KR20120112216A - Metal-clad laminate - Google Patents

Abstract

PURPOSE: A metal-clad laminated plate is provided to suppress micro-voids from being generated between metal foils and a polyimide layer by using metal foils with the intrinsic roughened sides. CONSTITUTION: Metal foils are arranged on one side or both sides of a polyimide layer in a metal-clad laminated plate. The glass transition temperature of the polyimide layer is more than or equal to 300 deg C. The roughened sides of the metal foils in contact with the polyimide layer satisfy the following conditions: the surface roughness of the roughened sides is in a range between 0.5 and 4um; the surface parts of the roughened sides are made of micro-protrusions(p, q) by a plurality of rough particles; and the aspect ratio of the micro-protrusions is in a range between 1.5 and 5.

Description

{METAL-CLAD LAMINATE}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a metal laminated board preferably used for a flexible circuit board, and more particularly to a flexible metal laminated board having flexibility in which an insulating layer is made of a polyimide resin.

2. Description of the Related Art In recent years, as electronic devices such as cellular phones, digital cameras, digital video, PDAs, car navigation systems, hard disks, and other various types of electronic devices have become more sophisticated, smaller, and lighter, An example in which a flexible printed substrate having a high thickness and easy to be used is employed is increasing. In addition, with respect to the flexible printed circuit boards used in these devices, which are becoming more sophisticated, demands for miniaturization of high density, multilayer structure, miniaturization, and high internal resistance are further increased.

In order to cope with such a demand, a polyimide resin layer is directly applied on a conductor and a plurality of polyimide resin layers having different thermal expansion coefficients are formed in a multilayered structure, whereby dimensional stability, adhesive force, and planarity after etching Discloses a method of providing a flexible printed circuit board having excellent reliability.

In the copper clad laminate having no adhesive layer used in such a flexible printed board, for example, in order to increase the adhesive force with the resin layer, such as Patent Document 2, Patent Document 3, Patent Document 4, etc., have.

However, recently, in order to cope with an increase in the solder bonding temperature due to the lead-freeization, since the polyimide resin layer in contact with the copper foil has a high internal resistance as in Patent Document 5, micro voids are formed between the copper foil and the polyimide layer There is a problem that the adhesion reliability is lowered because wiring peeling occurs due to penetration of pickling solution at the time of circuit processing. To solve this problem, there is a method of controlling the plating layer on the copper foil-roughened surface by suppressing the height of roughening treatment as in Patent Document 6. However, there is a concern that the initial peel strength is lowered by this method, and the problem remains.

Patent Document 1: Japanese Patent Publication No. 6-93537

Patent Document 2: JP-A-2-292894

Patent Document 3: JP-A-6-169168

Patent Document 4: JP-A-8-335775

Patent Document 5: WO 2002/085616

Patent Document 6: WO 2010/010892

The present invention has been made in view of the above problems, and it is an object of the present invention to provide a polyimide layer which is in contact with a roughened metal foil, which has high heat resistance but suppresses microvoids generated between the metal foil and the polyimide layer and improves adhesion reliability between the metal layer and the polyimide layer, And suppressing circuit peeling due to penetration of the metal-clad laminate.

The inventors of the present invention have conducted extensive studies in order to solve the above problems. As a result, the inventors of the present invention have found that the above problems can be solved by using a peculiar blend of metal foil surfaces and applying a resin having a specific characteristic to the polyimide resin in contact with the metal foil Thus, the present invention has been completed.

That is, the present invention provides a metal-clad laminate having a metal foil on one side or both sides of a polyimide layer, wherein the polyimide layer (i) in contact with the metal foil has a glass transition temperature of 300 ° C or higher and is in contact with the polyimide layer Wherein the roughened surface satisfies the requirements of (a) to (c) below.

(a) The surface roughness (Rz) of the roughened surface is in the range of 0.5 to 4 μm

(b) the surface layer portion of the roughened surface is in the form of a fine protrusion formed by a plurality of roughening particles, and the height of the protrusion height H with respect to the width L of the root portion of the first protrusion (H / L) represented by the ratio is in the range of 1.5 to 5, and the proportion of the projection shape having the projection height in the range of 1 to 3 占 퐉 is 50% or less with respect to the total number of projection shapes

(c) the existence ratio of the gap between the adjacent projections having a depth of 0.5 μm or more and a distance between adjacent projections in the range of 0.001 to 1 μm is 50% or less of the total projected shape number

(Effects of the Invention)

The metal-clad laminate according to the present invention is a laminate in which the polyimide constituting the insulating layer has high heat resistance and exhibits excellent dimensional stability and can suppress generation of micro voids between the metal foil and the polyimide layer in contact with the metal foil, It is excellent in chemical resistance such as in circuit processing, so that it can be used on a circuit board requiring high-precision processing, and its usefulness is very high.

Fig. 1 is a schematic view for explaining a harmonic shape in a copper foil cross section of a copper foil. Fig.
Fig. 2 is a copper foil cross-sectional photograph of the copper foil used in Example 1. Fig.
3 is a copper foil cross-sectional photograph of the copper foil used in Comparative Example 2. Fig.

Hereinafter, the present invention will be described in detail.

The metal-clad laminate of the present invention has a metal foil on one side or both sides of the polyimide layer. The polyimide layer may be a single layer or a plurality of layers if the glass transition temperature of the polyimide layer in contact with the metal foil is 300 캜 or more. Preferably, the polyimide layer is a polyimide layer different from the polyimide layer (i) having a glass transition temperature of 300 캜 or higher , And the other polyimide layer is composed of a polyimide resin layer (ii) having a glass transition temperature of 50 캜 or more higher than the glass transition temperature of the polyimide layer (i). The metal foil is not particularly limited as long as it exhibits a later surface roughened shape, but a copper foil or an alloy copper foil is preferable.

When a copper foil or an alloy copper foil is used as the metal foil, the thickness is preferably in the range of 5 mu m to 50 mu m, and more preferably in the range of 9 mu m to 30 mu m considering the applicability to the flexible wiring board.

The roughened surface to be in contact with the polyimide layer of the metal foil used in the present invention needs to satisfy the following requirements (a) to (c).

(a) The surface roughness Rz of the roughened surface is in the range of 0.5 to 4 μm

(b) the surface layer portion of the roughened surface is in the form of a fine protrusion formed by a plurality of roughening particles, and the height of the protrusion height H with respect to the width L of the root portion of the first protrusion (H / L) represented by the ratio is in the range of 1.5 to 5, and the proportion of the projection shape having the projection height in the range of 1 to 3 占 퐉 is 50% or less with respect to the total number of projection shapes

(c) the existence ratio of the gap between the adjacent projections having a depth of 0.5 μm or more and a distance between adjacent projections in the range of 0.001 to 1 μm is 50% or less of the total projected shape number

First, the surface roughness Rz of the roughened surface must be in the range of 0.5 to 4 占 퐉. If the value of Rz is not satisfied and the adhesive force between the metal foil and the polyimide layer is lowered to exceed 4 mu m, etching residues increase when the circuit is processed into a fine pattern, resulting in deterioration of electrical reliability. Here, the surface roughness Rz of the roughened surface refers to Rz defined in the definition of " 5.1 Roughness Average Roughness " of JISB 0601-1994 " Definition and Display of Surface Roughness ".

Next, the surface layer portion of the roughened surface is in the form of a fine projection formed by a plurality of roughened particles, and the ratio of the projection height H to the width L of the basic portion of the first projection in the fine projection- It is necessary that the ratio of the projections having the aspect ratio (H / L) shown in the range of 1.5 to 5 and the height of the projections in the range of 1 to 3 占 퐉 is 50% or less with respect to the total number of projections. When the aspect ratio and the height of the projection are more than 50%, the surface roughened shape is roughened, and when the polyimide layer having a high heat resistance (glass transition temperature) is heat-pressed, the flow property is insufficient and micro voids are likely to occur Loses.

Further, in the roughened surface of the metal foil surface, the existence ratio of gaps having a depth of 0.5 占 퐉 or more and a distance between adjacent projections in the range of 0.001 to 1 占 퐉 is 50% or less of the total number of projections It is necessary. If the ratio exceeds 50%, resin filling into the gap is not sufficiently performed, and micro voids are likely to occur.

Here, the roughened surface of the metal foil used in the present invention will be described with reference to Fig. Fig. 1 schematically shows an enlarged surface portion of a cross section of a metal foil. In the present invention, the aspect ratio of the microprojection shape of the roughened surface can be determined, for example, by dividing the height (H) of the first projections having the microprojection shape by the width L of the root portion of the projection Value. The height of the protrusion refers to a value indicating the longest length from the center connecting the bottom of adjacent valleys.

(C) of the present invention, there is a gap of 0.5 mu m or more in depth between adjacent protrusions, and a clearance having a distance between adjacent protrusions in the gap of 0.0001 to 1 mu m is present However, it is judged as existence ratio. In Fig. 1, the protrusions p and q are adjacent protrusions, and the protrusions p and q have a gap of 0.5 mu m or more in depth. The adjacent distance is in the range of 0.001 to 1 mu m. In the present invention, the smaller the gap is, the smaller the gap is, in other words, the requirement of (c), the gap between the protrusions is 0.5 mu m or more in depth, and the distance between adjacent ones to the depth is in the range of 0.001 to 1 mu m Is 50% or less of the total number of projection shapes.

The roughened shape formed on the surface of the metal foil used in the present invention preferably has a ratio of the projections having a width larger than the width L of the root portion toward the vertex direction by 20% And more preferably 10% or less. If this ratio exceeds 20%, microvoids tend to occur in the base portion of the projection shape.

In the roughened surface of the metal foil of the present invention, since the microprojection tends to be generated if the shape of the projections by the roughening treatment is long and thin, the average width of the projections having a height of 1 mu m or more in total projections is 1 mu m or more The ratio is preferably 10% or more, more preferably 30% or more. Here, the average width of the projection shapes may be regarded as the average width, which is the width at 1/2 height of the projection shape. The copper foil thus roughened is commercially available, and those satisfying the requirements of the roughened surface in the present invention are available from commercial products.

It is preferable that the roughened surface of the metal foil is plated with Ni, Zn and Cr on the roughened surface, has a Ni content of 0.1 mg / dm ² or more, and has a Y value (brightness) . This lightness is an index indicating the illuminance of the surface by irradiating the sample surface with light and letting the light reflectance be lightness. The low brightness means that the reflectance is low, that is, there are many narrow and deep gaps between adjacent protrusions, and micro voids are likely to occur at the time of thermocompression bonding. When the Ni content is less than 0.1 mg / dm < ^{2 &} gt ;, the corrosion resistance is insufficient, so that it is corroded by the acid regardless of the filling property of the polyimide.

Next, the polyimide layer to be an insulating layer with the metal-clad laminate of the present invention will be described.

As described above, in the present invention, the polyimide layer is indispensable as a layer in contact with the metal foil (i), and is preferably composed of a plurality of polyimides. Preferable examples of the constitution of the polyimide layer include the following constitutional examples. The PI layer (i) is a polyimide layer having a glass transition temperature of 300 ° C or higher, and the PI layer (ii) is a polyimide layer having a glass transition temperature of 300 ° C or higher. In the following constitutional example, M is abbreviation of metal foil, PI is abbreviation of polyimide, (i) is a polyimide layer having a glass transition temperature higher by 50 占 폚 or more.

1) M / PI layer (i) / PI layer (ii) / PI layer (i)

2) M / PI layer (i) / PI layer (ii) / PI layer (i) / M

3) M / Pl layer (ii) / PI layer (i) / M

The polyimide constituting the polyimide layer is generally represented by the following formula (1), and can be prepared by a known method in which the diamine component and the acid dianhydride component are substantially equimolarly used and polymerized in an organic polar solvent.

Wherein Ar ₁ is a tetravalent organic group having at least one aromatic ring, Ar ₂ is a divalent organic group having at least one aromatic ring, and n represents a repeating number. That is, Ar ₁ is a residue of an acid dianhydride, and Ar ₂ is a residue of a diamine.

Examples of the solvent to be used for the polymerization of polyimide include dimethylacetamide, n-methylpyrrolidinone, 2-butanone, diglyme, xylene, etc. These solvents may be used alone or in combination have. The resin viscosity of the polyamic acid (polyimide precursor) obtained by polymerization is preferably in the range of 500 cps to 35000 cps.

The diamine component and the acid dianhydride component used as a raw material are appropriately selected from the respective raw material components exemplified below in consideration of various properties required for the polyimide layer (i) and the polyimide layer (ii) constituting the insulating layer Is selected.

As the acid dianhydride, for example, an aromatic tetracarboxylic acid dianhydride represented by O (CO) ₂ -Ar ₁ - (CO) ₂ O is preferable, and an aromatic acid anhydride residue represented by the following formula (2) Ar ₁ is given as an example.

As the diamine, for example, an aromatic diamine represented by H ₂ N-Ar ₂ -NH ₂ is preferable, and an aromatic diamine in which an aromatic diamine residue represented by the following formula (3) is given as Ar ₂ is exemplified.

The polyimide layer (i) in the present invention is a polyimide layer having a glass transition temperature of 300 DEG C or more and in contact with the metal foil. The polyimide layer (i) is required to exhibit thermoplasticity when hot-pressed with a metal foil from the viewpoint of adhesion with the metal foil. However, when the glass transition temperature is lowered, the polyimide layer (i) From such a viewpoint, the preferable glass transition temperature of the polyimide layer (i) is preferably less than 350 占 폚.

The acid dianhydride component constituting the polyimide layer (i) includes those exemplified in the above formula (2), but it is preferable to use pyromellitic dianhydride (PMDA) as an essential component and particularly preferably 80 mol % Or more. Examples of the diamine component constituting the polyimide layer (i) include those exemplified in the above-mentioned formula (3). Particularly, 2,2-bis [4- (4-aminophenoxy) phenyl] propane (BAPP) And it is particularly preferable to use it as a main component in an amount of 80 mol% or more. Here, the other acid dianhydrides and diamine components may be used in combination of two or more.

The polyimide layer (ii) in the present invention is a polyimide layer having a glass transition temperature higher than that of the polyimide layer (i) by 50 占 폚 or more. The polyimide layer (ii) is preferably directly in contact with the metal foil and integrated with the metal foil through the polyimide layer (i) in view of adhesion with the metal foil.

The acid dianhydride component constituting the polyimide layer (ii) includes pyromellitic dianhydride (PMDA), 3,3 ', 4,4'-biphenyltetracarboxylic dianhydride (BPDA), 3,3' , 4,4'-benzophenone tetracarboxylic dianhydride (BTDA), 3,3 ', 4,4'-diphenylsulfone tetracarboxylic dianhydride (DSDA) and 4,4'-oxydiphthalic dianhydride And water (ODPA) are preferably used, and they may be used singly or in combination of two or more.

The diamine component constituting the polyimide layer (ii) includes diaminodiphenyl ether (DAPE), 2'-methoxy-4,4'-diaminobenzanilide (MABA), 2,2'- , 4'-diaminobiphenyl (m-TB), paraphenylenediamine (P-PDA), 1,3-bis (4-aminophenoxy) benzene (TPE- (APP), 1,4-bis (4-aminophenoxy) benzene (TPE-Q), and 2,2-bis [4- (4-aminophenoxy) phenyl] Are exemplified as preferable ones, and these may be used alone or in combination of two or more.

The thickness of the polyimide layer in the present invention is preferably in the range of 8 to 40 mu m, more preferably in the range of 9 to 30 mu m. The polyimide layer (i) is useful for maintaining adhesiveness with the metal layer and for maintaining balance by controlling the coefficient of linear expansion of the entire insulating layer. The thickness of the polyimide layer (i) is preferably in the range of 1 to 3 mu m. The polyimide layer (i) may be provided on one side or both sides of the polyimide layer (ii).

As described above, in the present invention, the insulating layer is composed of a single layer or a plurality of polyimide layers, but in the present invention, the coefficient of linear expansion (CTE) in the entire insulating layer (entire polyimide layer) is preferably 10 10 ^-6 ? ^-6 [1 / K]. When the polyimide layer has a plurality of layers, the coefficient of linear expansion (CTE) of the polyimide layer (ii) is preferably 30 x 10 ^-6 [1 / K] or less, more preferably 1 x 10 ^{-6 to} 20 x 10 ^-6 [1 / K] is particularly preferable. In this case, the polyimide layer (i) is preferably in the range of 20 × 10 ^{-6 to} 60 × 10 ^-6 [1 / K], more preferably in the range of 30 × 10 ^{-6 to} 50 × 10 ^-6 [1 / K] Is particularly preferable.

Hereinafter, the method for producing the metal-clad laminate according to the present invention will be described with reference to the [M / PI layer (i) / PI layer (ii) / PI layer (i) / M] do. In the following examples, M is a copper foil.

In this example, first, a polyamic acid solution, which is a precursor of polyimide, is applied directly to the surface of the roughened copper foil to form the polyimide layer (i), and the solvent contained in the resin solution is sprayed Remove.

Then, a polyamic acid solution which is a precursor of polyimide is applied directly to the polyimide layer (ii), and the solvent contained in the resin solution is removed at a temperature of 150 DEG C or lower.

Further, a polyamic acid solution which is a precursor of polyimide is applied directly to the polyimide layer (i), and the solvent contained in the resin solution is removed at a temperature of 150 ° C or lower. In this manner, after forming a plurality of layers of polyimide precursor layers on the copper foil by removing the solvent to some extent, heat treatment is performed at a temperature of 100-450 DEG C, preferably 300-450 DEG C for 5-40 minutes , And removal of the solvent and imidization are further performed.

In this state, a single-sided copper-clad laminate composed of three layers of polyimide layers is formed on the copper foil. The copper foil roughed on the polyimide layer (i) side of the single-sided copper clad laminate is heat-pressed. The hot pressing is heat-pressed at a temperature slightly higher than the glass transition temperature of the polyimide layer (i), and in the present invention, the generation of micro voids can be suppressed by using the copper foil of the specific roughened surface. In this embodiment, the copper foil roughened on both sides of the polyimide layer is applied, but in the present invention, the copper foil specified above may be applied only to the copper foil on one side, preferably on the heat-mounting side.

As described above, in the present invention, even when a polyimide layer having a high glass transition temperature is used as a layer in contact with a metal foil which requires heat resistance, the use of a roughened copper foil having a specific surface property can improve the dimensional stability, It is possible to suppress the occurrence of micro voids while maintaining various characteristics of the laminated sheet.

(Example)

Hereinafter, the present invention will be described in more detail based on examples. In the following examples, unless otherwise noted, various evaluations are as follows.

[Measurement of glass transition temperature]

The base copper foil was etched to obtain a polyimide film in a state of SII NanoTechnology Inc. Using a dynamic viscoelasticity measuring device (RSA-Ⅲ), the peak temperature of tan δ measured at 1.0 Hz in tensile mode was taken as the glass transition temperature.

[Evaluation of Harmonized Surface]

The shape of the roughened surface was evaluated by FE-SEM (manufactured by Hitachi High-Technologies Corporation, model S-4700), and the width of the copper foil was measured using a cross-section polisher (SM-09010 manufactured by JEOL Ltd.) The shape of the harmonic portion within the range of 占 퐉 was evaluated.

In addition, the amount of Ni in the roughened surface was measured by ICP-AES (manufactured by PerkinElmer Co., Ltd., 0ptima 4300) by using only the surface in contact with polyimide to 1N-nitric acid. The brightness (Y) is measured by Suga Test Instruments Co., Ltd. And measured using SM-4 manufactured by Mitsubishi Electric Corporation.

[Measurement of acid resistance]

The acid resistance of the flexible one-side copper-clad laminate was evaluated by circuit processing with a line width of 1 mm, immersing the copper-clad laminate in an aqueous solution of hydrochloric acid of 18 wt% at 50 DEG C for 60 minutes and then measuring the circuit end from the insulating layer (polyimide layer) , The discoloration width due to penetration of hydrochloric acid was measured. Here, it can be evaluated that the hydrochloric acid penetration width is 200 mu m or less.

[Measurement of adhesive strength (peel strength)] [

The adhesive force between the copper foil and the polyimide resin layer was obtained by forming an insulating layer made of polyimide resin on the copper foil and then performing circuit processing with a line width of 1 mm in the flexible one-side copper-clad laminate. The initial peel strength was measured by peeling the copper foil in the direction of 180 占 using a tensile tester (Stroog-M1) of the fabricator. The peel strength after the acid resistance was measured, and the peel strength after the acid resistance / the initial peel strength x 100 was regarded as the retention ratio.

Synthesis Example 1

N, N-dimethylacetamide was added to a reaction vessel equipped with a thermocouple and a stirrer and capable of nitrogen introduction at the same time. To this reaction vessel, 2,2-bis [4- (4-aminophenoxy) phenyl] propane (BAPP) was dissolved in a vessel while stirring. Then, pyromellitic dianhydride (PMDA) was added so that the total amount of the monomer added was 12 wt%. Thereafter, stirring was continued for 3 hours to obtain a resin solution b of a polyamic acid. The solution viscosity of the resin solution b of polyamic acid was 3,000 cps. The polyimide obtained from the polyamic acid exhibited a coefficient of linear expansion exceeding 30 x 10 < ^-6 > (1 / K) and had a glass transition temperature of 315 deg.

Synthesis Example 2

N, N-dimethylacetamide was added to a reaction vessel equipped with a thermocouple and a stirrer and capable of nitrogen introduction at the same time. In this reaction vessel, 2,2'-dimethyl-4,4'-diaminobiphenyl (m-TB) was dissolved in a vessel while stirring. Then, 3,3 ', 4,4'-biphenyltetracarboxylic dianhydride (BPD) and pyromellitic dianhydride (PMDA) were added. The amount of the monomer added was 15 wt%, and the molar ratio of each acid anhydride (BPDA: PMDA) was 20:80. Thereafter, stirring was continued for 3 hours to obtain a resin solution a of polyamic acid. The solution viscosity of the resin solution a of polyamic acid was 20,000 cps. The polyimide obtained from the polyamic acid exhibited a low coefficient of linear expansion of 20 x 10 < ^-6 > (1 / K) or less and had non-thermoplastic properties.

Example 1

As the copper foil, an electrolytic copper foil having a roughened surface shown in Table 1 was prepared by silane coupling treatment with a silane coupling agent having an amino group as a surface treatment layer. This copper foil was 12 mu m thick and the surface roughness (Rz) was 1.2 mu m. On this copper foil, a resin solution b of polyamic acid prepared in Synthesis Example 2, a resin solution a of polyamic acid prepared in Synthesis Example 1, and a resin solution b of polyamic acid prepared in Synthesis Example 2 were sequentially coated on the copper foil, At 300 DEG C or higher for about 10 minutes to obtain a flexible surface-anchor laminate having a thickness of 25 mu m as the polyimide layer. The polyimide layer has a layer of 21 mu m obtained from the resin solution a of polyamic acid and a layer of 2 mu m each obtained from the resin solution b of polyamic acid on both sides thereof.

The same copper foil as above was heated and pressed on the polyimide layer surface of the thus obtained flexible surface-copper-clad laminate by passing between the metal rolls under heat and pressure. The evaluation of the peel strength and acid resistance was carried out on the side of the heat-pressed side of the flexible double-side copper-clad laminate. As a result, the initial adhesive force of 1 mm peel between the copper foil and the polyimide layer was 1.95 kN / m. Further, the penetration width of this circuit by the acid resistance test was 69 탆, and the peel strength retention was 89%. The results are shown in Table 2.

Examples 2 and 3, Comparative Examples 1 and 2

The electrolytic copper foil shown in Table 1 having different surface metal amounts was used in the same manner as in Example 1 to evaluate the fill strength, hydrochloric acid permeability, and fill retention. The results are shown in Table 2.

Although not shown in Table 1, the roughened surfaces of all the copper foils used in Examples and Comparative Examples were plated with Ni, Zr and Cr.

In Table 1,

(b) The number of high aspect ratio non-number / total number of projections indicates the ratio of the number of the projections having the aspect ratio (H / L) in the range of 1.5 to 5 and the height of the projections in the range of 1 to 3 μm ,

(c) The number of narrow-gage / total number of projections between projections shall be the number of gaps having a depth of at least 0.5 μm between adjoining projections and a distance between adjacent projections in the range of 0.001 to 1 μm Ratio.

(D) The number of bulged protrusions / total protrusions is a ratio of the number of protrusions having a width larger than the source width L to the total number of protrusions measured.

(E) The projection average width is 1 占 퐉 or more / total projection number is a ratio of the number of projections having an average width of 1 占 퐉 or more to the total number of projections measured.

A photograph of the copper foil section used in Example 1 is shown in Fig. 2, and a photograph of the copper foil section used in Comparative Example 2 is shown in Fig. Here, the copper foil used in Examples 2 and 3 was similar to that of Fig. 2 although the Rz was different, but the surface of the copper foil used in Comparative Example 1 was similar to that of Fig. 3 although the Rz was different.

In the copper clad laminate obtained in Examples 1, 2 and 3, discoloration of the circuit end after hydrochloric acid treatment was 200 m or less and the peel strength retention was 70% or more. On the other hand, in Comparative Examples 1 and 2, discoloration due to peeling of the circuit was confirmed on the entire circuit end portion, and the peel strength retention ratio was less than 70%.

As described above, the flexible copper clad laminate obtained from the present invention was confirmed to be a highly reliable material because permeation after hydrochloric acid treatment was suppressed and circuit peeling did not occur.

L: width of the base portion of the fine projection shape H: height of the fine projection shape
p: one protrusion adjacent to q: one protrusion adjacent to p:

Claims (6)

A metal-clad laminate having a metal foil on one side or both sides of a polyimide layer, comprising:
Characterized in that the glass transition temperature of the polyimide layer (i) in contact with the metal foil is 300 DEG C or more and the surface to be roughened in contact with the polyimide layer of the metal foil satisfies the following requirements (a) to (c) Long laminated sheet.
(a) The surface roughness (Rz) of the roughened surface is in the range of 0.5 to 4 μm.
(b) the surface layer portion of the roughened surface is in the form of a fine protrusion formed by a plurality of roughening particles, and the height of the protrusion height H with respect to the width L of the root portion of the first protrusion (H / L) represented by the ratio is in the range of 1.5? 5, and the ratio of the projection shape having a height of 1? 3 占 퐉 is 50% or less with respect to the number of all projection shapes.
(c) The existence ratio of gaps having a depth of 0.5 μm or more between adjoining protrusions and a distance between adjacent protrusions in the range of 0.001 to 1 μm is 50% or less of the total protrusion number. The method according to claim 1,
Wherein the ratio of the projection shape having the width larger than the width L of the root portion toward the vertex direction is 20% or less with respect to the number of all the projection shapes in the projecting shape specified in (b) Laminates. 3. The method according to claim 1 or 2,
Wherein the ratio of the average width of protrusions having a height of 1 占 퐉 or more, which occupies 1 占 퐉 or more, in the entire protruding shape is 10% or more. 4. The method according to any one of claims 1 to 3,
Wherein the roughened surface is plated with Ni, Zn and Cr, the Ni content is 0.1 mg / dm ² or more, and the Y value (brightness) measured by an optical system is 25 or more. 5. The method according to any one of claims 1 to 4,
Wherein the polyimide layer is composed of a plurality of layers and the glass transition temperature of the polyimide layer (ii) not in contact with the metal foil is at least 50 캜 higher than the glass transition temperature of the polyimide layer (i) Laminates. 6. The method according to any one of claims 1 to 5,
Wherein the initial adhesion of the polyimide resin layer and the metal foil at a width of 1 mm is 1.0 kN / m or more, and the peel strength retention after immersion in hydrochloric acid is 80% or more.

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