JP2014136820A - Electroplating method and electroplating apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electroplating method for avoiding occurrence of short circuit between upper and lower conductor circuit layers of an interlayer resin insulating layer caused by sludge and formation of a dint in an upper surface of a via conductor formed in a conductor circuit layer.SOLUTION: In the electroplating method, when an electroplating layer is formed on a surface of an object to be plated 3 by immersing the object to be plated 3 serving as a cathode into an electroplating bath into which a plating solution 1 is charged, and further immersing a net-like vessel 5 accommodating an anode metal 4 injected therein, and then applying an electric current to the object to be plated 3 and the anode metal 4, sludge S generated from the anode metal 4 in the net-like vessel during plating treatment is removed from the electroplating bath by sucking the sludge S together with the plating solution from the electroplating bath through a suction pipe 7 by a suction pump 8, then separating the sludge from the plating solution by passing the sucked plating solution through a microfiltration filter 9, and returning the plating solution separated from the sludge to the vicinity of the object to be plated 3 in the electroplating bath.

Description

  The present invention relates to an electrolytic plating method and an electrolytic plating apparatus used for forming a conductive circuit layer of a printed wiring board.

  As a conventional electrolytic plating method, for example, the one described in Patent Document 1 is known, and in the apparatus described in Patent Document 1, an object to be plated as a cathode metal is immersed in an electrolytic plating tank containing a plating solution. At the same time, the anode basket filled with anode metal pellets is immersed in the vicinity of the object to be plated, and the anode metal ions in the plating solution are attached to the surface of the object to be plated by energizing them. An electrolytic plating layer is formed with the anode metal. At this time, if the plating amount increases, sludge is generated from the anode metal pellets in the anode basket, and the plating surface is contaminated by the sludge. In this method, bubbling is generated by supplying air to the bottom of the anode basket. The sludge is peeled off from the anode metal pellet and removed from the anode basket.

  Further, as a conventional electrolytic plating method, for example, the one described in Patent Document 2 is also known. In the method described in Patent Document 2, an object to be plated as a cathode metal is placed in an electrolytic plating tank containing a plating solution. Immerse the anode basket containing the mesh titanium case filled with the anode metal and apply electricity to them to attach the anode metal ions in the plating solution to the surface of the object to be plated. An electrolytic plating layer is formed with an anode metal. In this method, sludge generated from the anode metal in the anode basket during the plating process is received by the tray at the bottom of the anode basket, sucked together with the plating solution by the suction pipe, and passed through the filter from the plating solution. The sludge is removed from the anode basket by separating and returning the plating solution into the anode basket.

JP 09-241894 A JP 07-286299 A

  By the way, with the recent thinning of the printed wiring board, the thickness of the interlayer resin insulation layer constituting the build-up layer has also been reduced. For this reason, there is a problem that sludge adhering to the surface of the lower conductor circuit layer may penetrate the interlayer resin insulation layer, and a short circuit may occur between the upper and lower conductor circuit layers of the interlayer resin insulation layer. In this method, only the sludge is peeled off by bubbling, and the sludge is still floating in the plating solution in the electrolytic plating tank, so this short circuit problem cannot be solved.

  In the latter conventional method, sludge is removed from the plating solution together with the plating solution through a normal filter. However, fine sludge that passes through the eyes of a normal filter is contained in the electrolytic plating tank. There is a problem that it cannot be removed from the plating solution and is not sufficient for preventing short circuit. In addition, in this method, since the plating solution that has passed through the filter is returned to the anode basket, the metal ion concentration in the plating solution near the object to be plated decreases, and the upper surface of the via conductor formed in the conductor circuit layer is reduced. There is also a problem that dents are easily formed.

The present invention aims to advantageously solve the above problems, and the electrolytic plating method of the present invention immerses an object to be plated as a cathode metal in an electrolytic plating bath containing a plating solution. Then, a net-like container filled with the anode metal is immersed, and the object to be plated and the anode metal are energized to attach the anode metal ions in the plating solution to the surface of the object to be plated, and the anode metal is deposited on the surface of the object to be plated. When forming the electroplating layer with
During the plating process, sludge generated from the anode metal in the mesh container is sucked from the electrolytic plating tank through the suction pipe together with the plating solution with a suction pump, and the sucked plating solution is passed through a microfiltration filter. The sludge is removed from the electrolytic plating tank by separating the sludge from the plating liquid and returning the plating liquid from which the sludge has been separated to the vicinity of the object to be plated in the electrolytic plating tank.

Moreover, the electrolytic plating apparatus of the present invention immerses the object to be plated as the cathode metal in the electrolytic plating tank containing the plating solution, and also immerses the mesh container filled with the anode metal. In an apparatus for energizing a metal to attach anode metal ions in the plating solution to the surface of the object to be plated, and forming an electrolytic plating layer with the anode metal on the surface of the object to be plated,
A suction pump for sucking sludge generated from the anode metal in the mesh container during the plating process together with the plating solution from the electrolytic plating tank through the suction pipe;
A microfiltration filter that separates sludge in the plating solution from the plating solution through the plating solution sucked by the suction pump;
A return pipe for returning the plating solution from which the sludge has been separated by the microfiltration filter to the vicinity of the object to be plated in the electrolytic plating tank;
It is characterized by comprising.

  In the electrolytic plating method and the electrolytic plating apparatus according to the present invention, in the electrolytic plating tank containing the plating solution, the object to be plated as the cathode metal is immersed, and the mesh container filled with the anode metal is immersed, During the plating process, the anode metal ions in the plating solution are attached to the surface of the object to be plated by energizing the object to be plated and the anode metal, and the electrolytic plating layer is formed with the anode metal on the surface of the object to be plated. In addition, the sludge generated from the anode metal in the mesh container is sucked from the electrolytic plating tank through the suction pipe together with the plating solution with the suction pump, and the sucked plating solution is passed through the microfiltration filter to plate the sludge. Sludge is removed from the electrolytic plating tank by separating the plating solution from the liquid and returning the plating solution from which the sludge has been separated to the vicinity of the object to be plated in the electrolytic plating tank.

  Therefore, according to the electrolytic plating method and the electrolytic plating apparatus of the present invention, the sludge generated from the anode metal is removed from the plating solution in the electrolytic plating tank to a fine one, so that the build-up layer of the printed wiring board is configured. Even if the thickness of the interlayer resin insulation layer is small, sludge adhering to the surface of the lower conductive circuit layer avoids the occurrence of a short circuit between the upper and lower conductive circuit layers of the interlayer resin insulation layer due to the penetration of the interlayer resin insulation layer be able to. Also, since the plating solution sucked from the electrolytic plating tank is returned to the vicinity of the object to be plated in the electrolytic plating tank, the metal ion concentration of the plating liquid in the vicinity of the object to be plated does not decrease, so build-up of the printed wiring board Formation of a recess in the upper surface of the via conductor formed in the conductor circuit layer constituting the layer can be reduced or avoided.

  In the electrolytic plating method and the electrolytic plating apparatus of the present invention, preferably, the microfiltration filter has a pore diameter of 0.1 μm or less. In this way, fine sludge exceeding 0.1 μm is collected and removed by the microfiltration filter, so even if the thickness of the interlayer resin insulation layer on the lower conductive circuit layer is reduced to nearly 1 μm, it is fine. A short circuit between upper and lower conductive circuit layers due to sludge can be avoided.

  In the electrolytic plating method and the electrolytic plating apparatus according to the present invention, preferably, a diaphragm that allows metal ions to pass through but does not allow fine sludge to pass between the mesh container and the object to be plated in the electrolytic plating tank. It shall be partitioned. In this way, it is possible to supply metal ions directly from the anode metal in the mesh container to the vicinity of the object to be plated while avoiding a short circuit between the upper and lower conductor circuit layers due to fine sludge. Therefore, the formation of a recess in the upper surface of the via conductor formed in the conductor circuit layer constituting the build-up layer of the printed wiring board can be reduced or avoided.

  Furthermore, in the electrolytic plating method and the electrolytic plating apparatus according to the present invention, preferably, the microfiltration filter is screwed to the open end portion of the one-end open type cylindrical filter cartridge. In this way, it is possible to prevent the fine sludge from leaking out from the mounting portion of the filter cartridge and to reliably avoid a short circuit due to the fine sludge.

  In the electroplating method and the electroplating apparatus of the present invention, preferably, a coarse sludge filter is inserted between the microfiltration filter and the suction pump, and a large sludge exceeding 1 μm, for example, is first placed. Remove with coarse filter. In this way, it is possible to prevent the microfiltration filter from being clogged with a large sludge and to allow the device to be operated continuously for a long time.

It is a block diagram which shows typically one Embodiment of the electroplating apparatus of this invention used for one Embodiment of the electroplating method of this invention.

  Hereinafter, an embodiment of an electrolytic plating method of the present invention and an embodiment of an electrolytic plating apparatus of the present invention will be described in detail with reference to the drawings. FIG. 1 is a configuration diagram schematically showing one embodiment of the electrolytic plating apparatus of the present invention used in one embodiment of the electrolytic plating method of the present invention.

The electrolytic plating apparatus of this embodiment immerses a printed wiring board 3 as a cathode metal as a cathode metal in an electrolytic plating tank 2 containing a plating solution 1 and is filled with many copper balls 4 as an anode metal. The net-like titanium case 5 as a net-like container is immersed, and the net-like titanium case 5 and the printed wiring board 3 are partitioned by a nano-level diaphragm 6. By supplying a current from a power source (not shown) to the electrode such as the electroless plating film of the printed wiring board 3 and the copper ball 4 in the mesh titanium case 5, the copper ions (Cu ²⁺ ) C in the plating solution 1 are supplied While being attached to the electrode surface of the printed wiring board 3, electrons (e ⁻ ) E are emitted from the electrode of the printed wiring board 3 to form an electrolytic copper plating layer on the electrode surface of the printed wiring board 3.

In addition, the electrolytic plating apparatus of this embodiment electrolyzes sludge S such as copper oxide (Cu ₂ O) and copper sulfide (Cu ₂ S) generated from the copper balls 4 in the mesh titanium case 5 during the plating process. A suction pump 8 that sucks together with the plating solution 1 from the inside of the plating tank 2 through the suction pipe 7, and the sludge S in the plating solution 1 is passed through the plating solution 1 sucked by the suction pump 8. A microfiltration filter 9 that is separated from the plating solution 1 and a return pipe 10 that returns the plating solution 1 from which the sludge S has been separated by the microfiltration filter 9 to the vicinity of the printed wiring board 3 in the electrolytic plating tank 2 are provided. Yes.

  Furthermore, the electroplating apparatus of this embodiment is provided with a rough filtration filter 11 that first separates the large sludge S from the plating solution 1 between the suction pump 8 and the microfiltration filter 9. Between the microfiltration filter 9 and the electroplating tank 2 on the downstream side, a flow meter 12 for measuring the flow rate of the plating solution 1 separated from the sludge S and returned to the electroplating tank 2 is provided. .

  Here, the microfiltration filter 9 includes, for example, a PTFE (polytetrafluoroethylene) membrane type or a PSU (hydrophilic polysulfone) membrane type pleated filter (a solid material having a size of 0.1 μm or more manufactured by JMC Filter Co., Ltd.). Is used. A single-end open cylindrical filter cartridge with a maximum pore diameter of 0.1 μm is used, and the small-diameter cylindrical open end of the cylindrical filter cartridge is used as a single-end open cylinder. It is assumed that the filter cartridge mounting portion of the filter housing for the filter cartridge is mounted with a screw formed on the outer peripheral surface of the open end portion through a seal member such as an O-ring or a seal tape.

  In addition, the nano-level diaphragm 6 here is also, for example, a PTFE (polytetrafluoroethylene) film type or PSU film type pleated filter manufactured by JMC Filter Co., Ltd. .99%) and a diaphragm with a maximum pore diameter of 0.1 μm.

  In the plating method of this embodiment using the plating apparatus of this embodiment, sludge S generated from the copper balls 4 in the mesh titanium case 5 is removed from the electrolytic plating tank 2 during the plating process performed as described above. The suction pump 8 sucks the plating solution 1 together with the plating solution 1 through the suction pipe 7. The sucked plating solution 1 is first passed through the coarse filter 11 to first separate the large sludge S from the plating solution 1. The fine sludge S is separated from the plating solution 1 through the microfiltration filter 9, and the plating solution 1 separated from the sludge S is measured in the electrolytic plating tank 2 by the return pipe 10 while measuring the flow rate with the flow meter 12. The sludge S is removed from the electrolytic plating tank 2 by returning to the vicinity of the printed wiring board 3.

  Here, while the plating solution 1 is sucked out by the suction pump 8 in the electroplating tank 2 on the mesh titanium case 5 side with respect to the nano-level diaphragm 6, the electroplating tank 2 on the printed wiring board 3 side with respect to the nano-level diaphragm 6. In the inside, since the plating solution 1 is supplied through the return pipe 10, the surface of the plating solution 1 is closer to the mesh titanium case 5 side in the electrolytic plating tank 2 on the printed wiring board 3 side than the nano-level diaphragm 6. The difference in water head is higher than that in the electroplating tank 2, and the plating solution 1 is directly or directly into the electroplating tank 2 on the mesh titanium case 5 side from the electroplating tank 2 on the printed wiring board 3 side. Relaxed by moving through.

  Therefore, according to the electrolytic plating method and the electrolytic plating apparatus of this embodiment, the sludge S generated from the copper ball 4 is removed from the plating solution 1 in the electrolytic plating tank 2 up to the minute, so that the printed wiring board 3 Even if the thickness of the interlayer resin insulation layer constituting the build-up layer is thin, sludge adhering to the surface of the lower conductor circuit layer penetrates the interlayer resin insulation layer, so that the interlayer resin insulation layer between the upper and lower conductor circuit layers The occurrence of a short circuit can be avoided. In addition, since the plating solution 1 sucked from the electrolytic plating tank 2 is returned to the vicinity of the printed wiring board 3 in the electrolytic plating tank 2, the copper ion concentration of the plating liquid 1 in the vicinity of the printed wiring board 3 does not decrease. Formation of a recess in the upper surface of the via conductor formed in the conductor circuit layer constituting the build-up layer of the printed wiring board 3 can be reduced or avoided.

  Furthermore, according to the electroplating method and the electroplating apparatus of this embodiment, since the microfiltration filter 9 has a pore diameter of 0.1 μm or less, fine sludge S exceeding 0.1 μm is filtered by the microfiltration filter 9. Since they are collected and removed, even if the thickness of the interlayer resin insulation layer on the lower conductor circuit layer is reduced to nearly 1 μm, a short circuit between the upper and lower conductor circuit layers due to fine sludge can be avoided.

  Further, according to the electroplating method and the electroplating apparatus of this embodiment, copper ions C are permeated but fine sludge S is permeated between the mesh titanium case 5 and the printed wiring board 3 in the electroplating tank 2. Since it is partitioned by the nano-ion diaphragm 6 that is not allowed to flow, the copper ions C can be directly supplied from the copper balls 4 of the mesh titanium case 5 to the vicinity of the printed wiring board 3 while avoiding a short circuit between the upper and lower conductor circuit layers due to fine sludge. Since the copper ion concentration of the plating solution 1 in the vicinity of the printed wiring board 3 does not decrease, the formation of a depression on the upper surface of the via conductor formed in the conductor circuit layer constituting the build-up layer of the printed wiring board 3 is reduced or avoided. be able to.

  Furthermore, according to the electroplating method and the electroplating apparatus of this embodiment, the microfiltration filter 9 is screw-mounted on the open end portion of the one-side open type cylindrical filter unit. It is possible to prevent leakage of fine sludge and to prevent short circuit due to fine sludge.

  Then, according to the electrolytic plating method and the electrolytic plating apparatus of this embodiment, the coarse sludge filter 11 is inserted between the microfiltration filter 9 and the suction pump 8, and a large sludge S exceeding 1 μm, for example, is first applied. Since the coarse filtration filter 11 removes the fine filtration filter 9, the fine filtration filter 9 can be prevented from being clogged, and the apparatus can be operated continuously for a long time.

  As mentioned above, although demonstrated based on the example of illustration, the electroplating method and the electroplating apparatus of this invention are not limited to the above-mentioned example, and can be suitably changed within the limits of the statement of a claim, For example, in the above embodiment, the coarse filtration filter 11 is interposed between the fine filtration filter 9 and the suction pump 8, but the coarse filtration filter 11 can be omitted by providing a plurality of the fine filtration filters 9 in parallel, for example. . The electrolytic plating method and the electrolytic plating apparatus of the present invention can also be applied to electrolytic plating using an anode metal other than copper.

  Thus, according to the electrolytic plating method and the electrolytic plating apparatus of the present invention, since sludge generated from the anode metal is removed from the plating solution in the electrolytic plating tank to a fine one, the build-up layer of the printed wiring board is configured. Even if the thickness of the interlayer resin insulation layer is thin, avoid the occurrence of a short circuit between the upper and lower conductor circuit layers of the interlayer resin insulation layer due to the sludge adhering to the surface of the lower conductor circuit layer penetrating the interlayer resin insulation layer Can do. Also, since the plating solution sucked from the electrolytic plating tank is returned to the vicinity of the object to be plated in the electrolytic plating tank, the metal ion concentration of the plating liquid in the vicinity of the object to be plated does not decrease, so build-up of the printed wiring board Formation of a recess in the upper surface of the via conductor formed in the conductor circuit layer constituting the layer can be reduced or avoided.

DESCRIPTION OF SYMBOLS 1 Plating solution 2 Electrolytic plating tank 3 Printed wiring board 4 Copper ball 5 Reticulated titanium case 6 Nano level diaphragm 7 Suction piping 8 Suction pump 9 Fine filtration filter 10 Return piping 11 Coarse filtration filter 12 Flow meter C Copper ion E Electron S sludge

Claims (8)

Immerse the object to be plated as the cathode metal in the electrolytic plating tank containing the plating solution, immerse the mesh container filled with the anode metal, and energize the object to be plated and the anode metal in the plating solution. When attaching an anode metal ion to the surface of the object to be plated and forming an electrolytic plating layer with the anode metal on the surface of the object to be plated,
During the plating process, sludge generated from the anode metal in the mesh container is sucked from the electrolytic plating tank through the suction pipe together with the plating solution with a suction pump, and the sucked plating solution is passed through a microfiltration filter. An electrolytic plating method comprising removing sludge from an electroplating bath by separating the sludge from the plating bath and returning the separated plating solution to the vicinity of the object to be plated in the electroplating bath.   2. The electrolytic plating method according to claim 1, wherein the microfiltration filter has a pore size of 0.1 [mu] m or less.   The electrolysis according to claim 1 or 2, wherein the mesh container in the electrolytic plating tank and the object to be plated are separated by a diaphragm that allows metal ions to permeate but does not allow fine sludge to permeate. Plating method.   The electrolytic plating method according to any one of claims 1 to 3, wherein the microfiltration filter is screwed to an open end of a cylindrical filter cartridge having an open end. Immerse the object to be plated as the cathode metal in the electrolytic plating tank containing the plating solution, immerse the mesh container filled with the anode metal, and energize the object to be plated and the anode metal in the plating solution. In an apparatus for attaching an anode metal ion to the surface of the object to be plated and forming an electrolytic plating layer with the anode metal on the surface of the object to be plated,
A suction pump for sucking sludge generated from the anode metal in the mesh container during the plating process together with the plating solution from the electrolytic plating tank through the suction pipe;
A microfiltration filter that separates sludge in the plating solution from the plating solution through the plating solution sucked by the suction pump;
A return pipe for returning the plating solution from which the sludge has been separated by the microfiltration filter to the vicinity of the object to be plated in the electrolytic plating tank;
An electrolytic plating apparatus comprising:   6. The electrolytic plating apparatus according to claim 5, wherein the microfiltration filter has a pore diameter of 0.1 [mu] m or less.   The electrolytic plating according to claim 5 or 6, further comprising a diaphragm that partitions the mesh container in the electrolytic plating tank and the object to be plated and allows metal ions to permeate but does not allow fine sludge to permeate. apparatus.   8. The electroplating apparatus according to claim 5, wherein the microfiltration filter is a device in which an open end portion of a single-end open type cylindrical filter cartridge is screwed. 9.

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