JP4774702B2 - 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 pressurizing them is used. . 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 the above-mentioned laminated plate is called a so-called rigid substrate, and although it is excellent in terms of dimensional stability and the like, there is room for improvement in that it easily breaks when the laminated plate is bent. For the purpose of improving the flexibility (flexibility) of the laminate, for example, when a general aliphatic compound is contained in the prepreg, the Tg (glass transition temperature) of the prepreg is extremely lowered and a stable structure is maintained. It was difficult to do.

  Accordingly, the present invention provides a metal foil-clad laminate and a printed circuit board that are sufficiently excellent in flexibility (flexibility) while maintaining the high Tg characteristics of the prepreg, and a prepreg from which these can be obtained. For the purpose.

The prepreg of the present invention that solves the above problems includes a fiber base material and a resin composition impregnated therein, and the resin composition has a divalent group represented by the following formula (1) (hereinafter referred to as a resin group). And “alicyclic linking group-containing resin”).

  Since the prepreg of the present invention includes a resin composition containing an alicyclic linking group-containing resin, the prepreg is sufficiently excellent in flexibility (flexibility) while maintaining high Tg characteristics. Therefore, a metal foil-clad laminate or a printed circuit board produced by laminating such a prepreg can have both high heat resistance and excellent flexibility (flexibility).

  Moreover, in the metal foil tension laminated board and printed circuit board produced using the prepreg of this invention, since high copper foil peel strength (copper foil peeling strength) is obtained, the prepreg of this invention is metal foil and It is considered to have a high adhesive strength. Furthermore, in such a metal foil-clad laminate and a printed circuit board, good performance evaluation can be obtained even by a solder heat resistance test or a pressure cooker test (PCT). Therefore, by using the prepreg of the present invention, it is possible to obtain a metal foil-clad laminate or a printed circuit board having excellent solder heat resistance (solder resistance at high temperature) and PCT resistance (humidity resistance at high temperature). it can.

In the prepreg of the present invention, cycloaliphatic linking group-containing resin, Ru polyamideimide resin der. Using such a prepreg improves the thermal shock resistance, reflow resistance, crack resistance, etc. of the resulting metal foil-clad laminate and printed circuit board, so soldering is sufficient even if fine wiring is formed Stable surface mounting can be performed.

ここで、式（３ａ）中、Ｘ^１はスルホニル基を示し、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。
一般式（３ａ）で表される芳香族ジアミンは、ジアミノジフェニルスルホンであることが好ましい。 Here, the polyamide-imide resin is a siloxane diamine, an alicyclic diamine represented by the following formula (2) and an aromatic diamine represented by the following general formula (3a) (represented by the following formula (2)). A diamine mixture which is blended and contained at a ratio of 10/90 to 50/50 in terms of a molar ratio of (amount of alicyclic diamine) / (amount of aromatic diamine and siloxane diamine represented by the following general formula (3a)). (However, the aromatic diamine represented by the general formula (3a) is blended in an amount of 30 mol% or more with respect to the diamine mixture) and trimellitic anhydride is reacted to obtain an imide group-containing dicarboxylic acid. It is a polyamide-imide resin obtained by a production method comprising a reaction step and a second reaction step in which a diisocyanate is reacted with the imide group-containing dicarboxylic acid. 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 formula (1).

Here, in formula (3a), X ¹ represents a sulfonyl 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 methyl group.
The aromatic diamine represented by the general formula (3a) is preferably diaminodiphenyl sulfone.

  It is preferable that the resin composition further contains a thermosetting resin. By combining the alicyclic linking group-containing resin with a thermosetting resin, the heat resistance of the printed circuit board can be further increased. The thermosetting resin is more preferably an epoxy resin from the viewpoint of heat resistance, dimensional stability, and the like, and particularly preferably a resin having two or more glycidyl groups.

  Moreover, it is preferable that the thickness of a fiber base material is 5-50 micrometers. By using a fiber substrate with such a specific thin thickness, it has even higher flexibility (flexibility), can be bent arbitrarily, and can be printed at high density inside the housing. A circuit board is obtained.

  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 laminate and printed circuit board can have excellent flexibility (flexibility) by being manufactured using the prepreg of the present invention.

  According to the present invention, there are provided a metal foil-clad laminate and a printed circuit board that are sufficiently excellent in flexibility (flexibility) while maintaining high Tg characteristics of the prepreg, and a prepreg capable of obtaining these. The

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings as necessary. In the drawings, the same elements are denoted by the same reference numerals, and redundant description is omitted. Further, the positional relationship such as up, down, left and right is based on the positional relationship shown in the drawings unless otherwise specified. Further, the dimensional ratios in the drawings are not limited to the illustrated ratios.

  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 50 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 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.

  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, tyrano, silicon carbide, silicon nitride, zirconia, and other inorganic fibers, aramid, polyether ether ketone, polyether imide , 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 resin composition constituting the prepreg 100 contains an alicyclic linking group-containing resin having a divalent group represented by the above formula (1). Examples of the resin include a polyimide resin, a polyamideimide resin, and a maleimide resin having a divalent group represented by the above formula (1).

  Among these, the polyimide resin is not particularly limited as long as it has a divalent group represented by the above formula (1). For example, a diamine and a tetracarboxylic acid dianhydride represented by the above formula (2). To an amic acid (amidic acid) having the structure of the above formula (1), followed by dehydration and ring closure. At this time, siloxane diamine, aromatic diamine, and aliphatic diamine can be used in combination. In this case, the total number of moles of the diamine of the above formula (2) and other diamines is preferably equimolar with the tetracarboxylic dianhydride.

  The maleimide resin is not particularly limited as long as it has a divalent group represented by the above formula (1), but the diamine represented by the above formula (2) and maleic anhydride are in a molar ratio of 1 to 2. Can be used by mixing with a triazine compound or other thermosetting resin.

  In the present invention, the alicyclic linking group-containing resin is particularly preferably a polyamideimide resin. 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 polyamide-imide resin is not particularly limited as long as it is a resin composed of a polymer having a divalent group represented by the above formula (1) and having an imide group and an amide group in the main chain. Among them, a polyamideimide resin (siloxane-modified polyamideimide resin) having a divalent group composed of a polysiloxane chain is preferable in that the flexibility of the obtained printed circuit board is increased.

  Such a polyamide-imide resin is, for example, a diamine mixture containing a siloxane diamine, an alicyclic diamine represented by the above formula (2), and an aromatic diamine represented by the above 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 employ | adopting a manufacturing method provided with. The polyamide-imide resin may be synthesized using a 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. preferable.

  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 above formula (2) and the amount b of 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. More preferably.

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

  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.

As R < ⁴ > and R < ⁵ >, the phenyl group which may have a hydrogen atom, a C1-C3 alkyl group, or a substituent is preferable. 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 aromatic ring. 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.

  In addition to this, it is preferable that the resin composition constituting the prepreg 100 further contains a thermosetting 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 a functional group capable of reacting with an amide group in the polyamide-imide resin is preferable.

  The content of the thermosetting resin in the resin composition is preferably 1 to 200 parts by weight, preferably 3 to 100 parts by weight, based on 100 parts by weight of the polyamideimide resin (synonymous with “mass”; the same shall apply hereinafter). It is more preferable that it is 10 to 60 parts by weight. 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 an epoxy resin is used as the thermosetting resin, it is preferable to further contain an epoxy resin curing agent and / or curing accelerator in the resin composition. 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. If the amount of these curing agents or curing accelerators is small, unreacted epoxy resin tends to remain in the substrate and cause a decrease in Tg. If too much, unreacted curing agents and curing accelerators remain. Therefore, the insulation tends to decrease. Further, when the alicyclic linking group-containing resin is a polyamideimide resin, the epoxy group of the epoxy resin can also react with the amide group of the polyamideimide resin, so the amount of the curing agent is set in consideration of this. It is preferable.

  The resin composition 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 solid content in the resin composition. By using such a phosphorus-containing filler, a printed circuit board having a halogen-free and sufficient flame retardancy can be obtained.

  The prepreg 100 includes, for example, an impregnation step of impregnating a fiber base material with a varnish obtained by dissolving or dispersing a resin composition as described above in an organic solvent, and a drying step of removing (drying) the organic solvent. It can produce by the manufacturing method provided. Examples of the organic solvent used for the varnish include dimethyl sulfoxide, N, N-dimethylformamide, γ-butyrolactone, and cyclohexanone. Such an organic solvent may be contained in the prepreg as a residual volatile component, but the amount is preferably 5% 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 composition is 30 to 80% by mass with respect to the total amount of resin solids (varnish resin solids) in the varnish and the fiber base material.

  In the drying 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 resin composition 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.

  The 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. 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 300 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, a crosslinked structure is formed in the cured product of the resin composition 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)
<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
<Solvent of 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 water 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” ( 0.05mol), "Jeffamine D-2000" 72.0g (0. 0 36mol), "Wandamin" 1.3g (0.054mol), TMA80.7g (0.42mol ), and introduced to the reaction NMP589g This was stirred at 80 ° C. for 30 minutes. Then, 150 mL of toluene was added, and then the temperature of the reaction solution was raised and 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 water is being distilled, remove the distillate that has 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>
To 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 .06mol), "JEFFAMINE D-2000" 52.0g (0. 0 26mol), "Wandamin" 11.3g (0.054mol), TMA80.7g (0.42mol ), and the reaction solution was charged NMP575g And stirred at 80 ° C. for 30 minutes. Then, 150 mL of toluene was added, and then the temperature of the reaction solution was raised and 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 water is being distilled, remove the distillate that has 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 3)
<First reaction step>
To 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, 43.0 g of “KF-8010” (0 .05mol), "JEFFAMINE D-2000" 72.0g (0. 0 36mol), "Wandamin" 11.3g (0.054mol), TMA80.7g (0.42mol ), and the reaction solution was charged NMP599g And stirred at 80 ° C. for 30 minutes. Then, 150 mL of toluene was added, and then the temperature of the reaction solution was raised and 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 water is being distilled, remove the distillate that has 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.

Example 1
<Preparation of prepreg and copper clad laminate>
“NC3000” (Nippon Kayaku Co., Ltd., which is a dimethylacetamide solution of 250.0 g of NMP solution of polyamideimide resin (PAI) obtained in Synthesis Example 1 (resin solid content 35 mass%) and epoxy resin (Ep), A mixture of 40.0 g (trade name, resin solid content 50% by mass) and 0.2 g of 2-ethyl-4-methylimidazole was stirred for about 1 hour until uniform. And this liquid mixture was left still at room temperature (25 degreeC) for 24 hours for defoaming, and the varnish was obtained.

  The obtained varnish was impregnated into a glass cloth having a thickness of 28 μm (glass cloth, manufactured by Asahi Sebel Co., Ltd., trade name “1037”), and this was heated at 150 ° C. for 15 minutes to remove the solvent, and resin A prepreg having a composition content of 70% by mass (based on the mass of the entire prepreg) was obtained. A laminated body in which an electrolytic copper foil having a thickness of 12 μm (trade name “F2-WS-12”, manufactured by Furukawa Electric Co., Ltd.) is laminated on both sides of one prepreg so that the adhesive surface thereof is combined with the prepreg, 230 The double-sided copper-clad laminate was obtained by heating and pressing under a press condition of 4.0 MPa at 90 ° C. for 90 minutes.

<Evaluation of copper clad laminate>
The following evaluation was performed about the obtained double-sided laminated board. The results are shown in Table 1.

(1) Copper foil peel strength (copper foil peel strength)
About the obtained double-sided copper clad laminated board, the peeling test of the 90 degree direction was done, and the maximum load at that time was made into copper foil peel strength.

(2) Solder heat resistance (solder resistance at high temperature)
It was immersed in a solder bath heated to 260 ° 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 of the produced double-sided copper clad laminated board 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 break, B: Break

(4) PCT resistance (moisture resistance at high temperature)
A moisture absorption treatment of a pressure cooker test (PCT; saturation condition, 121 ° C., 2 atm) was performed for 1 hour on the laminated plate from which the copper foil on one side of the produced double-sided copper-clad laminate was removed by etching. It was immersed for 20 seconds in a solder bath heated to ° C. Then, the laminated board taken out from the solder bath was observed, and the PCT resistance was evaluated according to the following criteria depending on whether there was an abnormality such as blistering or peeling.
A: No abnormality, B: Abnormal.

(Example 2)
A varnish was obtained in the same manner as in Example 1 except that the NMP solution of the polyamideimide resin obtained in Synthesis Example 2 was used instead of the NMP solution of the polyamideimide resin obtained in Synthesis Example 1. 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 results are shown in Table 1.

(Example 3)
A varnish was obtained in the same manner as in Example 1 except that the NMP solution of the polyamideimide resin obtained in Synthesis Example 3 was used instead of the NMP solution of the polyamideimide resin obtained in Synthesis Example 1. 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 results are shown in Table 1.

(Comparative Example 1)
Instead of the NMP solution of the polyamideimide resin obtained in Synthesis Example 1, an NMP solution of “KS6600” (trade name, manufactured by Hitachi Chemical Co., Ltd.) was used as the polyamideimide resin not having the structure of the above formula (1). Except for this, a varnish was obtained in the same manner as in Example 1. 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 results are shown in Table 1.

  In the case of Examples 1 to 3, the copper foil peel strength (copper foil peel strength) of the double-sided copper-clad laminate is good, showing a high value of 0.8 to 1.0 kN / m, and the solder heat resistance is Abnormalities such as blistering and peeling were not observed for 300 seconds or longer, and the film was excellent in flexibility (flexibility) and could be bent arbitrarily. Furthermore, it was excellent also in solder heat resistance and PCT resistance, and abnormalities such as blistering and peeling were not confirmed.

  On the other hand, in the case of the comparative example 1, the copper foil peel strength of the double-sided copper-clad laminate showed a low value of 0.6 kN / m. Moreover, it was poor in flexibility (flexibility), and was broken when the laminate was folded. Furthermore, solder heat resistance and PCT resistance were also inferior to those of the examples, and abnormalities such as blistering and peeling were observed.

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.

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 (8)

A fiber base material, and a resin composition impregnated therein,
The resin composition contains a polyamideimide resin having a divalent group represented by the following formula (1),
The polyamide-imide resin is a siloxane diamine, an alicyclic diamine represented by the following formula (2), and an aromatic diamine represented by the following general formula (3a) ( an alicyclic represented by the following formula (2)). (Amount of formula diamine) / (amount of aromatic diamine and siloxane diamine represented by the following general formula (3a)) in a molar ratio of 10/90 to 50/50, and a diamine mixture contained therein (however, The aromatic diamine represented by the general formula (3a) is blended in an amount of 30 mol% or more with respect to the diamine mixture.) And the first reaction step in which trimellitic anhydride is reacted to obtain an imide group-containing dicarboxylic acid. When,
A prepreg obtained by a production method comprising: a second reaction step of reacting the imide group-containing dicarboxylic acid with a diisocyanate.

[In Formula (3a), X ¹ represents a sulfonyl 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 methyl group. ]   The prepreg according to claim 1, wherein the aromatic diamine represented by the general formula (3a) is diaminodiphenylsulfone.   The prepreg according to claim 1 or 2, wherein the resin composition further contains a thermosetting resin.   The prepreg according to claim 3, wherein the thermosetting resin is an epoxy resin.   The prepreg according to claim 4, wherein the epoxy resin is a resin having two or more glycidyl groups.   The prepreg as described in any one of Claims 1-5 whose thickness of the said fiber base material is 5-50 micrometers. A substrate obtained by heating and pressurizing a laminate obtained by laminating a predetermined number of the prepregs according to claim 1;
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 7.

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