JPH0719939B2 - Flexible double-sided metal foil laminate - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention provides a novel flexible double-sided film having a low solvent content in a plastic film, high adhesive strength, and excellent heat resistance, mechanical properties and electrical properties. Metal foil laminate (Fl
exible Metal Double Clad Laminate (hereinafter abbreviated as double-sided FMCL) and is used for flexible printed circuit boards, electromagnetic wave shielding films, packaging materials, etc.

[Conventional technology]

The double-sided FMCL is used as a material for comprehensively utilizing the characteristics of both metal and plastic, such as a flexible printed circuit board, an electromagnetic wave shielding film, and a packaging material.

Such a double-sided FMCL has hitherto been disclosed in, for example, JP-A-51-13617.
3, as disclosed in the same 55-91895, 62-183592,
After sticking the plastic film and metal foil with an adhesive or an adhesive sheet, also stick the metal foil on the opposite side of the plastic film with an adhesive or an adhesive sheet, or between the metal foil coated with the adhesive It is manufactured by sandwiching a film, or by sandwiching an adhesive sheet between a metal foil and a plastic film and laminating it, and an acrylic or epoxy-based low heat resistant adhesive layer may be present. It is a feature.

However, in recent years, even in the double-sided FMCL, thinning, weight reduction,
There is an increasing demand for higher performance and higher productivity by improving heat resistance.

In particular, for flexible printed circuit boards, circuit densification, surface mounting methods involving wire bonding, product miniaturization, and high productivity are being promoted. It is earnestly desired to provide double-sided FMCL with excellent mechanical and electrical characteristics.

However, the above-mentioned conventional double-sided FMCL has an essentially unnecessary adhesive layer, and since the adhesive layer is usually an acrylic or epoxy adhesive, the adhesive strength at high temperature and heat deterioration resistance etc. So-called low heat resistance cannot withstand high-temperature solder, electrical insulation characteristics deteriorate under high-temperature use conditions, and further adhesive strength decreases, causing problems in practical use.

The problem of the laminated board with such an adhesive layer is that a normal single-sided type flexible metal foil laminated board (FMCL = Flexible Metal C
lad laminate), it is a single-sided type.
In FMCL, for example, as shown in JP-A-52-35281 and JP-A-56-23791, heat-resistant plastic varnish is cast-coated on a metal foil using a T-die or various coaters, and dried. There has been proposed a method for producing a single-sided FMCL in which an adhesive layer is not interposed by a so-called casting method of solidifying.

The manufacturing method of these single-sided FMCL is simple,
Moreover, it is a single-sided type obtained because no adhesive layer is provided.
The FMCL properties are directly reflected in the plastic properties, and the adhesive strength with the metal foil hardly decreases even at high temperatures, which has the advantage of excellent heat resistance. ing.

However, in the double-sided FMCL, the above casting method used in the single-sided FMCL is unsuitable due to its laminated structure.

For this reason, two single-sided FMCLs that have a plastic film directly formed on the metal foil by the casting method are made to face each other with the plastic surface facing each other, and the double-sided FMCL does not include an adhesive layer. A method for producing a is proposed in JP-A-56-139953.

However, in this method, since 5% to 50% of the volatile content is contained in the plastic film, voids are generated in the solder bath at 260 ° C or higher, or after the product is used at high temperature of 200 ° C or higher. Problems occur in practical use due to the formation of parts or the deformation caused by shrinkage of the plastic film.

[Problems to be Solved by the Invention]

The object of the present invention is that two metal foils are directly fixed on both sides of a plastic film without interposing an adhesive, the solvent content in the plastic film is low, the adhesive strength is high, the heat resistance and the mechanical strength are high. It is to provide a double-sided FMCL having excellent characteristics and electrical characteristics.

[Means for solving problems]

To create a high-performance double-sided FMCL with excellent heat resistance, mechanical properties, and electrical properties, various properties of the plastic film, the amount of solvent remaining in the plastic film,
The inventors have speculated that the plastic film and the metal foil need to be optimized, and as a result of repeating the trial manufacture and the test, (a) the plastic film and the metal foil are directly connected without interposing an adhesive layer. Be adhered to.

(B) 90 degree peel strength of plastic film and metal foil is 0.7-22kgf / cm at room temperature and 0.4-20kgf / cm at 200 ℃.
To be.

(C) Solvent content in plastic is 1 by weight
~ 0.01%.

(D) The solder heat resistance of the double-sided FMCL shall not show any change in shape when immersed in a bath at 300 ° C for 30 seconds.

The inventors have found that it is necessary to satisfy all of the above conditions (a) to (d), and have confirmed this, and have completed the present invention.

That is, the double-sided FMCL of the present invention is such that the plastic film and the metal foil are directly fixed to each other without the interposition of an adhesive layer, so that the heat resistance is lowered due to the interposition of the adhesive layer, the mechanical performance is lowered, It is possible to avoid deterioration of electrical characteristics.

Further, in the double-sided FMCL of the present invention, the 90 degree peel strength between the plastic film metal foil is 0.7 kgf / cm at room temperature.
It is possible to have excellent adhesive strength, heat resistance, and mechanical properties by being 0.4 kgf / cm or more at 200 ° C., but a low peel strength of less than this is possible. In the case of holding, peeling occurs between the plastic film and the metal foil during processing, and it is not possible to obtain a satisfactory high performance double-sided FMCL.

Further, in the double-sided FMCL of the present invention, the solvent content in the plastic film is 1 to 0.01%, preferably 0.1% or less, more preferably 0.02% or less, thereby the adhesion at high temperature between the plastic film and the metal foil. The strength of the plastic film did not decrease, and the dimensional change of the plastic film was small, and it possessed good heat resistance. If the solvent content exceeds 1%, expansion due to the vapor pressure of the solvent when used at high temperatures, dimensional changes due to evaporation of the solvent, decrease in adhesive strength, etc. will result in heat-resistant double-sided FMCL. In particular, it cannot be used as a printed circuit board requiring heat resistance.

Furthermore, when immersed in a bath with a soldering heat resistance of 300 ° C for 30 seconds, no change in shape is observed, which allows general-purpose soldering processes for high-density circuits and high-speed soldering processes. Excellent double-sided FMCL has emerged.

As a result of further studies, the inventors have found that the plastic film as the base material has a tensile elastic modulus at room temperature of 100 to 800 kgf / mm ² and an elongation of 30 in accordance with the above conditions. ~ 200%.

(F) A dielectric constant of 3.0 to 3.5 at 1 KHz.

(G) It consists of a network plastic having a glass transition temperature of 280 to 390 ° C and / or a linear plastic having a glass transition temperature of 150 to 260 ° C.

It was also found that, when the condition of (2) is satisfied, the double-sided FMCL is further improved in heat resistance, mechanical properties and electrical properties and has high performance, and the present invention has been completed.

That is, the tensile elastic modulus of the plastic film as the base material is 100 to 800 kgf / mm ² , and the elongation percentage is 30 to 200%, whereby it is possible to exhibit excellent mechanical properties as a double-sided FMCL. , The tensile modulus is less than 100kgf / mm ² ,
Alternatively, if the elongation exceeds 200%, it is too soft for the double-sided FMCL and the tensile modulus is 800 kgf / m.
If it is larger than m ² or if the elongation is smaller than 30%, it is too hard to be a double-sided FMCL having excellent mechanical properties in any case.

Also, since the dielectric constant of the plastic film is 3.5 or less at 1 KHz, it is possible to show excellent electrical properties as a double-sided FMCL, but if this value is exceeded, the electrical properties as a double-sided FMCL will be It is defective, especially when used as a high-density printed circuit board,
Problems such as a decrease in signal transmission speed occur.

Furthermore, the double-sided FMCL of the present invention has a glass transition temperature of 280 ° C.
As it is made of reticulated plastic and / or linear plastic with a glass transition temperature of 150 ° C or higher, it can be used continuously at high temperature, or high temperature solder can be used. It shows excellent heat resistance, but if it is below these specified temperatures, the heat resistance of the base material itself is low, so both sides with excellent heat resistance
It cannot be FMCL.

As a result of extensive studies to satisfy the conditions (a) to (g), Japanese Patent Application No. 61-6
(1) a symmetrical aromatic meta-substituted primary diamine and a symmetric aromatic para-substituted primary diamine, in an equivalence ratio of 0-100: 100.
A polyimide produced by reacting with an aromatic tetracarboxylic acid anhydride after the substance contained within the range of 0 to (2), (2) symmetric aromatic meta-substituted primary diamine and aromatic tetracarboxylic acid An equivalent ratio of polyamic acid (A) produced by reacting an acid anhydride with polyamic acid (B) produced by reacting a symmetric aromatic para-substituted primary diamine and an aromatic tetracarboxylic acid anhydride After the substances contained in the range of 0 to 100: 100 to 0 are prepared, polyimide, which is produced by further progress of the reaction in the preparation, is suitable. (3) Steam (1) And in (2), the symmetric aromatic meta-substituted primary diamine has the following formula (However, X in the above formula is O, SO ₂ , CO, CH ₂ , C (CH ₃ ) ₂ , C
(CF ₃ ) ₂ or Direct connection is displayed. ) Is particularly suitable, but is not particularly limited to these, adhesiveness between plastic and metal foil, solvent content, tensile modulus, elongation, dielectric constant, and glass transition temperature is Anything within the above range may be used.

The thickness of the plastic film is preferably 5-100 μm
It is in the range of 10 to 50 μm, and more preferably in the range of 10 to 50 μm.

The metal foil is preferably made of copper, aluminum, gold, silver, nickel, alloys containing these, or other alloys, and particularly preferably metal foil made of copper and / or aluminum.

The thickness of the metal foil is preferably in the range of about 5 to 100 μm.

In order to increase the bonding surface area, the metal foil surface to which the plastic film is directly bonded is attached with particles by electroplating generally used in the surface treatment of copper foil, or subjected to AC etching, or AC It is preferable to apply etching or the like to increase the adhesive force, and the adhesive force may be enhanced by a silane coupling treatment or a titanate coupling treatment suitable for the organic polymer.

Further, the adhesive strength may be improved by performing a surface treatment with a monomer containing —SH group, which has a high bonding property with zinc, which is widely used as a rust preventive agent for copper foil, or a polymer.

The present invention can be embodied by, for example, the following methods, but is not limited thereto.

a. (1) Titanium varnish with polyamic acid on metal foil,
Alternatively, an emma coater or the like is used for casting and coating, followed by heating and drying to reduce the solvent content to 1% or less and to convert the polyamic acid into a network polyimide.

(2) A polyamic acid varnish, which is a precursor of linear polyimide, is cast-coated on another metal foil in the same manner, and then dried by heating to reduce the solvent content to 1% or less and to linearize polyamic acid. Convert to polyimide.

(3) As shown in FIG. 1, the polyimide surfaces of the laminating materials obtained in (1) and (2) above are superposed and laminated, and heated and pressed to integrate the polyimides.

Alternatively, b. (4) Cast a polyamic acid varnish, which is a precursor of mesh polyimide, onto a metal foil, and heat it to an intermediate state between touch drying and conversion to mesh polyimide. .

(5) A polyamic acid varnish that is a linear polyimide precursor is cast-coated on the polyamic acid varnish surface of the laminating material obtained in (4) above, and then heat-dried to reduce the solvent content to 1% or less. Convert polyamic acid to linear polyimide.

(6) As shown in FIG. 2, the metal foil is laminated on the polyimide surface of the laminating material obtained in the above (5) and laminated by heating and pressing to integrate the metal foil.

Alternatively, c. As shown in FIG. 3, the laminating material obtained in (1) above and the laminating material polyimide surface obtained in (5) are superposed and heated and pressed to integrate the polyimide. Let

Further, for example, d. The laminating materials of (5) above are integrated.

e. The above-mentioned lamination material (2) and the metal foil are integrated.

f. The laminating materials described in (2) above are integrated.

It can also be embodied by methods such as.

In the above production method, the coating thickness of each polyamic acid varnish is optional as long as the thickness of the integrated film after drying and curing is preferably in the range of 5 to 100 μm, more preferably 10 to 50 μm. However, it is preferable that the linear polyimide is applied so as to have a thickness of half or less of the film thickness.

The network polyimide is preferably one having an equivalent ratio of the symmetrical aromatic meta-substituted primary diamine and the symmetrical aromatic para-substituted primary diamine in the range of 0 to 50: 100 to 50, As the linear polyimide, the equivalent ratio is 100 to 9
It is preferably 0: 0 to 10.

The heating temperature can be changed by various conditions, but is usually about
It is in the range of 100 to 400 ° C, preferably 150 to 350 ° C.

Pressure is usually 0.1 to 200 kgf / cm ² , preferably 10 to 100 kg
f / cm ² .

[Action and effect]

The double-sided FMCL of this invention is excellent in heat resistance, mechanical and electrical performance, and has high durability and reliability even in a high temperature atmosphere in many applications such as flat cables, electromagnetic shielding materials, and packaging materials. It is possible to use it by nature.

In particular, when the double-sided FMCL of the present invention is used as a substrate for a flexible printed circuit, it can withstand through-hole processing by laser beam or high-temperature solder stably, thus improving productivity and increasing the circuit density. It is possible to obtain a flexible printed circuit that has excellent heat resistance, electrical and mechanical properties, because surface mounting density is high and wire bond processability and reliability can be improved. Therefore, the range of applications is greatly expanded.

Hereinafter, the present invention and its effects will be specifically described by showing Examples and Comparative Examples of the present invention.

In the examples and comparative examples, (1) 90 degree peel strength measurement conforms to IPC-FC-241A, (2) Solder heat resistance measurement conforms to JIS C-6481, abnormal shape such as expansion wavy deformation It was judged by the presence or absence of.

Example 1 (a) In a container equipped with a stirrer, a reflux condenser and a nitrogen introducing tube, 221 g (0.60 mol) of 4,4′-bis (3-aminophenoxy) biphenyl and 4,4′-diamino were added. 280 g (1.4 mol) of diphenyl ether was dissolved in 3500 ml of N, N-dimethylacetamide and cooled to around 0 ° C, and under this nitrogen atmosphere, 436 g (2.0 mol) of pyromellitic dianhydride.
Was added, and the mixture was reacted at 0 ° C. for 2 hours with stirring.

Next, the solution was raised to room temperature and stirred under a nitrogen atmosphere for about 20 hours.

The polyamic acid solution thus obtained had an inherent viscosity of 1.7d.
It was l / g.

This polyamic acid solution was diluted with N, N-dimethylacetamide to a concentration of 19%.

The solution (a) was uniformly cast-coated on a commercially available rolled copper foil having a thickness of 35 μm, heated at 130 ° C. for 5 minutes, and further heated at 160 ° C. for 5 minutes to be dried, and then the oxygen concentration was 0.5. % In a nitrogen atmosphere at 330 ° C. for 20 minutes to obtain a laminate material (a) in which a polyimide having a film thickness of 20 μm was directly adhered to a copper foil.

The glass transition temperature of the plastic film obtained by etching the entire copper foil of the laminating material (a) was 340 ° C.

The solvent content was 0.02%.

(B) In a container equipped with a stirrer, a reflux condenser and a nitrogen inlet tube, 737 g (2 mol) of 4,4′-bis (3-aminophenoxy) biphenyl was dissolved in 3500 ml of N, N-dimethylacetamide. The mixture was cooled to about 0 ° C., 436 g (2.0 mol) of pyromellitic dianhydride was added under a nitrogen atmosphere, and the mixture was stirred at about 0 ° C. for 2 hours.

Next, the solution was raised to room temperature and stirred under a nitrogen atmosphere for about 20 hours.

The polyamic acid solution thus obtained had an inherent viscosity of 1.5 dl /
It was g. This polyamic acid solution was diluted with N, N-dimethylacetamide to a concentration of 19%. This solution (b) was uniformly cast-coated on a commercial rolled copper foil having a thickness of 35 μm.
After heating at 0 ° C for 5 minutes and further heating at 160 ° C for 5 minutes and drying, it is heated in a nitrogen atmosphere at 330 ° C with an oxygen concentration of 0.5% for 20 minutes to form a linear film with a thickness of 20 μm on the copper foil. A laminate material (b) in which the polyimide was directly adhered was obtained.

The glass transition temperature of the plastic film obtained by completely etching the copper foil of the laminating material (b) was 260 ° C.

The solvent content was 0.01%.

The laminated materials of (a) and (b) were faced to each other with their polyimide surfaces facing each other and subjected to a press treatment of 50 kgf / cm ² at 290 ° C. for 20 minutes to obtain a double-sided FMCL.

The 90-degree peel strength of this double-sided FMCL copper foil plastic film is 1.7 kgf / c at room temperature on the laminating material (a) side.
m, 1.5 kgf / cm at 200 ° C, on the laminating material (b) side,
It was 22 kgf / cm at room temperature and 20 kgf / cm at 200 ° C.

The plastic film obtained by completely etching the copper foil of this double-sided FMCL has a tensile modulus of elasticity of 250 kg / mm at room temperature.
^{2. The} tensile elongation was 135% and the dielectric constant was 3.0 at 1KHz.

A printed circuit was formed on the copper foil surface of this double-sided FMCL by a photo-etching method, plated with through holes, and floated in a solder bath at 300 ° C for 30 seconds. There were no state change phenomena such as wavy deformation, delamination, voids and blister formation.

The laminate was left in a constant temperature bath at 200 ° C for 240 hours.
There was no occurrence of defects such as wavy deformation, delamination and blisters.

In other words, the double-sided FMCL of the present invention can withstand high-temperature solder, improve its productivity, and has high adhesive strength at high temperatures, so circuit densification and surface mounting method involving wire bonding can be adopted. In addition, the small heat deterioration property enables long-term use at high temperature.

Example 2 (c) In a container equipped with a stirrer, a reflux condenser and a nitrogen introducing tube, 73 g (0.60 mol) of 4,4'-bis (3-aminophenoxy) biphenyl and 4,4'-diamino were added. Dissolve 360 g (1.8 mol) of diphenyl ether in 3500 ml of N, N-dimethylacetamide, cool to around 0 ° C., and add 436 g (2.0 mol) of pyromellitic dianhydride to this under a nitrogen atmosphere and add 0 ° C. It was stirred for 2 hours in the vicinity. Next, the solution was raised to room temperature and stirred under a nitrogen atmosphere for about 20 hours.

The polyamic acid solution thus obtained had an inherent viscosity of 1.6 dl /
It was g.

This polyamic acid solution was diluted with N, N-dimethylacetamide to a concentration of 19%.

This solution (c) was uniformly cast-coated on a commercially available rolled copper foil having a thickness of 35 μm, heated at 130 ° C. for 5 minutes, and further heated at 160 ° C. for 5 minutes to be dried, and then 330 with an oxygen concentration of 0.5%. The laminate was heated in a nitrogen atmosphere at 0 ° C. for 10 minutes to obtain a lamination material (c) in which a polyimide having a film thickness of 20 μm was directly adhered to a copper foil.

The glass transition temperature of the plastic film obtained by etching the entire copper foil of the laminating material (C) was 390 ° C.

The solvent content was 0.4%.

(D) In a container equipped with a stirrer, a reflux condenser and a nitrogen inlet tube, 584 g (2.0 mol) of 1,3-bis (3-aminophenoxy) benzene and 3700 ml of N, N-dimethylacetamide.
, And put it in a nitrogen atmosphere at room temperature under the conditions of 3, 3 ', 4, 4'
-Benzophenone tetracarboxylic acid dianhydride 644 g (2.0
Mol) was added in four portions while paying attention to the rise in solution temperature, and the mixture was reacted at room temperature for about 24 hours.

The polyamic acid solution thus obtained had an inherent viscosity of 1.2 dl /
It was g.

This polyamic acid solution was diluted with N, N-dimethylacetamide to a concentration of 21%.

This (d) solution was uniformly cast-coated on a commercially available rolled copper foil having a thickness of 35 μm, heated at 130 ° C. for 5 minutes, further heated at 160 ° C. for 5 minutes and dried, and then the oxygen concentration was 3%. Heated in a nitrogen atmosphere at 250 ℃ for 30 minutes to obtain a film thickness of 10μ on the copper foil.
A layering material (d) to which the linear polyimide of m was directly adhered was obtained.

The glass transition temperature of the plastic film obtained by completely etching the copper foil of the laminating material (d) was 260 ° C.

The solvent content was 0.3%.

The polyimide surfaces of the laminating materials (C) and (D) are faced to each other and subjected to a press treatment at 240 ° C., 50 kgf / cm ^{2 for} 20 minutes,
A double-sided FMCL was obtained.

The 90 ° peel strength of this double-sided FMCL copper foil plastic film is 0.8 kgf / c at room temperature on the laminating material (c) side.
It was 0.6 kgf / cm at m and 200 ° C. The laminating material (d) side was 2.5 kgf / cm at room temperature and 0.5 kgf / cm at 200 ° C.

The tensile modulus at room temperature of the plastic film obtained by completely etching the copper foil of this double-sided FMCL is 260 kg / mm.
^{2. The} tensile elongation was 95% and the dielectric constant was 3.0 at 1KHz.

A printed circuit was formed on the copper foil surface of this double-sided FMCL by photo-etching, plated with through holes, and then floated in a solder bath at 300 ° C for 30 seconds. No delamination, voids, blister formation or any other change in state was observed.

The double-sided FMCL was left in a constant temperature bath at 200 ° C for 240 hours, but no defects such as wavy deformation, delamination, and blister were observed.

That is, as in Example 1, a double-sided FMCL having excellent productivity, heat resistance, mechanical properties and electrical properties was obtained.

Comparative Example 1 In Example 1, 330 during the manufacturing process of the laminating material (a)
A laminate material (e) was obtained by the same procedure except that the heating time in a nitrogen atmosphere at ℃ was changed to 5 minutes.

The glass transition temperature of the plastic film of this laminating material (e) was 340 ° C.

The solvent content was 1.4%.

The laminating material (e) and the laminating material (b) of Example 1 were laminated by the completely same method as the case of Example 1, and double-sided FMCL
Got This double sided FMCL copper foil and plastic film
90 degree peel strength is 1.
7kgf / cm, 1.5kgf / cm at 200 ℃, laminated material (b)
The side was 2.2 kgf / cm at room temperature and 2.0 kgf / cm at 200 ° C. The tensile modulus at room temperature of the plastic film obtained by completely etching the copper foil of this double-sided FMCL is 250k.
g / mm ^2, tensile elongation rate of 135% and a dielectric constant of 3.0 at 1KHz. That is, the solvent content in the plastic film is 1.
Double-sided FMCL that is almost the same as in Example 1 except that it is 4%
was gotten.

Further, a printed circuit was formed on the copper foil surface of the double-sided FMCL by a photo-etching method and through-hole plating was performed, but there was no wavy deformation, delamination, voids, or blisters.

When this double-sided FMCL on which a circuit was formed was suspended in a solder bath at 300 ° C for 30 seconds, a wavy deformation occurred and delamination occurred between the copper foil on the laminating material (e) side and the plastic film. As a result, a usable flexible printed circuit could not be obtained.

Also, when it was floated in a solder bath at 260 ° C for 20 seconds, wavy deformation occurred and delamination occurred between the copper foil and the plastic film, and a flexible printed circuit that could withstand use could not be obtained. .

Furthermore, when this double-sided FMCL was left in a constant temperature bath at 200 ° C for 240 hours, wavy deformation and delamination occurred.

That is, in Comparative Example 1, since the solvent content in the plastic film exceeds 1%, the plastic film cannot withstand a solder bath at 260 ° C as well as 300 ° C, and in addition, the high temperature deterioration is severe and the heat-resistant double-sided FM
It couldn't be CL.

Comparative Example 2 (e) 400 g of 4,4-diaminodiphenyl ether in a container equipped with a stirrer, a reflux condenser and a nitrogen introducing tube.
(2 mol) was dissolved in 3500 ml of N, N-dimethylacetamide, cooled to around 0 ° C, 436 g (2.0 mol) of pyromellitic dianhydride was added under a nitrogen atmosphere, and the mixture was stirred at around 0 ° C for 2 hours. Next, the solution was raised to room temperature and stirred under a nitrogen atmosphere for about 20 hours. The polyamic acid solution thus obtained had an inherent viscosity of 1.6 dl / g.

This polyamic acid solution was diluted with N, N-dimethylacetamide to a concentration of 16%.

This solution (e) was uniformly cast-coated on a commercially available rolled copper foil having a thickness of 35 μm, heated at 130 ° C. for 5 minutes, and further heated at 160 ° C. for 5 minutes to be dried, and then the oxygen concentration at 330 ° C. was 3%. Was heated in a nitrogen atmosphere for 20 minutes to obtain a laminate material (f) in which a polyimide having a film thickness of 20 μm was directly adhered to a copper foil.

The glass transition temperature of the plastic film obtained by completely etching the copper foil of the laminating material (f) was 400 ° C or higher.

The solvent content was 0.05%.

This laminating material (f) and the laminating material (d) in Example 2
Were laminated in the same manner as in Example 2 to obtain a double-sided FMCL.

The 90 degree peel strength of this double-sided FMCL copper foil plastic film is 0.35kgf / cm at room temperature and 200 ℃ at the laminating material (f) side.
Is 0.2 kgf / cm at room temperature on the laminating material (d) side at room temperature of 2.5
kgf / cm, 0.5 kgf / cm at 200 ° C.

The tensile elastic modulus at room temperature of the plastic film obtained by completely etching the copper foil of this double-sided FMCL is 320 kg / mm.
^{2. The} tensile elongation was 80% and the dielectric constant was 3.0 at 1KHz.

When this double-sided FMCL was punched to form through holes in the printed circuit, delamination occurred around the holes, and a good flexible printed circuit could not be obtained.

Furthermore, when wire bonding was applied to the double-sided FMCL on which the circuit was formed, delamination occurred between the copper foil and the plastic film.

That is, in Comparative Example 2, the peel strength between the copper foil and the plastic film was less than 0.7 kgf / cm at room temperature, and was 0.2 at 200 ° C.
Since it is less than 4 kgf / cm, neither through-hole processing nor wire-bonding processing was possible, and it was not at all satisfactory as a substrate for double-sided printed circuits.

[Brief description of drawings]

1 to 6 are schematic cross-sectional views of configuration examples of the double-sided FMCL of the present invention. 1 ... Metal foil 2 ... Mesh plastic film 3 ... Linear plastic film

Claims (5)

[Claims] 1. In a flexible double-sided metal foil laminate having a metal film adhered to both sides of a plastic film, the metal foil is directly adhered to the plastic film without an adhesive, and the 90 degree peel strength at room temperature is 0.7. ~ 22kgf / cm, 2
0.4 ~ 20kgf / cm at 00 ℃, solvent content of plastic film is 1 ~ 0.01%, solder heat resistance is 300 ℃
A flexible double-sided metal foil laminate, which does not show any change in shape when immersed in the bath for 30 seconds. 2. The plastic film has a tensile elastic modulus at room temperature of 100 to 800 kgf / mm ² , a tensile elongation of 30 to 200%, and a dielectric constant of 3.0 to 3.5 at 1 KHz. The laminated board according to claim 1. 3. The laminate according to claim 1, wherein the plastic film is made of a network plastic having a glass transition temperature of 280 to 390 ° C. and / or a linear plastic having a glass transition temperature of 150 to 260 ° C. 4. The plastic is a polyimide.
The laminated plate according to any one of 1 to 3. 5. The laminated board according to claim 1, wherein the laminated board is used for a flexible printed circuit board.