JPH1192917A - Metal polyimide film laminated body - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a metal-coated polyimlde substrate having high reliability with a specified pinhole number and specified peeling strength by subjecting the surface of a polyimide resin film to plasma reforming treatment and depositing a metal thin film of Cr, Ni or Ti and a Cu thin film. SOLUTION: One or both surfaces of a polyimide resin film having about 10 to 250 μm film thickness are subjected to plasma reforming to obtain 0.27 to 0.45 peak area intensity ratio of O/C on the surface measured by X-ray photoelectron spectroscopy. Then a metal thin film of one or more metals of Cr, Ni, Ti is formed in 5 to 200 nm thickness on the treated surface by dry plating such as vapor deposition, sputtering and ion plating. Then a Cu thin film is formed to 20 to 500 nm thickness on the metal thin film by dry plating, and further the Cu thin film is formed in specified thickness by electrolytic plating. Thus, a metal polyimide film laminated body is obtd., and the plating thin film has <=50/m<2> distribution of pinholes having 5 to 30 μm diameter and >=700 g/cm peeling strength.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a printed wiring board,
The present invention relates to a laminate of a metal and a polyimide film used for a flexible printed circuit board and the like, and relates to a metal polyimide film laminate having few pinholes and excellent peel strength.

[0002]

2. Description of the Related Art Polyimide resins have excellent heat resistance.
Further, since it is comparable to other plastic materials in mechanical, electrical and chemical properties, for example, a printed wiring board (PWB), a flexible printed board (FP)
C), and is often used as an insulating substrate material for electronic device parts such as a substrate for automatic tape bonding (TAB) mounting. Such a substrate for PWB, FPC, or TAB mounting has a conductive coating on the polyimide resin film surface. It is mainly obtained by processing a copper polyimide substrate on which copper is formed.

[0003] Such a metal-coated polyimide substrate (metal-polyimide film laminate) includes a three-layer substrate in which a polyimide resin film and a metal film are bonded via an adhesive, and a two-layer substrate in which a metal film is formed directly on the polyimide resin film. Currently, there is a great expectation for the use of a two-layer substrate which has high reliability of the bonding interface and can freely select the thickness of the polyimide resin film and the metal film.

As a method of forming a metal film directly on a polyimide resin film on these two-layer substrates, there are a vapor deposition / sputtering / ion plating method as a dry plating method, an electroless plating method as a wet method, and the like. The dry process is expected to have high productivity due to its simple process.

[0005]

However, in the case of the vapor deposition / sputtering method in this dry method, the reliability of the substrate will be reduced unless the surface of the polyimide resin film is modified by any treatment before forming the metal film. Such adhesion strength cannot be obtained. The adhesion strength referred to here does not mean only the microscopic bonding strength between the polyimide and the coated metal, but also includes the peeling strength standardized by JIS, JPCA, etc., including that. Considering UL standards etc., at least 500g / cm under various environments
The above is necessary.

[0006] Therefore, how to perform this surface modification is one of the important issues in the dry method, and in order to obtain the adhesion strength related to the reliability of the substrate, an appropriate amount of the surface modification is quantitatively grasped. There is a need to.

In the prior art, in order to obtain an adhesion strength related to the reliability of the substrate, for example, a plasma reforming method is used to limit the operation factors (plasma output, gas type / flow rate, pressure, time, etc.). Although there are examples, they generally differ depending on the plasma generation mechanism, scale, and shape of the apparatus, and thus cannot be generally used. There is also an example in which the plasma modification necessary for obtaining the adhesion strength related to the reliability of the substrate is limited by the surface tension of the modified polyimide resin film surface.

The present invention has been made in view of the above problems, and has high reliability even if any kind of polyimide resin film or plasma reformer is used.
It is an object of the present invention to provide a method for manufacturing a metal-coated polyimide substrate on which a WB, FPC, or TAB mounting substrate can be formed.

[0009]

According to the present invention, as a result of research for solving the above-mentioned problems, one or both surfaces of a polyimide resin film have been plasma-modified. Spectrometer (XPS)
From the analysis of the surface of the polyimide resin film, it was achieved by controlling the O / C (oxygen / carbon ratio) to be from 0.26 to 0.45 and then performing the following metal lamination. . That is, the present invention provides chromium, nickel,
A metal polyimide film laminate provided with at least one metal thin film selected from titanium and a copper thin film, wherein a pinhole (hereinafter referred to as 5.30 PH) having a diameter of 5 μm (micrometer) to 30 μm (micrometer) is provided in the laminate. Is not more than 50 per square meter, and the peel strength between the polyimide resin film and the metal thin film is 70.
0 g / cm or more (measured at room temperature) is a metal polyimide film laminate, wherein the metal thin film is formed by dry plating and has a thickness of 5 to 200
wherein the copper thin film is formed by dry plating, the copper thin film having a thickness of 20 to 500 nm, and a copper thin film formed by electrolytic plating. It is a metal polyimide film laminate described above.

In order to obtain the adhesion strength related to the reliability of the substrate, it is necessary to appropriately modify the surface of the polyimide resin film by plasma. Although the mechanism of the adhesion strength development by this plasma modification has not been elucidated yet, from the examination of the present invention, the O / O ratio of the surface of the modified film by XPS was determined.
It was found that by performing the plasma reforming while controlling the C peak area intensity ratio to be a ratio of 0.27 to 0.45, a laminate having excellent adhesion strength and a low 5.30 PH was obtained.

Therefore, although the behavior and the function and effect are not clear, it is possible to determine the degree of plasma modification necessary for developing a high adhesion strength that can ensure reliability by focusing on the amount of change.

The XPS used here means that the surface of a sample is irradiated with X-rays, the kinetic energy of photoelectrons emitted from the sample is measured, and the binding energy of electrons specific to the obtained various elements is determined. This is an analysis method for examining the composition and bonding state at several tens of angstroms of the sample surface layer by analyzing.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The polyimide film in the present invention is not particularly limited, but specific examples include Kapton, Upilex, Apical and the like. The film thickness of the film is preferably from 10 μm to 250 μm. In the laminate of the present invention, the film is subjected to a plasma treatment to improve the adhesion to the metal laminate afterwards.
In this plasma treatment, a known plasma treatment can be used. However, even if the plasma treatment is inadvertently performed, the laminate having excellent adhesion strength and a low 5.30 PH of the present invention cannot be obtained. The O / C peak area intensity ratio by XPS of the film surface of No. 1 was 0.
It is necessary to control the plasma processing so that the ratio becomes 27 to 0.45.

At least one metal thin film selected from chromium, nickel, and titanium is formed on the film subjected to the plasma treatment by the controlled plasma treatment. The formation of the metal thin film is formed by dry plating. The dry plating is not particularly limited, and may be formed by evaporation, sputtering, or the like.
What is necessary is just to select and use suitably from ion plating etc., and it is preferable that the film thickness is 5-200 nm. Next, a copper thin film having a thickness of 20 to 500 nm is formed on the metal thin film by dry plating. Further, a thick copper film is formed on the obtained laminate on which the two-layered metal thin film is formed by known electrolytic plating, and is used for a printed circuit board or the like.

{Evaluation of 5.30 PH} The obtained laminate was cut into 15 cm squares and placed on a light table to specify the position of transmitted light, and the pinhole (P
All of H) were measured for the size by an optical microscope and the number thereof was measured, and the number of pinholes having a diameter of 5 μm (5 μm) to 30 μm (30 μm) per square meter was evaluated. ｝ Evaluation of peel strength (adhesion strength)｝ The obtained laminate was processed into a metal thin film layer so as to form a pattern having a line width of 90 μm.
It was measured and evaluated by a 90-degree direction tensile test.

Hereinafter, the present invention will be described more specifically with reference to examples, but the present invention is not limited to only these examples.

【Example】

* Example 1 Kanefuchi Chemical Co., Ltd. polyimide film (thickness 50
μm 2) One surface (bright surface) of NPI-50 was subjected to plasma treatment (this treatment was performed while controlling the O / C peak area intensity ratio of the surface by XPS to be 0.31). After modification by plasma treatment, a 30-nm-thick deposited nickel film is formed, and a 100-nm-thick
An nm vapor-deposited Cu film was formed, and 35 μm electrolytic copper plating was further performed. Using a mask having a predetermined shape on the copper surface of the substrate, an etching process was performed according to the pattern obtained after applying and drying a resist, and processed so as to obtain a pattern having a line width of 90 μm.

The number of “5.30 PH” of the metal polyimide laminate obtained as described above was 0, and the “peel strength” at room temperature was 1300 g / cm after pattern processing. "Peel strength" after treatment at 180 ° C for 60 minutes
Was 1250 g / cm.

Example 2 A method of manufacturing a laminate similar to that of Example 1 was performed, except that nickel was changed to chromium. The number of “5.30 PH” of the obtained metal polyimide laminate was 0, and the “peel strength” at room temperature was 1400 g / cm. 180 ° C
The "peel strength" after the treatment for 60 minutes was 1,400 g / cm.

Example 3 The same method as in Example 1 was used, except that a titanium vapor-deposited film was used instead of the nickel vapor-deposited film. The number of “5.30 PH” of the obtained metal polyimide laminate was 2, and the “peel strength” at room temperature was 1200 g / cm. "Peel strength" after treatment at 180 ° C for 60 minutes
Was 1150 g / cm.

Example 4 The same method as that of Example 1 was used to produce a laminate, except that the O / C peak area intensity ratio by XPS was controlled to be 0.40, and a nickel vapor deposition film was formed. Instead, a chromium deposited film was used. “5.30PH” of the obtained metal polyimide laminate was 0 pieces, and “peel strength” at room temperature was 1600 g / cm. Also 18
"Peel strength" after treatment at 0 ° C for 60 minutes is 1550 g / c
m.

Example 5 The same method as that of Example 4 was used to produce a laminate, except that the plasma modification was performed so that the O / C peak area intensity ratio of the film surface by XPS was 0.45. The control was carried out. “5.30PH” of the obtained metal polyimide laminate was 0 pieces, and “peel strength” at room temperature was 1000 g / cm. Also at 180 ° C 6
The "peel strength" after the 0-minute treatment was 1000 g / cm.

Example 6 The same method as that of Example 4 was used to produce a laminate, but the plasma modification was carried out by plasma treatment so that the O / C peak area intensity ratio of the film surface by XPS was 0.26. The control was carried out. “5.30PH” of the obtained metal polyimide laminate was 0 pieces, and “peel strength” at room temperature was 800 g / cm. Also at 180 ° C 60
The “peel strength” after the minute treatment was 800 g / cm.
In addition, Kapton film (25 μm manufactured by Toray DuPont)
Thickness) and Ubilex film (75 made by Ube Industries)
(thickness) was carried out in the same manner as in Example 1 to Example 6 except that each was used. "Peel strength" is from 800 g / cm to 1500 g
/ Cm, and there was almost no difference depending on the polyimide film used.

* Comparative Example 1 A laminated body was manufactured in the same manner as in Example 1, except that the O / C peak area intensity ratio by XPS of the film surface by the plasma treatment was 0.48. The number of “5.30 PH” of the obtained metal polyimide laminate was 10, and the “peel strength” at room temperature was 400 g / cm. The “peel strength” after treatment at 180 ° C. for 60 minutes is 300 g /
cm.

* Comparative Example 2 A laminated body was manufactured in the same manner as in Example 1, except that the O / C peak area intensity ratio of the film surface by XPS by plasma treatment was 0.25. "5.30PH" of the obtained metal polyimide laminate was 25 pieces, and "peel strength" at room temperature was 350 g / cm. The “peel strength” after treatment at 180 ° C. for 60 minutes is 200 g /
cm.

* Comparative Example 3 Polyimide film manufactured by Kanegafuchi Chemical Co., Ltd. (thickness: 50)
μm) One side (bright side) of NPI-50 is plasma-treated (this processing is performed by controlling the O / C peak area intensity ratio by XPS of the surface to be 0.30).
Was. After modification by plasma treatment, a 30-nm-thick vapor-deposited copper film was formed, and further electroplated with copper to 35 μm. Using a mask having a predetermined shape on the copper surface of the substrate, an etching process was performed according to the pattern obtained after applying and drying a resist, and processed so as to obtain a pattern having a line width of 90 μm. The metal polyimide laminate obtained in the same manner as in Example 1 was evaluated. "5.30PH" is 3
And the "peel strength" at room temperature is 40 or more.
It was 0 g / cm. The “peel strength” after the treatment at 180 ° C. for 60 minutes was 250 g / cm.

[0026]

As described above, according to the present invention, no matter what kind of polyimide resin film or plasma reformer is used, there is little adhesion strength and almost no pinholes to obtain high reliability. A metal polyimide laminate can be obtained. By using the metal polyimide laminate obtained by the present invention, highly reliable PWB, FP
A substrate for mounting C and TAB can be manufactured.

Claims (3)

[Claims] 1. A metal polyimide film laminate comprising one or more metal thin films selected from chromium, nickel and titanium and a copper thin film provided on one or both surfaces of a polyimide resin film surface. No more than 50 pinholes (hereinafter abbreviated as 5.30PH) having a diameter of 5 μm (micron meter) to 30 μm (micron meter) per square meter (m ² ), and the peel strength between the polyimide resin film and the thin film Is 700 g / cm or more. 2. The metal polyimide film laminate according to claim 1, wherein the metal thin film is formed by dry plating and has a thickness of 5 to 200 nm. 3. The metal polyimide film laminate according to claim 1, wherein the copper thin film has a copper thin film having a thickness of 20 to 500 nm formed by dry plating and a copper thin film formed by electrolytic plating.