TWI680700B - Copper clad laminate and printed wiring board - Google Patents

Abstract

Provide copper-clad laminates and printed wiring boards, including polyimide insulation layer and copper foil, a) polyimide insulation layer including an adhesive polyimide layer and a low-expansion polyimide that are in contact with the surface of the copper foil Imine layer; b) the adhesive polyfluorene imide layer contains polyfluorene imide containing more than 50 mole% PMDA relative to the anhydride component and BAPP more than 50 mole% relative to the diamine component; c) low-swelling polymer The fluorene imide layer contains polyfluorene imide containing PMDA of 70 mol% to 100 mol% relative to the acid anhydride component; d) roughening the surface of the copper foil that is in contact with the adhesive polyfluorene imide layer, Rz 1.0 μm or less and Ra 0.2 μm or less; e) The amount of Ni attached to the surface of the copper foil that is in contact with the adhesive polyimide layer is 0.01 or less, the amount of Co is 0.01 to 0.5, and the amount of Mo is 0.01 to 0.5, Co + Mo is 0.1 to 0.7 (unit mg / dm ² ).

Description

Copper clad laminate and printed wiring board

The present invention provides a copper-clad laminate and a printed wiring board capable of coping with high-frequency waves caused by miniaturization and high performance of electronic equipment.

In recent years, with the progress of miniaturization, weight reduction, and space saving of electronic equipment, flexible printed wiring boards (Flexible Printed Circuits (FPC)) that are thin and light, have flexibility, and have excellent durability even after repeated bending. Demand is increasing. FPC can be packaged three-dimensionally and densely even in restricted spaces. Therefore, it expands its use in the wiring of movable parts of electronic devices such as HDDs, DVDs, and mobile phones, or in cables and connectors.

In addition to the above-mentioned high-density, high-performance devices have been developed, so it is necessary to cope with high-frequency waves of transmission signals. In information processing or information communication, in order to transmit and process large-capacity information and cooperate to increase the transmission frequency, the printed substrate material is required to reduce the transmission loss caused by the thinning of the insulating layer and the low dielectricity of the insulating layer. In the existing FPC using polyimide, the dielectric constant or dielectric loss tangent is high, and the transmission loss in the high-frequency wave region is high, so it is difficult to adapt. In order to cope with the high-frequency wave, it will use a low dielectric constant and low dielectric constant. FPC in which a liquid crystal polymer characterized by an electrical loss tangent is used as a dielectric layer. However, although liquid crystal polymers It has excellent electrical characteristics, but there is room for improvement in terms of heat resistance or adhesion to metal foil.

In order to improve the dielectric properties and adhesion to metal foil, a copper-clad laminate having a controlled concentration of the fluorene imine group in the polyfluorene layer in contact with the copper foil forming the conductor circuit has been proposed (Patent Document 1). According to Patent Document 1, although the dielectric characteristics can be controlled by a combination of the surface roughness Rz of the copper foil and a polyimide layer having a low fluorenimine concentration on the surface in contact with the copper foil, this control exists Limits and transmission characteristics are not fully met.

In order to improve the adhesion between the copper foil having a reduced roughness and the insulating layer, a copper foil having a predetermined metal deposited on the surface of the copper foil in contact with the insulating layer has been proposed (Patent Document 2). According to Patent Document 2, although the initial adhesion force and the reduction after the heat resistance test can be suppressed by the amounts of nickel, zinc, and cobalt deposited, the transmission loss is not sufficiently satisfied.

[Prior Art Literature] [Patent Literature]

[Patent Document 1] Japanese Patent No. 5031639

[Patent Document 2] Japanese Patent No. 4652020

The present invention provides a copper-clad laminate and a printed wiring board that can cope with high-frequency waves caused by miniaturization and high performance of electronic equipment.

In order to solve the problem, the inventors of the present invention paid attention to the type and amount of rust-preventive metal treated on the surface of the copper foil, and found that a copper foil having a specific surface state was used as a conductor layer and combined with the copper foil By using polyfluorene imide having specific dielectric characteristics in the insulating layer, a circuit board such as FPC having excellent impedance matching in a high-frequency wave region is obtained, and the present invention has been completed.

That is, the copper-clad laminate of the present invention includes a polyimide insulation layer and a copper foil on at least one of the surfaces of the polyimide insulation layer. The copper-clad laminate of the present invention is characterized by having the following constitutions a to e: a) the polyfluorene imine insulating layer includes an adhesive polyfluorine imide layer (i) which is in contact with the surface of the copper foil; A low-expansion polyimide layer (ii) laminated directly or indirectly on the adhesive polyimide layer (i); b) the adhesive polyimide layer (i) comprises The polyfluorene imide obtained by reacting a carboxylic acid anhydride component with a diamine component contains 50 mol% or more of pyromellitic dianhydride (PMDA) with respect to the acid anhydride component. As for the amine component, it contains 2,2-bis [4- (4-aminophenoxy) phenyl] propane (2,2-Bis [4- (4-aminophenoxy) phenyl] propane) , BAPP); c) The low-swelling polyfluorene imide layer (ii) contains a polyfluorene imide obtained by reacting a tetracarboxylic anhydride component and a diamine component. PMDA is contained in the range of 100% to 100%; d) roughening the surface of the copper foil that is in contact with the adhesive polyimide layer (i); Point average roughness (Rz) is 1.0 μm or less, The average surgical height (Ra) is 0.2 μm or less; e) the amount (Ni) of the nickel element attached to the surface of the copper foil that is in contact with the adhesive polyimide layer (i) is 0.01 mg / dm ² or less, the amount of cobalt (Co) is in the range of 0.01 mg / dm ² to 0.5 mg / dm ² , and the amount of molybdenum (Mo) is in the range of 0.01 mg / dm ² to 0.5 mg / dm ² In addition, the total amount of cobalt and molybdenum (Co + Mo) is within a range of 0.1 mg / dm ² to 0.7 mg / dm ² .

The copper-clad laminate of the present invention may be a roughening treatment of the copper foil, which can be confirmed by scanning electron microscopy (SEM) observation of the cross section of the copper foil, and rough measurement measured by the SEM observation. The maximum chemical height is less than 0.6 μm.

The copper-clad laminate of the present invention may be such that the adhesive polyfluorene imide layer (i) contains PMDA in a range of 90 mol% to 96 mol% with respect to the acid anhydride component, In the range of ear% to 10 mole%, it is selected from the group consisting of 3,3 ', 4,4'-biphenyltetracarboxylic dianhydride (3,3', 4,4'-Biphenyltetracarboxylic dianhydride, BPDA) and 4,4 One or more types of tetracarboxylic anhydrides in the group consisting of '-oxybisphthalic anhydride (4,4'-Oxydiphthalic anhydride, ODPA).

The copper-clad laminate according to the present invention may be such that the low-expansion polyfluorene imide layer (ii) contains, in the range of 70 mol% to 100 mol%, the following diamine components. The diamine represented by formula (1) contains a diamine represented by the following general formula (2) in a range of 0 mol% to 30 mol%.

[式中，R₁、R₂獨立地表示氫原子、或也可以被鹵素原子或苯基取代的烷基，R₁、R₂的至少兩個表示也可以被鹵素原子或苯基取代的烷基，n表示1~4的整數] [Chemical 1]

[Wherein R ₁ and R ₂ independently represent a hydrogen atom or an alkyl group which may be substituted with a halogen atom or a phenyl group, and at least two of R ₁ and R ₂ represent an alkyl group which may be substituted with a halogen atom or a phenyl group; Base, n represents an integer from 1 to 4]

[式中，X表示以下的結構]

[Wherein X represents the following structure]

The printed wiring board of the present invention is obtained by processing a wiring circuit of a copper foil of the optional copper-clad laminate.

The copper-clad laminate of the present invention can effectively utilize the dielectric properties of the polyimide insulation layer by suppressing the increase in resistance caused by the skin effect of the copper foil, and thus can be used as a signal requiring high-speed transmission. Suitable electronic materials.

FIG. 1 is a SEM photograph of a cross section of a copper foil used in Example 1. FIG.

Hereinafter, embodiments of the present invention will be described.

<Copper clad laminate>

The copper-clad laminate according to this embodiment is a copper-clad laminate including a polyimide insulation layer and a copper foil layer on at least one side of the polyimide insulation layer, and may be insulated only by polyimide A single-sided copper-clad laminate including copper foil on one side of the layer may be a double-sided copper-clad laminate including copper foil on both sides of the polyimide insulation layer. In addition, in order to obtain a double-sided copper-clad laminate, it can be obtained by forming the single-sided copper-clad laminate with the polyimide insulation layers facing each other and pressing and bonding by hot pressing; A copper foil is formed by pressure-bonding a copper foil on a polyimide insulation layer.

(Polyimide insulation layer)

The polyimide resin layer includes an adhesive polyimide layer (i) in contact with the surface of the copper foil, and a low-expansion polymer laminated directly or indirectly on the adhesive polyimide layer (i).醯 imine layer (ii).

Adhesive polyimide layer (i): The adhesive polyimide layer (i) contains A polyimide obtained by reacting a tetracarboxylic anhydride component with a diamine component. At least pyromellitic dianhydride (PMDA) is used as the acid anhydride component of the raw material, and 2,2-bis [4- (4- Aminophenoxy) phenyl] propane (BAPP). PMDA helps to improve the soldering heat resistance of polyimide, and BAPP helps to improve the adhesion between polyimide and copper foil. From such a viewpoint, PMDA is used in a range of 50 mol% or more, preferably 90 mol% or more, and more preferably 90 mol% to 100 mol% with respect to the acid anhydride component of the raw material. As for the diamine component, BAPP is used in a range of 50 mol% or more, preferably 90 mol% or more, and more preferably 90 mol% to 100 mol%. Furthermore, by using PMDA and BAPP of 50 mol% or more, especially 90 mol% or more, it is possible to achieve high film strength (especially tear strength) of polyimide and high adhesion to copper foil. As a result, the peel strength of the polyfluorene imide insulating layer and the copper foil can be improved.

The adhesive polyfluorene imine layer (i) is preferably selected from the group consisting of 3,3 ', 4,4'-biphenyltetracarboxylic dianhydride (BPDA) and 4,4'-oxybisphthalic dianhydride. (ODPA) An acid anhydride component of one or more tetracarboxylic anhydrides as a raw material. BPDA and ODPA have the effect of lowering the glass transition temperature to such an extent that it does not affect the lowering of the soldering heat resistance of polyimide. For example, sufficient adhesion can be ensured even during thermal compression bonding (lamination) with copper foil. The glass transition temperature of polyimide may be preferably in a range of 280 ° C to 320 ° C. In addition, BPDA and ODPA help to reduce the film strength of polyimide, on the other hand, it can reduce the concentration of fluorene imine, so it improves the dielectric characteristics, and further contributes to the reduction of polar groups of polyimide. Improve the moisture absorption characteristics of polyimide, and make the transmission loss of FPC lower. From such a viewpoint, it is preferable to use BPDA or ODPA in the range of 4 mol% to 10 mol% as the acid anhydride component of the raw material. In this case, it is preferable to use PMDA in the range of 90 mol% to 96 mol% with respect to the acid anhydride component of the raw material. Here, the "fluorene imino group concentration" is a value obtained by dividing the molecular weight of the fluorene imino moiety (-(CO) ₂ -N-) in the polyfluorene imide by the molecular weight of the entire structure of the polyfluorene imine.

Low-expansion polyimide layer (ii):

The low-swelling polyfluorene imide layer (ii) contains a polyfluorene imide obtained by reacting a tetracarboxylic anhydride component and a diamine component, and at least PMDA is used as the acid anhydride component of the raw material. PMDA can reduce the coefficient of thermal expansion (CTE) of polyimide. From the viewpoint of suppressing warpage or reduction in dimensional stability when forming a copper-clad laminate, as the polyimide insulation layer, it is preferable to control the CTE in a range of 10 ppm / K to 30 ppm / K. The imine layer (ii) is suitably used as a base film layer (a main layer of an insulating resin layer). The CTE of the polyfluorene imide constituting the low-swelling polyfluorene imine layer (ii) is preferably within a range of 1 ppm / K to 25 ppm / K, and more preferably within a range of 10 ppm / K to 20 ppm / K. From this viewpoint, PMDA is used in a range of 70 mol% to 100 mol% with respect to the acid anhydride component of the raw material.

The low-swelling polyfluorene imine layer (ii) preferably uses a diamine represented by the following general formula (1) and a diamine represented by the following general formula (2) as a raw material diamine component.

[式中，R₁、R₂獨立地表示氫原子、或也可以被鹵素原子或苯基取代的烷基，R₁、R₂的至少兩個表示也可以被鹵素原子或苯基取代的烷基，n表示1~4的整數] [Chemical 4]

[Wherein R ₁ and R ₂ independently represent a hydrogen atom or an alkyl group which may be substituted with a halogen atom or a phenyl group, and at least two of R ₁ and R ₂ represent an alkyl group which may be substituted with a halogen atom or a phenyl group; Base, n represents an integer from 1 to 4]

[式中，X表示以下的結構]

[Wherein X represents the following structure]

The diamine represented by the general formula (1) is an aromatic diamine, which contributes to low CTE or improvement of dielectric properties, and further contributes to low moisture absorption or high heat resistance. From such a viewpoint, the general formula (1) can be used within a range of preferably 70 mol% or more, and more preferably 70 mol% to 100 mol% with respect to the diamine component of the raw material. Represents a diamine.

Specific examples of the diamine represented by the general formula (1) include 4,4'-diamino-2,2'-dimethylbiphenyl, 4,4'-diamino-3,3 ' -Dimethylbiphenyl, 2,3'-dimethyl-4,4'-diaminobiphenyl, 3,3 ', 5-trimethyl-4,4'-diaminobiphenyl, 2 , 2 ', 5,5'-tetramethyl-4,4'-diaminobiphenyl, 3,3', 5,5'-tetramethyl-4,4'-diaminobiphenyl, 2 , 3 ', 5,5'-tetramethyl-4,4'-diaminobiphenyl, 2,2', 3,5-tetramethyl-4,4'-diaminobiphenyl, 2, 2 ', 3,3', 5,5'-hexamethyl-4,4'-diaminobiphenyl, 2,2 ', 3,3', 5,5 ', 6,6'-octadecyl -4,4'-diaminobiphenyl, 2,5-dimethylmethyl-4,4'-diaminobiphenyl, 2,3,5,6-tetramethyl-4,4 ' -Diaminobiphenyl, 2,2'-diethyl-4,4'-diaminobiphenyl, 2,2'-dipropyl-4,4'-diaminobiphenyl, 2,2 '-Bis (1-methylethyl) -4,4'-diaminobiphenyl, 5,5'-dimethyl-2,2'-bis (1-methylethyl) -4,4 '-Diaminobiphenyl, 2,2'-dioctyl-4,4'-diaminobiphenyl, 2,2'-bis (phenylmethyl) -4,4'-diamine Benzene, 4,4'-diamino-2,2'-bis (trifluoromethyl) biphenyl, 2,2'-divinyl-4,4'-diaminobiphenyl and the like.

Among the diamines represented by the general formula (1), R ₁ and R ₂ in the general formula (1) are preferably alkyl groups having 1 to 3 carbon atoms, and more preferably 4,4′-di Amino-2,2'-dimethylbiphenyl (m-TB), 4,4'-diamino-3,3'-dimethylbiphenyl.

In addition to the diamine represented by the general formula (1), the general formula (2) may be used in a range of 0 mol% to 30 mol% with respect to the diamine component of the raw material. The indicated diamine. The diamine represented by the general formula (2) contributes to the high CTE of the polyfluorene imine, and on the other hand, reduces the concentration of the fluorene imine group, thereby improving the dielectric characteristics. From such a viewpoint, the diamine component can be used within a range of preferably 1 mol% to 30 mol%, and more preferably 5 mol% to 30 mol% relative to the diamine component of the raw material. The diamine represented by the general formula (2).

Specific examples of the diamine represented by the general formula (2) include 1,4-bis (4-aminophenoxy) benzene and 1,3-bis (4-aminophenoxy) benzene (1 , 3-Bis (4-aminophenoxy) benzene, TPE-R), 2,2-bis [4- (4-aminophenoxy) phenyl] propane (BAPP), and the like.

As the acid anhydride component, an aromatic tetracarboxylic anhydride other than the acid anhydride may be used to such an extent that the effect of the present invention is not inhibited.

As the diamine component, an aromatic diamine other than the diamine may be used to such an extent that the effect of the present invention is not inhibited.

The thickness of the polyfluorene imide insulating layer may be in a range of 6 μm to 50 μm, and preferably in a range of 9 μm to 45 μm. If the thickness of the polyimide insulating layer is less than 6 μm, there may be a problem such as wrinkling during transportation in the production of a copper-clad laminate, etc. On the other hand, if the thickness of the polyimide insulating layer exceeds 50 μm, There is a concern that problems may occur in dimensional stability, bendability, and the like during the production of a copper-clad laminate. In the case where the polyfluorene imide insulating layer is formed of a plurality of layers, the total thickness may be within the above range.

When the polyimide insulation layer is used in a circuit board such as FPC, the dielectric constant is 3 GHz in order to set the transmission loss at the same level as that of a copper-clad laminate made of a liquid crystal polymer in the frequency band of 1 GHz to 40 GHz. It is preferably 3.1 or less, and the dielectric loss tangent is less than 0.005. By controlling the dielectric properties of the polyimide insulation layer within such a range, it is possible to suppress transmission loss of a high-frequency wave signal on a transmission path when used in a circuit board such as an FPC.

The polyimide insulation layer is used for circuit boards such as FPC. In this case, the transmission loss is reduced to the same level as the liquid crystal polymer. The dielectric constant at 10 GHz is preferably 3.0 or less, and the dielectric loss tangent may be 0.005 or less. By controlling the dielectric properties of the polyimide insulation layer within such a range, it is possible to suppress transmission loss of a high-frequency wave signal on a transmission path when used in a circuit board such as an FPC.

Considering the ease of controlling the thickness of the polyimide insulation layer or the physical properties, a so-called casting (coating) method in which a polyamidic acid solution is directly applied to a copper foil and then dried and hardened by heat treatment is preferably used. In addition, when a polyimide insulating layer is provided in multiple layers, it can be formed by sequentially coating another polyamidic acid solution on a polyamidic acid solution containing different constituent components. When the polyfluorene imide insulating layer includes a plurality of layers, the polyfluorine imide precursor resin having the same configuration may be used two or more times.

These acid anhydrides and diamines may be used alone, or two or more of them may be used in combination. By selecting the type of the acid anhydride and the diamine, or the respective molar ratios when two or more kinds of the acid anhydride or the diamine are used, thermal expansion properties, adhesiveness, glass transition temperature, and the like can be controlled.

The polyfluorene imide constituting the polyfluorene imide insulating layer can be produced by reacting the aromatic tetracarboxylic anhydride and the aromatic diamine in a solvent, and then heating and closing the ring after forming a precursor resin. For example, an acid anhydride component and a diamine component are substantially dissolved in an organic solvent, and a polymerization reaction is performed by stirring at a temperature in a range of 0 ° C to 100 ° C for 30 minutes to 24 hours, thereby obtaining a polyfluorene. Polyimide precursor of imine. During the reaction, the produced precursor is in a range of 5% to 30% by weight in the organic solvent, and preferably in a range of 10% to 20% by weight. Dissolve the reaction ingredients in a way. Examples of the organic solvent used in the polymerization include N, N-dimethylformamide, N, N-Dimethylacetamide (DMAc), and N-methyl-2-pyrrolidone. , 2-butanone, dimethylsulfine, dimethyl sulfate, cyclohexanone, dioxane, tetrahydrofuran, diglyme, triglyme, etc. These solvents may be used in combination of two or more kinds, and may also be used in combination with aromatic hydrocarbons such as xylene and toluene. In addition, the amount of such an organic solvent used is not particularly limited, and it is preferable to adjust the concentration of the polyamidic acid solution (polyimide precursor solution) obtained by the polymerization reaction to an amount of about 5% to 30% by weight. use.

The synthesized precursors are generally advantageously used as a reaction solvent solution, and can be concentrated, diluted or replaced with other organic solvents as needed. Moreover, the precursor is generally excellent in the solubility of the solvent, and thus can be used favorably. The method of imidating the precursor sulfonium is not particularly limited, and for example, heat treatment may be suitably used, that is, heating in the solvent at a temperature in a range of 80 ° C. to 400 ° C. for 1 hour to 24 hours.

The polyfluorene imide insulating layer may further contain an inorganic filler as necessary. Specific examples include silicon dioxide, aluminum oxide, magnesium oxide, beryllium oxide, boron nitride, aluminum nitride, silicon nitride, aluminum fluoride, and calcium fluoride. These inorganic fillers may be used singly or in combination of two or more.

(Copper foil)

In the copper-clad laminate of the present embodiment, the surface where the copper foil and the adhesive polyimide layer (i) are in contact with each other is roughened, and the ten-point average roughness (Rz) is 1.0 μm or less, The arithmetic average roughness (Ra) is 0.2 μm or less. The material of the copper foil may be a copper alloy.

In a state where a high-frequency wave signal is supplied to a signal wiring, there are problems in that a current flows only on the surface of the signal wiring, the effective cross-sectional area of the current flowing decreases, the DC resistance increases, and the signal is attenuated (skin effect). By reducing the surface roughness of the surface where the copper foil and the polyimide insulation layer are in contact with each other, it is possible to suppress an increase in the resistance of the signal wiring due to the skin effect. Based on this knowledge, the inventors of the present invention conducted further studies on reducing the conductor loss, and as a result, it was found that if the surface roughness of the copper foil is reduced to a certain degree, the effect of reducing the conductor loss is not so great. In addition, if the surface roughness is reduced in order to meet the electrical performance requirement standard, the adhesion (peel strength) between the copper foil and the polyimide insulation layer becomes weak. Therefore, from the viewpoint of satisfying the electrical performance requirements and ensuring the adhesion to the polyimide insulation layer, the surface of the copper foil needs to meet the requirements for the surface roughness and be roughened.

The roughening treatment of the copper foil can be formed by, for example, using a plating method to attach a film (luminous film) having fine unevenness on the surface of the copper foil with the same material (for example, copper) as the copper foil. In addition, the roughening treatment of the copper foil can be confirmed by scanning electron microscope (SEM) observation of the cross section of the copper foil, and more accurately reflects the fine unevenness on the surface of the copper foil against the current flowing on the surface of the copper foil due to the skin effect. Give impact. From such a viewpoint, the maximum value of the roughened height of the copper foil measured by SEM observation is preferably less than 0.6 μm. If the maximum value of the roughened height of the copper foil is less than 0.6 μm, it is possible to satisfy the requirements of ensuring adhesion to the polyimide insulation layer and suppressing wiring resistance. Increased demand for trade off relationships.

The copper-clad laminate according to the present embodiment performs a metal precipitation treatment to deposit at least cobalt and molybdenum on the surface of the copper foil that is in contact with the adhesive polyimide layer (i). With this metal precipitation treatment, the amount of nickel (Ni) on the surface of the copper foil is 0.01 mg / dm ² or less, and the amount of cobalt (Co) is within a range of 0.01 mg / dm ² to 0.5 mg / dm ² The amount of molybdenum (Mo) is in the range of 0.01 mg / dm ² to 0.5 mg / dm ² , and the total amount of cobalt and molybdenum (Co + Mo) is 0.1 mg / dm ² to 0.7 mg / dm ² Control within the range.

Nickel is a complete solid solution with respect to copper, and can be made into an alloy state, or nickel easily diffuses with respect to copper, and is easily made into an alloy state. In this state, the electrical resistance is larger than that of the copper simple substance, in other words, the electrical conductivity is reduced. Due to this phenomenon, if the amount of the nickel element adhered on the surface of the copper foil is large, the resistance of copper alloyed with nickel increases. As a result, the resistance of the signal wiring due to the skin effect increases, and the loss during signal transmission increases. From such a viewpoint, in the copper-clad laminate of the present embodiment, the amount of the nickel element attached to the surface where the copper foil and the adhesive polyimide layer (i) are in contact is suppressed to 0.01 mg / dm ² or less. .

Further, regarding the reduction of conductor loss, the inventors have found that in addition to the surface roughness of the copper foil, the amount of metal attached to the surface of the copper foil by metal precipitation treatment affects the conductor loss. If the amount of metal attached is large , It is difficult to reduce the conductor loss. On the other hand, it was confirmed that the smaller the adhesion amount of the metal subjected to the metal precipitation treatment, the lower the adhesion strength between the resin and the copper foil and its long-term reliability or chemical resistance. From such a viewpoint, in the copper-clad laminate of the present embodiment, it is difficult to make an alloy with copper, and there is a certain amount of metal on the surface of the copper foil that is a metal that is less likely to generate increased resistance than nickel. Cobalt and molybdenum can suppress conductor loss, and ensure the adhesion strength between resin and copper foil, its long-term reliability, and chemical resistance. Therefore, the amount of cobalt element (Co) attached to the surface of the copper foil used in the present embodiment in contact with the adhesive polyimide layer (i) is 0.01 mg / dm ² to 0.5 mg / dm ² Within the range, the amount (Mo) of the molybdenum element is in the range of 0.01 mg / dm ² to 0.5 mg / dm ² . In addition, by setting the total amount of cobalt and molybdenum elements (Co + Mo) to within a range of 0.1 mg / dm ² to 0.7 mg / dm ² , it is possible to suppress the buildup of wiring between wirings during wiring processing of a copper-clad laminate. The etching residue of the imine part can suppress the reduction of the resistance to the chemical solution caused by the etching, and the reduction of the adhesion strength between the copper foil and the polyimide and the reduction of its long-term reliability.

The metal precipitation treatment of the copper foil used in the copper-clad laminate according to this embodiment is not particularly limited as long as it can deposit the metal in a predetermined amount on the surface of the copper foil. For example, as an example of the metal precipitation treatment, a rust prevention treatment using the metal may be mentioned, and specifically, a plating treatment is performed using a bath containing a predetermined amount of the metal, and the surface is deposited on a copper foil. Metal methods, etc.

In addition, the copper foil used in the copper-clad laminate according to the present embodiment may be subjected to, for example, a siding, an aluminum alcoholate, or an aluminum chelate on the surface of the copper foil in order to improve the adhesion in addition to the metal precipitation treatment. Surface treatment of chemicals, silane coupling agents, etc.

In the copper-clad laminate according to this embodiment, a commercially available copper foil can be used as the copper foil. Specific examples thereof include those manufactured by Fukuda Metal Foil Industry Co., Ltd. CF-T49A-DS-HD (trade name) and the like.

In the copper-clad laminate of the present embodiment, for example, the thickness of the copper foil when used in the production of FPC is preferably in a range of 3 μm to 50 μm, and more preferably in a range of 5 μm to 30 μm. The line width is reduced, and the thickness of the copper foil is preferably within a range of 5 μm to 20 μm.

<Printed wiring board>

The printed wiring board of the present embodiment can be manufactured by processing a copper foil of the copper-clad laminate of the present embodiment into a pattern by using a common method to form a wiring layer, thereby manufacturing a printed wiring board as an embodiment of the present invention.

Hereinafter, an example of the case of a casting method is given as a representative, and the manufacturing method of the printed wiring board of this embodiment is demonstrated concretely.

First, the method for manufacturing a copper-clad laminate may include the following steps (1) to (3).

step 1):

Step (1) is a step of obtaining a resin solution of polyamidic acid which is a precursor of the polyamidoimine of the present invention.

Step (2):

Step (2) is a step of applying a polyamic acid resin solution on a copper foil to form a coating film. The copper foil can be used in the shape of a slice, a rolled copper foil, or an endless belt. In order to obtain productivity, it is effective to use a roll-shaped or endless belt-like shape and a continuous production form. In addition, from the viewpoint that the improvement effect of the accuracy of the wiring pattern in the printed wiring board is more exhibited, the copper foil is preferably formed into a long rolled copper. Foil.

A method for forming a coating film can be formed by directly coating a resin solution of polyamic acid on a copper foil and then drying it. The coating method is not particularly limited, and for example, coating can be performed using a coater such as a comma, a mold, a knife, a die lip, or the like.

The polyimide insulating layer may be a single layer or may include a plurality of layers. In the case where the polyfluorene imide insulating layer is multilayered, it can be formed by sequentially coating other precursors on a precursor layer containing different constituent components. When the precursor layer includes three or more layers, a precursor having the same structure two or more times may be used. A simple two-layer structure or a single-layer structure is industrially advantageous and is therefore preferred. The thickness of the precursor layer (after drying) may be, for example, in a range of 3 μm to 100 μm, and preferably in a range of 3 μm to 50 μm.

When the polyimide insulation layer is a multilayer, it is preferable to form the precursor layer so that the polyimide insulation layer in contact with the copper foil becomes a thermoplastic polyimide insulation layer. By using a thermoplastic polyimide, the adhesiveness with copper foil can be improved. The thermoplastic polyfluorene imide preferably has a glass transition temperature (Tg) of 360 ° C or lower, and more preferably 200 ° C to 320 ° C.

In addition, a single-layer or multi-layer precursor layer may be temporarily imidized to form a single-layer or multi-layer polyimide insulation layer, and then a precursor layer may be further formed thereon.

Step (3):

Step (3) is a step in which the coating film is heat-treated and then imidized to form a polyimide insulating layer. The method of the imidization is not particularly limited, and for example, a temperature range of 80 ° C. to 400 ° C. may be suitably used, and a range of 1 minute to 60 minutes may be suitably used. Heat treatment within time. In order to suppress the oxidation of the metal layer, heat treatment in a low-oxygen environment is preferable, and specifically, it is preferably performed in an environment of an inert gas such as nitrogen or a rare gas, in an environment of a reducing gas such as hydrogen, or in a vacuum. Through heat treatment, the polyfluorene phosphonium imide in the coating film is imidized to form a polyfluorene imine.

As described above, a copper-clad laminate including a polyimide insulating layer (single layer or multiple layers) and a copper foil can be manufactured.

In addition, the method for manufacturing a circuit board may further include the following step (4) in addition to the steps (1) to (3).

Step (4):

Step (4) is a step of patterning the copper foil of the copper-clad laminate to form a wiring layer. In this step, a copper foil is etched into a predetermined shape to form a pattern and processed into a wiring layer, thereby obtaining a printed wiring board. The etching can be performed by, for example, an arbitrary method using a photolithography technique or the like.

In the above description, only the characteristic steps of the method for manufacturing a printed wiring board have been described. That is, when manufacturing a printed wiring board, steps other than those usually performed, such as through-hole processing in the previous step, or terminal plating and external shape processing in the later step, may be performed according to a common method.

As described above, by using the polyfluorene imide insulating layer and the copper foil of the present embodiment, a copper-clad laminate having excellent impedance matching can be formed. In addition, by using the polyfluorene imide insulating layer and the copper foil of the present embodiment, the circuit board typified by FPC can improve the electrical signal transmission characteristics and reliability.

[Example]

Examples are given below to describe the features of the present invention in more detail. However, the scope of the present invention is not limited to the examples. In the following examples, unless otherwise specified, various measurements and evaluations were performed as described below.

[Determination of tear propagation resistance]

The tear propagation resistance was measured by preparing a 63.5 mm × 50 mm test piece, cutting a 12.7 mm incision into the test piece, and using a light load tear tester manufactured by Toyo Seiki.

[Measurement of glass transition temperature (Tg)]

The glass transition temperature was increased from 30 ° C. at a temperature rise rate of 4 ° C./min using a polyimide film having a size of 5 mm × 20 mm using a viscoelasticity measuring device (DMA: manufactured by TA Instruments, trade name; RSA3). The temperature was measured at 400 ° C. at a frequency of 1 Hz, and the temperature at which the change in the elastic modulus reached the maximum (the maximum tan δ change rate) was evaluated as the glass transition temperature.

[Measurement of peel strength and long-term reliability]

The peel strength was measured by using a TENSILON TESTER (manufactured by Toyo Seiki Seisakusho, Ltd .; trade name; Strograph VE-1D) with a double-sided tape to process the metal on the conductor layer side to a width of 1 mm. The resin layer side of the base material (including the metal / resin layer laminate) of the wiring is fixed to the SUS board, and the metal wiring is peeled from the resin layer at a speed of 50 mm / min in the 180 ° direction. force.

The long-term reliability is a percentage of the force at the time of peeling and the force before the heat treatment obtained after the wiring processing substrate is subjected to a heat treatment in an atmospheric environment at 150 ° C. for 1000 hours as the retention rate.

The pass / fail judgment is evaluated as "Pass" with a peel strength of 1.0 kN / m or more, and "Fail" with less than 1.0 kN / m. As for long-term reliability, the retention rate of the peel strength is 70% or more. As "excellent", more than 60% were evaluated as "good", more than 50% were evaluated as "passing", and less than 50% were evaluated as "passing".

[Evaluation of chemical resistance]

The evaluation of chemical resistance was performed by immersing the metal on the conductor layer side into a 1 mm wide wiring substrate (a laminate including a metal / resin layer) in a 20% by weight hydrochloric acid aqueous solution at 50 ° C for 1 hour. After the wiring was peeled off, the wiring or the resin layer side of the wiring was peeled off, and the penetration width of the aqueous hydrochloric acid solution that penetrated between the metal / resin layers was evaluated.

Chemical resistance was evaluated as "excellent" with no infiltration, "good" with an infiltration width of less than 20 µm, "passing" with an infiltration width of less than 30 µm, and "passing" with an infiltration width of 30 µm or more.

[Determination of dielectric constant and dielectric loss tangent]

The dielectric constant and the dielectric loss tangent are measured using a cavity resonator perturbation dielectric constant evaluation device (manufactured by Agilent, trade name: vector network analyzer E8363B), and measured at a predetermined frequency. The dielectric constant and dielectric loss tangent of the resin sheet (resin sheet after hardening). In addition, the resin sheet used in the measurement was left for 24 hours under conditions of a temperature of 24 ° C to 26 ° C and a humidity of 45% to 55%.

[Measurement of surface roughness of copper foil]

1) Determination of arithmetic mean height (Ra)

A stylus-type surface roughness meter (manufactured by Kosaka Research Institute Co., Ltd., trade name: Surfcorder ET-3000) was used to determine the measurement conditions under a pressure of 100 μN, a speed of 20 μm, and a range of 800 μm. The surface roughness is calculated by a method according to JIS-B0601: 1994.

2) Measurement of ten-point average roughness (Rz)

A stylus-type surface roughness meter (manufactured by Kosaka Research Institute Co., Ltd., trade name: Surfcorder ET-3000) was used to determine the measurement conditions under a pressure of 100 μN, a speed of 20 μm, and a range of 800 μm. The surface roughness is calculated by a method according to JIS-B0601: 1994.

[Measurement of Roughening Height of Copper Foil]

The cross-section forming process of the target copper foil was performed by ion irradiation using a cross-section sample preparation device (manufactured by Japan Electronics Corporation, trade name: SM-09010 cross section polisher), and the exposed copper foil was subjected to 5200 times The cross section was observed by SEM, and an image of the cross section of the copper foil was obtained. Using the obtained image, a roughened height was calculated based on the scale recorded in the image.

[Measurement of metal elements on the surface of copper foil subjected to metal precipitation treatment]

The analytical surface of the copper foil was masked, and the analytical surface was dissolved with 1N-nitric acid to a volume of 100 mL. Then, an inductively coupled plasma atomic emission spectrometer (Inductively Coupled Plasma-) manufactured by Perkinelmer was used. Atomic Emission Spectrometry (ICP-AES) Optima 4300 was used for measurement.

[Evaluation of transmission characteristics]

A circuit-processed evaluation sample of a microwave transmission line having a characteristic impedance of 50 Ω was used to perform circuit processing on a copper-clad laminate, and the transmission characteristics of the circuit-processed side (transmission line side) were evaluated. A vector network analyzer corrected by the SHORT-OPEN-LOOD-Thru (SOLT) method was used to measure the S-parameters in a predetermined frequency region, and the evaluation was performed with S21 (insertion loss).

The transmission loss was evaluated as "excellent" at less than 2.7dB / 10cm at a frequency of 5GHz, and "good" was evaluated at 2.7dB / 10cm or more and less than 3.0dB / 10cm, and 3.0dB / 10cm or more and less than 3.3dB. A / 10cm was evaluated as a "passing", and 3.3dB / 10cm or more was evaluated as a "passing". Moreover, at a frequency of 10 GHz, less than 4.1 dB / 10 cm is evaluated as "excellent", 4.1 dB / 10 cm or more and less than 4.6 dB / 10 cm is evaluated as "good", and 4.6 dB / 10 cm or more is less than 5.1 dB / 10 cm. The evaluation was "passed", and 5.1dB / 10cm or more was evaluated as "passed".

The abbreviations used in the synthesis examples indicate the following compounds.

m-TB: 2,2'-dimethyl-4,4'-diaminobiphenyl

TPE-R: 1,3-bis (4-aminophenoxy) benzene

BAPP: 2,2-bis [4- (4-aminophenoxy) phenyl] propane

PMDA: pyromellitic dianhydride

BPDA: 3,3 ', 4,4'-biphenyltetracarboxylic dianhydride

DMAc: N, N-dimethylacetamide

(Synthesis example 1)

Add the amount of solid content after polymerization to 15wt% in the reaction vessel. DMAc was stirred, and m-TB and TPE-R were introduced so that the molar ratio (m-TB: TPE-R) became 80:20. After sufficient stirring was performed until the charged diamine was completely dissolved, PMDA was added so that the molar ratio of the acid anhydride: diamine became 0.985: 1.000. Thereafter, stirring was continued at room temperature for 3 hours to obtain a polyamidic acid solution A having a viscosity of 25,000 cP.

(Synthesis example 2)

DMAc having a solid content concentration of 12 wt% after polymerization was added to the reaction vessel, stirred, and BAPP was charged. After sufficient stirring was performed until the charged diamine was completely dissolved, PMDA was added so that the molar ratio of the acid anhydride: diamine became 0.990: 1.000. Thereafter, stirring was continued at room temperature for 3 hours to obtain a polyamidic acid solution B having a viscosity of 2,300 cP.

(Synthesis example 3)

DMAc having a solid content concentration of 12 wt% after polymerization was added to the reaction vessel, stirred, and BAPP was charged. After sufficiently stirring until the diamine was completely dissolved, PMDA and BPDA were added so that the molar ratio of acid anhydride: diamine became 0.990: 1.000. PMDA and BPDA were added in such a way that the Mohr ratio (PMDA: BPDA) became 95: 5. Thereafter, stirring was continued at room temperature for 3 hours to obtain a polyamidic acid solution C having a viscosity of 2,000 cP.

(Production example 1)

On a copper foil having a thickness of 12 μm, the polyamic acid solution B was uniformly applied, and the solvent was removed by heating and drying at 120 ° C. for 1 minute and 30 seconds. This operation was repeated three times, and the thickness after heat processing was about 25 micrometers. After drying, advance from 130 ℃ The stepwise heat treatment is performed until the temperature is above 300 ° C., so that the imidization is completed to obtain a copper-clad laminate. About the obtained copper clad laminated board, the copper foil was etched and removed, and the polyimide film 1 was produced. The polyimide film 1 has a tear propagation resistance of 8.0 kN / m and a glass transition temperature of 315 ° C.

(Production example 2)

A polyimide film 2 was produced in the same manner as in Production Example 1 except that the polyamic acid solution C was used instead of the polyamic acid solution B. The tear resistance of the polyimide film 2 was 7.5 kN / m, and the glass transition temperature was 310 ° C.

[Example 1]

An electrolytic copper foil (having a thickness of 12 μm and a MD direction (Machine Direction on the polyimide insulation layer side) having a surface roughness Rz of 0.5 μm and Ra of 0.1 μm) was prepared. After roughening the surface of the copper foil, a plating treatment (metal precipitation treatment) containing a predetermined amount of cobalt and molybdenum is performed, and further zinc plating treatment and chromate treatment are sequentially performed to obtain a copper foil 1. Table 1 shows the analysis values of the metal elements subjected to the metal precipitation treatment in the copper foil 1. Moreover, the SEM photograph of the cross section of the copper foil 1 is shown in FIG. When referring to the SEM photograph, the maximum value of the roughening height of the roughening treatment was 0.25 μm.

On the surface of the copper foil 1 subjected to the metal precipitation treatment, a polyamic acid solution B, a polyamic acid solution A, and a polyamic acid solution B were sequentially applied (casted) so that the thicknesses after the heat treatment became 2 μm, respectively. , 21 μm and 2 μm. After drying, stepwise heat treatment is performed from 130 ° C. to 300 ° C. or more, and the imidization is completed to obtain a single-sided copper-clad laminate 1. Polyimide insulation layer side of the obtained single-sided copper-clad laminate 1 The copper foil 1 was overlapped, and thermocompression bonding (lamination) was performed for 15 minutes under the conditions of 340 ° C. and a pressure of 6.7 MPa to obtain a double-sided copper-clad laminate 1. The evaluation results of the double-sided copper-clad laminate 1 are shown in Table 2. As shown in Table 2, the transmission losses of 5 GHz and 10 GHz of the double-sided copper-clad laminate 1 were 2.5 dB / 10 cm and 3.9 dB / 10 cm, respectively. No penetration of hydrochloric acid was confirmed. In addition, the initial values of the peel strength and the retention after 150 hours at 1000 ° C. were 1.1 kN / m and 82% on the casting side, and 1.6 kN / m and 73% on the lamination side, respectively.

(Comparative example 1)

An electrolytic copper foil (having a thickness of 12 μm and a surface roughness Rz in the MD direction of the polyimide insulation layer side of 0.4 μm and Ra of 0.1 μm) was prepared. After the surface of this copper foil is roughened, a plating treatment (metal precipitation treatment) including a predetermined amount of nickel and cobalt is performed, and then a zinc plating treatment and a chromate treatment are sequentially performed to obtain a copper foil 2. Table 1 shows the analysis values of the metal elements subjected to the metal precipitation treatment in the copper foil 2. When the SEM photograph of the cross section of the copper foil 2 is referred to, the maximum value of the roughening height of the roughening process is 0.36 μm.

A double-sided copper-clad laminate 2 was obtained in the same manner as in Example 1 except that the copper foil 2 was used instead of the copper foil 1. The evaluation results of the double-sided copper-clad laminate 2 are shown in Table 2. As shown in Table 2, the 5 GHz and 10 GHz transmission losses of the double-sided copper-clad laminate 1 are 3.4 dB / 10 cm and 5.2 dB / 10 cm, respectively.

(Comparative example 2)

An electrolytic copper foil (having a thickness of 12 μm and a surface roughness Rz in the MD direction of the polyimide insulation layer side of 0.4 μm and Ra of 0.1 μm) was prepared. Roughen the surface of this copper foil After the treatment, a plating treatment (metal precipitation treatment) including a predetermined amount of nickel is performed, and further, a zinc plating treatment and a chromate treatment are sequentially performed to obtain a copper foil 3. Table 1 shows the analysis values of the metal elements subjected to the metal precipitation treatment in the copper foil 3. When the SEM photograph of the cross section of the copper foil 3 is referred to, the maximum value of the roughening height of the roughening process is 0.12 μm.

A double-sided copper-clad laminate 3 was obtained in the same manner as in Example 1 except that the copper foil 3 was used instead of the copper foil 1. The evaluation results of the double-sided copper-clad laminate 3 are shown in Table 2. As shown in Table 2, the transmission losses at 5 GHz and 10 GHz of the double-sided copper-clad laminate 3 were 2.5 dB / 10 cm and 3.9 dB / 10 cm, respectively, but the penetration of hydrochloric acid was 52.7 μm. In addition, the initial values of the peel strength and the retention rates after 150 hours and 1000 hours were 1.2 kN / m and 20% on the casting side, and 1.4 kN / m and 17% on the lamination side, respectively.

(Comparative example 3)

An electrolytic copper foil (having a thickness of 12 μm, a surface roughness Rz in the MD direction of the polyimide insulation layer side of 0.8 μm, and Ra of 0.2 μm) was prepared. After roughening the surface of the copper foil, a plating treatment (metal precipitation treatment) including a predetermined amount of nickel is performed, followed by a plating treatment including a predetermined amount of cobalt and molybdenum, and further a zinc plating treatment and Chromate treatment, copper foil 4 was obtained. Table 1 shows the analysis values of the metal elements subjected to the metal precipitation treatment in the copper foil 4. When the SEM photograph of the cross section of the copper foil 4 is referred to, the maximum value of the roughening height of the roughening process is 0.09 μm.

A double-sided copper-clad laminate 4 was obtained in the same manner as in Example 1 except that the copper foil 4 was used instead of the copper foil 1. The evaluation results of the double-sided copper-clad laminate 4 are shown in Table 2. As shown in Table 2, the transmission frequency of 5GHz and 10GHz of double-sided copper-clad laminate 4 The transmission loss was 2.8dB / 10cm and 4.3dB / 10cm, respectively, but the penetration of hydrochloric acid was 14.7 μm. In addition, the initial values of the peel strength and the retention rates after 150 hours and 1000 ° C. were 1.1 kN / m and 31% on the casting side, and 1.6 kN / m and 41% on the lamination side, respectively.

The above results are collectively shown in Tables 1 and 2.

As mentioned above, although embodiment of this invention was described in detail for the purpose of illustration, this invention is not limited to the said embodiment.

Claims (5)

A copper-clad laminate including a polyimide insulation layer and a copper foil on at least one side of the polyimide insulation layer. The copper-clad laminate is characterized in that: It has the following constitution a to constitution e: a) The polyfluorene imide insulating layer includes an adhesive polyfluorine imide layer (i) which is in contact with the surface of the copper foil, and is laminated directly or indirectly on the adhesive The low-swelling polyfluorene imine layer (ii) on the flexible polyfluorene imine layer (i); b) the adhesive polyfluorine imide layer (i) comprises a reaction obtained by reacting a tetracarboxylic anhydride component with a diamine component Polyimide contains 50 mol% or more of pyromellitic dianhydride (PMDA) relative to the tetracarboxylic anhydride component and 50 mol% or more of the diamine component 2,2-bis [4- (4-aminophenoxy) phenyl] propane (BAPP); c) the low-swelling polyfluorene imine layer (ii) comprises a tetracarboxylic anhydride component and a diamine The polyfluorene imide obtained by the component reaction contains pyromellitic dianhydride in the range of 70 mol% to 100 mol% relative to the tetracarboxylic anhydride component; d) in the copper foil Adhesive polyurea The surfaces of layer (i) are roughened. The ten-point average roughness (Rz) of the copper foil surface is 1.0 μm or less, and the arithmetic mean height (Ra) is 0.2 μm or less. The amount of nickel element (Ni) attached to the surface in contact with the adhesive polyfluorene imine layer (i) is 0.01 mg / dm ² or less, and the amount of cobalt element (Co) is 0.01 mg / dm ² In the range of ~ 0.5 mg / dm ² , the amount of molybdenum element (Mo) is in the range of 0.01 mg / dm ² to 0.5 mg / dm ² , and the total amount of cobalt and molybdenum elements (Co + Mo) is 0.1 mg / dm ² to 0.7 mg / dm ² . The copper-clad laminate according to item 1 of the scope of patent application, wherein the roughening treatment of the copper foil can be confirmed by scanning electron microscope (SEM) observation of a cross section of the copper foil, and the scanning method is used. The maximum value of the roughened height measured by observation with an electron microscope was less than 0.6 μm. The copper-clad laminate according to item 1 or item 2 of the patent application scope, wherein: the adhesive polyfluorene imine layer (i) is 90 mol% to the tetracarboxylic anhydride component. Pyromellitic dianhydride is contained in the range of 96 mol%, and is selected from the group consisting of 3,3 ', 4,4'-biphenyltetracarboxylic dianhydride (BPDA) in the range of 4 mol% to 10 mol%. ) And one or more tetracarboxylic anhydrides in the group consisting of 4,4'-oxybisphthalic dianhydride (ODPA). The copper-clad laminate according to item 1 or item 2 of the scope of patent application, wherein the low-expansion polyfluorene imine layer (ii) is 70 mol% to the diamine component. The diamine represented by the following general formula (1) is contained in the range of 100 mole%, and the diamine represented by the following general formula (2) is contained in the range of 0 mole% to 30 mole%; [Wherein R ₁ and R ₂ independently represent a hydrogen atom or an alkyl group which may be substituted with a halogen atom or a phenyl group, and at least two of R ₁ and R ₂ represent an alkyl group which may be substituted with a halogen atom or a phenyl group; Base, n represents an integer from 1 to 4] [Wherein X represents the following structure] A printed wiring board characterized by being processed by wiring circuits on the copper foil of the copper-clad laminate as described in any one of claims 1 to 4 of the scope of patent application.