JPH088534A - Manufacture of multilayer printed wiring board - Google Patents

Abstract

PURPOSE:To enable a multilayer printed wiring board to be enhanced in density and lessened in cost by a method wherein thermosetting additive bonding agent film is laminated on a photosetting resin surface and cured by heating. CONSTITUTION:Photosetting resin 4 is applied onto both sides or one side of an inner layer circuit board whose surface is roughened, exposed to light, and developed for the formation of a surface viahole 5. Then, a cured photosetting resin layer is polished and turned smooth. In succession, a thermosetting additive bonding agent film 6 is roll-laminated thereon at, normal pressures and cured by heating. At this point, as a space is present inside a previously formed viahole, air is expanded in a thermal treatment, whereby the additive bonding agent, film 6 is lifted and heaved up to burst out. The surface of the bonding agent layer is mechanical polished and turned smooth, and the heaved part of the film 6 is removed concurrently to make a viahole 8 disclosed again. Lastly, the cured surface of the additive bonding agent layer is finely roughened by chemicals, then a plating resist 9 is applied thereon, and the inner circuit board is subjected to electroless plating.

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 multilayer printed wiring board using a liquid photocurable resin and a thermosetting additive adhesive film.

[0002]

2. Description of the Related Art In recent years, high-precision personal computers and mobile phones have become widespread, and have been advanced in functionality and size. with this,
The multilayer printed wiring boards used are required to have finer circuit patterns and smaller surface via holes in order to achieve higher density, smaller size, and lighter weight, and at the same time, it is necessary to reduce costs. Has been.

As a conventional method for manufacturing a multilayer printed wiring board, a circuit is formed on a double-sided copper-clad board by etching, the surface of the circuit is roughened, and a glass cloth base material is impregnated with an epoxy resin. This was a step of stacking one or more cured prepreg sheets, further laminating a copper foil or a single-sided copper clad plate thereon, and heating and integrating them with a heating press. In this method, there is a limit to the fineness of the pattern,
In the conventional subtractive method for removing unnecessary portions of a copper foil circuit by etching, it is necessary to develop an etching dry film, etch the copper foil, and perform imaging twice. It is difficult to mass-produce a fine line of 50 μm or less by side etching.

Further, when the surface via hole is machined by a mechanical drill, the hole machining of a diameter of about 300 μm is the limit, and if it is less than that, problems such as hole position accuracy and drill life will occur. When processed with an excimer laser or carbon dioxide laser, it is possible to make holes of about 50 μm, but only when there is no glass cloth in the insulating layer. Will increase. Further, in the conventional process, the glass cloth base material must be impregnated with epoxy resin and semi-cured once in order to make a prepreg sheet, and since heat and pressure molding is performed by a press, a huge amount of equipment and a long time are required. Was needed.

[0005]

According to the conventional method of forming a prepreg by impregnating a glass cloth base material with an epoxy resin, heating and pressurizing by a press, and forming a surface via hole by a mechanical drill. Since the glass cloth is used, there is a problem that it is expensive and that it cannot be made extremely thin, and that a pattern is created by the subtractive method and a surface via hole is formed by a mechanical drill, so that it cannot be made fine.

The present invention has been made as a result of various studies in order to solve these problems. The object of the present invention is to provide a multilayer print which achieves ultra-thinness, fineness, high density and at the same time low cost. It is to provide a method for manufacturing a wiring board.

[0007]

The present invention provides a method for producing a multilayer printed wiring board comprising the following steps: (1) On both sides or one side of a surface-roughened inner layer circuit board,
A step of applying a photocurable resin and forming a surface via hole by exposure and development, (2) smoothing and polishing the surface of the resin,
A step of laminating a thermosetting additive adhesive film thereon under normal pressure and heating and curing, (3) polishing the adhesive resin portion raised on the surface via hole and the other adhesive resin portion together, and polishing. The present invention relates to a step of surface smoothing and forming a surface via hole again, (4) a step of chemically finely roughening the surface of an additive adhesive and electroless plating, and a method for manufacturing a multilayer printed wiring board comprising the following steps. (A) A step of etching a double-sided copper clad board to form an inner layer circuit, (B) a step of roughening the inner layer circuit surface, (C) applying a liquid photocurable resin to both sides or one side of the inner layer circuit board Then, a step of forming a surface via hole by exposure and development, a step of (D) smoothing and polishing the cured resin surface, laminating a thermosetting additive adhesive film thereon under atmospheric pressure, and heat curing. (E) A step of polishing the adhesive resin portion on the surface via hole and the adhesive resin portion other than the raised portion together to smooth the surface and form the surface via hole again, (F) the additive adhesive surface is chemically Step of electroless plating after finely roughening and applying plating resist,

The present invention will be described below in detail with reference to the drawings. First, as in the conventional method, the surface of the circuit copper foil (2) of the patterned inner layer circuit board (1) is treated with a chemical to roughen (A, B). (3) represents the roughened inner layer circuit surface. In this case, an inner layer circuit board using a copper foil that has been roughened in advance may be used. Next, a photocurable resin (4) as an undercoat material is applied to the surface by screen printing, a curtain coater, a roller coater or the like. Subsequently, the negative film is brought into close contact with the film by heat-drying by heat treatment, or the negative film is placed by non-contact without touch-drying, irradiated with ultraviolet rays, and then developed with an organic solvent or an alkaline aqueous solution, A photo via hole (5) is formed (C).

Next, the cured photocurable resin layer is mechanically polished to smooth the surface. The purpose is to prevent unnecessary voids from being left between the thermosetting additive adhesive film to be laminated next, and at the same time to improve the adhesiveness between the two resins. Subsequently, the thermosetting additive adhesive film (6) is roll-laminated under normal pressure and heat-treated to cure. At this time, since there is a space in the via hole formed in advance, the air is expanded by the heat treatment, and as a result, the film is lifted to the upper part and raised and burst (D). (7) shows the film on the raised and destroyed via hole.

The surface of the adhesive layer is mechanically polished to smooth the surface and simultaneously remove the raised portion, and the surface via hole (8) is again exposed. Finally, after finely roughening the surface of the additive adhesive that has been cured by a chemical, a plating resist (9) is applied and electroless plating is performed (F).
(10) shows a plated circuit.

The photocurable resin used as an undercoating agent in the present invention has excellent resistance to plating solutions and can be developed with an aqueous alkaline solution or an organic solvent. For example, it contains novolac type epoxy acrylate or urethane acrylate as a main component. If necessary, a thermosetting resin such as a bisphenol A type epoxy resin, a bisphenol F type epoxy resin, or a novolac type epoxy resin is mixed with an epoxy curing agent. In addition, a photoinitiator, an inorganic filler, an antifoaming agent, a leveling agent, a coupling agent, etc. may be added as necessary. Japanese Patent Application 6-4
A composition which is capable of being developed with an alkaline aqueous solution and which is excellent in solvent resistance and plating solution resistance is particularly preferable, as described in No. 0842.

Next, the types of the heat-curing additive adhesives can be mentioned, for example, Japanese Patent Publication No. 63-10752.
JP-A-63-297571, JP-A-64
As disclosed in JP-A-47095 and JP-A-3-18096, those in which the adhesive layer is roughened with an oxidizing agent are included, and the content thereof includes a rubber component such as acrylonitrile butadiene rubber and chromium-sulfuric acid as an oxidizing agent. The rubber component is eluted with an aqueous solution to roughen the adhesive surface.

Further, an inorganic fine powder such as silica or calcium carbonate is dispersed as an adhesive in a resin matrix having excellent heat resistance such as an epoxy resin, a phenol resin or a melamine resin, and the inorganic fine powder is used as a specific chemical. As described in JP-A-1-29479 and a method for roughening the adhesive layer by selectively eluting the cured epoxy with a cured epoxy having different solubilities with respect to an oxidizing agent in an epoxy resin matrix. There is a method in which resin fine powder is dispersed and the epoxy resin fine powder is selectively eluted with an oxidizing agent.

As the thermosetting type additive adhesive film used in the present invention, a film obtained by filmizing any one of the above can be used, but like a chromium-sulfuric acid aqueous solution, which has great problems in working environment and safety and hygiene. It is possible to roughen with permanganate without using a strong oxidizing agent, and at the same time, it is easy to form a film.
The thermosetting additive adhesive described in 04291 is particularly preferable.

[0015]

In the present invention, since the liquid photo-curable resin and the thermosetting additive adhesive film are used to form a multilayer structure, no glass cloth is used and no pressing is performed. It is low cost in terms of man-hours, and by combining a developable photocurable resin undercoating agent and a thermosetting additive adhesive film, it becomes possible to form surface via holes and additive plating, and to form fine patterns. become able to.

[0016]

EXAMPLES The present invention will be described below with reference to examples. 540g (4 equivalents of isocyanate) of organic polyisocyanate (Sumitomo Bayer Urethane: Sumidule 44V10) was put into a 2L flask, and triethylamine 1 was added.
g was added and warmed to 60 ° C. Acrylic acid into it
After 232 g (2 mol) of 2-hydroxyethyl was added dropwise over 30 minutes, the mixture was stirred and reacted at 60 ° C. for 3 hours to synthesize an isocyanate group-containing urethane acrylate.

Next, after adding 760 g (4 equivalents) of bisphenol A type epoxy resin (made by Yuka Shell Epoxy: Epicoat 828) and 1 g of methoxyphenol as a polymerization inhibitor into a 2 l flask, 288 g of acrylic acid (4 g
Mol), 1 g of benzyldimethylamine was added, and the temperature was 100 ° C.
The reaction was stirred for 6 hours. Then 160g of succinic anhydride
(1.6 mol) was added, and the mixture was reacted with stirring at 80 ° C. for 3 hours,
A carboxyl group-containing epoxy acrylate was synthesized.
25 g of this isocyanate group-containing urethane acrylate
And carboxyl group-containing epoxy acrylate 50g
And 12 g of glycidyl methacrylate were mixed, and 4.5 g of 1-hydroxycyclohexyl phenyl ketone (manufactured by Ciba-Geigy: Irgacure 184) was added as a photoinitiator to obtain a liquid photocurable resin.

Next, bisphenol F type epoxy resin (manufactured by Dainippon Ink Co., Ltd .: Epicron 830, epoxy equivalent 1
75) 100 parts by weight of bisphenol A type epoxy resin (epoxy equivalent 6400, weight average molecular weight 30,000)
50 parts by weight were dissolved in 200 parts by weight of methyl ethyl ketone with stirring. To this solution, 15 parts by weight of microencapsulated imidazole and 3 parts by weight of a silane coupling agent (manufactured by Nippon Unicar: A-187) were added as a curing agent to prepare a thermosetting additive adhesive varnish. 100 μm thickness with one-side release treatment as carrier film
The above polyethylene terephthalate film was used, and the above adhesive varnish was applied to this with a roller coater so that the thickness after drying was 30 μm, and dried to obtain a thermosetting additive adhesive film.

A glass epoxy double-sided copper clad laminate having a substrate thickness of 0.1 mm and a copper foil thickness of 35 μm was patterned to form an inner layer circuit board. Then, sodium chlorite 31g / l,
Sodium hydroxide 15g / l, sodium phosphate 12g
/ L in an alkaline aqueous solution at 95 ° C for 2 minutes to roughen the circuit surface, and the liquid photocurable resin prepared above is applied thereon by a curtain coater to a thickness of 70 µm and heat-treated at 80 ° C for 10 minutes to dry by touch. went. Subsequently, a predetermined pattern is placed, and a high-pressure mercury lamp exposure device is used to irradiate 30
Exposed with 0 mJ / cm ^2, then developed at a spray pressure of 2Kg / cm ² by aqueous sodium carbonate solution, to form a surface via hole.

The surface of the cured photocurable resin is smoothed by polishing with a belt sander, the thermosetting additive adhesive film is laminated thereon under normal pressure, and the carrier film is peeled off at 180 ° C. and 20 ° C. After heat-curing for a minute, the resulting multilayer printed wiring board substrate was perforated for plating through holes. After that, the adhesive adhesive raised portion on the surface via hole generated during heat curing and the other adhesive resin portion were combined and polished with a belt sander to make the surface smooth and to make the surface via hole appear again.

Then, 10 times in an alkaline aqueous solution at 80.degree.
After soaking for a minute, after degreasing and swelling the adhesive layer,
10 with an aqueous alkaline solution of potassium permanganate at 70 ° C
After roughening for a minute and washing thoroughly with water, it was immersed in a hydroxylamine sulfate aqueous solution at 50 ° C. for 10 minutes to neutralize and remove the permanganate remaining in the adhesive layer. Next, after being immersed in an alkaline degreasing solution at 75 ° C. for 5 minutes, it was thoroughly washed and immersed in a palladium-tin salt colloid catalyst solution for 5 minutes. After washing with water, the catalyst was immersed in a catalyst activation bath at room temperature for 8 minutes to remove excess tin salt from excess palladium-tin salt colloidal particles.
Subsequently, a desired plating circuit and a plating resist for forming a through hole were formed by a known method.

Then, the electroless copper plating solution at 70 ° C. was used for 10 times.
Immerse for 20 hours, and apply about 20μ to the entire surface of the substrate for multilayer printed wiring board
m electroless plating film was formed to produce an additive method multilayer printed wiring board.

[0023]

According to the method of the present invention, since no glass cloth is used and no pressing is performed when forming a multi-layer structure, it is possible to manufacture a multi-layer printed wiring board at low cost, and moreover, a surface via hole is formed. It is suitable for manufacturing a multilayer printed wiring board having a high-density fine pattern by forming a circuit by additive plating.

[Brief description of drawings]

FIG. 1 is a schematic cross-sectional view of steps showing a method for manufacturing a multilayer printed wiring board according to the present invention: 1 inner layer circuit board 2 circuit copper foil 3 roughened circuit surface 4 photocurable resin layer 5 surface photovia hole 6 thermosetting type Additive adhesive film 7 Raised and destroyed film 8 Surface via hole 9 Plating resist 10 Plating circuit

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical indication H05K 3/28 F

Claims (2)

[Claims] 1. A method for manufacturing a multilayer printed wiring board comprising the following steps. (1) On both sides or one side of the surface-roughened inner layer circuit board,
A step of applying a photocurable resin and forming a surface via hole by exposure and development, (2) smoothing and polishing the surface of the resin,
A step of laminating a thermosetting additive adhesive film thereon under normal pressure and heating and curing, (3) polishing the adhesive resin portion raised on the surface via hole and the other adhesive resin portion together, and polishing. A step of smoothing the surface and forming a surface via hole again, (4) a step of chemically roughening the surface of the additive adhesive and performing electroless plating, 2. A method for manufacturing a multilayer printed wiring board, which comprises the following steps. (A) A step of etching a double-sided copper clad board to form an inner layer circuit, (B) a step of roughening the inner layer circuit surface, (C) applying a liquid photocurable resin to both sides or one side of the inner layer circuit board Then, the step of forming a surface via hole by exposure and development,
(D) A step of smoothing and polishing the surface of the cured resin, laminating a thermosetting additive adhesive film thereon under normal pressure, and heat curing, (E) a raised adhesive resin portion on the surface via hole And a step of polishing the other resin portion of the adhesive together to smooth the surface and form a surface via hole again, (F) after chemically roughening the surface of the additive adhesive and applying a plating resist, electroless Plating process,