JPH11274685A - Method of forming printed circuit board - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide little difference between the etching speeds of insulation layers even at a high speed etching, by laminating a plurality of different kinds of insulation resin layers and forming holes for electric connection through the resin layers, using a plasma. SOLUTION: A thermoplastic adhesive polyimide PI-A of 3 μm thick and Tg = about 200 deg.C is coated on both surfaces of a Cu film having a thickness of 18 μm and holes of 0.3 mm diameter, and Regulus made of a thermoplastic polyimide film of Tg=270 deg.C, a polyimide layer obtd. by laminating a polyimide film captone H of 12.5 μm thick and Tg = about 420 deg.C and PI-A, and a Cu plate of 2 mm thick are overlaid on one side thereof to constitute a Cu plate/ polyimide/Cu film laminate as a circuit board. Thus there is little difference between the etching speeds of the insulation layers even at a high speed etching, and a fixed formed shape can be obtd.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for forming holes in an insulating layer of a printed circuit board. More specifically, the present invention relates to a method for forming a hole in an insulating layer of a printed circuit board using an insulating layer obtained by laminating a plurality of layers of different types of resins.

[0002]

2. Description of the Related Art In recent years, in the electronics industry, there has been a demand for higher performance, higher functions, and more compact electronic devices, and accordingly, IC chips and boards for mounting the IC chips have become finer. , The density is increasing. I
In the case of the C chip, a dry process using plasma is indispensable for fine patterning of silicon or the like. Further, a circuit board in which a copper foil as a conductive layer and a polyimide as an insulating layer are alternately laminated is widely used as an IC mounting board because of the excellent heat resistance, electrical characteristics, and the like of polyimide.

[0003] A mounting technique of a printed wiring board, particularly a technique of forming a through hole and a via hole in manufacturing a printed circuit board is particularly important. There are dry processes such as a mechanical drilling method and a laser processing method as a current through hole (via hole) and via hole (via hole) forming method, but a wet method is used in terms of cost or processing capability (etching speed). At present, there are many cases.

[0004] In recent years, various mechanical and electrical characteristics are required for a printed circuit board, and a polymer having a plurality of different structures may be used for a resin layer as an insulating layer.
For example, a polyimide that is a heat-resistant polymer is often used as the insulating layer. However, the physicochemical properties vary depending on the type of the polyimide, and a plurality of polyimides may be used as the insulating layer as needed.

In the conventional wet etching method, the etching rate is different depending on the type of the insulating layer. Therefore, the etching rate may be high in a layer having an insulating layer and slow in another layer. In particular, it has been found that a new problem arises when a resin layer which is easily etched is etched first and then a resin layer which is hardly etched is etched. That is, while a layer with a low etching rate is being etched, a layer with a high etching rate is further etched to increase the undercut, and the processed shape of the entire insulating layer cannot be kept constant. further,
As the printed circuit board becomes finer, the problem of the processed shape becomes more serious when a plurality of insulating layers are used.

[0006]

SUMMARY OF THE INVENTION An object of the present invention is to provide a method of punching an insulating layer of a circuit board using plasma, and more particularly, to stack a plurality of layers obtained from polymers having different structures as the insulating layer. It is an object of the present invention to provide a technique for etching a printed circuit board having a polyimide layer, which is obtained by using a plasma, by using plasma.

[0007]

Means for Solving the Problems The present inventors have conducted intensive studies on the above-mentioned problems, and as a result, have found that when drilling a printed circuit board having an insulating layer formed by laminating a plurality of resin layers having different structures. And found that plasma should be used. Particularly, regardless of the structure of the polymer, even if etching is performed at a high speed, there is almost no difference in the etching rate of each insulating layer, and a technique for providing a fixed processed shape has been found, and the present invention has been completed.

That is, the present invention provides (1) an insulating layer mainly formed of a resin and formed between conductive layers, wherein the insulating layer is formed by laminating a plurality of resin layers of different types. The method for processing a printed circuit board is characterized in that a hole is formed in a resin layer for making electrical connection by using plasma. (2) The glass transition temperature Tg of the resin layer is (1) The method for processing a printed circuit board according to (1), wherein the resin is made of a heat-resistant resin having a temperature of at least 130 ° C, and (3) the resin is made of polyimide having a different structure. A method for processing a printed circuit board according to any one of (2) and (4).
In a polyimide obtained by reacting an aromatic tetracarboxylic acid with an aromatic diamine, the structure of the aromatic tetracarboxylic acid is represented by the following formula (1), (2), (3) or (3). At least one of the aromatic diamines represented by the formulas (15) and (4) [formula 16] is represented by the formula (5) [formula 17], the formula (6) [formula 18], the formula (7) [formula 16] 19] The method for processing a printed circuit board according to (3), comprising at least one of formulas (8) [formula 20] and (9) [formula 21],

[0009]

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[0010]

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[0011]

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[0012]

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[0013]

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[0014]

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[0015]

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[0016]

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[0017]

Embedded image (5) The structure of polyimide is represented by the formula (10):
The method of processing a printed circuit board according to (4), wherein at least two of the formulas (11) [Formula 23] and (12) [Formula 24] are combined.

[0018]

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[0019]

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[0020]

Embedded image (6) Tg1 is the lowest Tg of the resin in the resin layer.
And the temperature T of the atmosphere in which the holes are formed is expressed as (Tg1-1)
(1) to (5), wherein plasma processing is performed while controlling the temperature in the range of (00) ° C ≦ T ≦ (Tg1 + 100) ° C.
(7) The method for processing a printed circuit board according to any one of (1) to (6), wherein the gas used to generate the plasma is a mixed gas of oxygen and a fluorine-based compound gas. (8) The method for processing a printed circuit board according to (7), wherein the fluorine-based compound gas is fluorine. (7) The method for processing a printed circuit board according to (7), wherein the fluorine compound gas is nitrogen trifluoride, wherein (10) the method for generating plasma uses a high frequency power supply of 10 to 100 MHz. A method for processing a printed circuit board according to any one of (1) to (9), wherein (1)
1) The method for processing a printed circuit board according to (10), wherein a negative DC voltage is applied to the high-frequency voltage independently of the high-frequency power supply.

[0021]

BEST MODE FOR CARRYING OUT THE INVENTION A circuit board according to the present invention is a circuit board in which a copper foil as a conductive layer and a resin layer as an insulating layer are alternately laminated. A plurality of types of resin layers are stacked as an insulating layer sandwiched between copper foils. The present invention is applicable to any such circuit board. Above all, it can be suitably used for a multilayer circuit board using polyimide having excellent heat resistance, electrical properties and the like as the resin.

It is industrially important to obtain an etching rate comparable to that of a conventionally used wet method for etching an insulating layer. To this end, it is effective means to heat the printed circuit board and to use plasma using a mixed gas of an oxygen-based gas and a fluorine-based compound gas.

Considering that the etching proceeds not by a physical reaction but by a chemical reaction, it is necessary to perform the etching under heating in order to improve the reaction rate. In particular, it is necessary to heat the insulating layer near the glass transition temperature of the insulating layer. It is most reactive to do it. The optimum temperature T differs depending on the type of the polymer. For example, in the case of a polymer having a heat resistance of 150 ° C. or higher, the glass transition temperature of the polymer is defined as Tg. (T
g-100) .degree. C.≤T.ltoreq. (Tg + 100) .degree. C., it is possible to obtain an etching rate higher than that performed at room temperature.
g-50) The temperature is further increased in an atmosphere where a temperature ≤ T ≤ Tg ° C.

At a temperature higher than Tg, the thermophysical properties of the polymer greatly change, which may result in a defective circuit board after etching. Therefore, when a laminated body of different types of resins is used as the insulating layer in the present invention, if the resin having the lowest Tg is Tg1, the temperature T of the etching atmosphere is (Tg1-100) ° C. ≦ T ≦
(Tg1 + 100) ° C, preferably (Tg1-50) ° C
≦ T ≦ Tg1 ° C.

Further, in addition to oxygen gas, fluorine-based compound gas such as nitrogen trifluoride (NF ₃ )
A system in which a gas or a fluorine (F ₂ ) gas is added is good, that is, a system in which these gases are added to an oxygen gas is effective for high-speed etching. The reason why the addition of these gases is effective is that C which is generally used as an etching species
It compared with a fluorine-based compound gas F _4, etc., F-F bonds and N-
This is because the F bond has lower binding energy than the C—F bond and easily becomes a fluorine ion, an NFx ion, or a radical in plasma.

In the present invention, the polymer as the insulating layer of the circuit board is not particularly limited, but a polyimide resin which is a heat-resistant resin is often used at present.
A specific example of the polyimide layer is a polyimide film that is commercially available under the trade name of Kapton, Upilex, Apical, or the like. Further, acid anhydrides such as pyromellitic anhydride, biphthalic anhydride, benzophenonetetracarboxylic anhydride, oxydiphthalic anhydride, hydrofurandiphthalic anhydride and methoxydiaminobenzene, 4,4′-oxydianiline, 3, 4 '
Oxydianiline, 3,3 ′ oxydianiline, bisdianilinomethane, 3,3′-diaminobenzophenone,
p, p-aminophenoxybenzene, p, m-aminophenoxybenzene, m, p-aminophenoxybenzene, m, m-aminophenoxybenzene, chloro-m-
Aminophenoxybenzene, p-pyridineaminophenoxybenzene, m-pyridineaminophenoxybenzene, p-aminophenoxybiphenyl, m-aminophenoxybiphenyl, p-bisaminophenoxybenzylsulfone, m-bisaminophenoxybenzylsulfone, p-bisamino Phenoxybenzylketone, m-bisaminophenoxybenzylketone, p-bisaminophenoxybenzylhexafluoropropane, m-bisaminophenoxybenzylhexafluoropropane, m-
Bisaminophenoxybenzylhexafluoropropane, p-bisaminophenoxybenzylpropane, o-
Polyimide formed by reaction with an amine such as bisaminophenoxybenzylpropane, m-bisaminophenoxybenzylpropane, p-diaminophenoxybenzylthioether, m-diaminophenoxybenzylthioether, indanediamine, spirobidiamine, diketonediamine, and imidization Can also be used effectively in the present invention.

Among them, particularly in a polyimide obtained by reacting an aromatic tetracarboxylic acid with an aromatic diamine, the structure of the aromatic tetracarboxylic acid is represented by the above-mentioned formulas (1), (2), (3) and (3). At least one of (4)
The structure of the species and the aromatic diamine is at least one of the formulas (5), (6), (7), (8) and (9), and the insulating layer of the printed circuit board And is used effectively in the present invention.
Here, at least one type of each structural body refers to, for example, a polyimide having formula (1) and formula (5) as a structural unit, wherein aromatic tetracarboxylic acid is represented by formula (1) and formula (2)
Or a structure containing the structure of the formula (3) in a fixed ratio, or a structure in which the aromatic diamine contains the formula (5), the formula (6), the formula (7), or the formula (8) in a fixed ratio. Refers to a so-called block polymer.

The thickness of the insulating layer is not particularly limited. However, considering the role of the insulating layer of the circuit board, if it is too thin, it is difficult to maintain the insulating properties. However, a problem arises in terms of cost, increase and other performance aspects. Therefore, the thickness of one insulating layer (in a state where a plurality of insulating layers are stacked) is about 5 to 500 μm,
Preferably it is about 10 to 100 μm.

When a circuit board having an insulating layer made of a plurality of different kinds of resins centering on such a polyimide-based resin is dry-etched by using plasma, Tg of the resin constituting the insulating layer is used. Is lower than the lowest temperature, more specifically, for example, in the case of an insulating layer in which polyimide having a Tg of about 250 ° C. and 350 ° C. is laminated, since Tg1 is 250 ° C., 150 ° C. to 350 ° C.
When etching is performed in the range of ° C, preferably in the range of 200 ° C to 250 ° C, the speed is dramatically improved.

The amount of the etching gas to be added is 5 to 90 vol%, preferably about 10 to 50 vol%, based on the oxygen gas. In the present invention, a high-frequency power source is preferable as a power source used to generate plasma, and its frequency is 10 kHz to 1000 MHz, preferably 10 kHz.
The frequency is from MHz to 100 MHz, but 13.56 MHz or 27 MHz is preferably used in view of the Radio Law and handling. Particularly, a frequency in this range is preferable for controlling the mobility of ions and radicals in the plasma. Further, applying a negative direct current component to the high frequency independently of the high frequency power supply is an effective means for controlling the ion potential and controlling the selective etching by ions.

In the present invention, at least (a) a plasma processing chamber for performing a plasma process, which is provided with means for introducing a circuit board, means for holding the circuit board, and means for discharging the circuit board, (b) a power application device, and (c) vacuum evacuation Means, (d) a dry etching apparatus provided with substrate heating and temperature control means. Furthermore, in order to improve the efficiency of the etching process, (e) a loading chamber for loading a circuit board installed on the substrate holder, (f) a loading chamber for unloading, and (g) plasma from the loading chamber. It is preferable to use an apparatus that also includes a processing chamber and a transfer mechanism for transferring the substrate holder from the plasma processing chamber to the unloading chamber. This is because when the plasma processing is performed continuously, the processing chamber is in a high vacuum, so that the circuit board is held in a chamber in which a certain degree of vacuum is maintained in advance, and then the circuit board is transferred to the processing chamber where the etching processing is performed. Is to shorten the time until a high vacuum is achieved. The spare room mentioned here refers to a (e) carry-in room and (f) carry-out room in a chamber in which a certain degree of vacuum is kept in advance.

The operating pressure of the plasma processing apparatus according to the present invention is not particularly limited as long as the plasma processing chamber can generate plasma. For example, 0.13 to 1,
It is 330 Pa, preferably about 1.3 to 270 Pa. The operating pressure of the loading chamber and the unloading chamber is higher than the pressure of the plasma processing chamber, for example, 1.3 to 13,300 P.
a, preferably about 13 to 1,330 Pa. The high pressure of the loading chamber and the unloading chamber is to save time for evacuating the plasma processing chamber, and the operation is performed by opening the atmosphere from the above pressure and evacuating the atmosphere from the atmosphere to the above pressure. The pressure in the plasma processing chamber is controlled by evacuation to the plasma generation pressure because the pressure in the chamber increases when the gate valve between the loading chamber and the loading chamber is opened.
Since the pressure inside the chamber increases again when the gate valve between the chamber and the carry-out chamber is opened, the chamber is evacuated to a plasma generation pressure. Hereinafter, a more detailed description will be given of a continuous processing apparatus using parallel plate type RF electrodes as an example.

The plasma processing chamber 11 has a frequency of 13.56 MHz.
Parallel plate high frequency electrode (electrode including RF power supply) 61
And a low-pass filter 62 that can independently apply a DC voltage to the RF electrode 61, and a counter electrode 71 (ground). In the plasma processing chamber 11, flanges 81 and 81 'with a bellows valve and a gate valve 8 for partitioning the chamber are provided.
2, 82 'are attached, and then the substrate carry-in chamber 21 and the substrate carry-out chamber 22 are connected. The plasma processing chamber 11 and the electrode 6
The heaters 1 and 71 are provided so as to control and heat the temperature. In addition, transfer arms 41 and 41 ′ are installed as a means for loading a substrate between the substrate loading chamber 21 and the plasma processing chamber 11 and a means for unloading a substrate between the substrate loading chamber 22 and the plasma processing chamber 11, respectively. Have been. The tips of the transfer arms 41 and 41 'are fork-shaped so that the substrate holder 31 can be placed thereon. Substrate loading room 2
1. The substrate discharge chamber 22 is provided with a leak valve so that the substrate can be opened to the atmosphere. Further, a rotary pump 12 is connected to the plasma processing chamber 11 so that the inside can be evacuated, and a mechanical booster pump 13 is connected to achieve a higher degree of vacuum. Rotary pumps 12 ′ and 12 ″ are also provided in the substrate carry-in chamber 21 and the carry-out chamber 22, respectively, so that the inside can be kept at a vacuum. The plasma processing chamber 11 has a gas line 14 (oxygen And NF _{3 etc.} ).

As a plasma etching method, first, the circuit board 51 is set on the substrate holder 31. Thereafter, the circuit board 51 and the substrate holder 31 are set at the tip (fork-like structure) of the substrate transfer arm 41 in the substrate loading chamber 21, the lid of the substrate loading chamber 21 is closed, and the chamber is evacuated. When the degree of vacuum reaches a pressure equal to or slightly higher than that of the plasma processing chamber 11, the gate valve 82 opens. After the gate valve 82 is opened, the substrate holder 31 on which the substrate 51 is placed is carried into the plasma processing chamber 11 and placed on the electrode 61. Thereafter, the transfer arm 41 returns to the substrate loading chamber, and closes the gate valve 82. Gas flows into the plasma processing chamber 11 through a gas line 14, and plasma is generated for a certain time. At this time, since the substrate loading chamber 21 is open to the atmosphere, the substrate holder 31 on which the substrate 51 is newly placed can be set. After the plasma processing (etching) for a certain time is completed, the degree of vacuum in the substrate unloading chamber 22 is reduced to the plasma processing chamber 11.
When a pressure equal to or slightly higher than is reached, the gate valve 82 'opens. After the gate valve 82 is opened, the transfer arm 41 'in the substrate unloading chamber 22 unloads the substrate holder 31 on which the substrate 51 is placed from the plasma processing chamber 11 to the substrate unloading chamber 22, and the gate valve 82' closes. The substrate unloading chamber 22 is opened to the atmosphere, and when the pressure returns to the atmospheric pressure, the substrate 51 and the substrate holder 31 are taken out. At this time, the new substrate 51 set in the substrate holder 31 in the substrate carry-in chamber 21 is transferred to the plasma processing chamber 11 after the gate valve 82 is opened. By repeating the transfer and the plasma processing in this manner, the circuit board is etched continuously and at high speed. In the example of the present apparatus, the circuit board is placed on the RF electrode and the etching is performed. However, the place where the electrode is placed may be changed and the board may be placed on the counter electrode. A schematic diagram of such an apparatus is shown in FIG.

[0035]

The present invention will be described more specifically with reference to the following examples. A case in which a film having a polyimide structure represented by the formula (10), the formula (11), or the formula (12) is bonded using the adhesive polyimide PI-A will be described.

Example 1 A copper thin film having a thickness of 18 μm and a hole diameter of 0.3 mmφ,
Thermoplastic polyimide film (trade name: Regulus, thickness 12.5 μm, Tg = 270 ° C., manufactured by Mitsui Chemicals, Inc.)
A thermoplastic adhesive polyimide PI-A (manufactured by Mitsui Chemicals, Inc .: thickness 3 μm, Tg = about 200 ° C.) is applied to both surfaces of the substrate, and a polyimide film (trade name:
A polyimide layer obtained by laminating PI-A with Kapton H, thickness 12.5 μm, Tg = about 420 ° C., manufactured by Toray DuPont) and a copper plate having a thickness of 2 mm were laminated by pressing. A laminate composed of a copper plate / polyimide / copper thin film was used as a circuit board (see FIG. 2 for the structure; Regulus is more difficult to etch than Kapton H in the wet method). Mixed gas of oxygen gas and NF ₃ (composition ratio is 80: 2
0), etching was performed by the plasma etching apparatus shown in FIG. 1 (however, no DC voltage was applied by the low-pass filter 62). The etching conditions are shown below. Etching conditions: oxygen gas / NF ₃ gas flow rate 80/20 sccm transfer chamber, unloading chamber pressure 133 Pa processing chamber pressure 13.3 Pa RF electrode power 400 W temperature 200 ° C. (processing chamber)

Example 2 A copper thin film having a thickness of 18 μm and a hole diameter of 0.3 mmφ,
On both sides of a polyimide film (trade name: Upilex S, thickness 12.5 μm, Tg = 359 ° C., manufactured by Ube Industries), a thermoplastic adhesive polyimide PI-A (manufactured by Mitsui Chemicals, Inc .: thickness 3 μm, Tg) = About 200 ° C)
A polyimide film (trade name: Kapton H, thickness 12.5 μm, Tg = about 420 ° C.,
A laminate composed of a copper plate / polyimide / copper thin film obtained by laminating a polyimide layer and a 2 mm-thick copper plate obtained by laminating PI-A with PI-A was used as a circuit board (configuration). (See FIG. 3; Upilex S is more difficult to etch than Kapton H in the wet method.) Mixed gas of oxygen gas and F ₂ (composition ratio is 80: 2
0), etching was performed by the plasma etching apparatus shown in FIG. 1 (however, a negative DC voltage of -300 V was applied by the low-pass filter 62). The etching conditions are shown below. Etching conditions: oxygen gas / F ₂ gas flow rate 80/20 sccm transfer chamber, unloading chamber pressure 133 Pa processing chamber pressure 27 Pa RF electrode power 400 W DC voltage -300 V temperature 180 ° C. (processing chamber)

Embodiment 3 In FIG. 1, a high-frequency power source of 13.56 MHz
Etching was performed under the same conditions as in Example 1 except that a 7 MHz high frequency power supply was used. Etching conditions: oxygen gas / NF ₃ gas flow rate 80/20 sccm transfer chamber, unloading chamber pressure 133 Pa processing chamber pressure 13.3 Pa RF electrode power 400 W temperature 200 ° C. (processing chamber)

Comparative Example 1 Using the circuit board described in Example 1, etching was performed with a hydrazine solution.

Comparative Example 2 The circuit board described in Example 1 was used. Etching was performed in the same manner as in Example 1. However, the temperature of the processing chamber was kept constant at room temperature (about 20 ° C.). Etching conditions: oxygen gas / NF ₃ gas flow rate 80/20 sccm transfer chamber, unloading chamber pressure 133 Pa processing chamber pressure 27 Pa RF electrode power 400 W temperature 20 ° C. (processing chamber)

Test Example 1 In Examples 1 and 2 and Comparative Examples 1 and 2, the time required for forming a hole in the polyimide layer was measured and the results are shown in Table 1.
The etched shape was also evaluated, and the anisotropy was evaluated as + or-(+ for an aspect ratio of 3 or more and large anisotropy, and partially isotropic (one with an aspect ratio close to 1). Those marked with are marked with-).

[0042]

[Table 1]

[0043]

According to the present invention, a plurality of layers of resins having different structures are formed into insulating layers by dry etching.
A method for boring a circuit board can be provided.

[Brief description of the drawings]

FIG. 1 is a schematic diagram of an apparatus.

FIG. 2 is a sectional view of a circuit board.

FIG. 3 is a sectional view of a circuit board.

[Explanation of symbols]

 11: Plasma processing chamber 12, 12 ', 12 ": Rotary pump 13: Mechanical booster pump 14: Gas line 21: Substrate carry-in chamber 22: Substrate carry-out chamber 31: Substrate holder 41, 41': Transfer arm 51: Circuit board 61: RF electrode 62: Low-pass filter for applying DC voltage 71: Counter electrode 81, 81 ': Flange with valve 82, 82': Gate valve

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Moruji Morita, 1190 Kasama-cho, Sakae-ku, Yokohama-shi, Kanagawa Mitsui Chemicals, Inc.

Claims (11)

[Claims] An insulating layer formed between conductive layers and mainly made of a resin, wherein the insulating layer is formed by laminating a plurality of layers of different types of resin to establish electrical connection. A method of processing a printed circuit board, characterized in that a hole in a resin layer to be formed is formed using plasma. 2. The method for processing a printed circuit board according to claim 1, wherein the resin layer is made of a heat-resistant resin having a glass transition temperature Tg of at least 130 ° C. 3. The method according to claim 1, wherein the resin is made of polyimide having a different structure. 4. A polyimide obtained by reacting an aromatic tetracarboxylic acid with an aromatic diamine, wherein the structure of the aromatic tetracarboxylic acid is represented by the formula (1), the formula (2), the formula (2), (3) At least one of the chemical formulas (3) and (4) and the structure of the aromatic diamine is represented by the formula (5)
It consists of at least one of the following: [Formula 5], Formula (6) [Formula 6], Formula (7) [Formula 7], Formula (8) [Formula 8] and Formula (9) [Formula 9] The method for processing a printed circuit board according to claim 3, wherein: Embedded image Embedded image Embedded image Embedded image Embedded image Embedded image Embedded image Embedded image Embedded image 5. A polyimide structure represented by the following formula (10):
0], formula (11) [formula 11] and formula (12) [formula 1]
5. The method for processing a printed circuit board according to claim 4, wherein at least two of the above two methods are combined. Embedded image Embedded image Embedded image 6. The lowest Tg of the resin in the resin layer is defined as Tg1, and the temperature T of the atmosphere in which the holes are formed is expressed as (Tg
The method for processing a printed circuit board according to any one of claims 1 to 5, wherein plasma processing is performed while controlling the temperature in a range of (1-100) ° C ≤ T ≤ (Tg1 + 100) ° C. 7. A gas used to generate a plasma,
7. The method for processing a printed circuit board according to claim 1, wherein the method is a mixed gas of oxygen and a fluorine-based compound gas. 8. The method for processing a printed circuit board according to claim 7, wherein the fluorine-based compound gas is fluorine. 9. The method for processing a printed circuit board according to claim 7, wherein the fluorine-based compound gas is nitrogen trifluoride. 10. A method for generating plasma, comprising:
10. The method for processing a printed circuit board according to claim 1, wherein a high frequency power supply of 00 MHz is used. 11. The method for processing a printed circuit board according to claim 10, wherein a negative DC voltage is applied to the high frequency voltage independently of the high frequency power supply.