JP4428783B2 - Method for manufacturing printed wiring board - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method of manufacturing a printed wiring board in which through holes for through holes are formed on a core substrate by a laser.
[0002]
[Prior art]
Multilayer build-up wiring boards are used for package substrates that require high performance. The multilayer build-up wiring board is formed by building up an interlayer resin insulating layer including wiring one by one on a core substrate provided with a through hole. The through hole provided in the core substrate was formed by drilling a through hole in the core substrate with a drill. However, a drill cannot form fine through-holes with a narrow pitch, and is not able to satisfy the performance required for high integration of printed wiring boards. For this reason, research has been conducted on drilling through holes in the core substrate using a laser.
[0003]
[Problems to be solved by the invention]
However, when a through hole is formed by a laser, disconnection may occur in a heat cycle and the reliability is low. When the cause of this disconnection was studied, it was found that bubbles were mixed in the through hole.
[0004]
The present inventor further studied the cause of air bubbles, and found that when a through hole was drilled with a laser in a copper-clad laminate forming the core substrate, the copper foil extended inward from the opening of the through hole. It was found that this was due to the remaining burr part. That is, as shown in FIG. 16A, when the through hole 233 is formed by laser in the core substrate 230 formed by laminating the copper foil 232, the burr 232b of the copper foil 232 remains in the opening of the through hole 233. . Then, as shown in FIG. 16B, when the plating film 235 is formed to form the through hole 236, bubbles E may remain between the burr 232b and the plating film 235. Further, as shown in FIG. 16C, when the through hole 236 is filled with the resin filler 240, bubbles E remain between the back surface of the burr 232b portion and the resin filler 240, or FIG. As shown in FIG. 16 (D), it was found that filling was difficult due to the burr 232b portion of the copper foil extending inward, and the resin filler 240 was not filled in the through hole 236.
[0005]
The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a method for manufacturing a printed wiring board capable of achieving both high reliability and wiring density.
[0008]
[Means for Solving the Problems]
  Claim1Is a method for producing a printed wiring board, comprising at least the following steps (A) to (D):
(A) The surface of the substrate on which the metal film is laminatedWith blackening reduction treatmentRoughening process;
(B) irradiating the substrate with a laser to form a plurality of through holes to be through holes;
(C) a step of desmearing the inside of the through-hole while simultaneously dissolving the metal film extending inward from the opening of the through-hole using an oxidizing agent;
(D) A step of filling the through hole with a filler.
[0009]
  Claim1In this invention, the surface of the substrate on which the metal film is laminated is roughened, and then a laser beam is irradiated to form a through hole. Therefore, reflection is suppressed and the metal film extending inward from the opening of the through hole is formed. The burr part does not become large. Further, since the burr portion of the metal film is dissolved, no bubbles remain when the conductor layer is formed in the through hole or when the filler is filled in the through hole, and the burr is the starting point. Since no corner cracks occur, the reliability of the through hole can be improved.
[0013]
  Claim1In this invention, since the oxidizing agent is used, the desmear treatment in the through-hole can be performed simultaneously with the dissolution of the burr portion of the metal film extending inward from the opening of the through-hole.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, a printed wiring board and a manufacturing method thereof according to an embodiment of the present invention will be described with reference to the drawings.
First, the configuration of the printed wiring board according to the first embodiment of the present invention will be described with reference to FIG. 7 showing a cross-sectional view of the printed wiring board 10 used as a package substrate.
As shown in FIG. 7, in the printed wiring board 10, through holes 36 are formed in the core substrate 30, and conductor circuits 34 are formed on both surfaces of the core substrate 30. On the core substrate 30, a lower-layer interlayer resin insulation layer 50 in which via holes 60 and conductor circuits 58 are formed is disposed. On the lower interlayer resin insulation layer 50, an upper interlayer resin insulation layer 150 in which via holes 160 and conductor circuits 158 are formed is disposed. A solder resist layer 70 is disposed on the upper interlayer resin insulation layer 150.
[0015]
On the upper surface of the printed wiring board 10, solder bumps 76U for connection to the IC chip are disposed in the openings of the solder resist layer 70. On the other hand, solder bumps 76D for connection to the daughter board are disposed in the opening of the solder resist layer 70 on the bottom surface of the package substrate.
[0016]
As shown in FIG. 6, the solder bumps 76 </ b> U are connected to the through holes 36 via via holes 160 formed in the interlayer resin insulation layer 150 and via holes 60 formed in the interlayer resin insulation layer 50. On the other hand, the solder bumps 76D are connected to the through holes 36 via via holes 160 formed in the interlayer resin insulation layer 150 and via holes 60 formed in the interlayer resin insulation layer 50.
[0017]
In the printed wiring board of the first embodiment, since the through holes 36 are formed by a laser, the through holes 36 having a small diameter can be arranged at a narrow pitch, and high integration is achieved.
[0018]
Hereinafter, a method for manufacturing the printed wiring board 10 shown in FIG. 7 will be described with reference to the drawings.
Here, first, a schematic configuration of a carbon dioxide laser in which through holes are formed in the core substrate 30 and the interlayer resin insulating layer 50 will be described with reference to FIG.
Various types of laser devices can be used. In the first embodiment, ML605GTX manufactured by Mitsubishi Electric is used as the laser device. As the CO2 laser transmitter 180, ML5003D2 manufactured by Mitsubishi Electric is used.
[0019]
The light emitted from the laser oscillator 180 enters the galvano head 170 via a transfer mask 182 for making the focal point on the substrate clear. The galvano head 170 is composed of a pair of galvano mirrors, a galvano mirror 174X that scans laser light in the X direction and a galvano mirror 174Y that scans in the Y direction. It is driven by motors 172X and 172Y. The motors 172X and 172Y are configured to adjust the angles of the mirrors 174X and 174Y according to a control command from a control device (not shown) and to send a detection signal from a built-in encoder to the computer side.
[0020]
The laser light is scanned in the XY directions via the galvanometer mirrors 174X and 174Y, passes through the f-θ lens 176, and forms the through-hole 33 for the through hole in the core substrate 30. The core substrate 30 is placed on an XY table 190 that moves in the XY direction.
[0021]
Subsequently, the manufacturing process of the printed wiring board according to the first embodiment of the present invention will be described with reference to FIGS. In the first embodiment, the printed wiring board is formed by a semi-additive method.
[0022]
(1) A copper clad laminate in which 18 μm copper foil 32 is laminated on both surfaces of a substrate 30 made of glass epoxy resin or BT (bismaleimide triazine) resin having a thickness of 0.8 mm as shown in FIG. 30A was the starting material. First, this copper clad laminate 30A is made of NaOH (10 g / l), NaClO.₂ (40 g / l), Na_Three PO_Four Blackening treatment using an aqueous solution containing (6 g / l) as a blackening bath (oxidation bath), and NaOH (10 g / l), NaBH_Four A reduction treatment using an aqueous solution containing (6 g / l) as a reduction bath was performed to form a roughened surface 32β on the entire surface of the copper foil 32 (see FIG. 1B). Here, the roughened surface is formed by the blackening reduction treatment, but the roughened surface can also be provided by etching described later or electroless plating.
[0023]
(2) Next, the substrate 30 is placed on the XY table 190 of the carbonic acid laser device described above with reference to FIG.₂ Using a gas laser, through holes 33 having a diameter of 100 to 200 μm are formed at a pitch of 300 μm under the conditions of a single hat mode, a pulse width of 50 to 200 μs, and 5 to 20 shots (FIG. 1C). In the manufacturing method of the first embodiment, since the surface of the copper foil 32 is roughened and then irradiated with a laser to form the through-hole 33, reflection is suppressed and the inner side extends from the opening of the through-hole 33. The burr portion of the copper foil 32 does not become large. In the present embodiment, the roughened surface 32β is formed on the copper foils 32 on both sides. However, if only the surface irradiated with the laser is roughened, the above effect can be obtained.
[0024]
(3) Then, the burr portion of the copper foil 32 extending from the opening to the inside from the opening of the through hole 33 is dissolved and removed with an etching solution (see FIG. 1D). Here, ferric chloride, cupric chloride, hydrogen peroxide / sulfuric acid, alkaline etchant, or the like can be used as an etching solution for dissolution. Further, burrs can be removed by using an acid such as sulfuric acid, nitric acid or hydrochloric acid. Further, it is possible to remove burrs using an oxidizing agent such as chromium or permanganate. When an oxidizing agent is used, desmear treatment in the through-hole 33 can be performed simultaneously with the dissolution of the burr portion. In this embodiment, since the burr | flash part is melt | dissolved, the opening property of the through-hole 33 becomes high.
[0025]
Then, after immersing in an electroless plating solution and forming a through hole 36 by depositing a copper plating film on the side wall of the through-hole 33 (FIG. 2A), the substrate is etched into a pattern according to a conventional method. An inner layer copper pattern (lower conductor circuit) 34 was formed on both sides of the substrate (FIG. 2B).
[0026]
(4) The substrate on which the lower conductor circuit 34 is formed is washed with water and dried, and then an etching solution is sprayed on both surfaces of the substrate to spray the surface of the lower conductor circuit 34, the surface of the land 36a of the through hole 36, and the inner wall. By etching, a roughened surface 34β was formed on the entire surface of the lower conductor circuit 34, and 36β was formed on the land 36a and the inner wall of the through hole 36 (see FIG. 2C). As an etching solution, a mixture of 10 parts by weight of imidazole copper (II) complex, 7 parts by weight of glycolic acid, 5 parts by weight of potassium chloride and 78 parts by weight of ion-exchanged water was used. As the etchant, for example, all of those used for printed wiring boards such as hydrogen peroxide, sulfuric acid, ferric chloride, and cupric chloride can be used.
[0027]
(5) The resin filler 40 containing epoxy resin as a main component was applied to both sides of the substrate using a printing machine to fill the space between the lower conductor circuits 34 or the through holes 36, followed by heat drying. . That is, by this step, the resin filler 40 is filled between the lower conductor circuits 34 or in the through holes 36 (see FIG. 2D). In this embodiment, since the burr | flash part of the copper foil 32 extended inside from the opening part of the through-hole 33 is removed, when the resin filler 40 is filled into the through-hole 33, the copper foil 32 and resin filling are carried out. Bubbles do not remain between the material 40 and the reliability of the through hole 36 can be improved.
[0028]
(6) One side of the substrate after the processing of (5) is filled with resin on the surface of the lower conductor circuit 34 or the land surface of the through hole 36 by belt sander polishing using belt polishing paper (manufactured by Sankyo Rikagaku Co., Ltd.). Polishing was performed so that the material 40 did not remain, and then buffing was performed to remove scratches caused by the belt sander polishing. Such a series of polishing was similarly performed on the other surface of the substrate. Then, the filled resin filler 40 was cured by heating (see FIG. 3A).
[0029]
In this way, the surface layer portion of the resin filler 40 filled in the through holes 36 and the like and the roughened layer 34β on the upper surface of the lower conductor circuit 34 are removed to smooth both surfaces of the substrate, and the resin filler 40 and the lower conductor circuit 34 are smoothed. A wiring substrate is obtained in which the side surface of the through hole 36 is firmly adhered via the roughened surface 34β, and the inner wall surface of the through hole 36 and the resin filler 40 are firmly adhered via the roughened surface 36β.
[0030]
(7) Next, the same etching solution as that used in (4) above is sprayed on both surfaces of the substrate after the processing in (6) above, and the surface of the lower conductor circuit 34 once flattened is sprayed. And the surface of the land 36a of the through hole 36 are etched to form the roughened surface 34β on the entire surface of the lower conductor circuit 34 and the roughened layer 36β on the surface of the land 36a of the through hole (see FIG. 3B). ).
[0031]
In this embodiment, the roughened surface is formed by the blackening reduction process in the step (1) and by etching in the step (7), but instead, the roughened layer is formed by electroless plating. It can also be formed. In this case, the substrate 30 on which the conductor circuit 34 is formed is subjected to alkali degreasing and soft etching, and then treated with a catalyst solution composed of paradium chloride and an organic acid to give a Pd catalyst and activate the catalyst. After that, copper sulfate 3.2 × 10^-2mol / l, nickel sulfate 3.9 × 10^-3mol / l, complexing agent 5.4 × 10^-2mol / l, sodium hypophosphite 3.3 × 10^-1mol / l, boric acid 5.0 × 10^-1It is immersed in an electroless plating solution consisting of mol / l, a surfactant (manufactured by Nissin Chemical Industry, Surfir 465) 0.1 g / l, PH = 9, and once every 4 seconds after immersion Then, a needle-like alloy coating layer made of Cu—Ni—P and a roughening layer 42 are provided on the surfaces of the lands 36 a of the conductor circuit 34 and the through hole 36 by longitudinal and lateral vibration.
[0032]
(8) Next, a pressure of 5 kg / cm is applied to both sides of the substrate that has undergone the above-described process while the temperature of a 50 μm-thick thermosetting cycloolefin resin sheet is raised to a temperature of 50 to 150 ° C.² And an interlayer resin insulation layer 50 made of cycloolefin resin is provided (see FIG. 3C). Note that the degree of vacuum during vacuum bonding is adjusted to 10 mmHg.
[0033]
(9) Next, CO with a wavelength of 9.4 μm₂ A via hole opening 48 having a diameter of 80 μm was provided in the interlayer resin insulating layer 50 made of cycloolefin resin under the conditions of a beam diameter of 5 mm, a pulse width of 50 μs, a mask hole diameter of 0.5 mm, and three shots using a gas laser ( (See FIG. 3D). Thereafter, desmear treatment was performed using oxygen plasma.
[0034]
(10) Next, plasma processing was performed using SV-4540 manufactured by Nippon Vacuum Technology Co., Ltd. to roughen the surface of the interlayer resin insulation layer 50 (see FIG. 4A). At this time, argon gas was used as an inert gas, and plasma treatment was performed for 2 minutes under the conditions of power 200 W, gas pressure 0.6 Pa, and temperature 70 ° C.
[0035]
(11) Next, using the same apparatus, after replacing the argon gas inside, sputtering using Ni—Cu alloy as a target was performed under conditions of atmospheric pressure 0.6 Pa, temperature 80 ° C., power 200 W, and time 5 minutes. The Ni—Cu alloy layer 52 was formed on the surface of the polyolefin-based interlayer resin insulation layer 50. At this time, the thickness of the formed Ni—Cu alloy layer 52 was 0.2 μm (see FIG. 4B).
[0036]
(12) A commercially available photosensitive dry film is pasted on both surfaces of the substrate after the above treatment, and a photomask film is placed thereon, and 100 mJ / cm.² Then, it was developed with 0.8% sodium carbonate to form a pattern of plating resist 54 having a thickness of 15 μm (see FIG. 4C).
[0037]
(13) Next, electroplating was performed under the following conditions to form an electroplated film 56 having a thickness of 15 μm (see FIG. 5A). In addition, with this electroplating film 56, the thickness of the portion that becomes the conductor circuit 58 and the plating filling of the portion that becomes the via hole 60 are performed in the steps described later. The additive in the electroplating aqueous solution is Kaparaside HL manufactured by Atotech Japan.
[0038]
[Electroplating aqueous solution]
Sulfuric acid 2.24 mol / l
Copper sulfate 0.26 mol / l
Additive 19.5 ml / l
[Electroplating conditions]
Current density 1 A / dm²
65 minutes
Temperature 22 ± 2 ° C
[0039]
(14) Next, after removing the plating resist 54 with 5% NaOH, the Ni—Cu alloy layer 52 existing under the plating resist 54 is etched using a mixed solution of nitric acid, sulfuric acid and hydrogen peroxide. The conductive circuit 58 (including the via hole 60) having a thickness of 16 μm made of the electrolytic copper plating film 56 and the like was formed (see FIG. 5B).
[0040]
(15) Subsequently, by repeating the steps (5) to (13), an upper interlayer resin insulation layer 150, a conductor circuit 158 and a via hole 160 were formed (see FIG. 5C).
[0041]
(16) Next, a photosensitizing agent obtained by acrylating 50% of an epoxy group of a cresol novolac type epoxy resin (manufactured by Nippon Kayaku Co., Ltd.) dissolved in diethylene glycol dimethyl ether (DMDG) to a concentration of 60% by weight. 46.67 parts by weight of oligomer (molecular weight: 4000), 15 parts by weight of 80% by weight of bisphenol A type epoxy resin (trade name: Epicoat 1001) dissolved in methyl ethyl ketone, imidazole curing agent (Shikoku Chemicals) Manufactured, product name: 2E4MZ-CN) 1.6 parts by weight, polyfunctional acrylic monomer (manufactured by Nippon Kayaku Co., Ltd., product name: R604) as a photosensitive monomer, polyvalent acrylic monomer (manufactured by Kyoei Chemical Co., Ltd.) , Trade name: DPE6A) 1.5 parts by weight, dispersion antifoaming agent (manufactured by Sannopco, trade name: S-65) 0.71 layer An amount part is placed in a container, and a mixed composition is prepared by stirring and mixing. 2.0 parts by weight of benzophenone (manufactured by Kanto Chemical Co., Inc.) as a photopolymerization initiator and Michler's ketone as a photosensitizer are mixed with this mixed composition. (Kanto Chemical Co., Ltd.) 0.2 parts by weight was added to obtain a solder resist composition (organic resin insulating material) having a viscosity adjusted to 2.0 Pa · s at 25 ° C.
Viscosity measurement was performed using a B-type viscometer (DVL-B type, manufactured by Tokyo Keiki Co., Ltd.). In the case of 4 or 6 rpm, the rotor No. 3 according.
[0042]
(17) Next, the solder resist composition is applied to both sides of the multilayer wiring board in a thickness of 20 μm, and after drying at 70 ° C. for 20 minutes and at 70 ° C. for 30 minutes, the solder resist is applied. A photomask with a thickness of 5 mm on which the pattern of the opening is drawn is brought into close contact with the solder resist layer and 1000 mJ / cm² Were exposed to UV light and developed with DMTG solution to form openings 71U and 71D having a diameter of 200 μm.
Further, the solder resist layer was cured by heating at 80 ° C. for 1 hour, 100 ° C. for 1 hour, 120 ° C. for 1 hour, and 150 ° C. for 3 hours to open the solder pad portion. A solder resist layer (organic resin insulating layer) 70 having a thickness of 20 μm was formed (FIG. 6A).
[0043]
(18) Next, the substrate on which the solder resist layer (organic resin insulating layer) 70 is formed is made of nickel chloride (2.3 × 10^-1mol / l), sodium hypophosphite (2.8 × 10^-1mol / l), sodium citrate (1.6 × 10^-1The nickel plating layer 72 having a thickness of 5 μm was formed in the openings 71U and 71D by immersing in an electroless nickel plating solution containing 0.5 mol / l) of pH = 4.5 (FIG. 6B). Further, the substrate was made of potassium gold cyanide (7.6 × 10 6^-3mol / l), ammonium chloride (1.9 × 10^-1mol / l), sodium citrate (1.2 × 10^-1mol / l), sodium hypophosphite (1.7 × 10^-1The gold plating layer 74 having a thickness of 0.03 μm was formed on the nickel plating layer 72 by immersing in an electroless plating solution containing 1 mol / l) at 80 ° C. for 7.5 minutes.
[0044]
(19) Thereafter, a solder paste is printed in the opening of the solder resist layer 70 and reflowed at 200 ° C. to form solder bumps (solder bodies) 76U and 76D, thereby completing the printed wiring board 10 (FIG. 7). reference).
[0045]
Subsequently, a printed wiring board and a manufacturing method thereof according to the second embodiment of the present invention will be described.
FIG. 15 shows a cross section of a printed wiring board according to the second embodiment applied to a package substrate. The printed wiring board 110 of the second embodiment is the same as that of the first embodiment described above with reference to FIG. However, in the first embodiment, the solder bumps 76D are disposed on the daughter board side, but in the second embodiment, the conductive connection pins 78 are disposed.
[0046]
Next, a method for manufacturing a printed wiring board according to the second embodiment will be described. Here, first, A. B. Production of a resin film for an interlayer resin insulation layer; The preparation of the resin filler will be described.
A. Preparation of resin film for interlayer resin insulation layer
30 parts by weight of bisphenol A type epoxy resin (epoxy equivalent 469, Epicoat 1001 manufactured by Yuka Shell Epoxy Co., Ltd.), 40 parts by weight of cresol novolac type epoxy resin (epoxy equivalent 215, Epiklon N-673 manufactured by Dainippon Ink & Chemicals, Inc.), triazine 30 parts by weight of a structure-containing phenol novolak resin (phenolic hydroxyl group equivalent 120, Phenolite KA-7052 manufactured by Dainippon Ink & Chemicals, Inc.) was dissolved in 20 parts by weight of ethyl diglycol acetate and 20 parts by weight of solvent naphtha with stirring. Thereto, terminal epoxidized polybutadiene rubber (Nagase Kasei Kogyo Denarex R-45EPT) 15 parts by weight, 2-phenyl-4,5-bis (hydroxymethyl) imidazole pulverized product 1.5 parts by weight, finely pulverized silica 2 parts by weight , Silicon Added to prepare an epoxy resin composition agent 0.5 parts by weight.
The obtained epoxy resin composition was applied on a PET film having a thickness of 38 μm using a roll coater so that the thickness after drying was 50 μm, and then dried at 80 to 120 ° C. for 10 minutes, whereby an interlayer resin was obtained. A resin film for an insulating layer was produced.
[0047]
B. Preparation of resin filler
100 parts by weight of bisphenol F type epoxy monomer (manufactured by Yuka Shell Co., Ltd., molecular weight: 310, YL983U), SiO having an average particle diameter of 1.6 μm and a maximum particle diameter of 15 μm or less coated with a silane coupling agent on the surface₂ 170 parts by weight of spherical particles (manufactured by Adtech, CRS 1101-CE) and 1.5 parts by weight of a leveling agent (Perenol S4, manufactured by San Nopco) are placed in a container and mixed by stirring. A 49 Pa · s resin filler was prepared.
As the curing agent, 6.5 parts by weight of an imidazole curing agent (manufactured by Shikoku Kasei Co., Ltd., 2E4MZ-CN) was used.
[0048]
Method for manufacturing printed wiring board
(1) A copper-clad laminate 30A in which 18 μm copper foil 32 is laminated on both surfaces of a substrate 30 made of glass epoxy resin or BT (bismaleimide triazine) resin having a thickness of 0.8 mm is used as a starting material (FIG. 9). (See (A)). First, this copper clad laminate 30A is made of NaOH (10 g / l), NaClO.₂ (40 g / l), Na_Three PO_Four Blackening treatment using an aqueous solution containing (6 g / l) as a blackening bath (oxidation bath), and NaOH (10 g / l), NaBH_Four A reduction treatment using an aqueous solution containing (6 g / l) as a reduction bath was performed to form a roughened surface 32β on the entire surface of the copper foil 32 (see FIG. 9B).
[0049]
(2) Next, the substrate 30 is placed on the table of the carbonic acid laser device described above with reference to FIG. 8, and irradiated with a carbon dioxide gas laser to form the through-hole 33 as shown in FIG. 9C. . In the manufacturing method of the second embodiment, the surface of the copper foil 32 is roughened and then irradiated with a laser to form the through-hole 33. Therefore, reflection is suppressed and the inside of the through-hole 33 extends from the opening. The burr portion of the copper foil 32 does not become large.
[0050]
(3) Then, the burr portion of the copper foil 32 extending from the opening to the inside from the opening of the through hole 33 is dissolved and removed with an etching solution (see FIG. 9D). Here, ferric chloride, cupric chloride, hydrogen peroxide / sulfuric acid, alkali etchant, or the like can be used as an etching solution for dissolution. Further, burrs can be removed by using an acid such as sulfuric acid, nitric acid or hydrochloric acid. Further, it is possible to remove burrs using an oxidizing agent such as chromium or permanganate. When an oxidizing agent is used, desmear treatment in the through-hole 33 can be performed simultaneously with the dissolution of the burr portion. Since the burrs are dissolved, the openability of the through holes 33 is enhanced.
[0051]
Then, after immersing in an electroless plating solution and depositing a copper plating film on the side wall of the through hole 33 to form a through hole 36 (FIG. 10A), the substrate is etched into a pattern according to a conventional method. An inner layer copper pattern (lower conductor circuit) 34 was formed on both sides of the substrate (FIG. 10B).
[0052]
(4) The substrate on which the lower conductor circuit 34 is formed is washed with water and dried, and then an etching solution is sprayed on both surfaces of the substrate to spray the surface of the lower conductor circuit 34, the surface of the land 36a of the through hole 36, and the inner wall. By etching, a roughened surface 34β was formed on the entire surface of the lower conductor circuit 34, and a roughened layer 36β was formed on the land surface and inner wall of the through hole (see FIG. 10C). As an etching solution, a mixture of 10 parts by weight of imidazole copper (II) complex, 7 parts by weight of glycolic acid, 5 parts by weight of potassium chloride and 78 parts by weight of ion-exchanged water was used.
[0053]
(5) After adjusting the resin filler described in B above, within 24 hours after adjustment by the following method, the through hole 36 and the outer edge of the conductor circuit 34 and the conductor circuit non-formed portion on one side of the substrate 30 A layer of the resin filler 40 was formed on the part (see FIG. 10D).
That is, first, the resin filler 40 was pushed into the through hole 36 using a squeegee and then dried at 100 ° C. for 20 minutes. Next, a mask having an opening corresponding to the conductor circuit non-forming portion is placed on the substrate, and a layer of the resin filler 40 is formed on the conductor circuit non-forming portion, which is a recess, using a squeegee. Drying was performed at 20 ° C. for 20 minutes. In this embodiment, since the burr | flash part of the copper foil 32 extended inside from the opening part of the through-hole 33 is removed, when the resin filler 40 is filled into the through-hole 33, the copper foil 32 and resin filling are carried out. Bubbles do not remain between the material 40 and the reliability of the through hole 36 can be improved.
[0054]
(6) The surface of the inner layer copper pattern 4 and the surface of the land 36a of the through-hole 36 are polished on one side of the substrate after the above processing (5) by belt sander polishing using # 600 belt polishing paper (manufactured by Sankyo Rikagaku). Then, the resin filler 40 was polished so as not to remain, and then buffed to remove scratches due to the belt sander polishing. Such a series of polishing was similarly performed on the other surface of the substrate.
Next, heat treatment was performed at 100 ° C. for 1 hour and 150 ° C. for 1 hour to cure the resin filler 40.
[0055]
In this way, the surface layer portion of the resin filler 40 and the surface of the lower conductor circuit 34 formed in the through hole 36 and the conductor circuit non-forming portion are flattened, and the resin filler 40 and the side surface of the lower conductor circuit 34 are roughened. An insulating substrate was obtained in which the inner wall surface of the through hole 36 and the resin filler 40 were firmly adhered to each other through the roughened surface 34β (see FIG. 11A). . That is, by this step, the surface of the resin filler 40 and the surface of the lower conductor circuit 34 are flush with each other.
[0056]
(7) After washing the substrate with water and acid degreasing, soft etching is performed, and then an etching solution is sprayed on both sides of the substrate to spray the surface of the lower conductor circuit 34, the surface of the land 36a of the through hole 36, and the inner wall. By etching, a roughened surface 34β was formed on the entire surface of the lower conductor circuit 34, and a roughened layer 36β was formed on the surface of the land 36a of the through hole (see FIG. 11B).
As an etchant, an etchant (MEC Etch Bond, manufactured by MEC Co.) consisting of 10 parts by weight of imidazole copper (II) complex, 7 parts by weight of glycolic acid, and 5 parts by weight of potassium chloride was used.
[0057]
(8) A resin film for an interlayer resin insulation layer that is slightly larger than the substrate prepared in A above is placed on both sides of the substrate, and the pressure is 4 kgf / cm.² Then, after temporarily crimping and cutting under conditions of a temperature of 80 ° C. and a crimping time of 10 seconds, an interlayer resin insulation layer 50 was formed by pasting using a vacuum laminator apparatus by the following method (FIG. 11C). reference). That is, a resin film for an interlayer resin insulation layer is placed on a substrate with a vacuum degree of 0.5 Torr and a pressure of 4 kgf / cm.² The film was subjected to main pressure bonding under conditions of a temperature of 80 ° C. and a pressure bonding time of 60 seconds, and then thermally cured at 170 ° C. for 30 minutes.
[0058]
(9) A mask 49 having a through hole 49a having a thickness of 1.2 mm is placed on the interlayer resin insulation layer 50. And CO of wavelength 9.4μm₂ A via hole opening 48 having a diameter of 80 μm was formed in the interlayer resin insulating layer 50 with a gas laser under conditions of a beam diameter of 4.0 mm, a pulse width of 8.0 μsec, a mask through-hole diameter of 1.0 mm, and one shot. (See FIG. 11D).
[0059]
(10) The substrate 30 on which the via hole opening 48 is formed is immersed in an 80 ° C. solution containing 60 g / l of permanganic acid for 10 minutes to dissolve and remove the epoxy resin particles present on the surface of the interlayer resin insulation layer 50. As a result, the surface of the interlayer resin insulating layer 50 including the inner wall of the via hole opening 48 was roughened (see FIG. 12A).
[0060]
(11) Next, the substrate after the above treatment was immersed in a neutralization solution (manufactured by Shipley Co., Ltd.) and then washed with water. Further, by applying a palladium catalyst to the surface of the roughened substrate (roughening depth 3 μm), catalyst nuclei are attached to the surface of the interlayer resin insulating layer 50 and the inner wall surface of the via hole opening 48. It was.
[0061]
(12) Next, the substrate was immersed in an electroless copper plating aqueous solution having the following composition to form an electroless copper plating film 51 having a thickness of 0.6 to 3.0 μm over the entire rough surface (FIG. 12 ( B)).
[Electroless plating aqueous solution]
NiSO_Four                   0.003 mol / l
Tartaric acid 0.200 mol / l
Copper sulfate 0.030 mol / l
HCHO 0.050 mol / l
NaOH 0.100 mol / l
α, α'-bipyridyl 40 mg / l
Polyethylene glycol (PEG) 0.10 g / l
[Electroless plating conditions]
40 minutes at 35 ° C liquid temperature
[0062]
(13) A commercially available photosensitive dry film is affixed to the electroless copper plating film 51, a mask is placed, and 100 mJ / cm² Then, a plating resist 54 having a thickness of 30 μm was provided by developing with a 0.8% aqueous sodium carbonate solution (see FIG. 12C).
[0063]
(14) Next, the substrate is washed with 50 ° C. water and degreased, washed with 25 ° C. water and further washed with sulfuric acid, and then subjected to electrolytic copper plating under the following conditions to obtain an electrolytic copper having a thickness of 20 μm. A plating film 56 was formed (see FIG. 13A).
(Electrolytic plating aqueous solution)
Sulfuric acid 2.24 mol / l
Copper sulfate 0.26 mol / l
Additive 19.5 ml / l
(Manufactured by Atotech Japan, Kaparaside HL)
[Electrolytic plating conditions]
Current density 1 A / dm²
65 minutes
Temperature 22 ± 2 ° C
[0064]
(15) After stripping and removing the plating resist 54 with 5% NaOH, the electroless plating film 51 under the plating resist 54 is etched and removed with a mixed solution of sulfuric acid and hydrogen peroxide to remove the electroless copper plating film. A conductor circuit (including via hole 60) 58 having a thickness of 18 μm formed of 51 and electrolytic copper plating film 56 was formed (see FIG. 13B).
[0065]
(16) The same treatment as in (7) was performed, and a roughened surface 62 was formed with an etching solution containing a cupric complex and an organic acid (see FIG. 13C).
[0066]
(17) By repeating the steps (8) to (16), an upper interlayer resin insulation layer 160, a conductor circuit 158 and a via hole 160 were further formed to obtain a multilayer wiring board (FIG. 14A). reference).
[0067]
(18) Next, a solder resist composition similar to that of the first embodiment is applied to both surfaces of the multilayer wiring board at a thickness of 20 μm, and dried at 70 ° C. for 20 minutes and 70 ° C. for 30 minutes. Then, a photomask having a thickness of 5 mm on which the pattern of the opening of the solder resist is drawn is brought into close contact with the solder resist layer and 1000 mJ / cm.² Were exposed to UV light and developed with DMTG solution to form openings 71U and 71D having a diameter of 200 μm.
Further, the solder resist layer is cured by heating at 80 ° C. for 1 hour, at 100 ° C. for 1 hour, at 120 ° C. for 1 hour, and at 150 ° C. for 3 hours. A 20 μm solder resist pattern layer 70 was formed (FIG. 14B). A commercially available solder resist composition can also be used as the solder resist composition.
[0068]
(19) Next, the substrate on which the solder resist layer 70 is formed is nickel chloride (2.3 × 10^-1mol / l), sodium hypophosphite (2.8 × 10^-1mol / l), sodium citrate (1.6 × 10^-1The nickel plating layer 72 having a thickness of 5 μm was formed in the openings 71U and 71D by immersing in an electroless nickel plating solution having a pH of 4.5 containing 1 mol / l). Further, the substrate was made of potassium gold cyanide (7.6 × 10 6^-3mol / l), ammonium chloride (1.9 × 10^-1mol / l), sodium citrate (1.2 × 10^-1mol / l), sodium hypophosphite (1.7 × 10^-1The gold plating layer 74 having a thickness of 0.03 μm was formed on the nickel plating layer 72 by immersing in an electroless gold plating solution containing (mol / l) at 80 ° C. for 7.5 minutes (FIG. 14C )).
[0069]
(20) Thereafter, a solder paste containing tin-lead is printed in the opening of the solder resist layer 70 on the surface on which the IC chip of the substrate is placed, and further, the tin-lead is formed in the opening of the solder resist layer 70 on the other surface. After the solder paste containing antimony was printed, the solder bumps 76U were provided on the upper surface by reflowing at 200 ° C. And the conductive connection pin 78 was arrange | positioned in the lower surface, and the printed circuit board 110 was manufactured (refer FIG. 15).
[0070]
In the above-described embodiment, an example in which a through hole is provided in a core substrate of a multilayer build-up wiring board with a laser has been described. The present invention can also be applied to a manufacturing method of a single printed wiring board to be connected or a printed wiring board in which a plurality of core substrates are laminated.
[0071]
As a comparative example, after forming through holes with a laser, the same printed wiring board as that of the above-described embodiment was formed without passing through a process using an etching solution, an acid, or an oxidizing agent.
When the printed wiring board of this comparative example was tested under heat cycle conditions, the conductor layer was disconnected in the through hole, or the through hole portion was not flat, and the conductor formed in the interlayer resin insulation layer or the upper layer Caused a crack in the circuit. As described above with reference to FIG. 16, this is because when the through hole is formed in the core substrate with a laser, the metal film remains as a burr, and when the conductor layer is formed in the through hole, It is considered that bubbles remained between the conductor layers, and when the through hole was filled with a filler, bubbles remained or insufficient filling occurred.
[Brief description of the drawings]
FIGS. 1A, 1B, 1C, and 1D are manufacturing process diagrams of a printed wiring board according to a first embodiment of the present invention.
FIGS. 2A, 2B, 2C and 2D are manufacturing process diagrams of a printed wiring board according to the first embodiment of the present invention.
3A, 3B, 3C, and 3D are manufacturing process diagrams of the printed wiring board according to the first embodiment of the present invention.
4A, 4B, and 4C are manufacturing process diagrams of a printed wiring board according to the first embodiment of the present invention. FIG.
5A, 5B, and 5C are manufacturing process diagrams of the printed wiring board according to the first embodiment of the present invention.
6A and 6B are manufacturing process diagrams of the printed wiring board according to the first embodiment of the present invention.
FIG. 7 is a cross-sectional view of the printed wiring board according to the first embodiment of the present invention.
FIG. 8 is an explanatory diagram of a carbon dioxide laser device that forms an opening.
9A, 9B, 9C, and 9D are manufacturing process diagrams of a printed wiring board according to a second embodiment of the present invention.
FIGS. 10A, 10B, 10C, and 10D are manufacturing process diagrams of a printed wiring board according to a second embodiment of the present invention.
11 (A), (B), (C), and (D) are manufacturing process diagrams of a printed wiring board according to a second embodiment of the present invention.
12A, 12B, and 12C are manufacturing process diagrams of a printed wiring board according to a second embodiment of the present invention.
FIGS. 13A, 13B, and 13C are manufacturing process diagrams of a printed wiring board according to a second embodiment of the present invention.
14A, 14B, and 14C are manufacturing process diagrams of a printed wiring board according to a second embodiment of the present invention.
FIG. 15 is a cross-sectional view of a printed wiring board according to a second embodiment of the present invention.
16 (A), (B), (C), and (D) are manufacturing process diagrams of a printed wiring board according to the prior art.
[Explanation of symbols]
30 core substrate
30A copper-clad laminate
32 Copper foil (metal film)
33 through holes
34 Conductor circuit
36 Bahia Hall
40 Resin filler
50 Interlayer resin insulation layer
58 Conductor circuit
60 Bahia Hall
70 Solder resist layer
76U, 76D Solder bump
150 Interlayer resin insulation layer
158 Conductor circuit
160 Viahole

Claims (2)

A method for producing a printed wiring board comprising at least the following steps (A) to (D):
(A) a step of roughening the surface of the substrate on which the metal film is laminated by blackening reduction treatment ;
(B) irradiating the substrate with a laser to form a plurality of through holes to be through holes;
(C) a step of desmearing the inside of the through-hole while simultaneously dissolving the metal film extending inward from the opening of the through-hole using an oxidizing agent;
(D) A step of filling the through hole with a filler. Filling the through hole with a filler, laminating an interlayer resin insulation layer, forming an opening in the interlayer resin insulation layer with a laser, and then filling the opening with plating to form a via hole The manufacturing method of the printed wiring board of Claim 1 .

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