JPH02131935A - Flexible copper-clad board - Google Patents

Abstract

PURPOSE:To increase adhesive strength between a heat resistant polymer film and a copper foil by forming a silane coupling agent on the surface of a copper foil layer in contact with a heat resistance polymer film layer, and then securing simple metal, its oxide or its alloy thereto. CONSTITUTION:After a silane coupling agent is formed on a copper foil, simple metal, its oxide or alloy is formed thereon. The simple metal, its oxide or alloy desirably selectively includes, for example, copper, zinc, chromium, nickel, copper oxide, chromium oxide, nickel-copper alloy, zinc-chromium alloy. A heat resistance polymer film layer is formed of heat resistant polymer having an imide bond and/or heat resistant polymer having heterocycle except the imide bond. The polymer having the imide bond includes, for example, polyimide, polyamideimide, polyhydantoin, polyparabanic acid, polyoxazinedion, etc., and the polymer having the heterocycle includes, for example, polybenzoimidazole, polyimidazopyrrolon, triazine derivatives, etc.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention is applied to flexible copper-clad laminates that are becoming popular in the electronics industry.
It relates to Clad Laminate (hereinafter abbreviated as FCL), and particularly relates to FCL which has excellent durability such as heat resistance and humidity resistance to deterioration. [Prior Art] FCL is mainly used as a base material for flexible printed wiring boards, but is also used for surface heating elements, electromagnetic shielding materials, flat cables, packaging materials, and the like.

In recent years, as cases in which printed wiring boards are housed have become more compact, FCL has been increasingly used as a base material for printed wiring boards.

Such FCLs have conventionally been manufactured by laminating a heat-resistant polymer film to a copper foil using an adhesive made of an organic polymer, usually with a thickness of 5 μm or more. However, FCL using this adhesive does not take full advantage of the excellent properties of the heat-resistant polymer film because the properties of the adhesive are insufficient, and there are problems particularly in terms of heat resistance.

For this purpose, a method of forming an FCL in which a heat-resistant polymer film and a copper foil are directly bonded to each other without using an adhesive has been studied.

For example, U.S. Patent No. 3,179,634, U.S. Patent No. 3,73
6, 170, JP-A-49-129,862, JP-A No. 58
-190.091, 59-162,044, etc. However, adhesive-free FC using these methods
L indicates that the adhesive strength between the heat-resistant polymer film and the copper foil is insufficient, or even if the adhesive strength is sufficient, the strength is unstable, and the adhesive strength deteriorates significantly in a high-temperature atmosphere. There was a drawback. In particular, among heat-resistant polymers, it is difficult to obtain stable and high adhesive strength with polyimide and polyamide-imide due to various reasons. Furthermore, U.S. Patent No. 3,736,170, Japanese Patent Application Laid-open No. 1987-
162,044, as described in the FC
In the case of polyimide insoluble in a phenolic solvent, which is suitable as a heat-resistant polymer for L, the peel strength between the heat-resistant polymer film and the copper foil is 0.30 to 0.30, as seen in the examples. 0.60 kg/cm, and if the bending stress is large or the circuit width is narrow, it cannot be said that the adhesive strength is sufficient considering the reliability of the circuit. [Problem to be solved by the invention] An epoxy resin whose polyimide film has a thickness of 5 μm or more,
FCL laminated to copper foil through an adhesive layer made of organic polymers such as acrylic resin has already been proposed, but existing FCLs that use adhesives made of such organic polymers have limited characteristics. has not reached the required level in many respects. On the other hand, although FCL without an adhesive layer is superior to FCL with an adhesive layer in terms of heat resistance, it does not reach the required level in terms of adhesive strength and strength of the heat-resistant polymer film. ．． In view of this situation, the present invention has been developed to ensure that the heat-resistant polymer film is firmly and stably adhered to the copper foil, and that the adhesive strength is durable while maintaining the situation where the excellent properties of the heat-resistant polymer film are utilized. This type of FCL is extremely useful in industry, especially in the electronics industry. [A thousand steps to solve the problem] That is, the present invention provides a flexible copper-clad laminate having a heat-resistant polymer film layer and a copper foil layer on at least one of the heat-resistant polymer film layers, which A flexible copper laminate N in which an elemental metal, an oxide thereof, or an alloy thereof is fixed to the copper foil layer after a silane coupling agent is formed on the surface of at least one copper foil layer in contact with the heat-resistant polymer. provisional, is,
In addition, the silane canopring agent is one or more selected from amine type, epoxy type, and mercapto type. , chromium, oxides thereof, or alloys thereof. That is, the gist of the present invention is that after providing a layer made of a silane coupling agent on at least one surface of m1B, a simple metal, its oxide, or its alloy is fixed, and a heat-resistant polymer,
Alternatively, a solution of the precursor is applied and dried by heating to form a heat-resistant polymer film.
F, which has solved the above-mentioned problems and has particularly improved adhesion.
The point is that CL is provided. Originally, the adhesive strength between the copper foil surface and the heat-resistant polymer is small. Therefore, in general, metals, their oxides, alloys, etc. are formed on copper foil to increase the adhesive strength with heat-resistant polymers. However, from a macroscopic perspective, simple metals, their oxides, alloys, etc. formed on copper foil are actually #JA
Since the entire surface of the foil is not covered, the adhesive strength depends on the adhesive strength between the above-mentioned simple metal or its oxide, alloy, etc. on the copper foil and the heat-resistant polymer. , it is inevitable to think that the adhesion strength remains low in the areas where alloy etc. are not formed. Therefore, in the present invention, before forming the above-mentioned elemental metal, its oxide, alloy, etc. on the copper foil, first, a silane coupling agent is fixed on the surface of the copper foil, and then the elemental metal, its oxide, alloy, etc. etc. are formed. The silane camping agent binds to the fI foil through Si-0 bonds, so when the silane camping agent is treated on the w4 foil, organic reactive groups such as amino groups, epoxy groups, and mercapto groups are exposed on the surface. That means you are doing it. After this, simple metals, their oxides, alloys, etc. are formed, but since these generally do not easily react with existing materials, the simple metals, their oxides, alloys, etc. It is not actually formed. With this kind of surface treatment,
On the surface of the copper foil, there are parts where the metal itself or its oxides, alloys, etc. are exposed, and parts where the silane coupling agent is exposed, so the heat-resistant polymer formed later and This allows for strong adhesion. Furthermore, if a silane coupling rule is simply formed on the copper foil without forming a single metal or its oxide, alloy, etc., the copper will be exposed on the surface of the copper foil and will be easily oxidized. When a heat-resistant polymer is formed after the above surface treatment, there is almost no deterioration even under harsh conditions such as heat drying of the resin, solder immersion, high temperature continuous treatment, high temperature high temperature treatment, etc., and there is no significant The thickness of the copper foil used in the present invention can be arbitrarily selected, but it is usually within the range of about 10 to 100 μm, and preferably about 10 to 50 μm, making it possible to maintain peel strength. It is within the range of . It is preferable that the surface of the copper foil in the present invention be subjected to surface purification treatment before being subjected to surface treatment. Moreover, the silane coupling agent used in the present invention is selected from those shown below.

NRz -Si (OCH3 OH CH, HS Rz Si (ORn).+CH3 HS Rz Si (OR4)z O CH3 Here, ~5) (n=1~5) More preferably, R..R. and Ri are R2
: →CH20T n=1 ~3 R4 : −+C I{ t +−r−C H 3 n =
O ~2 These silane coupling agents are easily available as commercial products. Siloxane compounds obtained by hydrolyzing these compounds may also be used, and these siloxane compounds also have efficacy as coupling agents. These coupling agents preferably have at least one hydrolyzable group remaining in their molecules, and this hydrolyzable group is a hydrogen group bonded to a silicon atom. It may also be a mixture with other hydrolyzable silanes, and they may be hydrolyzed together. In the present invention, after the silane coupling agent is formed on the copper foil, an elemental metal or its oxide, alloy, etc. is formed. Chromium, nickel, copper oxide, chromium oxide,
Preferably, it is selected from nickel-copper alloys and zinc-chromium alloys. The heat-resistant polymer film layer used in the present invention is made of a heat-resistant polymer having an imide bond and/or a heat-resistant polymer having a heterocycle other than an imide bond. Examples of the polymer having an imide bond include polyimide, These include polyamideimide, polyhydantoin, polybalabanic acid, polyoxazinedione, etc. Heat-resistant polymers having heterocycles other than imide bonds include polybenzimidazole, polyimidazopyrrolone, triazine derivatives, and the like.

In the present invention, heat-resistant polymers having imide bonds are preferred, and polyimides and polyamideimides are more preferred, and these may be polymerized.

Typical polyimides have the structural formulas shown below. Further, a polymer obtained from romellitic dianhydride and an aromatic diamine having a repeating unit represented by the structural formula (1), a polymer having a repeating unit represented by the structural formula (2), and a polymer having a repeating unit represented by the structural formula (2).
A polymer obtained from 3',4.4°-benzophenonetetracarboxylic dianhydride and an aromatic diamine, and a 3,3°,4.
Polymers obtained from 4'-biphenyltetracarboxylic dianhydride and aromatic diamines are also suitable. Further, the polyamideimide has the structural formula Q Q shown below.

In the above-mentioned Mizokari formula, R is the residue of the raw material diamine from which the amino group has been removed. Examples of diamines containing R that are the raw materials include O+I+p-phenylenediamine, 4,
4'-diaminodiphenylmethane, 3,3゛-diaminodiphenylmethane, 4,4゜-diaminobiphenyl, 3
, 3゜-diaminobiphenyl, 4.4-diaminoterphenyl, 3.3''-diaminocuphenyl, 44゜-
Diaminodiphenyl ether, 3,3'-diaminodiphenyl ether, 4,4°diaminodiphenyl sulfone, 3,3'diaminodiphenyl sulfone, 4,4°-diaminodiphenyl sulfide, 3,3°-diaminodiphenyl sulfide , 4,4゛-diaminodiphenylsulfoxide, 3.3''-diaminodiphenylsulfoxide, 4.4''-diaminobenzophenone, 3.3゜-
Diaminobenzophenone, 22-bis(4-aminophenyl)propane, 2,2-bis(3-aminophenyl)propane, bis[4-(4-aminophenoxy)phenyl]methane, bis[4-(3-aminophenoxy) ) phenylcomethane, 2,2-bis[4-(.4-aminophenoxy)phenyl]propane, 2,2-pis[
4-(3-aminophenoxy)phenyl]propane,
2.2-bis[4-(4-aminophenoxy)phenyl]-1.1,L3,3.3-hexafluoropropane, 2,2-bis[4-(3-aminophenoxy)phenyl]-1.1, 1,3,3.3-hexafluoropropane, 1.3-bis(4-aminophenoxy)benzene, 1.3bis(3-aminophenoxy)benzene, 4.
4°-bis(4-aminophenoxy)biphenyl, 4.
4'-bis(3-aminophenoxy)biphenyl, bis[4(4-aminophenoxy)phenyl]ketone, bis[4-(3-aminophenoxy)phenyl 1 ton,
Bis[4- (4-aminophenoxy)phenyl] sulfide, bis[4- (3-aminophenoxy)phenyl] sulfide, bis[4- (4-aminophenoxy)phenyl 1 sulfone, bis[4- (3-aminophenoquine) phenyl] sulfone, bis[4-(4-aminophenoxy)phenyl 1 sulfoxide, bis[4-(
3-aminophenoxy) phenyl] sulfoxide, bis [4- (4-aminophenoxy) phenyl] ether, bis [4- (3-aminophenoxy) phenyl coether, 4,4°-bis (4-aminophenyl sulfonyl) diphenyl ether, 4.4”-bis(3-aminophenylsulfonyl)diphenyl ether, 4,4°-
Symmetrical diamines such as bis(4-aminothiophenoxy)diphenylsulfone, 4.4″-bis(3-aminothiophenoxy)diphenylsulfone, 1.4-bis[4-(3aminothiophenoxy)penzoyl]benzene, etc. These can be used alone, in a mixture of two or more, or as a copolymer.To synthesize the above heat-resistant polymer, for example, N-methylpyrrolidone, N,N- Dimethylformamide, N,N-dimethylacetamide, dimethyl sulfoxide, γ-butyrolactone, cresol, phenol,
Preferably, the reaction is carried out in a solvent such as halogenated phenol.

In manufacturing the FCL of the present invention, a silane cambling agent is first formed on the copper foil. The method for forming the silane casobling agent on the copper foil is not particularly specified, as it is formed by applying it in the same manner as the application of a normal casobling agent.

For example, add 0.05% of the silane coupling agent to water.
An aqueous solution is prepared with a ratio of ~1%, and this is applied to the surface of the cleaned copper foil in a thin layer, usually 80 μm or less, with a thickness of 0.
50-150 after coating to a thickness of 1 μm or more
Water as a solvent is removed by drying at a temperature of about 100 m to form a silane camping agent on the surface of the copper foil.

Also, the silane camping agent was dissolved in a solvent such as cellosonoleph acetate at a ratio of about 0.05 to 1%. After immersing the copper foil in this solution, the silane coupling agent may be formed on the surface of the copper foil by drying and removing the solvent at about 50 to +50'c. The copper foil on which the silane camping agent has been formed as described above is then coated with a simple metal, its oxide, alloy, or the like.

There is no particular limitation on the method of forming these metals, their oxides, alloys, etc., but copper, chromium, nickel,
Water that contains one or more types of ions such as zinc? It is preferable to conduct the electrolytic treatment in 'jjfl' using a copper foil as a shade.

(Example) Next, the present invention will be further explained by showing examples. Example 1 (1) Synthesis of amic acid phase In a container equipped with a stirrer, a reflux condenser and a nitrogen inlet tube, 147 g (0.40 mol) of 4.4°-bis(3-aminophenoxy)biphenyl and 4.4°-bis(3-aminophenoxy)biphenyl were added. 4"-diaminodiphenyl ether 320g (1.60 mol)
wo, dissolved in NN-dimethylacetamide 3500d,
Cool to around 0°C, add 436g (2.0 mol) of biromellitic dianhydride under nitrogen atmosphere, and bring to 0'
The mixture was stirred for 2 hours near C. Next, return the above solution to room temperature,
The reaction was carried out for about 24 hours under a nitrogen atmosphere. The logarithmic viscosity of the polyamic acid solution thus obtained was 1.8 dl/g. This 7 volume solution of polyamic acid was diluted to 18% with N,N-dimethylacetamide, and the rotational viscosity was adjusted to 100,000.
Adjusted to cps. (2) Surface treatment of copper foil An electrolytic copper foil (38C, thickness 35 μm) manufactured by Mitsui Mining and Mining Co., Ltd. was immersed in dilute hydrochloric acid of 10% for 1 minute to remove the surface treatment layer. Next, a silane coupling agent having the following structure (manufactured by Shin-Etsu Chemical, IBM-573) ChHs-NH-CHz
-CHz-CHx-Si (OCRs) s? ．． 0g was dissolved in 1.0kg of cellosolve acetate, and this solution was applied to the shiny surface (g
4 μm coating on the surface where J4 is exposed, 80
It was dried at °C for 15 minutes. This silane ring-treated copper foil was heated to 5 g/l of Cr (h = 5 g/l) at 30°C.
, 20 g/l of NaOH. ．． ZnSOn ・71
1 ■ Water containing 0 58/2? 8 liquid at a current density of IOOA/bo for 15 seconds. At this time, the silane coupling treated surface of the copper foil was used as a cathode, and platinum was used as a counter electrode.

(3) Preparation of FCL 7 volumes of polyamic acid obtained in (1) 'tFI-
) was uniformly cast onto the electrolytically treated surface of the electrolytic copper foil obtained in ), heated and dried at 135°C for 5 minutes, then at 180°C for 4 minutes, and then heated in a nitrogen atmosphere at 250°C. The substrate was heated for 3 minutes in a nitrogen atmosphere at 350° C. and then for 5 minutes in a nitrogen atmosphere to obtain a flexible substrate.

The thickness of the polyimide layer of the flexible substrate thus obtained was 35 μm.

The peel strength between the polyimide layer and the surface treatment layer of this flexible substrate was 0.8 kg/cd. Comparative Example 1 A flexible substrate was obtained by carrying out the same operations as in Example 1, except that an electrolytic copper foil that had not been subjected to silanka sampling treatment was used as 'dAffi in Example 1. The thickness of the polyimide layer of the flexible substrate thus obtained was 30 μm.

The peel strength between the polyimide layer and the surface treatment layer of this flexible substrate was 0.3 kg/cd. Example 2 In Example 1 (2), Mitsui Mining & Co., Ltd. rolled copper foil (BSII, 35 μm) was used as the copper foil, except that silane coupling treatment and electrolytic treatment were performed on the non-glossy surface of the copper foil. A flexible substrate was obtained by performing the same operation as in Example 1.

The thickness of the polyimide layer thus obtained on the flexible J-base was 30 μm. The peel strength between the polyimide layer and the surface treatment layer of this flexible substrate was 1.3 kg/cr1. Comparative Example 2 The same operations as in Example 2 were performed except that the silane coupling treatment in Example 2 was not performed and only the electrolytic treatment was performed on the non-glossy surface of the copper foil to obtain one sheet of flexible vinyl base.

The thickness of the polyimide layer of the flexible substrate thus obtained was 30 μm. The peel strength between the polyimide layer and the surface treatment layer of this flexible substrate was 0.5 kg/cJ. Example 3 Synthesis of (+) polyamide boriamic acid varnish A. Preparation of polyamide with amino end groups = 6.84 g (00342 mol) of 4,4°-diaminodiphenyl ether
Anhydrous N, N
- Completely dissolved in 40 g of dimethylacetamide.

2.46 g (0.0121 mol) of solid isophthalic acid dichloride and 2.46 g (0.0121 mol) of solid isophthalic acid dichloride were cooled to -5 to 0°C in the reactor using a solvent jugient under a nitrogen atmosphere. molar) mixture of the above? It was added little by little to 8 liquids.

After the addition was complete, the viscous reaction solution was heated to 0°C and stirred for 1 hour.

Next, 3.09 g of propylene oxide was added to the reaction mixture.
(0.0532 mol) was diluted with 6 g of anhydrous N,N-dimethylacetamide, and the temperature of the reaction solution was adjusted to 5 to 1 mol.
It was added dropwise while maintaining the temperature at 0'C. After dropping, add the reaction solution to 5~
The mixture was stirred at 10°C for 1 hour to obtain a polyamide having a terminal amino group and a theoretically calculated average molecular weight of L 000. B. Production of polyamic acid having an acid anhydride end: 27 of biromellitic dianhydride was prepared using the same reaction apparatus as in A.
．． 1g (0.124 mol) to 41g of anhydrous N,N-dimethylacetamide? A: It became cloudy. A solution of 22.9 g (0.124 mol) of 4,4°-diaminodiphenyl ether dissolved in 92 g of anhydrous N,N-dimethylacetamide was added dropwise at 5 to 20°C under a nitrogen atmosphere. The viscosity increased as the amine solution was added dropwise, and when 75% of the amine solution was added dropwise, 67 g of anhydrous N,N-dimethylacetamide was added to adjust the viscosity. After the addition was completed, the reaction mixture was stirred at 20 to 25°C for 1 hour to obtain a polyamic acid having a terminal acid anhydride and an average molecular weight of s,ooo according to theoretical calculation. C. Preparation of polyamide-polyamic acid block copolymer: polyamide 1′ with amino end groups obtained by A
The solution was added to the solution of the anhydride-terminated polyamic acid obtained in B at 15-20°C under nitrogen atmosphere for about 3 hours.
It took 0 minutes to add.

Further, 89 g of N,N-dimethylacetamide was added and stirred for 2 hours at 20-25"C. Intrinsic viscosity (35
°C, 0.5 g/100 d (measured in N,N-dimethylacetamide solution) 1.62 viscosity 1 volume 7 containing 15.0% by weight of polyamide polyamic acid bronch copolymer
Night was gained.

(2) Surface treatment of copper foil An electrolytic copper foil (3EC, thickness 35 μm) manufactured by Mitsui Mining & Co., Ltd. was immersed in dilute hydrochloric acid of 10% for 1 minute to remove the surface treatment layer. Next, a silane coupling agent having the following structure (KBM-803 manufactured by Shin-Etsu Chemical Co., Ltd.) Its-CHz-C}It-CHz-Si (OCHx
) Dissolve 1.0g of s in 1.0kg of cellosolve acetate, apply this solution to the shiny surface (exposed copper surface) of the electrolytic copper foil from which the above surface treatment layer has been removed to a thickness of 4 μm, and heat at 80°C. Dry for 15 minutes. This silane coupling-treated copper foil was heated to CuSO4 at 30°C.
・35g/l of 5HJ, NiSO.・6HzO22
5g/l, polyacrylamide (molecular weight 700,000) 1
g/2, HxSOa 5g/2, NazsOa 50g
/l in an aqueous solution with a current density of 25OA/rrr for 60 seconds. At this time, the silane coupling treated side of the copper foil was used as the cathode, and platinum was used as the counter electrode. (3) Creation of PCI: Pour the solution of the polyamide polyamic acid copolymer obtained in step (1) uniformly onto the surface-treated surface of the electrolytic copper foil obtained in step (2). Spread and apply at +50'c for 20
After heating and drying for 1 minute, dry in a nitrogen atmosphere at 200°C for 10 minutes.
A flexible substrate was obtained by heating for a minute. The thickness of the polyamide-polyimide copolymer layer of the flexible substrate thus obtained was 30 μm.

The peel strength between the polyamide-imide layer and the surface treatment layer of this flexible substrate is l. It was OKG/CIA. Comparative Example: 3 A flexible substrate was obtained by carrying out the same operation as in Example 1, except that in Example 3, an electrolytic copper foil not subjected to silane coupling treatment was used as the defoil.

The thickness of the polyimide layer of the flexible substrate thus obtained was 30 μm. The peel strength between the polyamide-imide layer and the surface treatment layer of this flexible substrate was 0.5 kg/cd.

[Effects of the Invention] As described above, as proposed by the present invention, after the surface of the copper foil layer is subjected to silane casing treatment, an elemental metal, its oxide, alloy, etc. is formed, and then heat-resistant The FCL formed with the polymer has significantly increased adhesive strength between the heat-resistant polymer film and the copper foil. Since such FCL does not have an adhesive layer, it has good heat resistance, and due to the effect of the surface treatment layer, it also has good adhesion and heat deterioration resistance.

According to the present invention, a flexible substrate with excellent characteristics can be provided.

Claims (3)

[Claims] 1. A flexible copper-clad laminate having a heat-resistant polymer film layer and a copper foil layer on at least one of the heat-resistant polymer film layers, wherein the copper foil layer has the heat resistance of at least one of the copper foil layers. A flexible copper-clad laminate in which a metal, its oxide, or its alloy is fixed after a silane coupling agent is formed on the surface in contact with the polymer. 2. Silane coupling agents are amino-based, epoxy-based,
The flexible copper-clad laminate according to claim 1, wherein the flexible copper-clad laminate is one or more selected from mercapto type. 3. An elemental metal, its oxide, or its alloy is copper,
The flexible copper-clad laminate according to claim 1, which is one or more selected from zinc, nickel, chromium, oxides thereof, or alloys thereof.