JP2023146985A - Thermoplastic polyester composition, adhesive, resin film, laminate, coverlay film, copper foil with resin, metal clad laminate and circuit board - Google Patents

Abstract

To provide a thermoplastic polyester composition capable of forming an insulating resin layer with excellent soldering heat resistance, using thermoplastic polyester, without compromising dielectric properties.SOLUTION: A thermoplastic polyester composition contains (A) a thermoplastic polyester and (B) a magnesium oxide filler having an average particle diameter in the range of 30 nm to 10 μm, and the content of the (B) component to the total amount of the (A) component and the (B) component is in the range of 1 to 50 weight%, and the (B) component has no peak derived from magnesium hydroxide detected in an X-ray diffraction measurement.SELECTED DRAWING: None

Description

The present invention relates to thermoplastic polyester compositions, resin films, laminates, coverlay films, resin-coated copper foils, metal-clad laminates, and circuit boards useful as adhesives in circuit boards such as printed wiring boards.

In recent years, as electronic devices have become smaller, lighter, and space-saving, flexible printed circuit boards (FPCs) have become thinner, lighter, more flexible, and have excellent durability even after repeated bending. Demand for circuits is increasing. FPC can be mounted three-dimensionally and with high density even in a limited space, so it can be used, for example, in the wiring of moving parts of electronic devices such as HDDs, DVDs, and mobile phones, as well as parts such as cables and connectors. It is expanding.

In addition to the above-mentioned increase in density, as the performance of equipment has progressed, it is also necessary to support higher frequencies of transmission signals. In information processing and communications, efforts are being made to increase the transmission frequency in order to transmit and process large amounts of information, and printed circuit board materials are improving transmission by thinning the insulating layer and improving the dielectric properties of the insulating resin layer. There is a need to reduce losses. In the future, FPCs and adhesives that can handle higher frequencies will be required, and reducing transmission loss will become important. Regarding the improvement of the dielectric properties of printed circuit board materials, a resin composition has been proposed in which spherical silica whose surface has been treated with a surface treatment agent having a polymerizable unsaturated bond is blended with an ethylene-propylene-diene copolymer ( For example, Patent Document 1).

By the way, thermoplastic polyester is used in a wide range of fields such as mechanical parts, electrical/electronic parts, and automobile parts due to its excellent properties such as injection moldability and mechanical properties. It is expected to be applied to high-frequency components such as next-generation high-speed communication antennas that support ultra-low-latency communications and in-vehicle radars that support self-driving cars. Therefore, thermoplastic polyester is required to have low dielectric properties (low dielectric constant, low dielectric loss tangent) that can suppress dielectric loss.

International publication WO2019/026927

Generally, the blending of a filler into an insulating resin layer acts in the direction of weakening the adhesiveness with the metal layer and other insulating resin layers. In a circuit board such as an FPC, if the adhesion between an insulating resin layer and a wiring layer is low, misalignment or peeling of the wiring may occur, leading to a decrease in the reliability of the circuit board. Therefore, in circuit boards, it is very important to maintain adhesion between the insulating resin layer and the wiring layer, and it is required to ensure solder heat resistance. In addition, thermoplastic polyester has a dielectric loss in a high frequency band due to polar groups in its molecular structure, so there is a limit to how low the dielectric can be made.

Therefore, an object of the present invention is to provide a resin composition that uses thermoplastic polyester and can form an insulating resin layer with excellent solder heat resistance without impairing dielectric properties.

The thermoplastic polyester composition of the present invention comprises the following components (A) and (B);
(A) a thermoplastic polyester; and (B) a magnesium oxide filler having an average particle size within the range of 30 nm to 10 μm;
and the content of the component (B) with respect to the total amount of the component (A) and the component (B) is within the range of 1 to 50% by weight, and the component (B) is determined by X-ray diffraction measurement. It is characterized by the fact that no peak derived from magnesium hydroxide is detected.

The resin film of the present invention is a resin film including a filler-containing thermoplastic resin layer,
The filler-containing thermoplastic resin layer contains the following (A) component and (B) component;
(A) a thermoplastic polyester; and (B) a magnesium oxide filler having an average particle size within the range of 30 nm to 10 μm;
and the content of the component (B) with respect to the total amount of the component (A) and the component (B) is within the range of 1 to 50% by weight, and the component (B) is determined by X-ray diffraction measurement. It is characterized by the fact that no peak derived from magnesium hydroxide is detected.

In the thermoplastic polyester composition and resin film of the present invention, the magnesium oxide filler may contain 95.0% by weight or more of magnesium oxide.

In the thermoplastic polyester composition and resin film of the present invention, the magnesium oxide filler has a weight loss rate at 350°C when heated from 30°C to 450°C at a temperature increase rate of 10°C per minute in thermogravimetric analysis measurement. may be 2% or less.

In the thermoplastic polyester composition and resin film of the present invention, the thermoplastic polyester may contain an aliphatic dicarboxylic acid residue or an aliphatic diol residue, and the aliphatic dicarboxylic acid residue may contain a dimer acid residue. and the aliphatic diol residue may be a dimer diol residue.

The adhesive of the present invention contains the thermoplastic polyester composition described above, and is preferably used in electronic equipment that transmits, receives, or transmits high-frequency signals.

The laminate of the present invention is a laminate comprising a base material and an adhesive layer laminated on at least one surface of the base material, wherein the adhesive layer is made of the resin film described above. shall be.

The coverlay film of the present invention is a coverlay film having a coverlay film material layer and an adhesive layer laminated on the coverlay film material layer, wherein the adhesive layer is made from the resin film. It is characterized by becoming.

The resin-coated copper foil of the present invention is a resin-coated copper foil in which an adhesive layer and a copper foil are laminated, and the adhesive layer is made of the resin film described above.

The metal-clad laminate of the present invention is a metal-clad laminate having an insulating resin layer and a metal layer laminated on at least one surface of the insulating resin layer, wherein at least one of the insulating resin layers is , characterized in that it is made of the above resin film.

The circuit board of the present invention is formed by wiring the metal layer of the metal clad laminate.

Since the thermoplastic polyester composition of the present invention contains a thermoplastic polyester and a magnesium oxide filler having an average particle size within the range of 30 nm to 10 μm, it has practically sufficient soldering heat resistance while maintaining a low dielectric loss tangent. It is possible to form a resin film with excellent adhesive properties. Therefore, the thermoplastic polyester composition and resin film of the present invention can be particularly suitably used, for example, as circuit board materials such as FPCs in electronic devices that require high-speed signal transmission.

2 is a chart showing the results of thermogravimetric analysis measurement in Test Example 1. 3 is a chart showing the results of X-ray diffraction measurement in Test Example 2.

Embodiments of the present invention will be described below.

[Thermoplastic polyester composition]
The thermoplastic polyester composition of the present invention (hereinafter sometimes simply referred to as "resin composition") comprises the following components (A) and (B);
(A) a thermoplastic polyester; and (B) a magnesium oxide filler having an average particle size within the range of 30 nm to 10 μm;
Contains.

<(A) component: thermoplastic polyester>
The thermoplastic polyester of component (A) is preferably a non-liquid crystal polyester, and non-liquid crystal refers to one that does not exhibit anisotropy when melted. Furthermore, the thermoplastic polyester contains at least one residue selected from the group consisting of dicarboxylic acids or ester-forming derivatives thereof, diols or ester-forming derivatives thereof, hydroxycarboxylic acids or ester-forming derivatives thereof, and lactones. It is a polymer or copolymer having the main structural unit. Here, the main structural unit means that it contains at least 50 mol% of at least one type of residue selected from the group consisting of the above in all structural units, preferably 80 mol% of these residues. or more. From the viewpoint of mechanical properties and heat resistance, polymers or copolymers whose main structural units are residues of dicarboxylic acids or their ester-forming derivatives and diols or their ester-forming derivatives are preferred.

Examples of dicarboxylic acids include terephthalic acid, isophthalic acid, phthalic acid, 2,6-naphthalene dicarboxylic acid, 1,5-naphthalene dicarboxylic acid, bis(p-carboxyphenyl)methane, 1,4-anthracene dicarboxylic acid, 1, 5-anthracene dicarboxylic acid, 1,8-anthracene dicarboxylic acid, 2,6-anthracene dicarboxylic acid, 9,10-anthracene dicarboxylic acid, 4,4'-diphenyl ether dicarboxylic acid, 5-tetrabutylphosphonium isophthalic acid, 5-sodium Aromatic dicarboxylic acids such as sulfoisophthalic acid, aliphatic dicarboxylic acids such as oxalic acid, succinic acid, adipic acid, sebacic acid, azelaic acid, dodecanedioic acid, malonic acid, glutaric acid, dimer acid (including hydrogenated dimer acid) Examples include alicyclic dicarboxylic acids such as acids, 1,3-cyclohexanedicarboxylic acid, and 1,4-cyclohexanedicarboxylic acid. Further, as long as ester formation is possible, derivatives thereof (ester-forming derivatives) may be used. These may be used alone or in combination of two or more.

In addition, examples of the above-mentioned diols include ethylene glycol, propylene glycol, 1,4-butanediol, neopentyl glycol, 1,5-pentanediol, 1,6-hexanediol, decamethylene glycol, cyclohexanedimethanol, and cyclohexanediol. , aliphatic or alicyclic glycols having 2 to 20 carbon atoms such as dimer diol (including hydrogenated dimer diol), molecular weight 200 to 100 such as polyethylene glycol, poly-1,3-propylene glycol, polytetramethylene glycol, Examples include aromatic dioxy compounds such as 000 long chain glycol, 4,4'-dihydroxybiphenyl, hydroquinone, t-butylhydroquinone, bisphenol A, bisphenol S, and bisphenol F. Further, as long as ester formation is possible, derivatives thereof (ester-forming derivatives) may be used. They may be used alone or in combination of two or more.

The thermoplastic polyester has at least one of an aliphatic dicarboxylic acid residue and an aliphatic diol residue as the main structural unit of the thermoplastic polyester, which improves the dielectric properties of the thermoplastic polyester and has a low glass transition temperature. It is possible to alleviate internal stress by improving the thermocompression bonding properties by reducing the Tg (lower Tg) and lowering the elastic modulus. From this viewpoint, the aliphatic dicarboxylic acid residue is preferably a dimer acid residue, and the aliphatic diol residue is preferably a dimer diol residue.

Dimer acid is mainly composed of a dimer of unsaturated fatty acids having 10 to 26 carbon atoms, preferably a dimer of unsaturated fatty acids having 12 to 24 carbon atoms, and more preferably a dimer of unsaturated fatty acids having 14 to 26 carbon atoms. It is a dimer of 22 unsaturated fatty acids. Specifically, it is a dicarboxylic acid derived from unsaturated fatty acids such as oleic acid, linoleic acid, linolenic acid, and erucic acid. Note that the term "main component" used herein means a component whose content is 90% by weight or more, preferably 95% by weight or more, and more preferably 98% by weight.

Since the skeleton derived from dimer acid is a macromolecule aliphatic, it is possible to increase the molar volume of the molecule and relatively reduce the number of polar groups in the thermoplastic polyester. It is thought that such characteristics of the dimer acid contribute to improving the dielectric properties by reducing the relative dielectric constant and the dielectric loss tangent while suppressing a decrease in the heat resistance of the thermoplastic polyester. In addition, it has two freely movable hydrophobic chains with 7 to 9 carbon atoms and two chain aliphatic groups with a length close to 18 carbon atoms, which not only gives flexibility to thermoplastic polyester. Since thermoplastic polyester can be made to have an asymmetrical chemical structure or a non-planar chemical structure, it is thought that it is possible to lower the dielectric constant of thermoplastic polyester.

When using dimer acid as a copolymerization component of thermoplastic polyester, the content is preferably in the range of 10 to 100 mol%, more preferably 20 to 100% by mole based on the total polycarboxylic acids including dicarboxylic acids. It is within the range of 99 mol%, more preferably within the range of 35 to 90 mol%, most preferably within the range of 50 to 80 mol%. If the content of dimer acid is less than 10 mol%, flexibility tends to decrease.

Dimer diol is generally a diol derived from dimer acid, and when dimer diol is used as a copolymerization component of thermoplastic polyester, the content is 5 to 100 mol% based on the entire polyhydric alcohol containing diol. It is preferably within the range of, more preferably within the range of 10 to 80 mol%, and even more preferably within the range of 15 to 50 mol%. If the content of dimer diol is less than 5 mol%, flexibility tends to decrease.

The total content of dimer acid residues and dimer diol residues relative to the total of all dicarboxylic acid residues and all diol residues is preferably in the range of 5 to 100 mol%, more preferably in the range of 10 to 80 mol%. More preferably, it is within the range of 20 to 70 mol%. If the total content of dimer acid residues and dimer diol residues is less than 5 mol %, hygroscopicity tends to increase and dielectric properties tend to deteriorate.

Further, the molar ratio of the content of dimer diol residues to the total content of dimer acid residues and dimer diol residues is preferably 0.6 or more, more preferably 0.8 or more, and still more preferably 0.9. Above, 1 is most preferable. By setting such a molar ratio, long-term durability under a moist heat environment is improved.

The total content of dimer acid residues and dimer diol residues based on the entire thermoplastic polyester is preferably in the range of 10 to 80% by weight, more preferably in the range of 20 to 70% by weight, and even more preferably 30 to 60% by weight. It is preferably within the range of weight %. If the total content of dimer acid residues and dimer diol residues is less than 10% by weight, hygroscopicity tends to increase and dielectric properties tend to deteriorate.

In addition, from the viewpoint of further improving mechanical properties and heat resistance, it is preferable that the structural unit of the thermoplastic polyester contains at least one of an aromatic dicarboxylic acid residue and an aromatic diol residue, such as a terephthalic acid residue and an isophthalic acid residue. It is more preferable to contain a terephthalic acid residue or an isophthalic acid residue, and it is particularly preferable to contain a terephthalic acid residue or an isophthalic acid residue.

When aromatic dicarboxylic acid is used as a copolymerization component of thermoplastic polyester, the content is preferably in the range of 1 mol% or more and less than 50 mol%, more preferably It is preferably within the range of 5 to 45 mol%, more preferably within the range of 10 to 40 mol%, particularly preferably within the range of 20 to 40 mol%. When the content of aromatic dicarboxylic acid is less than 1 mol %, the cohesive force decreases, resulting in a decrease in adhesive strength and a tendency for sufficient adhesive performance to not be obtained. On the other hand, if the content of aromatic dicarboxylic acid is 50 mol % or more, initial adhesiveness (tackiness) tends to decrease.

When aromatic diol is used as a copolymerization component of thermoplastic polyester, the content is preferably within the range of 1 to 50 mol%, more preferably 5 to 40 mol%, based on the entire polyhydric alcohol. It is preferably within the range of 10 to 30 mol%, more preferably within the range of 10 to 30 mol%. If the aromatic diol content is less than 1 mol %, the cohesive force will be lowered, resulting in a lower adhesive strength and a tendency for sufficient adhesive performance to not be obtained. On the other hand, if the content of aromatic dicarboxylic acid exceeds 50 mol%, initial adhesiveness tends to decrease.

Furthermore, for the purpose of introducing a branched skeleton, the thermoplastic polyester may contain at least one selected from the group consisting of a trifunctional or more functional polycarboxylic acid residue and a trifunctional or more functional polyhydric alcohol residue as a structural unit of the thermoplastic polyester. preferable. In particular, when a cured coating film is obtained by reacting with a curing agent, the introduction of a branched skeleton increases the concentration of end groups (reaction points) in the resin, making it possible to obtain a strong coating film with a high crosslinking density.

The content of trifunctional or higher polyhydric carboxylic acid residues relative to the entire polyhydric carboxylic acid residues or the content of trifunctional or higher functional polyhydric alcohol residues relative to the entire polyhydric alcohol residues are each preferably 0.1 It is preferably in the range of 5 to 5 mol%, more preferably in the range of 0.3 to 3 mol%, even more preferably in the range of 0.5 to 2 mol%. By keeping these within the above range, it is possible to improve the mechanical properties of the coating film, such as elongation at break, and to improve the adhesive strength.

Examples of trifunctional or higher-functional polycarboxylic acids that can be used as a copolymerization component of thermoplastic polyester include trimellitic acid, trimesic acid, ethylene glycol bis(anhydrotrimellitate), and glycerol tris(anhydrotrimellitate). ), trimellitic anhydride, pyromellitic dianhydride, oxydiphthalic dianhydride, 3,3',4,4'-benzophenonetetracarboxylic dianhydride, 3,3',4,4'-diphenyl Tetracarboxylic dianhydride, 3,3',4,4'-diphenylsulfonetetracarboxylic dianhydride, 4,4'-(hexafluoroisopropylidene)diphthalic dianhydride, 2,2'-bis[ (dicarboxyphenoxy)phenyl] Propane dianhydride, etc., and these can be used alone or in combination of two or more.

Examples of trifunctional or higher-functional polyhydric alcohols that can be used as a copolymerization component of thermoplastic polyester include glycerin, trimethylolethane, trimethylolpropane, pentaerythritol, etc. More than one species can be used.

The weight average molecular weight (Mw) of the thermoplastic polyester is preferably within the range of 8,000 to 300,000, more preferably within the range of 20,000 to 200,000, even more preferably 30,000 to 100,000. Good within range. If the weight average molecular weight is less than 8,000, low hygroscopicity, tack-free property, and long-term durability in a moist heat environment will be insufficient, making it difficult to use when producing laminates such as metal-clad laminates and wiring boards. Problems such as the adhesive layer flowing and seeping out during press processing tend to occur. On the other hand, if the weight average molecular weight exceeds 300,000, the initial adhesion will be insufficient and the solution viscosity during application will be too high, making it difficult to obtain a uniform coating film. From this viewpoint, the peak top molecular weight (Mp) of the thermoplastic polyester is preferably within the range of 5,000 to 150,000, more preferably within the range of 10,000 to 100,000, even more preferably 20, It is preferably within the range of 000 to 70,000.

The water absorption rate of the thermoplastic polyester is preferably 2% by weight or less, more preferably 1% by weight or less, still more preferably 0.8% by weight or less. If the water absorption rate is too high, the wet heat durability and insulation reliability will decrease, and the dielectric properties will tend to decrease.

In addition, from the viewpoint of low hygroscopicity and long-term durability in a moist heat environment, the ester bond concentration of the thermoplastic polyester is preferably in the range of 2 to 7 mmol/g, more preferably in the range of 2 to 6 mmol/g. More preferably, it is within the range of 3 to 5 mmol/g. If the ester bond concentration is too low, initial adhesion will be insufficient. Note that, for example, the concentration of polar groups such as amide groups, imide groups, urethane groups, urea groups, ether groups, and carbonate groups should be lower because they reduce hygroscopicity, long-term durability in a moist heat environment, and dielectric properties. is preferable, and the total concentration of these polar groups is preferably 3 mmol/g or less, more preferably 2 mmol/g or less, still more preferably 1 mmol/g or less.

The glass transition temperature of the thermoplastic polyester is preferably within the range of 10 to 130°C. If the glass transition temperature is too low, the initial adhesion and tack-free properties tend to be insufficient, and if the glass transition temperature is too high, the initial adhesion and flexibility tend to be insufficient.

Thermoplastic polyesters can be manufactured by known methods. For example, it is produced by subjecting polycarboxylic acids and polyhydric alcohols to an esterification reaction, if necessary in the presence of a catalyst, to obtain a prepolymer, followed by polycondensation, and then depolymerization. can do. The reaction temperature for esterification is, for example, in the range of 180 to 280°C, and the reaction time is in the range of 60 minutes to 8 hours. Further, the temperature in polycondensation is, for example, within the range of 220 to 280°C, and the reaction time is within the range of 20 minutes to 4 hours. Note that the polycondensation is preferably carried out under reduced pressure.

Further, from the viewpoint of improving adhesiveness, it is preferable to use a trivalent or higher polyhydric carboxylic acid having 0 or 1 acid anhydride group for depolymerization. Examples of such polycarboxylic acids include trimellitic acid, trimellitic anhydride, hydrogenated trimellitic anhydride, trimesic acid, and the like. Among these, trivalent or higher polyhydric carboxylic acids having one acid anhydride group are preferred, such as trimellitic anhydride, hydrogenated trimellitic anhydride, etc., and trimellitic anhydride is particularly preferred. . The depolymerization temperature is, for example, in the range of 200 to 260°C, and the reaction time is in the range of 10 minutes to 3 hours. Furthermore, if 20 mole parts or more of trivalent or higher polyhydric carboxylic acid is used with respect to 100 mole parts of all the polycarboxylic acids constituting the thermoplastic polyester, the molecular weight may decrease significantly, so if it is less than 20 mole parts, The amount is preferably within the range of 1 to 15 mol parts, and even more preferably 2 to 10 mol parts.

<(B) Component: Magnesium oxide filler>
The magnesium oxide filler of component (B) is a filler whose main component is magnesium oxide (MgO; magnesia), and contains 95.0% by weight or more of magnesium oxide, preferably 98% by weight or more, more preferably 99% by weight or more. , most preferably 99.9% by weight or more. The higher the purity of the magnesium oxide constituting the filler, the better the dispersibility will be even if the average particle size is small, and the effect of improving soldering heat resistance will be more likely to be obtained while maintaining a low dielectric loss tangent. The magnesium oxide forming the filler may be either single crystal or polycrystalline, but single crystal is preferred since excellent dispersibility can be obtained even if the average particle size is small. By blending the magnesium oxide filler into the resin composition, soldering heat resistance can be enhanced without deteriorating the dielectric loss tangent when a resin film is formed.

Further, the average particle diameter of the magnesium oxide filler is within the range of 30 nm to 10 μm, preferably within the range of 30 nm to less than 10 μm, more preferably within the range of 30 nm to 5 μm, and still more preferably within the range of 30 nm to 1 μm. , most preferably within the range of 40 nm to 300 nm. Within this range, it is possible to effectively improve solder heat resistance without deteriorating dielectric properties when forming a resin film. If the average particle size is less than 30 nm, the dispersibility may decrease and it may be difficult to form a resin film, or it may be difficult to disperse uniformly when forming a resin film, resulting in deterioration of dielectric properties or , which may cause a decrease in soldering heat resistance. If the average particle diameter exceeds 10 μm, voids may occur due to increased stress due to resin contraction around the film when the film is formed, and may appear as irregularities on the surface of the film, deteriorating the smoothness of the film surface. Here, for magnesium oxide fillers with a particle size of less than 0.4 μm, the BET equivalent particle size is applied, and for magnesium oxide fillers with a particle size of 0.4 μm or more, the volume-based particle size distribution is determined by laser diffraction method. Apply the particle size obtained by measurement.

In particular, magnesium oxide filler with an average particle diameter (herein, average particle diameter means BET equivalent particle diameter, hereinafter referred to as "BET equivalent particle diameter") in the range of 30 nm to 300 nm has a small particle diameter. Nevertheless, it is most preferable because it has excellent dispersibility in the resin composition (resin solution) and resin film, and is highly effective in improving soldering heat resistance. The reason why a magnesium oxide filler with a BET equivalent particle size in the range of 30 nm to 300 nm is effective in improving soldering heat resistance is not yet clear, but it is possible to speculate as follows (1) to (3). .
(1) Because the particle size is small, excessive concentration of stress does not occur when dispersed in the thermoplastic polyester matrix resin, and although crazes (fine cracks) occur, large cracks are unlikely to occur.
(2) When the matrix resin is deformed, many small pores are formed around the filler particles, and the elongation is improved by these many pores. As a result, stress concentration is alleviated and craze is stabilized. To be done.
(3) Magnesium oxide filler has a low coefficient of thermal expansion (CTE) of about 13 ppm/K, so it can suppress the thermal expansion of the resin film at high temperatures and relieve the stress at the interface with the metal layer.

Magnesium oxide filler with a BET equivalent particle size in the range of 30 nm to 300 nm is produced by causing a vapor phase oxidation reaction between high purity metallic magnesium vapor and oxygen to generate crystal nuclei, and growing the crystal nuclei. . Therefore, since magnesium oxide is a single crystal and has high purity, it is considered to have the above characteristics.

On the other hand, in the case of aluminum oxide (alumina) filler, which is commonly used in the electronic materials field, it has a higher interfacial energy than magnesium oxide filler, so it has poor handling when the BET equivalent particle size is in the range of 30 nm to 300 nm. However, it is difficult to apply to polyimide, has poor wettability with resin, and is not stable even when pores are present, so it cannot be used to improve soldering heat resistance like magnesium oxide filler. Conceivable.

Note that the average particle diameter of the magnesium oxide filler may be within the range of 200 nm to 10 μm depending on the purpose. In addition, the "particle diameter" of the magnesium oxide filler can be calculated based on the diameter if it is spherical, and can be calculated based on the long diameter of the filler particle if it is plate-shaped or other shapes. can.

Further, as shown in the test examples described later, in the magnesium oxide filler, a peak derived from magnesium oxide is detected in X-ray diffraction (XRD) measurement, but a peak derived from magnesium hydroxide is not detected. When the magnesium oxide filler is measured by an X-ray diffraction method, it can be determined that the magnesium oxide filler does not substantially contain magnesium hydroxide because no peak derived from magnesium hydroxide is detected. Here, "not substantially containing magnesium hydroxide" means that the content of magnesium hydroxide in the magnesium oxide filler is 0.1% by weight or less.

Furthermore, as shown in the test example below, the magnesium oxide filler has a weight loss rate of 2% or less at 350°C when heated from 30°C to 450°C at a heating rate of 10°C per minute in thermogravimetric analysis. It is preferably 1.8% or less, and more preferably 1.8% or less. The fact that the weight loss rate in this temperature range is 2% or less means that dehydration and decomposition of magnesium hydroxide [Mg(OH) ₂ ] has hardly occurred, and the content of magnesium hydroxide in the magnesium oxide filler This means that the amount is very small. Here, magnesium hydroxide is mixed during the manufacturing process or is generated when the surface of magnesium oxide is hydrated due to the influence of environmental humidity during storage after manufacturing, but in the present invention, hydroxide It is preferable to use a magnesium oxide filler in which the magnesium content is reduced as much as possible.

Further, the shape of the magnesium oxide filler is not particularly limited, and may be, for example, a plate shape, a spherical shape, a polyhedral shape represented by a cube, etc. Here, "plate-like" is used to include, for example, flat, plate-like, flaky, scaly, etc., and the thickness of the filler is sufficiently smaller than the major axis or minor axis of the flat part, preferably 1 /2 or less.

The magnesium oxide filler may be subjected to surface treatment. Known techniques can be used for the surface treatment, and for example, modification by corona treatment, plasma treatment, UV treatment, etc., functional grouping treatment using a silane coupling agent, etc. are preferable. By surface-treating magnesium oxide filler, it is possible to improve its affinity with solvents or polyamic acid, and to improve the repulsion between filler particles. Improved stability.

As the magnesium oxide filler, commercially available products can be appropriately selected and used. Commercially available magnesium oxide fillers include, for example, high-purity ultrafine powder magnesia 2000A (product name), Magnesia 500A (product name), RF-10CS (product name), and RF-10CS-SC (product name) manufactured by Ube Materials. etc. can be used.

[Amount]
The weight ratio of component (B) to the total amount of components (A) and (B) in the resin composition is within the range of 1 to 50% by weight, preferably within the range of 10 to 45% by weight, and 15 to 50% by weight. It is more preferably within the range of 40% by weight. If the weight ratio of component (B) to the total amount of components (A) and (B) is less than 1% by weight, the improvement in soldering heat resistance may be insufficient. On the other hand, if the weight ratio of component (B) exceeds 50% by weight, the adhesiveness when forming a resin film may be reduced, or the resin film may become brittle and its bendability may be reduced. Furthermore, when the weight ratio of component (B) exceeds 50% by weight, the viscosity of the resin composition increases and workability decreases. In addition, when containing a magnesium oxide filler with a BET equivalent particle diameter within the range of 30 nm to 60 nm, from the viewpoint of suppressing agglomeration of the magnesium oxide filler, (B) ) The weight ratio of the component is preferably 10% by weight or less, more preferably 5% by weight or less.

The resin composition of the present embodiment may further contain inorganic fillers other than magnesium oxide, organic fillers, plasticizers, curing accelerators, coupling agents, Pigments, flame retardants, UV inhibitors, antioxidants, plasticizers, fluxes, dispersants, emulsifiers, low elasticity agents, diluents, antifoaming agents, ion trapping agents, leveling agents, catalysts, etc. can be blended as appropriate. can. Here, examples of inorganic fillers other than magnesium oxide include aluminum oxide, beryllium oxide, niobium oxide, titanium oxide, boron nitride, aluminum nitride, silicon nitride, aluminum fluoride, calcium fluoride, magnesium fluoride, and potassium silicofluoride. , phosphinate metal salts, and the like. These can be used alone or in combination of two or more. Further, as an optional component, other resin components such as epoxy resin, fluororesin, and olefin resin may be blended.

Furthermore, the resin composition of this embodiment may contain an organic solvent in order to appropriately adjust the viscosity and facilitate handling when forming a coating film. The organic solvent is used to ensure ease of handling and workability in molding the resin composition, and there is no particular restriction on the amount used. Examples of organic solvents include acetone, methyl ethyl ketone (MEK), methyl isobutyl ketone, cyclohexanone, ethyl acetate, ethylene glycol monomethyl ether, methanol, ethanol, propanol, butanol, N,N-dimethylformamide (DMF), N,N-dimethyl Acetamide (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 and the like. Two or more of these solvents can be used in combination, and it is also possible to use saturated hydrocarbons such as hexane and cyclohexane, and aromatic hydrocarbons such as xylene and toluene. These may be used alone, or two or more may be used as a mixture in any combination and ratio.

[viscosity]
The viscosity of the resin composition is preferably within the range of 3,000 cps to 100,000 cps, for example, as a viscosity range that improves handling properties when applying the resin composition and facilitates forming a coating film of uniform thickness. It is preferably within the range of 5,000 cps to 50,000 cps. If the viscosity is outside the above range, defects such as uneven thickness and streaks are likely to occur in the film during coating with a coater or the like.

[Preparation of resin composition]
When preparing a resin composition, for example, the magnesium oxide filler may be directly blended into a thermoplastic polyester resin solution prepared using an arbitrary solvent, or the entire amount of the magnesium oxide filler may be added at once. , may be added little by little in several portions. Further, the raw materials may be added all at once, or may be mixed little by little in several batches.

[glue]
The resin composition of this embodiment is useful as an adhesive (adhesive composition), and when an adhesive layer is formed using it, it has excellent flexibility and thermoplasticity. Therefore, the resin composition has favorable properties for applications such as materials for adhesive layers and adhesives for coverlay films that protect wiring parts in FPCs, rigid-flex circuit boards, and the like.
The adhesive of the present invention is preferably used in electronic equipment that transmits, receives, or transmits high-frequency signals, for example, in electronic equipment that transmits, receives, or transmits high-frequency signals within a frequency range of 1 to 60 GHz, and is used as a circuit board material. Applicable to

Furthermore, the resin composition of this embodiment can be intentionally cured by heat or light, and the degree of curing can be controlled depending on desired physical properties and uses. When curing by heat, for example, it is preferable to further contain an epoxy resin, and the epoxy group in the epoxy resin and the carboxyl group in the polyester are reacted and cured, resulting in excellent heat resistance, and not only adhesive strength but also solder heat resistance. An adhesive layer with excellent properties can be obtained.

When the resin composition of this embodiment is applied as an adhesive containing an epoxy resin, the acid value of the thermoplastic polyester is preferably 3 mgKOH/g or more, more preferably 4 to 60 mgKOH/g. It is preferably within the range, more preferably within the range of 5 to 40 mgKOH/g. By controlling it within such a range, the number of crosslinking points with the epoxy resin can be satisfied and the degree of crosslinking can be increased, so that heat resistance can be improved. On the other hand, it is not preferable to make the acid value too high because this will cause deterioration of dielectric properties.

Examples of epoxy resins include bifunctional glycidyl ether types such as bisphenol A diglycidyl ether, bisphenol S diglycidyl ether, and brominated bisphenol A diglycidyl ether; polyfunctional glycidyl ether types such as phenol novolac glycidyl ether and cresol novolac glycidyl ether. ; Glycidyl ester types such as hexahydrophthalic acid glycidyl ester and dimer acid glycidyl ester; Alicyclic or aliphatic epoxides such as triglycidyl isocyanurate, 3,4-epoxycyclohexylmethyl carboxylate, epoxidized polybutadiene, and epoxidized soybean oil etc. These can be used alone or in combination of two or more.

Further, when the resin composition of the present embodiment is applied as an adhesive containing an epoxy resin, the content of the epoxy resin is preferably 1 to 30 parts by weight based on 100 parts by weight of the thermoplastic polyester. It is preferably within the range of 2 to 20 parts by weight, still more preferably 3 to 10 parts by weight. By setting it within such a range, heat resistance, long-term durability in a moist heat environment, initial adhesiveness, and low moisture absorption can be improved. Incidentally, an increase in the content of the epoxy resin is not preferable because the dielectric properties tend to deteriorate.

The curing method for curing or semi-curing the adhesive of the present invention can be adjusted as appropriate depending on the ingredients and amount of the resin composition, and is usually heated at 80 to 200°C for 1 minute to 10 hours. There are conditions.

Further, a catalyst may be used when curing a resin composition containing an epoxy resin. Examples of such catalysts include 2-methylimidazole, 1,2-dimethylimidazole, 2-ethyl-4-methylimidazole, 2-phenyl-4-methylimidazole, and 1-cyanoethyl-2-ethyl-4-methyl. Imidazole compounds such as imidazole; triethylamine, triethylenediamine, N'-methyl-N-(2-dimethylaminoethyl)piperazine, 1,8-diazabicyclo(5,4,0)-undecene-7,1,5-diazabicyclo Tertiary amines such as (4,3,0)-nonene-5,6-dibutylamino-1,8-diazabicyclo(5,4,0)-undecene-7; Examples include compounds made into amine salts with octylic acid, quaternized tetraphenylborate salts, etc.; cationic catalysts such as triallylsulfonium hexafluoroantimonate and diallyliodonium hexafluoroantimonate; triphenylphosphine, and the like. Among these, 1,8-diazabicyclo(5,4,0)-undecene-7 and 1,5-diazabicyclo(4,3,0)-nonene-5,6-dibutylamino-1,8-diazabicyclo(5 , 4,0)-undecene-7; and compounds in which these tertiary amines are made into amine salts with phenol, octylic acid, quaternized tetraphenylborate salts, etc., have thermosetting and heat-resistant properties. It is preferable in terms of properties, adhesion to metals, and storage stability after blending. In this case, the blending amount is preferably 0.01 to 1 part by weight per 100 parts by weight of the thermoplastic polyester. Within this range, the catalytic effect on the reaction between the thermoplastic polyester and the epoxy resin will further increase, and strong adhesive performance can be obtained.

[Resin film]
The resin film of this embodiment is a resin film consisting of a single layer or multiple layers including a filler-containing thermoplastic resin layer, and the filler-containing thermoplastic resin layer has a solid content (excluding solvent) of the resin composition. The remainder) is made into a film using the main ingredients. In other words, the filler-containing thermoplastic resin layer includes (A) component and (B) component;
(A) a thermoplastic polyester; and (B) a magnesium oxide filler having an average particle size within the range of 30 nm to 10 μm;
and the content of component (B) based on the total amount of components (A) and (B) is within the range of 1 to 50% by weight. The resin film of this embodiment has excellent high frequency characteristics and excellent adhesiveness (especially solder heat resistance), and can be preferably used as an insulating resin layer of a circuit board such as an FPC. Note that the insulating resin layer of the circuit board includes an adhesive layer and a coverlay film material in addition to the insulating base material.

The resin film of this embodiment is not particularly limited as long as it is an insulating resin film containing the filler-containing thermoplastic resin layer described above, and may be a film (sheet) made of an insulating resin, or a copper foil The insulating resin film may be laminated on a base material such as a glass plate, a resin sheet such as a polyimide film, a polyamide film, or a polyester film.

(thickness)
The thickness of the resin film of this embodiment is, for example, preferably within the range of 5 μm or more and 125 μm or less, and more preferably within the range of 8 μm or more and 100 μm or less. If the thickness of the resin film is less than 5 μm, there is a risk of problems such as wrinkles during transportation during the production of the resin film, etc. On the other hand, if the thickness of the resin film exceeds 125 μm, there is a risk of decreased productivity of the resin film. There is.

Since the resin film of this embodiment has a low dielectric loss tangent and excellent adhesive properties, it can be used as an adhesive layer in a coverlay, a circuit board, a multilayer circuit board, an adhesive layer in a resin-coated copper foil, etc., a bond ply, and a bonding layer. It is useful as a sheet, etc.

[Laminated body]
A laminate according to an embodiment of the present invention has a base material and an adhesive layer laminated on at least one surface of the base material, and the adhesive layer is made of the above resin film. . Note that the laminate may include any layers other than those described above. Examples of the base material in the laminate include base materials of inorganic materials such as copper foil and glass plates, and base materials of resin materials such as polyimide films, polyamide films, and polyester films.
Preferred embodiments of the laminate include a coverlay film, resin-coated copper foil, and the like.

[Coverlay film]
A coverlay film, which is an embodiment of a laminate, has a coverlay film material layer as a base material, and an adhesive layer laminated on one side of the coverlay film material layer, and the adhesive layer is made of the above resin film. Note that the coverlay film may include any layer other than the above.

The material of the coverlay film material layer is not particularly limited, but for example, polyimide films such as polyimide resin, polyetherimide resin, polyamideimide resin, polyamide films, polyester films, etc. can be used. Among these, it is preferable to use a polyimide film having excellent heat resistance. In addition, the film material layer for the coverlay may contain a black pigment in order to effectively express light-shielding properties, hiding properties, design properties, etc., and the surface Optional ingredients such as matte pigments can be included to suppress the gloss of the paint.

The thickness of the coverlay film material layer is not particularly limited, but is preferably in the range of 5 μm or more and 100 μm or less, for example.
Further, the thickness of the adhesive layer is not particularly limited, but is preferably within the range of, for example, 10 μm or more and 75 μm or less.

The coverlay film of this embodiment can be manufactured by the method illustrated below.
First, as a first method, a varnish-like resin composition containing a solvent is applied to one side of a film material layer for coverlay, and then dried at a temperature of, for example, 80 to 180°C to form an adhesive layer. By doing so, a coverlay film having a coverlay film material layer and an adhesive layer can be formed.

In addition, as a second method, a varnish-like resin composition containing a solvent is applied onto an arbitrary base material, dried at a temperature of, for example, 80 to 180°C, and then peeled off. A coverlay film can be formed by forming a resin film and thermocompression bonding this resin film with a film material layer for coverlay at a temperature of, for example, 60 to 220°C.

[Copper foil with resin]
A resin-coated copper foil, which is another embodiment of the laminate, is one in which an adhesive layer is laminated on at least one side of a copper foil as a base material, and the adhesive layer is made of the above resin film. Note that the resin-coated copper foil of this embodiment may include any layer other than the above.

The thickness of the adhesive layer in the resin-coated copper foil is, for example, preferably in the range of 2 to 125 μm, more preferably in the range of 2 to 100 μm. If the thickness of the adhesive layer is less than the above lower limit, problems such as insufficient adhesiveness may occur. On the other hand, if the thickness of the adhesive layer exceeds the above upper limit, problems such as decreased dimensional stability will occur. Further, from the viewpoint of lowering the dielectric constant and lowering the dielectric loss tangent, it is preferable that the thickness of the adhesive layer is 3 μm or more.

The material of the copper foil in the resin-coated copper foil is preferably one whose main component is copper or a copper alloy. The thickness of the copper foil is preferably 35 μm or less, more preferably within the range of 5 to 25 μm. From the viewpoint of production stability and handling properties, the lower limit of the thickness of the copper foil is preferably 5 μm. Note that the copper foil may be a rolled copper foil or an electrolytic copper foil. Moreover, as the copper foil, commercially available copper foil can be used.

Resin-coated copper foil may be prepared, for example, by sputtering metal onto a resin film to form a seed layer and then forming a copper layer, for example by copper plating, or by heating the resin film and copper foil. It may also be prepared by laminating by a method such as pressure bonding. Furthermore, in order to form an adhesive layer on the copper foil, resin-coated copper foil can be prepared by casting a coating solution of a resin composition, drying it to form a coating film, and then performing the necessary heat treatment. good.

[Metal-clad laminate]
(First aspect)
A metal-clad laminate according to an embodiment 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 of the insulating resin layers is It is made of resin film. Note that the metal-clad laminate of this embodiment may include any layer other than those described above.

(Second aspect)
A metal-clad laminate according to another embodiment of the present invention includes, for example, an insulating resin layer, an adhesive layer laminated on at least one side of the insulating resin layer, and an adhesive layer laminated on at least one surface of the insulating resin layer. This is a so-called three-layer metal-clad laminate including a laminated metal layer, and the adhesive layer is made of the resin film described above. Note that the three-layer metal-clad laminate may include any layers other than those described above. In the three-layer metal-clad laminate, the adhesive layer may be provided on one or both sides of the insulating resin layer, and the metal layer may be provided on one or both sides of the insulating resin layer via the adhesive layer. Bye. That is, the three-layer metal-clad laminate may be a single-sided metal-clad laminate or a double-sided metal-clad laminate. A single-sided FPC or a double-sided FPC can be manufactured by processing the wiring circuit by etching the metal layer of the three-layer metal-clad laminate.

The insulating resin layer in the three-layer metal-clad laminate is not particularly limited as long as it is made of a resin that has electrical insulation properties, such as polyimide, epoxy resin, phenol resin, polyethylene, polypropylene, and polytetrafluoroethylene. , silicone, ETFE, etc.

The thickness of the insulating resin layer in the three-layer metal-clad laminate is, for example, preferably in the range of 1 to 125 μm, more preferably in the range of 5 to 100 μm. If the thickness of the insulating resin layer is less than the above lower limit, problems such as insufficient electrical insulation may occur. On the other hand, if the thickness of the insulating resin layer exceeds the above upper limit, problems such as warping of the three-layer metal clad laminate will occur.

The thickness of the adhesive layer in the three-layer metal-clad laminate is, for example, preferably in the range of 0.1 to 125 μm, more preferably in the range of 0.3 to 100 μm. In the three-layer metal-clad laminate of the present embodiment, if the thickness of the adhesive layer is less than the above-mentioned lower limit, problems such as insufficient adhesiveness may occur. On the other hand, if the thickness of the adhesive layer exceeds the above upper limit, problems such as decreased dimensional stability will occur. Further, from the viewpoint of lowering the dielectric constant and dielectric loss tangent of the entire insulating layer, which is a laminate of an insulating resin layer and an adhesive layer, the thickness of the adhesive layer is preferably 3 μm or more.

Further, the ratio of the thickness of the insulating resin layer to the thickness of the adhesive layer (thickness of the insulating resin layer/thickness of the adhesive layer) is preferably within the range of 0.1 to 3.0, for example, 0.15 to 2. It is more preferably within the range of .0. By setting such a ratio, warpage of the three-layer metal-clad laminate can be suppressed. Further, the insulating resin layer may contain a filler, if necessary. Examples of fillers include silicon dioxide, aluminum oxide, magnesium oxide, beryllium oxide, boron nitride, aluminum nitride, silicon nitride, aluminum fluoride, calcium fluoride, and metal salts of organic phosphinic acids. These can be used alone or in combination of two or more.

[Circuit board]
A circuit board according to an embodiment of the present invention is formed by wiring the metal layer of the metal-clad laminate of any of the embodiments described above. A circuit board such as an FPC can be manufactured by processing one or more metal layers of a metal-clad laminate into a pattern by a conventional method to form a wiring layer (conductor circuit layer). Note that the circuit board may include a coverlay film that covers the wiring layer.

Examples are shown below to explain the features of the present invention more specifically. However, the scope of the present invention is not limited to the examples. In addition, in the following examples, various measurements and evaluations are as follows unless otherwise specified.

[Method for measuring ester bond concentration]
The ester bond concentration (mmol/g) was determined using the following formula. In addition, when the amounts of polyhydric carboxylic acids and polyhydric alcohols are the same molar amount, any of the following calculation formulas may be used.
1) When polyhydric carboxylic acids are less than polyhydric alcohols Ester group concentration (mmol/g) = [(A1/a1×m1+A2/a2×m2+A3/a3×m3+...)/Z]×1000
A: Amount of polyvalent carboxylic acids (g)
a: Molecular weight of polyvalent carboxylic acids m: Number of carboxylic acid groups per molecule of polyvalent carboxylic acids Z: Finished weight (g)
[Note that the numbers in A1, A2, . . . , a1, a2, . ]
2) When polyhydric alcohols are less than polyhydric carboxylic acids Ester group concentration (mmol/g) = [(B1/b1×n1+B2/b2×n2+B3/b3×n3+...)/Z]×1000
B: Amount of polyhydric alcohol (g)
b: Molecular weight of polyhydric alcohol n: Number of hydroxyl groups per molecule of polyhydric alcohol Z: Finished weight (g)
[Note that the numbers in B1, B2, . . . , b1, b2, . . . , n1, n2, . ]

[Method for measuring glass transition temperature (Tg)]
The measurement was performed using a differential scanning calorimeter under the measurement conditions of a measurement temperature range of -70 to 140°C and a temperature increase rate of 10°C/min.

[Method for measuring weight average molecular weight (Mw) and peak top molecular weight (Mp)]
Using high performance liquid chromatography (manufactured by Tosoh Corporation, trade name: HLC-8320GPC), a column [TSKgel SuperMultipore HZ-M (exclusion limit molecular weight: 2 × 10 ⁶ , number of theoretical plates: 16000 plates/piece, packing material: styrene) was used. - divinylbenzene copolymer, filler particle size: 4 μm)] in series, and calculated based on standard polystyrene molecular weight conversion.

[Solder heat resistance test (drying)]
Etch away the copper foil on one side of a double-sided copper-clad laminate (manufactured by Nippon Steel Chemical & Materials Co., Ltd., product name: Espanex MB12-25-12UEG), and sandwich the other copper foil side and the resin sheet between the copper foils. They were laminated in a shape and pressed under the conditions of temperature: 160° C., pressure: 3.5 MPa, and time: 60 minutes. After drying this test piece with copper foil at 135°C for 60 minutes, it was immersed in a solder bath set at each evaluation temperature from 260°C to 300°C in 10°C increments for 10 seconds, and the adhesion state was observed. We checked for defects such as foaming, blistering, and peeling. As a judgment, if no defects were observed at 260° C., it was rated as 〇 (good), and if any defects were observed, it was graded as × (poor).

[Method of measuring filler particle size]
For fillers with a particle size of less than 0.4 μm, the BET equivalent particle size was applied.
For fillers with a particle size of 0.4 μm or more, a laser diffraction particle size distribution analyzer (manufactured by Malvern, trade name: Master Sizer 3000) was used to measure the particle refractive index of 1.54 using water as a dispersion medium. The particle diameter was measured using a laser diffraction/scattering measurement method under the following conditions. The value at which the cumulative value in the frequency distribution curve obtained by volume-based particle size distribution measurement using laser diffraction method is 50% was defined as the average particle diameter _D50 .

[Evaluation of dielectric properties]
Using a vector network analyzer (manufactured by Agilent, trade name: Vector Network Analyzer E8363C) and a split post dielectric resonator (SPDR resonator), a resin sheet was measured at a temperature of 23°C and a humidity of 50% RH for 24 hours. After leaving it for a period of time, the dielectric loss tangent (Tan δ) at a frequency of 10 GHz was measured. As a judgment, a case where the measurement result was 0.003 or less was judged as ○, and a case where it was larger than 0.003 was judged as ×.

[Measurement of water absorption rate]
A resin solution of the polyester composition was applied onto a release film using an applicator and dried at 120° C. for 10 minutes to produce a sheet with a resin layer having a dry thickness of 65 μm. This sheet was cut into a size of 7.5 cm x 11 cm, the resin layer side of the sheet was laminated on a glass plate, and then the release film was peeled off. By repeating this operation six times, a test plate having a resin layer with a thickness of 390 μm on the glass plate was obtained.
The thus obtained test plate was immersed in purified water at 23° C. for 24 hours, then taken out, the surface moisture was wiped off, and it was dried at 70° C. for 2 hours. The weight required in each of these steps was measured, and the water absorption rate (% by weight) was calculated from the weight change according to the following formula.
(c-d)×100/(b-a)
a: Weight of the glass plate alone b: Weight of the initial test plate c: Weight of the test plate immediately after removing it from purified water and wiping off moisture d: Weight of the test plate after drying at 70°C for 2 hours

The abbreviations used in this example represent the following compounds.
TPA: Terephthalic acid IPA: Isophthalic acid TMAn: Trimellitic anhydride EG: Ethylene glycol BPE-20: Polyhydric alcohol, manufactured by Sanyo Chemical Industries, Ltd., approximately 2 moles of ethylene oxide adduct of bisphenol A, trade name: Newpol BPE -20
P2033: Dimerdiol, manufactured by Croda, product name: "Pripol 2033"
Filler 1: Manufactured by Ube Materials, product name: High purity ultrafine powder magnesia 2000A (magnesium oxide, primary particles: single crystal, cubic shape, purity: magnesium oxide >99.98%, specific gravity: 3.58, BET equivalent particles Diameter: 200 nm, coefficient of thermal expansion: 13 ppm/K)
YDPN-638: Nippon Steel Chemical & Materials Co., Ltd., phenol novolac type epoxy resin, product name: YDPN-638

[Synthesis Example 1: Production of polyester (A-1)]
231.1 parts (1.3910 mol) of isophthalic acid (IPA) and trimellitic anhydride (TMAn) as polyvalent carboxylic acids were placed in a reaction vessel equipped with a thermometer, stirrer, rectification column, and nitrogen inlet tube. 2.7 parts (0.0141 mol), about 2 mol adduct of bisphenol A with ethylene oxide (BPE-20), 230.1 parts (0.7058 mol), and ethylene glycol (EG) 57. 0 part (0.9183 mol), 261.5 parts (0.4941 mol) of dimer diol (P2033), and 0.1 part of tetrabutyl titanate as a catalyst were charged, and the mixture was heated for 2.5 hours until the internal temperature reached 270°C. The temperature was raised to 270° C. for 1.5 hours to carry out the esterification reaction.
Next, 0.1 part of tetrabutyl titanate was added as a catalyst, the pressure inside the system was reduced to 2.5 hPa, and a polymerization reaction was carried out over 3 hours. Thereafter, the internal temperature was lowered to 240°C, 17.6 parts (0.0916 mol) of trimellitic acid anhydride (TMAn) was added, and a depolymerization reaction was carried out at 240°C for 1 hour to obtain polyester (A-1). Ta.

Synthesis Examples 2 to 4: Polyesters (A-2) to (A-4)
Polyesters (A-2) to (A-4) were obtained in the same manner as A-1 except that the resin composition was changed as shown in Table 1. Table 1 also shows the measurement results of ester bond concentration, water absorption, glass transition temperature (Tg), weight average molecular weight (Mw), and peak top molecular weight (Mp).

[Examples 1 to 4]
4 g of magnesium oxide filler (Filler 1) and 9 g of phenol novolac type epoxy resin (YDPN-638) were blended with 87 g of polyesters A-1 to A-4 prepared in Synthesis Examples 1 to 4, and toluene/methyl ethyl ketone = Resin varnishes 1a to 4a were prepared by stirring and mixing by adding a 5/1 (weight ratio) mixed solvent so that the solid content was 50%. As the filler 1, "Sample (1)" in Test Examples 1 and 2 described later was used.

[Example 5]
The resin sheet 1b ( Thickness: 25 μm) was prepared.
The evaluation results of the resin sheet 1b are as follows.
Dielectric loss tangent; 〇, Solder heat resistance test (drying); 〇

[Example 6]
A resin sheet 2b was prepared in the same manner as in Example 5 using the resin varnish 2a.
The evaluation results of the resin sheet 2b are as follows.
Dielectric loss tangent; 〇, Solder heat resistance test (drying); 〇

[Example 7]
A resin sheet 3b was prepared in the same manner as in Example 5 using the resin varnish 3a.
The evaluation results of the resin sheet 3b are as follows.
Dielectric loss tangent; 〇, Solder heat resistance test (drying); 〇

[Example 8]
A resin sheet 4b was prepared in the same manner as in Example 5 using the resin varnish 4a.
The evaluation results of the resin sheet 4b are as follows.
Dielectric loss tangent; 〇, Solder heat resistance test (drying); 〇

Comparative example 1
9 g of phenol novolak type epoxy resin (YDPN-638) was blended with 87 g of polyester A-1 prepared in Synthesis Example 1, and the solid content was reduced by adding a mixed solvent of toluene/methyl ethyl ketone = 5/1 (weight ratio). Resin varnish 5a was prepared by stirring and mixing to achieve a concentration of 50%.
The resin sheet 5b (thickness: 25 μm) is obtained by applying the resin varnish 5a to one side of the release-treated PET film, drying it at 100°C for 5 minutes, drying it at 120°C for 10 minutes, and peeling it off. Prepared.
The evaluation results of the resin sheet 5b are as follows.
Dielectric loss tangent: 〇, Solder heat resistance test (drying): ×

The above results are summarized in Table 2.

Table 2 shows that by blending a magnesium oxide filler with polyester, high soldering heat resistance can be achieved without deteriorating the dielectric loss tangent.

[Test Example 1]
Measurement of weight loss rate:
Thermogravimetric analysis measurements were carried out to investigate the formation state of magnesium hydroxide produced by hydration of magnesium oxide. The magnesium oxide samples (1) to (5) shown below were analyzed at 10°C/min using a thermogravimetric analyzer (TG: manufactured by Hitachi High-Tech Science Co., Ltd., trade name: TG/DTA7220) under a nitrogen atmosphere. The weight loss at 350° C. when heating from 30° C. to 450° C. was measured at a temperature increase rate, and the weight loss rate due to thermal decomposition of magnesium hydroxide was determined.

The above "Filler 1" was used as samples (1) to (5).
Sample (1): Immediately after opening Sample (2): After opening, it was placed in a reagent bottle and stored in a laboratory at room temperature and humidity for one year (the lid was opened and closed each time it was used)
Sample (3): After opening, exposed to an environment of 40°C and 90% humidity for 24 hours Sample (4): After opening, exposed to an environment of 40°C and 90% humidity for 48 hours Sample ( 5): After opening, exposed to an environment with a temperature of 40℃ and humidity of 90% for 72 hours.

The results of the thermogravimetric analysis measurements are shown in FIG. From Figure 1, the weight loss rates at 350°C for samples (1) to (5) are 0.36%, 1.46%, 0.85%, 1.59%, and 1.85%, respectively. , all of them were less than 2%, but sample (1) had the smallest weight loss rate, and the weight loss rate increased in the order of sample (3), sample (2), sample (4), and sample (5). You can see that From this result, it was confirmed that magnesium oxide is hydrated and the production of magnesium hydroxide progresses depending on the environmental humidity.

[Test Example 2]
For sample (1) used in Test Example 1, X-ray diffraction measurements were performed using an X-ray diffraction device [SmartLab (rotating anode) manufactured by Rigaku Corporation] by wide-angle X-ray diffraction method under the following conditions. .
X-ray source: MoKα ray (using Kβ filter)
Output: 60kV, 150mA
Slit system: CBO condensing mirror detector: Hypix-3000 (1D mode)
Scan method: 2θ/θ continuous scan Measurement range (2θ): 5 to 50°
Step width (2θ): 0.01°
Scan speed: 4°/min

The results of the X-ray diffraction measurement are shown in FIG. 2(a), and the peak position of Mg(OH) ₂ in the X-ray diffraction measurement is shown in FIG. 2(b) for reference. Further, based on the results shown in FIG. 2(a), the ratio of magnesium hydroxide was calculated by Rietveld analysis, and it was found that MgO was 100% by weight and Mg(OH) ₂ was 0% by weight.

From the above, it was confirmed that in sample (1), a peak derived from magnesium oxide was detected in the X-ray diffraction measurement, but a peak derived from magnesium hydroxide was not detected. Specifically, peaks originating from magnesium oxide were detected at positions with a 2θ of 16.8°, 19.4°, 27.6°, 32.5°, and 34.0°; No peaks derived from magnesium hydroxide were detected at positions 5°, 17.3°, 22.8° and 26.1°, indicating that sample (1) does not substantially contain magnesium hydroxide. confirmed.

From the above results, it was confirmed that the resin film according to the present embodiment can be suitably used as a material for circuit boards such as high-frequency compatible FPCs.

Although the embodiments of the present invention have been described above in detail for the purpose of illustration, the present invention is not limited to the above embodiments and can be modified in various ways.

Claims (17)

The following (A) component and (B) component;
(A) a thermoplastic polyester; and (B) a magnesium oxide filler having an average particle size within the range of 30 nm to 10 μm;
and the content of the component (B) with respect to the total amount of the component (A) and the component (B) is within the range of 1 to 50% by weight,
Component (B) is a thermoplastic polyester composition in which no peak derived from magnesium hydroxide is detected in X-ray diffraction measurements. The thermoplastic polyester composition according to claim 1, wherein the magnesium oxide filler contains 95.0% by weight or more of magnesium oxide. Claim characterized in that the magnesium oxide filler has a weight loss rate of 2% or less at 350°C when heated from 30°C to 450°C at a heating rate of 10°C per minute in thermogravimetric analysis. The thermoplastic polyester composition according to 1 or 2. 4. The thermoplastic polyester composition according to claim 1, wherein the thermoplastic polyester contains an aliphatic dicarboxylic acid residue or an aliphatic diol residue. 5. The thermoplastic polyester composition according to claim 4, wherein the aliphatic dicarboxylic acid residue is a dimer acid residue, and the aliphatic diol residue is a dimer diol residue. An adhesive comprising the thermoplastic polyester composition according to any one of claims 1 to 5. The adhesive according to claim 6, which is used for electronic equipment that transmits, receives, or transmits high-frequency signals. A resin film including a filler-containing thermoplastic resin layer,
The filler-containing thermoplastic resin layer contains the following (A) component and (B) component;
(A) a thermoplastic polyester; and (B) a magnesium oxide filler having an average particle size within the range of 30 nm to 10 μm;
and the content of the component (B) with respect to the total amount of the component (A) and the component (B) is within the range of 1 to 50% by weight,
Component (B) is a resin film characterized in that no peak derived from magnesium hydroxide is detected in X-ray diffraction measurement. The resin film according to claim 8, wherein the magnesium oxide filler contains 95.0% by weight or more of magnesium oxide. Claim characterized in that the magnesium oxide filler has a weight loss rate of 2% or less at 350°C when heated from 30°C to 450°C at a heating rate of 10°C per minute in thermogravimetric analysis. 8 or 9. The resin film according to 8 or 9. The resin film according to any one of claims 8 to 10, wherein the thermoplastic polyester contains an aliphatic dicarboxylic acid residue or an aliphatic diol residue. The resin film according to claim 11, wherein the aliphatic dicarboxylic acid residue is a dimer acid residue, and the aliphatic diol residue is a dimer diol residue. A laminate comprising a base material and an adhesive layer laminated on at least one surface of the base material,
A laminate, wherein the adhesive layer is made of the resin film according to any one of claims 8 to 12. A coverlay film comprising a coverlay film material layer and an adhesive layer laminated on the coverlay film material layer,
A coverlay film, wherein the adhesive layer is made of the resin film according to any one of claims 8 to 12. A resin-coated copper foil in which an adhesive layer and a copper foil are laminated,
A resin-coated copper foil, wherein the adhesive layer is made of the resin film according to any one of claims 8 to 12. A metal-clad laminate comprising an insulating resin layer and a metal layer laminated on at least one surface of the insulating resin layer,
A metal-clad laminate, wherein at least one of the insulating resin layers is made of the resin film according to any one of claims 8 to 12. A circuit board formed by wiring the metal layer of the metal-clad laminate according to claim 16.

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