JP2005286089A - Method for manufacturing multilayer printed wiring board - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for manufacturing a highly reliable multilayer printed wiring board wherein the external layer conductor circuit is high in surface smoothness and in adhesion with an insulating resin layer. <P>SOLUTION: In the method for manufacturing a multilayer printed circuit board, an insulating resin layer is formed on the surface of an internal layer circuit board with an internal layer conductor circuit formed thereon, and then an external layer conductor circuit is formed on the outer surface of the insulating resin layer. The method comprises (a) a step wherein a insulating resin layer material, formed of a hardenable resin-containing resin composition and showing a first heat generation peak and a second heat generation peak positioned at a higher temperature than the first in differential scanning calorimetry, is integratedly laminated on the internal layer circuit board for the formation of an insulating resin layer on the internal layer circuit board. The method further comprises (b) a step of producing corrugation on the outer surface of the insulating resin layer, (c) a step of forming an external layer conductor circuit on the corrugated surface, and (d) a step of heat treatment to follow the external layer conductor circuit forming step. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a method for manufacturing a multilayer printed wiring board.

  In recent years, with the demand for higher functionality of electronic devices, etc., high density integration and high density mounting of electronic components are progressing. For this reason, printed wiring boards and the like for high-density mounting used for these are smaller and higher in density than conventional ones. As a measure for increasing the density of such printed wiring boards, a multilayer wiring board by a build-up method is often used.

A general build-up multilayer wiring board is obtained by alternately laminating insulating resin layers having a thickness of 100 μm or less composed of a resin composition and conductor layers and bonding them by performing heat-pressure molding or the like. It has been.
Here, as a method of joining the insulating resin layer and the conductor layer, for example, an inner layer circuit board obtained by subjecting a base material with resin obtained by applying an insulating resin layer to a base material such as copper foil or an organic film to a circuit. There is a method of laminating on top and heating and press-molding this (see, for example, Patent Document 1).
In this method, after joining the insulating resin layer of the base material with resin and the inner layer circuit board, when using the metal foil base material, the outer layer conductor circuit is etched by etching the metal foil according to a predetermined pattern. Or a method of forming a predetermined outer layer conductor circuit by conducting metal plating after removing the entire surface of the metal foil or organic film.

However, when forming an outer layer conductor circuit from a metal foil by etching, there is a limit to miniaturization of the circuit. On the other hand, when an outer layer conductor circuit is formed by plating, it is necessary to form fine irregularities on the surface of the insulating resin layer on which the circuit is to be formed. In some cases, roughening proceeds to the entire surface to form large and uneven unevenness, and it is difficult to form fine unevenness uniformly.
In addition, there is a method using a roughened surface profile using a single-sided roughened copper foil as the base material. However, since the roughened surface has large irregularities, the conductive circuit is formed especially when the conductive circuit to be formed is fine. As a result, the smoothness of the conductor deteriorates, and the conductive loss increases due to the unevenness of the conductor circuit.
In these methods, there is a problem that the adhesion (peel strength) between the outer conductor circuit and the insulating resin layer is insufficient, and variations are likely to occur depending on the portion.

Japanese Patent Laid-Open No. 06-260760

  The present invention provides a method for producing a multilayer printed wiring board excellent in reliability, capable of forming a fine outer layer conductor circuit excellent in smoothness and adhesion to an insulating resin layer. .

Such an object is achieved by the following present inventions (1) to (7).
(1) A method for producing a multilayer printed wiring board by forming an insulating resin layer on the surface of an inner layer circuit board on which an inner layer conductor circuit has been formed in advance, and forming an outer layer conductor circuit on the outer surface of the insulating resin layer. There,
(A) Insulating resin layer material formed from a resin composition containing a curable resin and having a first exothermic peak and a second exothermic peak located at a higher temperature in differential scanning calorimetry, Forming an insulating resin layer on the inner circuit board by stacking and integrating on the inner circuit board;
(B) forming a concavo-convex shape on the outer surface of the insulating resin layer;
(C) a step of forming an outer layer conductor circuit on the formed uneven surface, and
(D) a step of performing a heat treatment after forming the outer layer conductor circuit;
A method for producing a multilayer printed wiring board, comprising:
(2) In the step (a), the insulating resin layer material includes, as a curable resin, a first curable resin that exhibits the first exothermic peak, and a second that exhibits the second exothermic peak. The manufacturing method of the multilayer printed wiring board as described in said (1) which contains the curable resin of.
(3) The method for producing a multilayer printed wiring board according to (1) or (2), wherein in the step (a), the curing reaction of the first curable resin is substantially performed.
(4) In the step (b), the second curable resin component is removed from the outer surface portion of the insulating resin layer by a desmear treatment before the curing reaction, thereby forming an uneven shape on the outer surface of the insulating resin layer. The manufacturing method of the multilayer printed wiring board in any one of said (1) thru | or (3) which forms.
(5) The method for producing a multilayer printed wiring board according to any one of (1) to (4), wherein in the step (d), the curing reaction of the second curable resin is substantially performed.
(6) The method for producing a multilayer printed wiring board according to any one of (1) to (5), wherein the first exothermic peak is in a range of 120 to 200 ° C.
(7) The method for producing a multilayer printed wiring board according to any one of (1) to (6), wherein the second exothermic peak is in a range of 150 to 250 ° C.

  According to the present invention, a fine outer layer conductor circuit excellent in smoothness and adhesion to an insulating resin layer can be formed, and a multilayer printed wiring board excellent in reliability can be manufactured.

Hereinafter, the manufacturing method of the multilayer printed wiring board of this invention is demonstrated.
The method for producing a multilayer printed wiring board of the present invention (hereinafter sometimes simply referred to as “manufacturing method”) includes forming an insulating resin layer on the surface of an inner layer circuit board on which an inner layer conductor circuit has been formed in advance, A method of manufacturing a multilayer printed wiring board by forming an outer layer conductor circuit (hereinafter simply referred to as “outer layer circuit”) on the outer surface of a layer,
(A) Insulating resin layer material formed from a resin composition containing a curable resin and having a first exothermic peak and a second exothermic peak located at a higher temperature in differential scanning calorimetry, Forming an insulating resin layer on the inner circuit board by stacking and integrating on the inner circuit board;
(B) forming a concavo-convex shape on the outer surface of the insulating resin layer;
(C) a step of forming an outer layer conductor circuit on the formed uneven surface, and
(D) a step of performing a heat treatment after forming the outer layer conductor circuit;
It is characterized by having.

In the production method of the present invention, first,
(A) Insulating resin layer material formed from a resin composition containing a curable resin and having a first exothermic peak and a second exothermic peak located at a higher temperature in differential scanning calorimetry, An insulating resin layer is formed on the inner circuit board by stacking and integrating on the inner circuit board.

The insulating resin layer material used in the step (a) is composed of a resin composition containing a curable resin, and in the differential scanning calorimetry, the first exothermic peak and the second temperature located at a higher temperature than this. It has an exothermic peak.
Specifically, there are two exothermic peaks appearing at different temperatures on the DSC curve illustrating the relationship between the temperature rise and the calorific value obtained by the differential scanning calorimetry.

The differential scanning calorimetry used in the production method of the present invention is a technique for quantitatively detecting a change in thermal energy generated from a sample when the sample is heated at a predetermined temperature condition. It can be performed using a calorimetric analyzer.
Although it does not specifically limit as temperature rising conditions at the time of performing differential scanning calorimetry here, It is preferable to implement at 5-10 degreeC / min. Thereby, evaluation can be performed with good reproducibility.

Although it does not specifically limit as a 1st exothermic peak here, It exists in the range of 120-200 degreeC. More preferably, it is 150-200 degreeC.
The second exothermic peak is not particularly limited, but is preferably in the range of 150 to 250 ° C. More preferably, it is 180-250 degreeC.
The first exothermic peak and the second exothermic peak are not particularly limited, but preferably have a difference of 30 to 80 ° C.

  First, by setting the first exothermic peak within the above range, the following effects can be exhibited. The temperature at which the insulating resin layer material is bonded to the inner layer circuit board, that is, the temperature at which the multilayer circuit board is usually manufactured by heating and pressing, or 0 to 50 ° C. lower than the first exothermic peak temperature. The curing reaction of the first curable resin can be efficiently advanced at the temperature. In addition, the progress of the curing reaction of the second curable resin can be substantially suppressed.

  Moreover, the following effects can be expressed by making a 2nd exothermic peak into the said range. After the insulating resin layer material is bonded to the inner layer circuit board, the outer layer circuit formed is heat-treated within a temperature range lower by 0 to 50 ° C. than the second exothermic peak temperature, thereby curing the second curable resin. Reaction can be advanced efficiently and the adhesiveness of an insulating resin layer and an outer layer circuit can be ensured. Moreover, since the conductor metal can be annealed, the stress strain when the outer layer circuit is formed by the conductor metal plating can be released together.

  Although it does not specifically limit as a form of the insulating resin layer material used in the said (a) process, For example, when manufacturing the sheet-like insulating resin layer material formed from a resin composition, it is excellent in handling property, and uses preferably. be able to.

  Here, the method for producing the sheet-like insulating resin layer material is not particularly limited. For example, a resin composition varnish prepared by dissolving and dispersing the resin composition in an organic solvent or the like is prepared, and a roll coater, a comma coater, or the like is prepared. Using a coating device, this is applied to a substrate serving as a carrier, the organic solvent contained in the resin composition varnish is substantially removed, and then the sheet-like insulation carried on the substrate A resin layer material can be obtained.

  Although it does not specifically limit as thickness of the sheet-like insulating resin layer material used here, It is preferable to set it as 15-100 micrometers. As a result, mechanical strength suitable for the handling of the insulating resin layer material can be imparted, and when manufacturing a multilayer printed wiring board using this, the irregularities of the inner circuit board can be filled, and necessary and sufficient insulation is achieved. The thickness of the resin layer can be ensured.

  Further, the surface shape of the sheet-like insulating resin layer material used here is not particularly limited, but it is preferable that unevenness is as small as possible on both the front and back sides.

In the step (a), the insulating resin layer material is laminated and integrated on the inner circuit board to form an insulating resin layer on the inner circuit board, but there is no particular limitation. A method of stacking and integrating the resin layer materials by heating and pressing them with a flat plate press device, a laminator device or the like can be preferably employed.

Here, the conditions for stacking and integration are not particularly limited. For example, in the case of using a flat plate press apparatus, a sheet-like insulating resin layer material is superposed on the inner circuit board, and this is preferably 80 to 180 ° C., 0 It can be carried out by heating and pressing at 5 to 4 MPa for 0.5 to 1.5 hours.
In the case of using a laminator device, the inner layer circuit board and the insulating resin layer material are overlapped, preferably heated and pressurized with a roll laminator at 70 to 100 ° C., and then bonded at 80 to 180 ° C. to 0.5 to 1 This can be done by heat treatment for a time.
As a result, the surface irregularities of the inner layer circuit board can be filled with the insulating resin layer material and molded, and the curing reaction of the first curable resin is efficiently advanced and firmly bonded onto the inner layer circuit board. An insulating resin layer can be formed.

Although it does not specifically limit as thickness of the insulating resin layer formed at the said (a) process, It is preferable to set it as 15-100 micrometers.
Thereby, while being able to set it as a highly reliable multilayer printed wiring board, the thickness of the whole multilayer printed wiring board can be restrained thinly.

  In addition, it is preferable that the surface form of the insulating resin layer formed on the surface of the inner circuit board in the step (a) is as small as possible. Thereby, a fine outer layer circuit with high smoothness can be formed.

Next, in the production method of the present invention,
(B) An uneven shape is formed on the outer surface of the insulating resin layer.

In the step (b), a minute uneven shape is formed on the outer surface of the insulating resin layer formed in the step (a).
Although this method is not particularly limited, for example, it is oxidized (desmeared) with potassium permanganate or the like, and the second curable resin component is dissolved from the outer surface portion of the insulating resin layer before the curing reaction. It is preferable that the removal is performed. Thereby, a minute uneven shape can be formed with high uniformity by a simple method, and the size (roughness) of the unevenness can be made suitable.

The roughness of the concavo-convex shape formed in the step (b) is not particularly limited, but Rmax (maximum height) measured by a contact-type surface roughness meter is 1 to 3 μm in accordance with JIS B 0601. Preferably there is.
Thereby, the smoothness of the outer layer circuit formed on this surface can be increased, and a fine outer layer circuit excellent in adhesion to the insulating resin layer and its uniformity can be formed.

Next, in the production method of the present invention,
(C) An outer layer circuit is formed on the irregular surface of the formed insulating resin layer.

In the step (c), the method of forming the outer layer circuit on the concavo-convex shape surface of the insulating resin layer is not particularly limited, but can be performed by a commonly used electroless plating method or electrolytic plating method.
In addition, although it does not specifically limit as a conductor metal which forms an outer layer circuit here, Copper, nickel, tin, etc. can be used and copper can be used normally normally.

Next, in the production method of the present invention,
(D) Heat treatment is performed after forming the outer layer circuit.

Although it does not specifically limit as conditions at the time of heat-processing at the said (d) process, It is preferable to carry out at the temperature 0-50 degreeC lower than the said 2nd exothermic peak temperature. Moreover, although it does not specifically limit about time, it can carry out in 0.5 to 3 hours.
Thereby, the curing reaction of the second curable resin can be efficiently advanced, the adhesion between the insulating resin layer and the outer layer circuit can be enhanced, and the metal used for forming the outer layer circuit can be annealed. A multilayer printed wiring board having excellent reliability can be manufactured.

  In the manufacturing method of the present invention, the insulating resin layer material is laminated and integrated again on the outer layer circuit surface thus formed, and the same processing is repeated to build up, thereby further stacking layers. A multilayer printed wiring board can also be manufactured.

Next, the resin composition used for forming the insulating resin layer in the production method of the present invention will be described.
This resin composition contains a curable resin. Although it does not specifically limit as curable resin used here, For example, phenol novolak resins, such as a phenol novolak resin, a cresol novolak resin, a bisphenol A novolak resin, a phenol resin, such as a resol type phenol resin, bisphenol A epoxy resin, bisphenol Bisphenol type epoxy resin such as F epoxy resin, novolak type epoxy resin such as novolac epoxy resin and cresol novolak epoxy resin, epoxy resin such as biphenyl type epoxy resin, novolac type cyanate resin, bisphenol A type cyanate resin, bisphenol E type cyanate resin And cyanate resins such as bisphenol type cyanate resins such as bisphenol F type cyanate resins.

The resin composition used in the production method of the present invention has a first exothermic peak and a second exothermic peak located at a higher temperature in the differential scanning calorimetry.
The resin composition preferably contains a first curable resin that exhibits the first exothermic peak and a second curable resin that exhibits the second exothermic peak. .

First, the first curable resin will be described.
The first curable resin preferably contains a cyanate resin and / or a prepolymer thereof.
The method for obtaining the cyanate resin and / or its prepolymer is not particularly limited. For example, the cyanate resin can be obtained by reacting a cyanogen halide with a phenol and prepolymerizing it by a method such as heating as necessary. it can. Moreover, the commercial item prepared in this way can also be used.

  By using a cyanate resin and / or a prepolymer thereof as the first curable resin, the elastic modulus of the insulating resin layer can be improved. Cyanate resins (especially novolac-type cyanate resins) have a rigid chemical structure and are therefore excellent in heat resistance, have a small decrease in elastic modulus even above the glass transition temperature, and maintain a high elastic modulus even at high temperatures. Can do. Furthermore, since a functional group having a high polarizability such as a hydroxyl group is not generated by the curing reaction, the dielectric properties can be improved.

  Among the cyanate resins, it is preferable to contain a novolac-type cyanate resin represented by the following general formula (I). Thereby, in addition to the above effects, the glass transition temperature of the insulating resin layer can be further increased, and various properties and flame retardancy of the insulating resin layer after curing can be further improved.

The molecular weight of the novolak cyanate resin represented by the general formula (I) is not particularly limited, but the weight average molecular weight by GPC measurement is preferably 500 to 10,000, and more preferably 700 to 5,000. is there.
If the weight average molecular weight is less than the lower limit, the mechanical strength of the insulating resin layer material may be lowered. Moreover, when the said upper limit is exceeded, the elasticity modulus of an insulating resin layer material may become high and workability | operativity will fall, or melt viscosity may become high and a moldability may fall.

  The method for obtaining the novolac-type cyanate resin is not particularly limited. For example, the novolac-type cyanate resin can be obtained by reacting a novolac-type phenol resin with a cyanating reagent such as a halogenated cyanide compound. Moreover, the commercial item prepared in this way can also be used.

In addition, as said cyanate resin, what prepolymerized this can also be used. That is, a cyanate resin may be used alone, a cyanate resin having a different weight average molecular weight may be used in combination, or a cyanate resin and a prepolymer thereof may be used in combination.
Here, the prepolymer is usually obtained by, for example, trimerizing the cyanate resin by, for example, heating reaction, and is preferably used for adjusting the moldability and fluidity of the resin composition. It is.
Although it does not specifically limit as a prepolymer here, For example, what a trimerization rate is 20 to 50 weight% can be used. This trimerization rate can be determined using, for example, an infrared spectroscopic analyzer.

Although it does not specifically limit as content of 1st curable resin in the said resin composition, It is preferable that it is 10 to 50 weight% with respect to the whole resin composition, More preferably, it is 10 to 40 weight% .
Thereby, the inner layer circuit board and the insulating resin layer can be firmly bonded.

Moreover, when using cyanate resin as 1st curable resin in the said resin composition, it is although it does not specifically limit as the content, It is preferable that it is 10 to 40 weight% with respect to the whole resin composition, Furthermore, Preferably it is 15 to 35% by weight.
When the content of the cyanate resin is less than the above lower limit, the effect may not be sufficient when the insulating resin layer is given heat resistance or low thermal expansion. Moreover, since the crosslinking density by cyanate resin will become high and the free volume will increase when the said upper limit is exceeded, the moisture resistance as an insulating resin layer may fall.

Next, the second curable resin will be described.
The second curable resin preferably contains an epoxy resin. Thereby, the film-forming property at the time of manufacturing a sheet-like insulating resin layer material and the adhesiveness to the inner layer circuit board can be improved.
Moreover, as an epoxy resin, it is preferable to contain the epoxy resin which does not contain a halogen atom substantially.

Such an epoxy resin is not particularly limited, and examples thereof include a phenol novolac type epoxy resin, a bisphenol type epoxy resin, a naphthalene type epoxy resin, and an arylalkylene type epoxy resin.
Among these, aryl alkylene type epoxy resins are preferable. Thereby, the moisture absorption solder heat resistance of a multilayer printed wiring board can further be improved. In addition to the above effects, flame resistance can be imparted to the insulating resin layer and the multilayer printed wiring board without using a halogen compound.

  Here, the aryl alkylene type epoxy resin refers to an epoxy resin having one or more aryl alkylene groups in the repeating unit, and examples thereof include a xylylene type epoxy resin and a biphenyl dimethylene type epoxy resin. Among these, a biphenyl dimethylene type epoxy resin represented by the following general formula (II) is preferable. Thereby, high flame retardance can be imparted to the insulating resin layer without using a halogen compound.

Although n of the biphenyl dimethylene type | mold epoxy resin represented by the said general formula (II) is not specifically limited, It is preferable that it is n = 1-10, More preferably, it is n = 2-5. Thereby, in the differential scanning calorimetry, the second exothermic peak can be expressed within a suitable temperature range.
When the number of n is less than the lower limit, the biphenyldimethylene type epoxy resin is easily crystallized, and the solubility in a general-purpose solvent is relatively lowered, which may make handling difficult. On the other hand, when the amount is larger than the above upper limit value, the fluidity of the resin is lowered, which may affect the film forming property when the sheet-like insulating resin layer material is produced.

  In addition, as an epoxy resin which does not contain a halogen atom substantially here, the content of the halogen atom in an epoxy resin can be 1 weight% or less, for example.

Although it does not specifically limit as content of 2nd curable resin in the said resin composition, It is preferable that it is 10 to 50 weight% with respect to the whole resin composition, More preferably, it is 15 to 45 weight% .
Thereby, the adhesiveness of an insulating resin layer and an outer layer circuit can be improved.

Further, the content in the case where the epoxy resin is used as the second curable resin in the resin composition is not particularly limited, but is preferably 10 to 50% by weight with respect to the entire resin composition. Preferably it is 15 to 35% by weight.
When the content of the epoxy resin is less than the above lower limit value, the adhesion between the inner circuit board and the insulating resin layer and the film forming property when producing a sheet-like insulating resin layer material may be affected. On the other hand, when the above upper limit is exceeded, the adhesion between the inner circuit board and the insulating resin layer may be insufficient or the chemical resistance may be lowered after the first curable resin is cured.

  In the resin composition used in the production method of the present invention, it is preferable to use, as a resin component, a phenoxy resin substantially free of halogen atoms in addition to the cyanate resin and the epoxy resin. Thereby, the film formability at the time of manufacturing a sheet-like insulating resin layer material can be further improved.

  Such a phenoxy resin is not particularly limited, and examples thereof include a phenoxy resin having a bisphenol skeleton, a phenoxy resin having a naphthalene skeleton, and a phenoxy resin having a biphenyl skeleton. Among these, bisphenol F type, bisphenol S type, and biphenyl type are preferable. Thereby, the flame retardance of a multilayer printed wiring board can be improved more.

  In addition, as a phenoxy resin which does not contain a halogen atom substantially here, what has the content of the halogen atom in a phenoxy resin is 1 weight% or less can be used, for example.

Although it does not specifically limit as molecular weight of the said phenoxy resin, It is preferable to use what the number average molecular weights by GPC measurement are 1,000-100,000. More preferably, it is 3,000-30,000.
If the number average molecular weight is less than the above lower limit, the effect of improving the film-forming property when producing a sheet-like insulating resin layer material may not be sufficient. If the number average molecular weight exceeds the above upper limit, the resin composition varnish may be used. The solubility of the phenoxy resin during preparation may decrease.

The content when the phenoxy resin is used as the resin component is not particularly limited, but is preferably 3 to 20% by weight, more preferably 5 to 15% by weight, based on the entire resin composition.
If the content of the phenoxy resin is less than the above lower limit, the effect of improving the film forming property when producing a sheet-like insulating resin layer material may be lowered. Moreover, when the said upper limit is exceeded, the low thermal expansibility of an insulating resin layer may fall.

Moreover, the resin composition used in the production method of the present invention can contain an inorganic filler in addition to the resin component such as the curable resin described above.
The inorganic filler is not particularly limited, for example, nitrides such as aluminum nitride, boron nitride, silicon nitride, talc, fired clay, unfired clay, mica, silicates such as glass, titanium oxide, alumina, silica, Oxides such as fused silica, carbonates such as calcium carbonate, magnesium carbonate and hydrotalcite, hydroxides such as aluminum hydroxide, magnesium hydroxide and calcium hydroxide, sulfates such as barium sulfate, calcium sulfate and calcium sulfite Alternatively, borates such as sulfite, zinc borate, barium metaborate, aluminum borate, calcium borate, sodium borate, and the like can be given.
Among these, silica is preferable. Furthermore, spherical silica is preferable, and spherical fused silica is particularly preferable. Thereby, the compounding quantity of the inorganic filler in a resin composition can be increased, and an insulating resin layer can be made especially low expansion. In addition, since the melt viscosity of the resin composition can be kept low by using spherical silica, the workability when producing the insulating resin layer material is excellent, and the moldability when producing the multilayer printed wiring board is improved. Can be improved.

  Although it does not specifically limit as a particle size of the said inorganic filler, It is preferable that an average particle diameter is 0.01-5 micrometers, More preferably, it is 0.2-2 micrometers. When the average particle size is less than the above lower limit, the viscosity of the resin composition varnish increases. When the average particle size exceeds the upper limit, sedimentation of the inorganic filler easily occurs in the resin composition varnish. However, workability may be reduced.

  When the inorganic filler is blended, the content of the inorganic filler in the resin composition is not particularly limited, but is preferably 20 to 70% by weight, more preferably 35 to 60% by weight of the entire resin composition. It is. When the content is less than the above lower limit, the effect may not be sufficient when the insulating resin layer has a high elastic modulus and a low thermal expansion coefficient. Moreover, when the said upper limit is exceeded, the moldability at the time of manufacturing a multilayer printed wiring board using an insulating resin layer material may fall by fluid fall.

Although it does not specifically limit in the resin composition used by this invention, When mix | blending an inorganic filler, it is preferable to contain a coupling agent further.
The coupling agent can improve the wettability of the interface between the curable resin and the inorganic filler, and can improve the heat resistance of the multilayer printed wiring board using the insulating resin layer, particularly the solder heat resistance after moisture absorption.

  The coupling agent used here is not particularly limited as long as it is usually used, but is selected from an epoxy silane coupling agent, a titanate coupling agent, an aminosilane coupling agent, and a silicone oil type coupling agent. It is preferred to use one or more coupling agents. Thereby, the wettability with the interface of the inorganic filler is improved, and the heat resistance can be further improved.

  Although content of a coupling agent is not specifically limited, It is preferable that it is 0.05-3 weight part with respect to 100 weight part of inorganic fillers, More preferably, it is 0.1-2 weight part. If the content is less than the above lower limit, the inorganic filler cannot be sufficiently covered, and the effect of improving the heat resistance of the multilayer printed wiring board may be reduced. On the other hand, when the above upper limit is exceeded, the bending strength of the insulating resin layer material or the multilayer printed wiring board may decrease.

In the resin composition used in the production method of the present invention, a curing catalyst can be used to accelerate the curing reaction of the curable resin.
Curing catalysts in the case of using a cyanate resin as the curable resin include, for example, tertiary amines such as triethylamine, tributylamine, quinoline, and isoquinoline, quaternary ammonium salts such as tetraethylammonium chloride and tetrabutylammonium bromide, phenol, and nonylphenol. , Catechol, pyrogal, aromatic hydroxy compounds represented by dihydroxynaphthalene, 2-methylimidazole, 2-phenylimidazole, 2-phenyl-4-methylimidazole, bis (2-ethyl-4-methyl-imidazole), 2- Phenyl-4-methyl-5-hydroxymethylimidazole, 2-phenyl-4,5-dihydroxymethylimidazole, 2-ethyl-4-methylimidazole, 2-undecylimidazole, 1-cyanoethyl 2-methylimidazole, 1-cyanoethyl-2-phenylimidazole, 1-cyanoethyl-2-ethyl-4-methylimidazole, 1-aminoethyl-2-methylimidazole, 1- (cyanoethylaminoethyl) -2-methylimidazole, Examples include imidazoles represented by 1-cyanoethyl-2-phenyl-4,5-bis (cyanoethoxymethylimidazole) or triazine addition type imidazole. Also, as a curing catalyst for cyanate resin, organic metal salts typified by zinc naphthenate, cobalt naphthenate, tin octylate, cobalt octylate, etc., copper acetylacetonate, aluminum acetylacetonate, cobalt acetylacetonate, etc. Organometallic complexes and the like. These may be used alone or in combination of two or more.

  Moreover, as a curing catalyst when using an epoxy resin as curable resin, a tertiary amine compound, an imidazole compound, a Lewis acid, etc. are mentioned, for example. These may be used alone or in combination of two or more.

In addition to this, the resin composition also includes a defoaming agent for preventing the generation of bubbles when manufacturing the sheet-like insulating resin layer material, and a liquid or powder difficulty for improving the flame retardancy of the multilayer printed wiring board. A thermoplastic resin or the like for improving the toughness and adhesion of the flame retardant and the insulating resin layer material and improving the handleability can also be added.
The thermoplastic resin used here is not particularly limited, and examples thereof include polyamide resins, polyester resins, polyimide resins, polyurethane resins, polystyrene resins, acrylic resins, and silicone resins.

  The reason why a highly reliable multilayer printed wiring board can be manufactured by manufacturing a multilayer printed wiring board by the manufacturing method of the present invention is considered as follows.

The insulating resin layer material used in the production method of the present invention is composed of a resin composition containing a curable resin, and in the differential scanning calorimetry, the first exothermic peak and the second temperature located at a higher temperature than this. It has an exothermic peak.
The insulating resin layer material is laminated and integrated on the inner layer circuit board on which the inner layer conductor circuit is formed in advance, thereby performing the curing reaction of the first curable resin and firmly bonding to the inner layer circuit board. A resin layer can be formed.
Next, the second curable resin component that is present on the outer surface of the formed insulating resin layer and is substantially uncured at this stage is preferably removed by desmearing or the like to thereby remove the insulating resin layer. Fine irregularities can be formed on the surface side with high uniformity.
Since the concavo-convex shape formed in this way is minute and there is substantially no large concavo-convex shape, a highly smooth outer layer circuit can be formed by attaching a conductive metal to the surface by plating or the like. . In addition, since the same profile as the minute uneven shape on the surface of the insulating resin layer is formed on the back surface side of the outer layer circuit, the adhesion between the insulating resin layer and the outer circuit can be ensured by the anchor effect, This adhesion strength can be made substantially constant regardless of the site where the outer layer circuit is formed.
Then, after the outer layer circuit is formed, the second curable resin can be cured and the outer layer circuit can be annealed by performing heat treatment preferably under a predetermined condition. As a result, the adhesion between the outer layer circuit and the insulating resin layer can be improved, and this can be stabilized by the subsequent thermal history.
In this way, a highly reliable multilayer printed wiring board can be manufactured.

  Hereinafter, the present invention will be described in detail with reference to Examples and Comparative Examples.

The raw materials used in Examples and Comparative Examples are as follows.
(1) Cyanate resin A / Novolac type cyanate resin: “Primaset PT-30” manufactured by Lonza Corporation, weight average molecular weight 700
(2) Cyanate Resin B / Novolac Cyanate Resin B: “Primaset PT-60” manufactured by Lonza Corporation, weight average molecular weight 2600
(3) Epoxy resin A / biphenyl dimethylene type epoxy resin: Nippon Kayaku Co., Ltd. “NC-3000P”, epoxy equivalent 275
(4) Epoxy resin B / bisphenol F type epoxy resin: “RE-404S” manufactured by Nippon Kayaku Co., Ltd., epoxy equivalent 165
(5) Phenoxy resin / bisphenol F type phenoxy resin: “Epicoat 4010P” manufactured by Japan Epoxy Resin Co., Ltd., number average molecular weight 6000
(6) Curing catalyst / imidazole compound: “2-phenyl-4,5-dihydroxymethylimidazole” manufactured by Shikoku Kasei Kogyo Co., Ltd.
(7) Inorganic filler / spherical fused silica: manufactured by Admatechs Co., Ltd. “SO-25H”, average particle size 0.5 μm
(8) Coupling agent / epoxysilane coupling agent: Nippon Unicar Co., Ltd. “A-187”

<Example 1>
1. Preparation of Resin Composition Varnish As the first curable resin, 14.5 parts by weight of cyanate resin A and 10 parts by weight of cyanate resin B were used. As the second curable resin, 35 parts by weight of epoxy resin A was used. This was mixed with 0.5 part by weight of a curing catalyst and dissolved and dispersed in methyl ethyl ketone.
Furthermore, 39.8 parts by weight of an inorganic filler and 0.2 parts by weight of a coupling agent were added and stirred for 10 minutes using a high-speed stirring device to obtain a resin composition varnish having a solid content of 60% by weight.

2. Production of Insulating Resin Layer Material Using a 25 μm thick polyethylene terephthalate (PET) film as a base material, the above-mentioned resin composition varnish is used in a comma coater device so that the insulating resin layer material thickness after drying is 50 μm. It was coated and dried at 150 ° C. for 5 minutes to obtain an insulating resin layer material with a substrate.

3. Production of Multilayer Printed Wiring Board By the following steps (1) to (5), the insulating resin layer material obtained above was laminated on both sides of the inner circuit board to obtain a four-layer multilayer printed wiring board.
(1) Insulating resin obtained above on the front and back of an inner layer circuit board (copper foil thickness 18 μm, L / S = 100/100 μm, clearance holes 1 mmφ, 3 mmφ, slit 2 mm) on which both predetermined inner layer circuits are formed Layer materials are stacked one by one, and this is roll laminated at 80 ° C. using a vacuum laminator (HLM-V570, manufactured by Hitachi Chemical Co., Ltd.), and then heated for 30 minutes in a drier set at 150 ° C. for insulation. A resin layer was formed.
(2) Using a carbon dioxide gas laser, a via hole of 100 μm was formed, and after connecting the inner and outer layers, the substrate was peeled from the insulating resin layer with the substrate.
(3) The surface of the insulating resin layer formed on the inner layer circuit board was desmeared in the following steps to form minute irregularities on the surface of the insulating resin layer.
(A) Swelling: 80 ° C./10 minutes (manufactured by Shipley, “MLB-211”)
(I) Roughening: 80 ° C./10 minutes (manufactured by Shipley, “Promoter 213A, 213B”)
(C) Neutralization: 50 ° C./10 minutes (manufactured by Shipley Co., Ltd., “New Trizer 216”)
(4) Copper plating was performed on the concavo-convex surface formed in (3) above to form a predetermined outer layer circuit (circuit thickness 20 μm, L / S = 50/50 μm).
(5) A heat treatment was performed at a temperature of 200 ° C. for 60 minutes to prepare a four-layer multilayer printed wiring board having a predetermined conductor pattern.

<Example 2>
As the first curable resin, 15.5 parts by weight of cyanate resin A was used. As the second curable resin, 24 parts by weight of epoxy resin A was used. This was mixed with 0.5 part by weight of a curing catalyst and dissolved and dispersed in methyl ethyl ketone.
Furthermore, 59.7 parts by weight of an inorganic filler and 0.3 part by weight of a coupling agent were added and stirred for 10 minutes using a high-speed stirring device to obtain a resin composition varnish having a solid content of 60% by weight.
Using this resin composition varnish, an insulating resin layer material and a multilayer printed wiring board were obtained in the same manner as in Example 1.

<Example 3>
As the first curable resin, 24.5 parts by weight of cyanate resin A was used. As the second curable resin, 25 parts by weight of epoxy resin A was used. In addition, 10 parts by weight of phenoxy resin was used as the curable resin. This was mixed with 0.5 part by weight of a curing catalyst and dissolved and dispersed in methyl ethyl ketone.
Furthermore, 39.8 parts by weight of an inorganic filler and 0.2 parts by weight of a coupling agent were added and stirred for 10 minutes using a high-speed stirring device to obtain a resin composition varnish having a solid content of 60% by weight.
Using this resin composition varnish, an insulating resin layer material and a multilayer printed wiring board were obtained in the same manner as in Example 1.

<Example 4>
As the first curable resin, 10 parts by weight of cyanate resin A was used. As the second curable resin, 34.5 parts by weight of epoxy resin A was used. This was mixed with 0.5 part by weight of a curing catalyst and dissolved and dispersed in methyl ethyl ketone.
Furthermore, 54.7 parts by weight of an inorganic filler and 0.3 part by weight of a coupling agent were added and stirred for 10 minutes using a high-speed stirrer to obtain a resin composition varnish having a solid content of 60% by weight.
Using this resin composition varnish, an insulating resin layer material and a multilayer printed wiring board were obtained in the same manner as in Example 1.

<Example 5>
As the first curable resin, 19.5 parts by weight of cyanate resin A and 20 parts by weight of cyanate resin B were used. As the second curable resin, 20 parts by weight of epoxy resin A was used. This was mixed with 0.5 part by weight of a curing catalyst and dissolved and dispersed in methyl ethyl ketone.
Furthermore, 39.8 parts by weight of an inorganic filler and 0.2 parts by weight of a coupling agent were added and stirred for 10 minutes using a high-speed stirring device to obtain a resin composition varnish having a solid content of 60% by weight.
Using this resin composition varnish, an insulating resin layer material and a multilayer printed wiring board were obtained in the same manner as in Example 1.

<Example 6>
As the first curable resin, 24.5 parts by weight of cyanate resin A was used. As the second curable resin, 20 parts by weight of epoxy resin A was used. This was mixed with 0.5 part by weight of a curing catalyst and dissolved and dispersed in methyl ethyl ketone.
Furthermore, 54.7 parts by weight of an inorganic filler and 0.3 part by weight of a coupling agent were added and stirred for 10 minutes using a high-speed stirrer to obtain a resin composition varnish having a solid content of 60% by weight.
Using this resin composition varnish, an insulating resin layer material and a multilayer printed wiring board were obtained in the same manner as in Example 1.

<Example 7>
As the first curable resin, 19.5 parts by weight of cyanate resin A was used. As the second curable resin, 45 parts by weight of epoxy resin A was used. This was mixed with 0.5 part by weight of a curing catalyst and dissolved and dispersed in methyl ethyl ketone.
Furthermore, 34.8 parts by weight of an inorganic filler and 0.2 part by weight of a coupling agent were added and stirred for 10 minutes using a high speed stirring device to obtain a resin composition varnish having a solid content of 60% by weight.
Using this resin composition varnish, an insulating resin layer material and a multilayer printed wiring board were obtained in the same manner as in Example 1.

<Comparative Example 1>
20 parts by weight of epoxy resin B, 48 parts by weight of phenoxy resin, and 2 parts by weight of curing catalyst were blended and dissolved and dispersed in methyl ethyl ketone.
Furthermore, 29.8 parts by weight of an inorganic filler and 0.2 part by weight of a coupling agent were added and stirred for 10 minutes using a high speed stirring device to obtain a resin composition varnish.
Using this resin composition varnish, an insulating resin layer material and a multilayer printed wiring board were obtained in the same manner as in Example 1.

<Comparative example 2>
25 parts by weight of epoxy resin A, 20 parts by weight of epoxy resin B, 23 parts by weight of phenoxy resin, and 2 parts by weight of a curing catalyst were blended and dissolved and dispersed in methyl ethyl ketone.
Furthermore, 29.8 parts by weight of an inorganic filler and 0.2 part by weight of a coupling agent were added and stirred for 10 minutes using a high speed stirring device to obtain a resin composition varnish.
Using this resin composition varnish, an insulating resin layer material and a multilayer printed wiring board were obtained in the same manner as in Example 1.

<Comparative Example 3>
24.5 parts by weight of cyanate resin A, 25 parts by weight of cyanate resin B, 10 parts by weight of phenoxy resin, and 0.5 parts by weight of a curing catalyst were blended and dissolved and dispersed in methyl ethyl ketone.
Furthermore, 39.8 parts by weight of an inorganic filler and 0.2 part by weight of a coupling agent were added and stirred for 10 minutes using a high speed stirring device to obtain a resin composition varnish.
Using this resin composition varnish, an insulating resin layer material and a multilayer printed wiring board were obtained in the same manner as in Example 1.

  The following evaluation was performed by the following methods for the insulating resin layer materials and multilayer printed wiring boards obtained in the examples and comparative examples. The obtained results are shown in Table 1.

1. Evaluation Method for Insulating Resin Layer Material (1) Differential Scanning Calorimetry Analysis Using a differential scanning calorimeter (TA Instruments), the temperature rising rate was 10 ° C./min. The DSC curve when analyzing the insulating resin layer material obtained in Example 1 is shown in FIG. 1, and the DSC curve when analyzing the insulating resin layer material obtained in Comparative Example 1 is shown in FIG.
From the DSC curve, the temperature showing the first and second exothermic peaks was read for the examples. Since the comparative example had one exothermic peak, the temperature indicating the peak was read.

(2) Thermal elastic modulus, glass transition temperature 18 μm thick copper foil was laminated on both sides of one insulating resin layer material, and heated for 90 minutes at a pressure of 2.5 MPa and a temperature of 200 ° C. with a vacuum press. After performing the pressure molding, the copper foil was entirely etched away on both sides to obtain a cured product of the insulating resin layer material.
A 5 × 25 mm sample was prepared from the cured product of the obtained insulating resin layer material. This was heated at 5 ° C./min by a DMA apparatus (manufactured by TA Instruments), the storage elastic moduli at 200 ° C. and 250 ° C. were measured, and the peak position of tan δ was defined as the glass transition temperature.

(3) Linear expansion coefficient A 4 x 20 mm sample was prepared from the cured product of the insulating resin layer material obtained in (2) above. Using this, it heated up at 10 degree-C / min with the TMA apparatus (made by TA Instruments), and measured the thermal expansion coefficient of 50-150 degreeC.

(4) Tensile strength A sample of 12.5 × 190 mm was prepared from the cured product of the insulating resin layer material obtained in (2) above. Using this, it was carried out at a test speed of 50 mm / min according to JIS K 7161.

(5) Dielectric constant, dielectric loss tangent Insulating resin layer material is laminated so that the thickness after heat and pressure molding is 1 mm, 18 μm thick copper foil is laminated on both sides thereof, and a vacuum press apparatus is used. After performing heat and pressure molding at a pressure of 2.5 MPa and a temperature of 200 ° C. for 90 minutes, the copper foil was entirely etched away on both sides to obtain a cured product of an insulating resin layer material.
Samples of 97 × 25 mm, 53 × 25 mm, and 37 × 25 mm were prepared from the obtained cured product of the insulating resin layer material. Using this, measurement was performed by the triplate line resonance method.

2. Evaluation of multilayer printed wiring board (1) Surface roughness (when manufacturing outer layer circuit)
After forming minute irregularities on the surface of the insulating resin layer formed on the inner circuit board, the surface roughness of this surface is measured with a contact surface roughness meter in accordance with JIS B 0601, and the reference length Rmax (maximum height) at 8 mm and Ra (average roughness) are displayed.

(2) Formability The multilayer printed wiring board was visually observed to check for the presence of molding voids.

(3) Shape of outer layer circuit The outer layer circuit formed on the multilayer printed wiring board was observed. The symbols are as follows.
◯: Good with no peeling of the 50 μm width circuit.
×: Partial peeling of the 50 μm wide circuit occurred.

(4) Peeling strength of outer layer circuit The peeling strength of the outer layer circuit (10 mm width) of the multilayer printed wiring board was measured in accordance with JIS K 6911 at five locations, and the average value was calculated.

(5) Hygroscopic solder heat resistance A 50 × 50 mm sample was prepared from a multilayer printed wiring board. This was treated with a pressure cooker at 125 ° C. for 2 hours and then immersed in a solder layer at 260 ° C. for 180 seconds to observe the presence or absence of blistering or peeling.

Examples 1 to 7 are obtained by the manufacturing method of the present invention using an insulating resin layer material having a first exothermic peak and a second exothermic peak located at a higher temperature in the differential scanning calorimetry. The multilayer printed wiring board thus obtained was excellent in surface smoothness on the outer layer circuit formation surface and had a sufficient level of peeling strength of the outer layer circuit, and was stable.
On the other hand, all the comparative examples used the insulating resin layer material having only one exothermic peak in the differential scanning calorimetry, but in Comparative Examples 1 and 2, the insulating resin layer had a low Tg and the thermal elastic modulus was It was not possible to measure. Then, when the outer layer circuit formation surface was roughened, the roughening progressed to the entire surface, so that only uneven and large irregularities could be formed, and the surface roughness increased. And the peeling strength of the formed outer layer circuit was lowered, and peeling occurred in a part of the circuit. In Comparative Example 3, since the insulating resin layer was substantially completely cured when the outer layer circuit was formed, the roughening treatment could not be performed and the outer layer circuit could not be formed.

The manufacturing method of the present invention can be suitably used for manufacturing a multilayer printed wiring board that can cope with fine pitch and high density wiring.
And the multilayer printed wiring board obtained by the manufacturing method of this invention can be used suitably as a multilayer printed wiring wiring board which can respond to such high-density integration and high-density mounting.

DSC curve when the insulating resin layer material obtained in Example 1 was analyzed DSC curve when the insulating resin layer material obtained in Comparative Example 1 was analyzed

Claims (7)

A method of manufacturing a multilayer printed wiring board by forming an insulating resin layer on the surface of an inner layer circuit board on which an inner layer conductor circuit has been formed in advance, and forming an outer layer conductor circuit on the outer surface of the insulating resin layer,
(A) Insulating resin layer material formed from a resin composition containing a curable resin and having a first exothermic peak and a second exothermic peak located at a higher temperature in differential scanning calorimetry, A step of stacking and integrating on the inner layer circuit board to form an insulating resin layer on the inner layer circuit board;
(B) forming an uneven shape on the outer surface of the insulating resin layer;
(C) forming an outer layer conductor circuit on the formed concavo-convex shape surface; and
(D) a step of performing a heat treatment after forming the outer layer conductor circuit;
A method for producing a multilayer printed wiring board, comprising: In the step (a), the insulating resin layer material includes a first curable resin that exhibits the first exothermic peak and a second curable resin that exhibits the second exothermic peak as a curable resin. The method for producing a multilayer printed wiring board according to claim 1, comprising a resin. The manufacturing method of the multilayer printed wiring board of Claim 1 or 2 which substantially performs hardening reaction of the said 1st curable resin in the said (a) process. In the step (b), a concavo-convex shape is formed on the outer surface of the insulating resin layer by removing the second curable resin component from the outer surface portion of the insulating resin layer by a desmear treatment before the curing reaction. The manufacturing method of the multilayer printed wiring board in any one of Claim 1 thru | or 3. The manufacturing method of the multilayer printed wiring board in any one of Claim 1 thru | or 4 which substantially performs hardening reaction of said 2nd curable resin in said (d) process. The method for manufacturing a multilayer printed wiring board according to claim 1, wherein the first exothermic peak is in a range of 120 to 200 ° C. 6. The method for producing a multilayer printed wiring board according to any one of claims 1 to 6, wherein the second exothermic peak is in a range of 150 to 250 ° C.

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