JP2005029734A - Prepreg for printed circuit board and multilayer printed circuit board produced by using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a prepreg for a printed circuit board moldable by hot-pressing at a relatively low temperature, having sufficient adhesiveness to conductors and giving an interlayer insulation layer having high heat-resistance, low dielectric constant, low dielectric loss tangent, low water absorption and high flame retardancy, and provide a multilayer printed circuit board having high performance and high density and producible in high work efficiency by using the prepreg. <P>SOLUTION: The prepreg for a printed circuit board is produced by impregnating a fibrous substrate with a thermosetting resin composition containing (A) a polyimide resin having carboxy group or acid anhydride group and a linear hydrocarbon structure having a number-average molecular weight of 300-6,000 and (B) an epoxy resin as essential components and semi-curing the impregnated resin composition. Preferably, the polyimide resin (A) has carboxy group or acid anhydride group, a linear hydrocarbon structure having a number-average molecular weight of 700-4,500, urethane bond, imide ring and isocyanurate ring and preferably further has a cyclic aliphatic structure. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a prepreg for a printed wiring board useful for forming an interlayer insulating layer of a multilayer printed wiring board and a multilayer printed wiring board produced using the same, and more particularly, has high heat resistance, low water absorption, low dielectric constant. The present invention relates to a prepreg for a printed wiring board having a low rate, low dielectric loss tangent and flame retardancy, and a multilayer printed wiring board produced using the same.

Conventionally, a multilayer printed wiring board has one or more prepreg sheets that are semi-cured by impregnating an epoxy resin with a substrate such as glass cloth, kraft paper, and glass nonwoven fabric on an inner circuit board on which a circuit is formed, Furthermore, it was manufactured through a process of superimposing a copper foil thereon and heating and pressurizing with a hot plate press to integrally form it.
However, since a material mainly composed of an epoxy resin is used as a thermosetting insulating resin material, sufficient characteristics have not been obtained with respect to low dielectric constant, low dielectric loss tangent, and low water absorption. .

On the other hand, introduction of an imide skeleton considered to be useful for heat resistance and low dielectric constant has also been attempted. For example, although it relates to a thermosetting composition for built-up, an aromatic diamine having an imide group and A composition using an epoxy resin has been proposed (see Patent Document 1). However, the dielectric constant is not discussed. In addition, even when viewed from the study cases of the present inventors, when a low molecular weight polyimide compound is used as a curing agent for an epoxy resin, most of the heat resistance and low dielectric properties as polyimide cannot be obtained. There are many cases that do not change. On the other hand, when a high molecular weight imide compound is used as a curing agent for an epoxy resin, the compatibility is poor and separation is almost the case.
In general, polyimide resins are used in various industries as polyimide films because of their heat resistance and dielectric characteristics, but most of them are polyimide films and cannot be used for the production of prepregs for printed wiring boards.

  In recent years, printed wiring boards are rapidly changing from conventional halogen-based flame retardants to non-halogen-based flame retardants in consideration of environmental impact. However, although most non-halogen flame retardants have sufficient properties in terms of flame retardancy, they actively improve solder heat resistance, water absorption, dielectric constant, and dielectric loss tangent as printed wiring boards. Rather, there was a concern that the characteristics were deteriorated, and the use amount was limited in most cases.

JP 2000-17148 A (Claims)

  The present invention has been made to solve the problems of the prior art as described above, and its main purpose is that it can be heated and pressed relatively easily, has sufficient adhesion to the conductor, and Pre-preg for printed wiring boards capable of forming interlayer insulation layers with high heat resistance, low dielectric constant, low dielectric loss tangent, low water absorption and flame retardancy, and high-performance, high-density multilayer prints that can be manufactured with good workability using the same It is to provide a wiring board.

In order to achieve the above object, according to the present invention, a linear hydrocarbon structure having (A) a carboxyl group or an acid anhydride group and a number average molecular weight of 300 to 6,000 is provided on a fibrous base material. There is provided a prepreg for a printed wiring board, which is impregnated with a thermosetting resin composition containing an epoxy resin as an essential component and (B) an epoxy resin as a semi-cured state.
The semi-cured state here means a solid that is solid at room temperature and fluidizes in a heated state.

In a preferred embodiment, the polyimide resin (A) comprises a carboxyl group or an acid anhydride group, a linear hydrocarbon structure having a number average molecular weight of 700 to 4,500, a urethane bond, an imide ring, and an isocyanurate ring. More preferably, a structural unit represented by the general formula (1) and a structural unit represented by the general formula (2) described later, and the general formulas (3), (4) and (5) ) Is a polyimide resin having any one or more of the terminal structures shown. The polyimide resin (A) is a polyimide resin having an acid value of 20 to 150 mgKOH / g, and the mass ratio (A) / (B) between the polyimide resin (A) and the epoxy resin (B) is 0.00. It is preferable that it is 1-10. In a preferred embodiment, the thermosetting resin composition further contains a compound (C) having two or more phenolic hydroxyl groups.
Furthermore, according to this invention, the multilayer printed wiring board by which the interlayer insulation resin layer is formed using the said prepreg is provided.

  The prepreg for a printed wiring board according to the present invention is a polyimide having (A) a carboxyl group or an acid anhydride group on a fibrous base material and a linear hydrocarbon structure having a number average molecular weight of 300 to 6,000. Because it is impregnated with a thermosetting resin composition containing resin and (B) epoxy resin as an essential component to be in a semi-cured state, it can be heat-pressed at a relatively low temperature and has sufficient adhesion to the conductor. In addition, an interlayer insulating layer having high heat resistance, flame retardancy, low dielectric constant, low dielectric loss tangent, and low water absorption can be formed with good workability. Therefore, by using such a printed wiring board prepreg, a high-performance, high-density multilayer printed wiring board can be manufactured with good workability.

As an insulating resin material for printed circuit board prepregs, the present inventors can be heat-press molded at a relatively low temperature, have high heat resistance, flame retardancy, low dielectric constant, sufficient for fibrous base materials As a result of intensive investigations on materials that satisfy the impregnation property and sufficient adhesion to the conductor, a prepreg for a printed wiring board that is made into a semi-cured state by impregnating the thermosetting resin composition into a fibrous base material has high heat resistance. It has been found that a multilayer printed wiring board using this has extremely excellent performance, and has completed the present invention. .
That is, the prepreg for a printed wiring board according to the present invention has a linear hydrocarbon structure having (A) a carboxyl group or an acid anhydride group and a number average molecular weight of 300 to 6,000 on a fibrous base material. The printed wiring board is characterized by being impregnated with a thermosetting resin composition containing the polyimide resin having (B) an epoxy resin as an essential component to be in a semi-cured state, and being capable of being heated and pressed at a relatively low temperature. By using the prepreg for the purpose, it is possible to form an interlayer insulating layer having sufficient workability and having high heat resistance, low dielectric constant, low dielectric loss tangent, low water absorption, and flame resistance with good workability. it can.

A particularly important component in the thermosetting resin composition used for preparing the prepreg for the printed wiring board of the present invention is a linear carbonization having the carboxyl group or the acid anhydride group and having a number average molecular weight of 300 to 6,000. It is a polyimide resin (A) having a hydrogen structure, and the physical properties are specific to polyimide, but it exhibits toughness due to the presence of a linear hydrocarbon structure, and has the same handling properties as an epoxy resin, The following important functions and effects are brought about for the prepreg for substrates.
(A) The imide skeleton realizes high heat resistance and a high glass transition point Tg.
(B) Since it has a carboxyl group or an acid anhydride group, it can react with an epoxy group, and can realize and improve adhesiveness, electrical characteristics, workability, and low-temperature curability, which are the characteristics of an epoxy resin.

(C) Since it has a partially linear hydrocarbon structure, it can be selectively roughened with a commercially available desmear liquid, forming irregularities on the surface of the cured coating film, and being a strong anchor with the conductor layer Excellent adhesion due to the effect is exhibited.
(D) Since it has a nitrogen-containing heterocyclic structure, it exhibits flame retardancy.
(E) Low water absorption, low dielectric constant, and low dielectric loss tangent can be realized by the linear hydrocarbon structure and the imide skeleton.
(F) When the polyimide resin contains an isocyanurate ring in particular, a polymer having a so-called hyperbranched polymer structure is formed, unlike a normal linear structure polyimide. For example, it is presumed that dendrimers having a carboxyl group or an acid anhydride group have a structure in which they are linked by a linear hydrocarbon structure. Therefore, although it is a polymer, it can be arbitrarily dissolved in an epoxy resin or an organic solvent, and its workability is similar to that of a low molecular compound or oligomer, and also has characteristics as a polymer material.

  The prepreg for a printed wiring board according to the present invention is impregnated in a fibrous base material with a thermosetting resin composition containing a polyimide resin (A) that exhibits the above-described functions and effects in combination with an epoxy resin (B). Therefore, it can be heated and pressed relatively easily, has sufficient adhesion to the conductor, and has high heat resistance, low dielectric constant, low dielectric loss tangent, low water absorption, flame retardant interlayer insulation layer Can be formed with good workability.

As a suitable method for producing the prepreg for a printed wiring board of the present invention, the polyimide resin (A) and the epoxy resin (B), preferably a compound (C) further having two or more phenolic hydroxyl groups, or other After impregnating a fibrous base material with a liquid thermosetting resin composition in which an additive is dissolved or dispersed in an organic solvent, the fiber base material is dried at about 100 to 200 ° C. for about 0.5 to 30 minutes, and semi-cured (B -Staging). At this time, what was adjusted so that the gel time of 170 degreeC may be 30 second to 120 second in the semi-hardened state is preferable. If the gel time in the semi-cured state is 29 seconds or less or does not exist, the resin does not follow the inner layer circuit and voids are likely to occur. On the other hand, when the gel time exceeds 120 seconds, a large amount of resin flows out at the time of pressing and the accuracy of the film thickness is lost, or the pressing time becomes very long, which is not economical.
Moreover, a laminated board can also be manufactured by laminating | stacking the several prepreg manufactured as mentioned above, and heat-molding. As the heat forming method, for example, a forming method of heating and pressing for about 30 to 180 minutes under conditions of about a pressure of 10 to 100 kgf / cm ² and a temperature of about 130 to 180 ° C. is suitable.
The resin content in the prepreg and laminate is preferably 30 to 60% by mass. When the amount is less than 30% by mass, an amount sufficient for remelting the resin cannot be obtained as described later, and the adhesion to the substrate is not preferable. On the other hand, when it exceeds 60% by mass, the film thickness becomes unstable.

As the fibrous base material used in the present invention, known and commonly used glass cloths, glass nonwoven fabrics, and aramid nonwoven fabrics can be used. In the case of the prepreg of the present invention, glass fiber is preferable from the viewpoint of resin fluidity (impregnation). A glass cloth having a fiber diameter of 10 μm or less, a fiber density of 40 to 80 fibers / inch, and treated with a silane coupling agent such as an epoxy silane coupling agent or an aminosilane coupling agent. More preferably, a treatment that eliminates the gap between the warp and weft nets as much as possible, for example, an MS treatment by Asahi Schwer, is used. Specific examples of the glass cloth include 1037, 1067, 1080, and 3313 manufactured by Asahi Schwer. As the glass nonwoven fabric, those having a basis weight of 15 g / m ² , a thickness of about 0.1 mm to a basis weight of 120 g / m ² , and a thickness of about 1.0 mm are preferable. Specifically, Cumulus (registered trademark) manufactured by Japan Vilene Co., Ltd. is there.
In addition, the fibrous base material used for the prepreg of the present invention is not limited to a glass cloth or an aramid nonwoven fabric, and preferably has a thickness of 100 μm or less from the viewpoint of the purpose of use.

  As a form of a method for producing a multilayer printed wiring board using the prepreg for printed wiring board of the present invention, for example, one or more prepregs for printed wiring board of the present invention are stacked on an inner circuit board on which a circuit is formed, After being integrally molded by heating and pressing with a plate press, thermosetting is performed as necessary, and then a hole (via hole, through hole, etc.) is drilled with a drill or laser processing machine, and a conductor is further formed on the hole and prepreg. After at least the step of performing the plating step (form [1]), the printed circuit board prepreg and the copper foil of the present invention are overlaid on the inner circuit board, and heated and pressed with a hot plate press to integrally form it, Heat cure if necessary, then drill holes with a drill or laser processing machine, plate the holes and connect with the inner layer circuit, then etch the surface conductor At least go through the form (in the form of [2]), and the like are preferably employed a step of patterning by. Under the present circumstances, the prepreg for printed wiring boards of this invention can also be piled up through another prepreg or an adhesive sheet.

In the above process, the resin contained in the prepreg is remelted by heating and pressurization, and strongly adheres to the inner layer circuit. Further, the unevenness on the surface of the prepreg is eliminated when heating and pressurizing with a hot plate press and is cured as it is, so that a multilayered plate having a flat surface state is finally obtained. The obtained multilayer printed wiring board is finally cured, for example, at about 130 to 200 ° C. for about 30 to 120 minutes.
Also, in the case of the form (b) using a copper foil, the resin contained in the prepreg is remelted by heating and pressurizing and adheres strongly to the copper foil as in the case of the inner layer circuit.

  As the inner layer substrate used in the above process, for example, a plastic substrate, a ceramic substrate, a metal substrate, a film substrate or the like can be used. Specifically, a glass epoxy substrate, a glass polyimide substrate, an alumina substrate, a low-temperature fired ceramic substrate An aluminum nitride substrate, an aluminum substrate, a polyimide film substrate, or the like can be used. The inner layer circuit (wiring pattern) is preferably copper, and the copper circuit is preferably subjected to chemical surface treatment. On a circuit subjected to physical polishing such as buff polishing, the prepreg of the present invention is not preferable because it has poor adhesion and tends to swell due to solder heat. As a suitable chemical treatment, a general-purpose blackening treatment or a treatment of forming a roughened surface by etching copper with a chemical, for example, Mec etch bond, Atotech bond film, McDermitt multi-bond, and the like are preferable.

In addition, the conductor plating is not particularly limited, such as electrolytic plating and / or electroless plating of copper, tin, solder, nickel and the like, and a plurality of them can be used in combination. It is also possible to substitute metal sputtering instead of plating.
As the copper foil, it is preferable to use commercially available electrolytic copper foils such as JTC, JTC-AM, JTC-FM manufactured by Japan Energy, and GTS, GTS-MP, F3-WS manufactured by Furukawa Circuit Foil. More preferably, a copper foil having one surface or both surfaces roughened in advance is good, and the surface is further treated with various metal platings, or treated with a known and commonly used coupling agent or organic chelating agent. Is preferred.

Further, as a drilling method, any of a method of drilling with a semiconductor laser such as a CO ₂ laser or a UV-YAG laser or a drill is possible. Holes are through holes (through holes) for the purpose of conducting the front and back of the board, partial holes (belly vias) for the purpose of conducting the inner layer circuit and the prepreg surface circuit, conformal vias, etc. Can be formed according to the desired design.
After drilling, if the desmear treatment is performed to remove the residue (smear) existing on the inner wall or bottom of the hole and to develop the anchor effect between the conductor (metal plating formed later), the surface Are formed simultaneously with a commercially available desmear liquid (roughening agent). This step can also be performed by a dry process such as plasma.

  As a circuit formation method for the conductor layer (metal plating or copper foil), a conventionally known method such as a panel plating method, an additive method, or a semi-additive method can be adopted according to the production form of the multilayer printed wiring board, and each process is repeated. Conventionally known methods such as multilayering can be adopted, and the method is not limited to a specific method. Since the manufacturing form of such a multilayer printed wiring board is well known to those skilled in the art, the detailed description thereof is omitted.

Next, each component of the thermosetting resin composition used for manufacture of the prepreg for printed wiring boards which concerns on this invention is demonstrated.
First, the polyimide resin (A) used in the present invention may be a polyimide resin having a carboxyl group or an acid anhydride group and a linear hydrocarbon structure having a number average molecular weight of 300 to 6,000. Since it is excellent in solubility and heat resistance in aprotic polar organic solvents such as general-purpose solvents such as ketone solvents, ester solvents and ether solvents, carboxyl groups or acid anhydride groups, and number average molecular weights of 700 to 4, A polyimide resin (A1) having 500 linear hydrocarbon structures, a urethane bond, an imide ring, and an isocyanurate ring, and more preferably having a cyclic aliphatic structure is preferable. The linear hydrocarbon structure is particularly preferably a linear hydrocarbon structure having a number average molecular weight of 800 to 4,200 because a polyimide resin having a good balance between flexibility and dielectric properties of the cured product can be obtained. .

Examples of the polyimide resin (A1) include a structural unit represented by the following general formula (1) and a structural unit represented by the following general formula (2), and the following general formulas (3) and (4). And a polyimide resin (A2) having any one or more of the terminal structures represented by (5). Among them, the acid value is 20 to 150 mgKOH / g, and the number average molecular weight is 700 to 4,500. The linear hydrocarbon structure has a content of 20 to 40% by mass, an isocyanurate ring concentration of 0.3 to 1.2 mmol / g, a number average molecular weight of 2,000 to 30,000, and a weight. A polyimide resin having an average molecular weight of 3,000 to 100,000 is more preferable.

In the present invention, the acid value, the isocyanurate ring concentration, the number average molecular weight, and the weight average molecular weight of the polyimide resin (A) are measured by the following methods.
(1) Acid value: Measured according to JIS K-5601-2-1. As a dilution solvent for the sample, a mixed solvent of acetone / water (9/1 volume ratio) with an acid value of 0 is used so that the acid value of the acid anhydride can also be measured.
(2) Concentration of isocyanurate ring: ¹³ C-NMR analysis [solvent: deuterated dimethyl sulfoxide (DMSO-d ₆ )] was performed, and a calibration curve was obtained from the spectral intensity of carbon atoms caused by the isocyanurate ring at 149 ppm. The isocyanurate ring concentration per milligram of polyimide resin (A) is determined. In addition, the concentration of the imide ring can be similarly determined from the spectral intensity of the carbon atom caused by the imide ring at 169 ppm by ¹³ C-NMR analysis.
(3) Number average molecular weight and weight average molecular weight: The number average molecular weight and weight average molecular weight in terms of polystyrene are determined by gel permeation chromatography (GPC).

In addition, when the content rate of the linear hydrocarbon structure in a polyimide resin (A) is a polyimide resin manufactured with the manufacturing method which a polyimide resin (A) mentions later, the use mass of the polyol compound (a2) in a synthetic raw material The number average molecular weight of the linear hydrocarbon structure can be determined from the number average molecular weight of the polyol compound (a2).
In addition, the content and number average molecular weight of the linear hydrocarbon structure in the polyimide resin whose manufacturing method is unknown are obtained by heat-treating the polyimide resin in the usual hydrolysis method, for example, in the presence of an organic amine, to decompose the urethane bond, By separating the linear hydrocarbon structure part from the polyimide resin and utilizing the fact that the linear hydrocarbon structure part is less polar than the imide structure part, the linear hydrocarbon structure is obtained with a low polarity organic solvent such as dichloromethane. It can be obtained by extracting a portion and measuring the amount of extraction and GPC analysis.

  Although the manufacturing method of the said polyimide resin used for the thermosetting resin composition of this invention is not specifically limited, It is a polyol compound which has a polyisocyanate compound (a1) and a linear hydrocarbon structure, Comprising: Linear hydrocarbon structure part The polyanhydric acid anhydride having three or more carboxyl groups is converted to a prepolymer (A1) having an isocyanate group at the terminal obtained by reacting with a polyol compound (a2) having a number average molecular weight of 300 to 6,000. A method of reacting the product (b) with an organic solvent is preferred.

  For example, in order to produce a polyimide resin (A) by the above production method, a polyisocyanate having an isocyanurate ring derived from a diisocyanate having a cyclic aliphatic structure having 6 to 13 carbon atoms, and a linear hydrocarbon A prepolymer having an isocyanate group at the terminal obtained by reacting a polyol compound having a structure with a polyol compound having a linear hydrocarbon structure portion having a number average molecular weight of 700 to 4,500 is converted to an acid anhydride of a tricarboxylic acid. The product may be reacted in an organic solvent.

  The polyisocyanate compound (a1) used in the production method is a compound having two or more isocyanate groups in the molecule, and examples thereof include aromatic polyisocyanates and aliphatic polyisocyanates (including cyclic aliphatic polyisocyanates); These polyisocyanate nurate bodies, burette bodies, adduct bodies, allophanate bodies, and the like can be mentioned.

  Examples of the aromatic polyisocyanate compound include p-phenylene diisocyanate, m-phenylene diisocyanate, p-xylene diisocyanate, m-xylene diisocyanate, 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, 4,4. '-Diphenylmethane diisocyanate, polymethylene polyphenyl polyisocyanate (crude MDI), polymethylene polyphenyl isocyanate, 3,3'-dimethyldiphenyl-4,4'-diisocyanate, 3,3'-diethyldiphenyl-4,4'- Diisocyanate, m-xylene diisocyanate, p-xylene diisocyanate, 1,3-bis (α, α-dimethylisocyanatomethyl) benzene, tetramethylxylylene diisocyanate, di Eniren'eteru-4,4'-diisocyanate, naphthalene diisocyanate, and the like.

  Examples of the aliphatic polyisocyanate compound include hexamethylene diisocyanate (HDI), lysine diisocyanate, trimethylhexamethylenemethylene diisocyanate, isophorone diisocyanate (IPDI), 4,4′-dicyclohexylmethane diisocyanate, hydrogenated xylene diisocyanate (HXDI), Examples include norbornylene diisocyanate (NBDI).

  As the polyisocyanate compound (a1), a polyimide resin having good solubility in an organic solvent, compatibility with an epoxy resin or an organic solvent, and a low dielectric constant and dielectric loss tangent of a cured product can be obtained. Group polyisocyanates are preferred. Further, isocyanurate type polyisocyanate is preferable because a cured product having a cured product having good heat resistance can be obtained.

  Furthermore, the polyisocyanate compound (a1) is a polyimide having good solubility in organic solvents, good compatibility with epoxy resins and organic solvents, low dielectric constant and dielectric loss tangent of cured products, and good heat resistance. Since the resin is obtained, the polyisocyanate compound (a11) having an isocyanurate ring derived from an aliphatic polyisocyanate is more preferable, and the polyisocyanate compound having an isocyanurate ring derived from a cyclic aliphatic polyisocyanate is further included. preferable. Examples of the polyisocyanate compound having an isocyanurate ring derived from the cycloaliphatic polyisocyanate include those having a cyclic aliphatic structure of 2 to 3 moles per mole of the isocyanurate ring. What has a cycloaliphatic structure 2.5-3 mol times is more preferable.

  As the polyisocyanate compound (a11), for example, one or two or more aliphatic diisocyanate compounds are isocyanurated in the presence or absence of an isocyanuration catalyst such as a quaternary ammonium salt. And those composed of a mixture of isocyanurates such as trimer, pentamer, and heptamer. Specific examples of the polyisocyanate compound (a11) include isophorone diisocyanate isocyanurate type polyisocyanate (IPDI3N), hexamethylene diisocyanate isocyanurate type polyisocyanate (HDI3N), hydrogenated xylene diisocyanate isocyanurate type polyisocyanate (HXDI3N). ), Isocyanurate type polyisocyanate of norbornane diisocyanate (NBDI3N), and the like.

  The polyisocyanate compound (a11) is a trimeric isocyanurate in 100 parts by mass of the polyisocyanate compound (a1) because a polyimide resin having good solubility in organic solvents and heat resistance of a cured product can be obtained. Is preferably 30 parts by mass or more, particularly preferably 50 parts by mass or more.

  Moreover, as said polyisocyanate compound (a11), since the content rate of an isocyanate group is 10-30 mass%, since the solubility to an organic solvent and the heat resistance of hardened | cured material are favorable, the polyimide resin is obtained. More preferred. Accordingly, the polyisocyanate compound (a11) is most preferably a polyisocyanate compound having an isocyanurate ring derived from a cycloaliphatic polyisocyanate having an isocyanate group content of 10 to 30% by mass. preferable.

  The polyisocyanate having an isocyanurate ring may be used in combination with other polyisocyanates, but isocyanurate type polyisocyanates are preferably used alone.

  It is essential that the polyol compound (a2) used in the production method is a polyol compound having a linear hydrocarbon structure portion having a number average molecular weight of 300 to 6,000, and in particular, solubility in an organic solvent, A linear hydrocarbon structure part is obtained because it has a good compatibility with epoxy resins and organic solvents, a low dielectric constant and dielectric loss tangent of the cured product, a high glass transition point Tg, and excellent film-forming properties. A polyol compound having a number average molecular weight of 700 to 4,500 is preferred, and a polyol compound having a linear hydrocarbon structure portion having a number average molecular weight of 800 to 4,200 is particularly preferred. A polyol compound having a linear hydrocarbon structure portion with a number average molecular weight of less than 300 is not preferable because the cured product has a high dielectric constant and dielectric loss tangent, while the linear hydrocarbon structure portion has a number average molecular weight of 6,000. A polyol compound exceeding the above is not preferable because the solubility in an organic solvent, the compatibility with an epoxy resin or an organic solvent, and the mechanical properties are poor.

  Examples of the polyol compound (a2) include compounds having an average of 1.5 or more hydroxyl groups bonded to the terminal and / or side chain of the linear hydrocarbon structure in total per molecule. The linear hydrocarbon structure may be linear or branched. The linear hydrocarbon structure may be a saturated hydrocarbon chain or an unsaturated hydrocarbon chain, but a saturated hydrocarbon chain is more preferable from the viewpoint of changes in physical properties and stability during heating.

  Examples of the polyol compound (a2) include polyol compounds having a polyolefin structure or a polydiene structure, wherein the polyol compound having a polyolefin structure or a polydiene structure has a number average molecular weight of 300 to 6,000 and hydrogenated products thereof. It is done. Examples of the olefin include ethylene, propylene, butene, isobutylene, pentene, and methylpentene. Examples of the diene include pentadiene, hexadiene, isoprene, butadiene, propadiene, and dimethylbutadiene.

  Specific examples of the polyol compound (a2) include polyethylene polyol, polypropylene polyol, polybutadiene polyol, hydrogenated polybutadiene polyol, polyisoprene polyol, hydrogenated polyisoprene polyol, etc., and the number of linear hydrocarbon structure portions. Examples include polyol compounds having an average molecular weight of 300 to 6,000. These may be used alone or in combination of two or more.

  The number of hydroxyl groups in the polyol compound (a2) is preferably 1.5 to 3 on average because it is difficult to gel, a molecular growth is good, and a polyimide resin having excellent flexibility is obtained. Further, the number of hydroxyl groups is particularly preferably an average of 1.8 to 2.2.

  As a commercial item of the said polyol compound (a2), liquid polybutadiene which has a hydroxyl group in both ends, such as NISSO PB (G series) by Nippon Soda Co., Ltd., Poly-bd by Idemitsu Petrochemical Co., Ltd .; Hydrogenated polybutadiene having hydroxyl groups at both ends, such as NISSO PB (GI series) manufactured by Nippon Soda Co., Ltd., polytail H manufactured by Mitsubishi Chemical Corporation, polytail HA, etc .; Poly-iP manufactured by Idemitsu Petrochemical Co., Ltd. Liquid C5 polymer having hydroxyl groups at both ends; hydrogenation having hydroxyl groups at both ends, such as Epol from Idemitsu Petrochemical Co., Ltd., TH-1, TH-2, TH-3 from Kuraray Co., Ltd. Examples include polyisoprene.

  Furthermore, as the polyol compound (a2), ester-modified polyol compounds and urethane-modified polyol compounds obtained by reacting various polybasic acids and polyisocyanates with polyol compounds having a linear hydrocarbon structure as described above can also be used. It is.

  The polyol compound (a2) is preferably a polybutadiene polyol and / or a hydrogenated polybutadiene polyol, and more preferably a hydrogenated polybutadiene polyol.

  In the polyimide resin obtained by the production method, the linear hydrocarbon structure derived from the polyol compound (2a) is introduced between rigid skeletons having imide bonds. In order for the polyimide resin obtained by the manufacturing method to have particularly excellent heat resistance, the glass transition point needs to be high, and therefore the polyol compound (a2) used as a raw material also has a high glass transition point. As a result of intensive studies, the glass transition point of the cured product has a lower glass transition point of the polyol compound (a2) introduced into the molecule of the polyimide resin. It became clear that the hardened | cured material which is more excellent in a mechanical physical property can be obtained by using a polyol compound with a high point and a low glass transition point. From the above knowledge, the glass transition point of the polyol compound (a2) is preferably −120 to 0 ° C.

  In the above production method, the polyol compound (a2) may be used in combination with another hydroxyl group-containing compound to the extent that the effects of the present invention are not impaired. In this case, the other hydroxyl group-containing compound is desirably used at 50% by mass or less based on the total hydroxyl group-containing compound.

  Examples of the acid anhydride (b) of a polycarboxylic acid having three or more carboxyl groups used in the present invention include tricarboxylic acid anhydrides and tetracarboxylic acid anhydrides.

Examples of the acid anhydride of tricarboxylic acid include trimellitic anhydride and naphthalene-1,2,4-tricarboxylic acid anhydride.
Examples of the acid anhydride of tetracarboxylic acid include pyromellitic dianhydride, benzophenone-3,4,3 ′, 4′-tetracarboxylic dianhydride, diphenyl ether-3,4,3 ′, 4′-. Tetracarboxylic dianhydride, benzene-1,2,3,4-tetracarboxylic dianhydride, biphenyl-3,4,3 ', 4'-tetracarboxylic dianhydride, biphenyl-2,3,2 ', 3'-tetracarboxylic dianhydride, naphthalene-2,3,6,7-tetracarboxylic dianhydride, naphthalene-1,2,4,5-tetracarboxylic dianhydride, naphthalene-1, 8,4,5-tetracarboxylic dianhydride, decahydronaphthalene-1,8,4,5-tetracarboxylic dianhydride, 4,8-dimethyl-1,2,3,5,6,7- Hexahydronaphthalene-1,2,5 6-tetracarboxylic dianhydride, 2,6-dichloronaphthalene-1,8,4,5-tetracarboxylic dianhydride, 2,7-dichloronaphthalene-1,8,4,5-tetracarboxylic acid Anhydride, 2,3,6,7-tetrachloronaphthalene-1,8,4,5-tetracarboxylic dianhydride, phenanthrene-1,2,9,10-tetracarboxylic dianhydride, berylene-3 , 4,9,10-tetracarboxylic dianhydride, bis (2,3-dicarboxyphenyl) methane dianhydride, bis (3,4-dicarboxyphenyl) methane dianhydride, 1,1-bis ( 2,3-dicarboxyphenyl) ethane dianhydride, 1,1-bis (3,4-dicarboxyphenyl) ethane dianhydride, 2,2-bis (2,3-dicarboxyphenyl) propane dianhydride 2,3-bis 3,4-dicarboxyphenyl) propane dianhydride, bis (3,4-dicarboxyphenyl) sulfone dianhydride, bis (3,4-dicarboxyphenyl) ether dianhydride And tetracarboxylic anhydride having a group. One or more of these can be used. Further, a tricarboxylic acid anhydride and a tetracarboxylic acid anhydride may be mixed and used.

  As the acid value of the polyimide resin obtained by the above production method, in order to improve the solubility in an organic solvent and the cured material properties, and further to improve the fluidity as the prepreg of the present invention, in terms of solids 20-150 mgKOH / g is preferable and 20-120 mgKOH / g is more preferable. When the acid value of the polyimide resin is less than 20 mgKOH / g, the crosslinking density is low and the solder heat resistance is inferior. On the other hand, when the acid value is larger than 150 mgKOH / g, the softening temperature and fluidity of the resin become too high, the followability to the inner layer circuit is deteriorated, and the molding is poor, which is not preferable. The molecular weight of the polyimide resin is preferably a number average molecular weight of 2,000 to 30,000 and a weight average molecular weight of 3,000 to 100,000 in order to improve solvent solubility. More preferably, the number average molecular weight is 2,000 to 10,000 and the weight average molecular weight is 3,000 to 50,000.

  The organic solvent used in the method for producing the polyimide resin may be reacted after it has been present in the system in advance, or it may be introduced in the middle. The prepolymer (a1) having a group and a polycarboxylic acid anhydride (b) having 3 or more carboxyl groups are preferably present at the start of the reaction. In order to maintain an appropriate reaction rate during this reaction, the proportion of the organic solvent in the system is preferably 80% by mass or less, more preferably 10 to 70% by mass of the reaction system. As the organic solvent, since a compound containing an isocyanate group is used as a raw material component, an aprotic polar solvent having no active proton such as a hydroxyl group or an amino group is preferable.

Next, among the essential components of the thermosetting resin composition used for the preparation of the prepreg of the present invention, the epoxy resin (B) has various physical properties such as sufficient heat resistance, chemical resistance and electrical properties as an interlayer insulating material. It is necessary to get.
As the epoxy resin (B), bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol S type epoxy resin, phenol novolac type epoxy resin, alkylphenol novolac type epoxy resin, biphenol type epoxy resin, naphthalene type epoxy resin, dicyclo Pentadiene type epoxy resins, epoxidized products of condensates of phenols and aromatic aldehydes having phenolic hydroxyl groups, or bromine atom-containing epoxy resins, phosphorus atom-containing epoxy resins, triglycidyl isocyanurate, alicyclic epoxy resins, etc. Well-known and conventional ones can be used alone or in combination of two or more. Moreover, you may contain the monofunctional epoxy resin as a reactive diluent.

  In particular, in the thermosetting resin composition used for preparing the prepreg of the present invention, it is preferable to arbitrarily mix an epoxy resin having an epoxy equivalent of 200 or more and an epoxy resin having an epoxy equivalent of 200 or less. An epoxy resin having an epoxy equivalent of 200 or more has little cure shrinkage, and gives warpage prevention of the base material and flexibility of the cured product. Moreover, the melt viscosity at the time of heating and pressurization can be increased, which is effective for controlling the amount of resin oozing after molding. On the other hand, an epoxy resin having an epoxy equivalent of 200 or less has high reactivity and gives mechanical strength to the cured product. Moreover, since the melt viscosity at the time of heating and pressing is low, it contributes to the filling property of the resin composition in the gaps between the inner layer circuits and the followability to the rough surface of the copper foil.

  Examples of the organic solvent used to dissolve the above-described components and other components include ordinary solvents such as ketones such as acetone, methyl ethyl ketone, and cyclohexanone, ethyl acetate, butyl acetate, cellosolve acetate, propylene glycol monomethyl ether acetate, Acetic esters such as carbitol acetate, cellosolves such as cellosolve and butylcellosolve, carbitols such as carbitol and butylcarbitol, aromatic hydrocarbons such as toluene and xylene, dimethylformamide, dimethylacetamide, N-methyl Pyrrolidone etc. can be used individually or in combination of 2 or more types. Note that the prepreg of the present invention contains voids after curing even in the presence of residual organic solvent (specified by the weight loss rate before and after drying when dried in a dryer maintained at 200 ° C. for 30 minutes). There is no problem as long as the characteristics of the printed circuit board, such as occurrence, are not impaired. Generally, it is preferable that it is 15 mass% or less of the whole composition.

  The thermosetting resin composition used for the preparation of the prepreg of the present invention can further contain an epoxy resin curing agent as required. Epoxy resin curing agents include tertiary amine compounds, imidazole compounds, guanidines, or epoxy adducts and microencapsulated organic phosphine compounds such as triphenylphosphine, tetraphenylphosphonium, and tetraphenylborate. , DBU or its derivatives can be used alone or in combination of two or more.

  Among these epoxy resin curing agents, the imidazole compound has a slow reaction in the temperature range (80 ° C. to 130 ° C.) when drying the solvent in the composition, and the temperature range during curing (150 ° C. to 200 ° C.). Then, it is preferable in that the reaction can proceed sufficiently and the physical properties of the cured product are sufficiently expressed. Moreover, an imidazole compound is preferable also at the point which is excellent in adhesiveness with a copper circuit and copper foil. Particularly preferable examples include 2-ethyl-4-methylimidazole, 2-methylimidazole, 2-phenylimidazole, 2-phenyl-4-methylimidazole, and bis (2-ethyl-4-methyl-imidazole). 2-phenyl-4-methyl-5-hydroxymethylimidazole, 2-phenyl-4,5-dihydroxymethylimidazole, or triazine addition type imidazole.

  These epoxy resin curing agents are preferably blended in the range of 0.05 to 20 parts by mass with respect to 100 parts by mass of the total amount of the epoxy resin (B). If the blending amount is less than 0.05 parts by mass, curing will be insufficient. On the other hand, if the blending amount exceeds 20 parts by mass, the effect of promoting the curing will not be increased, but there will be a problem that the heat resistance and mechanical strength are impaired.

The thermosetting resin composition used for preparing the prepreg of the present invention can be blended with a compound (C) having two or more phenolic hydroxyl groups for the purpose of further improving the mechanical strength and heat resistance of the cured product.
Examples of the compound (C) having two or more phenolic hydroxyl groups include phenol novolac resins, alkylphenol volac resins, bisphenol A novolac resins, dicyclopentadiene type phenol resins, Xylok type phenol resins, terpene modified phenol resins, polyvinylphenols, etc. A well-known and usual phenol resin can be used individually or in combination of 2 or more types.
The phenol resin is desirably blended at a ratio of 0 to 1.2 equivalents of the phenolic hydroxyl group with respect to 1 epoxy equivalent of the epoxy resin (B). Outside this range, the heat resistance of the obtained prepreg is impaired, which is not preferable.

The thermosetting resin composition used for preparing the prepreg of the present invention can further contain a thermoplastic resin as necessary.
As thermoplastic resins, polyesters, polyamides, polyethers, polyimides, polysulfides, polysulfones, polyacetals, butyral resins, NBR, phenoxy resins, polybutadienes, various engineering plastics, etc. can be used alone or in combination of two or more. Can be used.
These thermoplastic resins may be uniformly dispersed or dissolved in the resin composition at room temperature regardless of whether the epoxy resin in the resin composition is cured and then uniformly dispersed or phase-separated. preferable. These thermoplastic resins contribute to the prevention of repelling during coating and the improvement of transferability, and are effective in increasing the thickness of the coating. Effective for preventing warping. Furthermore, the melt viscosity at the time of heating and pressurization can be increased, which is effective for controlling the amount of resin oozing after molding.
The thermoplastic resin is preferably blended at a ratio of 100 parts by mass or less with respect to 100 parts by mass of the epoxy resin (B). If an amount exceeding 100 parts by mass is blended, the melt viscosity of the resin may become too high during heating and pressurization, or separation may occur in the state of the composition.

  The thermosetting resin composition used for the preparation of the prepreg of the present invention can be blended with an inorganic filler for the purpose of further improving properties such as adhesion of the cured product, mechanical strength, and linear expansion coefficient. For example, known and commonly used inorganic fillers such as barium sulfate, barium titanate, silicon oxide powder, finely divided silicon oxide, amorphous silica, talc, clay, magnesium carbonate, calcium carbonate, aluminum oxide, aluminum hydroxide, mica powder, etc. Can be used. The blending ratio is suitably 0 to 90% by mass of the resin composition.

  Further, the thermosetting resin composition used for the preparation of the prepreg of the present invention may further include phthalocyanine blue, phthalocyanine green, iodin green, disazo yellow, crystal violet, titanium oxide, carbon black, naphthalene black, etc. Known and commonly used colorants, known and commonly used thickeners such as asbestos, olben, benton and fine silica, defoamers and / or leveling agents such as silicones, fluorines and polymers, thiazoles and triazoles Adhesiveness-imparting agents such as silane coupling agents, titanate-based and aluminum-based commonly used additives can be blended.

  Examples of the synthesis of imide resins used in the present invention, examples using them, comparative examples and test examples will be described in detail below, but the present invention is not limited to the following examples. Of course. In the following, “parts” and “%” are based on mass unless otherwise specified.

Synthesis example 1
In a 20 liter flask equipped with a stirrer, a thermometer, and a condenser, 4951 parts of diethylene glycol monoethyl ether acetate (hereinafter abbreviated as EDGA) and a polyisocyanate having an isocyanurate ring derived from isophorone diisocyanate (hereinafter, referred to as EDGA) IPDI-N is abbreviated as IPDI-N, has an isocyanate group content of 18.2%, an isocyanurate ring-containing triisocyanate content of 85%, 2760 parts (12 moles as an isocyanate group), and polytail HA (both ends manufactured by Mitsubishi Chemical Corporation). Was charged with hydrogenated liquid polybutadiene having a hydroxyl group, number average molecular weight 2,100, hydroxyl value 51.2 mgKOH / g] 2191 parts (2 moles as a hydroxyl group), and heated to 80 ° C. while taking care of heat generation while stirring. After 3 hours reaction Subsequently, 1536 parts of EDGA and 1536 parts (8 mol) of trimellitic anhydride (hereinafter abbreviated as TMA) were charged, and the temperature was raised to 160 ° C., followed by reaction for 4 hours. The reaction proceeded with foaming. The system became a light brown clear liquid, and a polyimide resin solution was obtained.
The obtained polyimide resin solution was coated on a KBr plate, and the infrared absorption spectrum of the sample in which the solvent was volatilized was measured. As a result, 2270 cm ^−1, which is the characteristic absorption of the isocyanate group, disappeared completely, and 725 cm ⁻¹ and 1780 cm ⁻ absorption of the imide ring ¹ and 1720 cm ^-1, characteristic absorption of isocyanurate ring at 1690 cm ^-1 and 1460 cm ^-1, characteristic absorption of the urethane bond at 1550 cm ^-1. The acid value of the polyimide resin is 79 mgKOH / g in terms of solid content, the concentration of the isocyanurate ring is 0.66 mmol / g (in terms of resin solid content), and the number average molecular weight (hereinafter abbreviated as Mn) is 5. The weight average molecular weight (hereinafter abbreviated as Mw) was 24,000. Hereinafter, this polyimide resin solution is abbreviated as (X-1).

Synthesis example 2
Polyisocyanate having an isocyanurate ring derived from 1,6-hexanediisocyanate in 4300 parts of EDGA, 2070 parts of IPDI-N (9 mol as isocyanate group), in a 20-liter flask equipped with a stirrer, a thermometer and a condenser (Isocyanate group content 22.9%, isocyanurate ring-containing triisocyanate content 63.3%) 550 parts (3 moles as isocyanate groups) were charged and mixed to make uniform, then 2191 parts of polytail HA (as hydroxyl groups) 2 mol) was added and the temperature was raised to 80 ° C. while paying attention to heat generation while stirring, and the reaction was carried out for 3 hours. Next, 1536 parts (8 mol) of TMA was charged, and the temperature was raised to 160 ° C., followed by reaction for 4 hours. The reaction at this time proceeded with foaming, and when the viscosity increased and the system became difficult to stir, 2000 parts of EDGA was further added. The system became a light brown clear liquid, and a polyimide resin solution was obtained.
As a result of measuring the infrared absorption spectrum in the same manner as in Example 1 using the obtained polyimide resin solution, 2270 cm ^−1, which is the characteristic absorption of the isocyanate group, disappeared completely, and 725 cm ⁻¹ , 1780 cm ⁻¹ and 1720 cm ^−1. absorption of an imide ring, characteristic absorption of isocyanurate ring at 1690 cm ^-1 and 1460 cm ^-1, characteristic absorption of the urethane bond to 1550 cm ^-1 was confirmed on. Furthermore, the acid value of the polyimide resin was 85 mgKOH / g in terms of solid content, the concentration of the isocyanurate ring was 0.68 mmol / g, Mn was 5,500, and Mw was 22,000. Hereinafter, this polyimide resin solution is abbreviated as (X-2).

Synthesis example 3
Polyisocyanate having an isocyanurate ring derived from norbornylene diisocyanate in 5310 parts of EDGA, 1380 parts of IPDI-N (6 mol as isocyanate group), in a 20-liter flask equipped with a stirrer, a thermometer and a condenser (Isocyanate group content: 18.75%, isocyanurate ring-containing triisocyanate content: 65.5%) 1344 parts (6 moles as isocyanate groups) were charged and dissolved by heating at 80 ° C., and polytail HA 2191 parts (hydroxyl groups 2 moles) Was added, and the reaction was carried out at 80 ° C. for 5 hours while stirring. Then, 1536 parts (8 mol) of TMA was added, and the temperature was raised to 170 ° C., followed by reaction for 4 hours. The reaction proceeded with foaming. The inside of the system became a light brown clear liquid, and a polyimide resin solution was obtained.
As a result of measuring the infrared absorption spectrum in the same manner as in Example 1 using the obtained polyimide resin solution, 2270 cm ^−1, which is the characteristic absorption of the isocyanate group, disappeared completely, and 725 cm ⁻¹ , 1780 cm ⁻¹ and 1720 cm ^−1. absorption of imide ring, characteristic absorption of isocyanurate ring at 1690 cm ^-1 and 1460 cm ^-1, characteristic absorption of the urethane bond to 1550 cm ^-1 was confirmed on. The acid value of the polyimide resin was 75 mgKOH / g in terms of solid content, the concentration of the isocyanurate ring was 0.72 mmol / g, Mn was 4,400, and Mw was 21,000. Hereinafter, this polyimide resin solution is abbreviated as (X-3).

Examples 1 to 10 and Comparative Examples 1 and 2
To the blending components shown in Table 1, propylene glycol monomethyl ether acetate as an organic solvent and Aerosil # 972, which is fine silica, are added and kneaded and dispersed in a three-roll mill, and the viscosity is 40 dPa · s ± 10 dPa · s (rotation) A thermosetting resin composition adjusted to a viscometer of 5 rpm at 25 ° C. was obtained. Next, the obtained thermosetting resin composition was further adjusted to a viscosity of 1 to 2 dPa · s using methyl ethyl ketone to prepare a prepreg varnish.
Each of the obtained prepreg varnishes was applied to Asahi Shovel's 1080 glass cloth (glass fiber diameter: about 5 μm, glass fiber density: vertical × horizontal 60 × 47 / inch) using a prepreg coater, It dried at 40-120 degreeC and obtained the prepreg. (Solid content: about 50%: Gelation time is within a range of 80 to 100 seconds at 170 ° C.)

Test example 1
Next, the prepregs produced in Examples 1 to 10 and Comparative Examples 1 and 2 were directly sandwiched between heat-resistant silicon sheets and cured at 120 ° C. for 20 minutes and further at 170 ° C. for 2 hours to obtain a cured film. Table 2 shows the properties of the obtained cured film.

Test Example 2 (form [1])
The prepregs produced in Examples 1 to 10 and Comparative Examples 1 and 2 were formed on both sides of a substrate on which an inner layer circuit was formed from a glass-epoxy double-sided copper-clad laminate having a copper foil thickness of 18 μm and further subjected to a Mec etch bond treatment. Using a hot plate press through a heat-resistant silicon sheet on the opposite resin surface, 5 kgf / cm ² , 120 ° C., 20 minutes, then 25 kgf / cm ² , 170 ° C., 2 After curing under time conditions, the heat-resistant silicon sheet was removed, and a laminate having flat resin layers on both sides was produced.
Further, a predetermined through-hole portion, via-hole portion, and the like of this laminated plate were drilled with a drill and a laser, and then desmear treatment and surface irregularity formation were performed using a known and common chemical. Next, after the entire surface and the hole are made conductive by electroless copper plating and electrolytic copper plating, heat treatment is performed at 170 ° C. for 30 minutes for the purpose of moisture removal and copper plating annealing, and then through a commercially available etching resist. A pattern was formed by etching to produce a multilayer printed wiring board.
The multilayer printed wiring board thus produced was tested and evaluated for the following physical properties and characteristics. The results are shown in Table 3.

上記表２、表３及び後述する表４中の各物性及び特性は、以下のようにして測定・評価した。

The physical properties and characteristics in Tables 2 and 3 and Table 4 described later were measured and evaluated as follows.

(A) Glass transition temperature Tg:
It was measured by TMA (thermomechanical analysis).
(B) CTEα1 (linear expansion coefficient equal to or less than Tg):
Measured by TMA.
(C) Dielectric constant Dk and dielectric loss tangent Df:
It measured according to JIS K6911.
(D) Water absorption rate The cured film was immersed in distilled water controlled at 23 ° C. ± 2 ° C., and obtained from the mass change after 24 hours.
(E) Peel strength:
It measured according to JIS C6481.
(F) Solder heat resistance:
The completed printed wiring board (10 cm × 10 cm) is immersed in a solder layer at 288 ° C. ± 3 ° C. for 10 seconds. After repeating this operation five times, peeling of the copper foil was confirmed. In addition, the meaning of the code | symbol in Table 3 is as follows.
OK: No peeling NG: Peeling (g) Pattern formability:
Line and space The peeling of the 75 μm / 75 μm circuit was visually inspected. In addition, the meaning of the code | symbol in Table 3 is as follows.
OK: no peeling NG: peeling (h) flame retardancy:
An insulating layer was formed on both sides of a 0.4 mm thick FR-4 base material with a cured coating film to a thickness of 80 μm, and the test was conducted according to UL-94. In addition, the meaning of the code | symbol in Table 3 is as follows.
NG: The flame of the sample piece reaches the clamp, and is UL-94 V0 non-conformity.

Test example 3
The characteristics of the substrate produced by changing the panel pattern method to the semi-additive method in the production of the substrate in each of the above examples were almost the same as described above, and a circuit of line / space = 25 μm / 25 μm could be formed, and no peeling occurred. It was.

Test Example 4 (form [2])
The prepregs produced in Examples 1 to 3 and 7 to 10 and Comparative Examples 1 and 2 were formed by forming an inner layer circuit from a glass-epoxy double-sided copper-clad laminate having a copper foil thickness of 18 μm, and further subjected to MEC etch bond processing. Using a hot plate press through copper foil (F3-WS: Furukawa Circuit Foil) on the opposite resin surface so that the resin surface adheres to both sides of the substrate, 5 kgf / cm ² , 120 ° C., 20 minutes Then, it was cured under the conditions of 25 kgf / cm ² and 170 ° C. for 2 hours to produce a laminate.
Furthermore, a predetermined through hole portion of this laminated board is drilled with a drill, and the laser via portion is first provided with a guide by selectively removing the copper foil using an etching resist at the hole position, and a laser processing machine is used to provide a hole. Dawned. Next, after processing the smear of the through-hole part and the laser via part with a commercially available desmear solution, the holes are made conductive by electroless copper plating and electrolytic copper plating, and a pattern is formed by etching through a commercially available etching resist. A multilayer printed wiring board was produced.
The multilayer printed wiring board thus produced was tested and evaluated for the above physical properties and characteristics. The results are shown in Table 4.

Claims (6)

A fibrous base material having (A) a carboxyl group or an acid anhydride group and a polyimide resin having a linear hydrocarbon structure with a number average molecular weight of 300 to 6,000 and (B) an epoxy resin as essential components A prepreg for a printed wiring board, which is impregnated with a thermosetting resin composition to be in a semi-cured state. The polyimide resin (A) is a polyimide resin having a carboxyl group or an acid anhydride group, a linear hydrocarbon structure having a number average molecular weight of 700 to 4,500, a urethane bond, an imide ring, and an isocyanurate ring. The printed wiring board prepreg according to claim 1, wherein the printed wiring board is a prepreg. The polyimide resin (A) has a structural unit represented by the following general formula (1) and a structural unit represented by the following general formula (2), and the following general formulas (3), (4) and (5) The printed circuit board prepreg according to claim 1, wherein the prepreg is a polyimide resin having any one or more of the terminal structures represented by the formula:

The polyimide resin (A) is a polyimide resin having an acid value of 20 to 150 mgKOH / g, and the mass ratio (A) / (B) between the polyimide resin (A) and the epoxy resin (B) is 0.1. The prepreg for a printed wiring board according to any one of claims 1 to 3, wherein the prepreg is 10. The printed wiring board prepreg according to any one of claims 1 to 4, wherein the thermosetting resin composition further contains a compound (C) having two or more phenolic hydroxyl groups. A multilayer printed wiring board, wherein an interlayer insulating layer is formed using the prepreg for printed wiring board according to any one of claims 1 to 5.