Classifications

• • C—CHEMISTRY; METALLURGY
  • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
  • C25D—PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
  • C25D17/00—Constructional parts, or assemblies thereof, of cells for electrolytic coating
  • C25D17/16—Apparatus for electrolytic coating of small objects in bulk
  • C25D17/28—Apparatus for electrolytic coating of small objects in bulk with means for moving the objects individually through the apparatus during treatment
• • C—CHEMISTRY; METALLURGY
  • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
  • C25D—PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
  • C25D17/00—Constructional parts, or assemblies thereof, of cells for electrolytic coating
  • C25D17/06—Suspending or supporting devices for articles to be coated
• • 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
  • H05K3/22—Secondary treatment of printed circuits
  • H05K3/24—Reinforcing the conductive pattern
  • H05K3/241—Reinforcing the conductive pattern characterised by the electroplating method; means therefor, e.g. baths or apparatus

Definitions

• the invention relates to a method for the precise electrolytic deposition or removal of metals by etching or etching into the edge region of printed circuit boards and foil in continuous systems.
• the quality of the circuit board is determined, among other things, by the layer thickness distribution on the surface and in the boreholes.
• the layer thickness on the surface and in the drill holes in the edge area of a panel differs greatly from the layer thickness on the other surface areas.
• the thickness deviations can have positive as well as negative values.
• the Number of contact clips, their shape and insulation, the quality and quality of the contact surface of the contact clips, the geometry of the anodes and the bending elements as well as the distance of a panel to the next one in the transport direction in the continuous system.
• Document DE 42 05 660 C 1 describes a method for improving the layer thickness distribution in the edge region of workpieces fastened to cathode rails, for example printed circuit boards which are galvanized. Due to the voltage drop in the cathode rail and / or in the workpiece frames, electrical voltage differences occur between adjacent workpieces. These differences in tension cause differences in layer thickness in the edge area of neighboring workpieces. These differences in layer thickness are avoided by temporarily feeding current into the cathode rails and / or into the frames from opposite sides. This compensates for the voltage drop in the rails and racks.
• the optimization of the layer thicknesses on the workpieces does not affect the layer thickness fluctuations in the immediate area of the clamp gripping points.
• EP-A-0 254 030 describes a horizontal continuous system for the electrolytic application of metal to plate-shaped objects, such as printed circuit boards. All-round contact elements in the form of brackets grip the plates. The brackets are used to transport the panels and at the same time to supply the electroplating current. The brackets and thus also the plates have cathodic potential. To avoid clip metallization, the electrically conductive clip is usually provided with an insulating layer except for a small contact area. For electrical and mechanical reasons, the brackets have certain minimum dimensions. Several brackets take advantage of a printed circuit board.
• a disadvantage of this device is that the electrical field in the clamp area is shielded in an unfavorable manner. The consequence of this are large differences in layer thickness in the respective bracket area. Furthermore, the properties of the contact areas, the electrical contact resistance or resistance of the contact areas and the entire current path from the direct current source via lines and screw connections determine the layer thickness. Almost no metal is deposited under a bracket. To do this, excessive copper is deposited between two clamps. These differences could also not prevent a marginal picture. The large layer thickness differences decrease towards the benefit center. The edge area of the circuit board use, in particular from the clamp area, cannot be used for the circuit boards to be cut out. The quality of the adjoining areas is worse than average due to the large fluctuations in layer thickness.
• the width of the non-usable edge area depends on the specified tolerance of the electroplating layer thickness. This tolerance is small, especially in fine conductor technology, which is becoming more and more widespread. In practice, the edge strip width that cannot be used is between 25 and 50 millimeters due to the influence of the clips. Despite the cutting off of this edge area, if several factors come together unfavorably, the differences in layer thickness on the remaining plate can be so great that rejects arise. In addition, cutting off the peripheral areas creates considerable costs. At a transport speed of to
• Example 1 meter per minute and an unusable strip width of 25
• the daily loss in two-shift operation is therefore about 25 square meters.
• DE 1 95 04 51 7 C 1 describes a method and a device for electroplating plate-like items to be treated in horizontal continuous systems.
• the material to be treated preferably printed circuit boards, is gripped by clips.
• the brackets are used for power transmission and for transporting the printed circuit boards.
• the problem underlying the invention is to avoid the disadvantages of the known methods and devices and, in particular, to significantly reduce the differences in layer thickness that occur during the plating process on the printed circuit board and in particular in the area of the clamps, and thus to utilize the usable area with consistently high quality requirements to increase the layer thickness distribution and to significantly reduce the reject rate caused by layer thickness differences in the area near the edge.
• the method according to the invention for the precise electrolytic deposition of metal layers up to the edge area of printed circuit board and foil foil in a continuous system comprises the following method steps:
• the device according to the invention used to carry out the method has
• the contact elements are arranged so that they can take advantage of one or two opposite edge areas.
• the continuous system consists of several system parts arranged one behind the other in the transport direction.
• the contact elements are arranged so that the benefits in different parts of the system can be grasped at different contact gripping points.
• the contact elements are preferably arranged such that they are at equal distances T from one another. As a result, the contact elements always take advantage of the same part of a system.
• This offset V is preferably set to a value which results from the quotient of the distance T between the contact elements and the number of system parts arranged one behind the other.
• the offset can be kept constant by electrical synchronization of the drives of the contact elements in the system parts.
• a control designed in this way is used for the drives of the contact elements in the system parts so that the contact gripping points can be displaced by a predeterminable constant distance V on the use of system part to system part.
• phase position of the rotating contact elements, for example brackets, of each system part can also be adjusted by electrical or mechanical synchronization.
• the distance V of the contact gripping points from system part to system part can be kept constant.
• the drives of the contact elements in the system parts are designed in a corresponding manner.
• the synchronization of the drives is not limited to the electrical synchronization.
• phase synchronization can be implemented in the same way.
• the rotating brackets in each system section are mechanically adjusted in their phase relationship to one another.
• Appropriate mechanical Adjustment points for example in the form of set screws, are provided.
• FIG. 1 Example of the course of the layer thickness in the clamp area, obtained using a method according to the prior art, and a schematic plan view of the associated section of the circuit board use;
• Figure 2 Examples of the course of the layer thickness at the edge of the panel transverse to
• Figure 3 Schematic view of the device according to the invention.
• FIG. 4 Example of the course of the layer thickness in the bracket area with contact gripping points that are simply offset according to the invention and the associated cut-out in plan view;
• FIG. 5 Example of the course of the layer thickness in the clamp area with contact gripping points which are staggered twice according to the invention and a schematic top view of the associated cut-out section;
• FIG. 6 Resulting layer thickness distributions on the edge of the printed circuit board, transverse to the transport direction, according to the examples in FIGS. 4 and 5.
• the course of the layer thickness is on one Printed circuit board or foil use 1 8 shown in the clamp area in the transport direction 1 3.
• absolute layer thicknesses in ⁇ m and a specified tolerance field are entered.
• the distance between the contact gripping points in a continuous system, that is to say the distance between brackets in the transport direction, is also referred to as pitch T.
• FIG. 1 shows the course of the layer thickness 1, obtained using a method and a device according to the prior art.
• Adjacent contact gripping points seize the circuit board benefit 1 8 at locations 2 and 3.
• the diagram of FIG. 1 shows the position of the contact gripping points with the dashed lines 4 and 5. In the vicinity of the contact gripping points, the layer thickness drops to a minimum due to the shielding of the clips and increases to a maximum between the contact gripping points. The tolerance field 6 is far below or exceeded.
• FIG. 2 shows a corresponding course of the layer thickness 7 for the maximum 8 and a corresponding course 9 for the minimum 10.
• the hatched edge strip 1 2 of the circuit board is due to possible over or Falling below the tolerance range up to the limit 1 1 is unusable and must therefore be discarded.
• the device according to the invention is shown schematically in FIG. 3: separate transport members are not shown, provided that the contact elements are not also provided for transporting the panels 1 8 at the same time.
• the system consists of two system parts 1 5 and 1 7.
• the circumferential brackets and the continuous circuit board benefits 1 8 are shown. In the case of a horizontal continuous system, this is the top view. In the event that the benefits are kept vertical, this is a side view. Of course, other configurations are also included inclined use conceivable.
• the direction of transport is shown by arrow 1 3.
• the contact gripping points 1 4 of the first part 1 1 5 are shown as a circle.
• the contact gripping points 1 6 of the second plant part 1 7 are shown as a filled circle.
• the offset V of points 1 4 and 1 6 according to the invention on the printed circuit board panel in this example is half a pitch T.
• the defined displacement of the contact gripping points is achieved by the following measures: All system parts lead to the same distance between the contact gripping points by the same distance of the contact elements in the direction of transport. All system parts produce at the same transport and feed speed for the contact elements. The distance T from one plant part to the next plant part remains constant. Under these conditions, the individual drives 1 9 and 20 run in phase synchronization in the two system sections. The distance between the contact gripping points 0.5 T corresponds to a phase shift of 180 °, which is permanently maintained between the two drives. It is ensured by synchronization of the drives 1 9 and 20 with known means and methods of drive technology. The phase positions are adjusted electrically using the same means and methods.
• FIG. 4 shows how the defined thickness V of the contact gripping points 1 4 and 1 6 levels the course of the layer thickness 21.
• the layer thickness minimum 1 0 is raised, the maximum 8 is lowered.
• the tolerance field 6 shown as an example is still exceeded or fallen below.
• FIG. 5 shows the course of the layer thickness 22 with three continuous system parts connected in series.
• the contact gripping points of the first and second system parts are again denoted by 1 4 and 1 6 and those of the third by 23.
• the tolerance range is not exceeded or not fallen short of, because of the more frequent change of the contact elements minor fluctuations occur during the transfer from one system part to the next and due to the respective exposure of the previously covered contact gripping points.
• the areas of the plate or film surface previously shielded as contact gripping points can be metallized in subsequent system parts.
• the layer thickness profiles 25, 26 and 27, 28 are shown transversely to the direction of transport, as they result from the methods according to FIGS. 4 and 5.
• the representations are comparable to the representation in FIG. 2 to scale.
• the position of the contact gripping points on the printed circuit board 1 8 is marked with the arrow 24.
• the layer thickness profiles 25 and 26 in the two figures apply to the maximum 8 and to the minimum 1 0 for two system parts connected in series.
• the courses 27 and 28 apply accordingly to three system parts.
• the associated limits 29 and 30 for the usable area of the printed circuit board use 1 2, in which the layer thicknesses obtained still fall within the specified tolerance range, are shown in FIG. 6.
• the device can also be used for removing or thinning of metals by electrolytic etching ⁇
• the purpose be provided measures are different from the above-mentioned plating method and by the apparatus characterized in that the polarity of the electricity supply to the Contact elements and benefits on the one hand and to the counter electrodes (cathodes instead of anodes) on the other hand are reversed.

Landscapes

• Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Electrochemistry (AREA)
• Materials Engineering (AREA)
• Metallurgy (AREA)
• Organic Chemistry (AREA)
• Manufacturing & Machinery (AREA)
• Microelectronics & Electronic Packaging (AREA)
• Electroplating Methods And Accessories (AREA)
• Manufacturing Of Printed Wiring (AREA)

Applications Claiming Priority (3)

Publications (1)

Family

ID=7815516

Family Applications (1)

Country Status (6)

Families Citing this family (2)

Family Cites Families (5)

• 1996
  • 1996-12-20 DE DE19653272A patent/DE19653272C1/de not_active Expired - Lifetime
• 1997
  • 1997-12-10 JP JP52822298A patent/JP3891593B2/ja not_active Expired - Lifetime
  • 1997-12-10 CA CA002275261A patent/CA2275261A1/en not_active Abandoned
  • 1997-12-10 US US09/331,099 patent/US6186316B1/en not_active Expired - Fee Related
  • 1997-12-10 EP EP97953640A patent/EP0946794A1/de not_active Withdrawn
  • 1997-12-10 WO PCT/DE1997/002945 patent/WO1998028468A1/de not_active Application Discontinuation

Non-Patent Citations (1)

Also Published As

Similar Documents

Legal Events