JP4505908B2 - Method for manufacturing printed wiring board - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a printed wiring board and a manufacturing method thereof.
[0002]
[Prior art]
In recent years, there has been an increasing demand for electronic devices that are small, light, high-speed, multi-functional, and highly reliable, and semiconductor circuit elements have been highly integrated and speeded up to meet the requirements. Along with the trend of electronic devices and semiconductor circuit elements, printed wiring boards have responded in the form of multilayers, finer wiring, and smaller diameters for interlayer connection holes. In particular, in recent years, various companies have built-up wiring boards that have been changed from through holes, which are obstacles to higher density, to interstitial via holes (hereinafter referred to as IVH) that connect only conductors in adjacent layers. Developed and marketed.
[0003]
In this IVH, the inner wall of the hole is usually plated and the conductors of adjacent layers are electrically connected, but an insulating layer is stacked on the hole, and a hole is further drilled for connection. What is performed is that it is difficult to align the holes, and that the depth of the holes is so deep that it is difficult to replace the plating solution, which makes metalization difficult.
Therefore, as disclosed in JP-A-9-23067, JP-A-7-170046 and JP-A-7-176646, if the inside of the IVH is filled with a conductive paste, the hole is closed, and the IVH Since the upper part of the flat part is flat, an insulating layer is provided on the chin and there is no such thing even if a hole is made, the degree of freedom in wiring design is high, interlayer connection is possible directly under the component land, and IVH can be designed on top of IVH.
[0004]
[Problems to be solved by the invention]
The interlayer connection in which the conductive paste is filled with IVH has a problem that the IVH portion is easily broken in the thermal cycle test, particularly when the IVH diameter is 100 μm or less.
[0005]
An object of this invention is to provide the manufacturing method of the printed wiring board excellent in connection reliability even if it is fine IVH.
[0006]
[Means for Solving the Problems]
The present invention is characterized by the following.
(1) A step of providing an insulating layer with copper foil on an inner layer circuit board having an inner layer conductor, opening a hole reaching the inner layer conductor in the insulating layer with copper foil, and filling the hole with a plating metal by electroless plating The manufacturing method of the printed wiring board which has this.
(2) A part of the insulating layer with copper foil is removed by etching to form an opening, and the opening is irradiated with a laser to evaporate the insulating tank at that part and provide a hole reaching the inner layer conductor (1 ) Printed wiring board manufacturing method.
(3) The copper foil which has the roughness whose surface roughness of the copper foil which is in contact with the insulating layer of the insulating layer with copper foil is in the range of 0.1 to 2 μm with 10-point average roughness is used (1) Or the manufacturing method of the printed wiring board as described in (2).
(4) The method for manufacturing a printed wiring board according to any one of (1) to (3), wherein the plating metal filling the hole is nickel or a nickel alloy.
(5) The printed wiring board according to any one of (1) to (4), wherein the plated metal filling the hole is nickel or a nickel alloy and contains 0 to 30% by weight of phosphorus. Method.
(6) The printed wiring board according to any one of (1) to (4), wherein the plated metal filling the hole is nickel or a nickel alloy and contains 0 to 15 wt% of boron. Method.
(7) The plated metal filled in the hole is a nickel alloy and contains at least one of gold, silver, copper, tin, iron, zinc, tungsten, palladium, cobalt, manganese, chromium and rhenium. The printed wiring board manufacturing method according to any one of (1) to (6).
(8) An electroless plating solution containing any one of hydrazine, hypophosphite, and dimethylamine borane as a reducing agent for the plating metal is used as the electroless plating solution for forming the plating metal. The manufacturing method of the printed wiring board in any one of (7).
(9) The method for producing a printed wiring board according to any one of (1) to (8), wherein a plating solution containing at least 0.1 mmol / l of nickel ions is used for the electroless plating solution.
(10) Electroless palladium plating is selectively performed on the IVH bottom as a pretreatment step for filling the hole reaching the inner layer conductor in the insulating layer with a plating metal by electroless plating (1) to (9) The manufacturing method of the printed wiring board in any one of these.
[0007]
DETAILED DESCRIPTION OF THE INVENTION
For the insulating layer of the present invention, a thermosetting resin such as an epoxy resin, a polyimide resin, or a bismaleimide-triazine resin, or a thermoplastic resin such as a fluorine resin or a polyphenylene ether resin can be used.
[0008]
The epoxy resin may be anything as long as it has an epoxy group in the molecule, and is a bisphenol A type epoxy resin, a bisphenol F type epoxy resin, a bisphenol S type epoxy resin, an alicyclic epoxy resin, or an aliphatic chain. Epoxy resin, phenol novolac type epoxy resin, cresol novolac type epoxy resin, bisphenol A novolac type epoxy resin, diglycidyl etherified product of biphenol, diglycidyl etherified product of naphthalenediol, diglycidyl etherified product of phenols, alcohols And diglycidyl etherified products thereof, alkyl substitution products thereof, halides, hydrogenated products, and the like. These may be used in combination, and components other than the epoxy resin may be contained as impurities.
[0009]
In the present invention, an epoxy resin to be obtained by reacting a halogenated bisphenol compound such as tetrabromobisphenol A such as a halogenated bisphenol A type epoxy resin, a halogenated bisphenol F type epoxy resin, or a halogenated bisphenol S type epoxy resin with epichlorohydrin When an epoxy resin in which the ortho position with respect to the ether group of the benzene ring to which the ether group is bonded is substituted with a halogen atom such as chlorine or bromine is used, the epoxy resin is cured by the treatment liquid of the present invention. The efficiency of decomposition and / or dissolution of the product is particularly good.
[0010]
The curing agent for epoxy resin used in the present invention can be used without limitation as long as it cures the epoxy resin. For example, polyfunctional phenols, amines, imidazole compounds, acid anhydrides, organophosphorus compounds and These halides are included.
[0011]
Examples of polyfunctional phenols include monocyclic bifunctional phenols hydroquinone, resorcinol, catechol, polycyclic bifunctional phenols bisphenol A, bisphenol F, naphthalenediols, biphenols, and their halides, alkyl group substitution There is a body. Furthermore, there are novolak and resol which are polycondensates of these phenols and aldehydes.
[0012]
Examples of amines include aliphatic or aromatic primary amines, secondary amines, tertiary amines, quaternary ammonium salts and aliphatic cyclic amines, guanidines, urea derivatives, and the like.
[0013]
Examples of these compounds include N, N-benzyldimethylamine, 2- (dimethylaminomethyl) phenol, 2,4,6-tris (dimethylaminomethyl) phenol, tetramethylguanidine, triethanolamine, N, N '-Dimethylpiperazine, 1,4-diazabicyclo [2,2,2] octane, 1,8-diazabicyclo [5,4,0] -7-undecene, 1,5-diazabicyclo [4,4,0] -5 -Nonene, hexamethylenetetramine, pyridine, picoline, piperidine, pyrrolidine, dimethylcyclohexylamine, dimethylhexylamine, cyclohexylamine, diisobutylamine, di-n-butylamine, diphenylamine, N-methylaniline, tri-n-propylamine, tri -N-octylamine, tri-n -Butylamine, triphenylamine, tetramethylammonium chloride, tetramethylammonium bromide, tetramethylammonium iodide, triethylenetetramine, diaminodiphenylmethane, diaminodiphenyl ether, dicyandiamide, tolylbiguanide, guanylurea, dimethylurea and the like.
[0014]
Examples of imidazole compounds include imidazole, 2-ethylimidazole, 2-ethyl-4-methylimidazole, 2-methylimidazole, 2-phenylimidazole, 2-undecylimidazole, 1-benzyl-2-methylimidazole, 2- Heptadecylimidazole, 4,5-diphenylimidazole, 2-methylimidazoline, 2-phenylimidazoline, 2-undecylimidazoline, 2-heptadecylimidazoline, 2-isopropylimidazole, 2,4-dimethylimidazole, 2-phenyl-4 -Methylimidazole, 2-ethylimidazoline, 2-phenyl-4-methylimidazoline, benzimidazole, 1-cyanoethylimidazole and the like.
[0015]
Examples of the acid anhydride include phthalic anhydride, hexahydrophthalic anhydride, pyromellitic dianhydride, benzophenone tetracarboxylic dianhydride, and the like.
[0016]
The organic phosphorus compound is not particularly limited as long as it is a phosphorus compound having an organic group. For example, hexamethylphosphoric triamide, tri (dichloropropyl) phosphate, tri (chloropropyl) phosphate, phosphorous acid Examples include triphenyl, trimethyl phosphate, phenylphosphonic acid, triphenylphosphine, tri-n-butylphosphine, and diphenylphosphine.
[0017]
These curing agents can be used alone or in combination.
The compounding amount of these epoxy resin curing agents can be used without particular limitation as long as the curing reaction of the epoxy group can proceed, but preferably 0.01 to 5.0 with respect to 1 mol of the epoxy group. It is used in the range of equivalents, particularly preferably in the range of 0.8 to 1.2 equivalents.
[0018]
Moreover, you may mix | blend a hardening accelerator with the thermosetting epoxy resin composition of this invention as needed. Typical curing accelerators include, but are not limited to, tertiary amines, imidazoles, and quaternary ammonium salts.
[0019]
As the polyimide resin, those obtained by curing a bismaleimide resin with amines, and those obtained by curing these prepolymers with an epoxy resin, a biscyanate monomer, aminophenol, bisphenol, dicarboxylic acid, or the like can be used.
[0020]
The resin is dissolved in a soluble solvent to form a resin varnish, and if necessary, a curing agent, a reaction accelerator, a flame retardant, thermoplastic resin particles, a curing accelerator, a coloring material, an ultraviolet opaque agent, an antioxidant, a reduction Various additives such as agents and fillers can be added for preparation.
[0021]
Such a resin varnish is applied to the roughened surface of the copper foil, heated and dried to make it semi-cured to form an insulating layer with copper foil. The roughness of the roughened surface of the copper foil at this time is a 10-point average roughness, preferably in the range of 0.1 to 2 μm, and if it is less than 0.1 μm, the adhesive force between the insulating layer and the copper foil is If the thickness exceeds 2 μm, the insulating property may be deteriorated.
[0022]
For inner circuit boards with inner layer conductors, circuit conductors can be formed by etching away copper foil from unnecessary portions of copper-clad laminates used in ordinary printed wiring boards, or glass epoxy boards, polyimide boards, ceramics A material produced by forming an electroless plating adhesive layer on the surface of a substrate such as a substrate, roughening the surface of the adhesive layer, and forming copper plating only at a necessary location can be used.
In such an inner layer circuit board, it is preferable to roughen the surface of the inner layer conductor before forming the insulating layer and to improve the adhesion with the insulating layer formed on the inner layer conductor.
[0023]
To provide an insulating layer with copper foil on an inner layer circuit board having an inner layer conductor, the resin surface of the above-mentioned insulating layer with copper foil is laminated so as to be in contact with the inner layer conductor of the inner layer circuit board and laminated by heating and pressing. Can be integrated.
The conditions for stacking and integration at this time can be those of a normal multilayer printed wiring board, and if it is an insulating layer using an epoxy resin, for example, at 150 to 200 ° C., 0.5 to 4.0 MPa It is preferable to carry out under the condition of a range of 30 to 180 minutes.
[0024]
In order to make a hole reaching the inner layer conductor in this insulating layer with copper foil, it is performed by irradiating a laser, but it is preferable to remove in advance the copper foil at the location irradiated with the laser, and the size of the hole to be formed Accordingly, the copper foil is removed by etching to provide an opening.
In order to make a hole reaching the inner conductor in the insulating layer with copper foil in which the opening is formed, it can be formed by laser irradiation, and is not particularly limited, such as a carbon dioxide laser or a UV-YAG laser. The drilling conditions must be adjusted according to the type of insulating layer and the thickness of the insulating layer, and are preferably obtained experimentally. The amount of energy is within the range of 0.001 W to 1 W and is used for laser oscillation. Must be controlled so that a large amount of energy is not concentrated at once. The adjustment of the drilling conditions is performed by adjusting the pulse waveform duty ratio for driving the laser oscillation power source to 1/1000 to 1/1 in order to make a hole reaching the inner layer circuit of the inner layer circuit board and to make the hole diameter as small as possible. In the range of 10, it is preferably 1 to 20 shots (pulses). If the waveform duty ratio is less than 1/1000, it takes too much time to make a hole and is not efficient. If it exceeds 1/10, the irradiation energy is too large and the hole diameter becomes 1 mm or more, which is not practical. The number of shots (pulses) should be determined experimentally so that the adhesive in the hole can evaporate to reach the inner layer circuit. If less than one shot, a hole cannot be drilled. Even if the waveform duty ratio of the pulse is near 1/1000, the hole diameter becomes large and is not practical.
[0025]
After forming the hole in this manner, desmear treatment is performed in order to remove the debris of the insulating layer in the hole. This desmear treatment can use a general acidic oxidizing roughening solution or an alkaline oxidizing roughening solution. For example, an acidic oxidizing roughening solution includes a chromium / sulfuric acid roughening solution, and an alkaline oxidizing roughening solution may be a potassium permanganate roughening solution.
After the insulating layer is roughened with an oxidizing roughening solution, it is necessary to chemically neutralize the oxidizing roughening solution on the surface of the insulating resin. A general method can also be adopted.
For example, when a chromium / sulfuric acid roughening solution is used, it is treated with sodium hydrogen sulfite 10 g / l at room temperature for 5 minutes, and when a potassium permanganate roughening solution is used, 150 ml / l of sulfuric acid is peroxidized. For example, it is immersed in an aqueous solution of 15 ml / l of hydrogen water at room temperature for 5 minutes to complete neutralization.
[0026]
In order to make a hole reaching the inner layer conductor in the insulating layer, a photo-curing type insulating material is used for the insulating layer, and ultraviolet rays are irradiated through a photomask for masking a portion that becomes IVH on the insulating layer, and not exposed. This part can also be developed and removed, and can be carried out by using a photoinitiator such as an onium salt for the resin of the insulating layer.
[0027]
In order to fill the hole with electroless nickel plating or electroless nickel alloy plating, the laminated plate with holes in the insulating layer is immersed in the electroless nickel plating solution or electroless nickel alloy plating solution. The electroless nickel plating solution or electroless nickel alloy plating solution contains additives such as a complexing agent of nickel ions and nickel ions, a reducing agent of nickel ions, a pH adjusting agent, and a stabilizer if necessary. It is preferable to use one.
As a reducing agent used for electroless nickel plating or electroless nickel alloy plating, it is preferable to use an electroless plating solution containing any of hydrazine, hypophosphite, and dimethylamine borane.
The plating solution used for electroless nickel plating or electroless nickel alloy plating preferably contains at least 0.1 mmol / l or more of nickel ions, and if it is less than 0.1 mmol / l, the plating deposition rate may be slow. There is.
[0028]
Acid is used to activate the inner layer conductor exposed at the bottom of the IVH as a pretreatment step for filling the hole reaching the inner layer conductor in the insulating layer by electroless nickel plating or electroless nickel alloy plating More preferably, sulfuric acid is used. Furthermore, it is preferable to selectively perform electroless palladium plating on the bottom of the IVH. This electroless palladium plating is intended to facilitate the deposition of electroless plating on the activated inner layer copper pattern. Is preferred. This substituted palladium plating is not particularly limited as long as it can form a palladium film on copper by a substitution reaction of palladium ions in the plating solution.
[0029]
After filling the electroless nickel plating or electroless nickel alloy plating, it is preferable to perform a surface treatment on the surface of the insulating layer. In that case, the surface treatment is performed using a surface polishing machine using a cloth roll or a brush roll. Using a scrub polisher or a century polisher, the interlayer resin insulation layer surface is mechanically polished with a cloth roll, brush roll, or abrasive grain, and electroless nickel plating or electroless nickel alloy plating filled with IVH and an insulating layer Are preferably the same height.
[0030]
Thus, the circuit conductor can be formed on the surface of the substrate in which the IVH is filled with electroless nickel plating or electroless nickel alloy plating.
The circuit conductor is formed by forming plated copper on the entire surface of the insulating layer, and if necessary, adjusting the thickness by forming electrolytic plating, and etching resist so as to expose the unnecessary plated copper. The plating copper exposed from the etching resist can be formed by spraying a chemical etching solution and removing it by etching, and the plating resist is formed on the surface of the insulating layer at a location that does not become a circuit conductor, A circuit conductor can also be formed by selectively plating a portion where no plating resist is formed. In addition, a thin electroless plated copper is formed on the entire surface of the insulating layer, a plating resist is formed, electrolytic copper plating is performed, a circuit conductor is formed to a required thickness, and then the plating resist is peeled off. A circuit conductor can also be formed by etching away electrolessly plated copper formed at a location that is not a circuit conductor.
It is preferable to roughen the surface of the insulating layer so that the plated copper is in close contact with it, and it is preferable to use an oxidizing agent for this roughening. As the oxidizing agent, an oxidizing agent having strong oxidizing power such as chromate or permanganate is used. The depth of the recess on the roughened surface is in the range of 1 to 10 μm, more preferably in the range of 2 to 3 μm. If the depth is less than 1 μm, the adhesion with the plating may not be improved. There is a fear.
[0031]
【Example】
As shown in FIG. 1 (a), MCL-E-679, which is a glass cloth base epoxy copper clad laminate having a thickness of 0.2 mm, in which a copper foil having a thickness of 18 μm is bonded to both sides of the insulating base 22 is used. The copper foil of the unnecessary part was etched away using (made by Hitachi Chemical Co., Ltd., a brand name), the inner-layer conductor circuit 21 was formed, and the inner-layer circuit board 2 was produced.
The surface treatment of the inner layer conductor circuit 21 of the inner layer circuit board 2 is performed by spray spraying using MEC etch BOND CZ-8100 (trade name, manufactured by MEC Co., Ltd.) at a liquid temperature of 35 ° C. and a spray pressure of 0.147 MPa. Then, the copper surface is roughened to form irregularities with a roughness of about 3 μm, and then using a MEC etch BOND CL-8300 (trade name, manufactured by MEC Co., Ltd.) at a liquid temperature of 25 ° C. and an immersion time of 20 seconds. The copper surface was rust-proofed by immersion treatment under the above conditions.
As shown in FIG. 1B, MCF-6000E (trade name, manufactured by Hitachi Chemical Co., Ltd.), which is an insulating layer with copper foil, was laminated on both surfaces of the inner circuit board 2. The surface roughness of the copper foil 3 of this MCF-6000E (trade name, manufactured by Hitachi Chemical Co., Ltd.) was 1.2 μm in terms of 10-point average roughness, and the thickness of the insulating layer 1 was 40 μm.
As shown in FIG.1 (c), after removing the copper foil of the hole location by etching and forming the opening part 41 of a diameter of 80 micrometers, the carbon dioxide impact laser drilling machine L-500 (made by Sumitomo Heavy Industries, Ltd., According to the product name), a non-through hole 4 having a diameter of 80 μm is made, and the smear is removed by immersing in a mixed aqueous solution of potassium permanganate 65 g / l and sodium hydroxide 40 g / l at a liquid temperature of 70 ° C. for 2 minutes. It was.
Next, as plating pretreatment, it is immersed in acidic degreasing solution Z-200 (manufactured by World Metal Co., Ltd., trade name) for 1 minute at a liquid temperature of 60 ° C., and then immersed in sodium persulfate 50 g / l for 1 minute. Subsequently, it was immersed in 10 vol% sulfuric acid at room temperature for 1 minute. It was immersed in Melplate Activator 350 (Meltex Co., Ltd., trade name) for 5 minutes at room temperature.
Next, the catalyst on the copper foil surface was removed by feather polishing.
Next, it was immersed at 90 ° C. for 2 hours in NIPS-100 (trade name, manufactured by Hitachi Chemical Co., Ltd.), which is an electroless nickel-phosphorus alloy plating, and a nickel post was formed as shown in FIG. . Next, only the copper foil was selectively etched with an alkaline etching solution (mixed aqueous solution of 8% ammonia and 0.3% hydrogen peroxide).
Next, as shown in FIG. 1 (e), the substrate was immersed in HS-202B (trade name, manufactured by Hitachi Chemical Co., Ltd.), which is a palladium solution, at 25 ° C. for 15 minutes to attach the catalyst, Using CUST-201 (trade name, manufactured by Hitachi Chemical Co., Ltd.), electroless copper plating was performed at a liquid temperature of 25 ° C. for 30 minutes to form an electroless copper plating layer 6 having a thickness of 0.3 μm. .
As shown in FIG. 1 (f), FOTEC HW-425 (trade name, manufactured by Hitachi Chemical Co., Ltd.), which is a dry film for photoresist, is laminated on the surface of the electroless copper plating layer 6, and electrolytic copper plating is performed. The plating resist 7 was formed by exposing and developing ultraviolet rays through a photomask that masks the place to be performed.
As shown in FIG. 1 (g), using a copper sulfate bath, electrolytic copper plating is performed for about 10 μm under conditions of a liquid temperature of 25 ° C. and a current density of 1.0 A / dm ² , and circuit conductor width / circuit conductor spacing ( The electrolytic copper plating layer 8 was formed so that L / S) = 50/50.
As shown in FIG. 1 (h), the plating resist 7 is dissolved and removed with 1% by weight of sodium carbonate, and then the A process liquid (trade name, manufactured by Meltex Co., Ltd.), which is an ammonium-based alkaline copper etching liquid. It was immersed for 1 minute at room temperature, the electroless copper plating layer 6 formed under the plating resist 7 was removed by etching, and immediately after that, it was washed with running water.
Finally, in order to remove the palladium of electroless plating catalyst adhering to the resin surface and the slightly remaining electroless copper plating, the potassium permanganate was adjusted to 65 g / l and sodium hydroxide to 40 g / l. The mixed aqueous solution was subjected to an immersion treatment at a liquid temperature of 70 ° C. under an immersion time of 2 minutes, and the entire resin was removed by etching.
[0032]
The substrate had no conduction failure or circuit loss, and the plating peel of the outer layer conductor circuit was 1.4 KN / m.
[0033]
【The invention's effect】
As described above, according to the present invention, it is possible to provide a method for manufacturing a printed wiring board having excellent connection reliability even with a fine IVH.
[Brief description of the drawings]
FIGS. 1A to 1H are cross-sectional views in each step for explaining an embodiment of the present invention.
[Explanation of symbols]
1. Insulating layer Inner layer circuit board 22. Insulating base material 21. 2. Inner layer conductor circuit Copper foil 4. Non-through hole 41. Opening 6. 6. Electroless copper plating layer Plating resist 8. Electrolytic copper plating layer 10. Plating

Claims (8)

An insulating layer with copper foil is provided on an inner circuit board having an inner layer conductor, a hole reaching the inner layer conductor is formed in the insulating layer with copper foil, electroless palladium plating is performed, and then the copper foil surface is polished. the performed selectively the electroless palladium plating in the bottom of the hole, have a filling a plating metal by electroless plating to the hole,
A method for producing a printed wiring board, wherein the plated metal filling the holes is nickel or a nickel alloy .   2. A part of the insulating layer with copper foil is removed by etching to form an opening, and the opening is irradiated with a laser to evaporate the insulating layer and provide a hole reaching the inner layer conductor. Manufacturing method of printed wiring board.   The copper foil which has the roughness whose surface roughness of the copper foil which is in contact with the insulating layer of the insulating layer with copper foil is in the range of 0.1 to 2 μm with 10-point average roughness is used. The manufacturing method of the printed wiring board of description. The method for manufacturing a printed wiring board according to any one of claims 1 to 3 , wherein the plated metal filling the holes is nickel or a nickel alloy and contains 0 to 30 wt% of phosphorus. The method for manufacturing a printed wiring board according to any one of claims 1 to 4 , wherein the plated metal filling the holes is nickel or a nickel alloy and contains 0 to 15 wt% of boron. The plated metal filled in the hole is a nickel alloy and contains at least one of gold, silver, copper, tin, iron, zinc, tungsten, palladium, cobalt, manganese, chromium, rhenium method for manufacturing a printed wiring board according to any one of claim 1-5. In an electroless plating solution to form a plating metal as a reducing agent for the plating metal, hydrazine, hypophosphite, of claims 1-6 using an electroless plating solution containing either of the dimethylamine borane The manufacturing method of the printed wiring board in any one. The method for manufacturing a printed wiring board according to any one of claims 1 to 7 , wherein a plating solution containing at least 0.1 mmol / l of nickel ions is used as the electroless plating solution.

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