JP2011202053A - Resin varnish, carrier material with resin, prepreg, and laminated board - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a resin varnish that has little dissolved oxygen content therein and few defects in appearance when molding, and a carrier material with a resin, a prepreg, and a laminated board using the resin varnish.SOLUTION: The resin varnish is used for forming an insulating layer. The resin varnish is composed of a resin composition including a thermosetting resin, a filler, and a solvent, and has the dissolved oxygen content of 50% or less.

Description

The present invention relates to a resin varnish, a carrier material with a resin, a prepreg, and a laminated board.

  Resin varnish containing a filler is excellent in heat resistance and moldability, and has been used in various fields such as automobiles, aircraft, building materials, daily necessities, and industrial parts. As a problem common to these resin varnishes, as the filler content increases, it becomes necessary to increase the viscosity of the resin varnish and to perform a high dispersion treatment process, so that bubbles are likely to be generated in the resin varnish. It is done. The generated bubbles partially dissolve in the resin varnish or remain as bubbles. Then, at the time of molding by heating, dissolved air is generated inside the molded product as bubbles and voids. For this reason, the physical strength of the molded product is reduced, moisture enters from the bubble portion, cracking or peeling occurs, and the product is deteriorated. Further, when bubbles remain in the vicinity of the surface of the molded product, it causes a poor appearance. Various defoaming treatments have been studied in order to remove bubbles in the resin varnish (see, for example, Patent Document 1 and Patent Document 2).

  In recent years, along with demands for higher functionality, electronic components have been densely integrated and densely mounted, and electronic components compatible with high-density mounting used for these components have become more compact than ever. Therefore, in the electronic device, the influence of bubbles in the molded product is particularly large. Furthermore, when impregnating the resin varnish with a fibrous base material that easily generates bubbles, such as a prepreg, the defoaming treatment at the resin varnish stage is particularly important (see, for example, Patent Document 3). However, confirmation of the defoaming effect is a judgment after molding, such as measuring the void ratio of the molded product or checking the number of voids and blurring by visually checking the molded product, which can surely improve the yield. There was a problem that I could not.

JP 2002-234037 A JP 2003-39567 A JP 2002-307433 A

An object of the present invention is to provide a resin varnish with less appearance defects during molding.
Moreover, it is providing the carrier material with a resin using the said resin varnish, a prepreg, and a laminated board.

Such an object is achieved by the present inventions (1) to (8) below.
(1) A resin varnish used for forming an insulating layer, wherein the resin varnish is composed of a resin composition including a thermosetting resin, a filler, and a solvent, and the resin varnish is dissolved. A resin varnish characterized by having an oxygen content of 50% or less.
(2) Content of the said filler is a resin varnish as described in said (1) which is 65-400 weight part with respect to 100 weight part of said thermosetting resins.
(3) The resin varnish according to (1) or (2), wherein the thermosetting resin is selected from the group consisting of a cyanate resin, an epoxy resin, a phenoxy resin, or a phenol resin.
(4) The resin varnish according to any one of (1) to (3), wherein the solvent is selected from the group consisting of cyclohexanone, methyl isobutyl ketone, methyl ethyl ketone, and acetone.
(5) A carrier material with resin, which is obtained by applying the resin varnish according to any one of (1) to (4) to a carrier material.
(6) A prepreg obtained by impregnating a base material with the resin varnish according to any one of (1) to (4).
(7) A laminate obtained using the carrier material with a resin according to (5).
(8) A laminate obtained by using the prepreg described in (6) above.

According to the present invention, it is possible to suppress the occurrence of appearance defects during molding and produce a resin varnish with a high yield of molded products.
In addition, by using the resin varnish, a carrier material with resin, a prepreg, and a laminate having a high yield can be produced.

  Hereinafter, the resin varnish, the carrier material with resin, the prepreg, and the laminate will be described.

The resin varnish of the present invention is a resin varnish used for forming an insulating layer, and the resin varnish is composed of a resin composition containing a thermosetting resin, a filler, and a solvent, and the resin varnish. The amount of dissolved oxygen is 50% or less.
The carrier material with a resin of the present invention is obtained by applying the resin varnish to a carrier material.
The prepreg of the present invention is obtained by impregnating a base material with the resin varnish.
Moreover, the laminated board of this invention is obtained using the said carrier material with a resin, or the said prepreg, It is characterized by the above-mentioned.

  The resin varnish of the present invention is a resin varnish used for forming an insulating layer, and the resin varnish is composed of a resin composition containing a thermosetting resin, a filler, and a solvent, and the resin varnish. The dissolved oxygen content of the varnish is 50% or less.

  The insulating layer is not particularly limited, but includes insulating exteriors of electronic components such as capacitors and motors, sealing resin layers, interlayer insulating films in semiconductor integrated circuits, insulating substrates, insulating adhesive layers, solder resists, built-up layers, Non-conductive layers in semiconductor products such as planarization films and wafer coats can be mentioned.

The thermosetting resin is not particularly limited. For example, epoxy resin, cyanate resin, cyanate ester resin, xylene resin, guanamine resin, diallyl phthalate resin, vinyl ester resin, phenol resin, phenoxy resin, unsaturated polyester resin, polyimide , Resins having a triazine ring such as polyurethane, male resin, melamine resin, urea resin and epoxy acrylate, unsaturated polyester resin, bismaleimide resin, polyurethane resin, diallyl phthalate resin, silicone resin, resin having a benzoxazine ring It is done. Among these, those selected from the group consisting of an epoxy resin, a cyanate resin, a phenoxy resin, and a phenol resin are preferable because of excellent heat resistance, electrical characteristics, and cost.
These can be used alone or in combination of two or more.

Examples of the epoxy resin include bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol E type epoxy resin, bisphenol S type epoxy resin, bisphenol M type epoxy resin, bisphenol P type epoxy resin, and bisphenol Z type epoxy resin. Bisphenol type epoxy resins, phenol novolac type epoxy resins, cresol novolac epoxy resins and other novolac type epoxy resins, biphenyl type epoxy resins, xylylene type epoxy resins, biphenyl aralkyl type epoxy resins and other aryl alkylene type epoxy resins, naphthalene type epoxy resins , Anthracene type epoxy resin, phenoxy type epoxy resin, dicyclopentadiene type epoxy resin, norbornene type epoxy resin, adamanta Type epoxy resins, fluorene type epoxy resins and the like. The epoxy resin is preferable because it has high heat resistance, is excellent in insulation and insulation reliability, and is inexpensive.
One of these can be used alone, or two or more having different weight average molecular weights can be used in combination, or one or two or more of these prepolymers can be used in combination.

The cyanate resin can be obtained, for example, by reacting a halogenated cyanide compound with a phenol and prepolymerizing it by a method such as heating as necessary. Specific examples include bisphenol type cyanate resins such as novolac type cyanate resin, bisphenol A type cyanate resin, bisphenol E type cyanate resin, and tetramethylbisphenol F type cyanate resin.
Among these, novolac type cyanate resin is preferable. Thereby, the heat resistance improvement resulting from the improvement of a crosslinking density and the flame retardance of a resin composition etc. can be improved. This is because the novolac-type cyanate resin forms a triazine ring after the curing reaction. Furthermore, it is considered that novolak-type cyanate resin has a high benzene ring ratio due to its structure and is easily carbonized. Furthermore, even when the insulating layer has a thickness of 0.5 mm or less, excellent rigidity can be imparted to the manufactured insulating layer. In particular, since the rigidity during heating is excellent, the reliability when mounting a semiconductor element is also particularly excellent.
One of these can be used alone, or two or more having different weight average molecular weights can be used in combination, or one or two or more of these prepolymers can be used in combination.

  As said novolak-type cyanate resin, what is shown by following formula (1) can be used, for example.

  The average repeating unit n of the novolak cyanate resin represented by the formula (1) is not particularly limited, but is preferably 1 to 10, and particularly preferably 2 to 7. When the average repeating unit n is less than the lower limit, the novolak cyanate resin has low heat resistance, and the low-mer may be desorbed and volatilized during heating. Moreover, when average repeating unit n exceeds the said upper limit, melt viscosity will become high too much, and when it uses for a prepreg, a moldability may fall.

The phenoxy resin is not particularly limited. For example, in addition to a phenoxy resin having a bisphenol skeleton such as a bisphenol A type phenoxy resin, a bisphenol F type phenoxy resin, a bisphenol A / F mixed type phenoxy resin, a phenoxy resin having a naphthalene skeleton. And a phenoxy resin having a biphenyl skeleton. Thereby, plasticity can be given and the dimensional change of the layer arrange | positioned up and down of the insulating layer with respect to a heat history can be absorbed.
One of these can be used alone, or two or more having different weight average molecular weights can be used in combination, or one or two or more of these prepolymers can be used in combination.

  Although it does not specifically limit as said phenol resin, A novolak type phenol resin, a resol type phenol resin, an aryl alkylene type phenol resin, etc. are mentioned. The phenol resin is preferable because the heat resistance and punchability are improved. Among these, arylalkylene type phenol resins are preferable. Thereby, heat resistance can be improved further. Examples of the aryl alkylene type phenol resin include a xylylene type phenol resin and a biphenyl dimethylene type phenol resin. A biphenyl dimethylene type phenol resin can be shown, for example by following formula (2).

Although n of the biphenyl dimethylene type | mold phenol resin shown by Formula (2) is not specifically limited, 1-12 are preferable and 2-8 are especially preferable. If it is less than this, the heat resistance may decrease. Moreover, when more than this, since compatibility with other resin falls and workability | operativity may worsen, it is unpreferable. The combination of the aforementioned cyanate resin and / or prepolymer thereof (particularly a novolac type cyanate resin) and an arylalkylene type phenol resin can control the crosslink density and improve the adhesion between the metal and the resin.
One of these can be used alone, or two or more having different weight average molecular weights can be used in combination, or one or two or more of these prepolymers can be used in combination.

  Although it does not specifically limit as said filler, An inorganic filler and an organic filler can be used. Among these, an inorganic filler is preferable from the viewpoint of heat resistance.

Examples of the inorganic filler include silicates such as talc, fired clay, unfired clay, mica and glass, oxides such as titanium oxide, alumina, silica and fused silica, calcium carbonate, magnesium carbonate and hydrotalcite. Carbonates such as aluminum hydroxide, boehmite, magnesium hydroxide, calcium hydroxide, etc., sulfates or sulfites such as barium sulfate, calcium sulfate, calcium sulfite, zinc borate, barium metaborate, boric acid Examples thereof include borates such as aluminum, calcium borate and sodium borate, nitrides such as aluminum nitride, boron nitride and silicon nitride, carbon black, and inorganic pigments.
The inorganic pigment is not particularly limited as long as it is substantially insoluble in water. Examples of the white pigment include titanium dioxide (titanium white, titanium white), zinc oxide (zinc white), basic lead carbonate ( Examples of colored pigments such as lead white), strontium titanate, antimony oxide, and lithopone (a mixed crystal of zinc sulfide and barium sulfate) include petals, bitumen, county blue, cobalt blue, and chrome green.
Among these, aluminum hydroxide is preferable. Aluminum hydroxide releases moisture rapidly by heating, and the released water vapor dilutes the gas phase combustible gas, so that it can impart flame resistance.

As the organic filler, a dye or an organic pigment can be used. The organic dye and the organic pigment may be dissolved or dispersed in the resin. Examples of the organic dye include, but are not limited to, diaminostilbene disulfonic acid derivatives, imidazole derivatives, oxazole derivatives, coumarin derivatives, triazole derivatives, carbazole derivatives, pyridine derivatives, pyrazoline derivatives, naphthalic acid derivatives, imidazolone derivatives, and the like.
The organic pigment is not particularly limited as long as it is insoluble in water, and examples thereof include phthalocyanine blue, phthalocyanine green, isoindolinone yellow, quinacridone red, perylene red, and silicone resin powder.

  The content of the filler is preferably 65 to 400 parts by weight with respect to 100 parts by weight of the thermosetting resin. 100-350 weight part is further more preferable, and 150-300 weight part is especially preferable. When the content of the filler is within the above range, low thermal expansion and low water absorption can be imparted to the resin varnish.

The average particle diameter of the filler is not particularly limited, but is preferably 0.1 to 5 μm, particularly preferably 0.2 to 3 μm. If the average particle size of the filler is less than the lower limit, the viscosity of the varnish increases, which may affect workability during prepreg production. When the upper limit is exceeded, phenomena such as sedimentation of the filler may occur in the resin varnish.
The average particle diameter can be measured using, for example, a laser light scattering particle size distribution measuring apparatus.

The solvent is not particularly limited, and examples thereof include ketone solvents such as acetone, methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone, amide solvents such as dimethylacetamide and dimethylformamide, alcohols such as methanol and ethanol, toluene, xylene, and the like. Aromatic hydrocarbons, N, N-dimethylformamide, N, N-dimethylacetamide, N-methylpyrrolidone and other aprotic polar solvents, ethyl acetate, cyclohexane, heptane, cyclohexane, tetrahydrofuran, dimethyl sulfoxide, ethylene glycol, carb Examples include tall, cell solve, and anisole.
Among these, cyclohexanone, methyl isobutyl ketone, methyl ethyl ketone, and acetone are preferable. Thereby, the said thermosetting resin can be melt | dissolved favorably. One of these can be used alone, or two or more can be used in combination. In addition, a poor solvent can be used in combination as long as no adverse effect is exerted.

The amount of dissolved oxygen in the resin varnish is preferably 50% or less. In the present invention, the dissolved oxygen amount is a relative value when the dissolved oxygen amount measured in a state where oxygen dissolved in the resin varnish is saturated by aeration or the like is defined as 100%. By measuring this, the amount of air (air) dissolved in the resin varnish can be estimated.
The amount of dissolved oxygen is more preferably 40% or less, and particularly preferably 20% or less. Thereby, at the time of application | coating and application of the said resin varnish, there is no generation | occurrence | production of a repellency, a stripe, etc., and the carrier material with a resin of a favorable coating surface, a prepreg, etc. can be obtained with a sufficient yield.
The method for measuring the amount of dissolved oxygen in the resin varnish can be measured using a dissolved oxygen meter equipped with a galvanic oxygen sensor, for example, D-506 manufactured by Iijima Electronics Co., Ltd.

  In order to make the amount of dissolved oxygen within the above range, the resin varnish is defoamed. Examples of the defoaming method include vacuum defoaming, thin film defoaming, rotation revolution defoaming and the like. As the defoaming method, an appropriate one may be selected according to the properties of the resin varnish, and it may be processed by a single method or may be processed in combination of two or more. In order to promote defoaming, it is also effective to defoam after heating the resin varnish. In particular, it is preferable to use the rotation and revolution defoaming method in a heated state.

Next, the carrier material with resin will be described.
The carrier material with a resin can be obtained by forming an insulating layer on the surface of a carrier film, a metal foil or the like using the resin varnish.

The resin varnish is coated on a carrier film or a metal foil using various coating apparatuses, and then dried. Or after spray-coating a resin varnish on a carrier film or metal foil with a spray apparatus, this is dried. A resin sheet can be produced by these methods.
Although the said coating apparatus is not specifically limited, For example, a roll coater, a bar coater, a knife coater, a gravure coater, a die coater, a comma coater, a curtain coater, etc. can be used. Among these, a method using a die coater, a knife coater, and a comma coater is preferable. Thereby, the carrier material with a resin which does not have a void and has the thickness of a uniform insulating layer can be manufactured efficiently.

  Since the carrier film forms an insulating layer on the carrier film, it is preferable to select one that is easy to handle. Moreover, when using a carrier film, since an insulating layer is laminated | stacked on an inner-layer circuit board surface, since a carrier film is peeled, it is preferable that peeling is easy. Therefore, it is preferable to use a thermoplastic resin film having heat resistance such as a polyester resin such as polyethylene terephthalate or polybutylene terephthalate, a fluorine-based resin, or a polyimide resin, for example. Among these carrier films, a film made of polyester is most preferable. This facilitates peeling from the insulating layer with an appropriate strength.

  Although the thickness of the said carrier film is not specifically limited, 1-100 micrometers is preferable and 3-50 micrometers is especially preferable. When the thickness of the carrier film is within the above range, handling is easy and the flatness of the surface of the insulating layer is excellent.

  Similar to the carrier film, the metal foil may be used after peeling a resin sheet on an inner circuit board and may be used after peeling the metal foil as a conductor circuit. The metal foil is not particularly limited. For example, copper and / or copper-based alloy, aluminum and / or aluminum-based alloy, iron and / or iron-based alloy, silver and / or silver-based alloy, gold and gold-based alloy, Metal foils such as zinc and zinc alloys, nickel and nickel alloys, tin and tin alloys can be used.

The thickness of the metal foil is not particularly limited, but is preferably 0.1 μm or more and 70 μm or less. Further, it is preferably 1 μm or more and 35 μm or less, more preferably 1.5 μm or more and 18 μm or less. When the thickness of the metal foil is less than the above lower limit value, the metal foil is scratched and pinholes are generated, and when the metal foil is etched and used as a conductor circuit, plating variation, circuit disconnection, etching during circuit pattern molding There is a risk of infiltration of chemicals such as liquid and desmear liquid. Moreover, when the said upper limit is exceeded, the thickness variation of metal foil may become large, or the surface roughness variation of a metal foil roughening surface may become large.
The metal foil may be an ultrathin metal foil with a carrier foil. The ultrathin metal foil with a carrier foil is a metal foil obtained by laminating a peelable carrier foil and an ultrathin metal foil. Since an ultra-thin metal foil layer can be formed on both sides of the insulating layer by using an ultra-thin metal foil with a carrier foil, for example, when forming a circuit by a semi-additive method, etc. By electroplating the metal foil directly as the power feeding layer, the ultrathin copper foil can be flash etched after the circuit is formed. By using an ultra-thin metal foil with a carrier foil, even with an ultra-thin metal foil having a thickness of 10 μm or less, for example, a reduction in handling properties of the ultra-thin metal foil in a pressing process, and cracking or cutting of the ultra-thin copper foil are prevented. Can do. The thickness of the ultrathin metal foil is preferably 0.1 μm or more and 10 μm or less. Furthermore, it is preferably 0.5 μm or more and 5 μm or less, more preferably 1 μm or more and 3 μm or less. When the thickness of the ultrathin metal foil is less than the lower limit, the ultrathin metal foil is damaged after peeling the carrier foil, the pinhole of the ultrathin metal foil is generated, and the circuit pattern is formed by the generation of the pinhole. There is a risk of plating variations, disconnection of circuit wiring, penetration of chemicals such as etching liquid and desmear liquid, and the like. When the upper limit is exceeded, the thickness variation of the ultrathin metal foil may increase, or the surface roughness variation of the roughened metal foil roughened surface may increase.
Usually, an ultrathin metal foil with a carrier foil peels off the carrier foil before forming a circuit pattern on the press-molded laminate.

Next, the prepreg will be described.
The prepreg of the present invention is formed by impregnating a base material with the resin varnish. Thereby, a prepreg suitable for manufacturing a printed wiring board excellent in various characteristics such as dielectric characteristics, mechanical and electrical connection reliability under high temperature and high humidity can be obtained.

  The base material is not particularly limited, but glass fiber base materials such as glass woven fabric and glass nonwoven fabric, polyamide resin fibers, aromatic polyamide resin fibers, polyamide resin fibers such as wholly aromatic polyamide resin fibers, polyester resin fibers, Synthetic fiber substrate, kraft paper, cotton linter composed of woven or non-woven fabric mainly composed of aromatic polyester resin fiber, polyester resin fiber such as wholly aromatic polyester resin fiber, polyimide resin fiber, fluororesin fiber, etc. Examples thereof include organic fiber base materials such as paper base materials mainly composed of paper, mixed paper of linter and kraft pulp, and the like. Among these, a glass fiber base material is preferable. Thereby, the intensity | strength of a prepreg can improve, a water absorption can be lowered | hung, and a thermal expansion coefficient can be made small.

  Although the glass which comprises the said glass fiber base material is not specifically limited, For example, E glass, C glass, A glass, S glass, D glass, NE glass, T glass, H glass etc. are mentioned. Among these, E glass, T glass, or S glass is preferable. Thereby, the high elasticity of a glass fiber base material can be achieved and a thermal expansion coefficient can also be made small.

  Although the method for producing the prepreg is not particularly limited, for example, a method of immersing a substrate in the resin varnish, a method of applying the resin varnish to the substrate with various coaters, and spraying the resin varnish on the substrate by spraying Methods and the like. Among these, the method of immersing the substrate in the resin varnish is preferable. Thereby, the impregnation property of the resin composition with respect to a base material can be improved. In addition, when a base material is immersed in the said resin varnish, a normal impregnation coating equipment can be used.

Next, a laminated board is demonstrated.
The laminated board of this invention is obtained using the said carrier material with a resin or the said prepreg.
It can be obtained by laminating, heating and pressurizing a metal foil on both upper and lower surfaces of one or a plurality of laminated prepregs with the resin. Although the temperature at the time of the said heating is not specifically limited, 120-230 degreeC is preferable and especially 150-210 degreeC is preferable. The pressure during the pressurization is not particularly limited, but is preferably 1 to 5 MPa, and particularly preferably 2 to 4 MPa. Thereby, the laminated board excellent in the dielectric property and the mechanical and electrical connection reliability in high temperature and high humidity can be obtained.

  EXAMPLES Hereinafter, although this invention is demonstrated in detail using an Example and a comparative example, this invention is not limited to this.

Example 1
1-1. Production of resin varnish 15.7 parts by weight of cyanate resin (Primaset PT-30 Lonza), 18.7 parts by weight of epoxy resin (NC3000 Nippon Kayaku Co., Ltd., epoxy equivalent 275), filler (AOH180 Navaltech) 39.0 parts by weight, average particle diameter 0.6 μm), 0.2 parts by weight of silane coupling agent (KBM-573, Shin-Etsu Chemical Co., Ltd., N-phenyl-3-aminopropyltrimethoxysilane), 21.6 parts by weight of spherical silica (SO-31R manufactured by Admatechs, average particle size 1.2 μm) and 4.8 parts by weight of phenol resin (MEH7851-4L, Meiwa Kasei Co., Ltd., hydroxyl equivalent 187) are added to methyl isobutyl ketone. Dissolved and mixed. Subsequently, it stirred using the high-speed stirring apparatus and prepared the resin varnish. The obtained resin varnish was defoamed with a vacuum thin film defoamer.

1-2. Production of Carrier Material with Resin The resin varnish was coated on a PET film (polyethylene terephthalate, thickness 38 μm) and dried for 2 minutes with a dryer at 150 ° C. to obtain a carrier material with resin.

1-3. Preparation of prepreg Conditions of 5 minutes at a pressure of 1 MPa and a temperature of 120 ° C. with the resin surfaces of the carrier material with resin prepared as described above placed on both sides and sandwiched between glass cloth base materials (manufactured by Nittobo Co., Ltd., WEA-116E) The laminate was impregnated in a vacuum press. Subsequently, the PET film was peeled off to obtain a prepreg having a thickness of 0.1 mm.

1-4. Production of Laminate 1 Copper foils (Mitsui Metal Mining Co., Ltd., 3EC-VLP) with a thickness of 12 μm are superimposed on both sides of the prepreg produced as described above, and heated and pressure-molded at 220 ° C. and 3 MPa. To obtain a laminate 1 having a thickness of 0.1 mm.

1-5. Production of Laminate 2 After through hole processing was performed on the laminate 1 using a 0.1 mm drill bit, the through hole was filled by plating. Further, a circuit was formed on both sides by etching and used as an inner layer circuit board.
Each of the interior circuit boards is superposed one by one with the epoxy resin surface of the carrier material with resin inside, and this is heated under vacuum at a temperature of 100 ° C. and a pressure of 1 MPa using a vacuum pressurizing laminator device. Press-molded. After peeling the PET film of the base material from the carrier material with resin, it was cured by heating at 170 ° C. for 60 minutes with a hot air drying device to obtain a laminate 2.

(Example 2)
The defoaming treatment was the same as in Example 1 except that the defoaming treatment was carried out at 40 ° C. and then the static degassing was performed.

(Example 3)
The defoaming treatment was the same as in Example 1 except that the defoaming treatment was heated to 40 ° C. and then the vacuum rotation revolution defoaming was performed.

(Comparative Example 1)
The same procedure as in Example 1 was performed except that the resin varnish was not defoamed.

2. Evaluation Evaluation of the resin varnish, prepreg, laminate 1 and laminate 2 obtained in Examples and Comparative Examples is shown below.

2-1. Dissolved oxygen amount The dissolved oxygen amount of the resin varnish at 20 ° C. was measured using a dissolved oxygen meter (model B-506, manufactured by Iijima Electronics Co., Ltd.). First, after adjusting the resin varnish to 20 ° C., a stirrer was used to stir the resin varnish so as not to entrain bubbles, thereby giving a flow rate. Next, a sensor was put into the resin varnish being stirred, and the value was read when the value was stable.
The dissolved oxygen amount in Table 1 was expressed as a relative value when the saturated dissolved oxygen amount of the resin varnish was measured in advance and the value was taken as 100%.

2-2. Appearance (carrier material with resin and prepreg)
The carrier material with resin and the number of prepregs were visually measured.
Each code | symbol in Table 1 is as follows.
○: No repelling.
Δ: 1 to 99 repels of 5 mm or more.
X: 100 or more repellents of 5 mm or more.

2-3. Appearance (laminate 1 and laminate 2)
Cross-section observation of the laminated board 1 and the laminated board 2 was performed. The cross-sectional observation was performed using a metal microscope (manufactured by Olympus Corporation).
Each code | symbol in Table 1 is as follows.
○: No void was observed in the cross-sectional observation result.
X: A void was observed in the cross-sectional observation result.

2-4. Moisture-absorbing solder characteristics After the laminated plate 1 and the laminated plate 2 were cut to 50 mm x 50 mm with a grinder saw, a sample in which only 1/4 of the copper foil was left by etching was prepared and evaluated in accordance with JIS C 6481. The evaluation was performed by performing PCT moisture absorption treatment at 121 ° C., 100% for 2 hours, and then immersing in a solder bath at 288 ° C. for 30 seconds, and then checking for an appearance abnormality.
Each code | symbol in Table 1 is as follows.
○: No abnormality.
X: Swelling occurs.

2-5. Individual warpage Using a variable temperature laser three-dimensional measuring machine (Hitachi Technology & Service Co., Ltd., model LS220-MT100MT50), the sample chamber of the measuring machine is processed into a router with a size of 50 mm × 50 mm from the laminate 2 obtained above. The sample was separated into individual pieces, and the displacement in the height direction of the sample after separation was measured, and the value with the largest displacement difference was taken as the amount of warpage.

  The obtained evaluation results are shown in Table 1.

As is apparent from Table 1, the resin varnishes obtained in Examples 1 to 3 have a small amount of dissolved oxygen, and the carrier material with resin and the prepreg of Examples 1 to 3 produced using the resin varnish have repelling. It did not occur and the appearance was good. Moreover, the laminated board 1 and the laminated board 2 which were produced using the said resin varnish did not have a void, and the external appearance was favorable. Furthermore, it was excellent also in evaluation of moisture absorption solder heat resistance and the amount of warpage.
On the other hand, in Comparative Example 1, since the amount of dissolved oxygen in the resin varnish was large, repelling occurred in the carrier material with resin and the prepreg. Moreover, voids were generated in the laminate 1 and the laminate 2 produced using the resin varnish, and the evaluation of the hygroscopic solder heat resistance and the warpage amount of the laminate after separation was inferior.

  By using the resin varnish of the present invention, it is possible to produce a carrier material with a resin and a prepreg with little appearance defect during molding. Thereby, a laminated board can be produced with a sufficient yield.

Claims (8)

A resin varnish used for forming an insulating layer, wherein the resin varnish is composed of a resin composition containing a thermosetting resin, a filler, and a solvent, and the amount of dissolved oxygen in the resin varnish is 50. % Resin varnish characterized by being less than or equal to%. The resin varnish according to claim 1, wherein the content of the filler is 65 to 400 parts by weight with respect to 100 parts by weight of the thermosetting resin. The resin varnish according to claim 1 or 2, wherein the thermosetting resin is selected from the group consisting of a cyanate resin, an epoxy resin, a phenoxy resin, and a phenol resin. The resin varnish according to any one of claims 1 to 3, wherein the solvent is selected from the group consisting of cyclohexanone, methyl isobutyl ketone, methyl ethyl ketone, and acetone. A carrier material with a resin, which is obtained by applying the resin varnish according to claim 1 to a carrier material. A prepreg obtained by impregnating a base material with the resin varnish according to claim 1. A laminate obtained using the carrier material with a resin according to claim 5. A laminate obtained by using the prepreg according to claim 6.