JP2018174287A - Circuit board and multilayer circuit board - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a circuit board and a multilayer circuit board, which are excellent in adhesion, have a dielectric constant and a dielectric loss tangent and are equipped with an adhesion layer capable of reducing transmission loss even in high frequency transmission.SOLUTION: Circuit boards 1A, 2A and multilayer circuit boards 100, 101 formed by laminating a plurality of circuit boards include: an insulating base material layer 10 made of a liquid crystal polymer; a conductor circuit layer 20 formed on at least one surface of the insulating base material layer; and an adhesive layer 30 covering the conductor circuit layer. The conductive layer includes an adhesive polyimide which contains tetracarboxylic acid residue and diamine residue and in which two terminal carboxylic acid groups of dimer acid contain 40 parts by mole or more of diamine residue derived from dimer acid type diamine formed by being substituted to primary aminomethyl group or an amino group with respect to 100 parts by mole of the diamine residue.SELECTED DRAWING: Figure 1

Description

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

In recent years, with the progress of higher density and higher functionality of electronic devices, circuit board materials having further dimensional stability and excellent high frequency characteristics are required. In particular, low dielectric constant and low dielectric loss are important for the characteristics of organic interlayer insulating materials necessary for high-speed signal processing. In order to cope with higher frequencies, a multilayer wiring board using a liquid crystal polymer (LCP) characterized by a low dielectric constant and a low dielectric loss tangent as a dielectric layer has been proposed (for example, Patent Document 1). A multilayer wiring board having 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 a temperature near the melting point of the liquid crystal polymer base material. There is a concern that the electrical characteristics will be adversely affected, such as impedance mismatching. In addition, since the multilayer wiring board having a liquid crystal polymer as a base material layer has a smooth multilayer adhesive interface, the anchor effect does not appear and the interlayer adhesion becomes insufficient. In addition, a roughening treatment is required and the manufacturing process is complicated.

  By the way, as a technique related to an adhesive layer mainly composed of polyimide, a polyimide using a diamine compound derived from an aliphatic diamine such as dimer acid as a raw material, 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 the adhesive layer of the coverlay film (for example, Patent Document 2). The cross-linked polyimide resin of Patent Document 2 does not generate a volatile component composed of a cyclic siloxane compound, has excellent solder heat resistance, and has an adhesive force between a wiring layer and a coverlay film even in a use environment that is repeatedly exposed to high temperatures. It has the advantage of not lowering. However, Patent Document 2 does not discuss applicability to high-frequency signal transmission.

JP 2005-317953 A Japanese Patent No. 5777944

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

  As a result of intensive studies, the present inventors use adhesive polyimide capable of thermocompression bonding for the adhesive layer covering the conductor circuit layer in the circuit board having the insulating base layer made of a liquid crystal polymer and the conductor circuit layer. In addition, by controlling the type and amount of the monomer used as the raw material of the adhesive polyimide, it has been found that low dielectric constant and low dielectric loss tangent can be achieved while maintaining excellent adhesiveness. completed.

A circuit board according to the present invention includes an insulating base layer made of a liquid crystal polymer, a conductor circuit layer formed on at least one surface of the insulating base layer, and an adhesive layer covering the conductor circuit layer. It is a substrate.
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 is based on 100 mole parts of the diamine residue.
It is characterized by containing 40 mol parts or more of diamine residues derived from dimer acid type diamine in which two terminal carboxylic acid groups of dimer acid are substituted with primary aminomethyl groups or amino groups.

In the circuit board of the present invention, the adhesive polyimide is based on 100 mole parts of the tetracarboxylic acid residue.
It is characterized by containing a total of 90 mol parts or more of tetracarboxylic acid residues derived from tetracarboxylic acid anhydrides represented by the following general formula (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 formulas. In General Formula (2), the cyclic portion represented by Y is a 4-membered ring or 5-membered ring. It represents that a cyclic saturated hydrocarbon group selected from a ring, a 6-membered ring, a 7-membered ring or an 8-membered ring is formed. ]

[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 —, The integer of 1-20 is shown. ]

In the circuit board of the present invention, the adhesive polyimide is based on 100 mole parts of the diamine residue.
A diamine residue derived from the dimer acid type diamine may be contained in a range of 50 to 99 mole parts,
Even if it 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) within a range of 1 mol part or more and 50 mol parts or less. 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 the 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 is independently —O—, —S—, —CO. A divalent group selected from —, —SO—, —SO ₂ —, —COO—, —CH ₂ —, —C (CH ₃ ) ₂ —, —NH— or —CONH—, wherein n ₁ is independently Represents an integer of 0 to 4. However, in the formula (B3), those that overlap with the formula (B2) are excluded, and in the formula (B5), those that overlap with the formula (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 forms an adhesive layer that covers the conductor circuit layer with an adhesive polyimide into which a specific tetracarboxylic acid residue and diamine residue are introduced, thereby ensuring adhesion, reducing the dielectric constant, and reducing the dielectric constant. Dielectric loss tangent was made possible. In addition, the multilayer circuit board of the present invention has good interlayer connection and high reliability, and enables high-density integration and high-density mounting of electronic components.

It is explanatory drawing which shows the manufacturing process of the multilayer circuit board of one embodiment of this invention.

  Embodiments of the present invention will be described in detail.

[Circuit board]
The circuit board of the present embodiment has a conductor circuit layer on at least one surface 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 an adhesive layer formed of adhesive polyimide and a conductive circuit layer embedded therein, and the adhesive layer also has good low-temperature adhesiveness with a liquid crystal polymer. Therefore, the dielectric properties of the liquid crystal polymer are not adversely affected. 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. Moreover, the circuit board of this Embodiment may have arbitrary conductor circuit layers other than the conductor circuit layer coat | covered with the contact bonding layer.

(Insulating base material layer)
The insulating base material layer is made of a liquid crystal polymer. The liquid crystal polymer can be selected from various liquid crystal polymers such as a liquid crystal polymer used as an insulating substrate layer in a commercially available liquid crystal polymer film or a commercially available copper-clad laminate. As the liquid crystal polymer film, Kuraray's Bexter (trade name), Primatec's BIAC Film (trade name), or the like can be used. Moreover, as a copper clad laminated board, Panasonic R-F705T (brand name) etc. can be used.

  The thickness of the insulating base material layer is preferably in the range of 5 to 100 μm, for example, and more preferably in the range of 10 to 50 μm. If the thickness of the insulating base material layer is less than the lower limit, there may be a problem that sufficient electrical insulation cannot be secured. On the other hand, when the thickness of the insulating base material layer exceeds the above upper limit, problems such as reduction in dimensional stability occur.

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

  The heat distortion temperature of the liquid crystal polymer is preferably 180 ° C. or higher, more preferably 210 to 330 ° C. If it exists in this range, manufacture mentioned later can be implemented easily and does not have a bad influence on a liquid crystal polymer at the time of heat adhesion.

(Conductor circuit layer)
The conductor circuit layer in the circuit board of the present embodiment is not particularly limited as long as it is made of a conductive material. For example, copper, stainless steel, iron, nickel, beryllium, aluminum, zinc, indium, silver Gold, tin, zirconium, tantalum, titanium, lead, magnesium, manganese, and alloys thereof are preferable. Among these, copper or a copper alloy is particularly preferable.

  The conductor circuit layer can be formed by any method. For example, after forming an insulating substrate layer having a metal foil on one or both sides by thermocompression bonding a metal foil mainly composed of copper to the insulating substrate layer, a photosensitive resist is applied on the metal foil, A conductive circuit layer having a predetermined shape can be formed by performing exposure and development, forming 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 ink jetting or plating.

  Although the thickness of a conductor circuit layer is not specifically limited, For example, when using copper foil as a material of a conductor circuit layer, Preferably it is 35 micrometers or less, More preferably, it exists in the range of 5-25 micrometers. 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 sufficient. Moreover, as copper foil, the copper foil marketed can be used.

  The conductive circuit layer has a roughened surface in contact with the insulating base layer from the viewpoint of reducing transmission loss in high-frequency transmission and adhesion to the liquid crystal polymer, and the maximum height roughness (Rz) is 2. It is preferably 0.0 μm or less. The transmission loss is composed of the sum of the conductor loss and the dielectric loss. When the Rz of the conductor circuit layer is large, the conductor loss increases. That is, since Rz is adversely affected, it is necessary to control Rz.

  In addition to the conductor circuit layer, an interlayer connection electrode (via electrode) may be formed on the insulating base material layer. The interlayer connection electrode can be formed by forming a via hole in an insulating base layer made of a liquid crystal polymer by laser processing or drilling, and then filling 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. In the interlayer connection electrode, after forming the via hole, a plated portion may be formed on the inner surface of the via hole and a part of the surface of the conductor circuit layer.

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

  The adhesive polyimide constituting the adhesive layer is manufactured by imidizing a precursor polyamic acid obtained by reacting a specific acid anhydride with a diamine compound, so by explaining the acid anhydride and diamine compound Specific examples of adhesive polyimide are understood. In the present invention, the tetracarboxylic acid residue means a tetravalent group derived from tetracarboxylic dianhydride, and the diamine residue means a divalent group derived from a diamine compound. Means that.

(Tetracarboxylic acid residue)
The adhesive polyimide is based on a tetracarboxylic acid residue (100) derived from a tetracarboxylic acid anhydride represented by the following general formula (1) and / or (2) with respect to 100 mole parts of the tetracarboxylic acid residue. Hereinafter, it is preferable to contain 90 mol parts or more in total of “tetracarboxylic acid residue (1)” and “tetracarboxylic acid residue (2)”. In the present invention, the tetracarboxylic acid residue (1) and / or (2) is contained in a total of 90 mol parts or more with respect to 100 mol parts of the tetracarboxylic acid residue, thereby making the adhesive polyimide solvent-soluble. In addition, it is easy to achieve both flexibility and heat resistance of the adhesive polyimide, which is preferable. When the total of the 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 general formula (1), X represents a single bond or a divalent group selected from the following formulas. In general formula (2), the cyclic moiety represented by Y is a 4-membered ring or 5-membered ring. , A cyclic saturated hydrocarbon group selected from a 6-membered ring, a 7-membered ring and an 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 Represents an integer of ~ 20.

  Examples of the tetracarboxylic dianhydride for deriving the tetracarboxylic acid residue (1) include 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride (BPDA), 3,3 ′, 4,4′-benzophenone tetracarboxylic dianhydride (BTDA), 3,3 ′, 4,4′-diphenylsulfone tetracarboxylic 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 thereof include bis (trimellitic acid monoester anhydride) (TAHQ), ethylene glycol bisanhydro trimellitate (TMEG), and the like.

  Examples of the tetracarboxylic dianhydride for deriving 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- And cyclooctane tetracarboxylic dianhydride.

  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) as long as the effects of the invention are not impaired. be able to.

(Diamine residue)
The adhesive polyimide has a dimer acid type diamine residue derived from dimer acid type diamine in an amount of 40 mol parts or more, for example, 50 mol parts or more and 99 mol parts or less, preferably 100 mol parts of diamine residues. Is contained in a range of 60 mol parts or more, for example, 60 mol parts or more and 99 mol parts or less. By containing the dimer acid type diamine residue in the above amount, the dielectric property of the adhesive layer is improved, the thermocompression bonding property is improved by lowering the glass transition temperature (lower Tg) of the adhesive layer, and the low elastic modulus. The internal stress due to crystallization can be relaxed. If the dimer acid type diamine residue is less than 40 mol parts with respect to 100 mol parts of the diamine residues, sufficient adhesion to the liquid crystal polymer may not be obtained.

Here, the dimer acid type diamine means that two terminal carboxylic acid groups (—COOH) of dimer acid are substituted with primary aminomethyl groups (—CH ₂ —NH ₂ ) or amino groups (—NH ₂ ). Means a diamine. Dimer acid is a known dibasic acid obtained by an intermolecular polymerization reaction of an unsaturated fatty acid, and its industrial production process is almost standardized in the industry, and an unsaturated fatty acid having 11 to 22 carbon atoms is converted into a clay catalyst. It is obtained by dimerization with the above. The dimer acid obtained industrially is mainly composed of a dibasic acid having 36 carbon atoms obtained by dimerizing an unsaturated fatty acid having 18 carbon atoms such as oleic acid or linoleic acid, depending on the degree of purification. , Containing any amount of monomeric 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 dimer acid having a dimer acid content increased to 90% by weight or more by molecular distillation. In addition, although a double bond remains after the dimerization reaction, in the present invention, a dimer acid that is further reduced in the degree of unsaturation by hydrogenation reaction is included.

  As a feature of the dimer acid diamine, characteristics derived from the skeleton of the dimer acid can be imparted to the polyimide. That is, since the dimer acid type diamine is a macromolecular aliphatic having a molecular weight of about 560 to 620, the molecular molar volume can be increased and the polar groups of the polyimide can be relatively reduced. Such a feature of the dimer acid type diamine is considered to contribute to improving the dielectric characteristics by reducing the dielectric constant and the dielectric loss tangent while suppressing the decrease in 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-like aliphatic amino groups having a length close to 18 carbon atoms, not only gives flexibility to the polyimide, Since polyimide can be made into a non-target chemical structure or a non-planar chemical structure, it is considered that a low dielectric constant and a low dielectric loss tangent of polyimide can be achieved.

  The dimer acid type diamine is commercially available. For example, 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), and the like.

  In addition, the adhesive polyimide has a diamine residue derived from at least one diamine compound selected from diamine compounds represented by the following general formulas (B1) to (B7) with respect to 100 mol parts of the total diamine component. And it is preferable to contain in 1 mol part or more and 50 mol part or less in total, and it is more preferable to contain in 1 mol part or more and 40 mol part or less. Since the diamine compounds represented by the general formulas (B1) to (B7) have a flexible molecular structure, polyimide molecules are obtained by using at least one diamine compound selected from these in an amount within the above range. The flexibility of the chain can be improved, and solvent solubility and thermoplasticity can be imparted. In addition, for example, even when a via hole (through hole) is formed in the adhesive layer by laser processing, the ratio of the aromatic ring in the polyimide molecular structure can be increased, for example, the absorbability in the ultraviolet region can be increased. The glass transition temperature can be increased, and the heat resistance against the temperature rise of the bottom metal due to the heat input of the laser beam can be improved, so that the laser processability can be further improved. When the total amount of the diamine compounds represented by the general formulas (B1) to (B7) exceeds 50 mol parts with respect to 100 mol parts of all diamine components, the flexibility of the adhesive polyimide is insufficient, and Tg increases. Therefore, the residual stress due to thermocompression increases and the dimensional change rate after etching 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 is independently —O—, —S—, —CO—. , —SO—, —SO ₂ —, —COO—, —CH ₂ —, —C (CH ₃ ) ₂ —, —NH— or —CONH—, wherein n ₁ is independently An integer of 0 to 4 is shown. However, in the formula (B3), those that overlap with the formula (B2) are excluded, and in the formula (B5), those that overlap with the formula (B4) are excluded.
Note that “independently” means that in one of the above formulas (B1) to (B7), or in two or more, a plurality of linking groups A, a plurality of R _{1 s,} or a plurality of n ₁ are the same. It means good or different. In the formulas (B1) to (B7), 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 an arbitrary substituent such as a group).

The diamine represented by the formula (B1) (hereinafter sometimes referred to as “diamine (B1)”) is an aromatic diamine having two benzene rings. This diamine (B1) has high flexibility because the degree of freedom of the polyimide molecular chain is increased because the amino group directly connected to at least one benzene ring and the divalent linking group A are in the meta position. It is thought that it contributes to the improvement of the flexibility of the polyimide molecular chain. Therefore, the thermoplasticity of a polyimide increases by using diamine (B1). 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 and the like.

  The diamine represented by the formula (B2) (hereinafter sometimes referred to as “diamine (B2)”) is an aromatic diamine having three benzene rings. This diamine (B2) has high flexibility because the degree of freedom of the polyimide molecular chain is increased because the amino group directly connected to at least one benzene ring and the divalent linking group A are in the meta position. It is thought that it contributes to the improvement of the flexibility of the polyimide molecular chain. Therefore, the use of diamine (B2) increases the thermoplasticity of the polyimide. Here, as the linking group A, —O— is preferable.

  Examples of the diamine (B2) include 1,4-bis (3-aminophenoxy) benzene, 3- [4- (4-aminophenoxy) phenoxy] benzenamine, 3- [3- (4-aminophenoxy) phenoxy] Examples thereof include benzeneamine.

  The diamine represented by the formula (B3) (hereinafter sometimes referred to as “diamine (B3)”) is an aromatic diamine having three benzene rings. This diamine (B3) has high flexibility because the degree of freedom of the polyimide molecular chain is increased because two divalent linking groups A directly connected to one benzene ring are in the meta position. Therefore, it is thought that it contributes to the improvement of the flexibility of the polyimide molecular chain. Therefore, the use of diamine (B3) increases the thermoplasticity of the polyimide. Here, as the linking group A, —O— is preferable.

  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 the formula (B4) (hereinafter sometimes referred to as “diamine (B4)”) is an aromatic diamine having four benzene rings. This diamine (B4) has a 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, thereby improving the flexibility of the polyimide molecular chain. It is thought to contribute. Therefore, the use of diamine (B4) increases the thermoplasticity of the polyimide. Here, as the linking group A, —O—, —CH ₂ —, —C (CH ₃ ) ₂ —, —SO ₂ —, —CO—, and —CONH— are preferable.

  Examples of the diamine (B4) include bis [4- (3-aminophenoxy) phenyl] methane, bis [4- (3-aminophenoxy) phenyl] propane, bis [4- (3-aminophenoxy) phenyl] ether, bis [4- (3-aminophenoxy) phenyl] sulfone, bis [4- (3-aminophenoxy)] benzophenone, bis [4,4 ′-(3-aminophenoxy)] benzanilide and the like can be mentioned.

  The diamine represented by the formula (B5) (hereinafter sometimes referred to as “diamine (B5)”) is an aromatic diamine having four benzene rings. This diamine (B5) has high flexibility because the degree of freedom of the polyimide molecular chain is increased by having two divalent linking groups A directly connected to at least one benzene ring in the meta position. It is thought that it contributes to the improvement of the flexibility of the polyimide molecular chain. Therefore, the thermoplasticity of polyimide increases by using diamine (B5). Here, as the linking group A, —O— is preferable.

  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 the formula (B6) (hereinafter sometimes referred to as “diamine (B6)”) is an aromatic diamine having four benzene rings. This diamine (B6) has high flexibility by having at least two ether bonds, and is considered to contribute to the improvement of the flexibility of the polyimide molecular chain. Therefore, the use of diamine (B6) increases the thermoplasticity of the 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 -(4-Aminophenoxy) phenyl] sulfone (BAPS), bis [4- (4-aminophenoxy) phenyl] ketone (BAPK) and the like can be mentioned.

  The diamine represented by the 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 having high flexibility on both sides of the diphenyl skeleton, it is considered that this diamine (B7) contributes to improvement in flexibility of the polyimide molecular chain. Therefore, the thermoplasticity of polyimide increases by using diamine (B7). Here, as the linking group A, —O— is preferable.

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

  The adhesive polyimide can contain a diamine residue derived from a diamine compound other than the dimer acid diamine and diamines (B1) to (B7) as long as the effects of the invention are not impaired. As the diamine residue derived from the dimer acid type diamine and diamine compounds other than the diamines (B1) to (B7), those generally used as diamine compounds used for thermoplastic polyimide can be used without limitation. .

  Further, in the adhesive polyimide, by selecting the types of the tetracarboxylic acid residue and the diamine residue and the molar ratios when two or more tetracarboxylic acid residues or diamine residues are applied, The expansion coefficient, tensile modulus, glass transition temperature, etc. can be controlled. In addition, when a polyimide has a plurality of structural units of polyimide, it may exist as a block or at random, but it preferably exists at random.

The imide group concentration of the adhesive polyimide is preferably 20% by weight or less. Here, the “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 is decreased, and the low hygroscopicity is also deteriorated due to the increase in polar groups, so that the elastic modulus is increased.

  The weight average molecular weight of the adhesive polyimide is preferably in the range of, for example, 10,000 to 400,000, and more preferably in 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 tends to be reduced and it tends to become brittle. On the other hand, when the weight average molecular weight exceeds 400,000, the viscosity is excessively increased, and defects such as uneven thickness of the adhesive layer and streaks tend to occur during the coating operation.

Since the adhesive polyimide covers the conductor circuit layer, a completely imidized structure is most preferable in order to suppress copper diffusion. However, a part of the polyimide may be amic acid. The imidation ratio was measured at about 1015 cm ⁻¹ by measuring the infrared absorption spectrum of the polyimide thin film by a single reflection ATR method using a Fourier transform infrared spectrophotometer (commercial product: FT / IR620 manufactured by JASCO Corporation). It can be calculated from the absorbance of C═O stretching derived from an imide group of 1780 cm ⁻¹ with the benzene ring absorber as a reference.

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

  As said amino compound which can be used for bridge | crosslinking formation of adhesive polyimide, a dihydrazide compound, aromatic diamine, an aliphatic amine, etc. can be illustrated. Of these, dihydrazide compounds are preferred. Aliphatic amines other than dihydrazide compounds tend to form a crosslinked structure even at room temperature, and there is a concern about the storage stability of the varnish, while aromatic diamines need to be heated to form a crosslinked structure. Thus, when a dihydrazide compound is used, it is possible to achieve both storage stability of the varnish and shortening of the curing time. Examples of the dihydrazide compound 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 dihydradide didecadide Dihydrazide, fumaric acid dihydrazide, diglycolic acid dihydrazide, tartaric acid dihydrazide, malic acid dihydrazide, phthalic acid dihydrazide, isophthalic acid dihydrazide, terephthalic acid dihydrazide, 2,6-naphthodioic acid dihydrazide, 4,4-bisbenzenedihydrazide, 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 tetracarboxylic dianhydride and a diamine compound in a solvent to form a polyamic acid and then ring-closing with heating. For example, a tetracarboxylic dianhydride and a diamine compound are dissolved in an organic solvent in an approximately equimolar amount, and stirred for 30 minutes to 24 hours at a temperature within a range of 0 to 100 ° C. to cause a polymerization reaction. The precursor polyamic acid is obtained. In the reaction, the reaction components are dissolved so that the precursor to be produced is in the range of 5 to 50% by weight, preferably in the range of 10 to 40% by weight in the organic solvent. Examples of the organic solvent 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 further, aromatic hydrocarbons such as xylene and toluene can be used in combination. Further, the amount of such an organic solvent used is not particularly limited, but it should be adjusted so that the concentration of the polyamic acid solution obtained by the polymerization reaction is about 5 to 50% by weight. Is preferred.

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

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

  When the adhesive polyimide obtained as described above is crosslinked, the amino compound is added to the resin solution containing the ketone group-containing polyimide, and the ketone group in the adhesive polyimide and the amino compound primary class are added. A condensation reaction with an amino group. By this condensation reaction, the resin solution is cured to become a cured product. In this case, the added amount of the amino compound is preferably 0.004 mol to 1.5 mol, more preferably 0.005 mol to 1.2 mol, in total for the primary amino group with respect to 1 mol of the ketone group. The amino compound can be added so that the amount is preferably 0.03 mol to 0.9 mol, and most preferably 0.04 mol to 0.5 mol. Adhesion after curing because the addition of amino compounds such that the total amount of primary amino groups is less than 0.004 moles per mole of ketone groups is insufficient for crosslinking of the polyimide chains by the amino compounds. Heat resistance tends to be hardly exhibited in the layer, and when the addition amount of the amino compound exceeds 1.5 mol, the unreacted amino compound acts as a thermoplastic agent and tends to lower the heat resistance of the adhesive layer.

The conditions for the condensation reaction for forming the cross-link are not particularly limited as long as the conditions are such that the ketone group in the adhesive polyimide and the primary amino group of the amino compound react to form an imine bond (C═N bond). The temperature of the heat condensation is, for example, 120 for the purpose of releasing water generated by the condensation out of the system or simplifying the condensation step when the heat condensation reaction is subsequently performed after the synthesis of the adhesive polyimide. Within the range of -220 degreeC is preferable, and the inside of the range of 140-200 degreeC is more preferable. The reaction time is preferably about 30 minutes to 24 hours, and the end point of the reaction is 1670 cm by measuring the infrared absorption spectrum using, for example, a Fourier transform infrared spectrophotometer (commercial product: FT / IR620 manufactured by JASCO Corporation). ^-1 reduction of the absorption peak derived from the ketone group in the polyimide resin in the vicinity of or loss, and can be confirmed by the appearance of the absorption peak derived from the imine group 1635cm around ^-1.

  The heat condensation of the ketone group of the adhesive polyimide and the primary amino group of the amino compound is, for example, (a) a method of adding and heating an amino compound following the synthesis (imidation) 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 the adhesive polyimide is heated together with the remaining amino compound not involved in imidization or amidation, following the synthesis (imidation) of the adhesive polyimide, or , (C) The method of heating after processing the composition of the adhesive polyimide to which the amino compound is added into a predetermined shape (for example, after being applied to an arbitrary base material or after being formed into a film), etc. Can do.

Although imine bond formation was explained by forming a cross-linked structure to give heat resistance of adhesive polyimide, it is not limited to this, and as a polyimide curing method, for example, epoxy resin, epoxy resin curing agent etc. are blended It can also be cured.

(Adhesive layer thickness)
The thickness of the adhesive layer is preferably in the range of 5 to 125 μm, for example, and more preferably in the range of 10 to 50 μm. If the thickness of the adhesive layer is less than the lower limit, there may be a problem that sufficient electrical insulation cannot be secured. On the other hand, when the thickness of the adhesive layer exceeds the above upper limit, problems such as reduced dimensional stability occur.

(CTE of adhesive layer)
The adhesive polyimide has a high thermal expansibility, and CTE is preferably 35 ppm / K or more, more preferably 35 ppm / K or more and 200 ppm / K or less, and further 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 materials used, thickness, and drying / curing conditions.
Adhesive polyimide has high thermal expansion but low elasticity, so even if CTE exceeds 30 ppm / K, it can relieve internal stress generated during lamination. As a feature of the adhesive polyimide, the present inventors have found that a temperature range in which the storage elastic modulus decreases steeply as the temperature rises exists in the range of 40 to 250 ° C. Such characteristics are considered to be factors that relieve internal stress during thermocompression bonding and maintain dimensional stability after circuit processing.

(Dielectric loss tangent of adhesive layer)
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 still more preferably 0.00 in order to suppress deterioration of dielectric loss. The range of 001 to 0.0035 is preferable. If the dielectric loss tangent of the adhesive layer at 10 GHz exceeds 0.004, inconvenience such as loss of an electric signal is likely to occur on the transmission path of the high-frequency signal. On the other hand, the lower limit value of the dielectric loss tangent of the adhesive layer at 10 GHz is not particularly limited.

(Dielectric constant of adhesive layer)
The adhesive layer preferably has a dielectric constant at 10 GHz of 4.0 or less in order to ensure impedance matching. When the dielectric constant at 10 GHz of the adhesive layer exceeds 4.0, the dielectric loss of the adhesive layer is deteriorated, and inconvenience such as loss of an electric signal is likely to occur on the transmission path of the high-frequency signal.

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

  Since adhesive polyimide is solvent-soluble, when laminating an adhesive layer, it may be laminated by applying and drying a polyimide coating solution, or a film-like polyimide (hereinafter referred to as “adhesive film”). May be laminated.

  The adhesive film is formed by forming a polyimide film that forms the above-described adhesive layer into a film. The film-like polyimide may be in a state of being laminated on an arbitrary substrate such as a copper foil, a glass plate, a polyimide film, a polyamide film, or a polyester film.

  As an embodiment of the method for producing an adhesive film, for example, [1] a method of producing an adhesive film by applying a polyamic acid solution to a supporting substrate, drying, heat-treating and imidizing, and then peeling from the supporting substrate; [2] A method of producing an adhesive film by applying a polyamic acid solution to a supporting substrate and drying, then peeling the polyamic acid gel film from the supporting substrate and imidizing by heat treatment, [3] supporting substrate In addition, a method of producing an adhesive film by applying and drying an adhesive polyimide solution and then peeling it off from the supporting substrate can be mentioned. 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) on the support substrate is not particularly limited, and for example, the adhesive polyimide solution (or polyamic acid solution) can be applied by a coater such as a comma, a die, a knife, or a lip. The produced adhesive film is preferably formed by applying and drying an adhesive polyimide solution in which imidization is completed in a polyamic acid solution on a support substrate. Since the adhesive polyimide is solvent-soluble, it is advantageous because the polyamic acid is imidized in a solution state and can be used as it is as an adhesive polyimide coating solution.

  In addition, an adhesive film is obtained by apply | coating in the state of a solution (for example, varnish containing a solvent) on arbitrary base materials, for example, drying at the temperature of 80-180 degreeC, and then peeling. Moreover, arbitrary base materials can be made into a cover-lay film or a solder resist, and can also be set as the protective layer of an adhesive layer.

  The circuit board of the present embodiment is obtained by thermocompression bonding the adhesive film with the insulating base material layer on which the conductor circuit layer is formed, for example, at a temperature of 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 temperature of thermocompression bonding exceeds 220 ° C., the peel strength between the insulating base material layer and the polyimide layer tends to decrease. This is considered to be caused by heat-induced alteration of the liquid crystal polymer on the surface in contact with the adhesive layer.

[Multilayer circuit board]
The multilayer circuit board according to the present embodiment is formed by stacking a plurality of circuit boards according to the above embodiments. Further, the multilayer circuit board of the present embodiment may optionally have a conductor portion exposed on the surface of the multilayer circuit board. In this specification, the “conductor circuit layer” means 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 (in contact with the conductor circuit layer) This is distinguished from the via electrode.

  The high frequency characteristics of the multilayer circuit board of the present embodiment can be ensured by the adhesive layer and the conductor circuit layer embedded inside. Therefore, the multilayer circuit board according to the present embodiment can be a multilayer circuit board having high adhesion strength of the conductor circuit layer on which the component is mounted and high embedding property of the conductor circuit layer without impairing the high frequency characteristics. In addition, even when the conductor portion exposed on the surface of the multilayer circuit board of the present embodiment is provided, heat resistance and sufficient adhesive strength are ensured, and the conductor portion exposed on the surface during soldering during component mounting is ensured. Even when heat or stress is applied, delamination hardly occurs.

  In the multilayer circuit board of the present embodiment, an example in which two circuit boards each having a conductive circuit layer formed on at least one surface of an insulating base material layer are prepared, and the two circuit boards are stacked to form a multilayer circuit board. Will be described. Note that this embodiment will be described by way of example in which two circuit boards are stacked, but 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 the present embodiment. First, two circuit boards (referred to as “first circuit boards”) on which conductor circuit layers are formed are prepared. Here, as shown in FIG. 1A, a first circuit board in which a conductor circuit layer 20 is 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 the case where 1A is used is illustrated, the conductor circuit layer 20 may be formed on both surfaces of the insulating base material layer 10, respectively.

(Adhesive layer forming process)
Next, as shown in FIGS. 1B and 1C, an adhesive layer 30 is laminated so as to cover the conductor circuit layer 20 in the first circuit board 1A to form the second circuit board 2A. A layer forming step is performed. In addition, when 1 A of 1st circuit boards are the double-sided circuit boards in which the conductor circuit layer 20 is formed in both surfaces of the insulating base material layer 10, respectively, you may laminate | stack the adhesive layer 30 on both surfaces, respectively.

  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 side or both sides of the first circuit board 1A. For example, in the adhesive layer forming step, the adhesive film is bonded to one surface or both surfaces so as to cover the surface of the conductor circuit layer 20 and the exposed surface of the insulating base material layer 10 at a low temperature of 90 to 100 ° C. Can be performed.

  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 flat. By forming the surface of the adhesive layer 30 in a flat shape, the adhesion in the laminating process described later is improved. Moreover, it is preferable to form the thickness of the formed adhesive layer 30 uniformly.

(Lamination process)
Next, as shown in FIGS. 1D and 1E, a plurality of second circuit boards 2A provided with the adhesive layer 30 on one side or both sides, or the second circuit board 2A and another circuit board. A laminating process is performed in which the multilayer circuit board 100 is obtained by laminating (may be the first circuit board 1A). FIGS. 1D and 1E show a mode in which the adhesive layers 30 in the second circuit board 2A are stacked so as to be in contact with each other, but the adhesive layer surface of the second circuit board 2A and the other You may laminate | stack so that the surface by the side of the insulating base material layer 10 of 2 circuit board 2A may contact | connect. Note that although an example in which two circuit boards are stacked is described in this embodiment mode, a stacking process in which three or more circuit boards are stacked at a time can be performed.

  In the adhesive layer forming step, since the surface of the adhesive layer 30 is flattened, the adhesive layer 30 can be stacked without causing bubbles or the like in the stacking step.

(Thickness adjustment process)
If necessary, as shown in FIGS. 1E and 1F, the multilayer circuit board 100 obtained in the laminating step is pressed from both sides by a pressure roller, a press device, etc. A thickness adjusting step for adjusting the thickness of 30 can also be performed. Thickness accuracy can be improved by the thickness adjusting step.

(Heating process)
In the thickness adjusting step, after the thickness of the adhesive layer 30 is adjusted, a heating step of heating at a temperature of preferably 40 to 250 ° C., more preferably 120 ° C. or higher and lower than 180 ° C. is performed. 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 reduction in peel strength. Thereby, as shown in FIG. 1G, 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 form, for example, a crosslinked structure of imine bonds by heat condensation of adhesive polyimide.

  The multilayer circuit board 101 of the present embodiment has a configuration in which an adhesive layer 30 having a thickness that can ensure insulation, flexibility, and low dielectric properties is provided between the conductor circuit layer 20 and the insulating base material layer 10. Yes. In addition, you may provide a coverlay film or a soldering resist as a protective layer between the surfaces which the contact bonding layer 30 contacts as needed. In addition, chip-type electronic components such as an IC chip, a chip capacitor, a chip coil, and a chip resistor can be incorporated in the multilayer circuit board 101 of the present embodiment. In FIG. 1, these electronic components, via electrodes, and the like are not shown.

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

[Measurement of coefficient of thermal expansion (CTE)]
Using a thermomechanical analyzer (manufactured by Bruker, trade name: 4000SA), a polyimide film having a size of 3 mm × 20 mm was heated from 30 ° C. to 300 ° C. at a constant heating rate while applying a load of 5.0 g. Furthermore, after maintaining at that temperature for 10 minutes, it was cooled at a rate of 5 ° C./minute, and an average thermal expansion coefficient (thermal expansion coefficient) from 250 ° C. to 100 ° C. was determined.

[Measurement of glass transition temperature (Tg)]
Glass transition temperature is a rate of temperature increase from 30 ° C. to 400 ° C. using a polyimide film having a size of 5 mm × 20 mm, using a dynamic viscoelasticity measuring device (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 taken as the glass transition temperature.

[Measurement of surface roughness of copper foil]
The surface roughness of the copper foil is 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, Using a spring constant of 42 N / m), a tapping mode was used to measure a range of 80 μm × 80 μm on the surface of the copper foil, and a ten-point average roughness (Rzjis) was determined.

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

[Evaluation method of laser processability]
The laser workability was evaluated by the following method. UV-YAG, third harmonic 355nm laser light with a frequency of 60kHz and 1.0W in the direction of lamination of the multilayer circuit board of the sample to process the bottomed vias, and the adhesive layer is wrinkled and undercut Those which did not occur were evaluated as “good”, and those in which the adhesive layer was wrinkled or undercut were evaluated as “bad”.

[Measurement of reflow heat resistance]
Reflow heat resistance was performed by the following method. Sample multi-layer circuit board is moisture-absorbed at 40 ° C, 90% humidity, 96 hours, and then pre-heated at 120 ° C for 2 hours. The test was conducted with a profile that took 7 seconds of heat. Samples that did not swell between the layers of the sample or those that did not peel off the layer were evaluated as “good”, and samples that swelled or peeled off between the sample layers were evaluated as “impossible”.

[Measurement of peel strength]
The peel strength was measured by the following method. Using a tensile tester (manufactured by Toyo Seiki Seisakusho, Strograph VE), the peel strength was measured when a sample having a test piece width of 5 mm was pulled in the 90 ° direction of the adhesive layer at a speed of 50 mm / min. Note that a peel strength of 0.9 kN / m or more is “good”, a peel strength of 0.4 kN / m or more and less than 0.9 kN / m is “good”, and a peel strength of less than 0.4 kN / m is “impossible”. evaluated.

[Evaluation method of warpage]
The warpage was evaluated by the following method. A film of 10 cm × 10 cm was placed, and the average of the heights of warping at the four corners of the film was measured.

The abbreviations used in the examples 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 (trade name; PRIAMINE 1074, amine value; 210 mgKOH / g, a mixture of dimer diamine having a cyclic structure and a chain structure, produced by Croda Japan Co., Ltd. Dimer component content: 95% by weight or more)
ODPA: 4,4′-oxydiphthalic anhydride (also known as 5,5′-oxybis-1,3-isobenzofurandion)
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 mixed well at 40 ° C. for 1 hour to prepare a polyamic acid solution. The polyamic acid solution was heated to 190 ° C., heated and stirred for 4 hours, and 140 g of xylene was added to complete imidization. Polyimide solution 1 (solid content: 30 wt%, viscosity: 6,100 cps, weight average molecular weight) 63,900) was prepared.

(Synthesis Examples 2-9)
<Preparation of resin solution for adhesive layer>
Except for the raw material composition shown in Table 1, polyimide solutions 2 to 9 were prepared in the same manner as in Synthesis Example 1.

(Synthesis Example 10)
<Preparation of resin solution for adhesive layer>
To 100 g of polyimide solution 1 prepared in Synthesis Example 1 (30 g as a solid content), 1.1 g of N-12 (0.004 mol) is blended, and 0.1 g of NMP and 10 g of xylene are added and diluted. Furthermore, the polyimide solution 10 was prepared by stirring for 1 hour.

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

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

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

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

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

(Production Example 1)
<Preparation of resin sheet for adhesive layer>
The polyimide solution 10 was applied to one side of a release-treated PET film, dried at 80 ° C. for 15 minutes, and then peeled to prepare a resin sheet 1 (thickness: 25 μm). 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.

(Production Example 2)
<Preparation of resin sheet for adhesive layer>
A resin sheet 2 was prepared in the same manner as in Production Example 1 except that the 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.

(Production Example 3)
<Preparation of resin sheet for adhesive layer>
A resin sheet 3 was prepared in the same manner as in Production Example 1 except that the 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.

(Production Example 4)
<Preparation of resin sheet for adhesive layer>
A resin sheet 4 was prepared in the same manner as in Production Example 1 except that the 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.

(Production Example 5)
<Preparation of resin sheet for adhesive layer>
A resin sheet 5 was prepared in the same manner as in Production Example 1 except that the 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.

(Production Example 6)
<Preparation of resin sheet for adhesive layer>
A resin sheet 6 was prepared in the same manner as in Production Example 1 except that the 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.

(Production Example 7)
<Preparation of resin sheet for adhesive layer>
A resin sheet 7 was prepared in the same manner as in Production Example 1 except that the 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.

(Production Example 8)
<Preparation of resin sheet for adhesive layer>
A resin sheet 8 was prepared in the same manner as in Production Example 1 except that the 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.

(Production Example 9)
<Preparation of resin sheet for adhesive layer>
A resin sheet 9 was prepared in the same manner as in Production Example 1 except that the 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.

(Production Example 10)
<Preparation of coverlay>
The polyimide solution 7 was applied to one side of a polyimide film (trade name: Kapton EN-S, manufactured by Toray DuPont, thickness: 25 μm, CTE; 16 ppm / K, Dk; 3.79, Df; 0.0126). Drying was carried out at 15 ° C. for 15 minutes to prepare a coverlay 10 (adhesive layer thickness; 25 μm).

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

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

[Example 1]
Liquid crystal polymer film (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) as an insulating base material A double-sided flexible copper-clad laminate 1 provided with copper foil (electrolytic copper foil, thickness: 9 μm, surface roughness Rz; 2.0 μm) on both sides is prepared, and a circuit by etching is applied to the copper foil on one side The wiring board 1 which processed and formed the conductor circuit layer was prepared. In addition, the single-sided copper foil of the double-sided flexible copper-clad laminate 1 was removed by etching to prepare a single-sided flexible copper-clad laminate 1 ′.

  With the resin sheet 1 sandwiched between the surface on the conductor circuit layer side of the wiring board 1 and the surface on the insulating base material layer side of the single-sided flexible copper-clad laminate 1 ′, the temperature is 160 ° C. Circuit board 1 was prepared by thermocompression bonding under conditions of pressure; 4 MPa, time; 60 minutes. The warp 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 the resin sheet 2 was used in place of the resin sheet 1. The warp 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 the resin sheet 3 was used instead of the resin sheet 1. The warp 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 the resin sheet 4 was used instead of the resin sheet 1. The warp 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 the resin sheet 5 was used instead of the resin sheet 1. The warp 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 the resin sheet 6 was used instead of the resin sheet 1. The warp 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 the resin sheet 7 was used instead of the resin sheet 1. The warp of the circuit board 7 was “impossible”, the peel strength was “impossible”, 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 the resin sheet 8 was used instead of the resin sheet 1. The warp of the circuit board 8 was “good”, the peel strength was “good”, and the laser processability was “impossible”.

(Comparative Example 3)
A circuit board 9 was prepared in the same manner as in Example 1 except that the resin sheet 9 was used instead of the resin sheet 1. The warp of the circuit board 9 was “impossible”, the peel strength was “impossible”, and the laser processability was “good”.

[Example 7]
In the same manner as in Example 1, a wiring board 7 and a wiring board 7 ′ (both are the same as those of the wiring board 1) were prepared. The circuit board 7 and the circuit board 7 ′ in which the coverlays are laminated are laminated on the surfaces of the wiring board 7 and the wiring board 7 ′ on the respective conductor circuit layer side by overlapping the adhesive layer surfaces of the two coverlays 10. Prepared. In a state where the resin sheet 1 is sandwiched between the surface of the circuit board 7 on the cover lay side and the surface of the circuit board 7 'on the cover lay side, the temperature is 160 ° C., the pressure is 4 MPa, the time is 60 minutes. Then, the multilayer circuit board 7 was prepared by thermocompression bonding under conditions of temperature: 160 ° C., time: 1 hour in an oven. The warp 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 the coverlay 11 was used instead of the coverlay 10 and the resin sheet 2 was used instead of the 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 the coverlay 12 was used in place of the coverlay 10 and the resin sheet 3 was used in place of the resin sheet 1. The warp 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 changed to 180 ° C. instead of 160 ° C. The warp of the circuit board 10 was “good” and the peel strength was “impossible”.

(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 warp of the circuit board 11 was “good” and the peel strength was “impossible”.

  As mentioned above, although embodiment of this invention was described in detail for the purpose of illustration, this invention is not restrict | limited to the said embodiment, A various deformation | transformation is possible.

DESCRIPTION OF SYMBOLS 1A ... 1st circuit board, 2A ... 2nd circuit board, 10 ... Insulating base material layer, 20 ... Conductor circuit layer, 30 ... Adhesive layer, 100, 101 ... Multilayer circuit board

Claims (4)

A circuit board comprising an insulating base layer made of a liquid crystal polymer, a conductor circuit layer formed on at least one side of the insulating base layer, and an adhesive layer covering the conductor circuit layer,
The adhesive layer has an adhesive polyimide containing a tetracarboxylic acid residue and a diamine residue,
The adhesive polyimide is based on 100 mole parts of the diamine residue.
A circuit board comprising 40 mol 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. The adhesive polyimide is based on 100 mole parts of the tetracarboxylic acid residue.
It contains 90 mol parts or more in total of tetracarboxylic acid residues derived from tetracarboxylic acid anhydrides represented by the following general formula (1) and / or (2). Circuit board.

[In General Formula (1), X represents a single bond or a divalent group selected from the following formulas. In General Formula (2), the cyclic portion represented by Y is a 4-membered ring or 5-membered ring. It represents that a cyclic saturated hydrocarbon group selected from a ring, a 6-membered ring, a 7-membered ring or an 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 —, The integer of 1-20 is shown. ] The adhesive polyimide is based on 100 mole parts of the diamine residue.
Containing a diamine residue derived from the dimer acid type diamine in a range of 50 to 99 mole parts,
A diamine residue derived from at least one diamine compound selected from the diamine compounds represented by the following general formulas (B1) to (B7) is contained in the range of 1 to 50 mole parts. The circuit board according to 1 or 2.

[In the 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 is independently —O—, —S—, —CO. A divalent group selected from —, —SO—, —SO ₂ —, —COO—, —CH ₂ —, —C (CH ₃ ) ₂ —, —NH— or —CONH—, wherein n ₁ is independently Represents an integer of 0 to 4. However, in the formula (B3), those that overlap with the formula (B2) are excluded, and in the formula (B5), those that overlap with the formula (B4) are excluded. ] A multilayer circuit board in which a plurality of circuit boards are laminated,
The said circuit board is a circuit board of any one of Claims 1-3, The multilayer circuit board characterized by the above-mentioned.

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