JPH11177237A - Build-up multilayer printed wiring board and manufacture thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a build-up multilayer printed wiring board which is superior in thickness reduction, connection reliability enhancement, and substrate surface evenness, and a method of manufacturing the build-up multilayer printed wiring board with superior productivity SOLUTION: A wiring board comprises an inner layer circuit board 4. in which inner layer circuits 2 on its both side surfaces are connected mutually via a through hole 3, and on its each side surface, a thermosetting resin layer 6 in which electrically insulating filler is dispersed homogeneously, a first circuit 7 formed on the thermosetting resin layer 6, a first via hole 8 which connects the inner layer circuit 2 and the first circuit 7 electrically, a photosensitive resin layer 9 covering the surface of the above mentioned members, a second circuit 10 formed on the photosensitive resin layer 9, and a second via hole 11 which connects the first circuit 7 and the second circuit 10 electrically. The through hole 3 of the inner circuit board 4 is filled with an insulating resin in which the same electrically insulating filler used in the thermosetting resin layer 6 is dispersed homogeneously.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a build-up multilayer printed wiring board and a method for manufacturing the same.

[0002]

2. Description of the Related Art In recent years, the miniaturization, weight reduction, and multi-functionality of electronic devices have been further advanced, and with this, high integration of LSIs and chip components has progressed, and the form has also been increased to multi-pin and miniaturized. And it is changing rapidly. For this reason, a multilayer printed wiring board has been required to further increase the wiring pattern density in order to increase the mounting density of electronic components.

In order to satisfy these demands, thinning between layers, miniaturization of wiring, and reduction in the diameter of interlayer connection holes have been performed, and interstitial via holes (hereinafter, referred to as "connections") that connect only conductors between adjacent layers. IVH) and buried via holes (hereinafter referred to as BVH) have been used, and the diameters of the IVH and BVH have been further reduced.

[0004] In order to form a multilayer wiring, a plurality of circuit layers and an interlayer insulating layer therebetween are collectively stacked, laminated by heat and pressure, integrated, and formed with holes at required locations.
There is a build-up multilayer wiring board in which an interlayer insulating layer is formed on a circuit, a circuit is formed thereon, holes are provided in necessary places, and a circuit layer and an insulating layer are sequentially formed. .

As an example of this build-up multilayer wiring board, a thermosetting resin is filled in a through hole of an inner circuit board having a plated through hole and an inner layer circuit formed thereon by a silk screen printing method or the like. After filling and heating and curing, the resin that protrudes from the hole is removed by polishing or the like, a thermosetting resin is applied, and heat curing is performed to form an insulating layer, and a part of the insulating layer is selectively formed. By removing, a hole for interlayer connection is provided, the inner wall of the hole for interlayer connection is metallized by plating or the like, a circuit conductor is formed on the insulating resin, and a circuit is further formed. If this circuit is formed as an inner circuit board, one more insulating layer and circuit layer can be formed by the same operation as above.
By repeating this, a required multilayer circuit can be formed.

[0006]

Such a build-up multilayer wiring board is formed with an electrically insulating resin or conductive resin before forming a build-up layer on an inner circuit board having through holes. It is necessary to fill the hole.
Curtain coating, screen printing, dipping, and film laminating methods are known as methods of forming the insulating resin of the build-up layer. Must be removed by mechanical polishing, and the mechanical polishing causes a dimensional change of the inner layer circuit board, which causes a positional shift and lowers the yield.

Further, even when the insulating resin can be filled in the through-hole, the reliability of the connection is reduced because the thermal expansion coefficients of the inner circuit board and the filled resin are different.

The present invention provides a build-up multilayer printed wiring board excellent in thinning, improvement of connection reliability, and smoothing of a substrate surface, and a method of manufacturing a build-up multilayer printed wiring board excellent in productivity. The purpose is to:

[0009]

As shown in FIG. 1 (g), a build-up multilayer printed wiring board according to the present invention comprises an insulating substrate 1, an inner layer circuit 2 formed on both sides thereof, and a through hole 3. An inner circuit board 4 electrically connecting the inner circuits 2 on both sides, a thermosetting resin layer 6 having an electrically insulating filler uniformly dispersed on its surface, and a thermosetting resin layer 6
Circuit 7, a first via hole 8 for electrically connecting the inner circuit 2 and the first circuit 7, and a photosensitive resin layer 9 formed on the surface. And a second circuit 10 formed on the surface of the photosensitive resin layer 9.
And a second via hole 11 for electrically connecting the first circuit 7 and the second circuit 10, and the through hole 3 of the inner circuit board 4 is connected to the thermosetting resin layer 6. It is characterized by being filled with the same insulating resin.

Such a build-up multilayer printed wiring board can be manufactured by performing the following steps in this order. a. A thermosetting resin varnish is blended with an electrically insulating ceramic whisker, which is an electrically insulating filler, and the electrically insulating ceramic whisker is uniformly dispersed in the thermosetting resin varnish by stirring. It is applied to the roughened surface of the foil 21, heated and semi-cured to form a thermosetting resin layer 6,
The thermosetting resin layer 6 is overlaid on an insulating substrate 1 and an inner layer circuit board 4 formed on both sides thereof and an inner layer circuit board 4 electrically connected to the inner layer circuits 2 on both sides thereof by through holes 3. A process of heating and pressurizing to laminate and integrate. b. Forming an etching resist on the copper foil 21;
Removing the portion exposed from the etching resist by etching into the shape of the first via hole 8 to remove the etching resist. c. The inner layer circuit 2 is exposed by irradiating the cured thermosetting resin layer 6 exposed from the fine holes of the copper foil 21 etched and removed in the shape of the first via holes 8 with laser light. Forming a hole 82 to be the first via hole 8. d. The cured thermosetting resin layer 6 on the wall surface of the hole 82 is
A step of roughening and plating with a roughening agent. e. Forming an etching resist on the plating, etching away the plating and the copper foil 21 exposed from the etching resist, forming a first circuit 7, and then removing the etching resist. f. A step of oxidizing the surface of the first circuit 7 to form irregularities and reducing the formed copper oxide; g. A liquid photosensitive resin is applied to the surface on which the first circuit 7 is formed, a photosensitive resin layer 9 is formed, exposed and developed through a photomask, and a hole 1 serving as a second via hole 11 is formed.
Step 11 of forming. h. A step of roughening the resin surface of the photosensitive resin layer 9 including the wall surface of the hole 111 with an oxidizing roughening solution and performing plating. i. Forming an etching resist on the surface of the plating,
A step of selectively etching away the plating exposed from the etching resist to remove the etching resist.

Step a. Alternatively, the following steps can be used. a1. A thermosetting resin varnish obtained by uniformly dispersing the electrically insulating ceramic whisker in the thermosetting resin varnish by agitation, having a roughness suitable for bonding with a resin and a copper layer serving as a circuit as a whole. Two layers consisting of a carrier layer having sufficient strength for handling as a metal layer of the above are applied to the roughened surface of the copper layer of the composite metal foil which can be easily peeled, and semi-cured by heating to form a thermosetting resin layer 6 Then, a step of superposing the thermosetting resin layer 6 on the inner layer circuit board 4 on which the through-holes 3 and the inner layer circuit 2 are formed in advance, laminating and unifying the layers by heating and pressing, and then removing only the carrier layer.

Step a. Alternatively, the following steps can be used. a2. A thermosetting resin varnish obtained by uniformly dispersing the electrically insulating ceramic-based whisker in the thermosetting resin varnish by stirring has a roughness suitable for bonding to a resin and has a thickness of 1 to 9 μm which becomes a circuit. A second copper layer having a thickness of 10 to 150 μm having sufficient strength for handling as a first copper layer and a metal layer as a whole, and a thickness of 0.04 to 1 provided between the two layers. Coating on the roughened surface of the first copper layer of the composite metal foil composed of a nickel-phosphorus alloy layer of 0.5 μm, heating and semi-curing to form a thermosetting resin layer 6, and forming the through-hole 3 and the inner layer circuit 2 in advance After the thermosetting resin layer 6 is overlaid on the inner circuit board 4 on which is formed, and laminated by laminating by heating and pressing, only the carrier layer is removed, and then only the nickel-phosphorus alloy layer is removed. Process.

Further, using these manufacturing methods, the multilayer printed wiring board manufactured in the step i can be used as an inner layer substrate, and the steps f to i can be repeated as many times as necessary. ).

Further, using the multilayer printed wiring board prepared in step i as an inner layer substrate, a hole serving as a through hole 13 is formed, the inside of the hole is roughened, and the hole is roughened using a roughening agent.
After performing step 4, unnecessary plating 14 is selectively removed by etching, and steps b to i can be further performed.
For example, the structure is as shown in FIG.

Further, using the multilayer printed wiring board prepared in step i as an inner layer substrate, a hole serving as a through hole is formed, the inside of the hole is roughened, the surface is roughened using a roughening agent, and after plating is performed, unnecessary holes are formed. The plating can be selectively removed by etching, and the steps b to e can be further performed.
(C), the multilayer printed wiring board prepared in step i is used as an inner layer substrate, and after steps f to i are repeated as many times as necessary, a hole to be a through hole is formed, and the inside of the hole is roughened. After roughening using a roughening agent and performing plating, unnecessary plating is selectively removed by etching, and further, when Steps b to e are performed, a structure as shown in FIG. Become.

Furthermore, using the build-up multilayer printed wiring board as shown in FIGS. 2C and 2D as an inner layer substrate, the steps f to i can be repeated as many times as necessary. In this case, the structure is as shown in FIG. 2 (e) and FIG. 2 (f).

[0017]

BEST MODE FOR CARRYING OUT THE INVENTION (Thermosetting resin) As the thermosetting resin of the present invention, various resins can be used. Among them, a resin having no film forming ability alone can be used. . Here, the film-forming ability means that the resin is dissolved in a solvent to form a varnish, and the thickness is easily controlled when the varnish is applied to a carrier film.
In addition, when transporting, cutting and laminating a material that has been semi-cured by heating and drying, it is resistant to cracking and chipping of the resin, and it is possible to secure the minimum thickness as an insulating layer at the time of subsequent heat and pressure molding Means

As such a thermosetting resin, there is a resin which is conventionally used by impregnating a glass cloth, for example, a resin whose molecular weight does not exceed 30,000,
Epoxy resin, bismaleimide triazine resin, polyimide resin, phenol resin, melamine resin, silicon resin,
Examples include unsaturated polyester resins, cyanate ester resins, isocyanate resins, and modified resins thereof.
Among them, epoxy resin, bismaleimide triazine resin, and polyimide resin are preferable because of their high Tg, elastic modulus, and hardness. As the epoxy resin, bisphenol F type epoxy resin, bisphenol S type epoxy resin,
Phenol novolak epoxy resin, cresol novolak epoxy resin, bisphenol A novolak epoxy resin, salicylaldehyde novolak epoxy resin, bisphenol F novolak epoxy resin,
Uses alicyclic epoxy resin, glycidyl ester type epoxy resin, glycidylamine type epoxy resin, hydantoin type epoxy resin, isocyanurate type epoxy resin, aliphatic cyclic epoxy resin and their halides and hydrogenated products It can be used together. Among them, bisphenol A novolak epoxy resin and salicylaldehyde novolak epoxy resin are excellent in heat resistance and are preferable.

(Electrically Insulating Ceramic Whisker) The electrically insulating ceramic whisker used in the present invention preferably has an elastic modulus of 200 MPa or more. If it is less than 200 MPa, the rigidity is insufficient and the plate thickness is small. The warpage is large and the mountability on the motherboard is reduced. Such electrically insulating ceramic whiskers include, for example, aluminum borate, wollastonite, potassium titanate,
It can be used by selecting from basic magnesium sulfate, silicon nitride, and α-alumina. Among them, aluminum borate and potassium titanate have the same Mohs hardness as the conventional E glass, and the same wire bonding property as that of the conventional prepreg is obtained.Furthermore, aluminum borate has a high elastic modulus of 400 MPa. It is preferable because it is easily mixed with varnish.

The electrically insulating ceramic whisker preferably has an average diameter of 0.3 to 3 μm and an average length of at least 5 times the average diameter. When the average diameter is less than 0.3 μm, mixing with the resin varnish becomes difficult, and when the average diameter exceeds 3 μm, the dispersion in the resin is not sufficient,
The unevenness of the applied surface becomes large, which is not preferable. This average diameter is more preferably in the range of 0.3 to 1 μm. If the average length is less than 5 times, the rigidity of the resin cannot be obtained,
More preferably, it is 20 times or more. Also,
The upper limit is preferably 50 μm or less, and it is necessary that this numerical value be smaller than the circuit interval of the inner layer circuit, because at present there is no inner layer circuit interval smaller than 50 μm. If the average length exceeds the interval between the inner layer circuits, when the two circuits are in contact with each other, ion migration of copper is likely to occur along the electrically insulating ceramic whisker, and the possibility of short circuit is high, which is not preferable. .

In order to enhance the wettability between the electrically insulating ceramic whisker and the thermosetting resin, it is preferable to use an electrically insulating ceramic whisker whose surface has been treated with a coupling agent. Ring agents include silicon-based coupling agents, titanium-based coupling agents, aluminum-based coupling agents, zirconium-based coupling agents, zirconium-based coupling agents, chromium-based coupling agents, boron-based coupling agents, and phosphorus-based coupling agents. It can be used by selecting from a coupling agent, an amino coupling agent and the like.

(Curing Agent) As the curing agent used for the thermosetting resin of the present invention, any curing agent can be used as long as it is used for the above-mentioned resin. For example, when an epoxy resin is used for the resin, Dicyandiamide, bisphenol A, bisphenol F, polyvinyl phenol resin, novolak resin, and bisphenol A novolak resin are preferred because of their excellent heat resistance. The compounding ratio of this curing agent to the thermosetting resin is preferably in the range of 2 to 100 parts by weight, based on 100 parts by weight of the thermosetting resin, and in the case of dicyandiamide, 2 to 5 parts by weight, In the case of the above-mentioned curing agent, the range of 30 to 80 parts by weight is preferable. If the amount is less than 2 parts by weight, curing will be insufficient, heat resistance will decrease, and
If the amount exceeds the weight part, the electrical properties and heat resistance tend to decrease.

(Curing Accelerator) The thermosetting resin and the curing agent of the present invention further require a curing accelerator. When the thermosetting resin is an epoxy resin, imidazole is used as the curing accelerator. Compound, organic phosphorus compound, tertiary amine, quaternary
Secondary ammonium salts and the like can be used. The compounding ratio of the curing agent is preferably in the range of 0.01 to 20 parts by weight, preferably 0.1 to 20 parts by weight, based on 100 parts by weight of the thermosetting resin.
A range of 1.0 is more preferred. If the amount is less than 0.01 part by weight, the curing becomes insufficient and the heat resistance is reduced. If the amount exceeds 20 parts by weight, the life of the B stage is shortened and the heat resistance is reduced.

(Diluent) The thermosetting resin, the electrically insulating ceramic whisker, the curing agent, and the curing accelerator are used after being diluted with a solvent, and the solvent includes acetone, methyl ethyl ketone, toluene, xylene, methyl isobutylene. , Ethyl acetate, ethylene glycol monomethyl ether, methanol, N, N-dimethylformamide, N, N-dimethylacetamide and the like. The mixing ratio of the diluent to the thermosetting resin is 10%.
The range of 1 to 200 parts by weight relative to 0 parts by weight is preferable,
A range of 30 to 100 parts by weight is more preferable. When the amount is less than 1 part by weight, the viscosity becomes high and coating unevenness is easily generated.
If the amount is more than 00 parts by weight, the viscosity becomes too low and the coating cannot be applied to a required thickness.

(Ratio between thermosetting resin and electrically insulating ceramic whisker) The ratio between the thermosetting resin and the electrically insulating ceramic whisker is determined by the ratio of the electrically insulating ceramic whisker in the cured thermosetting resin. It is preferable to adjust so as to be 5 to 50 vol%. Furthermore, 20-4
More preferably, it is 0 vol%. If the content is less than 5 vol%, the film-forming ability of the thermosetting resin is small, the cutting powder is scattered at the time of cutting, etc., and handling is difficult, the rigidity is low, the warpage of the substrate after chip mounting becomes large, and the mountability is increased. descend. If it exceeds 50% by volume, the step a,
In the case of a1 or a3, at the time of the heat and pressure molding, the embedding into the holes and circuit intervals of the inner layer circuit board is insufficient, so that voids and blurring occur after the molding, and the insulating property is reduced.

(Photosensitive Insulating Resin) As the photosensitive resin composition used in the present invention, a photosensitive insulating resin or a resin combining photosensitivity and thermosetting can be used. Any composition may be used as long as it is a composition containing a copolymer or monomer having the same or a composition in which a heat-crosslinkable functional group and a thermal initiator are mixed in addition to light.

The first group which can be used as other resin components includes epoxy resin, brominated epoxy resin,
Examples include alicyclic epoxy resins such as rubber-modified epoxy resins and rubber-dispersed epoxy resins, bisphenol A-based epoxy resins, and acid-modified epoxy resins. In particular, when photo-curing is performed by light irradiation, modified products of these epoxy resins and unsaturated acids are preferred.

Examples of the unsaturated acid include maleic anhydride, tetrahydrophthalic anhydride, itaconic anhydride, acrylic acid, methacrylic acid and the like. These can be obtained by reacting the unsaturated carboxylic acid with the epoxy group of the epoxy resin in an amount equivalent to or less than the equivalent.

In addition, a thermosetting material such as a melamine resin and a cyanate ester resin, or a combination of the thermosetting material with a phenol resin is also one of the preferable application examples.
Other suitable combinations include the use of a flexibility-imparting agent, such as butadiene acrylonitrile rubber,
Examples include natural rubber, acrylic rubber, SBR, carboxylic acid-modified butadiene acrylonitrile rubber, carboxylic acid-modified acrylic rubber, crosslinked NBR particles, carboxylic acid-modified crosslinked NBR particles, and the like.

By adding such various resin components, it becomes possible to impart various properties to the cured product while maintaining the basic properties such as photocurability and thermosetting properties. For example,
Good electrical insulation can be imparted to the cured product by a combination with an epoxy resin or a phenol resin.

When the rubber component is blended, the cured product is given tough properties, and the surface treatment with an oxidizing chemical makes it possible to easily roughen the surface of the cured product. The curable composition may contain commonly used additives (polymerization stabilizer, leveling agent, pigment, dye, etc.). There is no problem in adding a filler. As the filler, silica, fused silica, talc, alumina, hydrated alumina, barium sulfate, calcium hydroxide, aerosil, inorganic fine particles such as calcium carbonate, powdered epoxy resin, organic fine particles such as powdered polyimide particles, powdered Teflon particles And the like. These fillers may be subjected to a coupling treatment in advance. These dispersions are achieved by a known kneading method such as a kneader ball mill, a bead mill, or a three-roll mill.

(Developer) Next, a via hole to be connected to the second circuit is formed in the insulating resin layer by a method of etching the unexposed portion with the developer. As the developer, an aqueous alkaline developer containing an organic solvent is used. Examples of the organic solvent used in the developer include glycol derivatives such as ethylene glycol, propylene glycol, trimethylene glycol, 1,4-butanediol,
Examples thereof include 5-pentanediol, 1,6-hexanediol, pinacol, dimers, trimers, multimers thereof, and substituted products of lower alkyl groups such as methyl, ethyl, propyl, and butyl groups. Specific examples include diethylene glycol, ethylene glycol monoethyl ether, triethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monobutyl ether, and the like. Also, diacetone alcohol, acetone, ethyl acetate, 2-methoxyethanol,
2-ethoxyethanol, ethyl alcohol, methyl alcohol, isopropyl alcohol, butyl alcohol and the like are used. These may contain two or more organic solvents. In particular, diethylene glycol is effective for that purpose. The concentration of the organic solvent is 1 to 50% by volume. Preferably, it is 5 to 35% by volume. Examples of the aqueous alkaline developer used for the developer include alkali metal hydroxides, carbonates, phosphates, borates and the like. Examples include sodium hydroxide, potassium hydroxide, ammonium hydroxide, sodium carbonate, potassium carbonate, trisodium phosphate, sodium borate, sodium metasilicate and the like. As a combination of an aqueous alkaline developer containing an organic solvent, an aqueous solution containing diethylene glycol monobutyl ether and sodium borate is preferably used. The concentration of diethylene glycol monobutyl ether is 5 to 30% by volume, and the concentration of sodium borate is 5 to 30% by volume.
30 g / l is preferred.

(Rinse treatment) Next, a rinse treatment is performed on the insulating resin layer after development. As the rinsing liquid, an aqueous solution containing an organic solvent is used. As the organic solvent, the organic solvent described for the developer can be used. It is particularly preferable to use an aqueous solution containing diethylene glycol monobutyl ether. The concentration of diethylene glycol monobutyl ether is preferably from 0.1 to 90% by volume, particularly from 1 to 90% by volume.
20% by volume is more preferred. The method of rinsing may be dipping or spraying, and the method is not particularly limited. If the amount is less than 0.1% by volume, the effect is poor, and if it exceeds 90% by volume, there is no difference in effect, and a large amount of energy is required for waste liquid treatment.

(Step a) In this step, in order to apply a thermosetting resin and an electrically insulating ceramic whisker to the copper foil, the thermosetting resin, the curing agent, the curing accelerator, and the diluent are mixed. An electrically insulating ceramic whisker was mixed with the solution (hereinafter, referred to as a thermosetting resin varnish),
The agitated varnish is applied, heated, and semi-cured.A shearing force is applied in a direction parallel to the copper foil, such as a blade coater, a rod coater, a knife coater, a squeeze coater, a reverse roll coater, or a transfer roll coater. Can be loaded or in a direction perpendicular to the plane of the copper foil,
It is preferable to select a coating method capable of applying a compressive force. The thickness of this thermosetting resin layer after semi-curing is 25 to 1
It is preferably in the range of 00 μm. This resin flow is preferably adjusted in the range of 500 μm to 10 mm. If it is less than 500 μm, the embedding property of the inner layer copper foil is small and irregularities are generated on the surface. If it exceeds 10 mm, the thickness of the end portion after lamination is reduced. It is thin and has poor insulation. This resin flow refers to a method in which a 30 mm square hole is made in a prepreg with a copper foil having a thickness of 50 μm and the resin is overlapped with the copper foil surface of the copper-clad laminate at a temperature of 170 ° C. and 2.5 Mpa.
The minimum distance of the resin that has flowed out from the edge of the 30 mm square hole to the surface of the copper foil when laminating and adhering by heating and pressurizing for 30 minutes.

(Step a1) This step a1 is the same as step a1
If the copper foil used in step a is very thin, it may be laid or wrinkled in the handling process, so a composite metal foil composed of a thin copper foil and a carrier is used. By allowing easy handling, laminating the inner layer circuit board, peeling the carrier, and processing the thin copper foil to form a circuit, thereby enabling finer processing of circuit conductors. is there.

(Step a2) In this step, when a thin copper foil is handled, in the case of a physically peelable carrier, in the handling step, a scratch may be generated on the surface of the copper foil or foreign matter may adhere. In order to prevent this, a composite metal foil having a high degree of adhesion is used, and a metal having a chemical removal condition different from that of the circuit conductor is used for removing the carrier. By the way, if such a metal layer is thick, it is not economical and the process becomes long. Therefore, an intermediate layer is used at a position where etching is to be stopped. As a solution for etching and removing only the second copper layer, a solution containing chlorine ions, ammonium ions, and copper ions (hereinafter, referred to as an alkali etchant) is used. The treatment is carried out by contact with a solution such as dipping or spraying. Further, in the step of removing only the nickel-phosphorus alloy, a liquid containing nitric acid and hydrogen peroxide as main components is added with an organic acid having a carboxyl group as an additive and -NH- and -N = as ring members. Or by spraying an aqueous solution containing a nitrogen-containing heterocyclic compound.

(Step b) In this step, an ordinary method of forming a plating resist for a wiring board can be used. That is, a method in which a peelable resist ink is printed on the surface of the copper foil by a silk screen printing method, a method in which a peelable resist film is laminated on the surface of the copper foil, and the first via hole 8 is formed via a photomask. A method of irradiating ultraviolet rays to the shape of the hole to be developed and developing and removing the portion of the hole can be used. In order to etch the copper foil, a chemical etching solution is brought into contact with the copper foil exposed from the etching resist formed as described above to selectively remove the copper etching solution. There are a dicopper solution and a ferric chloride solution. In order to chemically remove the etching resist, it is usually removed using a solvent or an aqueous alkaline solution.

(Step c) Drilling of the via hole is performed by a specific method such as laser, sand blast, plasma,
Although there is chemical etching or the like, a laser having good drilling properties is used. By irradiating a laser beam, the circuit conductor of the inner layer circuit board 4 is removed until the circuit conductor is exposed to form a via hole. Lasers that can be used in this step include a carbon dioxide laser, a YAG laser, an excimer laser, and the like, and a carbon dioxide laser is preferable from the viewpoint of productivity. The irradiation conditions of the laser beam at this time are preferably such that the pulse is oscillated with a short time and a large output. For example, the width of one pulse is 1 to 40 μsec and the pulse repetition frequency is 150 to 1
A laser oscillator capable of producing an output capable of drilling holes with an output magnitude in the range of 2 to 5 pulses under the conditions of 000 Hz and a repetition pulse number of 1 to 10 pulses is preferable because oscillation and control are easy. This output is in the range of 15 to 40 J / cm ² in terms of energy density. If the output per time is less than the above range, the resin layer cannot be evaporated and diverged.If the output exceeds the above range, the hole diameter becomes more than necessary and control is difficult, and the once evaporated resin is carbonized. It may adhere, and the attached carbide must be removed.

(Step d) As the roughening agent used in this step, any one can be used as long as it swells and dissolves the resin. Usually, it is preferable to use an aqueous solution of alkali permanganate. The plating used in this step uses the same technique as that of the through-hole plating of a normal wiring board. That is, a substance serving as a nucleus of plating such as palladium is adhered to the roughened resin layer, and an ionized plating metal,
The plating metal is brought into contact with an electroless plating solution having a complexing agent for the plating metal and a reducing agent for the plating metal to deposit the plating metal on the entire wall. By performing plating in this manner, the outer layer copper foil, the wall surface of the IVH, and the circuit conductor of the inner layer circuit board 4 can be electrically connected.

(Step e) In this step, as in step b,
This is a step of forming an outer layer circuit and removing the etching resist.

(Step f) In this step, an aqueous solution containing an alkaline oxidizing agent can be used for the oxidation treatment of the conductor circuit surface, and an aqueous solution containing an alkaline reducing agent can be used for the subsequent reduction treatment. Usually, it can be carried out by immersion.

(Step g) In this step, the method of forming the insulating resin layer includes a method in which a liquid resin is applied by a method such as roll coating, curtain coating, or dip coating, or a method in which the resin is formed into a film and bonded by lamination. Can be used. Exposure through a photomask can be performed using the same method as a normal method for forming a resist on a wiring board, and development is also performed using a dip, spray, or the like, which is used for manufacturing a normal wiring board. By contacting the substrate with the developing solution, the uncured portion of the resin layer can be removed. In order to more effectively remove the etching resist, it is preferable to use an aqueous solution containing an organic solvent as a rinsing liquid after development.

(Step h) The oxidizing roughening solution used in this step includes a roughening solution of chromium / sulfuric acid, a roughening solution of alkali permanganate, a roughening solution of sodium fluoride / chromium / sulfuric acid, a roughening solution of borofluoric acid. And the like can be used. Usually, it is preferable to use an aqueous solution of alkali permanganate. The plating is a step of performing electroless plating in the same manner as in the step d. Further, electroplating may be additionally performed as necessary.

(Step i) This is a step of forming an outer layer circuit and removing the etching resist as in the step b.

[0045]

EXAMPLE 1 Step a2: As shown in FIG. 1 (a), a glass cloth-epoxy resin impregnated glass cloth-epoxy resin impregnated double-sided copper-clad laminate as shown in FIG. MCLE as a plate
Using -679 (trade name, manufactured by Hitachi Chemical Co., Ltd.), drilling, electroless copper plating, forming the inner layer circuit 2 by a normal subtraction method, and manufacturing the inner layer circuit board 4 having through holes 3 did. Next, on the surface of the first copper layer of the composite metal foil composed of the first copper layer having a thickness of 5 μm / the nickel-phosphorus alloy layer having a thickness of 0.2 μm / the second copper layer having a thickness of 15 μm, A 30 vol% aluminum borate whisker was mixed with the resin content of the thermosetting resin varnish having the composition of the above, stirred, applied with a knife coater, and heated at 150 ° C. for 10 hours.
After drying for 5 minutes, an adhesive film with a copper foil having a semi-cured thermosetting resin layer 6 having a thickness of 50 μm was prepared. (Composition of thermosetting resin varnish) ・ Bisphenol A novolak epoxy resin 100 parts by weight (Epoxy equivalent: 200) ・ Bisphenol A novolak resin 60 parts by weight (hydroxyl equivalent: 106) 2-ethyl-4-methylimidazole (curing agent) 0.5 parts by weight Methyl ethyl ketone (diluent) ... 100 parts by weight The inner circuit board 4 thus produced and the adhesive film with copper foil are combined with the inner circuit 2 of the inner circuit board 4 as shown in FIG. The thermosetting resin layer 61 of the adhesive film is overlaid so as to be in contact with the adhesive film, and is heated at 170 ° C for 60 minutes at
, And the layers were integrated by heating and pressing. Under these conditions, the resin flow was 3 mm. Only the second copper layer was removed by etching with the following alkaline etchant. (Alkali etchant) ・ CuCl ₂・ ・ ・ ・ ・ ・ 175g / l ・ NH ₄ OH ··········· 154 g / l · NH ₄ Cl ······ 236 g / l Liquid temperature: 50 ° C Nickel Only the phosphorus alloy layer was removed by etching with the following etching solution. (Nickel-phosphorus etchant composition) ・ Nitric acid ・ ・ ・ ・ ・ ・ ・ ・ 200g / l ・ Hydrogen peroxide solution (35wt%)・ ・ ・ ・ ・ ・ ・ ・ 10ml / l ・ Organic acid containing carboxyl group (Dl malic acid) ・ ・ ・ ・ ・ ・ ・ 100g / l ・ Benzotriazole ・ ・ ・ ・ ・ ・ ・ ・ ・・ ・ ・ ・ 5g / l

Step b: The first layer formed as the copper foil 21
On the copper foil of the dry film Photek H-K425
(Hitachi Kasei Kogyo Co., Ltd., trade name), an etching resist is formed, and a portion of the copper foil 21 exposed from the etching resist is used as an opening of the copper foil for forming a via hole. Etching is removed to a shape, and the etching resist is replaced with 2% by weight of Na.
It was removed by an aqueous OH solution at 40 ° C. for 2 minutes.

Step c: Exposed from the opening of the copper foil 21
The cured thermosetting resin layer 6 was irradiated with carbon dioxide laser light at an energy density of 20 J / cm ² and an oscillation time of 1 hour.
By irradiating under the conditions of 4 μs, an oscillation frequency of 150 Hz and 4 pulses, as shown in FIG. 1C, the inner layer circuit board 4 is removed until the inner layer circuit 2 is exposed, and the first via hole is removed. 8 was formed.

Step d: The hardened thermosetting resin layer 6 on the wall surface of the hole 82 is coated with a 7 wt% aqueous solution of alkali permanganate as a roughening agent at a liquid temperature of 70 ° C. for 5 minutes. In order to roughen and electrically connect the inner layer circuit 2 of the inner layer circuit board 4 and the copper foil 21, plating is performed at a solution temperature of 70 ° C. using an electroless plating solution having the following composition. Was. (Composition of electroless _{plating) · CuSO 4 · 5H 2 O} ···················· 10g / l · EDTA · 4Na ········· 40g / l 37wt% HCHO 3ml / l NaOH ..... Amount to make pH 12.3

Step e: Dry film Photek H-W440 (manufactured by Hitachi Chemical Co., Ltd.
An etching resist according to the trade name) was formed, the portion exposed from the etching resist was removed by etching, and the etching resist was removed, thereby forming a circuit conductor as shown in FIG. 1 (d).

Step f: As a pre-multilayer bonding treatment on the surface of the conductor circuit, a copper surface is oxidized to form irregularities, and then a reduction treatment is performed. (Oxidation solution) ・ NaOH ・ ・ ・ ・ ・ ・ ・ 20g / l ・ Na ₃ PO ₄・ 12H ₂ O ・ ・ ・ ・ ・ ・・ ・ ・ ・ 30g / l ・ NaClO ₂・ ・ ・ ・ 80g / l ・ Pure water ・ ・ ・··························· Temperature: 85 ° C Time: 120 seconds (reduction treatment solution) ・ NaOH 5 g / l Dimethylamine borane 5 g / l Temperature: 25 ° C Time : 120 seconds

Step g: As shown in FIG. 1 (e), a photosensitive resin 91 having the following composition was applied on a polyethylene terephthalate film (50 μm thick) which had been subjected to a release treatment, and was heated at 80 ° C. After drying for 10 minutes, a film having a thickness of 60 μm was formed, and an insulating resin layer was formed by lamination. HIM-V530 (trade name, manufactured by Hitachi AIC Co., Ltd.) was used as a laminator under the following conditions.・ Laminating atmosphere: under reduced pressure (760 torr) ・ Air gauge pressure: 3 kg / cm ²・ Laminating speed: 0.5 m / min ・ Roll temperature: 110 ° C. (photosensitive insulating resin) ・ 2,2 ′ screw (4, 4 ′) -N-maleimidylphenoxyphenyl) propane 30 parts by weight Bisphenol A type epoxy with an epoxy equivalent of 500 Acid-modified epoxy resin synthesized by reacting one equivalent of tetrahydrophthalic anhydride with a resin under a nitrogen atmosphere at 150 ° C for 10 hours Acrylonitrile butadiene rubber containing 4 mol% of carboxyl groups in the molecule (PNR-1H, Nippon Synthetic Rubber Co., Ltd., trade name) 20 parts by weight 1,3-bis (9,9 '-Diakri Dino) heptane 5 parts by weight Aluminum hydroxide 10 parts by weight Irgacure 651 (manufactured by Ciba-Geigy) Name) ... 5 parts by weight Next, as shown in FIG. 1 (f), a light amount of 300 m is applied through a photomask in which a shielding portion is formed in a portion to be a via hole.
After irradiation with ultraviolet light of J / cm ² , the polyethylene terephthalate film on the film surface was peeled off, and the unexposed portion was developed and rinsed. As a developing solution, an aqueous alkaline developing solution containing an organic solvent was used, and diethylene glycol monobutyl ether was used as an organic solvent to 10% by volume. Further, an aqueous solution containing 15 g / l using sodium tetraborate (decahydrate) as an alkaline substance was prepared.
Development was performed at 0 ° C. for 4 minutes at a spray pressure of 1.0 kg / cm ² . As an aqueous solution containing an organic solvent as a rinse solution after development, diethylene glycol monobutyl ether,
An aqueous solution containing 0% by volume was rinsed at 40 ° C. for 4 minutes at a spray pressure of 1.0 kg / cm ² to form a hole 111 serving as a via hole.

Step h: Apply ultraviolet light 2 to the substrate after development and rinsing.
After irradiating J / cm ² and then heat-treating at 150 ° C. for 1 hour to perform post-curing, KMnO ₄ : 60 g / l, NaOH: 40 g /
1 was prepared, heated to 50 ° C., and immersed for 10 minutes. After _{this, SnC1 2: 30g / l,} HC
l: Neutralization treatment was performed by immersion treatment in a 300 ml / l aqueous solution at room temperature for 5 minutes. After the roughening treatment, in order to form a conductor circuit on the surface of the insulating layer, first, a catalyst HS for electroless copper plating is used.
It was immersed in −202B (trade name, manufactured by Hitachi Chemical Co., Ltd.) at room temperature for 15 minutes, and further electroplated with copper sulfate to form a 15 μm thick conductor layer on the surface of the insulating layer.

Step i: In order to remove unnecessary portions of the plated conductor, an etching resist was formed, and etching was performed using a hydrochloric acid / iron chloride etchant to form a circuit pattern. Next, similarly to the step (c), the etching resist was removed, and a build-up multilayer printed wiring board was manufactured as shown in FIG.

Example 2 Except for mixing and stirring 10 vol% of aluminum borate whiskers with respect to the resin content of the thermosetting resin varnish,
All operations were performed in the same manner as in Example 1. Laser drilling conditions were as follows: an energy density of 20 J / cm ² , an oscillation time of 1 μs, an oscillation frequency of 150 Hz, and a pulse number of 3 with a carbon dioxide laser.

Example 3 Except that 45 vol% of aluminum borate whiskers were mixed and stirred with respect to the resin content of the thermosetting resin varnish,
All operations were performed in the same manner as in Example 1. Laser drilling conditions are:
The energy density was 20 J / cm ² , the oscillation time was 1 μs, the oscillation frequency was 150 Hz, and the number of pulses was 5 with a carbon dioxide gas laser.

Example 4 The procedure of Example 1 was repeated, except that the following step a1 was used instead of step a2 of Example 1. Step a1: Using a 0.6 mm thick glass cloth-epoxy resin impregnated double-sided copper-clad laminate MCLE-679 (trade name, manufactured by Hitachi Chemical Co., Ltd.), drilling, electroless copper plating, and The inner layer circuit board 4 having through holes was produced by the subtraction method described above. A 30 vol% aluminum borate whisker is mixed with the resin content of the thermosetting resin varnish having the following composition on the surface of the thin copper layer of the composite metal foil composed of a thin copper foil having a thickness of 5 μm / a carrier copper layer having a thickness of 70 μm. The mixture was stirred, coated with a knife coater, and dried at 150 ° C. for 10 minutes to prepare a semi-cured adhesive film with a copper foil having a thermosetting resin having a thickness of 50 μm. (Composition of thermosetting resin varnish) Bisphenol A novolak epoxy resin 100 parts by weight (epoxy equivalent: 200) Bisphenol A novolak resin 60 parts by weight (hydroxyl equivalent: 106) 2-ethyl-4-methylimidazole (curing agent) ... 0.5 parts by weight-Methyl ethyl ketone (diluent) ... ..... 100 parts by weight

Comparative Example 1 Instead of the adhesive film with copper foil of Example 1, a prepreg obtained by applying and impregnating the following thermosetting resin varnish to a glass cloth was laminated between the composite metal foil and the inner layer circuit. Example 1
In the same manner as in the above, a build-up multilayer printed wiring board was produced. (Composition of thermosetting resin varnish) Bisphenol A novolak epoxy resin 100 parts by weight (epoxy equivalent: 200) Bisphenol A novolak resin 60 parts by weight (hydroxyl equivalent: 106) 2-ethyl-4-methylimidazole (curing agent) ... 0.5 parts by weight-Methyl ethyl ketone (diluent) ... ..... 100 parts by weight

Comparative Example 2 Instead of the adhesive film with a copper foil of Example 1, a film coated with the following thermosetting resin varnish was used and laminated between the composite metal foil and the inner layer circuit. Similarly, a build-up multilayer printed wiring board was produced. (Composition of thermosetting resin varnish) Bisphenol A novolak epoxy resin 100 parts by weight (epoxy equivalent: 200) Bisphenol A novolak resin 60 parts by weight (hydroxyl equivalent: 106) 2-ethyl-4-methylimidazole (curing agent) ... 0.5 parts by weight-Methyl ethyl ketone (diluent) ... ..... 100 parts by weight

Comparative Example 3 Instead of the adhesive film with copper foil, the thermosetting resin varnish of Comparative Example 2 was applied directly on the inner circuit board 4 by a silk screen printing method, and the copper foil was layered on A laminate was integrated by heating and pressing, and laminated between the composite metal foil and the inner layer circuit, and a build-up multilayer printed wiring board was produced in the same manner as in Example 1.

The following tests were performed on the build-up multilayer printed wiring boards manufactured as described above. Table 1 shows the results.
Shown in (Test)-Gas phase thermal shock test: Thermal shock tester Therma Shock Chamber TSR-103 (TABAI, trade name)
-65 ° C., 30 minutes⇔125 ° C., 30 minutes
A cycle was taken, and a change in connection resistance was measured. To measure the connection resistance, use a Hewlett-Packard multimeter 34
It was measured using 57A.

[0061]

[Table 1]

[0062]

As described above, according to the present invention, the thickness of the interlayer can be reduced, the wiring can be miniaturized, and the IVH and BV can be reduced.
It is possible to provide a multilayer printed wiring board excellent in reducing the diameter of H, excellent in strength, excellent in connection reliability, and excellent in productivity, and a method of manufacturing the same.

[Brief description of the drawings]

FIGS. 1A to 1G are cross-sectional views showing respective steps for explaining one embodiment of the present invention.

FIGS. 2A to 2F are cross-sectional views each showing another embodiment of the present invention.

[Explanation of Codes] 1. Insulating base material 2. Inner layer circuit Through hole 4. Inner layer circuit board 6. 6. Thermosetting resin layer 7. First circuit First via hole 82. Hole 9. Photosensitive resin layer 10. Second circuit 11. Second via hole 111. Hole 13. Through hole 14. Plating 21. Copper foil

 ──────────────────────────────────────────────────の Continuing on the front page (72) Masao Sugano 1500 Ogawa Ogawa, Shimodate City, Ibaraki Prefecture Inside Shimodate Research Laboratory, Hitachi Chemical Co., Ltd. (72) Shigeharu Ariya 1500 Ogawa Ogawa Shimodate City, Ibaraki Prefecture Hitachi Chemical Industries Inside Shimodate Research Laboratory (72) Inventor ▲ Tsuru ▼ Yoshiyuki 1500 Ogawa, Shimodate-shi, Ibaraki Pref.Hitachi Chemical Industry Co., Ltd. Tsukuba Development Laboratory

Claims (12)

[Claims] 1. An insulating substrate (1), an inner layer circuit (2) formed on both sides thereof, and an inner layer circuit on both sides thereof formed by through holes (3).
An inner circuit board (4) electrically connected to (2) and a thermosetting resin layer in which an electrically insulating filler is uniformly dispersed on the surface
(6) and the first layer formed on the surface of the thermosetting resin layer (6).
Circuit (7), a first via hole (8) for electrically connecting the inner layer circuit (2) and the first circuit (7), and a photosensitive resin layer ( 9) and its photosensitive resin layer
A second circuit (10) formed on the surface of (9), and a second via hole (11) for electrically connecting the first circuit (7) and the second circuit (10). Having a through hole (3) of the inner circuit board (4) filled with an insulating resin in which the same electrically insulating filler as the thermosetting resin layer (6) is uniformly dispersed. Characterized build-up multilayer printed wiring board. 2. The method according to claim 1, wherein the first via hole is formed by a method of physically and chemically removing the thermosetting resin layer partially. The described build-up multilayer printed wiring board. 3. The build-up multilayer printed wiring board according to claim 1, wherein the electrically insulating filler is a ceramic whisker. 4. A method for manufacturing a build-up multilayer printed wiring board, comprising the steps of: a. A thermosetting resin varnish is blended with an electrically insulating ceramic whisker, which is an electrically insulating filler, and the electrically insulating ceramic whisker is uniformly dispersed in the thermosetting resin varnish by stirring. Coating on the roughened surface of foil (21), heating and semi-curing to form thermosetting resin layer (6), insulating substrate (1) and inner layer circuit previously formed on both surfaces
(2) and inner layer circuit (2) on both sides by through hole (3)
A step of laminating the thermosetting resin layer (6) on an inner circuit board (4) to which the above is electrically connected, and heating and pressing to laminate and integrate. b. Forming an etching resist on the copper foil (21),
Removing the portion exposed from the etching resist into the shape of the first via hole (8) by etching, and removing the etching resist. c. The cured thermosetting resin layer (6) exposed from the fine hole of the copper foil (21) etched and removed in the shape of the hole of the first via hole (8) is irradiated with a laser beam, Removing the inner layer circuit (2) until the inner circuit (2) is exposed to form a hole (82) serving as a first via hole (8). d. A step of roughening the resin surface of the cured thermosetting resin layer (6) on the wall surface of the hole (82) using a roughening agent, and performing plating. e. Forming an etching resist on the plating, etching away the plating and the copper foil (21) exposed from the etching resist, forming a first circuit (7), and then removing the etching resist. f. A step of oxidizing the surface of the first circuit (7) to form irregularities and reducing the formed copper oxide; g. A liquid photosensitive resin is applied to the surface on which the first circuit (7) is formed, a photosensitive resin layer (9) is formed, exposed and developed through a photomask, and a second via hole (11) is formed. Forming a hole (111). h. A step of roughening the resin surface of the photosensitive resin layer (9) including the wall surface of the hole (111) with an oxidizing roughening solution and performing plating. i. Forming an etching resist on the surface of the plating,
A step of selectively etching away the plating exposed from the etching resist to remove the etching resist. 5. Step a. 5. The method for manufacturing a build-up multilayer printed wiring board according to claim 4, further comprising the following steps. a1. A thermosetting resin varnish obtained by uniformly dispersing the electrically insulating ceramic whisker in the thermosetting resin varnish by agitation, having a roughness suitable for bonding with a resin and a copper layer serving as a circuit as a whole. Two layers consisting of a carrier layer having sufficient strength for handling as a metal layer of the above are applied to the roughened surface of the copper layer of the composite metal foil which can be easily peeled off, heated and semi-cured, and a thermosetting resin layer (6) After forming the through hole (3) and the inner layer circuit (2) on the inner layer circuit board (4), the thermosetting resin layer (6) is stacked, and heated and pressurized to be laminated and integrated. Removing only the carrier layer. 6. Step a. 5. The method for manufacturing a build-up multilayer printed wiring board according to claim 4, further comprising the following steps. a2. A thermosetting resin varnish obtained by uniformly dispersing the electrically insulating ceramic-based whisker in the thermosetting resin varnish by stirring has a roughness suitable for bonding to a resin and has a thickness of 1 to 9 μm which becomes a circuit. A second copper layer having a thickness of 10 to 150 μm having sufficient strength for handling as a first copper layer and a metal layer as a whole, and a thickness of 0.04 to 1 provided between the two layers. 0.5 μm nickel-phosphorus alloy layer is applied to the roughened surface of the first copper layer of the composite metal foil, and is heated and semi-cured to form a thermosetting resin layer (6). Inner circuit board with inner layer circuit (2)
(4) a step of superposing the thermosetting resin layer (6) on the upper layer, heating and pressurizing to integrate the layers, and then removing only the carrier layer and only the nickel-phosphorus alloy layer. 7. The resin flow of the thermosetting resin is 500 μm
The thickness after semi-curing of the thermosetting resin layer is 25
The thickness is in the range of 100 to 100 μm.
7. The method for producing a build-up multilayer printed wiring board according to any one of 6. 8. The build-up multilayer print according to claim 4, wherein the amount of the electrically insulating ceramic whisker to be mixed with the thermosetting resin is 5 to 50 vol%. Manufacturing method of wiring board. 9. The build according to any one of claims 4 to 8, wherein the steps f to i are repeated a required number of times using the multilayer printed wiring board produced in the step i as an inner layer substrate. Manufacturing method of up multilayer printed wiring board. 10. Using the multilayer printed wiring board prepared in step i as an inner layer substrate, drilling a hole to be a through hole, roughening the inside of the hole with a roughening agent, plating, and selecting unnecessary plating. Etching and further removing
The method for producing a build-up multilayer printed wiring board according to any one of claims 4 to 9, wherein step i is performed. 11. Using the multilayer printed wiring board prepared in step i as an inner layer substrate, drilling a hole to be a through hole, roughening the inside of the hole with a roughening agent, plating, and selecting unnecessary plating. Etching and further removing
The method for manufacturing a build-up multilayer printed wiring board according to any one of claims 4 to 9, wherein step e is performed. 12. The build-up multilayer printed wiring board according to claim 11, wherein the multilayer printed wiring board manufactured in the step i is used as an inner substrate, and the steps f to i are repeated as many times as necessary. Production method.