JP5355858B2 - Multilayer wiring circuit board - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a multilayer wiring circuit board which sufficiently suppresses the occurrence of the breakage or deformation of the wiring circuit board in the course of processing the wiring circuit board to increase the density of the wiring circuit board through thickness reduction. <P>SOLUTION: The multilayer wiring circuit board includes at least two or more polyimide base material layers, and wiring circuit layers each formed at least on one surface of each polyimide base material layer. At least one of the polyimide base material layers is a polyimide resin layer that has a tearing propagation resistance of 100 to 400 mN, and a thermal expansion coefficient of 30&times;10<SP>-6</SP>/K or less. <P>COPYRIGHT: (C)2008,JPO&amp;INPIT

Description

  The present invention relates to a multilayer wiring circuit board, and more particularly to a multilayer wiring circuit board used in electronic information equipment that is required to be reduced in size, weight, and functionality.

  In recent years, with the miniaturization, weight reduction, high functionality, etc. of electronic information equipment, higher density of substrate wiring is required. In addition, a multilayer wiring circuit board in which wiring circuits are formed in multiple layers is known as one of practical means for increasing the density of substrate wiring. For example, Japanese Patent Laid-Open No. 9-92980 (Patent Document 1) discloses a multilayer wiring circuit board having a flexible portion, and such a multilayer wiring circuit board includes one or both sides of a polyimide resin layer. A copper-clad laminate provided with a metal foil such as copper foil is used.

  However, when a multilayer wiring circuit board is manufactured using a copper clad laminate that is currently used in general, if the polyimide resin layer as a base layer is thinned, it is necessary to transport or process the multilayer wiring circuit board. Since the strength of the polyimide resin layer is insufficient, there is a problem that it is difficult to make the polyimide resin layer sufficiently thin, which is one of the factors that hinder the thinning of the multilayer wiring circuit board.

That is, in the conventional multilayer wiring circuit board, since the copper-clad laminate as described above is laminated, the total thickness of the multilayer wiring circuit board is increased, and therefore in the processing process of the multilayer wiring circuit board. It has been difficult to reduce the thickness of the multilayer printed circuit board while sufficiently suppressing the occurrence of breakage and the like.
JP-A-9-92980

  The present invention has been made in view of the above-described problems of the prior art, and it is possible to increase the density by reducing the thickness while sufficiently suppressing the occurrence of breakage and deformation in the processing step of the multilayer printed circuit board. An object of the present invention is to provide a multilayer wiring circuit board.

  As a result of intensive studies to achieve the above object, the present inventors have obtained a multilayer having at least two polyimide base layers and a wiring circuit layer formed on at least one side of the polyimide base layer. In a printed circuit board, by making the polyimide base material layer a polyimide resin layer that satisfies a specific condition, it is possible to increase the density by reducing the thickness while sufficiently suppressing the occurrence of breakage and deformation in the processing process of the multilayer printed circuit board. The present inventors have found that a multilayer wiring circuit board capable of achieving the above can be obtained, and have completed the present invention.

That is, the multilayer wiring circuit board of the present invention includes at least two or more layers of the polyimide substrate layer, wherein possess at least one surface a wiring circuit layers formed of a polyimide base layer, the wiring circuit of at least one layer a multilayer printed circuit board layers Ru disposed between the polyimide base layer of two layers, at least one layer of the polyimide substrate layer, tear propagation resistance 100 is measured by the thickness 26μm It is in the range of 400 mN , the thermal expansion coefficient is 30 × 10 ⁻⁶ / K or less , the thickness is in the range of 5 to 35 μm, and the following general formula (1):
(In the formula (1), R represents a lower alkyl group having 1 to 6 carbon atoms, a phenyl group or a halogen, and l represents an existing molar ratio.)
It is a polyimide resin layer which has as a main polyimide layer the polyimide resin layer (A) which has the structural unit represented by 50 mol% or more .

In the multilayer printed circuit board of the present invention, the polyimide base material layer has a tear propagation resistance measured at a thickness of 26 μm in the range of 100 to 400 mN and a thermal expansion coefficient of 30 × 10 ⁻⁶ / K. The following polyimide resin layers are preferable.

  Furthermore, in the multilayer wiring circuit board of the present invention, it is preferable that the polyimide resin layer has a thickness in the range of 10 to 30 μm.

  Moreover, it is preferable that the multilayer wiring circuit board of this invention is obtained using the flexible laminated board which has the said polyimide resin layer and the conductor layer laminated | stacked on the at least single side | surface of the said polyimide resin layer.

  ADVANTAGE OF THE INVENTION According to this invention, it becomes possible to provide the multilayer wiring circuit board which can aim at the density increase by thinning, fully suppressing generation | occurrence | production of the fracture | rupture and deformation | transformation in the manufacturing process of a multilayer wiring circuit board. .

  Hereinafter, the present invention will be described in detail with reference to preferred embodiments thereof.

  First, the multilayer wiring circuit board of the present invention will be described. That is, the multilayer printed circuit board of the present invention has at least two or more polyimide substrate layers and a wired circuit layer formed on at least one surface of the polyimide substrate layer.

In the present invention, at least one of the polyimide base layers is a polyimide resin having a tear propagation resistance in the range of 100 to 400 mN and a thermal expansion coefficient of 30 × 10 ⁻⁶ / K or less. It needs to be a layer. Thus, by making at least one layer of the polyimide base material layer a polyimide resin layer according to the present invention that satisfies the above-mentioned conditions, the occurrence of breakage and deformation in the processing process of the multilayer wiring circuit board is sufficiently achieved. While suppressing, it becomes possible to achieve high density by thinning. That is, by setting the tear propagation resistance of the polyimide base layer in the range of 100 to 400 mN, even when the thickness of the polyimide base layer is thin, the breakage and deformation in the processing step of the multilayer wiring circuit board are sufficiently suppressed. It becomes possible. In addition, by setting the thermal expansion coefficient of the polyimide base material layer to 30 × 10 ⁻⁶ / K or less, it becomes possible to control the deformation of the multilayer wiring circuit board, such as curling, and to improve the dimensional stability. Is possible. Furthermore, in the present invention, the tear propagation resistance of the polyimide base layer is 130 to 350 mN from the viewpoint of further reducing the thickness while sufficiently suppressing the occurrence of breakage and deformation in the processing step of the multilayer wiring circuit board. The thermal expansion coefficient is preferably 25 × 10 ⁻⁶ / K or less. It should be noted that the tear propagation resistance and the thermal expansion coefficient can be measured by the methods described in the examples described later.

Moreover, in this invention, it is preferable that such a polyimide base material layer is a polyimide resin layer whose tear propagation resistance is in the range of 100 to 400 mN and whose thermal expansion coefficient is 30 × 10 ⁻⁶ / K or less. . Thus, if all the polyimide base material layers which comprise the multilayer wiring circuit board of this invention are the polyimide resin layers concerning this invention, the multilayer wiring circuit board can be made still thinner. In addition, as the number of polyimide base layers constituting the multilayer wiring circuit board of the present invention increases, the effect of the present invention for reducing the thickness of the multilayer wiring circuit board tends to increase.

  Although the polyimide resin layer concerning this invention needs to satisfy | fill the above specific conditions, as such a polyimide resin layer, the polyimide resin layer (A) which is demonstrated below is mainly used. What has as a polyimide layer is mentioned. In this specification, the main polyimide layer means a layer having a thickness of 60% or more of the total thickness of the polyimide resin layer, preferably a layer having a thickness of 80% or more, more preferably 90% or more. .

Here, the polyimide resin layer (A) preferably a structural unit represented by the before following general formula (1) are those having a ratio of more than 50 mol%.

  In General formula (1), R shows a C1-C6 lower alkyl group, a phenyl group, or a halogen. Moreover, l shows the presence molar ratio of the structural unit represented by General formula (1) in a polyimide resin layer (A). Furthermore, as a more preferable example of the structural unit represented by the general formula (1), a structural unit represented by the following general formula (2) is exemplified.

  Such a polyimide resin layer (A) has at least one structure of the structural units represented by the following general formulas (3) and (4) together with the structural unit represented by the general formula (1). It is more preferable that the unit is contained within a certain range.

In the general formula (3), Ar ₁ represents a divalent aromatic group represented by the following general formula (a) and / or (b). Furthermore, in the following general formulas (a) and (b), Ar ₃ represents a divalent aromatic group represented by the following structural formula (c) and / or (d). The preferable examples of Ar ₁ represented by the following structural formula (e), is exemplified divalent aromatic group represented by (f) and (g). In the general formula (4), Ar ₂ represents at least one group selected from the group consisting of divalent residues of 3,4′-diaminodiphenyl ether and 4,4′-diaminodiphenyl ether. Furthermore, in General formula (3) and (4), m and n show the molar ratio of the structural unit represented by General formula (3) and (4) in a polyimide resin layer (A), respectively.

  And when such a polyimide resin layer (A) contains the structural unit represented by the said General formula (1) and (3), l is the range of 0.6-0.9, m is 0. Preferably it is in the range of 1 to 0.4. Moreover, when such a polyimide resin layer (A) contains the structural units represented by the general formulas (1), (3) and (4), l is in the range of 0.6 to 0.9. , M is preferably in the range of 0.1 to 0.3, and n is preferably in the range of 0.01 to 0.2.

  The structural unit represented by the general formula (1) mainly improves properties such as low thermal expansion and high heat resistance, and the structural unit represented by the general formula (3) mainly includes toughness and adhesiveness. It is presumed that this property is improved, but it is not necessarily clear because of the synergistic effect and the influence of molecular weight. Moreover, there exists a tendency for the toughness etc. of a polyimide resin layer to improve by increasing the existing molar ratio m of the structural unit of the said General formula (3). Furthermore, the structural unit of the general formula (4) is effective for adjusting the balance between low thermal expansion and toughness of the polyimide resin layer.

  The polyimide resin constituting such a polyimide resin layer (A) is preferably obtained by imidizing a polyimide precursor resin having a weight average molecular weight of 150,000 to 800,000, more preferably 200,000 to 800,000. Is. If the value of the weight average molecular weight is less than 150,000, the tear propagation resistance of the polyimide resin layer (film) tends to be weak, whereas if it exceeds 800,000, it may be difficult to form a uniform polyimide resin layer. In addition, the weight average molecular weight can obtain | require the value of polystyrene conversion by GPC method. Moreover, since the weight average molecular weight of the polyimide resin obtained by imidizing the polyimide precursor resin is almost the same as that measured in the polyimide precursor resin state, the weight average molecular weight of the polyimide resin is equal to the weight average molecular weight of the polyimide precursor resin. Can be considered.

  The polyimide resin layer according to the present invention may be composed of a single layer, but the polyimide resin layer (A) as a main layer is another layer for improving adhesiveness with a wiring circuit layer or a conductor layer. You may have a polyimide resin layer. The total thickness of such polyimide resin layers is preferably in the range of 5 to 40 μm, more preferably 5 to 35 μm, still more preferably 10 to 30 μm, and particularly preferably 10 to 25 μm. Moreover, the thickness ratio of the polyimide resin layer (A) with respect to the total thickness of the polyimide resin layer is as described above, and by setting it in such a range, a flexible laminate having an excellent balance between tear strength and flexibility is obtained. be able to.

  Moreover, the polyimide resin layer concerning this invention can also be formed by multiple layers as mentioned above. A polyimide resin constituting the polyimide resin layer (A) and other polyimide resin layers other than the polyimide resin layer (A) is obtained by polymerizing raw material diamine and acid anhydride in the presence of a solvent to obtain a polyimide precursor resin. Thereafter, it can be produced by imidization by heat treatment. Examples of the solvent include dimethylacetamide, dimethylformamide, n-methylpyrrolidinone, 2-butanone, diglyme, xylene and the like, and they can be used alone or in combination of two or more.

Examples of the diamine which is a polyimide resin raw material constituting another polyimide resin layer include compounds represented by the general formula: H ₂ N—Ar ₄ —NH ₂ , and Ar ₄ is listed in the following formula (5). An aromatic diamine residue represented by the structural formula is exemplified.

  Among these diamines, 4,4′-diaminodiphenyl ether (4,4′-DAPE), 1,3-bis (4-aminophenoxy) benzene (TPE-R), 1,3-bis (3-aminophenoxy) ) Benzene (APB) and 2,2-bis (4-aminophenoxyphenyl) propane (BAPP) are preferred examples.

The acid anhydride comprising the polyimide resin material which constitutes the other of the polyimide resin layer, the general _{formula: O (OC) 2 Ar 5} (CO) a compound represented by the _{2 O} and the like, following the Ar ₅ Illustrative are the aromatic dianhydride residues represented by the structural formula listed in formula (6).

  Among these acid anhydrides, pyromellitic dianhydride (PMDA), 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride (BPDA), 3,3 ′, 4,4′-benzophenone Preferred examples include tetracarboxylic dianhydride (BTDA) and 3,3 ′, 4,4′-diphenylsulfone tetracarboxylic dianhydride (DSDA).

  In addition, depending on the combination of the diamine and the acid anhydride, the structural unit represented by the general formula (1), (3) or (4) may be given. It is not a polyimide resin raw material that constitutes the layer.

  Moreover, as a combination of the diamine and the acid anhydride which are the polyimide resin raw materials constituting the polyimide resin layer (A), it is understood from the explanation of the general formulas (1), (3) and (4). There are TPE-R, APB, 4,4′-DAPE, and the acid anhydride is PMDA. And as a diamine used as the polyimide resin raw material which comprises a polyimide resin layer (A), and an acid anhydride, what has the structural unit represented by the said General formula (1) in the ratio of 50 mol% or more is obtained. Two or more diamines and acid anhydrides may be used, and other diamines may be used.

  Furthermore, the molecular weight of the polyimide resin can be mainly controlled by changing the molar ratio of the raw material diamine and acid anhydride. The molar ratio is usually 1: 1. In addition, the polyimide resin which comprises a polyimide resin layer (A) is obtained by imidating the precursor (solution). When a highly adhesive polyimide resin layer is used as the other polyimide resin layer, such other polyimide resin layer is provided so as to be in contact with a conductor layer such as a copper foil serving as a wiring circuit layer. The resin layer (A) is preferably provided so as to be in contact with another polyimide resin layer.

  The polyimide resin layer according to the present invention is a polyimide resin layer formed by coating the polyimide precursor resin solution on an arbitrary supporting substrate, drying and heat-treating, and then peeling the polyimide film from the supporting substrate. Alternatively, the polyimide precursor resin solution may be directly coated on a conductor layer such as a copper foil to be a wiring circuit layer of the flexible laminate, and dried and heat-treated to obtain a flexible laminate. Considering the ease of application of the present invention to a multilayer wiring circuit board, the latter is advantageous in the present invention. In addition, when only a polyimide film is manufactured in advance, it is necessary to provide a conductor layer such as a copper foil later on the polyimide film, and a known method can be applied as this method. For example, a so-called laminating method in which a polyimide film and a metal foil such as a copper foil are heat-bonded is generally used. In this case, a polyimide-based adhesive resin is interposed without using an adhesive layer such as an epoxy resin. It is good.

  The wiring circuit layer according to the present invention is formed on at least one side of the polyimide base layer as described above. Such a wiring circuit layer is formed by subjecting a conductor layer such as a metal foil to a known circuit formation process.

  Examples of such metal foils include conductive metals such as copper, aluminum, iron, silver, palladium, nickel, chromium, molybdenum, tungsten, zinc, and alloys thereof. Among these, stainless steel, copper An alloy copper foil containing 90% or more of foil or copper is preferable. The thickness of the metal foil is preferably in the range of 10 to 18 μm. When the thickness of the metal foil is less than 10 μm, it is not preferable because it is difficult to obtain a metal as a raw material, handling properties at the time of manufacturing the laminated body are deteriorated, and wrinkles are easily generated at the manufacturing of the laminated body. On the other hand, when the thickness of the metal foil exceeds 18 μm, it is difficult to form good fine wiring in circuit processing, and productivity is inferior in view of chemical etching performed as necessary.

  In recent years, it has been desired to further reduce the thickness of the copper foil due to the demand for fine patterns, etc., but in order to satisfy such a demand, after making the flexible copper clad laminate, It can also be thinned by chemical polishing uniformly with an etchant, and instead of copper foil, a so-called ultra-thin copper foil with a carrier consisting of a carrier, a release layer, and an ultra-thin copper foil is used. The polyimide resin may be formed on the foil, and the carrier may be removed to form a thin copper foil layer.

  The multilayer wiring circuit board of the present invention has a plurality of polyimide base material layers and wiring circuit layers as described above, and the polyimide resin layer and a conductor layer laminated on at least one side of the polyimide resin layer. It is preferable that it is obtained using the flexible laminated board which has.

  Such a flexible laminate may be a single-sided flexible laminate having a metal foil only on one side of the polyimide resin layer, and a double-sided flexible laminate having a metal foil on both sides of the polyimide resin layer. It may be a plate. Moreover, in order to set it as a double-sided flexible laminated board, after manufacturing a single-sided flexible laminated board, it can manufacture by preparing new copper foil and the ultra-thin copper foil with a carrier, and heat-pressing. In addition, the flexible laminated board which has ultra-thin copper foil on both surfaces of an insulating layer can be manufactured by using ultra-thin copper foil with a carrier.

  Next, a method for producing the multilayer wiring circuit board of the present invention using the flexible laminate will be described with reference to the drawings.

  FIG. 1 is a process schematic diagram showing a preferred embodiment of a method for producing a multilayer wiring circuit board of the present invention. And the multilayer wiring circuit board of this invention is a process (lamination process) which laminates | stacks a single-sided flexible laminated board on the said wiring board, for example, the process of producing a wiring board using a double-sided flexible laminated board (wiring board preparation process). And a step of conducting the wiring circuit of the wiring board and the copper foil of the single-sided flexible laminate (conducting step), and forming the wiring circuit by subjecting the copper foil of the single-sided flexible laminate to a wiring circuit. And a step of forming a protective layer on the circuit (outer layer forming step). 1A corresponds to a wiring board manufacturing process, FIG. 1B corresponds to a lamination process, FIG. 1C corresponds to a conduction process, and FIG. 1D corresponds to an outer layer formation process. Correspond.

  In the wiring board manufacturing step, first, a double-sided flexible laminate having copper foil on both sides of the polyimide resin layer (polyimide substrate layer 1) is prepared. Thereafter, via holes 3 are formed at predetermined positions of the double-sided flexible laminate. A known method can be applied as a method for forming the via hole, but a method of opening with a laser is preferable. And in order to make the copper foil of a double-sided flexible laminated board conduct | electrically_connect in the formation part of the via hole 3, it fills with an electroconductive substance. As a method of filling the conductive material in this manner, a method of filling the via hole with plated copper by performing electroless plating and electrolytic plating after forming the via hole can be applied. Further, a known conductive paste may be applied.

  In the wiring board manufacturing step, next, a circuit forming process is performed on the copper foil of the double-sided flexible laminate to manufacture the wiring board 10. As a method of the circuit formation process, a known method can be appropriately employed. In this way, a wiring substrate 10 having a polyimide base layer 1 and a wiring circuit 2 ′ formed on both surfaces of the polyimide base layer 1 as shown in FIG. In the wiring board 10 shown in FIG. 1A, the wiring circuits 2 ′ formed on both surfaces of the polyimide base layer 1 are electrically connected to each other by the plated copper filled in the via hole 3.

  In the lamination step, first, a single-sided flexible laminate 11 having a copper foil 6 on one side of the polyimide resin layer (polyimide substrate layer 5) is prepared. Since such single-sided flexible laminates 11 are provided on both sides of the wiring board 10, at least two are prepared. And as shown in FIG.1 (b), the wiring board 10 and the two single-sided flexible laminated boards 11 are made to oppose so that the copper foil 6 of the flexible laminated board 11 may respectively become an outer side, Laminate.

  The adhesive 4 is not particularly limited, but is preferably one having high heat resistance and no dimensional change, such as an epoxy resin adhesive, a polyimide resin adhesive, a siloxane-modified polyimide resin adhesive, and an acrylic. A system adhesive is illustrated, Preferably a film-like adhesive film is applied.

  Moreover, the method of laminating in this way is not particularly limited, and a method of using a laminating apparatus such as a normal press or laminator can be employed. Moreover, as for lamination | stacking conditions, it is desirable to set it as the range of the temperature of 150-180 degreeC, the pressure of 2-4 MPa, and the holding time of 60-90 minutes. Although not shown in FIG. 1, cover lay films may be provided on both sides of the wiring board 10 as necessary. As such a coverlay film, a coverlay film in which an epoxy resin adhesive or an acrylic resin adhesive is provided on a polyimide film is preferably used.

  In the conduction step, first, the via hole 3 is formed at a predetermined position of the single-sided flexible laminated plate 11 laminated on the wiring board 10. Then, in order to make the wiring circuit 2 ′ of the wiring substrate 10 and the copper foil 6 of the single-sided flexible laminate 11 conductive in the formation portion of the via hole 3, a conductive substance is filled. As the method for forming the via hole and the method for filling the conductive material, the method as described above can be adopted. In this way, as shown in FIG. 1C, the wiring circuit 2 ′ of the wiring substrate 10 and the copper foil 6 of the single-sided flexible laminate 11 can be made conductive by the via hole 3.

  In the outer layer forming step, as shown in FIG. 1 (d), the copper foil 6 of the single-sided flexible laminate 11 is subjected to a circuit forming process to form a wiring circuit 6 ', and then a cover layer as a protective layer on the wiring circuit 6'. The film 7 is laminated. As a method of the circuit formation process, a known method can be appropriately employed. As the cover lay film 7, a cover lay film in which an epoxy resin adhesive or an acrylic resin adhesive is provided on a polyimide film is preferably used.

  The multilayer wiring circuit board 12 of the present invention can be manufactured by the method including the wiring board manufacturing process, the laminating process, the conduction process, and the outer layer forming process as described above. Further, in the method of manufacturing the multilayer wiring circuit board of the present invention, the method of manufacturing the multilayer wiring circuit board having four wiring circuit layers has been described as an example. Thus, for example, a multilayer wiring circuit board having six or eight wiring circuit layers can be provided. In this case, the coverlay film 7 is preferably used only for protecting the outermost wiring circuit layer.

  In the above embodiment, the multilayer wiring circuit board having no hinge portion that can be repeatedly bent has been described as an example. However, a single-layer or multiple-layer flexible wiring board is formed as a part of the multilayer wiring circuit board. It is good also as a multilayer wiring circuit board (multilayer hinge board | substrate) which has the hinge part which consists of.

  FIG. 2 is a schematic cross-sectional view showing a periphery of a hinge part of a multilayer wiring circuit board (multilayer hinge board) having a hinge part. The multilayer printed circuit board shown in FIG. 2 has a polyimide base layer 1, a wiring circuit 2 ′ formed on one side of the polyimide base layer 1, and a coverlay film 7 laminated on the wiring circuit 2 ′. Double-sided flexible wiring having single-sided flexible wiring board 13, polyimide base material layer 1, wiring circuit 2 'formed on both surfaces of polyimide base material layer 1, and coverlay film 7 laminated on wiring circuit 2' A substrate 14 is provided. In the multilayer wiring circuit board shown in FIG. 2, a space is formed between the flexible wiring boards at the hinge part, and the flexible wiring board is bonded to the adhesive at a part other than the hinge part. 4 is joined.

  EXAMPLES Hereinafter, although this invention is demonstrated more concretely based on an Example and a comparative example, this invention is not limited to a following example. In addition, the tear propagation resistance and thermal expansion coefficient (CTE) of the polyimide resin layer were measured by the following methods, respectively. Moreover, in such a measurement, the polyimide film obtained by carrying out the etching removal of the copper foil from the flexible laminated board used in the Example was used.

(I) Measurement of tear propagation resistance A polyimide film (63.5 mm x 50 mm) was prepared, and a 12.7 mm length cut was made into this polyimide film, and a light load tear tester made by Toyo Seiki It measured using.

(Ii) Measurement of coefficient of thermal expansion (CTE) Using a polyimide film (3 mm × 15 mm) as a test piece, a thermomechanical analysis (TMA) apparatus was used, and a constant heating rate was applied from 30 ° C. to 260 ° C. while applying a 5 g load. A tensile test was conducted in the temperature range of ° C. And the thermal expansion coefficient was computed from the amount of elongation of the polyimide film with respect to temperature.

(Synthesis Example 1)
In order to produce the polyimide resin layer of the flexible laminate used for producing the multilayer wiring circuit board of the present invention, a polyimide precursor a was produced as follows. That is, first, under a nitrogen stream, 69 g of 4,4′-diamino-2,2′-dimethylbiphenyldiamine (m-TB), 1,3-bis (4-aminophenoxy) benzene (TPE-R) as a diamine component. ) 29 g and 3,4'-diaminodiphenyl ether (3,4'-DAPE) 15 g were dissolved in about 250 to 300 g of the solvent N, N-dimethylacetamide (DMAc) while stirring in a 500 ml separable flask. Next, 110 g of pyromellitic dianhydride (PMDA) was added as a tetracarboxylic acid component. Thereafter, the solution was stirred at room temperature for 4 hours to carry out a polymerization reaction to obtain a yellowish brown viscous solution of polyimide precursor resin a. The viscosity of the obtained polyimide precursor resin solution at 25 ° C. was 43,000 mPa · s, and the weight average molecular weight (Mw) was 200,000. The viscosity was measured using a cone plate viscometer (manufactured by Tokimec Co., Ltd.) equipped with a thermostatic water tank, and the weight average molecular weight (Mw) was measured using GPC.

(Synthesis Example 2)
In order to produce the polyimide resin layer of the flexible laminate used for producing the multilayer wiring circuit board of the present invention, a polyimide precursor b was produced as follows. That is, first, under a nitrogen stream, as a diamine component, 2,2-bis (4-aminophenoxyphenyl) propane (BAPP) 87 g, 4,4′-diamino-2,2′-dimethylbiphenyldiamine (m-TB) 3) and 2 g of 4,4′-diaminodiphenyl ether (4,4′-DAPE) were dissolved in about 250 to 300 g of solvent DMAc while stirring in a 500 ml separable flask. Next, 46 g of pyromellitic dianhydride (PMDA) was added as a tetracarboxylic acid component. Thereafter, the solution was continuously stirred at room temperature for 4 hours to carry out a polymerization reaction, thereby obtaining a yellowish brown viscous solution of polyimide precursor resin b. The viscosity of the obtained polyimide precursor resin solution at 25 ° C. was 15000 mPa · s, and the weight average molecular weight (Mw) was 170,000.

(Production Example 1)
First, the solution of the polyimide precursor resin a obtained in Synthesis Example 1 is uniformly applied on an electrolytic copper foil having a thickness of 12 μm using an applicator so that the thickness after curing is 24.4 μm. The solvent was removed by heating and drying at 70 to 130 ° C. Thereafter, the solution of the polyimide precursor resin b obtained in Synthesis Example 2 was uniformly applied onto the dried film so that the thickness after curing was 1.6 μm, and the solvent was removed by heating at 130 ° C. . And after drying for 2 to 60 minutes at 50 to 130 ° C., further performing stepwise heat treatment for 2 to 30 minutes each at 130 ° C., 160 ° C., 200 ° C., 230 ° C., 280 ° C., 320 ° C., 360 ° C., A polyimide layer having a total thickness of 26 μm is formed by forming a polyimide layer on a copper foil, and comprising two layers of a layer (a) using the polyimide precursor resin a as a raw material and a layer (b) using the polyimide precursor resin b as a raw material. Obtained the laminated body for flexible laminated boards formed on copper foil. The thickness of each polyimide resin layer on the copper foil was 24.4 μm / 1.6 μm in the order of a / b. Thereafter, the copper foil was thinned to 8 μm by etching using a hydrogen peroxide / sulfuric acid based etching solution to obtain a single-sided flexible laminate. When the tear propagation resistance and thermal expansion coefficient of the polyimide resin layer were measured using a polyimide film obtained by etching away the copper foil from the obtained flexible laminate, the tear propagation resistance was 180 mN, and the thermal expansion The coefficient was 21 × 10 ⁻⁶ / K.

(Production Example 2)
First, a solution of the polyimide precursor resin b obtained in Synthesis Example 2 is uniformly applied onto an electrolytic copper foil having a thickness of 12 μm so that the thickness after curing is 1.6 μm, and is 70 to 130 ° C. And dried by heating to remove the solvent. Next, the polyimide precursor resin a solution obtained in Synthesis Example 1 is uniformly applied using an applicator so that the thickness after curing is 22.8 μm, and is heated and dried at 70 to 130 ° C. The solvent was removed. Furthermore, the solution of the polyimide precursor resin b obtained in Synthesis Example 2 was uniformly applied so that the thickness after curing was 1.6 μm, and dried by heating at 130 ° C. to remove the solvent. And after drying for 2 to 60 minutes at 50 to 130 ° C., further performing stepwise heat treatment for 2 to 30 minutes each at 130 ° C., 160 ° C., 200 ° C., 230 ° C., 280 ° C., 320 ° C., 360 ° C., A polyimide resin layer having a total thickness of 26 μm is formed by forming a polyimide layer on a copper foil, and comprising three layers of a layer (a) using the polyimide precursor resin a as a raw material and a layer (b) using the polyimide precursor resin b as a raw material. Obtained the laminated body for flexible laminated boards formed on copper foil. The thickness of each polyimide resin layer on the copper foil was 1.6 μm / 22.8 μm / 1.6 μm in the order of b / a / b. Next, the polyimide resin layer of the obtained laminate for a flexible laminate and an electrolytic copper foil having a thickness of 12 μm are heat-pressed using a laminator, and then copper is added using a hydrogen peroxide / sulfuric acid-based etching solution. The foil was thinned to 8 μm by etching to obtain a double-sided flexible laminate. When the tear propagation resistance and thermal expansion coefficient of the polyimide resin layer were measured using a polyimide film obtained by etching away the copper foil from the obtained flexible laminate, the tear propagation resistance was 175 mN, and the thermal expansion The coefficient was 21 × 10 ⁻⁶ / K.

Example 1
After preparing the double-sided flexible laminate obtained in Production Example 2 and forming the via hole 3 at a predetermined position, the via hole is filled with plated copper by ordinary electroless plating and electrolytic plating, and the copper foil of the double-sided flexible laminate is obtained. Conducted each other. Thereafter, the copper foil of the double-sided flexible laminate is subjected to a circuit formation process to form an arbitrary wiring circuit 2 ′, and wiring having wiring circuits 2 ′ on both sides of the polyimide base layer as shown in FIG. A substrate 10 was obtained.

  Next, two single-sided flexible laminates 11 obtained in Production Example 1 are prepared, and the wiring board 10 and the two single-sided flexible laminates 11 are arranged so that the copper foils 6 of the flexible laminates 11 are respectively outside. It was made to oppose and it laminated | stacked through the adhesive agent 4 (refer FIG.1 (b)). Note that the lamination conditions at this time were a temperature of 160 ° C., a pressure of 3 MPa, and a holding time of 60 minutes.

  Next, the via hole 3 is formed at a predetermined position of the single-sided flexible laminate 11 laminated on the wiring substrate 10 and filled with the via hole in the same manner as described above, and the wiring circuit 2 ′ and the single-sided flexible laminate 11 of the wiring substrate 10 are filled. The copper foil 6 was made conductive (see FIG. 1C).

  Next, the copper foil 6 of the single-sided flexible laminate 11 is subjected to a circuit formation process to form an arbitrary wiring circuit 6 ', and finally a coverlay film 7 for circuit protection is laminated to form four wiring circuit layers. A multilayer wiring circuit board 12 of the present invention having the above was obtained (see FIG. 1 (d)).

  As described above, according to the present invention, there is provided a multilayer wiring circuit board capable of achieving high density by thinning while sufficiently suppressing the occurrence of breakage and deformation in the processing process of the multilayer wiring circuit board. It becomes possible to do.

  Therefore, the multilayer wiring circuit board of the present invention is useful as a multilayer wiring circuit board used for electronic information equipment that is required to be reduced in size, weight, and functionality.

FIG. 1 is a process schematic diagram showing a preferred embodiment of a method for producing a multilayer wiring circuit board of the present invention (FIG. 1A corresponds to a wiring board manufacturing process, and FIG. 1B corresponds to a lamination process. FIG. 1C corresponds to the conduction process, and FIG. 1D corresponds to the outer layer formation process. 1 is a schematic cross-sectional view showing a peripheral portion of a hinge part of a multilayer wiring circuit board (multilayer hinge board) having a hinge part which is a preferred embodiment of the multilayer wiring circuit board of the present invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Polyimide base material layer, 2 '... Wiring circuit, 3 ... Via hole, 4 ... Adhesive, 5 ... Polyimide base material layer, 6 ... Copper foil, 6' ... Wiring circuit, 7 ... Coverlay film, 10 ... Wiring board DESCRIPTION OF SYMBOLS 11 ... Single-sided flexible laminated board, 12 ... Multi-layer wiring circuit board, 13 ... Single-sided flexible wiring board, 14 ... Double-sided flexible wiring board.

Claims (4)

And at least two layers of polyimide substrate layer, wherein possess at least one surface a wiring circuit layers formed of a polyimide base layer, the wiring circuit layers at least one layer of two layers of the polyimide substrate layer a multilayer printed circuit board that will be placed between the at least one layer of the polyimide substrate layer is in the range propagation resistance of 100~400mN tear as measured at a thickness of 26 .mu.m, the thermal expansion coefficient of 30 × 10 ⁻⁶ / K or less , the thickness is in the range of 5 to 35 μm, and the following general formula (1):
(In the formula (1), R represents a lower alkyl group having 1 to 6 carbon atoms, a phenyl group or a halogen, and l represents an existing molar ratio.)
A multilayer wiring circuit board comprising a polyimide resin layer (A) having a structural unit represented by 50% by mole or more as a main polyimide layer . The polyimide base material layer is a polyimide resin layer having a tear propagation resistance measured in a thickness of 26 μm in a range of 100 to 400 mN and a thermal expansion coefficient of 30 × 10 ⁻⁶ / K or less. The multilayer wiring circuit board according to claim 1.   The multilayer wiring circuit board according to claim 1, wherein the polyimide resin layer has a thickness in a range of 10 to 30 μm.   It is obtained using the flexible laminated board which has the said polyimide resin layer and the conductor layer laminated | stacked on the at least single side | surface of the said polyimide resin layer, The any one of Claims 1-3 characterized by the above-mentioned. A multilayer printed circuit board according to Item.