JP4899265B2 - MULTILAYER WIRING BOARD, MANUFACTURING METHOD THEREOF, AND LASER DRILL DEVICE - Google Patents

Description

【００５３】
【発明の効果】
本発明の多層配線基板の製造方法及びレーザードリル装置によれば、レーザードリル加工後のドロス除去専用工程（例えば物理研磨や化学研磨）を省略することができ、金属配線層と樹脂絶縁層とが交互に積層してなる多層配線基板において基板製造の短縮化でき、また孔部形成後の薬液処理による液流れを改善できるため歩留まり向上になる。また基板製造の短縮化によって、基板への負荷（基板の収縮および表面改質、樹脂絶縁層への吸湿）を回避することができる。
【００５４】
【図面の簡単な説明】
【図１】両面銅箔付き樹脂フレキシブル基板における穴止め（ブラインドビア）加工の上面図および断面図である。
【図２】レーザードリル加工によるドロス除去を示す説明図である。
【図３】レーザードリル加工後における上面配線層のテーパ角度（θ₂）および中間樹脂絶縁層におけるテーパ角度（θ₁）を示す説明図である。
【図４】テーパ角度を備えた孔部へのめっき処理時における薬液流れを示す説明図である。
【符号の簡単な説明】
１ 孔部開口径
２ 孔部底部径
３ 上面金属配線層
４ 絶縁樹脂層
５ 下面金属配線層
６ ドロス
７ ドロス径
８ 上面金属配線層加工用レーザーパルス光
９ 絶縁樹脂層加工用レーザーパルス光
１０ ドロス除去用レーザーパルス光[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for removing dross generated at a hole opening end for forming a via hole formed for interlayer connection of a metal wiring layer, and a multilayer wiring board using the same. More specifically, the present invention relates to a multilayer wiring board, a printed wiring board, a multilayer wiring board using via holes for interlayer connection formed in an interlayer insulating layer of a printed circuit for high-density mounting, a manufacturing method thereof, and a laser drill apparatus. is there.
[0002]
[Prior art]
In recent years, the performance of semiconductors has dramatically improved, and semiconductors have become multiterminal. However, since the printed wiring board (mother board) in the hard disk of the computer and the printed wiring board in the portable terminal and the mobile phone have a limited area, the size of the wiring board (semiconductor package) on which the semiconductor is mounted is limited.
[0003]
In order to mount a multi-terminal semiconductor, it is necessary to make the wiring board thinner (high density), but since the manufacturing method is difficult, multilayer wiring of the wiring board reduces the thinning of the wiring. Measures to take are taken. In multilayering, a hole is formed and a conductive metal material is coated in the hole so that an interlayer connection between the upper and lower metal wiring layers sandwiching the resin insulating layer is established.
[0004]
Conventionally, machining with a metal drill has been the mainstream when forming holes for interlayer connection. However, if the hole becomes finer, the drill to be processed naturally becomes smaller, but the micro drill is a consumable product that is expensive to manufacture and wears during processing. Therefore, in recent years, instead of machining a metal drill, laser processing (the apparatus used therefor is called a laser drill apparatus) that irradiates a workpiece with high-energy laser light and absorbs it by thermal processing is used instead of metal drill machining. It has come to be used.
[0005]
The laser beam used for laser processing is CO in the infrared region. ₂ Laser (wavelength 9.3 to 10.6 μm), YAG laser (fundamental wavelength 1.06 μm), YAG, YLF, YAP, YVO in the ultraviolet region _Four Lasers (third harmonic wavelength 355 nm, fourth harmonic wavelength 266 nm) and excimer lasers (XeCl wavelength 308 nm, KrF wavelength 248 nm, ArF wavelength 193 nm) are currently used as laser light for processing machines. . Laser processing using wavelengths in the infrared region is thermal processing or pyrolytic processing compared to machining in metal drills, and laser processing using wavelengths in the ultraviolet region is called photolytic processing using photochemical reactions.
[0006]
In the machining with a metal drill, the formation of the through hole is the mainstream, but since the laser machining is a pulse oscillation, only the insulating layer can be machined (hole stopper machining; FIG. 1). Therefore, the laser processing is mainly used for the blind hole processing of the wiring board. The separation of the hole diameters that are currently in practical use with various laser beams is CO. ₂ The laser has a diameter of 50 to 150 μm, and the ultraviolet laser has a diameter of 30 to 80 μm. Excimer lasers can be processed to a smaller diameter, such as φ20 μm, but are not suitable for mass production due to expensive consumables such as a highly reflective metal oxide mask and laser medium gas maintenance. However, in the above-described segregation, the formation of holes by ultraviolet lasers is promising as the density of wiring boards increases.
[0007]
In addition, in the formation of the wiring layer, for example, when the material of the metal wiring layer is copper, a manufacturing method (subtractive method) for forming wiring from the entire copper foil layer and a reverse pattern of the wiring are formed on the intermediate resin insulating layer, A manufacturing method (semi-additive method) in which copper wiring is deposited by an electrochemical method is considered promising. In general, it is said that the semi-additive method is superior for miniaturization of wiring. However, in order to form wiring, it is necessary to use both electroless plating and electrolytic plating. Wiring is formed only by etching copper foil. However, the subtractive method capable of producing a small number of manufacturing methods is suitable for mass production. In recent years, it has been reported that the thinning approaching the fine wiring of the semi-additive method is possible by improving the technology of the subtractive method.
[0008]
A multilayer wiring board is formed by hole formation by laser drilling and wiring formation by a subtractive method. The processing order is that the entire copper foil layer is subjected to laser drilling, and after the hole is formed, the inner wall of the hole is coated with a metal material by, for example, an electrochemical technique, and then the etching resist is patterned to etch ferric chloride solution or the like. Copper wiring is formed with a liquid.
[0009]
If the target of laser drilling is only a resin insulation layer, CO ₂ Although the hole can be formed with an ultraviolet laser, it is necessary to process the metal wiring layer and the resin insulating layer simultaneously (direct processing). However, CO ₂ If it is a laser, the laser beam is not absorbed by the copper foil and is reflected because it is not in the absorption wavelength range of the metal wiring layer.
[0010]
In order to solve the above problem, the metal wiring layer is blackened and CO ₂ A method of absorbing laser light or a method of performing via processing using a laser (conformal processing) after patterning a metal wiring layer into a hole shape by known photolithography (photo process) has been implemented. However, these methods have a problem in terms of manufacturing cost because the manufacturing process of the wiring board increases.
[0011]
Since the wavelength of the ultraviolet laser overlaps with the absorption wavelength of the metal, direct processing is possible. In addition, since the energy density is high, laser processing is possible even with a minute diameter. However, although it is the absorption wavelength of the metal, the hole is formed as shown in FIG. 1 because the heat processing element is strong for the metal and the copper foil is dissolved. Here, the copper melted by the high energy of the laser light becomes the shape 6 shown in FIG. Since several pulses to several tens of pulses are irradiated to form one hole, dross is formed in a form in which the copper dissolved at the opening end of the hole rises. FIG. 1 shows a top view and a cross-sectional view of a hole after laser drilling.
[0012]
If an attempt is made to fill the inside of the hole with copper, for example, by electrolytic plating while the dross 6 remains, the electric field concentrates on the locally uneven dross portion, and the growth of electrolytic copper on the upper surface copper layer is accelerated. The space is closed by the upper surface copper layer before the electrolytic copper is filled in the portion. As a result, voids remain in the holes. For this reason, dross must be removed after laser drilling the hole.
[0013]
For the conventional dross removal, chemical polishing or the like that is smoothed by physical polishing using a polishing sheet, an abrasive kneading buff, or the like, or selectively removes the convex portion of the hole opening is used. However, physical polishing may change the shape of the hole opening, chemical polishing may also polish copper at wiring locations other than dross, and surface modification by chemicals may occur. Furthermore, each dross removal method has one or more process lines, and thus has a problem in terms of product reliability and productivity.
[0014]
[Problems to be solved by the invention]
The present invention has been made in order to solve the above-described problems, and the formation of holes for connecting the upper and lower metal wiring layers to a multilayer wiring board composed of a plurality of resin insulation layers and metal wiring layers. Provided are a multilayer wiring board, a manufacturing method thereof, and a laser drill apparatus, which perform laser drilling to remove dross generated at the hole opening end for forming a via hole without using a dedicated process such as physical polishing or chemical polishing. With the goal.
[0015]
In order to achieve the above object in the present invention, first, in the invention of claim 1, in a method for manufacturing a multilayer wiring board in which insulating layers made of a resin insulating film and wiring layers made of a conductor film are alternately laminated, After forming the hole for forming the via hole from the wiring layer side of the wiring board using laser drilling, remove the dross generated at the opening end of the hole using the laser drill. Then, the taper angle is added to the upper wiring layer at the same time as the hole opening end dross is processed. This is a method for manufacturing a multilayer wiring board.
[0016]
In the invention of claim 2, the method of manufacturing a multilayer wiring board according to claim 1, wherein the laser drill is an ultraviolet laser drill using a single wavelength of 355 nm or less.
[0017]
In the invention of claim 3, the order of laser drilling the multilayer wiring board in which the insulating layers made of the resin insulating film and the wiring layers made of the conductor film are alternately laminated is the top surface wiring layer, the intermediate resin insulating layer, 3. The method of manufacturing a multilayer wiring board according to claim 1, wherein the hole opening end dross.
[0018]
In the invention of claim 4, a laser processing diameter larger by 0.1 to 50 μm than the hole processing diameter is used when removing dross generated at the opening end of the hole than the laser processing diameter at the time of forming the hole. The method for producing a multilayer wiring board according to claim 1, wherein:
[0019]
According to the invention of claim 5, the dross at the opening end is removed after the formation of individual holes in the same plane in the multilayer wiring board in which the insulating layers made of the resin insulating film and the wiring layers made of the conductor film are alternately laminated. At least one of burst processing to be performed or cycle processing to remove dross at the opening ends of all the holes in the same locus after forming all the holes in the same plane in the multilayer wiring board. It is a manufacturing method of the multilayer wiring board of Claims 1-4.
[0020]
In the invention of claim 6, In the hole for forming the via hole, the ratio of the taper angle of the upper surface wiring layer to the taper angle of the intermediate resin insulating layer (intermediate resin insulating layer / upper surface wiring layer) is 0.40 to 1.00. A method for producing a multilayer wiring board according to any one of claims 1 to 5 It is.
[0021]
Further, in the invention of claim 7, the claims 1 to 6 In the multilayer wiring board in which the insulating layer made of the resin insulating film and the wiring layer made of the conductor film are alternately laminated by the method for manufacturing a multilayer wiring board according to any one of the above, at least one of the through hole portion and the blind hole processing One or both of them are formed.
[0022]
Moreover, in invention of Claim 8, said Claims 1-. 6 In the multilayer wiring board manufacturing method according to any one of the above, in at least one of a rigid and a flexible circuit board in which insulating layers made of a resin insulating film and wiring layers made of a conductor film are alternately laminated, A multilayer wiring board having a hole for conducting a metal wiring layer.
[0023]
According to a ninth aspect of the present invention, in a laser drill apparatus for use in manufacturing a multilayer wiring board in which insulating layers made of a resin insulating film and wiring layers made of a conductor film are alternately laminated, from the wiring layer side of the multilayer wiring board. After forming a hole for forming a via hole by using an ultraviolet laser drill means using a single wavelength of 355 nm or less, the laser beam is spirally moved with a dross generated at the opening end of the hole by using the laser drill means. Removed by At the same time that the hole end dross is processed, the upper wiring layer is tapered. This is a laser drill device characterized by the above.
[0024]
In the invention of claim 10, a multilayer wiring board in which insulating layers made of a resin insulating film and wiring layers made of a conductor film are alternately laminated is formed on an upper surface wiring layer, an intermediate resin insulating layer, and a hole opening end dross. The laser drilling is performed in order. 9 It is a laser drill apparatus of description.
[0025]
In the invention of claim 11, a laser processing diameter larger by 0.1 to 100 μm than the hole processing diameter is used when removing dross generated at the opening end of the hole than the laser processing diameter when forming the hole. Claims 9 or 10 It is a laser drill apparatus of description.
[0026]
According to a twelfth aspect of the present invention, the dross at the opening end is formed after the formation of the individual holes in the same plane in the multilayer wiring board in which the insulating layers made of the resin insulating film and the wiring layers made of the conductor film are alternately laminated. It is characterized by performing at least one of burst processing to be removed or cycle processing to remove dross at all opening ends of the holes again in the same locus after forming all the holes in the same plane in the multilayer wiring board. Claims 9-11 The laser drill apparatus according to any one of the above.
[0027]
In the invention of claim 13, In the method of manufacturing a multilayer wiring board in which insulating layers made of a resin insulating film and wiring layers made of a conductor film are alternately laminated, the insulating layer is made of polyimide tape with a double-sided copper foil (copper / polyimide / copper → 9 / 30/9 μm film thickness), hole-stopping processing (blind via processing) using an ultraviolet laser with a wavelength of 355 nm, and processing 1000 holes into a pattern with a 400 μm pitch grid, and one hole In the processing of the upper surface copper foil layer, a laser beam having an energy density of 10 J / cm 2 is irradiated in a burst mode under a processing condition of 8 shots, and a laser beam of 2 J / cm 2 is processed in a processing of a polyimide layer in a burst mode. Is a process for forming a hole for forming a blind via hole having a diameter of φ50 μm and a hole bottom diameter of 2 is φ30 μm. The laser beam is returned to a density of 10 J / cm 2 and irradiated by two shots, and the ratio (θ2 / θ1) of the taper angle in the upper copper foil layer to the taper angle in the polyimide layer as the intermediate resin insulation layer is 0.55 to 0.60. Forming a hole for forming a blind via hole in a multilayer wiring board, comprising: It is.
[0029]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the manufacturing method (especially dross removal) of the multilayer wiring board of this invention is demonstrated. Subtractive and semi-additive methods are currently promising when forming fine wiring. In the subtractive method, copper wiring is completed on a copper foil by a resist coating-exposure-development-etching process. On the other hand, in the semi-additive method, copper wiring is completed by electroless plating-resist coating-exposure-development-electrolytic plating-soft etching on a resin. Copper deposited on the entire surface by electroless plating becomes a copper wiring having an independent pattern by soft etching. Furthermore, the plating when forming the copper wiring by the semi-additive method takes a very long process time and becomes an obstacle to improving the productivity.
[0030]
In adopting the subtractive method for wiring formation, direct processing of copper foil is required for laser drilling. CO ₂ Since the laser does not have an absorption wavelength in a metal, it is necessary to process the surface of the copper foil by performing a blackening treatment or the like. In this respect, since an ultraviolet laser has an absorption wavelength in a metal, laser drilling can be performed without performing a special treatment such as a blackening treatment.
[0031]
Since the ultraviolet laser beam machine uses pulse oscillation, the hole stop processing (blind via) as shown in FIG. 1 is performed by changing the pulse energy of the laser beam per unit area between the copper foil layer and the resin layer. Can do. For example, an energy of about 10 J / m 2 or more is required for copper foil layer processing using the third harmonic (wavelength 355 nm) of YAG, and about 1-3 J / m 2 is required for resin processing. Using this energy difference, a blind via can be formed by irradiating the upper copper foil layer with a pulse shot number that can process an energy of 10 J / m 2 and then a resin layer of 3 J / m 2. Further, the intensity distribution of the laser beam is stronger at the center of the hole and becomes weaker toward the end of the hole. That is, since the processing does not proceed in the portion where the laser intensity is weak, the hole portion has a tapered shape.
[0032]
A dross having a raised shape as shown in FIG. 1 is generated at the opening end of the hole after the metal layer direct processing. The raised film thickness is about 1 to 3 μm. In order to remove this dross with a laser drill, it is conceivable to irradiate several pulses of laser light having a diameter suitable for the range in which the dross extends. That is, in the hole forming process, first, copper foil processing is irradiated with energy of 10 J / m 2, second resin layer processing is about 1-3 J / m 2, and third is dross removal to irradiate 10 J / m 2 of energy. The part can be formed and dross removal can also be performed by laser drilling (see FIG. 2). Considering the absorption wavelength of copper, it is effective to use a laser beam having an ultraviolet wavelength of 355 nm or less. CO ₂ Since the laser does not have an absorption wavelength, it is necessary to blacken the dross again, resulting in an increase in the number of processes. It should be noted in the process of removing dross directly by laser drilling that if the number of pulses during dross removal is excessively increased, the copper foil at the bottom of the hole is processed simultaneously with the dross, and the blind via penetrates. It is possible to end up. The processing rate per pulse in laser drilling depends on the laser oscillation conditions, but processing rates less than 1 μm are easy. For this reason, it is desirable to determine the appropriate value of the number of pulses for dross removal after accurately grasping the film thickness of the dross. Moreover, you may irradiate the pulse energy lower than the pulse energy at the time of 1st copper foil processing as pulse energy of dross removal. For example, if it is 10 J / m 2 at the time of processing the first copper foil, it is to irradiate pulse energy of 8 to 9 J / m 2 at the time of dross removal.
[0033]
Also, if laser drilling with a diameter larger than the dross generation range is performed, there is a possibility that the film thickness of the copper foil that should be the wiring in the subsequent wiring forming process may be reduced. It is desirable that the diameter is the diameter of dross generation (7 in FIG. 1). On the other hand, if the initial film thickness of the copper wiring layer is not a problem compared to the processed film thickness at the time of dross removal, the diameter of the laser beam for dross removal need not be determined.
[0034]
In addition, in the case of a processing method (trepanning method) in which a laser beam of a certain unit diameter is spirally moved and expanded to a desired hole diameter (trepanning method), when the second resin processing is performed, the unit diameter is similarly spirally moved only on the dross. Dross removal can be performed. In this case, since only the dross is processed, the hole bottom is not processed.
[0035]
By performing dross removal with a laser drill means, three-stage laser light irradiation is required. In other words, the processing throughput may be reduced, but the number of irradiation pulses for dross removal depends on the film thickness of the dross, but is a few pulses, so it is relatively smaller than the number of pulses when processing the metal layer and the resin layer. Just the number of pulses. The processing throughput in the blind via processing by the metal layer + resin layer + dross removal is about 90 to 99%, compared to the blind via processing by only the metal layer + resin processing.
[0036]
Also, the processing sequence of metal layer + resin layer + dross removal processing is the same trajectory after processing all hole coordinate positions with the burst mode in which the next hole is processed after forming one hole and the processing conditions of the metal layer. A cycle mode is conceivable in which the resin layer is processed under the resin processing conditions, and the hole coordinate position is processed again by returning to the metal layer processing conditions again. In the burst mode, the problem of processing position accuracy is eliminated, but there is a possibility of time delay for switching processing conditions in three stages for each hole. In the cycle mode, metal layer → resin layer → dross removal is processed under each processing condition, so processing time loss due to switching of conditions is reduced, but the pattern of the same hole is made the same locus three times. Therefore, the processing position accuracy becomes a problem. The current laser drilling (means) processing conditions (processing diameter, processing energy, laser oscillation frequency, number of pulses, etc.) are controlled by software on the computer, so there is almost no loss of processing time when switching processing conditions. . Laser drilling of holes in burst mode is desirable.
[0037]
Further, the laser drilling method including the dross removing step is not limited to the above.
[0038]
Depending on the processing conditions (processing diameter, processing energy, laser oscillation frequency, number of pulses, etc.) of laser drilling (means), the upper wiring layer can be tapered. When the top wiring layer + intermediate resin insulating layer is subjected to blind via processing, the hole formed in the top wiring layer is mask-transferred to process the intermediate resin insulating layer. Further, since the energy density of the laser beam is lower when the intermediate resin insulating layer is processed than when the upper surface wiring layer is processed, the intermediate resin insulating layer is tapered. (In FIG. ₁ <Θ ₂ ) Furthermore, this taper angle relationship depends on the laser processing conditions. ₂ / Θ ₁ = 0.40 to 1.00.
[0039]
In a conventional method for manufacturing a via hole, after forming a hole for the via hole, the inside of the hole is covered with a metal by using an electrochemical method (mainly, plating technique). Since the method uses metal deposition in the chemical solution, the flow of the chemical solution into the hole is important. The aspect ratio is high in the hole for the minute via hole, and there is a high possibility that a stagnation point having no chemical flow is generated near the bottom of the hole (FIG. 4). At the stagnation point, no new liquid is supplied, which greatly hinders metal deposition.
[0040]
Here, the aspect ratio can be reduced by providing the upper wiring layer with a taper angle. In other words, improving the liquid flow by chemical treatment leads to an improvement in product yield.
[0041]
Hereinafter, a multilayer wiring board using the dross removing method of the present invention will be described. By processing the first laser drill on the metal layer (copper), then the second laser drill on the insulating layer, and finally the third laser drill on the dross part with the appropriate laser dose and number of shots. The hole from which the dross is removed can be formed only by the laser drill means. By removing dross by laser drilling (means), a dedicated dross removal process such as physical polishing and chemical polishing after laser drilling is omitted, and the productivity of the product is improved. In addition, by omitting the dross removal step, damage to the product substrate that occurs through the dross removal step (substrate shrinkage due to physical polishing, over-corrosion to the wiring part due to chemical polishing, surface modification and resin layer removal) (Absorption of moisture) can be avoided. That is, it leads to the manufacturing stability of a product.
[0042]
Moreover, since the treatment diameter at the time of dross removal is larger than at the time of blind via formation, the upper surface copper foil layer can be provided with a taper angle. Since the aspect ratio of the blind via formed by forming the taper angle on the upper surface copper foil layer is reduced by the thickness of the upper surface copper foil layer, it becomes easy to supply a new solution for the chemical treatment by the plating process in the subsequent step.
[0043]
In forming holes, blind via processing (blind hole processing) and through hole processing (through hole processing) are currently mainstream, but the dross removal method in the laser drill means (process) is compatible with either hole formation. Is possible. Also, it is an effective method for both rigid multilayer wiring boards and flexible multilayer wiring boards.
[0044]
【Example】
Using polyimide tape with double-sided copper foil (copper / polyimide / copper → 9/30 / 9μm thickness, Mitsui Chemicals Neoprex), hole stop processing (blind via processing) as shown in FIG. 1 has a wavelength of 355 nm Were used to form a pattern in which 1000 holes had a lattice shape with a pitch of 400 μm. One hole was irradiated in a burst mode under the processing conditions of 8 shots of laser light with an energy density of 10 J / cm 2 for processing the upper copper foil layer and 30 shots of 2 J / cm 2 for processing the polyimide layer. Since the processing was performed while changing the energy density, the bottom copper foil was not processed, and a hole for forming a blind via hole was formed. The hole opening diameter 1 was φ50 μm, and the hole bottom diameter 2 was φ30 μm. At this time, the film thickness of the dross generated at the opening end of the hole at an arbitrary position was measured with a scanning electron microscope and a laser microscope, and found to be 1.2 to 2.2 μm. The dross generation range 7 was about φ70 μm.
[0045]
Next, the processing conditions were changed to a processing diameter of φ70 μm, the laser beam was returned to an energy density of 10 J / cm 2, and two shots were irradiated (see FIG. 2). Because of the punching process, the copper foil at the bottom of the hole was processed again, but there was no problem even if the inside of the hole was filled with copper by plating. Further, the ratio of the taper angle in the upper copper foil layer at this time and the taper angle in the polyimide layer as the intermediate resin insulation layer (θ ₂ / Θ ₁ ) Was 0.55 to 0.60.
[0046]
In order to compare the plating coverage with the substrate from which the dross has been removed by the laser drill, 8 shots of laser light with an energy density of 10 J / m2 are used to process the upper copper foil layer, and 2 J / m2 laser light is used to process the polyimide layer. Under the processing conditions of 30 shots, # 1000 physical polishing was performed on the entire surface of the substrate irradiated in the burst mode. An abrasive kneading buff was used considering that the abrasive grains do not enter the hole after dross polishing. In addition, a sample substrate without dross removal was also prepared for comparative evaluation of plating coverage.
[0047]
The inside of the holes in the two types of sample substrates was similarly subjected to desmear treatment with an aqueous permanganate solution. Thereafter, electrolytic copper plating was performed in order to establish interlayer conduction between the upper and lower metal layers. The composition of the plating solution is copper sulfate 225 g / L, sulfuric acid 55 g / L, chloride ion 60 mg / L, additive 20 mL, the bath temperature is 25 ° C., and the cathode current density is 1.0 A / dm 2 with stirring for 60 minutes. Electroplating was performed. The sample was dried at 90 ° C. for 10 minutes after the electroplating.
[0048]
The two types of samples were filled in a resin, heated and cured at 50 ° C. for 1 hour, polished with a grinder, and the copper filling defect rate in the hole was examined. The copper filling defect rate of the substrate from which dross was removed by laser drilling and the substrate from which dross was removed by physical polishing was 0.5 to 3%. However, the copper filling defect rate of the substrate from which dross was not removed was 50 to 60%. This is presumably because the electric field concentration occurred in the convex part of the dross in the electrolytic plating process, and the growth of electrolytic copper at the hole opening was faster than the electrolytic copper growth at the hole bottom, leaving a void inside the hole.
[0049]
Further, a circuit was formed by forming a 1000-hole grid pattern into a chain pattern in which upper and lower wiring layers are alternately connected, and a continuity test was performed using a tester. Only samples that were completely conducted were accepted, and those that were disconnected were considered defective. Samples that had dross removed by laser drilling and had a taper angle had a yield of 95%, while samples that had no dross removed had a yield of 67%.
[0050]
In addition, since dross is removed by laser drilling, the physical polishing process, which is a dross removal dedicated process, is omitted, and the manufacturing process can be shortened. The time required for producing the sample substrate from the laser processing step to the electrolytic plating step was reduced by 15%.
[0051]
A heat cycle test and an insulation reliability test were performed as a substrate reliability evaluation test. The heat cycle test is performed at -65 ° C. × 30 min to 165 ° C. × 30 min, and the insulation reliability test is performed with a comb pattern of L / S = 50 μm / 50 μm between upper and lower layers at 80 ° C./85%/50 V after 1000 hours. The value of was measured. The test results are shown in Table 1.
[0052]
[Table 1]

[0053]
【Effect of the invention】
According to the method for manufacturing a multilayer wiring board and the laser drill apparatus of the present invention, it is possible to omit a dross removal dedicated process (for example, physical polishing or chemical polishing) after laser drilling, and a metal wiring layer and a resin insulating layer are provided. In the multilayer wiring board formed by alternately laminating, the production of the substrate can be shortened, and the liquid flow by the chemical treatment after the formation of the hole can be improved, so that the yield is improved. Further, by shortening the substrate manufacturing, it is possible to avoid loads on the substrate (shrinkage and surface modification of the substrate, moisture absorption to the resin insulating layer).
[0054]
[Brief description of the drawings]
1A and 1B are a top view and a cross-sectional view of hole stop (blind via) processing in a resin flexible substrate with a double-sided copper foil.
FIG. 2 is an explanatory view showing dross removal by laser drilling.
FIG. 3 shows the taper angle (θ of the upper wiring layer after laser drilling; ₂ ) And taper angle (θ ₁ FIG.
FIG. 4 is an explanatory view showing a chemical flow during the plating process on a hole having a taper angle.
[Brief description of symbols]
1 Hole opening diameter
2 Hole bottom diameter
3 Top metal wiring layer
4 Insulating resin layer
5 Bottom metal wiring layer
6 Dross
7 Dross diameter
8 Laser pulse light for upper surface metal wiring layer processing
9 Laser pulse light for insulating resin layer processing
10 Laser pulse light for dross removal

Claims (13)

  In a method for manufacturing a multilayer wiring board in which insulating layers made of a resin insulating film and wiring layers made of a conductor film are alternately laminated, laser drilling is performed on a hole for forming a via hole from the wiring layer side of the multilayer wiring board. After the formation, the laser drill is used to remove the dross generated at the hole opening end, and the hole opening end dross is processed, and at the same time, a taper angle is formed on the upper wiring layer. Method.   2. The method of manufacturing a multilayer wiring board according to claim 1, wherein the laser drill is an ultraviolet laser drill using a single wavelength of 355 nm or less.   The order in which laser drilling is performed on a multilayer wiring board in which insulating layers made of resin insulating films and wiring layers made of conductor films are alternately laminated is the upper surface wiring layer, the intermediate resin insulating layer, and the hole opening end dross. A method for manufacturing a multilayer wiring board according to claim 1 or 2.   The laser processing diameter larger by 0.1 to 100 µm than the hole processing diameter is used when removing dross generated at the opening end of the hole than the laser processing diameter at the time of forming the hole. The manufacturing method of the multilayer wiring board in any one of -3.   Burst processing to remove dross at the open end after forming individual holes in the same plane in a multilayer wiring board in which insulating layers made of resin insulating films and wiring layers made of conductor films are alternately laminated, or multilayer wiring board 5. At least one of the cycle processing for removing dross at all the hole openings at the same locus after forming all the holes in the same plane is performed. The manufacturing method of the multilayer wiring board as described in any one of.   In the hole for forming the via hole, the ratio of the taper angle of the upper surface wiring layer to the taper angle of the intermediate resin insulating layer (intermediate resin insulating layer / upper surface wiring layer) is 0.40 to 1.00. The manufacturing method of the multilayer wiring board in any one of Claims 1-5.   According to the method for manufacturing a multilayer wiring board according to any one of claims 1 to 6, in the multilayer wiring board in which insulating layers made of a resin insulating film and wiring layers made of a conductor film are alternately laminated, A multilayer wiring board in which at least one or both of blind hole processing are formed.   7. A method of manufacturing a multilayer wiring board according to claim 1, wherein at least one of a rigid and a flexible circuit board in which insulating layers made of a resin insulating film and wiring layers made of a conductor film are alternately laminated. On the other hand, a multilayer wiring board characterized in that a hole is formed for conducting the upper and lower metal wiring layers. In a laser drill apparatus used for manufacturing a multilayer wiring board in which an insulating layer made of a resin insulating film and a wiring layer made of a conductor film are alternately laminated, a hole for forming a via hole is formed from the wiring layer side of the multilayer wiring board. After forming using an ultraviolet laser drill means using a single wavelength of 355 nm or less, the laser drill means is used to remove the dross generated at the opening end of the hole by spirally moving the laser beam, thereby opening the hole. A laser drill device characterized in that a taper angle is given to an upper surface wiring layer simultaneously with processing an end dross .   Laser drilling a multilayer wiring board in which insulating layers made of a resin insulating film and wiring layers made of a conductor film are alternately laminated in the order of the upper surface wiring layer, the intermediate resin insulating layer, and the hole opening end dross. The laser drill device according to claim 9.   10. The laser processing diameter larger by 0.1 to 100 μm than the hole processing diameter is used when removing dross generated at the opening end of the hole than the laser processing diameter when forming the hole. Or the laser drill apparatus of 10.   Burst processing to remove dross at the open end after forming individual holes in the same plane in a multilayer wiring board in which insulating layers made of resin insulating films and wiring layers made of conductor films are alternately laminated, or multilayer wiring board The cycle machining for removing all the hole-opening drosses again at the same locus after forming all the holes in the same plane is performed. The laser drill apparatus as described in. In the method of manufacturing a multilayer wiring board in which insulating layers made of resin insulating films and wiring layers made of conductive films are alternately laminated,
The insulating layer uses a double-sided copper foil-coated polyimide tape (copper / polyimide / copper → 9/30/9 μm film thickness), and uses a UV laser with a wavelength of 355 nm for hole-stopping (blind via processing), 1000 Processing the holes into a 400 μm pitch grid pattern;
For one hole, the upper surface copper foil layer was processed with 8 shots of laser light with an energy density of 10 J / cm2, and the polyimide layer was processed with 2 J / cm2 laser light in 30 shots in a burst mode. Forming a hole for forming a blind via hole having a part opening diameter 1 of φ50 μm and a hole bottom diameter 2 of φ30 μm;
The processing conditions were changed to a processing diameter of φ70 μm, the laser beam was returned to an energy density of 10 J / cm2, and irradiated with two shots. The ratio of the taper angle in the upper copper foil layer to the taper angle in the polyimide layer as the intermediate resin insulation layer (θ2 / θ1) Forming a hole for forming a blind via hole having a thickness of 0.55 to 0.60.

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