JP7381185B2 - Circuit boards and multilayer circuit boards - Google Patents

Description

The present invention relates to a circuit board and a multilayer circuit board.

BACKGROUND ART In recent years, as electronic devices have become more dense and highly functional, circuit board materials with even greater dimensional stability and superior high frequency properties are required. 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 having a dielectric layer made of liquid crystal polymer (LCP), which is characterized by low dielectric constant and low dielectric loss tangent, has been proposed (for example, Patent Document 1). Multilayer wiring boards with liquid crystal polymer as an insulating layer are manufactured by heat-pressing the liquid crystal polymer base material, which is a thermoplastic resin, after heating it to around the melting point. It is feared that the position of the capacitor may easily shift, which may adversely affect electrical characteristics such as impedance mismatch. In addition, in multilayer wiring boards with liquid crystal polymer as the base material layer, if the multilayer adhesive interface is smooth, the anchor effect will not occur and the interlayer adhesion will be insufficient. There was also the problem that a roughening treatment was required and the manufacturing process was complicated.

By the way, as technologies related to adhesive layers containing polyimide as a main component, there are two methods: polyimide made from a diamine compound derived from an aliphatic diamine such as dimer acid, and an amino compound having at least two primary amino groups as functional groups. It has been proposed to apply a crosslinked polyimide resin obtained by reacting , to an adhesive layer of a coverlay film (for example, Patent Document 2). The crosslinked polyimide resin of Patent Document 2 does not generate volatile components made of cyclic siloxane compounds, has excellent soldering heat resistance, and maintains the adhesive strength between the wiring layer and the coverlay film even in environments where it is repeatedly exposed to high temperatures. This has the advantage of not causing any deterioration. However, in Patent Document 2, the applicability to high frequency signal transmission is not considered.

Japanese Patent Application Publication No. 2005-317953 Patent No. 5777944

An object of the present invention is to provide a circuit board and a multilayer circuit board equipped with an adhesive layer that has excellent adhesion, low dielectric constant and dielectric loss tangent, and can reduce transmission loss even in high frequency transmission.

As a result of intensive research, the present inventors have found that in a circuit board having an insulating base layer made of a liquid crystal polymer and a conductive circuit layer, an adhesive polyimide that can be bonded by thermocompression is used as an adhesive layer covering the conductive circuit layer. In addition, they discovered that by controlling the type and amount of monomers that are raw materials for the adhesive polyimide, it is possible to lower the dielectric constant and dielectric loss tangent while maintaining excellent adhesive properties, and have developed the present invention. completed.

The circuit board of the present invention includes an insulating base layer made of a liquid crystal polymer, a conductive circuit layer formed on at least one side of the insulating base layer, and an adhesive layer covering the conductive circuit layer. It is a board.
In the circuit board of the present invention, the adhesive layer has an adhesive polyimide containing a tetracarboxylic acid residue and a diamine residue,
The adhesive polyimide contains, based on 100 mole parts of the diamine residue,
It is characterized by containing 40 mole parts or more of a diamine residue derived from a dimer acid type diamine in which two terminal carboxylic acid groups of a dimer acid are substituted with primary aminomethyl groups or amino groups.

In the circuit board of the present invention, the adhesive polyimide comprises:
It is characterized by containing a total of 90 mole parts or more of tetracarboxylic acid residues derived from tetracarboxylic acid anhydrides represented by the following general formulas (1) and/or (2).

［一般式（１）中、Ｘは、単結合、または、下式から選ばれる２価の基を示し、一般式（２）中、Ｙで表される環状部分は、４員環、５員環、６員環、７員環又は８員環から選ばれる環状飽和炭化水素基を形成していることを表す。］

[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 moiety 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, or an 8-membered ring. ]

[上記式において、Ｚは－Ｃ_６Ｈ_４－、－(ＣＨ_２)ｎ－又は－ＣＨ_２－ＣＨ(－Ｏ－Ｃ(＝Ｏ)－ＣＨ_３)－ＣＨ_２－を示すが、ｎは１～２０の整数を示す。]

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

In the circuit board of the present invention, the adhesive polyimide comprises:
The diamine residue derived from the dimer acid type diamine may be contained within the range of 50 mole parts or more and 99 mole parts or less,
The diamine residue derived from at least one diamine compound selected from the diamine compounds represented by the following general formulas (B1) to (B7) may be contained in the range of 1 to 50 mole parts. good.

［式（Ｂ１）～（Ｂ７）において、Ｒ_１は独立に炭素数１～６の１価の炭化水素基又はアルコキシ基を示し、連結基Ａは独立に－Ｏ－、－Ｓ－、－ＣＯ－、－ＳＯ－、－ＳＯ_２－、－ＣＯＯ－、－ＣＨ_２－、－Ｃ（ＣＨ_３）_２－、－ＮＨ－若しくは－ＣＯＮＨ－から選ばれる２価の基を示し、ｎ_１は独立に０～４の整数を示す。ただし、式（Ｂ３）中から式（Ｂ２）と重複するものは除き、式（Ｂ５）中から式（Ｂ４）と重複するものは除くものとする。］

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

The multilayer circuit board of the present invention is a multilayer circuit board in which a plurality of circuit boards are laminated, and the circuit board is any one of the above circuit boards.

The circuit board of the present invention ensures adhesion, lowers the dielectric constant, and lowers the conductive circuit layer by forming an adhesive layer covering the conductor circuit layer using adhesive polyimide into which specific tetracarboxylic acid residues and diamine residues are introduced. This made it possible to change the dielectric loss tangent. Further, the multilayer circuit board of the present invention has good interlayer connections and is highly reliable, and can enable high-density integration and high-density packaging of electronic components.

FIG. 3 is an explanatory diagram showing a manufacturing process of a multilayer circuit board according to an embodiment of the present invention.

Embodiments of the present invention will be described in detail.

[Circuit board]
The circuit board of this embodiment has a conductor circuit layer on at least one side of an insulating base material layer made of a liquid crystal polymer, and the conductor circuit layer is covered with an adhesive layer. The high frequency characteristics of the circuit board of this embodiment can be ensured by the adhesive layer made of adhesive polyimide and the conductor circuit layer embedded inside, and the adhesive layer also has good low-temperature adhesion with the liquid crystal polymer. Therefore, it does not adversely affect the dielectric properties of the liquid crystal polymer. The adhesive layer covering the conductor circuit layer may partially cover the surface of the conductor circuit layer, or may cover the entire surface of the conductor circuit layer. Furthermore, the circuit board of this embodiment may have any conductive circuit layer other than the conductive circuit layer covered with the adhesive layer.

(Insulating base material layer)
The insulating base material layer is made of liquid crystal polymer. The liquid crystal polymer can be selected from various liquid crystal polymers such as those used as insulating base layers in commercially available liquid crystal polymer films or commercially available copper-clad laminates. As the liquid crystal polymer film, Vector (trade name) manufactured by Kuraray Co., Ltd., BIAC Film (trade name) manufactured by Primatec, etc. can be used. Further, as the copper-clad laminate, RF705T (trade name) manufactured by Panasonic Corporation or the like can be used.

The thickness of the insulating base layer is, for example, preferably in the range of 5 to 100 μm, more preferably in the range of 10 to 50 μm. If the thickness of the insulating base material layer is less than the above lower limit, problems such as insufficient electrical insulation may occur. On the other hand, if the thickness of the insulating base material layer exceeds the above upper limit, problems such as decreased dimensional stability will occur.

The liquid crystal polymer preferably has a coefficient of thermal expansion (CTE) within the range of 1 to 25 ppm/K, for example, from the viewpoint of obtaining stable dimensional accuracy of the circuit board.

Further, the heat distortion temperature of the liquid crystal polymer is preferably 180°C or higher, more preferably within the range of 210 to 330°C. If it is within this range, the production described below can be carried out easily and the liquid crystal polymer will not be adversely affected during heat bonding.

(conductor circuit layer)
The conductive circuit layer in the circuit board of this embodiment is not particularly limited as long as it is made of a conductive material, but examples include copper, stainless steel, iron, nickel, beryllium, aluminum, zinc, indium, and silver. , gold, tin, zirconium, tantalum, titanium, lead, magnesium, manganese and alloys thereof. Among these, copper or copper alloy is particularly preferred.

The conductive circuit layer can be formed by any method. For example, a metal foil containing copper as a main component is thermocompression bonded to an insulating base material layer to form an insulating base material layer having metal foil on one or both sides, and then a photosensitive resist is applied on the metal foil. A conductor circuit layer having a predetermined shape can be formed by performing exposure and development to form a predetermined mask pattern, etching the metal foil through the mask pattern, and then removing the mask pattern. Further, a conductor circuit layer having a predetermined shape may be formed on the insulating base material layer by inkjet or plating.

The thickness of the conductor circuit layer is not particularly limited, but for example, when copper foil is used as the material for the conductor circuit layer, it is preferably 35 μm or less, more preferably within the range of 5 to 25 μm. From the viewpoint of production stability and handling properties, the lower limit of the thickness of the copper foil is preferably 5 μm. In addition, when using copper foil, rolled copper foil or electrolytic copper foil may be used. Moreover, as the copper foil, commercially available copper foil can be used.

The surface of the conductor circuit layer in contact with the insulating base material layer is roughened, with a maximum height roughness (Rz) of 2, from the viewpoint of reducing transmission loss in high-frequency transmission and adhesion with the liquid crystal polymer. It is preferable that it is .0 μm or less. Transmission loss consists of the sum of conductor loss and dielectric loss, and when the Rz of the conductive circuit layer is large, the conductor loss becomes large. In other words, since it has an adverse effect on transmission loss, it is necessary to control Rz.

Note that an interlayer connection electrode (via electrode) may be formed in the insulating base material layer in addition to the conductor circuit layer. The interlayer connection electrode can be formed by forming a via hole in an insulating base material layer made of a liquid crystal polymer by laser processing or drilling, and then filling the via hole with a conductive paste by printing or the like. The conductive paste may be, for example, a mixture of a conductive powder containing tin as a main component and an organic solvent, an epoxy resin, or the like. Further, for the interlayer connection electrode, after forming a via hole, a plating portion may be formed on the inner surface of the via hole and a part of the surface of the conductive circuit layer.

(Adhesive layer)
The adhesive layer covers the conductive circuit layer. Moreover, a coverlay film or a solder resist may be provided as a protective layer on the adhesive layer, if necessary. After forming a conductive circuit layer in a predetermined pattern on one or both sides of an insulating base material layer made of a liquid crystal polymer, an adhesive layer is laminated thereon.

The adhesive polyimide constituting the adhesive layer is produced by imidizing a precursor polyamic acid obtained by reacting a specific acid anhydride and a diamine compound, so by explaining the acid anhydride and diamine compound, , specific examples of adhesive polyimides are understood. In the present invention, the term "tetracarboxylic acid residue" refers to a tetravalent group derived from tetracarboxylic dianhydride, and the term "diamine residue" refers to a divalent group derived from a diamine compound. means.

(tetracarboxylic acid residue)
The adhesive polyimide contains a tetracarboxylic acid residue derived from a tetracarboxylic anhydride represented by the following general formula (1) and/or (2) based on 100 mole parts of the tetracarboxylic acid residue ( Hereinafter, it is preferable to contain 90 mole parts or more in total of "tetracarboxylic acid residue (1)" and "tetracarboxylic acid residue (2)"). In the present invention, solvent solubility is imparted to the adhesive polyimide by containing the tetracarboxylic acid residues (1) and/or (2) in a total of 90 mol parts or more per 100 mol parts of the tetracarboxylic acid residues. This is preferable because it is easy to provide both flexibility and heat resistance of the adhesive polyimide. If the total amount of tetracarboxylic acid residues (1) and/or (2) is less than 90 parts by mole, the solvent solubility of the adhesive polyimide tends to decrease.

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 moiety represented by Y is a 4-membered ring or a 5-membered ring. , indicates the formation of a cyclic saturated hydrocarbon group selected from a 6-membered ring, a 7-membered ring, or 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 -, but n is 1 Indicates an integer between ~20.

Examples of the tetracarboxylic dianhydride for inducing the tetracarboxylic acid residue (1) include 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 Examples include bis(trimellitic acid monoester acid anhydride) (TAHQ) and ethylene glycol bisanhydrotrimellitate (TMEG).

In addition, examples of the tetracarboxylic dianhydride for inducing the tetracarboxylic acid residue (2) include 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- Examples include cyclooctanetetracarboxylic dianhydride.

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

(diamine residue)
The adhesive polyimide preferably contains dimer acid type diamine residues derived from dimer acid type diamine in an amount of 40 moles or more, for example 50 moles or more and 99 moles or less, per 100 moles of diamine residues. is contained within a range of 60 mole parts or more, for example, 60 mole parts or more and 99 mole parts or less. By containing the dimer acid type diamine residue in the above amount, the dielectric properties of the adhesive layer are improved, and the thermocompression bonding properties are improved and the elastic modulus is lowered by lowering the glass transition temperature (lower Tg) of the adhesive layer. It is possible to alleviate the internal stress caused by oxidation. If the amount of the dimer acid type diamine residue is less than 40 mol parts with respect to 100 mol parts of the diamine residue, sufficient adhesiveness with the liquid crystal polymer may not be obtained.

Here, a dimer acid type diamine is a diamine in which two terminal carboxylic acid groups (-COOH) of a dimer acid are substituted with a primary aminomethyl group (-CH ₂ --NH ₂ ) or an amino group (-NH ₂ ). It means a diamine. Dimer acid is a known dibasic acid obtained by intermolecular polymerization reaction of unsaturated fatty acids, and its industrial manufacturing process is almost standardized in the industry. It can be obtained by dimerization using etc. Industrially obtained dimer acids are mainly composed of dibasic acids with 36 carbon atoms obtained by dimerizing unsaturated fatty acids with 18 carbon atoms such as oleic acid and linoleic acid, but depending on the degree of purification, , any amount of monomer acid (18 carbon atoms), trimer acid (54 carbon atoms), and other polymerized fatty acids having 20 to 54 carbon atoms. In the present invention, it is preferable to use a dimer acid whose content of dimer acid has been increased to 90% by weight or more by molecular distillation. Further, although double bonds remain after the dimerization reaction, in the present invention, dimer acids also include those whose degree of unsaturation has been reduced by further hydrogenation reaction.

A feature of dimer acid type diamines is that they can impart properties derived from the dimer acid skeleton to polyimide. That is, since the dimer acid type diamine is a large aliphatic molecule with a molecular weight of approximately 560 to 620, it is possible to increase the molar volume of the molecule and relatively reduce the number of polar groups in polyimide. It is thought that such characteristics of the dimer acid type diamine contribute to improving the dielectric properties by reducing the dielectric constant and the dielectric loss tangent while suppressing a decrease in the heat resistance of polyimide. In addition, since it has two freely movable hydrophobic chains with 7 to 9 carbon atoms and two chain-like aliphatic amino groups with a length close to 18 carbon atoms, it not only gives polyimide flexibility, but also Since polyimide can be made to have an asymmetrical chemical structure or a non-planar chemical structure, it is thought that it is possible to lower the dielectric constant and dielectric loss tangent of polyimide.

Dimer acid diamines are commercially available, such as PRIAMINE 1073 (trade name), PRIAMINE 1074 (trade name), PRIAMINE 1075 (trade name) manufactured by Croda Japan, and Versamine 551 (trade name) manufactured by BASF Japan. ), Versamine 552 (trade name), etc.

In addition, the adhesive polyimide contains a diamine residue derived from at least one diamine compound selected from diamine compounds represented by the following general formulas (B1) to (B7), based on 100 mole parts of the total diamine component. The total content is preferably within the range of 1 mole part or more and 50 mole parts or less, and more preferably within the range of 1 mole part or more and 40 mole 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, polyimide molecules can be formed. It can improve chain flexibility and impart solvent solubility and thermoplasticity. Furthermore, even when forming via holes (through holes) in the adhesive layer by laser processing, for example, by increasing the proportion of aromatic rings in the polyimide molecular structure, it is possible to increase the absorption of ultraviolet rays, for example. The glass transition temperature of the bottom metal can be increased, thereby improving the heat resistance to the temperature rise of the bottom metal due to the heat input of laser light, thereby further improving laser processability. If the total amount of diamine compounds represented by general formulas (B1) to (B7) exceeds 50 mole parts based on 100 mole parts of all diamine components, the adhesive polyimide will lack flexibility and the Tg will increase. Therefore, residual stress due to thermocompression bonding increases, and the dimensional change rate after etching tends to worsen.

In formulas (B1) to (B7), R ₁ independently represents a monovalent hydrocarbon group or alkoxy group having 1 to 6 carbon atoms, and the linking group A independently represents -O-, -S-, -CO- , -SO-, -SO ₂ -, -COO-, -CH ₂ -, -C(CH ₃ ) ₂ -, -NH- or -CONH-, and n ₁ is independently Indicates an integer from 0 to 4. However, from equation (B3), those that overlap with equation (B2) are excluded, and from equation (B5), those that overlap with equation (B4) are excluded.
Note that "independently" means that in one or more of the above formulas (B1) to (B7), a plurality of linking groups A, a plurality of R ₁ or a plurality of n ₁ are the same. It means that it is okay and can be different. Furthermore, in formulas (B1) to (B7), the hydrogen atoms in the two terminal amino groups may be substituted, for example, -NR ₂ R ₃ (here, R ₂ and R ₃ are independently alkyl (means 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. This diamine (B1) has an amino group directly connected to at least one benzene ring and a divalent linking group A in the meta position, which increases the degree of freedom of the polyimide molecular chain and has high flexibility. It is thought that this contributes to improving the flexibility of polyimide molecular chains. Therefore, the use of diamine (B1) increases the thermoplasticity of polyimide. Here, as the linking group A, -O-, -CH ₂ -, -C(CH ₃ ) ₂ -, -CO-, -SO ₂ -, -S-, and -COO- are preferable.

Examples of the diamine (B1) include 3,3'-diaminodiphenylmethane, 3,3'-diaminodiphenylpropane, 3,3'-diaminodiphenyl sulfide, 3,3'-diaminodiphenyl sulfone, and 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, etc.

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 connected to at least one benzene ring and a divalent linking group A in the meta position, which increases the degree of freedom of the polyimide molecular chain and has high flexibility. It is thought that this contributes to improving the flexibility of polyimide molecular chains. Therefore, the use of diamine (B2) increases the thermoplasticity of polyimide. Here, the linking 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] Examples include benzeneamine and the like.

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 that are directly connected to one benzene ring and are located in the meta position of each other, which increases the degree of freedom of the polyimide molecular chain and has high flexibility. It is thought that this contributes to improving the flexibility of polyimide molecular chains. Therefore, the use of diamine (B3) increases the thermoplasticity of polyimide. Here, the linking 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 because the amino group directly connected to at least one benzene ring and the divalent linking group A are in the meta position, and it can improve the flexibility of the polyimide molecular chain. It is thought that this contributes. Therefore, the use of diamine (B4) increases the thermoplasticity of polyimide. Here, as the linking group A, -O-, -CH ₂ -, -C(CH ₃ ) ₂ -, -SO ₂ -, -CO-, and -CONH- are preferable.

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, and bis[4,4'-(3-aminophenoxy)]benzanilide.

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 that are directly connected to at least one benzene ring and are located in meta positions, so that the degree of freedom of the polyimide molecular chain increases and it has high flexibility. It is thought that this contributes to improving the flexibility of polyimide molecular chains. Therefore, the use of diamine (B5) increases the thermoplasticity of polyimide. Here, the linking 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, etc. .

The diamine represented by formula (B6) (hereinafter sometimes referred to as "diamine (B6)") is an aromatic diamine having four benzene rings. This diamine (B6) has high flexibility because it has at least two ether bonds, and is thought to contribute to improving the flexibility of the polyimide molecular chain. Therefore, the use of diamine (B6) increases the thermoplasticity of polyimide. Here, as the linking group A, -C(CH ₃ ) ₂ -, -O-, -SO ₂ -, and -CO- are preferable.

Examples of the diamine (B6) include 2,2-bis[4-(4-aminophenoxy)phenyl]propane (BAPP), bis[4-(4-aminophenoxy)phenyl]ether (BAPE), and bis[4-aminophenoxy)phenyl]ether (BAPE). Examples include -(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 divalent linking groups A with high flexibility on both sides of the diphenyl skeleton, it is thought that it contributes to improving the flexibility of the polyimide molecular chain. Therefore, the use of diamine (B7) increases the thermoplasticity of polyimide. Here, the linking 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. As the diamine residue derived from a diamine compound other than the dimer acid type diamine and diamines (B1) to (B7) mentioned above, those commonly used as diamine compounds used in thermoplastic polyimides can be used without limitation. .

In addition, in the adhesive polyimide, by selecting the types of the above-mentioned tetracarboxylic acid residues and diamine residues, and the molar ratio of two or more types of tetracarboxylic acid residues or diamine residues, it is possible to Expansion coefficient, tensile modulus, glass transition temperature, etc. can be controlled. Furthermore, when polyimide has a plurality of polyimide structural units, they may exist as blocks or randomly, but it is preferable that they exist randomly.

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

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. When the weight average molecular weight is less than 10,000, the strength of the polyimide layer decreases and 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 uneven thickness and streaks of the adhesive layer tend to occur during coating operations.

Since the adhesive polyimide is used to cover the conductor circuit layer, it is most preferable to have a completely imidized structure in order to suppress copper diffusion. However, a part of the polyimide may be an amic acid. The imidization rate was determined to be 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: JASCO Corporation FT/IR620). It can be calculated from the absorbance of C=O stretching derived from the imide group at 1780 cm ^-1 using the benzene ring absorber as a reference.

(Crosslink formation)
When the adhesive polyimide has a ketone group, crosslinking is achieved by reacting the ketone group with the amino group of an amino compound having at least two primary amino groups as functional groups to form a C=N bond. structure can be formed. By forming a crosslinked structure, the heat resistance of the adhesive polyimide can be improved. Preferred tetracarboxylic anhydrides for forming a polyimide having a ketone group include, for example, 3,3',4,4'-benzophenone tetracarboxylic dianhydride (BTDA), and examples of diamine compounds include, for example, 4 , 4'-bis(3-aminophenoxy)benzophenone (BABP), and 1,3-bis[4-(3-aminophenoxy)benzoyl]benzene (BABB).

Examples of the above-mentioned amino compounds that can be used for crosslinking adhesive polyimide include dihydrazide compounds, aromatic diamines, aliphatic amines, and the like. Among these, dihydrazide compounds are preferred. Aliphatic amines other than dihydrazide compounds tend to form crosslinked structures even at room temperature, and there is a concern about the storage stability of the varnish. On the other hand, aromatic diamines require high temperatures to form crosslinked structures. In this way, 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.

(Manufacture of adhesive layer)
The adhesive polyimide can be produced by reacting the above-mentioned tetracarboxylic dianhydride and a diamine compound in a solvent to produce a polyamic acid, and then ring-closing the polyamic acid by heating. For example, adhesive polyimide can be produced by dissolving approximately equimolar amounts of tetracarboxylic dianhydride and a diamine compound in an organic solvent, stirring at a temperature within the range of 0 to 100°C for 30 minutes to 24 hours, and causing a polymerization reaction. A polyamic acid precursor is obtained. In the reaction, the reaction components are dissolved in the organic solvent so that the amount of the precursor to be produced 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, dimethyl sulfoxide (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. Further, the amount of such an organic solvent to be used is not particularly limited, but it should be adjusted to an amount such 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 it can be concentrated, diluted, or replaced with another organic solvent if necessary. In addition, polyamic acids generally have excellent solvent solubility, so they are advantageously used. Preferably, the viscosity of the polyamic acid solution is within the range of 500 cps to 100,000 cps. Outside this range, defects such as uneven thickness and streaks are likely to occur in the film during coating operations using a coater or the like.

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

When crosslinking the adhesive polyimide obtained as described above, the above 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 amino compound are combined to form a primary compound. A condensation reaction is performed with an amino group. This condensation reaction causes the resin solution to harden into a cured product. In this case, the amount of the amino compound added is preferably 0.004 mol to 1.5 mol, preferably 0.005 mol to 1.2 mol, more preferably 0.005 mol to 1.2 mol, of primary amino groups per 1 mol of ketone group. The amino compound can be added preferably in an amount of 0.03 mol to 0.9 mol, most preferably 0.04 mol 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 mol of ketone group, crosslinking of the polyimide chains by the amino compound will not be sufficient, resulting in poor adhesion after curing. Heat resistance tends to be difficult to develop in the layer, and if the amount of the amino compound added exceeds 1.5 mol, the unreacted amino compound acts as a thermoplastic agent, which tends to reduce the heat resistance of the adhesive layer.

Conditions for the condensation reaction for forming crosslinks are not particularly limited as long as the ketone group in the adhesive polyimide reacts with the primary amino group of the amino compound to form an imine bond (C=N bond). The temperature of the heating condensation is set to 120° C., for example, in order to release water generated by condensation to the outside of the system, or to simplify the condensation process when performing a heating condensation reaction after synthesizing the adhesive polyimide. The temperature range is preferably from 140 to 200°C, more preferably from 140 to 200°C. The reaction time is preferably about 30 minutes to 24 hours, and the end point of the reaction can be determined, for example, by measuring the infrared absorption spectrum using a Fourier transform infrared spectrophotometer (commercial product: JASCO Corporation FT/IR620). This can be confirmed by the decrease 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 .

Thermal condensation of the ketone group of the adhesive polyimide and the primary amino group of the amino compound can be carried out by, for example, (a) a method in which an amino compound is added and heated subsequent to the synthesis (imidization) of the adhesive polyimide; b) A method in which an excess amount of an amino compound is charged in advance as a diamine component, and subsequent to 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 has been added after processing it into a predetermined shape (for example, after applying it to an arbitrary base material or forming it into a film shape), etc. Can be done.

In order to impart heat resistance to adhesive polyimide, we have explained the formation of imine bonds by forming a crosslinked structure, but the method is not limited to this, and as a method of curing polyimide, for example, epoxy resin, epoxy resin curing agent, etc. may be blended. It is also possible to cure it.

(thickness of adhesive layer)
The thickness of the adhesive layer is, for example, preferably in the range of 5 to 125 μm, more preferably in the range of 10 to 50 μm. If the thickness of the adhesive layer is less than the above lower limit, problems such as insufficient electrical insulation may occur. On the other hand, if the thickness of the adhesive layer exceeds the above upper limit, problems such as decreased dimensional stability will occur.

(CTE of adhesive layer)
The adhesive polyimide has high thermal expansion, and has a CTE of preferably 35 ppm/K or more, more preferably 35 ppm/K or more and 200 ppm/K or less, and even more preferably 35 ppm/K or more and 150 ppm/K or less. It is. An adhesive layer having a desired CTE can be obtained by appropriately changing the combination of raw materials used, the thickness, and drying/curing conditions.
Adhesive polyimide has high thermal expansion but low elasticity, so even if the CTE exceeds 30 ppm/K, it can alleviate internal stress generated during lamination. The present inventors have discovered that, as a characteristic of adhesive polyimide, there exists a temperature range in the range of 40 to 250° C. in which the storage elastic modulus decreases at a steep gradient as the temperature rises. Such characteristics are thought to be a factor in alleviating internal stress during thermocompression bonding and maintaining dimensional stability after circuit processing.

(Dielectric loss tangent of adhesive layer)
In order to suppress deterioration of dielectric loss, the adhesive layer has a dielectric loss tangent (Tan δ) at 10 GHz of preferably 0.004 or less, more preferably 0.0005 or more and 0.004 or less, and even more preferably 0.004 or less. It is preferably within the range of 001 or more and 0.0035 or less. If the dielectric loss tangent of the adhesive layer at 10 GHz exceeds 0.004, problems such as electrical signal loss are likely to occur on the high frequency signal transmission path. On the other hand, the lower limit of the dielectric loss tangent of the adhesive layer at 10 GHz is not particularly limited.

(Permittivity of adhesive layer)
The adhesive layer preferably has a dielectric constant of 4.0 or less at 10 GHz in order to ensure impedance matching. If the dielectric constant of the adhesive layer exceeds 4.0 at 10 GHz, the dielectric loss of the adhesive layer will deteriorate, and problems such as electrical signal loss will likely occur on the high-frequency signal transmission path.

(filler)
The adhesive layer may contain a filler, if necessary. Examples of fillers include silicon dioxide, aluminum oxide, magnesium oxide, beryllium oxide, boron nitride, aluminum nitride, silicon nitride, aluminum fluoride, calcium fluoride, and metal salts of organic phosphinic acids. These can be used alone or in combination of two or more.

Adhesive polyimide is solvent-soluble, so when laminating an adhesive layer, a polyimide coating solution may be applied and dried to laminate, or polyimide in the form of a film (hereinafter referred to as "adhesive film") may be used. It may be laminated as

The adhesive film is formed by forming the above-mentioned polyimide, which forms the adhesive layer, into a film shape. The film-like polyimide may be in a state where it is laminated on any base material such as a copper foil, a glass plate, a polyimide film, a polyamide film, or a polyester film.

Examples of the method for producing an adhesive film include: [1] A method of producing an adhesive film by applying a solution of polyamic acid to a supporting base material, drying it, heat-treating it to imidize it, and then peeling it off from the supporting base material; [2] A method of manufacturing an adhesive film by coating and drying a polyamic acid solution on a supporting base material, peeling off the polyamic acid gel film from the supporting base material, and heat-treating it to imidize it, [3] Supporting base material Another example is a method in which an adhesive polyimide solution is applied, dried, and then peeled off from a supporting substrate to produce an adhesive film. Note that the adhesive polyimide constituting the adhesive film may be crosslinked by the above method.

The method for applying the adhesive polyimide solution (or polyamic acid solution) onto the support substrate is not particularly limited, and can be applied using a comma, die, knife, lip, or other coater. The adhesive film to be manufactured is preferably formed by applying an adhesive polyimide solution that has been imidized in a polyamic acid solution onto a supporting substrate and drying it. Since adhesive polyimide is solvent-soluble, it is advantageous that polyamic acid can be imidized in a solution state and used as is as a coating solution for adhesive polyimide.

Note that the adhesive film can be obtained by applying a solution (for example, a varnish containing a solvent) onto any base material, drying it at a temperature of, for example, 80 to 180° C., and then peeling it off. Moreover, an arbitrary base material can be made into a coverlay film or a solder resist, and it can also be used as a protective layer of an adhesive layer.

The circuit board of this embodiment is obtained by thermocompression bonding this adhesive film to the insulating base material layer on which the conductor circuit layer is formed, at a temperature of, for example, 60° C. or higher and 220° C. or lower. When thermocompression bonding with the insulating base material layer is performed, the temperature is preferably 60°C or higher and lower than 180°C, more preferably 80°C or higher and 175°C or lower. When the thermocompression bonding temperature exceeds 220° C., the peel strength between the insulating base layer and the polyimide layer tends to decrease. This is considered to be due to heat-induced deterioration of the liquid crystal polymer on the surface in contact with the adhesive layer.

[Multilayer circuit board]
The multilayer circuit board of this embodiment is formed by laminating a plurality of circuit boards according to the above embodiments. Further, the multilayer circuit board of this embodiment may optionally have a conductor portion exposed on the surface of the multilayer circuit board. As used herein, the term "conductor circuit layer" refers to an in-plane connection electrode (land electrode) formed in the surface direction of an insulating base material layer made of a liquid crystal polymer, and an interlayer connection electrode (land electrode) in contact with the conductor circuit layer. (via electrode).

The high frequency characteristics of the multilayer circuit board of this embodiment can be ensured by the adhesive layer and the conductor circuit layer embedded inside. Therefore, the multilayer circuit board of this embodiment can be made into a multilayer circuit board with high adhesive strength of the conductor circuit layer on which components are mounted and high embeddability of the conductor circuit layer without impairing high frequency characteristics. Furthermore, even when the conductor portions exposed on the surface of the multilayer circuit board of this embodiment are provided, heat resistance and sufficient adhesive strength are ensured, and the conductor portions exposed on the surface during soldering during component mounting are secured. Delamination is less likely to occur even when heat or stress is applied.

In the multilayer circuit board of this embodiment, an example in which two circuit boards each having a conductor circuit layer formed on at least one side of an insulating base material layer are prepared, and these two circuit boards are laminated to form a multilayer circuit board. I will list and explain. Note that although this embodiment takes as an example a case in which two circuit boards are stacked, it can also be applied to a multilayer circuit board in which three or more circuit boards are stacked.

FIG. 1 is a manufacturing process diagram of a multilayer circuit board according to this embodiment. First, two circuit boards (referred to as "first circuit boards") on which conductive circuit layers are formed are prepared. Here, as shown in FIG. 1(a), a first circuit board has a conductor circuit layer 20 formed on one side of an insulating resin layer (hereinafter referred to as "insulating base material layer") 10 made of a liquid crystal polymer. Although 1A is used as an example, conductor circuit layers 20 may be formed on both sides of the insulating base layer 10.

(Adhesive layer formation process)
Next, as shown in FIGS. 1(b) and 1(c), an adhesive layer 30 is laminated to cover the conductor circuit layer 20 on the first circuit board 1A to form a second circuit board 2A. A layer forming step is performed. In addition, when the first circuit board 1A is a double-sided circuit board in which conductive circuit layers 20 are formed on both sides of the insulating base material layer 10, adhesive layers 30 may be laminated on both sides.

The adhesive layer forming step is performed by laminating the adhesive layer 30 on the exposed surface of the insulating base material layer 10 and the surface of the conductor circuit layer 20 on one or both surfaces of the first circuit board 1A. For example, the adhesive layer forming step includes laminating the adhesive film on one or both sides at a low temperature of 90 to 100° C. so as to cover the surface of the conductor circuit layer 20 and the exposed surface of the insulating base layer 10. This can be done by

In the adhesive layer forming step, the surface of the adhesive layer 30 in the second circuit board 2A to be formed is preferably formed into a flat surface. By forming the surface of the adhesive layer 30 in a flat shape, adhesiveness in the lamination process described later is improved. Further, it is preferable that the adhesive layer 30 formed has a uniform thickness.

(Lamination process)
Next, as shown in FIGS. 1(d) and (e), a plurality of second circuit boards 2A provided with the adhesive layer 30 on one or both surfaces, or a second circuit board 2A and another circuit board A lamination step is performed to obtain the multilayer circuit board 100 by laminating the circuit boards (which may be the first circuit board 1A described above). 1(d) and (e) show a mode in which the adhesive layers 30 of the second circuit board 2A are laminated so as to face each other, but the adhesive layer surface of the second circuit board 2A and the other The two circuit boards 2A may be stacked such that the surfaces on the insulating base material layer 10 side are in contact with each other. Note that although this embodiment shows an example in which two circuit boards are stacked, a stacking process in which three or more circuit boards are stacked at once can also be performed.

In the adhesive layer forming step, since the surface of the adhesive layer 30 is flattened, it is possible to laminate the adhesive layer 30 without creating bubbles or the like in the laminating step.

(Thickness adjustment process)
If necessary, as shown in FIGS. 1(e) and 1(f), the multilayer circuit board 100 obtained in the above laminating process is pressed from both sides with a pressure roller, a press device, etc. to form the adhesive layer. It is also possible to perform a thickness adjustment step of adjusting the thickness of the 30. The thickness adjustment process can improve the accuracy of the thickness.

(Heating process)
In the thickness adjustment step, after adjusting the thickness of the adhesive layer 30, a heating step is performed, preferably at a temperature of 40 to 250°C, more preferably 120°C or more and less than 180°C. In the heating step, it is particularly preferable to heat at a temperature of 130 to 170° C. from the viewpoint of suppressing thermal deterioration of the liquid crystal polymer and suppressing a decrease in peel strength. Thereby, as shown in FIG. 1(g), a multilayer circuit board 101 in which a plurality of circuit boards are integrally laminated is manufactured. At this time, the adhesive layer 30 can also be formed by, for example, forming a crosslinked structure of imine bonds by thermal condensation of adhesive polyimide.

The multilayer circuit board 101 of this embodiment has a structure in which an adhesive layer 30 having a thickness that ensures insulation, flexibility, and low dielectric properties is provided between the conductive circuit layer 20 and the insulating base material layer 10. There is. Note that, if necessary, a coverlay film or a solder resist may be provided as a protective layer between the opposing surfaces of the adhesive layer 30. Additionally, chip-type electronic components such as an IC chip, a chip capacitor, a chip coil, and a chip resistor can also be incorporated inside the multilayer circuit board 101 of this embodiment. Note that, in FIG. 1, illustration of these electronic components, via electrodes, etc. is omitted.

EXAMPLES Hereinafter, the present invention will be specifically explained with reference to Examples, but the present invention is not limited to these Examples in any way. In addition, in the following examples, various measurements and evaluations are as follows unless otherwise specified.

[Measurement of coefficient of thermal expansion (CTE)]
A polyimide film with a size of 3 mm x 20 mm was 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). After further holding at that temperature for 10 minutes, it was cooled at a rate of 5°C/min, and the average coefficient of thermal expansion (coefficient of thermal expansion) from 250°C to 100°C was determined.

[Measurement of glass transition temperature (Tg)]
The glass transition temperature was determined by heating a polyimide film with a size of 5 mm x 20 mm from 30°C to 400°C using a dynamic viscoelasticity analyzer (DMA: manufactured by UBM, trade name: E4000F). Measurement was performed at 4° C./min and a frequency of 11 Hz, and the temperature at which the change in elastic modulus (tan δ) was maximum was defined as the glass transition temperature.

[Measurement of surface roughness of copper foil]
The surface roughness of the copper foil was measured using AFM (manufactured by Bruker AXS, trade name: Dimension Icon type SPM), probe (manufactured by Bruker AXS, trade name: TESPA (NCHV), tip radius of curvature 10 nm, Using a spring constant of 42 N/m), measurement was performed in a tapping mode on an area of 80 μm x 80 μm on the surface of the copper foil, and the ten-point average roughness (Rzjis) was determined.

[Measurement of dielectric constant (Dk) and dielectric loss tangent (Df)]
The permittivity and dielectric loss tangent were measured using a cavity resonator perturbation method permittivity evaluation device (manufactured by Agilent, trade name: Vector Network Analyzer E8363C) and a split post dielectric resonator (SPDR resonator), using a resin sheet at a frequency of 10 GHz. The dielectric constant and dielectric loss tangent were measured. The resin sheet used in the measurement was left for 24 hours at a temperature of 24 to 26°C and a humidity of 45 to 55%.

[Laser processability evaluation method]
Laser processability was evaluated using the following method. A UV-YAG, third harmonic 355 nm laser beam with a frequency of 60 kHz and an intensity of 1.0 W was irradiated in the stacking direction of the sample multilayer circuit board to process the vias with a bottom, and there were no gouges or undercuts in the adhesive layer. Those in which no gouging or undercutting occurred were rated as "good," and those in which gouges or undercuts occurred in the adhesive layer were rated as "poor."

[Measurement of reflow heat resistance]
Reflow heat resistance was performed using the following method. After absorbing moisture at 40°C and 90% humidity for 96 hours, the sample multilayer circuit board was preheated at 120°C for 2 hours, then heated from 150°C to 180°C for 105 seconds, above 220°C for 65 seconds, and then to 245°C. The test was conducted with a heat profile of 7 seconds. Samples with no blistering between the layers or peeling of the layers were rated as "good", and samples with blistering between the layers or peeling of the layers were rated as "unsatisfactory".

[Measurement of peel strength]
Peel strength was measured using the following method. Using a tensile tester (Strograph VE, manufactured by Toyo Seiki Seisakusho), the peel strength was measured when a sample with a width of 5 mm was pulled in the 90° direction of the adhesive layer at a speed of 50 mm/min. In addition, a peel strength of 0.9 kN/m or more is considered "good", a peel strength of 0.4 kN/m or more and less than 0.9 kN/m is "acceptable", and a peel strength of less than 0.4 kN/m is "unacceptable". evaluated.

[Warpage evaluation method]
The warpage was evaluated using the following method. A 10 cm x 10 cm film was placed, and the average height of the four corners of the film was measured. If it was 10 mm or less, it was rated "good" and if it exceeded 10 mm, it was rated "unsatisfactory."

The abbreviations used in this example represent the following compounds.
BTDA: 3,3',4,4'-benzophenone tetracarboxylic dianhydride PMDA: Pyromellitic dianhydride APB: 1,3-bis(3-aminophenoxy)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: 210 mgKOH/g, mixture of dimer diamines with cyclic structure and chain structure, Dimer component content; 95% by weight or more)
ODPA: 4,4'-oxydiphthalic anhydride (also known as 5,5'-oxybis-1,3-isobenzofurandione)
N-12: Dodecanedioic acid dihydrazide NMP: N-methyl-2-pyrrolidone

(Synthesis example 1)
<Preparation of resin solution for adhesion>
In a 1000 ml separable flask, 57.68 g BTDA (0.179 mol), 87.10 g DDA (0.163 mol), 5.26 g APB (0.018 mol), 210 g NMP, and 140 g xylene. was charged and mixed well at 40° C. for 1 hour to prepare a polyamic acid solution. Polyimide solution 1 (solid content: 30% by weight, viscosity: 6,100 cps, weight average molecular weight ;63,900) was prepared.

(Synthesis examples 2 to 9)
<Preparation of resin solution for adhesive layer>
Polyimide solutions 2 to 9 were prepared in the same manner as in Synthesis Example 1, except that the raw material compositions shown in Table 1 were used.

(Synthesis example 10)
<Preparation of resin solution for adhesive layer>
1.1 g of N-12 (0.004 mol) was blended with 100 g (30 g as solid content) of polyimide solution 1 prepared in Synthesis Example 1, and diluted by adding 0.1 g of NMP and 10 g of xylene. Polyimide solution 10 was prepared by further stirring for 1 hour.

(Synthesis example 11)
<Preparation of resin solution for adhesive layer>
Polyimide solution 11 was prepared in the same manner as in Synthesis Example 10 except that polyimide solution 2 was used.

(Synthesis example 12)
<Preparation of resin solution for adhesive layer>
Polyimide solution 12 was prepared in the same manner as in Synthesis Example 10 except that polyimide solution 3 was used.

(Synthesis example 13)
<Preparation of resin solution for adhesive layer>
Polyimide solution 13 was prepared in the same manner as in Synthesis Example 10 except that polyimide solution 4 was used.

(Synthesis example 14)
<Preparation of resin solution for adhesive layer>
Polyimide solution 14 was prepared in the same manner as in Synthesis Example 10 except that polyimide solution 5 was used.

(Synthesis example 15)
<Preparation of resin solution for adhesive layer>
Polyimide solution 15 was prepared in the same manner as in Synthesis Example 10 except that polyimide solution 6 was used.

(Preparation example 1)
<Preparation of resin sheet for adhesive layer>
A resin sheet 1 (thickness: 25 μm) was prepared by applying polyimide solution 10 to one side of a PET film subjected to mold release treatment, drying it at 80° C. for 15 minutes, and then peeling it off. The glass transition temperature of the resin sheet 1 was 41.2° C., and the dielectric constant and dielectric loss tangent were 2.69 and 0.0023, respectively.

(Preparation example 2)
<Preparation of resin sheet for adhesive layer>
Resin sheet 2 was prepared in the same manner as in Preparation Example 1 except that polyimide solution 11 was used. The glass transition temperature of the resin sheet 2 was 48.0° C., and the dielectric constant and dielectric loss tangent were 2.50 and 0.0022, respectively.

(Preparation example 3)
<Preparation of resin sheet for adhesive layer>
Resin sheet 3 was prepared in the same manner as in Preparation Example 1 except that polyimide solution 12 was used. The glass transition temperature of the resin sheet 3 was 60.2°C, and the dielectric constant and dielectric loss tangent were 2.63 and 0.0025, respectively.

(Preparation example 4)
<Preparation of resin sheet for adhesive layer>
Resin sheet 4 was prepared in the same manner as in Preparation Example 1 except that polyimide solution 13 was used. The glass transition temperature of the resin sheet 4 was 72.0° C., and the dielectric constant and dielectric loss tangent were 2.70 and 0.0028, respectively.

(Preparation example 5)
<Preparation of resin sheet for adhesive layer>
Resin sheet 5 was prepared in the same manner as in Preparation Example 1 except that polyimide solution 14 was used. The glass transition temperature of the resin sheet 5 was 39.6° C., and the dielectric constant and dielectric loss tangent were 2.61 and 0.0025, respectively.

(Preparation example 6)
<Preparation of resin sheet for adhesive layer>
Resin sheet 6 was prepared in the same manner as in Preparation Example 1 except that polyimide solution 15 was used. The glass transition temperature of the resin sheet 6 was 48.2° C., and the dielectric constant and dielectric loss tangent were 2.61 and 0.0023, respectively.

(Preparation example 7)
<Preparation of resin sheet for adhesive layer>
Resin sheet 7 was prepared in the same manner as in Preparation Example 1 except that polyimide solution 7 was used. The glass transition temperature of the resin sheet 7 was 236.3° C., and the dielectric constant and dielectric loss tangent were 3.11 and 0.0050, respectively.

(Preparation example 8)
<Preparation of resin sheet for adhesive layer>
Resin sheet 8 was prepared in the same manner as in Preparation Example 1 except that polyimide solution 8 was used. The glass transition temperature of the resin sheet 8 was 164.8° C., and the dielectric constant and dielectric loss tangent were 2.90 and 0.0039, respectively.

(Preparation example 9)
<Preparation of resin sheet for adhesive layer>
Resin sheet 9 was prepared in the same manner as in Preparation Example 1 except that polyimide solution 9 was used. The glass transition temperature of the resin sheet 9 was 195.8° C., and the dielectric constant and dielectric loss tangent were 2.90 and 0.0041, respectively.

(Preparation example 10)
<Preparation of coverlay>
Polyimide solution 7 was applied to one side of a polyimide film (manufactured by DuPont-Toray Co., Ltd., trade name: Kapton EN-S, thickness: 25 μm, CTE: 16 ppm/K, Dk: 3.79, Df: 0.0126). Drying was performed at ℃ for 15 minutes to prepare coverlay 10 (adhesive layer thickness: 25 μm).

(Preparation example 11)
<Preparation of coverlay>
Coverlay 11 was prepared in the same manner as in Preparation Example 7 except that polyimide solution 8 was used.

(Preparation example 12)
<Preparation of coverlay>
Coverlay 12 was prepared in the same manner as in Preparation Example 7 except that polyimide solution 9 was used.

[Example 1]
A liquid crystal polymer film (manufactured by Kuraray Co., Ltd., trade name: CT-Z, thickness: 50 μm, CTE: 18 ppm/K, heat distortion temperature: 300°C, Dk: 3.40, Df: 0.0022) was used as an insulating base material. A double-sided flexible copper-clad laminate 1 with copper foil (electrolytic copper foil, thickness: 9 μm, surface roughness Rz: 2.0 μm) provided on both sides is prepared, and a circuit is etched on the copper foil on one side. A wiring board 1 on which a conductor circuit layer was formed was prepared by processing. At the same time, the copper foil on one side of the double-sided flexible copper-clad laminate 1 was removed by etching to prepare a single-sided flexible copper-clad laminate 1'.

The resin sheet 1 was sandwiched between the conductive circuit layer side surface of the wiring board 1 and the insulating base material layer side surface of the single-sided flexible copper clad laminate 1', and the resin sheet 1 was stacked on top of each other at a temperature of 160°C. The circuit board 1 was prepared by thermocompression bonding under conditions of a pressure of 4 MPa and a time of 60 minutes. The warpage of the circuit board 1 was "good", the peel strength was "good", and the laser processability was "good".

[Example 2]
A circuit board 2 was prepared in the same manner as in Example 1 except that resin sheet 2 was used instead of resin sheet 1. The warpage of the circuit board 2 was "good", the peel strength was "good", and the laser processability was "good".

[Example 3]
A circuit board 3 was prepared in the same manner as in Example 1 except that resin sheet 3 was used instead of resin sheet 1. The warpage of the circuit board 3 was "good", the peel strength was "good", and the laser processability was "good".

[Example 4]
A circuit board 4 was prepared in the same manner as in Example 1 except that resin sheet 4 was used instead of resin sheet 1. The warpage of the circuit board 4 was "good", the peel strength was "good", and the laser processability was "good".

[Example 5]
A circuit board 5 was prepared in the same manner as in Example 1 except that resin sheet 5 was used instead of resin sheet 1. The warpage of the circuit board 5 was "good", the peel strength was "good", and the laser processability was "good".

[Example 6]
A circuit board 6 was prepared in the same manner as in Example 1 except that resin sheet 6 was used instead of resin sheet 1. The warpage of the circuit board 6 was "good", the peel strength was "good", and the laser processability was "good".

(Comparative example 1)
A circuit board 7 was prepared in the same manner as in Example 1 except that resin sheet 7 was used instead of resin sheet 1. The warpage of the circuit board 7 was "not acceptable", the peel strength was "not acceptable", and the laser processability was "good".

(Comparative example 2)
A circuit board 8 was prepared in the same manner as in Example 1 except that resin sheet 8 was used instead of resin sheet 1. The warpage of the circuit board 8 was "good", the peel strength was "fair", and the laser processability was "bad".

(Comparative example 3)
A circuit board 9 was prepared in the same manner as in Example 1 except that resin sheet 9 was used instead of resin sheet 1. The warpage of the circuit board 9 was "not acceptable", the peel strength was "not acceptable", and the laser processability was "good".

[Example 7]
A wiring board 7 and a wiring board 7' (both of which are the same as the wiring board 1) were prepared in the same manner as in Example 1. The adhesive layer surfaces of two coverlays 10 are overlapped and laminated on the conductive circuit layer side surfaces of each of the wiring board 7 and the wiring board 7', and the circuit board 7 and the circuit board 7' with the coverlays laminated thereon are stacked. Prepared. The resin sheet 1 was sandwiched between the coverlay side surface of the circuit board 7 and the coverlay side surface of the circuit board 7', and in the stacked state, the temperature was 160°C, the pressure was 4MPa, and the time was 60 minutes. The multilayer circuit board 7 was prepared by vacuum laminating under the following conditions and then thermocompression bonding in an oven at a temperature of 160° C. for 1 hour. The warpage of the multilayer circuit board 7 was "good", and the laser processability and reflow resistance were also "good".

[Example 8]
A multilayer circuit board 8 was prepared in the same manner as in Example 7 except that coverlay 11 was used instead of coverlay 10 and resin sheet 2 was used instead of resin sheet 1. The warpage of the multilayer circuit board 8 was "good", and the laser processability and reflow resistance were also "good".

[Example 9]
A multilayer circuit board 9 was prepared in the same manner as in Example 7 except that coverlay 12 was used instead of coverlay 10 and resin sheet 3 was used instead of resin sheet 1. The warpage of the multilayer circuit board 9 was "good", and the laser processability and reflow resistance were also "good".

(Reference example 1)
A circuit board 10 was prepared in the same manner as in Example 1 except that the thermocompression bonding temperature was 180°C instead of 160°C. The warpage of the circuit board 10 was "good", and the peel strength was "poor".

(Reference example 2)
A circuit board 11 was prepared in the same manner as in Example 7 except that the thermocompression bonding temperature was changed to 180°C instead of 160°C. The warpage of the circuit board 11 was "good", and the peel strength was "bad".

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 can be modified in various ways.

1A...First circuit board, 2A...Second circuit board, 10...Insulating base material layer, 20...Conductor circuit layer, 30...Adhesive layer, 100, 101...Multilayer circuit board

Claims (3)

A circuit board comprising an insulating base layer made of a liquid crystal polymer, a conductive circuit layer formed on at least one side of the insulating base layer, and an adhesive layer covering the conductive circuit layer,
The adhesive layer has an adhesive polyimide having a dielectric loss tangent of 0.004 or less at a frequency of 10 GHz measured using a split post dielectric resonator, and containing a tetracarboxylic acid residue and a diamine residue. Ori,
The adhesive polyimide contains, based on 100 mole parts of the diamine residue,
Contains a diamine residue derived from a dimer acid type diamine in which two terminal carboxylic acid groups of a dimer acid are substituted with a primary aminomethyl group or an amino group within a range of 50 to 99 mole parts. ,
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) in a range of 1 to 50 mole parts. Characteristic circuit board.

[In formulas (B1) to (B7), R ₁ independently represents a monovalent hydrocarbon group or alkoxy group having 1 to 6 carbon atoms, and the linking group A independently represents -O-, -S-, -CO -, -SO-, -SO ₂ -, -COO-, -CH ₂ -, -C(CH ₃ ) ₂ -, -NH- or -CONH-, where n ₁ is independent indicates an integer from 0 to 4. However, from equation (B3), those that overlap with equation (B2) are excluded, and from equation (B5), those that overlap with equation (B4) are excluded. ] The adhesive polyimide contains, based on 100 mole parts of the tetracarboxylic acid residue,
Claim 1, characterized in that it contains a total of 90 mole parts or more of tetracarboxylic acid residues derived from tetracarboxylic acid anhydrides represented by the following general formulas (1) and/or (2). circuit board.

[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 moiety 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, or 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 -, but n is Indicates an integer from 1 to 20. ] A multilayer circuit board made by laminating multiple circuit boards,
A multilayer circuit board, wherein the circuit board is the circuit board according to claim 1 or 2 .

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