JP6528578B2 - Polyimide resin and laminate - Google Patents

Description

  The present invention relates to a novel polyimide resin useful as, for example, an insulating member of a circuit board.

  Polymeric materials are used in various products around us because of their properties such as easy processing and light weight. A polyimide resin developed by DuPont in the United States in 1955 has been developed because of its excellent heat resistance. Since then, many researchers have conducted detailed studies, and it has become clear that the performances such as heat resistance, dimensional stability, and insulation properties show the top class performance among organic substances, and, for example, application to insulating materials of electronic parts Is in progress.

  Patent Document 1 discloses a laminate having a metal foil and a polyimide resin layer. In addition, the polyimide resin layer contains a polyimide resin using pyromellitic anhydride as the acid dianhydride and 4,4'-diamino-2,2'-dimethylbiphenyl and bisaminophenoxybenzene as the diamine. It is disclosed. Furthermore, it is described that a laminated body is suitably used for manufacture of a flexible printed wiring board and a suspension for HDD.

  Patent Document 2 discloses a polyimide metal foil composite film comprising a conductive metal foil and a polyimide resin layer directly laminated on the surface of the conductive metal foil. Further, the polyimide resin layer contains a polyimide resin using pyromellitic anhydride as the acid dianhydride and m-tolidine and 2,2-bis [4- (4-aminophenoxy) phenyl] propane as the diamine. Is disclosed. Furthermore, it is described that a polyimide metal foil composite film is a material of a circuit board.

  Patent Document 3 discloses a laminate having a polyimide resin layer formed by coating on a conductor. It is also disclosed that the polyimide resin layer contains a polyimide resin using 4,4'-diamino-2,2'-dimethylbiphenyl as a diamine. Furthermore, it is described that a laminated body is used for a flexible printed wiring board, a suspension for HDD, etc.

Patent No. 4544588 Patent No. 3523952 Patent No. 3759454

  A polyimide resin using pyromellitic anhydride (PMDA) as the acid dianhydride and 4,4'-diamino-2,2'-dimethylbiphenyl (TBHG) as the diamine has a linear humidity expansion coefficient (Coefficient of liner Humidity) It has properties such as low expansion (CHE) and high etching rate (Et rate) to an alkaline etchant.

  In polyimide resins, low CHE and high Et-rate are often in a trade-off relationship. Generally, the reduction of CHE is required to have the property that water does not easily adsorb, but the improvement of Et-rate is required to have the property that water can easily adsorb. Polyimide resins using PMDA and TBHG are useful as materials compatible with low CHE and high Et-rate.

  On the other hand, polyimide resins using PMDA and TBHG have the property of low coefficient of linear thermal expansion (CTE). Therefore, for example, when the polyimide resin layer is disposed on the metal layer, the difference between the CTE of the metal layer and the CTE of the polyimide resin layer is large, and the laminate is easily warped.

  The present invention has been made in view of the above-described circumstances, and its main object is to provide a novel polyimide resin having an improved CTE while achieving both a low CHE and a high Et-rate.

  In order to solve the above problems, the present inventors have conducted intensive studies, and by adding a specific diamine at a specific ratio, CTE improves while achieving both low CHE and high Et-rate. To complete the present invention.

  That is, in the present invention, the structural units represented by the formula (1) and the formula (2) are contained, and the ratio of the structural unit represented by the above formula (1) is all the repetitions constituting the polymer skeleton. The ratio of the structural unit represented by the above formula (2) is within the range of 60 mol% or more and 84 mol% or less with respect to the unit, 16 mol% or more with respect to all the repeating units constituting the above-mentioned polymer skeleton Provided is a polyimide resin having a range of 35 mol% or less.

(In Formula (1), A ₁ is an acid dianhydride component, and 50 mol% or more of A ₁ is a component represented by Formula (i), and R ₁ and R ₂ each independently have 1 carbon atom The hydrocarbon group is 4 or less, and in the formula (2), A ₂ is an acid dianhydride component, and 50 mol% or more of A ₂ is a component represented by the formula (i))

  According to the present invention, since the structural units represented by the formulas (1) and (2) are contained at a predetermined ratio, a polyimide resin with improved CTE while achieving both low CHE and high Et-rate can do.

  In the said invention, it is preferable that the ratio of the component represented by the said Formula (i) is 80 mol% or more with respect to all the acid dianhydride components which comprise the said polymeric skeleton.

  In the above invention, the polyimide resin further contains the structural unit represented by the formula (3), and the proportion of the structural unit represented by the above formula (3) is all the repeating units constituting the above-mentioned polymer skeleton. Preferably, it is in the range of 1 mol% to 10 mol%.

(In Formula (3), A ₃ is an acid dianhydride component, and 50 mol% or more of A ₃ is a component represented by Formula (i))

  In the above invention, preferably, the polyimide resin is used as the polyimide resin of a laminate including a polyimide resin layer containing a polyimide resin and a metal layer disposed on at least one surface of the polyimide resin layer. .

  Further, in the present invention, it is a laminate comprising a polyimide resin layer containing a polyimide resin and a metal layer disposed on at least one surface of the polyimide resin layer, wherein the polyimide resin is the above-mentioned polyimide resin To provide a laminate characterized in that

  According to the present invention, by using the above-described polyimide resin, it is possible to obtain a laminate in which warpage due to heat and humidity is suppressed. Furthermore, since the polyimide resin mentioned above has a high etching rate with respect to an alkaline etching solution, it can be made into a laminated body in which processing of a polyimide resin layer is easy.

  In the said invention, it is preferable that the linear thermal expansion coefficient of the said polyimide resin layer exists in the range of 10 ppm / degrees C or more and 30 ppm / degrees C or less.

  In the said invention, it is preferable that the linear humidity expansion coefficient of the said polyimide resin layer is 15 ppm /% RH or less.

  In the above invention, the etching rate of the polyimide resin layer is preferably 11 μm / min or more.

  In the above invention, the metal layer is preferably stainless steel or copper.

  In the above-mentioned invention, it is preferable that the above-mentioned layered product equips the both sides of the above-mentioned polyimide resin layer with the above-mentioned metal layer, one above-mentioned metal layer is stainless steel, and the other above-mentioned metal layer is copper.

  In the above invention, it is preferable that the metal layer which is the copper is formed by at least one of a PVD method and a wet plating method.

  In the above-mentioned invention, it is preferable that the above-mentioned metal layer which is the above-mentioned copper is formed from the above-mentioned polyimide resin layer side by PVD method and electrolytic plating method.

  In the said invention, it is preferable that the said laminated body is a circuit board provided with the said metal layer of pattern shape.

  In the above invention, the circuit board is preferably a suspension board for HDD.

  The polyimide resin of the present invention has an effect that CTE can be improved while achieving both low CHE and high Et-rate.

It is a schematic sectional drawing which shows an example of the laminated body of this invention. It is a schematic sectional drawing which shows the other example of the laminated body of this invention. It is a schematic diagram explaining the suspension board for HDD in this invention.

  Hereinafter, the polyimide resin and the laminate of the present invention will be described in detail.

A. Polyimide Resin The polyimide resin of the present invention contains the structural units represented by the formula (1) and the formula (2), and the ratio of the structural units represented by the above formula (1) is all constituting the polymer skeleton The ratio of the structural unit represented by the above-mentioned formula (2) is within the range of 60 mol% or more and 84 mol% or less with respect to the repeating units of 16% with respect to all repeating units constituting the above-mentioned polymer skeleton. % Or more and 35 mol% or less.

  According to the present invention, since the structural units represented by the formulas (1) and (2) are contained at a predetermined ratio, a polyimide resin with improved CTE while achieving both low CHE and high Et-rate can do. As described above, a polyimide resin using pyromellitic anhydride (PMDA) as the acid dianhydride and 4,4'-diamino-2,2'-dimethylbiphenyl (TBHG) as the diamine has a low CHE, It has the property that the Et rate is high. However, this polyimide resin has a low CTE. Therefore, for example, when the polyimide resin layer is disposed on the metal layer, the difference between the CTE of the metal layer and the CTE of the polyimide resin layer becomes large, and the laminate is warped. Is easy to occur. On the other hand, in the present invention, by combining TBHG and 3,4'-diaminodiphenyl ether (3,4'-DPE) as a diamine in a predetermined ratio, compatibility between low CHE and high Et-rate is achieved. It is possible to improve CTE while planning.

  The polyimide resin of the present invention has a structural unit represented by the formula (1).

In Formula (1), A ₁ is an acid dianhydride component, and 50 mol% or more of A ₁ is a component represented by Formula (i). That is, the main component of A ₁ is the PMDA component. The ratio of the PMDA component in A ₁ may be 70 mol% or more, or 90 mol% or more. The acid dianhydride component other than the PMDA component is not particularly limited as long as it is a component using a known tetracarboxylic acid dianhydride.

  Examples of known tetracarboxylic acid dianhydrides include 3,3 ′, 4,4′-diphenylsulfone tetracarboxylic acid dianhydride, 3,3 ′, 4,4′-benzophenonetetracarboxylic acid dianhydride, 3,3 ', 4,4'-diphenylethertetracarboxylic dianhydride, 3,3', 4,4'-biphenyltetracarboxylic dianhydride, 4,4'-biphthalic anhydride, 4,4 ' -Oxydiphthalic anhydride etc. can be mentioned.

Further, R ₁ and R ₂ in the formula (1) are each independently a hydrocarbon group having 1 or more and 4 or less carbon atoms. The hydrocarbon group may be a saturated hydrocarbon group or an unsaturated hydrocarbon group. As R ₁ and R ₂ , for example, methyl group, ethyl group, n-propyl group, i-propyl group, n-butyl group, sec-butyl group, i-butyl group, t-butyl group etc. may be mentioned it can.

  In addition, the ratio of the structural unit represented by the formula (1) is usually in the range of 60 mol% or more and 84 mol% or less and 65 mol% or more and 80 mol% or less based on all repeating units constituting the polymer skeleton. It may be in the range of If the proportion of structural units represented by the formula (1) is too large, the CTE may not be sufficiently improved, and if the proportion of structural units represented by the formula (1) is too small, low CHE and high Et It may be difficult to balance rates.

  The polyimide resin of the present invention has a structural unit represented by Formula (2).

In Formula (2), A ₂ is an acid dianhydride component, and 50 mol% or more of A ₂ is a component represented by Formula (i). That is, the main component of the _{A 2} are PMDA component. Ratio of PMDA components in A ₂ may be more than 70 mol%, may be more than 90 mol%. The acid dianhydride component other than the PMDA component is not particularly limited as long as it is a component using a known tetracarboxylic acid dianhydride.

  Further, the proportion of the structural unit represented by the formula (2) is usually in the range of 16 mol% to 35 mol%, and 20 mol% to 35 mol%, with respect to all the repeating units constituting the polymer skeleton. It may be in the range of If the proportion of structural units represented by the formula (2) is too large, it may be difficult to achieve both low CHE and high Et-rate, and the proportion of structural units represented by the formula (2) is If the amount is too small, the CTE may not be sufficiently improved.

  The polyimide resin of this invention contains the structural unit represented by Formula (1) and Formula (2) by a predetermined | prescribed ratio. On the other hand, the polyimide resin of the present invention may contain one or two or more other structural units in addition to the structural units represented by Formula (1) and Formula (2). The acid dianhydride component and the diamine component in other structural units may be any known components and are not particularly limited. That is, known tetracarboxylic acid dianhydrides and diamines can be optionally used.

  The known tetracarboxylic acid dianhydride is as described above. Also, as known diamines, for example, p-phenylenediamine, m-phenylenediamine, 2,4-diaminotoluene, 4,4'-diaminodiphenylether, 3,4'-diaminodiphenylmethane, 4,4'-diaminodiphenylmethane 4,4'-diaminodiphenyl sulfone, 3,3'-diaminodiphenyl sulfone, 3,3'-diaminobenzophenone, 4,4'-diaminobenzophenone, 4,4'-bis (4-aminophenoxy) biphenyl, 1 , 3-bis [2- (4-aminophenyl) -2-propyl] benzene, 1,4-bis [2- (4-aminophenyl) -2-propyl] benzene, 2,2-bis [(4- Aminophenoxy) methyl] propane, 2,2-bis [(4-aminophenoxy) methyl] propane, 1,3-biphenyl (3-aminophenoxy) benzene, 1,3-bis (4-aminophenoxy) benzene, 1,4-bis (4-aminophenoxy) benzene, 4,4′-bis (4-aminophenoxy) diphenyl sulfone, 1 And 3-bis (4-aminobenzoyloxy) propane etc. can be mentioned.

  The polyimide resin of this invention may have a structural unit represented by Formula (3) as needed. For example, a polyimide resin having high adhesion to a metal layer can be used.

In the formula (3), _{A 3} is an acid dianhydride component, or 50 mol% of _{A 3} is a component represented by the formula (i). That is, the main component of the _{A 3} is PMDA component. Ratio of PMDA components in A ₃ may be more than 70 mol%, may be more than 90 mol%. The acid dianhydride component other than the PMDA component is not particularly limited as long as it is a component using a known tetracarboxylic acid dianhydride.

  Moreover, the ratio of the structural unit represented by Formula (3) is although it does not specifically limit, For example, it is in the range of 1 mol% or more and 10 mol% or less with respect to all the repeating units which comprise polymer backbone. If the proportion of structural units represented by the formula (3) is too large, it may be difficult to achieve both low CHE and high Et-rate, and the proportion of structural units represented by the formula (3) is If the amount is too small, adhesion may not be sufficiently improved.

  The polyimide resin of the present invention usually contains, as an acid dianhydride component, a component represented by Formula (i), that is, a PMDA component as a main component. The PMDA component is preferably 50% or more, and more preferably 80 mol% or more, with respect to all the acid dianhydride components constituting the polymer skeleton. In addition, all acid dianhydride components in the polyimide resin may be PMDA components. The raw material PMDA has the following structure. Moreover, well-known tetracarboxylic dianhydride can be used as acid dianhydride other than PMDA.

  In addition, the diamine which comprises the structural unit represented by Formula (1)-(3) has the following structures, respectively.

  The weight average molecular weight of the polyimide resin of the present invention is, for example, preferably in the range of 3,000 or more and 1,000,000 or less, and more preferably in the range of 15,000 or more and 150,000 or less. When the weight average molecular weight is too low, for example, when a polyimide resin is used as a film, sufficient strength may not be obtained. If the weight average molecular weight is too high, the viscosity of the polyimide precursor composition will increase and the solubility of the polyimide precursor will also decrease, so for example, when a polyimide resin is used as a film, it may not be possible to form a smooth surface. is there. The weight average molecular weight refers to a value in terms of polystyrene by gel permeation chromatography (GPC).

  The polyimide resin of the present invention may be a random polymer, a block polymer or an alternating polymer. The polyimide resin of the present invention may further contain an additive. Examples of the additive include photosensitizers, fillers, antioxidants, adhesion imparting agents, surfactants and the like.

  Examples of the photosensitizer include naphthoquinone diazide sulfonic acid ester compounds, Michler's ketone, diethylaminobenzophenone, benzoin monomethyl ether, thioxanthone and the like. Examples of the filler include graphite, Teflon (registered trademark), alumina, organic fibers, glass fibers, carbon fibers and the like. Examples of the antioxidant include phosphites, phosphonites, hindered phenols, styrenated phenols and the like.

  As the adhesion promoter, for example, vinyltriethoxysilane, γ-glycidoxypropyltriethoxysilane, γ-methacryloxypropyltrimethoxysilane, ureapropyltriethoxysilane, methylphenylsilanediol, ethylphenylsilanediol, n -Propylphenylsilanediol, isopropylphenylsilanediol, n-butylphenylsilanediol, isobutylphenylsilanediol, tert-butylphenylsilanediol and the like can be mentioned. As surfactant, polyoxyethylene uralyl ether, polyoxyethylene stearyl ether, polyoxyethylene oleyl ether, polyoxyethylene octyl phenol ether etc. can be mentioned, for example.

  The shape of the polyimide resin of the present invention is not particularly limited, and examples thereof include layers and particles. The layered polyimide resin preferably has CTE, CHE, and an etching rate within a predetermined range described in “B. Laminate”.

  Examples of uses of the polyimide resin of the present invention include uses as an insulating member. Moreover, as an article which can apply the polyimide resin of this invention, a circuit board, a color filter, an anti-reflective film, a hologram, a construction material, a coating material, printing ink etc. can be mentioned, for example. In particular, the polyimide resin of the present invention is preferably used as a polyimide resin of a laminate to be described later. This is because the difference between the CTE of the metal layer and the CTE of the polyimide resin layer is reduced, and the occurrence of warpage in the laminate can be suppressed.

  In the present invention, the precursor composition of the polyimide resin described above can also be provided. Specifically, the structural units represented by the formulas (4) and (5) are contained, and the ratio of the structural units represented by the above-mentioned formula (4) is to all repeating units constituting the polymer skeleton. To the contrary, the proportion of the structural unit represented by the above formula (5) is within the range of 60 mol% or more and 84 mol% or less and is 16 mol% or more and 35 mol% with respect to all the repeating units constituting the polymer skeleton The polyimide precursor composition characterized by including the polyimide precursor which is in the following range can be provided. The polyimide precursor corresponds to a so-called polyamic acid.

In formula (4), B ₁ is an acid dianhydride component, and 50 mol% or more of B ₁ is a component represented by formula (ii), and R ₁ and R ₂ each independently have 1 or more carbon atoms 4 or less hydrocarbon group. In the formula (5), _{B 2} is an acid dianhydride component, 50 mol% or more of _{B 2} is a component represented by formula (ii). That is, the main components of B ₁ and B ₂ are PMDA components. The proportion of the PMDA component in B ₁ and B ₂ may be independently 70 mol% or more, or 90 mol% or more. The acid dianhydride component other than the PMDA component is not particularly limited as long as it is a component using a known tetracarboxylic acid dianhydride. Further, _{R 1} and _{R 2} in the formula (4) is the same as _{R 1} and _{R 2} in Formula (1) described above.

  The polyimide precursor contains the structural units represented by Formula (4) and Formula (5) in a predetermined ratio. On the other hand, the polyimide precursor may further contain other structural units in addition to the structural units represented by Formula (4) and Formula (5). The acid dianhydride component and the diamine component in other structural units may be any known components and are not particularly limited. That is, known tetracarboxylic acid dianhydrides and diamines can be optionally used. The other structural unit may be of one type or of two or more types.

  Moreover, the polyimide precursor may have a structural unit represented by Formula (6) as needed. Furthermore, it is preferable that the ratio of the structural unit represented by Formula (6) exists in the range of 1 mol% or more and 10 mol% or less with respect to all the repeating units which comprise polymer backbone.

In the formula (6), _{B 3} is an acid dianhydride component, 50 mol% or more of _{B 3} is a component represented by formula (ii). That is, the main component of _{B 3} is PMDA component. Ratio of PMDA components in B ₃ may be more than 70 mol%, may be more than 90 mol%. The acid dianhydride component other than the PMDA component is not particularly limited as long as it is a component using a known tetracarboxylic acid dianhydride.

  The polyimide precursor composition preferably contains an organic solvent in addition to the polyimide precursor. Examples of the organic solvent include polar solvents such as N-methylpyrrolidone, N, N-dimethylacetamide, and N, N-dimethylformamide. In addition, the organic solvent is removed by drying the polyimide precursor composition, and the polyimide precursor is cured (imidized) to obtain a polyimide resin. The drying temperature is, for example, 50 ° C. or more. The heat treatment temperature for curing is, for example, 200 ° C. or more.

B. Laminate FIG. 1 is a schematic cross-sectional view showing an example of the laminate of the present invention. A laminate 10 shown in FIG. 1 includes a metal layer 1 and a polyimide resin layer 2 disposed on the metal layer 1. In FIG. 1, the metal layer 1 is disposed on one surface of the polyimide resin layer 2, but the metal layer 1 may be disposed on both sides of the polyimide resin layer 2. Specifically, as shown in FIG. 2, the laminate 10 is formed on the first metal layer 1 a, the polyimide resin layer 2 disposed on the first metal layer 1 a, and the polyimide resin layer 2. You may provide with the 2 metal layer 1b. The present invention is characterized in that the polyimide resin layer 2 contains the above-mentioned polyimide resin.

According to the present invention, by using the above-described polyimide resin, it is possible to obtain a laminate in which warpage due to heat and humidity is suppressed. Furthermore, since the polyimide resin mentioned above has a high etching rate with respect to an alkaline etching solution, it can be made into a laminated body in which processing of a polyimide resin layer is easy.
Hereinafter, the layered product of the present invention is explained for every composition.

1. Polyimide resin layer The polyimide resin layer in the present invention is a layer containing the polyimide resin described in the above "A. polyimide resin". The content of the polyimide resin in the polyimide resin layer is, for example, 80% by weight or more, and preferably 90% by weight or more.

  The linear thermal expansion coefficient (CTE) of the polyimide resin layer is, for example, 10 ppm / ° C. or more, and may be 11 ppm / ° C. or more. On the other hand, the CTE of the polyimide resin layer is, for example, 30 ppm / ° C. or less, may be 25 ppm / ° C. or less, or 22 ppm / ° C. or less.

  CTE can be measured by the following method. First, the polyimide resin layer is separated from the laminate. Examples of the separation method include a method of removing the metal layer from the laminate by etching, a method of physically peeling the metal layer and the polyimide resin, and the like. Next, the obtained polyimide resin layer is cut into a width of 5 mm and a length of 18 mm to obtain an evaluation sample. The CTE of the evaluation sample is measured using a thermomechanical analyzer (for example, TMA 60 (manufactured by Shimadzu Corporation)). Measurement conditions are a temperature rising rate of 10 ° C./min, a tensile weight of 9 g, and an average value in a range of 100 ° C. to 150 ° C. as CTE.

  The difference between the CTE of the polyimide resin layer and the CTE of the metal layer is, for example, preferably 8 ppm / ° C. or less, more preferably 5 ppm / ° C. or less.

  The linear humidity expansion coefficient (CHE) of the polyimide resin layer is, for example, preferably 15 ppm /% RH or less, more preferably 9.9 ppm /% RH or less, and 9.0 ppm /% RH or less Is more preferred. The lower limit of CHE of the polyimide resin layer is 0 ppm /% RH.

  CHE can be measured by the following method. First, the polyimide resin layer is separated from the laminate. Examples of the separation method include a method of removing the metal layer from the laminate by etching, a method of physically peeling the metal layer and the polyimide resin, and the like. Next, the obtained polyimide resin layer is cut into a width of 5 mm and a length of 20 mm to obtain an evaluation sample. The CHE is measured on the evaluation sample using a variable humidity mechanical analyzer (for example, Thermo Plus TMA 8310 (manufactured by RIGAKU Co., Ltd.)). Measurement conditions are such that the temperature is kept constant at 25 ° C. and the humidity is maintained at 15% RH for 30 minutes or more until the sample becomes stable. The humidity is then 20% RH and the sample is held for at least 30 minutes until the sample is stable. Thereafter, the humidity is set to 50% RH to stabilize the sample. The difference between the sample length stabilized at 50% RH and the sample length stabilized at 20% RH divided by the change in humidity (in this case 50-20 30) divided by the sample length And CHE. In the measurement, the tensile weight is 5 g.

  The etching rate of the polyimide resin layer is, for example, preferably 11 μm / min or more, and more preferably 14 μm / min or more. On the other hand, the etching rate of the polyimide resin layer is, for example, 90 μm / min or less, preferably 60 μm / min or less, and more preferably 30 μm / min or less. The etching rate is a condition in which potassium hydroxide, monoethanolamine and water are mixed at a weight ratio of potassium hydroxide: monoethanolamine: water = 1: 1: 1 as an etching solution, and the condition of the solution temperature is 75 ° C. It is a value at the time of measuring by.

  The polyimide resin layer may have a single layer structure or a multilayer structure. In the former case, the polyimide resin layer is preferably disposed directly on the metal layer. In the latter case, at least one layer of the plurality of layers constituting the polyimide resin layer may contain the polyimide resin described above. As an example of the latter, mention is made of a polyimide resin layer having a core layer containing the above-mentioned polyimide resin and an adhesive layer disposed on at least one surface of the core layer and having higher adhesion to the metal layer than the core layer. Can. The adhesive layer may be disposed on only one surface of the core layer, or may be disposed on both sides of the core layer. The polyimide resin contained in the adhesive layer is appropriately selected so as to obtain an adhesive layer having higher adhesion to the metal layer than the core layer.

  Although the thickness of a polyimide resin layer changes with uses of a laminated body, it exists in the range of 5 micrometers-30 micrometers, for example, and it is preferable to exist in the range of 5 micrometers-15 micrometers.

2. Metal Layer The metal layer in the present invention is a layer disposed on at least one surface of the polyimide resin layer. The material of the metal layer is preferably a material having conductivity, and examples thereof include stainless steel, copper, nickel, aluminum, and any alloy thereof. For example, “the metal layer is copper” means that the material of the metal layer is copper or an alloy containing copper as a main component. The same applies to other materials.

  The metal layer may be a metal layer obtained by a plating method, or may be a metal layer obtained by rolling a metal. The plating method may be a dry plating method or a wet plating method. As a dry plating method, PVD methods, such as sputtering, can be mentioned, for example. On the other hand, as a wet plating method, an electrolytic plating method and an electroless plating method are usually mentioned. In the present invention, the metal layer which is copper is preferably formed by at least one of PVD and wet plating. In particular, it is preferable that the metal layer which is copper is formed by the PVD method and the electrolytic plating method from the polyimide resin layer side. In this case, a seed layer is formed on the surface of the polyimide resin layer by a PVD method such as sputtering, and then copper is deposited from the seed layer by electrolytic plating. As a material of a seed layer, copper, chromium, nickel etc. can be mentioned, for example.

  The metal layer in the present invention is a layer disposed on at least one surface of the polyimide resin layer. The metal layer may be formed only on one surface of the polyimide resin layer, or may be formed on both sides of the polyimide resin layer. In the latter case, the metal layers formed on both sides of the polyimide resin layer may be the same material or different materials. In particular, in the present invention, it is preferable that one metal layer (first metal layer) is stainless steel and the other metal layer (second metal layer) is copper. This is because a laminate useful as a circuit board can be obtained.

  The linear thermal expansion coefficient (CTE) of the metal layer varies depending on the material of the metal layer, but is preferably in the range of 10 ppm / ° C. to 30 ppm / ° C., for example, and in the range of 14 ppm / ° C. to 20 ppm / ° C. It is more preferable that

  The thickness of the metal layer varies depending on the application of the laminate, but is, for example, in the range of 1 μm to 40 μm, and preferably in the range of 5 μm to 30 μm.

3. Laminate Application Although the application of the laminate of the present invention is not particularly limited, for example, a circuit board can be mentioned. The circuit board usually has a patterned metal layer, and the metal layer is used as a wire. Examples of the circuit board include a suspension board for a hard disk drive (HDD) and a flexible printed wiring board.

  FIG. 3A is a schematic plan view showing an example of a suspension board for an HDD, and FIG. 3B is a cross-sectional view taken along the line A-A of FIG. In FIG. 3A, the insulating layer and the cover layer are omitted for convenience, and in FIG. 3B, the cover layer is omitted for convenience. The HDD suspension substrate 100 shown in FIG. 3A is provided at one end portion, is provided at the head side area 101 for mounting a magnetic head etc., and is provided at the other end portion, and is connected to an external circuit board etc. And a plurality of wiring layers 103a to 103d for electrically connecting the head side area 101 and the tail side area 102. The wiring layer 103a and the wiring layer 103b are a pair of wiring layers, and similarly, the wiring layer 103c and the wiring layer 103d are also a pair of wiring layers. Generally, one of the two wiring layers is a write wiring layer, and the other is a read wiring layer.

  Further, as shown in FIG. 3B, the HDD suspension substrate 100 includes a first metal layer 1a, a polyimide resin layer 2 which is an insulating layer disposed on the first metal layer 1a, and a polyimide resin layer 2 And a second metal layer 1b which is a wiring layer disposed on the upper side. Although not shown, an insulating cover layer may be disposed to cover the second metal layer 1b. In particular, the first metal layer 1a is preferably stainless steel, and the second metal layer 1b is preferably copper.

  The method for producing the laminate of the present invention is not particularly limited as long as it is a method by which the desired laminate can be obtained. As an example of a manufacturing method, the polyimide precursor composition mentioned above is coated on a metal layer (1st metal layer), the coating film formation process of forming a coating film, and heating the said coating film And a polyimide resin layer forming step of forming a polyimide resin layer containing a polyimide resin. In the coating film forming step, it is preferable to apply the polyimide precursor composition directly. Moreover, it is preferable that a 1st metal layer is stainless steel. Furthermore, after the polyimide resin layer forming step, a second metal layer forming step of forming a second metal layer may be included by at least one of PVD method and wet plating method. The second metal layer is preferably copper.

  The present invention is not limited to the above embodiment. The above-described embodiment is an exemplification, and the technical idea described in the claims of the present invention has substantially the same configuration as that of the technical idea described in the claims of the present invention and exhibits the same operation and effect as the present invention in any case. It is included in the technical scope of the invention.

  Hereinafter, the present invention will be described more specifically.

Example 1
In a separable flask equipped with a stir bar, 0.35 mol of 3,4'-diaminodiphenyl ether (3,4'-DPE) and 4,4'-diamino-2,2'-dimethylbiphenyl (TBHG) 0.91 mol and 0.14 mol of 2,2-bis [4- (4-aminophenoxy) phenyl] propane (BAPP) were dissolved in N-methylpyrrolidone (NMP). Thereafter, 1.49 mol of pyromellitic anhydride (PMDA) was added stepwise while stirring, and the polymerization reaction was allowed to proceed to obtain a polyimide precursor solution.

  The resulting polyimide precursor solution is applied to a 18 μm thick stainless steel so that the thickness after curing becomes 10 μm, and 80 ° C., 120 ° C., 135 ° C., 150 ° C., 165 ° C. Heat treatment (drying) was performed at 180 ° C. for 2 minutes each. Thereafter, heat treatment (curing) was performed for 2 minutes each at 250 ° C., 300 ° C., and 380 ° C. in a nitrogen atmosphere to obtain a laminate having a polyimide resin layer and a stainless steel layer. The composition of the polyimide resin corresponds to x = 65, y = 25 and z = 10 in the following formula.

[Examples 2 and 3 and Comparative Examples 1 to 3]
A laminate was obtained in the same manner as Example 1, except that the proportions of TBHG, TBHG and BAPP were changed so as to obtain the compositions described in Table 1 below.

[Evaluation]
The stainless steel layer was etched from the laminates obtained in Examples 1 to 3 and Comparative Examples 1 to 3 to obtain a film-like polyimide resin layer. The linear thermal expansion coefficient (CTE) and linear humidity expansion coefficient (CHE) of the obtained polyimide resin layer were measured. The measuring method is as described above. Moreover, the etching rate of the polyimide resin layer was measured using the laminated body obtained in Examples 1-3 and Comparative Examples 1-3. The measuring method is as described above. The results are shown in Table 1.

  As shown in Table 1, in Comparative Example 2, since the ratio of TBHG is high, both low CHE and high Et rate can be achieved, but the CTE is low. On the other hand, in Examples 1 to 3, when the TBHG and the 3, 4'-DPE were within the predetermined range, the CTE was improved while achieving both the low CHE and the high Et-rate. In addition, in the comparative example 1, when 3, 4'-DPE was used, all of CHE, an Et rate, and CTE became high. Further, in Comparative Example 3, the proportion of TBHG was low and the proportion of BAPP was high, so although the CTE was high, the CHE increased and the Et rate decreased. From these results, when TBHG is in the range of 60 mol% or more and 84 mol% or less, and 3,4′-DPE is in the range of 16 mol% or more and 35 mol% or less, both CHE and high Et , CTE was confirmed to improve.

DESCRIPTION OF SYMBOLS 1 ... Metal layer 1a ... 1st metal layer 1b ... 2nd metal layer 2 ... Polyimide resin layer 10 ... Laminated body 100 ... Suspension board for HDD 101 ... Head side area 102 ... Tail side area 103 ... Wiring layer

Claims (13)

Containing structural units represented by the formula (1) and the formula (2),
The proportion of the structural unit represented by the formula (1) is, with respect to all repeating units constituting the polymer backbone, in the range of less 60 mol% or more 8 0 mol%,
The proportion of the structural unit represented by the formula (2) comprises for all the repeating units constituting the polymer backbone, in the range in der Lupo polyimide resin above 16 mol% 35 mol or less,

(In Formula (1), A ₁ is an acid dianhydride component, and 50 mol% or more of A ₁ is a component represented by Formula (i), and R ₁ and R ₂ each independently have 1 carbon atom The hydrocarbon group is 4 or less, and in the formula (2), A ₂ is an acid dianhydride component, and 50 mol% or more of A ₂ is a component represented by the formula (i))
The said polyimide resin further contains the structural unit represented by Formula (3),
The ratio of the structural unit represented by said Formula (3) is in the range of 1 mol% or more and 10 mol% or less with respect to all the repeating units which comprise the said polymer skeleton.

(In Formula (3), A ₃ is an acid dianhydride component, and 50 mol% or more of A ₃ is a component represented by Formula (i))   The ratio of the component represented by said Formula (i) is 80 mol% or more with respect to all the acid dianhydride components which comprise the said polymer skeleton, The polyimide resin of Claim 1 characterized by the above-mentioned. . And the polyimide resin layer containing a polyimide resin, to claim 1 or claim 2, characterized in that used as the polyimide resin of the laminate and a metal layer disposed on at least one surface of the polyimide resin layer Polyimide resin as described. A laminate comprising: a polyimide resin layer containing a polyimide resin; and a metal layer disposed on at least one surface of the polyimide resin layer,
The laminated body characterized by the said polyimide resin being a polyimide resin as described in any one of Claim 1- Claim 3 . The linear thermal expansion coefficient of the said polyimide resin layer is in the range of 10 ppm / degrees C. or more and 30 ppm / degrees C. or less, The laminated body of Claim 4 characterized by the above-mentioned. The linear humidity expansion coefficient of the said polyimide resin layer is 15 ppm /% RH or less, The laminated body of Claim 4 or Claim 5 characterized by the above-mentioned. The etching rate of the said polyimide resin layer is 11 micrometers / min or more, The laminated body as described in any one of Claim 4 to 6 characterized by the above-mentioned. The laminate according to any one of claims 4 to 7 , wherein the metal layer is stainless steel or copper. The metal layer is provided on both sides of the polyimide resin layer,
The laminate according to any one of claims 4 to 8 , wherein one of the metal layers is stainless steel and the other of the metal layers is copper. The laminate according to claim 8 or 9 , wherein the metal layer which is the copper is formed by at least one of a PVD method and a wet plating method. The said metal layer which is the said copper is formed by the PVD method and the electroplating method from the said polyimide resin layer side, The laminated body of Claim 8 or Claim 9 characterized by the above-mentioned. The laminate according to any one of claims 4 to 11 , wherein the laminate is a circuit board including the patterned metal layer. The laminate according to claim 12 , wherein the circuit board is a suspension board for an HDD.

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