JP3297006B2 - Multilayer printed wiring board - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multilayer printed wiring board, and more particularly to a multilayer printed wiring board capable of forming a via hole and a fine pattern having a diameter of less than 100 .mu.m and effectively removing the development residue in the via hole. suggest.

[0002]

2. Description of the Related Art In recent years, so-called build-up multilayer wiring boards have been receiving attention due to a demand for higher density of the multilayer wiring boards. This build-up multilayer wiring board is manufactured by a method disclosed in, for example, Japanese Patent Publication No. 4-55555. That is, on the core substrate, a photosensitive adhesive for electroless plating is applied, dried, exposed, and developed to form an interlayer resin insulating layer having a via hole opening. After the surface of the resin insulation layer is roughened by treatment with an oxidizing agent, a plating resist is provided on the roughened surface, and then electroless plating is performed on the non-resist-formed portion to form a conductor circuit pattern including via holes. By repeating such a process a plurality of times, a multilayered build-up wiring board can be obtained.

As an adhesive for electroless plating used for an interlayer resin insulating layer of such a build-up wiring board,
JP-A-63-158156 and JP-A-2-188992 (U.S. Pat.
SP 5,055,321, US Pat. No. 5,589,255), as described in US Pat. No. 5,589,255).
There is a type in which dissolvable resin particles composed of fine particles having a size of μm or less are dispersed in a hardly heat-resistant resin matrix.

Further, Japanese Patent Application Laid-Open No. 61-276875 (USP)
No. 4,752,499, USP 5,021,472) have an average particle size of 1.6.
It discloses that an epoxy resin powder crushed to μm is dispersed in a hardly heat-resistant resin matrix. Further, JP-A-7-34048 (US Pat. No. 5,519,177) discloses a tough epoxy-polyether sulfone (PE
S) An adhesive for electroless plating using a resin composite as a resin matrix is disclosed.

However, when such a build-up multilayer printed wiring board is actually manufactured and an IC chip is mounted,
Since there is no adhesion at the interface between the plating resist and the conductor circuit,
A new problem has been discovered in that a crack is generated in the interlayer resin insulating layer from the interface between the plating resist and the conductor circuit due to the difference in thermal expansion coefficient between the plating resist and the conductor circuit.

On the other hand, as a method of preventing the occurrence of cracks, there is a method of improving the adhesion between the conductor circuit and the interlayer resin insulation layer by removing the plating resist and roughening the side surface of the conductor circuit. Adopted.

As a method for manufacturing a wiring board by removing such a plating resist, a semi-additive method is the most realistic method. In this semi-additive method, the surface of an interlayer resin insulating layer (adhesive layer for electroless plating) is roughened, electroless plating is applied thinly on the entire surface, a plating resist is formed, electrolytic plating is performed, and a thicker layer is formed between the plating resists. In this method, a conductive pattern is formed by providing an electrolytic plating film, removing the plating resist, and dissolving and removing the electroless plating film under the plating resist.

[0008]

However, in the semi-additive method, it is necessary to dissolve and remove the electroless plating film under the plating resist. Therefore, when the anchor of the roughened surface formed on the interlayer resin insulating layer surface is deep,
A conductor is likely to remain in the anchor, which causes a reduction in insulation resistance between wires. If the anchor is deep, the electroless plating film will be excessively etched. Therefore, if a fine pattern such as L / S = 25/25 μm is to be formed, the conductor circuit will be excessively etched. Disconnection occurs. Therefore, in order to remove the conductor in the anchor without performing excessive etching treatment, the anchor on the roughened surface is reduced by reducing the particle size of the heat-resistant resin particles forming the anchor and decreasing the blending amount thereof. It is desirable to make it shallow.

On the other hand, if an attempt is made to provide a fine opening for forming a via hole of less than 100 μmφ in the interlayer resin insulating layer, the developer does not sufficiently flow and residual development occurs, and the bottom of the opening for forming the via hole is formed. Resin tends to remain.
Such resin residue can be dissolved and removed during the roughening treatment of the adhesive layer for electroless plating. This is because heat-resistant resin particles that dissolve in an oxidizing agent and the like also exist in the resin residue. However, in order to advantageously remove the conductor in the anchor, as described above, by reducing the particle size of the heat-resistant resin particles and reducing the blending amount thereof, if the anchor on the roughened surface is made shallow, the rough surface due to an oxidizing agent or the like may be obtained. However, such a roughening treatment causes a problem that the resin residue at the bottom of the via hole cannot be completely removed. Therefore, to remove the resin residue at the bottom of the opening,
It is desirable to increase the particle size of the heat-resistant resin particles and increase the amount thereof.

The present invention derives a configuration of an interlayer resin insulating layer that simultaneously satisfies the two conflicting requirements described above, whereby fine via holes and fine patterns can be formed, and there is no development residue in the via holes. An object is to provide a multilayer printed wiring board having excellent reliability.

[0011]

Means for Solving the Problems The present inventors have made intensive studies to realize the above object. As a result, the amount of heat-resistant resin particles on the inner layer side (substrate side) of the adhesive layer for electroless plating is increased, and the amount of heat-resistant resin particles on the side where the roughened surface is formed (opposite to the substrate) is reduced. As a result, it has been newly found that the above-mentioned problem can be solved.

The present invention is based on such knowledge, and the gist configuration thereof is as follows. (1) On a substrate on which a conductive circuit is formed, a cured heat-resistant resin particle that is soluble in an acid or an oxidant is dispersed in a cured heat-resistant resin matrix that is hardly soluble in an acid or an oxidant. An adhesive layer for electrolytic plating is formed, and the surface of the adhesive layer for electroless plating has a roughened surface formed by dissolving and removing heat-resistant resin particles, and an upper layer side is formed on the roughened surface. In a multilayer printed wiring board on which a conductor circuit is formed, the adhesive layer for electroless plating is composed of two layers.
Heat-resistant resin particles in the adhesive layer for electroless plating on the substrate side.
The blending amount of the particles is based on the solid content of the heat-resistant resin matrix
20 to 50% by weight, the other being for electroless plating
The amount of heat-resistant resin particles in the agent layer depends on the heat-resistant resin matrix.
5% by weight or more and less than 20% by weight based on the solid content of
There is provided a multilayer printed wiring board.

[0013]

In the multilayer printed wiring board according to the above (1), the heat-resistant resin particles have an average particle size of 0.1 to 1.0 μm.
It is preferable that The heat-resistant resin matrix of the adhesive for electroless plating is composed of a composite of an epoxy resin and PES, and the amount of PES in the composite is less than 30% by weight based on the solid content of the heat-resistant resin matrix. Is preferred. The adhesive layer for electroless plating has a diameter of 100
It is preferable that a via hole of less than μm is formed. The conductor circuit preferably includes an electroless plating film and an electrolytic plating film. It is preferable that a roughening layer is formed on at least a part of the surface of the conductor circuit on the substrate.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The multilayer printed wiring board of the present invention
The feature is that the amount of heat-resistant resin particles in the adhesive layer for electroless plating constituting the interlayer resin insulation layer is reduced on the side where the roughened surface is formed and increased on the opposite side (substrate side). is there. That is, for the electroless plating in the present invention
The adhesive layer consists of two layers, and the substrate side (lower side) is electroless
The amount of heat-resistant resin particles in the adhesive layer
20 to 50% by weight based on the solid content of the resin matrix
Yes, the other (upper side) of the adhesive layer for electroless plating
The amount of the heat-resistant resin particles depends on the solidity of the heat-resistant resin matrix.
Not less than 5% by weight and less than 20% by weight
It is a feature. Here, the compounding amount of the heat-resistant resin particles in the lower layer is such that the resin residue can be removed during the roughening treatment, and the inner wall at the bottom of the via hole is not too large by the roughening treatment. The blending amount of the particles is within a range where the anchor on the roughened surface can be made shallow so as not to excessively lower the peel strength. So this
According to the structure of the interlayer resin insulating layer as described above, the shallow rough surface and the high
Fine pattern and fine
Providing multilayer printed wiring boards with via holes
Can be

In the present invention, the heat-resistant resin particles preferably have an average particle size of 0.1 to 1.0 μm.
The reason is that if the average particle size of the heat-resistant resin particles is within the above range, the anchor on the roughened surface is shallow, the conductor between the lines can be prevented, and a fine pattern (L / S = 25/25 μm) is realized. Because you can. Also, the roughening treatment does not increase the diameter of the via hole and does not lose the ability to remove the undeveloped portion.

[0017]

It is necessary that the heat-resistant resin particles have been previously cured. The reason is that the heat-resistant resin particles are dissolved in a solvent that dissolves the resin matrix when not cured, are uniformly mixed with the resin matrix, and the resin particles alone cannot be selectively dissolved and removed with an acid or an oxidizing agent. Because.

As the heat-resistant resin matrix, it is possible to use a thermosetting resin (including one obtained by sensitizing a part of the thermosetting group), a photosensitive resin, or a composite of these resins and a thermoplastic resin. it can. As the thermosetting resin, an epoxy resin, a phenol resin, a polyimide resin, or the like can be used. When sensitizing the thermosetting resin, the thermosetting group is subjected to an acrylate reaction with methacrylic acid, acrylic acid, or the like. Particularly, acrylate of epoxy resin is most suitable. As the epoxy resin, a novolak type epoxy resin, an alicyclic epoxy resin, or the like can be used. As the thermoplastic resin, polyether sulfone, polysulfone, polyphenylene sulfone, polyphenylene sulfide, polyphenyl ether, polyether imide and the like can be used.

In the present invention, it is particularly preferable to use a composite of epoxy resin (including acrylate of epoxy resin) and polytersulfone (PES) as the heat-resistant resin matrix. This is because toughening is possible.
In this case, the amount of PES is preferably less than 30% by weight, more preferably 15 to 25% by weight, based on the solid content of the heat resistant resin matrix. The reason is that if the amount of PES is increased,
This is because, when the diameter of the via hole is reduced, PES remains at the bottom of the via hole, and it is difficult to remove the PES by roughening.

As the heat resistant resin particles, amino resin (melamine resin, urea resin, guanamine resin, etc.), epoxy resin, bismaleimide-triazine resin and the like are preferable.
The epoxy resin is advantageous in that it can be arbitrarily prepared by dissolving in an acid or an oxidizing agent or hardly dissolving in an acid or an oxidizing agent by appropriately selecting the type of the oligomer or the curing agent. . For example, a resin obtained by curing a bisphenol A type epoxy resin with an amine-based curing agent is very soluble in chromic acid, whereas a resin obtained by curing a cresol novolac type epoxy resin with an imidazole curing agent is hardly dissolved in chromic acid.

The adhesive for electroless plating of the present invention may be impregnated into a fibrous substrate such as a glass cloth to form a B-stage state, or may be formed into a film. Further, it may be formed into a substrate shape. In the adhesive for electroless plating of the present invention, the constituent resin may be halogenated to make it flame-retardant, or a dye, a pigment, or an ultraviolet absorber may be added. Further, a fibrous filler or an inorganic filler may be filled to adjust the toughness and the coefficient of thermal expansion.

In the printed wiring board using the adhesive for electroless plating of the present invention, the roughened surface has an anchor depth of Rmax = 1.
５5 μm. This anchor depth is about 1/2 of the anchor depth Rmax = 10 μm of the roughened surface formed by the conventional adhesive, and even if the electroless plating film under the plating resist is dissolved and removed, the plating residue remains. In addition, the amount of palladium catalyst nuclei under the plating resist can be reduced.

In the multilayer printed wiring board of the present invention, a roughened layer is formed on the surface of the conductor circuit formed on the substrate in order to improve the adhesion with the adhesive layer for electroless plating. It is desirable. This roughened layer may be formed on the upper surface of the conductor circuit when the substrate is formed by the full additive method, and may be formed on the side surface or the entire surface of the conductor circuit when the substrate is formed by the subtractive method. desirable. By such a roughened layer, the adhesiveness with the adhesive layer for electroless plating is improved, and cracks caused by a difference in thermal expansion coefficient between the conductor circuit and the adhesive for electroless plating during a heat cycle are suppressed. Can be.

In the case where the roughened layer is formed on the surface of the conductor circuit, when the opening for forming the via hole is formed in the adhesive layer for electroless plating, the roughened layer at the bottom of the opening is developed. Unsatisfactory resin tends to remain. In this regard, the present invention is advantageous because such residual resin can be removed during the roughening treatment of the adhesive layer for electroless plating.

Further, the roughened layer may be formed on the upper surface, the side surface, or the entire surface of the conductor circuit formed on the roughened surface of the adhesive for electroless plating. The reason for this is that cracks that occur during a heat cycle can be suppressed by improving the adhesion to the solder resist that covers the conductor circuit and the upper interlayer resin insulation layer.

Next, a method for manufacturing a printed wiring board according to the present invention will be described by taking a semi-additive method as an example. (1) First, a through hole is drilled in the substrate, and a through hole is formed by applying electroless plating to the wall surface of the through hole and the surface of the copper foil. As the substrate, a resin substrate such as a glass epoxy substrate, a polyimide substrate, a bismaleimide-triazine resin substrate, a fluororesin substrate, or a copper-clad laminate of these resins, a ceramic substrate, a metal substrate, or the like can be used. In particular, when the dielectric constant is considered, it is preferable to use a double-sided copper-clad fluororesin (polytetrafluoroethylene or the like) substrate. This substrate is obtained by thermocompression bonding copper foil having one surface roughened to a fluororesin substrate. Copper plating is preferred as the electroless plating. In the case of a substrate with poor plating coverage, such as a fluororesin substrate, a treatment using a pretreatment liquid (trade name: tetra-etch) composed of an organic acid or the like,
Perform surface modification such as plasma treatment.

(2) Next, electrolytic plating is performed for thickening. Copper plating is preferable as the electrolytic plating. Further, a roughening layer may be provided by roughening the inner wall of the through hole and the surface of the electrolytic plating film. The roughened layer may be formed by a blackening (oxidation) -reduction treatment, by a spray treatment (etching treatment) of a mixed aqueous solution of an organic acid and a cupric complex, or by a copper-nickel-phosphorus needle-like alloy. Some are by plating.

When a roughened layer is formed by electroless plating in these treatments, the copper ion concentration, nickel ion concentration and hypophosphite ion concentration are each 2.2 × 10 4
^{-2 to} 4.1 × 10 ^-2 mol / l, 2.2 × 10 ^{-3 to} 4.1 × 10 ^-3 mol
/ L, an aqueous plating solution having a composition of 0.20 to 0.25 mol / l is desirably used. This is because the crystal structure of the film deposited in this range has a needle-like structure and is excellent in anchor effect. To this aqueous electroless plating solution, a complexing agent or an additive may be added in addition to the above compounds. In addition, 0.01 to 10 g / l
May be added. Examples of the surfactant include Surfynol 440 and 46 manufactured by Nissin Chemical Industry.
It is desirable to use an acetylene-containing polyoxyethylene surfactant such as 5,485. That is, when a roughened layer is formed by electroless plating, copper sulfate 1 to 40 g / l,
Nickel sulfate 0.1-6.0 g / l, citric acid 10-20 g /
l, hypophosphite 10-100 g / l, boric acid 10-40 g /
It is desirable to use an aqueous plating solution having a solution composition of 0.01 to 10 g / l of a surfactant.

When a roughened layer is formed by redox treatment, NaOH (10 g / l), NaClO ₂ (40 g / l), Na ₃ PO
₄ (6 g / l) as an oxidation bath, NaOH (10 g / l), NaBH
₄ (5 g / l) is desirably used as the reducing bath.

When a roughened layer is formed by etching using a mixed aqueous solution of an organic acid and a cupric complex, a CZ8100 solution manufactured by Mec Co., Ltd. is typically used.
The copper surface is made uneven using the oxidizing power of copper.

The roughened layer may be covered with a layer of a metal or a noble metal having an ionization tendency larger than copper and equal to or smaller than titanium. The reason for this is that the metal or noble metal layer covers the roughened layer and prevents local electrode reaction of the conductor circuit when roughening the interlayer insulating layer, thereby preventing the conductor circuit from melting. . The thickness of this layer is preferably 0.01 to 2 μm.

Examples of such metals include titanium, aluminum, zinc, iron, indium, thallium, cobalt,
There is at least one selected from nickel, tin, lead, and bismuth. The noble metals include gold, silver, platinum and palladium. Among them, tin is advantageous because it can form a thin layer by electroless displacement plating and can follow a roughened layer. In the case of tin, a Sn layer having a thickness of about 0.01 to 2 μm is formed by a replacement reaction of Cu—Sn using tin borofluoride-thiourea or tin chloride-thiourea liquid. On the other hand, in the case of a noble metal, a method such as sputtering or vapor deposition is adopted.

(3) Next, a metal particle paste is filled in the through holes. Specifically, the metal particle paste is filled in the through-hole by being applied by a printing method on a substrate on which a mask having an opening formed in the through-hole is placed, and after filling, dried and cured. This metal particle paste is composed of metal particles and a resin, and a solvent may be added as necessary. As metal particles, Cu, Au, Ag, Al,
Ni, Pd, Pt, Ti, Cr, Sn / Pb, etc. can be used. The particle size of the metal particles is preferably 1.0 to 10 μm. The resins used are epoxy resin, phenol resin, polyimide resin, polytetrafluoroethylene (PTF).
E) and other fluororesins, bismaleimide triazine (B
T) Resin, FEP, PFA, PPS, PEN, PES,
Nylon, aramid, PEEK, PEKK, PET and the like can be used. Examples of the solvent include NMP (normal methyl pyrrolidone), DMDG (diethylene glycol dimethyl ether), glycerin, water, 1- or 2- or 3-cyclohexanol, cyclohexanone, methyl cellosolve, methyl cellosolve acetate, methanol, ethanol, butanol, Propanol, bisphenol A type, F type epoxy and the like can be used.

In order to increase the adhesion between the metal particles and the resin, a metal surface modifier such as a silane coupling agent may be added to the metal particle paste. Further, as other additives, an antifoaming agent such as an acrylic antifoaming agent or a silicon-based antifoaming agent, or an inorganic filler such as silica, alumina, or talc may be added.

In particular, the optimum composition of the metal particle paste is a combination of a mixture of a 7: 3 weight ratio of Cu powder and a solventless epoxy and a curing agent, or a 7: 3: 3 weight ratio of a Cu powder.
A combination of flour, PPS and NMP is preferred.

Further, the metal particle paste protruding from the through-hole and the roughened layer on the surface of the electrolytic plating film of the substrate are removed by polishing to flatten the substrate surface. Polishing is
Belt sander and buffing are good. As a result of this polishing, a part of the metal particles is exposed on the surface, and the metal particles in the exposed portion are integrated with the plating film of the conductor layer, thereby exhibiting good adhesion.

(4) After providing a catalyst nucleus on the surface of the substrate planarized in the above (3), electroless plating and electrolytic plating are performed.
Further, an etching resist is formed, and a portion where the resist is not formed is etched to form a conductor layer portion covering the conductor circuit portion and the metal particle paste. As the etchant, an aqueous solution of sulfuric acid-hydrogen peroxide, an aqueous solution of persulfate such as ammonium persulfate, sodium persulfate, or potassium persulfate, or an aqueous solution of ferric chloride or cupric chloride is preferable.

(5) Then, after the etching resist is peeled off to form independent conductor circuits and conductor layers, a roughened layer is formed on the surfaces of the conductor circuits and conductor layers. If a roughened layer is formed on the surface of the conductor layer covering the conductor circuit and the metal particle paste, the conductor has excellent adhesion to the interlayer resin insulation layer. No crack originating from the interface with the insulating layer. On the other hand, the conductor layer covering the metal particle paste has improved adhesion to via holes that are electrically connected. The method of forming the roughened layer is as described above, and includes blackening (oxidation) -reduction treatment, needle-like alloy plating,
Alternatively, there is a method of forming by etching. Further, after the roughening, a resin may be filled between the conductor circuits, and the surface may be polished and smoothed. At this time, as the filling resin,
A composition comprising a bisphenol F type epoxy resin, an imidazole curing agent and inorganic particles is preferred.

(6) An interlayer resin insulation layer is formed on the wiring board thus manufactured. As the interlayer resin insulating layer, the above-described adhesive for electroless plating is employed. Specifically, in the adhesive layer for electroless plating on the side close to the substrate, the compounding amount of the heat-resistant resin particles is 20 to 50% by weight based on the solid content of the heat-resistant resin matrix, while In the adhesive layer for electrolytic plating, it is desirable that the amount of the heat-resistant resin particles is 5% by weight or more and less than 20% by weight based on the solid content of the heat-resistant resin matrix. These two types of adhesives for electroless plating are respectively applied to a substrate using a roll coater or a curtain coater and dried.

(7) The interlayer resin insulation layer is cured to provide an opening for forming a via hole. The curing treatment is performed by thermosetting when the resin matrix of the adhesive for electroless plating is a thermosetting resin, and by exposure to ultraviolet rays or the like when the resin matrix is a photosensitive resin. The opening for forming the via hole is formed by laser light or oxygen plasma when the resin matrix of the adhesive for electroless plating is a thermosetting resin, or by exposure and development when the resin matrix is a photosensitive resin. In particular, in the case of exposure and development processing, a photomask (preferably a glass substrate) on which the above-described circular pattern for forming a via hole is drawn is placed in close contact with the photosensitive interlayer resin insulating layer, and is exposed and developed. To process.

The adhesive layer for electroless plating has a thickness of 45
μm or less, more preferably 20 to 45 μm. The reason is that if it exceeds 45 μm, the diameter of the via hole cannot be reduced, and a via hole of less than 100 μm cannot be obtained. In addition, the thickness of the adhesive layer for electroless plating
When the average particle diameter of the heat-resistant resin particles is set to 45 μm or less and the average particle diameter of the heat-resistant resin particles exceeds 2 μm, the layers are communicated by the roughening treatment. In this regard, since the average particle size of the heat-resistant resin particles used in the present invention is as small as 0.1 to 1.0 μm, such a problem can be solved.

(8) The surface of the interlayer resin insulation layer (adhesive layer for electroless plating) in which the openings are formed in (7) is roughened. In the present invention using an adhesive for electroless plating, resin particles present on the surface of the adhesive are dissolved and removed with an acid or an oxidizing agent, and the surface of the adhesive layer is roughened. The depth of the anchor by this roughening is preferably about 1 to 5 μm. Examples of the acid include phosphoric acid, hydrochloric acid, sulfuric acid, and organic acids such as formic acid and acetic acid, and it is particularly preferable to use an organic acid. This is because when the roughening treatment is performed, the metal conductor layer exposed from the via hole is hardly corroded. As the oxidizing agent, it is desirable to use chromic acid or permanganate (such as potassium permanganate).

(9) A catalyst nucleus is provided on the roughened surface of the interlayer resin insulating layer. It is desirable to use a noble metal ion or a noble metal colloid for providing the catalyst nucleus, and generally, palladium chloride or a palladium colloid is used. In addition,
It is desirable to perform a heat treatment to fix the catalyst core. Palladium is preferred as such a catalyst core.

(10) Next, electroless plating is performed on the roughened surface of the interlayer resin insulating layer, and an electroless plated film is formed on the entire surface. The thickness of the electroless plating film is 0.1 to 5 μm, more preferably 0.2 to 2.0 μm. The electroless plating is preferably an electroless copper plating. As the plating solution, a conventional plating solution can be used. For example, 29 g / l copper sulfate, 25 g / l sodium carbonate, 140 g / l tartrate, 40 g / l sodium hydroxide, 37% formaldehyde 150 ml, A composition having a pH of 11.5 is preferred.

(11) A photosensitive resin film (dry film) is laminated on the electroless plating film formed in (10), and a photomask (glass substrate) on which a plating resist pattern is drawn on the photosensitive resin film. Are placed in close contact with each other, and exposed and developed to form a plating resist pattern.

(12) Electroplating is applied to the portion where the plating resist is not formed to provide a conductor circuit portion and a via hole. Here, it is desirable to use copper plating as the electrolytic plating. The thickness is preferably 10 to 20 μm. It is preferable that an electrolytic plating film is filled in the via hole to form a so-called filled via. This is because the flatness of the interlayer resin insulating layer can be ensured. The via hole may be formed immediately above the through hole provided in the substrate. This is for higher density.

(13) After removing the plating resist, the electroless plating film under the plating resist is removed by using a mixture of sulfuric acid and hydrogen peroxide, sodium persulfate, ammonium persulfate, ferric chloride, cupric chloride, etc. Dissolves and removes with an etching solution of the above to form an independent conductor circuit. Further, the palladium catalyst nuclei on the exposed roughened surface are dissolved and removed with chromic acid or the like.

(14) The above steps can be repeated on this substrate to provide a further upper layer conductive circuit.
Hereinafter, description will be made based on embodiments.

[0050]

[Electroless plating aqueous 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 [Electroless plating conditions] 30 minutes at a liquid temperature of 70 ° C.

Then, electrolytic copper plating was performed under the following conditions to form an electrolytic copper plating film having a thickness of 15 μm (FIG. 1 (c)).
reference). [Electroplating aqueous solution] Sulfuric acid 180 g / l Copper sulfate 80 g / l Additive (manufactured by Atotech Japan, trade name: Capparaside GL) 1 ml / l [Electroplating conditions] Current density 1 A / dm ² hours 30 minutes Temperature Room temperature

(2) A substrate having a conductor (including through holes) formed of an electroless copper plating film and an electrolytic copper plating film formed on the entire surface is washed with water, dried, and then washed with NaOH (10 g / l), NaCl
O ₂ (40 g / l) and Na ₃ PO ₄ (6 g / l) are subjected to an oxidation-reduction treatment using an oxidation bath (blackening bath), NaOH (10 g / l), and NaBH ₄ (6 g / l) as a reduction bath. A roughened layer 4 was provided on the entire surface of the conductor including the through hole 3 (see FIG. 1 (d)).

(3) Next, a metal particle paste 5 containing copper particles having an average particle diameter of 15 μm (manufactured by Tsuta Electric Wire Co., Ltd., DD paste: non-conductive filled copper paste) 5 is filled into the through hole 3 by screen printing. 30 minutes at 100 ℃, 2 at 180 ℃
It was dried and cured under the conditions of time. Then, the metal particle paste 5 protruding from the roughened surface on the upper surface of the conductor and the through hole 3 is removed by belt sanding using # 400 belt abrasive paper (manufactured by Sankyo Rikagaku Co., Ltd.). In order to remove this, the substrate surface was flattened by buffing using alumina granulation or SiC granulation (see FIG. 1 (e)).

(4) An electroless copper plating film having a thickness of 0.6 μm is formed by applying a palladium catalyst (manufactured by Atotech) to the substrate surface flattened in the above (3) and performing electroless copper plating according to a conventional method. 6 was formed (see FIG. 1 (f)).

(5) Next, electrolytic copper plating is performed under the following conditions to form an electrolytic copper plating film 7 having a thickness of 15 μm, a portion to be a conductor circuit 9 is thickened, and a metal filled in the through hole 3 is formed. A portion to be the conductor layer 10 covering the particle paste 5 was formed. [Electroplating aqueous solution] Sulfuric acid 180 g / l Copper sulfate 80 g / l Additive (manufactured by Atotech Japan, trade name: Capparaside GL) 1 ml / l [Electroplating conditions] Current density 1 A / dm ² hours 30 minutes Temperature Room temperature

(6) A commercially available photosensitive dry film is stuck on both sides of the substrate on which the portions to be the conductor circuits 9 and the conductor layers 10 are formed, a mask is placed, and exposure is performed at 100 mJ / cm ² .
The film was developed with 8% sodium carbonate to form an etching resist 8 having a thickness of 15 μm (see FIG. 2A).

(7) Then, the plating film in the portion where the etching resist 8 is not formed is dissolved and removed by etching using a mixed solution of sulfuric acid and hydrogen peroxide, and the etching resist 8 is stripped with 5% KOH. After removal, a conductor layer 10 covering the independent conductor circuit 9 and the metal particle paste 5 was formed (see FIG. 2 (b)). Further, the conductor surface was roughened by an oxidation-reduction treatment.

[Preparation of Resin Filler] 100 parts by weight of bisphenol F type epoxy monomer (manufactured by Yuka Shell, molecular weight: 310, YL983U), S having an average particle size of 1.6 μm and having a surface coated with a silane coupling agent
iO ₂ spherical particles (manufactured by Admatech, CRS 1101-CE, where the maximum particle size is not more than the thickness (15 μm) of the inner layer copper pattern described below) 170 parts by weight, leveling agent (manufactured by San Nopco, Perenol S4) 1.5 The weight of the mixture is kneaded with three rolls and the viscosity of the mixture is 45,000 ~ at 23 ± 1 ° C.
Adjusted to 49,000cps. 6.5 parts by weight of imidazole curing agent (2E4MZ-CN, manufactured by Shikoku Chemicals). These were mixed to prepare a resin filler 12a.

(8) The prepared resin filler 12a is applied to one surface of the substrate using a roll coater to fill the space between the conductor circuits 9 or the conductor layers 10 and dried at 70 ° C. for 20 minutes. Similarly, the other surface was filled with the resin filler 12a between the conductor circuit 9 or the conductor layer 10, and dried by heating at 70 ° C. for 20 minutes.

(9) Replace one side of the substrate after the above processing with #
Belt sanding using 600 belt polishing papers (manufactured by Sankyo Rikagaku Co., Ltd.) so that the resin filler 12a does not remain on the surface of the inner layer copper patterns 9 and 10, and then to remove the scratches caused by the belt sanding. Was buffed. Such a series of polishing was similarly performed on the other surface of the substrate. Then at 100 ° C for 1 hour and at 120 ° C for 3 hours.
Heat treatment was performed for 1 hour at 150 ° C. and for 7 hours at 180 ° C. to cure the resin filler 12a.

(10) Next, on the surface of the conductor layer 10 covering the conductor circuit 9 and the metal particle paste 5, a 2.5 μm-thick roughened layer (irregular layer) 11 made of a Cu—Ni—P alloy is formed. Further, a Sn layer having a thickness of 0.05 μm was formed on the surface of the roughened layer 11 (see FIG. 2C, the Sn layer is not shown). The formation method is as follows. That is, the substrate was acid-degreased and soft-etched, and then treated with a catalyst solution comprising palladium chloride and an organic acid to provide a Pd catalyst. After activating this catalyst, copper sulfate 8 g / l, nickel sulfate 0.6g /
l, citric acid 15 g / l, sodium hypophosphite 29 g /
1, boric acid 31 g / l, surfactant 0.1 g / l, pH = 9
The surface of the copper conductor circuit was formed with a 2.5 μm-thick roughened layer 11 (concavo-convex layer) on the entire surface of the copper conductor circuit. Further, it was immersed in an electroless tin displacement plating bath composed of 0.1 mol / l tin borofluoride-1.0 mol / l thiourea solution at 50 ° C. for 1 hour, and a 0.05 μm thick tin displacement plating layer was formed on the surface of the roughened layer. Was provided.

(11) An adhesive for electroless plating was prepared as follows. [Adhesive on side (lower layer) close to substrate] 35 parts by weight (solid content: 80%) of 25% acrylate of cresol novolak type epoxy resin (manufactured by Nippon Kayaku, molecular weight: 2500), 4 parts by weight of photosensitive monomer (manufactured by Toa Gosei, trade name: Aronix M315), defoaming 0.5 part by weight of an agent (manufactured by San Nopco, trade name: S-65) and 3.6 parts by weight of NMP were mixed with stirring. . 8 parts by weight of polyethersulfone (PES), epoxy resin particles (manufactured by Sanyo Chemicals, trade name: polymer pole)
Was mixed with 14.49 parts by weight of an average particle size of 0.5 μm, and then 20 parts by weight of NMP was further added thereto, followed by stirring and mixing. . Imidazole curing agent (Shikoku Chemicals, trade name: 2E4MZ-
2 parts by weight of CN), 2 parts by weight of photoinitiator (manufactured by Ciba Geigy, trade name: Irgacure I-907), 0.2 parts by weight of photosensitizer (manufactured by Nippon Kayaku, trade name: DETX-S), 1.5 parts by weight of NMP Was mixed with stirring. These were mixed to obtain an adhesive for electroless plating.

[Adhesive on Opposite Side (Upper Layer) of Substrate] 35 parts by weight (solid content: 80%) of 25% acrylate of cresol novolak type epoxy resin (manufactured by Nippon Kayaku, molecular weight: 2500), 4 parts by weight of photosensitive monomer (manufactured by Toa Gosei, trade name: Aronix M315), defoaming 0.5 part by weight of an agent (manufactured by San Nopco, trade name: S-65) and 3.6 parts by weight of NMP were mixed with stirring. . 8 parts by weight of polyethersulfone (PES), epoxy resin particles (manufactured by Sanyo Chemicals, trade name: polymer pole)
Was mixed with 7.245 parts by weight of a powder having an average particle size of 0.5 μm, and then 20 parts by weight of NMP was further added and mixed with stirring. . Imidazole curing agent (Shikoku Chemicals, trade name: 2E4MZ-
2 parts by weight of CN), 2 parts by weight of photoinitiator (manufactured by Ciba-Geigy, trade name: Irgacure I-907), 0.2 parts by weight of photosensitizer (manufactured by Nippon Kayaku, trade name: DETX-S), 1.5 parts by weight of NMP Parts were stirred and mixed. These were mixed to obtain an adhesive for electroless plating.

(12) The photosensitive adhesive solution prepared in the above (11) was sequentially applied to both sides of the substrate by using a roll coater, left in a horizontal state for 20 minutes, and then left at 60 ° C. for 30 minutes. Was dried to form an adhesive layer 12b (two-layer structure) having a thickness of 60 μm (see FIG. 2 (d)). Further, a polyethylene terephthalate film was stuck on the adhesive layer 12b via an adhesive.

(13) A 5 mm-thick soda lime glass substrate on which a circular pattern (mask pattern) having the same shape as the via hole is drawn on both sides of the substrate on which the adhesive layer 12b is formed, with a light-shielding ink having a thickness of 5 μm. The side on which the circular pattern was drawn was placed in close contact with the adhesive layer 12b, and was exposed to ultraviolet light.

(14) The exposed substrate was spray-developed with a DMTG (triethylene glycol dimethyl ether) solution to form an opening serving as a 80 μmφ via hole in the adhesive layer 12b. Further, the substrate is exposed at 3000 mJ / cm ² using an ultra-high pressure mercury lamp, and is exposed at 100 ° C. for 1 hour.
By performing the heat treatment at 150 ° C. for 5 hours, an adhesive layer 12 having a thickness of 35 μm having openings (opening 13 for forming via holes) having excellent dimensional accuracy corresponding to a photomask film.
b was formed (see FIG. 2 (e)). Note that the roughened layer is partially exposed in the opening serving as the via hole.

(15) The substrate on which the via hole forming openings 13 are formed is immersed in chromic acid for 10 minutes to dissolve and remove the epoxy resin particles present on the surface of the adhesive layer, thereby removing the surface of the adhesive layer. Roughened, then neutralized solution (Shipley)
And then washed with water.

(16) A palladium catalyst (manufactured by Atotech) is applied to the substrate that has been subjected to the surface roughening treatment (roughening depth: 5 μm), so that the surface of the adhesive layer 12 b and the surface of the via hole opening 13 are formed. A catalyst core was provided.

(17) The substrate was immersed in an aqueous electroless copper plating solution having the following composition to form an electroless copper plating film 14 having a thickness of 0.6 μm on the entire rough surface (see FIG. 3A). . [Electroless plating aqueous 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 [Electroless plating conditions] 70 ° C. 30 minutes at liquid temperature

(18) A commercially available photosensitive resin film (dry film) is thermocompression-bonded to the electroless copper plating film 14 and the thickness of the chromium layer in which the plating resist non-formed portion is drawn as a mask pattern A 5 mm soda lime glass substrate is contacted with the photosensitive resin film on the side on which the chromium layer is formed, and exposed at 110 mJ / cm ² , 0.8%
After developing with sodium carbonate, a pattern of a plating resist 16 having a thickness of 15 μm with L / S = 25/25 μm was provided (FIG. 3).
(b)).

(19) Then, electrolytic copper plating was performed under the following conditions to form an electrolytic copper plating film 15 having a thickness of 15 μm (FIG. 3).
(c)). [Electroplating aqueous solution] Sulfuric acid 180 g / l Copper sulfate 80 g / l Additive (manufactured by Atotech Japan, trade name: Capparaside GL) 1 ml / l [Electroplating conditions] Current density 1.2 A / dm ² hours 30 minutes Temperature Room temperature

(20) After the plating resist 16 is removed by spraying 5% KOH, the electroless plating film 14 under the plating resist 16 is dissolved and removed by etching with a mixed solution of sulfuric acid and hydrogen peroxide. Then, an inner conductor circuit 9 (including via holes 17) having an L / S of 25/25 μm and a thickness of 18 μm comprising the electroless copper plating film 14 and the electrolytic copper plating film 15 was formed (see FIG. 3D). Further, Pd remaining on the roughened surface was immersed in chromic acid (800 g / l) for 1 to 10 minutes and removed.

(21) In the above (20), the conductor circuit 9 (via hole)
17 g), copper sulfate 8 g / l, nickel sulfate 0.6 g / l, citric acid 15 g / l, sodium hypophosphite 29 g / l, boric acid 31 g / l, surfactant 0.1 g /
1 was immersed in an electroless plating solution having a pH of 9 to form a roughened layer 11 made of copper-nickel-phosphorus having a thickness of 3 μm on the surface of the conductor circuit. At this time, the roughened layer 11 is
(Fluorescence X-ray analysis) showed that 98 mol% of Cu,
The composition ratio was 1.5 mol% and P 0.5 mol%. Further, the substrate is washed with water, immersed in an electroless tin displacement plating bath composed of 0.1 mol / l tin borofluoride-1.0 mol / l thiourea solution at 50 ° C. for 1 hour, and the surface of the roughened layer 11 is Thickness 0.
A tin-substituted plating layer of 05 μm was formed (however, the tin-substituted plating layer is not shown).

(22) By repeating the above steps (11) to (21), an upper interlayer resin insulating layer 12b and a conductor circuit 9 (including via holes 17) are further provided to obtain a multilayer wiring board. (See FIG. 4 (a)). Here, the roughened layer 11 made of copper-nickel-phosphorus is provided on the surface of the conductor circuit, but the tin-substituted plating layer is not formed on the roughened layer surface.

(23) On the other hand, 60% by weight dissolved in DMDG
Cresol novolak epoxy resin (Nippon Kayaku)
14.6% bisphenol A type epoxy resin (manufactured by Yuka Shell Co., trade name: Epikote 1001) in which 46.67 parts by weight of a photosensitizing oligomer (molecular weight 4000) obtained by acrylate of 50% of epoxy groups of the above is dissolved in methyl ethyl ketone 15.0 Parts by weight, imidazole curing agent (Shikoku Chemicals, trade name: 2E4M
1.6 parts by weight of Z-CN), 3 parts by weight of a photosensitive acrylic monomer (manufactured by Nippon Kayaku, trade name: R604), and also a polyvalent acrylic monomer (manufactured by Kyoeisha Chemical, trade name: DP)
E6A) 1.5 parts by weight, 0.71 part by weight of a dispersion antifoaming agent (manufactured by San Nopco, trade name: S-65), and 2 parts by weight of benzophenone (manufactured by Kanto Kagaku) as a photoinitiator based on the mixture. Parts, 0.2 parts by weight of Michler's ketone (manufactured by Kanto Chemical Co., Ltd.) as a photosensitizer, and added a viscosity of 2.0 Pa ·
s was obtained. The viscosity was measured at 60 rpm using a B-type viscometer (Tokyo Keiki, DVL-B type).
In the case of No. 4, the rotor No. 4 was used, and in the case of 6 rpm, the rotor No. 3 was used.

(24) The solder resist composition was applied to both sides of the multilayer wiring board obtained in the above (22) in a thickness of 20 μm. Next, after performing a drying process at 70 ° C. for 20 minutes and a temperature of 70 ° C. for 30 minutes, a thickness 5 on which a circular pattern (mask pattern) of the solder resist opening is drawn by the chromium layer
A soda lime glass substrate having a thickness of ² mm was exposed to ultraviolet light of 1000 mJ / cm ² with the side on which the chromium layer was formed in close contact with the solder resist layer, and subjected to DMTG development treatment. In addition, at 80 ° C
Heat treatment at 100 ° C. for 1 hour, 120 ° C. for 1 hour, and 150 ° C. for 3 hours. The solder resist pattern layer 18 (opening diameter: 200 μm) with openings on the upper surface of the solder pads, via holes and lands (opening diameter: 200 μm) (Thickness: 20 μm).

(25) Next, the solder resist pattern layer 18
The substrate on which was formed was immersed in an electroless nickel plating solution having a pH of 5 consisting of 30 g / l of nickel chloride, 10 g / l of sodium hypophosphite, and 10 g / l of sodium citrate for 20 minutes, and the thickness of the opening was measured. A nickel plating layer 19 of 5 μm was formed. Further, the substrate was treated with 2 g of potassium potassium cyanide /
l, ammonium chloride 75 g / l, sodium citrate 50
A gold plating layer 20 having a thickness of 0.03 μm was formed on the nickel plating layer 19 by immersion in an electroless gold plating solution consisting of g / l and sodium hypophosphite 10 g / l at 93 ° C. for 23 seconds.

(26) Solder resist pattern layer
Solder paste (printed solder paste) was printed in the opening 18 and reflowed at 200 ° C. to form a solder bump (solder body) 21 to manufacture a multilayer printed wiring board having the solder bump 21 (see FIG. 4B). .

(Comparative Example 1) The adhesive layer for electroless plating was 1
A multilayer printed wiring board having solder bumps was manufactured in the same manner as in Example 1, except that the layers were all prepared under the conditions of the upper layer side.

(Comparative Example 2) The adhesive layer for electroless plating was 1
A multilayer printed wiring board having solder bumps was manufactured in the same manner as in Example 1, except that the layers were all prepared under the lower layer conditions.

The multilayer printed wiring board thus manufactured was evaluated as described below. Table 1 shows the results.
Shown in (Evaluation) A wiring pattern of L / S = 25/25 μm was formed, and the presence or absence of disconnection was examined. (Evaluation) The presence or absence of resin residue at the bottom of the via hole after the roughening treatment was observed with an electron microscope.

[0082]

[Table 1]

[0083]

As described above, according to the present invention, fine via holes and fine patterns can be formed.
Moreover, it is possible to provide a multilayer printed wiring board having excellent reliability without developing residue at the bottom of the via hole.

[Brief description of the drawings]

1 (a) to 1 (f) are views showing a part of a process for manufacturing a multilayer printed wiring board of the present invention.

2 (a) to 2 (e) are views showing a part of a process for manufacturing a multilayer printed wiring board according to the present invention.

FIGS. 3 (a) to 3 (d) are views showing a part of a process of manufacturing a multilayer printed wiring board according to the present invention.

FIGS. 4A and 4B are diagrams illustrating a part of a process of manufacturing a multilayer printed wiring board according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Substrate 2 Copper foil 3 Through hole 4,11 Roughened layer 5 Metal particle paste 6,14 Electroless plating film 7,15 Electrolytic plating film 8 Etching resist 9 Conductor circuit 10 Conductive layer 12a Resin filler 12b Interlayer resin insulating layer 13 Via hole opening 16 Plating resist 17 Via hole 18 Solder resist layer 19 Nickel plating layer 20 Gold plating layer 21 Solder bump (solder)

────────────────────────────────────────────────── ─── Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI H05K 3/18 H05K 3/18 K 3/38 3/38 A (56) References JP-A-9-266375 (JP, A) (58) Field surveyed (Int. Cl. ⁷ , DB name) H05K 3/46 C09J 163/00 C23C 18/20 H05K 3/18 H05K 3/38

Claims (5)

(57) [Claims] 1. A heat-resistant resin matrix hardly soluble in an acid or an oxidant is dispersed in a heat-resistant resin matrix hardened in an acid or an oxidant on a substrate on which a conductive circuit is formed. The adhesive layer for electroless plating is formed, and the surface of the adhesive layer for electroless plating has a roughened surface formed by dissolving and removing the heat-resistant resin particles, and an upper layer is formed on the roughened surface. In the multilayer printed wiring board on which the conductive circuit on the side is formed, the adhesive layer for electroless plating is composed of two layers,
Amount of heat-resistant resin particles in adhesive layer for electroless plating
Is 20 to 5 with respect to the solid content of the heat-resistant resin matrix.
0% by weight, and the resistance of the other electroless plating adhesive layer
The amount of the heat-resistant resin particles depends on the solidity of the heat-resistant resin matrix.
A multilayer printed wiring board characterized in that the content is 5% by weight or more and less than 20% by weight based on the shape component. 2. The heat-resistant resin particles have an average particle size.
The multilayer printed wiring board according to claim 1, wherein the thickness is 0.1 to 1.0 m. 3. The heat-resistant resin matrix of the adhesive for electroless plating comprises a composite of an epoxy resin and PES, and the amount of PES in the composite is 30% by weight based on the solid content of the heat-resistant resin matrix. %. The multilayer printed wiring board according to claim 1, wherein the amount is less than 0.1%. 4. The multilayer printed wiring board according to claim 1, wherein said conductive circuit is formed of an electroless plating film and an electrolytic plating film. 5. The multilayer printed wiring board according to claim 1, wherein a roughened layer is formed on at least a part of the surface of the conductive circuit on the substrate.