JP2000068626A - Manufacture of printed wiring board - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of manufacturing a printed wiring board, which is excellent in electrical characteristics, by a method wherein nickel-plated layers are respectively formed reliably in apertures formed in a solder resist layer and bonding of the nickel-plated layers to solder bumps is ensured. SOLUTION: This method of manufacturing a printed wiring board has a process, wherein a solder resist layer 10 is formed on conductor circuits 3 a board then, apertures having such a hole diameter as at least one part of a pad part forming one part of each conductor circuit 3 is exposed are formed at the positions, where correspond to the pad parts, on the layer 10 and after that, after nickel-plated layers 12 and gold-plated layers 13 are respectively formed in order in these apertures, solder bumps 14 are formed. At the the time of formation of the layers 12, the board is vibrated 20 times/minute or more respectively in the directions parallel and vertical to the board.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a printed wiring board in which a nickel plating layer is reliably formed in an opening of a solder-resist layer and there is no defective connection with a solder bump.

[0002]

2. Description of the Related Art In general, a solder bump or the like is formed on a surface layer of a printed wiring board for mounting an IC chip or the like, and a solder resist layer is provided so that these solder bumps are not fused to each other. Specifically, a solder resist layer is formed on the conductor circuit formed on the substrate, and then at least one of the pad portions is provided on the solder resist layer at a position corresponding to the pad portion forming a part of the conductor circuit. An opening having a hole diameter at which the portion is exposed is formed. Thereafter, a nickel plating layer and a gold plating layer are sequentially formed in the opening, and then a solder paste or the like is printed and reflowed to form a solder bump.

[0003]

As a means for forming a nickel plating layer in the opening of the solder-resist layer, it is preferable to use an electroless plating method from the viewpoint of uniform electrodeposition. Is because the plating deposition reaction does not occur in the opening or because the reaction is stopped, etc.
In some cases, the thickness of the nickel layer is reduced, or the nickel layer is not formed. As a result, there has been a problem that the bonding with the solder bumps cannot be performed, and a poor connection between the IC chip and the printed wiring board occurs.

A main object of the present invention is to provide a method for manufacturing a printed wiring board having excellent electrical connectivity by reliably forming a nickel plating layer in an opening of a solder resist layer and ensuring bonding with a solder bump. Is to provide.

[0005]

As described above, when a nickel plating layer is formed in an opening of a solder resist layer, a plating reaction may not occur or may stop.

Therefore, the present inventors diligently studied the cause, and found that bubbles remained in the opening or that the nickel plating solution was not sufficiently supplied into the opening due to hydrogen gas generated when the nickel plating layer was formed. By
It was found that unreaction and reaction termination occurred.

Further, as a result of further research based on the findings, in order to make the thickness of the nickel plating layer uniform, plating was performed while rocking the substrate in directions parallel and perpendicular thereto. However, by setting the number of swings to 20 times / minute or more, and by eliminating bubbles and hydrogen gas remaining in the opening,
It was found that the supply of the nickel plating solution into the opening became stable, and the nickel plating layer could be formed reliably.

That is, when the nickel plating layer is formed in the opening of the solder-resist layer, the number of swings in the directions parallel and perpendicular to the substrate is increased, and the opening and the surface of the solder-resist layer are formed. By eliminating attached air bubbles and hydrogen gas, the plating layer can be formed stably and reliably, and as a result, the bonding with the solder bumps becomes stable and excellent electrical connectivity can be obtained. Success,
The present invention has been completed.

The gist configuration of the present invention is as follows. Forming a solder resist layer on the conductor circuit formed on the substrate, and then exposing at least a part of the pad portion at a position of the solder resist layer corresponding to the pad portion forming a part of the conductor circuit; Forming an opening having a diameter, and then forming a nickel plating layer and a gold plating layer in this opening in order to form a solder bump, and then forming the nickel plating layer. In this case, the substrate is oscillated at least 20 times / min in directions parallel and perpendicular to the substrate.

[0010] Here, "oscillation in a direction parallel to the substrate" specifically means oscillation on a plane including the substrate surface, and "oscillation in a direction perpendicular to the substrate". "Swing in the direction" specifically means a swing in the thickness direction of the substrate.

Further, it is preferable that the nickel plating layer is formed by electroless plating. Further, the swinging of the substrate in the parallel and vertical directions is performed simultaneously, or
It is preferable to alternately perform each reciprocation. In addition, the swing distance of the substrate in the parallel and vertical directions is 5
More preferably, it is in the range of ３０30 cm.

[0012]

Next, a method for manufacturing a printed wiring board according to the present invention will be described. The manufacturing method described below is a case where a printed wiring board is manufactured using a semi-additive method. However, the present invention is not limited to this method. For example, a printed wiring board is manufactured using a full additive method. May be manufactured.

The printed wiring board is manufactured according to the procedure shown in FIGS. As the substrate, a substrate 1 such as a glass epoxy substrate, a polyimide substrate, a resin insulating substrate such as a bismaleimide-triazine resin substrate, a ceramic substrate, or a metal substrate is used.

In the manufacture of a printed wiring board, first, as shown in FIG.
After forming a roughened layer on the conductive circuit 3 by plating or etching, the filling resin 4 is filled in the through hole 2. Next, an adhesive layer 5 for electroless plating is formed, and an opening 6 for forming a via hole is formed at a predetermined position of the adhesive layer 5 (FIG. 2). Thereafter, the surface of the adhesive layer 5 is roughened to a roughened surface (FIG. 3), and a thin electroless plating layer 7 is formed on the entire roughened surface (FIG. 4). And
A plating resist 8 was formed (FIG. 5), and a thick electroplating layer 9 was formed in a portion where no plating resist was formed (FIG. 6).
Thereafter, the plating resist 8 is removed, and etching treatment is performed.
A conductor circuit including the electroplating layer 9 and the electroless plating layer 7 is formed (FIG. 7). 3 to 7 if necessary.
By repeating this step, a further multilayered conductor circuit can be formed on the upper layer (FIG. 8). It is preferable that all the conductor circuits are formed of a copper pattern.

[0015] The adhesive layer for electroless plating is cured, and particles made of a heat-resistant resin which is soluble in an acid or an oxidizing agent (hereinafter referred to as "resin particles") are uncured and converted into an acid or an oxidizing agent. Optimally, it is formed of a mixture dispersed in a matrix of a hardly soluble heat-resistant resin (hereinafter referred to as “resin matrix”).

That is, when the adhesive layer for electroless plating is formed from the above mixture, the resin particles are dissolved and removed by treating with an acid or an oxidizing agent, and the surface is formed of a coarse octopus-shaped anchor. Surface can be formed.

As the resin particles, it is preferable to use amino resin (melamine resin, urea resin, guanamine resin), epoxy resin powder and the like.

As the powder used for the resin particles,
Heat-resistant resin powder having an average particle size of 10 μm or less, aggregated particles obtained by aggregating a heat-resistant resin powder having an average particle size of 2 μm or less,
A mixture of a heat-resistant resin powder having an average particle diameter of 2 to 10 μm and a heat-resistant resin powder having an average particle diameter of 2 μm or less, and an average particle diameter of 2 μm on the surface of the heat-resistant resin powder having an average particle diameter of 2 to 10 μm.
m, a heat-resistant resin powder having an average particle diameter of 0.1 to 0.8 μm, and a pseudo particle obtained by adhering at least one of a heat-resistant resin powder and an inorganic powder having an average particle diameter of 0.1 to 0.8 μm.
It is desirable to use a mixture with a heat-resistant resin powder having a diameter of more than 8 μm and less than 2 μm, and a heat-resistant resin powder having an average particle diameter of 0.1 to 1.0 μm. By using these, a more complicated anchor can be formed.

The resin matrix is preferably composed of a "resin composite composed of a thermosetting resin and a thermoplastic resin" or a "resin composite composed of a photosensitive resin and a thermoplastic resin". That is, the former has high heat resistance, and the latter can form an opening for via hole by photolithography.

As the thermosetting resin, it is preferable to use an epoxy resin, a phenol resin, a polyimide resin or the like, and as the photosensitive resin, methacrylic acid, acrylic acid or the like is used to acrylate the thermosetting group. It is most preferable to use a reaction product, particularly an acrylate of an epoxy resin.

As the epoxy resin, it is preferable to use a novolak type epoxy resin such as a phenol novolak type or a cresol novolak type, or an alicyclic epoxy resin modified with dicyclopentadiene.

Examples of the thermoplastic resin include polyether sulfone (PES), polysulfone (PSF), polyphenylene sulfone (PPS), polyphenylene sulfide (PPES), and polyphenyl ether (PP).
It is preferable to use E), polyetherimide (PI) and the like.

The mixing ratio of the thermosetting resin to the thermoplastic resin and the mixing ratio of the photosensitive resin to the thermoplastic resin are both excellent in toughness and durability without impairing the heat resistance. From the point of securing the physical properties of
It is preferable to set it in the range of 95/5 to 50/50.

The mixing ratio of the resin particles is in the range of 5 to 50% by weight, preferably 10 to 40% by weight, based on the solid content of the resin matrix. The adhesive layer for electroless plating may be composed of two layers having different compositions.

After forming the conductor circuit on the substrate, an interlayer insulating resin layer is formed on the conductor circuit.

In this case, a roughened layer is formed on the conductor circuit in order to improve the adhesion between the conductor circuit and the interlayer insulating resin layer. As the method, there is a method of depositing a roughened layer by electroless plating, or a method of forming a roughened layer by etching.

The method of forming a roughened layer on a conductor circuit can be applied to the case where a roughened layer is formed on a solder-resist layer. In this case, however, the Sn layer is not formed on the roughened layer. .

As the interlayer insulating resin layer, the same one as the above-mentioned adhesive layer for electroless plating can be used.

Next, an opening for forming a via hole is provided in the interlayer resin layer while the interlayer insulating resin layer is cured. The curing treatment of the interlayer insulating resin layer is performed using heat or ultraviolet rays. The via hole forming opening provided in the interlayer resin layer is formed using laser light, oxygen plasma or the like when the interlayer insulating resin layer is a thermosetting resin,
When the interlayer insulating resin layer is a photosensitive resin, it is formed by exposure and development processing.

In the exposure and development processing, a photomask (preferably a glass substrate) on which a circular pattern for forming an opening for forming a via hole is drawn is placed on the circular pattern side with a photosensitive interlayer. After being placed in close contact with the resin insulating layer, exposure and development are performed.

Then, the surface of the interlayer resin insulating layer provided with the via hole forming opening is roughened. In particular, in the present invention,
When the interlayer resin insulation layer has the same structure as the adhesive layer for electroless plating, the surface of the interlayer resin insulation layer is roughened by dissolving and removing the resin particles present on the surface with an acid or an oxidizing agent. Thus, a roughened layer is formed on the interlayer insulating resin layer.

As the acid treatment, phosphoric acid, hydrochloric acid, sulfuric acid, or an organic acid such as formic acid or acetic acid can be used.
Particularly, an organic acid is suitable for an acid treatment solution because it hardly corrodes a metal conductor layer exposed from a via hole when a roughening treatment is performed.

In the oxidation treatment, it is desirable to use chromic acid or permanganate (such as potassium permanganate).

The surface roughness of the roughened layer is preferably such that the maximum height Ry, which is one of the parameters representing the surface roughness, is in the range of 0.1 to 20 μm.

If the value of the maximum height Ry is larger than 20 μm, the roughened layer itself is liable to be damaged or peeled off. On the other hand, if the value of the maximum height Ry is smaller than 0.1 μm, the adhesion becomes poor. Is likely to decrease. In particular, in the semi-additive method, the value of the maximum height Ry is set to 0. 0 in order to enable the removal of the electroless plating layer while securing the adhesion.
It is preferable to set it in the range of 1 to 5 μm.

Next, after a catalyst nucleus is provided on the interlayer insulating resin having the roughened layer formed thereon, a thin electroless plating layer is formed on the entire surface thereof. This electroless plating layer is preferably formed by electroless copper plating, and has a thickness of 1 to 5 μm, more preferably 2 to 3 μm.

Incidentally, as the electroless copper plating solution, those having a general solution composition can be used.
29 g / l, sodium carbonate: 25 g / l, EDTA:
140 g / l, sodium hydroxide: 40 g / l, 37%
A liquid composition consisting of 150 ml of formaldehyde (PH = 11.5) is conceivable.

Further, a photosensitive resin film (dry film) is laminated on the electroless plating layer formed as described above, and a photomask (preferably, a plating resist pattern is drawn on the photosensitive resin film). A glass substrate) is placed in close contact with the substrate and exposed and developed to form a plating resist pattern to form a non-conductive portion.

Thereafter, an electroplating layer is formed on a conductor portion other than the non-conductor portion on the electroless copper plating layer, and a conductor circuit and a conductor portion serving as a via hole are provided. The electroplating layer is preferably formed by electrocopper plating, and its thickness is preferably 10 to 20 μm.

Next, after removing the plating resist of the non-conductive circuit portion, a mixed solution of sulfuric acid and hydrogen peroxide or an etching solution such as sodium persulfate, ammonium persulfate, ferric chloride, cupric chloride, etc. To remove the electroless plating layer to obtain an independent conductor circuit and a via hole consisting of two layers, an electroless plating layer and an electroplating layer. The palladium catalyst nuclei on the roughened surface exposed to the non-conductive portion are dissolved and removed with chromic acid, sulfuric acid and hydrogen peroxide.

Thereafter, a roughened layer is formed on the surface conductor circuit. The formed roughened layer is etched, polished,
It is desirable that the surface be a roughened surface of copper formed by an oxidation treatment or a redox treatment or a roughened surface formed by a plating film. The conductor circuit used in the present invention is desirably formed of an electroless plating layer or a composite layer of the electroless plating layer and the electroplating layer. This is because a roughened surface is not easily formed in a conductor circuit obtained by etching a rolled copper foil.

Next, as shown in FIG. 9, a solder-resist layer 10 is formed on the conductor circuit 3 on which the roughened layer has been formed. The thickness of the solder resist layer 10 is 5 to 40 μm
It is preferable to set it in the range. If the thickness is less than 5 μm, it may not be possible to function sufficiently as a solder dam. If the thickness is more than 40 μm, it is difficult to form an opening provided in the solder resist layer 10 thereafter. In addition to this, the contact with the solder bumps causes cracks to occur in the solder bumps.

As the solder resist layer 10, various resins can be used. For example, bisphenol A type epoxy resin, acrylate of bisphenol A type epoxy resin, novolak type epoxy resin, acrylate of novolak type epoxy resin may be used as an amine-based curing agent or the like. A resin cured with an imidazole curing agent or the like can be used.

In particular, when an opening is provided in the solder resist layer 10 to form a solder bump, the solder bump is formed of "novolak-type epoxy resin or acrylate of novolak-type epoxy resin" and containing "imidazole curing agent" as a curing agent. Is preferred.

The solder resist layer 10 having such a configuration
Has the advantage that the migration of lead (the phenomenon that lead ions diffuse in the solder resist layer) is small. Moreover, the solder resist layer 10 is a resin layer obtained by curing an acrylate of a novolak type epoxy resin with an imidazole curing agent, is excellent in heat resistance and alkali resistance, does not deteriorate even at a temperature at which the solder melts (around 200 ° C.), It is not decomposed by a strongly basic plating solution such as nickel plating or gold plating.

However, since such a solder resist layer 10 is formed of a resin having a rigid skeleton, peeling is likely to occur. Therefore, if the surface on which the solder resist layer 10 is formed is the roughened layer, such peeling can be effectively prevented.

The acrylate of the novolak type epoxy resin is preferably an epoxy resin obtained by reacting glycidyl ether of phenol novolak or cresol novolak with acrylic acid or methacrylic acid.

The above imidazole curing agent is desirably liquid at 25 ° C. This is because a liquid can be uniformly mixed. As such a liquid imidazole curing agent,
1-benzyl-2-methylimidazole, 1-cyanoethyl-
It is preferable to use 2-ethyl-4-methylimidazole and 4-methyl-2-ethylimidazole. The addition amount of the imidazole curing agent is desirably 1 to 10% by weight based on the total solid content of the solder resist composition. The reason for this is that if the added amount is within this range, uniform mixing can be easily obtained.

The composition before curing of the solder resist layer 10 desirably uses a glycol ether-based solvent as a solvent. The solder resist layer 10 using such a composition does not generate free oxygen, does not oxidize the copper pad surface, and has little harm to the human body.

The glycol ether solvents include the following
It is more preferable to use at least one of the structural formulas represented by the formula (A), particularly preferably diethylene glycol dimethyl ether (DMDG) and triethylene glycol dimethyl ether (DMTG). This is because these solvents can completely dissolve benzophenone and Michler's ketone as reaction initiators by heating at about 30 to 50 ° C.

CH ₃ O— (CH ₂ CH ₂ O) _n —CH ₃ (n = 1 to 5) --- (A) The glycol ether solvent is based on the total weight of the solder resist composition. Preferably, it is in the range of 10 to 40% by weight.

The solder resist layer 1 as described above
0, in addition to the above composition, furthermore, various antifoaming agents and leveling agents, thermosetting resin for improving heat resistance and base resistance and imparting flexibility, and improving resolution. For this purpose, a photosensitive monomer or the like can be added.

For example, it is preferable to use an acrylic ester polymer as the leveling agent, and to use Irgacure I manufactured by Ciba Geigy as the initiator.
907 is preferably used, and DETX-S manufactured by Nippon Kayaku is preferably used as the photosensitizer.

Further, when the solder resist layer 10 needs to play a role of hiding the wiring pattern,
It is preferable to further add a dye or pigment to the composition constituting the solder resist layer 10. It is desirable to use, for example, phthalocyanine green as the dye.

As the thermosetting resin as the additional component, for example, a bisphenol type epoxy resin can be used. The bisphenol type epoxy resin includes a bisphenol A type epoxy resin and a bisphenol F type epoxy resin. The former is a case where basic resistance is emphasized, and the latter is a case where low viscosity is required (evaluation of applicability). It is preferable to use each of them.

As the photosensitive monomer as the additional component, for example, a polyvalent acrylic monomer can be used. This is because the polyvalent acrylic monomer can improve the resolution. For example, a polyacrylic monomer is desirable.

The composition of the solder resist layer 10 has a viscosity of 0.5 to 10 Pa · s at 25 ° C.
And more preferably 1 to 10 Pa · s
It is. This is because if the viscosity is within the above range, application with a roll coater is easy.

After the formation of the solder-resist layer 10, the opening 11 having a hole diameter at which at least a part of the pad 19 is exposed is exposed at a position corresponding to the pad 19 forming a part of the conductor circuit 3. A nickel plating layer 12 is formed in the opening 11 of the solder-resist layer 10 by electroless plating (see FIG. 10).

Prior to the formation of the nickel plating layer 12,
First, the surface of the opening 11 of the solder-resist layer 10 is washed with a degreasing solution, and a catalyst such as palladium is applied to the opening 1.
A process of applying and activating the conductor portion exposed from the step 1 is performed.

In the present invention, when forming the nickel plating layer 12, it is essential that the substrate be rocked at least 20 times / min in directions parallel and perpendicular to the substrate, respectively. By adopting this configuration, bubbles and hydrogen gas remaining in the opening 11 can be eliminated, the supply of the nickel plating solution into the opening 11 can be stabilized, and the nickel plating layer 12 can be reliably formed. As a result, bonding with the solder bumps 14 is stabilized, and excellent electrical connectivity can be obtained.

The swinging of the substrate in the parallel and vertical directions may be performed simultaneously or alternately with each reciprocation, but the former remains in the opening 11. This is preferable because bubbles and hydrogen gas can be removed more effectively.

The swing distance of the substrate in the parallel and vertical directions is preferably in the range of 5 to 30 cm.

If the distance of the swing in the parallel direction (hereinafter referred to as "vertical swing") is smaller than 5 cm, the opening 11
This is because it is not possible to sufficiently eliminate bubbles and hydrogen gas remaining in the substrate, and if it exceeds 30 cm, the impact on the substrate increases.

When the vertical swing distance (hereinafter referred to as “lateral swing”) is smaller than 5 cm, the opening 11
This is because it is not possible to sufficiently remove bubbles and hydrogen gas remaining in the substrate, and if it exceeds 30 cm, the substrate tends to warp.

A specific example in which the nickel plating layer 12 is formed by the above method will be described for reference. For example, after immersion in a predetermined electroless nickel plating solution, the vertical swing distance is set to 20 cm and the vertical The nickel plating layer 12 is formed while the substrate is oscillated under the conditions that the number of oscillations is 20 times / minute, the distance of the horizontal oscillation is 15 cm, and the number of times of the horizontal oscillation is 35 times / minute. do it.

The thickness of the nickel plating layer 12 is 0.5 to 2
It is preferably in the range of 0 μm, more preferably 3 to
The range is 10 μm. The thickness of the nickel plating layer 12 is
If it is less than 0.5 μm, the solder bump 14 and the nickel plating layer
This is because it is difficult to obtain a sufficient connection of 12
m, the solder bumps 14 cannot be completely accommodated in the openings 11, and the adjacent bumps may be bonded to each other,
This is because 14 and the nickel plating layer 12 are easily peeled off.

The electroless plating solution used for forming the nickel plating layer 12 will be described. The electroless plating solution is composed of a nickel compound, a reducing agent, a complexing agent, a buffer, and an additive.

As the nickel compound, nickel sulfate,
Nickel chloride, nickel acetate, nickel carbonate, nickel sulfamate, nickel formate and the like are used, and it is particularly preferable to use nickel sulfate and nickel chloride.

As the reducing agent, sodium hypophosphite,
Dimethylamine borane (DMAB), formaldehyde, sodium tetrahydroborate, glyoxylic acid and the like are used, and it is particularly preferable to use sodium hypophosphite.

Acetic acid, sodium acetate,
Lactic acid, oxalic acid, oxalate, citric acid, citrate,
O-coordination compounds such as tartaric acid, tartrate, succinic acid, succinate, glutamic acid, salicylic acid, malonic acid and malic acid; N-coordination compounds such as thiaglycolic acid; ammonia, hydrazine and triethano -Lamine,
Glycine, alanine, asuraparagine, iminodiacetic acid,
At least one compound is used from the compound group of N-coordination compounds such as pyridine, ethylenediamine, ethylenediaminetetraacetic acid, quadrol and o-aminophenol. In particular, it is desirable to use citric acid, ammonia, hydrazine, and ethylenediaminetetraacetic acid.

Examples of the buffer include monocarboxylic acids such as formic acid, acetic acid, propionic acid, butyric acid, acrylic acid and trimethylacetic acid, oxalic acid, succinic acid, malonic acid, maleic acid, and the like.
Dicarboxylic acids such as itaconic acid, glycolic acid, lactic acid,
Salicylic acid, tartaric acid, oxycarboxylic acids such as citric acid, boric acid, carbonic acid, using inorganic acids such as sulfurous acid,
In particular, it is desirable to use formic acid, acetic acid, and boric acid.

Examples of the additives include a surfactant which gives a gloss to the plating film, a sulfur compound which reduces the catalytic activity, a nitrogen compound, a lead ion, a sulfide or a fluoride ammonium salt which promotes the plating reaction, a nitrate, a chlorate, Molybdenum salt, tungsten salt, lead chloride which suppresses decomposition of plating,
Stabilize plating baths and plating films by using trace amounts of lead sulfide, lead nitrate, thiourea, potassium rhodanate, and selenic acid, which suppress the generation of hydrogen gas in the reaction.

Specific examples of the composition of the plating solution for forming the nickel plating layer 12 will be described for reference. For example, nickel sulfate 4.5 g / l, sodium hypophosphite 25 g / l, citric acid Sodium 40g / l, boric acid 1
The plating solution may be composed of 2 g / l and thiourea 0.1 g / l (PH = 4.5). Alternatively, a commercially available plating solution, for example, “Nimden NPR-4” manufactured by Uemura Kogyo can be used.

After forming the nickel plating layer 12, as shown in FIG. 10, a gold plating layer 13 is formed by gold plating. The thickness of the gold plating layer 13 is 0.01 to 0.10
μm, more preferably 0.03 μm
Before and after.

After forming the gold plating layer 13, solder bumps 14 are formed as shown in FIG. The formation of the solder bumps 14 is preferably performed, for example, by applying a solder paste and performing a reflow process.

The above is only an example of the embodiment of the present invention, and various changes can be made within the scope of the claims.

[0077]

EXAMPLE A printed wiring board was manufactured according to the manufacturing method of the present invention, and will be described below.

(Examples) (1) A copper-clad laminate in which 18 μm copper foil is laminated on both surfaces of a substrate made of glass epoxy resin or BT (bismaleimide triazine) resin having a thickness of 1 mm was used as a starting material. First, the copper-clad laminate was drilled, subjected to an electroless plating treatment, and etched in a pattern to form an inner copper pattern and through holes on both surfaces of the substrate.

(2) The substrate on which the inner layer copper pattern and the through hole are formed is washed with water, dried, and then subjected to an oxidation bath (blackening bath).
NaOH (10 g / l), NaClO ₂ (40 g / l),
Na ₃ PO ₄ (6 g / l), NaOH (10 g /
1) A roughened layer was provided on the inner surface of the inner layer copper pattern and the through hole by oxidation-reduction treatment using NaBH ₄ (6 g / l).

(3) As shown in FIG. 12 (a), a resin filler 15 produced by mixing and kneading a raw material composition for preparing a resin filler composed of a resin composition and a curing agent composition was mixed with After filling the inside of the through hole 16 within 24 hours after the preparation, drying it at 100 ° C. for 20 minutes, it is applied to both sides of the substrate 17 by printing to fill the space between the conductor circuits 18 (FIG. 12B). ), Dried at 100 ° C for 20 minutes,
In the same manner, apply the resin filler 15 to the other
Fill between 18 or through hole 16
Heat drying for 20 minutes.

The resin composition is a bisphenol F type epoxy monomer (manufactured by Yuka Shell, molecular weight 310, YL983U).
00 parts by weight, SiO ₂ spherical particles having an average particle size of 1.6 μm coated with a silane coupling agent on the surface (manufactured by Admatech, CRS 1101-CE, where the maximum particle size is the thickness of an inner copper pattern described later (Less than 15μm)
170 parts by weight and 1.5 parts by weight of a leveling agent (manufactured by San Nopco, Perenol S4) are obtained by adjusting the viscosity of the mixture to 45,000 to 49,000 cps at 23 ± 1 ° C. by stirring and mixing. Used 6.5 parts by weight of an imidazole curing agent (2E4MZ-CN, manufactured by Shikoku Chemicals).

(4) As shown in FIG. 12 (c), one side of the substrate 17 after the processing of (3) is subjected to belt sanding using # 600 belt abrasive paper (manufactured by Sankyo Rikagaku). Polishing was performed so that the resin filler 15 did not remain on the surface of the inner layer copper pattern 18 and the surface of the land constituting the through hole 16, and then buffing was performed to remove the scratches caused by the belt sander polishing. Such a series of polishing was similarly performed on the other surface of the substrate.

Next, at 100 ° C. for 1 hour and at 150 ° C. for 1 hour.
The resin filler was cured by performing a heat treatment for a time. In this way, the surface layer of the resin filler filled in the through holes and the roughened layer on the upper surface of the inner conductor circuit are removed to smooth both surfaces of the substrate, and the resin filler and the side surfaces of the inner conductor circuit are roughened. A wiring board was firmly adhered through the layer, and the inner wall surface of the through hole and the resin filler were firmly adhered through the roughened layer. That is, by this step, the surface of the resin filler and the surface of the inner layer copper pattern become flush with each other.

(5) The printed wiring board on which the conductor circuit is formed is degreased with an alkali and soft-etched, and then treated with a catalyst solution comprising palladium chloride and an organic acid to form
After the catalyst was activated and the catalyst was activated, copper sulfate was added.
2 × 10 ^-2 mol / l, nickel sulfate 3.9 × 10 ^-3 m
ol / l, citric acid 7.8 × 10 ^-3 mol / l, sodium hypophosphite 2.3 × 10 ^-1 mol / l, boric acid 5.
0 × 10 ⁻¹ mol / l, surfactant (manufactured by Nissin Chemical Industry,
Surfel 465) 1.1 × 10 ^-4 mol / l, PH
= 9 and immersed in an electroless plating solution consisting of
Vertically and horizontally oscillating at a rate of once every 4 seconds, the Cu-Ni-
A coating layer of a needle-like alloy plating made of P and a roughened layer were provided.

Further, tin borofluoride 0.1 mol /
1, thiourea 1.0 mol / l, temperature 35 ° C., PH =
A Cu—Sn substitution reaction was performed under the conditions of 1.2, and a 0.3 μm thick Sn layer was provided on the surface of the roughened layer.

(6) An interlayer resin insulating agent (for lower layer) is applied to both sides of the substrate of the above (5) by a roll coater within 24 hours after preparation, and left in a horizontal state for 20 minutes. After drying (pre-baking) for 30 minutes, a photosensitive adhesive solution for electroless plating (for the upper layer) is applied within 24 hours after preparation, left in a horizontal state for 20 minutes, and then left at 60 ° C. for 30 minutes. (Prebaking) to form an adhesive layer having a thickness of 35 μm.

The interlayer resin insulator (for the lower layer) is prepared by stirring and mixing a raw material composition comprising a resin composition, a resin composition and a curing agent composition to adjust the viscosity to 1.5 Pa · s.

The resin composition was prepared by dissolving a 25% acrylated cresol novolak type epoxy resin (manufactured by Nippon Kayaku Co., Ltd., molecular weight 2500) in DMDG at a concentration of 80 wt%.
35 parts by weight, 4 parts by weight of photosensitive monomer (Aronix M315, manufactured by Toa Gosei), 0. Antifoaming agent (S-65, manufactured by San Nopco)
5 parts by weight and 3.6 parts by weight of NMP were obtained by stirring and mixing.

The resin composition was composed of 12 parts by weight of polyether sulfone (PES) and epoxy resin particles (manufactured by Sanyo Chemical Co., Ltd.).
After mixing 14.49 parts by weight of a polymer pole having an average particle size of 0.5 μm, 30 parts by weight of NMP were further added,
It was obtained by stirring and mixing with a bead mill.

The curing agent composition was composed of 2 parts by weight of an imidazole curing agent (2E4MZ-CN, manufactured by Shikoku Chemicals), 2 parts by weight of a photoinitiator (Irgacure I-907, manufactured by Ciba Geigy), and a photosensitizer (manufactured by Nippon Kayaku) , DETX-S) and 1.5 parts by weight of NMP.

The adhesive for electroless plating (for the upper layer) is prepared by stirring and mixing a raw material composition comprising a resin composition, a resin composition and a curing agent composition to adjust the viscosity to 7 Pa · s.

The resin composition was prepared by dissolving 35 parts by weight of a resin solution prepared by dissolving 25% acrylate of a cresol novolac type epoxy resin (manufactured by Nippon Kayaku Co., Ltd., molecular weight: 2500) in DMDG at a concentration of 80% by weight, and a photosensitive monomer (Toa) 3.15 parts by weight of a synthetic product, Aronix M315), 0.5 parts by weight of an antifoaming agent (manufactured by San Nopco, S-65), and 3.6 parts by weight of NMP were obtained by stirring and mixing.

The resin composition used was composed of 12 parts by weight of polyether sulfone (PES) and an epoxy resin particle (manufactured by Sanyo Chemical Industries, polymer pole) having an average particle size of 1.0 μm.
After mixing 30 parts by weight of NMP and 30 parts by weight of NMP, the mixture was stirred and mixed with a bead mill.

The curing agent composition was composed of 2 parts by weight of an imidazole curing agent (2E4MZ-CN, manufactured by Shikoku Kasei), 2 parts by weight of a photoinitiator (Irgacure I-907, manufactured by Ciba Geigy), and a photosensitizer (manufactured by Nippon Kayaku) , DETX-S) 0.2 parts by weight and NMP 1.5 parts by weight with stirring.

(7) A photomask film on which a black circle of 85 μmφ was printed was brought into close contact with both surfaces of the substrate on which the adhesive layer was formed in the above (6), and was exposed at 500 mJ / cm ² by an ultra-high pressure mercury lamp. This was spray-developed with a DMTG solution, and the substrate was exposed at 3000 mJ / cm ² using an ultra-high pressure mercury lamp, followed by heat treatment (100 ° C. for 1 hour, 120 ° C. for 1 hour, and 150 ° C. for 3 hours (post-baking). )
85μ with excellent dimensional accuracy equivalent to a photomask film
Thickness 35 with mφ opening (via hole forming opening)
An interlayer resin insulating layer of μm (two-layer structure) was formed. still,
The tin plating layer was partially exposed in the opening serving as the via hole.

(8) The substrate having the openings formed is treated with chromic acid.
By immersing for 19 minutes, the surface of the interlayer resin insulation layer is roughened by dissolving and removing the epoxy resin particles present on the surface of the interlayer resin insulation layer, and then immersed in a neutralization solution (manufactured by Shipley). And washed with water.

Further, by applying a palladium catalyst (manufactured by Atotech) to the surface of the substrate subjected to the surface roughening treatment (roughening depth: 6 μm), the surface of the interlayer resin insulating layer and the inner wall surface of the opening for the via hole are formed. The catalyst core was attached.

(9) The substrate is immersed in an electroless copper plating solution (solution temperature: 70 ° C.) having the following composition for 30 minutes to form an electroless copper plating layer having a thickness of 0.6 μm on the entire rough surface. did.

[Composition of electroless plating solution] EDTA 150 g / l Copper sulfate 20 g / l HCHO 30 ml / l NaOH 40 g / l α, α'-bipyridyl 80 mg / l PEG 0.1 g / l

(10) A commercially available photosensitive dry film was stuck on the electroless copper plating layer formed in the above (9), a mask was placed, exposed at 100 mJ / cm ² , and developed with 0.8% sodium carbonate. After processing, a plating resist having a thickness of 15 μm was provided.

(11) Next, the conductor portion where the resist is not formed is subjected to electrolytic copper plating under the following plating conditions to a thickness of 15%.
A μm electrolytic copper plating layer was formed.

[Electroplating solution] Sulfuric acid 180 g / l Copper sulfate 80 g / l Additive 1 ml / l Additive: Capparaside GL manufactured by Atotech Japan
And [Electroplating conditions] Current density 1A / dm ² hours 30 minutes Temperature Room temperature

(12) After the plating resist is peeled off with 5% KOH, the electroless plating layer under the plating resist is dissolved and removed by etching with a mixed solution of sulfuric acid and hydrogen peroxide to remove the electroless copper plating layer. And a thickness of 18 consisting of electrolytic copper plating layer
A μm conductive circuit (including via holes) was formed.

(13) The same treatment as in (5) was performed to form a roughened surface made of Cu-Ni-P, and the surface was further substituted with Sn.

(14) By repeating the above steps (6) to (13), a conductor circuit of an upper layer was further formed to obtain a multilayer wiring board. However, no Sn layer was formed on the roughened surface of the uppermost layer.

(15) A solder resist composition having a thickness of 20 μm was applied to both sides of the multilayer printed wiring board obtained in the above (14). Then at 70 ° C. for 20 minutes and 70 ° C. for 30 minutes.
After performing a drying process for 5 minutes, a 5 mm-thick photomask film on which a circular pattern (mask pattern) is drawn is placed in close contact with the substrate, exposed to ultraviolet light of 1000 mJ / cm ² , and DMTG
Developed. Then, at 80 ° C. for one hour, 100
C. for 1 hour, 120.degree. C. for 1 hour, and 150.degree. C. for 3 hours to form an opening 11 including a solder pad 19 (including a via hole and its land) (opening diameter 2).
(00 μm) A solder resist layer 10 (thickness: 20 μm) was formed (see FIG. 10).

The solder resist composition was prepared by dissolving 50% by weight of an epoxy group of a cresol novolac type epoxy resin (manufactured by Nippon Kayaku Co., Ltd.) of 60% by weight dissolved in DMDG, and sensitizing oligomer (molecular weight: 4000) 46.67 g; 80% by weight bisphenol A type epoxy resin dissolved in methyl ethyl ketone (manufactured by Yuka Shell, Epicoat 100
1) 15.0 g, imidazole curing agent (Shikoku Chemicals, 2E4MZ-C
N) 1.6 g, 3 g of a polyvalent acrylic monomer (R604, manufactured by Nippon Kayaku) as a photosensitive monomer, 1.5 g of the same polyvalent acrylic monomer (DPE6A, manufactured by Kyoeisha Chemical Co., Ltd.) -65) was mixed with 0.71 g, and 2 g of benzophenone (manufactured by Kanto Kagaku) as a photoinitiator and 0.2 g of Michler's ketone (manufactured by Kanto Kagaku) as a photosensitizer were added to the mixture to give a viscosity of 25. 2.0Pa at ℃
s. In addition, the viscosity was measured by B
Using a viscometer (DVL-B type, manufactured by Tokyo Keiki Co., Ltd.) with rotor No. 4 at 60 rpm and rotor N at 6 rpm
o.3

(16) Then, nickel chloride 2.3 × 10 ^-1 mo
l / l, sodium hypophosphite 2.8 × 10 ^-1 mol / l and sodium citrate 1.6 × 10 ^-1 mol / l
A vertical swing distance of 2 is applied to the electroless nickel plating solution of H = 4.5.
0cm, vertical swing frequency 30 times / min, and horizontal swing distance 20
The substrate was immersed for 20 minutes while oscillating the substrate under the condition of 20 cm / min and the number of horizontal oscillations of 20 times / min.

(17) Further, the substrate was washed with 7.6 × 10 ⁻³ mol / l of potassium gold cyanide and 1.9 × 10 ³ ammonium chloride.
^-1 mol / l, sodium citrate 1.2 × 10 ^-1 mol /
immersed in an electroless gold plating solution consisting of 1.7 × 10 ^-1 mol / l sodium hypophosphite at 80 ° C. for 7.5 minutes to form a 0.03 μm thick gold plating layer on the nickel plating layer. Formed.

(18) Then, a solder paste was printed on the opening of the solder resist layer and reflowed at 200 ° C. to form a solder bump (solder body), thereby producing a printed wiring board having the solder bump. .

(Comparative Example) Basically the same as Example, except that the number of vertical and horizontal swings performed at the time of forming the nickel plating layer of (16) was 10 times / min.

(Evaluation of Performance) The printed wiring boards manufactured in the above Examples and Comparative Examples were inspected for the occurrence rate of reaction failure of the nickel plating layer and the gold plating layer and the occurrence rate of connection failure with the solder bumps. The quality of the connectivity was evaluated.

The rate of occurrence of a reaction failure of the nickel plating layer and the gold plating layer was calculated from the result of measurement with an optical microscope (magnification: 50 times). The ratio was calculated from the result of a continuity test between the solder bumps and the corresponding conductor wiring.

When the thickness of the nickel plating layer and the thickness of the gold plating layer were measured by an electron microscope (magnification: 1000 times), the thickness of each of the nickel plating layers was 5 μm.
The thickness of each of the gold plating layers was 0.03 μm. Table 1 shows the results of these evaluations.

[0115]

[Table 1]

From the results shown in Table 1, in the comparative example, there was a printed wiring board in which a poor reaction between the nickel plating layer and the gold plating layer occurred and a conduction failure occurred between the solder bump and the corresponding conductor wiring. However, in the example, there was no printed wiring board in which a reaction failure of the nickel plating layer and the gold plating layer and a connection failure with the solder bump occurred.

[0117]

According to the manufacturing method of the present invention, a nickel plating layer can be reliably formed in an opening of a solder resist layer, and a printed wiring having excellent electrical connectivity can be obtained by ensuring bonding with a solder bump. It became possible to provide boards.

[Brief description of the drawings]

FIG. 1 is a view for explaining a step of forming a conductive circuit on a substrate among steps of a method of manufacturing a printed wiring board according to the present invention.

FIG. 2 is a view for explaining a step of forming a conductive circuit on a substrate in the steps of the method for manufacturing a printed wiring board according to the present invention.

FIG. 3 is a view for explaining a step of forming a conductive circuit on a substrate in the steps of the method for manufacturing a printed wiring board according to the present invention.

FIG. 4 is a view for explaining a step of forming a conductive circuit on a substrate among the steps of the method for manufacturing a printed wiring board according to the present invention.

FIG. 5 is a view for explaining a step of forming a conductive circuit on a substrate in the steps of the method for manufacturing a printed wiring board according to the present invention.

FIG. 6 is a view for explaining a step of forming a conductive circuit on a substrate in the steps of the method for manufacturing a printed wiring board according to the present invention.

FIG. 7 is a view for explaining a step of forming a conductive circuit on a substrate in the steps of the method for manufacturing a printed wiring board according to the present invention.

FIG. 8 is a view for explaining a step of forming a conductive circuit on a substrate among the steps of the method for manufacturing a printed wiring board according to the present invention.

FIG. 9 is a diagram for explaining a process from forming a solder resist layer 10 on a substrate on which a conductor circuit is formed to forming a solder bump 14 in an opening 11 thereof.

FIG. 10 is a view for explaining steps from forming a solder resist layer 10 on a substrate on which a conductor circuit is formed to forming a solder bump 14 in an opening 11 thereof.

FIG. 11 is a view for explaining steps from forming a solder resist layer 10 on a substrate on which a conductor circuit is formed to forming a solder bump 14 in an opening 11 thereof.

FIGS. 12 (a) to 12 (c) are views showing some of the steps in order to explain the manufacturing steps of the example.

[Description of Signs] 1 Substrate 2 Through Hole 3 Conductor Circuit 4 Filling Resin 5 Electroless Plating Adhesive Layer 6 Via Hole Forming Opening 7 Electroless Plating Layer 8 Plating Resist 9 Electroplating Layer 10 Solder Resist Layer 11 Opening 12 Nickel plating layer 13 Gold plating layer 14 Solder bump 15 Resin filler 16 Through hole 17 Substrate 18 Conductor circuit 19 Pad part

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 4M105 AA02 AA10 AA13 AA15 AA19 5E343 AA07 AA15 AA16 AA17 AA18 AA22 AA24 BB23 BB34 BB44 BB54 BB55 BB67 BB72 CC33 CC34 CC36 CC38 CC46 CC47 CC48 CC67 CC18 DD33 DD33 DD33 DD33 DD33 DD33 DD33 DD33 5E346 AA53 CC09 CC10 CC16 CC32 CC37 CC38 CC54 DD25 DD33 EE33 FF04 FF13 GG17 HH07

Claims (6)

[Claims] A solder resist layer is formed on a conductor circuit formed on a substrate, and at least one of the pad portions is provided on the solder resist layer at a position corresponding to the pad portion forming a part of the conductor circuit. Forming an opening having a hole diameter at which the portion is exposed, and then, in this opening, forming a nickel plating layer and a gold plating layer, and then forming a solder bump after forming the solder bump. A method for manufacturing a printed wiring board, comprising: swinging the substrate in a direction parallel to and perpendicular to the nickel plating layer at least 20 times / minute when forming the nickel plating layer. 2. The method according to claim 1, wherein the nickel plating layer is formed by electroless plating. 3. The method according to claim 1, wherein the swinging of the substrate in the parallel and vertical directions is performed simultaneously. 4. The method for manufacturing a printed wiring board according to claim 1, wherein the swinging of the substrate in the parallel and vertical directions is performed alternately for each reciprocation. 5. The method for manufacturing a printed wiring board according to claim 1, wherein a swing distance of the substrate in the parallel direction is in a range of 5 to 30 cm. 6. The method for manufacturing a printed wiring board according to claim 1, wherein a swing distance of the substrate in the vertical direction is in a range of 5 to 30 cm.