JP4555985B2 - Prepreg, and metal foil-clad laminate and printed circuit board obtained using the same - Google Patents

Description

  The present invention relates to a prepreg, a metal foil-clad laminate and a printed circuit board obtained using the prepreg.

  The printed circuit board is usually composed of an insulating substrate and a printed circuit provided on the substrate. As the substrate, for example, a laminate (printed wiring board laminate) obtained by stacking a predetermined number of prepregs impregnated with an electrically insulating resin as a matrix on a fiber base material, and heating and pressing the prepregs is integrated. . When a printed circuit (printed circuit) is formed by a subtractive method to obtain a printed circuit board, a metal foil-clad laminate in which metal foil is laminated on one side or both sides of a substrate made of the above laminate is used. This metal foil-clad laminate is produced, for example, by stacking a metal foil such as a copper foil on the surface (one side or both sides) of a prepreg and heating and pressing it. As the electrically insulating resin, a thermosetting resin such as a phenol resin, an epoxy resin, a polyimide resin, or a bismaleimide-triazine resin is widely used, and a thermoplastic resin such as a fluororesin or a polyphenylene ether resin may be used.

  With the spread of information terminal devices such as personal computers and mobile phones, printed circuit boards mounted on them are becoming smaller and higher in density. The mounting form proceeds from a pin insertion type to a surface mounting type, and further to an area array type represented by a BGA (ball grid array) using a substrate such as a plastic substrate made of a laminate as described above. It is out. When a bare chip is directly mounted on a substrate like a BGA, the connection between the bare chip and the substrate is generally performed by wire bonding by thermosonic bonding. For this reason, the board | substrate which mounts a bare chip will be exposed to 150 degreeC or more high temperature, and a certain amount of heat resistance is requested | required of the electrically insulating resin used for a board | substrate.

  By the way, from the viewpoint of environmental problems, lead-free solder has been developed. However, when mounting using lead-free solder, the substrate is required to have higher heat resistance because its melting temperature is high. Moreover, the request | requirement which makes the material of a board | substrate halogen-free is also increasing, and use of a brominated flame retardant has become difficult.

  In addition, the printed circuit board may be required to have a so-called repair property that removes the chip once mounted, but in order to remove the chip, the same amount of heat is applied as when the chip is mounted, and the chip is mounted again. Heat will also be applied. Therefore, printed circuit boards that require repairability are also required to have durability (thermal shock resistance) against repeated high-temperature thermal shocks. If the thermal shock resistance is insufficient, peeling or the like tends to occur between the fiber base material and the resin when repaired.

Thus, for example, a prepreg in which a fiber base material is impregnated with a resin composition containing a polyamideimide resin having excellent thermal shock resistance and the like as an essential component and a substrate obtained using the prepreg have been proposed (for example, see Patent Document 1). ).
JP 2003-55486 A

  A conventional substrate made of a laminate as described above is said to be a so-called rigid substrate, and although it is excellent in terms of dimensional stability and the like, there is still room for improvement in terms of adhesive strength between the metal foil and the substrate and heat resistance. there were. In particular, when component mounting is performed using so-called lead-free solder that does not contain lead, it is difficult to obtain a substrate that is satisfactory in terms of solder heat resistance because the temperature required for the reflow process and the like is high.

  Therefore, the present invention provides a metal foil-clad laminate and a printed circuit board that can achieve both the adhesive strength and heat resistance between the metal foil and the substrate at a sufficiently high level at the same time, and a prepreg capable of obtaining them. For the purpose.

  In order to solve the above problems, the present invention is a prepreg obtained by removing a solvent from a varnish containing a solvent and a polyamide-imide resin dissolved in the solvent and impregnating the fiber base material, The solvent is a prepreg characterized by being a mixed solvent composed of a good solvent and a poor solvent for the polyamideimide resin.

  The prepreg of the present invention is obtained by removing a mixed solvent from a varnish using a mixed solvent composed of a good solvent and a poor solvent of a polyamideimide resin, whereby the adhesive strength and heat resistance between the metal foil and the substrate are obtained. It is possible to obtain metal foil-clad laminates and printed circuit boards that achieve both of the properties at a sufficiently high level simultaneously.

  The present inventors speculate that the improvement in heat resistance is caused by the fact that the amount of voids formed in the substrate is reduced by using the specific mixed solvent as described above. If a large number of voids are formed in the substrate, for example, when the substrate is heated to a high temperature exceeding 260 ° C. in a reflow process or the like, these voids expand and cause defects such as peeling of the metal foil. It is done.

  It is considered that the voids in the substrate are reduced, for example, because the viscosity of the varnish is greatly reduced by using a mixed solvent. Conventionally, in the production of a substrate using a resin composition containing a polyamide-imide resin, a varnish in which a polyamide-imide resin is dissolved in a solvent composed of the good solvent has been used. As a result of diligent investigation focusing on the solvent, the viscosity of the varnish is higher when a mixed solvent that is a combination of a good solvent and a poor solvent is used as a solvent for the varnish than when a solvent consisting of only the good solvent is used. It was found that it was greatly reduced. When the viscosity of the varnish decreases, the fiber base material is easily impregnated, and the non-impregnated portion is less likely to remain in the prepreg. By reducing the unimpregnated portion, it is considered that the amount of voids derived from the unimpregnated portion in the prepreg is reduced in the substrate. Furthermore, the poor solvent of the polyamide-imide resin often has a lower boiling point than that of the good solvent and can be easily removed from the varnish after impregnating the fiber base material. It is thought to decrease.

  On the other hand, the mechanism of the effect of improving adhesiveness is not necessarily clear, but, for example, in the process of removing the solvent from the varnish, because the polyamideimide resin precipitates while the ratio of the poor solvent and the good solvent changes, There is a possibility that the morphology of the polyamideimide resin in the prepreg is different from the case where only the good solvent is used as the varnish solvent. In general, the adhesion of the resin to other materials can change with changes in its morphology.

  In the present invention, the good solvent means a solvent in which the solubility of the polyamideimide resin used in the varnish (the amount of solute that can be dissolved in 100 g of the solvent) is 10 g or more at room temperature. A poor solvent means a solvent having a solubility of less than 10 g.

  The mixed solvent preferably contains 1 to 60% by mass of a poor solvent based on the total amount thereof. If the content ratio of the poor solvent is less than 1% by mass, the effect of improving the adhesiveness and heat resistance tends to be reduced. If the content exceeds 60% by mass, the solubility of the polyamideimide resin in the mixed solvent is reduced. The stability of the prepreg manufacturing process tends to decrease.

  The good solvent preferably contains at least one solvent selected from the group consisting of N-methyl-2-pyrrolidone, N, N-dimethylacetamide, dimethyl sulfoxide, dimethylformamide, γ-butyrolactone and cyclohexanone.

  The boiling point of the poor solvent is preferably 150 ° C. or lower. By using a poor solvent having a boiling point of 150 ° C., the effect of improving adhesiveness and heat resistance is more easily exhibited.

  The poor solvent preferably contains at least one solvent selected from the group consisting of water, ether compounds (ethers), chloroform, n-hexane, methyl ethyl ketone, acetone and alcohol compounds (alcohols).

  The thickness of the fiber base material is preferably 5 to 100 μm. By using such a fiber substrate having a specific thin thickness, a printed circuit board that has great flexibility, can be bent arbitrarily, and can be mounted at a high density inside the housing can be obtained.

  Moreover, it is preferable that a fiber base material is a glass cloth at the point which is excellent in the handleability of a prepreg, and the insulation of the printed circuit board obtained.

  The polyamide-imide resin is preferably a polyamide-imide resin (siloxane-modified polyamide-imide resin) having a divalent group consisting of a polysiloxane chain in that the flexibility of the resulting printed circuit board is increased.

  The polyamideimide resin is preferably a polyamideimide resin having a divalent group represented by the following chemical formula (1). By using the polyamideimide resin having such a specific structure, the peeling strength of the metal foil on the printed circuit board can be further increased.

  Polyamideimide resin is added to a diamine diamine, a diamine mixture containing an alicyclic diamine represented by the following chemical formula (2) and an aromatic diamine represented by the following general formula (3a) or (3b). It is a polyamide-imide resin obtained by a production method comprising a first reaction step of reacting merit acid to obtain an imide group-containing dicarboxylic acid and a second reaction step of reacting the imide group-containing dicarboxylic acid with a diisocyanate. ,preferable. The polyamideimide resin obtained by such a production method has both a divalent group composed of a polysiloxane chain and a divalent group represented by the above chemical formula (1).

［式（３ａ）及び（３ｂ）中、Ｘ^１は炭素数１〜３の２価の脂肪族炭化水素基、炭素数１〜３の２価のハロゲン化脂肪族炭化水素基、スルホニル基、オキシ基、カルボニル基、単結合又は下記一般式（３１ａ）若しくは（３１ｂ）で表される２価の基を示し、Ｘ^２は炭素数１〜３の２価の脂肪族炭化水素基、炭素数１〜３の２価のハロゲン化脂肪族炭化水素基、スルホニル基、オキシ基又はカルボニル基を示し、Ｒ^１、Ｒ^２及びＲ^３はそれぞれ独立に水素原子、水酸基、メトキシ基、メチル基又はハロゲン化メチル基を示す。

式（３１ａ）中、Ｚは炭素数１〜３の２価の脂肪族炭化水素基、炭素数１〜３の２価のハロゲン化脂肪族炭化水素基、スルホニル基、オキシ基、カルボニル基又は単結合を示す。］

[In the formulas (3a) and (3b), X ¹ represents a divalent aliphatic hydrocarbon group having 1 to 3 carbon atoms, a divalent halogenated aliphatic hydrocarbon group having 1 to 3 carbon atoms, a sulfonyl group, an oxy group. A divalent group represented by a group, a carbonyl group, a single bond or the following general formula (31a) or (31b), wherein X ² is a divalent aliphatic hydrocarbon group having 1 to 3 carbon atoms; Represents a divalent halogenated aliphatic hydrocarbon group of ˜3, a sulfonyl group, an oxy group or a carbonyl group, and R ¹ , R ² and R ³ each independently represent a hydrogen atom, a hydroxyl group, a methoxy group, a methyl group or a halogenated group Indicates a methyl group.

In formula (31a), Z represents a divalent aliphatic hydrocarbon group having 1 to 3 carbon atoms, a divalent halogenated aliphatic hydrocarbon group having 1 to 3 carbon atoms, a sulfonyl group, an oxy group, a carbonyl group, or a simple group. Indicates a bond. ]

  The varnish preferably further contains a thermosetting resin. By combining the thermosetting resin with the polyamideimide resin, the heat resistance of the printed circuit board can be further enhanced. Furthermore, this thermosetting resin is preferably an epoxy resin from the viewpoint of heat resistance, dimensional stability, and the like.

  A metal foil-clad laminate of the present invention comprises a substrate obtained by heating and pressing a laminate obtained by laminating a predetermined number of the prepregs of the present invention, and a metal foil provided on at least one surface of the substrate. It is a metal foil-clad laminate and can be suitably used to obtain a printed circuit board. The printed circuit board of the present invention is obtained by forming a circuit on the metal foil-clad laminate of the present invention. These metal foil-clad laminates and printed circuit boards can be produced using the prepreg of the present invention, so that both the adhesive strength and heat resistance between the metal foil and the substrate can be achieved at a sufficiently high level at the same time.

  ADVANTAGE OF THE INVENTION According to this invention, the metal foil tension laminated board and printed circuit board which achieve both the adhesive strength and heat resistance of metal foil and a board | substrate at a sufficiently high level simultaneously, and the prepreg which can obtain these are provided. The

  FIG. 1 is a partial perspective view showing an embodiment of a prepreg according to the present invention. A prepreg 100 shown in FIG. 1 is a sheet-like prepreg composed of a fiber base material and a resin composition impregnated therein.

  The fiber base material in the prepreg 100 is a flexible fiber base material that can be bent arbitrarily, and the thickness thereof is preferably 5 to 100 μm. Thereby, the flexibility of the obtained printed circuit board becomes large, and it becomes easy to bend arbitrarily. In order to further increase the flexibility of the printed circuit board, the thickness is more preferably 5 to 50 μm, and further preferably 10 to 30 μm. By using a fiber base material, it becomes possible to reduce the dimensional change accompanying heating, moisture absorption, etc. in a manufacturing process.

  Along with the downsizing and high performance of electronic devices, it has become necessary to store components mounted in a limited space inside the housing. The plate can be mounted in the housing at a high density. As a printed circuit board that can be arbitrarily bent, a plurality of printed circuit boards are arranged in multiple stages and connected to each other by a wire harness or a flexible wiring board, or a flexible substrate based on polyimide. A rigid-flex substrate in which a conventional rigid substrate is multilayered is known. However, printed circuit boards that can be bent arbitrarily while using a fiber base material are conventional foldable prints because they have little dimensional change due to heating, moisture absorption, etc. in the manufacturing process and PCT resistance. It is also superior to circuit boards.

  The form of the fiber base material is not particularly limited as long as it is used when producing a metal foil-clad laminate or a multilayer printed circuit board. Usually, a fiber base material such as a woven fabric or a nonwoven fabric is used. The fibers constituting the fiber substrate include glass, alumina, asbestos, boron, silica alumina glass, silica glass, tyranno, silicon carbide, silicon nitride, zirconia, and other inorganic fibers, aramid, polyetheretherketone, polyetherimide , Organic fibers such as polyethersulfone, carbon and cellulose, or mixed papers thereof. Among these, glass fiber is preferable. In particular, glass cloth (glass fiber woven fabric) is preferably used as the fiber base material.

  The prepreg 100 is obtained by removing a solvent from a varnish containing a solvent and a polyamideimide resin dissolved in the solvent and impregnating the fiber base material. Therefore, the resin composition in the prepreg 100 is a resin composition containing a polyamideimide resin. Usually, the resin composition in a prepreg contains a small amount of solvent as a residual volatile matter.

  The solvent for the varnish is a mixed solvent composed of a good solvent and a poor solvent for the polyamideimide resin. Compared with the case where a resin composition containing a polyamide resin is diluted with only a good solvent, the viscosity of the varnish decreases more when diluted with a poor solvent. Therefore, by using a mixed solvent, even a varnish containing a high-concentration resin composition can have a low viscosity, and the impregnation of the varnish into the fiber substrate becomes easy.

  In this mixed solvent, the content ratio of the poor solvent is preferably 1 to 60% by mass, more preferably 30 to 50% by mass based on the entire mixed solvent. In other words, the mixing ratio of the good solvent to the poor solvent (good solvent / poor solvent) in the mixed solvent is preferably 99/1 to 40/60 by weight, and preferably 70/30 to 50/50. More preferred. By setting the content ratio of the poor solvent in such a range, the effects of reducing the residual volatile content in the prepreg, stabilizing the adhesive strength with the metal foil, and further improving the heat resistance of the substrate are particularly prominent. When the content ratio of the poor solvent is less than 1% by mass, such effects tend to decrease. When the content exceeds 60% by mass, the polyamide resin tends to precipitate and the stability of the varnish tends to decrease. is there.

  A good solvent is a solvent in which the solubility of the polyamideimide resin used in the varnish (the amount of solute that can be dissolved in 100 g of the solvent) is 10 g or more at room temperature. The good solvent preferably has a polyamideimide resin solubility of 20 g or more, and more preferably 30 g or more. Moreover, it is preferable that the boiling point of a good solvent exceeds 150 degreeC.

  Specifically, the good solvent contains at least one solvent selected from the group consisting of N-methyl-2-pyrrolidone, N, N-dimethylacetamide, dimethyl sulfoxide, dimethylformamide, γ-butyrolactone, and cyclohexanone. Is preferred.

  On the other hand, the poor solvent has a solubility of the polyamide-imide resin used for the varnish of less than 10 g at room temperature. As for this poor solvent, it is more preferable that the solubility of a polyamide-imide resin is 5 g or less, and it is further more preferable that it is 1 g or less. Moreover, it is preferable that a poor solvent is 150 degrees C or less, and it is more preferable that it is 50-150 degreeC.

  Specifically, the poor solvent preferably contains at least one solvent selected from the group consisting of water, ether compounds, chloroform, n-hexane, methyl ethyl ketone, acetone and alcohol compounds. Furthermore, among these, methyl ethyl ketone, acetone or an alcohol compound which does not contain a halogen and has a boiling point of 50 to 150 ° C. is particularly preferable. Here, examples of the ether compound include diisopropyl ether and dibutyl ether, and examples of the alcohol compound include methanol, ethanol, 2-propanol, and isobutanol.

  As described above, the good solvent and the poor solvent are determined by the solubility of the polyamideimide resin used in the varnish. As a simpler method, a reference polyamideimide resin is separately prepared, and the solubility of the polyamideimide resin is determined. It is good also as a standard. As a reference polyamideimide resin, for example, a polyamideimide resin obtained as follows can be used.

  First, 82.10 g (0.20 mol) of BAPP (2.2-bis [4- (4-aminophenoxy) phenyl] propane), which is an aromatic diamine, and 80.68 g of TMA (trimellitic anhydride) (0 And 42 mol) in NMP (N-methyl-2-pyrrolidone) at 80 ° C., and then 100 ml of toluene was added to the reaction solution and subjected to thermal dehydration and cyclization at 160 ° C., whereby an imide group-containing dicarboxylic acid was obtained. Get. Next, after cooling the reaction solution to room temperature, 60.07 g (0.24 mol) of MDI (4,4′-diphenylmethane diisocyanate) is added as an aromatic diisocyanate and allowed to undergo decarboxylation polyaddition reaction with an imide group-containing dicarboxylic acid. Thus, a polyamide resin that can be used as a standard for solubility is obtained. The weight average molecular weight of the polyamideimide resin thus obtained is 70,000 to 90,000.

  The polyamide-imide resin is not particularly limited as long as it is a resin composed of a polymer having an imide group and an amide group in the main chain. By using the polyamide-imide resin, the resulting metal foil-clad laminate and printed circuit board have excellent thermal shock resistance, reflow resistance, and crack resistance, and are advantageous for the formation of fine wiring.

  The polyamideimide resin is preferably a siloxane-modified polyamideimide resin having a divalent group consisting of a polysiloxane chain. The polyamideimide resin preferably has a divalent group represented by the chemical formula (1). Furthermore, a polyamideimide resin having both a divalent group composed of a polysiloxane chain and a divalent group represented by the above chemical formula (1) is more preferable.

  The polyamideimide resin is synthesized using a good solvent having a boiling point exceeding 150 ° C. as a reaction solvent, such as N-methyl-2-pyrrolidone and N, N-dimethylacetamide, which are commonly used synthetic solvents. Is preferred.

  Such a polyamide-imide resin is, for example, a diamine mixture containing a siloxane diamine, an alicyclic diamine represented by the chemical formula (2), and an aromatic diamine represented by the general formula (3a) or (3b). A first reaction step of reacting trimellitic anhydride to obtain an imide group-containing dicarboxylic acid (diimide dicarboxylic acid having two imide groups), a second reaction step of reacting the imide group-containing dicarboxylic acid with a diisocyanate, It can obtain suitably by using the manufacturing method provided with.

  In the diamine mixture used in the first reaction step, the ratio (a / b) between the amount a of the alicyclic diamine represented by the chemical formula (2) and the amount b of the other diamines (aromatic diamine and siloxane diamine). Is preferably 0.1 / 99.9 to 99.9 / 0.1 in molar ratio, more preferably 10/90 to 50/50, and 20/80 to 40/60 Is more preferable.

  As the alicyclic diamine represented by the chemical formula (2), for example, “Wandamine” (trade name, manufactured by Shin Nippon Rika Co., Ltd.), which is 4,4′-diaminodicyclohexylmethane, is commercially available. .

  As the aromatic diamine, a diamine having two or more aromatic rings is preferable. Specifically, 2,2-bis [4- (4-aminophenoxy) phenyl] propane (BAPP), bis [4- (3-aminophenoxy) phenyl] sulfone, bis [4- (4-aminophenoxy) Phenyl] sulfone, 2,2-bis [4- (4-aminophenoxy) phenyl] hexafluoropropane, bis [4- (4-aminophenoxy) phenyl] methane, 4,4′-bis (4-aminophenoxy) Biphenyl, bis [4- (4-aminophenoxy) phenyl] ether, bis [4- (4-aminophenoxy) phenyl] ketone, 1,3-bis (4-aminophenoxy) benzene, 1,4-bis (4 -Aminophenoxy) benzene, 2,2'-dimethylbiphenyl-4,4'-diamine, 2,2'-bis (trifluoromethyl) biphenyl 4,4′-diamine, 2,6,2 ′, 6′-tetramethyl-4,4′-diamine, 5,5′-dimethyl-2,2′-sulfonyl-biphenyl-4,4′-diamine, 3,3′-dihydroxybiphenyl-4,4′-diamine, (4,4′-diamino) diphenyl ether, (4,4′-diamino) diphenylsulfone, (4,4′-diamino) benzophenone, (3,3 Examples include '-diamino) benzophenone, (4,4'-diamino) diphenylmethane, (4,4'-diamino) diphenyl ether, (3,3'-diamino) diphenyl ether, and the like. These can be used alone or in combination as an aromatic diamine.

  The siloxane diamine is not particularly limited as long as it is a diamine compound having a polysiloxane chain, and examples thereof include those represented by the following general formula (4a), (4b), (4c) or (4d).

In the above formulas (4a) to (4d), n ₁ , n ₂ , n ₃ and n ₄ each independently represent a positive integer. n ₁ , n ₂ , n ₃ and n ₄ are each preferably 1 to 50.

  Examples of the siloxane diamine represented by the general formula (4a) include “X-22-161AS” (amine equivalent 450), “X-22-161A” (amine equivalent 840), “X-22-161B” (amine). Equivalent 1500) (above trade name, manufactured by Shin-Etsu Chemical Co., Ltd.), “BY16-853” (amine equivalent 650), “BY16-853B” (amine equivalent 2200) (above trade name, manufactured by Toray Dow Corning Silicone Co., Ltd.) Etc. are available as commercial products.

  Examples of the siloxane diamine represented by the general formula (4d) include “X-22-9409” (amine equivalent 700), “X-22-1660B-3” (amine equivalent 2200) (above trade names, Shin-Etsu Chemical Co., Ltd.). Etc.) are commercially available.

  The diamine mixture used in the first reaction step may contain an aliphatic diamine in addition to the above diamine. By using an aliphatic diamine, it is possible to lower the elastic modulus of the resin in the substrate while maintaining a high glass transition temperature, and it becomes even easier to bend the printed circuit board. It is also possible to adjust the elastic modulus of the resin by increasing or decreasing the proportion of the aliphatic diamine in the entire amine mixture.

As aliphatic diamine, the compound represented by following General formula (5) is mentioned, for example. In Formula (5), X ³ represents a methylene group, a sulfonyl group, an oxy group (ether group), a carbonyl group or a single bond, and R ⁴ and R ⁵ each independently have a hydrogen atom, an alkyl group or a substituent. The phenyl group which may be shown is shown, p shows the integer of 1-50.

The R ⁴ and R ^5, a hydrogen atom, preferably a phenyl group which may have an alkyl group or a substituent having 1 to 3 carbon atoms. Examples of the substituent for the phenyl group include an alkyl group having 1 to 3 carbon atoms and a halogen atom. In order to achieve both the low elastic modulus and high Tg of the resin, X ³ in the general formula (5) is preferably an oxy group. Commercially available products of aliphatic diamines in which X ³ is an oxy group include “Jeffamine D-400” (trade name, manufactured by Sun Techno Chemical Co., amine equivalent 400), “Jephamine D-2000” (trade name, Sun Techno Chemical). An amine equivalent 1000), etc. can be illustrated.

  As the diisocyanate used in the second reaction step, for example, a compound represented by the following general formula (6) can be used.

  As the diisocyanate represented by the general formula (6), aliphatic diisocyanate or aromatic diisocyanate can be used, but it is preferable to use aromatic diisocyanate, and it is more preferable to use both in combination.

In the case of an aromatic diisocyanate, D in the general formula (6) is a divalent organic group having at least one (preferably two or more) aromatic rings. In this case, D is _{-C 6 H 4 -CH 2 -C 6} H 4 - a divalent group represented by is preferably selected from the group consisting of tolylene group and a naphthylene group. More specifically, the aromatic diisocyanate includes 4,4′-diphenylmethane diisocyanate (MDI), 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, naphthalene-1,5-diisocyanate, 2,4. -Tolylene dimer etc. can be illustrated and it is especially preferable to use MDI. By using MDI as the aromatic diisocyanate, the flexibility of the resin containing the polyamideimide resin is improved, and the flexibility of the printed circuit board can be further increased.

  In the case of an aliphatic diisocyanate, D in the general formula (6) is a divalent aliphatic hydrocarbon group. In this case, D is preferably at least one group selected from the group consisting of a hexamethylene group, a 2,2,4-trimethylhexamethylene group and an isophorone group. That is, as the aliphatic diisocyanate, hexamethylene diisocyanate, 2,2,4-trimethylhexamethylene diisocyanate, isophorone diisocyanate and the like are preferable.

  When using together aromatic diisocyanate and aliphatic diisocyanate, it is preferable to add 5-10 mol% of aliphatic diisocyanate with respect to aromatic diisocyanate. Such combined use can further improve the heat resistance of the resulting polyamideimide resin.

  By using the raw materials as described above and adopting a production method including the first and second reaction steps, a polyamideimide resin that can be suitably used for the prepreg of the present invention is obtained. In addition, a 1st and 2nd reaction process can each be performed by conventionally well-known reaction conditions.

  The varnish preferably further contains a thermosetting resin in addition to the solvent and the polyamideimide resin. Examples of the thermosetting resin include epoxy resins, polyimide resins, unsaturated polyester resins, polyurethane resins, bismaleimide resins, triazine-bismaleimide resins, phenol resins, and the like. Among these, an epoxy resin which is a thermosetting resin having an epoxy group as a functional group capable of reacting with an amide group in the polyamide-imide resin is preferable.

  The content of the thermosetting resin is preferably 1 to 200 parts by weight, more preferably 3 to 100 parts by weight, and more preferably 10 to 60 parts by weight with respect to 100 parts by weight of the polyamideimide resin. Further preferred. When this content is less than 1 part by weight, the solvent resistance tends to decrease, and when it exceeds 200 parts by weight, the Tg of the resin in the substrate decreases due to the unreacted thermosetting resin, or is flexible. Tend to decrease.

  Examples of the epoxy resin include polyglycidyl ether, polyglycidyl ester, polyglycidylamine (N-glycidyl derivative), and alicyclic epoxy resin. The polyglycidyl ether is obtained, for example, by reacting a polyhydric phenol such as bisphenol A, a novolak-type phenol resin and an orthocresol novolac-type phenol resin, or a polyhydric alcohol such as 1,4-butanediol with epichlorohydrin, The polyglycidyl ester is obtained by reacting, for example, a polybasic acid such as phthalic acid or hexahydrophthalic acid with epichlorohydrin, and the N-glycidyl derivative is, for example, a compound having an amine, an amide or a heterocyclic nitrogen base. And epichlorohydrin.

  By using an epoxy resin as a thermosetting resin, a printed circuit board that can be cured at a temperature of 180 ° C. or less and reacts with an amide group of a polyamide-imide resin to have particularly good thermal, mechanical, and electrical characteristics. can get. The epoxy resin usually has 2 or more glycidyl groups, but more preferably 3 or more. The suitable content of the epoxy resin varies depending on the number of glycidyl groups that the epoxy resin has. As the number of glycidyl groups possessed by the epoxy resin increases, the content thereof can be reduced.

  When using an epoxy resin as a thermosetting resin, it is preferable to further contain an epoxy resin curing agent and / or a curing accelerator in the varnish. The epoxy resin curing agent and the curing accelerator are not particularly limited as long as they react with the epoxy resin or accelerate the curing of the epoxy resin. Or what has the function of both a hardening | curing agent and a hardening accelerator may be used.

  As the curing agent, for example, amines, imidazoles, polyfunctional phenols, acid anhydrides and the like can be used. As the amines, dicyandiamide, diaminodiphenylmethane, guanylurea and the like can be used. As the polyfunctional phenols, hydroquinone, resorcinol, bisphenol A and their halogen compounds, and a novolak type phenol resin or resole which is a condensate with formaldehyde. Type phenol resins can be used, and as the acid anhydrides, phthalic anhydride, benzophenone tetracarboxylic dianhydride, methyl hymic acid and the like can be used. As the curing accelerator, for example, imidazoles such as alkyl group-substituted imidazole and benzimidazole can be used.

  When the curing agent is an amine, the blending amount is preferably such that the active hydrogen equivalent and the epoxy equivalent of the epoxy resin are approximately equal. In addition, when the curing accelerator is imidazole, the blending amount is empirically set to 0.001 to 10 parts by weight with respect to 100 parts by weight of the epoxy resin, rather than simply having an equivalent ratio with active hydrogen. preferable. When the curing agent is polyfunctional phenols or acid anhydrides, the blending amount is an amount that is a ratio of 0.6 to 1.2 equivalents of phenolic hydroxyl groups or carboxyl groups with respect to 1 equivalent of epoxy resin. Is preferred. When the amount of these curing agents or curing accelerators is small, unreacted epoxy resin tends to remain in the substrate, leading to a decrease in Tg (glass transition temperature). The promoter remains and the insulating property tends to decrease. Further, since the epoxy group of the epoxy resin can also react with the amide group of the polyamideimide resin, it is preferable to set the amount of the curing agent in consideration of this.

  The varnish may further contain an additive type flame retardant for the purpose of improving flame retardancy. As this flame retardant, a phosphorus-containing filler containing phosphorus is preferable. Examples of the phosphorus-containing filler include “OP930” (trade name, manufactured by Clariant, phosphorus content 23.5% by mass), “HCA-HQ” (trade name, manufactured by Sanko Co., Ltd., phosphorus content 9.6% by mass). ), “PMP-100” (phosphorus content 13.8 mass%), “PMP-200” (phosphorus content 9.3 mass%), “PMP-300” (phosphorus content 9) which are melamine polyphosphates .8% by mass) (trade name, manufactured by Nissan Chemical Co., Ltd.) and the like are commercially available. When the amount of the phosphorus-containing filler added is large, the flame retardancy is further improved, but at the same time, the flexibility of the substrate is lowered or the heat resistance when the printed circuit board is obtained tends to be lowered. Therefore, the addition amount of the phosphorus-containing filler is preferably 0.1 to 10% by mass and more preferably 1 to 5% by mass based on the amount of resin solids (components other than the solvent) in the varnish. preferable. By using such a phosphorus-containing filler, a printed circuit board having a halogen-free and sufficient flame retardancy can be obtained.

  The varnish can be prepared by dissolving the polyamideimide resin in the above mixed solvent and further dissolving or dispersing components other than the above polyamideimide resin as necessary. Alternatively, a polyamideimide resin may be synthesized in a good solvent, and a poor solvent may be added to the reaction solution after the synthesis reaction. In this case, it is preferable to add a good solvent such as dimethyl sulfoxide, N, N-dimethylformamide, γ-butyrolactone, cyclohexanone or the like in addition to the poor solvent to adjust the concentration and viscosity.

  Here, the polyamideimide resin in the varnish is preferably completely dissolved in the mixed solvent. However, if the varnish has such fluidity and uniformity that it can be essentially uniformly impregnated into the entire fiber base, a part of the polyamide-imide resin is finely and uniformly in the mixed solvent. It may be in a dispersed state. When coarse particles of polyamideimide resin precipitated in the varnish are present, it becomes difficult to impregnate the fiber substrate essentially uniformly. Thus, by using the varnish in which the polyamideimide resin is dissolved, a prepreg in which the resin composition is essentially uniformly impregnated in the entire fiber base material is obtained.

  The prepreg 100 can be suitably manufactured by, for example, a manufacturing method including an impregnation step of impregnating a fiber base with a varnish as described above and a solvent removal step of removing the solvent from the impregnated varnish.

  The prepreg obtained by such a production method is usually a prepreg obtained by impregnating a fiber base material having a predetermined thickness with a resin composition, and the resin composition comprises a polyamideimide resin, a solvent, Is a prepreg which is a resin composition containing a thermosetting resin as an essential component. Here, the amount of the solvent contained in the prepreg as the residual volatile matter is preferably 2% by mass or less based on the mass of the entire prepreg.

  In the impregnation step, the method of impregnating the varnish is not particularly limited, and the impregnation can be performed by a conventionally known method such as immersing the fiber base material in the varnish. The amount of impregnation of the varnish is preferably such that the resin solid content is 30 to 80% by mass with respect to the total amount of the resin solid content (components other than the solvent) and the fiber base in the varnish.

  In the solvent removal step, the solvent contained in the varnish is removed. In other words, the prepreg is dried. The solvent is preferably removed so that 80% by mass or more of the solvent in the varnish volatilizes. Specifically, it is preferable to remove the solvent by heating to 80 to 180 ° C. Further, the heating time is preferably within a time range in which the varnish does not gel in consideration of the gel time of the varnish.

  Here, when the varnish contains 100 parts by weight of the siloxane-modified polyamideimide resin and 1 to 200 parts by weight of the thermosetting resin, the volatilization rate of the solvent in the varnish can be particularly increased. When the volatilization rate of the solvent is high, the solvent is removed at a low temperature of 150 ° C. or less at which the curing reaction of the thermosetting resin is not accelerated so much in the solvent removal step, and the residual volatile content is low, for example, 5% by mass or less. It becomes possible to become a level. By reducing the residual volatile matter, a metal foil-clad laminate having good adhesion between the fiber substrate and metal foil (such as copper foil) and the cured product of the resin composition can be obtained. Also, if the residual volatile content is small, the occurrence of swelling due to the volatilization of the solvent is suppressed in the lamination process with a metal foil such as a copper foil, and the solder heat resistance of the obtained metal foil-clad laminate is further improved. can do.

  A metal foil-clad laminate of the present invention comprises a substrate obtained by heating and pressing a laminate in which a predetermined number of prepregs are laminated, and a metal foil provided on at least one surface of the substrate. It is a board. By using the prepreg of the present invention, this metal foil-clad laminate can simultaneously achieve both the adhesive strength and heat resistance between the metal foil and the substrate at a high level.

  FIG. 2 is a partial cross-sectional view showing an embodiment of a metal foil-clad laminate according to the present invention. The metal foil-clad laminate 200 includes a sheet-like substrate 30 obtained by heating and pressing a laminate in which a predetermined number of prepregs 100 are laminated, and two metal foils 10 provided in close contact with both surfaces of the substrate 30. It consists of.

  The substrate 30 is made of a laminate in which a plurality of fiber reinforced resin layers 3 derived from a plurality of prepregs 100 are laminated. In order to increase the flexibility of the metal foil-clad laminate and the printed circuit board, the thickness of the substrate 30 is preferably 10 to 500 μm. In each fiber reinforced resin layer 3, the fiber base material is impregnated with resin as a matrix. When an epoxy resin is used for the varnish, in this resin, a crosslinked structure is formed by a crosslinking reaction between the polyamideimide resin and the epoxy resin.

  The metal foil-clad laminate can be obtained by stacking metal foil on both sides of a laminate in which a predetermined number (preferably 10 or less) of prepregs 100 are laminated, and heating and pressing the laminate. At this time, the heating temperature and pressure are not particularly limited, but the heating temperature is usually 150 to 280 ° C. (preferably 180 to 250 ° C.), and the pressure is usually 0.5 to 20 MPa (preferably 1 to 8 MPa). Range.

  As the metal foil 10, a copper foil or an aluminum foil is generally used, but a copper foil is preferable. As the copper foil, one having a thickness of 5 to 200 μm, which is usually used for a copper-clad laminate, can be used, but in order to increase the flexibility of the printed circuit board, the thickness is 5 to 18 μm. Is more preferable. Alternatively, nickel, nickel-phosphorus, nickel-tin alloy, nickel-iron alloy, lead, lead-tin alloy, etc. are used as intermediate layers, and a 0.5-15 μm copper layer and a 10-300 μm copper layer are provided on both sides. Alternatively, a three-layer composite foil or a two-layer composite foil in which aluminum and copper foil are combined can be used.

  The embodiment of the metal foil-clad laminate is not limited to the above aspect. For example, using one prepreg 100, the substrate may be composed of one fiber reinforced resin layer, or a metal foil may be provided on only one side of the substrate. In addition, the insulating plate which consists of a laminated body comprised by a fiber reinforced resin layer can also be obtained by heating and pressurizing only the prepreg 100, without laminating | stacking metal foil.

  FIG. 3 is a partial cross-sectional view showing an embodiment of a printed circuit board according to the present invention. A printed circuit board 300 shown in FIG. 3 is mainly composed of a substrate 30 similar to the above and two metal foils 10 bonded to both surfaces of the substrate 30, and a part of the metal foil 10 is removed. A wiring pattern is formed. Further, a plurality of through holes 70 are formed to penetrate the printed circuit board 300 in a direction substantially perpendicular to the main surface, and a metal plating layer 60 having a predetermined thickness is formed on the hole wall of the through hole 70. ing.

  The printed circuit board 300 is obtained by forming a circuit on the metal foil-clad laminate 200 described above. Circuit formation (circuit processing) can be performed by a conventionally known method such as a subtractive method. In addition, a predetermined circuit component (not shown) is usually mounted on the printed circuit board 300.

  Examples and comparative examples will be described below, but the present invention is not limited to these examples.

(Synthesis of polyamide-imide resin)
Polyamideimide resin was synthesized using the following raw materials.
<Aromatic diamine>
・ DDS (Diaminodiphenylsulfone, aromatic diamine having two or more aromatic rings)
<Siloxane diamine>
"KF-8010" (trade name, manufactured by Shin-Etsu Chemical Co., Ltd., reactive silicone oil, amine equivalent 430)
"X-22-161A" (trade name, manufactured by Shin-Etsu Chemical Co., Ltd., reactive silicone oil, amine equivalent 900)
<Aliphatic diamine>
・ "Jefamine D-2000" (trade name, manufactured by Sun Techno Chemical Co., Ltd., amine equivalent 1000)
<Alicyclic diamine>
・ "Wandamin" (trade name, manufactured by Shin Nippon Rika Co., Ltd.)
<Trimellitic anhydride>
・ TMA
<Good solvent for polyamideimide resin>
・ NMP (N-methyl-2-pyrrolidone, aprotic polar solvent)
<Aromatic hydrocarbon azeotropic with water>
・ Toluene <aromatic diisocyanate>
・ MDI (4,4'-diphenylmethane diisocyanate)

(Synthesis Example 1)
<First reaction step>
In a 1-liter separable flask equipped with a 25 ml moisture meter with a cock connected to a reflux condenser, a thermometer and a stirrer, 14.9 g (0.06 mol) of DDS, 43.0 g of “KF-8010” ( 0.05 mol), 72.0 g (0.36 mol) of “Jeffamine D-2000”, 1.3 g (0.054 mol) of “Wandamine”, 80.7 g (0.42 mol) of TMA, and 524 g of NMP were added to the reaction solution. And stirred at 80 ° C. for 30 minutes. Then, 150 ml of toluene was added, the temperature of the reaction solution was raised, and the mixture was refluxed at about 160 ° C. for 2 hours. After confirming that approximately 7.2 ml or more of water has accumulated in the moisture determination receiver and that no distilling of water can be observed, while removing the distillate accumulated in the moisture determination receiver, The temperature was raised to ° C. and toluene was removed from the reaction solution.
<Second reaction step>
Thereafter, 55.1 g (0.22 mol) of MDI was added to the reaction solution returned to room temperature (25 ° C.) and reacted at 190 ° C. for 2 hours. After completion of the reaction, an NMP solution of polyamideimide resin was obtained.

(Synthesis Example 2)
<First reaction step>
Into a 1 liter separable flask equipped with a 25 ml water meter with a cock connected to a reflux condenser, a thermometer and a stirrer, 14.9 g (0.06 mol) of DDS, 51.6 g of “KF-8010” (0 0.06 mol), 52.0 g (0.26 mol) of “Jeffamine D-2000”, 11.3 g (0.054 mol) of “Wandamine”, 80.7 g (0.42 mol) of TMA, and 663 g of NMP to obtain a reaction solution. This was stirred at 80 ° C. for 30 minutes. Then, 150 ml of toluene was added, the temperature of the reaction solution was raised, and the mixture was refluxed at about 160 ° C. for 2 hours. After confirming that approximately 7.2 ml or more of water has accumulated in the moisture determination receiver and that no distilling of water can be observed, while removing the distillate accumulated in the moisture determination receiver, The temperature was raised to ° C. and toluene was removed from the reaction solution.
<Second reaction step>
Thereafter, 55.1 g (0.22 mol) of MDI (4,4′-diphenylmethane diisocyanate) as an aromatic diisocyanate was added to the reaction solution returned to room temperature (25 ° C.), and reacted at 190 ° C. for 2 hours. After completion of the reaction, an NMP solution of polyamideimide resin was obtained.

(Synthesis Example 3)
<First reaction step>
Into a 1 liter separable flask equipped with a 25 ml water meter with a cock connected to a reflux condenser, a thermometer and a stirrer, 14.9 g (0.06 mol) of DDS, 108.0 g of “X-22-161A” (0.05 mol), “Jefamine D-2000” 72.0 g (0.36 mol), “Wandamine” 11.3 g (0.054 mol), TMA 80.7 g (0.42 mol), and NMP 728 g were added and reacted. This was stirred at 80 ° C. for 30 minutes. Then, 150 ml of toluene was added, the temperature of the reaction solution was raised, and the mixture was refluxed at about 160 ° C. for 2 hours. After confirming that approximately 7.2 ml or more of water has accumulated in the moisture determination receiver and that no distilling of water can be observed, while removing the distillate accumulated in the moisture determination receiver, The temperature was raised to ° C. and toluene was removed from the reaction solution.
<Second reaction step>
Thereafter, 60.1 g (0.24 mol) of MDI (4,4′-diphenylmethane diisocyanate) as an aromatic diisocyanate was added to the reaction solution returned to room temperature (25 ° C.), and reacted at 190 ° C. for 2 hours. After completion of the reaction, an NMP solution of polyamideimide resin was obtained.

(Comparison of dilution effect of good or poor solvent)
228.6 g of NMP solution of polyamideimide resin obtained in Synthesis Example 1 (resin solid content: 32% by mass) and methyl ethyl ketone of “NC3000H” (trade name, epoxy resin, manufactured by Nippon Kayaku Co., Ltd.) which is a thermosetting resin (MEK) A solution obtained by mixing 40.0 g of a solution (resin solid content: 50% by mass) and 0.2 g of 2-ethyl-4-methylimidazole is stirred for about 1 hour until uniform, and is used for viscosity evaluation. Varnish (resin solid content concentration 34.5% by mass) was prepared.

  N, N-dimethylacetamide (DMAC), which is a good solvent, or methyl ethyl ketone (MEK), which is a poor solvent, is added to the varnish of this resin composition, respectively, so that the resin solid content concentration is 20% by mass, 25.0% by mass. The result of having measured the viscosity change of the varnish when it diluted to 27.5 mass% and 30.0 mass% was shown in FIG. As shown in FIG. 4, the decrease in viscosity was greater in the case of dilution with MEK, which is a poor solvent, than in the case of dilution with DMAC, which is a good solvent.

Example 1
<Preparation of prepreg and copper clad laminate>
228.6 g of NMP solution of polyamideimide resin obtained in Synthesis Example 1 (resin solid content 35 mass%), 40.0 g of MEK solution (resin solid content 50 mass%) of “NC3000H” which is an epoxy resin, 2- The mixture obtained by mixing 0.2 g of ethyl-4-methylimidazole was stirred for about 1 hour until uniform, and then 79 g of MEK as a poor solvent was further added and stirred for about 1 hour. And this liquid mixture is left still for 24 hours at room temperature (25 degreeC) for defoaming, and contains the mixed solvent which consists of good solvent (NMP) / poor solvent (MEK) = 60/40 (weight ratio). And the density | concentration of resin solid content obtained the varnish whose mass reference | standard is 28.8 mass% of the whole varnish. The viscosity of the varnish at 25 ° C. was 300 mPa · sec.

  The obtained varnish was impregnated into a glass cloth having a thickness of 28 μm (“1037” (trade name), manufactured by Asahi Schavel Co., Ltd.), and this was heated at 150 ° C. for 15 minutes to remove the solvent, and 70 mass A prepreg impregnated with% (based on the total mass of the prepreg) was obtained. The residual volatile content of the obtained prepreg was 0.5% by mass (based on the total mass of the prepreg). A laminated body in which an electrolytic copper foil having a thickness of 12 μm (“F2-WS-12” (trade name), manufactured by Furukawa Electric Co., Ltd.) is laminated on both sides of the prepreg so that the adhesive surface is combined with the prepreg, It was heated and pressed under a press condition of 4.0 MPa for 90 minutes to obtain a double-sided copper-clad laminate.

<Evaluation of copper clad laminate>
About the obtained double-sided laminated board, the following items were evaluated. The evaluation results are summarized in Table 1.

(1) Copper foil peeling strength The obtained double-sided copper-clad laminate was subjected to a 90 ° peeling test, and the maximum load at that time was defined as the copper foil peeling strength.

(2) Solder heat resistance It was immersed in a solder bath heated to 260 ° C., 288 ° C. or 300 ° C., and the time (seconds) until abnormalities such as blistering and peeling occurred after the start of immersion was measured.

(3) Flexibility (flexibility)
The laminated board from which the copper foil was removed by etching was bent, and the flexibility was evaluated according to the following criteria depending on the presence or absence of breakage.
A: No breakage, B: Some breakage, C: Breakage.

(Example 2)
258.6 g of NMP solution of polyamideimide resin obtained in Synthesis Example 2 (resin solid content 29 mass%), 50.0 g of MEK solution (resin solid content 50 mass%) of “NC3000H” which is an epoxy resin, 2- 0.2 g of ethyl-4-methylimidazole and 66.7 g of MEK slurry (resin solid content 30% by mass) of “OP930” (trade name, manufactured by Clariant), which is a phosphorus-containing filler (phosphorous flame retardant filler) The mixed liquid was stirred for about 1 hour until it became uniform, and 112 g of MEK was further added and stirred for about 1 hour. And the liquid mixture is allowed to stand at room temperature (25 ° C.) for 24 hours for defoaming, and contains a mixed solvent of good solvent (NMP) / poor solvent (MEK) = 50/50 (weight ratio), A varnish having a resin solid content concentration of 24.7% by mass was obtained. The viscosity of the varnish at room temperature was 320 mPa · s.
Using the obtained varnish, the prepreg and the double-sided copper-clad laminate were prepared and evaluated in the same manner as in Example 1. The evaluation results are summarized in Table 1.

(Example 3)
274.2 g of NMP solution of polyamideimide resin obtained in Synthesis Example 3 (resin solid content 31 mass%) and MEK solution (resin solid content) of “DER331L” (trade name, manufactured by Dainippon Ink Co., Ltd.) which is an epoxy resin 50 mass%) 30.0 g, 2-ethyl-4-methylimidazole 0.2 g, and phosphorus-based flame retardant filler “OP930” acetone slurry (resin solid content 30 mass%) 66.7 g were mixed. The mixture was stirred for about 1 hour until uniform, then 40.2 g of acetone was further added and stirred for about 1 hour. The mixed solution is allowed to stand at room temperature (25 ° C.) for 24 hours for defoaming and contains a mixed solvent of good solvent (NMP) / poor solvent (MEK and acetone) = 65/35 (weight ratio). Thus, a varnish having a resin solid content concentration of 29.2% by mass was obtained. The viscosity of the varnish at room temperature was 350 mPa · s.
Using the obtained varnish, the prepreg and the double-sided copper-clad laminate were prepared and evaluated in the same manner as in Example 1. The evaluation results are summarized in Table 1.

(Comparative Example 1)
Only good solvents (NMP and DMAC) were obtained in the same manner as in Example 1 except that 50.0 g of DMAC solution of “NC3000H” (resin solid content: 50% by mass) was used as the epoxy resin and 140 g of DMAC was used instead of MEK79 g. A varnish having a concentration of resin solid content of 24.5% by mass was obtained. The viscosity of the varnish at room temperature was relatively low at 282 mPa · sec, reflecting the low concentration of resin solids.
Using the obtained varnish, the prepreg and the copper clad laminate were prepared and evaluated in the same manner as in Example 1. The evaluation results are summarized in Table 1.

(Comparative Example 2)
Using 50.0 g of “NC3000H” DMAC solution (resin solid content 50 mass%) as an epoxy resin and 66.7 g of “OP930” DMAC slurry (resin solid content 30 mass%) as a phosphorus-containing filler, Instead of using 50.0 g of DMAC in the same manner as in Example 2, a varnish containing a good solvent (NMP and DMAC) alone and containing a resin solid content of 28.3% by mass was obtained. The viscosity of the varnish at room temperature was 600 mPa · s.
Using the obtained varnish, the prepreg and the copper clad laminate were prepared and evaluated in the same manner as in Example 1. The evaluation results are summarized in Table 1.

(Comparative Example 3)
The mixed solvent consisting of good solvent (NMP) / poor solvent (MEK) = 30/70 (weight ratio) was obtained in the same manner as in Example 1 except that the amount of MEK added last was changed from 79 g to 326.7 g. An attempt was made to obtain a varnish of a resin composition comprising the resin, but a large amount of resin was precipitated, and a stable varnish could not be obtained. Therefore, it was not possible to prepare a prepreg.

In Table 1, the preparation amount (g) of each component in a varnish and each evaluation result are shown collectively.

  As shown in Table 1, the residual volatile content in the prepreg was 0.4 to 0.6% by mass in the examples, and 0.9 to 1.5% by mass in the comparative examples.

  In the case of Examples 1 to 3, the copper foil peel strength of the double-sided copper-clad laminate is good, showing a high value of 0.9 to 1.2 kN / m, and the solder heat resistance is 300 seconds or more, blistering, Abnormalities such as peeling were not observed and it was good, and it was excellent in flexibility (flexibility) and could be bent arbitrarily.

  On the other hand, in the case of Comparative Examples 1 and 2, an average copper foil peel strength value of 0.6 to 0.7 kN / m was obtained, but a variation of about 0.1 kN / m was partially observed. It was. Further, regarding solder heat resistance (300 ° C.), there was no problem until 180 seconds, but after that, partial blistering was observed. In Comparative Example 3 in which good solvent / poor solvent = 30/70, a large amount of resin solids were precipitated, and a stable varnish in which the polyamideimide resin was dissolved was not obtained, so that prepreg could not be produced.

It is a fragmentary perspective view which shows one Embodiment of the prepreg by this invention. It is a fragmentary sectional view showing one embodiment of a metal foil tension laminate sheet by the present invention. 1 is a partial cross-sectional view illustrating an embodiment of a printed circuit board according to the present invention. It is a graph which shows the relationship between the viscosity of a varnish, and resin solid content density | concentration.

Explanation of symbols

DESCRIPTION OF SYMBOLS 3 ... Fiber reinforced resin layer, 10 ... Metal foil, 30 ... Board | substrate, 60 ... Metal plating layer, 70 ... Through-hole, 100 ... Pre-preg, 200 ... Metal foil tension laminated board, 300 ... Printed circuit board.

Claims (10)

A prepreg obtained by removing the solvent from a varnish containing a solvent and a polyamideimide resin dissolved in the solvent and impregnating the fiber base material,
The varnish further contains an epoxy resin,
The solvent is a mixed solvent composed of a good solvent and a poor solvent of the polyamideimide resin, and the mixed solvent contains 30 to 50% by mass of the poor solvent based on the total amount thereof,
The said polyamide-imide resin is a prepreg which is a polyamide-imide resin which has a bivalent group represented by following Chemical formula (1).

  The good solvent contains at least one solvent selected from the group consisting of N-methyl-2-pyrrolidone, N, N-dimethylacetamide, dimethyl sulfoxide, dimethylformamide, γ-butyrolactone, and cyclohexanone. The prepreg as described.   The prepreg according to claim 1 or 2, wherein the poor solvent has a boiling point of 150 ° C or lower.   The said poor solvent contains at least 1 sort (s) of solvent chosen from the group which consists of water, an ether compound, chloroform, n-hexane, methyl ethyl ketone, acetone, and an alcohol compound. Prepreg.   The prepreg as described in any one of Claims 1-4 whose thickness of the said fiber base material is 5-100 micrometers.   The prepreg according to any one of claims 1 to 5, wherein the fiber base material is a glass cloth.   The prepreg according to any one of claims 1 to 6, wherein the polyamide-imide resin is a polyamide-imide resin having a divalent group composed of a polysiloxane chain. The polyamide-imide resin is a diamine diamine, an alicyclic diamine represented by the following chemical formula (2), and a diamine mixture containing an aromatic diamine represented by the following general formula (3a) or (3b). A first reaction step of reacting an acid to obtain an imide group-containing dicarboxylic acid;
The prepreg as described in any one of Claims 1-7 which is a polyamide imide resin obtained by a manufacturing method provided with the 2nd reaction process of making diisocyanate react with the said imide group containing dicarboxylic acid.

[In the formulas (3a) and (3b), X ¹ represents a divalent aliphatic hydrocarbon group having 1 to 3 carbon atoms, a divalent halogenated aliphatic hydrocarbon group having 1 to 3 carbon atoms, a sulfonyl group, an oxy group. A divalent group represented by a group, a carbonyl group, a single bond or the following general formula (31a) or (31b), wherein X ² is a divalent aliphatic hydrocarbon group having 1 to 3 carbon atoms; Represents a divalent halogenated aliphatic hydrocarbon group of ˜3, a sulfonyl group, an oxy group or a carbonyl group, and R ¹ , R ² and R ³ each independently represent a hydrogen atom, a hydroxyl group, a methoxy group, a methyl group or a halogenated group Indicates a methyl group.

In formula (31a), Z represents a divalent aliphatic hydrocarbon group having 1 to 3 carbon atoms, a divalent halogenated aliphatic hydrocarbon group having 1 to 3 carbon atoms, a sulfonyl group, an oxy group, a carbonyl group, or a simple group. Indicates a bond. ] A substrate obtained by heating and pressing a laminate obtained by laminating a predetermined number of the prepregs according to any one of claims 1 to 8 ,
A metal foil-clad laminate comprising: a metal foil provided on at least one surface of the substrate. A printed circuit board obtained by processing a circuit on the metal foil-clad laminate according to claim 9 .

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