JP2621880B2 - Flexible metal plastic laminate - Google Patents

Description

The present invention relates to a flexible metal-plastic laminate having a plastic thin film directly formed on a metal foil without using an adhesive, and has a very small interlayer dimensional difference and an organic The present invention relates to a laminate having a very low solvent content in a polymer thin film, a large 90 ° peel adhesive strength at room temperature between a plastic thin film and a metal thin film, high flexibility, and excellent workability.

[Conventional technology] Flexible metal plastic laminate (FMCL = Flexib
le Metal Clad Laminate) is used in large quantities as a packaging material, flexible printed circuit board, covering material for electromagnetic wave shielding, and other materials that make full use of the characteristics of both metals and plastics. Things are used.

Laminated in these FMCL without any intervening adhesive
FMCL should take advantage of the excellent properties of plastic thin films, but in reality their properties have not been fully utilized. This may be due to the low adhesive strength of the laminate, making it unsuitable for use, or poor workability.

In order to take advantage of the excellent properties of plastic thin films, these FMCLs require that the dimensions of the metal foil and the plastic layer be within the appropriate range for each other due to the processing means and application. Furthermore, the amount of the solvent contained in the plastic is required to be not more than a certain amount, and in addition to the three requirements that the 90-degree peel adhesion strength between the metal foil and the plastic layer is not less than a certain value. is necessary. These will be described below.

FM with plastic thin film formed directly on metal foil
CL is caused by differences in the coefficient of thermal expansion between metals and plastics, or differences in tensile strength, compressive strength, and elastic modulus, etc., and the dimensional difference between the two is out of the appropriate range. In order to alleviate the problem, the solvent is often contained in the plastic thin film so that the solvent is adversely affected in the subsequent steps, for example, in order to leave or include the solvent later. For this reason, these FMCLs have many problems such as harmful curl in processing and wrinkling after pattern formation by etching of metal foil.

Therefore, despite the fact that adhesives having various disadvantages are omitted and the features of plastic films are utilized, they are used only for limited applications, or even if they are used, those skilled in the art will find it difficult to process them. I have.

The plastic thin film size may be long in a special manufacturing method, but is often short in comparison with that of a metal foil. The dimensional difference referred to here can be measured when each layer constituting the FMCL is singulated by a method in which no stress is generated.

Since it is usually difficult to singulate all the layers by a method in which no new stress is generated, it can be seen that substantially no new stress is generated.
Measure the dimensions while in the CL state, take the measurements as the dimensions of the metal foil (which is equal to the dimensions of the plastic film before etching), and then etch the metal using an agent that does not affect the plastic film. The foil is removed, the plastic layer is singulated, the dimensions are measured and taken as the plastic thin film dimensions to determine the dimensional difference between them (which is equal to the plastic dimensional difference before and after etching).

The shrinkage ratio of the plastic before and after the etching is represented by the following equation.

Shrinkage = {(Plastic dimension before etching−Plastic dimension after etching) / Plastic dimension before etching} × 100 The adverse effects due to large dimensional contraction of the plastic thin film are roughly classified into the following two.

a) The FMCL is curled with the plastic thin film inside or outside, and it is extremely difficult to punch, cut, apply a pattern to metal foil, attach, superimpose, and perform other processing by developing this FMCL while suppressing this curl. Has become.

b) Flexible printed wiring board (FPC = Flexible Prin
ted Circuit) is typical, but when a precise circuit pattern is drawn with an etching resist ink and then etched, and the metal foil is partially left, the portion between the portion where the metal foil remains and the portion where it does not remain is Causes a dimensional difference, which causes an overall wrinkle. As a result, the relative positional relationship between points on the pattern changes, the precision required for mounting components or connecting to other patterns is lacking, and the appearance is unsightly.

If the plastic thin film dimension is more than a certain dimension compared to that of the metal foil, shorter or longer, it can be said that there is little practicality. The limit is generally less than ± 0.3%, preferably less than ± 0.1%. In addition, the solvent contained in the plastic thin film often tends to reduce the above dimensions, but has a large adverse effect on the FMCL processing.

The adverse effect is that the solvent tends to escape over time because the solvent is not fixed in the plastic thin film. This is to cause dimensional shrinkage.

In particular, when applied to an FPC (Flexible Printed Circuit) and floated in a solder bath at 260 ° C., in many cases, the solvent rapidly escapes and the plastic layer shrinks. In severe cases, there is a disadvantage that foaming may occur in the plastic film layer and wrinkles may occur.

Therefore, considering long-term dimensional stability or dimensional stability during processing with heat treatment, the solvent contained in the plastic layer is less than 0.2%, preferably 0.1% or less, more preferably 0.05% or less. . Furthermore, the 90-degree peel adhesive strength between the metal foil and the plastic layer at room temperature is used to prevent delamination during repeated bending of the FMCL or to prevent the metal foil pattern formed by etching from peeling from the plastic layer. Necessary and the stronger, the better. The lower limit is 0.7 kg / cm in the industry.

From the above, the shrinkage rate of the plastic thin film is ± 0.3
% And the amount of solvent contained in the plastic thin film is less than 0.2%.
It will be understood that it is essential to have the three requirements that the 0 degree peel adhesive strength is 0.7 kg / cm or more. Such FMCL can be easily processed and used in many of the above applications because of its excellent workability.

However, it was formed directly without using an adhesive
Many attempts have been made in FMCL to satisfy all of these characteristics, but it is extremely difficult to satisfy the above three requirements at the same time, and it has not been realized conventionally. If the dimensional difference between the metal foil and the plastic thin film is ± 0.3% or more, it is not preferable for the FMCL as described above, and it is a fatal defect in some applications.
There is a CL. As a countermeasure, Japanese Patent Application Laid-Open No. 56-23791 discloses a method in which a plastic thin film is swollen by absorbing 0.2 to 2% of a solvent so that the size of the plastic thin film is close to that of a metal foil.

However, although this method has an effect of reducing the dimensional difference, it is hardly practical as an FMCL because of the side effect caused by the inclusion of the solvent in the plastic as described above. Moreover, as in the embodiment, the dimensional difference is 0.3
%, Which is not practical for FMCL. In addition, JP-A-59-22388 and 59-2
As shown by 2389, by applying bending plastic deformation to the metal foil in the opposite direction to the curl, a simple curl that tries to eliminate the curl by balancing with the stress causing the curl formation based on the dimensional difference between the metal foil and the plastic thin film There is a removal method. In this case, the dimensions of the metal foil do not change substantially before and after the treatment.

FMCL treated by this method has only the above-mentioned adverse effects a) due to the small size of the plastic thin film,
It is only temporarily resolved in appearance, and has the disadvantage of returning to the current state after passing through the heat history. Regarding adverse effect b), the dimensional difference between the plastic thin film and the metal foil is the same as before the treatment Has the disadvantage that essentially no improvement can occur.

Some attempts have been made to selectively stretch the plastic thin film to approximate the dimensions of the metal foil. For example, Japanese Patent Application Laid-Open Nos. 54-108272 and 54-111673 disclose a method of reducing the dimensional difference by winding the plastic thin film on the outside and holding it at a high temperature for a long time and annealing the plastic thin film in a stretched state. However, since the plastic thin film contracts again due to the difference in the coefficient of thermal expansion between the metal and the plastic during cooling to room temperature, there is a disadvantage that the dimensional difference hardly disappears.
Also, an attempt to reduce the difference in the coefficient of thermal expansion between plastic and metal and to reduce the dimensional difference due to the coefficient of thermal expansion when cooling to room temperature after laminating the plastic thin film and metal foil at a high temperature has been made. 60-157286 and 60-210894. However, although not described, it is presumed that if the dimensional difference can be achieved, it is necessary to consider the problem of drying shrinkage due to volatilization of the solvent from the polyamic acid varnish or curing shrinkage due to the imidization reaction. It is considered that the difference in the coefficient of expansion (expressed by the coefficient of thermal expansion of plastic minus the coefficient of thermal expansion of metal) is required to be -1.0 to 0.4 × 10 ⁻⁵ / ° C.

In this case, the coefficient of thermal expansion of the entire plastic is close to or lower than that of metal, resulting in a film having too high rigidity (generally having a tensile modulus of 400 kg / mm ² or more), and loses the flexibility desirable for FMCL. In addition, as a result of the increased rigidity, the 90 ° peel adhesion strength between the film and the metal foil at room temperature is reduced, and it is lower than the 0.7 kg / cm generally required for FMCL. There is. To reduce the dimensional difference between the metal foil and the plastic thin film, it is considered that FMCL obtained by using only a plastic having a low coefficient of thermal expansion lacks practicality.

[Problems to be Solved by the Invention] An object of the present invention is to provide a FMCL having a plastic thin layer directly formed on a long metal foil without using an adhesive, in which the dimensional difference between the metal foil and the plastic thin film is ± 0.3%
Smaller, the solvent content in the thin film is less than 0.2%,
In addition, it is an object of the present invention to provide an FMCL which has a 90 ° peel adhesive strength between a metal foil and a plastic thin film at room temperature of 0.7 kg / cm or more and is excellent in flexibility and processability.

[Means for Solving the Problems] The present invention relates to a method for compressing or compressing a metal foil in an FMCL having a plastic thin film composed of one or more layers directly formed on a metal foil without using an adhesive and having a solvent content of less than 0.2%. And / or stretching plastic deformation to reduce the shrinkage of the plastic thin film to less than ± 0.3% (hereinafter referred to as method 1), or the solvent content of the entire plastic thin film layer is less than 0.2% and the average linear thermal expansion coefficient is It is larger than that of metal in the range of (−1.0 to +0.4) × 10 ⁻⁵ / ° C., and in addition, at least the tensile modulus at room temperature of the plastic in contact with the metal foil is 10%.
It can be achieved by FMCL obtained by a method of providing a plastic film layer comprising two or more layers having a tensile elongation of 0 to 400 kg / mm ² and a tensile elongation of 40 to 200% (hereinafter referred to as method 2). In addition. Solvent content in plastic
In order to make it smaller than 0.2%, it is obtained by staying at a temperature of 200 ° C. or more for a necessary time and removing the solvent. Alternatively, it can be obtained by extruding and molding a thermoplastic resin containing no solvent onto a metal foil.

Various materials can be used for the plastics and metals used in these FMCLs.

As the plastic, although not particularly limited, polyimide, polyamide imide, polyester, polyamide,
Polyether sulfone, polyether ether ketone, polypropylene, crosslinked polyethylene, polyparabanic acid, polyfluoroethylene, and the like are used. Especially FPC
Since heat resistance is required, polyimide, polyamide imide, aromatic polyester, and polyfluoroethylene polyparabanic acid are used. The thickness of the plastic thin film is preferably about 5 to 100 μm.

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

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

Preferred mechanical properties, plastics tensile modulus, and a 100 kg / mm ² or more at room temperature, the amount of deformation 1
At 0% or less, it is difficult to undergo plastic deformation, and the metal has a tensile modulus of 10,000 kg / mm ² or less, preferably 5,000 or less.
It is 0 kg / mm ² or less, and plastic deformation starts when the amount of deformation is several percent or less, and the tensile elastic modulus in the plastic deformation region is 5 times or less that of plastic.

FMCL having a plastic thin film composed of one or more layers directly formed on a metal foil without an adhesive in the present invention
Is generally produced as follows, but is not limited thereto.

Whether the polymer is synthesized in the solvent, dissolved in the solvent, or the precursor of the polymer is synthesized in the solvent,
Dissolve in solvent.

The varnish obtained by these methods is applied on a metal foil, dried at an appropriate temperature, and, if necessary, a heat-curing reaction is performed, and the solvent content is reduced to less than 0.2%. When the varnish is applied, the thickness of the thin film after drying and curing is preferably 5
100100 μm, more preferably about 10-50 μm. When the film thickness is large, the application and drying and curing of the varnish may be repeated.

In addition to such a method, it can also be produced by extruding a melt of plastic on a metal foil.

When the desired FMCL is obtained by Method 2, a polymer varnish having a tensile modulus of 100 to 400 kg / mm ² and a tensile elongation of 40 to 200% as a first layer, or a varnish thereof. First, apply the varnish of the precursor to the metal foil and immediately apply the varnish of the second layer or later, or dry the first varnish (solvent content is 1% or more). It is obtained by a method such as coating.

The reason for applying the first layer is that the polymer after the second layer has a low adhesive force to the metal foil as described above, so that it is not appropriate to apply the polymer directly to the metal foil. The purpose of is to bridge the bond between the metal and the polymer after the second layer without impairing the properties of the plastic layer like an adhesive. Moreover, the polymers in the second and subsequent layers generally have too high rigidity, and thus tend to lack flexibility as an FMCL. The flexibility can be increased by using a polymer having a low tensile modulus in the first layer.

The thickness of the polymer of the first layer after the solvent is dried is preferably 1/3 or less, more preferably 1/5 or less, of the total thickness of the polymers of the second and subsequent layers after the solvent is dried. The reason is that if there is a difference in the coefficient of linear thermal expansion between the polymer layers in the thickness direction, curling will occur in the plastic thin film after the metal foil is removed by etching. For, to mitigate or substantially avoid it. That is, after the second layer, the rigidity of the polymer is high, that is, the tensile modulus is 400 kg / mm ² or more, and in many cases, 600 kg
a / mm ^2, the thicker than the first layer, the first layer of low polymer rigidity, which tensile elastic modulus is at 400 kg / mm ² or less, most are at 300 kg / mm ² or less, the second layer Although less than 1/3 of the thickness, it is not much affected by this first layer. For this reason, the plastic thin film does not substantially curl.

At this time, as described above, the average coefficient of linear thermal expansion of the film finally formed on the metal is higher than that of the metal by (−1.0).
It is necessary to select the polymer so that it is only considerably large within the range of +0.4) × 10 ^-5 / ° C., and the final heating temperature is the highest glass transition temperature among the polymers constituting the film. It must be above the glass transition temperature.

FMCLs other than those manufactured by method 2 have a considerable detrimental difference in dimensions between the metal foil and the plastic film, generally ± 0.3% or more, and often ± 0.5%.
% Or more.

In this case, the desired FMCL can be obtained by one of the methods.

In the first method, the metal foil is shrunk and / or expanded by plastic deformation to approach the size of the plastic layer within the range of 0.001 to 5% in the longitudinal direction and / or the width direction of the metal foil while being laminated in the FMCL. Or by being matched. Here, the method of shrinking or expanding is not particularly limited. For example, as the method of expanding, a) FMCL is performed in the same manner as in biaxial stretching of a plastic film.
The whole is stretched, and the extent of the stretching is only a part of the stretching amount of the metal foil that causes plastic deformation. However, the plastic film is stretched and plastically deformed.

Therefore, the degree of stretching varies depending on the metal and plastic material constituting the FMCL, but is generally within 5%. If the amount of stretch plastic deformation of the metal foil becomes equal to the dimensional difference between the metal foil and the plastic film in the original FMCL, the dimensional difference after the stretch deformation is substantially eliminated.

b) In the case of a short fixed-size sheet, for example, 300 mm square, it can be performed by sandwiching the FMCL between high-precision precision presses and stretching the FMCL uniformly in the plane direction.

c) As shown in FIG. 1, place a long FMCL on a curved surface of a first bar provided at an angle of 0 to 80 degrees with respect to the width direction thereof, with a plastic film inside and under tension. First step in the longitudinal direction, 0 in the FMCL width direction
A second step of longitudinally sliding the laminate under tension with the polymer inward on the curved surface of a second bar provided at an angle of -80 degrees, in any order, and One or more steps, there is a method to carry out, in this method, metal foil, tensile elastic modulus of the plastic film,
The shape of the first bar and the second bar, particularly the radius of curvature of the curved surface through which the plastic film passes, the angle of introduction, the angle of extraction (see FIG. 2) and the degree of tension when the FMCL passes through the bar, The number of times the FMCL passes through the bar has a large effect on the degree of dimensional difference correction. In order to expand the metal, the radius of curvature of the curved surface through which the plastic film of the bar passes is 0.
001-0.5mm, the tension applied to FMCL is the total pressure of FMCL,
Although it depends on the thickness of the constituent materials, it is generally 50 g / cm or more, preferably 200 g / cm or more, and the total of the introduction angle and the extraction angle is 20 to 140 degrees, preferably 90 to 140 degrees, and the bar is The number of passes is not particularly limited, but it is practical that each bar has 5 or less passes.

In these methods, generally, the smaller the radius of curvature of the curved surface of the bar, the larger the tension applied to the FMCL, the larger the angle of introduction,
The smaller the sum of the induced angles, the larger the elastic modulus of the plastic, the smaller the elastic modulus of the metal and the easier it is to plastically deform, the more easily the metal is stretched and plastically deformed.

The shrinking method is as follows: a) In the case of a short fixed-size sheet, for example, 300 mm square, an FMCL is sandwiched between parallel plates and held between the parallel plates with a pressure of about the contact pressure. Thereafter, pressure is applied to the end face of the FMCL. The pressure is required to be large enough to cause shrinkage plastic deformation of the metal foil, and a method of manufacturing by controlling the amount of shrinkage deformation by the magnitude of this pressure.

b) In the case of a long FMCL, the device may be completely identical when it is inflated. The difference in method is that the copper foil is slipped on the curved surface of the bar, instead of the plastic film. Only.

 Other than this, it is implemented in a similar manner.

Example 1 A container equipped with a stirrer, a reflux condenser and a nitrogen inlet tube was charged with 4,4′-bis (3-aminophenoxy) biphenyl 2
21 g (0.60 mol) and 280 g (1.4 mol) of 4,4'-diaminodiphenyl ether were mixed with N, N-dimethylacetamide 3500
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 above solution was returned to room temperature, and stirred under a nitrogen atmosphere for about 20 hours. The polyamic acid solution thus obtained is
Diluted to 19% with N, N-dimethylacetamide and adjusted rotational viscosity to 120,000 cps. Rolled copper foil (Nihon Mining Co., Ltd., DN
−02, thickness 35μm) evenly and applied at 130 ℃
And dried at 180 ° C. for 5 minutes.

Under a nitrogen atmosphere at _{360 ℃ (0 2 2vol.%} ) Was heated for 20 minutes in a thickness 60μm with a coating film of polyimide
FMCL was obtained. The average coefficient of linear thermal expansion of the copper foil from room temperature to 100 ° C. was 1.7 × 10 ⁻⁵ / ° C. When the FMCL thus obtained is cut into a square substrate of 24 × 24 cm,
In both the width direction and the longitudinal direction, a curl with a radius of curvature of 15 cm with the polyimide thin layer inside was observed. The dimensional shrinkage of the polyimide thin layer was 0.65%, and the amount of the remaining solvent, N, N-dimethylacetamide, in the polyimide thin layer was 0.01%. The average linear thermal expansion coefficient of this polyimide from room temperature to 100 ° C. was 4.4 × 10 ⁻⁵ / ° C. This long product of FMCL was slit to a width of 24 cm by a slitter and wound up on a roll. After that, the FMCL wound on this roll
Is fixed at an angle of 40 degrees with respect to the width direction, the cross section thereof is 0.6 mm in width and 50 mm in length, and the functional edge, that is, the radius of curvature of the edge portion in contact with the FMCL is 0.05.
While passing the surface of the copper foil in contact with the first bar made of zirconia having a diameter of mm, the copper foil was passed at an introduction angle of 60 degrees and an extraction angle of 60 degrees. At this time, a tension of 12 kg, that is, 0.5 kg / cm width was applied to the FMCL in the traveling direction. After passing through the first bar, the surface of the copper foil is brought into contact with a second bar of the same shape made of zirconia at an angle of -40 degrees with respect to the width direction under the same conditions as in the first bar. Let it pass. The process of rubbing the edges of the two bars was repeated three times in an environment of 20 ° C. and 50% humidity, and wound up again on a roll. FM obtained in this way
As for CL, the dimensional shrinkage of the polyimide thin layer before and after the etching of the copper foil was 0.03%.

This FMCL was stored at 50 ° C. for one year, but no change in dimensional shrinkage was observed. An FPC was manufactured by drawing a wiring pattern on the FMCL by a conventional method. This FPC had very little unevenness on the whole and on the functional surface, and had good flatness.

This FPC was floated on the surface of the molten solder at 260 ° C. for 10 seconds, and then returned to normal temperature. However, the entire surface still had a good flat surface with little unevenness.

The 90 ° peel adhesive strength at 23 ° C. of the metal foil and plastic film of FMCL obtained as described above was 1.7 k.
g / cm.

Example 2 A container equipped with a stirrer, a reflux condenser, and a nitrogen inlet tube was charged with 4,4′-bis (3-aminophenoxy) biphenyl 2
Dissolve 21 g (0.6 mol) in N, N-dimethylacetamide (1400 ml) and pyromellitic dianhydride under nitrogen atmosphere
130 g (0.6 mol) was added, and the mixture was stirred at room temperature for about 20 hours. The rotational viscosity of the polyamic acid solution thus obtained is 8
It was 3,000 cps.

 This solution is referred to as solution A.

Next, 120 g (0.6 mol) of 4,4'-diaminodiphenyl ether was placed in a similar container with N, N'-dimethylacetamide.
The solution was dissolved in 1000 ml, and under a nitrogen atmosphere, 130 g (0.6 mol) of pyromellitic dianhydride was added, followed by stirring at room temperature for about 20 hours. The rotational viscosity of the polyamic acid solution thus obtained is
It was 65,000 cps.

 This solution is referred to as solution B.

The solution A was uniformly coated on a rolled copper foil (thickness: 35 μm) of the same lot as that used in Example 1, and dried by heating at 130 ° C. for 3 minutes and further at 160 ° C. for 3 minutes. The thickness of the dried polyamic acid film was 3 μm. Next, the polyamic acid-coated copper foil was uniformly coated with the solution B, heated and dried at 130 ° C. for 5 minutes, further at 160 ° C. for 5 minutes, and then heated in a 370 ° C. nitrogen atmosphere for 10 minutes. hand,
A copper foil coated with polyimide was obtained.

The residual solvent amount in the polyimide thin film was 0.03%.
The total thickness of the film from the solution A and the film from the solution B was 27 μm, and the average coefficient of linear thermal expansion was 2.
5 × 10 ⁻⁵ / ° C.

This FMCL was curled as in Example 1, and the dimensional shrinkage was 0.45%. Then, curl correction and dimensional correction were performed in the same manner as in Example 1 to obtain a square FMCL of 24 × 24 cm. The curl status visually observed was such that the copper foil was on the inside and the radius of curvature was 20 cm or more. The dimensional shrinkage was 0.02% in both the width direction and the length direction. This FMCL had good adhesion between the polyimide composite film and the copper foil, and the 90 ° peel adhesive strength was 1.8 kg / cm.

Further, an FPC was manufactured by drawing a wiring pattern by a conventional method, and this FPC had very little unevenness on the whole and on the functional surface and had good flatness.

[Example 3] 219 g (1.8 mol) of 1,4'-diamino-2-methylbenzene was dissolved in 4250 g of N-methyl-2-pyrrolidone in a vessel equipped with a stirrer, a reflux condenser and a nitrogen inlet tube, 0
Cool down to around ℃, and under nitrogen atmosphere 3,3 ', 4,4'
530 g (1.8 mol) of -biphenyltetracarboxylic dianhydride was added, and the mixture was stirred at about 0 ° C for 2 hours.

Next, the solution was returned to room temperature and stirred under a nitrogen atmosphere for about 20 hours. The polyamic acid solution thus obtained was left at 60 ° C. until the rotational viscosity became 50 ps. This solution is referred to as solution C.

In the same manner as in Example 2, solution A was uniformly coated on the same lot of rolled copper foil as used in Example 1,
It was dried by heating at 130 ° C. for 3 minutes and further at 160 ° C. for 4 minutes.
The thickness of the dried polyamic acid film was 4 μm. Next, coat the solution C uniformly, and at 130 ° C for 5 minutes,
After further heating and drying at 160 ° C. for 5 minutes, it was heated in a nitrogen atmosphere at 400 ° C. for 10 minutes to obtain a polyimide-coated copper foil. The film thickness of the entire polyimide was 30 μm. The residual solvent amount in the polyimide thin film was 0.02%. This FMCL
Had a curl with a radius of curvature of 20 cm with the copper foil inside, but this did not hinder processing. The dimensional shrinkage was -0.12%. The adhesive strength between the polyimide composite film and the copper foil was 1.3 kg / cm at a peel strength of 90 degrees. The solution A
Tensile modulus at room temperature of the polyimide film prepared from a 240 kg / mm ^2, and the tensile elongation, 9
It was 0%. The coefficient of thermal expansion of the polyimide composite film was 1.0 × 10 ⁻⁵ ° C. Furthermore, an FPC was manufactured by drawing a wiring pattern by a conventional method, and this FPC had little unevenness on the entire surface and the functional surface, and had no problem in flatness in practical use.

[Comparative Example-1] The solution C obtained in Example 3 was uniformly coated on a rolled copper foil of the same lot as that used in Example 1 in the same manner as in Example 1, and was further coated at 130 ° C for 5 minutes. After heating and drying at 180 ° C for 5 minutes, it is heated in a nitrogen atmosphere at 400 ° C for 10 minutes, and the FMCL having a polyimide coating film with a thickness of 60 µm
I got

The dimensional shrinkage of the thin polyimide layer of FMCL was -0.15%. The coefficient of linear thermal expansion from room temperature to 100 ° C. of the polyimide film was 6 × 10 ⁻⁶ / ° C. An FPC was manufactured by drawing a wiring pattern by a conventional method, but the flatness of the FPC was not a problem in practical use. However, the adhesion between the important polyimide film and copper foil is 0.35 at 90 degree peel strength.
Since the circuit peeling was as low as kg / cm, it was judged that it was not practical for FMCL.

Comparative Example 2 In Example 1, the dimensional shrinkage of the polyimide thin film was 0.
I tried to draw the wiring pattern while it was as large as 55%, but the work was extremely difficult due to the curl. Furthermore, the pattern that could be drawn also had a very large amount of unevenness as a whole and lacked planarity, and the workability of subsequent processing such as lamination of a coverlay film was extremely poor.

Comparative Example 3 In Example 1, the polyamic acid solution was uniformly cast and applied to the rolled copper foil, and then heated and dried at 130 ° C. for 5 minutes and further at 180 ° C. for 5 minutes. Thereafter 0 ₂ 2 vol at.% Of 280 ° C. in a nitrogen atmosphere and heated for 5 minutes to obtain a FMCL thickness 60μm with a coating film of polyimide. The dimensional shrinkage of the polyimide thin film was 0.50%, and the amount of N, N-dimethylacetamide, which was the amount of residual solvent in the polyimide thin film, was 1.0%. This long FMCL was used in the same manner as in Example 1 to reduce the dimensional shrinkage of the polyimide thin film to 0.10%. This FMCL had a weak curl with a radius of curvature of 15 cm with the copper foil inside.

An FPC was manufactured by drawing a wiring pattern on this FMCL by a conventional method, but the workability was good.

This FPC had very little unevenness on the whole and on the functional surface, and had good flatness.

However, this FPC was applied to the surface of
After floating for 2 seconds, when the temperature was returned to room temperature, a strong curl having a radius of curvature of 3.0 cm with the polyimide thin film inside was generated. This was due to the contraction of the polyimide thin film due to the volatilization of a part of the solvent remaining in the polyimide thin film.

Further, when this FMCL was left at 100 ° C. for one month, the dimensional shrinkage of the polyimide thin film was increased to 0.4%. It is presumed that this is because the solvent volatilizes gradually.

[Brief description of the drawings]

Fig. 1 is a plan view for explaining the arrangement angles of bars functioning in the process of correcting the dimensions of the plastic constituting FMCL, and the meaning of the longitudinal and lateral directions, and Fig. 2 is the introduction and derivation angles of the FMCL function base. FIG.

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Claims (11)

(57) [Claims] 1. A flexible metal-plastic laminate having a plastic thin film directly formed on a metal foil without an adhesive, wherein the metal foil has a radius of curvature of 0.001 to 0.5.
The metal foil is brought into contact with the curved surface of a bar having a curved surface of mm and passed under tension. Thus, when the metal foil is entirely removed by chemical etching, the shrinkage ratio of the plastic thin film is based on the thin film size before etching. As less than ± 0.3% and the solvent content in plastic is
A flexible metal-plastic laminate having a 90 ° peel adhesion between a metal foil and a plastic thin film at room temperature of less than 2%, which is 0.7 kg / cm or more. 2. The laminate according to claim 1, wherein the plastic thin film comprises a plurality of types of plastics. 3. The method according to claim ² , wherein at least the plastic in contact with the metal foil has a tensile modulus at room temperature of 100 to 400 kg / mm ² and a tensile elongation of 40 to 200%.
13. The laminate according to the above item. 4. Contacting a metal foil and having a tensile modulus of 100 to 400 kg / m
m ² and a tensile elongation of 40 to 200%, the thickness of the plastic thin film is 1 / th of the thickness of the entire plastic layer.
3. The laminate according to claim 2, wherein the thickness is 3 or less. 5. The laminate according to claim 3, wherein the average coefficient of linear thermal expansion of the plastic thin film is larger than that of metal by (−1.0 to +0.4) × 10 ⁻⁵ / ° C. 6. The method according to claim 1, wherein the average coefficient of linear thermal expansion of the plastic thin film is at least 1.0 × 10 ⁻⁵ / ° C. lower than that of the metal, or at least 0.4 × 10 ⁻⁵ / ° C. A laminate as described. 7. The laminate according to claim 1, wherein the plastic is a heat-resistant polymer having an imide bond, a heat-resistant polyester or polyfluoroethylene. 8. The laminate according to claim 7, wherein the heat-resistant polymer having an imide bond is polyimide or amide imide. 9. The metal foil is made of copper, aluminum, nickel,
The laminate according to claim 1, wherein the laminate is gold or silver. 10. The laminate according to claim 1, wherein the use of the laminate is a substrate for a flexible printed circuit. 11. The laminate according to claim 2, wherein the use of the laminate is a substrate for a flexible printed circuit.