JPH0634433B2 - Metal-clad laminate for printed wiring - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to printing in which a thin plate such as an aromatic polymer film or sheet in which a metal oxide is uniformly dispersed and blended and a metal foil are laminated. The present invention relates to a metal-clad laminate for wiring.

[Prior Art] Conventionally used as an insulating material for a flexible printed circuit board as a printed wiring board in an electronic component, a film carrier tape for mounting a semiconductor laminated circuit, or various electric motors, transformers, and generators in electric equipment. Polyimide film, aromatic polyamide paper, polyester film, epoxy resin-impregnated glass cloth, etc. are used for the insulator.

In particular, since the polyimide film is excellent in heat resistance and mechanical strength, it is widely used as an insulating film for a metal foil-clad laminated film in a printed wiring board.

However, in general, organic polymers have a drawback that they have a large coefficient of thermal expansion as compared with inorganic substances, and aromatic polyimide polymers are no exception, therefore, for example, in use as a flexible printed circuit board,
When bonding a metal foil to a polyimide film, it is necessary to provide an adhesive layer made of another material between the polyimide film and the metal foil in order to prevent curling caused by the difference in thermal expansion coefficient. Since the material used for such an adhesive layer is generally inferior in heat resistance, there is a problem that the heat resistance of the polyimide fill cannot be fully utilized.

Therefore, many attempts have been made to improve the coefficient of thermal expansion of polyimide polymers, and polyimides having various structures have been proposed. For example, Japanese Unexamined Patent Publication No. 60-250031 discloses that it has a low expansion property. A polyimide using a diamine component selected from the above is disclosed, and its application to copper-clad laminates and the like is disclosed in JP-A-60-221.
It is disclosed in Japanese Patent No. 426. Another example is an attempt to improve dimensional stability by using an acid dianhydride, which is a constituent of polyimide, or a compound having a special structure as a diamine component.

However, as described above, the use of a compound having a special structure leaves problems such as difficulty in obtaining raw materials and toxicity.

[Problems to be Solved by the Invention] The present invention has been made in view of the above problems, and a metal oxide sol or a metal alkoxide that can be converted into a metal oxide by heat treatment and an easily available raw material. A metal-clad laminate obtained by laminating a thin plate such as a metal oxide-containing film or sheet obtained by subjecting a composition comprising a varnish of an aromatic polymer to a film and heat treatment to the metal foil is laminated. , Shows significantly higher heat resistance, mechanical strength, and dimensional stability than a laminate using a conventionally known aromatic polymer film or sheet,
It is possible to stack with metal foil without interposing an adhesive layer,
Therefore, the present invention has been completed with the knowledge that curling, which is a drawback of the prior art, does not occur.

An object of the present invention is to provide a novel metal-clad laminate for printed wiring, which does not require an adhesive layer when laminated with a metal foil and has excellent heat resistance, mechanical strength and dimensional stability. .

[Means for Solving Problems] That is, the present invention relates to a composition comprising a metal oxide sol or a metal alkoxide or a partial condensate thereof capable of becoming a metal oxide by heat treatment and a varnish of an aromatic polymer. The present invention provides a metal-clad laminate for printed wiring, in which a metal oxide-containing thin plate obtained by film-forming and heat treatment is laminated on a metal foil.

In the present invention, the aromatic varnish of the aromatic polymer is preferably a varnish of the aromatic polyimide polymer and its precursor, the aromatic poiamic acid polymer or the aromatic polysulfone polymer.

The aromatic polyimide-based polymer is specifically represented by the following general formula [I] (However, Ar ¹ is Chosen from; Ar ² is R is an alkyl group having 1 to 3 carbon atoms, an alkoxy group, or halogen; X is a single bond, -O-, -S-, -SO
_2- , It represents either an alcoalkylene group having 1 to 6 carbon atoms or a perfluoroalcoalkylene group; n represents an integer of 0 to 2. ) Is a polymer having a repeating unit represented by the formula: and is produced from a usual acid dianhydride and a diamine component. Preparation as a varnish is an organic solvent capable of dissolving the polymer, for example,
Prepared with N, N-dimethylacetamide.

On the other hand, an aromatic polysulfone-based polymer has the following general formula [II] as a basic skeleton. (However, Ar in the formula is R ^{1 to} R ⁷ represent hydrogen or a hydrocarbon group having 1 to 8 carbon atoms and may be the same or different; a to e are 0 to 4, f and g are integers of 0 to 3; They may be the same or different; X ¹ and X ² are single bonds, selected from -O-, -S-; Y is a single bond, -O-, -S-, -SO _2- , R is hydrogen or a hydrocarbon group having 1 to 6 carbon atoms. ) Is a homopolymer having the unit structure represented by the formula (1) and having the same repeating basic skeleton unit, or a copolymer having two or more types of basic units. Examples of the aromatic polysulfone-based polymer include polysulfone, polyether sulfone, polythioether sulfone and copolymers thereof. The manufacturing method thereof is disclosed in Japanese Patent Application Laid-Open No. Sho 61-61.
-72020. The organic solvent in the preparation as a varnish is not particularly limited as long as it can dissolve these polymers, but N-methyl-2-pyrrolidone and the like can be illustrated as a preferable example. (Hereinafter, the aromatic polyimide-based polymer and the polyamic acid-based polymer or the aromatic polysulfone-based polymer are collectively referred to as a polymer.) Metal oxide sol or metal alkoxide capable of forming a metal oxide by the heat treatment in the present invention Is required to be a metal oxide at a heat treatment temperature below the decomposition temperature of the polymer.

The metal alkoxide is preferably at least one selected from Si, Al, Sn, Ti and Zr. Specifically, Si alkoxides such as silicon tetraoxide, Al alkoxides such as aluminum triisopropoxide, Sn alkoxides such as tin tetrabutoxide, Ti alkoxides such as titanium tetraisopropoxide,
Examples thereof include Zr alkoxides such as zirconium tetrabutoxide. Precondensed partial condensates are also used. Further, metal alkoxides or partial condensates can be used alone or in combination.

(Hereinafter, unless otherwise specified as a partial condensate, the metal alkoxide includes a partial condensate.) Next, an aqueous or organic sol is used as the metal oxide sol in the present invention, for example, silica sol, alumina sol, Examples thereof include antimony oxide sol, iron oxide sol, zirconia sol, titania sol, and tin oxide sol. The aqueous metal oxide sol is a dispersion of water in metal oxide particles of colloidal size, the organic sol is organized by the hydrophobic treatment of the metal oxide surface, the dispersion medium is alcohol-based, for example Those made of methyl alcohol, ethyl alcohol, n-puyopyr alcohol, isopropyl alcohol, etc. are commercially available. In the present invention, an organic sol may be used in which the surface of the metal oxide is further subjected to a hydrophobic treatment to change the phase of the dispersion medium to another hydrophobic organic solvent, or a mixed solvent may be used.

The metal alkoxide and the metal oxide sol may be used in combination.

In the present invention, the metal oxide-containing thin plate to be laminated on the metal foil is a film or a sheet, and includes a thin plate.

The amount of the metal oxide contained in the thin plate is preferably 1 to 200 polymer parts per 100 parts by weight of the polymer,
Heat resistance and dimensional stability improve as the amount of metal oxide increases, but if it is too large, it tends to become brittle, and if it is too small, the effect is difficult to develop, and therefore, preferably 10 to 100 parts by weight. is there.

As a method of preparing a composition by blending a metal oxide with a polymer and forming a film, a method of directly blending a metal oxide in a powder form is known, but in such a method, It is difficult to completely convert the powder, which usually exists as secondary particles, into primary particles, and as a result, the particles themselves become defect points of the film, which lowers the strength of the film or makes it brittle. In some cases, it may be difficult to form a film by film formation.

The present invention is characterized in that a thin film such as a metal oxide-containing film or sheet is formed by heat treatment while forming a film of a composition in which a metal oxide sol or a metal alkoxide is mixed with a polymer varnish. The obtained thin plate body does not have the above-mentioned problems at all when it is used as a metal-clad laminate. In the case of a composition containing a metal alkoxide, the heat treatment with film formation causes the condensation to proceed to form a metal oxide, and as a result, a uniformly dispersed thin plate can be obtained. Here, the metal alkoxide may be stored as a partial condensate by adding water and a catalyst such as an acid or a base to hydrolyze the alkoxide to proceed with condensation.
In this case, it is sufficient if the amount of water added is equal to or more than the equivalent of the alcoholate contained in the metal alkoxide, but the degree of condensation by hydrolysis can be adjusted with an amount equal to or less than the equivalent of the alcoholate.

Regarding the metal oxide sol, since the metal oxide particles have already been formed, basically the metal oxide is uniformly dispersed by the drying step when forming the composition formed into the polymer varnish into a film. The obtained thin plate body is obtained.

The metal oxide sol or metal alkoxide used in the present invention can be used particularly without any other treatment, but in the preparation of the composition by blending the polymer into the varnish, the purpose of improving the miscibility and dispersibility A suitable solvate may be added. Further, a silane coupling agent may be added in order to improve the mixing property, and the silane coupling agent in this case is not only a dispersion improver of the substance dispersed with the polymer but also an action as a dispersion stabilizer. ,
By selecting one having an appropriate functional group, it becomes possible to bind to the functional group of the polymer, and the physical properties of the obtained thin plate can be remarkably improved. Examples of such silane coupling agents that can be used include alkyl-based silane coupling agents such as methyltrimethoxysilane, halogen-based silane coupling agents such as γ-chloropropyltrimethoxysilane, and vinyl-based silane coupling agents such as vinyltriethoxysilane. Silane coupling agent,
Methacrylic silane coupling agents such as γ-methacryloxypropyltrimethoxysilane, epoxy silane coupling agents such as γ-glycidoxypropyltrimethoxysilane, mercaptosilane coupling agents different from γ-mercaptopropyltriethoxysilane. , Hydroxy-type silane coupling agents such as γ- (diethanolamine) propyltriethoxysilane, isocyanate-type silane coupling agents such as γ-isocyanatopropyltrimethoxysilane, amine-type silane coupling agents such as γ-aminopropyltrimethoxysilane Examples thereof include agents or their salt types, and these may be used alone or in combination of two or more kinds. Such a silane coupling agent may be simply added and mixed at the time of compounding a metal or metal oxide sol with a polymer, or at the time of film formation, but the polymer has a functional group and some interaction with the silane coupling agent or When bond formation is expected, it is also effective to preliminarily mix with the polymer or perform pretreatment such as heating. In addition, titanate-based coupling agents and aluminum-based coupling agents can be used depending on the properties required of the metal oxide. It is also effective to use a chelating agent or a complexing agent such as acetylacetone for the purpose of stabilizing the metal alkoxide or the composition and preparing the reaction.

A composition comprising a metal alkoxide or a metal oxide sol and a polymer varnish is formed into a film and subjected to heat treatment to cause polycondensation to proceed to form a thin plate, which is then formed into a metal oxide-containing thin plate. , The heating temperature in this case is 50
It is between ℃ and 500 ℃. If the heating temperature is too low, the removal of the solvent will be insufficient, and the contribution of heating to the above reaction will be small, and if it is too high, thermal decomposition will occur. Therefore,
It is preferably 100 ° C to 400 ° C. The physical properties of the thin plate obtained by such treatment can be further improved by performing post-treatments such as stretching and curing treatment.
Further, it is also possible to impregnate a liquid composition with glass cloth, carbon fiber, aramid cloth, glass paper, carbon paper, aramid paper or the like, or to disperse a fibrous material to form a thin plate excellent in heat resistance. it can. The coefficient of thermal expansion of the obtained thin plate body can be made close to that of the metal foil to be laminated by adjusting the amount of metal oxide contained.

In order to form a metal-clad laminate by laminating the metallization-containing thin plate obtained as described above to a metal foil, a method utilizing the step of thinning the film by the above film formation and the obtained thin plate and metal Two methods of heat-sealing the foil are adopted. That is, a metal oxide sol or a composition comprising a metal alkoxide and a polymer varnish is directly processed on a metal foil to form a film, and a metal oxide is formed by thinning the metal foil according to the above heat treatment method. A method for forming a metal-clad laminate in which thin sheet bodies are laminated.

The composition comprising a metal oxide sol or metal alkoxide and a polymer varnish is formed into a film and the metal oxide-containing thin plate and the metal foil obtained by thinning the composition according to the heat treatment method are heated. A method of forming a metal-clad laminate by fusing.

A good metal-clad laminate can be obtained by any of the above methods. Here, if it is a thermoplastic type as the metal oxide-containing film, it is desirable that the temperature is the above-mentioned temperature with respect to the heating temperature at the time of film formation, but if it is a thermosetting type, it is adjusted so that curing does not proceed too much. It is also possible to make it into a thin plate by the above-mentioned state, so-called B-stage, and to completely cure the metal oxide-containing film obtained by laminating it with the metal foil at the time of lamination. A heating press for lamination by heat fusion in the above method,
The use of a laminating device such as a roll laminator is preferred. In addition to heat fusion, it can be laminated with an adhesive, but since the coefficient of thermal expansion of the metal oxide-containing thin plate body is as small as that of the metal foil, the metal foil can be simply heat fused without using an adhesive. It is preferable that the metal-clad laminate is laminated with the metal-clad laminate without curling or warping.

[Action] The action mechanism of the metal-clad laminate obtained by laminating a thin plate such as a metal oxide-containing film or sheet of the present invention on a metal foil has excellent heat resistance and dimensional stability, but is not always clear. When the metal oxide is mixed with the polymer varnish in the metal oxide sol or the metal alkoxide, the metal oxide is uniformly mixed and dispersed, and further, the polycondensation proceeds by heat treatment with film formation. It is assumed that the metal oxide causes some interaction with the functional group of the polymer or a chemical bond is formed. Further, it is possible to make the contained metal oxide a large amount, and by adjusting the amount, the coefficient of thermal expansion of the metal oxide-containing thin plate can be made approximately the same as that of the metal foil. It is considered that the metal-clad laminate by lamination can be a laminate without curling or warping.

[Examples] The present invention will be described in more detail with reference to Examples.
Needless to say, the present invention is not limited to only the embodiments.

Preparation Example 1 Preparation of Silicon Tetraethoxide Solution In a reactor equipped with a stirrer and a dropping funnel, 80 g of N, N-dimethylacetamide and 69.4 g of silicon tetraethoxide (manufactured by Tokyo Chemical Industry Co., Ltd.) were charged and stirred vigorously. ρ
-Toluenesulfonic acid (0.69 g) and water (24.0 g) are added dropwise at room temperature over 30 minutes, and the mixture is stirred for a whole day and night to give a transparent and homogeneous solution of silicon tetraethoxide (SiO ₂ concentration 11.5%). Prepared.

Preparation Example 2 Preparation of titanium tetraisopropoxide solution N, N-dimethylacetamide was placed in a reactor equipped with a stirrer.
56g and titanium tetra-isoproxide (product of Nippon Soda Co., Ltd.)
Charge 71.4g and stir vigorously to acetylacetone 2
5.1 g of water and 4.5 g of water were added at room temperature, and the mixture was stirred for a whole day and night, and a transparent and uniform solution of titanium tetraisopropoxide (TiO ₂
A converted concentration of 12.8%) was prepared.

Preparation Example 3 Preparation of silica sol N-methyl was placed in a reactor equipped with a stirrer and a dropping funnel.
-2-Prepare 100 g of pyrrolidone and, with vigorous stirring,
83 g of 30% silica methonol sol (“OSCAL-1132”, manufactured by Catalysis & Chemical Industry Co., Ltd.) was added dropwise at room temperature over 10 minutes, and then heated to distill off the methanol content of the sol to give a transparent, uniform 20% N-methyl silica. -2-Pyrrolidone sol was prepared.

Preparation Example 4 Preparation of polyamic acid varnish In a reactor equipped with a stirrer, a dropping funnel and a reflux condenser.
Charge 4,4'-diaminodiphenyl ether (20.02 g) and N, N-dimethylacetamide (213 g), and add pyromellitic dianhydride (21.81 g) over 2 hours while maintaining the temperature at 10 ° C or lower with vigorous stirring through nitrogen gas. did. Then, the reaction temperature was set to room temperature, and the solution in which pyromellitic dianhydride was completely dissolved was further stirred at room temperature for 6 hours to obtain a varnish of polyamic acid. The logarithmic viscosity (ηinh) of this varnish of polyamic acid was 1.86 dl / g (0.5 g / N, concentration of 100 ml of N-dimethylacetamide, measured at 30 ° C., the same applies hereinafter).

Preparation Example 5 Preparation of aromatic poisulfone polymer varnish 4,4-dichlorodiphenylsulfone, bisphenol A,
Further, 4,4'-dichlorophenyl sulfone and sodium sulfate were added to a precursor obtained by reacting potassium carbonate with each other and reacted to obtain an aromatic polythioether sulfone polymer represented by the following formula. (For details, see
See JP 61-72020. ) Logarithmic viscosity (η-inh) is 0.65 (0.5g / phenol: 1,1,2,
2-tetrachloroethylene = 3: 2 weight ratio, concentration of 100 ml, measured at 30 ° C.) 20 g of this polymer and 0.5 g of hexamethoxymethylmelamine
It was dissolved in 80 g of N-methyl-2-pyrrolidone and the insoluble material was removed by filtration to prepare a varnish.

Example 1 100 g of the polyamic acid varnish obtained in Preparation Example 4 was placed in a reactor equipped with a stirrer, a dropping funnel, and a reflux condenser.
, While maintaining vigorous stirring at room temperature,
Silicon tetraethoxide solution prepared in Preparation Example 1 3
6 g was added dropwise over about 30 minutes to obtain a brown transparent viscous liquid composition.

Next, the obtained viscous liquid composition was applied to a rolled copper foil having a thickness of 35 μm and dried in a nitrogen gas atmosphere at 100 g for 1 hour, and then the copper foil was fixed with a fixing frame. By heating at 200 ° C. for 2 hours and at 350 ° C. for 2 hours, a metal-clad laminate for flexible printed wiring having a coating film thickness of 30 μm was obtained. No curling occurred even when this laminated plate was removed from the fixed frame, and no swelling or curling was observed even after holding at 350 ° C. for 30 seconds as a solder heat resistance test.

Example 2 In a reactor similar to that of Example 1, 100 g of the polyamic acid varnish obtained in Preparation Example 4 was charged, and 0.16 g of 3-aminopropyltriethoxysilane was added at room temperature with vigorous stirring.
Was added and stirred at room temperature, and then a solution prepared by mixing 22 g of the silicon tetraethoxide solution prepared in Preparation Example 1 and 11.5 g of the titanium tetraisopropoxide solution prepared in Preparation Example 2 was added. It was added dropwise over 30 minutes to obtain a brown transparent viscous liquid composition.

Next, this viscous liquid was applied onto a copper foil, dried and heated in the same manner as in Example 1 to obtain a metal-clad laminate for flexible printed wiring laminated with the copper foil.

This laminated plate did not curl even after it was removed from the fixed frame, and no swelling or curling was observed even at 350 ° C. for 30 seconds in the solder heat resistance test.

Example 3 100 g of the aromatic polysulfone-based polymer varnish obtained in Preparation Example 5 was charged in the same reactor as in Example 1, and 116 g of the silicon tetraethoxy solution prepared in Preparation Example 1 was prepared with a heart sound while vigorously stirring. Was added dropwise over about 1 hour to obtain a composition composed of a translucent viscous liquid.

This viscous liquid is cast on a glass plate and kept at 100 ° C for 1 hour.
After heat treatment at 200 ° C. for 2 hours, the coating film formed on the glass plate was peeled off to obtain a film having a thickness of 30 μm. This film is laid on a rolled copper foil with a thickness of 35 μm, 28 ℃, 40k
It was pressed for 1 hour under the condition of g / cm ² to obtain a metal-clad laminate for flexible printed wiring. This laminated plate did not curl, and no swelling or curling was observed even at 350 ° C. for 30 seconds in the solder heat resistance test.

Example 4 N- of a commercially available aromatic polysulfone (“Udelp-1700”: manufactured by Union Carbide Co.) was placed in the same reactor as in Example 1.
100 g of 20% methyl-2-pyrrolidone solution was charged, and 10 g of silicasol prepared in Preparation Example 3 was dripped at room temperature with vigorous stirring for about 10 minutes to give a colorless transparent viscous liquid. A composition was obtained.

Next, 100 g / m ² of glass cloth was immersed in this viscous liquid, then pulled up and dried at 180 ° C for 15 minutes to obtain a resin content of
Produced 70% prepreg, followed by this prepreg 8
A rolled copper foil with a thickness of 35 μm is sandwiched between the top and bottom, and it is 40
It was pressed for 30 minutes under the condition of kg / cm ² to obtain a metal-clad laminate for rigid printed wiring. In the solder heat resistance test, this laminated plate did not show any swelling or curling even at 350 ° C. for 30 seconds.

Comparative Example 1 Only the polyamic acid varnish obtained in Preparation Example 4 was applied onto a copper foil in the same manner as in Example 1 and dried to prepare a metal-clad laminate for flexible printed wiring. However, this laminated plate curled after being removed from the fixed frame after the heat treatment. When this laminated plate was rewound in the opposite direction to remove the curl and made into a flat plate and subjected to a solder heat resistance test, it curled again at 350 ° C. for 30 seconds.

Comparative Example 2 100 g / m ² of glass cloth was immersed in the commercially available aromatic polysulfone varnish used in Example 4, and a metal-clad laminate for rigid printed wiring was obtained by the same method as in Example 4. This laminate was tested at
I swelled in seconds.

[Effects of the Invention] The metal-clad laminate for wiring for printing of the present invention comprises a metal foil,
It is characterized in that thin films such as polymer films or sheets containing a large amount of metal oxides are directly laminated. Therefore, since the metal foil and the thin plate are not laminated via the adhesive layer, it is recognized that the heat resistance and the dimensional stability are extremely good as compared with the conventional laminated plate.

Claims (5)

[Claims] 1. A metal obtained by heat-treating a composition comprising a metal oxide sol or metal alkoxide or a partial condensate thereof and a varnish of an aromatic polymer capable of forming a metal oxide by heat treatment and heat-treating. A metal-clad laminate for printed wiring, comprising an oxide-containing thin plate laminated on a metal foil. 2. The metal-clad laminate according to claim 1, wherein the varnish of the aromatic polymer is a varnish of the aromatic polyimide polymer or a varnish of the aromatic polyamic acid polymer which is a precursor thereof. Board. 3. The metal-clad laminate according to claim 1, wherein the aromatic polymer varnish is an aromatic polysulfone polymer varnish. 4. A metal-clad laminate is formed by forming a composition comprising a metal oxide sol, a metal alkoxide or a partial condensate thereof and a varnish of an aromatic polymer on a metal foil and heat-treating the composition to form a laminate. A metal-clad laminate according to claim 1. 5. The metal-clad laminate according to claim 1, wherein the metal-clad laminate is obtained by heat-sealing a metal oxide-containing thin plate member to a metal foil.