JPH08167770A - Manufacture of copper-clad polyimide board for copper foil transfer - Google Patents

Abstract

PURPOSE: To transfer a copper foil easily on the side of a polyimide base material having a bonding agent, by using aqueous solution containing hydrazine or using the one containing both hydrazine and alkali metal hydroxide as the etching liquid of polyimide. CONSTITUTION: Through the use of aqueous solution containing hydrazine hydrate of 0.3-10mol/l, at least one surface of a polyimide resin are treated by etching. While a catalyzer for electroless plating is given to the polyimide resin, a film made of nickel, cobalt or a nickel-cobalt alloy is formed on it, and further, it is subjected to a heat treatment. Thereafter, a copper layer is formed on the film by electroless or electrical plating of copper. Also, as the aqueous solution for the etching treatment, the one containing both hydrazine hydrate of 0. 3-10mol/l and alkali metal hydroxide of 0-0.4mol/l can be used.

Description

Detailed Description of the Invention

[0001]

The present invention relates to a flexible printed wiring board (FPC) and automatic tape bonding (TAB).
The present invention relates to a method for producing a metal-coated polyimide substrate for performing a copper foil, which is a material for a printed wiring board (PWB) such as a tape, by a transfer method.

[0002]

2. Description of the Related Art With the recent miniaturization and speeding up of electronic equipment, high wiring density and high functionality have been achieved also in printed wiring boards, and along with this, thinning of copper foil has been progressing.
Usually, printed wiring boards used in electronic devices and the like, a substrate such as a polyimide film or glass epoxy,
It is manufactured by a laminating method or a thermocompression bonding method in which a copper foil manufactured by rolling or an electrolysis method is bonded with an adhesive. Here, the thickness of the copper foil produced by rolling or electrolysis is 35 μm, and even the thin one is about 15 μm, and a copper foil having a thickness less than that has low rigidity and is difficult to handle. The production of a printed wiring board using a copper foil having a thickness of 15 μm or less is very difficult and has not been performed so often.

In recent years, as a method for solving this problem, a copper foil with aluminum has been developed in which aluminum is used as a support and a copper layer of about 9 μm is formed on the surface of the support to give rigidity to the copper foil. On the other hand, regarding an adhesive, when a polyester or epoxy-based adhesive having low heat resistance is conventionally used, an isocyanate-based, nitrile rubber-based or nylon-based adhesive is used and laminated at about 100 ° C. However, with the recent increase in heat resistance, polyimide-based materials having good heat resistance have come to be used as the base material and the adhesive, and the temperature during lamination is as high as 250 ° C. or higher.

[0004]

A copper foil produced using aluminum as a support is laminated on, for example, a polyimide film substrate to produce a printed wiring board substrate, and wiring is formed to obtain a printed wiring board. In this case, it is necessary to dissolve and remove unnecessary aluminum foil with an alkaline solution or the like. Therefore, as the number of processing steps increases,
Problems such as the need for wastewater treatment of the aluminum solution occur. Further, when the thickness of the copper foil is further reduced to about 5 μm, the handling becomes difficult and the manufacturing becomes difficult even by this method. Further, since the aluminum foil as the support cannot be used repeatedly, the cost becomes high.

An object of the present invention is to supply a thin copper foil having a thickness of 10 μm or less for laminating on a polyimide base material by means of a copper-coated polyimide substrate having a polyimide resin as a support. The copper coating has heat resistance of, and further reduces the adhesion strength at the interface between the copper and the polyimide resin of the copper-coated polyimide substrate during lamination, and can easily transfer the copper foil to the polyimide base material having the adhesive. The purpose is to provide a polyimide substrate.

[0006]

In order to solve the above problems, the present invention provides hydrazine hydrate in an amount of 0.3 to 10 mol / l.
At least one surface of the polyimide resin is subjected to an etching treatment with an aqueous solution containing, a catalyst for electroless plating is applied, and a film of nickel or cobalt or an alloy thereof is formed by an electroless plating method, followed by heat treatment, and thereafter. The copper layer is formed by electroless plating or electroplating of copper. Moreover, the aqueous solution for the etching treatment contains hydrazine hydrate in an amount of 0.3 to 10 mol / l.
Further, it may contain 0 to 0.4 mol / l of an alkali metal hydroxide.

Etching is usually carried out at 10 to 50 ° C.
It takes about 30 seconds to 5 minutes. As the alkali metal, sodium, potassium, lithium or the like can be applied. Further, the type of nickel or cobalt or their alloy layer is not particularly limited. In the heat treatment, the maximum temperature reached by the polyimide resin on which nickel, cobalt, or an alloy thereof is formed is 350 to 54.
It is in the range of 0 ° C. The copper layer after heat treatment may be formed by electroless plating or electroplating, and is not particularly limited.

[0008]

In the present invention, hydrazine or an aqueous solution of hydrazine and an alkali metal hydroxide is used as the polyimide etching solution. This is because the surface of the polyimide resin is made hydrophilic by the hydrolysis of the polyimide resin by the alkali metal hydroxide and the cleavage of the imide bond by the hydrazine hydrate so that the catalyst nuclei for electroless plating are easily adsorbed. When the concentration of hydrazine hydrate is less than 0.3 mol / l, the catalyst for electroless plating is insufficiently applied and the electroless plating film is insufficiently formed. The concentration of hydrazine hydrate is 10m.
If it is higher than ol / l or the concentration of alkali metal hydroxide is higher than 0.4 mol / l, the adhesion strength between copper and polyimide resin becomes too high due to the heat treatment process after the film formation, and the adhesion strength during lamination. Is insufficiently reduced, and the copper foil cannot be transferred to the polyimide base material having the adhesive.

After forming electroless nickel or cobalt or an alloy thereof by electroless plating,
The heat treatment is performed in the inert atmosphere in the range of the maximum reached temperature of 350 to 540 ° C. This is a treatment for obtaining the adhesion strength between the copper and the polyimide resin before lamination,
This is because if the temperature is lower than 350 ° C., sufficient adhesion strength cannot be obtained, and if the temperature is higher than 540 ° C., thermal degradation of the polyimide resin becomes large and the polyimide resin cannot be reused. Generally, regarding the adhesion strength of the copper-clad polyimide substrate, the adhesion strength at which peeling does not occur at the interface between the copper and the polyimide resin is required to be 300 g / cm or more depending on the handling condition before lamination, Adhesion strength when transferring copper foil at 50g /
cm or less is required. According to the present invention, the adhesion strength before laminating is 500 to 1000 g / cm, and the temperature during laminating is set to about 250 ° C. in the atmosphere.
The adhesion strength is less than 50 g / cm, and the copper foil can be easily transferred.

If the copper-coated polyimide substrate manufactured according to the present invention is processed for wiring before laminating, the wiring itself is directly attached to the polyimide base material having an adhesive during lamination. It is possible to transfer. The polyimide resin film is preferable, and the same effect can be obtained as a copper-coated polyimide substrate not only on one side but also when copper layers are formed on both sides. Further, according to the present invention,
Since the polyimide resin is used as the support, the rigidity is high,
The thickness of the copper foil can be made extremely small, and the desired copper thickness can be easily adjusted by changing the time and current density during copper electroplating. Further, the polyimide resin is economical because it can be used repeatedly.

[0011]

EXAMPLES Next, examples of the present invention will be described. (Example 1) Kapton 200H manufactured by Toray DuPont
A 30 × 30 cm film substrate made of a polyimide resin of the mold is immersed in an aqueous solution containing 5 mol / l of hydrazine hydrate at 25 ° C. for 60 seconds to make the surface hydrophilic, and one side is masked to activate a normal catalyst. Then, the following electroless plating of nickel was performed. (Bath _{composition) NiCl 2 · 6H 2 O:} 0.1M NaH 2 PO 2 · H 2 O: 0.1M sodium citrate: 0.2 M pH: 9 (Plating conditions) Temperature: 60 ° C. Time: obtained 30 seconds The thickness of electroless nickel plating film is 0.05μ
It was m.

After that, using a hot air circulation type heating furnace manufactured by Koyo Lindbergh Co., Ltd., the temperature was raised to 400 ° C. in nitrogen gas at a temperature rising rate of 9 ° C./min, and after that, the material was heated and held for 1.5 hours. The cooling rate was 2.5 ° C./min.
Then, the following electroless copper plating treatment was performed on the film substrate. (Bath 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 The thickness of the obtained electroless copper plating film was 0.4 μm.

Further, copper was electroplated on the electroless copper plating film under the following conditions. (Bath 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: Air stirring time: 13 minutes Obtained copper The coating thickness was 5 μm. This result is
It shows that a thin copper foil having a thickness of about 5 μm can be formed on a polyimide resin film substrate. To measure the adhesion strength of the copper-coated polyimide substrate obtained here, the above,
Under the copper electroplating conditions, it is plated for 77 minutes,
The thickness of the copper foil was 35 μm.

Thereafter, an etching resist (# 873-X; manufactured by Hanami Kagaku Co., Ltd.) was applied to the copper surface of the obtained substrate so that the width was 1 cm and the length was 10 cm. It was dissolved in the copper etching solution shown. (Bath composition) FeCl ₃ : 333 g / l (Treatment condition) Temperature: 40 ° C. Time: 8 minutes Stirring: Oscillating stirring After removing the etching resist with xylene, the film substrate was fixed and the autograph (AGS-50 was used.
(A; manufactured by Shimadzu Corporation), the adhesion strength was measured at a peeling speed of 20 mm / min.

As a result, the adhesion strength was 800 g / cm, which was a sufficient adhesion strength in handling. Next, assuming adhesive strength at the time of lamination, the adhesive strength was measured by leaving it at 250 ° C. for 20 minutes. As a result, the adhesion strength is 30g
The adhesion strength was such that the copper foil could be transferred during lamination. As a result, in the handling work up to the transfer process of the copper foil, it does not peel off at the interface between the copper and the polyimide resin, and at the time of lamination, the interface between the copper and the polyimide resin peels off, showing that the transfer of the copper foil can be sufficiently performed. ing.

(Example 2) Kapt manufactured by Toray DuPont
A 30 × 30 cm film substrate made of on200H type polyimide resin is immersed for 60 seconds in a 25 ° C. aqueous solution containing 0.3 mol / l hydrazine hydrate and 0.4 mol / l potassium hydroxide to make the surface hydrophilic. After that, one side was masked and a normal catalyst activation treatment was performed, and the following electroless plating of cobalt was performed. (Bath _{composition) CoSo 4 · 7H 2 O:} 0.05M NaH 2 PO 2 · H 2 O: 0.2M sodium citrate: 0.2M pH: 10 (Plating conditions) Temperature: 60 ° C. Time: obtained 2 minutes The thickness of the electroless cobalt plating film is 0.03μ
It was m. After that, using a hot air circulation type heating furnace manufactured by Koyo Lindbergh Co., Ltd., the temperature was raised to 420 ° C. at a temperature rising rate of 9 ° C./min in a nitrogen atmosphere, and then heated and held for 1.5 hours. It cooled at the temperature-fall rate of 5 degreeC / min.

Thereafter, a copper-coated polyimide substrate was prepared in the same manner as in Example 1 and the adhesion strength was measured. As a result, the adhesion strength was 900 g / cm, which was sufficient in handling. Next, assuming the adhesion strength during lamination, 2
It was left at 50 ° C. for 20 minutes and the adhesion strength was measured. As a result, the adhesion strength was 40 g / cm, which was such that the copper foil could be transferred during lamination. As a result, in the handling work up to the transfer step of the copper foil, it does not peel off at the interface between the copper and the polyimide resin, and at the time of lamination, the interface between the copper and the polyimide peels off, showing that the transfer of the copper foil can be sufficiently performed. There is.

Example 3 0.5 mol of hydrazine hydrate was added.
The treatment was performed in the same manner as in Example 1 except that the heat treatment temperature in nitrogen gas was set to 350 ° C. in addition to 1 / l. As a result, in the handling work up to the transfer step of the copper foil, there is no peeling at the interface between the copper and the polyimide resin, the interface between the copper and the polyimide is peeled off at the time of lamination, and the copper foil can be sufficiently transferred in the examples. It was similar to 1.

Example 4 10 mol of hydrazine hydrate
The treatment was performed in the same manner as in Example 1 except that the amount was changed to / l. As a result, in the handling work up to the transfer process of the copper foil,
It was similar to Example 1 in that it did not peel off at the interface between the copper and the polyimide resin, and at the time of lamination, the interface between the copper and the polyimide peeled off and the transfer of the copper foil was sufficiently performed.

Example 5 10 mol of hydrazine hydrate
A treatment was performed in the same manner as in Example 2 except that / l was set. As a result, in the handling work up to the transfer process of the copper foil,
It was similar to Example 2 in that it did not peel off at the interface between the copper and the polyimide resin, and at the time of lamination it peeled off at the interface between the copper and the polyimide so that the copper foil could be sufficiently transferred.

(Comparative Example 1) A polyimide resin was added at 0.2 mo
Nickel electroless plating was performed by the same treatment as in Example 1 except that the surface was made hydrophilic by dipping in an aqueous solution of 25 ° C containing 1 / l of hydrazine hydrate for 60 seconds.
However, a sufficient nickel film was not formed on the polyimide surface, and the subsequent steps could not be performed. This result shows that when the hydrazine hydrate and alkali hydroxide concentrations are below the concentration range of the present invention, the formation of the electroless plating film becomes insufficient.

Comparative Example 2 12 mol of polyimide resin
The same treatment as in Example 1 was carried out except that the surface was made hydrophilic by dipping in an aqueous solution of 25 ° C. containing hydrazine hydrazine / l / l and 0.5 mol / l potassium hydroxide for 60 seconds.
The adhesion strength was measured. As a result, the adhesion strength is 1200g
/ Cm, which was a sufficient adhesion strength in handling.
Next, measure the adhesion strength at the time of lamination and
It was left for 0 minutes and the adhesion strength was measured. As a result, the adhesion strength was as high as 1000 g / cm, and the adhesion was such that the copper foil could not be transferred during lamination. This result indicates that when the hydrazine hydrate and alkali hydroxide concentrations exceeded the concentration range of the present invention, the adhesion strength between copper and polyimide during lamination was high, and the copper foil could not be transferred.

[0023]

EFFECTS OF THE INVENTION Since the present invention is constituted as described above, it is possible to easily form a copper foil having a thickness of 10 μm or less on a polyimide film. Copper foil can be easily transferred to the material, and it can be used for higher wiring density and higher functionality of printed wiring boards. In addition, since the polyimide film can be repeatedly used, it has excellent economical efficiency.

Claims (3)

[Claims] 1. A hydrazine hydrate in an amount of 0.3 to 10 mol / mol.
At least one surface of the polyimide resin is etched with an aqueous solution containing 1 to give a catalyst for electroless plating, and a coating film of nickel or cobalt or an alloy thereof is formed by an electroless plating method and then in an inert atmosphere. And a copper layer is formed by electroless plating or electroplating of copper, and a method for producing a copper-coated polyimide substrate for a transfer copper foil. 2. A hydrazine hydrate in an amount of 0.3 to 10 mol / mol.
at least one surface of the polyimide resin is etched with an aqueous solution containing 1 or less and 0.4 mol / l or less of an alkali metal hydroxide to impart a catalyst for electroless plating to form a coating film of nickel or cobalt or an alloy thereof. A method for producing a copper-coated polyimide substrate for a transfer copper foil, which comprises forming by a non-electrolytic plating method, followed by heat treatment in an inert atmosphere, and then forming a copper layer by electroless plating or electroplating of copper. 3. The heat treatment according to any one of claims 1 to 3, wherein the maximum attainable temperature of the polyimide resin coated with nickel, cobalt or an alloy thereof is in the range of 350 to 540 ° C. For producing a copper-coated polyimide substrate for transfer copper foil.