WO2001018600A1

WO2001018600A1 - Vacuum copier

Info

Publication number: WO2001018600A1
Application number: PCT/DE2000/002945
Authority: WO
Inventors: Udo Webler
Original assignee: B. Bacher Graphische Geräte Gmbh
Priority date: 1999-09-03
Filing date: 2000-08-28
Publication date: 2001-03-15
Also published as: TW535026B; DE19942213A1

Abstract

Disclosed is a copying device (1) consisting of one rigid body, one spacer and one body which can be deformed under vacuum and which is separated from the rigid body by said spacer, whereby said device can be adapted by reducing the distance therebetween in a contact volume in order to block a pattern master against a pattern receiver. The spacer (3) is equipped with an element which can be extended and retracted between two positions, the regulating distance thereof being at least such that the body which in the first position is only slightly deformable under vacuum and which has a generally spherical shape, is fully adapted to the shape of the rigid body when in the second position.

Description

Title: VACUUMKO p i ERGERAT

Bescnreibung

The present invention addresses the preambles of the independent claims. The invention thus generally relates to the copying of patterns from a pattern generator, for example a film, to a pattern receiver, for example a printed circuit board.

Printed circuit boards are usually produced by placing a film with the conductor pattern over a light-sensitive coated printed circuit board and then performing an exposure through the film. This copying process requires high precision, especially for thin conductor tracks that are close together. It is therefore important that the film lies on the circuit board and that there is no displacement when placed on top of one another or that air bubbles are trapped between the film as the pattern generator and the circuit board as the pattern receiver.

From DE 43 20 792 AI a copying frame for copiers of the graphics industry is known, wherein a film is placed on a copy and this is placed on a rubber blanket supported by a flexible disc (vacuum blanket) and pressed against a glass pane, and with a space between a vacuum is built up on the rubber cover and the glass pane. Here, in the known arrangement between the rubber cover and the glass pane, a circumferential, in particular flexible sealing profile is to be placed on the edge, with a plurality in the edge region of the flexible pane in particular, an aquidistant bore is provided and the bores are functionally connected with a vacuum pump. As a result, the flexible pane with the rubber cover is pressed against the glass pane starting from the axis of symmetry and nestles radially against the glass pane until the maximum negative pressure, deforming the sealing professional, tightly and flatly against the entire cross section of the copied material and the film Glass pane rests.

Further examples of the fixation of sample carriers and receivers against one another can be found, for example, in DE 29 28 320 C2, which describes a mat for a copier frame for exposing photo material that is rigid in its plane with a transparent plate, in particular a glass plate, and one on this under the Exposure to a pressure difference that is printable, flexible and resiliently deformable in its mat with a surface occupied by a plurality of projections.

Furthermore, DE GBM 82 16 678 Ul describes a copying frame with a transparent plate, a flexible plate covering the transparent plate, an elastic sealing strip arranged between the edges of the transparent and the flexible plate, and one on the one of the two plates and the Sealing strip limited space with its suction side connected pump to generate a negative pressure, the flexible plate made of a material with a high modulus of elasticity, in particular made of metal, and is held in one plane over its entire circumference. Reference is also made to FR 2 436 094, SU 1 672 404 A2, DE 30 30 400 AI, regarding a rubber blanket for copying machines, DE GBM 83 11 236 Ul, FR 2 663 133 and de EP 0 457 949 AI. A problem with these previously known devices, in which a contact vacuum is built up between the rigid body and the typically highly flexible and easily deformable body as a rubber blanket in order to fix the film to the printed circuit board, is that an uneven build-up of the contact vacuum does not rule out completely can trap air bubbles. As a result, these lead to inaccuracies in the image and thus a deteriorated resolution.

The object of the present invention is to provide something new for commercial use.

The solution to this task is claimed independently. Preferred embodiments are found in the subclaims.

The invention thus proposes a copying device with a rigid body and a spacer, which separates the rigid body from a reversibly vacuum-deformable body, which can nestle against the rigid body in a contact vacuum while reducing the distance to fix a pattern generator against a pattern receiver, the reversibly vacuum-deformable Body is only slightly flexible and the spacer comprises an element which can be moved in and out between two positions, the travel of the element being at least so large that in the first position the generally spherically curved under the influence of vacuum, but only slightly flexible Body is not conformable to the rigid body and only reaches this in the second position of the spacer or its adjusting element. An essential aspect of the present invention is thus to be seen in the fact that the contact vacuum pressure can be controlled and built up independently of the contact by using a controllably movable element in the spacer, with which the rigid body and the deformable body towards one another and later away from one another can be moved. The time required for fixation is only small, since the contact vacuum can be built up very quickly without air bubbles being trapped. In particular, there is no danger that a body that is too soft, in the event of a sudden contact vacuum pressure build-up, will be moved towards the rigid body so quickly that air bubbles are enclosed. Nevertheless, through the controlled build-up of the contact vacuum. The device of the present invention is thus suitable for a quick, yet very precise fixation.

While the copier can also be used for other areas of the graphics industry, a particularly preferred application is the copying of printed circuit boards, the pattern generator being a so-called master and the printed circuit board being the pattern receiver. With the method according to the invention, conductor track accuracies of up to better than 40 μm can easily be achieved; 38μm accuracy was achieved in a practical example.

The vacuum-deformable body is preferably firmly connected to the pattern generator or is identical to it. It can be provided, for example, to attach a film foil as a pattern generator, in particular by means of a first vacuum, to a plexiglass or glass plate and then to expose it as a vacuum-deformable body together with the plate to a second vacuum, which deforms the plate. alternatives references, the circuit board pattern can be attached directly to the glass body as a so-called glass master.

Typically, the deformability of the vacuum-deformable body only has to be low. It is preferred, for example, if the vacuum-deformable body moves by only 1 mm with a size of 60 x 60 cm. This deformation can easily be achieved with glass plates. It will be appreciated that the maximum deflection in the middle increases correspondingly for much larger plates. However, even with very large glass plates, a maximum deflection of a few, e.g. 3 mm preferred to keep the travel of the retractable and extendable element and thus the pressing times low.

The rigid body can form or represent a vacuum transport frame for a printed circuit board.

While it is possible to use hydraulic or pneumatic piston-cylinder units as a retractable and extendable adjusting element, in a particularly preferred embodiment spindles are provided which can be retracted and extended in a spindle bearing fixed to the housing. A plurality of adjusting elements are typically provided in order to move the rigid body up and down, for example, at all corners. The movement is preferably synchronous, which can be achieved with spindles by moving a toothed belt on the periphery of the glass plate from spindle to spindle in order to actuate all spindles together.

It goes without saying that a preferred, generally parallel movement of the two bodies towards and away from one another is particularly easy with a synchronization of the adjusting elements can be achieved. The actuating elements are preferably designed and / or in particular attached to the housing in such a way that they lower the rigid body onto the stationary body or move it away from it. This is preferred because the vacuum-deformable body is typically formed as a translucent plate and a light source can be provided below the plate. However, it should be mentioned that, if necessary, the transport system can also be replaced by a glass plate, in particular in order to carry out exposure on both sides.

It should be mentioned that protection is also sought for an exposure method according to the invention.

The invention is described below only by way of example with reference to the drawing. In this shows:

1 is a copying apparatus of the present invention which is greatly inflated for purposes of illustration.

According to Fig. 1, generally designated with 1 copying apparatus 1 comprises a rigid body 2, a spacer 3 and a angeorαneten in a housing 4 reversible vacuum-deformable body 5, which is shown ^λ dashed under Vakuumdeformierung a ^¬ withdrawn position than 5.

The rigid body 2 is a transport frame 2 for printed circuit boards known per se, on which a printed circuit board 6 is sucked in via vacuum channels 7. The printed circuit board 6 has to un ^¬ th toward a photosensitive layer. The vacuum channels 7 lead via a vacuum line 8 to a vacuum pump (not shown). The rigid body 2 has supports 9 at its corners, against which the spacers 3 abut.

The spacer 3 is formed with spindles 3a and spindle housings 3b as adjusting elements. A spindle arrangement is provided at each corner of the housing 4. The housing 4 accommodates the spindle housing 3b with the retractable and extendable spindles 3a.

A toothed belt (not shown) runs parallel to and around the plane of the plate 5 between the spindles, being guided close to the wall of the housing 4. The toothed belt is connected to the spindles so that they move in and out due to its movement. The toothed belt itself is in turn controlled by a stepper motor, which receives its control signals from a central system controller (not shown). Furthermore, a lighting arrangement (not shown) is provided, through which the vacuum-deformable body 5 can be illuminated from below.

The vacuum-deformable body 5 is formed from transparent, optically high-quality, streak-free glass and is provided with a circumferential groove 10 which is connected via a vacuum line 11 to a vacuum pump (not shown).

A film 12 is arranged above the vacuum-deformable body 5 and protrudes beyond the vacuum grooves 10.

From the housing 4 away a circumferential sealing profile 13 extends to the rigid body 2 toward provided of rubber having a hermetically abge ^¬ compacted space 15 between the rigid body 2 and the flexible body 5 encloses in any position of the spacer 3, and is sufficiently stable to the Allow generation of a contact vacuum. A vacuum line 14 leads from this hermetically sealed space to a vacuum pump.

Controllable valves are arranged between the openings 8, 14 and 11 and the respective vacuum source.

The arrangement of the present invention operates as follows:

First of all, a printed circuit board 6 is attached to the rigid body 2 by suction via the suction channels 7.

Then a film 12 is aligned on the glass plate 5 and held by suction of air through the line 11 on the grooves 10. The very high flexibility of the film ensures that no air bubbles are trapped.

The spindles 3a of the actuating elements 3 are fully extended and the rigid body 2 is arranged above the spindles in such a way that the supports 9 come to rest on the extended spindles. At the same time, the circuit board 6 is thus arranged above the film 5.

The space 15 is already hermetically sealed by the contact of the sealing profile 13 both on the rigid body 2 and on the housing 4. Air is then sucked out of the hermetically sealed space 15 via line 14. Since the housing 4 and thus the space enclosed by it lies below the vacuum-deformable body 5 at normal pressure, there is a pressure gradient towards the space 15. As a result, the glass plate 5 deforms into its dashed shape 5 ^λ and with the film film 12 fixed thereon. The film film 12, which is vacuum-sucked on the body 5 on the other side, remains stuck regardless of the deformation due to the adnasion. The deformation of the glass plate is greatly exaggerated in the figure. The deformation actually occurring in practice can therefore be achieved quickly since the deformation actually required is only slight.

Due to the extended spacers 3, the spherically deformed glass plate 5 'will only touch the printed circuit board 6 selectively or on a very small area, but will not yet conform to it.

As soon as a static state is reached (or possibly already during the deformation), the

Stepper motor (not shown) actuated to move the toothed belt and thus lower the spindles 3a. This lowers the rigid body 2 lying on them. This continues until the circuit board rests on the spherically deformed glass body 5 ^λ and finally has full-surface, snug contact at least on the surface of the film sheet 12. At this moment the downward movement of the spindles can be stopped and the exposure can then be carried out. There is no danger of air bubbles being trapped between the circuit board 6 and the glass plate 5, since the structure is controlled and results evenly from the center outwards due to the parallel lowering of the spindles.

As soon as the exposure has ended, the hermetically sealed space can be suitably ventilated and the spindles are moved upwards. The exposed circuit board can be removed and the process can be repeated. It should be mentioned that the extended position of the spindles will depend, among other things, on the thickness of the printed circuit boards 6. It should also be mentioned that the spindles are preferably ball-bearing, for example in a ball screw, in order to ensure a uniform movement.

Claims

claims

1. A copying device with a rigid body, a spacer and a vacuum-deformable body separated therefrom from the rigid body, which can nestle against the rigid body in a contact vacuum while reducing the distance to fix a pattern generator against a pattern receiver, characterized in that that the spacer comprises an element which can be extended and retracted between two positions, the travel of which is at least so great that the vacuum-deformable body, which is generally spherically bent in a vacuum under the first position, only fully conforms to the rigid body in the second position.

2. A copying device according to the preceding claim for copying a circuit board pattern from a master to a circuit board, wherein the pattern generator is the master and the circuit board is the pattern receiver.

3. Copying device according to one of the preceding claims, characterized in that the vacuum-deformable body is identical to the pattern generator or is firmly connected to it.

4. Copying device according to the preceding claim, characterized in that the pattern generator comprises a glass or plexiglass plate, on which a film foil can be fixed as a pattern generator, in particular by means of vacuum.

5. Copying device according to the preceding claim, characterized in that the glass or plexiglass plate has a structure, in particular a circumferential groove, via which the film is fixed.

6. Copying device according to one of the preceding claims, characterized in that the vacuum-deformable body is a glass master.

7. Copying device according to one of the preceding claims, characterized in that the vacuum-deformable is only slightly flexible and, in particular under full vacuum, does not bend in the center by more than 3 mm, preferably less than 2 mm, particularly preferably only 1 mm, towards the rigid body.

8. Copying device according to one of the preceding claims, characterized in that the rigid body forms and / or comprises a vacuum transport frame for a printed circuit board.

9. Copying device according to one of the preceding claims, characterized in that the spacer comprises at least one piston-cylinder unit as a retractable and extendable adjusting element.

10. Copying device according to one of the preceding claims, characterized in that the spacer comprises at least one spindle arrangement as a retractable and extendable adjusting element.

11. Copying device according to one of the preceding claims, characterized in that a plurality of spaced adjusting elements is provided.

12. Copying device according to claim 10 and 11, characterized in that for synchronous movement of the Stellele- elements αie spindles are connected to a single drive, in particular a toothed belt.

13. Copying device according to one of the preceding claims, characterized in that the adjusting elements are designed to achieve the distance between the rigid and the flexible body by at least generally parallel movement of one of the two bodies towards and away from each other.

14. Copying device according to one of the preceding claims, characterized in that the adjusting elements are fastened in such a way that they lower the rigid body onto the stationary, flexible body and / or lift it away from it.

15. A method for producing a printed circuit board, characterized in that a printed circuit board pattern is provided on a vacuum-deformable, but only slightly flexible body, opposite the vacuum-deformable body, a rigid body is arranged, the vacuum-deformable body in the direction of the rigid body by applying a deforming vacuum is spherically deformed and the rigid body is then lowered against the deformed surface of the vakuumverfor th body controlled by adjusting a spacer.