JP2003318532A - Flexible printed wiring board - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a double-layer flexible printed wiring board having a metal conductor layer that is durable against high temperatures and high humidity for a long period of time, and can maintain high adhesive strength even when heat or stresses are applied to the layer. <P>SOLUTION: This flexible printed wiring board is constituted by providing a vapor-deposited metal layer on one surface or both surfaces of a plastic film and laminating a conductive metallic layer having a thickness of 0.5-35 μm upon the vapor-deposited metal layer by electroplating and uniting the layers into one body. The vapor-deposited metal layer is composed of a layer containing Ni and Cr as the main component and another layer containing Cu as the main component. The composition of the Ni and Cr-containing layer near the interface (interface A) with the plastic film is made different from that of the layer near the interface (interface B) with the Cu-containing layer. In addition, the Cr content of the layer near the interface A is made lower than that of the layer near the interface B. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a flexible printed wiring board using a metal vapor deposition layer / conductive metal layer laminated film.

[0002]

2. Description of the Related Art Conventionally, there has been known a flexible printed wiring board having a three-layer structure in which a copper foil as a conductor layer is attached to a plastic film via an adhesive layer. This three-layer structure type flexible printed wiring board has a problem that the dimensional accuracy after processing is reduced because the heat resistance of the adhesive used is lower than that of the plastic film, and the thickness of the copper foil used is usually Since it is 10 μm or more, there is a drawback that patterning for high-density wiring with a narrow pitch is difficult.

On the other hand, a metal layer as a conductor layer is formed on a plastic film by a wet plating method or a dry plating method (for example, a vacuum deposition method, a sputtering method, an ion plating method) without using an adhesive. A two-layer structure type flexible printed wiring board is also known. In this two-layer structure type flexible printed wiring board, since the conductor layer can be made thinner than 10 μm, high-density wiring is possible, but a severe heat load test (for example, temperature 85 ° C., humidity 85%, However, there is a drawback in that the adhesion between the plastic film and the conductor layer decreases when the electroless plating treatment with tin, nickel, solder or gold is performed for 1000 hours). Further, when mounting an IC on a two-layer type board with wiring, tin, solder, gold, or a eutectic of these materials is used between the conductor layer and the plastic film, especially Ni and Cr.
However, there is a drawback that it may sneak between the layer mainly composed of copper and the copper layer. Although the cause of the decrease in the adhesiveness at the interface of the printed wiring board having a two-layer structure after the heat load or the electroless plating treatment is not clear, the oxidation of the copper foil as the conductor layer and the electroless plating to be performed later are not clear. Chemical reaction or IC generated at the interface due to the reducing treatment liquid used in the process
It is considered that the heat and stress applied to the substrate during mounting may be the cause.

[0004]

Therefore, according to the present invention, the plastic film, the conductor layer on the plastic film, and the interface between them can sufficiently withstand the action and heat load of the chemicals used in the electroless plating process. The adhesiveness of the interface between the conductor layer and the substrate after electroless plating is excellent as well as the adhesion durability after heat loading, and even if heat or stress is applied during IC mounting, the interface remains Tin,
We provide a flexible printed wiring board with excellent adhesion and durability that does not allow solder, gold or eutectic of these to penetrate between the conductor layer and the plastic film and has insulation reliability under high temperature and high humidity. The purpose is to do.

[0005]

In order to solve the above-mentioned problems, the flexible wiring substrate according to the present invention is provided with a metal deposition layer on one or both sides of a plastic film, and an electroplating method is applied on the metal deposition layer. In a flexible printed wiring board formed by laminating a conductive metal layer, the metal vapor deposition layer is composed of a layer containing Ni and Cr as main components and a layer containing copper as main components, and contains Ni and Cr as main components. The composition near the interface (interface A) on the side of the layer contacting the plastic film is different from the composition near the interface (interface B) on the side of the layer containing Ni and Cr as the main components and in contact with the layer containing copper as the main component, Also, the Cr content near interface A and the Cr content near interface B
The flexible printed wiring board is characterized in that the Cr content near the interface A is lower.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION The flexible printed wiring board according to the present invention will be described in detail below.

The structure of a preferred example of the flexible printed wiring board of the present invention is shown in FIG. In FIG. 1, a metal vapor deposition layer 2 containing Ni and Cr as main components is laminated on one surface of a plastic film 1, and a metal vapor deposition layer 3 mainly containing copper is further laminated thereon. Then, the conductive metal layer 4 is further laminated thereon.

Examples of the plastic film as the substrate used in the present invention include polyethylene terephthalate, polyethylene-2,6-naphthalate, polyethylene-α, β-bis (2-chlorophenoxyethane-4,
4'-dicarboxylate), polyester, polyphenylene sulfide, polyether sulfone, polyether ether ketone, aromatic polyamide, polyarylate, polyimide, polyamideimide, polyetherimide, polyparazic acid, polyoxadiazole and halogens thereof. Examples of the film include a group or a methyl group-substituted product. It may also contain these copolymers or other organic polymers. Known additives such as lubricants and plasticizers may be added to these plastics.

In the present invention, an unstretched film obtained by melt-extruding a polymer containing 85 mol% or more of the repeating unit represented by the following formula in the above plastic is stretched and oriented biaxially to improve mechanical properties. Films are particularly preferably used.

[0010]

[Chemical 1] (Wherein, X is shown H, CH _3, F, and CI group). Also,
A film made of a polymer containing 50 mol% or more of the repeating unit represented by the following formula and formed by a wet or dry wet method, or a film obtained by biaxially stretching and / or heat treating the film is also preferably used.

[0011]

[Chemical 2] (Here, X is H, CH ₃ , F, CI group, m and n are 0 to 3
Indicates an integer).

A plastic film made of a polymer containing a repeating unit as described above is particularly excellent in heat resistance and humidity resistance and has a small dimensional change in a wet etching process.

The thickness of the plastic film as the base material is preferably about 6 to 125 μm, which is often used.
A thickness of 12-50 μm is suitable. If the plastic film is too thin, problems such as insufficient strength and difficulty in metal deposition or wiring processing and the need for a reinforcing film tend to occur. If it is too thick, bendability is impaired, which is not preferable.

In the present invention, prior to forming a thick conductive metal layer by electroplating, a metal vapor deposition layer is formed on one or both sides of a plastic film by vacuum vapor deposition or sputtering. The metal deposition layer is composed of Ni and Cr.
And a layer containing copper as a main component. This makes it possible to form a layer having low resistance and high flexibility.

In the present invention, the layer containing Ni and Cr as the main components is the interface (interface A) on the side in contact with the plastic film.
The composition is different in the vicinity and in the vicinity of the interface (interface B) on the side in contact with the layer containing copper as the main component, and the Cr content near interface A and the Cr content near interface B include the Cr content near interface A. It is necessary that the rate is lower. As a result, the adhesion between the plastic film and the conductor layer is reduced, and tin, solder, gold, or a eutectic of these when the IC is mounted on a two-layer type board on which wiring is provided may cause the conductor layer and the plastic film to separate. It is possible to solve the above-mentioned drawback that the layer may sneak between the copper layer and the layer containing Ni and Cr as the main components.

The Cr content near the interface A is preferably 0 to 10%. If the Cr content is less than this range, the above-mentioned drawbacks cannot be solved and it becomes difficult to achieve the object of the present invention. If the Cr content is higher than this range, Cr may remain between the wirings after etching Cu to form the wirings, and insulation between the wirings may not be secured. Further, even if the insulation between the wirings can be maintained immediately after etching, the insulation may be broken when a voltage is continuously applied under high temperature and high humidity.

The Cr content near the interface B is preferably 15 to 25%. Although Cr may not be contained at all, if it is more than this range, a phenomenon in which tin, solder, gold, or a eutectic of these, or the like easily sneak into the interface B, and it becomes difficult to achieve the object of the present invention.

The thickness of the metal vapor deposition layer containing Ni and Cr as main components is preferably 11 nm or more and 25 nm or less. If the film thickness is less than this range, the above-mentioned drawbacks cannot be solved and it becomes difficult to achieve the object of the present invention. Also,
If the film thickness is larger than this range, Cr may remain between the wirings after etching Cu to form the wirings.
Insulation between wires may not be secured.

As described above, the composition of the layer containing Ni and Cr as the main components is different near the interface A and the interface B. As a method for achieving this, metal vapor deposition containing Ni and Cr as the main components is used. The layer is composed of at least two layers, and among these layers, the Cr content of the layer in contact with the plastic film is different from the Cr content of the layer in contact with the layer containing copper as the main component, and the Cr content of the layer in contact with the plastic film is different. This can be achieved by providing at least two layers containing Ni and Cr as main components so that the content is higher than the Cr content of the layer in contact with the layer containing copper as the main component.

Further, a layer having a composition different from the composition near the interface A or the interface B may be provided in the middle to divide the layer into three or more layers, or the composition may be continuously changed assuming that the division is further advanced. You may make it laminate | stack. Because it is easy to manufacture,
A two-layer structure is preferred. In this case, the Cr content is 0 to 1
2 of 0% layer and 15-25% Cr content
More preferably, it is a layer. When the number of layers is three, the Cr content in the middle layer is preferably between the Cr contents in the front and rear layers because the adhesion between the layers is high, and especially the Cr content is 0-10. %, A layer having a Cr content of 5 to 15%, and a layer having a Cr content of 15 to 25% are more preferably a total of three layers.

When considering the entire metal vapor deposition layer containing Ni and Cr as main components, the film thickness is X (nm), and Ni and Cr are
XY / 100 is 0.5 or more, where Y (%) is the average content rate of Cr atoms in the metal vapor deposition layer containing as a main component.
It is preferably 5 or less. If XY / 100 is less than this range, the above-mentioned drawbacks cannot be solved and it becomes difficult to achieve the object of the present invention. If XY / 100 is more than this range, Cr may remain between the wirings after etching Cu to form the wirings, and insulation between the wirings may not be secured.

N of a metal vapor deposition layer containing Ni and Cr as main components
The i and Cr contents can be determined by examining constituent elements by Auger electron spectroscopy. In this case, the plastic film of the flexible printed wiring board of the present invention is removed by some method to expose the interface A, and Auger electron spectroscopy is applied while etching with an ion beam to remove the constituent elements near the interface A. Find out. Further, by continuing the etching and examining the constituent elements beyond the interface B to the copper layer, the constituent elements near the interface B are investigated.
The content ratio of Cr can be estimated by examining the peak intensity ratio of Ni and Cr obtained as a result. Ni near interface A
/ Cr peak intensity ratio is 8 or more, Ni / near interface B
It is preferable that the peak intensity ratio of Cr is 2 to 3. Also,
It is preferable that the ratio of the peak intensity ratio near the interface B to the peak intensity ratio near the interface A is 2.5 or more.

Next to the metal vapor deposition layer containing Ni and Cr as the main components, a metal vapor deposition layer containing copper as the main component is provided. The thickness of the metal vapor deposition layer is preferably 10 to 300 nm, more preferably 30 to 120 nm, further preferably 40 to 1 nm.
00 nm. When the film thickness is thinner than 10 nm, the copper film is easily eluted in the metal plating step, and when it is thicker than 300 nm, the film is easily peeled off after the metal plating step and the production efficiency is not good, which is not preferable.

A thicker conductive metal layer (metal plating layer) is formed on the metal thin film by electrolytic or electroless plating.
To form. The electrolytic metal plating step includes degreasing and acid activation treatments for improving adhesion, metal strike, and metal plating. When entering the electroplating process immediately after depositing the metal thin film, degreasing and acid activation treatment,
The metal strike may be omitted. The current density for feeding the thin metal layer is preferably 0.2 to 10 A / dm ² , and 0.5 to
5 A / dm ² is more preferable. Also, electroless plating can be applied instead of electrolytic plating.

Conductive metal layer (metal plating layer) to be formed
The thickness of is preferably 0.5 to 35 μm,
1.0 to 20 μm is more preferable. Thickness is 0.5 μm
If it is less than the above, the reliability of the metal plating layer is not sufficient. Further, if the thickness exceeds 35 μm, it takes time to form the film, which is not economically efficient, and the etching of the end portion of the circuit pattern is likely to proceed during the etching process, and there is a risk of disconnection due to bending, which is not preferable in terms of quality. . Although it depends on the current density of the target circuit, the thickness is more preferably about 1.0 to 20 μm in terms of workability and quality.

The plating conditions vary depending on the composition of the plating bath, the current density, the bath temperature, the stirring conditions, etc., but are not particularly limited. The plating bath includes a copper sulfate bath, copper pyrophosphate bath, copper cyanide bath, nickel sulfamate bath, tin-nickel alloy plating bath, copper-tin-zinc alloy plating bath, tin-nickel-copper alloy plating bath, etc. Preferred, but not limited to. After etching, noble metal plating such as gold cyanide plating, silver cyanide plating, rhodium plating and palladium plating may be additionally formed on the terminal portion.

Next, a pattern is formed on the flexible printed wiring board of the present invention by etching. Specifically, unnecessary portions of metal are dissolved and removed by a chemical reaction to form a predetermined electric circuit pattern. . As the etching liquid, an aqueous solution of cupric chloride, ferric chloride, persulfates, hydrogen peroxide / sulfuric acid, alkali enchant, etc. can be used. In addition, a necessary portion of the metal to be left as a pattern is covered with an organic compound resist by a photographic method or a screen printing method, or a dissimilar metal resist is plated and protected to prevent dissolution of the metal. A feature of the present invention is that a finer pattern can be formed, and moreover, a product that can withstand repeated bending of products and various environmental tests can be formed.

The flexible printed wiring board of the present invention is a computer, a terminal device, a telephone, a communication device, a measurement control device, a camera, a clock, an automobile, an office equipment, a home electric appliance,
It can be used in all fields of electronics such as aircraft instruments and medical equipment. It can also be applied to connectors and flat electrodes.

[0029]

EXAMPLES The flexible printed wiring board of the present invention will be described in detail below with reference to examples. The characteristic values in the examples were measured according to the following measuring methods. (a) Peel strength: evaluated according to JIS C6481 (180 degree peel). (b) Adhesion under normal condition: 100 ° C. after pattern formation in the above evaluation
It was dried for 15 minutes and measured at room temperature and normal humidity. (c) Heat-resistant peeling adhesion: The above-mentioned evaluation was carried out at 150 ° C. for 10 days after pattern formation, taken out, and then measured at room temperature and normal humidity. (d) High-temperature and high-humidity peeling adhesion: The above-mentioned evaluation was carried out at 121 ° C. and 100% RH for 4 days after pattern formation, taken out, and then measured at room temperature and normal humidity.

Example 1 Plasma treatment was carried out on one side of a 38 μm thick polyimide film “Kapton” (registered trademark of DuPont, USA). Plasma treatment is 5m
In a vacuum chamber having a vacuum degree of Pa or less, nitrogen gas was introduced up to 1.6 Pa, and the RF power was 1.1 kW. Then, a target of chromium 5% nickel 95% is used to form a nickel chromium vapor-deposited layer having a thickness of 10 nm on the plasma-treated surface of the polyimide film by sputtering, and a target of chromium 20% nickel 80% is used. Sputter deposition on the nickel chrome deposition layer,
A nickel-chromium vapor-deposited layer having a thickness of 4.5 nm was formed and combined to form a metal vapor-deposited layer containing Ni and Cr as main components. Further, copper having a purity of 99.99% was sputter-deposited on the metal vapor deposition layer containing Ni and Cr as main components to form a copper vapor deposition layer having a thickness of 80 nm. Then, electrolytic copper plating with a thickness of 9 μm was performed to form a conductive metal layer on the metal vapor deposition layer.

Table 1 shows the measurement results of the peeling adhesion of the obtained flexible printed wiring board. Good results were shown in normal state adhesive strength, heat resistant peeling adhesive strength, and high temperature and high humidity peeling adhesive strength. Further, the metal layer of this flexible printed wiring board was etched to form a wiring pattern having a width of 1 mm. When this wiring pattern was bent, heated at 420 ° C., and soldered, no submerged solder was observed between the polyimide film and the metal layer.

The metal layer of this flexible printed wiring board is etched to have a width of 30 μm and a space 40.
A wiring pattern of μm was prepared. Electroless Sn plating is applied to this wiring pattern to obtain a Sn of 0.2 μm in thickness.
A plating layer was formed. An IC having this wiring pattern and gold bumps is used as a bonding device ILT-1 manufactured by Shinkawa Co., Ltd.
When IC was mounted using No. 10, Sn and Au were not seen between the copper layer and the polyimide film, and the chip was mounted normally. The mounting conditions at this time are: tool temperature 370 ° C., stage temperature 445 ° C., mounting time 1 second, forming amount 50 μ.
It was m.

The metal layer of this flexible printed wiring board is etched to have a width of 30 μm and a space 40.
A comb-shaped wiring pattern for insulation test of μm was prepared. When a voltage of 60V is applied between the terminals of this wiring pattern, 1
A resistance value of 0 ^ 12Ω (Amioka Note: exponentiation) is shown.
This wiring pattern 6 under high temperature and high humidity of 85 ℃ 85% RH
Although the voltage of 0 V was continuously applied, the resistance value did not fluctuate even after 500 hours, and a good result was shown.

The polyimide of this flexible printed wiring board was dissolved and removed in a heated ethylenediamine / hydrazine mixed solution to expose the polyimide side interface of the metal vapor deposition layer containing Ni and Cr as the main components, and Auger electron spectroscopy The constituent element ratio was measured by. The measuring device is PE
It was performed with PHI-670 manufactured by RKIN ELMER. The measurement conditions were an acceleration voltage of 10 kV, a sample current of 20 nA, a beam diameter of 80 nmφ, and a sample tilt angle of 30 degrees. The ion etching conditions for performing the analysis in the depth direction were as follows: ion species Ar +, accelerating voltage 2 kV, sample inclination angle 30 °, and etching rate 6 nm / min (SiO ₂ conversion value). As a result, Ni / C at the time when the Cr peak appeared
The ratio P of r is 9.9, and Ni after the etching further progresses
The ratio Q of / Cr was 2.5 and P / Q = 3.96.

(Example 2) On the polyimide film treated by plasma in the same manner as in Example 1, chromium 5% nickel 9
Sputter deposition using a 5% target, thickness 5 nm
Nickel chrome vapor deposition layer of 10% chromium
Using a target of nickel 90%, sputter vapor deposition is performed on the nickel chromium vapor deposition layer to form a nickel chromium vapor deposition layer having a thickness of 5 nm, and further chromium 20% nickel 80
% Target was used to perform sputter deposition on the nickel chrome vapor deposition layer to form a nickel chrome vapor deposition layer having a thickness of 4.5 nm, and a metal vapor deposition layer containing Ni and Cr as main components was combined. Furthermore, copper with a purity of 99.99% is added to Ni and Cr.
The thickness is 8 by sputtering deposition on the metal deposition layer containing
A 0 nm copper vapor deposition layer was formed as a metal vapor deposition layer. After that, electrolytic copper plating with a thickness of 9 μm was performed to form a conductive metal layer on the metal vapor deposition layer, thus producing a flexible printed wiring board. When the peeling adhesion was measured in the same manner as in Example 1, the results shown in Table 1 were obtained. Compared with Example 1, the result was almost the same.

Further, the metal layer of the flexible printed wiring board was etched to form a wiring pattern having a width of 1 mm. Bend +42 to this wiring pattern
After heating at 0 ° C and soldering, no solder submerged between the polyimide film and the metal layer was observed,
It was confirmed that the results were the same as in Example 1.

When IC mounting was performed in the same manner as in Example 1, no submergence of Au and Sn between the copper layer of the wiring pattern and the polyimide film was confirmed.

An insulation test was conducted in the same manner as in Example 1. As a result, a voltage of 60 V was applied after etching and at a high temperature and high humidity of 85 ° C. and 85% RH for 500 hours. A table was shown and good results were obtained.

When Auger electron spectroscopy was performed on this flexible printed wiring board in the same manner as in Example 1, the Ni / Cr ratios were 10, 5.9 and 2.6 in that order, and P / Q = 10. /2.6=3.85. (Comparative Example 1) A polyimide film vapor-treated as in Example 1 was sputter-deposited using a target of chromium 20% and nickel 80% to form a nickel-chromium vapor-deposited layer having a thickness of 4.5 nm. 99.99% copper was sputter-deposited on the nickel-chrome vapor-deposited layer to a thickness of 8
A 0 nm copper vapor deposition layer was formed as a metal vapor deposition layer. After that, electrolytic copper plating with a thickness of 9 μm was performed to form a conductive metal layer on the metal vapor deposition layer, thus producing a flexible printed wiring board. When the peeling adhesion was measured in the same manner as in Example 1, the results shown in Table 1 were obtained. Compared with Example 1, the heat-resistant peeling adhesion and the high-temperature and high-humidity peeling adhesion strength were slightly inferior. Further, the metal layer of this flexible printed wiring board was etched to form a wiring pattern having a width of 1 mm. When this wiring pattern was bent, heated at 420 ° C., and soldered, it was confirmed that solder submerged between the polyimide film and the metal layer, which was inferior to that of Example 1.

When IC mounting was carried out in the same manner as in Example 1, it was confirmed that Au and Sn sunk between the copper layer of the wiring pattern and the polyimide film.
When Auger electron spectroscopy was performed on this flexible printed wiring board in the same manner as in Example 1, it was found that Ni
The ratio of / Cr was 2.7.

[0041]

[Table 1] (Comparative Example 2) A polyimide film subjected to plasma treatment in the same manner as in Example 1 was sputter-deposited using a target of chromium 20% and nickel 80% to form a nickel-chromium vapor-deposited layer having a thickness of 14.5 nm, and further purified. 99.99%
Copper was vapor-deposited on the nickel-chrome vapor-deposited layer to form a copper vapor-deposited layer having a thickness of 80 nm, which was used as a metal vapor-deposited layer. After that, electrolytic copper plating with a thickness of 9 μm was performed to form a conductive metal layer on the metal vapor deposition layer, thus producing a flexible printed wiring board. When the metal layer of this flexible printed wiring board was etched to form a wiring pattern with a width of 1 mm, a nickel-chrome vapor deposition layer remained between the wiring,
The insulation between the wiring patterns could not be removed, and it was unsuitable as a flexible printed wiring board.

(Comparative Example 3) A thickness of 1 was obtained by sputtering deposition on a polyimide film treated by plasma in the same manner as in Example 1 using a target of 10% chromium and 90% nickel.
A nickel chromium vapor deposition layer having a thickness of 4.5 nm was formed, and copper having a purity of 99.99% was sputter vapor deposited on the nickel chromium vapor deposition layer to form a copper vapor deposition layer having a thickness of 80 nm, which was used as a metal vapor deposition layer. After that, electrolytic copper plating with a thickness of 9 μm is performed,
A conductive metal layer was formed on the metal vapor deposition layer to produce a flexible printed wiring board. When the peeling adhesion was measured in the same manner as in Example 1, the results shown in Table 1 were obtained.
Compared with Example 1, the results were slightly superior in the normal state peeling adhesion and the high temperature and high humidity peeling adhesion.

Further, the metal layer of this flexible printed wiring board was etched to form a wiring pattern having a width of 1 mm. Bend +42 to this wiring pattern
When heating was performed at 0 ° C. and soldering was performed, no penetration of solder between the polyimide film and the metal layer was observed.

The metal layer of this flexible printed wiring board was etched to give a width of 30 μm and a space 40.
A wiring pattern of μm was prepared. Electroless Sn plating is applied to this wiring pattern to obtain a Sn of 0.2 μm in thickness.
A plating layer was formed. An IC having this wiring pattern and gold bumps is used as a bonding device ILT-1 manufactured by Shinkawa Co., Ltd.
When IC was mounted using No. 10, Sn and Au were not seen between the copper layer and the polyimide film, and the chip was mounted normally. The mounting conditions at this time are: tool temperature 370 ° C., stage temperature 445 ° C., mounting time 1 second, forming amount 50 μ.
It was m.

The metal layer of this flexible printed wiring board was etched to give a width of 30 μm and a space 40.
A comb-shaped wiring pattern for insulation test of μm was prepared. When a voltage of 60V is applied between the terminals of this wiring pattern, 1
A resistance value of 0 ^ 12Ω was shown. This wiring pattern is 85
Although a voltage of 60 V was continuously applied under a high temperature and high humidity condition of 85 ° C. and 85% RH, a short circuit occurred between wirings after 300 hours, which was inferior to that of Example 1.

When Auger electron spectroscopy was performed on this flexible printed wiring board in the same manner as in Example 1, the Ni / Cr ratio was 6.0.

[0047]

According to the present invention, a metal layer having a thickness of about 0.5 to 35 μm can be formed on a plastic film, and even if steps such as pattern formation, etching, wiring and IC mounting are performed. Even after undergoing a more rigorous environmental test,
FPC board with excellent adhesion without peeling or peeling, CO
A flexible printed wiring board such as an F board can be obtained. Moreover, conventionally, for example, a copper foil having a thickness of less than 12 μm has not been produced due to the limit of the thickness of the copper foil.
By being able to form a thinner copper layer of 5-11 μm,
The pattern accuracy is improved, and higher density and higher accuracy wiring is possible. In addition, a flexible printed wiring board that is economical and has high quality can be obtained with few creases and pinholes generated during copper foil lamination.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a preferred example of a flexible printed wiring board of the present invention.

[Explanation of symbols]

1: Plastic film 2: Metal vapor deposition layer (layer containing Ni and Cr as main components) 3: Metal vapor deposition layer (layer whose main component is copper) 4: conductive metal layer 5: Interface A 6: Interface B

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) H05K 1/09 H05K 1/09 C (72) Inventor Toru Miyake Fukushima Prefecture Iwase-gun Kagamiishi-cho Narita character Suwa-cho 334 -3 Toyo Metallizing Co., Ltd. Fukushima Plant (72) Inventor Akinori Nakano Suwa Town, Kagamiishi Town, Iwase-gun, Fukushima Prefecture Suwa Town 334 -3 Toyo Metallizing Co., Ltd. Fukushima Plant F-term (reference) 4E351 AA01 AA04 BB01 BB33 BB38 CC03 CC06 DD04 DD17 DD19 GG02 4F100 AB01A AB01B AB01C AB01E AB13A AB13B AB13E AB16A AB16B AB16E AB17A AB17B AB17E AK01D AK41D AK47D AK49D AK54D AK55D AK57D BA04 BA05 BA07 BA10A BA10D BA10E BA25A BA25B BA25E BA27E BA44A BA44B EH66A EH66B EH66E EH71C EH71E EJ51 GB43 JG01C JG01E JJ03 JL04 JL11 YY00A YY00B YY00E 4K029 AA11 AA25 BA21 BA25 BB02 BC03 BD00 CA05 EA01 5E34 3 AA12 AA18 AA33 BB17 BB24 BB38 BB44 DD76 EE36 GG02

Claims (11)

[Claims] 1. A flexible printed wiring board comprising a metal vapor deposition layer provided on one or both sides of a plastic film, and a conductive metal layer laminated on the metal vapor deposition layer by an electroplating method. It is composed of a layer containing Ni and Cr as main components and a layer containing copper as main components, and the composition near the interface (interface A) on the side in contact with the plastic film of the layer containing Ni and Cr as the main component and Ni and Cr The composition of the layer containing the main component near the interface (interface B) on the side in contact with the layer containing copper as a main component is different, and the Cr content near interface A and the Cr content near interface B are similar to those near interface A. A flexible printed wiring board having a lower Cr content. 2. A metal vapor-deposited layer containing Ni and Cr as main components is composed of at least two layers, and among these layers, the Cr content of the layer in contact with the plastic film and the layer in contact with the layer containing copper as the main component. 2. The flexible printed wiring according to claim 1, wherein the Cr content is different and the Cr content of the layer in contact with the plastic film is lower than the Cr content of the layer in contact with the layer containing copper as a main component. Substrate. 3. A plastic film, a polyester film, a polyphenylene sulfide film, a polyimide film, a polyparazinic acid film, a polyether sulfone film, a polyether ether ketone film, an aromatic polyamide film, a polyoxazole film, a liquid crystal polymer film, and The flexible printed wiring board according to claim 1 or 2, which is selected from the films consisting of these halogen group- or methyl group-substituted products. 4. The Cr content near interface B is 15 to 25%.
The substrate for flexible printed wiring according to any one of claims 1 to 3, wherein 5. The flexible printed wiring board according to claim 1, wherein the Cr content in the vicinity of the interface A is 0 to 10%. 6. The substrate for flexible printed wiring according to claim 1, wherein the film thickness of the metal vapor deposition layer containing Ni and Cr as main components is 11 nm or more and 20 nm or less. 7. The metal vapor deposition layer containing Ni and Cr as main components has a Cr content of 0 to 10 from the plastic film side.
%, And a layer with a Cr content of 15 to 25%. 7. The flexible printed wiring board according to claim 1, wherein the layer has a Cr content of 15 to 25%. 8. The metal vapor deposition layer containing Ni and Cr as main components has a Cr content of 0 to 10 from the plastic film side.
%, A layer having a Cr content of 5 to 15%, and a layer having a Cr content of 15 to 25%, that is, a total of 3 layers. 7. Substrate for flexible printed wiring. 9. When the metal vapor deposition layer containing Ni and Cr as the main components is examined for the constituent element ratio by Auger electron spectroscopy depth direction analysis, the Ni / Cr in the portion in contact with the plastic film is measured.
Is 8 or more, and the peak intensity ratio of Ni / Cr in the portion in contact with the layer containing copper as a main component is 2 to 3, 9. Substrate for flexible printed wiring. 10. When the metal vapor deposition layer containing Ni and Cr as the main components is examined for the constituent element ratio by Auger electron spectroscopy depth direction analysis, the Ni / C at the portion in contact with the plastic film is measured.
When the peak intensity ratio of r is P and the peak intensity ratio of Ni / Cr in the portion in contact with the layer containing copper as the main component is Q, P / Q
Is 2.5 or more, The board for flexible printed wirings according to any one of claims 1 to 8. 11. The film thickness of the metal vapor deposition layer containing Ni and Cr as main components is X (nm), and the average Cr content of the metal vapor deposition layer containing Ni and Cr as main components is Y (%). When XY
/ 100 is 0.5 or more and 2.5 or less, The board for flexible printed wirings in any one of Claims 1-10 characterized by the above-mentioned.