JPH05114779A - Manufacture of copper polyimide board - Google Patents

Abstract

PURPOSE:To prevent copper from diffusing when a board is kept high in temperature by a method wherein the surface of a polyimide resin film is subjected to a hydrophilic treatment with a specific hydrazine hydrate water solution, and an intermediate layer of nickel, its alloy, cobalt, or its allay is provided to an interface between copper and the polyimide resin film. CONSTITUTION:The surface of a polyimide resin film is subjected to hydrophilic treatment with a specific hydrazine hydrate water solution which contains 1-15mol/l of hydrazine hydrate and 0.5-5mol/l of metal hydroxide at a temperature of 10-50 deg.C, catalyst is added, an electroless plating film of nickel, cobalt, or either of their alloys is formed as thick as 0.01-0.1mum on the surface of the resin film, where the impurity content of the plating film is 10% or below. The resin film is thermally treated in an inert atmosphere as kept at a maximum temperature of 350-540 deg.C so as to keep a heat load coefficient D obtained by a formula in a range of 0.3-3.5. In a formula D, t0 denotes a treatment starting time and Ti indicates the temperature of a board itself at a certain time.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a flexible printed wiring board (EPC) and automatic tape bonding (TAB).
The present invention relates to a method for manufacturing a copper-polyimide substrate that is a raw material for a printed wiring board (PWB) such as a tape.

[0002]

2. Description of the Related Art In recent years, there has been a demand for higher wiring density and higher functionality in printed wiring boards as electronic equipment becomes smaller and faster. The substrate material is also required to have a low dielectric constant, a high insulation resistance value, and good heat resistance. Polyimide resin has attracted attention as a substrate material satisfying this requirement, and has been frequently used as a material for EPC and TAB tapes. Usually, a copper polyimide obtained by coating the surface of a film-shaped polyimide resin with copper as a metal layer. Substrates are often used.

As a method for forming a copper layer on a polyimide resin film, a laminating method in which a polyimide resin film and a copper foil are bonded with an adhesive has been conventionally used.
Since the presence of adhesive adversely affects the insulation and heat resistance of the substrate, recently copper layers are directly formed on polyimide resin films by sputtering, ion plating, vapor deposition, electroless plating, etc. The way is done.

However, when a copper-polyimide resin substrate obtained by directly forming a copper layer on the surface of a polyimide resin film is left in a high temperature environment for a long time, the adhesion strength at the interface between the copper layer and the polyimide resin film decreases. However, there was a risk of causing problems such as peeling. As a result of various studies on this problem, it was found that the decrease in adhesion strength was due to diffusion of copper to the polyimide side.

As a method for preventing the diffusion of copper, it is conceivable to form a barrier layer made of a metal which hardly diffuses in the middle of forming a copper layer on a polyimide resin. Conventionally, a metal layer such as nickel is formed between the resin and the copper layer when the copper layer is formed on the polyimide resin in order to prevent the deterioration of the adhesion of the copper due to the thermal shock when the board is soldered. (For example, Japanese Patent Laid-Open No. 63-286580), the thickness required for the intermediate metal layer is required to be 0.15 μm or more for this purpose.

[0006]

By the way, when a copper polyimide substrate is used for EPC or TAB tape, it is necessary to form a copper lead on the substrate by a subtractive method, a semi-additive method, a full-additive method or the like. , For example, when the copper lead is formed by the subtractive method, a copper layer is provided on the surface of the polyimide resin film by electroless plating, and if necessary, electrolytic copper plating is further applied thereon, and a resist is applied thereon. After coating and bringing a predetermined mask into close contact with each other, exposure and development are performed, and then etching processing is performed to form a copper lead portion.

When forming the copper lead portion, if a copper polyimide substrate having an intermediate layer of nickel or the like formed on the underlayer by the method as disclosed in JP-A-63-286580 is used, copper and a dissimilar metal layer are formed. Because of the different etching rates, when trying to form the shape of the copper lead portion into a desired shape, the dissimilar metal layer of the intermediate layer remains on the surface of the polyimide resin and causes deterioration of the insulation resistance between the leads. Further, when the intermediate metal layer is completely dissolved and removed, the copper lead does not have a desired shape due to overetching of the copper layer. Further, even when the semi-additive method is used for forming the copper lead, the manufacturing method thereof is slightly different from the subtractive method, but the method of forming the copper lead by etching is basically the same as the above. For the same reason, satisfactory results cannot be obtained.

In order to eliminate the above problems, when a wiring board or the like is prepared by using a copper-polyimide substrate on which an intermediate layer of a different metal such as nickel is formed as an underlayer, nickel or the like is used during the manufacturing process. It is necessary to add a step of selectively etching only the dissimilar metal layer, which is not only complicated but also economically problematic.

The present invention solves the above-mentioned problems in a copper polyimide substrate in which an intermediate layer of a different metal such as nickel is formed as a base metal layer on a polyimide resin film, and the obtained substrate is subjected to high temperature and high humidity. Adhesion strength between copper and polyimide hardly deteriorates even when exposed to a long time, and a special etching process is used to remove the underlying metal layer when manufacturing EPC or TAB tape using this substrate. It is an object of the present invention to provide a method for manufacturing a copper-polyimide substrate in which lead portions can be formed without doing so.

[0010]

Means for Solving the Problems The present invention for solving the above-mentioned problems is to make the surface of a polyimide resin film hydrophilic, impart a catalyst, subject it to electroless plating, and subject it to heat treatment in an inert atmosphere, Thereafter, in producing a copper-polyimide substrate by performing electroless plating following electroless copper plating, or electroless copper plating, hydrophilic treatment of the polyimide resin film surface, hydrazine hydrate 1 ~
It is carried out using an aqueous solution of 15 mol / l and an alkali metal hydroxide of 0.5 to 5 mol / l at a temperature of 10 to 50 ° C. After applying a catalyst, nickel, cobalt or an alloy of these metals is applied to the surface. The electroless plating film of any one of the above is applied in a thickness of 0.01 to 0.1 μm so that the content of impurities in the film is 10 wt% or less. Maximum temperature reached at 350-54
It is characterized in that the heat treatment is performed in an inert atmosphere in a temperature range of 0 ° C. and a heat load coefficient D obtained by the following mathematical formula 1 is in a range of 0.3 to 3.5. It is a thing.

[0011]

[Equation 2] (However, to is a treatment start time, ti is an arbitrary time, and Ti is a temperature of the substrate itself at an arbitrary time.) In the present invention, the alkali metal used in the hydrophilization treatment is sodium, Examples include potassium and lithium. Also,
The type of impurities contained in the electroless plating film of nickel, cobalt or an alloy of these metals is not particularly limited, except for phosphorus and boron which are usually contained in the electroless film of this type.

[0012]

In the present invention, the intermediate layer of nickel or its alloy, or cobalt or its alloy is provided at the interface between the copper and the polyimide resin film because the intermediate layer is inside the polyimide resin of copper when the substrate is heated at a high temperature. This is because it is possible to prevent the diffusion of

The use of a mixed aqueous solution of hydrazine hydrate and alkali metal hydroxide as the hydrophilic treatment liquid for the polyimide resin film is carried out by cleavage of the imide bond by hydrazine hydrate and hydrolysis of the alkali metal hydroxide. This is because the surface of the polyimide resin film is easily hydrophilized, and the catalyst is easily absorbed when the catalyst is applied as a pretreatment for electroless plating.

When the concentration of hydrazine hydrate is lower than 1 mol / l, the effect of cleaving the imide bond is insufficient, and the concentration is 1
If it is higher than 5 mol / l, the adhesion strength between the electroless plating layer and the polyimide resin film will be lowered, so that the concentration is preferably in the range of 1 to 15 mol / l. When the concentration of the alkali metal hydroxide is lower than 0.5 mol / l, the hydrolysis is insufficient, and when it is higher than 5 mol / l, the adhesion strength is lowered. And the range.

The hydrophilization method may be the same as the ordinary etching method, and the required treatment time cannot be generally specified, but 30 seconds to 5 minutes is usually sufficient.

The thickness of the intermediate layer made of nickel, cobalt, or an alloy of these metals is limited to the range of 0.01 to 0.1 .mu.m because the effect of preventing copper from diffusing into the polyimide resin is 0.01 .mu.m or less. This is because the adhesion strength of copper is lowered due to the diffusion of copper when left for a long time at a temperature of 150 ° C. or higher in an atmosphere containing oxygen such as the air. This is because, when the lead portion is formed by the subtractive method or the semi-additive method, the intermediate layer remains in the base etching step and the insulation resistance between the wirings is reduced.

Further, according to the present invention, the impurity content of the intermediate layer made of nickel, cobalt or an alloy thereof is set to 1
The content is suppressed to 0% by weight or less, but this is to prevent the decrease in the solubility of nickel, cobalt, etc. in the etching solution process, and when the impurity content exceeds 10% by weight, the intermediate layer remains, This causes a problem that the insulation resistance between the wirings decreases.

After forming the intermediate layer of nickel, cobalt, or an alloy thereof, heat treatment is performed to make the polyimide resin film hydrophilic by etching treatment hydrophobic so that the adhesion strength under high temperature and high humidity is increased. This is to prevent the decrease. At this time, the maximum attainable temperature of the substrate is set to 350 ° C. or less because the empirical rule for setting the heat load coefficient as described later does not hold, and the decrease of the adhesion strength under high temperature and high humidity is sufficiently prevented. Because you can't.

The heat load coefficient in the present invention is a coefficient of temperature and time, and is obtained by the above-mentioned formula 1. This formula is an empirical formula so that it can be empirically formulated so that it can be applied even when the heat treatment apparatus is different. When this heat load coefficient is less than 0.3, the heat treatment will reduce the adhesion strength under high temperature and high humidity. In any case, it is not preferable because the dynamic strength is remarkably lowered.

The present invention is also effective when a metal other than copper is used as the lead forming metal, and the conditions in that case may be appropriately selected.

[0021]

EXAMPLES Examples of the present invention will be described below. Example 1 30 cm square Kapton 200 manufactured by Toray DuPont
An H-type polyimide resin film containing 5 mol / l hydrazine hydrate and 3 mol / l sodium hydroxide 25
After dipping in a 60 ° C. aqueous solution for 60 seconds to make the surface of the polyimide resin film hydrophilic, masking one side and subjecting it to catalyst activation treatment by a conventional method, and performing electroless plating of nickel under the conditions shown in Table 1. It was

[0022]

[Table 1] (Plating solution composition) NiCl ₂ .6H ₂ O: 0.1 mol / l NaH ₂ PO ₂ .H ₂ O: 0.1 mol / l Sodium citrate: 0.2 mol / l pH: 9 (Plating conditions) Temperature: 60 ° C Time: 30 seconds The thickness of the obtained electroless nickel plating film is 0.05μ.
It was m. The content of phosphorus as an impurity was 7% by weight.

Then, using a hot-air circulation type heating furnace manufactured by Koyo Lindbergh, the temperature was raised to 400 ° C. at a temperature rising rate of 9 ° C./min in a nitrogen gas atmosphere, and then kept at the same temperature for 1.5 hours. It cooled at the temperature-fall rate of 2.5 degreeC / min. The heat load coefficient at this time was 0.7. Then, the substrate is subjected to electroless copper plating under the conditions shown in Table 2,
After obtaining a 0.4 μm plated film, electrolytic copper plating was further performed under the conditions shown in Table 3.

[0024]

[Table 2] (Plating solution composition) CuSO ₄ .5H ₂ O: 10 g / l EDTA.2Na: 30 g / l 37% HCHO: 5 g / l dipyridyl: 20 mg / l PEG # 1000: 0.5 g / l (plating conditions ) Temperature: 65 ° C Stirring: Air stirring time: 10 minutes

[0025]

[Table 3] (Plating solution composition) CuSO ₄ .5H ₂ O: 120 g / l H ₂ SO ₄ : 150 g / l (electrolysis conditions) Temperature: 25 ° C. Cathode current density: 2 A / dm ² Stirring: When stirring air Interval: 90 minutes The thickness of the obtained copper film was 35 μm. On the copper film of the copper polyimide substrate having the nickel intermediate layer thus obtained, 10 μl of an alkyl resin type photoresist is applied.
It was evenly applied to a thickness of m and baked at 70 ° C. for 30 minutes.
After that, masking was performed on the substrate so that the wiring width was 200 μm, the photoresist layer was irradiated with ultraviolet rays of 300 mj / cm, and then the resist was developed. Then, the exposed copper surface was subjected to etching treatment under the conditions shown in Table 3 to dissolve the copper.

[0026]

(Table 4) (Etching liquid composition) 30% H ₂ O: 100 g / l H ₂ SO ₄ : 150 g / l (Treatment conditions) Temperature: 25 ° C. Time: 4 minutes Stirring: Shaking stirring After 4 wt% The resist layer was peeled off at 60 ° C. using an aqueous sodium solution, and the presence or absence of a residual nickel layer between wirings was observed and the insulation resistance value was measured. As a result, no nickel layer remained between the wirings, and the insulation resistance was 1 × 10 ¹⁰ Ω (IPC-TM-650).
2.6.3.2. C-24 / 23/50 method), and good results were obtained. Moreover, when the adhesion strength between the copper and the polyimide resin film was measured, it was 1400 g.
A high value of / cm was obtained. Further, after this substrate was left in the atmosphere at 150 ° C. for 10,000 hours, the adhesion strength was measured again to 1200 g / cm, which was almost no decrease. Further, after leaving it for 1000 hours in a high-temperature and high-humidity atmosphere of 85 ° C. and 85%, measurement was carried out, and it was 1000 g / cm 2, which was a very high value.

This result shows that the copper polyimide substrate obtained by the method of the present invention is a copper polyimide substrate having a nickel intermediate layer having a thickness of 0.05 μm and an impurity content of 7% by weight and a thermal load coefficient of 0.7 at 400 ° C. When heat-treated at the temperature of, the nickel layer does not remain even if etching is performed by applying the conventional etching treatment method without performing a special etching treatment for melting the intermediate layer. Moreover, the wiring board made from the copper polyimide substrate obtained by the present invention shows high adhesion strength even after being left for a long time in a high temperature environment or a high temperature and high humidity environment, and has high reliability as a printed wiring board. It turned out to be a thing. Example 2 30 cm square Kapton 200 manufactured by Toray DuPont
An H-type polyimide resin film containing 5 mol / l hydrazine hydrate and 3 mol / l sodium hydroxide 25
After dipping in a 60 ° C. aqueous solution for 60 seconds to make the surface of the polyimide resin film hydrophilic, masking one side and subjecting it to catalyst activation treatment by a conventional method, and performing electroless plating of cobalt under the conditions shown in Table 5. It was

[0028]

[Table 5] (Plating solution composition) CoSO ₄ .5H ₂ O: 0.05 mol / l NaH ₂ PO ₂ .H ₂ O: 0.2 mol / l Sodium citrate: 0.2 mol / l pH: 10 (Plating conditions) Temperature: 60 ° C Time: 2 minutes Thickness of the obtained electroless cobalt plating film is 0.05μ
It was m. The content of phosphorus as an impurity was 3% by weight.

Then, using a hot air circulation type heating furnace manufactured by Koyo Lindbergh, the mixture was heated to 420 ° C. at a temperature rising rate of 9 ° C./min in a nitrogen gas atmosphere, and then kept at the same temperature for 1.5 hours. It cooled at the temperature-fall rate of 2.5 degreeC / min. The heat load coefficient at this time was 3.1.

Thereafter, a copper-polyimide substrate was prepared in the same procedure as in Example 1, wirings were formed, and the obtained wiring board was observed for the presence or absence of a residual cobalt layer between the wirings and the insulation resistance value was measured. It was As a result, no cobalt layer remained between the wirings, and the insulation resistance was 1 × 10.
¹⁰ Ω (IPC-TM-650 2.6.3.2.C-
24/23/50 method), and good results were obtained. Further, when the adhesion strength between the copper and the polyimide resin film was measured, a high value of 1250 g / cm was obtained. Further, after the substrate was left in the atmosphere at 150 ° C. for 1000 hours, the adhesion strength was measured again and found to be 1050 g / cm, which was almost no decrease. In addition, in a high temperature and high humidity atmosphere of 85 ° C and 85%, 100
After standing for 0 hour, measurement was performed and found to be 950 g / cm
And a very high value was obtained.

This result shows that the copper polyimide substrate obtained by the method of the present invention is a copper polyimide substrate having a cobalt intermediate layer having a thickness of 0.05 μm and an impurity content of 3% by weight and a thermal load coefficient of 3.1 at 420 ° C. When the heat treatment is performed at the above temperature, no special etching treatment for melting the cobalt intermediate layer is performed, and even if etching is performed by applying the conventional etching treatment method, no cobalt layer remains. Further, the wiring board made from the copper polyimide substrate obtained by the present invention shows high adhesion strength even after being left in a high temperature environment or a high temperature and high humidity environment for a long time, and thus has high reliability as a printed wiring board. It was found to have. Example 3 A copper polyimide substrate was prepared and wiring was formed in the same procedure as in Example 2 except that both surfaces of the polyimide resin film were subjected to electroless plating of nickel, and wiring was formed. The presence or absence of the nickel layer was observed and the insulation resistance value was measured. As a result, no nickel layer remained between the wires on both sides, and the insulation resistance was
1 × 10 ¹⁰ Ω and 2 × 10 ¹⁰ Ω (IPC
-TM-650 2.6.3.2. C-24 / 23/5
According to method 0), good results were obtained.

Further, the adhesion strength between the copper and the polyimide resin film was measured and found to be 1300 g / c, respectively.
m and 950 g / cm, which were considerably high values on both sides. Furthermore, when this substrate was left in the atmosphere at 150 ° C. for 1000 hours, the adhesion strength was measured again. The values were 1050 g / cm and 800 g / cm, respectively, and the adhesion strength did not decrease. It was In addition, at a high temperature and high humidity of 85 ° C and 85%, 10
When it was measured after being left for 00 hours, the adhesion strength was 1000 g / cm and 800 g / cm, respectively, which was a value having no problem in practical use.

This result shows that the copper polyimide substrate obtained by the method of the present invention is a copper polyimide substrate having a nickel intermediate layer having a thickness of 0.05 μm and an impurity content of 3% by weight, and a thermal load coefficient of 3.1 at 420 ° C. When the heat treatment is performed at the above temperature, no special etching treatment for melting the nickel intermediate layer is performed, and no cobalt layer remains even if etching is performed by applying the conventional etching treatment method. Further, the wiring board made from the copper polyimide substrate obtained by the present invention shows high adhesion strength even after being left in a high temperature environment or a high temperature and high humidity environment for a long time, and has high reliability as a printed wiring board. Was found to have. Example 4 After electroless plating of nickel, the temperature was raised to 480 ° C. at a temperature rising rate of 40 ° C./min in a nitrogen atmosphere using a far-infrared radiation furnace so that the heat load coefficient was 0.7, and held for 30 seconds. After that, a copper-polyimide substrate was prepared in the same procedure as in Example 1 except that the temperature was lowered at a rate of 160 ° C./min, wiring was formed, and the obtained wiring board was observed for the presence or absence of a residual nickel layer between the wiring and The insulation resistance value was measured. As a result, no nickel layer remained between the wirings, and the insulation resistance was 1 × 10 ¹⁰ Ω (IPC-TM-
650 2.6.3.2. C-24 / 23/50 method), and good results were obtained. Also, when measuring the adhesion strength between the copper and the polyimide resin film,
A very high value of 1400 g / cm was obtained. Further, after the substrate was left in the atmosphere at 150 ° C. for 1000 hours, the adhesion strength was measured again and found to be 1250 g /
The cm and the value were hardly reduced. Also, 85
The adhesion strength was 1100 g / cm when measured after leaving it for 1000 hours in a high temperature and high humidity atmosphere of 85 ° C.
And an extremely good value was obtained.

This result shows that the copper polyimide substrate obtained by the method of the present invention is a copper polyimide substrate having a nickel intermediate layer with a thickness of 0.05 μm and an impurity content of 7% by weight at a thermal load coefficient of 0.7 at 480 ° C. When the heat treatment is performed at the above temperature, there is no residual nickel layer even if the conventional etching method is applied without performing any special etching treatment for melting the nickel intermediate layer. Further, the wiring board made from the copper polyimide substrate obtained by the present invention shows high adhesion strength even after being left in a high temperature environment or a high temperature and high humidity environment for a long time, and thus has high reliability as a printed wiring board. It was found to have. Comparative Example 1 30 cm square Kapton 200 manufactured by Toray DuPont
The H-type polyimide resin film is immersed in an aqueous solution containing 0.5 mol / l hydrazine hydrate and 0.3 mol / l sodium hydroxide at 25 ° C. for 2 minutes to make the surface of the polyimide resin film hydrophilic. After that, one side was masked and a catalyst activation treatment was carried out by a conventional method, and a nickel electroless plating treatment was carried out under the same conditions as in Example 1. As a result, the nickel deposition became non-uniform and the subsequent steps could not be performed.

This result shows that when the hydrazine hydrate and alkali metal hydroxide concentrations are below the range specified in the present invention,
It shows that the formation of the electroless plating film becomes insufficient. Comparative Example 2 30 cm square Kapton 200 manufactured by Toray DuPont
An H-type polyimide resin film containing 5 mol / l hydrazine hydrate and 3 mol / l sodium hydroxide 25
After dipping in a 60 ° C. aqueous solution for 60 seconds to make the surface of the polyimide resin film hydrophilic, masking one side and subjecting it to catalytic activation treatment by a conventional method, and performing electroless plating of nickel under the conditions shown in Table 6. It was

[0036]

Table 6 (Composition of the plating _{solution) NiCl 2 · 6H 2 O:} 0.1 mol _{/ l NaH 2 PO 2 · H} 2 O: 0.1 mol / l sodium citrate: 0.1 mol / l pH: 5 .6 (Plating conditions) Temperature: 60 ° C Time: 1 minute The thickness of the obtained electroless nickel plating film is 0.03μ.
It was m. The content of phosphorus as an impurity is 12% by weight.
Met. After that, a copper-polyimide substrate was prepared in the same procedure as in Example 1, wirings were formed, and the obtained wiring board was observed for the presence or absence of a residual nickel layer between the wirings and the insulation resistance value was measured. As a result, a nickel layer remained between the wirings, and the insulation resistance was 4 × 10 ⁶ Ω (IP
C-TM-650 2.6.3.2. C-24 / 23 /
50 method), and the insulation resistance value was significantly reduced.

This result shows that the thickness of the electroless nickel plating film formed on one surface of the polyimide resin film was 0.1.
Even if the thickness is less than or equal to μm, if the impurity content is 10% by weight or more, the nickel layer remains in the copper polyimide substrate in the etching step, and the insulation resistance value decreases, so that the reliability of the wiring board material is low. It turns out that it will drop significantly. Comparative Example 3 30 cm square Kapton 200 manufactured by Toray DuPont
H type polyimide resin film was immersed in an aqueous solution containing 5 mol / l hydrazine hydrate and 3 mol / l sodium hydroxide at 25 ° C. for 30 seconds to make the polyimide resin film surface hydrophilic, Was subjected to a catalyst activation treatment by a conventional method, and nickel electroless plating treatment was performed under the conditions shown in Table 7.

[0038]

TABLE 7 (Composition of the plating _{solution) NiCl 2 · 6H 2 O:} 0.1 mol _{/ l NaH 2 PO 2 · H} 2 O: 0.1 mol / l pyrophosphoric sodium phosphate: 0.2 mol / l pH: 10 (Plating conditions) Temperature: 60 ° C Time: 5 minutes Thickness of the obtained electroless nickel plating film is 0.15μ.
It was m. The content of phosphorus as an impurity was 3.4% by weight. After that, a copper-polyimide substrate was prepared in the same procedure as in Example 1, wirings were formed, and the obtained wiring board was observed for the presence or absence of a residual nickel layer between the wirings and the insulation resistance value was measured. As a result, a nickel layer remained between the wirings, and the insulation resistance was 4 × 10 ⁶ Ω (I
PC-TM-650 2.6.3.2. C-24 / 23
/ 50 method), and the insulation resistance value was significantly reduced.

As a result, the thickness of the electroless nickel plating film formed on the polyimide resin film was 0.1 μm.
If the content is larger, the nickel layer remains in the copper polyimide substrate during the etching process and the insulation resistance value decreases, even if the impurity content is 3.4% by weight or 10% by weight or less. It can be seen that the sex is significantly reduced. Example 4 30 cm square Kapton 200 manufactured by Toray DuPont
An H-type polyimide resin film containing 5 mol / l hydrazine hydrate and 3 mol / l sodium hydroxide 25
After dipping in a 60 ° C. aqueous solution for 60 seconds to make the surface of the polyimide resin film hydrophilic, masking one side and subjecting it to catalyst activation treatment by a conventional method, and performing electroless plating of nickel under the conditions shown in Table 8. It was

[0040]

[Table 8] (Plating solution composition) NiCl ₂ .6H ₂ O: 0.1 mol / l NaH ₂ PO ₂ .H ₂ O: 0.1 mol / l Sodium pyrophosphate: 0.2 mol / l pH: 10 (Plating conditions) Temperature: 60 ° C. Time: 10 seconds The thickness of the obtained electroless nickel plating film is 0.005.
was μm. The content of phosphorus as an impurity was 3.4% by weight. After that, a copper-polyimide substrate was prepared in the same procedure as in Example 1, wirings were formed, and the obtained wiring board was observed for the presence or absence of a residual nickel layer between the wirings and the insulation resistance value was measured. As a result, no nickel layer remained between the wirings, and the insulation resistance was 4 × 10 ^10.
Ω (IPC-TM-650 2.6.3.2.C-24
/ 23/50 method), and good results were also obtained for the insulation resistance value. Further, when the adhesion strength between the copper of this substrate and the polyimide resin film was measured, it was 125
A good result of 0 g / cm was also obtained. But,
When this substrate is left in the atmosphere at 150 ° C. for 1000 hours, the adhesion strength is 1250 g / cm to 1
It has dropped significantly to 00 g / cm. Also, 85
Even when left in a high temperature and high humidity environment of 85 ° C. for 1000 hours, the adhesion strength decreased to 150 g / cm.

This result shows that the thickness of the electroless nickel plating film formed on the polyimide resin film is 0.01 μm.
If it is smaller than m, even if the impurity content is 10% by weight or less, the adhesion strength between the copper and the polyimide resin film remarkably decreases when left in a high temperature environment or a high temperature and high humidity environment for a long time. Therefore, it is understood that the reliability of the wiring board material is poor. Example 5 The heat load coefficient during heat treatment was 0.2, and the maximum temperature reached was 38.
A copper-polyimide substrate was prepared in the same procedure as in Example 1 except that the temperature was 0 ° C., and the adhesion strength between copper and the polyimide resin film on this substrate was measured to be 1000 g / cm 2.
However, the adhesive strength was measured after leaving it for 1000 hours in a high temperature and high humidity environment of 85 ° C. and 85%.
The value has dropped significantly to 0 g / cm.

This result shows that when the heat load coefficient at the time of heat treatment is 0.2, which is lower than the value specified in the present invention, copper and polyimide are obtained when the obtained substrate is exposed to high temperature and high humidity for a long time. The adhesion strength with the resin film is greatly reduced,
This shows that the reliability as a wiring board material is lowered.

[0043]

As described above, according to the present invention,
It is possible to form an intermediate plating film by electroless plating of nickel or cobalt or these alloys without lowering the adhesion strength between copper and polyimide resin film, and also high adhesion strength under high temperature or high temperature and high humidity environment. Moreover, when a wiring board such as FPC or TAB tape is produced using the obtained copper polyimide substrate, nickel or cobalt can be used without any special consideration in the copper etching step for wiring formation. Since it is possible to prevent the residue from remaining, it greatly contributes to the improvement of the performance of FPC, TAB tape and the like in a high temperature environment.

Claims (1)

[Claims] 1. A surface of a polyimide resin film is made hydrophilic, a catalyst is applied, electroless plating is performed, heat treatment is performed in an inert atmosphere, and then electroless copper plating or electroless copper plating is followed by electrolysis. When a copper-polyimide substrate is manufactured by performing copper plating, the surface of the polyimide resin film is made hydrophilic, and hydrazine hydrate is added to
˜15 mol / l, and an alkali metal hydroxide containing 0.5 to 5 mol / l in an aqueous solution at 10 to 50 ° C. is used, and after the catalyst is applied, nickel, cobalt or these metals are added to the surface. An electroless plating film made of any one of the alloys is applied in a thickness of 0.01 to 0.1 μm so that the content of impurities in the film is 10% by weight or less, and the obtained substrate is The maximum temperature reached on the substrate is 3
The heat treatment is performed in an inert atmosphere within a temperature range of 50 to 540 ° C. and a heat load coefficient D calculated by the following mathematical formula 1 within a range of 0.3 to 3.5. And a method for manufacturing a copper-polyimide substrate. [Equation 1] (However, to is the processing start time, ti is an arbitrary time, and Ti is the temperature of the substrate itself at the arbitrary time.)