JP2015229763A - Resin composition, prepreg, metal-clad laminate sheet, printed wiring board - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a resin composition that can realize both a lowered dielectric constant and lowered linear expansion coefficient of the resin composition's cured product without relying on the means of reducing the contained amount of the inorganic filler.SOLUTION: Provided is a resin composition for printed wiring boards, and the resin composition contains an epoxy resin, at least any one of phenol-based curing agent and amine-based curing agent, a carbodiimide resin represented by the formula (1), and an inorganic filler.

Description

  The present invention relates to a resin composition, a prepreg, and a metal-clad laminate used as a material for a printed wiring board, and also relates to a printed wiring board manufactured using these.

  Conventionally, when manufacturing a printed wiring board, a resin composition as a material has been required to have a low dielectric constant for high-speed signal transmission, high-frequency response, impedance control, and the like. As a method for this, for example, a method using a resin having a lower relative dielectric constant than that of a general resin by changing the basic skeleton of the resin used in the resin composition, or an inorganic filling that can cause a high dielectric constant The method etc. which reduce content in the resin composition of a material are mentioned.

  However, in the former method of changing the basic skeleton of the resin, it may be necessary to change the manufacturing process due to a change in workability when manufacturing a printed wiring board. Further, in the latter method of reducing the content of the inorganic filler, the coefficient of thermal expansion (CTE) of the cured product of the resin composition is increased, which can be a factor of lowering reliability.

  Under such circumstances, for example, Patent Document 1 describes a thermosetting resin composition capable of obtaining a cured product that exhibits a sufficiently low dielectric loss tangent while maintaining a low dielectric constant. This thermosetting resin composition contains a thermosetting resin, an active ester compound having an active ester group, and a carbodiimide compound having a carbodiimide group.

JP 2006-335834 A

  Currently, widely used materials for printed wiring boards include combinations of epoxy resins and phenolic curing agents, combinations of epoxy resins and amine curing agents, combinations of epoxy resins, phenolic curing agents and amine curing agents. It is a resin composition based on the above.

  However, although Patent Document 1 describes that an epoxy resin is preferable as the thermosetting resin, it is possible to reduce the dielectric constant and the coefficient of linear expansion of the cured product of the resin composition based on the above combination. It is not described to realize both.

  In addition, increasing the content of inorganic fillers such as silica in the resin composition makes it easier to achieve a low linear expansion coefficient, but the inorganic filler itself has a high dielectric constant, so a low dielectric constant can be realized. It becomes difficult. Conversely, if the content of the inorganic filler is reduced in order to realize a low dielectric constant, it is difficult to realize a low linear expansion coefficient.

  The present invention has been made in view of the above points, and it is possible to reduce the dielectric constant and the linear expansion coefficient of the cured product of the resin composition without using a means for reducing the content of the inorganic filler. An object is to provide a resin composition, a prepreg, a metal-clad laminate, and a printed wiring board that can realize both.

  In order to solve the above problems, the inventors of the present application provide a second grade generated by a curing reaction between an epoxy and a curing agent in an epoxy resin-based resin composition using a phenolic curing agent or an amine curing agent as a curing agent. Focusing on the possibility that the hydroxyl group is a factor in increasing the dielectric constant, we considered improving the dielectric constant by reducing the secondary hydroxyl group remaining in the resin curing system. As a means for reducing secondary hydroxyl groups, attention was focused on carbodiimide resins that can react with secondary hydroxyl groups. However, when a carbodiimide resin is included as a component of the resin composition, when the resin varnish is impregnated into a fiber substrate such as a glass cloth, the varnish impregnation property may be lowered, for example, an unimpregnated part is partially formed. there were. As a result of further investigation, it was found that the dielectric constant of the resin composition can be reduced without lowering the varnish impregnation property by using a specific carbodiimide, and the present invention has been completed.

The resin composition according to the present invention is:
A resin composition for a printed wiring board,
The resin composition is
Epoxy resin,
At least one of a phenolic curing agent and an amine curing agent;
A carbodiimide resin represented by the formula (1);
And an inorganic filler.

In the resin composition,
The relative dielectric constant of the cured product of the resin composition is 3.3 or less,
It is preferable that the linear expansion coefficient at the glass transition temperature or lower of the cured product of the resin composition is 65 ppm / ° C. or lower.

In the resin composition,
It is preferable that the carbodiimide resin is contained so that a carbodiimide equivalent of the carbodiimide resin is within a range of 0.1 to 0.6 with respect to an epoxy equivalent of the epoxy resin.

In the resin composition,
Silica is included in the inorganic filler,
It is preferable that the content of the inorganic filler is in the range of 30 to 80 parts by mass with respect to 100 parts by mass of the residue obtained by removing the inorganic filler from the resin composition.

in this case,
In addition to the silica, the inorganic filler may contain one or more selected from the group consisting of metal hydroxides, metal oxides, metal carbonates, metal sulfates, and metal silicates. .

In that case,
It is preferable that the content of the inorganic filler other than silica is 15 parts by mass or less with respect to 100 parts by mass of the residue.

In the resin composition,
The number average molecular weight of the carbodiimide resin is preferably in the range of 1000 to 3000.

  The prepreg according to the present invention is characterized in that the resin composition is impregnated in a base material and semi-cured.

  The metal-clad laminate according to the present invention is characterized in that a metal foil is superimposed on the prepreg and formed by heating and pressing.

  The printed wiring board according to the present invention is characterized in that a conductor pattern is formed by removing a part of the metal foil of the metal-clad laminate.

  According to the present invention, the amount of the secondary hydroxyl group in the cured product of the resin composition by reacting the carbodiimide resin represented by the formula (1) with the secondary hydroxyl group generated by the curing reaction between the epoxy resin and the curing agent. Is reduced. Thereby, both the low dielectric constant and the low linear expansion coefficient of the cured product of the resin composition can be realized without using means for reducing the content of the inorganic filler.

  Embodiments of the present invention will be described below.

  The resin composition according to the embodiment of the present invention will be described. The resin composition is used for a printed wiring board and contains an epoxy resin, a curing agent, a carbodiimide resin, and an inorganic filler as essential components.

  First, the respective components constituting the resin composition will be described.

  Examples of the epoxy resin include alicyclic epoxies such as bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol S type epoxy resin, naphthalene skeleton type epoxy resin, biphenyl type epoxy resin, and dicyclopentadiene skeleton containing epoxy resin. Resin, diglycidyl ether compound of polyfunctional phenol, diglycidyl ether compound of polyfunctional alcohol, phenol novolac type epoxy resin, cresol novolac type epoxy resin, bisphenol A novolac type epoxy resin, bromine-containing epoxy resin obtained by brominating these, Examples thereof include a phosphorus-containing epoxy resin modified with a phosphorus compound. One or more selected from these groups can be used.

  Further, as the curing agent, at least one of a phenolic curing agent and an amine curing agent is used. That is, either the phenolic curing agent or the amine curing agent may be used, or both the phenolic curing agent and the amine curing agent may be used.

  Here, the phenolic curing agent is not particularly limited as long as it is bifunctional or higher. For example, it has bisphenol A, bisphenol F, phenol novolac resin, cresol novolac resin, bisphenol A type novolac resin, triazine ring. A phenolic novolac resin can be used.

  On the other hand, the amine curing agent is not particularly limited as long as it is bifunctional or higher, and examples thereof include diaminodiphenylmethane, dicyandiamide, and triamine.

  One or more selected from the group of the phenolic curing agent and the amine curing agent can be used. Furthermore, other difunctional or higher curing agents may be used in combination as long as the object of the present invention is not impaired. In the resin composition, the curing agent may be contained so that an active hydrogen equivalent of the curing agent is within a range of 0.7 to 1.3 with respect to an epoxy equivalent of the epoxy resin. More preferably, it exists in the range of 0.8-1.2.

  The carbodiimide is a general term for chemical substances including a functional group (carbodiimide group) represented by the chemical formula -N = C = N-. In the present embodiment, the carbodiimide is particularly represented by the formula (1). Resin is used. As said carbodiimide resin, what uses tetramethyl-m-xylylene diisocyanate as a raw material can be mentioned, for example. In general, a reaction between an epoxy resin and a phenolic curing agent, or a reaction between an epoxy resin and an amine curing agent generates a secondary hydroxyl group. This secondary hydroxyl group causes a dielectric constant to increase. On the other hand, the presence of the carbodiimide resin represented by the formula (1) in the same reaction system causes the carbodiimide group of the carbodiimide resin to react with the secondary hydroxyl group, and the secondary hydroxyl group disappears. It is considered that the relative dielectric constant of the cured product of the resin composition is reduced. Here, if it is used without specifying the type of carbodiimide resin as the resin component, the resin composition becomes thickened when it is varnished, impregnation into the fiber base material is impaired, or when thermoforming There is a concern that the moldability and the heat resistance of the cured product of the resin composition are lowered. On the other hand, in the present invention, by using the specific carbodiimide resin represented by the formula (1), the dielectric constant can be reduced without adversely affecting these characteristics. Therefore, in the resin composition, the dielectric constant can be reduced without using means for reducing the content of the inorganic filler described later. Therefore, the trade-off between the merit of lowering the linear expansion coefficient of the cured product of the resin composition obtained by using the inorganic filler and the demerit of increasing the dielectric constant is solved. It is possible to achieve a low linear expansion coefficient and a low dielectric constant of the cured product.

  In the resin composition, the linear expansion coefficient at the glass transition temperature or lower of the cured product is preferably 65 ppm / ° C. or lower, and more preferably 62 ppm / ° C. or lower. In the resin composition, the relative dielectric constant of the cured product is preferably 3.3 or less, and more preferably 3.2 or less.

  The number average molecular weight (Mn) of the carbodiimide resin represented by the formula (1) is preferably in the range of 1000 to 3000. When the number average molecular weight is 1000 or more, a sufficient amount of carbodiimide groups can be secured and the remaining secondary hydroxyl groups can be suppressed. When the number average molecular weight is 3000 or less, the resin composition can be suitably varnished, and the impregnation of the varnish into the substrate can be further improved.

  In the resin composition, the carbodiimide equivalent of the carbodiimide resin represented by the formula (1) is within the range of 0.1 to 0.6 with respect to the epoxy equivalent of the epoxy resin. It is preferable that a carbodiimide resin is contained. When the carbodiimide equivalent is 0.1 or more, the relative dielectric constant of the cured product of the resin composition can be further reduced. Moreover, when the said carbodiimide equivalent is 0.6 or less, it can suppress that unreacted carbodiimide resin remains, and can improve the heat resistance of the hardened | cured material of the said resin composition.

  Examples of the carbodiimide resin other than the carbodiimide resin represented by the formula (1) include those using hydrogenated methylene diphenyl diisocyanate as a raw material and those using diphenylmethane diisocyanate as a raw material. However, even if a resin composition is prepared using such a carbodiimide resin, the impregnation property to a base material is bad, and there exists a possibility that a prepreg cannot be manufactured.

  Further, as the inorganic filler, it is preferable to use a material containing at least silica. Furthermore, the content of the inorganic filler is preferably in the range of 30 to 80 parts by mass of the inorganic filler with respect to 100 parts by mass of the remaining amount obtained by removing the inorganic filler from the total amount of the resin composition. . When the content of the inorganic filler is 30 parts by mass or more, the linear expansion coefficient below the glass transition temperature of the cured product of the resin composition can be further reduced. Moreover, the specific dielectric constant of the hardened | cured material of the said resin composition can further be reduced because content of the said inorganic filler is 80 mass parts or less. Hereinafter, a residue obtained by removing the inorganic filler from the total amount of the resin composition is also simply referred to as a residue. Thus, although the said inorganic filler is remove | excluded in the remainder, various additives etc. may be contained.

  The inorganic filler contains at least one selected from the group consisting of metal hydroxides, metal oxides, metal carbonates, metal sulfates, and metal silicates as inorganic fillers other than silica. May be. Examples of the metal hydroxide include aluminum hydroxide and magnesium hydroxide. Examples of the metal oxide include aluminum oxide such as alumina, magnesium oxide, and the like. Examples of the metal carbonate include calcium carbonate. Examples of the metal sulfate include magnesium sulfate. Examples of the metal silicate include magnesium silicate. One or more selected from these groups can be used. In this case, the content of the inorganic filler other than silica is preferably 15 parts by mass or less with respect to the remaining 100 parts by mass. Thereby, other characteristics, such as a flame retardance, can be provided, implement | achieving both low dielectric constant reduction and low linear expansion coefficient about the hardened | cured material of the said resin composition. This is suitable for producing FR-4 grade metal-clad laminates.

  Furthermore, the resin composition may contain additives such as a curing accelerator as an optional component as required. As the curing accelerator, for example, an imidazole compound, an organic phosphate compound, a tertiary amine, or the like can be used. The content of the curing accelerator is not particularly limited as long as the object of the present invention is not impaired.

  Next, the preparation method of the resin composition of this embodiment is demonstrated. The resin composition is prepared by mixing the epoxy resin, the curing agent, the carbodiimide resin, the inorganic filler, and other components as required, in predetermined amounts, mixing them in a solvent, and further stirring. It can prepare as a resin varnish by mixing. At this time, a resin varnish containing only the residue excluding the inorganic filler may be used as a base resin (varnish), and the inorganic filler may be added to the base resin. Examples of the solvent include ethers such as ethylene glycol monomethyl ether, ketones such as acetone and methyl ethyl ketone (MEK), aromatic hydrocarbons such as benzene and toluene, dimethylformamide, and the like.

  Next, the prepreg according to the embodiment of the present invention will be described. The prepreg is obtained by impregnating a varnish of the resin composition obtained as described above into a substrate such as glass cloth, heating and drying at 110 to 140 ° C., removing the solvent in the varnish, It can be produced by semi-curing the resin composition. The resin content (content of the resin composition) of the prepreg is preferably 30 to 80% by mass with respect to the total amount of the prepreg.

  Next, the metal-clad laminate according to the embodiment of the present invention will be described. The metal-clad laminate can be produced by stacking a metal foil on the prepreg obtained as described above and heating and pressing. For example, the metal-clad laminate such as a copper-clad laminate is obtained by laminating a metal foil such as a copper foil on one or both sides of one prepreg or a plurality of the prepregs, and heating and pressing the foil. A board can be manufactured. In the metal-clad laminate, the cured product of the prepreg forms an insulating layer. The heating and pressing conditions are, for example, 140 to 200 ° C., 0.5 to 5.0 MPa, and 40 to 240 minutes.

  Next, the printed wiring board according to the embodiment of the present invention will be described. The printed wiring board is manufactured by using a subtractive method or the like to remove a portion of the metal foil of the metal-clad laminate obtained as described above by etching to form a conductor pattern. Can do.

  Moreover, a multilayer printed wiring board can be manufactured by using the said printed wiring board as a core material (inner layer material) and carrying out the lamination | stacking shaping | molding of the said prepreg on this single side | surface or both surfaces. Specifically, the conductor pattern (inner layer pattern) of the core material is roughened by black oxidation or the like, and then a metal foil is stacked on the surface of the core material via a prepreg, and this is heated and pressed to form a laminate. To do. The heating and pressing conditions at this time are, for example, 140 to 200 ° C., 0.5 to 5.0 MPa, and 40 to 240 minutes. Next, drilling and desmearing are performed as necessary. Then, a multilayer printed wiring board can be manufactured by forming a conductor pattern (outer layer pattern) using a subtractive method and plating the inner wall of the hole to form a through hole or a blind via hole. . The number of layers of the printed wiring board is not particularly limited.

  In the printed wiring board, the insulating layer is formed of an insulating layer of the metal-clad laminate, that is, a cured product of the prepreg. The cured product of the prepreg is obtained by impregnating the resin composition into a base material and curing it.

  Here, since the relative dielectric constant of the cured product of the resin composition is suitably reduced as described above, the relative dielectric constant of the cured product (insulating layer) of the prepreg is also suitably reduced. It becomes. Therefore, in the printed wiring board, since the dielectric constant of the insulating layer is lowered, when a signal is transmitted by the conductor pattern, the signal speed can be increased and a large amount of information can be processed at a high speed.

  Moreover, the cured product of the resin composition contains the carbodiimide resin represented by the formula (1) as described above, thereby reducing the dielectric constant without reducing the content of the inorganic filler. Therefore, the linear expansion coefficient of the cured product of the prepreg can also be reduced. Therefore, in the printed wiring board, the linear expansion coefficient of the insulating layer is also reduced and the reliability is improved.

  As described above, according to the present invention, the combination of the epoxy resin and the phenol-based curing agent, the epoxy resin and the amine-based curing agent can be used without using the means for reducing the content of the inorganic filler. In any combination of the epoxy resin, the phenolic curing agent, and the amine curing agent, it is possible to achieve both a low dielectric constant and a low linear expansion coefficient of the cured product of the resin composition. it can.

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

[Resin composition]
The following epoxy resin, curing agent, carbodiimide resin, inorganic filler, and curing accelerator are prepared as raw materials for the resin composition, and these raw materials are mixed in the blending amounts shown in Table 2 to make the resin composition a resin varnish As prepared. The unit of the compounding amount shown in Table 2 is part by mass for epoxy resins, curing agents, and carbodiimide resins, and phr (per hundred resin) for inorganic fillers and curing accelerators. In Table 2, “phr” means a mass part relative to 100 parts by mass when the total of the epoxy resin, the curing agent, and the carbodiimide resin is 100 parts by mass. In Table 2, “carbodiimide equivalent / epoxy equivalent” indicates the carbodiimide equivalent of the carbodiimide resin to the epoxy equivalent of 1 of the epoxy resin.

  Details of each raw material are as follows.

<Epoxy resin>
Bisphenol A type epoxy resin (“850-S” manufactured by DIC Corporation, epoxy equivalent: 180 g / eq)
<Phenolic curing agent>
Phenol novolac resin (“TD-2090” manufactured by DIC Corporation, phenol equivalent: 105 g / eq)
<Amine-based curing agent>
・ Dicyandiamide (DICY)
<Carbodiimide resin represented by Formula (1)>
-Carbodiimide resin made from tetramethyl-m-xylylene diisocyanate (Nisshinbo Chemical Co., Ltd. "V-05", Mn: 1000)
-Carbodiimide resin made from tetramethyl-m-xylylene diisocyanate (Nisshinbo Chemical Co., Ltd. "V-07", Mn: 3000)
<Other carbodiimide resins>
・ Carbodiimide resin made from hydrogenated methylenediphenyl diisocyanate (Nisshinbo Chemical Co., Ltd. “HMV-8CA”, Mn: 2000)
-Carbodiimide resin made from diphenylmethane diisocyanate (Rhein Chemie Japan Co., Ltd. “STABAXOL P”, Mn: 3500)
<Inorganic filler>
-Silica particles ("MC3000" manufactured by Admatechs Corporation)
Aluminum hydroxide particles (“CL-303” manufactured by Sumitomo Chemical Co., Ltd.)
<Curing accelerator>
2-ethyl-4-methylimidazole (“2E4MZ” manufactured by Shikoku Kasei Kogyo Co., Ltd.)
[Prepreg]
A glass cloth (E glass) as a base material was impregnated with the resin varnish, and this was heated and dried until it became a semi-cured state, thereby producing a prepreg having a resin amount of 70% by mass. The resin amount is a mass percentage of the resin composition with respect to the prepreg.

[Metal-clad laminate]
After the number of the prepregs having a thickness of about 0.8 mm after forming is stacked, and a copper foil having a thickness of 12 μm is stacked as a metal foil on both sides, 180 ° C. and 2.94 MPa (30 kgf / cm ² ). A copper clad laminate (CCL) as a metal-clad laminate was produced by heating and pressing for 60 minutes.

[Evaluation of the physical properties]
Evaluation of physical properties of varnish impregnation property, relative dielectric constant, linear expansion coefficient, and heat resistance was performed as follows. The results of each physical property evaluation are shown in Table 2.

<Varnish impregnation>
The prepreg was observed and varnish impregnation property was evaluated according to the following criteria.

“OK”: The glass cloth has no unimpregnated portion of the resin composition “NG”: The glass cloth has an unimpregnated portion of the resin composition <Relative permittivity>
The copper foil on both sides of the copper clad laminate was removed by etching to obtain an unclad plate. The relative dielectric constant of this unclad plate at a frequency of 1 GHz was measured according to IPC TM-650 2.5.5.9. This measured value was taken as the relative dielectric constant of CCL.

  Next, using the Lichtenecker logarithmic mixing rule shown in [Equation 1], the relative dielectric constant of the cured product of the resin composition was calculated from the measured relative dielectric constant of CCL. Table 1 shows the relative dielectric constant and specific gravity of silica, aluminum hydroxide and glass cloth used for the calculation.

<Linear expansion coefficient>
The copper foil on both sides of the copper clad laminate was removed by etching to obtain an unclad plate. The linear expansion coefficient in the thickness direction of the unclad plate below the glass transition temperature of the cured product of the resin composition was measured according to IPC TM-650 2.4.24C. This measured value was taken as the linear expansion coefficient of CCL.

  Next, the linear expansion coefficient of the cured product of the resin composition was calculated from the measured linear expansion coefficient of CCL using the equation shown in [Equation 2]. Table 2 shows the specific gravity of the resin composition used for the calculation.

<Heat resistance>
The copper foil on both sides of the copper clad laminate was removed by etching to obtain an unclad plate. Using a TG / DTA (Thermogravimetry / Differential Thermal Analysis) measuring device, when the temperature of the unclad plate is raised at 10 ° C./min in a nitrogen atmosphere, and the mass is reduced by 5 mass% with respect to the mass at the start of temperature elevation. The temperature was measured and the heat resistance was evaluated according to the following criteria.

“◯”: Mass decreased by 5 mass% at a temperature of 340 ° C. or higher “X”: Mass decreased by 5 mass% at a temperature of less than 340 ° C.

  As is clear from Table 2, it was confirmed that in Examples 1 to 12 compared to Comparative Examples 1 to 4, it was possible to achieve both a low dielectric constant and a low linear expansion coefficient of the cured product of the resin composition.

  A more detailed comparison between the example and the comparative example is as follows.

  Examples 1 to 3, 8, and 12 and Comparative Example 1 have the same composition except for the carbodiimide resin. Since these had the same compounding amount of the inorganic filler (silica), the linear expansion coefficients were similar, but Examples 1 to 3, 8, and 12 using the carbodiimide resin represented by the formula (1). Then, it was confirmed that relative dielectric constant becomes small compared with the comparative example 1 which does not use the said carbodiimide resin.

  Examples 1 to 3 and Examples 8 and 12 have the same composition except for the content of the carbodiimide resin represented by the formula (1). In Example 8 in which the carbodiimide equivalent was less than 0.1 with respect to epoxy equivalent 1, the relative dielectric constant was slightly higher than in Examples 1-3. On the other hand, in Example 12, in which the carbodiimide equivalent exceeded 0.6 with respect to the epoxy equivalent 1, the heat resistance was inferior. On the other hand, in Examples 1-3, both low dielectric constant and low linear expansion coefficient were realizable, and also heat resistance was favorable.

  Moreover, Example 2 and Example 9 have the same composition except content of an inorganic filler (silica). In Example 9, the content of the inorganic filler is less than 30 phr, but in Example 2, since the content of the inorganic filler is in the range of 30 to 80 phr, Example 2 has a lower linear expansion coefficient. From a viewpoint, it is better.

  Moreover, Example 10 and the comparative example 2 are the same compositions except carbodiimide resin. Since the blending amount of the inorganic filler (aluminum hydroxide) is the same, the linear expansion coefficient was almost the same, but in Example 10 using the carbodiimide resin represented by the formula (1), a comparative example was used. The dielectric constant was lower than 2.

  In Comparative Examples 3 and 4 in which the carbodiimide resin represented by the formula (1) is not used and other carbodiimide resins are used, the varnish impregnation property is lowered, and thus a copper-clad laminate for evaluating physical properties is manufactured. I could not.

Claims (9)

A resin composition for a printed wiring board,
The resin composition is
Epoxy resin,
At least one of a phenolic curing agent and an amine curing agent;
A carbodiimide resin represented by the formula (1);
A resin composition comprising an inorganic filler.

The relative dielectric constant of the cured product of the resin composition is 3.3 or less,
2. The resin composition according to claim 1, wherein a linear expansion coefficient at a glass transition temperature or lower of the cured product of the resin composition is 65 ppm / ° C. or lower. The carbodiimide resin is contained so that a carbodiimide equivalent of the carbodiimide resin is within a range of 0.1 to 0.6 with respect to an epoxy equivalent of the epoxy resin. The resin composition as described. Silica is included in the inorganic filler,
4. The content of the inorganic filler is in the range of 30 to 80 parts by mass with respect to 100 parts by mass of the remainder obtained by removing the inorganic filler from the resin composition. 5. The resin composition according to claim 1. The inorganic filler includes one or more selected from the group consisting of metal hydroxides, metal oxides, metal carbonates, metal sulfates, and metal silicates as inorganic fillers other than silica. And
The resin composition according to claim 4, wherein the content of the inorganic filler other than silica is 15 parts by mass or less with respect to 100 parts by mass of the residue. The number average molecular weight of the said carbodiimide resin exists in the range of 1000-3000, The resin composition as described in any one of Claims 1 thru | or 5 characterized by the above-mentioned. A prepreg characterized in that the resin composition according to any one of claims 1 to 6 is impregnated in a substrate and semi-cured. A metal-clad laminate, wherein the prepreg according to claim 7 is formed by overlapping a metal foil and heating and pressing. A printed wiring board, wherein a conductor pattern is formed by removing a part of the metal foil of the metal-clad laminate according to claim 8.