JP2002057440A - Discharge plasma processing method and apparatus thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a discharge plasma processing method and an apparatus therefor which can realize a stable discharge state under the atmospheric pressure condition and treat circuit boards with a small quantity of process gas, using a simple and convenient apparatus. SOLUTION: The discharge plasma processing method and the apparatus thereof are characterized, by setting a solid dielectric on at least one opposite surface of a pair of opposed electrodes under a pressure near the atmospheric pressure, introducing a process gas between the opposed electrodes, applying a pulse-like electric field to obtain a plasma, and exposing a circuit board to the plasma.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a discharge plasma processing method, and more particularly, to a discharge plasma processing method for a circuit board and an apparatus therefor.

[0002]

2. Description of the Related Art As a method for treating a surface of a solid such as a plastic, a dry process for generating glow discharge plasma at a pressure of 1.333 to 1.333 × 10 ⁴ Pa is widely known. In this method, the pressure is 1.3
When the pressure exceeds 33 × 10 ⁴ Pa, the discharge is localized and shifts to arc discharge, which makes it difficult to apply to a plastic substrate having poor heat resistance.
It is necessary to perform the treatment under a low pressure of ⁴ Pa.

[0003] Since the above-mentioned surface treatment method requires treatment at a low pressure, a vacuum chamber, a vacuum evacuation device, and the like must be provided, and the surface treatment device becomes expensive. In the case of processing an area substrate, a large-capacity vacuum vessel and a large-output evacuation device are required, so that the surface treatment device becomes more expensive.
In addition, when performing surface treatment on a plastic substrate having high water absorption, it takes a long time to evacuate the plastic substrate.

Japanese Patent Publication No. 2-48626 discloses a method of forming a thin film using a thin wire electrode. This thin film forming method is to mix an inert gas such as helium, a fluorine-containing gas, and a monomer gas and supply the mixed gas to a glow discharge plasma region near the substrate from a porous tube having a plurality of apertures, thereby forming a thin film on the substrate. Is formed.

In this thin film manufacturing method, glow discharge plasma is generated at atmospheric pressure, so that the cost of equipment and facilities can be reduced, and a large area substrate can be processed. But,
In this thin film manufacturing method, a flat electrode or a curved electrode is used in the inside of the processing container, so that the apparatus can be further simplified. However, at present, since the size and shape of the base material are restricted, it is not easy to perform surface treatment at an arbitrary position.

[0006] Japanese Patent Application Laid-Open No. Hei 5-275193 discloses that a mixed gas composed of a rare gas and a processing gas is maintained in a unidirectional flow state between electrodes provided with a solid dielectric and discharge plasma is generated. An apparatus for treating a substrate surface to be generated is disclosed.
However, since this surface treatment apparatus is an apparatus that generates discharge plasma in an open-system atmospheric pressure state, in the case where a desired surface treatment is performed by eliminating the influence of the outside air and bringing the discharge plasma into contact with the substrate surface. It is necessary to flow the mixed gas at a high speed, and it is necessary to keep flowing a large flow of gas, which is not a satisfactory surface treatment apparatus.

As a method of cleaning a circuit board,
JP-A-9-148095, JP-A-10-1070
No. 62 discloses a plasma cleaning method as a method of removing dirt from a bonding pad. However, this method requires a vacuum chamber, a vacuum evacuation device, and the like, and similarly to the above, the surface cleaning processing device is expensive, and has a problem that the processed product is expensive.

[0008]

SUMMARY OF THE INVENTION In view of the above, it is an object of the present invention to realize a stable discharge state under atmospheric pressure conditions and to process a circuit board with a simple apparatus and a small amount of processing gas. And a discharge plasma processing method.

[0009]

Means for Solving the Problems The present inventor has made extensive studies in view of the above-mentioned problems, and as a result, the use of a discharge plasma processing apparatus capable of realizing a stable discharge state under atmospheric pressure conditions has facilitated the use of a circuit board. And found that the present invention was completed.

That is, according to a first aspect of the present invention, a solid dielectric is provided on at least one of opposing surfaces of a pair of electrodes facing each other under a pressure near atmospheric pressure, and a processing gas is provided between the pair of electrodes. A discharge plasma treatment method for a circuit board, characterized by contacting a circuit board with a plasma obtained by applying a pulsed electric field to the circuit board.

According to a second aspect of the present invention, the pulsed electric field has a pulse rise and / or fall time of 100 μs or less and an electric field intensity of 1 to 250 kV / cm. 4. The discharge plasma processing method described in 1. above.

A third invention of the present invention is the first or second invention, wherein the pulsed electric field has a frequency of 0.5 to 100 kHz and a pulse duration of 1 to 1000 μs. Is a discharge plasma processing method.

A fourth invention of the present invention is characterized in that plasma generated between the opposed electrodes is guided from the gas outlet nozzle toward the base material.
It is a discharge plasma processing method according to any one of the first to third aspects.

According to a fifth aspect of the present invention, there is provided a solid dielectric container provided with a gas outlet at one electrode, and another electrode provided opposite the gas outlet to provide a gas outlet. A circuit board is arranged between the port and the other electrode, and the processing gas is continuously discharged from the gas outlet, and at the same time, an electric field is applied between the one electrode and the other electrode to cause a discharge. A discharge plasma processing method for generating plasma, wherein a pulsed electric field applied between the electrodes is
A discharge plasma treatment method for a circuit board, wherein a rise time and a fall time are 100 μs or less and an electric field intensity is 1 to 100 kV / cm.

According to a sixth aspect of the present invention, the circuit board is a resin plate for a circuit board.
5 is a discharge plasma processing method according to any one of the fifth aspects of the invention.

According to a seventh aspect of the present invention, there is provided a pair of opposing electrodes having a solid dielectric disposed on at least one opposing surface, a mechanism for introducing a processing gas between the pair of opposing electrodes,
A discharge plasma processing apparatus for processing a circuit board, comprising: a mechanism for applying a pulsed electric field between the electrodes; and a mechanism for bringing plasma obtained by the pulsed electric field into contact with a circuit board.

According to an eighth aspect of the present invention, a mechanism for bringing plasma into contact with a circuit board is such that plasma generated between opposed electrodes is guided from a gas outlet nozzle toward a substrate. A discharge plasma processing apparatus according to a seventh aspect of the invention.

According to a ninth aspect of the present invention, there is provided an electrode provided with a solid dielectric container having a gas outlet and another electrode provided opposite the gas outlet. The processing gas is continuously discharged from the gas outlet, and the rise time and the fall time are 10 times between the one electrode and the other electrode.
0 μs or less, and the electric field intensity is 1 to 100 kV /
A discharge plasma processing apparatus for processing a circuit board, characterized in that a pulsed electric field of 1 cm is applied.

According to a tenth aspect of the present invention, there is provided a discharge plasma processing apparatus according to the ninth aspect, wherein the solid dielectric container is made of a material having a relative dielectric constant of 10 or more in a 25 ° C. environment. Device.

[0020]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention relates to a processing method in a semiconductor manufacturing process by plasma processing, wherein a solid dielectric is provided on at least one of opposing surfaces of a pair of opposing electrodes under a pressure near atmospheric pressure. A discharge plasma processing method and apparatus for a circuit board, in which a discharge gas obtained by introducing a processing gas between a pair of opposed electrodes and applying a pulsed electric field between the electrodes is brought into contact with the circuit board. Hereinafter, the present invention will be described in detail.

Means for bringing the plasma into contact with the circuit board include, for example, (1) a method in which a circuit board is arranged in a discharge space of plasma generated between opposing electrodes, and the plasma is brought into contact with the circuit board; 2) There is a method (gun type) in which plasma generated between opposed electrodes is brought into contact with a circuit board disposed outside the discharge space so as to be guided.

As a specific method of the above (1), a circuit board is arranged between parallel plate type electrodes coated with a solid dielectric or the like and is brought into contact with plasma, and an upper electrode having a large number of holes is provided. Use, a method of treating with a shower-like plasma, a method of running a circuit board, providing a container-like solid dielectric having an outlet nozzle on one electrode, and spraying plasma from the nozzle onto a circuit board arranged on another electrode Method and the like.

As a specific method of the above (2),
The solid dielectric is extended to form a plasma induction nozzle, such as a method of spraying onto a circuit board placed outside the discharge space, such as a parallel plate electrode, a long nozzle, and a coaxial cylindrical electrode. And a combination of cylindrical nozzles. The material at the tip of the nozzle does not necessarily need to be a solid dielectric, and may be a metal or the like as long as the material is insulated from the electrodes.

The method of the above-mentioned method (1) in which a circuit board is arranged in a discharge space of plasma generated between opposed electrodes and plasma is brought into contact with the circuit board will be described with reference to the drawings. FIG. 1 is a diagram showing a cross section of an example of the discharge plasma processing apparatus of the present invention. In the figure, 1 is a power supply, 2 and 3 are electrodes, 4 is a solid dielectric container, 5 is a gas outlet, 7 is a processing gas inlet, 8 is a jig for connecting the electrodes, and 14 is a circuit board, respectively. .

In the present invention, a discharge plasma is generated inside the solid dielectric container 4 by applying an electric field between the electrode 2 and the electrode 3 while the processing gas is introduced into the solid dielectric container 4. Let it. The gas inside the solid dielectric container 4 is blown out from the gas blowout port 5 toward the circuit board 14, and the components of the processing gas excited into a plasma state come into contact with the surface of the circuit board 14, thereby processing the circuit board. Done. Therefore, the processing position of the circuit board can be changed by changing the relative position between the solid dielectric container 4 and the circuit board 5, and the processing of a large-area circuit board can be performed with a simple apparatus and a small amount of processing gas. In addition, partial designation processing can be performed.

The shape of the electrodes 2 and 3 is not particularly limited, and may be a curved shape such as a cylindrical shape or a spherical shape, in addition to the flat shape shown in the figure. The electrodes 2 and 3 may be made of a multi-component metal such as stainless steel or brass, or may be made of a pure metal such as copper or aluminum.

The distance from the center of the electrode 2 to the inside of the solid dielectric container 4 and the center of the gas outlet 5 to the electrode 3 depends on the thickness and material of the solid dielectric container 4 and the thickness of the circuit board 14. The thickness is appropriately determined depending on the thickness, the material, the magnitude of the applied voltage, and the like, but is preferably 0.5 to 30 mm. If it exceeds 30 mm, a high voltage is required, the discharge state is likely to shift to arc discharge, and uniform surface treatment becomes difficult.

The shape of the solid dielectric container 4 used in the present invention is not particularly limited, and examples thereof include a square, a cylinder, and a sphere.

Examples of the material of the solid dielectric container 4 include plastics such as polytetrafluoroethylene and polyethylene terephthalate, glass, metal oxides such as silicon dioxide, aluminum oxide, zirconium dioxide and titanium dioxide, and barium titanate. Double oxides and the like can be mentioned.

In particular, the relative dielectric constant under an environment of 25 ° C. is 1
The use of a solid dielectric material having a value of 0 or more can generate a high-density discharge plasma at a low voltage, thereby improving the processing efficiency. The upper limit of the relative dielectric constant is not particularly limited, but about 18,500 of actual materials are available and can be used in the present invention. Particularly preferred is a solid dielectric having a relative dielectric constant of 10 to 100. Specific examples of the solid dielectric having a relative dielectric constant of 10 or more include metal oxides such as zirconium dioxide and titanium dioxide, and double oxides such as barium titanate.

Titanate compounds are known as ferroelectrics. Different dielectric constant by the crystal structure, TiO ₂
It has a relative dielectric constant of about 80 in a single rutile crystal structure. B
The compound of TiO ₂ with an oxide of a metal such as a, Sr, Pb, Ca, Mg, Zr and the like has a relative dielectric constant of about 2,000 to 1
8,500, which can be changed depending on purity and crystallinity.

On the other hand, in the case of TiO ₂ alone, the composition in which the composition is changed by heating is so severe that the use environment is restricted. There are problems such as instability.
Therefore it is better to use contain a _Al 2 _{O 3} than TiO ₂ alone. A mixture of TiO ₂ and Al ₂ O ₃ is thermally practically stable and therefore suitable for practical use. Preferably,
5 to 50% by weight of titanium oxide, 50 to 9 of aluminum oxide
It is a metal oxide coating mixed at 5% by weight. If the proportion of aluminum oxide is less than 50% by weight, arc discharge is likely to occur, and if it exceeds 95% by weight, a high applied voltage is required to generate discharge plasma. Such a film has a relative dielectric constant of about 10 to 14 and a specific resistance of about 10 ¹⁰ and is suitable as a material for the solid dielectric container of the present invention.

When zirconium oxide alone is used, it has a relative dielectric constant of about 12, which is advantageous for generating discharge plasma at a low voltage. Normally, zirconium oxide is composed of 30 parts of yttrium oxide (Y ₂ O ₃ ), calcium carbonate (CaCO ₃ ), magnesium oxide (MgO) or the like.
The addition is performed in an amount of not more than% by weight to prevent expansion and shrinkage due to crystal transformation, thereby stabilizing it. These can be used in the present invention. The relative permittivity is determined by the type of the additive and the crystallinity of the metal oxide. In the present invention, those containing at least 70% by weight of zirconium oxide are preferred. For example, a zirconium oxide coating containing 4 to 20% by weight of yttrium oxide has a relative dielectric constant of 8 to 1%.
It is about 6, which is suitable as the solid dielectric of the present invention.

The solid dielectric container 4 preferably has the electrodes 2 provided thereon. FIGS. 2 and 3 are diagrams showing examples of the arrangement of the electrodes 2 and the solid dielectric container 4. Solid dielectric container 4
When the electrode 2 is rectangular, the electrode 2 may be provided on a surface other than the surface on which the gas outlet 5 is provided. The thickness of the surface of the solid dielectric container 4 on which the electrodes 2 are disposed is 0.03 to
30 mm is preferred. If it is less than 0.03 mm, dielectric breakdown may occur when a high voltage is applied, and arc discharge may occur.

The solid dielectric container 4 preferably has a gas inlet 7 and a gas outlet 5. The shape of the gas outlet 5 is not particularly limited, and examples thereof include a slit shape, a shape having many holes, and a protruding shape formed by the solid dielectric container. 4, 5 and 6 are diagrams illustrating examples of the gas outlet 5. Also,
The solid dielectric container of the present invention may have a gas storage capability in addition to the form having the gas inlet shown in FIG.

The jig 8 shown in FIG. 1 can change the distance between the electrode 3 and the gas outlet 5 freely.
With the jig 8, for example, when the circuit board 14 is a large-area object, the surface treatment can be performed by continuously moving the electrode 3 and the gas outlet 5 while keeping the distance between the electrode 3 and the gas outlet 5 constant.
In the case where only a part of the circuit board 14 is processed, a continuous surface treatment, a partial surface treatment, or the like can be performed by freely changing the interval between the electrode 3 and the upper outlet 5. However,
If the distance between the gas outlet 5 and the circuit board 14 is too long, the probability of contact with air increases and the processing efficiency decreases, so care must be taken.

The method (gun type) of bringing the plasma generated between the opposing electrodes into contact with the circuit board disposed outside the discharge space in the above method (2) will be described with reference to the drawings.

FIG. 7 shows an apparatus for spraying a plasma gas onto a base material using a cylindrical solid dielectric provided with a gas outlet, and a donut-shaped gas suction port provided around the gas outlet nozzle. It is a figure showing an example of a device and a device provided with a substrate conveyance mechanism. 1 is an electrode, 2 is an outer electrode, 3 is an inner electrode, 4 is a solid dielectric, 5 is a gas outlet, 7 is a processing gas inlet, 10 is an exhaust gas cylinder, 14 is a circuit board, and 41 to 43 are conveyor belts. Respectively. For example, the processing gas is introduced into the cylindrical solid dielectric container from the gas inlet 7 in the direction of the outline arrow, and the electrode 2 and the cylindrical solid dielectric disposed outside the cylindrical solid dielectric container are introduced. By applying a pulse electric field between the inner electrode 3 and the inside of the container, plasma is blown out from the gas blowout port 5 as plasma. On the other hand, the circuit board 14 includes three transporting steps in which the transporting belt 41 is first transported by the loading belt 41, then transported to the gas outlet by the processing belt 42, processed, and then transported out by the transporting belt 43. The treated gas is removed from the exhaust gas cylinder 10 together with the organic matter after the treatment, and does not reattach to the circuit board for contamination. The degree of processing can be changed by using a transport belt whose feed speed can be arbitrarily adjusted, and a cooling or heating mechanism can be added. Further, the nozzle body made of a cylindrical solid dielectric may be provided with a nozzle standby mechanism that performs a preliminary discharge after applying a voltage between the electrodes and waits outside the base material until the plasma is stabilized, if necessary. Alternatively, an XYZ moving mechanism may be provided to sweep over the circuit board.

FIG. 8 shows an apparatus for blowing plasma gas to a circuit board by a parallel plate-type long nozzle, an apparatus having a gas suction port provided around a gas outlet nozzle, and a circuit board transport mechanism. FIG. 2 is a diagram showing an example of a device that has been used. 1 is a power source, 2 and 3 are electrodes, 4 is a solid dielectric, 5
Denotes a gas outlet, 7 denotes a processing gas inlet, 9 denotes a discharge space, 10 denotes an exhaust gas cylinder, 14 denotes a circuit board, and 42 denotes a transport belt. For example, the processing gas is introduced into the discharge space 9 from the gas inlet 7 in the direction of the arrow, and is blown out from the gas outlet 5 as plasma by applying a pulse electric field between the electrode 2 and the electrode 3. . On the other hand, the circuit board 14 is carried to the gas outlet by the belt 42 and processed. The treated gas is removed from the exhaust gas cylinder 10 together with the organic matter after the treatment, and does not reattach to the circuit board and contaminate it. The degree of processing can be changed by using a transfer belt that can arbitrarily adjust the feed speed, and a cooling or heating mechanism can be added. Also, the nozzle body can be
After applying a voltage between the electrodes, a pre-discharge is performed, and a nozzle standby mechanism that waits outside the circuit board until the plasma is stabilized can be provided. Alternatively, an XYZ moving mechanism can be provided to allow the nozzle to move on the circuit board. It can also be swept.

In the processing of the circuit board of the present invention, any processing can be performed for each purpose by selecting an inert gas such as oxygen, hydrogen, nitrogen or argon as a processing gas to be supplied into the solid dielectric. Yes, it can clean organic contaminants on circuit boards, remove resist, improve the adhesion of organic films, reduce metal oxides, and modify surfaces.

For example, in the manufacture of a circuit board, if the surface to be subjected to wire bonding is contaminated with an organic substance such as an epoxy resin, the adhesiveness is extremely reduced. However, this is to be cleaned by performing discharge plasma treatment. And the wire bonding strength is improved.

The surface of the metal terminal to be soldered is
It is usually covered with native oxide, but it can be exposed to a clean metal surface by performing a plasma reduction process in a discharge plasma process in the presence of hydrogen gas to improve the adhesion with solder and bonding wires. it can.

Further, a resin plate for a circuit board, for example, B
The surface of the GA resin plate or the like is subjected to a discharge plasma treatment in the presence of oxygen gas to remove organic contaminants on the surface and to improve the adhesion to the sealing resin by hydrophilization by surface oxidation.

When a gas other than the inert gas is used as the processing gas from the viewpoint of economy and safety, the processing is preferably performed in an atmosphere in which the processing gas is diluted with the inert gas. Examples of the inert gas include rare gases such as helium, neon, argon, and xenon, and nitrogen gas. These may be used alone or in combination of two or more. Conventionally, treatment has been performed in the presence of helium under a pressure near atmospheric pressure. However, according to the method of applying a pulsed electric field of the present invention, argon and nitrogen are inexpensive compared to helium. Stable processing in gas is possible.

The mixing ratio between the processing gas and the inert gas is appropriately determined depending on the type of the gas used. When a pulsed electric field is applied, the treatment can be performed in an atmosphere having an arbitrary mixing ratio. Therefore, the mixing ratio may be determined from the viewpoint of economy and safety. In the case of not relying on the pulsed electric field, if the concentration of the processing gas is too high, it becomes difficult to generate discharge plasma, so that the concentration of the processing gas is the same as that in the mixed gas of the processing gas and the inert gas. It is preferably from 0.01 to 10% by volume, more preferably from 0.1 to 5% by volume.

In the present invention, the processing gas is continuously discharged from the gas outlet 5 provided in the solid dielectric container 4. In the case of using a plurality of types of processing gases in combination or diluting the processing gas with an inert gas, in the apparatus of FIG. 1, each gas is a general gas flow controller not shown in the figure. Are supplied through the gas inlet 7 into the solid dielectric container 4, and the mixed gas is discharged from the gas outlet 5.

The supply amount and the flow rate of the processing gas (when diluted with an inert gas and used, indicate a mixed gas of the processing gas and the inert gas; the same applies hereinafter). Cross section, circuit board 14 and gas outlet 5
The distance is appropriately determined depending on the distance between them. For example, when the cross-sectional area of the gas outlet 5 is 100 mm ² , the supply amount of the processing gas is preferably a flow rate of 5 SLM,
The flow velocity of the processing gas was 830 mm /
sec is preferred. When the supply amount of the processing gas is increased, the flow velocity of the processing gas is increased in proportion thereto, and the time required for the surface treatment is reduced.

The pressure conditions for performing the discharge plasma processing method of the present invention are not particularly limited, and processing under a pressure near atmospheric pressure is possible. The pressure under atmospheric pressure is as follows.
Refers to a pressure of 333 × 10 ^{4 to} 10.664 × 10 ⁴ Pa. 9.331 Easy pressure adjustment and simple device
The range is preferably from × 10 ^{4 to} 10.297 × 10 ⁴ Pa.

The time required for the discharge plasma treatment is appropriately determined depending on the purpose of the treatment, the magnitude of the applied voltage, the material of the circuit board, the composition of the mixed gas, and the like.

Further, the processing can be performed in a state where the circuit board is heated or cooled, or the processing can be performed in combination with a chemical pre-processing or post-processing.

Hereinafter, the pulse electric field of the present invention will be described. FIG. 9 shows an example of the pulse voltage waveform. The waveforms (a) and (b) are of the impulse type, the waveform (c) is of the pulse type, and the waveform (d) is of the modulation type. Although FIG. 7 shows an example in which voltage application is repeated positive and negative, a pulse of a type in which a voltage is applied to either the positive or negative polarity side may be used. Further, a pulse electric field on which a direct current is superimposed may be applied. The waveform of the pulse electric field in the present invention is not limited to the above-mentioned waveforms, and may be modulated using pulses having different pulse shapes, rise times, and frequencies. Such modulation is suitable for performing high-speed continuous surface treatment.

The rise time and fall time of the pulse electric field are 40 ns to 100 μs. 100μ
If s is exceeded, the discharge state is likely to shift to an arc and becomes unstable, making it difficult to realize a stable discharge state. In addition, the shorter the rise time and the fall time, the more efficiently the gas is ionized at the time of plasma generation.
If it is less than ns, it is difficult to realize on equipment. More preferably 50
ns to 5 μs. Here, the rise time refers to the time during which the voltage change is continuously positive, and the fall time refers to the time during which the voltage change is continuously negative.

The electric field strength of the pulse electric field is 1 to 100 k.
V / cm. If it is less than 1 kV / cm, it takes too much time for the treatment, and if it exceeds 100 kV / cm, arc discharge is likely to occur.

The frequency of the pulse electric field is 1 kHz to 1
Preferably, it is 00 kHz. If it is less than 1 kHz, it takes too much time for the treatment, and if it exceeds 100 kHz, arc discharge is likely to occur. Further, the time during which one pulse electric field is applied is preferably 1 μs to 1000 μs. If it is less than 1 μs, the discharge becomes unstable, and if it exceeds 1000 μs, it tends to shift to arc discharge. More preferably, it is 3 μs to 200 μs. The time during which one pulse electric field is applied is shown in FIG. 7 as an example. In the pulse electric field composed of repetition of ON and OFF, one pulse continuous O
Say N hours.

[0055]

The present invention will be described in more detail with reference to the following examples, but the present invention is not limited to these examples.

Example 1 A 110 mm (W) × 5 mm (D) × 50 mm (H) copper electrode was coated with an alumina-based dielectric having a relative dielectric constant of 12 by 1 mm.
The plasma generated between the thick parallel sprayed parallel plate electrodes is
Using a plasma generator shown in FIG. 8 which blows the gas from the slit-shaped gas outlet nozzle 5 with a gap of mm toward the base material, a 100 × 100 mm copper plate for a circuit board was subjected to plasma processing under the following conditions.

Plasma processing conditions Processing gas: mixed gas of oxygen 0.5 SLM + argon 9.5 SLM Discharge conditions: waveform a, rise / fall time 10 μm
s, peak value 4.5 kV, frequency 10 KHz, processing time 1
Second

As a result of analyzing the surface condition of the copper plate before and after the treatment by ESCA, the carbon component on the surface was reduced from 62 atom% to 4 atom%.
8 atom%. In addition, the static contact angle of the copper plate surface with water before and after the treatment was measured with a semi-automatic contact angle meter (CA-X150, manufactured by Kyowa Interface Science Co., Ltd.) by dropping 2 μL of water droplets. As a result, the contact angle was reduced from 105 degrees before the treatment to 20 degrees (wet and spread state) after the treatment. This indicated that organic contaminants on the surface were removed.

Example 2 A plasma treatment was performed on a copper plate for a circuit board in the same manner as in Example 1 except that the treatment time was 3 seconds. As a result of analyzing the surface state of the copper plate before and after the treatment by ESCA, the carbon component on the surface was reduced from 62 atom% to 15 atom%. The static contact angle of the copper plate surface with water before and after the treatment was 2
A water droplet of μL was dropped and measured with a semi-automatic contact angle meter (CA-X150, manufactured by Kyowa Interface Science Co., Ltd.). As a result, from the contact angle of 105 degrees before the treatment to 10 degrees after the treatment (wet and spread state)
Down to This indicated that organic contaminants on the surface were removed.

Example 3 A plasma treatment was performed on a copper plate for a circuit board in the same manner as in Example 1 except that the treatment time was changed to 30 seconds. As a result of analyzing the surface state of the copper plate before and after the treatment by ESCA, the carbon component on the surface was reduced from 62 atom% to 5 atom%. The static contact angle of the copper plate surface with water before and after the treatment was 2
A water droplet of μL was dropped and measured with a semi-automatic contact angle meter (CA-X150, manufactured by Kyowa Interface Science Co., Ltd.). As a result, the contact angle was reduced from 105 degrees before the treatment to 5 degrees (wet spread state) after the treatment. This indicated that organic contaminants on the surface were removed.

Example 4 A 250 mm (W) × 5 mm (D) × 50 mm (H) copper electrode was coated with an alumina-based dielectric having a relative dielectric constant of 12 by 1 mm.
The plasma generated between the thick parallel sprayed parallel plate electrodes is
Using the plasma generator shown in FIG. 8 in which the gas is blown from the slit-shaped gas outlet nozzle 5 at intervals of mm toward the base material,
As substrate to be treated, via diameter 100μm, pitch 250μ
Plasma processing was performed under the following plasma processing conditions using an A4 size glass epoxy substrate having a hole of m.

Plasma processing conditions Processing gas: mixed gas of 30% by volume of oxygen + 2% by volume of CF ₄ + 68% by volume of argon Discharge conditions: Waveform a, rise / fall time 10 μm
s, 20kV _PP , frequency 10KHz

The processing time was changed to 20 seconds, and the amount of residual smear (the amount of residue in the via hole) was measured at each time.
Fig. 1 shows the result of plotting the residual smear rate against the processing time.
0 is shown. With the processing time, the residual smear rate decreases,
The smear was completely removed in seconds.

Comparative Example 1 As a processing gas, 1% by volume of oxygen + 0.5% by volume of CF ₄ +
The processing was performed in the same manner as in Example 4 except that a mixed gas of 98.5% by volume of helium was used, and a voltage having a sin waveform having a frequency of 12.2 kHz was applied to the electrodes. It took 10 minutes for the residual smear ratio to become 20%, and the residual smear ratio could not be reduced to 0% even if the treatment was continued.

Comparative Example 2 Under 1.333 × 10 Pa, a frequency of 12.2 kHz was applied to the electrode.
Processing was performed in the same manner as in Example 4 except that a voltage having a sin waveform of z was applied. It took 10 minutes for the residual smear ratio to reach 0%.

Example 5 The following discharge plasma processing apparatus as shown in FIG. 1 having the gas outlet shown in FIG.
A 100 × 100 mm BGA for a circuit board was subjected to plasma processing under the following conditions.

Discharge plasma processing apparatus: 110 mm (W)
× 5mm (D) × 50mm (H) solid dielectric container 4
Is a 1 mm-thick alumina-based dielectric having a relative dielectric constant of 12 sprayed on the inner surface of a copper container.
A slit-shaped gas outlet 5 mm × 1 mm long is provided, and a 100 × 30 × 1 mm copper electrode 2 is arranged near the gas outlet 5. Also, the other 10
A copper electrode 3 of 0 × 30 × 1 mm is provided on the back surface of the sample 14,
The electrode 2 is disposed so as to maintain a distance of 10 mm.

Plasma processing conditions Processing gas: mixed gas of oxygen 1 SLM + argon 9 SLM Discharge conditions: waveform a, rise / fall time 10 μm
s, peak value 7.2 kV, frequency 10 KHz, processing time 5
Second

The surface condition of the BGA for a circuit board before and after the treatment was analyzed by ESCA.
om% to 10 atom%. In addition, the static contact angle of water on the surface of the circuit board BGA before and after the treatment was 2
A water droplet of μL was dropped and measured with a semi-automatic contact angle meter (CA-X150, manufactured by Kyowa Interface Science Co., Ltd.). As a result, it was found that the contact angle before the treatment decreased from 105 ° to 0 ° (wet-spread state) after the treatment, indicating that the surface became hydrophilic.

Next, the BGA for a circuit board before and after the treatment was sealed with a molding resin for a semiconductor, and the adhesion strength between the board and the sealing resin was measured as a value of the shear peel strength. As a result, the adhesion strength before the treatment was improved from 8 MPa to 15 MPa. This indicates that the organic contaminants on the surface were removed by the discharge plasma treatment, and that the adhesion was improved by hydrophilization by surface oxidation.

Example 6 A 100 × 100 mm circuit copper plate was subjected to plasma processing under the following conditions by using the same discharge plasma processing apparatus as in Example 4 while moving. Plasma processing conditions Processing gas: mixed gas of 0.5 SLM of hydrogen + 9.5 SLM of argon Discharge conditions: waveform a, rise / fall time 10 μm
s, crest value 5.5 kV, frequency 10 kHz, processing time 5
Second

As a result of analyzing the surface condition of the copper plate before and after the treatment by ESCA, the oxygen component on the surface was reduced from 40 atom% to 1 atom%.
It was reduced to 5 atom%, indicating that the reduction reaction had proceeded. Next, a gold wire was soldered to the copper plate before and after the treatment, and the wire tensile strength by soldering was measured by a tensile test using a spring balance. As a result, the tensile strength before the treatment was increased from 9 g to 11 g.

Comparative Example 3 A sin at a frequency of 12.2 kHz was used instead of the pulse electric field.
Processing was performed in the same manner as in Example 1 except that a voltage having a waveform was applied. However, the voltage required for generating a discharge required 10 kV or more, and the discharge state was arc discharge. Holes.

Comparative Example 4 Instead of the pulse electric field, a sin having a frequency of 12.2 kHz was used.
Processing was performed in the same manner as in Example 2 except that a waveform voltage was applied. Since the object to be processed was a metal, the discharge starting voltage was about 7 kV, but an arc discharge also occurred and the copper substrate surface melted.

[0075]

The discharge plasma processing method of the present invention has the above-described structure, and can perform continuous surface treatment and partial surface treatment of a circuit board under atmospheric pressure with a simple apparatus and a small amount of processing. It can be performed more uniformly with gas. Further, since the surface treatment step can be easily performed in-line, the surface of the circuit board can be easily cleaned, and the adhesiveness and printability can be easily improved. Further, the discharge plasma treatment method of the present invention can perform a stable treatment at a high level under atmospheric pressure conditions by generating a discharge plasma by applying a specific pulsed electric field, and can achieve a stable discharge. The range of voltage conditions and the like that can realize the state is wide. Further, according to the specific pulse electric field according to the present invention, high-density discharge plasma can be generated, which is advantageous in high-speed continuous processing.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view showing an example of a discharge plasma processing apparatus of the present invention.

FIG. 2 is an example of an arrangement of a solid dielectric container and one electrode of a discharge plasma processing apparatus.

FIG. 3 is an example of an arrangement of a solid dielectric container and one electrode of a discharge plasma processing apparatus.

FIG. 4 is an example of a gas outlet of a discharge plasma processing apparatus.

FIG. 5 is an example of a gas outlet of a discharge plasma processing apparatus.

FIG. 6 is an example of a gas outlet of a discharge plasma processing apparatus.

FIG. 7 is an example of a discharge plasma processing apparatus.

FIG. 8 is an example of a discharge plasma processing apparatus.

FIG. 9 is a diagram of a voltage waveform showing an example of a pulsed electric field according to the present invention.

FIG. 10 is a diagram showing the results of Example 4.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Power supply (high voltage pulse power supply) 2, 3 electrodes 4 Solid dielectric container 5 Gas outlet 7 Gas inlet 8 Jig 9 Discharge space 10 Exhaust gas exhaust tube 14 Circuit board 41, 42, 43 Transport belt

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 4G075 AA30 BC10 CA14 CA15 CA47 DA02 DA05 EA01 EB42 EB43 EC21 FB02 FB04 FB06 FB12 FC11 FC15 5E343 AA02 AA12 BB08 BB24 BB61 EE08 FF23 GG11 GG20 5F004 AA18BA04 BA04 EH13

Claims (10)

[Claims] At least one opposing surface of a pair of opposing electrodes is provided with a solid dielectric under a pressure near the atmospheric pressure,
A discharge plasma treatment method for a circuit board, wherein plasma obtained by introducing a processing gas between the pair of opposed electrodes and applying a pulsed electric field is brought into contact with the circuit board. 2. The pulse-like electric field has a pulse rise and / or fall time of 100 μs or less and an electric field intensity of 1 to 250 kV / cm.
3. The discharge plasma processing method according to item 1. 3. A pulse-like electric field having a frequency of 0.5 to 1
The method of claim 1 or 2, wherein the pulse duration is 00 kHz and the pulse duration is 1 to 1000 μs. 4. The discharge plasma processing according to claim 1, wherein plasma generated between the opposed electrodes is guided from the gas outlet nozzle toward the substrate. Method. 5. A solid dielectric container provided with a gas outlet on one electrode, another electrode provided opposite the gas outlet, and between the gas outlet and another electrode. A discharge plasma processing method in which a circuit board is arranged and a processing gas is continuously discharged from the gas outlet, and a discharge plasma is generated by applying an electric field between the one electrode and the other electrode. The pulse-shaped electric field applied between the electrodes has a rise time and a fall time of 100 μs or less, and an electric field intensity of 1 to 100 kV.
/ Cm, a discharge plasma treatment method. 6. The discharge plasma processing method according to claim 1, wherein the circuit board is a resin plate for the circuit board. 7. A pair of opposing electrodes having a solid dielectric disposed on at least one opposing surface, a mechanism for introducing a processing gas between the pair of opposing electrodes, and a mechanism for applying a pulsed electric field between the electrodes. And a mechanism for contacting a plasma obtained by the pulsed electric field with a circuit board. 8. The method according to claim 7, wherein the mechanism for bringing the plasma into contact with the circuit board is configured to guide the plasma generated between the opposed electrodes from the gas outlet nozzle toward the substrate. Discharge plasma processing equipment. 9. An electrode provided with a solid dielectric container provided with a gas outlet and another electrode provided opposite to the gas outlet, and processing is performed from the gas outlet. The discharge gas is continuously discharged, and a rise time and a fall time between the one electrode and the other electrode are 100 μs or less, and an electric field intensity is 1 to 100 kV / cm. A discharge plasma processing apparatus for processing, wherein a pulsed electric field is applied. 10. The discharge plasma processing apparatus according to claim 9, wherein the solid dielectric container is made of a material having a relative dielectric constant of 10 or more in a 25 ° C. environment.