KR101450471B1 - Preparation method of flexible metal clad laminate using batch curing - Google Patents

Abstract

The present invention provides a method for manufacturing a flexible metal clad laminate using a batch curing method which includes the steps of: (i) manufacturing half-finished goods by spraying and drying a polyamic acid precursor resin which is changeable to a polyimide resin on a metal clad; and (ii) performing a curing process by a batch method to station the half-finished goods in a heating device for preset time. Wherein, a specific condition is satisfied. According to the present invention, when curing the half-finished goods coated with a polyimide layer by the batch method, the oxidation of the goods is prevented even though an anti-oxidation material is not used. Economic efficiency is improved by reducing material costs and simplifying a manufacturing process.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a flexible metal-clad laminate,

The present invention relates to a method of manufacturing a flexible metal foil laminate used for a printed circuit board, and more particularly, to a method of manufacturing a flexible metal foil laminate for use in a printed circuit board, And a manufacturing method of the flexible metal foil laminate is simplified.

In order to pursue the versatility and convenience of smart phones and electronic products, various characteristics are required for electronic materials. Among them, Flexible Copper Clad Laminate (FCCL) has a flexible characteristic, and its application range is gradually increasing from the connection part of slide phone, camera, and notebook while realizing a 3D model which was not previously thought. In order to secure competitiveness by accelerating growth of the global market, many competitors are implementing cost reduction by increasing production through process expansion and process improvement.

Flexible metal clad laminates, for example, copper clad laminate (FCCL), are made of polyamic acid or polyimide (PI) by using diamine and acid dianhydride. The resin is coated on a copper foil and dried to form a semi-finished product, followed by curing to produce a flexible copper clad laminate. At this time, the method of curing polyimide is divided into two types.

The first is to produce polyimide (PI) by polymerizing polyamic acid using line speed and temperature (eg infrared heat) as an in-line curing method. This method does not use the anti-oxidation auxiliary material of the product in the production of the product because the initial facility cost is large, but oxidation does not occur on the copper foil surface during the volatilization of the solvent. Therefore, the material cost of the product is reduced.

The second is a batch heat curing method. The dried semi-finished product is put into a batch oven, and then the polyamic acid is polymerized using the temperature rise time and the temperature to complete the curing with polyimide. In this method, the initial equipment cost is low, whereas when the semi-finished product wound in a roll-state is unwound without auxiliary materials, oxidation occurs. Therefore, it is necessary to use auxiliary materials that prevent oxidation and prevent oxidization, There is a drawback that it takes a lot of time. Such auxiliary materials include mesh-net, polyimide (PI) film, and copper foil. Mesh-mesh is good for recyclability, but it is difficult to use because mesh network structure is transferred to the product, and polyimide (PI) film is good for recycling, but sticky due to static electricity occurs And problems occur in the appearance of the product. The copper foil can improve the above two problems, but the recycling rate is low and the material cost is increased in the production of the product. That is, since the auxiliary material copper foil is interposed between the products, the annealing is promoted while transferring the oxidized portion of the product to the auxiliary material copper foil, and the copper foil used as the auxiliary material during the process is changed So that the existing stiffness is lowered. Therefore, when recycling the copper material of the subsidiary material, the appearance of the product may cause wrinkles and poor appearance. Oxidation occurs when the copper foil is not used. Oxidation generated at this time may cause various types of defects in the manufacture of the flexible circuit board. For example, the surface treatment and plating process may not be smooth due to oxidation of the copper foil, which may lead to breakage of the electrical properties of the final product.

SUMMARY OF THE INVENTION The present invention has been conceived in order to solve the above-mentioned problems, and it is an object of the present invention to provide a polyimide resin composition for use in batch curing a polyimide resin composition comprising a polyimide resin solid content, a metal foil thickness, a polyimide resin layer thickness coated on a metal foil, It is noted that oxidation of the flexible metal foil laminated plate is prevented even when the anti-oxidation auxiliary material is not used in the same manner as the continuous production curing (In-line cure) method.

Accordingly, it is an object of the present invention to provide a novel manufacturing method of a flexible metal-clad laminate that uses a batch curing method that is more competitive than a continuous production curing (In-Line Cure) .

(I) applying a polyimide precursor resin convertible to a polyimide resin onto a metal foil and drying to form a semi-finished product; And (ii) curing the semi-finished product by a batch method in which the substrate is allowed to stand in a heating apparatus for a predetermined time, wherein the condition of the following formula (1) is satisfied.

[Equation 1]

(2.0 ≤ Y ≤ 5.0)

(2.0? Y? 5.0)

In this formula,

K is the product thickness of the final flexible metal-clad laminate (FCCL), which is the thickness of the copper foil / the thickness of the polyimide (PI)

T is the thickness of the polyimide layer before curing - thickness of the semi-finished polyimide coating layer,

V is the residual amount of the organic solvent after curing by the arrangement method,

N is the solid content in the synthesis of polyimide resin.

According to a preferred embodiment of the present invention, in the step (ii), the semi-finished product is put into a heating device to cure the semi-finished product, and the anti-oxidation auxiliary material of the semi-finished product can be used unused.

Here, the antioxidant auxiliary material is preferably selected from the group consisting of a mesh net, a polyimide film, and a copper foil.

In the present invention, in the step (i), the polyimide precursor resin is a polyamic acid solution obtained by imidization reaction with an acid dianhydride and a diamine, wherein the solid content is in the range of 10 to 30 wt% . Preferably, the polyamic acid solution further includes an inorganic filler that reduces a thermal expansion coefficient (CTE) between the metal foil and the polyimide layer.

According to another preferred embodiment of the present invention, the thickness of the metal foil is preferably in the range of 6 to 70 mu m. The thickness of the polyimide precursor resin layer applied in the step (i) is preferably in the range of 6 탆 to 50 탆.

According to another preferred embodiment of the present invention, drying of the step (i) is carried out in the range of 150 to 200 ° C, and the curing of the step (ii) is carried out in the range of 300 to 400 ° C.

The present invention also provides a flexible metal foil laminate produced by the above-described method. Here, the metal foil is preferably a copper foil.

In the present invention, the process technology for controlling the polyimide resin formation with high solid content, the coating thickness of the polyimide resin layer coated on the copper foil, and the thickness of the semi-finished product is developed, and oxidation of the flexible metal foil laminate As a result, productivity and economical efficiency can be improved due to reduction of material cost and simplification of manufacturing process.

Hereinafter, the present invention will be described in detail.

The present invention relates to a flexible metal-clad laminate capable of securing the simplicity and economical efficiency of the manufacturing process by improving the oxidation defects equivalent to the continuous production curing (in-line cure) method, applying the batch curing method, And to provide a novel manufacturing method.

That is, in conventional batch curing, the main cause of the oxidation is the residual amount of the organic solvent. However, not all of the oxidation is completely solved by the residual amount of the organic solvent, and the curl of the semi-finished product must be improved at the same time as the residual amount of the organic solvent.

For this purpose, in the present invention, a batch curing method is employed as a heat treatment method for curing with polyimide (PI), wherein the thickness of the copper foil constituting the flexible metal foil laminates, the initial coating thickness of the polyimide coating layer before curing, (V / C) of the organic solvent after curing, the solid content in the polyamic acid, and the like.

By adjusting the constituent elements of the flexible metal foil laminate to specific conditions as described above, oxidation of the product can be prevented even without using the conventional antioxidant auxiliary materials. Therefore, as in the case of the continuous production curing (In-Line Curing), it is possible to increase the economic efficiency and productivity by securing the conditions for producing the products without using the subsidiary materials.

≪ Manufacturing method of flexible metal foil laminates &

Hereinafter, a method of manufacturing the flexible metal film-laminated board according to the present invention will be described. However, the present invention is not limited to the following production methods, and the steps of each process may be modified or selectively mixed if necessary.

The method for fabricating a flexible metal foil laminate according to the present invention can be manufactured by forming a polyimide precursor resin layer on a metal foil and then completely curing the formed resin layer with polyimide (PI) by batch curing.

In one preferred embodiment of the above production method, (i) a polyimide precursor resin convertible to a polyimide resin is coated on a metal foil and dried to produce a semi-finished product; And (ii) curing the semi-finished product by a batch method in which the semi-finished product is allowed to stand in the heating apparatus for a predetermined period of time. Here, the step (ii) is characterized by curing while satisfying the condition of the formula (1).

Hereinafter, the manufacturing method of the FCC laminated board will be described in more detail as follows.

(1) Production of a semi-finished product having a polyimide resin layer formed on a metal foil

In this step, a polyamic acid solution is coated on the metal foil a plurality of times and then dried to produce a semi-finished product.

The metal foil is not particularly limited as long as it is a metal having conductivity and ductility. For example, copper, tin, gold, or silver, preferably copper (Cu). In the case of copper foil, it may be a rolled copper foil or an electrolytic copper foil.

The thickness of the metal foil is not particularly limited, but is preferably in the range of 6 to 70 mu m, more preferably in the range of 9 to 35 mu m.

In the present invention, a polyamic acid solution can be used as the polyimide precursor resin which can be converted into the polyimide resin to be coated on the metal foil.

The polyamic acid solution may be obtained through an imidation reaction of a dianhydride (dianhydride) and a diamine according to a conventional method known in the art, and more specifically, an aromatic tetracarboxylic dianhydride and an aromatic The diamine is dissolved in a polar solvent to prepare a polyamic acid solution.

Non-limiting examples of the dianhydride used for preparing the polyamic acid solution include pyromellitic dianhydride (PMDA), 3,3 ', 4,4'-biphenyltetracarboxylic dianhydride 3,3 ', 4,4'-biphenyltetracarboxylic dianhydride (BPDA), 3', 4,4'-benzophenonetetracarboxylic dianhydride (BTDA) , 4,4'-oxydiphthalic anhydride (ODPA), 4,4 '- (4,4'-isopropylidene diphenoxy) -bis- (phthalic anhydride) (BPADA: 4,4'-isopropylidenediphenoxy) -bis (phthalic anhydride), 2,2'-bis- (3,4-dicarboxyphenyl) hexafluoropropanedianhydride (6FDA: 2,2 ' ethylene glycol bis (anhydro-trimellitate), hydroquinone diphthalic anhydride (ethylene glycol bis (anhydro-trimellitate)), HQDEA: Hydroquinone diphthalic anhydride, 3,4,3 ', 4'-diphenylsulfone tetracarboxylic dianhydride (DSDA: 3,4,3', 4'-diphenylsulfonetetracarboxylic dihydride) . Preferably, at least one of the above-mentioned dianhydrides is selected and mixed.

Also, non-limiting examples of the diamine include p-phenylenediamine (p-PDA), m-phenylene diamine (m-PDA), 4,4'-oxydianiline 4,4'-ODA: 3,4'-oxydianiline, 2,2-bis (4-4 [aminophenoxy] -phenyl) propane (BAPP: phenyl) propane, 2,2'-dimethyl-4,4'-diaminobiphenyl (m-TB-HG) Aminophenoxy) benzene (TPER: 1,3-bis (4-aminophenoxy) benzene), 2,2- (4-aminophenoxy) phenyl sulfone, 4,4'-diamino benzanilide, 4,4'-bis (4-aminophenoxy) biphenyl (4,4'-bis (4-aminophenoxy) biphenyl), or a mixture of at least one of these. Preferably, at least one of the above-mentioned diamines is selected and mixed.

The polyamic acid solution of the present invention may further include an appropriate amount of an inorganic filler to increase the dimensional stability of the flexible metal foil laminate produced by reducing the difference in CTE between the formed polyimide resin layer and the metal foil.

Generally, the coefficient of thermal expansion of the polyimide resin is 20 to 50 ppm, while the coefficient of thermal expansion of the copper foil is 18 ppm. Therefore, the final flexible metal foil laminate may be bent due to the difference in the CTE. The inorganic filler can reduce the difference in the coefficient of thermal expansion (CTE) between the polyimide resin and the copper foil, thereby improving the warping property and the low expansion of the final product, and effectively improving the mechanical properties and the low stress .

Non-limiting examples of usable inorganic fillers include talc, mica, silica, calcium carbonate, magnesium carbonate, clay, calcium silicate ), Titanium dioxide, antimony oxide, glass fiber, or a mixture thereof. The amount of the inorganic filler to be used is preferably at least 10% by weight and less than 25% by weight based on 100% by weight of the total amount of the polyamic acid preparation reactant, but is not particularly limited thereto.

The solvent used in the polyamic acid solution according to the present invention is not particularly limited as long as it is well known in the art, and examples thereof include N-methylpyrrolidinone (NMP), N, N-dimethylacetamide N-dimethylacetamide (DMAc), tetrahydrofuran (THF), N, N-dimethylformamide (DMF), dimethylsulfoxide (DMSO), cyclohexane, , Acetonitrile, and the like. These may be used alone or in combination of two or more.

It is also within the scope of the present invention to add small amounts of dianhydrides or other diamines or other additive compounds other than the exemplified compounds as needed.

In the present invention, on the other hand, , It is necessary to develop polyimide resin with high solid content capable of producing mass production products. An important factor in the synthesis of such a polyimide resin is the rate of change in molarity and viscosity, and in terms of properties, flexibility and adhesion must be increased.

The polyamic acid solution [varnish] according to the present invention preferably has a viscosity of 3,000 to 50,000 cps, but is not limited thereto. The content of the solid content in the polyamic acid solution may be in the range of 10 to 30% by weight, preferably in the range of 13 to 25% by weight, based on 100% by weight of the whole solution. If the solid content satisfies the above-described range, the coating property is good, and therefore, the workability is excellent and the effect of alleviating the semi-finished product curl phenomenon for improving the oxidation can be exhibited. Here, the solid content means the total concentration of the solid components excluding the organic solvent, that is, the organic resin component and the inorganic solid component.

The thickness of the polyamic acid solution to be coated on the metal foil may vary depending on the concentration, but the thickness of the polyimide resin layer after the imidization reaction is finally 6 To 50 m, preferably 9 to 25 m.

The polyamic acid solution of the present invention may contain a plasticizer, an antioxidant, a flame retarding agent, a dispersing agent, a viscosity adjusting agent, a leveling agent, or other conventional additives, etc. insofar as it does not significantly impair the objects and effects of the present invention It can be added appropriately and used.

In the polyamic acid solution of the present invention, the organic resin component, the inorganic solid component added as needed, and the organic solvent may be mixed using a pot mill, a ball mill, a homogenizer, a super mill or the like.

The above-mentioned method of applying the polyamic acid solution varnish onto the metal foil can be carried out by a conventional coating method known in the art such as a dip coating, a die coating, a roll coating, a comma coating , Bar coating, casting, or a combination thereof.

Also, the method of drying the applied polyamic acid layer may be appropriately adjusted within a range of ordinary temperature and pressure known in the art. For example, a method in which a polyamic acid solution is coated on a metal foil and then dried at 150 to 200 ° C to produce a semi-finished product.

The thickness of the polyimide precursor resin layer applied to the step may be in the range of 2 to 7 times, preferably in the range of 2 to 5 times, when the thickness of the dried polyimide precursor resin layer of the semi- . If it is out of the above range, there is a problem that the semi-finished product Curl is severe and appearance defects occur or the line speed is lowered due to a large amount of solvent remaining.

(2) batch-curing the semi-finished product to prepare an imidation reaction

In this step, the imidization reaction is completed through batch curing of the dried semi-finished product to produce a flexible metal foil laminate.

Here, batch curing is one of heat treatment methods for converting a polyamic acid precursor resin into a polyimide resin. Instead of using a device that continuously passes through each of the baths and processes, . For example, the polyimide precursor resin is coated and dried, and then the polyimide precursor resin is allowed to stand in the high-temperature heating furnace for a predetermined time to perform the imidation reaction.

Conventionally, a batch curing method is a method in which a semi-finished product rolled in a roll state is injected into a heating device to cure it, and since oxidation occurs when the roll form is released, auxiliary materials such as a mesh net, Polyimide film and copper foil should be used. Therefore, while the initial equipment cost is low, the cost of the material is increased.

In contrast, in the present invention, the thickness of the copper foil constituting the flexible metal foil laminate, the initial coating thickness of the polyimide coating layer before curing, the thickness of the semi-finished polyimide layer, the residual amount of the organic solvent in the semi-finished product (V / C) By adjusting the contents to a specific range, oxidation of the product is prevented even when the conventional batch curing process auxiliary material is not used in the batch curing, so that economical efficiency and simplification of the manufacturing process can be achieved.

As described above, the optimal condition of each component constituting the flexible metal film-clad laminate of the present invention is expressed by the following equation (1).

[Equation 1]

, 2.0 ≤ Y ≤ 5.0

, 2.0? Y? 5.0

In this formula,

K is the product thickness of the final flexible metal-clad laminate (FCCL), which is the thickness of the copper foil / the thickness of the polyimide (PI)

T is the thickness difference (initial polyimide coating layer thickness before curing - polyimide thickness of semi-finished product)

V is the remaining amount of solvent after oven drying,

N is the solid content of the polyimide resin.

In the formula (1) according to the present invention, when the y value is 2.0 or more, the oxidation rate of the product is lowered. On the other hand, when the y value exceeds 5.0, a curl phenomenon occurs in the semi-finished product, The work becomes difficult. In addition, there are many defects, resulting in poor workability and cost reduction. Accordingly, the y value is preferably in the range of 2.0 to 5.0, more preferably in the range of 2.0 to 3.0. When the y value is 1.5 or less, a large amount of oxidation occurs, resulting in a low yield.

Particularly, in the present invention, as the K (final product thickness) and N (solid content) are higher, the subsidiary materials can be removed as T (difference in thickness of the polyimide coating layer) and V become smaller. Here, in each preferred range, K ranges from 0.2 to 1.5, N ranges from 10 to 25, T ranges from 20 to 80, and V ranges from 12 to 24.

The batch curing method and conditions thereof according to the present invention can be suitably adjusted within the range of ordinary temperature and pressure known in the art. For example, it is preferably carried out at a temperature of 300 to 400 ° C for 4 to 15 hours. The heating apparatus used in the batch curing system may also be any conventional apparatus known to those skilled in the art. Such a conventional heating apparatus (heating furnace) may employ a hot air furnace in an inert gas atmosphere such as nitrogen.

In the batch curing system, the maximum temperature is 300 ° C to 400 ° C, the nitrogen feed rate is 0.7 ° C / min to 1.6 ° C / min, the heating apparatus size is 200 ° to 400 ° . However, it is not particularly limited.

It can be seen that the product of the flexible metal foil laminate of the present invention manufactured as described above is ensured without application of the auxiliary materials for batch curing (see Table 3 below).

Further, the present invention provides a flexible metal foil laminate (FCCL) manufactured by the above-described method and a flexible printed circuit board comprising the same.

The flexible printed circuit board can contribute to high performance and long life of various electronic devices because the flexible printed circuit board continuously exhibits various performances such as excellent heat resistance, insulation, flexibility, flame resistance, and chemical resistance due to polyimide.

Hereinafter, examples and experimental examples of the present invention will be described in detail. However, the following examples are only the preferred embodiments of the present invention, and the present invention is not limited to the following examples and experimental examples.

[Example 1]

Preparation of polyamic acid solution

166 ml of N-methylpyrrolidone (NMP) was added to a four-neck reaction vessel equipped with a thermometer, a stirrer, a nitrogen inlet, and a power dispensing funnel. To this solution, 5.34 g (0.0657 mol) of P-phenylenediamine (p-PDA) and 2.58 g (0.0168 mol) of 4,4'-oxydianiline (ODA) were added and stirred to dissolve completely at 25 ° C. To this solution was slowly added 16.32 (0.0739 mol) of 3,3 ', 4,4'-biphenyltetracarboxylic dianhydride (BPDA) and pyromellitic dianhydride (PDMA) 1.37 (0.0082 mol) While stirring to obtain a polyamic acid solution having a viscosity of 20,000 cps.

[Examples 2 to 3]

The polyamic acid solution was prepared in the same manner as in the preparation of the polyamic acid solution of Example 1, except that the contents of BPDA, PMDA, p-PDA and ODA were adjusted as shown in Table 1 below.

Example 1 Example 2 Example 3 BPDA 16.62 g 21.74 g 29.41 g 0.0739 mol 0.0739 mol 0.0739 mol PMDA 1.37g 1.79 g 2.42 g 0.0082mol 0.0082mol 0.0082mol p-PDA 5.43 g 7.10 g 9.61 g 0.0657 mol 0.0657 mol 0.0657 mol ROOM 2.58 g 3.37 g 4.56 g 0.0168 mol 0.0168 mol 0.0168 mol NMP 174 g 166 g 154 g Solids content 13.00% 17.00% 23.00%

[ Comparative Example 1]

Semi-finished product manufacturing process

The polyimic acid solution synthesized in Example 1 was used to set the coating thickness to 12 탆 for a copper foil to an initial thickness of 63 탆 to prepare a final PI thickness 12 탆 product. The coating drying (L / S, temperature, air flow rate) conditions were adjusted so that the solvent content of the semi-finished product was 15%. The results are set as shown in Table 2 below.

[Comparative Examples 2 to 9]

The initial coating thickness, the final PI thickness and the solvent content of the polyamic acid solution obtained in Examples 1 to 3 were changed in accordance with the setting range of Table 2 below by changing the coating drying (L / S, temperature, air volume) CF-150 and IPC-TM-650 2.1.5A, respectively.

[Experimental Example 1: Appearance Evaluation]

Each of the flexible copper-clad laminates produced in Examples 1 to 3 and Comparative Examples 1 to 9 was subjected to a batch curing process under conditions of metal foil stamping, wrinkling, oxidation; Wrinkles, scratches, etc. of the polyimide layer were evaluated. Good results were evaluated as OK, and in the case of defects, NG was indicated. The appearance evaluation results of such a flexible copper clad laminate are shown in Table 3 below.

At this time, the experimental data of the flexible copper-clad laminates were integrated and summarized to verify the equation (1) according to the present invention, and the Y value securing the product quality without application of the subsidiary material was obtained.

(1)

(One)

(K: product thickness, T: thickness variation, V: solvent content, N: solid content)

K
(Product Specification) T
(Thickness change) V
(Sol. Content) N
(Solid content) Y
(Result) Oxidation improvement
result Comparative Example 1 k2 t2 v2 Example 1 1.83 NG Comparative Example 2 k3 t2 v2 2.29 OK Comparative Example 3 k3 t2 v3 1.87 NG Comparative Example 4 k2 t1 v1 Example 2 3.43 OK Comparative Example 5 k2 t3 v2 1.10 NG Comparative Example 6 k2 t1 v2
Example 3 2.91 OK Comparative Example 7 k1 t1 v2 2.18 OK Comparative Example 8 k1 t1 v3 1.64 NG Comparative Example 9 k3 t3 v3 2.71 OK

As a result of the experiment, it was found that when the Y value is 2.0 or more, the oxidation can be improved without using the auxiliary material in the batch curing system. Accordingly, in the present invention, it is possible to confirm the possibility of mass production of a new batch curing facility capable of achieving the productivity improvement effect equivalent to the continuous production curing (line curing) method and the cost reduction, by securing the optimum conditions to be controlled by the batch curing method there was.

Claims (10)

(i) applying and drying a polyimide precursor resin convertible to a polyimide resin on a metal foil to produce a semi-finished product; And
(Ii) a step of curing the semi-finished product by a batch method in which the substrate is allowed to stand in a heating apparatus for a predetermined time, and the condition of the following formula (1) is satisfied:
[Equation 1]

, 2.0? Y? 5.0
In this formula,
K is the product thickness of the final flexible metal-clad laminate (FCCL), which is the thickness of the copper foil / the thickness of the polyimide (PI)
T is the thickness of the polyimide layer before curing - thickness of the semi-finished polyimide coating layer
V represents the residual amount of the organic solvent after curing by the arrangement method
N is the solid content in the synthesis of polyimide resin. The manufacturing method of a flexible metal film-laminated board according to claim 1, wherein the step (ii) is a step of putting the semi-finished product in a heating device to harden the semi-finished product, wherein the anti-oxidation auxiliary material of the semi-finished product is not used. The method according to claim 2, wherein the anti-oxidation auxiliary material is selected from the group consisting of a mesh net, a polyimide film, and a copper foil. The polyimide precursor resin according to claim 1, wherein the polyimide precursor resin is a polyamic acid solution obtained by imidization reaction with an acid dianhydride and a diamine, wherein the polyimide resin solid content is 10 to 30 wt% %. ≪ / RTI > The method of claim 4, wherein the polyamic acid solution is selected from the group consisting of talc, mica, silica, calcium carbonate, magnesium carbonate, clay, calcium silicate, titanium oxide, antimony oxide, And an inorganic filler selected from the group consisting of a mixture of two or more thereof, and a mixture thereof. The method according to claim 1, wherein the thickness of the metal foil is in the range of 6 to 70 μm. The method according to claim 1, wherein the metal foil is copper, tin, gold, silver, or an alloy thereof. The method according to claim 1, wherein the thickness of the polyimide precursor resin layer applied in the step (i) ranges from 2 to 7 times the thickness of the polyimide precursor resin layer of the semi-finished product. The method according to claim 1, wherein the drying temperature in step (i) is in the range of 150 to 200 ° C,
Wherein the curing temperature of step (ii) is in the range of 300 to 400 占 폚. A flexible metal foil laminate produced by the method of any one of claims 1 to 9.