KR20110018809A - Metal-coated polyimide film and process for producing the same - Google Patents

Abstract

PURPOSE: A metal-coating polyimide film, which has dimensional stability, and a manufacturing method of the same are provided to reduce the number of pin-holes of the metal - coating polyimide film. CONSTITUTION: A base metal layer is formed on the surface of a polyimide film by using a reel-to-reel method. The base metal layer is composed of a nickel-chrome alloy layer and a copper layer. A copper plating layer is formed on the base metal layer by using a continuous metal coating device. The thickness of the copper coating is 0.5-3.0μm. The thickness of the polyimide film is 10-50μm. The polyimide film has even surface.

Description

Metal-Coated Polyimide Film and Process for Producing the Same {Metal-coated Polyimide Film and Process for Producing the Same}

The present invention relates to a metal-coated polyimide film and a method for manufacturing the same, and more particularly, a metal having very few pinholes, high corrosion resistance, and excellent dimensional stability, which can cope with fine pitching of electronic circuits. It relates to a coated polyimide film and a production method thereof.

Metal-coated polyimide films are widely used as substrates for mounting IC chips for driving for displaying images on liquid crystal displays. In recent years, COF (Chip-on-Film) attracts attention as a method of mounting a driving IC chip for liquid crystal display.

Compared to TCP (Tape® Carrier Package), which is the mainstream of the conventional mounting method, the COF enables the fine pitch of the wiring, the miniaturization of the driving IC chip to be mounted, and the ease of reducing the mounting cost. have.

As a general manufacturing method of COF, the metal-coated polyimide film which formed the metal film on the surface of the polyimide film which is high heat resistance and high insulation resin is used as a board | substrate, and the metal film on the board | substrate is dug out by the photolithographic technique. After patterning to form the wiring, a method of tin plating a desired portion of the wiring, for example, and then coating the desired portion with a solder resist is used.

As the metal-coated polyimide film for COF where fine pitch mounting is performed, the mainstream is to form a metal film directly on the polyimide film surface without using an adhesive layer. The metal-coated polyimide film is, for example, after plasma treatment of the surface of the polyimide film, the nickel-chromium alloy is adhered to a thickness of 70 to 500 mm by the sputtering method to form a sputter layer, and then the It is obtained by making copper adhere by the plating method on it, and then performing thick electrolytic copper plating (refer patent document 1: 2nd page).

When forming a sputtering layer by the said sputtering method, a sputtering is performed in vacuum by conveying a polyimide film continuously by the reel-to-reel method, for example. For example, the vacuum chamber provided with the 1st and 2nd roll-attachment shaft which can be driven by a winding-up and unwinding machine and can wind up and wind up a film of a long axis, and the film form adhered to the said vacuum tank. A sputtering unit to form a film on the film, and unwinds the film from the roll set on one side of the roll-attachment shaft, transfers it through an area facing the sputter unit of the vacuum chamber, and winds up the roll on the other side of the roll-attachment shaft. The continuous sputtering apparatus which continuously forms a film on it while conveying this is used (refer patent document 2: Unexamined-Japanese-Patent No. 2006-336029, page 2).

Due to the recent rapid progress in high-definition liquid crystal display screens and miniaturization of liquid crystal drive IC chips, high-density wiring, i.e., fine pitching, has become strong even for COF produced using the metal-coated polyimide film. Is required. However, when attempting to produce fine pitch COF using the metal-coated polyimide film obtained by the conventional method as described above, the wiring having a portion missing by the pinhole present in the metal layer of the metal-coated polyimide film This increased the yield of the product, the resulting wiring was low in corrosion resistance, and the wiring could be peeled off in the fine circuit section. Thus, it was in a state unsatisfactory for fine pitch COF.

The cause of the pinhole is solved by the material of the sputter layer itself (see Patent Document 3), or by the activation treatment performed on the sputter layer to improve the adhesion with the electroplated coating film (see Patent Document 4). However, as a result of adopting these various methods, some pinholes can be reduced, but they are still not sufficient for the production of fine pitch COF.

When the plurality of films are provided to the film, the cause of the pinhole is regarded as a foreign matter attached when the film moves between the film deposition apparatuses in a state exposed to the air, and the plurality of surfaces on which two surface treatment means are fixed to the rotating shaft. By providing a processing means, a composite vacuum surface treatment apparatus capable of simultaneously performing a plurality of surface treatments by changing the surface treatment means facing the film treatment position has been proposed (see Patent Document 5: First page). . It is explained that the use of this apparatus prevents the film during the process from being exposed to the air, thereby eliminating defects such as the generation of pinholes and the deterioration of adhesiveness in the formed thin film. However, although the copper-coated polyimide film in which the copper layer was formed to have a thickness of 8 μm by the wet plating method on the surface-treated polyimide film using the above apparatus is disclosed in the examples, a detailed description of the improvement of pinhole and adhesion And the effect is unclear.

In addition, although the present invention relates to a strip-shaped member in which a semiconductor layer is deposited, not a metal layer, the cause of the unevenness occurring on the surface is foreign matter mixed between the strip-shaped member and the transport steering roller when the strip-shaped member is transferred. In the process of sequentially stacking the semiconductor thin film on the strip-shaped member and winding it up, the occurrence of unevenness is prevented by sandwiching the eye paper between the strip-shaped member and the steering roller so that no physical contact occurs between the strip-shaped member and the steering roller. The method is proposed (refer patent document 6: 3, page 6). According to this method, semiconductor films with few defects can be produced in high yield in large quantities.

However, when attempting to apply with the manufacturing method of the metal-coated polyimide film which excludes the contact of a strip | belt-shaped member and a steering roller by eye paper in this way, a mechanism for inserting eye paper is needed and the apparatus becomes complicated, There is a possibility that foreign matter may be generated from the eye paper itself, causing defects in the copper layer. In addition, there is a problem that when a special one is used as a child paper, it rises.

Therefore, a method that can reduce the pinhole number of the metal-coated polyimide film is still not developed.

Conventional COF was obtained by forming a wiring by a subtractive method using a metal-coated polyimide film having a copper layer having a thickness of 5 to 12 μm. However, in order to manufacture fine pitch COFs having a required line width of 25 μm or less, wiring by a semi-additive method using a metal-coated polyimide film having a copper layer having a thickness of 1.0 to 3.0 μm is required. It is common to form

Thus, in the metal-coated polyimide fill having a smaller thickness of the copper layer than the conventional one, in addition to the strong reduction in pinholes and high corrosion resistance described above, the dimensions at the time of etching and heating to increase the product yield It is also desired that there is little variation in the rate of change, that is, excellent in dimensional stability.

As described above, there is a demand for a metal-coated polyimide film having a very small number of pinholes, high corrosion resistance, and excellent dimensional stability so as to meet the demand for fine pitching of an electronic circuit, and a manufacturing method thereof.

[Patent Documents]

-Patent Document 1: Japanese Patent Application Laid-Open No. 2002-252257 (see page 2)

-Patent Document 2: Japanese Patent Application Laid-Open No. 2006-336029 (see page 2)

-Patent Document 3: Japanese Patent Application Laid-Open No. 2006-73766

-Patent Document 4: Japanese Patent Application Laid-Open No. 2006-324474

-Patent Document 5: Japanese Patent Application Laid-Open No. 2007-063639 (see page 1)

-Patent Document 6: Japanese Patent Application Laid-Open No. 09-082652 (see pages 3 and 6).

SUMMARY OF THE INVENTION In view of the problems of the prior art, an object of the present invention is to provide a metal-coated polyimide film having very low pinholes, high corrosion resistance, and excellent dimensional stability in order to cope with fine pitching of electronic circuits, and to manufacture thereof. To provide a way.

MEANS TO SOLVE THE PROBLEM The present inventors discovered that the pinhole of the copper plating layer originated from the pinhole of the base metal layer, and formed the base metal layer by the dry-plating method by the reel-to-reel method as a result of having examined variously in order to solve the said subject. In this case, when the specific conditions are set, the number of pinholes on the surface of the base metal layer is greatly reduced. As a result, it has been found that the above problem can be solved by forming a copper plating layer on the base metal layer.

That is, according to the first invention of the present invention,

(A) forming a base metal layer composed of a nickel-chromium alloy layer and a copper layer on the surface of the polyimide film by a reel-to-reel method by dry plating; and then using a continuous plating apparatus, a copper plating layer on the base metal layer. A method for producing a metal-coated polyimide film comprising the step (b) of forming a film,

In step (a), when the surface of the base metal layer is observed by the light table by making only the polyimide film surface the portion in contact with the conveying device until the polyimide film on which the base metal layer is formed is wound on a roll, the diameter The number of the pinholes 10 micrometers or more shall be 20 or less with respect to an area of 160 mm angle, and in the process (b), the copper plating layer of thickness 0.5-3.0 micrometers is formed, The manufacturing method of the metal-coated polyimide film characterized by the above-mentioned. This is provided.

According to the second invention of the present invention, in the first invention, the polyimide film has a thickness of 10 to 50 µm and the surface is smooth, the method for producing a metal-coated polyimide film is provided.

According to the third invention of the present invention, in the first invention, in the step (a), the base metal layer is formed of a nickel-chromium alloy layer and a copper layer, in order to prepare a metal-coated polyimide film. A method is provided.

According to the 4th invention of this invention, in the said 3rd invention, the thickness of the said nickel-chromium alloy layer is 5-50 nm, The manufacturing method of the metal-coated polyimide film is provided.

According to a fifth aspect of the present invention, in the third or fourth aspect of the present invention, the nickel-chromium alloy layer is formed of a nickel-chromium alloy containing 5 to 30 mass% of chromium. A method for producing a polyimide film is provided.

According to the sixth invention of the present invention, in the third invention, the copper layer is provided with a method for producing a metal-coated polyimide film, characterized in that the thickness is 50 ~ 500 nm.

According to a seventh aspect of the present invention, in the first aspect of the present invention, in the step (b), the copper plating layer is formed by an electroplating method using a copper sulfate plating bath. Is provided.

According to the eighth invention of the present invention, in the seventh invention, the cathode current density is adjusted so that the internal stress of the formed copper plating layer becomes a tensile stress of 5 to 30 MPa in a state before the polyimide film is dried. A method for producing a metal-coated polyimide film is provided.

According to the 9th invention of this invention, As a metal-coated polyimide film obtained by the manufacturing method of any one of said 1-8 invention,

When the surface of the copper plating layer was observed with a light table, the number of pinholes having a diameter of 10 µm or more was 10 or less for an area of 160 mm angle, and the metal-coating was characterized in that the bending count of the MIT corrosion resistance evaluation was 2000 or more. A polyimide film is provided.

The tenth invention of the present invention is the metal-coated according to the ninth invention, wherein the etching dimensional change rate (Method # B) and the heating dimensional change rate (Method # C) are 0.03% or less with respect to the transfer direction and the perpendicular direction thereof. A polyimide film is provided.

The metal-coated polyimide film of the present invention has a very small number of pinholes, high corrosion resistance and excellent dimensional stability, and is very suitable as a substrate for fine pitching of electronic circuits. In addition, the manufacturing method transfers the polyimide film in a reel-to-reel manner, forms a nickel-chromium alloy layer on the surface of the polyimide film, and then, until the polyimide film on which the base metal layer is formed is wound on a roll, By making only the surface which contact | connects a conveying apparatus a polyimide film surface, since it is simple and suitable for industrial scale production, the industrial value is very high.

Hereinafter, the present invention will be described in detail.

One. Method for producing metal-coated polyimide film

The manufacturing method of the metal-coated polyimide film of this invention is demonstrated.

The production method of the present invention comprises a step (a) of obtaining a polyimide film having a base metal layer composed of a nickel-chromium alloy layer and a copper layer formed thereon by a dry plating method by a reel-to-reel method, and then A method for producing a metal-coated polyimide film comprising the step (b) of forming a copper plating layer on a base metal layer using a plating apparatus,

In the step (a), after the nickel-chromium alloy layer is formed, the transfer until the polyimide film on which the base metal layer is formed is rolled up on a roll is a portion in contact with the transfer device as the polyimide film surface only.

In the step (b), a copper plating layer having a thickness of 0.5 to 3.0 µm is formed, while the internal stress of the formed copper plating layer is a tensile stress of 5 to 30 MPa in a state before the polyimide film is dried.

In step (a), only the polyimide film surface is in contact with the transfer device when transferring the polyimide film after the nickel-chromium alloy layer is formed, and in step (b), a copper plating layer having a thickness of 0.5 to 3.0 µm is The technical significance of the present invention is that the forming and the internal stress of the formed copper plating layer become a tensile stress of 5 to 30 MPa in a state before the polyimide film is dried.

That is, in the step (a), when transferring the polyimide film after forming the nickel-chromium alloy layer, only the polyimide film surface is in contact with the conveying device. After the formation, the polyimide film on which the base metal layer is formed is wound on the roll, and the foreign material such as a waste material between the nickel-chromium alloy layer and the copper layer and the conveying roller or free roller of the conveying equipment are in contact with each other. This is because it is caused by being pressed by the nickel-chromium alloy layer or the copper layer.

When the base metal layer is formed in this way, the number of pinholes having a diameter of 10 μm or more generated in the base metal layer can be 20 or less for an area of 160 mm angle. This is important. That is, as will be described later, when the copper plating layer is formed on the base metal layer by the electroplating method, the thickness of the copper plating layer is increased, and the number of pinholes that can be detected by the light table is reduced, but the process (b) This is because, when the thickness of the copper layer formed in the above) is 3.0 µm or less, such an effect is small, and pinholes having a diameter of 10 µm or more generated in the base metal layer are likely to remain as pinholes as seen on the surface of the metal-coated polyimide film.

Furthermore, according to the results of the present inventors' investigation, in the case where the nickel-chromium alloy layer or the copper layer is formed by vapor deposition or sputtering, pinholes having a diameter of 10 µm or more are hardly generated under normal conditions.

In the step (b), forming a copper plating layer having a thickness of 0.5 to 3.0 µm is a requirement of the metal-coated polyimide film corresponding to fine pitching, and high corrosion resistance is obtained. When the thickness of the copper plating layer exceeds 3.0 µm, the number of bendings of the MIT fracture resistance evaluation is less than 2000, and high fracture resistance cannot be obtained. On the other hand, if the copper plating layer is less than 0.5 mu m, sufficient conductivity cannot be obtained for the wiring formed by using the metal-coated polyimide film.

In the step (b), the internal stress of the formed copper plating layer is set to a tensile stress of 5 to 30 MPa in a state before the polyimide film is dried, and the internal stress of the copper plating layer due to shrinkage of the polyimide film due to drying. By reducing the etch rate change rate and the heating dimensional change rate to 0.03% or less with respect to the direction perpendicular to the feed direction, dimensional stability is ensured.

Hereinafter, it demonstrates per process.

One) Process (a)

Process (a) is a process of conveying a polyimide film continuously in a reel-to-reel method, forming a base metal layer by the vapor deposition method or sputtering method on the surface of a polyimide film, and winding up to a roll. In the present invention, a nickel-chromium alloy layer is first formed on the polyimide film surface. And a copper layer is formed on a nickel-chromium alloy layer.

In order to make it possible to respond to fine pitch, the polyimide film used for this invention is 10-50 micrometers in thickness, It is preferable to set it as 25-38 micrometers in thickness preferably. Films of such thickness are generally industrially produced and used. In addition, in consideration of the contact between the polyimide film and the base metal layer during winding, it is preferable that the surface of the polyimide film is smooth at the point of preventing pinhole generation.

Although the vapor deposition method, sputtering method, etc. are used as said dry plating method, the various literatures which have been proposed and reported about deposition conditions and sputtering conditions can be referred to.

It is preferable that the thickness of the nickel-chromium alloy layer which comprises a base layer shall be 5-50 nm. By setting it as 5-50 nm, the improvement effect of the said anti-migration characteristic can be acquired. If the thickness is less than 5 nm, the migration resistance may not be sufficient. If the thickness is more than 50 nm, the etching property may be deteriorated. There is.

As a nickel-chromium layer, it is preferable to use the nickel alloy containing 5-30 mass% of chromium. If the chromium content is less than 5% by mass, the migration resistance may not be sufficient. If the chromium content is more than 30% by mass, the etching property is lowered. When forming a wiring board such as COF, the base metal layer may not be sufficiently removed. There is a case where the insulation of the liver cannot be secured.

The thickness of the copper layer formed on the nickel-chromium layer is preferably 50 to 500 nm. This is because if the thickness is less than 50 nm, sufficient conductivity may not be obtained in the step (b) to form the copper plating layer by the electrocopper plating method. If the thickness exceeds 500 nm, the formation time by the sputter becomes long, and the productivity is lowered.

In addition to copper, the copper layer may be formed using a copper alloy such as a copper-nickel alloy or a copper-nickel-chromium alloy in accordance with the purpose of improving corrosion resistance and the like. However, the copper layer is preferably pure copper in order to secure conductivity.

Most importantly in the process (a), as described above, after forming a nickel-chromium alloy layer on the surface of the polyimide film to be transferred in a reel-to-reel manner, the polyimide film having the base metal layer formed thereon is wound on a roll. Until it does so, only a polyimide film surface is supported by a conveying apparatus so that a nickel-chromium alloy layer surface or copper layer surface may not contact a conveying apparatus, and it conveys.

By doing in this way, the number of pinholes 10 micrometers or more in diameter which generate | occur | produce in a base metal layer can be made into 20 or less with respect to an area of 160 mm angle.

The copper layer constituting the base metal layer has a lower hardness than the nickel-chromium layer below it, which increases the possibility of pinholes coming into contact with the transfer device. After the formation of the copper layer, it is particularly important to transport the copper layer and the transfer device so that they do not come into contact with each other.

The polyimide film on which the base metal layer is formed is wound on a roll. At this time, the surface of the base metal layer and the surface of the polyimide film are in contact with each other. However, the polyimide film is flexible, so that even when the two are in contact with each other, there is no problem. However, in the case where the winding pressure is high (the tension applied to the polyimide film is high), in spite of the flexibility of the polyimide, pinholes may occur due to the fine convex portions on the surface of the polyimide film. Therefore, it is preferable that the surface of the polyimide film to be used is smooth.

In order to transfer by the reel-to-reel method without contacting a base metal layer and a conveying installation, after forming the said nickel-chromium alloy layer, only the polyimide film surface which is a back surface may be supported by a conveyance roll or a free roll, and it may convey. This is because contact with a transfer facility or the like on the back side of the polyimide film in which the base metal layer does not exist is not a problem.

As another method, a method of conveying the polyimide film in a straight line shape by only adjusting the position of the take-up axis and the take-up axis can be considered. However, in such a method, first, since a strong tension must be applied to the polyimide film in order to maintain a straight transfer line, the film may be deformed, which is not preferable.

Moreover, since the thickness of the axis which winds up a polyimide film and the thickness of the axis which winds up a polyimide film change with time, it is complicated to maintain the space | interval between a target and a polyimide film in a vapor deposition apparatus or a sputtering apparatus at a constant. Since a mechanism is required, it is furthermore undesirable.

2) Process (b)

Process (b) is a process of forming a copper plating layer on the base metal layer formed by said process (a) by the electrocopper plating method, the electroless copper plating method, or a combination thereof.

The copper plating layer formed is made into 0.5-3.0 micrometers in thickness, considering the case where wiring boards, such as COF corresponding to fine pitch formation, are formed by the semi-additive process as mentioned above. Such thickness is limited to the above range in terms of high flex resistance and conductivity, as described above.

However, when the thickness of the copper layer is 3.0 μm or less, the following matters should be noted.

That is, when the copper layer is formed by the electroplating method, copper is deposited in the base metal to form the copper layer, but the portion where the base metal does not exist, i.e., in the pinhole part, the plated metal in the direction of the pinhole from the copper deposited around. This precipitates and covers the pinholes. For this reason, the pinhole of the base metal is lost from the appearance so that the thickness of the obtained copper layer is thick.

However, when the thickness of the copper layer is 3.0 μm or less, the fine pinholes on the surface of the base metal layer are covered by the deposited copper and disappear from the appearance, while the pinholes having a diameter of 10 μm or more are completely covered by the deposited copper and are lost from the surface. In many cases, it remains as a pinhole on the metal-coated polyimide film surface in many cases. Therefore, the number of pinholes cannot be greatly reduced in the step (b).

For this reason, in step (b), a copper plating layer is formed on this base metal layer by using a polyimide film having a base metal layer of 20 or less for an area of 160 mm angle with a pinhole number of 10 µm or more obtained in step (a). Form. In this way, the number of pinholes 10 micrometers or more in diameter which can be detected by light table observation can be made into 10 or less with respect to an area of 160 mm angle.

Therefore, in step (a), obtaining a polyimide film having a base metal layer of 20 or less for an area of 160 mm angle with a pinhole number of 10 µm or more in diameter is a charging agent of step (b) and is very important.

Moreover, even if the pinholes of the base metal layer are lost on the surface by carefully selecting copper plating conditions, the reality is that copper does not precipitate out of the pinholes and thus loses the pinholes, so that the pinholes are simply hidden from the surface. . For this reason, in such a metal-coated polyimide film, not only the adhesion between the copper layer and the base metal layer, or the base metal layer and the polyimide film is insufficient, but also the pinholes of the base metal layer are peeled off as a starting point of peeling during bending. Because of its ease, it does not result in a highly refractory metal-coated polyimide film.

In the present invention, the copper plating layer is formed by an electroplating method, an electroless plating method, or a combination thereof. However, in view of productivity and cost, the copper plating layer is preferably formed by an electroplating method, and an electroplating method using a copper sulfate plating bath. This is more preferable.

In this case, the copper sulfate plating bath used is not specifically limited, The copper sulfate plating bath generally used may be used. In addition, plating conditions are not special and the conditions normally used may be sufficient.

In the method of this invention, in the formed copper plating layer, it is preferable to control so that the internal stress may be a tensile stress of 5-30 MPa in the state before a polyimide film is dried. Such control can be made by selecting the plating conditions such as the composition of the copper sulfate plating bath to be used, the cathode current density, the electrolytic solution supply amount, and the like when the copper plating layer is formed by the electrocopper plating method.

The simplest method is to suppress the cathode current density. Assuming that an ordinary copper sulfate plating bath is used, the average cathode current density is preferably 2.0 A / dm ² or less, and more preferably 1.0 A / dm ² or less. This is because if the average cathode current density exceeds 2.0 A / dm ² , the precipitation of copper becomes uneven, making it difficult to control the internal stress of the copper plating layer.

The copper plating layer having a tensile stress of 5 to 30 MPa in the state before the polyimide film is dried is contracted by the drying of the polyimide film, and the internal stress of the copper plating layer is alleviated. As a result, the rate of change in etching dimensions and heating dimensions The rate of change is 0.03% or less with respect to the conveying direction and its perpendicular direction, resulting in a metal-coated polyimide film excellent in dimensional stability.

2. Metal-coated Polyimide Film

The metal-coated polyimide film of the present invention is a metal-coated polyimide film in which a base metal layer is directly formed on a polyimide film surface and a copper plating layer is formed on the base metal layer. The thickness of copper plating layer is 0.5-3.0 micrometers, and when the surface of such copper plating layer is observed with the light table, the number of the pinholes 10 micrometers or more in diameter is 10 or less for the area of 160 mm, and MIT corrosion resistance evaluation The number of times of bending is 2000 or more, and the etch change rate (Method # B) and the heating change rate (Method # C) are not more than 0.03% as absolute values with respect to the direction of transfer and its right angle.

In the present invention, as a result of observing the surface of the copper plating layer with a light table, it is fine to use 10 or more metal-coated polyimide films having more than 10 pinholes within an area of 160 mm angle. This is because, when a wiring board such as pitch COF is made, the possibility of disconnection in the wiring increases, which lowers the yield of the wiring board such as fine pitch COF. Moreover, it is because reliability, such as COF, cannot be ensured.

The reason why the thickness of the copper plating layer is 0.5 to 3.0 µm is because it satisfies the requirements of the metal-coated polyimide film corresponding to fine pitching, and high corrosion resistance can be obtained. This is because when the thickness of the copper plated layer exceeds 3.0 µm, the number of bendings of the MIT corrosion resistance evaluation may be less than 2000 times, and high corrosion resistance cannot always be stably obtained. On the other hand, when the copper plating layer is less than 0.5 µm, it is because sufficient conductivity cannot be obtained with a circuit formed using a metal-coated polyimide film.

The number of bending times of the MIT corrosion resistance evaluation is set to 2000 or more times when the wire is processed on a fine pitch COF or the like and used for the bending portion of the electronic component, even if the bending is repeated during use, the wiring is not easily disconnected. Because it satisfies.

The etching dimensional change rate (Method # B) and the heating dimensional change rate (Method # C) of 0.03% or less with respect to the transfer direction and the perpendicular direction thereof are outside of this range and correspond to the fine pitch, for example, the wiring width of 20 to This is because, when a wiring board such as a COF having a wiring pattern of 25 µm is formed and the IC chip is mounted thereon, the bonding failure between the electrode pad on the surface of the IC chip and the lead of the wiring may increase. This tendency is remarkable when the IC chip is mounted by the flip chip bonding method.

In order for the polyimide film used for this invention to be able to respond to the fine pitch of the metal-coated polyimide film finally obtained, it is preferable that the surface is smooth and thickness is 10-50 micrometers, More preferably, thickness 25 It is assumed that it is ˜38 μm.

The base metal layer has a two-layer structure of a nickel-chromium alloy layer and the same layer, and the nickel-chromium alloy layer is formed of a nickel-chromium alloy having a thickness of 5 to 50 nm and containing 5 to 30 mass% of chromium. It is desirable to. If it is less than 5 nm, the migration resistance cannot be sufficiently obtained, and if it exceeds 50 nm, the etching property is degraded, and when forming a wiring board such as COF, the base metal layer may not be sufficiently removed to secure insulation between the wirings. Because. In addition, the thickness of the copper layer is preferably 50 to 500 nm. When the copper plating layer is less than 50 nm, sufficient electroconductivity may not be obtained when the electroplating method is used. When it exceeds 500 nm, the formation time by the sputter becomes longer and productivity is lowered.

[Example]

Hereinafter, although an Example and a comparative example of this invention demonstrate this invention further in detail, this invention is not limited by these Examples. In addition, various physical properties of the metal-coated polyimide film obtained in Examples and Comparative Examples were measured and evaluated according to the following measurement and evaluation methods, and the following were used as the used polyimide film.

One. Measurement, evaluation method

(1) Pinhole size: Measured visually using a transmitted light table.

In this invention, the magnitude | size of a pinhole means the maximum distance which measured arbitrary two points from the circumference | surroundings of a pinhole, and a pinhole of 10 micrometers or more means that this maximum distance is 10 micrometers or more.

(2) MIT corrosion resistance evaluation: The number of times until the bending was reached in the MIT corrosion resistance test method with R = 0.38, load 1000 g, and line width 0.5 mm, carried out by the method according to JPCA BM01-11.6 and JIS C5016-8.7. Was obtained.

(3) Etching dimensional change rate (Method # B) and heating dimensional change rate (Method # C): Measured according to the method defined in IPC-TM-650, 2, 2 and 4. The figures were evaluated in absolute terms.

2. Polyimide film

The used polyimide film is a 35-micrometer-thick polyimide film (the UHB Co., Ltd. product, UPILEX35SGA).

(Example 1)

The process will be described below.

One. Formation of the base metal layer (step (a))

While continuously conveying the polyimide film by the unwinder and the winder, a nickel-chromium alloy layer having a thickness of 23 nm was formed by a conventional direct current sputtering method. The chromium concentration of the nickel-chromium layer was 20 mass%.

Then, a copper layer having a thickness of 100 nm was formed thereon to obtain a base metal layer.

The apparatus used for the formation of the base metal layer was a device in which a winding machine, a winding machine, and a sputtering device were installed in a vacuum chamber, and after the nickel-chromium layer was formed, only the polyimide film surface was supported by the transfer roll and wound around the winding roll. .

The polyimide film on which the base metal layer was formed was observed with a transmitted light table, and the results are shown in Table 1.

2. Forming Copper Plating Layer (Step (b))

It was formed by electroplating a copper plating layer having a thickness of 1.3 mu m on the base metal layer using a conventional copper sulfate plating bath. The copper sulfate plating bath used was 23 g / l in copper concentration, and bath temperature was 27 degreeC. Further, the plating bath was a continuous plating bath, and electroplating was performed by continuously transferring each bath by a winding machine and a winding machine. The feed rate was 115 m / h, the average cathode current density of the plating bath was adjusted to ≤ 1.0 A / dm ² , and the internal stress of the plating film was adjusted in the cell manner before the polyimide film was dried. By laminating, it was made to become the tensile stress corresponding to the range of 5-30 MPa. In the measurement by the prior test piece, the internal stress of the plating film became the tensile stress of 15 MPa in the state before a polyimide film dries.

In the obtained metal-coated polyimide film, the number of 10 micrometers or more of pinholes was observed and calculated | required by the transmitted-light type light table, and evaluation of MIT corrosion resistance and dimensional stability was also shown, and the result obtained is shown in Table 1.

(Example 2)

A metal-coated polyimide film was obtained in the same manner as in Example 1 except that a polyimide film having a thickness of 35 μm (manufactured by Kaneka Co., Ltd., Apical-35FP) was used as the polyimide film. Evaluated. The obtained results are shown in Table 1.

The internal stress of the plated film was such that the film formation in the cell system was laminated in a state before the polyimide film was dried, so that the tensile stress was in the range of 5 to 30 MPa.

(Example 3)

A metal-coated polyimide film was obtained in the same manner as in Example 1 except that the thickness of the copper plating layer was 0.5 μm, and evaluated in the same manner as in Example 1. The obtained results are shown in Table 1.

The internal stress of the plated film was such that the film formation in the cell system was laminated in a state before the polyimide film was dried, so that the tensile stress was in the range of 5 to 30 MPa.

In the measurement by the prior test piece, the internal stress of the plating film became the tensile stress of 8 MPa in the state before a polyimide film dries.

(Example 4)

A metal-coated polyimide film was obtained in the same manner as in Example 1 except that the thickness of the copper plating layer was 3.0 μm, and the evaluation was performed in the same manner as in Example 1. The obtained results are shown in Table 1.

In the measurement by the prior test piece, the internal stress of the plating film became 25 MPa tensile stress in the state before a polyimide film was dried.

(Example 5)

A metal-coated polyimide film was obtained in the same manner as in Example 1 except that the average cathode current density of the plating bath was adjusted to ≤ ^2.0 A / dm ^{2 so} that the internal stress of the plating film was a tensile stress of 30 MPa. And evaluated in the same manner. The obtained results are shown in Table 1.

(Example 6)

Using the copper clad polyimide film obtained in Examples 1 to 5, COF having a wiring spacing of 25 µm was semi-additive method, and the wiring processing yield was calculated. When the thing of Example 1 was used, it was 85%, Example Fine pitch is 83% when using 2, 80% when using Example 3, 83% when using Example 4, 80% when using Example 5, etc. It was satisfactory for correspondence.

(Comparative Example 1)

In the winding portion of the sputtering apparatus, a metal-coated polyimide film was obtained in the same manner as in Example 1 except that a device having a mechanism for supporting the polyimide film by contacting the roll with the surface of the base metal layer after copper layer formation was obtained. , It was evaluated in the same manner as in Example 1. The obtained results are shown in Table 1.

(Comparative Example 2)

In the winding portion of the sputtering apparatus, a device having a mechanism for supporting a polyimide film by contacting the roll with the surface of the base metal layer after copper layer formation is used, and the average cathode current density of the plating bath is 3 to 5 A / in the copper plating process. A metal-coated polyimide film was obtained in the same manner as in Example 1 except that the copper plating layer having a thickness of 8.5 μm was adjusted to dm ² and evaluated in the same manner as in Example 1. The obtained results are shown in Table 1.

(Comparative Example 3)

It was 61% when the wiring work yield was calculated | required by the method similar to Example 6 using the copper clad polyimide film obtained by the comparative example 1.

TABLE 1

In Table 1, TD-B is the etching dimension change rate (Method # B) in the direction orthogonal to the conveyance direction of a polyimide film, and TD-C is the heating dimension change rate in the orthogonal direction and the conveyance direction of a polyimide film ( Method C).

From Table 1 and the above results, the surface of the copper-clad polyimide film of Examples 1 to 5 manufactured in accordance with the present invention has few pinholes, high corrosion resistance, small dimensional fluctuations during etching and heating, and excellent dimensional stability. It can be seen that.

On the other hand, in Comparative Example 1 in which the surface of the copper layer was not kept in a non-contact state after the formation of the base metal layer, the corrosion resistance and the dimensional stability were good, but a large number of pinholes of 10 μm or more existed to obtain a copper-coated polyimide film for fine pitch. Could not. In addition, since the surface of the copper layer was not kept in a non-contact state after the formation of the base metal layer, and Comparative Example 2 having a copper plating layer thickness of 8. 5 占 퐉 thickened the copper plating layer, the diameter 10 that can be detected by the light table was 10. Although the pinhole number of micrometers or more improved, the corrosion resistance and dimensional stability did not become a favorable value.

The metal-coated polyimide film of the present invention is a metal-coated polyimide film having a pinhole defect of 10 or less for an area of 160 mm or more and a very small number of pinhole defects of 10 μm or more and excellent in MIT corrosion resistance and dimensional stability. Therefore, it can be used suitably also for wiring boards, such as fine pitch COF, PWB, FPC, and TAB, and a semi-additive board | substrate.

In addition, the method of the present invention has high industrial value because it is simple and suitable for mass production.

Claims (10)

(A) forming a base metal layer consisting of a nickel-chromium alloy layer and a copper layer on the surface of the polyimide film by a dry plating method by a reel-to-reel method, and then using the continuous plating apparatus on the base metal layer A method for producing a metal-coated polyimide film comprising the step (b) of forming a copper plating layer, In step (a), when the surface of the base metal layer is observed by the light table by making only the polyimide film surface the portion in contact with the conveying device until the polyimide film on which the base metal layer is formed is wound on a roll, the diameter The number of the pinholes of 10 micrometers or more is made 20 or less with respect to an area of 160 mm angle, and in the process (b), the copper plating layer of 0.5-3.0 micrometers thickness is formed, The metal-coated polyimide film of Manufacturing method. The method for producing a metal-coated polyimide film according to claim 1, wherein the polyimide film has a thickness of 10 to 50 µm and a smooth surface. The method for producing a metal-coated polyimide film according to claim 1, wherein in step (a), the base metal layer is formed in the order of the nickel-chromium alloy layer and the copper layer. 4. The method of claim 3, wherein the nickel-chromium alloy layer has a thickness of 5 to 50 nm. The method for producing a metal-coated polyimide film according to claim 3, wherein the nickel-chromium alloy layer is formed of a nickel-chromium alloy containing 5 to 30 mass% of chromium. The method of claim 3, wherein the copper layer has a thickness of 50 to 500 nm. The method for producing a metal-coated polyimide film according to claim 1, wherein in the step (b), the copper plating layer is formed by an electrocopper plating method using a copper sulfate plating bath. 8. The production of the metal-coated polyimide film according to claim 7, wherein the cathode current density is adjusted so that the internal stress of the formed copper plating layer becomes a tensile stress of 5 to 30 MPa in a state before the polyimide film is dried. Way. As a metal-coated polyimide film obtained by the manufacturing method according to any one of claims 1 to 8, When the surface of the copper plating layer was observed with a light table, the number of pinholes having a diameter of 10 µm or more was 10 or less for an area of 160 mm angle, and the metal-coating was characterized in that the bending count of the MIT corrosion resistance evaluation was 2000 or more. Polyimide film. 10. The metal-coated polyimide film of claim 9, wherein the etching dimensional change rate (Method # B) and the heating dimensional change rate (Method # C) are 0.03% or less with respect to the transfer direction and a right angle direction thereof.