JP2005113173A - Electroplating device for flexible multilayer circuit board - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electroplating device performing continuous treatment where, at the time of via filling, the time for the via filling is reduced, and plating precipitated on the cathode power supply part in a plating liquid bath can continuously be peeled. <P>SOLUTION: In the reel to reel continuous electroplating device where the blind via hole of a flexible multilayer circuit board is filled with plating metal so as to be formed, a cathode power supply part is provided in an electroplating liquid, the cathode power supply part is a belt body having conductivity, a plating peeling treatment tank is provided adjacently to the electroplating tank, and the belt body having conductivity is continuously passed through the inside of the electroplating tank and the inside of the plating peeling treatment tank. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to the production of a flexible multilayer wiring board having a multilayer structure in which insulating layers made of resin such as polyimide and conductor wiring layers are alternately laminated, and particularly used for an interposer for mounting a semiconductor element. The present invention relates to a plating apparatus for a flexible multilayer wiring board for forming minute diameter blind via holes by reel-to-reel continuous electrolytic plating.

  In recent years, semiconductor elements such as semiconductor large-scale integrated circuits (LSIs) have increased in the degree of integration of transistors, and the operating speed has reached 1 GHz in terms of clock frequency, and the number of input / output terminals has exceeded 1,000. Has led to.

  Moreover, in order to mount a semiconductor element on a printed wiring board, interposers such as BGA and CSP have been developed and put into practical use.

  Such a multilayer wiring board is formed by alternately stacking insulating resin layers and conductor wiring layers on a copper-clad substrate or a ceramic substrate (see, for example, Patent Document 1). The insulating layer of the multilayer wiring board manufactured by this method can be formed and thinned by applying a resin such as polyimide. Further, the conductor wiring layer can be formed by plating, and fine wiring is possible. On the other hand, the via hole connecting the upper and lower conductor wiring layers can be formed by forming a hole by laser processing or the like and plating the inside.

  Separately, a structure in which a polyimide film with copper foil is bonded to a conventional multilayer printed wiring board with an adhesive has also been proposed (see, for example, Patent Document 2). Also in this configuration, it is possible to form fine wiring from the thin copper foil, and similarly, high wiring density, thin film, and miniaturization can be achieved. Furthermore, since it is a tape-like film, reel-to-reel processing is possible, and production efficiency can be improved unlike conventional sheet processing.

  On the other hand, for the formation of via holes that connect the upper and lower conductor wiring layers, the introduction of excimer lasers and laser processing machines using third and fourth harmonics of YAG has become popular, and the formation of via holes with very small diameters has been carried out. ing. Via holes that connect the upper and lower conductor wiring layers are formed by laser in the order of conductor material and organic insulating material, exposing the surface of the lower conductor wiring layer, and then the residue of the organic insulating material deposited on the lower conductor wiring layer of the via hole Then, an electroplating seed layer is formed by electroless plating or the like, and this seed layer is used as an electrode to deposit a certain thickness of plating on the side and bottom of the hole.

  In this electroplating process, which deposits a certain thickness on the side and bottom of the hole, recently, filled vias are formed by filling the hole with plating metal in order to pass high-speed signals or increase the degree of freedom of wiring. A method of forming a via hole directly above a via is actively used.

  This filled via plating employs a technique in which a plating metal is selectively deposited inside the hole by various additives called polymers, brighteners, and levelers (see, for example, Patent Document 3). When this filled via plating is performed on a tape-shaped substrate such as a polyimide film with copper foil, an electroplating apparatus that performs continuous processing on a reel-to-reel is required.

  In this electroplating apparatus that performs continuous processing on a reel-to-reel basis, if there is a cathode power feeding part in an ordinary electroplating bath, plating also deposits on the cathode power feeding part, which can cause problems such as damage to the transfer part and the substrate. Therefore, the cathode feeding part is installed outside the electrolytic plating tank in the part where there is no plating solution.

  In the case of a continuous plating apparatus, the length of the electrolytic plating tank is determined according to the plating time and the conveyance speed, but in the case where a cathode feeding portion is provided at both ends of one electrolytic plating tank, the plating tank is If it is long, depending on the resistance of the substrate, the voltage becomes very large with respect to the set current during plating, and there are problems such as heat generation of the substrate. In many cases, a power feeding portion is arranged.

This cathode feeding part is arranged at both ends of the electroplating tank and exists in the air without being immersed in the plating solution, in order to prevent insufficient feeding due to poor contact between the substrate and the cathode feeding part. Liquid such as water is supplied. However, when filled via plating is performed, the supply of water in the cathode feeding portion and the cathode feeding portion are in the air, so there are problems such as disappearance of additives, oxidation of the substrate, lowering of copper concentration in the via, and so on. It takes longer than normal plating time. In other words, there was a problem that via filling was delayed.
Japanese Patent Laid-Open No. 4-148590 JP 2001-53115 A Japanese Patent Laid-Open No. 2001-200386

  The present invention arranges a cathode power feeding portion in a plating solution bath when performing via filling that fills via holes connecting upper and lower conductor wiring layers of a multilayer wiring board by an electroplating apparatus that performs continuous processing on a reel-to-reel basis. It is another object of the present invention to provide a plating apparatus capable of shortening the via filling time and continuously peeling the plating deposited on the cathode power feeding portion in the plating solution bath.

  According to the present invention, an insulating layer made of an organic insulating material and a wiring layer made of a conductive material are alternately stacked, and the blind via hole of a flexible multilayer wiring board having a blind via hole connecting the upper and lower wiring layers is filled with a plating metal. In the reel-to-reel continuous electrolytic plating apparatus to be formed, the electroplating apparatus for a flexible multilayer wiring board is characterized in that a cathode feeding portion is provided in an electrolytic plating solution.

  The present invention is also the electroplating apparatus for a flexible multilayer wiring board according to the above invention, characterized in that the cathode feeding portion is a conductive band.

  In the electroplating apparatus for a flexible multilayer wiring board according to the present invention, the conductive band is a metal belt or a conductive resin belt that has been welded and rolled all around. An electroplating apparatus for a flexible multilayer wiring board.

  Further, the present invention provides the electroplating apparatus for a flexible multilayer wiring board according to the above invention, wherein the conductive band contacts the cathode feeding roller in the process of transporting the conductive band. An electroplating apparatus for a flexible multilayer wiring board, wherein the electroplating apparatus is characterized in that it has a band.

Further, the present invention provides an electroplating apparatus for a flexible multilayer wiring board according to the above invention, wherein a plating stripping treatment tank is provided adjacent to the electroplating tank in order to peel the plating deposited on the conductive belt. An electroplating apparatus for a flexible multilayer wiring board, wherein the conductive strip is continuously passed through an electroplating bath and a plating stripping bath.

  The present invention is also directed to the electroplating apparatus for a flexible multilayer wiring board according to the above invention, wherein the conductive band is transported with a holding angle by an insulative driving roller and supports the board in order to support the board. An electroplating apparatus for a flexible multilayer wiring board, wherein at least one of the corner portions is brought into close contact with the substrate.

  The present invention is also the electroplating apparatus for a flexible multilayer wiring board according to the above invention, characterized in that the method for transporting the flexible multilayer wiring board is vertical transport.

  The present invention relates to a reel-to-reel continuous electrolytic plating apparatus that is formed by filling blind via holes with plating metal, the cathode feeding portion is provided in the electrolytic plating solution, and the plating stripping treatment tank is adjacent to the electrolytic plating tank. A flexible multi-layer that continuously passes the conductive strip through the electrolytic plating bath and the plating stripping treatment tank, shortening the via filling time and continuously stripping the plating deposited on the cathode power feeding section It becomes an electrolytic plating apparatus for a wiring board.

  Hereinafter, embodiments of the present invention will be described in detail.

  As shown in FIG. 1, a general electroplating apparatus includes a reel (101) and a take-up reel (105), and a reel-to-reel continuous electroplating apparatus that conveys the flexible multilayer wiring board in the vertical direction. It is.

  FIG. 2 shows one unit composed of a cathode feeding portion (102) and an electrolytic plating tank (103) in the reel-to-reel continuous electrolytic plating apparatus shown in FIG.

  The reel-to-reel plating apparatus has a long electrolytic tank, and the power supply at both ends causes problems such as heat generation of the substrate due to the resistance of the substrate and the voltage to the set current increases. As shown in FIG. 1, normally, a plurality of electrolytic plating tanks (103) are provided, and a cathode power feeding portion (102) is disposed therebetween.

  In the electrolytic plating tank, an anode (104) is arranged on one side or both sides through which the substrate (106) passes. A nozzle (107) for jetting is also installed in the plating tank.

  In reel-to-reel electrolytic plating, the film thickness variation in the conveyance direction is averaged by conveyance, but the film thickness variation occurs in the width direction. In particular, since current lines are concentrated at both ends of the substrate, shielding plates (108) are provided at the upper and lower ends of the substrate to prevent current lines from concentrating on the top and bottom of the substrate and to control variations in the width direction.

  Also, the horizontal transfer may be used as the transfer method. However, in the case of double-sided plating with horizontal transfer, the vertical transfer is preferable because an anode exists on the lower side and there is a problem in maintenance.

  The configuration of an embodiment of the electrolytic plating apparatus for a flexible multilayer wiring board according to the present invention will be described with reference to FIG. The substrate (201) to be plated is transported to the electrolytic plating tank (202) by reel-to-reel vertical transport. In the electrolytic plating tank (202), an anode (203) is arranged on both sides of the substrate (201), and a jet nozzle (204) for jetting and a film thickness control shielding plate (205) are arranged.

  In the present invention, a conductive belt (209) is used as the cathode feeding portion. The conductive band (209) is disposed in the electrolytic plating tank (202) with a certain holding angle on the insulating drive roller (208).

  The conductive band (209) passes through the plating solution side overflow drain tank (207) from the insulating drive roller (208), and the plating solution on the surface is dropped by the cleaning nozzle 1 (211). After passing through the negative electrode feeding roller (210), the plating peeling treatment tank (212), the cleaning nozzle 2 (215) and the air knife (216), the loop-like movement that is put into the electrolytic plating tank again is repeated.

  In FIG. 3, the white arrow indicates the transport direction of the substrate (201).

  The conductive band (209) has the polarity of the cathode by the cathode feeding roller (210) via the rotary connector (220) to which the cathode terminal cable (219) of the rectifier (217) is connected. . The conductive belt (209) comes into contact with the substrate (201) in the electrolytic plating tank (202), so that power can be supplied into the plating solution.

  As shown in FIG. 3, the cathode power feeding portion supports the front and back of the substrate (201) by disposing the insulating drive rollers (208) opposite to each other, and performs transport and power feeding to the front and back in a stable state. In addition, since it is necessary to return the transport line after support to the center position of the pass line again, for example, three or more support rollers are used, or the pass line is returned to the center position using a backup roll (206).

  The plating stripping treatment tank (212) has a stripping solution overflow drain (214) at both ends of the plating stripping treatment bath (212) so that the plating stripping treatment bath (212) can be immersed in the stripping solution and treated by the jet nozzle (213). It is said.

  Moreover, about the plating conditions, in the length of a plating tank, the conveyance speed which can ensure sufficient plating time for filling, a cathode current density, etc. are used as parameters. A flexible multilayer wiring board formed by such a plating method can be via-filled via holes in an appropriate plating time.

  Hereinafter, the present invention will be described by way of specific examples. In addition, this invention is not limited to this Example at all.

  A polyimide tape with double-sided copper foil (Neolex (trade name): Cu / PI / Cu = 9 μm / 30 μm / 9 μm) was used for the substrate. In order to process a via hole in this substrate, a via hole was processed using an ultraviolet laser having a wavelength of 355 nm. The processed via hole diameter was 30 μm.

  When the processed via hole was observed with an optical microscope, it was confirmed that dross due to via processing was generated at the opening end of the via hole. Therefore, physical polishing was performed to remove the dross portion.

  Thereafter, in order to remove the resin residue deposited on the bottom of the via hole, potassium permanganate and sodium hydroxide were dissolved in ion exchange water at a ratio of 3 to 2, and heated to about 50 ° C. The substrate was immersed in this mixed solution to remove the resin residue.

  Next, in order to form an electroplating seed layer, an ordinary electroless copper plating treatment was performed.

  Electrolytic copper plating was performed with a vertical-to-reel reel-to-reel continuous electrolytic plating apparatus. The length of the plating tank is 9 m, and power feeding rollers are installed at both ends of the plating tank. In the plating tank, a total of two sets of cathode power feeding portions made of a conductive belt body with 2 to 1 sets of substrate front and back surfaces were installed at intervals of 3 m.

As the conductive belt, a seamless stainless steel belt having a thickness of 0.3 mm that has been rolled on the entire circumference was used. The insulating drive roller in the plating tank was made of vinyl chloride. Further, 200 g / l of persulfate soda was used as the stripping solution, and 20 g / l of sulfuric acid was used for cleaning the conductive band before and after the stripping process.

  In the electrolytic plating tank, a positive electrode containing phosphorus-containing copper balls in a titanium case was installed on both sides of the substrate as an anode. In addition, a nozzle for jet flow was installed between the anodes, and a shielding plate for film thickness variation control was installed on the upper and lower parts of the substrate with a PVC plate.

  The composition of the plating solution was 200 g / l copper sulfate pentahydrate, 50 g / l sulfuric acid, 50 mg / l chlorine, and 25 ml / l plating additive. In order to set the plating current density and plating time to 1 ASD capable of via filling by single wafer processing and 30 minutes, the conveyance speed was set to 0.3 m / min.

  Thereafter, the cross-section of the substrate was observed to investigate the copper filling failure, but 0 of the 1,000 defective portions that had not been via-filled were investigated. In addition, the seamless stainless steel belt during the plating treatment could always come into contact with the substrate in an unplated state, and there was no generation of scratches or dents on the substrate.

  As a comparison, plating was performed in the same manner using a plating apparatus in which cathode feeding portions exposed in the air were provided before and after a 3 m long plating tank, and three tank plating tanks were arranged in series. Thereafter, cross-sectional observation of the substrate was performed, but filling was not completed in all the vias, and dents remained in the via portions.

As a comparison, the plating tank of the plating apparatus was set to 9 m, the cathode power feeding roller was installed at both ends, and plating was performed with one plating tank. The cathode feeding roller was installed in the air without being immersed in the plating solution. The conveyance speed was 0.3 m / min and the current density was 1 A / dm ² .

  As a result, since a long plating tank of 9 m was fed, it was confirmed that the voltage rose to a maximum of about 5 V with respect to the set current due to the resistance of the substrate, and the surface temperature of the substrate rose to about 70 ° C. . Therefore, it was determined that it was impossible to feed power to the long plating layer of 9 m only at both ends.

  As another comparison, plating was performed by setting the plating tank of the plating apparatus to 9 m and placing a cathode feeding roller in the plating solution every 3 m. Filling was completed in all vias and there were no dents in the vias, but as the plating time increased, plating was deposited on the cathode feed roller, causing scratches and dents other than vias on the substrate surface. did.

  From the above results, since it is difficult to feed a long plating layer only at both ends, it is necessary to install a cathode feeding roller in the middle, the cathode feeding roller installed in the middle is not installed in the air, Filling is possible by placing it in the liquid, and scratches and dents on the substrate can be prevented by continuously peeling the plating deposited on the cathode feeding portion.

It is a block diagram of a general reel-to-reel continuous electrolytic plating apparatus. It is a block diagram of 1 unit of the reel to reel continuous electroplating apparatus of FIG. It is a block diagram of one Example of the electroplating apparatus of the flexible multilayer wiring board of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 101 ... Unwinding reel 102 ... Cathode feeding part 103 ... Electrolytic plating tank 104 ... Anode 105 ... Winding reel 106 ... Substrate 107 ... Jet nozzle 108 ... Film thickness control shielding plate 201 ... Substrate 202 ... Electrolytic plating tank 203 ... Anode 204 ... jet nozzle 205 ... shielding plate for film thickness control 206 ... backup roll 207 ... plating solution side overflow drain 208 ... insulating drive roller 209 ... conductive belt 210 ... cathode feeding roller 211 ... cleaning nozzle 1
212 ... Plating peeling treatment tank 213 ... Jet nozzle 214 ... Stripping liquid overflow drain 215 ... Cleaning nozzle 2
216 ... Air knife 217 ... Rectifier 218 ... Anode terminal cable 219 ... Cathode terminal cable 220 ... Rotary connector

Claims (7)

  Reel toe formed by filling insulating vias made of an organic insulating material and wiring layers made of a conductive material alternately, and filling the blind via holes of a flexible multilayer wiring board having blind via holes connecting the upper and lower wiring layers with plating metal. An electroplating apparatus for a flexible multilayer wiring board, wherein a cathode power feeding portion is provided in an electroplating solution in a reel continuous electroplating apparatus.   2. The electroplating apparatus for a flexible multilayer wiring board according to claim 1, wherein the cathode feeding portion is a conductive band.   3. The electroplating apparatus for a flexible multilayer wiring board according to claim 2, wherein the conductive belt is a metal belt or a conductive resin belt that has been welded and rolled all around.   4. The conductive band according to claim 2, wherein the conductive band is made into a negative band by contacting a negative electrode feeding roller in a process of transporting the conductive band. Electroplating equipment for flexible multilayer wiring boards.   In order to peel the plating deposited on the conductive strip, a plating stripping treatment tank is provided adjacent to the electrolytic plating bath, and the conductive strip is continuously removed from the inside of the electrolytic plating bath. 5. The electroplating apparatus for a flexible multilayer wiring board according to claim 2, 3 or 4, wherein the tank is passed through.   The conductive belt is conveyed with a holding angle by an insulating drive roller, and the holding angle portion is closely attached to the substrate at least one place on the front and back of the substrate in order to support the substrate. Item 6. The electrolytic plating apparatus for a flexible multilayer wiring board according to Item 2, 3, 4, or 5.   The electroplating apparatus for a flexible multilayer wiring board according to claim 1, wherein the transporting method of the flexible multilayer wiring board is vertical conveyance.