DE10260802B4 - Screen printing device and screen printing process - Google Patents

Abstract

Screen printing apparatus (1) for printing on a substrate (12) with a printing solution (7) containing at least one volatile solvent
a volume region (17) which is sealed off from the environment by means of a hood (35) and contains a means for producing and maintaining a gas atmosphere which is nearly saturated with the volatile solvent, the volume required for the transfer of the printing solution (7) to the substrate (12 ) responsible parts (5, 10, 15) of the screen printing device (1) in the volume area (17),
- A lock (40) which is tightly connected to the hood (35), and
- A movable substrate holder (15) for insertion and removal of the substrates (12) through the lock (40).

Description

The Screen or stencil printing process is a widely used printing process, that for a variety of imprints, such as pictures or texts on paper, glass plates, plastic carriers or, for example, fabrics is used. Possible is also the pressure of cockpit displays by means of screen or stencil printing. Furthermore, the screen printing process for the production of functional Structures used, for example, for printing printed conductors on boards.

The Screen or stencil printing process provides a through-printing process in which a printing plate, a screen or a stencil is used, in which a pattern to be printed is structured. So, for example in the printing form for the printing solution permeable and non-permeable areas to be available. The printing solution is applied to the printing form and the color transfer is then in the Usually by a squeegee, which moves over the printing form, thereby the printing solution over the Sieve pushes and these through the permeable areas of the printing form hindurchpreßt. At the same time, the printing solution becomes transferred to the underlying substrate. Between the printing form and the substrate is common a small distance of, for example, about 1 mm, the so-called jump, the in screen printing often for one lubrication-free pressure needed becomes. As a printing plate becomes common a printing screen of e.g. Polyester or stainless steel wire mesh used, its mesh size depending from the application of about 700 microns to less than 20 μm can amount.

at many traditional screen printing applications typically use printing solutions the one viscosity have some 1000 mPas and are also thixotropic to one Smearing the printing solution while to prevent the screen printing process. In the case of low-viscosity printing solutions these often by adding additives, for example thixotropic agents or defoamers modified (A. Rombold "Siebdruck and serigraphy ", Ravensburger book publishing 1995; O. Lückert "Pigment and Filler Tables", Lazen 1980).

If the printing solutions volatile or volatile solvent Contain, for example, xylene or toluene, in the sieve or Stencil printing process the problem occur that the stitches of the sieve or the openings of the Template by evaporating the solvent with the solids the printing solution enforce. As a result, the color transfer decreases through the screen onto the substrate to be printed so that fine Structures with increasing length of the Printing process worse resolved become and the surface quality of the printed Layer changes. For this reason, the screens and stencils often decline cleaned every printing. This means a considerable time and cost.

Screen printing devices are for example in the publications US 4,637,308 and JP 2001334631 A described.

It Therefore, the object of the present invention is a screen printing device and to provide a screen printing process which clogs the Reduced pressure and so a faster and cheaper Print enabled.

These The object is achieved by a screen printing apparatus according to claim 1 and a screen printing method according to claim 7 solved. Advantageous embodiments the screen printing device and the screen printing process are the subject of dependent claims.

• – einen mittels einer Haube gegenüber der Umgebung dicht abgeschlossenen Volumenbereich, der ein Mittel zum Erzeugen und Aufrechterhalten einer mit dem flüchtigen Lösungsmittel nahezu gesättigten Gasatmosphäre enthält bzw. der ein Verdunsten des Lösungsmittels verhindert, wobei sich die, für den Übertrag der Drucklösung auf das Substrat verantwortlichen Teile der Druckvorrichtung in diesem Volumenbereich befinden,
• – eine Schleuse, die mit der Haube dicht verbunden ist, und
• – einen beweglichen Substrathalter zum Ein- und Ausschleusen der Substrate durch die Schleuse.

A screen printing apparatus according to the invention for printing a substrate with a printing solution containing at least one volatile solvent comprises

• A volume region which is sealed off from the environment by means of a hood and which contains a means for generating and maintaining a gas atmosphere which is nearly saturated with the volatile solvent or which prevents evaporation of the solvent, the ones responsible for transferring the printing solution to the substrate Parts of the printing device are in this volume range,
• A lock tightly connected to the hood, and
• - A movable substrate holder for insertion and removal of the substrates through the lock.

Under for the carry the printing solution Parts responsible for the substrate become those components the screen printing device, which in the printing process or e.g. involved in the fixation of the substrate to be printed, so for example Squeegee, sieve, screen frame for fixing the screen and printing frame for fixing the substrate to be printed.

Since the responsible for the transfer of the printing solution to the substrate parts are housed in the sealed against the environment volume range, particularly effective evaporation of the volatile solvent is prevented. That is why it is possible with the invent to the screen printing machine according to the invention faster and cheaper to print than conventional Siedruckmaschienen, since between the individual printing operations, the sieve no longer needs to be cleaned of dried printing solution residues.

Of the The area enclosed by the environment contains volume a means for generating and maintaining one with the volatile solvent almost saturated Gas atmosphere. Due to the high partial pressure of the solvent in the saturated gas atmosphere can particularly easy evaporation of the solvent is reduced or be prevented. Under almost saturated in the context of the invention will also be a gas atmosphere understood that the minimum with 80% of the corresponding solvent saturated is. As gas atmosphere can be used for a wide variety of gases and gas mixtures, being common Air-solvent mixtures be used.

to Achieving a high partial pressure of the volatile solvent can withstand the tightly closed volume area with the light-volatile solvent saturated gas atmosphere supplied and discharged again become. Can do this separate inlets and outlets to the tightly closed volume area, for example, can be completed by a hood, provided be. The advantage of this design the screen printing device according to the invention is that, for example in place of a solvent-air mixture also Mixture of the solvent used with inert gases, for example nitrogen or noble gases which minimizes the risk of explosion.

Farther include the for the carry responsible parts of the screen printing device a screen and at least a squeegee, these parts on a printing table for fixation of the substrate to be printed are arranged.

Farther is in an execution the screen printing device according to the invention a hood to complete of the volume range over the one for the carry responsible parts of the screen printing on the printing table available. By means of a hood can be the volume range mentioned above is particularly simple and reliable with respect to Complete the environment. In this embodiment the screen printing device according to the invention are located only the squeegee and the sieve and all others directly on the carry the printing solution involved components of the screen printing device and the printing Substrate under the hood. All other components of the screen printing device, are outside the hood and are not nearly saturated with the volatile solvent gas atmosphere exposed. This variant of the screen printing device according to the invention has the advantage that only completed a relatively small volume range from the environment must become.

A the lock tightly connected to the hood is arranged on the printing table, being movable on the printing table, a substrate holder for on and Outward transfer of the substrates through the lock is present. Then it is very easy, by moving the substrate holder back and forth through the lock Substrates during the printing process into the closed volume area. and out again.

The with the fleeting solvent saturated gas atmosphere let yourself particularly easy to produce in that in the tightly closed volume area a reservoir for the volatile solvent is present for evaporation. Then, due to evaporation of the fleeting solvent from the reservoir particularly easily creates a saturated gas atmosphere become. Furthermore, it is still possible by means of inlets and outlets to the tightly closed volume area, for example, by means attached to the hood supply and discharge lines one with the most volatile solvent saturated Gas atmosphere supply and dissipate again. It also can Inert-solvent mixtures are used, for example, nitrogen or inert gas solvent mixtures, so that a risk of explosion can be minimized.

• A) das Substrat wird über eine Schleuse in einen mittels einer Haube von der Umgebung dicht abgeschlossenen Volumenbereich eingeschleust, der die für den Übertrag der Drucklösung verantwortlichen Teile einer Siebdruckvorrichtung enthält und der eine mit dem Lösungsmittel nahezu gesättigte Gasatmosphäre enthält,
• B) danach wird die Drucklösung auf das Substrat aufgebracht, und
• C) anschließend wird das Substrat über die Schleuse aus dem abgeschlossenen Volumenbereich ausgeschleust.

The invention furthermore relates to a screen-printing method for applying a printing solution containing at least one volatile solvent to a substrate, the printing operation being carried out in a volume region sealed off from the environment, which contains a gas atmosphere which is almost saturated with the solvent, with the following steps:

• A) the substrate is introduced via a lock in a sealed by means of a hood from the environment volume region containing the responsible for the transfer of the printing solution parts of a screen printing device and containing a nearly saturated with the solvent gas atmosphere
• B) then the printing solution is applied to the substrate, and
• C) then the substrate is discharged via the lock from the closed volume area.

In the screen printing method according to the invention, in a method step A), the substrate is conveyed via a lock into a volume sealed off from the environment by means of a hood introduced area, which contains the responsible for the transfer of the printing solution parts of the screen printing device. Thereafter, in a method step B), the printing solution is applied to the substrate by screen printing. Subsequently, in a method step C), the substrate is discharged via the lock from the closed volume area.

advantageously, is the hood with the lock arranged on a printing table, in which case particularly simple in process steps A) and C) the substrate by means of a movably arranged on the printing table Substrate holder on and can be discharged.

• – Lochtransporterpolymere, elektrolumineszierende Polymere und Elektronentransporterpolymere.

Furthermore, the screen printing method can be used for producing an organic, electroluminescent diode, wherein then during the printing process, in particular in method step B) functional layers are applied to the substrate which are selected from the following polymers:

• Hole transport polymers, electroluminescent polymers and electron transporter polymers.

Hole transporters polymers and electron transporter polymers are electrically conductive polymers for example, positive charges ("holes") or negative charges (Electrons) can transport. Examples of hole transporters are materials such as poly-3,4-ethylenedioxythiophene (PEDOT) in question. As electroluminescent polymer can be For example, use poly [2-methoxy, 5- (2'-ethylhexoxy) -1,4-phenylenevinylene] (MEH-PPV). can continue for example, polyfluorenes as electroluminescent polymers be used.

in the The present invention is not intended to be to scale Figures and embodiments be explained in more detail.

The 1A and 1B show in cross-section a screen printing device according to the invention, in which only the components of the screen printing device that are directly involved in the printing process are closed off from the environment by means of a hood.

2 shows schematically in the review an organic, produced by the screen printing process according to the invention, organic electroluminescent display.

1A shows a screen printing device according to the invention during the printing process. In this case, only the components directly involved in the printing process of the screen printing device, ie the squeegee 5 that the printing solution 7 over the sieve 10 distributed, the sieve 10 as well as the substrate to be printed 12 with the on the printing table 20 movably arranged substrate holder 15 under the hood 35 accommodated. By means of the hood 35 attached inlets and outlets 41 For example, a gas atmosphere saturated with the volatile solvent can be added to and removed from the delimited volume range. At the inlet or outlet 41 are schematically drawn arrows that indicate the direction of flow of the solvent-gas mixture. Furthermore, there is a lock 40 tight with the hood 35 on the printing table 20 connected.

1B shows the screen printing device according to the invention according to 1A after completion of the printing process. It is by means of horizontal movement of the substrate holder 15 the printed substrate located thereon 12 through the lock 40 from the saturated volume area saturated with the solvent 17 been discharged. After changing the substrate 12 and its reinsert then the next printing process can be started.

2 shows an organic electroluminescent display produced by means of the screen printing method according to the invention when viewed through a transparent substrate 12 , On the substrate 12 are anode strips in the form of parallel strips 45 present, on the large surface by means of the screen printing process according to the invention a functional layer 7a is applied. Furthermore, insulating bars 50 perpendicular to the anode strips 45 present, which by tearing off a large area vapor-deposited cathode metal film, the cathode strips 55 structure.

In the following, the production of this organic, electroluminescent display will be explained in more detail. On a transparent substrate 12 Indium tin oxide (ITO) is applied and patterned by known methods, for example by means of hydrogen bromide so that electrode tracks 45 with a width of 200 microns and a distance of 30 microns arise. Perpendicular to these ITO anode strips are photoresist webs 50 arranged with overhang for cathode structuring with a distance of 200 microns, a width of 30 microns and a height of 6 microns [F. Steuber "Investigation of the efficiency, color matching and degradation of organic electroluminescent displays", Shaker Verlag 1999]. On a large area a rectangle of an aqueous solution of Lochtranspor age, for example, poly-3,4-ethylenedioxythiophene (PEDOT) is printed with the screen printing process of the invention and then dried for 5 minutes at 300 ° C (layer 7a ). This rectangle is then flashed using toluene as a volatile solvent In the same way, the electroluminescent emitter material MEH-PPV is printed on in the same way by means of the screen printing method according to the invention. During the entire printing process, at least the parts of the printing press that are responsible for the transfer of the printing solution and the substrate to be printed with the substrate holder (see 1A and 1B ) under a saturated toluene atmosphere.

through the screen printing process according to the invention can several of these displays are printed consecutively without the screen while the printing process must be cleaned.

Through a shadow mask can finally on the organic layers 7a large area, the second electrode are vapor-deposited. The metal breaks off at the overhangs of the photoresist webs, the cathode strips being perpendicular to the ITO anode strips 55 be formed. After electrical contacting, the organic material lights green at the crossing points of the anodes and cathodes.

It For example, instead of the hood described here other cover devices, such as chambers possible.

Claims (11)

Screen printing device ( 1 ) for printing on a substrate ( 12 ) with a printing solution ( 7 ) containing at least one volatile solvent, comprising one by means of a hood ( 35 ) relative to the environment tightly closed volume area ( 17 ), which contains a means for generating and maintaining a gas atmosphere which is nearly saturated with the volatile solvent, the pressure for the transfer of the pressure solution ( 7 ) on the substrate ( 12 ) responsible parts ( 5 . 10 . 15 ) of the screen printing device ( 1 ) in the volume area ( 17 ), - a lock ( 40 ), with the hood ( 35 ) is tightly connected, and - a movable substrate holder ( 15 ) for introducing and removing the substrates ( 12 ) through the lock ( 40 ). Screen printing device according to the preceding claim, - in which the parts of the screen printing device which are responsible for transferring the printing solution ( 1 ) a sieve ( 10 ) and at least one squeegee ( 5 ), these parts being mounted on a printing table ( 20 ) are arranged, on which the substrate to be printed ( 12 ) is fixed. Screen printing apparatus according to claim 2, - in which the hood ( 25 ) on the parts responsible for the transfer ( 5 . 10 . 15 ) of the screen printing device on the printing table ( 20 ) is available. Screen-printing device according to one of the preceding claims, - in the tightly closed volume region ( 17 ) a reservoir ( 27 ) is present for the volatile solvent for evaporation. Screen printing device according to one of the preceding claims, - in which with the closed volume area ( 17 ) tightly connected inlets and outlets ( 41 ) are present for the supply and discharge of a saturated with the solvent gas atmosphere. Screen printing device according to one of the preceding claims, - in which a substrate changer for exchanging the substrate ( 12 ) is available. Screen printing process for applying a printing solution ( 7 ) containing at least one volatile solvent onto a substrate ( 12 ), with the following process steps: A) the substrate ( 12 ) is via a lock ( 40 ) into one by means of a hood ( 35 ) volume area sealed tightly by the environment ( 17 ), which contains the parts of a screen printing device which are responsible for the transfer of the printing solution and which contains a gas atmosphere which is almost saturated with the solvent B), after which the printing solution is applied to the substrate ( 12 ), and then C) the substrate is removed from the closed volume area via the lock (FIG. 17 ) discharged. Screen printing method according to the preceding claim, - in which in the closed volume area ( 17 ) the solvent from a reservoir ( 27 ) is evaporated. Screen printing method according to one of claims 7 or 8th, - at in the process steps A) and C) the substrate by means of a on the printing table movably arranged substrate holder on and is discharged. Screen printing process for producing an organic, electroluminescent diode according to one of claims 7 to 9, wherein functional polymers are applied to the substrate during the printing process, which are selected from the following polymers: hole transporter polymers, electroluminescent polymers, and - Electron transporter polymers. Screen printing process for producing an organic, electroluminescent diode according to claim 10, - in which the functional polymers in process step B) on the substrate be applied.