wherein the first metal layer is at least partially plated over the first mold and / or the second metal layer is at least partially plated over the second mold to form at least one projection.