JP2585297B2 - Flexible plastic metal laminate - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention uses a flexible metal plastic laminate having excellent heat resistance, electrical properties, and mechanical properties, and at the same time, suitable for a process of correcting interlayer dimensional differences. The present invention relates to a flexible metal plastic laminate in which the obtained interlayer dimensional difference is corrected.

[Prior art] Flexible metal plastic laminate (FMCL = Flex) composed of laminated metal foil and plastic film
ible Metal Clad Laminate) is a packaging material, flexible printed circuit board,
It is used in large quantities as a material that combines and utilizes the characteristics of both metals and plastics, such as electromagnetic shielding films.

These FMCLs require that the dimensions of the metal foil and the plastic layer be in an appropriate relationship to each other for their processing means and applications.

However, due to the difference in the coefficient of thermal expansion between metal and plastic, or the difference in tensile strength, compressive strength, elastic modulus, etc., in ordinary FMCL, the dimensions of both are outside the desired appropriate range, Stakeholders in the industry have been struggling to address the deficiencies caused by this.

These differences in dimensions can be quantitatively grasped if each of the metal foil or the plastic layer of the FMCL is separated and singulated by a method that does not generate stress.

In many cases, the dimensions of the plastic layer are less than a reasonable range and are generally shorter than those of the metal foil.

The adverse effects of a short plastic layer are roughly classified into the following two types.

First, a) FMCL is curled with the plastic layer inside. It is extremely difficult to perform punching, cutting, patterning, lamination, and other processing that must be performed by expanding the FMCL while suppressing this curl. It is what has become. B) Flexible printed wiring board (FPC = Flexible Prin
ted circuit), a precise circuit pattern is drawn with an etching resist ink and then etched, and if the metal foil is left partially, the dimensional change occurs in the part with and without the metal foil Therefore, an entire wrinkle is formed.

As a result, the relative positional relationship between the points on the pattern changes, and the precision required for mounting components or connecting to other patterns is lacking, and the appearance is unsightly.

For this reason, in FMCL, if the dimensions of the plastic layer are smaller than the dimensions of the metal foil by more than a certain dimension, it can be said that there is almost no practical usefulness.

According to the study of the present inventors, the measurement of these dimensional differences was determined as follows because it is usually difficult to separate and singly separate each component by a method that does not generate stress again. That is, according to our method, a dimension is measured in the FMCL state as a very approximate singulation method in which stress is not renewed substantially, and the measured value is measured as the dimension of the metal foil (ie, (Equal to the dimensions of the plastic layer before etching), then removing the metal foil by etching using a chemical that does not affect the plastic layer, singulating the plastic layer, measuring the dimensions, , The dimensional difference between them (which is equal to the length of the plastic layer before etching minus the length of the plastic layer after etching) is determined.

In some cases, various measures have conventionally been taken to eliminate the above-mentioned drawbacks which may be fatal as products, but FMCLs having satisfactory properties have not been completed.

As examples of known techniques, several simple curl removing methods have been proposed. For example, JP-A-59-
As shown in 22388 and 59-22389, by applying bending plastic deformation opposite to curling to a metal foil to balance the stress causing curl formation based on the dimensional difference between the metal foil and the plastic. There is a method of reducing curling. However, in this case, the dimensions of the metal foil remain substantially unchanged before and after the treatment.

Thus, in the FMCL treated by this method, only the above-mentioned a) among the adverse effects of the small size of the plastic layer is apparently only temporarily resolved. Therefore, there is a defect that the resin layer returns to its original state immediately after passing through the heat history. In addition, regarding the adverse effect b), since the dimensional difference between the plastic layer and the metal foil remains substantially unchanged from before the treatment, There is a disadvantage that no fundamental improvement in properties has been made.

Furthermore, Japanese Patent Application Laid-Open No. 59-82783 has attempted to reduce curl by selecting a copper foil.
This method is also simply a measure of curl reduction,
Not only is the dimensional difference between the plastic layer and the metal layer not improved at all, but also the curl remains, and there is a major problem that both of the adverse effects a) and b) are present.

It should be noted that, as anyone can easily think of, some attempts have been made to easily stretch the shrinking “plastic layer” closer to the dimensions of the metal foil. I have.

For example, Japanese Patent Application Laid-Open No. 56-23791 attempts to make the size of a plastic layer close to that of a metal foil by absorbing and swelling a solvent in a plastic layer.

However, in this method, the FMCL is heated to a high temperature, for example, 10
If exposed to an atmosphere of 0 ° C or higher, or for a long time,
The solvent that has been absorbed inevitably escapes from the plastic layer due to being left in the air, and the plastic layer has the disadvantage of shrinking again. In the first place, it is extremely difficult to reduce the dimensional difference between the metal foil and the metal foil to a certain required range.

Japanese Patent Application Laid-Open No. Sho 54-108272 discloses a method in which the plastic layer is stretched while being wound at a high temperature for a long time while being rolled so that the plastic layer is on the outside, and the plastic layer is stretched. However, since the plastic layer contracts again due to the difference in the coefficient of thermal expansion between metal and plastic when cooled from high temperature to room temperature, the dimensional difference is hardly reduced. There is.

Conventionally, USP 3179634, JP-A-49-51559, JP-A-52-1158
A-FMCL (= Adhesiveless FMCL), which does not use an adhesive for lamination, provided by 88, 57-80049, 57-181857, 59-162044, and JP-A-61-66049, has heat resistance, Although it has excellent performance in terms of flexible dielectric properties, it has not been put to practical use mainly due to dimensional difference or dimensional shrinkage of a thin plastic layer.

[Problems to be solved by the invention]

An object of the present invention is to use an FMCL capable of easily correcting an interlayer dimensional difference between a metal layer and a plastic layer, and using the dimensional difference by a dimensional difference correcting method proposed by the present inventors. To provide a modified FMCL.

[Means to solve the problem]

That is, according to the present invention, in a flexible laminate having a metal layer and a plastic layer laminated on each other and having a difference in interlayer dimension between the metal layer and the plastic layer, the bending of the metal layer given by the following equation The rigidity is 20 gcm or less, 0.001 gcm or more, and the flexural rigidity of the plastic layer is 1 / the flexural rigidity of the metal layer.
A flexible laminated plate having a radius of curvature of 500 or more and 1/2 or less is passed under tension by bringing the metal layer into contact with the edge of a bar having an edge curved surface with a radius of curvature smaller than 0.5 mm, and the metal layer is compressed plastically. There is provided a flexible metal-plastic laminate in which the difference in dimension between the metal layer and the plastic layer has been corrected by being deformed.

However, D: Flexural rigidity (g · cm) E: Young's modulus (g / cm ² ) t: Thickness (cm) ν: Poisson's ratio (−) [Embodiment of the invention] Hereinafter, embodiments of the invention will be described in detail. Will be described.

We have proposed the following method as FMCL for correcting a dimensional difference between layers in a flexible laminate made by laminating a plastic layer and a metal layer by shrinking and plastically deforming the metal layer. According to the method, for example, in the case of a continuous sheet, a long FMCL is provided at an angle within a range of 0 to 80 degrees with respect to a width direction (TD direction) thereof, and a functional curved surface of an edge is provided. Part (ie,
A first process in which an FMCL is bent on a curved surface of a first bar having a radius of curvature of an edge portion which is smaller than 0.5 mm and is brought into contact with a metal foil side to pass through while maintaining a considerable tension state; Then, with respect to the TD direction of the FMCL,
Provided as an angle in the range of 80 degrees, similarly, the FMCL is bent on the curved surface of the second bar where the radius of curvature of the functional curved surface portion of the edge is smaller than 0.5 mm, and the metal foil side is brought into contact with the The process is performed one or more times before and after the second process of passing while maintaining the tension state, and the shrinkage of the plastic thin layer before and after the etching of the metal foil is caused by the longitudinal direction of the FMCL ( In the case of only MD direction), the dimensional difference between the layers is corrected by setting the FMCL to ± 5 degrees or less with respect to the TD direction and performing at least one of the first and second processes described above at least once. Things.

The above-described method of correcting the interlayer dimensional difference is applied to a case where the plastic layer is shorter than the metal layer, and this is a basic embodiment of the present invention.

However, for the case where the plastic layer is longer than the metal layer, which is not the case in practice, we propose the following method.

That is, according to the method, a long flexible metal foil laminate having a metal foil and a polymer thin film is placed on a curved surface of a bar provided at an angle of 0 to 80 degrees with respect to the width direction of the laminate, and the polymer is formed. A step of sliding in the longitudinal direction in a tension state with the inside inward, and on the curved surface of a bar provided at an angle of 0 to -80 degrees with respect to the width direction of the laminate, the polymer Is performed one or more times in the longitudinal direction in a tensioned state, thereby correcting the dimensional difference between the metal foil layer and the polymer layer of the flexible metal foil laminate.

Thus, by such an interlayer size correcting method, the dimensional difference of a normal flexible metal plastic laminate can be corrected tentatively and in principle.
We have found that the effect may not always be sufficient under all conditions. Thus, when we further examined, as the target FMCA, the bending rigidity was a metal layer having a specific rigidity of 20 gcm or less, and the bending rigidity was 1/50 of that of the metal foil layer.
When FMCL is formed by laminating plastic layers having a specific rigidity of 0 or more, or having such physical properties
When FMCL is selected, surprisingly, it is found that the effect of correcting the interlayer dimensional difference can be extremely easily and maximally achieved as compared with the others, and the present invention is completed. It has been reached.

It is considered that the technical basis that the FMCL of the present invention can particularly exert such an effect is probably as described below.

For ease of understanding, a case will be described in which the dimension of the plastic thin layer has an interlayer dimension difference that is, for example, 0.5% shorter than the dimension of the metal foil only in the MD direction.

As shown in FIG. 1, the FMCL is provided at 0 degree in the TD direction (width direction), that is, at a right angle to the direction in which the FMCL advances, and the edge curved surface having a radius of curvature smaller than 0.5 mm ( It is assumed that the metal foil side of the FMCL of the present invention is bent and brought into contact with the edge of the first bar (edge) to pass through.

According to the FMCL of the present invention, in a flexible laminate obtained by laminating a metal layer and a plastic layer, the bending rigidity of the metal layer is 20 gcm or less, and the bending rigidity of the plastic layer is the bending rigidity of the metal layer. It is preferable to select a flexible metal plastic laminate characterized by being at least 1/500 of the above. This is because if the bending stiffness of the metal layer is 20 gcm or less and the bending stiffness of the plastic layer is 1/500 or more of the bending stiffness of the metal layer, the bending stiffness of the metal layer and the plastic layer is probably balanced. As a result, as shown in FIG. 2, a compressive stress acts on the entire metal layer, so that the metal layer has
Surprisingly, "shrinkage plastic deformation" occurs, this value
It can be 0.4% or more.

On the other hand, a tensile stress acts on the plastic thin film, but almost all of the action causes elastic deformation, so that it goes without saying that the dimensions are not substantially changed.

Based on these results, in the processed FMCL, only "plastic deformation due to metal shrinkage" remains as shrinkage of 0.4% or more, and the dimensional difference between metal foil and plastic thin layer is relatively Reduced to less than 0.1% and substantial dimensional difference
Essentially eliminated. That is, the metal is plastically deformed.
Since it shrinks by 4% or more, the remaining dimensional difference is only 0.5% -0.
4% = 0.1% or less.

In summary, in the first place, causing “thin plastic deformation of a stretch” in a thin metal layer is a well-known conventional technique since ancient times, and it can be achieved very easily without a person skilled in the art. Needless to say, it is not enough. However, the means employed by the present invention is quite different and is a surprising means of causing "plastic compression deformation" in thin metal layers.
On earth, how many could have devised to "compress" such a thin metal layer? To our knowledge, such means have not been suggested or described in any publication prior to the filing of the present application.

Although this is not the case in reality, FMCL
In the case where the plastic layer is longer than the metal layer, the above-described action is reversed by performing the above-mentioned processing of bringing the plastic layer into contact with the bar, and the plastic deformation of the metal layer is caused by elongation. And the dimensional difference in the arrowhead is substantially and substantially eliminated in the FMCL.

However, if the bending stiffness of the metal layer exceeds 20 gcm, the stiffness is too strong and the metal layer undergoes only bending deformation and cannot perform contraction deformation.On the other hand, if the bending stiffness of the plastic layer is less than 1/500, It is estimated that the rigidity of the metal layer is too strong with respect to the plastic layer, so that the metal layer also undergoes only bending deformation.

More specifically, when the bending stiffness of the metal layer and the plastic layer is out of the range specified in the present invention, as shown in FIG. 3, tensile stress and compressive stress are simultaneously generated in the metal layer. Therefore, the metal layer is "bent deformation"
When the metal layer is viewed as a whole, the dimension of the metal layer does not change, and the dimension does not change relative to the plastic layer. Therefore, it is presumed that there is no difference in correcting the dimensional difference between the two layers. Note that the means for simply causing the metal layer to undergo “bending plastic deformation” in the curled FMCL is merely an easy conventional technique, as is the case for stretching the plastic layer.

FM with dimensional difference only in MD direction for convenience of understanding
Considering CL, if the dimensions of the FMCL plastic thin layer are different from the metal foil in both the MD and TD directions,
The following may be performed. That is, although it depends on the degree of its length, generally, as shown in FIG.
0 to 80 degrees, preferably 5 to the TD direction (width direction)
If the metal foil or plastic layer side is brought into contact with a bar having an angle of ~ 60 degrees and the bar passes through in the MD direction under tension, a-
The metal layer of the FMCL contracts or stretches in the direction b, and then the FMCL
When a bar having an angle of 0 to -80 degrees, preferably -5 to -60 degrees in the TD direction is similarly passed, the metal foil contracts or stretches in the cd direction.

As a result, the metal foil contracts or stretches in all directions, and the dimensional difference is corrected in all directions.

Important items to be considered when correcting the interlayer dimensional difference of the FMCL of the present invention are the radius of curvature of the edge of the bar through which the metal foil passes, the angle of the bar with respect to the TD direction of the FMCL, and the length of the bar when passing through the bar edge. These are the magnitude of the tension acting on the FMCL, the passing speed, the number of passes, the bend angle shown in FIG. 1, and the like.

These are actually desired taking into account factors such as the dimensional difference between the metal layer and the plastic layer, the distribution of the dimensional difference in the MD and TD directions, the elastic modulus of the metal layer and the plastic layer, and the elastic displacement limit. Is controlled within the range.

The lower the temperature of the environment in which the treatment is performed, the higher the modulus of elasticity of the plastic layer, and the greater the stress of shrinking and deforming the metal foil. However, it is usually not necessary to cool below 0 degrees,
It is sufficiently effective at room temperature.

It should be noted that the present invention is characterized in that the radius of curvature of the edge of the bar is extremely small.
Specifically, it is extremely important that the thickness is less than 0.5 mm. The reason why the radius of curvature of the edge of the bar is less than 0.5 mm is not merely a numerical limitation. As shown in FIG. 2, when the thin FMCL passes through the curved surface of the edge, the shrinkage acting on the metal foil is reduced. This is technically extremely important in that the stress is increased to increase the degree of bending to the shrinkage plastic deformation region of the metal, and the metal is contracted by strong bending.

If the radius of curvature is 0.5 mm or more, the compressive stress acting on the metal foil can not reach the metal foil to the shrinkage plastic deformation area, or even if it can reach, the small deformation only for a short time Only slight bending deformation is practically given, and there is no help in eliminating substantial dimensional differences.

The bar has a radius of curvature of 0.5 mm at the contact point with the FMCL.
If it is less than the above, it goes without saying that the same effect can be obtained even if there are two or more contact portions with the FMCL.

Here, the bending stiffness of a plate or film is defined by the following equation.

However, D: bending stiffness (g · cm) E: Young's modulus (g / cm ² ) t: thickness (cm) ν: Poisson's ratio (−) The metal used in the present invention usually undergoes plastic deformation under stress. The exact Young's modulus of both layers is difficult to measure because of the viscoelastic nature of the resulting plastic. Therefore, in the present invention, for example, a tensile test of a metal layer or a plastic layer alone is performed at a predetermined tensile speed using a tensile tester, and the stress is determined by a load-displacement chart or by measuring strain using a strain gauge. 1kg /
The bending stiffness is defined by the above-mentioned bending stiffness equation using the so-called apparent Young's modulus in mm ² or more.

The metal layer used in the present invention is preferably one having good electric characteristics with low plastic deformation stress, such as copper, aluminum, nickel, gold, silver and alloys containing these, and particularly preferably copper and aluminum. And its bending stiffness is 20
Those having a value of not more than g · cm and not less than 0.001 g · cm are preferable.

Note that the metal layer may be a stacked metal layer, that is, a plurality of metal layers, as long as the combined bending rigidity is 20 g · cm or less. Usually, a metal layer having a thickness of about 10 to 100 μm is used.

It is also a preferred embodiment that these metal layers are subjected to an annealing recrystallization treatment to reduce the apparent Young's modulus to a specific range defined by the present invention.

On the other hand, the plastic layer used in the present invention may be any material such as polyethylene and vinyl chloride polypropylene.However, the main application of the FMCL in which the dimensional difference has been eliminated using the FMCL of the present invention is FPC. Considering
For the plastic layer that is the substrate, the tensile strength is 10
kg / mm ² or more, tensile modulus is preferably 100 kg / mm ² or more, tensile elongation is preferably 10% or more, glass transition point is 100 ° C. or more, and insulation is volume resistance. Preferably, the rate is 10 ¹⁰ Ωcm or more.

Examples of suitable plastics having these various characteristic values within preferred ranges include, for example, polyimide, polyaramid,
Polyamide imide, polyester, polyarylate, polyethersulfone, polyetheretherketone,
And polyphenylene sulphite.

In the present invention, the bending stiffness of the plastic layer is 1/500 or more of the bending stiffness of the metal layer, preferably 1/200 or more,
That is, it is preferably 10 g · cm or less. If the bending rigidity of the plastic layer is 1/500 or more, preferably 1/200 or more of the metal layer, the plastic layer may be composed of a plurality of layers. That is, such a plastic layer is selected.

Usually, a plastic layer having a thickness of about 10 to 100 μm is used.

The method of laminating the plastic layer and the metal layer is as follows: 1) dimensions of bonding the plastic film and the metal foil under heat and pressure using an adhesive; 2) flowing a polymer varnish directly on the copper foil. A method of spreading, drying and curing, 3) a method of directly extruding a molten polymer on a metal layer, and the like are preferably used.

[Action and effect]

It has a specific bending rigidity as described above according to the present invention.
When there is a dimensional difference between the metal layer and the plastic layer, the FMCL uses this to contact the metal layer with a bar having an edge curved surface having a radius of curvature smaller than 0.5 mm proposed by the present inventors. By applying a method of compressing and plastically deforming the metal layer by passing the metal layer under a tension state and performing an interlayer dimensional difference correction process, the interlayer dimensional difference between the metal layer and the plastic layer can be extremely easily reduced by 0.3%. In the following, there is an operational effect that an FMCL corrected to 0.1% or less can be obtained.

When such an interlayer dimension difference is corrected, the FMCL has excellent handling and workability during processing, as well as processing such as punching, cutting, patterning, circuit formation, etc. due to the interlayer dimensions. Since subsequent deformation, unevenness and wrinkles are reduced, and a stable flatness is maintained over time, it can be used in many applications such as flat cables, electromagnetic wave shielding materials, and packaging materials.

In particular, this FMCL is used for flexible printed circuit boards (FP
When used as C), the mutual positional relationship between points in the pattern on the metal layer is stable, and no deformation or unevenness occurs even after circuit formation after etching, mounting of parts, and connection with other substrates Interconnection is performed with high precision.

In other words, when the FMCL according to the present invention is a metal layer that is obtained by directly laminating a polyimide layer as a plastic layer without using an adhesive, the interlayer dimensional difference correction process is performed using the FMCL specified in the present invention. 0.1% dimensional difference between layers
The following FMCL can be used. Therefore, when the modified FMCL is used for FPC, since it does not include an adhesive layer, it is possible to obtain an FPC having excellent heat resistance, electrical properties, mechanical properties, and dimensional stability, and to achieve dimensional accuracy. It is suitable for forming a fine pattern which is a much severer pattern, and the use range is greatly expanded.

Example 1 Hereinafter, the present invention and its effects will be specifically described with reference to Examples and Comparative Examples of the present invention.

Example A flexural rigidity of 1.13 g cm (thickness: 35 μm, apparent Young's modulus at a tensile stress of 3 kg / mm ² , 2800 kg / mm ² , test conditions: temperature: 25 ° C., tensile speed: 1 mm / min) ,Four,
A non-volatile component obtained from 4'-diaminodiphenyl ether and pyromellitic acid and using N-methylpyrrolidone as a solvent 23
A polyamide acid varnish of weight% was cast and applied so that the polyimide film after imidization had a flexural rigidity of 0.1 g · cm. This was heated at 120 ° C. for 5 minutes and further at 180 ° C. for 4 minutes, and then heated in a nitrogen atmosphere (O ₂ : 1.5%) at 370 ° C. for 5 minutes to imidize, and an FMCL comprising a copper foil layer and a polyimide layer was formed. I got

A sample was cut out from the FMCL, and a polyimide film obtained by etching was measured.
A 093g · cm, was about 1/12 of the bending stiffness of the foil (thickness 32 [mu] m, Young mm apparent tensile stress 1.5 kg / mm ² of 2
90kg / mm ² , test condition is temperature 25 ℃, pulling speed 1mm / min).

A sample having a length of 600 mm was cut out from the FMCL, and the FMCL was marked from the plastic layer as shown in FIG. 5, and A ₁ C ₁ ,
The distance between A ₂ C ₂ , A ₃ C ₃ , A ₁ A ₃ , B ₁ B ₃ , and C ₁ C ₃ was 200.00 mm. Then, the FMCL was subjected to an etching treatment to remove copper, and the distance was measured again. The result was as follows.

As described above, the polyimide layer is 0.54 to copper foil layer
It was 0.56% smaller.

Applying a tension of 500 g / cm to this long FMCL with a copper foil layer in contact with a bar made of titanium alloy with a radius of curvature of 0.2 mm at the contact part, applying +40 degrees to TD (width direction). Interlayer dimensional difference correction processing was performed in which each slide was performed once at 40 degrees. The bending angle was 122 degrees.

The FMCL after the correction treatment had good uniformity without wrinkles or irregularities. The dimensional difference between the modified MD and TD layers was measured by the same measurement method as described above.

As is evident from the measurement results, the dimensional difference was uniform at 0.3% or less regardless of the direction and location, and the dimensional difference between the layers was corrected by about 0.3%.

Further, the FMCL that has been subjected to the interlayer dimensional difference correction processing is subjected to the second interlayer dimensional difference correction processing under the same conditions as the first time except that the break angle is 120 degrees, and then the same measurement method is used as described above. When the dimensional difference between the layers was measured, the dimensional difference between the copper foil and the polyimide film was 0.05 to 0.07%, and a very good FMCL could be obtained.

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.

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

Comparative Example 1 Flexural rigidity 177gcm (thickness 100μm, Young's modulus 19600kg / m
The polyimide film after imidization of the polyamic acid varnish of Example 1 on a stainless steel copper foil of m ² ) has a flexural rigidity of 0.6 g.
・ Covered and applied so as to obtain cm.

This was imidized under the heating conditions of Example 1 to obtain FMCL composed of a stainless steel foil layer and a polyimide layer.

A sample was cut out from the FMCL, and a polyimide film obtained by etching was measured.
It was 64 gcm, about 1/276 of the bending stiffness of the copper foil (apparent Young's modulus 290 at a thickness of 60 μm and a tensile stress of 1.5 kg / mm ^2).
kg / mm ² , test conditions are temperature 25 ° C and tensile speed 1mm / min).

A sample having a length of 60 mm was cut out from the FMCL, and the dimensional difference between the stainless steel foil layer and the polyimide layer was measured in the same manner as in Example 1. As a result, it was found that the difference was 0.73 to 0.78%.

This FMCL was subjected to the same interlayer dimensional difference correction processing as in Example 1, that is, 500 g /
As shown in FIG. 6, an inter-layer dimensional difference correction process was performed in which the film was slid once at +40 degrees and -40 degrees with a tension of cm.

The FMCL after the correction had a loose curl with the stainless steel foil layer inside, but no wrinkles or irregularities were observed.

When the dimensional difference between the MD and TD layers after the correction was measured by the same method as described above, it was 0.71 to 0.77%, and the dimensional difference was hardly corrected.

Further, after performing the second interlayer dimension difference correction processing under the same conditions as the first time except that the bending angle is 120 degrees, the FMCL that has been subjected to the interlayer dimension difference correction processing is used. When the dimensional difference was measured, the dimensional difference between both layers was 0.72
0.70.77, and the dimensional difference was not corrected.

Comparative Example 2 An electrolytic copper foil having a bending stiffness of 1.68 g · cm (thickness of 35 μm, apparent Young's modulus of 4200 kg / mm ² at a tensile stress of 3 kg / mm ² , and a test condition of a temperature of 25 ° C. and a tensile speed of 1 mm / min) Then, the polyamic acid varnish of Example 1 was cast and applied such that the polyimide layer after imidization had a flexural rigidity of 2 × 10 ⁻³ gcm.

This was imidized under the heating conditions of Example 1 to obtain FMCL composed of a copper foil layer and a polyimide layer.

A sample was cut out from the FMCL, and a polyimide film obtained by etching was measured.
06 × 10 ⁻³ g · cm, about 1/816 of the bending rigidity of copper foil (Thickness 9 μm, apparent Young's modulus at a tensile stress of 1.5 kg / mm ² 290 kg / mm ² , test conditions were: At a temperature of 25 ° C and a tensile speed of 1 mm / m
in).

A sample having a length of 600 mm was cut out from this FMCL, and the dimensional difference between the copper foil layer and the polyimide layer was measured in the same manner as in Example 1. The result was 0.53 to 0.57%.

This FMCL was subjected to the same interlayer dimension difference correction processing as in Example 1. The modified FMCL had a loose curl with the copper foil layer inside.

When the dimensional difference between the MD and TD layers after the correction was measured by the same method as described above, the difference was 0.50 to 0.56%, and the dimensional difference was hardly corrected.

Further, after the FMCL was subjected to the second interlayer dimensional difference correction process as in Example 1, the dimensional difference between the layers was measured by the same measuring method as described above. The result was 0.50 to 0.56%, and the dimensional difference was still corrected. I didn't.

Using this FMCL, draw a wiring pattern in the usual way,
When the FPC was manufactured, irregularities and wrinkles occurred, and the FPC was not normal.

[Brief description of the drawings]

FIG. 1 (a) is a plan view showing the arrangement of FMCLs and bars, and FIG.
FIG. 2 (b) is a longitudinal sectional view, FIG. 2 is a longitudinal sectional view illustrating a state in which the FMCL is undergoing plastic deformation due to shrinkage, and FIG. 3 is a state in which the FMCL is undergoing bending deformation. FIG. 4 is a plan view showing the arrangement of FMCLs and bars, and FIG.
The figure is a plan view showing reference points on the FMCL.

Continuation of the front page (56) References JP-A-52-115888 (JP, A) JP-A-58-199001 (JP, A) JP-A-61-287736 (JP, A)

Claims (1)

(57) [Claims] 1. A flexible laminate having a metal layer and a plastic layer laminated on each other and having a difference in interlayer dimension between the metal layer and the plastic layer, wherein the bending rigidity of the metal layer given by the following formula is 20 g. Cm or less, 0.001 gcm or more, and the flexural rigidity of the plastic layer is 1/500 or more of the flexural rigidity of the metal layer. An interlayer dimensional difference between the metal layer and the plastic layer, wherein the metal layer is brought into contact with an edge of a bar having an edge curved surface and passes under tension to compressively deform the metal layer. Is a flexible metal plastic laminate that has been modified. However, D: Flexural rigidity (g · cm) E: Young's modulus (g / cm ² ) t: Thickness (cm) ν: Poisson's ratio (−)