WO2010050759A2

WO2010050759A2 - Flexible metal-clad laminate and a method of manufacturing the same

Info

Publication number: WO2010050759A2
Application number: PCT/KR2009/006295
Authority: WO
Inventors: Weonjung Choi; Seunghoon Jung; Byoungwook Jo; Daenyoun Kim
Original assignee: Sk Energy Co., Ltd.
Priority date: 2008-10-31
Filing date: 2009-10-29
Publication date: 2010-05-06
Also published as: WO2010050759A3; KR20100048474A; TWI494214B; TW201032999A

Abstract

Disclosed is a flexible metal-clad laminate. More specifically, disclosed is a flexible metal clad laminate including'- a first polyimide layer that is positioned on one surface of a metal foil and has glass transition temperature of 300 to 500 °C; a second polyimide layer that is positioned on one surface of the first polyimide layer and has a linear thermal expansion coefficient of 1 to 20 ppm/K; and a thermoplastic polyimide layer that is positioned on one surface of the second polyimide layer, whereby the flexible metal-clad laminate has an excellent exterior after imidization, is not curled after and before etching, and has excellent adhesive strength with a metal foil and excellent dimensional stability after etching.

Description

[DESCRIPTION] [Invention Title]

Flexible Metal-clad laminate and a method of manufacturing the same [Technical Field]

<ι> The present invention relates to a flexible metal-clad laminate and a method of manufacturing the same, and more specifically to a flexible metal- clad laminate used for manufacturing a printed circuit board and a method of manufacturing the same. [Background Art]

<2> A flexible metal-clad laminate used for manufacturing a flexible printed circuit board, which is a laminate of a conductive metal foil and an insulating resin, may perform micro circuit processing and may be curled at a narrow space such that its use has been increased as the miniaturization and lightweight of electronic devices are progressed.

<3> The flexible metal clad laminate is classified into a two-layer type and a three-layer type. The three-layer type using adhesives has a problem of the degradation in heat resistance and flame resistance and a change in dimension during a heat treatment process as compared to the two-layer type. Thereby, in manufacturing the flexible printed circuit board, the current tendency generally uses the flexible metal clad laminate in the two-layer type rather than the three-layer type.

<4> Due to the current tendency of lightweight, slimness, and miniaturization of the circuit, the use of double-sided metal clad laminate is being increased. The double-sided metal clad laminate is generally manufactured by laminating thermoplastic polyimide on an outermost layer of polyimide resin used as the insulating layer and the metal foil. In this case, there is problem in that the curling of the flexible copper clad laminate after and before etching occurs due to the existence of the thermoplastic polyimide resin.

<5> KR Laid-Open Patent Nos. 10-2004-0084028 and 2006-0129081, or 2003- 0079991 disclosed methods that apply and dry polyimide precursor resin several times in order to improve adhesive strength with a metal foil and control the curling after and before etching metal layer. The disclosed methods use thermoplastic polyimide (TPI) as polyimide resin, which is directly casted on the metal foil, to maintain high adhesive strength with the applied metal foil. However, there are problems in that KR Laid^~0pen Patent No. 10-2004-0084028 easily causes the badness of external appearance, such as the blistering on a polyimide surface and delamination between polyimid resin layers or between polyimide resin layer and the metal foil, etc, since the thermoplastic polyimide resin contacting with the metal foil usually has low glass transition temperature of about 200 to 250 ^°C , KR Laid Open No. 2006-0129081 needs the thinness of the thermoplastic polyimide layer so that a linear thermal expansion coefficient of polyimide resin meets a linear thermal expansion coefficient of metal, and KR Laid Open No. 2003- 0079991 increases the usage of expensive thermoplastic polyimide. [Disclosure] [Technical Problem]

<6> To solve the above-mentioned problems. An object of the present invention is to provide a flexible metal clad laminate that has excellent external appearance after imidization, does not cause curling after and before etching, and has excellent adhesive strength between polyimide resin layer and metal foil and dimensional stability after etching.

<7> In addition, another object of the present invention is to provide a metal clad laminate that may be used as a double-sided metal clad laminate by laminating a single-sided metal clad laminate with a metal foil and a method of manufacturing the same. [Technical Solution]

<8> To achieve the above object, the present invention provides a flexible metal clad laminate including: a first polyimide layer that is positioned on one surface of a metal foil and has glass transition temperature of 300 to 500 ^°C ; a second polyimide layer that is positioned on one surface of the first polyimide layer and has a linear thermal expansion coefficient of 1 to 20 ppm/K; and a thermoplastic polyimide layer that is positioned on one surface of the second polyimide layer.

<9> The present invention provides a method of manufacturing a flexible metal-clad laminate including: (a) applying and drying polyamic acid solution that is positioned on one surface of a metal foil and has the glass transition temperature of 300 to 500 °C after imidization and then forming a first polyimide layer; (b) applying and drying polyamic acid solution that is positioned on one surface of the formed first polyimide layer and has a coefficient of linear thermal expansion of 1 to 20 ppm/K after imidization and then manufacturing a second polyimide layer; (c) applying and drying polyamic acid solution that is positioned on one surface of the formed second polyimide layer, has glass transition temperature of 200 °C ≤ Tg < 300 ^°C after imidization, and has a coefficient of linear thermal expansion of 30 to 200 ppm/K, and then forming a thermoplastic polyimide layer; and (d) imidizing the manufactured laminate by performing heat treatment at 0 to 500 0C.

<io> Hereinafter, an exemplary embodiment of the present invention will be described in detail. In describing the present invention, a detailed description of related known functions or configurations will be omitted so as not to obscure the subject of the present invention.

<ii> Terms used in the specification, "about", "substantially", etc., which represents a degree, are used as meanings at numerical values or approaching numerical values when inherent tolerances of preparation and material are presented to the above-mentioned meanings and they are used to prevent unconscientious invaders from unfairly using the contents in which accurate or absolute numerical values are disclosed in order to help the understandings of the present invention, are disclosed.

<i2> The present invention relates to a flexible metal-clad laminate that includes CD a polyimide layer (hereinafter, referred to as 'first polyimide layer') having glass transition temperature (Tg) of 300 to 500 ^°C , (2) a polyimide layer (hereinafter, referred to as 'second polyimide layer') that is positioned on one surface of the above-mentioned first polyimide layer and has a coefficient of linear thermal expansion of 1 to 20 ppm/K, © a thermoplastic polyimide resin layer (hereinafter, referred to as 'thermoplastic polyimide layer') existing on one surface of the second polyimide layer and a double-sided flexible metal-clad laminate obtained by laminating the above-mentioned flexible metal-clad laminate with metal foil.

<i3> The laminate according to the present invention has an excellent exterior after thermal imidization, is not curled after and before etching, and has excellent adhesive strength between polyimide layer and a metal foil and excellent dimensional stability after etching. In addition, the laminate manufactured according to the present invention may be manufactured into the double-sided metal-clad laminate by laminating another metal foil on one surface of the thermoplastic polyimide layer.

<i4> The first polyimide layer positioned on one surface of the metal foil has a coefficient of linear thermal expansion of 5 to 40 ppm/K. Preferably, the first polyimide layer has a higher coefficient of linear thermal expansion within the range of 5 to 25 ppm/K as compared to the second polyimide layer. In this case, the adhesive strength with the applied metal foil may be stably maintained to at least 1.0 kgf/cm, more preferably 1.0 to 3.0 kgf/cm and the curling of the laminate due to the thermoplastic polyimide layer having a high coefficient of linear thermal expansion may be removed since stress curled inward the metal foil due to the difference in the coefficient of linear thermal expansion with the second polyimide layer is formed.

<15> As the first polyimide layer contacting with the metal foil, a polyimide resin having a glass transition temperature of 300 °C or more, more preferably 300 to 500 ⁰C is used. Generally, the thermoplastic polyimide resin is used as the first polyimide layer. In this case, there are problems in that the badness of external appearance, such as the blistering on a polyimide surface and delamination between the polyimid resin layers or between the polyimide resin layer and the metal foil, etc., due to a low glass transistion temperature, occurs. Therefore in order to prevent the exterior badness during the imidization process, the low thermal expansion polyimide resin having a glass transition temperature of 300 ^°C or more should be used as the first polyimide layer contacting with the metal foil.

<i6> The second polyimide layer positioned on one surface of the first polyimide layer has a coefficient of linear thermal expansion of 20 ppm/K or less, more preferably 1 to 20 ppm/K. To overcome the high coefficient of linear thermal expansion of the thermoplastic polyimide, the polyimide resin having a low coefficient of linear thermal expansion should be used as the second polyimide resin, and this makes the coefficient of linear thermal expansion of the entire polyimide resin similar to the coefficient of linear thermal expansion of the metal foil. Thereby, the curling after and before the etching of the laminate is prevented and the dimensional change after the etching may be controlled to -0.1% to +0.1%, more preferably -0.05% to +0.05%.

<i7> As materials forming the above-mentioned polyimide layer, tetracarboxyl ic acid di anhydride and diamino compound may be usually used, but the materials are not limited thereto.

<i8> As the tetracarboxyl ic acid dianhydride to exhibit the low thermal expansion, pyromellitic dianhydride, 3,3' ,4,4'-biphenyltetracarboxylic acid dianhydride, 3,3' ,4,4'-benzophenonetetracarboxylic acid dianhydride, etc., are preferably used.

<i9> In addition, as the diamino compound, 4,4'-diaminophenyl ether, p- phenylenediamine, 4,4'-thiobisbenzenamine, etc., are preferably used.

<20> The low thermal expansion polyimide resin according to the present invention includes a polyimide resin of the following Formula 1. <2 I > [Formula 1]

<23> Among all the components of [Formula 1] , 0.5 < m < 1.0 and 0 ≤ n ≤ 0.5, m+n=l.

<24> X and Y included in [Formula 1] each is aromatic dianhydride compound independently selected from the following structure.

<25> <26> Meanwhile, if the compositions of the thermoplastic polyimide resin have sufficient fluidity in at least glass transition temperature, any compositions may be used. Further, compositions having fluidity by pressure may be used. In addition, thermoplastic polyimide resins manufactured from at least two dianhydride monomers and at least two diamine monomers as well as thermoplastic polyimide resins manufactured from a single dianhydride monomer and a single diamine monomer are included.

<27> The thermoplastic polyimide layer of the present invention may have the glass transition temperature of 200 °C ≤ Tg ≤ 300 °C and the thermal expansion coefficient of 30 to 200 ppm/K. More specifically, the thermoplastic polyimide resin forming the thermoplastic polyimide layer of the present invention preferably includes 30 to 100 wt% of repeating unit that includes W and Z of the following [Formula 2] (hereinafter, referred to as 'thermoplastic repeating unit'). When the fraction of the thermoplastic repeating unit does not reach 30%, the fluidity of the thermoplastic polyimide layer is insufficient, such that thermal laminating is impossible or the adhesive strength with the laminated metal is low after manufacturing the double-sided metal clad laminates. Therefore, the fraction of the thermoplastic repeating unit should be carefully controlled considering the glass transition temperature of the thermoplastic polyimide layer. When considering the laminating process to manufacture the double-sided metal clad laminates, the glass transition temperature of the thermoplastic polyimide resin preferably is about 200^°C to 300 °C .

<28> [Formula 2]

<30> In the above [Formula 2], m and n are real numbers that m+n=l, 0.3 ≤ m < l, 0 < n < 0.7.

<31> W included in the above [Formula 2], which is aromatic diamino compound selected below, may be used alone or by copolymerizing them.

<33> W₁ is selected from -(CH₂)-, -(CH₂)Ii-, -CH₂-C(CH₂J₂-CH₂-,

<34> W₂ is selected from -0-, -CO-, -S-, -SO₂-, -C(CHa)₂-, -CONH-, -C(CF₃V, -(CH₂)-,

<35> W₃ is selected from -0-, -CO-, -S-, -SO₂-, -C(CH₃V, -CONH-, -C(CFs)₂-, -(CH₂)-,

<36> W₄ is selected from -0-, -CO-,

<37> W₅ is selected from -Q-, -CO-, -S-, -SO₂-, -C(CH₃V, -CONH-, -C(CFs)₂-, -(CH₂)- ,

<38> W₆ is selected from -O- , -CO-, -S-, -SO₂-, -C(CHa)₂-, -CONH-, -C(CF₃V, -(CH₂)-.

<39> More preferably, W included in the above [Formula 2], which is aromatic diamino compound selected below, may be used alone or by copolymer izing them.

<41 > W₃, W₅, and W₆ are selected from -0-, -CO-, -S-, -SO₂-, -C(CHs)₂-, -CONH- , -C(CF₃)₂-, -(CH₂)-.

<42> Z included in the above [Formula 2], which is aromatic dianhydride selected below, may be used alone or by copolymer i zing them.

<43> <44> P included in the above [Formula 2], which is aromatic diamino compound selected below, may be used alone or by copolymerizing them.

<46> Pi is compound selected from -0-, -CONH-,

<47> P₂ is compound selected from -H, -CH₃, -CF₃, <48> Q included in the above [Formula 2], which is aromatic dianhydride selected below, may be used alone or by copolymerizing them.

<49>

<50> The polyimide resin described in the present invention includes all resins having an imide ring according to the following [Formula 3], but is not limited thereto. Examples of the polyimide resin may include polyimide, polyamideimide, polyesterimide, etc.

<5i> [Formula 3]

<53> In [Formula 3], Ar and Ar₂ are (C6-C20) aryl group, where n is a real number selected from 1 to 10,000,000.

<54> However, if the desired characteristics of the present invention may be achieved, the composition of the polyimide resin is specifically not limited and may be made of the polyimide resin alone, the derivatives thereof, or at least mixtures of the polyimid resin and derivatives thereof. In addition, imidization accelerator such as pyridine, quinolin, etc., adhesion promoter such as si lane coupling agent, titanate coupling agent, epoxy compound, etc., ant i foaming agent to facilitate an applying process, and other additives such as leveling agent, etc., may be used.

<55> The present invention provides a method of manufacturing a flexible metal-clad laminate including: (a) applying and drying polyamic acid solution that is positioned on one surface of a metal foil and has the glass transition temperature of 300 to 500 °C after imidization and then forming a first polyimide layer; (b) applying and drying polyamic acid solution that is positioned on one surface of the formed first polyimide layer and has a coefficient of linear thermal expansion of 1 to 20 ppm/K after imidization and then manufacturing a second polyimide layer! (c) applying and drying polyamic acid solution that is positioned on one surface of the formed second polyimide layer, has glass transition temperature of 200 ^°C ≤ Tg ≤ 300 ^°C after imidization, and has a coefficient of linear thermal expansion of 30 to 200 pρm/K, and then forming a thermoplastic polyimide layer; and (d) imidizing the manufactured laminate by performing heat treatment on the manufactured laminate at 0 to 500 ^°C .

<56> In the (a) to (c), the drying temperature after applying the polyamic acid solution, which is polyimide precursor resin, is not limited, but is preferably 80 to 220 °C . The polyamic acid, which is subjected to the (a) to (c), becomes a gel film in a solid state having self supportability coated on a copper foil. When the drying temperature of the polyamic acid is less than 80 ^°C , solvent volatile velocity is insignificant, such that it is difficult to substantially exhibit the drying effect. On the other hand, when the drying temperature of the polyamic acid is more than 220 ^°C , the coating layer is being excessively hardened, such that there is a risk that degrades physical properties later or does not exhibit stable physical properties.

<57> The present invention provides a flexible metal-clad laminate

<S8> Comprised of the first polyimide layer on a surface of the metal foil, the second polyimide layer, and the thermoplastic polyimide layer, wherein each of the layers is formed by appling and drying the polyimide precursor resin repeatedly and then converted into the polyimide resin by infrared heat treatment.

<59> The polyimide resin included in each layer may be directly applied on the metal foil in a fully imidized state or in a partially imidized state, but is generally converted into polyimide resin by applying the polyimide precursor solution and then performing the thermal or chemical conversion process thereon. As the heat treating method, any methods may be applied, but the heat treating method is generally performed by forming the gel film through the applying and drying of partially imidized polyimide resin or polyimide precursor resin and then fixing it within a drying furnace for a predetermined time or continuously moving it into the drying furnace for a predetermined time. The heat treatment temperature is generally 300 ^"C and more, more preferably, the high temperature treatment of 300 to 500 t is performed.

<60> One known heating manner satisfying the object of the present invention may be applied as the heat treatment manner.

<6i> The hot wind heating furnace is generally used under the atmosphere of nitrogen. In this case, however, the difference in the imidization history occurs in a thickness direction such that it is impossible to perform the uniform heat treatment and in the case of the thick film, there is a problem in that it is difficult to remove solvent existing inside the film to make worse the dimensional stability. Therefore, in order to perform the heat treatment on the laminate of the present invention, it is preferable to use the infrared heater that may perform the uniform heat treatment in the thickness direction of the film. Thereby, the flexible metal-clad laminate having excellent dimensional stability that the dimensional change after the etching is -0.1% to +0.1%, preferably -0.05% to +0.05% may be manufactured.

<62> As the applicable coating method when applying each layer of the present invention, a knife coating method, roll coating method, die coating method, a curtain coating method, etc., may be used. However, the method satisfying the objects of the present is not limited thereto.

<63> The double-sided metal-clad laminate described in the present invention may be manufactured by laminating additionally new metal foil on the thermoplastic polyimide layer. The laminating temperature is not specifically limited, but there is a need to heat at the glass transition temperature or more of the thermoplastic polyimide resin. When the heating temperature of the thermoplastic polyimide is not sufficient, the sufficient fluidity necessary for the compression with the metal foil may not be secured and therefore, it is impossible to secure the stable adhesive strength. Preferably, the heating temperature at the time of the compression is generally higher by 30 to 100 ^°C than the glass transition temperature (Tg) of the thermoplastic polyimide resin In addition, the laminating pressure is preferably 50 to 200 kgf/cm as a linear pressure. When the pressure is high, the laminating temperature may be lowered, such that the work is preferably performed at a pressure as high as possible.

<64> The present invention provides a flexible metal-clad laminate having peel strength of 1.0 to 3.00 kgf/cm at an interface of the first polyimide layer and the metal foil. In addition, the present invention provides a flexible metal-clad laminate having peel strength of 1.0 to 3.0 kgf/cm at an interface of the thermoplastic polyimide and the metal foil stacked by further performing the laminating, making it possible to stably maintain the adhesive strength.

[Advantageous Effects] <65> As described above, the flexible metal-clad laminate according to the present invention has an excellent exterior after the imidization, is not curled after and before the etching, and has the excellent adhesive strength with the metal foil . <66> In addition, the laminate manufactured according to the present invention may be manufactured into the double-sided metal-clad laminate through the laminating process.

[Description of Drawings! <67> The above and other objects, features and advantages of the present invention will become apparent from the following description of preferred embodiments given in conjunction with the accompanying drawings, in which: <68> FIG. 1 is an exterior photograph of a surface of a metal foil according to an example 1 of the present invention. <69> FIG. 2 is an exterior photograph of a metal foil according to comparative example 3.

[Best Mode] <70> Hereinafter, the present invention will be described in more detail with reference to the following Examples, but the scope of the present invention is not limited thereto.

<7i> The abbreviations used in the following Examples are as follows.

<72> -DMAc: N,N-dimethylacetamide

<73> -BPDA: 3,3' ,4,4'-biphenyltetracarboxylic acid di anhydride

<74> -PDA: p-phenylenedi amine

<75> -ODA: 4,4'-diaminodiphenylether

<76> -TPE-R: l,3-bis(4-aminophenoxy)benzene

<77> -BAPB: 4,4'-bis(4-aminophenoxy) bi phenyl.

<78> Physical properties disclosed in the present invention followed the next measuring methods. <79> 1. Measurement of coefficient of thermal linear expansion (CTE) and glass transition temperature (Tg). <80> The coefficient of linear thermal expansion was obtained by rising up to 400 ^°C at a speed of 5 °C per a minute and averaging a value between 100 °C and 250 ⁰C in the measured thermal expansion value by using a thermomechanical analyzer (TMA) In addition, a turning point of a thermal expansion curve measured through the above process was considered as the glass transition temperature (Tg).

<8i> 2. Curl after and before etching

<82> In order to measure the curl of a laminate after and before the etching, a sample was cut in a square that is 30 cm in width and length, respectively and was then averaged by measuring a height from the ground of each corner. When the average value does not exceed lcm, a flat laminate was considered.

<83> 3. Adhesive strength between polyimide resin and metal foil

<84> In order to measure the adhesive strength between the polyimide resin and the metal foil, the metal layer of the laminate was patterned in a width of lmm and then, the 180° peel strength was measured using a universal testing machine (UTM).

<85> 4. Exterior observation of polyimide resin

<86> By observing a shape of the surface after cutting the laminate in a square that is 30 cm in width and length, respectively, the exterior of the polyimide resin was determined to be good when there are no the blistering, the swelling, delamination between polyimid resin layers or between polyimide resin layer and the metal foil.

<87> 5. Dimensional change after etching

<88> It followed a method B of IPC-TM-650, 2.2.4. After holes for position recognition is drilled at four vertexes of a square sample of which MD and TD are 275 X 255 mm, respectively, and was stored in a thermohygrostat of 23 ^°C and 50% RH for 24 hours, a distance between the respective holes was repetitively measured three times and then averaged. Then, after the metal foil was etched and was stored in the thermohygrostat for 24 hours, the distance between holes was measured again. The change in the MD and TD direction of the values so measured was calculated.

<89> [Preparing Example 1] <90> PDA 12,312 g and ODA 2,533 g of diamine was agitated and completely dissolved in 211,378 g of DMAc solution and BPDA as dianhydride was added thereto several times so that a total amount of the BPDA reaches 38,000 g.

<91> Thereafter, the agitation was continuously performed for about 24 hours to prepare polyamic acid solution.

<92> The polyamic acid solution so prepared was cast to prepare a film and raised up to 350 ^°C for 60 minutes, and maintained for about 30 minutes. The thickness of the film reached to 20 μm after curing. The measured glass transition temperature and the coefficient of linear thermal expansion each was 12.0 ⁰C and 342 ppm/K.

<93> [Preparing Examples 2 to 8] <94> The polyamic acid solution was prepared using compositions and contents of [Table 1] in the same manner as Preparing Example 1.

<95> [Table 1]

<96>

<97> Example 1

<98> The polyamic acid solution prepared from the [Preparing Example2] was applied on an electro-deposited copper foil (surface roughness, Rz=2.0 μm) having a thickness of 12 μm and then dried at 130 °C so that the first polyimide precursor layer was formed.

<99> The polyamic acid solution prepared from the [Preparing Example 3] was applied on a surface of the first polyimide precursor layer and then dried at 150 ^°C so that the second polyimide precursor layer was formed.

<ioo> Thereafter, the polyamic acid solution prepared from the [Preparing Example 8] was applied on a surface of the second polyimide precursor layer and then dried at 150 °C so that the thermoplastic polyimide precursor layer was formed.

<ioι> Then, the laminate like above was subjected to the heat treatment for 9 minutes from 150 ^°C to 395 °C under the nitrogen atmosphere, such that it was completely imidized. Each thickness of the first polyimide layer, the second polyimide layer, and the thermoplastic polyimide layer reached to 5 μm, 13 μm and 3.5 μm respectively after curing. The results disclosed in [Table 2].

<iO2> Example 2

<i03> The polyamic acid solution prepared from the [Preparing Example2] was applied on an electro-deposited copper foil (surface roughness, Rz=2.0 μm) having a thickness of 12 μm and then dried at 160 ^°C so that the first polyimide precursor layer was formed.

<iO4> The polyamic acid solution prepared from the [Preparing Example 3] was applied on a surface of the first polyimide precursor layer and then dried at 150 ^°C so that the second polyimide precursor layer was formed.

<i05> Thereafter, the polyamic acid solution prepared from the [Preparing Example 7] was applied on a surface of the second polyimide precursor layer and then dried at 150°C so that the thermoplastic polyimide precursor layer was formed.

<i06> Then, the laminate like above was subjected to the heat treatment for 9 minutes from 150 ^°C to 395 °C under the nitrogen atmosphere, such that it was completely imidized. Each thickness of the first polyimide layer, the second polyimide layer, and the thermoplastic polyimide layer reached to 5 μm, 13 μm and 3 μm respectively after curing. The results disclosed in [Table 2].

<iO7> Example 3

<iϋ8> The polyamic acid solution prepared from the [Preparing Example2] was applied on an electro-deposited copper foiKsurface roughness, Rz=2.0 μm) having a thickness of 12 μm and then dried at 160 ⁰C so that the first polyimide precursor layer was formed.

<io9> The polyamic acid solution prepared from the [Preparing Example 3] was applied on a surface of the first polyimide precursor layer and then dried at 150 "C so that the second polyimide precursor layer was formed.

<πo> Thereafter, the polyamic acid solution prepared from the [Preparing Example 6] was applied on a surface of the second polyimide precursor layer and then dried at 160 ^°C so that the thermoplastic polyimide precursor layer was formed.

<iii> Then, the laminate like above was subjected to the heat treatment for 10 minutes from 150 °C to 395 °C under the nitrogen atmosphere, such that it was completely imidized. Each thickness of the first polyimide layer, the second polyimide layer, and the thermoplastic polyimide layer reached to 5 μm , 13 μm and 3 μm respectively after curing. The results disclosed in [Table 2].

<ii2> Example 4

<ii3> The polyamic acid solution prepared from the [Preparing Example2] was applied on an electro-deposited copper foiKsurface roughness, Rz=2.0 μm) having a thickness of 18 μm and then dried at 160 ^"C so that the first polyimide precursor layer was formed.

<ii4> The polyamic acid solution prepared from the [Preparing Example 1] was applied on a surface of the first polyimide precursor layer and then dried at 150 ^°C so that the second polyimide precursor layer was formed.

<ii5> Thereafter, the polyamic acid solution prepared from the [Preparing Example 5] was applied on a surface of the second polyimide precursor layer and then dried at 150 °C so that the thermoplastic polyimide precursor layer was formed.

<ii6> Then, the laminate like above was subjected to the heat treatment for 10 minutes from 150 °C to 395 ^°C under the nitrogen atmosphere, such that it was completely imidized. Each thickness of the first polyimide layer, the second polyimide layer, and the thermoplastic polyimide layer reached to 5 p , 18 μm and 3 μm respectively after curing. The results disclosed in [Table 2].

<ii7> Comparative Example 1

<ii8> The polyamic acid solution prepared from the [Preparing Example2] was applied on an electro-deposited copper foiKsurface roughness, Rz=2.0 μm) having a thickness of 12 μm and then dried at 130 ^°C so that the first polyimide precursor layer was formed.

<ii9> The polyamic acid solution prepared from the [Preparing Example 3] was applied on a surface of the first polyimide precursor layer and then dried at 150 ^°C so that the second polyimide precursor layer was formed.

<i20> Then, the laminate like above was subjected to the heat treatment for 9 minutes from 150 °C to 395 °C under the nitrogen atmosphere, such that it was completely imidized. Each thickness of the first polyimide layer and the second polyimide layer reached to 5 jam and 13 μm respectively after curing. The results disclosed in [Table 3].

<i2i> Comparative Example 2

<i22> The polyamic acid solution prepared from the [Preparing Example 4] was applied on an electro-deposited copper foiKsurface roughness, Rz=2.0 μm) having a thickness of 18/ΛΠ and then dried at 150 ^°C so that the first polyimide precursor layer was formed.

<i23> The polyamic acid solution prepared from the [Preparing Example 7] was applied on a surface of the first polyimide precursor layer and then dried at 150 ^°C so that the second polyimide precursor layer was formed.

<i24> Then, the laminate like above was subjected to the heat treatment for 7 minutes from 150 "C to 395 ^°C under the nitrogen atmosphere, such that it was completely imidized. Each thickness of the first polyimide layer and the second polyimide layer reached to 18 μm and 3 μm respectively after curing. The results disclosed in [Table 3].

<125> Comparative Example 3

<i26> The polyamic acid solution prepared from the [Preparing Example 7] was applied on an electro-deposited copper foiKsurface roughness, Rz=2.0 μm) having a thickness of 18 μm and then dried at 180 ^°C so that the first polyimide precursor layer was formed.

<i27> The polyamic acid solution prepared from the [Preparing Example 3] was applied on a surface of the first polyimide precursor layer and then dried at 150 ^°C so that the second polyimide precursor layer was formed.

<i28> Thereafter, the polyamic acid solution prepared from the [Preparing Example 7] was applied on a surface of the second polyimide precursor layer and then dried at 150 "C so that the thermoplastic polyimide precursor layer was formed.

<129> Then, the laminate like above was subjected to the heat treatment for 9 minutes from 150 °C to 395 "C under the nitrogen atmosphere, such that it was completely imidized. Each thickness of the first polyimide layer, the second polyimide layer, and the thermoplastic polyimide layer reached to 2 μm, 22 μm and 2 μm respectively after curing. The results disclosed in [Table 3].

<i30> Comparative Example 4

<i3i> The polyamic acid solution prepared from the [Preparing Example 8] was applied on an electro-deposited copper foiKsurface roughness, Rz=2.0 μm) having a thickness of 18μm and then dried at 130 ^°C so that the first polyimide precursor layer was formed.

<132> The polyamic acid solution prepared from the [Preparing Example 1] was applied on a surface of the first polyimide precursor layer and then dried at 150 ^°C so that the second polyimide precursor layer was formed.

<i33> Thereafter, the polyamic acid solution prepared from the [Preparing Example 8] was applied on a surface of the second polyimide precursor layer and then dried at 180 °C so that the thermoplastic polyimide precursor layer was formed.

<134> Then, the laminate like above was subjected to the heat treatment for 24 minutes from 230 ^°C to 385 ^°C under the nitrogen atmosphere, such that it was completely imidized. Each thickness of the first polyimide layer, the second polyimide layer, and the thermoplastic polyimide layer reached to 2.5 μm, 20 μm and 3 μm respectively after curing. The results disclosed in [Table 3].

<135> [Table 2]

<I36>

<137> [Table 3]

<138>

<139> FIG. 1 is an exterior photograph of a surface of a metal foil according to a [Example 1] of the present invention. Referring to FIG. 1, the exterior of the metal foil according to the present invention is good since there are no the foaming generation, the swelling, the delamination between the metal foil and the polyimide layer or the polyimide layers. On the other hand, FIG. 2 is an exterior photograph of a metal foil according to a [comparative example 3]. Referring to FIG. 2, resin having the glass transition temperature of 232 °C lower than 300 °C is used for the first polyimide layer to generate the foaming on the surface of the metal foil, such that it may be confirmed that the exterior is poor.

<140> While the present invention has been described with respect to the specific embodiments, it will be apparent to those skilled in the art that various changes and modifications may be made without departing from the spirit and scope of the invention as defined in the following claims.

Claims

[CLAIMS] ΪClaim 1]

<I42> A flexible metal clad laminate, comprising: <i43> a first polyimide layer that is positioned on one surface of a metal foil and has glass transition temperature of 300 to 500 ^°C ;

<i44> a second polyimide layer that is positioned on one surface of the first polyimide layer and has a linear thermal expansion coefficient of 1 to 20 ppm/K; and

<145> a thermoplastic polyimide layer that is positioned on one surface of the second polyimide layer.

[Claim 2]

<i46> The flexible metal clad laminate of claim 1, wherein the metal foil is further laminated on one surface of the thermoplastic polyimide layer.

[Claim 3]

<i47> The flexible metal clad laminate of claim 2, wherein the peel strength at an interface of the thermoplastic polyimide and the metal foil is 1.0 ^~ 3.0 kgf/cm. [Claim 4]

<i48> The flexible metal clad laminate of claim 1,

<i49> each of the layers is formed by appling and drying the polyimide precursor resin repeatedly and then converted into the polyimide resin by infrared heat treatment. [Claim 5]

<i5o> The flexible metal clad laminate of claim 1, wherein the coefficient of linear thermal expansion of the first polyimide layer is 5 ~ 40 ppm/K. [Claim 6]

<i5i> The flexible metal clad laminate of claim 1, wherein the glass transition temperature of the thermoplastic polyimide layer is 200 ^°C ≤ Tg ≤ 300 ^°C and the coefficient of linear thermal coefficient thereof is 30 ^~ 200 ppm/K. [Claim 7] <152> The flexible metal clad laminate of claim 1, wherein the peel strength at an interface of the first polyimde layer and the metal foil is 1.0 ~ 3.0 kgf/cm. [Claim 81

<153> The flexible metal clad laminate of claim 1, wherein the dimensional change after etching of the flexible metal clad laminate is -0.05% ~ +0.05%. [Claim 9]

<154> The flexible metal clad laminate of claim 5, wherein the resin forming the first polyimide layer or the scond polyimide layer follows the following [Formula 1] .

<155> [Formula 1]

<157> where 0.5 < m < 1.0 and 0 < n < 0.5, m+n=l; and

<158> X and Y included in [Formula 1] each, which is aromatic dianhydride compound independently selected from the following structure, is equal to or different from each other.

<159>

[Claim 10]

<160> The flexible metal clad laminate of claim 6, wherein the thermoplastic polyimide layer is resin represented by the following [Formula 2]. <161> [Formula 2]

<163> in the above [Formula 2], m and n are real numbers that m+n=l, 0.3 ≤ m < 1, 0 < n < 0.7.

<164> W included in the above [Formula 2], which is aromatic diamino compound selected below, is used alone or by copolymerizing them.

<166> W₁ is selected from -(CH₂)-, -(CH₂)n-, -CH₂-C(CH₂)₂-CH₂-,

<167> W₂ is selected from -0-, -CO-, -S-, -SO₂-, -C(CHs)₂-, -CONH-, -C(CF₃)₂-, -(CH₂)-,

<168> W₃ is selected from -O- , -CO-, -S-, -SO₂-, -C(CHs)₂-, -CONH-, -C(CF₃)₂-, -(CH₂)-,

<169> W₄ is selected from -0-, -CO-, <170> W₅ is selected from -0-, -CO-, -S-, -SO₂-, -C(CHs)₂-, -CONH-, -C(CF₃)₂-, -(CH₂)-,

<171 > W₆ is selected from -0-, -CO-, -S-, -SO₂-, -C(CHa)₂-, -CONH-, -C(CF₃)₂-, -(CH₂)-. <172> Z included in the above [Formula 2], which is aromatic dianhydride compound selected below, is used alone or by copolymerizing them.

<173>

<174> where P included in the above [Formula 2], which is aromatic diamino compound selected below, is used alone or by copolymeri zing them.

<176> where Pi is compound selected from -0-, -CONH-,

<177> P2 is compound selected from -H, -CH3, -CF3, <178> Q included in the above [Formula 2], which is aromatic dianhydride selected below, is used alone or by copolymerizing them.

<179>

[Claim 11]

<180> The flexible metal clad laminate of claim 10, wherein W included in the above [Formula 2], which is aromatic diamino compound selected below, is used alone or by copolymerizing them.

<182> where W₃, W₅, and W₆ each is selected from -Q-, -CO-, -S-, -SO2-, -C(CHa)₂-, -CONH-, -C(CFs)₂-, -(CH₂)-.

[Claim 12]

<183> A method of manufacturing a flexible metal-clad laminate, comprising:

<i84> (a) applying and drying polyamic acid solution that is positioned on one surface of a metal foil and has the glass transition temperature of 300 to 500 "C after imidization and then forming a first polyimide layer;

<i85> (b) applying and drying polyamic acid solution that is positioned on one surface of the formed first polyimide layer and has a coefficient of linear thermal expansion of 1 to 20 ppm/K after imidization and then manufacturing a second polyimide layer;

<186> (c) applying and drying polyamic acid solution that is positioned on one surface of the formed second polyimide layer, has glass transition temperature of 200 ⁰C ≤ Tg ≤ 300 °C after imidization, and has a coefficient of linear thermal expansion of 30 to 200 ppm/K, and then forming a thermoplastic polyimide layer; and

<i87> (d) imidizing the manufactured laminate by performing heat treatment at 0 to 500 ⁰C. [Claim 13]

<i88> The method of manufacturing a flexible metal-clad laminate of claim 12, wherein the drying temperature at (a) the applying and drying of polyamic acid solution is 80 to 220 °C . [Claim 14]

<i89> The method of manufacturing a flexible metal-clad laminate of claim 12, wherein the coating method of each layer uses methods selected from a group consisting of a knife coating method, roll coating method, die coating method, a curtain coating method, and a combined method thereof. [Claim 15]

<i90> The method of manufacturing a flexible metal-clad laminate of claim 12, wherein the heat treatment at the imidizing of the manufactured laminate is performed using an infrared heater under the nitrogen atmosphere.