JP5905101B2 - Method for processing a plastic substrate and apparatus for at least partially regenerating a processing solution - Google Patents

Description

  The present invention relates to a method for treating, in particular etching, plastic substrates, in particular printed circuit boards and printed circuit foils, having the features of the independent claim 1 of the method with a treatment solution comprising permanganate. The present invention at least partially comprises a processing solution comprising permanganate used for processing and / or etching plastic components, in particular printed circuit boards and printed circuit foils, having the features of device independent claim 8. The present invention also relates to a device for playing back.

BACKGROUND OF THE INVENTION Treating or etching plastic molded parts or plastic substrates such as printed circuit boards or printed circuit foils with solutions containing permanganate is often a preliminary step for metallization of the substrate surface or bore. Done. Thus, the substrate is brought into contact with a suitable processing solution in a processing tank of a dipping machine or tunnel machine in a horizontal transport direction, and the temperature of the solution may be from 50 ° C. to approximately 100 ° C.

  EP 1657324 discloses a method for metallizing an insulating or non-conductive substrate by etching with an etching solution, in this case the concentration for roughening and metallizing the surface of the substrate. Temperature and time are controlled.

  Such processing solutions lose processing properties when used for long periods of time and therefore must be replenished regularly or fully or partially replaced, thus increasing costs.

  A first object of the present invention is to process, particularly etch, plastic substrates, particularly printed circuit boards and printed circuit foils, using a treatment solution containing permanganate, which allows for extended use of the treatment solution. Is to provide a method. A second object is to provide an apparatus for the regeneration of treatment solutions that is effective and cost-effective to achieve the object of the method.

These objects can be achieved by the subject matter of the independent claims. Advantageous preferred embodiment features of the invention result from the subclaims. In order to achieve the first object, the present invention proposes a method of treating, in particular etching, plastic molded parts and in particular plastic substrates such as printed circuit boards and printed circuit foils with a treatment solution containing permanganate. . It is intended by the present invention that the carbonate concentration based on sodium carbonate Na ₂ CO ₃ is set to the desired value of the carbonate compound in the processing solution in the dissolved state by removing the carbonate compound from the processing solution. Has been. The dissolved carbonate compound is now converted to a solid by freezing and then removed from the treatment solution by filtration. Filtration in the context of the present invention should be understood as a process in which solid particles are removed from solution.

  The desired value is set at a value of less than 200 g / l in the present invention, preferably the carbonate compound concentration in the treatment solution for the process is set at a value of 30-150 g / l, more preferred. In the treatment solution, the concentration of the carbonate compound is set to a value of 50 to 100 g / l. Carbonate is a reaction product generated by the reaction of the treatment solution with the plastic substrate.

  Freezing of the carbonate compound can be achieved by transferring the processing solution completely or partially to the cooling tank and then cooling the processing solution in the cooling tank. Thereafter, the carbonate can be removed from the solution by filtration by transferring the cooled and frozen treatment solution containing carbonate from the cooling tank to a downstream filtration device.

The treatment solution contains sodium permanganate to remove the carbonate compound from the treatment solution by freezing and subsequent filtration. The proportion of permanganate in the treatment solution consists of more than 50% sodium permanganate (Na ₂ MnO ₄ ).

  In the method of the present invention, the freezing of the carbonate compound is particularly achieved by cooling the treatment solution to a freezing temperature of -12 ° C to + 12 ° C, preferably -9 ° C to + 10 ° C, more preferably -7 ° C to + 5 ° C. Can be done.

  The method of removing the carbonate can be performed such that the regenerated permanganate solution having a processing temperature of, for example, 50 ° C. to 98 ° C. is transferred from the processing tank to the cooling tank. The solution can in this case pass through one or two precoolers. In the cooling tank, the solution is cooled to a freezing temperature, ie, a temperature below 0 ° C., whereby solid carbonate crystals are formed in the solution as a result of the low temperature. After reaching the freezing temperature, and possibly after an additional waiting time after reaching the freezing temperature, the solution containing the carbonate crystals is completely or more preferably partially transferred from the cooling tank to the filtration device. Moved. There, the crystals are filtered and possibly held by the negative pressure provided to the filter. The filtrate can be returned to the processing tank, where it can pass through one of the precoolers, thereby automatically heating the filtrate again. The filter cake formed by the carbonate crystals can be rinsed from the filter and converted to waste water.

  Another advantageous embodiment of the method includes, in addition to the method described above, that an electrolytic permanganate regeneration of the treatment solution is achieved, for example as described in WO 2001/90442. Manganate produced by the reaction of permanganate in the treatment solution in the treatment tank with the plastic substrate is converted back to permanganate by anodization by contacting the treatment solution with a suitable electrolytic cell. In particular, at least one such combination of the method of the present invention for setting a specific carbonate concentration in a treatment solution by electrolytic permanganate regeneration can increase the efficiency of permanganate regeneration, An improved longer life of the solution can be achieved.

  A second object of the present invention is to at least partially render a treatment solution comprising permanganate by reducing the concentration of carbonate compound contained in the treatment solution in order to carry out the claimed method. This is accomplished by providing an apparatus for playback. Thereby, the apparatus has at least one cooling tank for providing a regenerated processing solution, the cooling tank further comprising a cooling device directed to the cooling tank and from the processing solution It has a downstream filtration device for separating carbonate compounds.

  The filtration device can have at least one filter tank and one filter, for example a filter strainer. The filter tank can be connected to a negative pressure device to increase the differential pressure in the filter during filtration, thereby achieving faster filtration.

  The filter in the filter tank can be movably arranged, for example tiltable or rotatable, to facilitate cleaning of the filter.

  The apparatus of the invention according to one of the embodiments of the invention is suitable for carrying out a method according to one of the method embodiments of the invention.

  In the following, exemplary embodiments of the invention exemplify the invention and its advantages in more detail on the basis of the accompanying drawings in particular. The dimensional ratios of the individual elements in the drawing do not correspond to the actual ratios. This is because some shapes are shown in a simplified manner, while others are shown in an enlarged ratio relative to other elements for better visibility.

1 shows an embodiment of the present invention, in which an apparatus is provided for the regeneration of a processing solution used to process, eg etch, plastic parts such as printed circuit boards. 2 shows a schematic view of a cleaning unit of the apparatus according to FIG. 3 shows a schematic view of a filter unit that is part of the filter device according to FIGS. 1 and 2.

  The same reference numerals are used for the same elements of the invention or elements that perform the same function. The illustrated embodiment is merely an example of how the apparatus and method of the present invention would look, and does not show any consequential limitations.

  The schematic diagram of FIG. 1 shows one embodiment of the apparatus 10 of the present invention for at least partially regenerating a processing solution 12 containing permanganate in a processing tank 14. The processing tank 14 is used for processing a plastic substrate, for example, etching. The apparatus 10 reduces the concentration of the carbonate compound in the treatment solution 12. The device 10 includes a cooling tank 16 and a downstream filter device 20 as essential elements. The processing solution 12 to be regenerated is transferred from the processing tank 14 to the cooling tank 16, and a cooling device 18 is provided for the cooling tank 16. The cooling device 18 is a treatment solution in the cooling tank 16 through one of the heat exchangers through which the coolant flows, and more preferably through a cooling jacket 19 provided around the cooling tank 16. To provide low temperature. The discharge part 35 of the cooling tank 16 is connected to the filter device 20 for separating the solid carbonate compound separated from the processing solution.

  For example, a precooler 22, which can be designed as a heat exchanger, can be installed between the processing tank 14 and the cooling tank 16, thereby precooling the regenerated processing solution 12 sent to the cooling tank 16. Alternatively, the cooled and regenerated treatment solution 12, ie the filtrate or rinse water of the filter device 20, can be used.

  The filter device 20 can be connected to a negative pressure unit 24 that facilitates separation of the solid portion from the processing solution. It has been found that significantly higher amounts of carbonate crystals can be filtered if the filtration process occurs quickly. The provision of the negative pressure unit 24 results in a significantly greater differential pressure in the filter for filtration, which allows a significantly faster filtration. To remove the sticky permanganate, the filter cake containing the filtered carbonate crystals can be rinsed using the flushing device 28. The resulting rinse aqueous solution can be transferred to the treatment tank 14. While the filter cake is rinsed from the filter by the flushing device 28, the resulting solution or sludge can be conveyed via the drain 26 to the drain. The filtrate produced in the filter device 20, ie the regenerated process solution, is preferably transferred to the process tank 14 and returned. Accordingly, the regenerated processing solution flows through the precooler 22, where the regenerated processing solution is automatically heated again, and the processing solution transferred from the processing tank 14 to the cooling tank is cooled. .

The cooling tank 16 is preferably provided with, for example, an electric stirring device 32, which has a rotating stirring blade with a vertical bar, for example, and these stirring blades. Is usually moved in close proximity along the inner wall of the tank, thereby removing the carbonate seed crystals formed on the inner wall of the tank from the wall and dispersing them in the solution. The agitation blade preferably extends on the funnel-like floor 34 of the cooling tank 16 (not shown here) and captures more or less all solid portions of the processing solution 12 deposited on the walls. Extends into the floor 34 . The spacing between the bar and the wall may be, for example, less than 20 mm, in particular less than 5 mm, preferably less than about 1 mm. The stirrer may extend to the drain 35 of the cooling tank so that the carbonate crystals can be removed from the wall.

  Although regeneration of the treatment solution 12 extends the service life of the treatment solution 12, the normal life of the treatment solution 12 is generally relatively short. This is highly dependent on the formation of carbonate compounds in solution, which can have a negative effect on the etching action. For this reason, the regenerator 10 according to the invention is used to reduce the carbonate concentration to a value preferably below 200 g / l, in particular to a value of 30 to 150 g / l, with a concentration value of 50 to 100 g / l. (Measured as grams of sodium carbonate per liter of treatment solution) is more preferred for obtaining optimal results. In order to set the desired concentration range of the treatment solution 12, the carbonate formed by the etching process is removed from the solution 12 using the apparatus 10. This is done by freezing the carbonate from the treatment solution 12 in the cooling tank 16 and the carbonate is converted from a dissolved state to an undissolved state. For economic reasons, as little permanganate as possible should be converted to an undissolved state. By using sodium permanganate, an appropriate freezing temperature can be selected and the carbonate can be frozen without freezing too much permanganate.

  The filter device 20 is used for rapid separation of the frozen carbonates, possibly dissolving the frozen carbonates.

  The temperature in the cooling tank 16 is set so that carbonate crystals form in the processing solution or on the inner wall. In order to freeze the carbonate, a solution temperature of −12 ° C. to + 12 ° C., in particular −9 ° C. to + 10 ° C., preferably −7 ° C. to + 5 ° C. is set. The temperature of the cooling liquid becomes lower respectively.

The amount of processing solution transferred to the cooling tank 16 provides an amount that does not exceed the temperature required to freeze the carbonate to prevent reverse dissolution of the carbonate seed crystals already formed. It is. Reverse lysis otherwise significantly reduces the rate of formation of frozen carbonates. Transferring portions of the processing solution to the cooling tank 16 and transferring the cooled and frozen processing solution containing carbonate from the cooling tank 16 to the downstream filter device 20 is dependent on the temperature of the processing solution in the cooling tank. Can be carried out such that the freezing temperature is not exceeded. Preferably, based on the working volume of the cooling tank 16, for example greater than 50 l, a partial volume of processing solution in the cooling tank 16, such as a supply and discharge of less than 10 l, will also occur. The corresponding partial volume can be set and transported by the supply pump 21 and the transfer pump 37. Return pump 23, the processing solution which is reproduced carbonated removed, and the rinse solution was produced by rinsing the filter cake back to the processing tank 14, these solutions can flow through the pre-cooling unit 22.

  The schematic block diagram of FIG. 2 shows additional structural details of the cleaning unit 36 that basically includes the filter device 20 compared to FIG. The filter device 20 can basically include a filter tank 42 and a filter such as a filter strainer 56.

  In order to obtain a high feed of filtered carbonate, from the time when a chilled processing solution, preferably a partial amount of the processing solution in the cooling tank 16, is added to the filter device 20, the formation of the filter cake. It has been found advantageous to carry out the filtration process in the shortest possible time, measured to completion. Thus, the filtration process is completed in less than 10 minutes, preferably less than 200 seconds. Alternatively, the filter device 20 can be cooled using, for example, a cooling jacket. Longer filtration times are possible.

  The cooling tank 16, the transfer line 38 between the cooling tank 16 and the filter device 20, and the filter tank 42 can be insulated.

  Improved filtration and separation effects can be achieved by using differential pressure. A negative pressure can be supplied from the negative pressure unit 24 to the tank 42 through the vacuum tube 46.

After filtration, the filter cake can be rinsed with water, preferably chilled water, preferably below 10 ° C., introduced from the rinse water line 40 through the nozzle 52 (FIG. 3). Any sticky permanganate solution can thereby be washed off and fed back into the treatment tank 14. That is, the rinse water can be sucked through the filter 56 by negative pressure or vacuum. After the filtration process of the filter cake consisting of carbonate crystals, the filter 56, through the nozzle 52, water, preferably washed by being not not or heated by cooling water, carbonate solutions or sludge removal through discharge water pipe 26 Is done.

  The schematic diagram of FIG. 3 shows a possible embodiment of the filter device 20 according to the invention. Around the upper region of the filter tank 42, the filter tank 42 has a nozzle 52 at the height of the filter or filter strainer 56. The nozzle 52 is used to rinse the filter cake or to clean the filter from the filter cake with water from the rinse water line 40. Filtrate is removed through return tube 44.

  The filter 56 can be disposed so as to be tiltable, for example, rotatable about a horizontal axis. The filter 56 occupies a horizontal position in the activated state and can be moved to a tilted or vertical position for the cleaning process. The filter 56 can also be tilted or rotated 180 °. In order to properly clean the filter strainer 56, the nozzle 52 is located at a height that is higher or lower than the height of the horizontally disposed strainer 56. During cleaning, the filter strainer 56 is tilted or rotated and the top and bottom sides are sprayed with rinse water.

  The ventilation unit 30 and the negative pressure pipe 46 of the negative pressure unit 24 are connected in the upper region of the tank but below the filter. The negative pressure unit 24 can basically include a negative pressure pump 59, a negative pressure tank 58, and a cutoff valve 57.

  As FIG. 1 shows, an apparatus 10 for setting a certain carbonate concentration in the treatment solution is an electrolyte regenerator 11 for permanganate oxidation for the manganate produced during the etching reaction. Can also be combined. In that case, both regenerators can be connected to the processing tank 14 through the supply and return pipes 25, 44, 64, 65.

10 11 electrolyte reproducing apparatus 12 processing solution 14 treatment tank 16 cooled tank 18 cooling device 19 returns the cooling jacket 20 filter device 21 supply pump 22 pre-cooling unit 23 the pump 24 the negative pressure unit 25 supply pipe 26 drain pipe, discarding unit 28 flushing device 30 Ventilation section 32 Stirrer 34 Floor, funnel-shaped floor 35 Drainage section 36 Washing unit 37 Transfer pump 38 Transfer line 40 Rinse water line 42 Rank, filter tank 44 Return pipe 46 Negative pressure pipe 52 Nozzle 56 Filter strainer 57 Cutoff valve 58 Negative pressure Tank 59 Negative pressure pump 64 Return pipe 65 Supply pipe

Claims (8)

The plastic member, a way to processing by a processing solution containing a permanganate, the concentration of the carbonate compound in the treatment solution, freezing, and subsequent said carbonate compound from the processing solution by filtration By removing , setting to a value of less than 200 g / l, the treatment solution comprises sodium permanganate.   The method of claim 1, wherein the permanganate proportion in the treatment solution comprises greater than 50% sodium permanganate. The method according to claim 1 or 2, wherein the freezing of the carbonate compound is performed by cooling the treatment solution to a freezing temperature of -12 ° C to + 12 ° C.   Transferring the plurality of portions of the processing solution to a cooling tank, and transferring the processing solution containing cooled and frozen carbonate from the cooling tank to a downstream filter device, the processing solution in the cooling tank. The method according to any one of claims 1 to 3, wherein the temperature is controlled so as not to exceed a freezing temperature.   The manganate produced by the reaction of permanganate in the treatment solution in a treatment tank with a plastic substrate is converted to permanganate by bringing the treatment solution into contact with an electrolytic cell. The method according to any one of the above. To carry out the method of any one of claims 1 to 5, by reducing the concentration of the carbonate compound contained in the processing solution, it is used in order to process the plastic member, over An apparatus for at least partially regenerating a treatment solution comprising manganate, the apparatus comprising at least one cooling tank, the cooling tank being fed with the treatment solution to be regenerated, and An apparatus comprising a downstream filter device for separating a carbonate compound from a treatment solution.   The apparatus according to claim 6, wherein the filter device includes at least one filter tank and one filter, and the filter tank is connected to a negative pressure unit.   Use of the device according to claim 6 or 7 for carrying out the method according to any one of claims 1 to 5.

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