JPH10287833A - Production of insulating varnish and multi-layered printed wiring board using the insulating varnish - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an insulating varnish capable of giving adhesive films inhibited in the contamination of whisker aggregates and high in insulating reliability by stirring electrically insulating whiskers in a resin varnish and subsequently kneading the prepared slurry by the use of a bead mill. SOLUTION: This method for producing an insulating varnish comprises stirring electrically insulating ceramic whiskers having an average diameter of 0.3-3 μm and an average length of 3-50 μm in a resin varnish, and subsequently kneading the prepared slurry by the use of a bead mill. Thereby, the insulating varnish giving printed wiring boards flat in surfaces, good in circuit processability, high in rigidity, hence high in mounting reliability, high in surface hardness, good in thermal expansion coefficient, and hence good in dimensional stability is obtained. A multi-layered printed wiring board is obtained by coating the varnish on a copper foil, etc., laminating the obtained insulating material to an inner layer wiring board having an inner circuit thereon, forming an outer layer surface circuit on the laminate, and subsequently electrically connecting the outer layer circuit to the inner layer circuit.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing an insulating varnish applied to an insulating material for a printed wiring board which can meet the demand for thinner and higher density printed wiring boards on which electronic components are mounted, and a method for manufacturing the same. The present invention relates to a multilayer printed wiring board using an insulating material obtained from varnish.

[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. The multilayer printed wiring board is formed by hot-pressing these printed wiring boards via a prepreg, or by hot-pressing these printed wiring boards and copper foil via a prepreg. A circuit is formed on the surface of the multilayer copper-clad laminate containing the inner layer circuit obtained by the formation.

As a prepreg for a printed wiring board, a glass cloth prepreg obtained by impregnating a glass cloth with a resin and drying the resin to make the resin semi-cured has been used. For a multilayer printed wiring board, the prepreg of the glass cloth prepreg has been used. other,
JP-A-6-200216 and JP-A-6-24246
Japanese Patent Application Laid-Open No. 6-19686, which describes a prepreg that does not use a glass cloth and is made of a resin having a film forming ability in a semi-cured state.
An adhesive film with a copper foil having an adhesive film formed on one side of a copper foil, as described in Japanese Patent Publication No. 2 (JP-A) No. 2 (1994), is used. The film-forming ability referred to here means that troubles such as cracking or chipping of the resin hardly occur during the steps of transporting, cutting, and laminating the prepreg, and the interlayer insulating layer is formed in the portion where the inner layer circuit exists at the time of subsequent hot pressing. 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. Further, fine through holes and interstitial via holes (IVH) are required, and good drill workability and laser hole workability are required. 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, and it is desirable to use a thermosetting resin such as an epoxy resin.

However, the epoxy resin has high fluidity due to its low molecular weight before molding, and does not have the property of forming a sheet-like insulating material. Therefore,
Conventionally, a prepreg in which an insulating resin is impregnated into a reinforcing base material such as a glass cloth has been prepared in advance and used as an insulating layer. However, it has become difficult to respond to the above requirements with the conventional prepreg.

At present, in the glass cloth generally used for the prepreg, the gap between the yarns (glass fiber bundles) increases as the thickness decreases. 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. Further, the thinner the glass cloth is, the larger the gap between the yarns is, the lower the volume fraction of the fibers of the prepreg becomes, and the lower the rigidity of the interlayer insulating layer becomes. For this reason, there is a problem in that the deflection is likely to increase in a component mounting step or the like after processing the circuit in the outer layer.

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. Furthermore, a multilayer printed wiring board manufactured using a prepreg using these glass cloths is easily misaligned by a glass cloth unevenly distributed during small-diameter drilling, and the drill is easily folded. In addition, due to the presence of glass fibers, laser drilling is poor,
The unevenness of the inner layer circuit easily appears on the surface, and the surface flatness is poor.
Therefore, it is not possible to meet the increasing demand for higher density and thinner multilayer printed wiring boards using the current glass cloth base material prepreg.

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 drill workability, laser hole workability 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 a high temperature, and is likely to bend in the component mounting process, and the wire bonding property is extremely poor. In addition, there is no glass cloth substrate in the outer insulating layer and the coefficient of thermal expansion is large because the thermal expansion coefficient is large, the reliability of connection with the mounted component is low, and cracks in the solder connection due to the thermal expansion and contraction of heating and cooling And many problems such as easy breakage. Therefore, it is not possible to meet the increasing demand for higher density and thinner multilayer printed wiring boards by using an adhesive film which is a prepreg without a glass cloth or an adhesive film with a copper foil.

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. It was found that a sheet-like insulating material obtained by casting a varnish obtained by dispersing an electrically insulating whisker for maintaining shape in an insulating resin on a carrier substrate was effective. However, electrical insulating whiskers have the property of agglomerating in a dry state, and special kneading equipment is required to disperse the electrical insulating whiskers in the insulating resin. However, even if such measures are taken, the aggregates of the electrically insulating whiskers cannot be completely eliminated. By the way, in the multilayer wiring board material, the insulating layer thickness is set to be equal to or greater than the inner layer circuit thickness in order to ensure the filling property of the inner layer circuit. It is desired to be as thin as possible. Therefore, the thickness of the insulating layer is usually 25 to 100 μm, and at least 25 μm
Is secured. However, the size (length) of the aggregate of electrically insulating whiskers exceeds 50 μm, and some
Some of them exceeded 00 μm. When a sheet-like insulating material produced using a varnish containing an aggregate of electrically insulating whiskers is applied to a multilayer wiring board, the aggregate of electrically insulating whiskers comes into contact between conductors, and CAF (Conducer)
tive Anodic Filament).

An object of the present invention is to provide a method for producing an insulating varnish having excellent electrical insulation properties.

[0011]

The method for producing an insulating varnish of the present invention is characterized in that a slurry is prepared by stirring an electrically insulating whisker in a resin varnish, and the slurry is kneaded with a bead mill.

The electrically insulating whiskers before the preparation of the slurry include ceramic whiskers having an average diameter of 0.3 to 3.0 μm and an average length of 3 to 50 μm. Some can be used.

An insulating material obtained by applying such an insulating varnish to a copper foil or a carrier film is laminated on an inner wiring board on which an inner circuit is formed, and a circuit on an outer layer is formed. To form a multilayer wiring board.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION

(Bead Mill) The bead mill used in the present invention is preferably made of ceramic, and it is necessary that no foreign matter is mixed in the kneading step of the insulating varnish containing the electrically insulating ceramic whisker. As a ceramic bead mill, one that combines zirconia beads with equipment coated on the inner surface with high hardness zirconia hardly causes scratches and peeling even when kneading an electrically insulating ceramic whisker, it is used in insulating varnish. This is preferable because foreign substances are hardly mixed. Further, the size of the beads is not particularly limited, but is preferably in the range of 300 μm to 2 mm in diameter. When the diameter is less than 300 μm, the efficiency of separation from the insulating varnish by the filter is low, the loss of the insulating varnish is large, and the separation speed is low. When the diameter exceeds 2 mm, the frequency of collision with the electrically insulating whisker decreases, and the kneading efficiency decreases.

(Whisker) The whisker used in the present invention is an electrically insulating ceramic whisker.
It is preferable that the elastic modulus is 200 GPa or more.
If it is less than 0 GPa, sufficient rigidity cannot be obtained when a multilayer printed wiring board is formed. Examples of whisker types include aluminum borate, wollastonite, potassium titanate, basic magnesium sulfate, silicon nitride, α-
One or more materials selected from alumina can be used. Among them, aluminum borate whiskers are
It has a modulus of elasticity of about 400 GPa, much higher than that of glass, a small coefficient of thermal expansion, and is relatively inexpensive. The printed wiring board manufactured using the prepreg of the present invention using the aluminum borate whisker has higher rigidity at room temperature and high temperature than the conventional printed wiring board using glass cloth, and has excellent wire bonding properties. Low thermal expansion coefficient and excellent dimensional stability. Therefore,
As a material of the whisker used in the present invention, aluminum borate is optimal. The average diameter of the whiskers is 0.3
If it is less than μm, mixing with the resin varnish becomes difficult and the coating workability deteriorates. If it exceeds 3 μm, the flatness of the surface is adversely affected and the microscopic uniform dispersion of whiskers is impaired. Therefore, the average diameter of the whiskers is preferably in the range of 0.3 μm to 3 μm.
Furthermore, the same reason and good coatability (easy to apply smoothly)
Therefore, the average diameter is most preferably in the range of 0.5 μm to 1 μm. 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, if the whiskers are too long, it becomes difficult to uniformly disperse them in the varnish, and the coatability decreases. In addition, 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 the insulating material of the present invention using a whisker having such a length has better migration resistance than a conventional printed wiring board using a prepreg based on a glass cloth.

In order to further increase the rigidity and heat resistance of the printed wiring board, it is effective to use whiskers whose surfaces have been treated with a silane coupling agent. Whiskers surface-treated with a coupling agent are excellent in wettability and bonding with a resin, and can improve rigidity and heat resistance. The coupling agent used at this time is silicon-based,
Known materials such as titanium, aluminum, zirconium, zirconaluminium, chromium, boron, phosphorus, and amino acids can be used.

(Resin) The resin used in the present invention is a resin used for a conventional prepreg using a glass cloth as a base material and an adhesive film not containing a glass cloth base material or an adhesive film with a copper foil. 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 conventional prepregs based on glass cloth has no film-forming ability by itself, so it is formed as an adhesive layer on one side of copper foil by coating, and the solvent is removed by heating. When semi-cured, during transporting, cutting and laminating processes, troubles such as cracking or chipping of the resin are likely to occur, and during subsequent hot pressing, the interlayer insulating layer becomes abnormally thin at the inner layer circuit existing part etc. Conventionally, it has been difficult to use for an adhesive film with a copper foil because it is easy to cause a trouble such as a decrease in insulation resistance or a short circuit. However, in the present invention, whiskers are dispersed in the resin, and the resin is reinforced by the whiskers. Therefore, the prepreg layer composed of the resin of the present invention and the whiskers exhibits film forming ability, and is transported, cut, and laminated. During the steps such as those described above, troubles such as cracking or chipping of the resin hardly occur, and the occurrence of the phenomenon that the interlayer insulating layer becomes abnormally thin 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. It is also possible to reduce the amount of the high molecular weight component to be added by the amount of the film forming ability enhanced by the dispersion of the whiskers, 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, or various modified resins thereof are suitable. Among them, bismaleimide triazine resin and epoxy resin are particularly preferable in terms of printed wiring board characteristics. As the epoxy resin, bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol S type epoxy resin, phenol novolak type epoxy resin, cresol novolak type epoxy resin, bisphenol A novolak type epoxy resin, salicylaldehyde novolak type epoxy resin, Bisphenol F novolak type epoxy resin, alicyclic epoxy resin, glycidyl ester type epoxy resin, glycidylamine type epoxy resin, hydantoin type epoxy resin, isocyanurate type epoxy resin, aliphatic cyclic epoxy resin and their halides and hydrogenated products And mixtures of the above resins. 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 Resins, 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, and is preferably in the range of 2 to 100 parts by weight with respect to 100 parts by weight of the resin. Further, in the case of dicyandiamide, 2 to 5 parts by weight, For other curing agents, the range is preferably 30 to 80 parts by weight. If it is less than 2 parts by weight, sufficient curing cannot be obtained,
If the amount exceeds 100 parts by weight, an excessive curing agent may remain, and the electric properties and the like of the cured product may be deteriorated.

(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 preferably in the range of 0.01 to 20 parts by weight, more preferably 0.1 to 20 parts by weight, based on 100 parts by weight of the resin.
A range of 10 parts by weight is more preferred. If the amount is less than 0.01 part by weight, the curing will be remarkably slow, and if it exceeds 20 parts by weight, the curing rate will be so high that the curing reaction cannot be controlled.

(Diluent) The thermosetting resin of the present invention can be diluted with a solvent and used as a resin varnish. Such solvents include acetone, methyl ethyl ketone, toluene, xylene, methyl isobutyl ketone, ethyl acetate, ethylene glycol monomethyl ether, methanol, ethanol, N, N-dimethylformamide, 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. If the amount is less than 1 part by weight, there is no effect as a diluent, and if it exceeds 200 parts by weight, the viscosity of the resin composition is too low, and it is difficult to apply the resin composition to a copper foil or a carrier film.

(Other Compounding Agents) Further, in the present invention, conventionally known coupling agents, fillers and the like may be appropriately added to the resin, if necessary, in addition to the above-mentioned components.

(Proportion of Resin and Whisker) If 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 prepreg is liable to be finely broken at the time of cutting and to be easily scattered. In addition, the handleability is deteriorated, and sufficient rigidity cannot be obtained when the wiring board is used. On the other hand, if the mixing amount of the whisker is 350 parts by weight or more, the filling property of the inner layer circuit and the resin filling property between the circuits at the time of hot pressing are impaired, and the whisker composite resin layer after the hot pressing is voids or faint. 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. The amount of the whisker is 30 parts by weight based on 100 parts by weight of the resin solid content because the whisker can have dimensional stability and wire bonding properties.
More preferably, it is 230 parts by weight.

(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) Whisker in the insulating material composed of the electrically insulating whisker of the present invention and the resin in the B-stage state is in a state close to two-dimensional orientation (whisker is in the axial direction of the insulating material layer). (A state close to being parallel to the surface to be formed). By orienting the whiskers in this manner, 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, when a resin varnish obtained by mixing whiskers with a copper foil is coated, a blade is used. A coating that can apply a shearing force in the direction parallel to the copper foil such as a coater, rod coater, knife coater, squeeze coater, reverse roll coater, transfer roll coater, etc., or can apply a compressive force in the direction perpendicular to the copper foil surface. The construction method may be adopted.

The present invention relates to a method for producing an insulating varnish by kneading an electrically insulating whisker prepared in a slurry form using a resin varnish using a bead mill. By improving the dispersibility and shortening the average length of the electrically insulating whiskers, the entanglement between the electrically insulating whiskers is reduced, and the electrically insulating whiskers are not included in the insulating varnish to contain the electrically insulating whisker aggregates. The insulation reliability of the insulating material obtained by compounding the above can be improved. In addition, the insulating layer manufactured using the insulating material of the present invention has good workability with respect to laser light and is a fine whisker than glass, so that the insulating layer using the conventional glass cloth prepreg is not used. Difficult laser drilling can be done easily. Therefore, a small-diameter interstitial via hole (IVH) having a diameter of 100 μm or less can be easily formed, and the circuit of the printed wiring board can be miniaturized.
It can greatly contribute to higher density and higher performance of electronic equipment.

[0029]

【Example】

Example 1 70 parts by weight of (varnish) bisphenol A novolak type epoxy resin (molecular weight: 1200, epoxy equivalent: 208) and bisphenol A novolak resin (molecular weight: 7)
00, hydroxyl equivalent: 118) and 30 parts by weight, and 0.5% of 2-ethyl-4-methylimidazole as a curing accelerator.
Parts by weight and a thermosetting resin consisting of 70 parts by weight of methyl ethyl ketone, an average diameter of 0.8 μm and an average fiber length of 20 μm.
m of aluminum borate whisker with a resin solid content of 100
It was blended so as to be 90 parts by weight with respect to parts by weight, and stirred until the aluminum borate whisker became a slurry. This slurry was kneaded with a batch-type zirconia bead mill for 90 minutes, passed through a 200-mesh nylon filter to separate and remove the beads, and the kneaded varnish was defoamed with a vacuum dryer to obtain an insulating varnish. . (Adhesive film) This insulating varnish was coated with 18 μm thick copper foil and 50 μm thick polyethylene terephthalate (hereinafter, referred to as
It is called PET. ) Coat the film with a knife coater,
Heat drying at a temperature of 150 ° C. for 10 minutes to remove the solvent and semi-curing of the resin, so that the thickness of the adhesive layer is 50 μm.
And an adhesive film with a copper foil of 100 μm, and an adhesive film with a thickness of 50 μm and 100 μm with a PET film.
The ET film was peeled off and removed to prepare adhesive films having a whisker volume fraction of 30% and an epoxy resin in a semi-cured state with the whiskers and having a thickness of 50 μm and 100 μm. The produced adhesive film with copper foil can be cut cleanly without scattering of resin by a cutter knife and shear, without blocking between adhesive films,
The handling was good. In addition, the adhesive film produced by coating the PET film has no troubles such as cracking during peeling of the PET film or normal handling, and can be cut cleanly with a cutter knife and shear without scattering of resin. There was no blocking between them, and the handling was good.

(Electrolytic corrosion test) Next, an etching resist pattern was formed on the copper foil surface of the glass-epoxy double-sided copper-clad laminate having a thickness of 0.8 mm so as to be an electrode on the inner surface of the electrolytic corrosion test. The copper foil in the various places is removed by etching, and the adhesive film with the copper foil having a thickness of 50 μm of the insulating layer prepared above is overlapped on the upper and lower sides so that the adhesive film is in contact with the pattern serving as the electrode on the inner surface of the electrolytic corrosion test. And stack 17
Hot pressing was performed under the conditions of 5 ° C., 2 MPa and 60 minutes. In the obtained laminate, a portion corresponding to the position of the electrolytic corrosion test pattern serving as the inner layer electrode, an etching resist pattern was formed in a shape serving as the outer layer electrode, and copper foil in unnecessary portions was removed by etching. An electrolytic corrosion test piece was obtained. The inner layer and a voltage of 50V was applied between the outer electrodes, 85 ° C., a result of measuring the insulation resistance value after 1000 hours passed in an atmosphere of RH 85%, showed good values of more than 10 ⁹ Omega, adhesive It was confirmed that the film had excellent corrosion resistance.

(Bending elastic modulus) Further, the prepared thickness 100
A single-sided roughened copper foil having a thickness of 18 μm was laminated on and under the μm adhesive film so that the roughened surface faced the adhesive film, and was subjected to hot pressing. The copper foil of the obtained copper-clad laminate was removed by etching, and the flexural modulus was measured by three-point bending.
It was 0 GPa (no copper foil, vertical average). (Drilling Accuracy) When the copper-clad laminates were drilled by stacking ten copper-clad laminates with a diameter of 0.3 mm, the amount of displacement between the uppermost plate and the lowermost plate was measured to be 20 μm or less.

(Multilayer Printed Wiring Board) Unnecessary portions of the copper foil on both sides of the copper-clad laminate are etched and removed to form a circuit, and a 50 μm-thick adhesive film previously produced is laminated on both sides thereof. Further, a single-sided roughened copper foil having a thickness of 18 μm is laminated on the outside so that the roughened surface faces the adhesive film, and is hot-pressed at 175 ° C., 2 MPa, and 60 minutes,
A multilayer copper-clad laminate with an inner circuit was prepared. As a result of measuring the surface roughness of the multilayer copper-clad laminate containing the inner layer circuit with a stylus type surface roughness meter, the measurement location was on a straight line having a length of 25 mm including a portion with and without an inner layer circuit immediately below. On the surface of the outer layer, the average of 10 points 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, and the surface flatness was satisfactory without any trouble in circuit processing. Further, a predetermined position of the surface copper foil of the multilayer copper-clad laminate containing the inner layer circuit was removed by etching to remove
Drill a hole of 5μm, make a hole using an impact laser manufactured by Sumitomo Heavy Industries, Ltd., perform desmear treatment with permanganic acid, perform electroless plating, then print and develop an etching resist pattern. Then, unnecessary copper was removed by etching to form a circuit. On both sides of this multilayer printed wiring board, the adhesive film having a thickness of 50 μm previously prepared is laminated, and further on the outside thereof, a 18 μm-thick one-side roughened copper foil is laminated so that the roughened surface faces the adhesive film, At 175 ° C., 2 MPa, 60 minutes, hot-press molding is performed to prepare a multilayer copper-clad laminate with an inner layer circuit, a predetermined position is etched away, a hole having a diameter of 75 μm is formed, and a hole is formed in the hole by Sumitomo Heavy Industries, Ltd. Drilling using Impact Laser Co., Ltd., performing desmear treatment with permanganic acid, performing electroless plating, baking and developing an etching resist pattern, etching away unnecessary copper To form a circuit. Repeat the above steps for 10
A layer printed wiring board was produced.

(Test of Multilayer Printed Wiring Board) A part of the multilayer printed wiring board was cut out, and its coefficient of thermal expansion and flexural modulus were measured. The coefficient of thermal expansion was measured by TMA, and the flexural modulus was measured by a bending mode of DMA. The average coefficient of thermal expansion in the vertical direction is 10 ppm / ° C. (at room temperature), and the average bending elastic modulus in the vertical direction is 60 G at room temperature.
Pa and 40 GPa at high temperature (200 ° C.). The surface hardness measured by a Barcol hardness meter is 65 at room temperature,
It was 50 at high temperature (200 ° C.). (Wire bonding property) Further, 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 are
When the ultrasonic output was 1 W, the ultrasonic output time was 50 μs, the bond load was 100 g, and the wire bonding temperature was 180 ° C., the wire bonding was successfully performed. (Thermal shock test) Also, an IC chip (TSOP) having a size of 8 mm × 20 mm was connected to the surface circuit via solder on this 10-layer printed wiring board, and this IC chip (TSOP)
Is mounted at -65 ° C for 30 minutes and 150 ° C for 30 minutes.
As a result of evaluation by a thermal shock test in which exposure to the environment for one minute was one cycle, no defect such as disconnection occurred in the solder connection even after 2,000 cycles. A continuity test was performed on a circuit including an interstitial via hole inside the substrate, but no trouble such as disconnection occurred.

Example 2 A (varnish) salicylaldehyde novolak type epoxy resin (molecular weight: 1000, epoxy equivalent: 180) was mixed with 70
Parts by weight and bisphenol A novolak resin (molecular weight:
700, hydroxyl equivalent: 118), 30 parts by weight, and N-methylimidazole as a curing accelerator, 0.5 part by weight,
An aluminum borate whisker having an average diameter of 0.8 μm and an average fiber length of 20 μm was mixed with a thermosetting resin composed of 70 parts by weight of methyl ethyl ketone so as to be 90 parts by weight based on 100 parts by weight of the resin solid content. The whiskers were stirred until they became a slurry. This slurry was kneaded with a batch-type zirconia bead mill for 90 minutes, passed through a 200-mesh nylon filter to separate and remove the beads, and the kneaded varnish was defoamed with a vacuum dryer to obtain an insulating varnish. . (Adhesive film) This insulating varnish was applied to a copper foil of 18 μm thickness and a PET film of 50 μm thickness by a knife coater, and was heated and dried at a temperature of 150 ° C. for 10 minutes to remove the solvent and to remove the resin. Cured to produce an adhesive film with a copper foil with an adhesive layer thickness of 50 μm and 100 μm, and an adhesive film with a PET film with an adhesive layer thickness of 50 μm and 100 μm. Peel the PET film from the adhesive film with a PET film Removal was performed to produce an adhesive film having a whisker volume fraction of 30% and a thickness of 50 μm and a thickness of 100 μm comprising a whisker and an epoxy resin in a semi-cured state. The produced adhesive film with a copper foil was cut cleanly by a cutter knife and a shear without scattering of a resin, etc., and there was no blocking between the adhesive films, and the handleability was good. Also, PET
The adhesive film produced by coating the film has no trouble such as cracking during peeling of the PET film or normal handling, and can be cut cleanly with a cutter knife and shear without scattering of resin, and blocking between adhesive films. No problem occurred, and the handleability was good.

(Electro-corrosion test) Next, a pattern to be an electrode of the inner layer surface of the electro-corrosion test was formed on the copper foil surface of the glass epoxy double-sided copper clad laminate having a thickness of 0.8 mm by etching. The adhesive film with a copper foil having a thickness of 50 μm of the insulating layer prepared above was laminated and laminated so that the adhesive film was in contact with the pattern to be the electrode on the inner surface of the electrolytic corrosion test, and the conditions were 175 ° C., 2 MPa, and 60 minutes. And hot pressing.
An outer layer electrode pattern was formed by etching on a portion of the obtained laminated board corresponding to the position of the inner layer electrode electrolytic corrosion test pattern, thereby obtaining an electrolytic corrosion test piece. A voltage of 50 V is applied between the electrodes of the inner layer and the outer layer, and 85 ° C., 85% RH
As a result of measuring the insulation resistance value after 1000 hours under the atmosphere, a good value of 10 ⁹ Ω or more was confirmed, and it was confirmed that the adhesive film was excellent in electric corrosion resistance. (Flexural Modulus) Further, a 18 μm-thick roughened copper foil having a thickness of 18 μm was laminated above and below the prepared adhesive film having a thickness of 100 μm so that the roughened surface faced the adhesive film.
Thermocompression molding was performed at 2 ° C. for 60 minutes. When the copper foil of the obtained copper-clad laminate was removed by etching, and the flexural modulus was measured by three-point bending, it was 20 GPa (no copper foil, average vertical length). (Drilling Accuracy) When the copper-clad laminates were drilled by stacking ten copper-clad laminates with a diameter of 0.3 mm, the amount of displacement between the uppermost plate and the lowermost plate was measured to be 20 μm or less.

(Multilayer Printed Wiring Board) Unnecessary portions of the copper foil on both sides of the copper-clad laminate are etched and removed to form a circuit, and the adhesive film of the present invention having a thickness of 50 μm previously prepared on both sides thereof. Laminated copper foil with a thickness of 18 μm is laminated on the outside so that the roughened surface faces the adhesive film, and is hot-pressed at 175 ° C., 2 MPa for 60 minutes to form a multilayer copper clad with an inner circuit. A laminate was prepared. The surface roughness of the multilayer copper-clad laminate containing the inner layer circuit was measured with a stylus type surface roughness meter. As a result, the measurement point was a straight line having a length of 25 mm including a portion with and without an inner layer circuit immediately below. On the surface of the outer layer on the line, the level difference of 10
The point average was 3 μm or less, and good surface flatness that did not hinder circuit processing was obtained. Further, a predetermined position of the surface copper foil of the multilayer copper-clad laminate containing the inner layer circuit was removed by etching to form a hole having a diameter of 75 μm, and the hole was formed by Sumitomo Heavy Industries, Ltd.
Drilling using an impact laser made, performing desmear treatment with permanganic acid, performing electroless plating, baking and developing an etching resist pattern, etching away unnecessary copper, and removing the circuit Was formed. On both sides of this multilayer printed wiring board, the adhesive film having a thickness of 50 μm previously prepared is stacked, and further on the outside thereof, a 18 μm-thick roughened copper foil is laminated so that the roughened surface faces the adhesive film, It is hot-pressed under the conditions of 175 ° C., 2 MPa and 60 minutes to prepare a multilayer copper-clad laminate with an inner layer circuit, and a predetermined position of the copper foil is removed by etching to make a hole of 75 μm in diameter. Drilling is performed using an impact laser manufactured by Machine Industry Co., Ltd., desmearing with permanganic acid is performed, electroless plating is performed, and an etching resist pattern is baked and developed to form unnecessary portions of copper. A circuit was formed by etching away. The above steps were repeated to produce a 10-layer printed wiring board.

(Test of Multilayer Printed Wiring Board) A part of this multilayer printed wiring board was cut out, and its coefficient of thermal expansion and flexural modulus were measured. The coefficient of thermal expansion was measured by TMA, and the flexural modulus was measured by a bending mode of DMA. The average coefficient of thermal expansion in the vertical direction is 10 ppm / ° C. (at room temperature), and the average bending elastic modulus in the vertical direction is 60 G at room temperature.
Pa and 50 GPa at high temperature (200 ° C.). The surface hardness measured by a Barcol hardness meter is 65 at room temperature,
It was 55 at high temperature (200 ° C.). (Wire bonding property) Further, 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 are
When the ultrasonic output was 1 W, the ultrasonic output time was 50 μs, the bond load was 100 g, and the wire bonding temperature was 180 ° C., the wire bonding was successfully performed. (Thermal shock test) Also, an IC chip (TSOP) having a size of 8 mm × 20 mm was connected to the surface circuit via solder on this 10-layer printed wiring board, and this IC chip (TSOP)
Is mounted at -65 ° C for 30 minutes and 150 ° C for 30 minutes.
As a result of evaluation by a thermal shock test in which exposure to the environment for one minute was performed as one cycle, no defect such as disconnection occurred in the solder connection even after 2,000 cycles. A continuity test was performed on a circuit including an interstitial via hole inside the substrate, but no trouble such as disconnection occurred.

Comparative Example 1 70 parts by weight of (varnish) bisphenol A novolak type epoxy resin (molecular weight: 1200, epoxy equivalent: 206) and bisphenol A novolak resin (molecular weight: 7)
00, hydroxyl equivalent: 118) in a resin varnish consisting of 30 parts by weight, 0.5 parts by weight of 2-ethyl-4-methylimidazole and 70 parts by weight of methyl ethyl ketone, having an average diameter of 0.8 μm and an average fiber length of 20 μm. Of aluminum borate whiskers of 90 parts by weight per 100 parts by weight of resin solids
It was blended so as to be parts by weight, and stirred until aluminum borate whiskers were uniformly dispersed in the varnish. (Adhesive film) This insulating varnish was applied to a copper foil of 18 μm thickness and a PET film of 50 μm thickness by a knife coater, and was heated and dried at a temperature of 150 ° C. for 10 minutes to remove the solvent and to remove the resin. Cured to produce an adhesive film with a copper foil with an adhesive layer thickness of 50 μm and 100 μm, and an adhesive film with a PET film with an adhesive layer thickness of 50 μm and 100 μm. Peel the PET film from the adhesive film with a PET film Removal was performed to produce an adhesive film having a whisker volume fraction of 30% and a thickness of 50 μm and a thickness of 100 μm comprising a whisker and an epoxy resin in a semi-cured state. The produced adhesive film with a copper foil was cut cleanly by a cutter knife and a shear without scattering of a resin, etc., and there was no blocking between the adhesive films, and the handleability was good. Also, PET
The adhesive film produced by coating the film has no trouble such as cracking during peeling of the PET film or normal handling, and can be cut cleanly with a cutter knife and shear without scattering of resin, and blocking between adhesive films. No problem occurred, and the handleability was good.

(Electrolytic corrosion test) Next, an etching resist pattern was formed on the copper foil surfaces on both sides of the glass epoxy double-sided copper-clad laminate having a thickness of 0.8 mm in a shape to be an electrode on the inner surface of the electrolytic corrosion test. Unnecessary portions of the copper foil are removed by etching, and an adhesive film having a thickness of 50 μm of the adhesive layer prepared above is overlapped on the upper and lower sides so that the adhesive film is in contact with a pattern serving as an electrode on the inner surface of the electrolytic corrosion test. Further, a single-sided roughened copper foil having a thickness of 18 μm was laminated so that the roughened surface faced the adhesive film, and was hot-pressed at 175 ° C., 2 MPa and 60 minutes. Unnecessary portions of the copper foil of the obtained laminated board are removed by etching, and a pattern to be an outer layer electrode is formed at a position corresponding to the position of the inner layer electrode to be an electrolytic corrosion test pattern to obtain an electrolytic corrosion test piece. Was. A voltage of 50 V was applied between the inner layer electrode and the outer layer electrode, and the change with time was tracked in an atmosphere of 85 ° C. and 85% RH. As a result, the insulation resistance value after 250 hours became less than 10 ⁹ Ω, and the adhesive film became electrically resistant. It turned out that it was inferior in eating habits. (Bending elastic modulus) A single-sided roughened copper foil having a thickness of 18 μm is laminated on and under the prepared adhesive film having a thickness of 100 μm so that the roughening faces the adhesive film.
a, Hot-press molding was performed under the conditions of 60 minutes. When the copper foil of the obtained copper-clad laminate was removed by etching, and the flexural modulus was measured by three-point bending, it was 20 GPa (no copper foil, average vertical length). (Drilling Accuracy) When the copper-clad laminates were drilled by stacking ten copper-clad laminates with a diameter of 0.3 mm, the amount of displacement between the uppermost plate and the lowermost plate was measured to be 20 μm or less.

(Multilayer Printed Wiring Board) The copper-clad laminate was subjected to circuit processing, and the thickness of 50 μm previously formed on both surfaces thereof
The adhesive film of the present invention is laminated, and a single-sided roughened copper foil having a thickness of 18 μm is further laminated on the outside so that the roughened surface faces the adhesive film, and is hot-pressed at 175 ° C., 2 MPa, and 60 minutes. Then, a multilayer copper-clad laminate containing an inner layer circuit was produced. As a result of measuring the surface roughness of the multilayer copper-clad laminate containing the inner layer circuit with a stylus type surface roughness meter, the measurement location was on a straight line having a length of 25 mm including a portion with and without an inner layer circuit immediately below. On the surface of the outer layer, the average of 10 points 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, and the surface flatness was satisfactory without any trouble in circuit processing. Further, a predetermined position of the surface copper foil of the multilayer copper-clad laminate containing the inner layer circuit was etched away to form a hole having a diameter of 75 μm, and the hole was formed using an impact laser manufactured by Sumitomo Heavy Industries, Ltd.
After performing desmear treatment with permanganate and performing electroless plating, bake the etching resist pattern.
The circuit was formed by development, and unnecessary portions of copper were removed by etching to form a circuit. On both sides of this multilayer printed wiring board, the adhesive film having a thickness of 50 μm previously prepared, and a single-sided roughened copper foil having a thickness of 18 μm on the outside thereof are further laminated so that the roughened surface faces the adhesive film. ℃, 2MPa,
It is hot-pressed under the conditions of 60 minutes to prepare a multilayer copper-clad laminate with an inner circuit, and a predetermined position of the copper foil is removed by etching to make a hole having a diameter of 75 μm.
Drilling using Impact Laser Co., Ltd., performing desmear treatment with permanganic acid, performing electroless plating, baking and developing an etching resist pattern, etching away unnecessary copper Thus, a circuit was formed. The above steps were repeated to produce a 10-layer printed wiring board.

(Test of Multilayer Printed Wiring Board) A part of the multilayer printed wiring board was cut out, and its coefficient of thermal expansion and flexural modulus were measured. The coefficient of thermal expansion was measured by TMA, and the flexural modulus was measured by a bending mode of DMA. The average coefficient of thermal expansion in the vertical direction is 10 ppm / ° C. (at room temperature), and the average bending elastic modulus in the vertical direction is 60 G at room temperature.
Pa and 40 GPa at high temperature (200 ° C.). The surface hardness measured by a Barcol hardness meter is 65 at room temperature,
It was 50 at high temperature (200 ° C.). (Wire bonding property) Further, 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 are
When the ultrasonic output was 1 W, the ultrasonic output time was 50 μs, the bond load was 100 g, and the wire bonding temperature was 180 ° C., the wire bonding was successfully performed. (Thermal shock test) Also, an IC chip (TSOP) having a size of 8 mm × 20 mm was connected to the surface circuit via solder on this 10-layer printed wiring board, and this IC chip (TSOP)
Is mounted at -65 ° C for 30 minutes and 150 ° C for 30 minutes.
As a result of evaluation by a thermal shock test in which exposure to the environment for one minute was performed as one cycle, no defect such as disconnection occurred in the solder connection even after 2,000 cycles. A continuity test was performed on a circuit including an interstitial via hole inside the substrate, but no trouble such as disconnection occurred.

Comparative Example 2 (prepreg) bisphenol A novolak type epoxy resin (molecular weight: 1200, epoxy equivalent: 206) was mixed with 7
0 parts by weight, 30 parts by weight of bisphenol A novolak resin (molecular weight: 700, hydroxyl equivalent: 118), and 2 parts by weight.
0.5 parts by weight of -ethyl-4-methylimidazole;
A resin varnish consisting of 70 parts by weight of methyl ethyl ketone is impregnated onto a glass cloth having a thickness of 50 μm and 100 μm, and dried by heating at a temperature of 150 ° C. for 10 minutes to remove the solvent and semi-harden the resin. The thickness of the semi-cured epoxy resin is 70 μm and 1
A 20 μm epoxy prepreg was prepared. The resin was scattered in the prepared prepreg when cutting with a cutter knife and a shear.

(Electro-corrosion test) Next, an etching resist pattern was formed on the copper foil surfaces on both sides of the glass epoxy double-sided copper-clad laminate having a thickness of 0.8 mm so as to be an electrode on the inner layer surface of the electro-corrosion test. An unnecessary portion of the copper foil is removed by etching, and an epoxy prepreg having a thickness of 70 μm and a roughened single-sided copper foil having a thickness of 18 μm are formed on the upper and lower portions of the copper prepreg. And hot-pressed under the conditions of 175 ° C., 2 MPa, and 60 minutes. An outer layer electrode pattern was formed by etching on a portion of the obtained laminated board corresponding to the position of the inner layer electrode electrolytic corrosion test pattern, thereby obtaining an electrolytic corrosion test piece. The inner layer and a voltage of 50V was applied between the outer electrodes, 85 ° C., a result of measuring the insulation resistance value after 1000 hours passed in an atmosphere of RH 85%, showed good values of more than 10 ⁹ Omega, epoxy It was confirmed that the cured product of the prepreg had excellent electric corrosion resistance. (Bending elastic modulus) A single-side roughened copper foil having a thickness of 18 μm is placed above and below the epoxy prepreg having a thickness of 120 μm prepared above.
Laminate so that the roughened surface faces the prepreg,
Thermocompression molding was performed at 2 ° C. for 60 minutes at 60 ° C. When the flexural modulus of the obtained copper-clad laminate was measured by three-point bending, it was 8 GPa (no copper foil, average lengthwise). (Drilling Accuracy) Further, when the copper-clad laminates were drilled by stacking ten copper-clad laminates with a diameter of 0.3 mm, the deviation between the hole positions of the uppermost plate and the lowermost plate was measured and found to be 50 μm or more.

(Multilayer Printed Wiring Board) An unnecessary portion of the copper-clad laminate is removed by etching the copper foil to produce an inner layer circuit board, and a 50 μm-thick glass epoxy prepreg previously prepared is laminated on both sides thereof. 18μ thick outside
m single-sided roughened copper foil was laminated such that the roughened surface faced the prepreg, and was hot-pressed at 175 ° C., 2 MPa, and 60 minutes to produce a multilayer copper-clad laminate with an inner layer circuit. As a result of measuring the surface roughness of the multilayer copper-clad laminate containing the inner layer circuit with a stylus type surface roughness meter, the measurement location was on a straight line having a length of 25 mm including a portion with and without an inner layer circuit immediately below. Of the step between the part with and without the inner layer circuit on the outer layer surface of
The zero point average was 8 μm or more. Further, a predetermined position of the surface copper foil of the multilayer copper-clad laminate containing the inner layer circuit was removed by etching to make a hole having a diameter of 75 μm, and the hole was tried to be made by using an impact laser manufactured by Sumitomo Heavy Industries, Ltd. However, the glass part could not be removed.

Comparative Example 3 (Adhesive Film) 50 parts by weight of a high molecular weight epoxy polymer having a weight average molecular weight of 50,000, and
N, N-dimethylacetamide was used so that the high molecular weight epoxy polymer had a solid content of 30% by weight, 50 parts by weight of a bisphenol A type epoxy resin (molecular weight: 343, epoxy equivalent: 175), and a high molecular weight epoxy resin 0.2 equivalent of a phenolic resin-masked diisocyanate as a cross-linking agent and 2-ethyl-4- as a curing agent
A resin varnish consisting of 0.5 parts by weight of methyl imidazole was applied to a copper foil of 18 μm thickness and a PET film of 50 μm thickness by a knife coater, and was heated and dried at 150 ° C. for 10 minutes to remove the solvent. Then, the resin is semi-cured to produce an adhesive film with a copper foil having an adhesive layer thickness of 50 μm and an adhesive film with a PET film having an adhesive layer thickness of 50 μm, and peeling off the PET film from the adhesive film with the PET film. Removal was performed to produce an adhesive film having a thickness of 50 μm and made of an epoxy resin. The produced adhesive film was free of troubles such as cracking during peeling of the PET film or normal handling, and could be cut cleanly without scattering of resin by a cutter knife and shear, but blocking between the adhesive films occurred. The handling was bad.

(Electrolytic corrosion test) Next, an etching resist pattern was formed on the copper foil surfaces on both sides of the glass epoxy double-sided copper-clad laminate having a thickness of 0.8 mm in a shape to be an electrode on the inner layer surface of the electrolytic corrosion test. Then, unnecessary portions of the copper foil are removed by etching, and the adhesive film with a copper foil having a thickness of 50 μm of the adhesive layer prepared above and below is brought into contact with the pattern in which the adhesive film serves as an electrode on the inner surface of the electrolytic corrosion test. And hot-pressed under the conditions of 175 ° C., 2 MPa, and 60 minutes. An outer layer electrode pattern was formed by etching on a portion of the obtained laminated board corresponding to the position of the inner layer electrode electrolytic corrosion test pattern, thereby obtaining an electrolytic corrosion test piece. A voltage of 50 V is applied between the electrodes of the inner layer and the outer layer, and 85 ° C., 85%
As a result of measuring an insulation resistance value after 1000 hours in an atmosphere of RH, a good value of 10 ⁹ Ω or more was shown, and it was confirmed that the adhesive film was excellent in electric corrosion resistance.

(Multilayer Printed Wiring Board) A 50 μm-thick adhesive film prepared previously was laminated on both sides of the inner circuit board prepared in Comparative Example 1, and a 18 μm-thick roughened copper foil was further roughened on the outer side. The laminate was laminated so that the surface thereof faced the adhesive film, and hot-pressed at 175 ° C. and 2 MPa for 60 minutes to produce a multilayer copper-clad laminate having 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. As a result, the measurement point was a straight line having a length of 25 mm including a portion with and without an inner layer circuit immediately below. On the surface of the outer layer on the line, the level difference of 10
The point average was 3 μm or less, and good surface flatness that did not hinder circuit processing was obtained. Further, a predetermined position of the surface copper foil of the multilayer copper-clad laminate containing the inner layer circuit was removed by etching to form a hole having a diameter of 75 μm, and the hole was formed by Sumitomo Heavy Industries, Ltd.
After drilling using an impact laser manufactured, performing desmear treatment with permanganic acid, performing electroless plating, baking and developing an etching resist pattern, etching away unnecessary copper, and removing the circuit Was formed. On both sides of this multilayer printed wiring board, the adhesive film having a thickness of 50 μm previously prepared, and a single-sided roughened copper foil having a thickness of 18 μm on the outside thereof are further laminated so that the roughened surface faces the adhesive film. C., 2 MPa, for 60 minutes to produce a multi-layer copper-clad laminate with an inner layer circuit.
After making a hole of μm, making a hole using an impact laser manufactured by Sumitomo Heavy Industries, Ltd., performing desmear treatment with permanganic acid, performing electroless plating, and then printing and developing the etching resist pattern. The circuit was formed by removing unnecessary portions of copper by etching. The above steps were repeated to produce a 10-layer printed wiring board.

(Test of Multilayer Printed Wiring Board) A part of this multilayer printed wiring board was cut out, and its coefficient of thermal expansion and flexural modulus were measured. The coefficient of thermal expansion was measured by TMA, and the flexural modulus was measured by a bending mode of DMA. The average coefficient of thermal expansion in the vertical direction is 30 ppm / ° C. (at room temperature), and the average bending elastic modulus in the vertical direction is 20 G at room temperature.
Pa and 10 GPa at a high temperature (200 ° C.). The surface hardness measured by a Barcol hardness tester was 30 at room temperature,
It was 10 at high temperature (200 ° C.). (Wire bonding property) Further, 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 are
The ultrasonic output was 1 W, the ultrasonic output time was 50 μs, and the bond load was 100 g. Wire bonding temperature 10
Even when the temperature was lowered to 0 ° C., peeling of the wire occurred. (Thermal shock test) Also, an IC chip (TSOP) having a size of 8 mm × 20 mm was connected to the surface circuit via solder on this 10-layer printed wiring board, and this IC chip (TSOP)
Is mounted at -65 ° C for 30 minutes and 150 ° C for 30 minutes.
As a result of a thermal shock test in which exposure to the environment for one minute was performed as one cycle, a disconnection defect occurred in the solder connection part after about 100 cycles. Further, a continuity test of a circuit including an interstitial via hole inside the substrate revealed a broken portion.

[0049]

According to the method for producing an insulating varnish of the present invention,
Mixing of the aggregate of the electrically insulating whiskers into the adhesive film in which the electrically insulating whiskers are combined can be suppressed at the stage of the insulating varnish, and the insulation reliability of the adhesive film can be increased. 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. Is flat, has good circuit workability, has high rigidity, so that mounting reliability is high, surface hardness is high, wire bonding is good, and thermal expansion coefficient is small, so dimensional stability is good. Therefore, the density of the multilayer printed wiring board has been increased,
It makes a great contribution to thinning, high reliability, and low cost.

Continuation of the front page (51) Int.Cl. ⁶ Identification symbol FI // C08L 63/00 C08L 63/00 C (72) Inventor Yasushi Yashiro 1500 Oji Ogawa, Shimodate-shi, Ibaraki Pref. 72) Inventor Atsuyuki Takahashi 1500 Ogawa, Shimodate, Ibaraki Pref., Shimodate Research Laboratory, Hitachi Chemical Co., Ltd. Person Shigeharu Ariya 1500 Oji Ogawa, Shimodate City, Ibaraki Pref., Shimodate Research Laboratory, Hitachi Chemical Co., Ltd. Hitachi Chemical Industry Co., Ltd., Shimodate Research Laboratory (72) Inventor Daisuke Fujimoto 1500, Oji Ogawa, Shimodate City, Ibaraki Prefecture, Hitachi Chemical Industry Co., Ltd.

Claims (3)

[Claims] 1. A method for producing an insulating varnish, comprising stirring an electrically insulating whisker in a resin varnish to prepare a slurry, and kneading the slurry with a bead mill. 2. An electrically insulating whisker before preparing a slurry is a ceramic whisker having an average diameter of 0.3 to 3 μm and an average length of 3 to 50 μm. The method for producing an insulating varnish according to claim 1, wherein the insulating varnish is used. 3. An insulating material obtained by applying the insulating varnish according to claim 1 to a copper foil or a carrier film,
A multilayer printed wiring board manufactured by laminating an inner layer circuit board having an inner layer circuit formed thereon, forming a circuit on an outer layer surface, and electrically connecting to the inner layer circuit.