KR20210084279A - Resin composition, resin film and metal clad laminate - Google Patents

Abstract

Provided are a resin composition and a resin film capable of responding to the high frequency of electronic devices by further improving the dielectric properties of a resin film using polyimide as a raw material. More specifically, the present invention relates to a resin composition which contains a solid content of polyamic acid or an organic compound containing polyimide, and silica particles, wherein the content of silica particles is in a range of 10 to 85 wt% with respect to a total amount of the solid content and the total of the silica particles, and as the total crystal particles, a ratio of the total area of the peaks derived from a cristobalite crystal phase and a quartz crystal phase to the total peak area derived from SiO_2 in the range of 2Θ=10 to 90° of the X-ray diffraction spectrum by CuKα ray is 20 wt% or more.

Description

A resin composition, a resin film, and a metal clad laminated board TECHNICAL FIELD

The present invention relates to, for example, a resin composition useful as a circuit board material, a resin film, and a metal-clad laminate.

In recent years, use of a thin and lightweight flexible printed wiring board (FPC) is increasing with size reduction, weight reduction, and space saving of an electronic device. Since the FPC enables three-dimensional and high-density mounting even in a limited space, its use is expanding to parts such as wiring of movable parts of electronic devices, cables, and connectors. In addition to these, as the speed and performance of communication devices progress, FPC corresponding to a high-frequency transmission signal for realizing a high transmission speed is also required.

As a problem in transmitting high-frequency signals, there is a transmission loss in the signal transmission path. If the transmission loss is large, problems such as loss of electrical signals and delay of signals occur. In order for FPC to respond to high frequency increase, it becomes important to reduce the transmission loss by lowering the dielectric constant of the insulating resin layer and lowering the dielectric loss tangent. Therefore, a liquid crystal polymer or a fluorine resin having a low dielectric constant and a low dielectric loss tangent is used as an insulating resin layer for the FPC for high frequency signals. However, although liquid crystal polymers have excellent dielectric properties, there is room for improvement in heat resistance and adhesion to metal foil, and fluorine-based resins have poor handling properties because of their high coefficient of thermal expansion.

Polyimide is also used as an insulating resin excellent in heat resistance and adhesiveness with metal foil. However, in general, polyimide has inferior dielectric properties compared to liquid crystal polymers and fluorine-based resins. As a method for low-dielectric conversion of an aromatic polyimide, there is a method in which an aliphatic structure is included in the resin skeleton. However, the advantage of including the aliphatic structure in the resin skeleton is, in most cases, a trade-off relationship with the required characteristics of FPC such as heat resistance and dimensional stability. As other means, there are various obstacles in terms of cost and productivity in order to achieve low dielectric conversion while maintaining excellent heat resistance and required characteristics of FPC only with the skeleton of polyimide, such as using special monomers or expensive fluorine-based monomers.

Therefore, a method of improving properties by compounding a resin and a different material is known. For example, in patent document 1, the polyimide composition excellent in thermal conductivity is reported by compounding the powder of aluminum nitride or silicon nitride, and a specific polyimide.

Moreover, in patent document 2, the generation|occurrence|production of the curvature in a semiconductor package and a crack is suppressed by adding cristobalite silica to an epoxy resin.

Compositing is also effective in improving dielectric properties, and in Patent Document 3, a resin film having a low dielectric loss tangent and low thermal expansion is proposed as a combination of a thermosetting polyimide resin and elastomer synthesized from amorphous silica and bismaleimide. Moreover, in patent document 4, the manufacturing method of the low dielectric polyimide film which combined polyimide and fluororesin particle|grains is proposed.

Japanese Patent No. 3551687 Japanese Patent Laid-Open No. 2019-1937 Japanese Patent Laid-Open No. 2018-12747 Japanese Patent No. 6387181 Publication

As described above, it has been desired to develop a polyimide having a low dielectric conversion while maintaining properties such as high heat resistance and excellent adhesion. However, in patent document 3, it is limited to a thermosetting resin, and there exists a subject in the adhesive strength at the time of multilayering. Moreover, in patent document 4, it is complexation with a comparatively expensive fluororesin filler, and there exists a subject, such as a thermal expansion coefficient becoming high.

In addition, in the composite of the prior art, the composition of the filler is considered important, and there is hardly any mention of the crystal structure thereof.

Accordingly, an object of the present invention is to provide a resin composition and a resin film capable of responding to the high frequency of electronic devices by further improving the dielectric properties of polyimide.

The inventors of the present invention have discovered the knowledge that, in the composite of polyimide-based resin and silica particles, the use of a silica particle having a higher ratio of cristobalite phase improves dielectric properties compared to amorphous silica, and the present invention completed.

That is, the resin composition of the present invention contains the solid content of an organic compound containing polyamic acid or polyimide, and silica particles,

The content of the silica particles is in the range of 10 to 85% by weight based on the total amount of the solid content and the total of the silica particles (however, polyamic acid is converted into imidized polyimide.);

The total area of the peaks derived from the cristobalite crystal phase and the quartz crystal phase with respect to the total peak area derived from _{SiO 2} in the range of 2θ = 10° to 90° of the X-ray diffraction spectrum by CuKα ray as the whole of the silica particles. of 20% by weight or more.

_{In the resin composition of the present invention, the median diameter D 50} in the frequency distribution curve of the silica particles obtained by the volume-based particle size distribution measurement by the laser diffraction scattering method may be in the range of 6 to 20 µm.

As for the resin composition of this invention, the circularity of 0.7 or more may be sufficient as 90 weight% or more of the particle|grains whose particle diameter in the said silica particle is 3 micrometers or more.

As for the resin composition of this invention, 2.3 or more of true specific gravity may be sufficient as 90 weight% or more of the said silica particle.

The resin film of the present invention is a resin film having a single or multiple polyimide layers, wherein at least one of the polyimide layers is a crystalline silica-containing polyimide layer formed of any of the above resin compositions, and the crystallinity The thickness of the silica-containing polyimide layer is in the range of 15 µm to 200 µm.

As for the resin film of this invention, 50 % or more may be sufficient as the ratio of the thickness of the said crystalline silica containing polyimide layer with respect to the thickness of the whole resin film.

The resin film of the present invention may have a dielectric constant of 3.1 or less at a frequency of 3 to 20 GHz as measured by a split post dielectric resonator (SPDR).

The resin film of the present invention may have a dielectric loss tangent of 0.005 or less at a frequency of 3 to 20 GHz as measured by a split post dielectric resonator (SPDR).

The resin film of the present invention may have a coefficient of thermal expansion of 50 ppm/K or less.

The metal-clad laminate of the present invention includes an insulating resin layer and a metal layer laminated on at least one surface of the insulating resin layer, and at least one layer of the insulating resin layer contains any of the above resin films.

Since the resin composition of this invention contains the silica particle which has a specific crystal structure in addition to the heat resistance inherent in polyimide, it is excellent in dielectric properties. Therefore, the resin composition and resin film of this invention can be used especially suitably as circuit board materials, such as FPC, in the electronic device which requires high-speed signal transmission. Specifically, it is suitable for uses, such as an insulating resin layer of FPC for mobile devices, such as a smartphone which handles a high frequency signal, and an insulating resin layer of FPC for vehicle mounting which heat resistance is required.

EMBODIMENT OF THE INVENTION Hereinafter, embodiment of this invention is described.

[resin composition]

A resin composition according to an embodiment of the present invention is a resin composition containing a solid content of an organic compound containing polyamic acid or polyimide, and silica particles,

Content of the said silica particle exists in the range of 10-85 weight% with respect to the total amount of the said solid content, and the said silica particle,

The total area of the peaks derived from the cristobalite crystal phase and the quartz crystal phase with respect to the total peak area derived from _{SiO 2} in the range of 2θ = 10° to 90° of the X-ray diffraction spectrum by CuKα ray as the whole of the silica particles. of 20% by weight or more. The varnish (resin solution) containing a polyamic acid may be sufficient as a resin composition, and the polyimide solution containing a solvent-soluble polyimide may be sufficient as it.

[Solids content of organic compounds]

The solid content of the organic compound means the remaining solid content after removing the solvent and the inorganic solid content from the resin composition. That is, the solid content of the organic compound contains polyamic acid or polyimide, and as an optional component, resins other than polyimide, crosslinking agents, organic fillers, plasticizers, curing accelerators, coupling agents, organic pigments, organic flame retardants, fillers, etc. It may contain non-volatile organic compounds. Here, as resin other than a polyimide, an epoxy resin, a fluororesin, an olefin resin, polyether resin, polyester resin etc. are mentioned, for example. As a crosslinking agent, the amino compound (amino compound for bridge|crosslinking formation) etc. which have at least two primary amino groups mentioned later as a functional group are mentioned. Examples of the organic filler include liquid crystal polymer particles, fluorine-based polymer particles, polyether-based resin particles, and olefin-based resin particles.

It is preferable that it is 60 weight% or more, as for the content rate of the polyamic acid or polyimide in solid content of an organic compound, 70 weight% or more is more preferable, and 80 weight% or more is the most preferable. When the content rate of a polyamic acid or a polyimide is less than 60 weight%, the toughness of resin will fall and the film holding property at the time of forming a resin film will fall. In addition, in the case of polyamic acid, it shall be converted into imidated polyimide, and shall compute a weight ratio.

[Polyamic acid or polyimide]

A polyimide is generally represented by the following general formula (1). Such a polyimide can be produced by a known method in which a diamine component and an acid dianhydride component are used in substantially equimolar amounts and polymerized in an organic polar solvent. In this case, in order to make a viscosity into a desired range, you may adjust the molar ratio of the acid dianhydride component with respect to a diamine component, and it is preferable to make the range into the range of the molar ratio of 0.98 - 1.03, for example.

Here, Ar ₁ is a tetravalent organic _{group having one or more aromatic rings, and Ar 2} is a divalent organic group having one or more aromatic rings. And Ar ₁ may be a residue of an acid dianhydride, and Ar ₂ may be a residue of a diamine. In addition, n shows the repeating number of the structural unit of General formula (1), It is 200 or more, Preferably it is the number of 300-1000.

As the acid dianhydride, for example, _{an aromatic tetracarboxylic dianhydride represented by O(OC) 2} -Ar ₁ -(CO) ₂ O is preferable, and giving the following aromatic acid anhydride residue as Ar ₁ is exemplified. do.

An acid dianhydride can be used individually or in mixture of 2 or more types. Among these, pyromellitic dianhydride (PMDA), 3,3',4,4'-biphenyltetracarboxylic dianhydride (BPDA), 3,3',4,4'-benzophenonetetracarboxylic acid It is preferable to use one selected from dianhydride (BTDA), 3,3',4,4'-diphenylsulfonetetracarboxylic dianhydride (DSDA), and 4,4'-oxydiphthalic dianhydride (ODPA). desirable.

As the diamine, for example, _{an aromatic diamine represented by H 2} N-Ar ₂ -NH ₂ is preferable, and an aromatic diamine to which the following aromatic diamine residue is given as _{Ar 2 is exemplified.}

Among these diamines, diaminodiphenyl ether (DAPE), 2,2'-dimethyl-4,4'-diaminobiphenyl (m-TB), paraphenylenediamine (p-PDA), 1,3-bis (4-aminophenoxy)benzene (TPE-R), 1,3-bis (3-aminophenoxy) benzene (APB), 1,4-bis (4-aminophenoxy) benzene (TPE-Q), 2,2-bis[4-(4-aminophenoxy)phenyl]propane (BAPP), and 2,2-bis(trifluoromethyl)benzidine (TFMB) are exemplified as suitable.

A polyimide can be manufactured by making an acid dianhydride and a diamine compound react in a solvent, producing|generating the polyamic acid which is a precursor, and carrying out ring closure (imidization) by heating. For example, polyamic acid is obtained by dissolving an acid dianhydride and a diamine compound in substantially equimolar amounts in an organic solvent, stirring at a temperature within the range of 0 to 100°C for 30 minutes to 72 hours, and polymerization reaction. At the time of reaction, the reaction component is dissolved so that the produced|generated precursor may fall within the range of 5 to 30 weight% in an organic solvent, Preferably it is within the range of 10 to 20 weight%. Examples of the organic solvent used for the polymerization reaction include N,N-dimethylformamide (DMF), N,N-dimethylacetamide (DMAc), N,N-diethylacetamide, and N-methyl-2-pi. Rollidone (NMP), 2-butanone, dimethyl sulfoxide (DMSO), hexamethylphosphoramide, N-methylcaprolactam, dimethyl sulfate, cyclohexanone, dioxane, tetrahydrofuran, diglyme, triglyme , cresol, and the like. Two or more of these solvents may be used in combination, and further, an aromatic hydrocarbon such as xylene or toluene may be used in combination. In addition, although there is no restriction|limiting in particular as the usage-amount of such an organic solvent, It is preferable to adjust and use it so that the density|concentration of the polyamic acid solution obtained by a polymerization reaction will be about 5 to 30 weight%.

The synthesized polyamic acid is usually advantageously used as a reaction solvent solution, but it can be concentrated, diluted or replaced with another organic solvent as needed to form a resin composition. The method for imidating the polyamic acid is not particularly limited, and for example, heat treatment such as heating in the above solvent at a temperature within the range of 80 to 400° C. over 1 to 24 hours is suitably employed.

A thermoplastic polyimide may be sufficient as a polyimide, and a thermosetting polyimide may be sufficient as it. In addition, although "thermoplastic polyimide" generally refers to a polyimide whose glass transition temperature (Tg) can be clearly confirmed, in the present invention, the storage modulus at 30° C. measured using a dynamic viscoelasticity measuring device (DMA). The polyimide is 1.0×10 ⁸ Pa or more and the storage elastic modulus at 300°C is less than ^{3.0×10 7 Pa.} In addition, although "non-thermoplastic polyimide" generally refers to a polyimide that does not show softening or adhesion even when heated, in the present invention, the storage modulus at 30°C measured using a dynamic viscoelasticity measuring device (DMA) is 1.0 x10 ⁹ Pa or more and refers to a polyimide having a storage elastic modulus at 300°C of 3.0×10 ^{8 Pa or more.}

[Silica Particles]

As a silica particle, what is necessary is just to contain the crystalline silica particle. Moreover, the amorphous silica particle may be included. By mix|blending a crystalline silica particle with a resin composition, the dielectric loss tangent at the time of forming a resin film can be reduced. It is especially preferable to use the silica particle which has a cristobalite crystal phase as a crystalline silica particle from a viewpoint of attaining the low dielectric loss tangent at the time of forming a resin film. Silica particles having a cristobalite crystal phase have very excellent dielectric properties compared to general silica particles (for example, silica particles containing 90% by weight or more of a cristobalite crystal phase have a dielectric loss tangent of about 0.0008 at 10 GHz in a single unit). , can greatly contribute to the low dielectric loss tangent of the resin film.

_{In addition, the silica particles have a median diameter D 50} in a frequency distribution curve obtained by a volume-based particle size distribution by a laser diffraction scattering method in the range of 6 to 20 μm, and preferably in the range of 8 to 15 μm. . If it is in this range, a dielectric property is raised effectively, and the resin film in which the oil conversion was reduced is obtained, without deteriorating the surface smoothness when mix|blended with a resin film. When the median diameter D ₅₀ is less than the above range, the surface area of the silica particles increases, and the adsorbed water on the surface of the silica particles may affect the dielectric properties. When the median diameter D ₅₀ exceeds the said range, it may appear as the unevenness|corrugation of the surface of a film, and worsen the smoothness of the film surface.

Moreover, as a silica particle, it is preferable to use a spherical silica particle. A spherical silica particle is a silica particle whose shape is close|similar to a true spherical shape, and the ratio of an average major diameter to an average minor diameter says that it is close to 1 or 1. Further, in order to improve the dispersibility and dielectric properties of the silica particles, it is preferable that 90 wt% or more of the silica particles having a particle diameter of 3 µm or more have a circularity of 0.7 or more, and more preferably 0.9 or more. The circularity of a silica particle can be calculated|required by the ratio of the perimeter length of the circle|circle and the perimeter length of the said particle|grains, supposing the circle which has the same projected area as the image|photographed particle by the image analysis method. When the circularity is less than 0.7, the surface area increases, which may adversely affect the dielectric properties, and the increase in the viscosity when blended with the resin solution increases, making handling difficult. In addition, in the sphericity obtained three-dimensionally, a value substantially corresponding to the value of the circularity is preferable.

Further, the silica particles preferably have a true specific gravity of 2.3 or more in order to improve the dispersibility and dielectric properties of the silica particles. When the true specific gravity is less than 2.3, it is suggested that the crystallinity of the silica particles is small, and the effect of improving the dielectric properties becomes small.

The silica particle may surface-treat. A well-known technique can be used for surface treatment, For example, modification by corona treatment, plasma treatment, UV treatment, etc., functionalization treatment using a silane coupling agent, etc. are preferable. By surface-treating silica particles, by providing an alkyl group, an amino group, an alkoxy group, etc. to the particle surface, affinity with a solvent or polyamic acid is improved, or by improving the repulsive force between particles, dispersibility of silica particles, varnish long-term stability is improved.

_{SiO 2} in the range of 2θ = 10° to 90° of the X-ray diffraction spectrum by CuKα ray as the entire aggregate of silica particles to be used from the viewpoint of achieving low dielectric loss tangent when the resin film is formed The ratio of the total area of the peaks derived from the cristobalite crystal phase and the quartz crystal phase to the total area of the total peaks derived from is preferably 20 wt% or more, more preferably 40 wt% or more, and preferably 80 wt% or more. By increasing the ratio of the cristobalite crystal phase and/or the quartz crystal phase in the entire silica particle, it becomes possible to further achieve a lower dielectric dissipation tangent of the polyimide. When the ratio of the area of the peaks derived from the cristobalite crystal phase and the quartz crystal phase in the whole silica particle is less than 20 wt%, the effect of improving the dielectric properties becomes unclear. The ratio of the cristobalite crystal phase is determined in the range of 10°≤2θ≤90° by X-ray diffraction (XRD) using α radiation for the total silica particles in a uniformly mixed state, the cristobalite crystal phase and the quartz crystal phase It is calculated|required by the ratio of the total area of the diffraction peak derived from and the total area of the diffraction peak derived from all the silica particles within the said range. In addition, when the target peak in the X-ray diffraction analysis spectrum is difficult to separate from the amorphous broad peak or overlaps with other crystalline peaks, various known analysis methods, for example, the internal standard method, the PONKCS method, etc. can be used

As a preferred embodiment, an aggregate of silica particles having a cristobalite crystal phase ratio of 50 wt% or more can be used. As a more preferred embodiment, a part of the aggregate of silica particles having a cristobalite crystal phase ratio of 90 wt% or more (for example, 80 wt% or less of the total) can be used by substituting amorphous silica particles. Alternative use of the amorphous silica particles can be performed as needed, whereby cost reduction, high-density filling, and adjustment of solution viscosity are possible, and there is an advantage in that a resin composition excellent in handleability can be prepared.

In addition, the silica particle can select and use a commercial item suitably. As the crystalline silica particles, for example, spherical cristobalite silica powder (manufactured by Nittetsu Chemical & Materials, trade name; CR10-20) can be preferably used. Further, as the amorphous silica particles that can be combined with the crystalline silica particles, a spherical amorphous silica powder (manufactured by Nittetsu Chemical & Materials, trade name; SC70-2, trade name; SP40-10) or the like can be used. Moreover, you may use together 2 or more types of other silica particle as a silica particle.

[Composition]

The content of the silica particles in the resin composition is within the range of 10 to 85% by weight (however, polyamic acid is converted into imidized polyimide.) with respect to the total amount of the solid content and silica particles of the organic compound in the resin composition. , preferably in the range of 10 to 80% by weight, more preferably in the range of 15 to 75% by weight. When the content of the silica particles is less than 10% by weight, the effect of lowering the dielectric loss tangent cannot be sufficiently obtained. In addition, when the content ratio of silica particles exceeds 85% by weight, properties such as adhesiveness of the polyimide are lowered. In particular, when the content ratio of silica particles exceeds 80% by weight, it is easy to break when a resin film is formed, When bendability falls and it is going to form a resin film, the viscosity of a resin composition becomes high and workability|operativity also falls.

[Optional Ingredients]

The resin composition of this embodiment can contain an organic solvent. Examples of the organic solvent include N,N-dimethylformamide (DMF), N,N-dimethylacetamide (DMAc), N,N-diethylacetamide, N-methyl-2-pyrrolidone (NMP). , 2-butanone, dimethyl sulfoxide (DMSO), hexamethylphosphoramide, N-methylcaprolactam, dimethyl sulfate, cyclohexanone, dioxane, tetrahydrofuran, diglyme, triglyme, cresol, etc. can Two or more of these solvents may be used in combination, and further, an aromatic hydrocarbon such as xylene or toluene may be used in combination. Although there is no restriction|limiting in particular as content of an organic solvent, It is preferable to adjust and use the concentration of polyamic acid or polyimide to about 5 to 30 weight% of usage-amounts.

In the resin composition of the present invention, an inorganic filler other than silica, an inorganic pigment, an inorganic flame retardant, an inorganic heat dissipating agent, and the like can be suitably blended as an optional component as needed within a range that does not impair the effects of the present invention. Examples of the inorganic filler other than the silica particles include aluminum oxide, magnesium oxide, beryllium oxide, niobium oxide, titanium oxide, boron nitride, aluminum nitride, silicon nitride, aluminum fluoride, calcium fluoride, magnesium fluoride, potassium silicate, phosphinic acid metal salt. and the like. These can be used 1 type or in mixture of 2 or more types.

[Viscosity]

The viscosity of the resin composition is preferably within the range of 3000 cps to 100000 cps, for example, in the range of 3000 cps to 100000 cps, as a viscosity range in which it is easy to form a coating film of uniform thickness by improving handling properties when coating the resin composition particles, 5000 cps to 50000 cps It is more preferable to set it as within the range. When the viscosity is out of the above-described range, defects such as thickness non-uniformity and streaks are likely to occur in the film during the coating operation by a coater or the like.

[Preparation of resin composition]

At the time of preparation of a resin composition, you may mix|blend a silica particle directly with the resin solution of the polyamic acid produced using arbitrary solvents, for example. Alternatively, in consideration of the dispersibility of the silica particles, the silica particles are mixed in advance with the reaction solvent in which either one of the acid dianhydride component and the diamine component, which are raw materials of polyamic acid, is added, and then the other raw material is added under stirring. You may advance superposition|polymerization. Either method may inject|throw-in all the silica particles at a time, and may divide into several times and may add little by little. In addition, a raw material may also be put in at once, and it may divide into several times and may mix little by little.

[Resin Film]

The resin film of the present embodiment is a resin film having a single or multiple polyimide layers, and at least one, preferably all, of the polyimide layers is a crystalline silica-containing polyimide layer formed of the resin composition. do.

In a resin film, it is preferable to exist in the range of 15-200 micrometers, for example, and, as for the thickness of the crystalline silica containing polyimide layer formed by the resin composition, it is more preferable to exist in the range of 20-150 micrometers. When the thickness of the crystalline silica-containing polyimide layer is less than 15 µm, silica particles protrude to the surface of the resin film, and the surface smoothness deteriorates. Conversely, when the thickness of the crystalline silica-containing polyimide layer exceeds 200 µm, it tends to be disadvantageous in terms of a decrease in bendability of the resin film.

The thickness of the whole resin film exists in the range of 15-200 micrometers, for example, it is preferable to exist in the range of 20-200 micrometers, The inside of the range which is 25-200 micrometers is more preferable. When the thickness of a resin film is less than 15 micrometers, in the conveyance process at the time of manufacture of a metal clad laminated board, it will become easy to generate|occur|produce problems, such as a wrinkle and a resin film tearing in metal foil. Conversely, when the thickness of the resin film exceeds 200 µm, it tends to be disadvantageous in terms of a decrease in bendability of the resin film.

Moreover, it is preferable that the ratio of the thickness of a crystalline silica containing polyimide layer with respect to the total thickness of a resin film is 50 % or more with respect to total thickness. When the ratio of the thickness of the crystalline silica-containing polyimide layer to the total thickness of the resin film is less than 50%, the effect of improving the dielectric properties cannot be sufficiently obtained.

The method of forming a crystalline silica containing polyimide layer is not specifically limited, A well-known method is employable. Here, the most representative example is shown.

First, a coating film is formed by directly casting a resin composition on an arbitrary supporting substrate. Next, the solvent is removed to some extent by drying the coating film at a temperature of 150°C or lower. When the resin composition contains polyamic acid, thereafter, the coating film is further subjected to heat treatment for about 5 to 30 minutes at a temperature range of 100 to 400°C, preferably 130 to 360°C, for imidization. . In this way, the crystalline silica-containing polyimide layer can be formed on the supporting substrate.

When setting it as two or more polyimide layers, after apply|coating and drying the resin solution of a 1st polyamic acid, the resin solution of a 2nd polyamic acid is apply|coated and dried. After that, similarly, the resin solution of the third polyamic acid, then the resin solution of the fourth polyamic acid, ..., the resin solution of the polyamic acid is sequentially applied as many times as necessary, and dried do. Thereafter, it is preferable to perform imidization by performing heat treatment for about 5 to 30 minutes in a temperature range of 100 to 400° C. collectively. When the temperature of imidation is lower than 100 degreeC, the dehydration ring-closure reaction of a polyimide does not fully advance, and conversely, when it exceeds 400 degreeC, there exists a possibility that a polyimide layer may deteriorate.

Moreover, by performing suitable surface treatment etc. to the arbitrary polyimide layer imidated, it can pile up a layer anew again through the process of application|coating of a resin solution, drying, and imidation. In that case, it is not necessary to complete the imidization in the intermediate step, and it is possible to complete the imidization by integrating it in the final step.

In addition, the arbitrary polyimide layer imidated can be thermocompression-bonded with the resin film formed separately.

In addition, the state which has a support base material may be sufficient as a resin film.

Further, another example of forming a crystalline silica-containing polyimide layer is given.

First, on an arbitrary support base material, a resin composition is cast-coated, and it shape|molds in film form. This film-form molding is heat-dried on a support base material, and let it be the gel film which has self-supporting property. After peeling a gel film from a support base material, when a resin composition contains a polyamic acid, it heat-processes at high temperature further, it is imidated and it is set as the resin film of polyimide.

The support base material used for formation of a crystalline silica containing polyimide layer is not specifically limited, A base material of arbitrary materials can be used. In addition, at the time of formation of a resin film, it is not necessary to form the resin film which completed imidation completely on the base material. For example, the resin film in the polyimide precursor state of a semi-cured state is isolate|separated from a support base material by means, such as peeling, and imidation is completed after isolation|separation, and it can also be set as a resin film.

A resin film may contain only the polyimide layer (the said crystalline silica containing polyimide layer is included) containing an inorganic filler, and may have a polyimide layer which does not contain an inorganic filler. When making a resin film into the laminated structure of multiple layers, it is preferable to make all the layers contain an inorganic filler when improvement of a dielectric characteristic is considered. However, when the adjacent layer of the polyimide layer containing the inorganic filler is a layer not containing an inorganic filler or a layer having a low content thereof, the advantageous effect that the sliding of the inorganic filler during processing can be prevented. can have When it has a polyimide layer which does not contain an inorganic filler, the thickness is in the range of 1/100 - 1/2 of the polyimide layer containing an inorganic filler, Preferably 1/20 - 1/3 It is better to be within the range of When it has a polyimide layer which does not contain an inorganic filler, when the polyimide layer is made to contact a metal layer, the adhesiveness of a metal layer and an insulating layer will improve.

Coefficient of thermal expansion (CTE) of the resin film is not particularly limited, for example, 10 × 10 ^-6 to 50 × 10 ^-6 / K (10 to 50ppm / K) preferably in the range, and the 15 × 10 ^{- 6} to 40 × 10 range of ^-6 / K (15 to 40ppm / K) I is more preferable. When the coefficient of thermal expansion of the resin film ^{is smaller than 10 x 10 -6} /K, curling tends to occur after a metal clad laminate, and handling properties are inferior. On the other hand, when the coefficient of thermal expansion of the resin film ^{exceeds 50×10 -6} /K, dimensional stability as an electronic material such as a flexible substrate is deteriorated, and heat resistance tends to also decrease.

[hereditary tangent]

When the resin film is applied, for example, as an insulating resin layer of a circuit board, the entire film is measured by a split post dielectric resonator (SPDR) in order to reduce dielectric loss during transmission of high-frequency signals. It is preferable that it is 0.005 or less, and, as for the dielectric loss tangent (Tanδ) in 3-20 GHz, it is more preferable that it is 0.004 or less. In order to improve the transmission loss of the circuit board, it is particularly important to control the dielectric loss tangent of the insulating resin layer, and by setting the dielectric loss tangent within the above range, the effect of lowering the transmission loss is increased. Therefore, when applying a resin film as an insulating resin layer of a high frequency circuit board, for example, a transmission loss can be reduced efficiently. When the dielectric loss tangent in 3-20 GHz exceeds 0.005, when a resin film is applied as an insulating resin layer of a circuit board, it will become easy to generate|occur|produce the problem, such as an electrical signal loss becoming large on the transmission path of a high frequency signal. Although the lower limit in particular of the dielectric loss tangent in 3-20 GHz is not restrict|limited, The physical property control in the case of applying a resin film as an insulating resin layer of a circuit board needs to be considered.

[Relative permittivity]

In the case of applying the resin film as an insulating resin layer of a circuit board, for example, in order to ensure impedance matching, the entire film is 3 to 20 GHz when measured by a split post dielectric resonator (SPDR). It is preferable that the dielectric constant is 3.1 or less. When the relative permittivity in 3 to 20 GHz exceeds 3.1, when the resin film is applied as an insulating resin layer of a circuit board, it leads to deterioration of dielectric loss, and the loss of electric signals on the transmission path of high-frequency signals increases. problems are likely to occur.

[Metal Covered Laminate]

The metal-clad laminate of the present embodiment is a metal-clad laminate including an insulating resin layer and a metal layer laminated on at least one surface of the insulating resin layer, and at least one of the insulating resin layers contains the resin film. The metal-clad laminate may be a single-sided metal-clad laminate having a metal layer on only one side of the insulating resin layer, or a double-sided metal-clad laminate having a metal layer on both surfaces of the insulating resin layer.

[Insulation resin layer]

The insulating resin layer is composed of a single layer or a plurality of layers, and includes a layer including the resin film. For example, the said resin film may form the non-thermoplastic polyimide layer as a main layer of the insulating resin layer for ensuring a mechanical characteristic and a thermal property. Moreover, the said resin film may form the thermoplastic polyimide layer as an adhesive bond layer which bears adhesive strength with metal layers, such as copper foil. In addition, a "main layer" means the layer which occupies 50% or more of the total thickness of an insulating resin layer.

In addition, the metal-clad laminated board of this embodiment does not exclude using the adhesive agent for bonding the polyimide layer containing an inorganic filler, and metal foil. However, in the case of interposing the adhesive layer in a double-sided metal-clad laminate having a metal layer on both surfaces of the insulating resin layer, the thickness of the adhesive layer is preferably less than 30% of the thickness of the entire insulating resin layer so as not to impair dielectric properties. and it is more preferable to set it as less than 20%. In the case of interposing the adhesive layer in a single-sided metal-clad laminate having a metal layer on only one side of the insulating resin layer, the thickness of the adhesive layer is preferably less than 15% of the thickness of the entire insulating resin layer so as not to impair dielectric properties. and it is more preferable to set it as less than 10%. Moreover, since an adhesive layer comprises a part of an insulating resin layer, it is preferable that it is a polyimide layer. When a crystalline silica containing polyimide layer comprises the main layer of an insulating resin layer, it is preferable that the glass transition temperature of a crystalline silica containing polyimide layer shall be 300 degreeC or more from a viewpoint of providing heat resistance. In order to make a glass transition temperature into 300 degreeC or more, it becomes possible by appropriately selecting the above-mentioned acid dianhydride and diamine component which comprise a polyimide.

As a method of manufacturing a metal-clad laminate using a resin film as an insulating resin layer, for example, a method of heat-compressing a metal foil directly on a resin film or through an optional adhesive, or a method such as metal vapor deposition on a resin film to form a metal layer and a method of forming In addition, a double-sided metal-clad laminate is, for example, a method of forming a single-sided metal-clad laminate by forming a single-sided metal-clad laminate, then making the polyimide layers face each other and compressing them by hot pressing, or a metal foil on the polyimide layer of a single-sided metal-clad laminate. It can be obtained by a method of forming by pressing or the like.

[Metal layer]

The material of the metal layer is not particularly limited, and for example, copper, stainless steel, iron, nickel, beryllium, aluminum, zinc, indium, silver, gold, tin, zirconium, tantalum, titanium, lead, magnesium, manganese, and alloys thereof. and the like. Among these, copper or a copper alloy is especially preferable. A metal layer may contain metal foil, and the thing which metal-deposited on the film, the thing which printed the paste, etc. may be sufficient as it. Moreover, from the point which can apply|coat a resin composition directly, even if it is metal foil or a metal plate, it can be used, and copper foil or a copper plate is preferable.

The thickness of the metal layer is not particularly limited because it is appropriately set according to the purpose of use of the metal-clad laminate. For example, the thickness of the metal layer is preferably in the range of 5 µm to 3 mm, more preferably in the range of 12 µm to 1 mm. When the thickness of a metal layer is less than 5 micrometers, there exists a possibility that problems, such as wrinkles, may arise at the time of conveyance in manufacture of a metal clad laminated board, etc. Conversely, when the thickness of the metal layer exceeds 3 mm, it is hard and the workability deteriorates. About the thickness of a metal layer, a thick thing is suitable for uses, such as a vehicle-mounted circuit board, and a thin metal layer is suitable for uses, such as a circuit board for LEDs, in general.

Example

Examples are shown below, and the characteristics of the present invention will be described in more detail. However, the scope of the present invention is not limited to the Examples. In addition, in the following examples, unless otherwise indicated, various measurements and evaluation are based on the following.

[Measurement of viscosity]

The viscosity of the resin solution was measured at 25°C using an E-type viscometer (manufactured by Brookfield, trade name; DV-II+Pro). The rotational speed was set so that the torque became 10% to 90%, and the value when the viscosity was stabilized was read 1 minute after starting the measurement.

[Measurement of dielectric constant and dielectric loss tangent]

<Silica Particles>

Relative permittivity measurement mode using a vector network analyzer (manufactured by Keysight Technologies, trade name; Vector Network Analyzer E8363C) and a dielectric constant measurement apparatus manufactured by Kanto Denshi Oyo Kaihatsu by a cavity resonator perturbation method; It was set to TM020, and the dielectric constant (ε1) and dielectric loss tangent (Tanδ1) of the silica particles at a frequency of 10 GHz were measured. In addition, the silica particle was powdery, and it filled and measured the sample tube tube (inner diameter 1.68 mm, outer diameter 2.28 mm, height 8 cm).

<Resin Film>

The relative dielectric constant (ε1) and dielectric loss tangent (Tanδ1) of the resin film at a frequency of 10 GHz were measured using a Vector Network Analyzer (manufactured by Keysight Technologies, trade name; Vector Network Analyzer E8363C) and an SPDR resonator. In addition, the resin film used for a measurement is temperature; 24-26°C, humidity; It is allowed to stand for 24 hours under the conditions of 45 to 55%.

[Measurement of coefficient of thermal expansion (CTE)]

A resin film having a size of 3 mm × 20 mm was heated from 30° C. to 265° C. at a constant temperature increase rate while applying a load of 5.0 g using a thermomechanical analyzer (manufactured by Bruker, trade name; 4000SA), and further After holding at the temperature for 10 minutes, it was cooled at a rate of 5°C/min to obtain an average coefficient of thermal expansion (coefficient of thermal expansion, CTE) from 200°C to 100°C.

[Measurement of particle diameter]

Using a laser diffraction particle size distribution analyzer (manufactured by Malvern, trade name; Master Sizer 3000), using water as a dispersion medium and a particle refractive index of 1.54, measurement of the particle diameter of silica particles by a laser diffraction/scattering measurement method was performed. was done.

[Measurement of true specific gravity]

The true specific gravity of the silica particles was measured by a pycnometer method (liquid phase displacement method) using a continuous automatic powder true density measuring apparatus (manufactured by Seishin Industrial Co., Ltd., trade name; AUTO TRUE DENSERMAT-7000).

[Measurement of cristobalite crystal phase]

X-ray diffraction apparatus; using (Brewer keosa product name D2PHASER), the diffraction angle (Cu, Kα) 2θ = 10 ° to 90 ° all the diffraction pattern derived from SiO ₂ in the range of (peak position and peak width, and peak intensity), the total area of all peaks derived _{from SiO 2 is calculated.} Next, specific, and calculating the total area of the overall peak in the cristobalite determining the peak position is derived on the cristobalite crystal was determined the ratio (% by weight) to the total area of all peaks derived from SiO _2. In addition, for the attribution of each peak, the database of the International Center for Diffraction Data (ICDD) was referred.

[Measurement of circularity]

The average circularity of silica particles by dynamic flow particle image analysis was measured using a wet flow particle size/shape analyzer (manufactured by Sysmex, trade name: FPIA-3000).

[Evaluation of bendability]

In accordance with JISK5600-5-1, the center of the long side of the 5 cm x 10 cm resin film is uniformly bent over 1 to 2 seconds as if wound around a 5 mm φ metal rod, and the resin film breaks even when bent at 180 ° C. Or the thing which a crack did not generate|occur|produce was made into "good|favorableness", and the thing which fracture|rupture or crack generate|occur|produced was made into "impossible".

The symbol used for a synthesis example, a comparative example, and an Example shows the following compounds.

PMDA: pyromellitic dianhydride

BPDA: 3,3',4,4'-biphenyltetracarboxylic dianhydride

BAPP: 2,2-bis[4-(4-aminophenoxy)phenyl]propane

m-TB: 2,2'-dimethyl-4,4'-diaminobiphenyl

DMAc: N,N-dimethylacetamide

Filler 1: Manufactured by Nittetsu Chemicals & Materials. product name; CR10-20 (spherical cristobalite silica powder, circularity; 0.98, cristobalite crystal phase; 98% by weight, true specific gravity; 2.33, D ₅₀ ; 10.8 µm, dielectric constant at 10 GHz; 3.16, dielectric loss tangent at 10 GHz; 0.0008)

Filler 2: manufactured by Nittetsu Chemicals & Materials. product name; SC70-2 (spherical amorphous silica powder, circularity; 0.98, true specific gravity; 2.21, D ₅₀ ; 11.7 µm, relative dielectric constant at 10 GHz; 3.08, dielectric loss tangent at 10 GHz; 0.0015)

Filler 3: Nittetsu Chemical & Materials, brand name; SP40-10 (spherical amorphous silica powder, true spherical shape, true specific gravity; 2.21, D ₅₀ ; 2.5 µm, relative dielectric constant at 10 GHz; 2.78, dielectric loss tangent at 10 GHz; 0.0030)

(Synthesis Example 1)

In a 300 ml separable flask, 24 g of BAPP (60 mmol) and 230 g of DMAc were charged, and the mixture was stirred at room temperature under a nitrogen stream. After complete dissolution, 6.5 g of PMDA (30 mmol) and 8.7 g of BPDA (30 mmol) were added, followed by stirring at room temperature for 18 hours to obtain a polyamic acid solution A. The obtained polyamic acid solution A had a viscosity of 21,074 cps.

(Synthesis Example 2)

In a 300 ml separable flask, 19 g of m-TB (90 mmol) and 230 g of DMAc were added, and the mixture was stirred at room temperature under a nitrogen stream. After complete dissolution, 16 g of PMDA (72 mmol) and 5.3 g of BPDA (18 mmol) were added, followed by stirring at room temperature for 18 hours to obtain a polyamic acid solution B. The obtained polyamic acid solution B had a viscosity of 22,400 cps.

[Example 1]

58.7 g of polyamic acid solution A and 6.1 g of Filler 1 were mixed and stirred until a visually uniform solution was obtained to prepare polyamic acid composition 1a (viscosity; 23,000 cps).

The polyamic acid composition 1a was apply|coated on the copper foil 1 (electrolytic copper foil, thickness; 12 micrometers), and it dried at 130 degreeC for 3 minutes. Thereafter, a stepwise heat treatment was performed from 155°C to 360°C to imidize it, and the metal-clad laminate 1b was prepared. The copper foil of the metal-clad laminated board 1b was removed by etching, and the resin film 1c was prepared. The dielectric constant of the resin film 1c (thickness; 51.6 micrometers) was 3.04, the dielectric loss tangent was 0.0044, and the bendability was "good".

[Example 2]

70.0 g of polyamic acid solution B and 7.8 g of Filler 1 were mixed and stirred until a visually uniform solution was obtained to prepare polyamic acid composition 2a (viscosity; 24,800 cps).

It carried out similarly to Example 1, and prepared the metal-clad laminated board 2b and the resin film 2c. The dielectric constant of the resin film 2c (thickness; 46.1 µm) was 2.78, the dielectric loss tangent was 0.0037, the CTE was 34 ppm/K, and the bendability was “good”.

[Example 3]

60.0 g of polyamic acid solution B and 20.0 g of Filler 1 were mixed and stirred until a visually uniform solution was obtained to prepare polyamic acid composition 3a (viscosity: 28, 400 cps).

It carried out similarly to Example 1, and prepared the metal-clad laminated board 3b and the resin film 3c. The dielectric constant of the resin film 3c (thickness; 78.1 µm) was 2.71, the dielectric loss tangent was 0.0028, the CTE was 34 ppm/K, and the bendability was “good”.

[Example 4]

55.0 g of polyamic acid solution B and 36.6 g of Filler 1 were mixed and stirred until a visually uniform solution was prepared to prepare polyamic acid composition 4a (viscosity; 29, 900 cps).

It carried out similarly to Example 1, after preparing the metal clad laminated board 4b, the resin film 4c was prepared. The dielectric constant of the resin film 4c (thickness; 117.8 µm) was 2.56, the dielectric loss tangent was 0.0015, the CTE was 31 ppm/K, and the bendability was "impossible".

[Example 5]

50.0 g of polyamic acid solution B, 6.6 g of filler 1 and 25.3 g of filler 2 were mixed and stirred until a visually uniform solution was prepared, thereby preparing polyamic acid composition 5a (viscosity: 31,000 cps). did.

It carried out similarly to Example 1, after preparing the metal clad laminated board 5b, the resin film 5c was prepared. The dielectric constant of the resin film 5c (thickness; 115.5 µm) was 2.71, the dielectric loss tangent was 0.0017, the CTE was 27 ppm/K, and the bendability was "impossible".

(Comparative Example 1)

The polyamic acid solution A was apply|coated on the copper foil 1, and it dried at 90 degreeC for 1 minute and 130 degreeC for 5 minutes. Thereafter, a stepwise heat treatment was performed from 155°C to 360°C to imidize it, and the metal-clad laminate A1 was prepared.

It carried out similarly to Example 1, the copper foil of metal-clad laminated board A1 was etched away, and resin film A1 was prepared. The dielectric constant of the resin film A1 (thickness; 41.4 µm) was 3.16, the dielectric loss tangent was 0.0062, the CTE was 51 ppm/K, and the bendability was “good”.

(Comparative Example 2)

56.2 g of polyamic acid solution A and 5.5 g of filler 2 were mixed, and stirred until it became a uniform solution visually to prepare polyamic acid composition A2 (viscosity; 23,600 cps).

It carried out similarly to Example 1, and prepared metal-clad laminated board A2 and resin film A2. The dielectric constant of the resin film A2 (thickness; 50.7 micrometers) was 3.04, the dielectric loss tangent was 0.0047, and the bendability was "good".

(Comparative Example 3)

56.2 g of polyamic acid solution A and 5.5 g of filler 3 were mixed and stirred until a visually uniform solution was prepared, thereby preparing polyamic acid composition A3 (viscosity: 30,000 cps).

It carried out similarly to Example 1, and after preparing metal clad laminated board A3, resin film A3 was prepared. The dielectric constant of the resin film A3 (thickness; 45.6 µm) was 3.25, the dielectric loss tangent was 0.0052, the CTE was 41, and the bendability was “good”.

The above results are put together and shown in Table 1 and Table 2.

The crystal phase in Table 1 means the ratio of the cristobalite crystal phase, and the filler ratio means the ratio (weight ratio) of the filler to the total of the polyamic acid solution (varnish) or the total solid content of the organic compound and the silica particles. (However, it was calculated by converting the weight of polyamic acid into polyimide after imidization). In addition, the filler content rate in Table 2 means the ratio (weight ratio) of the filler with respect to a resin film.

It was confirmed that the polyamic acid composition 1a of Example 1 had a low viscosity compared with the polyamic acid compositions A2 and A3 of Comparative Examples 2 and 3, respectively. In addition, in the resin film 1c of Example 1, compared with the resin films A2 to A3 of Comparative Examples 2 to 3, the relative dielectric constant and dielectric loss tangent were lowered. .

From the above result, it was confirmed that the resin film which concerns on this embodiment can be used suitably as a material for high frequency compatible flexible printed circuit boards.

As mentioned above, although embodiment of this invention was described in detail for the purpose of illustration, this invention is not restrict|limited to the said embodiment, and various deformation|transformation is possible.

Claims (10)

A resin composition comprising a solid content of an organic compound containing polyamic acid or polyimide, and silica particles,
The content of the silica particles is in the range of 10 to 85% by weight based on the total amount of the solid content and the total of the silica particles (however, polyamic acid is converted into imidized polyimide.);
The total area of the peaks derived from the cristobalite crystal phase and the quartz crystal phase with respect to the total peak area derived from _{SiO 2} in the range of 2θ = 10° to 90° of the X-ray diffraction spectrum by CuKα ray as the whole of the silica particles. The resin composition, characterized in that the ratio of 20% by weight or more. According to claim 1,
_{The resin composition in which the median diameter D 50} in the frequency distribution curve of the said silica particle obtained by volume-based particle size distribution measurement by the laser diffraction scattering method exists in the range of 6-20 micrometers. 3. The method of claim 1 or 2,
The resin composition in which 90 weight% or more of the particle|grains whose particle diameter in the said silica particle is 3 micrometers or more is 0.7 or more circularity. 4. The method according to any one of claims 1 to 3,
The resin composition in which 90 weight% or more of the said silica particle is 2.3 or more of true specific gravity. It is a resin film having a single or multiple polyimide layers,
At least one of the polyimide layers is a crystalline silica-containing polyimide layer formed of the resin composition according to any one of claims 1 to 4, and the crystalline silica-containing polyimide layer has a thickness of 15 µm. to a resin film in the range of 200 μm. 6. The method of claim 5,
The resin film in which the ratio of the thickness of the said crystalline silica containing polyimide layer with respect to the thickness of the whole resin film is 50 % or more. 7. The method of claim 5 or 6,
A resin film having a dielectric constant of 3.1 or less at a frequency of 3 to 20 GHz as measured by a split post dielectric resonator (SPDR). 8. The method according to any one of claims 5 to 7,
A resin film having a dielectric loss tangent of 0.005 or less at a frequency of 3 to 20 GHz as measured by a split post dielectric resonator (SPDR). 9. The method according to any one of claims 5 to 8,
A resin film having a coefficient of thermal expansion of 50 ppm/K or less. A metal-clad laminate comprising an insulating resin layer and a metal layer laminated on at least one surface of the insulating resin layer,
At least one layer of the said insulating resin layer contains the resin film in any one of Claims 5-9, The metal-clad laminated board characterized by the above-mentioned.