JP3343330B2 - Method for producing insulating varnish, insulating varnish obtained by this method, and multilayer printed wiring board using this insulating varnish - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an insulating varnish for a multilayer printed wiring board excellent in high density, a method for manufacturing the same, and a multilayer printed wiring board using the same.

[0002]

2. Description of the Related Art A printed wiring board is usually obtained by laminating a copper foil and a prepreg, and performing circuit processing on a copper-clad laminate obtained by hot pressing. Further, a multilayer printed wiring board was obtained by hot-pressing these printed wiring boards via a prepreg, or by hot-pressing these printed wiring boards and copper foil through a prepreg and integrating them. It is obtained by forming a circuit on the surface of a multilayer copper-clad laminate containing an inner layer circuit.

Conventionally, as a prepreg for a printed wiring board, a glass cloth prepreg obtained by impregnating and drying a glass cloth with a resin to make the resin semi-cured is used. Also,
In the multilayer printed wiring board, in addition to the glass cloth printed wiring board, an adhesive film in a semi-cured state of a resin having a film forming ability, which is a prepreg that does not use glass cloth, is disclosed in JP-A-6-200216, JP-A-6
No. 242465 discloses an adhesive film with a copper foil in which the adhesive film is formed on one side of a copper foil.
It is disclosed in 196,862. The film forming ability here means that during the steps of transporting, cutting, and laminating the prepreg, troubles such as cracking or chipping of the resin are unlikely to occur. It means performance that is unlikely to cause troubles such as abnormal thinning, reduction in interlayer insulation resistance and short circuit.

[0004]

In recent years, electronic devices have been reduced in size, weight, performance, and cost, and printed wiring boards have been required to have higher density, thinner, higher reliability, and lower cost. Has been requested. For high density, fine wiring is required, and for that purpose, the surface must have good flatness and good dimensional stability. Finer through holes and interstitial via holes (IVH)
It is required that drill workability and laser hole workability are good.

[0005] In order to improve the flatness of the surface, it is necessary to increase the fluidity of the resin at the time of multilayer lamination molding. For this purpose, it is desirable to use a thermosetting resin such as an epoxy resin. The resin exhibits high fluidity due to its low molecular weight before molding, but does not have the property of forming a sheet-like insulating material. Therefore, conventionally, a prepreg in which a reinforcing base material such as a glass cloth is impregnated with an insulating resin has been prepared in advance and used for the insulating layer. However, at present, the glass cloth generally used for prepregs has a larger gap between yarns (glass fiber bundles) as its thickness becomes thinner. For this reason, the thinner the cloth, the more the curling (the phenomenon that the yarn is bent or the warp and the weft, which should intersect at right angles, intersect at right angles rather than at right angles) is more likely to occur. Due to this bending, abnormal dimensional changes and warpage tend to occur after hot pressing. Furthermore, the thinner the glass cloth, the larger the gap between the yarns, the lower the volume fraction of the fibers of the prepreg, and the lower the rigidity of the interlayer insulating layer, and the higher the deflection in the component mounting process after processing the outer layer circuit. Is a problem that tends to be large. At present, the thinnest glass cloth generally used is a 30 μm cloth, and the thickness of a prepreg using the cloth is about 40 μm. If the resin content is reduced in order to further reduce the thickness of the prepreg, the ability to fill holes in the unevenness of the inner layer circuit with the resin is reduced, and voids are generated. Further, if the glass cloth is made thinner than this, the strength of the cloth itself is reduced, so that the glass cloth is easily broken in the step of impregnating the glass cloth with a resin, and it becomes difficult to manufacture a prepreg. In addition, multilayer printed wiring boards manufactured using prepregs using these glass cloths are apt to be misaligned due to unevenly distributed glass cloth during small-diameter drilling, and are easy to break the drill. There are problems such as poor drilling property, unevenness of the inner layer circuit easily appearing on the surface, and poor surface flatness.

On the other hand, an adhesive film which is a prepreg without a glass cloth or an adhesive film with a copper foil can be made thinner, and is excellent in small diameter drilling property, laser hole processing property and surface flatness. However, the multilayer printed wiring boards made with these prepregs have extremely low rigidity because the outer insulating layer does not have a glass cloth base material. This low rigidity is extremely remarkable at high temperatures, and it is easy to bend in the component mounting process, the wire bonding property is low, and the outer insulating layer has no glass cloth base material and the coefficient of thermal expansion is large, so mounting There are many problems, such as a large difference in thermal expansion from the component, low reliability of connection with the mounted component, and easy cracking and breakage at the solder connection due to thermal expansion and contraction during heating and cooling.

Therefore, a base material such as glass cloth is used as a new insulating material for solving the problems of high density, thinness, high reliability, and low cost for a multilayer printed wiring board that cannot be solved by a conventional prepreg. A sheet-like insulating material obtained by casting a varnish obtained by dispersing an electrically insulating whisker for keeping a shape on a carrier substrate without containing the same has been proposed and developed. However, in order to disperse the electrically insulating whisker in the insulating resin, special kneading equipment is required or the surface treatment of the electrically insulating whisker needs to be appropriately performed. Insufficient insulation may occur when the produced insulating material is used for a multilayer printed wiring board. This is because there is a portion where the electric insulating whisker is not properly dispersed in the insulating varnish, or there is a portion where the electric insulating whisker / resin interface (hereinafter, abbreviated as “interface”) has insufficient adhesiveness. This is because the diffusion of the moisture progresses and the elution of copper from the copper foil by the ionic impurities in the insulating layer may be promoted.

Usually, as a method of improving the adhesiveness and dispersibility of the interface of various fillers, there is a method of using a filler whose surface has been previously treated with a treating agent such as a coupling agent. Since the cost is high and the types of commercially available processing fillers are very limited, it has been difficult to select a processing filler suitable for various resin compounding systems. When the filler is treated, it is usually heated and dried after being immersed in a diluted solution of the treating agent or sprayed by a spray or the like, but in this drying step, the coupling agent is oligomerized on the surface of the treated filler. The problem of forming a physical adsorption layer and the problem that the filler agglomerates and therefore needs to be finely pulverized at the time of blending into a varnish or the like, so that the surface of the filler leaves an uneven treatment layer. In some cases, the physical adsorption layer and the non-uniform processing layer reduce the adhesiveness of the interface when the laminate is used.

As a solution to this problem, a method of directly adding a coupling agent at the time of compounding a varnish is disclosed in Japanese Patent Application Laid-Open No. 61-2722.
In this method, although the resin is preliminarily compounded, the varnish has a high viscosity and can avoid agglomeration of the filler to some extent. However, there was a problem that the orientation could not be achieved, and sufficient interface adhesion could not be exhibited.

The present invention solves the above-mentioned problems of the prior art, and when producing an insulating varnish in which electric insulating whiskers are compounded, the electric insulating whiskers have a good dispersibility and a good appearance, so that a multilayer print can be obtained. An object of the present invention is to provide an insulating varnish in which the adhesiveness of an interface is improved when a wiring board is formed, and high reliability and a low coefficient of thermal expansion are exhibited.

[0011]

Manufacturing method of the insulating varnish of the present invention SUMMARY OF] includes an electrically insulating whiskers, siloxane repeat
Reacting with hydroxyl groups on the surface of the base material at the end with two or more repeating units
Silicone oligomer solution with one or more functional groups
The method is characterized in that a resin material is mixed with a solution comprising a solvent treatment liquid for treating the surface of the electrically insulating whisker.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION

(Treatment liquid) As the solvent treatment liquid of the present invention, a coupling agent solution can be used. Examples of such a coupling agent include a silane-based coupling agent and a titanate-based coupling agent.
Generally, there are an epoxy silane type, an amino silane type, a cationic silane type, a vinyl silane type, an acryl silane type, a mercapto silane type and a composite type thereof. Any number of additives may be used in combination, and the amount of the additives is not particularly limited.

In the present invention, a silicone oligomer can be used in place of a conventional coupling agent for the purpose of expressing better interfacial adhesion. As a silicone oligomer, there are two or more siloxane repeating units,
There is no particular limitation on the molecular weight, skeleton and the like of the terminal as long as the terminal has at least one functional group that reacts with a hydroxyl group on the surface of the base material, but those having about 2 to 70 siloxane repeating units are preferable. When the siloxane repeating unit is large, uneven processing is likely to occur, and heat resistance is reduced. R ₂ SiO _2/2 , RSiO _3/2 , SiO of bifunctional, trifunctional, tetrafunctional siloxane units
_4/2 means the following structures, respectively. Here, R is the same or different organic group, and specific examples thereof include a methyl group, an ethyl group, a phenyl group, and a vinyl group. The functional group that reacts with the hydroxyl group on the surface of the base material of the silicone oligomer is not particularly limited, but an alkoxyl group or a silanol group is generally preferable. Further, the silicone oligomer preferably contains at least one kind of bifunctional, trifunctional or tetrafunctional siloxane unit in the molecule, and furthermore, the tetrafunctional siloxane unit has
More preferably, it is 15 mol% or more of the entire silicone oligomer. These silicone oligomers can be used in combination with the above-mentioned coupling agent and the like. There are no particular restrictions on the types used in combination and the amounts thereof.

In the present invention, a solvent is used to dilute these solutions. The solvent is not particularly limited and includes, for example, acetone, methyl ethyl ketone, toluene, xylene, methyl isobutyl ketone, ethyl acetate, ethylene glycol monomethyl ether, N, N-dimethylformamide, methanol, ethanol and the like. You may mix. The solids concentration of the solvent treatment liquid is not particularly limited and can be appropriately changed depending on the kind of treatment agent and the amount of the treatment agent attached to the filler, but is preferably in the range of 0.1% by weight to 50% by weight. When the amount is less than 1% by weight, the effect of the surface treatment is hardly exhibited, and when it exceeds 50% by weight, the heat resistance is apt to decrease.

(Whisker) The whisker used in the present invention is an electrically insulating ceramic whisker. Examples of the whisker include aluminum borate, wollastonite, potassium titanate, basic magnesium sulfate, silicon nitride and α. -At least one selected from alumina can be used. Among them, aluminum borate whiskers have a high modulus of elasticity, a low coefficient of thermal expansion, and are relatively inexpensive. A printed wiring board made using an insulating varnish using this aluminum borate whisker has higher rigidity at normal and high temperatures, a superior wire bonding property, and a higher electrical conductivity than a printed wiring board using a conventional glass cloth. Excellent signal transmission characteristics, low coefficient of thermal expansion, and excellent dimensional stability.

If the average diameter of the whiskers is less than 0.3 μm, mixing with the resin varnish becomes difficult and the coating workability deteriorates. If the average diameter exceeds 3 μm, the flatness of the surface is adversely affected and the whiskers are microscopically observed. Uniform dispersibility is impaired. Therefore, the average diameter of the whiskers is 0.3 μm
It is preferably in the range of ３3 μm. Furthermore, the average diameter is most preferably in the range of 0.5 μm to 1 μm for the same reason and good coatability (easy to apply smoothly). By selecting a whisker having such a diameter, a printed wiring board having more excellent surface flatness than using a prepreg using a conventional glass cloth as a base material can be obtained.

The average length of the whiskers is preferably at least 10 times the average diameter. If the ratio is less than 10 times, the reinforcing effect as a fiber becomes small, and at the same time, it becomes difficult to perform two-dimensional orientation in the resin layer of the whisker described later, so that sufficient rigidity cannot be obtained when the wiring board is used. However, when the whiskers are too long, it is difficult to uniformly disperse them in the varnish, and the coatability is reduced. Also, the probability that a whisker in contact with one conductor circuit comes into contact with another conductor circuit increases, and there is a possibility of causing an inter-circuit short circuit accident due to migration of copper ions that tend to move along the fiber. There's a problem. Therefore, the average length of the whiskers is preferably 50 μm or less. A printed wiring board manufactured using a varnish insulating material using whiskers of such a length has better migration resistance than a conventional printed wiring board using a prepreg based on glass cloth.

(Treatment Conditions) The present invention is characterized in that after a filler is treated in a solvent treatment solution, a resin material is blended as it is without a drying step to form a varnish. that time,
The treatment temperature and treatment time are not limited, and can be appropriately adjusted depending on the type and amount of the filler and the treatment agent, and the treatment is usually preferably performed at room temperature to 80 ° C. for 30 minutes or more.

(Resin) The resin used in the present invention is a resin used for a conventional prepreg based on a glass cloth and an adhesive film containing no glass cloth substrate or an adhesive film with a copper foil. Any thermosetting resin can be used. The term “resin” as used herein means a resin containing a resin, a curing agent, a curing accelerator, a coupling agent (if necessary), and a diluent (if necessary).

The resin used in the conventional prepreg based on glass cloth has no film-forming ability by itself, so it is formed as an adhesive layer on one side of a copper foil by coating, and the solvent is heated. When the resin is removed and semi-cured, troubles such as cracking or chipping of the resin are likely to occur during the transport, cutting, lamination, etc. process, or the interlayer insulating layer is abnormal due to the presence of the inner layer circuit during the subsequent hot pressing. Conventionally, it has been difficult to use it for an adhesive film with a copper foil because it is liable to cause troubles such as a decrease in interlayer insulation resistance and a short circuit. However, in the present invention, whiskers are dispersed in the resin, and the resin is reinforced by the whiskers.
During the processes such as cutting and lamination, troubles such as cracking or chipping of the resin hardly occur, and the occurrence of an abnormal thinning of the interlayer insulating layer during hot pressing due to the presence of whiskers can be prevented.

It is also effective to use a resin conventionally used for an adhesive film or an adhesive film with a copper foil. These resins have a film forming ability even when used alone by containing a high molecular weight component and the like.However, by dispersing whiskers in the resin according to the present invention, the film forming ability is further enhanced and the handleability is improved. In addition, the insulation reliability can be further improved. Further, by dispersing the whiskers, it is possible to reduce the amount of the high molecular weight component to be added by an amount corresponding to the enhancement of the film forming ability, thereby improving the heat resistance and adhesiveness of the resin in some cases.

As the type of the resin, for example, epoxy resin, bismaleimide triazine resin, polyimide resin,
Phenol resins, melamine resins, silicon resins, unsaturated polyester resins, cyanate ester resins, isocyanate resins, polyimide resins and various modified resins thereof are preferred. Among them, bismaleimide triazine resin and epoxy resin are particularly preferable in terms of printed wiring board characteristics. As the epoxy resin, bisphenol A
Epoxy resin, bisphenol F epoxy resin, bisphenol S epoxy resin, phenol novolak epoxy resin, cresol novolak epoxy resin, bisphenol A novolak epoxy resin, salicylaldehyde novolak epoxy resin, bisphenol F novolak epoxy resin, fat Cyclic epoxy resins, glycidyl ester type epoxy resins, glycidylamine type epoxy resins, hydantoin type epoxy resins, isocyanurate type epoxy resins, aliphatic cyclic epoxy resins and their halides, hydrogenated products, and mixtures of the above resins are preferred. It is. Among them, bisphenol A novolak type epoxy resin or salicylaldehyde novolak type epoxy resin is preferable because of its excellent heat resistance.

(Curing agent) As the curing agent for such a resin, those conventionally used can be used. When the resin is an epoxy resin, for example, dicyandiamide, bisphenol A, bisphenol F, polyvinyl phenol, phenol novolak resin, Bisphenol A novolak resins and halides and hydrides of these phenolic resins can be used. Among them, bisphenol A novolak resin is preferable because of its excellent heat resistance. The ratio of the curing agent to the resin may be a conventionally used ratio,
The amount is preferably in the range of 2 to 100 parts by weight with respect to 0 parts by weight, and further, in dicyandiamide, 2 to 5 parts by weight,
For other curing agents, the range is preferably 30 to 80 parts by weight.

(Curing Accelerator) When the resin is an epoxy resin, an imidazole compound, an organic phosphorus compound, a tertiary amine, a quaternary ammonium salt, or the like is used as the curing accelerator. The ratio of the curing accelerator to the resin may be a conventionally used ratio, and is based on 100 parts by weight of the resin.
The range is preferably 0.01 to 20 parts by weight, and 0.1 to 1 part by weight.
A range of 0 parts by weight is more preferred.

(Diluent) The thermosetting resin used in the present invention can be diluted with a solvent and used as a resin varnish. Solvents include acetone, methyl ethyl ketone, toluene, xylene, methyl isobutyl ketone, ethyl acetate, ethylene glycol monomethyl ether, methanol, ethanol, N, N-dimethylformamide, N, N
N-dimethylacetamide and the like can be used. The ratio of the diluent to the resin may be a conventionally used ratio, and is preferably in the range of 1 to 200 parts by weight, more preferably 30 to 100 parts by weight, per 100 parts by weight of the resin.

(Ion Scavenger) The ion scavenger used in the present invention includes an inorganic ion scavenger and an organic copper damage inhibitor. Inorganic ion scavengers are classified into inorganic ion exchangers that perform ion exchange by taking in ions of the opposite charge, and adsorbents that simply adsorb ions and the like, but some have both. The adsorbed substance of the ion-adsorbed inorganic substance is an inorganic substance that decomposes ions by performing mass transfer from a liquid or a solid using the adsorptivity of a porous solid, and is an inorganic substance such as a layered compound having excellent heat resistance and chemical resistance. Activated carbon, zeolite, synthetic zeolite, silica gel, activated alumina, activated clay, and the like. In order to increase the adsorption capacity, it is preferable to use a porous material or a fine powder that has been increased in specific surface area. In addition, hindered phenol-based Yoshinox BB (trade name, manufactured by Yoshitomi Pharmaceutical Co., Ltd.), triazole-based, and thiol-based Disnet DB (trade name, manufactured by Sankyo Pharmaceutical Co., Ltd.), etc., as organic copper damage inhibitors. It may be added. The amount of each of these additives should be 1 to 10 parts by weight, preferably 1 to 5 parts by weight, based on 100 parts by weight of the resin.
Addition of more than 10 parts by weight is not preferred because it causes problems such as a decrease in heat resistance and an increase in cost.

(Other Compounding Agents) In the present invention, conventionally known coupling agents, fillers, high molecular weight resins and the like may be appropriately compounded in the resin, if necessary, in addition to the above-mentioned components. Is also good.

(Proportion of Resin and Whisker) When the amount of the electrically insulating whisker in the resin is less than 5 parts by weight based on 100 parts by weight of the resin solid content, the resin is finely crushed and scattered at the time of cutting the prepreg. It becomes difficult to handle, for example, it becomes easy, and sufficient rigidity cannot be obtained when the wiring board is used. On the other hand, if the compounding amount of the whisker exceeds 350 parts by weight, the filling property of the inner layer circuit at the time of hot pressing and the filling property of the resin between the circuits are impaired, and the whisker composite resin layer after the hot pressing is voided or blurred. Is likely to occur, and the characteristics of the wiring board may be impaired. Therefore, the amount of the whisker is preferably 5 to 350 parts by weight based on 100 parts by weight of the resin solids. In addition, it has excellent fillability of the inner layer circuit and resin filling between the circuits, and the manufactured wiring board has the same or higher rigidity as compared to the wiring board manufactured using the prepreg using the conventional glass cloth. Due to the dimensional stability and wire bonding properties, the whisker content is 3 parts per 100 parts by weight of resin solids.
More preferably, the amount is 0 to 230 parts by weight.

(Kneading method) In order to improve the dispersibility of the insulating whisker, after preparing an insulating varnish, kneading with a mill, a three-roll mill or a bead mill can be performed in combination. After kneading, it is desirable to remove bubbles in the varnish by stirring and defoaming under reduced pressure.

(Carrier Film) In the present invention, the carrier film on which the whisker composite resin layer (B-stage state), which is an insulating layer, is formed on one surface thereof is a metal foil such as a copper foil or an aluminum foil, or a polyester film. , A polyimide film, or a film obtained by treating the surfaces of the metal foil and the film with a release agent.

(Whisker Orientation in Prepreg Layer) A whisker in an insulating material composed of the electrically insulating whisker of the present invention and a resin in a B-stage state is in a state close to two-dimensional orientation (whisker is in an axial direction). (A state close to parallel to the surface on which the material layer is formed). By orienting the whiskers in this way, the insulating material of the present invention can obtain good handleability and, at the same time, high rigidity, good dimensional stability and surface flatness when formed into a wiring board.

(Coating method) In order to orient the whiskers as described above, a whisker having a fiber length in the above-described preferred range is used, and at the same time, a blade is used when applying an insulating varnish in which whiskers are mixed with copper foil. A shear force can be applied in a direction parallel to the copper foil such as a coater, rod coater, knife coater, squeeze coater, reverse roll coater, transfer roll coater, or a compressive force can be applied in a direction perpendicular to the copper foil surface. What is necessary is just to adopt the coating method which can be performed.

(Function) According to the present invention described above, by mixing the resin material directly into the solution obtained by treating the surface of the electrically insulating whisker, there is no drying step after treating the filler. It is uniformly dispersed in the varnish without agglomeration or the like, a uniform treatment agent layer is formed on the whisker surface, and the compatibility with the resin is improved. Furthermore, the adhesiveness of the interface is improved, and high insulation reliability and low expansion coefficient are to be achieved when the insulating material obtained by combining the electrically insulating whiskers manufactured by the present method is used as a material for a multilayer printed wiring board. Can be. In addition, the insulating layer manufactured using the insulating material of the present invention has a better workability to the laser than glass and is a fine whisker, so that the insulating layer using the conventional glass cloth prepreg is not used. Difficult laser drilling can be done easily. Therefore, a diameter of 100 μm
The following small interstitial via holes (IV
H) can be easily manufactured, the circuit of the printed wiring board can be miniaturized, and it can greatly contribute to higher density and higher performance of electronic devices.

[0034]

【Example】

Example 1 A-187 (manufactured by Nippon Unicar Co., Ltd.) and methyl ethyl ketone, which are γ-glycidoxypropyltrimethoxysilane, were added as a silane coupling agent to a glass flask equipped with a stirrer, a condenser, and a thermometer. Thus, a treatment liquid having a solid content of 5% by weight was prepared. 60% by weight of aluminum borate whiskers having an average diameter of 0.8 μm and an average fiber length of 20 μm were added to this treatment liquid, and the mixture was stirred at room temperature for 1 hour to prepare a treatment filler-containing solution.

Example 2 In a glass flask equipped with a stirrer, a condenser and a thermometer, N-β- (N-vinylbenzylaminoethyl) -γ-aminopropyltrimethoxysilane.hydrochloride was used as a silane coupling agent. SZ-6032 (trade name, manufactured by Dow Corning Toray Silicone Co., Ltd.) and methyl ethyl ketone were added to prepare a treatment liquid having a solid content of 5% by weight. An aluminum borate whisker having an average diameter of 0.8 μm and an average fiber length of 20 μm was added to this treatment solution at 60% by weight.
After mixing and stirring at room temperature for 1 hour, a solution containing the treated filler was prepared.

Example 3 To a glass flask equipped with a stirrer, a condenser and a thermometer, KR46B (trade name, manufactured by Ajinomoto Co., Ltd.), which is isopropyl tris (dioctyl pyrophosphate) titanate, as a titanate coupling agent and methyl ethyl ketone were added. A treatment liquid having a solid content of 5% by weight was prepared. This treatment liquid has an average diameter of 0.8 μm and an average fiber length of 20.
An aluminum borate whisker of 60 μm was mixed and stirred at room temperature for 1 hour to prepare a solution containing a treated filler.

Example 4 A glass flask equipped with a stirrer, a condenser and a thermometer was charged with 40 g of tetramethoxysilane and 9 g of methanol.
0.47 g of acetic acid and 1 part of distilled water were added to the solution containing 3 g.
After mixing 8.9 g, the mixture was stirred at 50 ° C. for 8 hours to synthesize a silicone oligomer. The average of the siloxane repeating units of the obtained silicone oligomer was 20. Methyl ethyl ketone was added to the silicone oligomer solution to prepare a treatment liquid having a solid content of 5% by weight. 60% by weight of aluminum borate whisker having an average diameter of 0.8 μm and an average fiber length of 20 μm was added to the treatment liquid, and the mixture was stirred at room temperature for 1 hour.
A solution containing the treatment filler was prepared.

Example 5 As in Example 4, trimethoxymethylsilane was added to 40
g, 93 g of methanol in a solution containing 0.5 g of acetic acid.
After mixing 3 g and 15.8 g of distilled water, the mixture was stirred at 50 ° C. for 8 hours to synthesize a silicone oligomer. The average of the siloxane repeating units of the obtained silicone oligomer was 15. Methyl ethyl ketone was added to the silicone oligomer solution to prepare a treatment liquid having a solid content of 5% by weight. 60% by weight of aluminum borate whiskers having an average diameter of 0.8 μm and an average fiber length of 20 μm were added to this treatment liquid, and the mixture was stirred at room temperature for 1 hour to prepare a treatment filler-containing solution.

Example 6 As in Example 4, dimethoxydimethylsilane was added to 34
g, 8 g of tetramethoxysilane and 98 g of methanol
0.60 g of acetic acid and 14.0 g of distilled water were added to the blended solution.
After mixing g, the mixture was stirred at 50 ° C. for 8 hours to synthesize a silicone oligomer. The average of the siloxane repeating units of the obtained silicone oligomer was 28. Methyl ethyl ketone was added to the silicone oligomer solution to prepare a treatment liquid having a solid content of 3% by weight. 0.8 μm average diameter
m, an aluminum borate whisker having an average fiber length of 20 μm was blended at 60% by weight and stirred at room temperature for 1 hour to prepare a solution containing a treated filler.

Example 7 As in Example 4, dimethoxydimethylsilane was added to 20
g, 25 g of tetramethoxysilane and 10 g of methanol.
0.60 g of acetic acid and 1 part of distilled water were added to the solution containing 5 g.
After blending 7.8 g, the mixture was stirred at 50 ° C. for 8 hours to synthesize a silicone oligomer. The average of the siloxane repeating units of the obtained silicone oligomer was 30. Methyl ethyl ketone was added to the silicone oligomer solution to prepare a treatment liquid having a solid content of 5% by weight. 60% by weight of aluminum borate whisker having an average diameter of 0.8 μm and an average fiber length of 20 μm was added to the treatment liquid, and the mixture was stirred at room temperature for 1 hour.
A solution containing the treatment filler was prepared.

Example 8 As in Example 4, trimethoxymethylsilane was added to 20
g, 22 g of tetramethoxysilane, 98 g of methanol
acetic acid 0.52 g and distilled water 18.
After blending 3 g, the mixture was stirred at 50 ° C. for 8 hours to synthesize a silicone oligomer. The average of the siloxane repeating units of the obtained silicone oligomer was 25. Methyl ethyl ketone was added to the silicone oligomer solution to prepare a treatment liquid having a solid content of 5% by weight. This treatment liquid has an average diameter of 0.8
An aluminum borate whisker having an average fiber length of 20 μm was mixed at 60% by weight and stirred at room temperature for 1 hour to prepare a solution containing a treated filler.

Example 9 As in Example 4, dimethoxydimethylsilane was added to 10
g, 10 g of trimethoxymethylsilane, 20 g of tetramethoxysilane, and 93 g of methanol in a solution containing 0.52 g of acetic acid and 16.5 g of distilled water.
The mixture was stirred at 8 ° C. for 8 hours to synthesize a silicone oligomer. The average of the siloxane repeating units of the obtained silicone oligomer was 23. Methyl ethyl ketone was added to the silicone oligomer solution to prepare a treatment liquid having a solid content of 5% by weight. 60% by weight of aluminum borate whiskers having an average diameter of 0.8 μm and an average fiber length of 20 μm were added to this treatment liquid, and the mixture was stirred at room temperature for 1 hour to prepare a treatment filler-containing solution.

Example 10 As in Example 4, 0.34 g of acetic acid was added to a solution containing 40 g of tetraethoxysilane and 93 g of methanol.
After blending 13.8 g of distilled water, the mixture was stirred at 50 ° C. for 8 hours to synthesize a silicone oligomer. The average number of siloxane repeating units in the obtained silicone oligomer was 19. Methyl ethyl ketone was added to the silicone oligomer solution to prepare a treatment liquid having a solid content of 5% by weight. 60% by weight of aluminum borate whiskers having an average diameter of 0.8 μm and an average fiber length of 20 μm were added to this treatment liquid, and the mixture was stirred at room temperature for 1 hour to prepare a treatment filler-containing solution.

Example 11 A-187 (manufactured by Nippon Unicar Co., Ltd., trade name) and γ-glycidoxypropyltrimethoxysilane were used as the silane coupling agent in the silicone oligomer solution obtained in Example 4. In addition, solid content 5
% By weight (silicone oligomer: A-187 = 50: 5
The treatment liquid of 0) was prepared. This treatment liquid has an average diameter of 0.8
An aluminum borate whisker having an average fiber length of 20 μm was mixed at 60% by weight and stirred at room temperature for 1 hour to prepare a solution containing a treated filler.

Example 12 The silicone oligomer solution obtained in Example 4 was added to KR46B which is isopropyl tris (dioctyl pyrophosphate) titanate as a titanate coupling agent.
(Trade name, manufactured by Ajinomoto Co., Inc.) and methyl ethyl ketone, and solid content of 5% by weight (silicone oligomer: KR4
6B = 50: 50). 60% by weight of aluminum borate whiskers having an average diameter of 0.8 μm and an average fiber length of 20 μm were added to this treatment liquid, and the mixture was stirred at room temperature for 1 hour to prepare a treatment filler-containing solution.

(Varnish Resin Composition A) The solutions of Examples 1 to 12 were heated to 50 ° C., and the following resin was added to 300 parts by weight of this solution to prepare a varnish having a solid content of 75% by weight.・ Bisphenol A novolak epoxy resin 100 parts by weight (epoxy equivalent: 210) ・ Bisphenol A novolak resin 40 parts by weight (hydroxyl group)・ Equivalent: 123) ・ 4-brominated bisphenol A ・ ・ ・ ・ ・ ・ ・ ・ ・ 40 parts by weight (hydroxyl equivalent: 272) ・ Imidazole curing accelerator ・ ・ ・ ・ ・ ・ ・........... 0.5 parts by weight

(Varnish Resin Composition B) The solutions of Examples 1 to 12 were heated to 50 ° C., and to 400 parts by weight of the solution, 100 parts by weight of the following resin and methyl ethyl ketone were added to prepare a varnish having a solid content of 65% by weight. Produced.・ Bisphenol A novolak type epoxy resin ・ ・ ・ ・ ・ ・ ・ ・ ・ 100 parts by weight (epoxy equivalent: 210) ・ Brominated phenoxy resin ・ ・ ・ ・ ・ ・ ・ ・ ・70 parts by weight (epoxy equivalent: 12940) Bisphenol A novolak resin 40 parts by weight (hydroxyl equivalent: 123) 4-brominated bisphenol A 30 parts by weight (hydroxyl equivalent: 272) Imidazole-based curing accelerator 0.5 parts by weight

Comparative Example 1 As an electrically insulating whisker, an untreated untreated untreated whisker had an average diameter of 0.8 μm and an average fiber length of 20 μm.
A varnish was prepared in the same manner as in Example 1 using a μm aluminum borate whisker.

Comparative Example 2 The varnish of Comparative Example 1 was used as a silane coupling agent with γ-
A-1 which is glycidoxypropyltrimethoxysilane
87 (manufactured by Nippon Unicar Co., Ltd., 2 parts by weight).

Comparative Example 3 Instead of the silane coupling agent, an aluminum borate whisker having an average diameter of 0.8 μm and an average fiber length of 20 μm was prepared using KF101 (trade name, manufactured by Shin-Etsu Chemical Co., Ltd.) which is an epoxy-modified silicone oil. A varnish was prepared in the same manner as in Example 1 except for the treatment.

Comparative Example 4 As the silane coupling agent used in Example 1, γ-
A-1 which is glycidoxypropyltrimethoxysilane
87 (manufactured by Nippon Unicar Co., Ltd., trade name) was prepared with methanol at a solid content of 1% by weight, and untreated aluminum borate whiskers having an average diameter of 0.8 μm and an average fiber length of 20 μm were added at room temperature for 1 hour. After immersion and stirring, 1
After drying at 20 ° C. for 1 hour, a surface treatment was performed. Using this treated aluminum borate whisker, a varnish was produced in the same manner as in Example 1.

Comparative Example 5 The same thermosetting resin as that of Example 1 as a main component was impregnated and applied to glass cloths having a thickness of 50 μm and 100 μm.
The film is heated and dried at a temperature of 150 ° C. for 10 minutes to remove the solvent and semi-cured the resin. The thickness of the glass cloth and the semi-cured epoxy resin is 50 μm and 10 μm.
A 0 μm glass epoxy prepreg was prepared.

Comparative Example 6 A high-molecular-weight epoxy polymer having a weight-average molecular weight of 50,000 and a thermosetting resin having a film-form performance containing a bisphenol A type epoxy resin as a main component and a thickness of 18 μm were prepared.
It is made of an epoxy resin in a semi-cured state by coating a copper foil and a 50 μm-thick PET film with a knife coater, heating and drying at 150 ° C. for 10 minutes to remove the solvent and semi-cured the resin. Insulation layer thickness is 50
The insulating material with copper foil of μm and the PET are removed by peeling, and the thickness of the semi-cured epoxy resin is 50 μm.
m was prepared.

An insulating varnish prepared in each of Examples 1 to 12 and Comparative Examples 1 to 4 was coated with a copper foil having a thickness of 18 μm and a thickness of 50 μm.
m is coated on a polyethylene terephthalate (PET) film with a knife coater, dried by heating at a temperature of 150 ° C. for 10 minutes to remove the solvent, semi-cured, and whisker with a whisker volume fraction of 30%. The thickness of the insulating layer made of epoxy resin in a semi-cured state is 50μ.
The insulating material with a copper foil of m and 100 μm and the PET were removed by peeling to produce an insulating material having a thickness of 50 μm and made of a semi-cured epoxy resin.

The following items were evaluated with respect to the produced insulating material. (B-stage film handleability) The handleability was evaluated as "O" when the material could be cut cleanly by a cutter knife and a shear without scattering of resin, and no blocking occurred between insulating materials.

(Cured Product Characteristics) The insulating material with a copper foil having a thickness of 50 μm prepared above was laminated and laminated so that the insulating layers faced each other, and was subjected to hot pressing. After the molding, the copper foil portion was removed by etching to obtain a target resin plate. The elastic modulus and the coefficient of thermal expansion of this resin plate were measured. The elastic modulus is TM
In the tensile mode of A, the coefficient of thermal expansion was measured in the tensile mode of TMA.

(Electro-corrosion resistance test) On a glass epoxy double-sided copper-clad laminate having a thickness of 0.8 mm, a pattern to be an electrode on the inner layer surface of the electro-corrosion test was formed by etching, and the upper and lower insulating layers were formed. An insulating material with a copper foil having a thickness of 50 μm was overlapped and laminated so that the insulating material was in contact with a pattern to be an electrode on the inner layer surface of the electrolytic corrosion test, and was subjected to hot pressing. An outer layer electrode pattern was formed by etching on a portion of the obtained laminated plate corresponding to the position of the inner layer electrode corrosion test pattern to obtain an electrolytic corrosion test piece. A voltage of 50 V was applied between the inner layer electrode and the outer layer electrode, and the insulation resistance value was measured after a lapse of 1000 hours in an atmosphere of 85 ° C. and 85% RH.
As a result of measuring the insulation resistance after 1000 hours, 10
Those showing good values of ⁹ Ω or more were evaluated as ○, and others were evaluated as ×.

(Surface Roughness) A 18 μm thick plate was placed above and below the prepared 100 μm thick glass base epoxy resin prepreg.
m single-sided roughened copper foil was laminated so that the roughened surface faced the insulating material, and hot-pressed. This copper-clad laminate is subjected to circuit processing, and the insulating material of the present invention having a thickness of 50 μm previously prepared on both surfaces thereof, and a single-sided roughened copper foil having a thickness of 18 μm on the outer surface thereof is further provided with a roughened surface as an insulating material. They were laminated so as to face each other, and were hot-pressed to produce a multilayer copper-clad laminate containing an inner circuit. The surface roughness of the multilayer copper-clad laminate containing the inner layer circuit was measured with a stylus type surface roughness meter. The measurement location was the outer layer surface on a straight line having a length of 25 mm including a portion with and without an inner layer circuit immediately below. When the 10-point average of the level difference between the portion having the inner layer circuit and the portion not having the inner layer circuit was 3 μm or less, it was evaluated as ○, and the others were evaluated as ×.

(Hot Reliability Test) A hole having a diameter of 75 μm was formed in a predetermined position of the surface copper foil of the multilayer copper-clad laminate containing an inner layer circuit by etching, and the hole was subjected to an impact laser manufactured by Sumitomo Heavy Industries, Ltd. Drilling was performed, desmearing was performed by permanganate treatment, electroless plating was performed, and a circuit was formed by pattern baking etching. The insulating material of the present invention having a thickness of 50 μm is again laminated on both sides of the multilayer printed wiring board, and a single-sided roughened copper foil having a thickness of 18 μm is further laminated on the outer side thereof so that the roughened surface faces the insulating material. A multilayer copper-clad laminate with an inner layer circuit is formed, and a hole having a diameter of 75 μm is formed at a predetermined position by etching, and the hole is formed with an impact laser manufactured by Sumitomo Heavy Industries, Ltd., and treated with permanganate. After performing desmearing and electroless plating, a circuit was formed by pattern baking etching. The above steps were repeated to produce a 10-layer printed wiring board. At this time, those that can be drilled by the laser were rated as ○, and others were rated as x. A bare chip was mounted on a part of the 10-layer printed wiring board and connected to a surface circuit by wire bonding. The wire bonding conditions were as follows: ultrasonic output was 1 W, ultrasonic output time was 50 μs, bond load was 100 g, and wire bonding temperature was 180 ° C. did. Also, a TSOP having a size of 8 × 20 mm was connected to the surface circuit via solder to this 10-layer printed wiring board, and the TSOP mounting board was heated to −65 ° C.
→ Evaluated in a heat cycle test at 150 ° C., a sample in which no defect such as disconnection occurred in the solder connection even after 2,000 cycles was evaluated as ○, and other samples were evaluated as ×. Further, a circuit including an interstitial via hole inside the substrate was subjected to a continuity test, and no trouble such as disconnection occurred. From the above results,
The results are shown in Tables 1 and 2.

[0060]

[Table 1]

[0061]

[Table 2] The following can be understood from the above results. Examples 1 to 12
Achieves a low coefficient of thermal expansion and high corrosion resistance without lowering the properties of the laminate as compared with the case where no treatment is performed.

The insulating varnish of the present invention is obtained by directly mixing a resin material with a solvent treatment liquid containing whiskers obtained by treating the surface of an electrically insulating whisker to form a resin varnish.
The dispersibility of the whiskers and the adhesive strength at the interface can be improved, and the multilayer printed wiring board using an insulating material obtained by combining the electrically insulating whiskers can have a low coefficient of thermal expansion and high insulation reliability. The insulating material obtained by using the insulating varnish manufactured according to the present invention is a material in which an epoxy resin can be formed into a sheet by adding an electrically insulating whisker, and a printed wiring board using this is: The surface is flat, the circuit workability is good, the rigidity is high, the mounting reliability is high, and the thermal expansion coefficient is small, so the dimensional stability is improved.

[0063]

As described above, according to the present invention, a method of manufacturing an insulating varnish for a multilayer printed wiring board excellent in high density, thinning, high reliability, and low cost, and a method for manufacturing the same. It is possible to provide a manufactured insulating varnish and a multilayer printed wiring board using the insulating varnish.

────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁷ Identification code FI C09D 183/04 C09D 183/04 H05K 3/46 H05K 3/46 GT (72) Inventor Takata Morita Oji Ogawa, Shimodate City, Ibaraki Prefecture 1500 Shimodate Research Laboratory, Hitachi Chemical Co., Ltd. (72) Inventor: Takahiro Tanabe 1500, Oji Ogawa, Shimodate City, Ibaraki Pref.In the Shimodate Plant, Hitachi Chemical Co., Ltd. (56) References JP-A-7-142860 (JP, A) JP-A-9-136372 (JP, A) JP-A-63-75073 (JP, A) JP JP-A-2-150468 (JP, A) JP-A-6-157815 (JP, A) JP-A-6-242432 (JP, A) JP-A-9-254313 (JP, A) A) JP-A-9 -302142 (JP, A) JP-A-7-331112 (JP, A) JP-A-9-241424 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) C09D 5/25 B32B 5/00-27/42 C08J 5/04-5/08 C08J 5/24 H05K 3/46 C09C 3/08-3/12

Claims (12)

(57) [Claims] 1. An electrically insulating whisker and a siloxane resin.
It has two or more repeating units, and the terminal is opposite to the hydroxyl group on the substrate surface.
Silicone oligomer solution having at least one corresponding functional group
A method for producing an insulating varnish, comprising mixing a resin material into a solution comprising a solvent treatment liquid for treating the surface of an electrically insulating whisker comprising: 2. The electrically insulating whisker is a ceramic whisker, wherein the whisker has an average diameter of 0.3 to
The method for producing an insulating varnish according to claim 1, wherein the insulating varnish has a range of 3.0 µm and an average length of 3 to 50 µm. 3. The silicone oligomer has a trifunctional (RSiO _3/2 ) siloxane unit or a tetrafunctional (SiO _4/2 ) unit in the molecule.
Manufacturing method of the insulating varnish according to claim 1 or 2, characterized by using those containing siloxane units. (In the formula, R groups are the same or different organic groups.) 4. A silicone oligomer, also claim 1, characterized in bifunctional (R ₂ SiO _2/2) siloxane units and tetrafunctional (SiO _4/2) be used those containing siloxane units in the molecule
3. The method for producing an insulating varnish according to item 2 . (In the formula, R groups are the same or different organic groups.) 5. The silicone oligomer has three functional groups in the molecule.
(RSiO _3/2) siloxane units and tetrafunctional (SiO _4/2) according to claim 1 or, characterized by using one containing siloxane units
3. The method for producing an insulating varnish according to item 2 . (In the formula, R groups are the same or different organic groups.) 6. The silicone oligomer has a bifunctional compound in the molecule.
(R ₂ SiO _2/2) siloxane units and trifunctional (RSiO _3/2) The claim 1, characterized by using one containing siloxane units
3. The method for producing an insulating varnish according to item 2 . (In the formula, R groups are the same or different organic groups.) 7. The silicone oligomer has a bifunctional compound in the molecule.
(R ₂ SiO _2/2) siloxane units and trifunctional (RSiO _3/2) siloxane units and tetrafunctional to claim 1 or 2, characterized by using one containing a (SiO _4/2) siloxane units A method for producing the insulating varnish according to the above. (In the formula, R groups are the same or different organic groups.) 8. The silicone oligomer contains 15 mol% of tetrafunctional (RSiO _4/2 ) siloxane units in the molecule.
Claim 3, characterized in that the above is used .
8. The method for producing an insulating varnish according to any one of 4, 5, and 7 . 9. A solvent treatment solution, the production method of the insulating varnish according to any one of claims 1 to 8, characterized in that the combined use of silicone oligomer and a silane coupling agent. 10. A solvent treatment solution, the production method of the insulating varnish according to any one of claims 1 to 8, characterized in that the combined use of silicone oligomer and a titanate coupling agent. 11. An insulating varnish produced by the method according to any one of claims 1 to 10 . 12. An insulating material obtained by applying an insulating varnish produced by the method according to any one of claims 1 to 10 to a copper foil or a carrier film, and laminating with a wiring board having a circuit formed thereon. A multilayer printed wiring board manufactured by forming a circuit on an outer layer surface and electrically connecting the circuit to an inner layer circuit.