JP2008031409A - Low dielectric resin composition, prepreg, metal-clad laminate, printed circuit board - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a low dielectric resin composition whose dielectric constant, dielectric loss tangent and coefficient of thermal expansion all can be reduced and whose insulation reliability can be enhanced. <P>SOLUTION: The present invention relates to a low dielectric resin composition comprising a thermosetting resin and hollow particles each comprising a shell and a hollow portion. The hollow particles have an average porosity of 30 to 80 vol.% and an average particle diameter of 0.1 to 20 μm, and ≥98 mass% of all the shells of the hollow particles are formed from silica. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a low dielectric resin composition, a prepreg, a metal-clad laminate, and a printed wiring board that are used for manufacturing various electronic devices.

  In recent years, electronic devices are required to have a high number of layers by increasing the speed of signals and increasing the number of wires. In response to such demands, laminates are required to have a low dielectric constant, a low dielectric loss tangent, and a low thermal expansion coefficient (low α).

  Conventionally, in order to achieve a low dielectric constant and a low dielectric loss tangent, polyimides and fluorides, which are materials having a low dielectric constant and dielectric loss tangent, have been used. Moreover, the space | gap by a hollow particle etc. has also been utilized (for example, refer patent document 1-4).

On the other hand, in response to the demand for low thermal expansion, a method of highly filling an inorganic filler has been taken.
JP-A-5-9270 JP-A-8-46309 JP 10-298407 A JP-A-2005-15613

  However, in the hollow particles described in Patent Documents 1-4, both the dielectric constant and the dielectric loss tangent may not be reduced due to the influence of impurities. In addition, when the hollow particles are organic compounds as in Patent Document 4, the dielectric properties are good, but the thermal expansion coefficient cannot be lowered, and there is a possibility that it is not possible to cope with multilayering. Furthermore, the requirement for insulation reliability has increased with the increase in the number of layers.

  The present invention has been made in view of the above points. A low dielectric resin composition and a prepreg that can reduce the dielectric constant, dielectric loss tangent, and thermal expansion coefficient, and can obtain high insulation reliability. An object of the present invention is to provide a metal-clad laminate and a printed wiring board.

  The low dielectric resin composition according to claim 1 of the present invention is a low dielectric resin composition containing a hollow particle composed of a shell and a hollow part and a thermosetting resin. Is made of silica, and has an average porosity of 30 to 80% by volume and an average particle size of 0.1 to 20 μm.

  The invention according to claim 2 is characterized in that in claim 1, hollow particles having an average porosity of 50 to 80% by volume are used.

  The invention according to claim 3 is characterized in that in claim 1 or 2, the hollow particles are those having an average particle diameter of 0.5 to 5 μm.

  The invention according to claim 4 is characterized in that in any one of claims 1 to 3, the hollow particles are those whose surfaces have been subjected to a hydrophobic treatment.

  The invention according to claim 5 is characterized in that, in any one of claims 1 to 4, the content of the hollow particles is 5 to 30% by mass with respect to the total amount of the low dielectric resin composition. .

  The invention according to claim 6 is characterized in that, in any one of claims 1 to 5, the content of the hollow particles is 5 to 20% by mass with respect to the total amount of the low dielectric resin composition. .

  The invention according to claim 7 is characterized in that, in any one of claims 1 to 6, the content of the hollow particles is 10 to 20% by mass with respect to the total amount of the low dielectric resin composition. .

  The invention according to an eighth aspect is characterized in that, in any one of the first to seventh aspects, a polyphenylene ether resin is used as the thermosetting resin.

  The invention according to claim 9 is characterized in that in claim 8, the polyphenylene ether resin has a structure represented by the following formula (1) and has a number average molecular weight of 3000 to 7000. To do.

  A prepreg according to claim 10 of the present application is characterized in that the low dielectric resin composition according to any one of claims 1 to 9 is impregnated into a base material and heat-dried. .

  A metal-clad laminate according to claim 11 of the present application is characterized in that the prepreg according to claim 10 and a metal foil are laminated and heated and pressed.

  A printed wiring board according to claim 12 of the present application is characterized in that a circuit is formed on the metal-clad laminate according to claim 11.

  According to the low dielectric resin composition of the first aspect of the present invention, the dielectric constant, dielectric loss tangent, and thermal expansion coefficient can all be reduced, and insulation reliability can be increased.

  According to the invention of claim 2, the coefficient of thermal expansion can be further reduced.

  According to the invention which concerns on Claim 3, solder heat resistance can further be improved.

  According to the invention which concerns on Claim 4, solder heat resistance can further be improved.

  According to the invention of claim 5, the heat resistance of the solder, the insulation reliability, and the resin flow of the prepreg can be further improved, and a good appearance can be obtained by preventing the unevenness on the surface of the laminate. It is something that can be done.

  According to the invention which concerns on Claim 6, wear of the drill used at the time of drilling of a through-hole etc. decreases, and the lifetime of a drill can be extended.

  According to the invention which concerns on Claim 7, a dielectric constant, a dielectric loss tangent, and a thermal expansion coefficient can be made still smaller.

  According to the eighth aspect of the present invention, the dielectric constant and dielectric loss tangent can be further reduced.

  According to the ninth aspect of the invention, the dielectric constant can be further reduced and the resin flow of the prepreg can be further increased.

  According to the prepreg of the present invention, the dielectric constant, dielectric loss tangent, and thermal expansion coefficient can all be reduced, and insulation reliability can be increased.

  According to the metal-clad laminate of claim 11 of the present invention, the dielectric constant, dielectric loss tangent, and thermal expansion coefficient can all be reduced, and insulation reliability can be increased.

  According to the printed wiring board of the twelfth aspect of the present invention, the dielectric constant, dielectric loss tangent, and coefficient of thermal expansion can all be reduced, and insulation reliability can be increased.

  Embodiments of the present invention will be described below.

  The low dielectric resin composition according to the present invention contains hollow particles composed of a shell (outer shell) and a hollow portion and a thermosetting resin.

  In the present invention, as the thermosetting resin, one kind or two or more kinds of epoxy resins such as brominated epoxy resin and cresol novolac type epoxy resin can be used, and it is not particularly limited, but polyphenylene ether (PPE) It is preferable to use a resin. Thereby, compared with the case where an epoxy resin etc. are used, a dielectric constant and a dielectric loss tangent can be made still smaller. As such a polyphenylene ether resin, those obtained by reducing the molecular weight of the high molecular weight polyphenylene ether resin represented by the structure of the following general formula (2) by a molecular weight reduction method described later can be used.

  Examples of the high molecular weight polyphenylene ether resin represented by the general formula (1) include poly (2,6-dimethyl-1,4-phenylene oxide).

  The polyphenylene ether resin that can be used in the present invention is, for example, molded from the high molecular weight polyphenylene ether having a number average molecular weight (Mn) of about 13,000 to 25,000 synthesized by the method disclosed in US Pat. No. 4,059,568. In order to adjust to a melt viscosity suitable for the number, the number average molecular weight is obtained by reducing the molecular weight to about 2000 to 10,000.

  As a method for obtaining a polyphenylene ether resin having a reduced molecular weight, a known method for reducing the molecular weight, specifically, for example, the method of reducing the molecular weight by reacting a phenol species with a polyphenylene ether resin, “The Journal of Organic Chemistry. , 34,297-303 (1969) ", an improved known method thereof, and the like can be used.

  As the method, for example, the high molecular weight polyphenylene ether resin having a number average molecular weight of about 13,000 to 25,000 is a solvent together with a phenol species, a decomposition peroxide and, if necessary, a fatty acid metal salt such as cobalt naphthenate for promoting a decomposition reaction. The method of decomposing even the number average molecular weight to about 2000-10000 by making it react in is mentioned.

  Examples of the phenol species include phenol, cresol, xylenol, hydroquinone, bisphenol A, 2,6-dimethylphenol, 4,4'-dihydroxydiphenyl ether, and the like.

  Examples of the decomposition peroxide include di (t-butylperoxyisopropyl) benzene, benzoyl peroxide, 3,3 ′, 5,5′-tetramethyl-1,4-diphenoquinone chloranil, 2 , 4,6-tri-t-butylphenoxyl, t-butylperoxyisopropyl monocarbonate, azobisisobutyronitrile and the like.

  And especially as a polyphenylene ether resin, it is preferable to use what has a structure shown by following formula (1) and whose number average molecular weight is 3000-7000.

  The aryl group represented by X is derived from the phenol species. Examples of the aryl group include a phenyl group, a biphenyl group, an indenyl group, and a naphthyl group, and a phenyl group is preferable. In addition, the aryl group of the present invention also includes a diphenyl ether group in which these aryl groups are bonded with an oxygen atom, a benzophenone group bonded with a carbonyl group, and a 2,2-diphenylpropane group bonded with an alkylene group. Included in the definition. In addition, these aryl groups may be substituted with a general substituent such as an alkyl group (preferably a C1-C6 alkyl group, particularly a methyl group), an alkenyl group, an alkynyl group, or a halogen atom.

  By using the polyphenylene ether resin having the structure represented by the above formula (1), the dielectric constant can be further reduced and the resin flow of the prepreg can be further increased. However, if the number average molecular weight is less than 3000, the glass transition temperature and the heat resistance may be lowered. Conversely, if the number average molecular weight exceeds 7000, the fluidity is reduced, and the resin filling between circuits is poor. May occur.

  Further, in the general formula (1), a polyphenylene ether in which Z of the moiety represented by the following general formula (3) is a phenylene group, n is 1, and the number average molecular weight is 3000 to 7000. Resins are particularly preferred.

  By using such a polyphenylene ether resin, the moldability of the resulting prepreg is excellent, the heat resistance such as solder heat resistance of the obtained laminate is increased, and the dielectric loss tangent that affects the transmission speed tends to be lower. There is.

  In the partial structure represented by the general formula (3), a halide of a compound having the partial structure, for example, halogenated methylstyrene, and the polyphenylene ether resin reduced in molecular weight are present in the presence of an alkali metal hydroxide. It can be performed by reacting with.

  As a specific example, for example, by dissolving a polyphenylene ether resin having a phenol group at the terminal and halogenated methylstyrene in an organic solvent such as toluene, and dropping an aqueous solution of an alkali metal hydroxide into this solution, An end-modified polyphenylene ether resin by ethenyl benzylation, which is an example of the structure, is obtained. At this time, the alkali metal hydroxide functions as a dehydrohalogenating agent (for example, a dehydrochlorinating agent), and this alkali metal hydroxide desorbs the hydrogen halide from the phenol group and halogenated methylstyrene, The structure represented by the general formula (1) is bonded to O instead of H of the phenol group (—OH) at the terminal of the polyphenylene ether resin. In addition, it is preferable that reaction temperature is 30-100 degreeC and reaction time is 0.5 to 20 hours.

  Examples of the halogenated methylstyrene include, for example, p-chloromethylstyrene, m-chloromethylstyrene, a mixture of p-chloromethylstyrene and m-chloromethylstyrene, p-bromomethylstyrene, m-bromomethylstyrene, A mixture of p-bromomethylstyrene and m-bromomethylstyrene or the like can be used. In particular, the halogenated methylstyrene is preferably at least one selected from the group consisting of p-chloromethylstyrene and m-chloromethylstyrene. When such a halogenated methylstyrene is used, the partial structure represented by the general formula (3) becomes at least one selected from the group consisting of a p-ethenylbenzyl group and an m-ethenylbenzyl group. The melting point and softening point of the ether resin can be arbitrarily changed. For example, when p-chloromethylstyrene is used, the symmetry becomes good, and a polyphenylene ether resin having a high melting point and a high softening point can be obtained. Also, a mixture of p-chloromethylstyrene and m-chloromethylstyrene Can be used to obtain a polyphenylene ether resin having a low melting point and a low softening point, and the workability during molding is improved.

  The alkali metal hydroxide is not particularly limited, and for example, potassium hydroxide, sodium hydroxide, a mixture thereof, and the like can be used. In addition, it is preferable that the mixture ratio of an alkali metal hydroxide is about 1.1-2.0 times mole with respect to 1 mol of phenol groups.

  In carrying out ethenyl benzylation, a phase transfer catalyst may be used. The phase transfer catalyst has a function of incorporating an alkali metal hydroxide and is soluble in both a phase composed of a polar solvent such as water and a phase composed of a nonpolar solvent such as an organic solvent. It is a catalyst that can move. When a phase transfer catalyst is not used, it is difficult to solubilize only alkali metal hydroxide in a nonpolar solvent, so halogenation is performed from polyphenylene ether resin and halogenated methylstyrene dissolved in the nonpolar solvent. It may take a long time to desorb hydrogen. However, in the presence of the phase transfer catalyst, the alkali metal hydroxide dissolved in the polar solvent is taken into the phase transfer catalyst and then transferred into the nonpolar solvent by the phase transfer catalyst. Hydroxides can be easily solubilized in nonpolar solvents, and ethenylbenzylation can be promoted. The phase transfer catalyst is not particularly limited, and for example, a quaternary ammonium salt such as tetra-n-butylammonium bromide can be used. In the presence of a phase transfer catalyst, the ethenyl benzylation reaction is preferably performed at a temperature of 100 ° C. or lower.

  By the method described above, a polyphenylene ether resin having at least one structure (substantially upper limit is 4) represented by the general formula (1) at the molecular end can be produced.

  The low dielectric resin composition according to the present invention may contain a crosslinkable curing agent in addition to a thermosetting resin and hollow particles described later.

  Examples of the crosslinkable curing agent include triallyl isocyanurate (TAIC), triallyl cyanurate, diallyl phthalate, diallyl isophthalate, diallyl maleate, diallyl fumarate, diethylene glycol diallyl carbonate, triallyl phosphate, ethylene glycol diallyl ether, triaryl ether Compounds such as allyl ether of methylolpropane, partially allyl ether of pentaerythritol, diallyl sebacate, allylated novolak, allylated resole resin are used. Among these, triallyl isocyanate is preferable from the viewpoint that the dielectric loss tangent which affects the variation in transmission time can be lowered.

  In the present invention, hollow particles satisfying the following three conditions are used.

First, as a first condition, 98% by mass or more (substantially upper limit is 100% by mass) of the entire shell is required to be formed of silica (SiO ₂ ). If the silica content is less than 98% by mass of the entire shell, the dielectric constant, dielectric loss tangent, thermal expansion coefficient may increase, and insulation reliability may decrease. Here, the hollow particles can be produced by the sol-gel method. Even if 98% by mass or more of the entire shell is formed of silica, the hollow particles have a large number of silanol groups and poor dielectric loss tangent. Therefore, it is preferable to manufacture by a flame melting method. As the component occupying less than 2% by weight of the total shell include, for _{example, CaO, Al 2 O 3, B} 2 O 3, MgO, Na 2 O, K 2 O, and TiO ₂ or the like. The hollow part of the hollow particles is filled with an inert gas such as nitrogen, oxygen or argon, or a mixed gas such as air.

  Next, as the second condition, the average porosity is required to be 30 to 80% by volume. If the average porosity is less than 30% by volume, the ratio of the hollow portions of the hollow particles is too small to sufficiently reduce the dielectric constant. Conversely, if the average porosity exceeds 80% by volume, the laminate The hollow particles are broken during the production of the plate and the dielectric constant cannot be lowered. In particular, it is preferable to use hollow particles having an average porosity of 50 to 80% by volume. Thereby, the thermal expansion coefficient can be further reduced. The average porosity is measured by the pycnometer method and the ratio of the average specific gravity to the specific gravity of the material forming the hollow particles is (1− (average specific gravity / specific gravity of the material forming the hollow particles)) × 100 ( Volume%). The specific gravity of the hollow particles is about 0.9 to 1.3, more preferably about 0.9 to 1.1. Specific examples of such hollow particles include “DBS series” manufactured by Denki Kagaku Kogyo Co., Ltd. and the like.

  Finally, as a third condition, the average particle size is required to be 0.1 to 20 μm. When the average particle size is less than 0.1 μm, the fluidity is deteriorated and the resin flow of the prepreg is lowered. On the contrary, when the average particle size is more than 20 μm, the insulation reliability is lowered, and a recent laminated board The appearance of the laminate is deteriorated due to the reduction in thickness. In particular, it is preferable to use hollow particles having an average particle size of 0.5 to 5 μm. Thereby, solder heat resistance can further be improved. The average particle size can be measured by a laser diffraction particle size distribution measurement method, for example, using a CILAS Model 920L laser diffraction particle size distribution measurement device or the like.

  Moreover, as the hollow particles, it is preferable to use those whose surfaces have been subjected to a hydrophobic treatment. This hydrophobizing treatment can be performed using a coupling agent. When an epoxy resin is used as the thermosetting resin, epoxy silane, aminosilane or the like is used as the coupling agent, and when a polyphenylene ether resin is used as the thermosetting resin, vinyl silane or silazane is used as the coupling agent. Is preferred. Thus, when the surface of the hollow particles is hydrophobized using a coupling agent, the solder heat resistance during moisture absorption can be further increased, and the dispersibility when preparing the varnish can be increased. In addition, interlayer adhesion and insulation reliability in the laminate can be improved.

  And it is preferable that content of a hollow particle is 5-30 mass% with respect to the low dielectric resin composition whole quantity. As a result, the solder heat resistance, the insulation reliability, and the resin flow of the prepreg can be further increased, and the appearance of irregularities on the surface of the laminated plate can be prevented and a good appearance can be obtained. However, if the content of the hollow particles is less than 5% by mass, the effect of lowering the dielectric constant may not be sufficiently obtained. Conversely, if the content of the hollow particles exceeds 30% by mass, the moisture absorption There is a possibility that the solder heat resistance at the time is lowered, the resin flow of the prepreg is lowered, and the interlayer adhesion and insulation reliability in the laminated board are lowered. In particular, the content of the hollow particles is more preferably 5 to 20% by mass. Thereby, wear of a drill used for drilling a through hole or the like is reduced, and the life of the drill can be extended. Furthermore, the content of the hollow particles is more preferably 10 to 20% by mass. As a result, the dielectric constant, dielectric loss tangent, and thermal expansion coefficient can be further reduced.

  As described above, since the low dielectric resin composition according to the present invention contains a thermosetting resin and predetermined hollow particles, the dielectric constant, dielectric loss tangent, and thermal expansion coefficient can all be reduced. In addition, high insulation reliability can be obtained.

  The low dielectric resin composition according to the present invention is prepared into a varnish for the purpose of impregnating a base material during the production of a prepreg. Hereinafter, the preparation method of a varnish is demonstrated.

  When using an epoxy resin as the thermosetting resin, first, the epoxy resin is dissolved in a heated organic solvent, and further, a curing agent such as dicyandiamide (DICY) and curing acceleration such as 2-ethyl-4-methylimidazole (2E4MZ) are performed. A resin varnish is prepared by adding an agent and stirring and mixing it. Next, after cooling this resin varnish, a hollow particle is added, and it stirs and mixes again, The varnish of a low dielectric resin composition can be obtained.

  On the other hand, when a polyphenylene ether resin is used as the thermosetting resin, first, the polyphenylene ether resin is dissolved in a heated organic solvent, and further, a crosslinkable curing agent such as triallyl isocyanurate (TAIC) and di (t-butylperoxide) are used. A resin varnish is prepared by adding a reaction initiator such as oxyisopropyl) benzene and stirring and mixing it. Next, after cooling this resin varnish, a hollow particle is added, and it stirs and mixes again, The varnish of a low dielectric resin composition can be obtained.

  The organic solvent is not particularly limited as long as it does not dissolve the resin component and does not adversely affect the reaction. For example, ketones such as methyl ethyl ketone (MEK), ethers such as dibutyl ether, acetic acid Esters such as ethyl, amides such as dimethylformamide (DMF), aromatic hydrocarbons such as benzene, toluene and xylene, and a suitable organic solvent such as chlorinated hydrocarbons such as trichloroethylene may be used. A mixture of more than one can be used. What is necessary is just to adjust the solid content density | concentration of the said varnish suitably according to the operation | work which makes a base material impregnate in manufacturing a prepreg, for example, 20-80 mass% is suitable.

  Further, the method of stirring and mixing is not particularly limited as long as each component is uniformly dissolved or dispersed in a solvent. Specifically, a planetary mixer, a ball mill, a bead mill, a roll mill, etc. The method using is preferable.

  The prepreg according to the present invention is produced by impregnating the base material with the low dielectric resin composition obtained as described above and heating and drying it until it is in a semi-cured state (B stage state). be able to.

  As the base material, glass cloth made of glass fiber, woven fabric of organic fiber, or the like can be used, but it has excellent dimensional stability and high balance of performance such as high rigidity. It is preferable to use it.

  Moreover, it is preferable that content of the low dielectric resin composition in a prepreg is 40-95 mass%. If the content is less than 40% by mass, voids, creases and the like may occur during molding. In addition, since it is difficult for content to exceed 95 mass%, a substantial upper limit will be 95 mass%.

  Further, in producing the prepreg, the impregnation can be performed by dipping or coating. The impregnation can be repeated several times as necessary. At this time, the impregnation can be repeated using a plurality of solutions having different compositions and concentrations, and finally adjusted to a desired composition and resin amount. Is possible.

  Moreover, the base material impregnated with the varnish of the low dielectric resin composition becomes a semi-cured prepreg by being heated at a desired heating condition, for example, 80 to 170 ° C. for 1 to 10 minutes.

  Next, the metal-clad laminate according to the present invention can be manufactured by laminating the prepreg and the metal foil obtained as described above and heating and pressing the prepreg. Specifically, a double-sided metal-clad laminate is obtained by stacking metal foils such as copper foil on both sides or one side of a prepreg (one or two or more layers), and heating and pressurizing and integrating them. Alternatively, a single-sided metal-clad laminate can be obtained.

  And the printed wiring board which concerns on this invention can be manufactured by forming a circuit in the metal-clad laminated board obtained as mentioned above. Specifically, a printed wiring board can be obtained by removing the metal foil on the surface of the metal-clad laminate by etching to form a conductor pattern. Moreover, a multilayer printed wiring board can also be manufactured using this printed wiring board as a core material.

  As described above, since the prepreg, the metal-clad laminate, and the printed wiring board (including a multilayer printed wiring board) according to the present invention are all manufactured using a low dielectric resin composition as a material, the dielectric constant, Both the dielectric loss tangent and the coefficient of thermal expansion can be reduced, and insulation reliability can be increased.

  Hereinafter, the present invention will be specifically described by way of examples.

(Examples 1-9, 11, 12, 15)
In the blending amount shown in the following [Table 1], first, a mixed solvent (room temperature) of dimethylformamide (DMF) and methyl ethyl ketone (MEK) is “YDB-500EK75” (epoxy equivalent) manufactured by Toto Kasei Co., Ltd., which is a brominated epoxy resin. 500, solid content 75% by mass) and “YDCN220EK75” (epoxy equivalent 210, solid content 75% by mass) manufactured by Toto Kasei Co., Ltd., which is a cresol novolak type epoxy resin, and further dicyandiamide manufactured by Nippon Carbide Co., Ltd. (DICY) and 2-ethyl-4-methylimidazole (2E4MZ) manufactured by Shikoku Kasei Kogyo Co., Ltd. were added, and this was stirred and mixed to prepare a resin varnish. Next, after cooling this resin varnish to room temperature, hollow particles (“hollow particles-1” to “hollow particles-8”) are added in the blending amounts shown in [Table 4] to [Table 6] below, and again. The low dielectric resin composition varnishes of Examples 1 to 9, 11, 12, and 15 were obtained by stirring and mixing at 3000 rpm for 30 minutes using a disper.

(Example 10)
Examples 1 to 9, except that the hollow particles used were “KBM403” manufactured by Shin-Etsu Chemical Co., Ltd., which is an epoxy silane, whose surface was hydrophobized (“Hollow Particles-9”). In the same manner as in Nos. 11, 12, and 15, a varnish of the low dielectric resin composition of Example 10 was obtained.

(Example 13)
First, “Noryl PX9701” (Mn = 20000) manufactured by Japan GE Plastics Co., Ltd., which is a polyphenylene oxide resin, is dissolved in toluene heated to 90 ° C. in the blending amounts shown in [Table 2] below. A resin varnish was prepared by adding “Perbutyl P” manufactured by Nippon Oil & Fats Co., Ltd., which is triallyl isocyanurate (TAIC) and di (t-butylperoxyisopropyl) benzene, and stirring and mixing them. . Next, after cooling this resin varnish to room temperature, hollow particles (“hollow particle-10”) are added in the blending amounts shown in [Table 6] below, and the mixture is stirred and mixed again at 3000 rpm for 30 minutes using a disper. Thus, a varnish of the low dielectric resin composition of Example 13 was obtained. However, the hollow particles (“hollow particles-10”) are obtained by hydrophobizing the surface using “KBM1003” manufactured by Shin-Etsu Chemical Co., Ltd., which is vinyl silane.

(Example 14)
First, the molecular weight of the high molecular weight polyphenylene ether resin was reduced as follows.

  200 g of toluene was placed in a 2000 mL flask equipped with a stirrer and a stirring blade. While controlling the flask at an internal temperature of 80 ° C., high molecular weight polyphenylene ether resin “Noryl PX9701” manufactured by Japan GE Plastics Co., Ltd .: 100 g, bisphenol A: 4.3 g, t-butylperoxyisopropyl monocarbonate “Perbutyl I” manufactured by Nippon Oil & Fats Co., Ltd .: 2.94 g and cobalt naphthenate solution (8 mass% solution dissolved in toluene): 0.0042 g are added and stirred until the high molecular weight polyphenylene ether is completely dissolved. Thus, a low molecular weight polyphenylene ether resin was prepared.

  The low molecular weight polyphenylene ether obtained was reprecipitated with a large amount of methanol to remove impurities, and dried at 80 ° C. under reduced pressure for 3 hours to completely remove toluene.

  Next, the low molecular weight polyphenylene ether resin obtained as described above was ethenylbenzylated as follows.

  200 g of the low-molecular-weight polyphenylene ether resin in a 1 L three-necked flask equipped with a temperature controller, a stirrer, a cooling facility, and a dropping funnel, chloromethylstyrene (ratio of p-chloromethylstyrene and m-chloromethylstyrene is 1 1; manufactured by Tokyo Chemical Industry Co., Ltd.): 15 g, tetra-n-butylammonium bromide: 0.8 g, toluene: 400 g were charged, dissolved by stirring, the liquid temperature was adjusted to 75 ° C., and an aqueous sodium hydroxide solution (hydroxide) Sodium 10 g / water 10 g) was added dropwise over 20 minutes, and stirring was further continued at 75 ° C. for 4 hours. Next, after neutralizing the contents of the flask with a 10% by mass hydrochloric acid aqueous solution, a large amount of methanol was added to obtain ethenylbenzylated polyphenylene ether as a precipitate. The precipitate filtrate is washed three times with a mixed solution of methanol and water (80:20 mass ratio) and then treated under reduced pressure at 80 ° C. for 3 hours to remove ethenylbenzyl from the solvent and water. The polyphenylene ether resin was taken out.

  When the number average molecular weight of the obtained ethenylbenzylated polyphenylene ether resin was measured by GPC, the number average molecular weight (Mn) was 3,500. The number average molecular weight was measured by gel permeation chromatography (GPC) using TSK guard column HXL-4, G4000HXL: 1, G3000HXL: 1, G2000HXL: 1, G1000HXL: 2 columns.

  Then, using the ethenylbenzylated polyphenylene ether resin (modified polyphenylene ether resin) obtained as described above, a low dielectric resin composition was prepared as follows.

  First, the modified polyphenylene ether resin (Mn = 3500) obtained as described above is dissolved in toluene heated to 70 ° C. in the blending amounts shown in [Table 3] below. A resin varnish was prepared by adding allyl isocyanurate (TAIC) and “perbutyl P” manufactured by NOF Corporation, which is di (t-butylperoxyisopropyl) benzene, and stirring and mixing them. Next, after cooling this resin varnish to room temperature, hollow particles (“hollow particle-10”) are added in the blending amounts shown in [Table 6] below, and the mixture is stirred and mixed again at 3000 rpm for 30 minutes using a disper. Thus, a varnish of the low dielectric resin composition of Example 14 was obtained. However, the hollow particles (“hollow particles-10”) are obtained by hydrophobizing the surface using “KBM1003” manufactured by Shin-Etsu Chemical Co., Ltd., which is vinyl silane.

(Examples 16 to 20)
Hollow particles ("Hollow particle-13" to "Hollow particle-16") were added to the same resin varnish as in Example 14 in the blending amounts shown in [Table 7] below, and 30 minutes at 3000 rpm using a disper. By stirring and mixing, the varnishes of the low dielectric resin compositions of Examples 16 to 20 were obtained. However, the hollow particles (“hollow particle-13” to “hollow particle-15”) are obtained by hydrophobizing the surface using “KBM1003” manufactured by Shin-Etsu Chemical Co., Ltd., which is vinyl silane.

(Comparative Example 1)
As the hollow particles, silica having 90% by mass of the entire shell and an average particle size of 40 μm (“hollow particle-12”: “Glass Bubble Filler K37” manufactured by Sumitomo 3M Co., Ltd.) was used. Except for the above, a varnish of Comparative Example 1 was obtained in the same manner as in Examples 1 to 9, 11, 12, and 15.

(Comparative Example 2)
A varnish of Comparative Example 3 was obtained in the same manner as in Examples 1 to 9, 11, 12, and 15 except that no hollow particles were used.

(Comparative Example 3)
Examples 1-9, 11 and 11 except that the hollow particles produced by the sol-gel method (“hollow particles-11”) were used and the content of the hollow particles was set to 10% by mass. In the same manner as in Nos. 12 and 15, the varnish of Comparative Example 3 was obtained.

(Comparative Example 4)
A varnish of Comparative Example 4 was obtained in the same manner as in Example 16 except that “FB-5SDC” which is fused silica was used instead of the hollow particles.

(Manufacture of prepreg)
Each varnish obtained as described above is impregnated into a base material (“WEA116E” manufactured by Nittobo, which is a glass cloth), and then heated and dried under the drying conditions shown in the following [Table 1] to [Table 3]. A prepreg was obtained by removing the solvent.

(Manufacture of laminates)
Six prepregs obtained as described above are stacked, 35 μm thick copper foil (ST foil) is arranged on both surfaces, and heated and pressurized under the curing conditions shown in the following [Table 1] to [Table 3]. Thus, a double-sided copper clad laminate I having a thickness of 0.75 mm was obtained.

  On the other hand, a 35 μm thick copper foil (ST foil) is placed on both sides of one prepreg obtained as described above, and heated and pressurized under the curing conditions shown in the following [Table 1] to [Table 3]. Thus, a double-sided copper clad laminate II having a thickness of 0.13 mm was obtained.

(Dielectric constant / dielectric loss tangent)
The dielectric properties at 1 GHz of the double-sided copper-clad laminate I were measured based on IPC TM-650 2.5.5.9.

(Coefficient of thermal expansion)
The copper foils on both sides of the double-sided copper clad laminate I are etched to produce a test piece, and this test piece is measured at a temperature rise of 75 to 120 ° C. using a TMA measuring apparatus (Seiko Instruments Co., Ltd.). The coefficient of thermal expansion (thickness direction) was measured.

(PCT solder heat resistance)
The copper foils on the front and back sides of the double-sided copper-clad laminate I were etched and subjected to pressure cooker treatment (121 ° C., humidity 100%). The treated double-sided copper-clad laminate was immersed in a 260 ° C. solder bath for 20 seconds, and then the time during which no abnormal appearance such as swelling occurred was evaluated.

(Appearance observation of laminated board)
Visually observe the appearance of the double-sided copper clad laminate II. “◎” indicates that there is no unevenness, “○” indicates that there is a slight unevenness but there is no problem as a product, and “×” indicates that the surface has unevenness. It was evaluated.

(Insulation reliability)
The double-sided copper clad laminate II was subjected to pressure cooker treatment (110 ° C., humidity 85%, treatment for 100 hours).

  And the voltage of 50V was applied to the double-sided copper clad laminated board II after the said process for predetermined time, the resistance value was measured, and the presence or absence of abnormality was confirmed. “A” indicates that no abnormality is observed even when a voltage is applied for 300 hours, “O” indicates that no abnormality is observed even when a voltage is applied for 100 hours, and an abnormality is observed until the voltage application time reaches 100 hours. What was seen was evaluated as “×”.

(Prepreg resin flow (Glinis))
The resin flow of the prepreg was measured based on JIS C 6521. A resin flow RF (%) of 10% or more was evaluated as “◎”, 5% or more and less than 10% as “◯”, and less than 5% as “×”.

(Drill wear evaluation)
The double-sided copper-clad laminate I was used as the core material 1, and as shown in FIG. 1, four core materials 1 were sandwiched between the entry board 2 and the backup board 3, and then drilled by a drilling machine 4. . “LE400” manufactured by Mitsubishi Gas Chemical Co., Ltd. is used as the entry board 2, a bake plate having a thickness of 1.5 mm is used as the backup board 3, and “ND-1V211” manufactured by Hitachi Seiko Co., Ltd. is used as the drilling machine 4. Was used. The drill bit 5 has a drill diameter of φ0.4 mm (union: UV L092A / HA = 45 °), the drill rotation speed is 160 krpm (peripheral speed: 150 m / min), and the drill feed speed is 3.2 m. / Min (chip load: 20 μ / rev), 1000 holes were drilled.

  Next, the area when the drill bit 5 before and after drilling was viewed from the tip was image-analyzed, the decrease in the area was obtained, and the drill wear rate was calculated. The drill wear rate of less than 40% is “◎”, 40% or more and less than 50% is “◯”, and 50% or more and less than 60% is “Δ”, and is 60% or more. Things were rated as “x”.

  The above test results are shown in [Table 4] to [Table 8] below.

It is a front view which shows the mode of a drill process.

Claims (12)

  In the low dielectric resin composition containing hollow particles composed of a shell and a hollow portion and a thermosetting resin, 98% by mass or more of the entire shell is formed of silica as hollow particles, and the average porosity is 30 to 80. A low dielectric resin composition comprising: a volume percentage and an average particle diameter of 0.1 to 20 μm.   2. The low dielectric resin composition according to claim 1, wherein the hollow particles are those having an average porosity of 50 to 80% by volume.   The low dielectric resin composition according to claim 1 or 2, wherein the hollow particles are those having an average particle diameter of 0.5 to 5 µm.   The low dielectric resin composition according to any one of claims 1 to 3, wherein the hollow particles are those having a hydrophobic surface.   The low dielectric resin composition according to any one of claims 1 to 4, wherein the content of the hollow particles is 5 to 30% by mass with respect to the total amount of the low dielectric resin composition.   The low dielectric resin composition according to any one of claims 1 to 5, wherein the content of the hollow particles is 5 to 20 mass% with respect to the total amount of the low dielectric resin composition.   The low dielectric resin composition according to any one of claims 1 to 6, wherein the content of the hollow particles is 10 to 20% by mass with respect to the total amount of the low dielectric resin composition.   The low dielectric resin composition according to any one of claims 1 to 7, wherein a polyphenylene ether resin is used as the thermosetting resin. 9. The low dielectric resin composition according to claim 8, wherein the polyphenylene ether resin has a structure represented by the following formula (1) and has a number average molecular weight of 3000 to 7000.

  A prepreg obtained by impregnating a low dielectric resin composition according to any one of claims 1 to 9 into a substrate and heating and drying it.   A metal-clad laminate obtained by laminating the prepreg according to claim 10 and a metal foil and heating and pressing the laminate.   A printed wiring board comprising a circuit formed on the metal-clad laminate according to claim 11.

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