JP4652020B2 - Copper-clad laminate - Google Patents

Description

  The present invention relates to a copper-clad laminate in which an insulating layer made of a polyimide resin is provided on a copper foil.

  In recent years, flexible printed circuit boards have been used as substrate materials for electrical wiring, as mobile phones, digital cameras, digital video, PDAs, car navigators, and other various electronic devices that are becoming more sophisticated have become smaller and lighter. Accordingly, there are increasing demands for miniaturization and high density, multilayering, finer, low dielectric, and high heat resistance of wiring members.

  Copper-clad laminates used for such flexible printed circuit boards have so far been made by bonding an insulator made of a film such as polyimide or polyester and a copper foil (conductor) via an adhesive such as epoxy resin or acrylic resin. Manufactured. However, the copper-clad laminate produced by the method as described above has a problem that heat resistance and flame retardancy are lowered due to the presence of the adhesive layer. Moreover, the dimensional change is large when the conductor is etched or when any heat treatment is performed, and such a copper-clad laminate has a problem in that it hinders subsequent processes.

  In order to solve these problems, the polyimide resin layer is applied directly on the conductor, and the insulator is formed by multilayering with a plurality of polyimide resin layers having different thermal expansion coefficients. Japanese Patent Publication No. 6-93537 (Patent Document 1) and the like disclose a method for providing a flexible printed circuit board having excellent reliability with respect to stability, adhesive strength, flatness after etching, and the like.

  By the way, a copper-clad laminate used for a flexible printed circuit board is required to have flexibility, flexibility, high-density mounting, and the like. Narrow pitch and high density mounting are desired. In order to increase the density of the flexible printed circuit board, it is necessary to reduce the width and interval of the circuit wiring, that is, to make the pitch fine. Therefore, in a copper-clad laminate without an adhesive layer, for example, as disclosed in Japanese Patent Application Laid-Open No. 2001-214298 (Patent Document 2), the roughness is high or rough in order to increase the adhesive force with the resin layer. Copper foil that has been processed is used. However, when a laminated board is formed using copper foil with high roughness for applications that require fine pitch, the copper foil remains on the resin when etching is used to form a circuit, or the etching linearity decreases. As a result, problems such as non-uniform circuit widths occur.

  For this reason, it is necessary to use a copper foil with a small surface roughness in order to narrow the wiring pitch and increase the density, but the copper foil with a small surface roughness has an anchor effect, that is, a resin copper foil. Since the bite into the surface irregularities is small, the mechanical adhesive strength cannot be obtained, and the adhesive strength to the resin becomes low. Therefore, the surface of the metal foil that has not been subjected to roughening treatment is insulated from the metal foil by subjecting the surface to any one of rust prevention treatment, chromate treatment, and silane coupling treatment, or a combination thereof. There has been proposed a metal-clad laminate in which adhesion and flatness at the interface with a layer are compatible (see Patent Document 3). However, this laminate uses a prepreg in which an insulating layer is coated on a base material with a varnish made of a specific resin composition.

  On the other hand, for copper-clad laminates, approaches from the copper foil side, such as low roughness of the copper foil surface, low roughness of the surface after half-etching, and examination of surface metal species, have been mainly performed so far. However, in order to meet the recent demands for high-density mounting, it is also necessary to examine issues such as dimensional stability on the resin side, sinking during mounting, and adhesiveness of ACF (anisotropic conductive film) In view of these, it is necessary to satisfy the adhesiveness between the insulating layer made of resin and the copper foil.

Japanese Patent Publication No. 6-93537 JP 2001-214298 A JP 2004-25835 A

  As described above, in a copper-clad laminate in which an insulating layer is formed directly on a copper foil without using an adhesive, which is said to be excellent in heat resistance, flame retardancy and dimensional stability, No one has yet been found that can simultaneously satisfy the reliability of the mechanical adhesive strength between the copper foil and the insulating layer. The present invention provides a copper-clad laminate having excellent heat resistance, flame retardancy, dimensional stability, etc., capable of high-density mounting, and having excellent adhesion and adhesive strength retention. Objective.

  In order to achieve the above object, the present inventors have studied, and by depositing a predetermined metal on the surface of the copper foil in contact with the insulating layer and performing a treatment with a coupling agent, adhesion and fine pitch are achieved. The present inventors have found that a copper-clad laminate that can satisfy the above requirements can be obtained at the same time, and have completed the present invention.

That is, the present invention is a copper-clad laminate provided with an insulating layer made of a polyimide-based resin formed by heat treatment by applying a polyimide precursor solution on a copper foil, and has a coefficient of linear thermal expansion (CTE) of 30 × A surface of a copper foil having a surface roughness Rz of 0.3 to 1.0 μm is in contact with an insulating layer made of a non-thermoplastic low thermal expansion polyimide resin of 10 ⁻⁶ / ° C. or less , and at least nickel, zinc, and cobalt are contained. A metal precipitation treatment to be precipitated and a treatment with a coupling agent are performed, and the surface of the copper foil subjected to the metal precipitation treatment is nickel 5 to 15 μg / cm ² , zinc 1 to 5 μg / cm ² , and cobalt 0. It is a copper-clad laminate having a nickel / (nickel + zinc) ratio of 0.70 or more, having 1-5 μg / cm ² and representing the content ratio of nickel and zinc.

  In this invention, what was obtained by well-known manufacturing methods, such as rolled copper foil and electrolytic copper foil, can be used for copper foil, for example. The thickness of the copper foil may be in the range of 8 to 35 μm, and preferably in the range of 12 to 18 μm. If the thickness of the copper foil is less than 8 μm, it may be difficult to adjust the tension in the line manufacturing process as in the case of mass production of copper-clad laminates. The flexibility of the laminate is poor. In the present invention, the treatment for roughening the surface of the copper foil is not particularly required, and the roughness of the surface of the copper foil is preferably Rz = 0.3 to 1.5 μm. By using a copper foil whose surface roughness is within the above range, a copper-clad laminate capable of forming a fine circuit pattern can be obtained. In particular, considering the fine pattern properties during circuit processing, the Rz value is preferably 0.3 to 1.0. Rz represents the ten-point average roughness (JIS B 0601-1994) in the surface roughness.

In the present invention, the surface of the copper foil in contact with the insulating layer is subjected to a metal deposition treatment for depositing at least nickel and zinc, and nickel of 5 to 15 μg / cm ² and zinc of 1 to 5 μg / cm ² are applied to the surface of the copper foil. And nickel / (nickel + zinc) representing the content ratio of nickel and zinc needs to be 0.70 or more. When the amount of nickel and zinc deposited on the surface of the copper foil after the metal deposition treatment is less than the above values, the initial adhesive strength between the copper foil and the resin layer when the copper-clad laminate is formed is sufficiently obtained. In addition, there is a possibility that a sufficient value of the adhesive strength retention rate when the heat resistance test is performed may not be obtained. On the contrary, if the amount of nickel and zinc deposited exceeds the above values, problems such as etching residue may occur when a copper-clad laminate is formed and fine circuit processing is performed. On the other hand, if the value of nickel / (nickel + zinc) is less than 0.70, problems such as a decrease in initial adhesive strength and a decrease in retention after a heat test may occur.

Further, the metal precipitation treatment in the present invention is preferably a metal precipitation treatment in which cobalt is precipitated together with the nickel and zinc described above. At this time, the amount of cobalt deposited on the surface of the copper foil is preferably 0.1 to 5 μg / cm ² . By precipitating cobalt in the above range together with nickel and zinc, the initial adhesive strength can be improved, and a decrease in the adhesive strength after the heat resistance test can be suppressed.
In the present invention, the total content of nickel, zinc and cobalt deposited on the surface of the copper foil is preferably 70% or more with respect to the total amount of all metals excluding copper present on the surface of the copper foil. . More specifically, Ni (nickel) 70 to 85% by weight, Zn (zinc) 10 to 20% by weight, Co (cobalt) when represented by the metal composition ratio present on the surface of the copper foil after the metal deposition treatment. It may have 0 to 30% by weight, and other metals may include, for example, Mo (molybdenum) 0 to 5% by weight, Cr (chromium) 0 to 5% by weight, and the like.

  The metal deposition treatment in the present invention is not particularly limited as long as it is a means capable of depositing the above-described metal in a predetermined amount on the surface of the copper foil, and examples thereof include a rust prevention treatment using the above metal. Specifically, a method of performing a plating treatment using a bath containing a predetermined amount of the above metal and depositing the above metal on the surface of the copper foil can be exemplified.

  Moreover, in this invention, the surface of the copper foil which carried out the metal precipitation process needs to be processed with the coupling agent. By treating with a coupling agent, it is possible to obtain an excellent initial adhesive strength between the copper foil and the insulating layer when a copper-clad laminate is formed, and the adhesive strength when a heat resistance test is performed. An excellent retention rate can be obtained.

  For the above coupling agent, it is preferable that the surface of the copper foil can be organically treated, such as aluminum alcoholate, aluminum chelate, silane coupling agent, triazine thiols, benzotriazoles, acetylene alcohols, acetylacetones, catechols. O-benzoquinones, tannins, quinolinols, azoles and the like. In particular, from the viewpoint of exhibiting excellent adhesion between the copper foil and the insulating layer, specifically, γ-aminopropyltriethoxysilane, γ-glycidoxypropyltrimethoxysilane, N-2- ( Aminoethyl) γ-aminopropyltrimethoxysilane, N-3- (4- (3-aminopropoxy) ptoxy) propyl-3-aminopropyltrimethoxysilane, 3-amino-1,2,4-triazole, 2- Amino-1,3,4-triazole, 4-amino-1,2,4-triazole, 1-amino-1,3,4-triazole, p-styryltrimethoxysilane, vinylethoxysilane, N-phenyl-3 Coupling agents such as -aminopropyltrimethoxysilane and 3-mercaptopropyltriethoxysilane are preferred, and γ-glycidoxypropyltrimethoxysilane is preferred from the viewpoint of further improving adhesiveness. These coupling agents may be used alone or in combination of two or more.

  Regarding a specific method of treatment with a coupling agent in the present invention, for example, when using the above coupling agent, first, a predetermined amount of the coupling agent is dissolved in water as a solvent, and then the present invention. It is applied to the surface of the copper foil after the metal precipitation treatment in and dried. At this time, heat treatment may be performed as necessary. Moreover, as a method of apply | coating the coupling agent dissolved in water with respect to the surface of copper foil, well-known methods, such as a dipping method, a showering method, a spraying method, can be used, for example.

Moreover, about the insulating layer which consists of a polyimide-type resin in this invention, what was obtained by superposing | polymerizing a well-known diamine and an acid anhydride in presence of a solvent can be used.
Examples of the diamine used include 4,4′-diaminodiphenyl ether, 2′-methoxy-4,4′-diaminobenzanilide, 1,4-bis (4-aminophenoxy) benzene, 1,3-bis (4-amino). Phenoxy) benzene, 2,2'-bis [4- (4-aminophenoxy) phenyl] propane, 2,2'-dimethyl-4,4'-diaminobiphenyl, 3,3'-dihydroxy-4,4'- Diaminobiphenyl, 4,4′diaminobenzanilide and the like can be mentioned. Examples of the acid anhydride include pyromellitic anhydride, 3,3 ', 4,4'-biphenyltetracarboxylic dianhydride, 3,3'4,4'-biphenyltetracarboxylic dianhydride, 3,3 ', 4,4'-diphenylsulfone tetracarboxylic dianhydride, 4,4'-oxydiphthalic anhydride and the like can be mentioned. About diamine and an acid anhydride, respectively, only 1 type may be used and it can also be used in combination of 2 or more types.

  Examples of the solvent used in the polymerization include dimethylacetamide, n-methylpyrrolidinone, 2-butanone, diglyme, xylene, and the like. These can be used alone or in combination of two or more. . The resin viscosity of the precursor (polyamic acid) obtained by polymerization is preferably in the range of 500 cps to 35000 cps.

  In this invention, about the method of forming the resin layer which consists of a polyimide-type resin, the precursor solution of a polyimide is apply | coated to the surface of the copper foil which performed the metal deposition process and the process by a coupling agent, and the temperature range is 100-450. The solvent is dried and imidized by performing a heat treatment for about 5 to 20 minutes at a temperature range of 300C, preferably 300C to 450C. If the temperature of the heat treatment is lower than 100 ° C, the polyimide may not be imidized sufficiently and the original characteristics may not be exhibited. Conversely, if the temperature exceeds 450 ° C, the resin layer and the copper foil made of polyimide resin are oxidized. There is a risk of deterioration due to, for example. If the temperature of heat processing is 300 degreeC or more, imidation of resin can fully advance.

  The thickness of the insulating layer in the present invention is preferably in the range of 8 to 45 μm, and preferably in the range of 15 to 40 μm. If the thickness of the insulating layer is less than 8 μm, there may be a problem in the transportability at the time of mounting after manufacturing the copper-clad laminate, and conversely if it exceeds 45 μm, the dimensional stability during the production of the copper-clad laminate There is a risk of problems in flexibility and the like.

The polyimide resin forming the insulating layer in the present invention preferably has a coefficient of linear thermal expansion (CTE) of 30 × 10 ⁻⁶ / ° C. or less, more preferably a CTE of 1 × 10 ⁻⁶ to 30 × 10 ⁻⁶ / A non-thermoplastic low thermal expansion polyimide resin having a temperature range of ° C. is preferable. By forming an insulating layer using a polyimide resin with a CTE value in the above range, it is possible to reduce as much as possible the occurrence of curling when forming a copper-clad laminate with excellent dimensional stability. Excellent adhesion and cover material adhesion. Furthermore, sinking of the chip or the like during mounting of the obtained copper-clad laminate can be reduced.

  Further, the insulating layer in the present invention may be formed from two or more layers of polyimide resin. At this time, it is preferable that 70% or more of the total thickness of the polyimide resin forming the insulating layer is formed from the non-thermoplastic low thermal expansion polyimide resin having the CTE. If the ratio (thickness) of the non-thermoplastic low-thermal-expansion polyimide resin in the insulating layer is less than 70%, the effect of reducing sinking during mounting may not be exhibited sufficiently.

  The copper-clad laminate in the present invention preferably has an initial adhesive strength of 1.0 kN / m or more (when the copper foil thickness is 18 μm and the circuit width is 100 μm), and the adhesive strength is maintained after 168 hours at 150 ° C. The rate should be 80% or more. With these values, the product has excellent reliability as a product for flexible printed circuit boards.

  The copper-clad laminate in the present invention may be a single-sided copper-clad laminate provided with a copper foil only on one side of the insulating layer, and two copper foils are prepared and the respective adhesive surfaces are prepared. It is good also as a double-sided copper clad laminated board formed by performing the metal precipitation process and the process by a coupling agent in this invention, and interposing an insulating layer between these copper foils. In addition, in order to obtain a double-sided copper-clad laminate, after forming a single-sided copper-clad laminate, the insulating layers may be faced to each other and bonded by hot pressing, or between two copper foils. An insulating layer may be sandwiched between the layers and pressed by hot pressing.

The copper-clad laminate in the present invention is excellent in heat resistance, flame retardancy, dimensional stability, etc. because it forms an insulating layer directly on the copper foil without using an adhesive, and sinks when mounting a chip or the like In addition, high-density mounting is possible, excellent in fine circuit processability, and excellent adhesion and adhesive strength retention. As a flexible printed circuit board, it is reliable when used in electrical and electronic components. It is excellent and can be suitably used for fine processing applications. In particular, when the insulating layer is formed from a non-thermoplastic low thermal expansion polyimide resin having a coefficient of linear thermal expansion (CTE) of 30 × 10 ⁻⁶ / ° C. or less, the insulating layer has excellent dimensional stability and a copper-clad laminate is formed. The occurrence of curling at the time of cutting can be reduced as much as possible, and excellent performance in ACF adhesion and cover material adhesion can be achieved, and further, sinking of chips etc. during mounting can be further reduced. it can.

  Hereinafter, the present invention will be described in more detail based on examples. In the following Examples, various evaluations are as follows unless otherwise specified.

[Measurement of linear expansion coefficient]
Using a thermomechanical analyzer manufactured by Seiko Instruments Inc., heated up to 250 ° C, held at that temperature for 10 minutes, cooled at a rate of 5 ° C / min, and an average coefficient of thermal expansion from 240 ° C to 100 ° C ( (Linear thermal expansion coefficient) was determined.

[Measurement of adhesive strength]
The adhesive strength between the copper foil and the insulating layer is that after forming an insulating layer made of polyimide resin on the copper foil, circuit processing is performed to a line width of 0.1 mm, and a tensile tester manufactured by Toyo Seiki Co., Ltd. Using -M1), the copper foil was peeled off in the 90 ° direction and measured.

[Measurement of retention rate]
After forming an insulation layer made of polyimide resin on the copper foil, circuit processing was performed to a line width of 0.1 mm, and then heat treatment was performed in an air atmosphere at 150 ° C. for 168 hours, and a tensile tester manufactured by Toyo Seiki Co., Ltd. Using -M1), the copper foil was peeled off in the 90 ° direction and measured. The percentage of the obtained value and the adhesive force obtained above was defined as the retention rate.

[Measurement of ACF adhesion]
After forming an insulating layer made of a polyimide resin on the copper foil, the copper foil is etched to create a laminate. After moderately cutting the laminate, using a Japan Avionics pulse heat bonder, after attaching ACF (anisotropic conductive film) under certain conditions, Toyo Seiki Co., Ltd. tensile tester (Strograph-M1 The copper foil was peeled off in the 90 ° direction and measured. About the measured result, it evaluated in two steps, (circle): 1.5 kN / m or more and (triangle | delta): less than 1.5 kN / m.

[Measurement of sinking during mounting]
After an insulating layer made of polyimide resin is formed on the copper foil, circuit processing for mounting is performed. In the mounting, a gold bump of a chip is thermocompression bonded by a gold-tin eutectic on a copper wiring plated with tin. The thermocompression bonding tool is heated to 300 ° C. or higher, and the pressure and the crimping time are performed under conditions optimized for each member. The eutectic state of gold-tin and the sinking of the pump are judged by observing the cross section after thermocompression bonding. ◎ No subsidence at the time of cross-sectional observation, ○: Slight subsidence is observed but there is no practical problem, Δ : There was a problem in any one or more of non-eutectic region formation, bump thermal deformation, and sinking into the resin part, and was evaluated in three stages.

(Synthesis Example 1)
Put n-methylpyrrolidinone in a reaction vessel equipped with a thermocouple and stirrer and capable of introducing nitrogen, immerse this reaction vessel in ice water, and then add pyromellitic anhydride (PMDA) to the reaction vessel. Thereafter, 4,4′-diaminodiphenyl ether (hereinafter referred to as DAPE) and 2′-methoxy-4,4′-diaminobenzanilide (hereinafter referred to as MABA) were added. The total amount of monomers charged was 15 wt%, the molar ratio of each diamine (MABA: DAPE) was 60:40, and the molar ratio of acid anhydride to diamine was 0.98: 1.0. Thereafter, stirring was further continued, and the reaction vessel was removed from the ice water when the temperature in the reaction vessel was in the range of room temperature to ± 5 ° C. Stirring was continued for 3 hours at room temperature, and the solution viscosity of the resulting polyamic acid was 15,000 cps.

(Synthesis Example 2)
In a reaction vessel equipped with a thermocouple and a stirrer and capable of introducing nitrogen, n-methylpyrrolidinone is placed, and after this reaction vessel is immersed in ice water contained in the vessel, PMDA / 3, 3 ', 4, 4 '-Biphenyltetracarboxylic dianhydride (hereinafter BTDA) was added, and then 4,4'-diaminodiphenyl ether (hereinafter DAPE) was added. The total monomer charge was 15 wt%, and the molar ratio of acid anhydride to diamine was 1.03: 1.0. Thereafter, stirring was further continued, and the reaction vessel was removed from the ice water when the temperature in the reaction vessel was in the range of room temperature to ± 5 ° C. Stirring was continued for 3 hours at room temperature, and the solution viscosity of the resulting polyamic acid was 3,200 cps.

(Synthesis Example 3)
N, N-dimethylacetamide was placed in a reaction vessel equipped with a thermocouple and a stirrer and capable of introducing nitrogen. 2,2′-Dimethyl-4,4′-diaminobiphenyl (hereinafter referred to as m-TB) was dissolved in the reaction vessel with stirring. Then 3,3 ', 4,4'-biphenyltetracarboxylic dianhydride and pyromellitic dianhydride were added. The total amount of monomers charged was 15 wt%, and the molar ratio of each acid anhydride (BPDA: PMDA) was 80:20. Thereafter, stirring was continued for 3 hours, and the solution viscosity of the obtained polyamic acid was 20,000 cps.

(Synthesis Example 4)
N, N-dimethylacetamide was placed in a reaction vessel equipped with a thermocouple and a stirrer and capable of introducing nitrogen. 2,2-bis [4- (4-aminophenoxy) phenyl] propane was dissolved in the reaction vessel with stirring. Then 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride and pyromellitic dianhydride were added. The total amount of monomers charged was 15 wt%, and the molar ratio of each acid anhydride (BPDA: PMDA) was 90:10. Thereafter, stirring was continued for 3 hours, and the solution viscosity of the obtained polyamic acid was 5,000 cps.

[Example 1]
An electrolytic copper foil having a thickness of 18 μm and a surface roughness Rz = 0.7 μm was prepared. The surface of this copper foil is plated with a bath containing a predetermined amount of nickel, zinc and cobalt (metal precipitation treatment), and each metal is deposited on the surface of the copper foil so that the amount of precipitation shown in Table 1 is obtained. A foil 1 was obtained. In addition, about this copper foil 1, the metal composition analysis contained in the surface of copper foil was performed using the atomic absorption analyzer (made by Rigaku). The results are shown in Table 1.

  Next, an aqueous solution prepared by adjusting the concentration of γ-glycidoxypropyltrimethoxysilane to a concentration of 5 g / l was prepared and sprayed on the surface of the copper foil that had been subjected to metal deposition treatment by showering. It was dried for about 5 seconds (treatment with a coupling agent). The polyimide precursor solution prepared in Synthesis Example 1 is applied by hand on the surface of the copper foil that has been subjected to the coupling treatment, and after drying, heat treatment is finally performed at 300 ° C. or more for about 4 minutes, and the thickness of the insulating layer is 40 μm. A copper-clad laminate was obtained. The thermal expansion coefficient of polyimide (insulating layer) in the obtained copper-clad laminate was 20 ppm. The 0.1 mm peel of this copper-clad laminate had an initial adhesive strength of 1.0 kN / m and a retention rate of adhesive strength of 90% after 168 hours at 150 ° C. (in the air atmosphere). Further, the evaluation of ACF adhesion and the sinking during mounting were evaluated by the method described above. The results are shown in Table 2.

[Example 2]
Using the same copper foil 1 as in Example 1, treatment with a coupling agent was performed in the same manner as in Example 1. The polyimide precursor solution prepared in Synthesis Example 3 is applied by hand on the surface of the copper foil 1 that has been subjected to the metal deposition treatment and the coupling agent treatment, and after drying, heat treatment is finally performed at 300 ° C. or more for about 4 minutes. Then, a copper-clad laminate with an insulating layer thickness of 40 μm was obtained. The thermal expansion coefficient of polyimide (insulating layer) in the obtained copper-clad laminate was 14 ppm. The 0.1 mm peel of this copper-clad laminate had an initial adhesive strength of 1.0 kN / m and a retention rate of 90% after 168 hours at 150 ° C. (in the atmosphere). Further, the evaluation of ACF adhesion and the sinking during mounting were evaluated by the method described above. The results are shown in Table 2.

[Reference Example 1]
Using the same copper foil 1 as in Example 1, treatment with a coupling agent was performed in the same manner as in Example 1. The polyimide precursor solution prepared in Synthesis Example 2 is applied by hand on the surface of the copper foil 1 that has been subjected to the metal deposition treatment and the coupling agent treatment, and after drying, heat treatment is finally performed at 300 ° C. or more for about 4 minutes. Then, a copper-clad laminate with an insulating layer thickness of 40 μm was obtained. The thermal expansion coefficient of polyimide (insulating layer) in the obtained copper-clad laminate was 54 ppm. The 0.1 mm peel of this copper-clad laminate had an initial adhesive strength of 1.8 kN / m, a retention rate of 25% after 168 hours at 150 ° C. (in the atmosphere). Further, the evaluation of ACF adhesion and the sinking during mounting were evaluated by the method described above. The results are shown in Table 2.

[Reference Example 2]
Using the same copper foil 1 as in Example 1, treatment with a coupling agent was performed in the same manner as in Example 1. The polyimide precursor solution prepared in Synthesis Example 4 is applied by hand on the surface of the copper foil 1 that has been subjected to the metal deposition treatment and the coupling agent treatment, and after drying, heat treatment is finally performed at 300 ° C. or more for about 4 minutes. Then, a copper-clad laminate with an insulating layer thickness of 40 μm was obtained. The thermal expansion coefficient of polyimide in the obtained copper-clad laminate was 48 ppm. The 0.1 mm peel of this copper-clad laminate had an initial adhesive strength of 1.8 kN / m, a retention rate of 25% after 168 hours at 150 ° C. (in the atmosphere). Further, the evaluation of ACF adhesion and the sinking during mounting were evaluated by the method described above. The results are shown in Table 2.

[Comparative Example 1]
An electrolytic copper foil having a thickness of 18 μm and a surface roughness Rz = 0.8 μm was prepared. The surface of this copper foil is plated with a bath containing a predetermined amount of nickel, zinc and cobalt (metal precipitation treatment), and each metal is deposited on the surface of the copper foil so that the amount of precipitation shown in Table 1 is obtained. A foil 2 was obtained. Using this copper foil 2, a treatment with a coupling agent was performed in the same manner as in Example 1. The polyimide precursor solution prepared in Synthesis Example 1 is applied by hand onto the surface of the copper foil 2 that has been subjected to the metal deposition treatment and the coupling agent treatment, and after drying, heat treatment is finally performed at 300 ° C. or more for about 4 minutes. Then, a copper-clad laminate with an insulating layer thickness of 40 μm was obtained. The thermal expansion coefficient of polyimide (insulating layer) in the obtained copper-clad laminate was 20 ppm. The 0.1 mm peel of this copper-clad laminate had an initial adhesive strength of 0.4 kN / m (Table 2).

[Comparative Example 2]
Using the copper foil 2, treatment with a coupling agent was performed in the same manner as in Example 1. The polyimide precursor solution prepared in Synthesis Example 3 is applied by hand on the surface of the copper foil 2 that has been subjected to the metal deposition treatment and the coupling agent treatment, and after drying, heat treatment is finally performed at 300 ° C. or more for about 4 minutes. Then, a copper-clad laminate with an insulating layer thickness of 40 μm was obtained. The thermal expansion coefficient of polyimide in the obtained copper-clad laminate was 14 ppm. The 0.1 mm peel of this sample had an initial adhesive strength of 0.4 kN / m (Table 2).

[Comparative Example 3]
A rolled copper foil having a thickness of 18 μm and a surface roughness Rz = 1.0 μm was prepared. The surface of this copper foil is plated with a bath containing a predetermined amount of nickel, zinc and cobalt (metal precipitation treatment), and each metal is deposited on the surface of the copper foil so that the amount of precipitation shown in Table 1 is obtained. A foil 3 was obtained. Using this copper foil 3, treatment with a coupling agent was performed in the same manner as in Example 1. The polyimide precursor solution prepared in Synthesis Example 3 is applied by hand on the surface of the copper foil 3 that has been subjected to the metal deposition treatment and the coupling agent treatment, and after drying, heat treatment is finally performed at 300 ° C. or higher for about 4 minutes. Then, a copper-clad laminate with an insulating layer thickness of 40 μm was obtained. The thermal expansion coefficient of polyimide (insulating layer) in the obtained copper-clad laminate was 14 ppm. The 0.1 mm peel of this copper-clad laminate had an initial adhesive strength of 0.2 kN / m (Table 2).

[Comparative Example 4]
An electrolytic copper foil having a thickness of 18 μm and a surface roughness Rz = 1.0 μm was prepared. The surface of this copper foil is plated with a bath containing a predetermined amount of nickel, zinc and cobalt (metal precipitation treatment), and each metal is deposited on the surface of the copper foil so that the amount of precipitation shown in Table 1 is obtained. A foil 4 was obtained. Using this copper foil 4, a treatment with a coupling agent was performed in the same manner as in Example 1. The polyimide precursor solution prepared in Synthesis Example 3 above is applied to the surface of the copper foil 4 subjected to the metal deposition treatment and the coupling agent treatment by hand, and after drying, heat treatment is finally performed at 300 ° C. or more for about 4 minutes. Then, a copper-clad laminate with an insulating layer thickness of 40 μm was obtained. The thermal expansion coefficient of polyimide (insulating layer) in the obtained copper-clad laminate was 14 ppm. The 0.1 mm peel of this copper-clad laminate had an initial adhesive strength of 0.6 kN / m and a retention rate of 70% after 168 hours at 150 ° C. (in the atmosphere). Further, the evaluation of ACF adhesion and the sinking during mounting were evaluated by the method described above. The results are shown in Table 2.

[Comparative Example 5]
An electrolytic copper foil having a thickness of 18 μm and a surface roughness Rz = 1.0 μm was prepared. The surface of this copper foil is plated with a bath containing a predetermined amount of nickel, zinc and cobalt (metal precipitation treatment), and each metal is deposited on the surface of the copper foil so that the amount of precipitation shown in Table 1 is obtained. A foil 5 was obtained. Using this copper foil 5, a treatment with a coupling agent was performed in the same manner as in Example 1. The polyimide precursor solution prepared in Synthesis Example 3 is applied to the surface of the copper foil 5 that has been subjected to the metal deposition treatment and the coupling agent treatment by hand, and after drying, heat treatment is finally performed at 300 ° C. or more for about 4 minutes. Then, a copper-clad laminate with an insulating layer thickness of 40 μm was obtained. The thermal expansion coefficient of polyimide (insulating layer) in the obtained copper-clad laminate was 14 ppm. The 0.1 mm peel of this copper-clad laminate had an initial adhesive strength of 0.3 kN / m (Table 2).

[Comparative Example 6]
Using the copper foil 1, the polyimide precursor solution prepared in Synthesis Example 3 was hand-coated on the surface of the copper foil 1 subjected to the metal deposition treatment without performing the treatment with the coupling agent, and after drying, finally Heat treatment was performed at 300 ° C. or more for about 4 minutes to obtain a copper-clad laminate with an insulating layer thickness of 40 μm. The thermal expansion coefficient of polyimide (insulating layer) in the obtained copper-clad laminate was 14 ppm. The 0.1 mm peel of this copper-clad laminate had an initial adhesive strength of 0.6 kN / m (Table 2).

Claims (4)

A copper-clad laminate having a polyimide precursor solution coated on a copper foil and provided with an insulating layer made of a polyimide resin formed by heat treatment, and having a coefficient of linear thermal expansion (CTE) of 30 × 10 ⁻⁶ / ° C. or less A metal deposition treatment in which at least nickel, zinc, and cobalt are deposited on the surface of the copper foil having a surface roughness Rz of 0.3 to 1.0 μm in contact with an insulating layer made of a non-thermoplastic low thermal expansion polyimide resin. The surface of the copper foil subjected to the metal deposition treatment is nickel 5 to 15 μg / cm ² , zinc 1 to 5 μg / cm ² , and cobalt 0.1 to 5 μg / cm ^2. And nickel / (nickel + zinc) representing the content ratio of nickel and zinc is 0.70 or more. The metal composition ratio present on the surface of the copper foil after the metal deposition treatment is 70 to 85% by weight of nickel, 10 to 20% by weight of zinc, and 30% by weight or less of cobalt with respect to the total amount of all metals excluding copper. copper-clad laminate according to claim 1 is. 3. The copper-clad laminate according to claim 1, wherein the insulating layer comprises a single layer of a non-thermoplastic low thermal expansion polyimide resin having a coefficient of linear thermal expansion (CTE) of 30 × 10 ⁻⁶ / ° C. or less.   The initial adhesive strength is 1.0 kN / m or more (when the copper foil thickness is 18 μm and the circuit width is 100 μm), and the retention of adhesive strength after 168 hours at 150 ° C. is 80% or more. A copper-clad laminate according to crab.