Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B65—CONVEYING; PACKING; STORING; HANDLING THIN OR FILAMENTARY MATERIAL
  • B65G—TRANSPORT OR STORAGE DEVICES, e.g. CONVEYORS FOR LOADING OR TIPPING, SHOP CONVEYOR SYSTEMS OR PNEUMATIC TUBE CONVEYORS
  • B65G47/00—Article or material-handling devices associated with conveyors; Methods employing such devices
  • B65G47/22—Devices influencing the relative position or the attitude of articles during transit by conveyors
  • B65G47/24—Devices influencing the relative position or the attitude of articles during transit by conveyors orientating the articles
  • B65G47/248—Devices influencing the relative position or the attitude of articles during transit by conveyors orientating the articles by turning over or inverting them
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
  • B05C—APPARATUS FOR APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
  • B05C13/00—Means for manipulating or holding work, e.g. for separate articles
  • B05C13/02—Means for manipulating or holding work, e.g. for separate articles for particular articles
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
  • B05C—APPARATUS FOR APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
  • B05C9/00—Apparatus or plant for applying liquid or other fluent material to surfaces by means not covered by any preceding group, or in which the means of applying the liquid or other fluent material is not important
  • B05C9/04—Apparatus or plant for applying liquid or other fluent material to surfaces by means not covered by any preceding group, or in which the means of applying the liquid or other fluent material is not important for applying liquid or other fluent material to opposite sides of the work
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
  • B05D—PROCESSES FOR APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
  • B05D1/00—Processes for applying liquids or other fluent materials
  • B05D1/30—Processes for applying liquids or other fluent materials performed by gravity only, i.e. flow coating
• • H—ELECTRICITY
  • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
  • H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
  • H05K13/00—Apparatus or processes specially adapted for manufacturing or adjusting assemblages of electric components
  • H05K13/0061—Tools for holding the circuit boards during processing; handling transport of printed circuit boards
• • H—ELECTRICITY
  • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
  • H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
  • H05K3/00—Apparatus or processes for manufacturing printed circuits
  • H05K3/0091—Apparatus for coating printed circuits using liquid non-metallic coating compositions
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
  • B05D—PROCESSES FOR APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
  • B05D2252/00—Sheets
  • B05D2252/10—Applying the material on both sides
• • H—ELECTRICITY
  • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
  • H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
  • H05K2203/00—Indexing scheme relating to apparatus or processes for manufacturing printed circuits covered by H05K3/00
  • H05K2203/15—Position of the PCB during processing
  • H05K2203/1509—Horizontally held PCB
• • H—ELECTRICITY
  • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
  • H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
  • H05K2203/00—Indexing scheme relating to apparatus or processes for manufacturing printed circuits covered by H05K3/00
  • H05K2203/15—Position of the PCB during processing
  • H05K2203/1563—Reversing the PCB
• • H—ELECTRICITY
  • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
  • H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
  • H05K2203/00—Indexing scheme relating to apparatus or processes for manufacturing printed circuits covered by H05K3/00
  • H05K2203/15—Position of the PCB during processing
  • H05K2203/159—Using gravitational force; Processing against the gravity direction; Using centrifugal force

Definitions

• the subject of the invention is a process and apparatus for continuously coating both sides of plate- shaped workpieces, particularly printed circuit boards, with liquid coating material, in which process the workpiece is first transported through a coater and coated on the first side. Then the workpiece is turned over 180°, passed through the same coater, and coated on the second side.
• WO 87/045 84 discloses a process and equipment for coating both sides of printed circuit boards with liquid coating material.
• the printed circuit board to be coated is placed on a mobile transporting apparatus or on a transporting carrier and clamped thereon at the edges.
• the transporting carrier with the attached printed circuit board is first passed through the coater, turned over 180° in a turning apparatus, and passed a second time through the same coater to coat the back side of the printed circuit board.
• JP 63-134449 discloses a turning apparatus whose rotation axis is similarly oriented perpendicular to the transport direction. When this apparatus is used in a coater installation through which the printed circuit board is passed twice, the same disadvantages arise as with the equipment in WO 87/045 84.
• DE-OS 17 52 079 discloses a process and apparatus for inking both sides of plates. The plates are first passed on roller conveyors through an apparatus with ink rollers to ink one side of the plates. After passing through a dryer, the plates are reversed and passed to a turning apparatus. Because the plates are tilted in the turning apparatus, a second roller conveyor must be applied to the plates to hold them in place.
• the plates are then pivoted upward on a circular path around the rotation axis of the turning apparatus and conveyed to the inking rollers a second time.
• the same edge leads in the transport direction as in the first pass through the inking rolls. Because printed circuit boards are dried only after the second pass through the coater, this turning apparatus is not suitable for coating printed circuit boards. Travel on a circular path generates acceleration forces acting in the plane of the plates, causing flow in the still liquid coating material.
• the problem involved in the invention is devising a process to coat both sides of plate-shaped workpieces so that a finished coating on one side is not damaged and coater contamination is largely avoided.
• Another problem involved in the invention is making available a coating installation for performing the process and a turning apparatus that can be used especially advantageously in a coating installation.
• the present invention is directed to a process and apparatus employed therein for continuously coating both sides of plate-shaped workpieces, particularly printed circuit boards, with liquid coating material in which process the workpiece is first transported through a coater and coated on one side, and the workpiece is then turned over 180°, passed through the same coater, and coated on the second side, characterized in that, during transport and turning, the workpiece is transported on punctate supports, the workpiece is turned over on an axis lying in the direction of transport, and the workpiece is passed backward through the coater to coat the second side.
• Figure 1 is a side view of one embodiment of the turning apparatus with a curtain coater.
• Figure 2 is a top view of the apparatus shown in Figure 1,
• Figure 3 is a front view of the apparatus shown in Figure 1
• Figure 4 is a perspective view of a rail with knife-edge disks.
• Figure 5 is a a rail with knife-edge disks and V- shaped angle pieces.
• Figure 6 is a partial side view of the apparatus shown in Figure 1 in another embodiment.
• FIG. 7 is a schematic representation of the conveyor rollers in another version.
• Figure 8 is a side view of the turning apparatus in another embodiment.
• punctate supports supports having minimum bearing areas in contact with the object being supported
• punctate support does not damage a coated surface, because the coating material after application generally has such surface tension and viscosity that the punctate contact sites heal spontaneously. Punctate supports become contaminated less than, for example, rollers or holding clamps, so that the intervals between cleaning the coater are distinctly longer than for conventional equipment.
• the workpiece coated on one side is turned over around an axis lying in the transport direction.
• This alignment of the rotation axis offers the advantage that the acceleration forces acting on the workpiece during the turn, as opposed to the version in DE-OS 17 52 079, are directed essentially perpendicular to the surface of the plate, so that the surface coated with still liquid material is not damaged.
• aeration can be continued during and/or after turning to eliminate solvents. In the case of less sensitive coating materials, aeration can be performed only during the turn.
• Warming the workpiece during and/or after turning may also be advantageous if the workpiece must always have the same temperature during coating.
• a turning apparatus that can be used with particular advantage together with a single coating station is characterized in that the rotation axis of the turning apparatus coincides with the axis of the workpiece lying in the transport direction, the second conveyor section is horizontal, and at least the second conveyor section located in the turning apparatus has punctate supports bearing the workpieces on both sides. Additional facilities for holding the workpiece are unnecessary, because the workpiece cannot slide out of the conveyor section during the turn.
• the punctate supports in the conveyor are knife-edge disks arranged next to each other in the transport direction, with the workpiece to be transported being supported on its edges area. Because the workpiece should be on the punctate supports after the workpiece has been turned over, the disks are located in the turning apparatus not only next to each other but also one above another to form double tracks so that the workpiece is guided between the disks. In addition, guide bars can be provided between the disks to keep the workpiece from falling out. When the rotation speed of the turning apparatus is high enough that the pressure exerted by the punctate supports on the workpiece overcomes gravity, the guide bars can be omitted.
• knife-edge disks offers the advantage that the bearing area on the workpiece is minimized.
• the bearing area of the knife-edge disks is so small that after the coated workpiece is removed, the coating material, because of its residual flow capability, can spontaneously heal the bearing points so that no coating damage can be detected on the finished and dried workpiece.
• rollers with a V-shaped cross section.
• Plate-shaped workpieces lie with at least one edge on one of the V- shaped areas of these rollers thus assuring punctate support. Additional guide bars are unnecessary in this embodiment.
• the rollers or disks can be either rotated by a suitable drive or mounted for free rotation.
• the conveyor is provided with rods that push the workpiece to be treated and accelerate it to a given speed.
• the first conveyor section has a first push rod that is positioned between the knife-edge disks or rollers located on the sides and that can move back and forth in the transport direction.
• the first push rod contacts the workpiece at its rear edge and pushes the workpiece into the turning apparatus where the workpiece is braked and positioned in the second conveyor section.
• the workpiece can be braked by having V-shaped angle pieces instead of rollers or disks at the end of the second conveyor section into which the workpiece enters and is braked.
• a second push rod is located in the second conveyor section.
• the second push rod When the plate-shaped workpiece enters the turning apparatus, the second push rod is retracted and serves as a stop for the incoming plate. After the plate is turned over, this push rod is actuated, contacts the front edge of the plate, and pushes it at a given speed out of the turning apparatus. To prevent damage to the workpiece during braking and accelerating, the contact end of each push rod is furnished with a shock-absorber.
• the two push rods can be connected with one another advantageously by a frame so that a common drive can be provided for both push rods.
• the first conveyor section can be lowered on one side to form a drop zone during transport from the turning apparatus, so that the workpiece can slide out under the first push rod and be removed. In this case, it is unnecessary to raise the first push rod.
• the drop zone facilitates more rapid removal of the workpiece.
• the two conveyor sections can also be equipped with rotating belts having pins.
• Two pin belts are located one above the other corresponding to the configuration of the knife-edge disks in the turning apparatus, so that the workpiece is guided between these pin belts in the turning apparatus.
• the turning apparatus is cylindrical with a front and a rear wall between which the second conveyor section is located. These walls are mounted on roller bearings and are rotated by a drive around the axis of rotation to turn the workpiece over.
• the front wall has an opening for inserting and removing the workpiece to be turned. Brushes may also be mounted on this front wall to clean the pin belts during rotation.
• the turning apparatus can also have only one wall, preferably the front wall, on which the second conveyor section is flange-mounted projecting freely.
• the rollers are mounted either individually or in groups on a replaceable rail. These rails can be easily interchanged manually and placed in a cleaning solution.
• the turning apparatus preferably also has an air exhaust apparatus and/or a heating apparatus.
• the turning apparatus of the invention is preferably used together with a coater, especially a curtain coater, to form a coating station.
• the coater in this case is preferably located between the turning apparatus and the first conveyor section.
• the workpiece to be treated is placed first on the first conveyor section and forwarded at a given speed through the curtain coater. Then the workpiece coated on one side reaches the second conveyor section in the turning apparatus. In passing through the coater, the leading edge of the workpiece is necessarily also coated. However, this is not a problem if the workpiece does not present the same leading edge during the second pass through the curtain coater.
• the invention's turning apparatus assures this by the rotation axis of the turning apparatus being in the transport direction. After the workpiece coated on one side is turned over, it is moved out of the turning apparatus backward so that now the rear edge is passed first through the coater. This assures that the edges of the workpiece being treated are overloaded with coating material, thus avoiding excess coating material dripping on the conveyor.
• Figure 1 shows a side view of the cylindrical turning apparatus 1.
• the front wall 14 and the rear wall 15 are circular and are mounted rotatably on a base plate 11.
• the rear wall 15 is driven by a motor 12 that rotates the turning apparatus 1 around the rotation axis 22.
• the front wall lies on a roller bearing 13.
• Located between the walls 14, 15 is the second section 3b of the conveyor 2 formed by rails 6, on whose side knife-edge disks 5 are positioned parallelwise next to one another.
• the distance between the upper and lower row of the knife-edge disks 5 in each case is matched to the thickness of the workpiece 4 being turned.
• guide bars are located on the side in the area between the rails 6 to prevent the workpiece from falling out during turning.
• the first section 3a of the conveyor 2 is positioned before the turning apparatus 1 and is also equipped with rails 6 fitted with knife-edge disks 5.
• the conveyor 2 has a first push rod 7 on the contact end of which is a shock absorber 9 that, in the embodiment shown in Figure 1, contacts the rear edge of the workpiece 4.
• the push rod 7 is moved in the direction of the arrow to insert the workpiece 4 in the turning apparatus 1, so that the workpiece 4 is accelerated to a specific given speed that the workpiece attains upon exiting the first conveyor section 3a.
• the workpiece 4 then passes into a curtain coater 17 located in the open space between the first conveyor section 3a and the turning apparatus 1.
• the liquid coating material flows down from the coater 17 forming a coating curtain 18 which is collected in a supply container 19.
• the workpiece moves through the coating curtain 18, has its top side coated, and then passes into the turning apparatus 1.
• the workpiece 4 is received on the knife-edge disks 5 of the second conveyor section 3b and forwarded.
• the workpiece 4 is intercepted and braked by a second push rod 8 located in the second conveyor section 3b.
• V-shaped angle pieces or metal sheets 23 instead of knife-edge disks 5 may be located for braking in the end segment 30 of the second conveyor section 3b, as shown in Figure 5.
• the turning apparatus 1 rotates 180° around the rotation axis 22 that coincides with the longitudinal axis of the workpiece .
• the second push rod 8 with the shock absorber 10 on its contact end moves into the turning apparatus 1 and accelerates the workpiece 4 back to the given speed at which the workpiece 4 then moves a second time through the coating curtain 18 to coat the back side.
• the incoming workpiece 4 is braked in the region of the first conveyor section 3a by the push rod 7 and the shock absorber 9. It is also possible to lower the conveyor section 3a from position A to position B so that the first conveyor section 3a forms a drop zone and the plate 4 passes under the push rod 7.
• the plate 4 is then received by another conveyor not shown and transported for further processing.
• the latter conveyor must also receive the workpieces without touching the surface.
• V-shaped arms or roller tracks contacting only the plate edges may be used, in which case support is provided either between the conveyor rails or at right angles to them on the leading and trailing plate edges.
• Figure 2 shows a top view of the apparatus of Figure 1 with the coater 17 omitted.
• the rails 6 with the knife-edge disks 5 are spaced so that the edges of the plate 4 are on the knife-edge disks 5.
• the two push rods 7 and 8 are connected together by a common frame 21 with a common drive 20 that moves the push rods back and forth in the direction of the arrow.
• Figure 8 shows another embodiment of the turning apparatus 1.
• An especially compact configuration is achieved if only one round front wall 14 is provided on which the rails 6 and the guide bars 31 are each attached as an integral component on flanges.
• the back wall can thus be omitted.
• the frame connecting the push rods 7 and 8 is located above the conveyor sections 3a and 3b.
• Figure 3 shows a front view of the turning apparatus 1.
• the round front wall 14 has an opening 27 through which the workpiece 4 is inserted into and removed from the turning apparatus 1.
• the guide bars are located between the rails 6.
• FIG. 4 shows another embodiment of the turning apparatus 1.
• the rails with knife-edge disks are replaced by pin belts 24 with pins 25 pointing toward workpiece 4.
• the belts rotate on guide rollers driven by a motor (not shown) .
• the pins 25 have pointed tips to assure punctate support of the workpiece 4.
• the second conveyor section 3b in the turning apparatus 1 has two conveyor belts 24 arranged one above the other for each edge with the pin spacing adjusted to the thickness of the plate 4 being turned.
• V-shaped rolls 26 are provided for the conveyor sections 3a and 3b.
• V-shaped rolls 26 offer the advantage that the workpiece is supported only on one edge 28. Instead of two rows of knife-edge disks arranged one above the other for each edge in the turning apparatus, only one row of V-shaped rolls 26 is necessary, because after the turn, the support area of the V-shaped rolls 26 merely changes.
• the turning apparatus 1 can also have added accessories.
• an air exhaust apparatus 16 is provided above the conveyor section 3b so that intermediate drying of a plate already coated on one side can be performed during the turning process.
• a heating apparatus 29 is provided in the turning apparatus 1 as illustrated schematically in Figure 6.

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• Engineering & Computer Science (AREA)
• Manufacturing & Machinery (AREA)
• Microelectronics & Electronic Packaging (AREA)
• Mechanical Engineering (AREA)
• Coating Apparatus (AREA)

Applications Claiming Priority (2)

Publications (1)

Family

ID=6426640

Family Applications (1)

Country Status (2)

Cited By (19)

Families Citing this family (6)

Citations (6)

• 1991
  • 1991-03-07 DE DE19914107224 patent/DE4107224C1/de not_active Expired - Fee Related
• 1992
  • 1992-03-09 WO PCT/US1992/001941 patent/WO1992015403A1/en active Application Filing

Patent Citations (6)

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