JP2023036706A - Method for manufacturing multilayer circuit board - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a multilayer circuit board which is excellent in dimensional stability of a conductor circuit, and has an adhesive layer capable of reducing transmission loss even in transmission of a high frequency signal, and a method for manufacturing the same.

SOLUTION: A circuit board 101 includes an insulation resin layer 10, a conductor circuit layer 50 laminated on one surface of the insulation resin layer, and an adhesive layer 30 laminated on the other surface of the insulation resin layer. A resin constituting the adhesive layer is adhesive polyimide containing 50 parts by mol or more of a diamine residue derived from dimer acid type diamine obtained by substituting two terminal carboxylic acid groups of a dimer acid for a primary aminomethyl group or amino group, with respect to 100 parts by mol of the total amount of a diamine residue. A multilayer circuit board 200 is manufactured by collectively pressure-bonding an adhesive layer of a first circuit board 101 facing a conductor circuit layer of a second circuit board 101, and an adhesive layer of the second circuit board 101 facing a conductor circuit layer of an arbitrary circuit board 110 having no adhesive layer in an overlapping manner.

SELECTED DRAWING: Figure 4

COPYRIGHT: (C)2023,JPO&INPIT

Description

TECHNICAL FIELD The present invention relates to a metal-clad laminate, a circuit board, a multilayer circuit board having a plurality of laminated conductor circuit layers, and a method for producing the same.

In recent years, with the development of high-density and high-performance electronic devices, circuit board materials with further dimensional stability and excellent high-frequency characteristics are in demand. In particular, low dielectric constant and low dielectric loss are important characteristics of organic interlayer insulating materials required for high-speed signal processing. In order to cope with higher frequencies, a multilayer wiring board has been proposed in which a liquid crystal polymer (LCP) having a low dielectric constant and a low dielectric loss tangent is used as a dielectric layer (for example, Patent Document 1). A multilayer wiring board with a liquid crystal polymer as an insulating layer is manufactured by thermocompression bonding in a state where the liquid crystal polymer base material, which is a thermoplastic resin, is heated to near the melting point. positional deviation is likely to occur, and there is concern that electrical characteristics such as impedance mismatch may be adversely affected. In addition, in a multi-layer wiring board using a liquid crystal polymer as a base layer, if the multi-layer adhesion interface is smooth, the anchor effect will not be exhibited and the interlayer adhesion will be insufficient. There is also the problem that roughening treatment is required in the first step, and the manufacturing process is complicated.

By the way, as a technology related to an adhesive layer having polyimide as a main component, there are polyimides made from diamine compounds derived from aliphatic diamines such as dimer acid, and amino compounds having at least two primary amino groups as functional groups. is applied to the adhesive layer of the coverlay film (for example, Patent Document 2). The crosslinked polyimide resin of Patent Document 2 does not generate a volatile component composed of a cyclic siloxane compound, has excellent soldering heat resistance, and maintains the adhesive strength between the wiring layer and the coverlay film even in an environment where it is repeatedly exposed to high temperatures. It has the advantage of not deteriorating. However, Patent Document 2 does not consider applicability to high-frequency signal transmission.

JP-A-2005-317953 Japanese Unexamined Patent Application Publication No. 2013-1730

In the future, as one direction for multi-layer circuit boards to support high-frequency signal transmission, dielectric properties can be improved by increasing the total thickness of insulating resin layers and adhesive layers while maintaining the dimensional stability of conductor circuits. Improvements can be considered. For this reason, in metal-clad laminates and circuit boards, which are materials for multilayer circuit boards, design concepts different from conventional multilayer circuit boards have been required not only in terms of materials but also in structure.

SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to provide a multi-layer circuit board having a novel structure in which the dimensional stability of the conductor circuit is excellent and the transmission loss can be reduced even in the transmission of high-frequency signals.

As a result of intensive research, the present inventors have found that by using a metal-clad laminate with a specific structure as a material for a multilayer circuit board, while maintaining excellent adhesiveness and dimensional stability of the conductor circuit, The inventors have found that it is possible to cope with the transmission of high-frequency signals, and completed the present invention.

That is, the metal-clad laminate of the present invention comprises an insulating resin layer, a metal layer laminated on one side of the insulating resin layer, and an adhesive layer laminated on the other side of the insulating resin layer. I have.
Further, the circuit board of the present invention includes an insulating resin layer, a conductor circuit layer formed on one surface of the insulating resin layer, and an adhesive layer laminated on the other surface of the insulating resin layer. ing.
In the metal-clad laminate or circuit board of the present invention, the resin constituting the adhesive layer is a thermoplastic resin or a thermosetting resin, and the following conditions (i) to (iii);
(i) a storage modulus at 50°C of 1800 MPa or less;
(ii) the maximum value of storage modulus in the temperature range from 180°C to 260°C is 800 MPa or less;
(iii) having a glass transition temperature (Tg) of 180° C. or less;
It satisfies

In the metal-clad laminate or circuit board of the present invention, the thermoplastic resin may be an adhesive polyimide containing a tetracarboxylic acid residue and a diamine residue. In this case, the adhesive polyimide is a dimer acid-type diamine obtained by substituting two terminal carboxylic acid groups of a dimer acid with a primary aminomethyl group or an amino group with respect to the total amount of 100 mol parts of the diamine residue. It may contain 50 mol parts or more of diamine residues derived from.

The metal-clad laminate of the present invention may be a material for a circuit board formed by processing the metal layer into wiring.

In the metal-clad laminate or circuit board of the present invention, the adhesive polyimide is represented by the following general formulas (1) and/or (2) with respect to 100 mol parts of the total amount of the tetracarboxylic acid residue. It may contain a total of 90 mol parts or more of tetracarboxylic acid residues derived from tetracarboxylic anhydride.

In general formula (1), X represents a single bond or a divalent group selected from the following formula, and in general formula (2), the cyclic portion represented by Y is a 4-membered ring, a 5-membered ring , represents that a saturated cyclic hydrocarbon group selected from a 6-, 7-, or 8-membered ring is formed.

In the above formula, Z represents -C ₆ H ₄ -, -(CH ₂ )n- or -CH ₂ -CH(-O-C(=O)-CH ₃ )-CH ₂ -, where n is 1 Indicates an integer from ~20.

In the metal-clad laminate or circuit board of the present invention, the adhesive polyimide contains 50 mol parts or more and 99 mol parts of diamine residues derived from the dimer acid-type diamine with respect to the total amount of 100 mol parts of the diamine residues. diamine residue derived from at least one diamine compound selected from diamine compounds represented by the following general formulas (B1) to (B7). may be contained within the range of 1 mol part or more and 50 mol parts or less.

In formulas (B1) to (B7), R ₁ independently represents a monovalent hydrocarbon group having 1 to 6 carbon atoms or an alkoxy group, and the linking group A independently represents -O-, -S-, -CO- , —SO—, —SO ₂ —, —COO—, —CH ₂ —, —C(CH ₃ ) ₂ —, —NH— or —CONH—, wherein n ₁ is independently Indicates an integer from 0 to 4. However, the formula (B3) that overlaps with the formula (B2) is excluded, and the formula (B5) that overlaps with the formula (B4) is excluded.

The multilayer circuit board of the present invention is a laminate of a plurality of circuit boards,
At least one or more of any one of the circuit boards described above is included as the circuit board.

A method for manufacturing a multilayer circuit board according to the first aspect of the present invention comprises:
preparing a plurality of circuit boards each having an insulating resin layer, a conductive circuit layer formed on one surface of the insulating resin layer, and an adhesive layer laminated on the other surface of the insulating resin layer; as well as,
stacking and press-bonding the conductive circuit layer of one of the circuit boards and the adhesive layer of the other circuit board so as to face each other;
may include.

A method for manufacturing a multilayer circuit board according to the second aspect of the present invention comprises:
preparing a plurality of circuit boards each having an insulating resin layer, a conductive circuit layer formed on one surface of the insulating resin layer, and an adhesive layer laminated on the other surface of the insulating resin layer; as well as,
a step of stacking and press-bonding the adhesive layer of one circuit board and the adhesive layer of another circuit board so as to face each other;
may include.

The metal-clad laminate of the present invention has a structure in which a metal layer is provided on one side of an insulating resin layer and an adhesive layer is provided on the other side. It is useful as a material for circuit boards. In addition, when a multilayer circuit board is manufactured using a metal-clad laminate, while maintaining the dimensional stability of the conductor circuit, it ensures coverage and adhesion to the conductor circuit layer, and further reduces the thickness of the entire resin layer. can be secured. Therefore, by using the metal-clad laminate of the present invention, a multilayer circuit board having good interlayer connection and high reliability can be obtained.
In addition, the multilayer circuit board of the present invention can reduce transmission loss even in transmission of high-frequency signals, enabling high-density integration and high-density mounting of electronic components. Moreover, since the multilayer circuit board of the present invention is excellent in heat resistance, it is possible to mount a semiconductor chip that generates a large amount of heat.

BRIEF DESCRIPTION OF THE DRAWINGS It is sectional drawing which shows the structure of the metal-clad laminated board concerning one embodiment of this invention. 1 is a cross-sectional view showing the structure of a circuit board according to one embodiment of the present invention; FIG. 1 is a cross-sectional view showing the structure of a multilayer circuit board according to a first embodiment of the present invention; FIG. FIG. 4 is an explanatory view showing manufacturing steps of the multilayer circuit board according to the first embodiment of the present invention; FIG. 5 is a cross-sectional view showing the structure of a multilayer circuit board according to a second embodiment of the present invention; It is explanatory drawing which shows the manufacturing process of the multilayer circuit board concerning the 2nd Embodiment of this invention.

An embodiment of the present invention will be described in detail.

[Metal clad laminate]
FIG. 1 is a cross-sectional view showing the structure of a metal-clad laminate according to one embodiment of the present invention. The metal-clad laminate 100 of the present embodiment includes an insulating resin layer 10, a metal layer 20 laminated on one surface of the insulating resin layer 10, and an adhesive layer laminated on the other surface of the insulating resin layer 10. 30 and . That is, the metal-clad laminate 100 has a structure in which the metal layer 20/insulating resin layer 10/adhesive layer 30 are laminated in this order. In other words, the metal-clad laminate 100 includes an adhesive layer 30 on the back side (insulating resin layer 10 side) of a single-sided metal-clad laminate 40 formed by laminating an insulating resin layer 10 and a metal layer 20 . has a structure to which is added. The adhesive layer 30 may be formed on the entire surface of one side of the insulating resin layer 10, or may be formed only on a portion thereof.

<Single-sided metal clad laminate>
The structure of the single-sided metal-clad laminate 40 is not particularly limited, and a common FPC material can be used, such as a commercially available copper-clad laminate. For example, commercially available copper-clad laminates include RF705T (trade name) manufactured by Panasonic Corporation and Espanex (trade name) manufactured by Nippon Steel Chemical & Materials.

(metal layer)
The material of the metal layer 20 is not particularly limited, but examples include copper, stainless steel, iron, nickel, beryllium, aluminum, zinc, indium, silver, gold, tin, zirconium, tantalum, titanium, lead, magnesium, manganese and These alloys etc. are mentioned. Among these, copper or a copper alloy is particularly preferred. The material of the wiring layer in the circuit board of this embodiment, which will be described later, is also the same as that of the metal layer 20 .

The thickness of the metal layer 20 is not particularly limited, but when using a metal foil such as a copper foil, the thickness is preferably 35 μm or less, more preferably in the range of 5 to 25 μm. The lower limit of the thickness of the metal foil is preferably 5 μm from the viewpoint of production stability and handling. When copper foil is used, it may be rolled copper foil or electrolytic copper foil. Moreover, as a copper foil, the copper foil marketed can be used.

In addition, the metal foil may be subjected to surface treatment with, for example, siding, aluminum alcoholate, aluminum chelate, silane coupling agent, etc., for the purpose of rust prevention treatment and adhesion strength improvement.

(insulating resin layer)
The insulating resin layer 10 is not particularly limited as long as it is made of an electrically insulating resin, and examples include polyimide, liquid crystal polymer, epoxy resin, phenol resin, polyethylene, polypropylene, polytetrafluoroethylene, silicone, ETFE, BT resin, etc. can be mentioned, but polyimide is preferable. In the present invention, polyimide means a polymer having an imide group in its molecular structure, such as polyamideimide, polyetherimide, polyesterimide, polysiloxaneimide, and polybenzimidazoleimide, in addition to polyimide.

Moreover, the insulating resin layer 10 is not limited to a single layer, and may be a laminate of a plurality of resin layers. Insulating resin layer 10 preferably includes a non-thermoplastic polyimide layer. The term "non-thermoplastic polyimide" generally refers to polyimide that does not soften or exhibit adhesiveness when heated. A polyimide having a storage modulus of 1.0×10 ⁹ Pa or more at °C and a storage modulus of 3.0×10 ⁸ Pa or more at 300°C.

The insulating resin layer 10 can be selected from, for example, a commercially available polyimide film, a commercially available liquid crystal polymer film, or a resin used as an insulating base material for a commercially available metal-clad laminate. Polyimide films include Upilex (trade name) manufactured by Ube Industries, Kapton (trade name) manufactured by DuPont Toray, Apical (trade name) and Pixio (trade name) manufactured by Kaneka, and liquid crystal polymer films. Vecstar (trade name) manufactured by Kuraray Co., Ltd., BIAC Film (trade name) manufactured by Primatec, and the like can be used.

The coefficient of thermal expansion (CTE) of the insulating resin layer 10 is not particularly limited, but is preferably 10 ppm/K or more, preferably 10 ppm/K or more and 30 ppm/K or less, more preferably 15 ppm/K or more. It is within the range of 25 ppm/K or less. If the CTE is less than 10 ppm/K or more than 30 ppm/K, warping will occur and dimensional stability will decrease. A desired CTE can be obtained by appropriately changing the combination of raw materials used, the thickness, and the drying/curing conditions.

The coefficient of thermal expansion (CTE) of the entire resin layer including the insulating resin layer 10 and the adhesive layer 30 is not particularly limited, but is preferably in the range of 10 ppm/K or more and 30 ppm/K or less, more preferably is in the range of 15 ppm/K or more and 25 ppm/K or less. If the total CTE of these resin layers is less than 10 ppm/K or more than 30 ppm/K, warpage occurs and dimensional stability decreases.

For example, when the insulating resin layer 10 is applied to a multilayer circuit board, the dielectric loss tangent (Tan δ) at 10 GHz is preferably 0.02 or less, more preferably 0.0005 or more, in order to suppress deterioration of dielectric loss. It is preferably in the range of 0.01 or less, more preferably in the range of 0.001 to 0.008. If the dielectric loss tangent of the insulating resin layer 10 at 10 GHz exceeds 0.02, problems such as loss of electrical signals tend to occur on the transmission path of high-frequency signals when applied to a multilayer circuit board. On the other hand, the lower limit value of the dielectric loss tangent of the insulating resin layer 10 at 10 GHz is not particularly limited, but the control of the physical properties as the insulating resin layer of the multilayer circuit board is taken into consideration.

Insulating resin layer 10 preferably has a dielectric constant (ε) of 4.0 or less at 10 GHz in order to ensure impedance matching when applied as an insulating resin layer of a multilayer circuit board, for example. If the dielectric constant of the insulating resin layer 10 at 10 GHz exceeds 4.0, the dielectric loss of the insulating resin layer 10 is deteriorated when applied to a multilayer circuit board, resulting in loss of electrical signals on the transmission path of high frequency signals. inconvenience is more likely to occur.

<Adhesive layer>
The adhesive layer 30 is composed of a thermoplastic resin or a thermosetting resin, under the following conditions;
(i) a storage modulus at 50°C of 1800 MPa or less;
(ii) the maximum value of the storage modulus from 180°C to 260°C is 800 MPa or less;
and (iii) a glass transition temperature (Tg) of 180° C. or lower;
It satisfies Examples of such resins include polyimide resins, polyamide resins, epoxy resins, phenoxy resins, acrylic resins, polyurethane resins, styrene resins, polyester resins, phenol resins, polysulfone resins, polyethersulfone resins, polyphenylene sulfide resins, polyethylene resins, Polypropylene resin, silicone resin, polyether ketone resin, polyvinyl alcohol resin, polyvinyl butyral resin, styrene-maleimide copolymer, maleimide-vinyl compound copolymer, or (meth) acrylic copolymer, epoxy resin, benzoxazine resin, Examples include resins such as bismaleimide resins and cyanate ester resins, and from among these, those that satisfy conditions (i) to (iii) are selected, or designed to satisfy conditions (i) to (iii). or can be used for the adhesive layer 30 .

When the adhesive layer 30 is a thermosetting resin, it may contain an organic peroxide, a curing agent, a curing accelerator, etc., and if necessary, a curing agent and a curing accelerator, or a catalyst and a co-catalyst are used in combination. You may The amount of the curing agent, curing accelerator, catalyst, co-catalyst, and organic peroxide to be added and whether or not to add them can be determined within the range where the above conditions (i) to (iii) can be ensured.

The adhesive layer 30 has a storage modulus of 1800 MPa or less at 50° C. and a maximum storage modulus of 800 MPa or less in the temperature range from 180° C. to 260° C., as shown in conditions (i) and (ii). be. Such properties of the adhesive layer 30 are considered to be the factors for relieving internal stress during thermocompression bonding and maintaining dimensional stability after circuit processing. The storage modulus of the adhesive layer 30 at the upper limit temperature (260° C.) of the temperature range is preferably 800 MPa or less, more preferably 500 MPa or less. With such a storage elastic modulus, warping is less likely to occur even after a solder reflow process after circuit processing.

As shown in condition (iii), the adhesive layer 30 has a glass transition temperature (Tg) of 180° C. or lower, preferably 160° C. or lower. By setting the glass transition temperature of the adhesive layer 30 to 180° C. or lower, thermocompression bonding can be performed at a low temperature, so that the internal stress generated during lamination can be alleviated and dimensional change can be suppressed. If the Tg of the adhesive layer 30 exceeds 180° C., the temperature at which it is interposed between the insulating resin layer 10 and an arbitrary circuit board for adhesion becomes high, which may impair the dimensional stability.

(CTE of adhesion layer)
The thermoplastic resin or thermosetting resin that constitutes the adhesive layer 30 has high thermal expansion but low elasticity and a low glass transition temperature, so even if the CTE exceeds 30 ppm/K, the internal stress generated during lamination can be mitigated. Therefore, the CTE of the adhesive layer 30 is preferably 35 ppm/K or higher, more preferably in the range of 35 ppm/K to 200 ppm/K, and even more preferably in the range of 35 ppm/K to 150 ppm/K. The adhesive layer 30 having a desired CTE can be obtained by appropriately changing the combination of raw materials to be used, the thickness, and the drying/curing conditions.

(Dielectric loss tangent of adhesive layer)
For example, when applied to a multilayer circuit board, the dielectric loss tangent (Tan δ) at 10 GHz is preferably 0.004 or less, more preferably 0.003 or less, and furthermore, in order to suppress deterioration of dielectric loss. Preferably, it is 0.002 or less. If the dielectric loss tangent of the adhesive layer 30 at 10 GHz exceeds 0.004, problems such as loss of electrical signals tend to occur on the transmission path of high-frequency signals when applied to a multilayer circuit board. On the other hand, the lower limit value of the dielectric loss tangent of the adhesive layer 30 at 10 GHz is not particularly limited.

(Dielectric constant of adhesive layer)
The adhesive layer 30 preferably has a dielectric constant of 4.0 or less at 10 GHz in order to ensure impedance matching when applied to a multilayer circuit board, for example. If the dielectric constant of the adhesive layer 30 at 10 GHz exceeds 4.0, the dielectric loss of the adhesive layer 30 will be worsened when applied to a multilayer circuit board, and there will be problems such as loss of electrical signals on the transmission path of high-frequency signals. becomes more likely to occur.

(filler)
The adhesion layer 30 may contain a filler as needed. Examples of fillers include silicon dioxide, aluminum oxide, magnesium oxide, beryllium oxide, boron nitride, aluminum nitride, silicon nitride, aluminum fluoride, calcium fluoride, metal salts of organic phosphinic acids, and the like. These can be used singly or in combination of two or more.

(adhesive polyimide)
Next, the case where the resin constituting the adhesive layer 30 is an adhesive thermoplastic polyimide containing a tetracarboxylic acid residue and a diamine residue (hereinafter sometimes referred to as "adhesive polyimide") is taken as an example. A specific configuration example of the adhesive layer 30 will be described. Adhesive polyimide is produced by imidizing a precursor polyamic acid obtained by reacting a specific acid anhydride and a diamine compound. A specific example is understood. In the present invention, the tetracarboxylic acid residue means a tetravalent group derived from a tetracarboxylic dianhydride, and the diamine residue is a divalent group derived from a diamine compound. means that In addition, the term "thermoplastic polyimide" generally refers to a polyimide whose glass transition temperature (Tg) can be clearly identified. ×10 ⁸ Pa or more and a storage modulus at 300°C of less than 3.0 × 10 ⁷ Pa.

(tetracarboxylic acid residue)
The adhesive polyimide contains tetracarboxylic acid residues derived from tetracarboxylic anhydrides represented by the following general formulas (1) and/or (2) with respect to 100 mol parts of all tetracarboxylic acid residues. (Hereinafter, sometimes referred to as "tetracarboxylic acid residue (1)" and "tetracarboxylic acid residue (2)"), it is preferable to contain a total of 90 mol parts or more. In the present invention, the tetracarboxylic acid residues (1) and/or (2) are contained in a total of 90 mol parts or more with respect to 100 mol parts of all tetracarboxylic acid residues, so that the adhesive polyimide is solvent-soluble. is imparted, and compatibility between the flexibility and heat resistance of the adhesive polyimide can easily be achieved, which is more preferable. If the total amount of tetracarboxylic acid residues (1) and/or (2) is less than 90 mol parts, the solvent solubility of the adhesive polyimide tends to decrease.

In general formula (1), X represents a single bond or a divalent group selected from the following formula, and in general formula (2), the cyclic portion represented by Y is a 4-membered ring, a 5-membered ring , a cyclic saturated hydrocarbon group selected from a 6-, 7-, or 8-membered ring.

In the above formula, Z represents -C ₆ H ₄ -, -(CH ₂ )n- or -CH ₂ -CH(-O-C(=O)-CH ₃ )-CH ₂ -, where n is 1 Indicates an integer from ~20.

Tetracarboxylic dianhydrides for deriving the tetracarboxylic acid residue (1) include, for example, 3,3′,4,4′-biphenyltetracarboxylic dianhydride (BPDA), 3,3′, 4,4'-benzophenonetetracarboxylic dianhydride (BTDA), 3,3',4,4'-diphenylsulfonetetracarboxylic dianhydride (DSDA), 4,4'-oxydiphthalic anhydride (ODPA) , 4,4′-(hexafluoroisopropylidene)diphthalic anhydride (6FDA), 2,2-bis[4-(3,4-dicarboxyphenoxy)phenyl]propane dianhydride (BPADA), p-phenylene Bis(trimellitic acid monoester acid anhydride) (TAHQ), ethylene glycol bisanhydrotrimellitate (TMEG), and the like can be mentioned.

Further, the tetracarboxylic dianhydride for deriving the tetracarboxylic acid residue (2) includes, for example, 1,2,3,4-cyclobutanetetracarboxylic dianhydride, 1,2,3,4- Cyclopentanetetracarboxylic dianhydride, 1,2,4,5-cyclohexanetetracarboxylic dianhydride, 1,2,4,5-cycloheptanetetracarboxylic dianhydride, 1,2,5,6- Cyclooctanetetracarboxylic dianhydride and the like can be mentioned.

The adhesive polyimide contains a tetracarboxylic acid residue derived from an acid anhydride other than the tetracarboxylic acid anhydride represented by the general formula (1) or (2) within the range that does not impair the effects of the invention. be able to.

(diamine residue)
The adhesive polyimide contains 50 mol parts or more of the dimer acid-type diamine residue derived from the dimer acid-type diamine with respect to 100 mol parts of the total diamine residues, for example, within the range of 50 mol parts or more and 99 mol parts or less, It is preferably contained in the range of 80 mol parts or more, for example 80 mol parts or more and 99 mol parts or less. By containing the dimer acid-type diamine residue in the above amount, the dielectric properties of the adhesive layer 30 are improved, and the thermocompression bonding properties are improved by lowering the glass transition temperature of the adhesive layer 30. Stress can be relieved. In addition, when the dimer acid-type diamine residue is 50 mol parts or more, solvent solubility and thermoplasticity can be imparted, the water absorption of the adhesive layer 30 can be reduced, and dimensional change due to etching, for example, can be reduced. If the dimer acid-type diamine residue is less than 50 mol parts per 100 mol parts of all diamine residues, the solvent solubility of the adhesive polyimide is reduced.

Here, the dimer acid-type diamine means that the two terminal carboxylic acid groups (-COOH) of the dimer acid are substituted with primary aminomethyl groups (-CH ₂ -NH ₂ ) or amino groups (-NH ₂ ). means a diamine consisting of Dimer acid is a known dibasic acid obtained by an intermolecular polymerization reaction of unsaturated fatty acids, and its industrial production process is almost standardized in the industry. It is obtained by dimerization with Etc. Industrially obtained dimer acid is mainly composed of dibasic acid with 36 carbon atoms obtained by dimerizing unsaturated fatty acids with 18 carbon atoms such as oleic acid and linoleic acid. , any amount of monomeric acids (18 carbon atoms), trimer acids (54 carbon atoms), and other polymerized fatty acids of 20 to 54 carbon atoms. In the present invention, it is preferable to use dimer acid whose content is increased to 90% by weight or more by molecular distillation. Moreover, although a double bond remains after the dimerization reaction, in the present invention, the dimer acid includes the one which is further hydrogenated to reduce the degree of unsaturation.

As a feature of the dimer acid-type diamine, it is possible to impart properties derived from the skeleton of the dimer acid to the polyimide. That is, the dimer acid-type diamine is a macromolecular aliphatic with a molecular weight of about 560 to 620, so that the molar volume of the molecule can be increased and the polar groups of the polyimide can be relatively reduced. Such features of the dimer acid-type diamine are considered to contribute to improving the dielectric properties by reducing the dielectric constant and the dielectric loss tangent while suppressing the deterioration of the heat resistance of the polyimide. In addition, since it has two freely moving hydrophobic chains having 7 to 9 carbon atoms and two chain aliphatic amino groups having a length close to 18 carbon atoms, it not only gives the polyimide flexibility, Since polyimide can have an asymmetrical chemical structure or a non-planar chemical structure, it is thought that a low dielectric constant and a low dielectric loss tangent of polyimide can be achieved.

Dimer acid-type diamines are commercially available, for example, PRIAMINE 1073 (trade name), PRIAMINE 1074 (trade name), and PRIAMINE 1075 (trade name) manufactured by Croda Japan, Versamin 551 (trade name) manufactured by BASF Japan. ), Versamin 552 (trade name), and the like.

In addition, the adhesive polyimide contains a diamine residue derived from at least one diamine compound selected from the diamine compounds represented by the following general formulas (B1) to (B7), to 100 mol parts of all diamine residues. On the other hand, the total content is preferably in the range of 1 mol part or more and 50 mol parts or less, and more preferably in the range of 1 mol part or more and 20 mol parts or less. Since the diamine compounds represented by the general formulas (B1) to (B7) have a flexible molecular structure, by using at least one diamine compound selected from these in an amount within the above range, the polyimide molecule It can improve chain flexibility and impart solvent solubility and thermoplasticity. Further, by using the diamine compounds represented by the general formulas (B1) to (B7), even when a via hole (through hole) is formed in the adhesive layer 30 by laser processing, for example, the ratio of the aromatic rings in the polyimide molecular structure By increasing the temperature, it is possible to increase the absorption in the ultraviolet region, for example, and also to increase the glass transition temperature of the adhesive layer 30, thereby improving the heat resistance against the temperature rise of the bottom metal due to the heat input of the laser light. Therefore, the laser workability can be further improved. The total amount of diamine residues derived from at least one diamine compound selected from diamine compounds represented by the following general formulas (B1) to (B7) is 50 per 100 mole parts of all diamine residues. If it exceeds the molar part, the flexibility of the adhesive polyimide becomes insufficient and the glass transition temperature rises, so that the residual stress due to thermocompression bonding increases and the post-etching dimensional change rate tends to deteriorate.

In formulas (B1) to (B7), R ₁ independently represents a monovalent hydrocarbon group having 1 to 6 carbon atoms or an alkoxy group, and the linking group A independently represents -O-, -S-, -CO- , —SO—, —SO ₂ —, —COO—, —CH ₂ —, —C(CH ₃ ) ₂ —, —NH— or —CONH—, wherein n ₁ is independently Indicates an integer from 0 to 4. However, the formula (B3) that overlaps with the formula (B2) is excluded, and the formula (B5) that overlaps with the formula (B4) is excluded.
The term “independently” means that in one or more of the above formulas (B1) to (B7), multiple linking groups A, multiple R ₁ or multiple n ₁ may be the same. It means good and can be different. Further, in formulas (B1) to (B7), the hydrogen atoms in the two terminal amino groups may be substituted, for example —NR ₂ R ₃ (wherein R ₂ and R ₃ are independently alkyl (meaning any substituent such as a group).

The diamine represented by formula (B1) (hereinafter sometimes referred to as "diamine (B1)") is an aromatic diamine having two benzene rings. In this diamine (B1), the amino group directly attached to at least one benzene ring and the divalent linking group A are at the meta position, so that the degree of freedom of the polyimide molecular chain is increased and has high flexibility. It is thought that it contributes to the improvement of the flexibility of the polyimide molecular chain. Therefore, the use of the diamine (B1) enhances the thermoplasticity of the polyimide. Here, the linking group A is preferably -O-, -CH ₂ -, -C(CH ₃ ) ₂ -, -CO-, -SO ₂ -, -S-, or -COO-.

Diamine (B1) includes, for example, 3,3'-diaminodiphenylmethane, 3,3'-diaminodiphenylpropane, 3,3'-diaminodiphenyl sulfide, 3,3'-diaminodiphenyl sulfone, 3,3-diaminodiphenyl ether , 3,4'-diaminodiphenyl ether, 3,4'-diaminodiphenylmethane, 3,4'-diaminodiphenylpropane, 3,4'-diaminodiphenyl sulfide, 3,3'-diaminobenzophenone, (3,3'-bisamino ) diphenylamine and the like.

The diamine represented by formula (B2) (hereinafter sometimes referred to as "diamine (B2)") is an aromatic diamine having three benzene rings. This diamine (B2) has an amino group directly attached to at least one benzene ring and a divalent linking group A at the meta position, so that the degree of freedom of the polyimide molecular chain is increased and has high flexibility. It is thought that it contributes to the improvement of the flexibility of the polyimide molecular chain. Therefore, the use of the diamine (B2) enhances the thermoplasticity of the polyimide. Here, the connecting group A is preferably -O-.

Examples of the diamine (B2) include 1,4-bis(3-aminophenoxy)benzene, 3-[4-(4-aminophenoxy)phenoxy]benzenamine, 3-[3-(4-aminophenoxy)phenoxy] Benzenamine and the like can be mentioned.

The diamine represented by formula (B3) (hereinafter sometimes referred to as "diamine (B3)") is an aromatic diamine having three benzene rings. This diamine (B3) has two divalent linking groups A directly connected to one benzene ring at the meta-position to each other, so that the degree of freedom of the polyimide molecular chain is increased and has high flexibility. It is thought that this contributes to the improvement of the flexibility of the polyimide molecular chain. Therefore, the use of the diamine (B3) enhances the thermoplasticity of the polyimide. Here, the connecting group A is preferably -O-.

Examples of the diamine (B3) include 1,3-bis(4-aminophenoxy)benzene (TPE-R), 1,3-bis(3-aminophenoxy)benzene (APB), 4,4'-[2- Methyl-(1,3-phenylene)bisoxy]bisaniline, 4,4'-[4-methyl-(1,3-phenylene)bisoxy]bisaniline, 4,4'-[5-methyl-(1,3-phenylene) ) bisoxy] bisaniline and the like.

The diamine represented by formula (B4) (hereinafter sometimes referred to as "diamine (B4)") is an aromatic diamine having four benzene rings. This diamine (B4) has high flexibility due to the fact that the amino group directly connected to at least one benzene ring and the divalent linking group A are in the meta position, and improve the flexibility of the polyimide molecular chain. considered to contribute. Therefore, the use of the diamine (B4) enhances the thermoplasticity of the polyimide. Here, the linking group A is preferably -O-, -CH ₂ -, -C(CH ₃ ) ₂ -, -SO ₂ -, -CO-, or -CONH-.

Diamines (B4) include bis[4-(3-aminophenoxy)phenyl]methane, bis[4-(3-aminophenoxy)phenyl]propane, bis[4-(3-aminophenoxy)phenyl]ether, bis Examples include [4-(3-aminophenoxy)phenyl]sulfone, bis[4-(3-aminophenoxy)]benzophenone, bis[4,4'-(3-aminophenoxy)]benzanilide and the like.

The diamine represented by formula (B5) (hereinafter sometimes referred to as "diamine (B5)") is an aromatic diamine having four benzene rings. This diamine (B5) has two divalent linking groups A directly connected to at least one benzene ring at the meta position to each other, so that the degree of freedom of the polyimide molecular chain is increased and has high flexibility. It is thought that it contributes to the improvement of the flexibility of the polyimide molecular chain. Therefore, the use of the diamine (B5) enhances the thermoplasticity of the polyimide. Here, the connecting group A is preferably -O-.

Examples of the diamine (B5) include 4-[3-[4-(4-aminophenoxy)phenoxy]phenoxy]aniline, 4,4'-[oxybis(3,1-phenyleneoxy)]bisaniline, and the like. .

The diamine represented by formula (B6) (hereinafter sometimes referred to as "diamine (B6)") is an aromatic diamine having four benzene rings. Since this diamine (B6) has at least two ether bonds, it has high flexibility, and is considered to contribute to the improvement of the flexibility of the polyimide molecular chain. Therefore, the use of the diamine (B6) enhances the thermoplasticity of the polyimide. Here, the linking group A is preferably -C(CH ₃ ) ₂ -, -O-, -SO ₂ -, or -CO-.

Examples of the diamine (B6) include 2,2-bis[4-(4-aminophenoxy)phenyl]propane (BAPP), bis[4-(4-aminophenoxy)phenyl]ether (BAPE), bis[4 -(4-aminophenoxy)phenyl]sulfone (BAPS), bis[4-(4-aminophenoxy)phenyl]ketone (BAPK) and the like.

The diamine represented by formula (B7) (hereinafter sometimes referred to as "diamine (B7)") is an aromatic diamine having four benzene rings. Since this diamine (B7) has highly flexible divalent linking groups A on both sides of the diphenyl skeleton, it is believed that this contributes to the improvement of the flexibility of the polyimide molecular chain. Therefore, the use of the diamine (B7) enhances the thermoplasticity of the polyimide. Here, the connecting group A is preferably -O-.

Examples of the diamine (B7) include bis[4-(3-aminophenoxy)]biphenyl, bis[4-(4-aminophenoxy)]biphenyl and the like.

The adhesive polyimide may contain a diamine residue derived from a diamine compound other than the dimer acid-type diamine and diamines (B1) to (B7) as long as the effects of the invention are not impaired.

In addition, the adhesive polyimide is prepared by selecting the types of the tetracarboxylic acid residue and the diamine residue, and the respective molar ratios when two or more tetracarboxylic acid residues or diamine residues are contained. The expansion coefficient, tensile modulus, glass transition temperature, etc. can be controlled. When a plurality of polyimide structural units are present, they may be present as blocks or randomly, but are preferably present randomly.

The imide group concentration of the adhesive polyimide is preferably 20% by weight or less. Here, "imide group concentration" means a value obtained by dividing the molecular weight of the imide group (-(CO) ₂ -N-) in the polyimide by the molecular weight of the entire structure of the polyimide. When the imide group concentration exceeds 20% by weight, the molecular weight of the resin itself becomes small, and the low hygroscopicity deteriorates due to the increase in polar groups, resulting in an increase in elastic modulus.

The weight average molecular weight of the adhesive polyimide is, for example, preferably within the range of 10,000 to 400,000, more preferably within the range of 20,000 to 350,000. If the weight-average molecular weight is less than 10,000, the strength of the adhesive layer 30 is lowered and the adhesive layer 30 tends to become brittle. On the other hand, if the weight-average molecular weight exceeds 400,000, the viscosity increases excessively, and defects such as unevenness in the thickness of the adhesive layer 30 and streaks tend to occur during the coating operation.

Since the adhesive polyimide covers the conductive circuit layers of any circuit board when forming a multi-layer circuit board, a completely imidized structure is most preferable to suppress copper diffusion. However, part of the polyimide may be amic acid. The imidization rate is around 1015 cm ⁻¹ by measuring the infrared absorption spectrum of the polyimide thin film by the single reflection ATR method using a Fourier transform infrared spectrophotometer (commercial product: FT/IR620 manufactured by JASCO Corporation). can be calculated from the absorbance of C═O stretching derived from the imide group at 1780 cm ⁻¹ based on the benzene ring absorber of .

(crosslink formation)
When the adhesive polyimide has a ketone group, the ketone group is reacted with the amino group of an amino compound having at least two primary amino groups as functional groups to form a C=N bond, thereby cross-linking. Structures can be formed. By forming a crosslinked structure, the heat resistance of the adhesive polyimide can be improved. A preferred tetracarboxylic anhydride for forming a polyimide having a ketone group is, for example, 3,3′,4,4′-benzophenonetetracarboxylic dianhydride (BTDA), and a diamine compound is, for example, 4 Aromatic diamines such as ,4'-bis(3-aminophenoxy)benzophenone (BABP) and 1,3-bis[4-(3-aminophenoxy)benzoyl]benzene (BABB) can be mentioned.

Examples of amino compounds that can be used for crosslinking the adhesive polyimide include dihydrazide compounds, aromatic diamines, and aliphatic amines. Among these, dihydrazide compounds are preferred. Aliphatic amines other than dihydrazide compounds tend to form a crosslinked structure even at room temperature, and there is concern about the storage stability of varnishes. On the other hand, aromatic diamines require a high temperature to form a crosslinked structure. When a dihydrazide compound is used, both the storage stability of the varnish and the shortening of the curing time can be achieved. Examples of dihydrazide compounds include oxalic acid dihydrazide, malonic acid dihydrazide, succinic acid dihydrazide, glutaric acid dihydrazide, adipic acid dihydrazide, pimelic acid dihydrazide, suberic acid dihydrazide, azelaic acid dihydrazide, sebacic acid dihydrazide, dodecanedioic acid dihydrazide, and maleic acid. dihydrazide, fumaric acid dihydrazide, diglycolic acid dihydrazide, tartaric acid dihydrazide, malic acid dihydrazide, phthalic acid dihydrazide, isophthalic acid dihydrazide, terephthalic acid dihydrazide, 2,6-naphthoedioic acid dihydrazide, 4,4-bisbenzene dihydrazide, 1,4 Dihydrazide compounds such as -naphthoic acid dihydrazide, 2,6-pyridinedioic acid dihydrazide, and itaconic acid dihydrazide are preferred. The above dihydrazide compounds may be used alone or in combination of two or more.

The adhesive polyimide can be produced by reacting the tetracarboxylic dianhydride and the diamine compound in a solvent to form a polyamic acid, followed by heat ring closure. For example, a tetracarboxylic dianhydride and a diamine compound are dissolved in an organic solvent in approximately equimolar amounts and stirred at a temperature within the range of 0 to 100° C. for 30 minutes to 24 hours for a polymerization reaction to form an adhesive polyimide. A polyamic acid precursor is obtained. In the reaction, the reaction components are dissolved in the organic solvent so that the resulting precursor is within the range of 5 to 50% by weight, preferably within the range of 10 to 40% by weight. Examples of organic solvents used in the polymerization reaction include N,N-dimethylformamide (DMF), N,N-dimethylacetamide (DMAc), N,N-diethylacetamide, N-methyl-2-pyrrolidone (NMP), 2 -butanone, dimethylsulfoxide (DMSO), hexamethylphosphoramide, N-methylcaprolactam, dimethyl sulfate, cyclohexanone, dioxane, tetrahydrofuran, diglyme, triglyme, cresol and the like. Two or more of these solvents can be used in combination, and aromatic hydrocarbons such as xylene and toluene can also be used in combination. The amount of such an organic solvent to be used is not particularly limited, but the amount used is adjusted so that the concentration of the polyamic acid solution obtained by the polymerization reaction is about 5 to 50% by weight. is preferred.

It is usually advantageous to use the synthesized polyamic acid as a reaction solvent solution, but if necessary, it can be concentrated, diluted, or replaced with another organic solvent. Polyamic acid is also advantageously used because it is generally excellent in solvent solubility. The viscosity of the polyamic acid solution is preferably in the range of 500 cps to 100,000 cps. If the thickness is out of this range, defects such as thickness unevenness and streaks are likely to occur in the film during the coating operation using a coater or the like.

The method of imidizing the polyamic acid to form a polyimide is not particularly limited, for example, a heat treatment such as heating for 1 to 24 hours under a temperature condition within the range of 80 to 400 ° C. in the solvent is preferably employed. be done.

When cross-linking the adhesive polyimide obtained as described above, the amino compound is added to a resin solution containing a polyimide having a ketone group, and the ketone group in the adhesive polyimide and the primary amino compound are Condensation reaction with an amino group. Due to this condensation reaction, the resin solution is cured into a cured product. In this case, the amount of the amino compound to be added is preferably 0.004 mol to 1.5 mol, preferably 0.005 mol to 1.2 mol, and more, per 1 mol of the ketone group. The amino compound can be added in an amount of preferably 0.03 to 0.9 mol, most preferably 0.04 to 0.5 mol. If the amount of amino compound added is such that the total amount of primary amino groups is less than 0.004 mol per 1 mol of ketone group, the polyimide chain is not sufficiently crosslinked by the amino compound. The heat resistance tends to be difficult to develop in the layer 30, and when the amount of the amino compound added exceeds 1.5 mol, the unreacted amino compound acts as a thermoplastic and tends to lower the heat resistance of the adhesive layer 30. .

The condensation reaction conditions for cross-linking are not particularly limited as long as the ketone groups in the adhesive polyimide react with the primary amino groups of the amino compound to form imine bonds (C=N bonds). The temperature of the heat condensation is, for example, 120° C. for reasons such as releasing water generated by the condensation to the outside of the system, or simplifying the condensation step when the heat condensation reaction is subsequently performed after the synthesis of the adhesive polyimide. It is preferably within the range of -220°C, more preferably within the range of 140-200°C. The reaction time is preferably about 30 minutes to 24 hours, and the end point of the reaction is, for example, 1670 cm by measuring the infrared absorption spectrum using a Fourier transform infrared spectrophotometer (commercial product: FT/IR620 manufactured by JASCO Corporation). It can be confirmed by the reduction or disappearance of the absorption peak derived from the ketone group in the polyimide resin around ⁻¹ and the appearance of the absorption peak derived from the imine group around 1635 cm ⁻¹ .

The thermal condensation of the ketone group of the adhesive polyimide and the primary amino group of the amino compound can be performed, for example, by (a) a method of adding an amino compound and heating following synthesis (imidation) of the adhesive polyimide, ( b) A method in which an excessive amount of an amino compound is charged in advance as a diamine component, and following the synthesis (imidization) of the adhesive polyimide, the adhesive polyimide is heated together with the remaining amino compound that does not participate in imidization or amidation, or , (c) a method of heating an adhesive polyimide composition to which an amino compound is added after processing it into a predetermined shape (for example, after applying it to an arbitrary substrate or after forming it into a film), and the like. can be done.

In order to impart heat resistance to the adhesive layer 30, the formation of an imine bond has been described as the formation of a crosslinked structure in the adhesive polyimide. It is also possible to add a resin curing agent or the like for curing.

<Thickness of resin layer>
In the metal-clad laminate 100, when the total thickness T1 of the thickness T3 of the insulating resin layer 10 and the thickness T2 of the adhesive layer 30 is T1, the total thickness T1 is in the range of 50 to 250 μm, and is in the range of 70 to 150 μm. preferably within If the total thickness T1 is less than 50 μm, the effect of reducing transmission loss when manufacturing a multilayer circuit board using the metal-clad laminate 100 is insufficient, and if it exceeds 250 μm, there is a risk of reduced productivity.

Also, the thickness T2 of the adhesive layer 30 is preferably in the range of, for example, 20 to 200 μm, more preferably in the range of 20 to 100 μm. If the thickness T2 of the adhesive layer 30 is less than the above lower limit, the transmission loss of the high frequency substrate may increase. On the other hand, if the thickness T2 of the adhesive layer 30 exceeds the above upper limit, problems such as deterioration in dimensional stability may occur.

Also, the ratio (T2/T1) of the thickness T2 of the adhesive layer 30 to the total thickness T1 is within the range of 0.5 to 0.8, preferably within the range of 0.5 to 0.7. If the ratio (T2/T1) is less than 0.5, it will be difficult to make the total thickness T1 50 μm or more, and if it exceeds 0.8, problems such as reduced dimensional stability will occur.

The thickness T3 of the insulating resin layer 10 is, for example, preferably in the range of 12-100 μm, more preferably in the range of 12-50 μm. If the thickness T3 of the insulating resin layer 10 is less than the above lower limit, problems such as warping of the metal-clad laminate 100 may occur. If the thickness T3 of the insulating resin layer 10 exceeds the above upper limit, problems such as reduced productivity occur.

In the metal-clad laminate 100 of the present embodiment, the thickness T2 of the adhesive layer 30 itself is increased in order to reduce the dielectric loss tangent of the entire resin layer and to enable high-frequency transmission. However, since a material with a low elastic modulus generally exhibits a high coefficient of thermal expansion, increasing the layer thickness may lead to a decrease in dimensional stability. Here, the dimensional change that occurs when the metal-clad laminate 100 is circuit-processed to form a multi-layer circuit is mainly caused by the following mechanisms a) to c), and the total amount of b) and c) is It is thought that this appears as a dimensional change after etching.
a) During the production of the metal-clad laminate 100, internal stress is accumulated in the resin layer.
b) By etching the metal layer 20 during circuit processing, the internal stress accumulated in a) is released and the resin layer expands or contracts.
c) When the metal layer 20 is etched during circuit processing, exposed resin absorbs moisture and expands.

Factors of the internal stress in a) above are a) difference in thermal expansion coefficient between the metal layer 20 and the resin layer, and b) resin internal strain caused by film formation. Here, the magnitude of the internal stress caused by a) is affected not only by the difference in the coefficient of thermal expansion, but also by the temperature difference ΔT between the bonding temperature (heating temperature) and the cooling solidification temperature when forming a multi-layer circuit. do. That is, since the internal stress increases in proportion to the temperature difference ΔT, even if the difference in thermal expansion coefficient between the metal layer 20 and the resin layer is small, the internal stress increases as the resin requires a higher temperature for adhesion. Become. In the metal-clad laminate 100 of the present embodiment, the adhesive layer 30 that satisfies the above conditions (i) to (iii) reduces the internal stress and ensures dimensional stability. Further, since the adhesive layer 30 is laminated on the insulating resin layer 10, it functions as an intermediate layer when a multilayer circuit board is formed, and suppresses warpage and dimensional change.

[Method for producing metal-clad laminate]
The metal-clad laminate 100 can be manufactured, for example, by method 1 or method 2 below.
[Method 1]
A method in which the resin composition that forms the adhesive layer 30 is formed into a film to form an adhesive film, and the adhesive film is arranged so as to face the insulating resin layer 10 of the single-sided metal-clad laminate 40 and bonded together, followed by thermocompression bonding. .
[Method 2]
A method in which a solution of a resin composition that forms the adhesive layer 30 is applied to a predetermined thickness on the insulating resin layer 10 of the single-sided metal-clad laminate 40 and then dried. In this case, if necessary, a treatment such as heating may be performed for curing reaction or cross-linking reaction.

The adhesive film used in Method 1 can be produced, for example, by applying a solution of the resin composition that will form the adhesive layer 30 to an arbitrary supporting substrate, drying the solution, and then peeling off from the supporting substrate. As the adhesive film, an adhesive polyimide film obtained by forming the above adhesive polyimide into a film may be used. As an embodiment of the method for producing an adhesive polyimide film, for example, [1] a support substrate is coated with a polyamic acid solution, dried, imidized by heat treatment, and then peeled off from the support substrate to produce an adhesive film. [2] A method of applying a polyamic acid solution to a supporting substrate and drying it, then peeling off the polyamic acid gel film from the supporting substrate and imidizing it by heat treatment to produce an adhesive film, [3] Supporting A method in which an adhesive polyimide solution is applied to a base material, dried, and then peeled off from the supporting base material to produce an adhesive film can be mentioned. Among the above [1] to [3], it is preferable to form by the method [3] in which a solution of an adhesive polyimide whose imidization is completed in a polyamic acid solution is applied onto a supporting substrate and dried. Since the adhesive polyimide is solvent-soluble, it is advantageous that the polyamic acid can be imidized in a solution state and used as it is as a coating liquid for the adhesive polyimide. The adhesive polyimide constituting the adhesive film may be crosslinked by the above method.

In methods 1 and 2, the method of applying the solution of the resin composition that will form the adhesive layer 30 onto the supporting substrate or the insulating resin layer 10 is not particularly limited, and examples include commas, dies, knives, lips, and the like. It can be applied with a coater. In the step of forming the adhesive layer 30, the surface of the adhesive layer 30 to be formed is preferably flat. Also, it is preferable to form the adhesive layer 30 with a uniform thickness. By flattening the surface of the adhesive layer 30 and making the thickness uniform, the adhesiveness in the manufacturing process of the multilayer circuit board is improved.

The metal-clad laminate 100 of the present embodiment obtained as described above can be used to manufacture a single-sided FPC or a double-sided FPC by wiring and circuit processing the metal layer 20. In addition, the adhesiveness of the adhesive layer 30 can be used. Alternatively, a multilayer circuit board can be manufactured by laminating a plurality of single-sided FPCs or double-sided FPCs by using an arbitrary bonding sheet.

[Circuit board]
FIG. 2 is a cross-sectional view showing the structure of a circuit board according to one embodiment of the present invention. The circuit board 101 includes an insulating resin layer 10, a conductor circuit layer 50 laminated on one side of the insulating resin layer 10, and an adhesive layer 30 laminated on the other side of the insulating resin layer 10. ing. That is, the circuit board 101 has a structure in which the conductor circuit layer 50/insulating resin layer 10/adhesive layer 30 are laminated in this order. The circuit board 101 of the present embodiment is obtained by processing the metal layer 20 of the metal-clad laminate 100 for wiring circuits.

(Conductor circuit layer)
The conductor circuit layer 50 is a layer in which a conductor circuit is formed in a predetermined pattern on one side of the insulating resin layer 10 . For example, a photosensitive resist is applied on the metal layer 20 of the metal-clad laminate 100, exposed and developed to form a predetermined mask pattern, the metal layer 20 is etched through the mask pattern, and then the mask is applied. By removing the pattern, a conductor circuit layer 50 having a predetermined pattern can be formed. The “conductor circuit layer” means an in-plane connection electrode (land electrode) formed in the surface direction of the insulating resin layer 10, and is distinguished from an interlayer connection electrode (via electrode).

From the viewpoint of reducing transmission loss in high-frequency transmission, the conductor circuit layer 50 preferably has a maximum height roughness (Rz) of 1.0 μm or less on the surface in contact with the insulating resin layer 10 . Transmission loss is the sum of conductor loss and dielectric loss. If the conductor circuit layer 50 has a large Rz, the conductor loss increases and adversely affects the transmission loss. Therefore, it is preferable to control Rz.

The configurations of the insulating resin layer 10 and the adhesive layer 30 in the circuit board 101 of the present embodiment are as described for the metal-clad laminate 100 .

[Multilayer circuit board]
Next, a multilayer circuit board according to an embodiment of the present invention will be described with reference to FIGS. 3 to 6. FIG. In general, a multilayer circuit board has a laminate containing a plurality of insulating resin layers and two or more conductor circuit layers embedded in the laminate. It has a resin layer and at least two conductor circuit layers. Two preferred embodiments of multilayer circuit boards are described herein. The multilayer circuit boards 200 and 201 of this embodiment include at least one or more of the circuit boards 101 described above. Moreover, the multilayer circuit boards 200 and 201 of the present embodiment can include one or more arbitrary circuit boards other than the circuit board 101 laminated on the circuit board 101 .

<First Embodiment>
FIG. 3 is a cross-sectional view in the lamination direction showing the structure of the multilayer circuit board 200 according to the first embodiment of the present invention. A multilayer circuit board 200 according to the first embodiment has a structure in which a plurality of circuit boards 101 and an arbitrary circuit board 110 are laminated in the same direction.
That is, from top to bottom in FIG. The adhesive layer 30 of the circuit board 101 is laminated so as to cover the conductor circuit layer 50 of any circuit board 110 that does not have the adhesive layer 30 . Here, the structure and material of the arbitrary circuit board 110 are not limited. may have Moreover, the conductor circuit layer 50 in the arbitrary circuit board 110 may be formed on the insulating resin layer 10 by inkjet, sputtering, plating, or the like. Furthermore, the thickness, material, physical properties, etc. of the conductor circuit layer 50 and the insulating resin layer 10 in the arbitrary circuit board 110 are not particularly limited.

Although FIG. 3 illustrates a laminated structure of two circuit boards 101 and one arbitrary circuit board 110, three or more circuit boards 101 may be laminated. Moreover, the adhesive layer 30 may cover all or part of the conductor circuit layer 50 of the adjacent circuit board 101 or arbitrary circuit board 110 . Furthermore, although the multilayer circuit board 200 has the conductor circuit layer 50 exposed on the surface of the uppermost circuit board 101 , any protective film may be provided to cover the uppermost conductor circuit layer 50 . 3 exemplifies the case where the conductor circuit layer 50 is formed on one side of the insulating resin layer 10 as the arbitrary circuit board 110, but the conductor circuit layer 50 is formed on both sides of the insulating resin layer 10, respectively. It may be formed.

FIG. 4 is a manufacturing process diagram of the multilayer circuit board 200 according to the first embodiment. First, a plurality of circuit boards 101 and an arbitrary circuit board 110 are prepared. The adhesive layer 30 of the first circuit board 101 faces the conductor circuit layer 50 of the second circuit board 101, and the adhesive layer 30 of the second circuit board 101 does not have the adhesive layer 30. It can be manufactured by overlappingly arranging the conductor circuit layer 50 of an arbitrary circuit board 110 so as to face it, and then collectively crimping them (crimping step). Although FIG. 4 shows an example in which two circuit boards 101 are laminated, three or more circuit boards 101 can be laminated at once. Also, the number of arbitrary circuit boards 110 is not limited to one, and a plurality of boards can be laminated.

Since the surface of the adhesive layer 30 of the circuit board 101 is flattened, the adhesive resin is filled between the conductor circuits in the conductor circuit layer 50 without forming any voids or the like in the adhesive layer 30 during the pressure bonding process. It is possible to laminate with Further, if necessary, a thickness adjustment step of adjusting the thickness of the adhesive layer 30 may be performed by pressing the multilayer circuit board 200 obtained by lamination from both sides with pressure rollers, a press device, or the like. can. The thickness adjustment process can improve the accuracy of the thickness of the adhesive layer 30 and the multilayer circuit board 200 as a whole. Further, heat treatment may be performed at a temperature of 60 to 220° C., for example, during pressure bonding. As a result, a multilayer circuit board 200 in which a plurality of circuit boards are integrally laminated is manufactured. During this heat treatment, a crosslinked structure of imine bonds can be formed in the adhesive layer 30 by thermal condensation of the adhesive polyimide, for example.

In this embodiment, the adhesive layer 30 of each circuit board 101 has a function as a bonding sheet for bonding the circuit boards together and a function as a protective film for protecting the conductor circuit. Therefore, there is no need to separately prepare a bonding sheet or protective layer for the conductor circuit and interpose it between the circuit boards, and it is possible to simplify the process and equipment for forming the multilayer circuit, simplify the materials, and reduce the cost. becomes possible.

In the multilayer circuit board 200 obtained as described above, the adhesive layer 30 having sufficient thickness to ensure insulation, flexibility and low dielectric properties is provided between the conductor circuit layer 50 and the insulating resin layer 10. configuration. In addition, the multilayer circuit board 200 of the present embodiment may be provided with a layer such as a coverlay film or a solder resist as a protective layer, if necessary. Although not shown, chip-type electronic components such as IC chips, chip capacitors, chip coils, and chip resistors can be incorporated inside the multilayer circuit board 200 of the present embodiment. In addition, interlayer connection electrodes (via electrodes) (not shown) may be formed in the multilayer circuit board 200 of the present embodiment. The interlayer connection electrodes can be formed by forming via holes in the insulating resin layer 10 by laser processing or drilling and then filling them with a conductive paste by printing or the like. As the conductive paste, for example, a conductive powder containing tin as a main component, mixed with an organic solvent, an epoxy resin, or the like can be used. Further, the interlayer connection electrode may form a plated portion on the inner surface of the via hole and part of the surface of the conductive circuit layer 50 after forming the via hole.

<Second embodiment>
FIG. 5 is a cross-sectional view in the lamination direction showing the structure of a multilayer circuit board 201 according to the second embodiment of the present invention. In the multilayer circuit board 201 of the second embodiment, one circuit board unit 102 is formed by bonding a pair of circuit boards 101 such that their adhesive layers 30 face each other. contains at least one
That is, from top to bottom in FIG. ), and are laminated such that the circuit board unit 102 is sandwiched between the adhesive layers 30 of the two metal-clad laminates 100 . The adhesive layer 30 of the first metal-clad laminate 100 is laminated so as to be in contact with the conductor circuit layer 50 on one side (the upper side in the drawing) of the circuit board unit 102, and further on the other side of the circuit board unit 102. The adhesive layer 30 of the second metal-clad laminate 100 is laminated so as to be in contact with the conductive circuit layer 50 (lower side in the drawing). Although FIG. 5 shows a laminated structure including only one circuit board unit 102, a plurality of circuit board units 102 can be formed by further interposing a bonding sheet, circuit board 101, or optional circuit board 110. It is good also as a lamination structure containing. Also, the circuit board 101 may be used as one or both of the upper and lower metal-clad laminates 100 .

FIG. 6 is a manufacturing process diagram of the multilayer circuit board 201 according to the second embodiment. First, one circuit board unit 102 and two metal-clad laminates 100 are prepared. Here, the circuit board unit 102 can be manufactured by preparing a pair of circuit boards 101 and bonding the adhesive layer 30 of one circuit board 101 and the adhesive layer 30 of the other circuit board 101 together. Then, the multilayer circuit board 201 is arranged so that the adhesive layer 30 of the first metal-clad laminate 100 faces the conductive circuit layer 50 on the upper surface side of the circuit board unit 102, and furthermore, the circuit board unit 102 is The adhesive layer 30 of the second metal-clad laminate 100 is arranged so as to face the conductor circuit layer 50 on the lower surface side, and these are collectively crimped (crimping step).

In addition, without fabricating the circuit board unit 102, the adhesive layer 30 of the first metal-clad laminate 100 is arranged so as to face the conductor circuit layer 50 of the upper circuit board 101, and the upper circuit board 101 The adhesive layer 30 and the adhesive layer 30 of the lower circuit board 101 are arranged so as to face each other, and further, the adhesive layer of the second metal-clad laminate 100 is placed on the conductor circuit layer 50 of the lower circuit board 101. 30 may be arranged to face each other, and these may be crimped collectively.

If necessary, a thickness adjustment step of adjusting the thickness of the adhesive layer 30 can be performed by pressing the multilayer circuit board 201 obtained by lamination from both sides with pressure rollers, a press device, or the like. The thickness adjustment process can improve the precision of the thickness of the adhesive layer 30 and the multilayer circuit board 201 as a whole. Further, heat treatment may be performed at a temperature of 60 to 220° C., for example, during pressure bonding. As a result, a multilayer circuit board 201 in which a plurality of circuit boards are integrally laminated is manufactured. During this heat treatment, a crosslinked structure of imine bonds can be formed in the adhesive layer 30 by thermal condensation of the adhesive polyimide, for example.

Also in the present embodiment, the adhesive layer 30 of each circuit board 101 functions as a bonding sheet for bonding the circuit boards together. Therefore, there is no need to separately prepare a bonding sheet and interpose it between the circuit boards, and it is possible to simplify the process and equipment for forming the multilayer circuit, simplify the materials, and reduce the cost.

Other configurations and effects of the multilayer circuit board 201 of the present embodiment are the same as those of the multilayer circuit board 200 of the first embodiment.

EXAMPLES Examples are given below to more specifically describe the features of the present invention. However, the scope of the present invention is not limited to the examples. In the following examples, unless otherwise specified, various measurements and evaluations are as follows.

[Measurement of dimensional change rate]
The dimensional change rate was measured by the following procedure. First, using a test piece of 150 mm square, a target for position measurement is formed by exposing and developing a dry film resist at intervals of 100 mm. After measuring the dimensions before etching (normal state) in an atmosphere with a temperature of 23 ± 2 ° C and a relative humidity of 50 ± 5%, the copper other than the target of the test piece is etched (liquid temperature 40 ° C or less, time within 10 minutes) Remove by After standing for 24±4 hours in an atmosphere with a temperature of 23±2° C. and a relative humidity of 50±5%, the dimensions after etching are measured. The dimensional change rate with respect to the normal state at each of three points in the MD direction (longitudinal direction) and the TD direction (width direction) is calculated, and the average value of each is taken as the dimensional change rate after etching. The post-etching dimensional change rate was calculated by the following formula.

Post-etching dimensional change rate (%) = (B - A) / A x 100
A; Distance between targets before etching B; Distance between targets after etching

Next, this test piece is heat-treated in an oven at 250° C. for 1 hour, and the distance between the position targets after that is measured. The dimensional change rate after etching at each of three points in the MD direction (longitudinal direction) and the TD direction (width direction) is calculated, and the average value of each is taken as the dimensional change rate after heat treatment. The heating dimensional change rate was calculated by the following formula.

Dimensional change rate after heating (%) = (C - B) / B x 100
B; Distance between targets after etching C; Distance between targets after heating

[Measurement of viscosity]
The viscosity at 25° C. was measured using an E-type viscometer (manufactured by Brookfield, trade name: DV-II+Pro). The number of revolutions was set so that the torque was 10% to 90%, and after 2 minutes from the start of the measurement, the value was read when the viscosity stabilized.

[Measurement of coefficient of thermal expansion (CTE)]
A polyimide film with a size of 3 mm × 20 mm is heated from 30 ° C. to 300 ° C. at a constant heating rate while applying a load of 5.0 g using a thermomechanical analyzer (manufactured by Bruker, trade name; 4000SA). Further, after holding at that temperature for 10 minutes, it was cooled at a rate of 5°C/min, and the average thermal expansion coefficient (thermal expansion coefficient) from 250°C to 100°C was determined.

[Measurement of storage modulus and glass transition temperature (Tg)]
A resin sheet with a size of 5 mm × 20 mm was heated from 30 ° C. to 400 ° C. at a rate of 4 ° C./min using a dynamic viscoelasticity measuring device (DMA: manufactured by UBM, trade name: E4000F). Measurements were made at a frequency of 11 Hz. The glass transition temperature was defined as the temperature at which the change in elastic modulus (tan δ) was maximum.

[Measurement of permittivity and dissipation factor]
A vector network analyzer (manufactured by Agilent, trade name E8363C) and an SPDR resonator were used to measure the permittivity and dielectric loss tangent of the resin sheet at 10 GHz. The materials used for the measurement were left for 24 hours under the conditions of temperature: 24-26°C and humidity: 45°C-55% RH.

[Measurement of surface roughness of copper foil]
AFM (manufactured by Bruker AXS, trade name: Dimension Icon type SPM), probe (manufactured by Bruker AXS, trade name: TESPA (NCHV), tip curvature radius 10 nm, spring constant 42 N / m) Then, in the tapping mode, the area of 80 μm×80 μm on the surface of the copper foil was measured to obtain the ten-point average roughness (Rzjis).

The abbreviations used in Synthesis Examples represent the following compounds.
o BPDA: 3,3',4,4'-biphenyltetracarboxylic dianhydride o BPADA: 2,2-bis[4-(3,4-dicarboxyphenoxy)phenyl]propane dianhydride o PMDA: pyro Melitic dianhydride ○ BTDA: 3,3',4,4'-benzophenonetetracarboxylic dianhydride ○ m-TB: 2,2'-dimethyl-4,4'-diaminobiphenyl ○ TPE-R: 1 ,3-bis(4-aminophenoxy)benzene ○ Bisaniline-M: 1,3-bis[2-(4-aminophenyl)-2-propyl]benzene ○ BAPP: 2,2-bis[4-(4- Aminophenoxy)phenyl]propane DDA: Aliphatic diamine having 36 carbon atoms (manufactured by Croda Japan Co., Ltd., trade name; PRIAMINE 1074, amine value: 205 mgKOH/g, mixture of dimer diamine with cyclic structure and chain structure, dimer component content; 95% by weight or more)
〇DMAc: N,N-dimethylacetamide 〇NMP: N-methyl-2-pyrrolidone 〇N-12: Dodecanedioic acid dihydrazide 〇OP935: Organic phosphinate aluminum salt (manufactured by Clariant Japan, trade name; Exolit OP935)
○ R710: (trade name, manufactured by Printec Co., Ltd., bisphenol type epoxy resin, epoxy equivalent 170, liquid at room temperature, weight average molecular weight: about 340)
○ VG3101L: (trade name, manufactured by Printec Co., Ltd., polyfunctional epoxy resin, epoxy equivalent: 210, softening point: 39 to 46 ° C.)
○ SR35K: (trade name, manufactured by Printec Co., Ltd., epoxy resin, epoxy equivalent: 930 to 940, softening point: 86 to 98 ° C.)
〇 YDCN-700-10: (trade name, manufactured by Nippon Steel Chemical & Materials Co., Ltd., cresol novolak type epoxy resin, epoxy equivalent 210, softening point 75 to 85 ° C.)
○ Milex XLC-LL: (trade name, manufactured by Mitsui Chemicals, Inc., phenolic resin, hydroxyl equivalent: 175, softening point: 77 ° C., water absorption: 1% by mass, mass reduction rate on heating: 4% by mass)
〇HE200C-10: (trade name, manufactured by Air Water Inc., phenolic resin, hydroxyl equivalent: 200, softening point: 65 to 76°C, water absorption: 1% by mass, mass reduction rate upon heating: 4% by mass)
〇HE910-10: (trade name, manufactured by Air Water Inc., phenolic resin, hydroxyl equivalent: 101, softening point: 83°C, water absorption: 1% by mass, mass reduction rate upon heating: 3% by mass)
○ SC1030-HJA: (trade name, manufactured by Admatechs Co., Ltd., silica filler dispersion, average particle size: 0.25 μm)
○ Aerosil R972: (trade name, manufactured by Nippon Aerosil Co., Ltd., silica, average particle size: 0.016 μm)
○Acrylic rubber HTR-860P-30B-CHN: (Sample name, manufactured by Teikoku Kagaku Sangyo Co., Ltd., weight average molecular weight: 230,000, glycidyl functional group monomer ratio: 8%, Tg: -7°C)
○Acrylic rubber HTR-860P-3CSP: (Sample name, manufactured by Teikoku Kagaku Sangyo Co., Ltd., weight average molecular weight: 800,000, glycidyl functional group monomer ratio: 3%, Tg: -7°C)
○A-1160: (trade name, manufactured by GE Toshiba Corporation, γ-ureidopropyltriethoxysilane)
○A-189: (trade name, manufactured by GE Toshiba Corporation, γ-mercaptopropyltrimethoxysilane)
○ Curesol 2PZ-CN: (trade name, manufactured by Shikoku Chemical Industry Co., Ltd., 1-cyanoethyl-2-phenylimidazole)
○ RE-810NM: (trade name, manufactured by Nippon Kayaku Co., Ltd., diallyl bisphenol A diglycidyl ether (property: liquid))
○ Follett SCS: (trade name, manufactured by Soken Chemical Co., Ltd., styryl group-containing acrylic polymer (Tg: 70 ° C., weight average molecular weight: 15000))
○ BMI-1: (trade name, manufactured by Tokyo Kasei Co., Ltd., 4,4'-bismaleimide diphenylmethane)
○ TPPK: (trade name, manufactured by Tokyo Kasei Co., Ltd., tetraphenylphosphonium tetraphenylborate)
〇 HP-P1: (Product name, manufactured by Mizushima Ferroalloy Co., Ltd., boron nitride filler)

(Synthesis example 1)
<Preparation of resin solution A for adhesive layer>
Cyclohexanone was added to a composition consisting of (a) an epoxy resin and a phenolic resin as thermosetting resins and (c) an inorganic filler having the product names and composition ratios (unit: parts by mass) shown in Table 1, followed by stirring and mixing. To this, (b) acrylic rubber as a high-molecular-weight component shown in Table 1 is added and stirred, and (e) a coupling agent and (d) a curing accelerator shown in Table 1 are added to homogenize each component. The resin solution A for the adhesive layer was obtained by stirring until the

(Synthesis example 2)
<Synthesis of Polyimide Resin (PI-1) and Preparation of Resin Solution B for Adhesive Layer>
1,3-bis(3-aminopropyl)tetramethyldisiloxane (manufactured by Shin-Etsu Chemical Co., Ltd., trade name: LP-7100) is placed in a 300 mL flask equipped with a thermometer, stirrer, condenser, and nitrogen inlet tube. 15.53 g, 28.13 g of polyoxypropylene diamine (manufactured by BASF Corporation, trade name: D400, molecular weight: 450), and 100.0 g of NMP were charged and stirred to prepare a reaction solution. After the diamine was dissolved, 32.30 g of 4,4'-oxydiphthalic dianhydride previously purified by recrystallization from acetic anhydride was added little by little to the reaction solution while cooling the flask in an ice bath. After reacting at room temperature (25° C.) for 8 hours, 67.0 g of xylene was added, and the mixture was heated at 180° C. while blowing nitrogen gas, thereby removing xylene and water azeotropically. The reaction solution was poured into a large amount of water, and the precipitated resin was collected by filtration and dried to obtain a polyimide resin (PI-1). When the molecular weight of the obtained polyimide resin (PI-1) was measured by GPC, it was found to have a number average molecular weight Mn of 22,400 and a weight average molecular weight Mw of 70,200 in terms of polystyrene.
Using the polyimide resin (PI-1) obtained above, each component was blended in the composition ratio (unit: parts by mass) shown in Table 2 to obtain a resin solution B for an adhesive layer.

(Synthesis Example 3)
<Preparation of resin solution C for adhesive layer>
In a 500 mL 4-necked flask equipped with a nitrogen inlet tube, stirrer, thermocouple, Dean-Stark trap, and condenser, 44.92 g BTDA (0.139 mol), 75.08 g DDA (0.141 mol), 168 g of NMP and 112 g of xylene were charged and mixed at 40° C. for 30 minutes to prepare a polyamic acid solution. This polyamic acid solution was heated to 190° C., heated and stirred for 4 hours, and distilled water and xylene were removed from the system. Then, it is cooled to 100° C., 112 g of xylene is added and stirred, and further cooled to 30° C. to complete imidation, and the resin solution C for adhesive layer (solid content: 29.5% by weight, weight average molecular weight 75,700).

(Synthesis Example 4)
<Preparation of resin solution D for adhesive layer>
42.51 g of BPADA (0.082 mol), 34.30 g of DDA (0.066 mol), 6.56 g of BAPP (0.016 mol), 208 g of NMP and 112 g of xylene except that the raw material composition was A polyamic acid solution was prepared in the same manner as in Synthesis Example 3. This polyamic acid solution was treated in the same manner as in Synthesis Example 3 to obtain an adhesive layer resin solution D (solid content: 30.0% by weight, weight average molecular weight: 65,000).

(Synthesis Example 5)
<Preparation of polyamic acid solution 1 for insulating resin layer>
Under a nitrogen stream, 64.20 g of m-TB (0.302 mol) and 5.48 g of bisaniline-M (0.016 mol) were added to the reactor, and an amount that would give a solid content concentration of 15% by weight after polymerization. of DMAc was added and dissolved by stirring at room temperature. Next, after adding 34.20 g of PMDA (0.157 mol) and 46.13 g of BPDA (0.157 mol), the polymerization reaction was carried out at room temperature for 3 hours with continuous stirring, polyamic acid solution 1 (viscosity: 26,500 cps) were prepared.

(Synthesis Example 6)
<Preparation of polyamic acid solution 2 for insulating resin layer>
69.56 g of m-TB (0.328 mol), 542.75 g of TPE-R (1.857 mol), DMAc in an amount to give a solids concentration of 12% by weight after polymerization, 194.39 g of PMDA ( A polyamic acid solution 2 (viscosity: 2,650 cps) was prepared in the same manner as in Synthesis Example 3, except that 0.891 mol) and 393.31 g of BPDA (1.337 mol) were used as the raw material composition.

(Production example 1)
<Preparation of resin sheet A for adhesive layer>
After coating the silicone-treated surface of the release substrate (length × width × thickness = 320 mm × 240 mm × 25 μm) so that the thickness after drying the resin solution A for the adhesive layer is 50 μm, it is heated at 80 ° C. for 15 minutes. After drying by heating for 1 minute, drying at 120° C. for 15 minutes, the resin sheet A was prepared by peeling from the release substrate. Further, the resin sheet A was heated in an oven at 120° C. for 2 hours and at 170° C. for 3 hours in order to evaluate physical properties after curing. At that time, the cured resin sheet A had a Tg of 95°C, a storage modulus of 960 MPa at 50°C, and a maximum storage modulus of 7 MPa from 180°C to 260°C.

(Production example 2)
<Preparation of resin sheet B for adhesive layer>
After coating the silicone-treated surface of the release substrate (length × width × thickness = 320 mm × 240 mm × 25 μm) so that the thickness after drying the resin solution B for the adhesive layer is 50 μm, it is heated at 80 ° C. for 15 minutes. The resin sheet B was prepared by heat-drying for 1 minute, further drying at 120° C. for 15 minutes, and peeling off from the release substrate. Further, resin sheet B was heated in an oven at 120° C. for 2 hours and at 170° C. for 3 hours in order to evaluate physical properties after curing. At that time, the cured resin sheet B had a Tg of 100°C or less, a storage modulus of 1800 MPa or less at 50°C, and a maximum storage modulus of 70 MPa from 180°C to 260°C.

(Production example 3)
<Preparation of resin sheet C for adhesive layer>
169.49 g (50 g as solid content) of resin solution C for the adhesive layer was blended with 1.8 g of N-12 (0.0036 mol) and 12.5 g of OP935, 6.485 g of NMP and 19.345 g of xylene was added to dilute the polyimide varnish 1.

Polyimide varnish 1 was applied to the silicone-treated surface of the release substrate (length x width x thickness = 320 mm x 240 mm x 25 µm) so that the thickness after drying was 50 µm, and then dried by heating at 80 ° C. for 15 minutes. , to prepare a resin sheet C by peeling from the release substrate. The resin sheet C had a Tg of 78°C, a storage modulus of 800 MPa at 50°C, and a maximum storage modulus of 10 MPa from 180°C to 260°C. Also, the dielectric constant (Dk) and dielectric loss tangent (Df) were 2.68 and 0.0028, respectively.

(Production example 4)
<Preparation of resin sheet D for adhesive layer>
After coating the silicone-treated surface of the release substrate (length × width × thickness = 320 mm × 240 mm × 25 μm) so that the thickness after drying the resin solution D for the adhesive layer is 50 μm, it is heated at 80 ° C. for 15 minutes. A resin sheet D was prepared by heat-drying for 1 minute and peeling off from the release substrate. Resin sheet D had a Tg of 82° C., a storage modulus of 1800 MPa or less at 50° C., and a maximum value of 2 MPa or less between 180° C. and 260° C. Also, the dielectric constant (Dk) and dielectric loss tangent (Df) were 2.80 and 0.0026, respectively.

(Production example 5)
<Preparation of single-sided metal-clad laminate>
On a copper foil 1 (electrolytic copper foil, thickness: 12 μm, surface roughness Rz on the resin layer side: 0.6 μm), polyamic acid solution 2 is evenly applied so that the thickness after curing is about 2 to 3 μm. After coating, the solvent was removed by heating and drying at 120°C. Next, polyamic acid solution 1 was uniformly applied thereon so that the thickness after curing was about 21 μm, and dried by heating at 120° C. to remove the solvent. Further, the polyamic acid solution 2 was applied evenly thereon so that the thickness after curing was about 2 to 3 μm, and then dried by heating at 120° C. to remove the solvent. Further, stepwise heat treatment was performed from 120° C. to 360° C. to complete imidization, and a single-sided metal-clad laminate 1 was prepared. The dimensional change rate of the single-sided metal-clad laminate 1 is as follows.
Dimensional change rate after etching in MD direction (longitudinal direction); 0.01%
Dimensional change rate after etching in the TD direction (width direction); -0.04%
Dimensional change after heating in MD direction (longitudinal direction); -0.03%
Dimensional change rate after heating in the TD direction (width direction); -0.01%
In addition, the polyimide film 1 (thickness: 25 μm) prepared by etching away the copper foil 1 of the single-sided metal clad laminate 1 using an aqueous ferric chloride solution has a CTE of 20.0 ppm/K and a dielectric constant (Dk ) and dielectric loss tangent (Df) were 3.40 and 0.0029, respectively.

[Example 1]
After coating the resin solution A for the adhesive layer on the resin surface of the single-sided metal-clad laminate 1 so that the thickness after drying is 50 μm, it is dried by heating at 80° C. for 15 minutes, and further dried at 120° C. for 15 minutes. By doing so, a single-sided metal-clad laminate 1 with an adhesive layer was prepared. Further, the adhesive layer-attached single-sided metal-clad laminate 1 was heated in an oven at 120° C. for 2 hours and at 170° C. for 3 hours in order to evaluate physical properties after the adhesive layer was cured. The evaluation results of the adhesive layer-attached single-sided metal-clad laminate 1 after heating are as follows.
Dimensional change rate after etching in MD direction; -0.05%
Dimensional change rate after etching in the TD direction; -0.02%
Dimensional change rate after heating in MD direction; -0.01%
Dimensional change rate after heating in TD direction; -0.03%
There was no problem with the dimensional change of the adhesive layer-attached single-sided metal-clad laminate 1 after heating. The CTE of the resin laminate 1 (thickness: 75 μm) prepared by etching away the copper foil 1 in the single-sided metal-clad laminate 1 with an adhesive layer after heating was 26.2 ppm/K.

[Example 2]
After coating the resin solution B for the adhesive layer on the resin surface of the single-sided metal-clad laminate 1 so that the thickness after drying is 50 μm, it is dried by heating at 80° C. for 15 minutes, and further dried at 120° C. for 15 minutes. By doing so, a single-sided metal-clad laminate 2 with an adhesive layer was prepared. Further, the adhesive layer-attached single-sided metal-clad laminate 2 was heated in an oven at 120° C. for 2 hours and at 170° C. for 3 hours in order to evaluate physical properties after the adhesive layer was cured. The evaluation results of the adhesive layer-attached single-sided metal-clad laminate 2 after heating are as follows.
Dimensional change rate after etching in MD direction; -0.08%
Dimensional change rate after etching in TD direction; -0.06%
Dimensional change rate after heating in MD direction; -0.03%
Dimensional change rate after heating in TD direction; -0.06%
There was no problem with the dimensional change of the adhesive layer-attached single-sided metal-clad laminate 2 after heating. The CTE of the resin laminate 2 (thickness: 75 μm) prepared by etching away the copper foil 1 in the single-sided metal-clad laminate 2 with an adhesive layer after heating was 25.0 ppm/K.

[Example 3]
Polyimide varnish 1 is applied to the resin surface of single-sided metal-clad laminate 1 so that the thickness after drying is 50 μm, and then dried by heating at 80° C. for 15 minutes to obtain single-sided metal-clad laminate 3 with an adhesive layer. prepared. The single-sided metal-clad laminate 3 with an adhesive layer was heated in an oven at 180° C. for 1 minute and then at 150° C. for 30 minutes, and the evaluation results are as follows.
Dimensional change rate after etching in MD direction; -0.05%
Dimensional change rate after etching in TD direction; -0.04%
Dimensional change rate after heating in MD direction; 0.05%
Dimensional change rate after heating in TD direction; 0.01%
There was no problem with the dimensional change of the adhesive layer-attached single-sided metal-clad laminate 3 after heating. In addition, the CTE in the resin laminate 3 (thickness: 75 μm) prepared by etching away the copper foil 1 in the single-sided metal-clad laminate 3 with an adhesive layer after heating was 25.6 ppm/K, and the dielectric constant (Dk) and dielectric loss tangent (Df) were 2.92 and 0.0028, respectively.

[Example 4]
After coating the resin solution D for the adhesive layer on the resin surface of the single-sided metal-clad laminate 1 so that the thickness after drying becomes 50 μm, it is dried by heating at 80° C. for 15 minutes to obtain a single-sided metal-clad with adhesive layer. Laminate 4 was prepared. In addition, the single-sided metal-clad laminate 4 with an adhesive layer was evaluated after being heated in an oven at 180°C for 1 minute and at 150°C for 30 minutes. ) were 3.00 and 0.0027, respectively.

[Example 5]
Liquid crystal polymer film (manufactured by Kuraray Co., Ltd., trade name: CT-Z, thickness: 25 μm, CTE: 18 ppm/K, heat distortion temperature: 300 ° C., Dk: 3.40, Df: 0.0022) as an insulating substrate , a double-sided metal-clad laminate 1 provided with copper foils 1 on both sides was prepared. A single-sided metal-clad laminate 2 was prepared by removing the copper foil 1 on one side of the double-sided metal-clad laminate 1 by etching.

Polyimide varnish 1 is applied to the resin surface of single-sided metal-clad laminate 2 so that the thickness after drying is 50 μm, and then dried by heating at 80° C. for 15 minutes to obtain single-sided metal-clad laminate 5 with an adhesive layer. prepared. In addition, the single-sided metal-clad laminate 5 with an adhesive layer was evaluated after being heated in an oven at 180°C for 1 minute and at 150°C for 30 minutes. ) were 2.92 and 0.0026, respectively.

[Example 6]
The resin solution D for the adhesive layer is applied to the resin surface of the single-sided metal-clad laminate 2 so that the thickness after drying is 50 μm, and then dried by heating at 80° C. for 15 minutes to obtain a single-sided metal-clad adhesive layer. Laminate 6 was prepared. In addition, the single-sided metal-clad laminate 6 with an adhesive layer was evaluated after being heated in an oven at 180° C. for 1 minute and at 150° C. for 30 minutes. ) were 3.00 and 0.0025, respectively.

[Example 7]
Copper foil 1 of single-sided metal-clad laminate 1 was subjected to circuit processing by a subtractive method to prepare single-sided wiring board 1 having a conductor circuit layer formed thereon. At the same time, the copper foils 1 of the two adhesive layer-attached single-sided metal-clad laminates 3 were subjected to circuit processing by a subtractive method to prepare two adhesive layer-attached single-sided wiring boards 1 each having a conductive circuit layer formed thereon. .

The conductor circuit layer of the single-sided wiring board 1 and the adhesive layer of the single-sided wiring board 1 with an adhesive layer, the conductor circuit layer of the single-sided wiring board 1 with an adhesive layer and the adhesive layer of the single-sided wiring board 1 with another adhesive layer After superimposing them so as to face each other, the multilayer circuit board 1 was prepared by thermocompression bonding for 60 minutes under conditions of 160° C. and 4 MPa. On the crimping surface of the multilayer circuit board 1, the conductive circuit layer was sufficiently filled with the adhesive, and no disturbance of the conductor circuit due to the thermocompression bonding process occurred.

[Example 8]
After preparing two single-sided wiring boards 1 with an adhesive layer and superimposing them so that the adhesive layer of one single-sided wiring board 1 with an adhesive layer faces the adhesive layer of another single-sided wiring board 1 with an adhesive layer, A double-sided circuit board 1 was prepared by thermocompression bonding at 160° C. and 4 MPa for 60 minutes. On the pressure-bonding surface of the double-sided circuit board 1, the adhesive layers were sufficiently bonded to each other, and no disturbance of the conductor circuit caused by the thermocompression bonding process occurred.

[Example 9]
Copper foils 1 of two adhesive layer-attached single-sided metal-clad laminates 4 were subjected to circuit processing by a subtractive method to prepare two adhesive layer-attached single-sided wiring boards 2 on which conductor circuit layers were formed.

The conductor circuit layer of the single-sided wiring board 1 and the adhesive layer of the single-sided wiring board 2 with an adhesive layer, the conductor circuit layer of the single-sided wiring board 2 with an adhesive layer and the adhesive layer of the single-sided wiring board 2 with another adhesive layer After superimposing them so as to face each other, the multilayer circuit board 2 was prepared by thermocompression bonding for 60 minutes under conditions of 160° C. and 4 MPa. On the crimping surface of the multilayer circuit board 2, the conductor circuit layer was sufficiently filled with the adhesive, and no disturbance of the conductor circuit caused by the thermocompression bonding process occurred.

[Example 10]
After preparing two single-sided wiring boards 2 with an adhesive layer and superimposing them so that the adhesive layer of one single-sided wiring board 2 with an adhesive layer faces the adhesive layer of another single-sided wiring board 2 with an adhesive layer, A double-sided circuit board 2 was prepared by thermocompression bonding at 160° C. and 4 MPa for 60 minutes. On the pressure-bonding surface of the double-sided circuit board 2, the adhesive layers were sufficiently bonded to each other, and no disturbance of the conductor circuit caused by the thermocompression bonding process occurred.

[Example 11]
The copper foil 1 of the single-sided metal-clad laminate 2 was subjected to circuit processing by a subtractive method to prepare a single-sided wiring board 2 having a conductor circuit layer formed thereon. At the same time, the copper foils 1 of the two adhesive layer-attached single-sided metal-clad laminates 5 were subjected to circuit processing by a subtractive method to prepare two adhesive layer-attached single-sided wiring boards 3 on which conductor circuit layers were formed. .

The conductor circuit layer of the single-sided wiring board 2 and the adhesive layer of the single-sided wiring board 3 with the adhesive layer, the conductor circuit layer of the single-sided wiring board 3 with the adhesive layer and the adhesive layer of the single-sided wiring board 3 with the adhesive layer After superimposing them so as to face each other, the multilayer circuit board 3 was prepared by thermocompression bonding for 60 minutes under conditions of 160° C. and 4 MPa. On the crimping surface of the multilayer circuit board 3, the conductive circuit layer was sufficiently filled with the adhesive, and the conductor circuit was not disturbed due to the thermocompression bonding process.

[Example 12]
After preparing two single-sided wiring boards 3 with an adhesive layer and superimposing them so that the adhesive layer of one single-sided wiring board 3 with an adhesive layer faces the adhesive layer of another single-sided wiring board 3 with an adhesive layer, A double-sided circuit board 3 was prepared by thermocompression bonding for 60 minutes at 160° C. and 4 MPa. On the crimped surface of the double-sided circuit board 3, the adhesive layers were sufficiently bonded to each other, and no disorder of the conductor circuit due to the thermocompression bonding process occurred.

[Example 13]
Copper foils 1 of two single-sided metal-clad laminates 6 with an adhesive layer were subjected to circuit processing by a subtractive method to prepare two single-sided wiring boards 4 with an adhesive layer on which a conductor circuit layer was formed.

The conductor circuit layer of the single-sided wiring board 2 and the adhesive layer of the single-sided wiring board 4 with an adhesive layer, the conductor circuit layer of the single-sided wiring board 4 with an adhesive layer and the adhesive layer of the single-sided wiring board 4 with another adhesive layer A multilayer circuit board 4 was prepared by stacking them so as to face each other and thermally compressing them for 60 minutes under the conditions of 160° C. and 4 MPa. On the crimping surface of the multilayer circuit board 4, the conductive circuit layer was sufficiently filled with the adhesive, and the conductor circuit was not disturbed due to the thermocompression bonding process.

[Example 14]
After preparing two single-sided wiring boards 4 with an adhesive layer and superimposing them so that the adhesive layer of one single-sided wiring board 4 with an adhesive layer faces the adhesive layer of another single-sided wiring board 4 with an adhesive layer, A double-sided circuit board 4 was prepared by thermocompression bonding at 160° C. and 4 MPa for 60 minutes. On the pressure-bonding surface of the double-sided circuit board 4, the adhesive layers were sufficiently bonded to each other, and no disturbance of the conductor circuit caused by the thermocompression bonding process occurred.

Although the embodiments of the present invention have been described above in detail for the purpose of illustration, the present invention is not limited to the above embodiments and various modifications are possible.

DESCRIPTION OF SYMBOLS 10... Insulating resin layer 20... Metal layer 30... Adhesive layer 40... Single-sided metal clad laminate 50... Conductor circuit layer 100... Metal clad laminate 101... Circuit board 102... Circuit board unit 110... Arbitrary circuit boards, 200, 201... multilayer circuit boards

Claims (3)

preparing a plurality of circuit boards each having an insulating resin layer, a conductive circuit layer formed on one surface of the insulating resin layer, and an adhesive layer laminated on the other surface of the insulating resin layer; as well as,
stacking and press-bonding the conductive circuit layer of one of the circuit boards and the adhesive layer of the other circuit board so as to face each other;
A method for manufacturing a multilayer circuit board comprising
The resin constituting the adhesive layer is an adhesive polyimide containing a tetracarboxylic acid residue and a diamine residue,
The adhesive polyimide is derived from a dimer acid-type diamine obtained by substituting two terminal carboxylic acid groups of a dimer acid with a primary aminomethyl group or an amino group with respect to the total amount of 100 mol parts of the diamine residue. A method for producing a multilayer circuit board, comprising 50 mol parts or more of a diamine residue. The adhesive polyimide is a tetracarboxylic acid derived from a tetracarboxylic anhydride represented by the following general formula (1) and / or (2) with respect to 100 mol parts of the total amount of the tetracarboxylic acid residue 2. The method for producing a multilayer circuit board according to claim 1, wherein the residue is contained in a total of 90 mol parts or more.

[In the general formula (1), X represents a single bond or a divalent group selected from the following formula, and in the general formula (2), the cyclic portion represented by Y is a 4-membered ring, a 5-membered ring, It represents forming a cyclic saturated hydrocarbon group selected from a ring, a 6-membered ring, a 7-membered ring and an 8-membered ring. ]

[In the above formula, Z represents -C ₆ H ₄ -, -(CH ₂ )n- or -CH ₂ -CH(-O-C(=O)-CH ₃ )-CH ₂ -, where n is Indicates an integer from 1 to 20. ] The adhesive polyimide contains 50 mol parts or more and 99 mol parts or less of diamine residues derived from the dimer acid-type diamine with respect to the total amount of 100 mol parts of the diamine residues,
1 to 50 mol parts of a diamine residue derived from at least one diamine compound selected from diamine compounds represented by the following general formulas (B1) to (B7): 2. The method for producing a multilayer circuit board according to 1.

[In the formulas (B1) to (B7), R ₁ independently represents a monovalent hydrocarbon group or an alkoxy group having 1 to 6 carbon atoms, and the linking group A independently represents -O-, -S-, -CO a divalent group selected from -, -SO-, -SO ₂ -, -COO-, -CH ₂ -, -C(CH ₃ ) ₂ -, -NH- or -CONH-, n ₁ is independent indicates an integer from 0 to 4. However, the formula (B3) that overlaps with the formula (B2) is excluded, and the formula (B5) that overlaps with the formula (B4) is excluded. ]

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