DE3705592A1 - Device for the thin coating (lacquering) of disc-shaped substrates for electronic applications, for example circuit boards, Compact Discs, etc. - Google Patents

Abstract

A device for the thin coating (lacquering) of disc-shaped substrates for electronic applications, for example circuit boards, Compact Discs, etc., has a spray device for the coating material which is arranged in a spray chamber which has adjacent to it at least one treatment chamber, in particular drying chamber, for the coated substrates. A continuously driven conveyor for the substrates which runs through the spray chamber and the treatment chamber is designed as a circular conveyor which has a number of carriers which are movable at uniform distances on at least one circular path about a fixed axis, with in each case one support for a horizontally aligned substrate. The outline of each support is smaller than that of a supported substrate such that the carrier can be essentially completely covered by a supported substrate. In addition, the drive devices of the circular conveyor with the associated bearing means and guide means are arranged outside the spray region or shielded with respect to the latter.

Description

The invention relates to a device for thin Coating (varnishing) of disc-shaped substrates for electronic applications, e.g. ladder flat compact disks etc., with a loading layering material fine atomizing and the zer dusted coating material in a spray area conductive evenly on the respective substrate Spray device arranged in a spray chamber net, be with at least one of the spray chamber neighboring treatment - especially drying chamber for the coated substrates, as well as with one through the spray and treatment chamber running, continuously driven conveyor, the one loading and unloading station for the uncoated or the coated substrates is ordered and through which the substrates in hori zonal alignment spaced side by side passing under the spray device through the spray chamber and then through the treatment chamber are transportable. The task and the removal station can be separated from each other or older be natively combined.  

For coating and especially coating of Circuit boards and other disc-shaped sub strate as they are in electronics in the ver a wide variety of embodiments are fully or semi-automatic working systems with this basic principle construction in use. The transportation of the substrates the sprayer is generally done over either by monorails or, especially at small substrates, on horizontal transport tapes. The horizontal arrangement of the transport tapes is generally useful because thereby avoiding that on the substrate still flowable applied in the spray area Coating material, for example the paint, under heavy force flow down the substrate and there with uneven layer thicknesses before it is hardened.

Become endless conveyor belts to transport the substrates used, it can not be avoided that the Conveyor belts in the non-overlying sub covered areas in the spray chamber be contaminated with coating material what to the same extent for spraying chamber lying management facilities of this funding bands applies. They will also take up the substrates the carrier or recordings in an endless conveyor tied upside down from the strand below transported back, with the result that the danger there is excess coating material (overspray) during the return transport to the Substrate contact area can get, with which  next placed substrate is dirty becomes.

A very fine atomization of particles and thus great homogeneity of the applied layer reached with a spray device that one with high speed (20-60,000 rpm) rotating Spray head in the form of an atomizer bell points (iee productronic 29 (1984), No. 10, 30), being an electric field in the spray area is maintained, ty typically a high voltage of up to 100 kV is used.

If the substrates to be coated are non-metallic (semiconductor wafers, ceramic wafers, etc.) or only have very thin metallized surfaces (compact disks), the electrodes that form an electrode for the electric field must be assigned to the ground electrodes, which are located directly below in the spray area the substrate. They can run along with the substrate moved by the conveyor - then they simultaneously form part of the conveyor system - or can be arranged in a stationary manner below the spray device. In the latter case, a thin paper layer or film is used as the conveying element of the conveyor, which slides over the ground electrodes and on which the substrates are placed. This paper layer or film is naturally sprayed together with the substrates in the spray zone; this entails agile cleaning processes if, as is known for paper tapes, a disposable tape is used (GB-PS 11 26 539, FR-OS 25 70 297, WO 86/01 745).

For a profitable coating, especially Be painting of mass products are these devices not suitable.

Even in systems that work with linear conveyors, use the chain-shaped conveying elements, result the explanations for the large number of chain links pollution problems, always the reason additional problem is that the substrate carrier when returning from the lower run on the head be transported upright so that coating material on the substrate support surfaces of the carrier can run.

The object of the invention is therefore a device for thin coating (lacquering) more disc-shaped Substrates for electronic applications create where the risk of contamination of the be moving parts and the substrate support surfaces with excess coating material to a minimum is reduced and still half or full automatic, exact, homogeneous coating, in particular disc-shaped substrates in the context of an economy allowed mass production.

To solve this problem, the above is Device according to the invention characterized in that that the conveyor is a circular conveyor, the one Number at equal intervals to at least a circular path movable around a fixed axis Carrier with one pad each for a horizontal aligned substrate that the outline  each edition a little less than or equal to one placed substrate is such that the carrier by an overlaid substrate is essentially complete can be covered and that the drive devices of the circular conveyor with the assigned bearings and guide means outside the spray area arranged or shielded against this.

Because the carriers with their supports for the substrates with the district conveyor always in the same horizon valley levels are transported horizontally ensured that even when returning the abge no excess coating was emptied from the carrier material can get onto the carrier. By your Pass through the spray chamber are the ones with the Parts of the carrier in contact with substrates completely covered by the substrates themselves, with the result that pollution of the up contact surfaces with coating material excluded is. At the same time, the drive devices of the Circular conveyor with the associated storage and management facilities outside the sphere of influence of atomized coating agent arranged, with what the need for extensive cleaning work not applicable.

In a preferred embodiment, the circle conveyor a number of one around the fixed axis rotatably mounted, coupled with a drive Hub on outgoing arms on which the Carriers are arranged. These arms themselves are ge Insensitive to spraying in the spray zone and do not require cleaning, while on the other hand  a very simple structure of the funding systems in the form of a carousel.

At least two can be on each of the arms Carriers at different distances from the site fixed axis to be arranged around the spray area (Spray cone) better to use. It is also before partial if in the area of the spray chamber below the carrier is a catcher for excess Coating material is arranged, which is more appropriate as can have a drip pan, the edge in a radial direction corresponding to the spray area stood from the fixed axis and to the ge if necessary, suction devices are connected. These Collecting device allows an easy possibility the recovery of the coating material (Re cycling). The collecting device is, for example, via a Siphon connected to a recycling tank. Through the Coating agent consumption can be reused be kept very low. The spray chamber or Spray booth allows air filters to be attached to the top and a largely laminar air flow from above to lead down through the chamber; over the siphon the exhaust air can be removed.

Advantageously, the arms can at least in the Area of the spray chamber by at least one sloping drain surface at least be partially covered to spray them before to protect fog. The arms can also be on her outer ends as a drainage point for excess coating material acting deepest Have point so that orderly, locally be limited running conditions for those who got on their arms result in excess coating material.  

When considering the physical Ge conditions of the substrates (e.g. small wall strength, small weight) is appropriate, the Substrates during the coating and / or the subsequent drying or treatment stationary Any carrier can fix on their carrier a chuck for the have placed substrate. Besides, it can to achieve a very uniform coating small layer thickness may be appropriate if everyone Bearings rotatably mounted about a vertical axis and with a rotation movement around this axis dividing drive is coupled.

For certain substrates, e.g. for compact discs, it is desirable to apply the one applied in the spray chamber To remove the varnish in the edge area again in order To avoid the appearance of paint beads and the like. This can be accomplished in a simple manner by that in the area between the spray and the dry chamber a device for edge removal the coating of the substrates is arranged, the coated substrates from the circular conveyor can be fed in succession.

In addition, the spray chamber can be a tunnel or lock-shaped entry and exit have an opening for the arms through which one in the essential spray-tight sealing of the spray chamber is effected to the outside. So that is safe placed that no coating material mist after can penetrate outside, especially when the  tunnel-like or lock-like inlet and outlet suction devices are connected.

The spray device arranged in the spray chamber can, depending on the coating used material and the type of substrates to be coated an ultrasonic atomizer or an airless Atomizer device or other for the particular Have particularly suitable atomizers for the purpose. A particularly homogeneous coating results if the sprayer is a high speed one rotating spray head and a device for Er Generation of an electric field in the spray area has, the then at least partially metallic supports with their tensioning or holding devices (chucks) as electrodes of the device acting to generate the electric field forms and grounded or with a pole of a high be connected to this device can.

In the drawing is an embodiment of the Subject of the invention shown. Show it:

Fig. 1 shows a device according to the invention in a schematic view and in a plan view,

Fig. 2 shows the device according to Fig. 1, taken along the line II-II of Fig. 1, in a side view;

Fig. 3 shows a compact disk as an example of a substrate to be coated, in a plan view, and

Fig. 4 shows the compact disk of FIG. 3 in cross section in a larger schematic representation, with the layer sequence of polycarbonate support - sputtered metal layer - surface to be painted (from bottom to top), and

Fig. 5 shows a substrate carrier of the device of FIG. 1, with associated clamping or holding device, in a schematic representation, in a side view and on a different scale.

The device shown in the drawing is used in particular for coating substrates in the form of compact disks 1 , one of which is schematically illustrated in Fig. 3, 4. However, it can also be used for coating other disk-shaped substrates, such as semiconductor wafers, printed circuit boards, ceramic substrates, foils and the like, while under a compact disk both CD-DA (compact disk digital audio) CD-ROM ( ie only readable) as well as CD-I (ie interactive, ie readable and writable) data memories can be understood. Each such compact disk 1 consists of an injection-molded or pressed thin polycarbonate disc 50 , which was metallized on one side by sputtering on an aluminum reflective layer 51 in a separate, irrelevant operation and which is coated in the described device with a protective lacquer layer 52 that must. The protective lacquer layer 52 is intended to completely cover the sputtered aluminum layer 51 .

The device has a substantially kastenför shaped rectangular housing 2 , the walls of which are made of sheet metal to shield the electrical field and the wall 3 is divided into a spray chamber 4 and a subsequent drying chamber 5 by a vertical metallic partition. The walls of the spray chamber 4 can be lined with an insulating material (eg polypropylene, Teflon, PVC). In the housing 2 , a circular conveyor designed in the form of a transport carousel 6 is arranged, which is set up on the floor with a base frame 7 . On the base frame 7 is arranged in the region of the partition 3 vertical axis 8, a hub ring 9 rotatably gela gela gerert, which is connected to the axis 8 via spokes 10 .

On the inside of the hub ring 9 , a toothing 11 is arranged, into which a drive pinion 12 engages, which is coupled via a shaft 13 to a drive device 14 accommodated in the lower part 7 , which allows the hub ring 9 , based on FIG. 1 to continuously drive clockwise, as indicated by an arrow 150 .

On the hub ring 9 outwardly projecting arms 15 are attached at equal intervals, which are arranged in the manner shown in FIG. 2 obliquely downward inclined to. On each end of each of the arms 15, a substrate carrier 16 is mounted, which is provided with a plate-shaped, circular-cylindrical receiving disc 17 , which forms a horizontally oriented circular contact surface for a compact disk 1 . The dimensions of the receiving disk 17 and the cylindrical support 16 are selected such that a compact disk 1 placed on a support disk 17 completely covers the support surface and the support 16 upwards. Each of the carriers 16 is attached to the associated arm 15 via a funnel-shaped housing part 18 and a vertical bearing bush 19 ; it can contain a drive device 21 ( FIG. 5) with which the support disc can be given a rotary movement about the assigned vertical axis 22 .

In addition, each of the carriers 16 is provided with a clamping, tensioning or suction device (chuck) for a compact disc 1 which allows the compact disc to be fixed in position on the support disc 17 in such a way that the latter is mentioned Rotating movement of the support plate 17 participates. This clamping or tensioning device in the present case has a number of channels 23 in the receiving disk 17 , which are connected via a suitable distributor device to a vacuum source 24 , which allows the channels 23 to be subjected to a vacuum and thus the compact disk 1 on the support disc 17 to suck.

While in the embodiment shown in Fig. 1.2 From EMBODIMENTS on each of the arms 15, only one carrier 16 is arranged at the end, which at 16 could also be properly made so that each of the arms 15, a plurality, eg. Two carriers 16, a carries, which are arranged at different radial distances from the vertical axis 8 . In any case, but with their centers on a common, concentric to the axis 8 lying circle carrier 17 in the transport carousel 6 are each transported on a common circular path.

The housing 2 has, on its front wall 25 arranged in the region of the service side, has an approximately triangular indentation 26 in cross section, which is delimited by two walls 27 connected to the dividing wall 3 , approximately at right angles to one another. In the walls 27 has an inlet are opening 28 in the spray chamber 4 and an outlet opening 29 from the drying chamber 5 is provided, through which the beam 16 entering from the space formed by the indentation 26 Operation space in the spraying chamber 4 and withdrawn from the drying chamber 5 of can . In addition, the partition 3 has an outlet opening 30 , which allows the transfer of the carrier 16 from the spray chamber into the drying chamber 5 .

The inlet opening 28 and the outlet opening 30 of the spray chamber 4 are each formed with a lock on closing sheet metal channel 31 or tunnel-like, wherein a coating material suction device 32 is connected to the sheet metal channels 31 .

In the spray chamber 4 in the area above the rotating carrier 16 in a vertical plane, a spray device 33 is arranged with a high-speed rotating spray bell 34 , the coating material (varnish) supplied to it finely distributed in a indicated at 35 in Fig. 2 Spray jet down to the discs 17 placed on the compact disk 1 , ie the substrates. The application of the coating material takes place in an electrical field, which is generated between the metallic atomizing bell 34 and the metallic carriers 16 (or the metallic platen 17 ) by the atomizing bell 34 and the metallic hub ring 9 each having a pole one Not further illustrated high voltage source (up to about 100 kV) are connected. For this purpose, the hub ring 9 is grounded at 37 via a slip ring line 36 .

In the spray chamber 4 , a coating medium collecting device is also arranged below the transport path of the carrier 16 , which has a collecting trough 38 which projects radially beyond the spray jet or cone 35 and is connected to a recycling tank 39 , from which the captured liquid coating material is supplied for reuse via pumps and filters not shown. A suction device 32 for coating material mist is connected to the collecting trough 38 .

A fixed to the partition 3 , substantially roof-shaped obliquely downward cover plate 40 covers the arms 15 in the area of the spray chamber 4 up to the area of the carrier 16 ; impinging coating material runs into the collecting trough 38 . The arms 15 are finally formed in such a way that at their ends there is a deepest point acting as a drainage point for excess coating material at 41 .

The device described so far works like follows:

The uncoated compact disks 1 are preferably placed automatically at a feed station A in the region of the indentation 26 on the supporting disks 17 of the carriers 16 passing by and fixed thereon by the clamping and clamping device already described. They then enter through the opening 28 and the sluice-like channel 31 into the spray chamber 4 , where they move under the spray cone 35 in a horizontal orientation and are coated with the coating material. They then leave the spray chamber 14 via the opening 30 and the lock-like channel 31 and enter the drying chamber 5 , in which the coating material applied to the compact disks 1 is brought to harden. The fully coated cured compact discs 1 ver finally leave the drying chamber through the opening 29 and are removed at a removal station B from the carriers 16 after loosening the clamping and clamping device.

The drive and guide devices of the trans port carousel 6 can be seen completely covered by the cover plate 40 and the partition 3 against the action of the coating material in the spray chamber 4 . Excess coating material is collected in the collecting trough 38 and, as already mentioned, supplied for reuse via the recycling tank 39 .

In the area between the spray chamber 4 and the drying chamber 5 , a device, schematically indicated at 42 in FIG. 2, for removing the edge coating of the compact disks 1 can be arranged. Such facilities are known per se and are therefore not described in further detail.

The device described is particularly suitable also for spraying UV curing lacquer. At the Spraying such a paint will not evaporate any solution medium, so that suction devices largely can be omitted.  

Basically, all other types can of paints (including those containing solvents) or Be Layering agents are used.

Since the contact surfaces for the compact disks 1 on the receiving discs 17 and the carrier 16 are completely covered due to their dimensions by the compact disks 1 placed in the support station A , they cannot be contaminated with coating agent when passing through the spray chamber 4 . When treating substrates with a different outline shape, for example rectangular circuit boards, the receiving disks 17 are to be designed accordingly, so that in any case a perfect covering of the support surfaces is ensured by the substrates placed on them.

Claims (17)

1. Device for thin coating (lacquering) of disc-shaped substrates for electronic application purposes, for example printed circuit boards, compact disks etc., with a spray atomizing the coating material and spraying the coating material evenly onto the respective substrate in a spray area, the device is arranged in a spray chamber, with at least one of the spray chamber adjacent treatment, in particular drying chamber, for the coated substrates, and with a running through the spray and the treatment chamber, continuously driven conveyor, which a task and a removal station for the uncoated or the coated substrates is assigned and by which the substrates are horizontally spaced next to each other under the spray device by the spray chamber and then by the loading treatment chamber can be transported, characterized in that the För which is a circular conveyor ( 6 ), which has a number in uniform from on at least one circular path about a fixed axis ( 8 ) movable carrier ( 16 ), each with a support ( 17 ) for a horizontally oriented substrate ( 1 ) that the outline of each edition ( 17 ) is little less than or equal to that of a laid-on substrate ( 1 ), such that the carrier ( 16 ) can be covered completely by a laid-on substrate and that the drive devices ( 12 to 14 ) of the circular conveyor with the associated bearing and guide means ( 8 , 9 ) are arranged outside the spray area or are shielded against it. 2. Device according to claim 1, characterized in that the circular conveyor has a number of a star-shaped outgoing arms ( 15 ) rotatably mounted around the fixed axis ( 8 ), with a drive ( 12 to 14 ) coupled hub ( 9 ) which the carrier ( 16 ) are arranged. 3. Apparatus according to claim 2, characterized in that on each of the arms ( 15 ) at least two supports ( 16 ) are arranged at different distances from the fixed axis ( 8 ). 4. Apparatus according to claim 2 or 3, characterized in that the arms ( 15 ) have at their outer ends a as a drip point for excess coating material deepest point ( 41 ). 5. Device according to one of the preceding claims, characterized in that in the region of the spray chamber ( 4 ) below the carrier ( 16 ) a collecting device ( 38 , 39 ) for excess coating material is arranged. 6. The device according to claim 5, characterized in that the collecting device has a collecting trough ( 38 ), the edge of which extends in a radial distance from the fixed axis ( 8 ) corresponding to the spray area ( 35 ) and connected to the optionally suction means ( 32 ) are. 7. Device according to one of claims 2 to 5, characterized in that the arms ( 15 ) are at least partially covered at least in the region of the spray chamber ( 4 ) by at least one sloping drain surface ( 40 ). 8. Device according to one of the preceding claims, characterized in that each carrier ( 15 ) has a clamping or holding device ( Fig. 4) for the placed on the substrate ( 1 ). 9. The device according to claim 8, characterized in that each carrier ( 16 ) rotatably mounted about a vertical axis ( 22 ) and coupled to it with a rotational movement about this axis issuing drive ( 21 ). 10. Device according to one of the preceding claims, characterized in that in the area between the spray and the drying chamber ( 4 , 5 ) a device ( 42 ) for edge removal of the coating from the substrates ( 1 ) is arranged, the the coated substrates can be fed in succession from the circular conveyor ( 6 ). 11. The device according to one of claims 2 to 7, characterized in that the spray chamber ( 4 ) has a tunnel-like or lock-shaped inlet and outlet opening ( 28 , 30 ) for the arms ( 15 ) through which an essentially spray tight sealing of the spray chamber ( 4 ) is effected to the outside. 12. The apparatus according to claim 11, characterized in that at the tunnel or lock-like inlet and outlet opening ( 28 , 30 ) suction means ( 32 ) are closed. 13. Device according to one of the preceding claims, characterized in that the spray device ( 33 ) has an ultrasonic atomizer. 14. Device according to one of claims 1 to 12, characterized in that the spray device ( 33 ) has an airless atomizer device. 15. Device according to one of claims 1-12, characterized in that the spray device ( 33 ) has a spray head ( 34 ) rotating at high speed. 16. The apparatus of claim 13 or 15, characterized in that the spray device ( 33 ) has a device for generating an electric field in the spray area ( 35 ). 17. The apparatus according to claim 16, characterized in that the at least partially metallic Trä ger ( 16 ) acting as an electrode of the device for generating the electric field He acting and grounded or connected to a pole of a high voltage source of this device.