JP4478844B2 - Printed wiring board manufacturing method and printed wiring board manufactured by the method - Google Patents

Description

（微細配線形成性）
・×：Ｌ／Ｓ＝５０μｍ／５０μｍ 配線形成不可
・○：Ｌ／Ｓ＝３０μｍ／３０μｍ 配線形成可能
・◎：Ｌ／Ｓ＝２０μｍ／２０μｍ 配線形成可能
（気相熱衝撃試験）
・×：５００サイクル未満で導通抵抗変化率１０％以上
・○：５００サイクル以上１０００サイクル未満で導通抵抗変化率１０％以上
・◎：１０００サイクル以上で導通抵抗変化率１０％未満
【００３６】
【発明の効果】
以上に説明したとおり、本発明によって、層間の薄型化、配線の微細化、また、ＩＶＨの接続信頼性に優れ、生産性に優れた多層プリント配線板の製造方法を提供することができる。
【図面の簡単な説明】
【図１】（ａ）〜（ｆ）は、それぞれ本発明の一実施例を説明するための各工程を示す断面図である。
【符号の説明】
１．内層回路 ２．穴埋め材
３．内層回路板 ４．熱硬化性樹脂
５．ＩＶＨ ６．無電解銅めっき
７．めっきレジスト ８．無電解めっき銅エッチング
９．ビルドアップ基板[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a printed wiring board manufacturing method and a printed wiring board manufactured by the method.
[0002]
[Prior art]
In recent years, electronic devices have become lighter, thinner, multifunctional, and faster, and build-up wiring boards have been used, and via holes have been miniaturized. For manufacturing such a build-up wiring board, an insulating resin layer is formed on the inner wiring board, then a via hole is formed by irradiating a carbon dioxide laser, and after desmearing, the interlayer connection is performed by electroless plating or the like. After metallizing the inner wall of the hole and the surface of the insulating resin layer, forming a plating resist on the surface of the insulating resin layer, pattern electroplating to form a circuit conductor, then peeling the plating resist and performing quick etching, There is a method of forming a circuit by etching away electroless plating.
[0003]
[Problems to be solved by the invention]
In this build-up multilayer wiring board, the pattern that becomes a circuit when the electroless plating is removed by etching in order to form a circuit is simultaneously shaved by the etching solution.
Further, in order to promote adhesion with a thermosetting resin in order to form a multilayer circuit using the substrate on which the circuit is formed as an inner circuit board, a process of oxidizing / reducing the copper surface is generally used. Has been done. As a pretreatment of this oxidation / reduction treatment, the copper surface is thinly removed with a chemical etching solution such as ammonium persulfate to carry out the oxidation / reduction treatment.
The conductor circuit is etched and removed by these two etching processes, and there is a problem that the yield such as thinning or disconnection of the wiring is reduced, and even if no disconnection occurs, the thickness of the circuit copper foil is reduced. There was a problem that the connection reliability of the thermal cycle test and the like was lowered.
[0004]
An object of the present invention is to provide a method for manufacturing a printed wiring board that is excellent in productivity and suitable for fine wiring that does not deteriorate connection reliability, and a printed wiring board manufactured by the method.
[0005]
[Means for Solving the Problems]
The invention is characterized by the following.
(1) In a method of manufacturing a printed wiring board, a resin layer is formed on an inner circuit board having an inner circuit, a hole reaching the inner layer, a hole inner wall is metalized, and an outer circuit is formed. Then, a base copper plating is formed by electroless copper plating , a plating resist is formed on the surface of the base copper plating , a conductor is formed into a circuit shape by electrolytic copper plating , and the plating resist is removed and is placed under the plating resist. and the underlying copper plating, thereby forming an outer layer circuit are etched away with an etchant mainly composed of formic acid, to roughen the surface, a benzotriazole solution by immersing the printed wiring board, the further the outer circuit surface A method for producing a printed wiring board for forming a resin layer .
(2) A printed wiring board manufactured by the method of (1).
[0006]
DETAILED DESCRIPTION OF THE INVENTION
In the present invention, the resin used is preferably a thermosetting resin, and more preferably an epoxy resin. Such an epoxy resin is composed of a thermosetting resin composition containing an epoxy resin and a curing agent. The thermosetting resin composition further includes a curing accelerator, a catalyst, an elastomer, a flame retardant, and the like as necessary. May be added.
[0007]
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.
[0008]
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.
[0009]
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.
[0010]
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.
[0011]
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.
[0012]
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.
[0013]
Examples of the acid anhydride include phthalic anhydride, hexahydrophthalic anhydride, pyromellitic dianhydride, benzophenone tetracarboxylic dianhydride, and the like.
[0014]
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.
[0015]
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.
[0016]
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.
[0017]
A ceramic whisker can be further added to the resin composition for a wiring board of the present invention. Such ceramic whiskers preferably have an elastic modulus of 200 GPa or more. If it is less than 200 GPa, sufficient rigidity cannot be obtained when used as a wiring board material or a wiring board.
As such, for example, one or more selected from aluminum borate, wollastonite, potassium titanate, basic magnesium sulfate, silicon nitride, and α-alumina can be used. Among them, aluminum borate whisker and potassium titanate whisker have Mohs hardness almost equivalent to E glass used for a general prepreg base material, and can obtain drilling workability similar to that of a conventional prepreg. The aluminum borate whisker has a high elastic modulus of about 400 GPa and is easy to mix with the resin varnish, and is more preferable.
[0018]
The average diameter of the whisker is preferably 0.3 μm to 3 μm, and more preferably 0.5 μm to 1 μm. If the average diameter of the whisker is 0.3 μm or less, mixing with the resin varnish becomes difficult, and if it exceeds 3 μm, the microscopic dispersion in the resin is not sufficient, and the surface unevenness becomes large, which is not preferable. .
Further, the ratio of the average diameter to the average length is preferably 10 or more, and the rigidity can be further increased, preferably 20 or more. When this ratio is less than 10, the reinforcing effect as a fiber becomes small. The upper limit of this average length is 100 μm, more preferably 50 μm. Exceeding this upper limit makes it difficult to disperse in the resin varnish, and increases the probability that one whisker will come into contact with the two conductor circuits, and the probability that migration of copper ions will occur along the fibers of the whisker. Become.
[0019]
In addition, in order to increase the rigidity, heat resistance and moisture resistance of the multilayer printed wiring board, it is preferable to use an electrically insulating whisker that has been surface-treated with a coupling agent having excellent wettability and bondability with a resin, Examples of such coupling agents include silicon coupling agents, titanium coupling agents, aluminum coupling agents, zirconium coupling agents, zircoaluminum coupling agents, chromium coupling agents, and boron coupling agents. , A phosphorus coupling agent, an amino acid coupling agent and the like.
[0020]
The ratio between the thermosetting resin and the ceramic whisker is preferably adjusted so that the volume fraction of the whisker in the cured resin is in the range of 5% to 50%. If the volume fraction of whiskers in the cured resin is less than 5%, the prepreg with copper foil (copper foil / thermosetting resin layer) will be shattered and scattered during cutting, making handling extremely difficult. When the wiring board is used, the rigidity is lowered. On the other hand, if the volume fraction of whiskers exceeds 50%, the holes and circuit gaps are not sufficiently embedded in the heat and pressure molding, voids and blurring occur after molding, and the insulating properties are lowered. Moreover, as for the ratio of resin and whisker, it is more preferable that the volume fraction of the whisker in the cured resin is 20 to 40%.
[0021]
In addition, a laminate comprising the resin and metal layer of the present invention is a prepreg in which the above resin composition is dissolved in a solvent such as methyl ethyl ketone or isopropyl alcohol to form a resin varnish, which is impregnated into a glass cloth.・ Dried and semi-cured and laminated with metal foil such as copper foil and aluminum foil, laminated by heating and pressurizing, and resin varnish to metal foil with blade coater, rod coater, knife coater, Apply a uniform thickness with a squeeze coater, reverse roll coater, transfer roll coater, etc., heat and dry to make it semi-cured, or such a resin layer with metal foil on the inner circuit board Are laminated and integrated by heating and pressurizing, the above prepreg is plated on a heat-cured resin plate, and on the inner circuit board. Resin varnish coated with a uniform thickness with a blade coater, rod coater, knife coater, squeeze coater, reverse roll coater, transfer roll coater, etc., heated and dried, and plated on the surface, or metal foil In some cases, a resin layer is laminated on an inner circuit board, heated and pressed, laminated and integrated, and then the metal foil is removed by etching and then the surface is plated.
[0022]
The inner layer circuit board on which the inner layer circuit is formed can be the inner layer circuit board used for ordinary printed wiring boards, and the circuit is formed by etching away unnecessary copper foil from the copper-clad laminate for printed wiring boards Or, if necessary, drill holes in the double-sided copper-clad laminate for printed wiring boards, perform electroless plating to form plated metal on the inner walls of the holes, and if necessary, perform electrolytic plating to provide the necessary circuit conductor Thickness, unnecessary copper foil and plated metal removed by etching to form a circuit can be used.
[0023]
Overlay the above resin layer with metal foil on the inner layer circuit board on which the inner layer circuit is formed, heat and pressurize and integrate the layers, and then make a laser hole from the top of this metal foil to reach the inner layer circuit. Can be opened by irradiation. When the metal foil is thick, the metal foil is once removed by etching and a metal layer is formed by plating, and then a via hole can be formed by irradiating a laser on the metal layer. At this time, it is preferable to roughen the resin layer before plating, and a general acidic oxidizing roughening solution or an alkaline oxidizing roughening solution can be used. For example, as the acidic oxidizing roughening liquid, there is a chromium / sulfuric acid roughening liquid, and as the alkaline oxidizing roughening liquid, a potassium permanganate roughening liquid or the like can be used.
After the resin 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, but 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.
[0024]
The type of laser of the laser processing machine used for drilling by laser irradiation is not particularly limited, such as a carbon dioxide gas laser or a UV-YAG laser. The drilling conditions must be adjusted according to the thickness of the metal foil, the type of resin and the thickness of the resin, and are preferably obtained experimentally. The amount of energy is within the range of 0.001 W to 1 W, It is necessary to control the laser oscillation power supply so that a large amount of energy is not concentrated at a time by applying a pulsed power supply. 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.
In addition, if the surface of the metal layer is too smooth, it may reflect the laser beam and may not evaporate. The degree of roughening only needs to exhibit a hue that can absorb laser light. For example, the surface may be clouded with a chemical etching solution composed of cupric chloride and hydrochloric acid or an ammonium persulfate solution.
[0025]
After the via hole is formed, it is preferable to perform a desmear treatment to remove the debris of the adhesive in the via hole. This desmear treatment may be performed using a general acidic oxidizing roughening solution or an alkaline oxidizing roughening solution. Chemical solution can be used. 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 resin 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, but 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]
The copper plating performed to form the conductor as the outer layer circuit after the above may be the same method as the electroless plating, or after thinly electroless plating, for example, a copper sulfate bath or a copper pyrophosphate bath Electroplating can be performed to the required thickness for the circuit conductor. What is important at this time is to perform electroless plating on the inner wall of the formed via hole to form plated copper for connecting the inner layer circuit conductor and the outer layer circuit. Thereafter, if the thickness of the circuit conductor is about 1 to 15 μm, it can be formed by electroless plating, and if it exceeds 15 μm, electrolytic plating can be used in combination. Preferably, in order to form a precise wiring, it is preferable to form by electroless plating because the surface becomes flat. Moreover, a plating resist is formed before plating, and a circuit is formed by performing plating only on the shape of the circuit.
After copper plating in this manner, the plating resist is peeled and removed, and the thin copper plating underneath is removed by etching to form a circuit.
[0027]
The surface treatment solution of the conductor circuit, various materials can be used, an etching solution mainly composed of formic acid is preferred in view of formability or the like of the unevenness of the etching rate and surface.
[0028]
【Example】
Example 1
As shown in FIG. 1 (a), MCL-679 (trade name, manufactured by Hitachi Chemical Co., Ltd.), which is a 0.4 mm thick glass cloth-epoxy resin impregnated double-sided copper-clad laminate, The inner layer circuit 1 having the through-hole 101 that has been subjected to electrolytic copper plating, filled with a thermosetting resin M-650TH (manufactured, trade name) as a filling material in the through-hole 101, heated and cured, and filled with a normal subtract method. The formed inner layer board was produced. Then, it heat-dried at 130 degreeC for 30 minutes using the hot air dryer.
As shown in FIG.1 (b), as the thermosetting resin layer 4, buildup film AS-9000E (made by Hitachi Chemical Co., Ltd., a brand name) and an inner layer board are piled up at 170 degreeC for 60 minutes, 2.5 MPa. The layers were integrated by heating and pressurizing at a pressure of.
As shown in FIG. 1C, the cured thermosetting resin layer 4 is irradiated by a carbon dioxide laser under the conditions of an energy density of 20 J / cm ² , an oscillation time of 5 μsec, an oscillation frequency of 500 Hz, and 4 pulses. The inner layer circuit 1 was removed until the inner layer circuit 1 was exposed to form IVH5.
The substrate surface of the cured thermosetting resin layer 4 and the wall surface of IVH5 were roughened using a 7% alkaline permanganate aqueous solution as a roughening agent at a liquid temperature of 70 ° C. for 10 minutes.
The substrate surface is brought into contact with HS-202B (trade name, manufactured by Hitachi Chemical Co., Ltd.), which is an electroless copper plating catalyst application treatment solution, on the roughened substrate surface and via hole wall surface at room temperature for 10 minutes. And a catalyst was provided to the via-hole wall surface.
As shown in FIG. 1 (d), on the surface of the substrate provided with the catalyst and the wall surface of the via hole, the substrate is placed on CUST-201 (trade name, manufactured by Hitachi Chemical Co., Ltd.) which is an electroless copper plating solution. Immersion electroless copper plating 6 was performed to a thickness of 0.3 μm. For the measurement of the plating film thickness, SFT8000 (Seiko Electronics Co., Ltd., trade name) was used.
The surface of the electroless copper plating 6 was laminated with a dry film FOTEC RY3025 (trade name, manufactured by Hitachi Chemical Co., Ltd.), and a plating resist 7 was formed in the gap portion.
As shown in FIG.1 (e), the board | substrate in which the said plating resist 7 was formed was electroplated so that the thickness of a conductor circuit might be set to 15 micrometers using a copper sulfate plating solution.
For the electroplated substrate, a general spray-type peeling machine was used under the conditions of 50 ° C., spray pressure 2.0 kg / cm ² , 1 minute using a stripping solution RS-2000 (product name, manufactured by Atotech). The plating resist was peeled off.
As shown in FIG. 1 (f), CZ-8100 (MEC Co., Ltd.) was used as a liquid for removing the underlying copper and forming irregularities on the surface of the conductor circuit of the substrate plated with pattern on the electroless copper plating 6. The surface of the base copper and the surface of the conductor circuit were simultaneously roughened using a product made by the company. The etching amount was set at 3 μm.
The heat treatment was performed using a general hot air dryer under conditions of 150 ° C. and 60 minutes.
In order to remove the plating catalyst in the exposed portion of the resin surface of the substrate from which the base copper was removed, a 7% alkaline permanganate aqueous solution as a roughening agent was used, and the temperature was 70 ° C. for 5 minutes. Processed with conditions.
Step n.
In order to prevent oxidation of the copper surface, the substrate was immersed in a 1 wt% aqueous solution of benzotriazole.
Steps b to n were repeated to produce a two-layer buildup substrate.
[0029]
Reference example 1
It was produced in the same manner as in Example 1 except that NBD (trade name, manufactured by Ebara Densan Co., Ltd.) was used instead of the etching solution in Example 1.
[0030]
Reference example 2
It was produced in the same manner as in Example 1 except that CPE-900 (trade name, manufactured by Mitsubishi Gas Chemical Co., Ltd.) was used instead of the etching solution in Example 1.
[0031]
Comparative Example 1
Instead of the etching solution of Example 1, ammonium persulfate was used as the etching solution for electroless plating copper.
[0032]
Comparative Example 2
Instead of the etching solution of Example 1, a cupric chloride etching solution was used as an etching solution for electroless plating copper.
[0033]
Comparative Example 3
Instead of the etching solution of Example 1, a ferric chloride etching solution was used as an etching solution for electroless plating copper.
[0034]
The following tests were performed on the substrates produced as described above. The results are shown in Table 1.
(test)
-Vapor phase thermal shock test: Thermal shock tester Therma Shock Chamber TSR-103 (manufactured by Tabai, trade name) -65 ° C, 30 minutes to 125 ° C, 30 minutes as one cycle, and change in connection resistance It was measured. The connection resistance was measured using a Hewlett-Packard multimeter 3457A.
[0035]
[Table 1]

(Fine wiring formability)
・X : L / S = 50 μm / 50 μm Wiring cannot be formed ○: L / S = 30 μm / 30 μm Wiring can be formed ・ ◎: L / S = 20 μm / 20 μm Wiring can be formed (vapor phase thermal shock test)
* : Conduction resistance change rate of 10% or more at less than 500 cycles-○: Conduction resistance change rate of 10% or more at 500 cycles or more and less than 1000 cycles-A: Conduction resistance change rate of less than 10% at 1000 cycles or more
【The invention's effect】
As described above, according to the present invention, it is possible to provide a method for manufacturing a multilayer printed wiring board that is thin in layers, miniaturized wiring, excellent in connection reliability of IVH, and excellent in productivity.
[Brief description of the drawings]
FIGS. 1A to 1F are cross-sectional views showing respective steps for explaining an embodiment of the present invention.
[Explanation of symbols]
1. Inner layer circuit 2. hole filling material Inner layer circuit board 4. 4. Thermosetting resin IVH 6. 6. Electroless copper plating Plating resist 8. Electroless plating copper etching9. Build-up board

Claims (2)

In the method of manufacturing a printed wiring board in which a resin layer is formed on an inner layer circuit board having an inner layer circuit, a hole reaching the inner layer is formed, the inner wall of the hole is metalized, and an outer layer circuit is formed, the surface of the resin layer is electrolessly formed. Form the base copper plating by copper plating , form a plating resist on the surface of the base copper plating , form a conductor in the shape of the circuit by electrolytic copper plating , remove the plating resist, and the base copper that was under the plating resist the plating, thereby forming an outer layer circuit are etched away with an etchant mainly composed of formic acid, to roughen the surface, immersing the printed wiring board benzotriazole solution, a further resin layer on the outer surface of the circuit A method of manufacturing a printed wiring board to be formed . The printed wiring board manufactured by the method of Claim 1.

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