JPH05102665A - Vapor phase reduction apparatus for internal layer plate - Google Patents

Abstract

PURPOSE:To manufacture a multiplaye printed wiring board with high productivity and without causing pollution by a method wherein a net driven by a roll or an endless porous belt is employed as a conveying means and entrance and exit parts are respectively composed of gaps which are larger than the thickness of an internal layer plate and are located in front and rear parts and inert gas supply parts which are located in approximately central parts between the gaps. CONSTITUTION:When an operation is started, nonoxidizing gas is supplied to a reduction chamber 2 and the air in the reduction chamber 2 and entrance shielding parts 11, 12, 31 and 32 is completely replaced by the nonoxidizing gas. The supply of the nonoxidizing gas through the nonoxidizing gas inlets 12 and 32 of the entrance shielding parts 11, 12, 31 and 32 is started and the supply of nonoxidizing gas containing reducing gas to the reduction chamber is started. A circulating recycle apparatus and the like are operated properly to obtain the predetermined concentration and temperature of the reducing gas. An endless porous belt which is provided along the route of a supply table 1, the reduction chamber 2 and a take out table 3 is moved at a predetermined speed. With this constitution, multilayer printed wiring boards can automatically and continuously be processed under a relatively low temperature and, further, hazardous waste is not produced practically.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is a novel vapor-phase reduction apparatus for continuously performing vapor-phase reduction treatment on inner layer plates one by one. Fine copper oxide is formed on the copper foil surface of the inner layer plate for a multilayer printed wiring board. It is preferably used for producing a multilayer board in which the "pink ring" is substantially eliminated by forming a concave-convex film and subjecting it to a gas phase reduction for multilayer lamination molding.

[0002]

2. Description of the Related Art Multi-layer printed wiring boards are mainly manufactured by (a). Mass lamination method and (b). Pin lamination method, which are printed wiring boards for inner layers (hereinafter referred to as "inner layer boards"). It is manufactured, and the inner layer board, prepreg and copper foil or single-sided copper clad laminate is combined to form a multi-layered laminate to form a multilayer board made of copper foil on both sides, which is manufactured by processes such as through hole processing and outer layer printed wiring processing. ing.

In this multilayer printed board, a method of using a copper foil whose both surfaces are preliminarily roughened in order to improve the multilayer adhesive strength of the inner layer board; after forming a printed wiring network for the inner layer ,. A method of forming a copper oxide fine concavo-convex film on the surface of a copper foil with an oxidizing treatment aqueous solution ,. A method of treating the copper foil surface with a silane coupling agent or an organic titanate coupling agent is known. Conventionally, from the viewpoint of adhesiveness and economical efficiency, usually, after forming a printed wiring network for the inner layer on a copper clad laminate having a glossy surface, it is treated with an oxidizing alkaline aqueous solution to give a brown or black copper oxide fine uneven film. What is formed is used.

However, this copper oxide fine uneven film, particularly cupric oxide, is easily dissolved in an acidic aqueous solution such as hydrochloric acid or sulfuric acid, and is brittle. For this reason, small holes are made in the laminated multilayer board, and during the through-hole plating step or electroless plating or the subsequent electroplating step, the copper oxide fine uneven film exposed on the hole wall is sequentially turned inward. A so-called "halo" or "pink ring" is generated which is attacked by the acid solution, and there is a drawback that causes deterioration of the reliability of the printed wiring board such as insulation.

As a method for preventing the halo or pink ring which occurs when this brown or black copper oxide fine uneven film is used. There is disclosed a method of changing the copper oxide fine uneven film on the surface of the copper foil obtained in the above step to a cuprous oxide or metallic copper by reducing it with an aqueous solution of a reducing agent (JP-A-56-153797, etc.). These methods can achieve a practical level of adhesive strength, but require a new liquid-phase reduction treatment step, and the adhesive strength is lower than that of a brown or black copper oxide fine uneven film. Therefore, it is necessary to make the reducing conditions extremely strict to obtain an adhesive strength that can be put to practical use. Further, there is a variation in the effect of preventing the "pink ring" from occurring, and a new problem of waste liquid treatment of the reducing agent aqueous solution occurs.

[0006]

DISCLOSURE OF THE INVENTION The inventors of the present invention have performed a reduction treatment on a copper oxide fine uneven film that has been subjected to a brown or black oxidation treatment, and there is no variation in the effect of preventing "pink rings", and there is little decrease in adhesive strength. There was no such problem, and a thorough study was made on a method that does not cause a new problem of waste liquid treatment.

As a result, the vapor phase reduction method was completed, and Japanese Patent Application No. 2-
Patent applications were filed as 199210, 2-277884, 2-277885, and 2-284203. However, the industrial practice of these inventions generally requires the handling of reducing gases, which are relatively unfamiliar in the art. From this point, it is preferable to use a continuous automated device from the viewpoint of safety without air mixing into the reduction chamber (system) and gas leakage into the atmosphere, and not only safety but also productivity. As a result of examination from the viewpoint, the present invention has been completed.

[0008]

That is, the present invention is to form a brown or black copper oxide fine uneven film by chemically oxidizing a copper foil surface of an inner layer board for a multilayer printed wiring board on which a printed wiring network is formed. After that, a vapor phase batch reduction apparatus for the inner layer plate that reduces the copper oxide fine irregularity film in a reducing gas presence atmosphere under substantially normal pressure, wherein the inner layer plate supply table (1) is non-oxidizing. Inlet shielding part (11) by gas, reducing gas supply device, inert gas supply or processing circulation device, reduction chamber (2) connecting waste gas processing device if necessary, outlet shielding by non-oxidizing gas Part (31), which is provided in series with the take-out table (3) for the reduced inner layer plate, and the inner layer plate is supplied to the feeding table (1) and the reducing chamber (2).
, A vapor phase reduction apparatus for the inner layer plate, which is provided with a transfer means (5) for sequentially transferring to the unloading table (3).

In the present invention, the transfer means (5)
Is an endless belt having a mesh or perforations driven by a roll, and the entrance and exit shields (11, 31) are
Each of them is composed of a gap larger than the thickness of the inner layer plate in the front and rear and an inert gas supply part to the gap approximately in the center thereof, and further, the shielding part (31) and the extraction table (3) This is a vapor phase reduction apparatus for an inner layer plate, further comprising a post-treatment chamber (4) provided therebetween.

The structure of the present invention will be described below. The vapor-phase reduction apparatus of the present invention is generally an apparatus for continuously putting the inner layer plates into the gas-phase reduction chamber one by one, performing reduction treatment, and taking out, and the holding time of the inner layer plates in the reduction chamber is relatively short. It is a case of reducing in time.

First, the reducing chamber (2) in the apparatus of the present invention is, of course, connected to a reducing gas supply device, an inert gas supply device or a processing device for circulation and reuse, and more preferably, a reduction device. In order to further shorten the time, a part for spraying the reducing gas present gas to the inner layer plate surface and a waste gas treatment device are provided. Further, a shutoff unit for shutting off the atmosphere in the reducing chamber and the external atmosphere, and a control device for controlling the continuous loading and unloading of the inner layer plate are provided.

Specific examples of the transfer means (5) include a belt-like material driven by rolls and a large number of rolls. In addition, in the method of forming copper oxide fine irregularities, when using a method of using a frame or holes for fixing, it is preferable to use these as they are in the vapor phase reduction apparatus of the present invention, fixed to the inside of the frame There is also a method of fixing the inner layer plate or the inner layer plate having holes for fixing, etc. to a transfer tool provided on both sides and transferring.

In the case of a belt-shaped material, the inner layer plate does not substantially move back and forth, left and right on the belt-shaped material, so that there is little possibility of damaging the copper oxide fine concavo-convex film except when it is charged, which is preferable. However, on the lower surface side that comes into contact with the belt-shaped material, the chance of contact with the reducing gas is less than that on the upper surface, and the reduction rates of the upper and lower surfaces are likely to differ. For this reason, the belt-like material preferably has a net-like material or a large number of holes, grooves, and the like having a size that allows the reducing gas to easily flow.

In the case of rolls, it is essential that the surface of the rolls is made of a soft material so as not to damage the copper oxide fine uneven film, and when the rolls are moved, the difference in rotation speed between the rolls is required. If the reduction is insufficient, the copper oxide fine concavo-convex film is damaged. Therefore, the rotation speed (surface speed) between the rolls to the intermediate portion of the reduction chamber is set to be exactly the same.

When the inner layer plate fixed to the inside of the frame is fixed to the transfer tools provided on both sides and transferred, means such as belt, rope or chain, roll or gear, screw and the like can be mentioned. Then, a suitable one is selected depending on the shape of the frame. Further, when using the holes provided in the inner layer plate or the edge portion of the inner layer plate, the inner layer plate is fixed to a fixing jig for transferring the inner layer plate, and the fixing jig for transfer is supplied to the supply table (1).
→ Non-oxidizing gas inlet shielding part (11) → Reduction chamber (2) → Non-oxidizing gas outlet shielding part (31) → Reduced inner layer plate take-out stand (3) → Supply stand (1) By cycling to.
Further, in this case, it is more preferable to transfer the paper in a vertically standing state.

The inlet and outlet shielding means (11, 31) using a non-oxidizing gas for shutting off the atmosphere of the reducing chamber and the external atmosphere are
Non-oxidizing gas introduction part, which is typically slightly higher than normal pressure
(12) and a gas flow curtain provided with a flat plate-like gap (slit) on both sides thereof through which the inner layer plate can pass.

The slit and the non-oxidizing gas introduction part (12)
As a seal function equivalent to that, use a roll or belt with a surface that does not damage the copper oxide fine uneven film, and rotate or move at the same speed as the transfer speed; extremely lightweight roll or lightweight A flexible strip curtain should be provided at the end of the strip so that it can be easily floated due to the pressure difference of the inert gas introduced. Use a roll that is in contact with or sealed only in the vicinity, and blow out an inert gas from this porous; the surface layer part of the roll is several mm above atmospheric pressure.
It should be formed by an air bag or the like pressurized to about Hg;

Next, the inner layer board of the present invention reduced by the above apparatus is a printed wiring board used as an inner layer of a multilayer printed wiring board. As this inner layer board, a base material, a matrix resin, etc., except that the inner layer printed wiring network copper foil surface is subjected to an oxidation treatment for interlayer adhesion to form black or brown copper oxide fine irregularities Conventionally known ones can be used and are not particularly limited.

A method of making a printed wiring network copper foil surface into a brown or black copper oxide fine uneven film--a fine uneven film of copper oxide having submicron-order needles, wedges, ono, anchors, etc .-- is known. Usually, after the copper foil surface of the inner layer plate is polished or washed, pre-etching (soft etching, chemical polishing) is performed with an aqueous solution of copper chloride or ammonium persulfate, and an oxidizing treatment is performed with an alkaline oxidizing aqueous solution.

Among the known methods for forming a brown or black copper oxide fine concavo-convex film, a specific method which has been put into practical use is the obtained copper oxide fine concavo-convex film as it is, or these are reduced in a liquid phase. It is a condition under which a good adhesive force is obtained when treated and multilayer-laminated.

However, according to the present invention, since this copper oxide fine unevenness film is used after vapor phase reduction which has never been used before, the copper oxide fine unevenness film or the surface reduced in the liquid phase has the best adhesive strength. Things are not always the best after reduction. As a copper oxide fine uneven film, the unevenness is large compared to the conventional one and the adhesive strength is poor because it is brittle, or when copper oxide is partly dropped off when laminating the laminate set, it adheres to the non-printed wiring part. Even if a trouble that causes contamination is generated, if the metal copper is reduced, the cause of such trouble disappears, so that it can be used as one showing higher adhesive strength.

However, in the present invention, since these inner layer plates are placed as they are on the belt or the like and transferred,
It is necessary to avoid that the fine uneven surface is scratched and becomes a defect in the charging. Therefore, when using the inner layer plate on which the copper oxide fine concavo-convex film that easily causes defects such as scratches is used, as described above, a method is used in which a frame or the like is used and the device or the like does not come into contact with the printed wiring network surface. To use.

Further, according to the present invention, since reduction is carried out by a relatively short time reduction treatment, when the reduction rate is insufficient, before the reduction, for example, in the latter half of the washing after the completion of the oxidation treatment, other time By applying the platinum group catalyst to the copper oxide fine irregularities, the reduction temperature can be lowered or the speed can be increased. Further, in the present invention, the copper oxide of the inner layer plate which forms the copper oxide fine irregularities is reduced by the vapor phase reduction apparatus of the present invention, and preferably the fine irregularities substantially composed of metallic copper are formed.

The gas phase reduction of the present invention is carried out in an atmosphere containing a reducing gas. The atmosphere in which a reducing gas is present is an atmosphere in which a reducing gas such as hydrogen or carbon monoxide or any other gasifiable reducing compound such as hydrazine gas is present, and is usually diluted with a non-oxidizing gas. However, it is a gas phase atmosphere that enables operation at normal pressure. The temperature, time, etc. of the gas phase reduction can be appropriately selected depending on the type and amount (absolute pressure or partial pressure) of the reducing gas used, the presence or absence of the white metal catalyst.

Generally, when a gas having a small reducing power at room temperature such as hydrogen is used, the temperature is in the range of 80 ° C to 300 ° C,
In particular, the temperature is 100 to 160 ° C, and the upper limit temperature is particularly selected from the range of temperature considering the dimensional stability of the inner layer plate to be treated, and the treatment time is appropriately selected from the range of 1 minute to 24 hours, preferably 10 minutes to 3 hours. Therefore, it is preferable to add a white metal catalyst to accelerate the reaction at a lower temperature.

In the case of a compound having a reducing ability even at room temperature, such as hydrazine, it is usually in the range of 160 ° C. to room temperature, preferably 140 ° C. to 60 ° C., particularly 120 ° C. to 80 ° C., and the treatment time.
It is appropriately selected from the range of 30 seconds to 3 hours, preferably 1 to 60 minutes, and particularly 2 to 30 minutes. In this case, too, reduction can be carried out at high speed by adding a platinum catalyst.

Particularly when hydrazine gas is used, even if the atmosphere itself is in the gas phase, hydrazine gas is condensed on the copper oxide fine uneven film or water produced by the reduction reaction does not vaporize to form a liquid film. Then, the reduction reaction may proceed in the liquid film, and in the case of the high-speed or low-temperature reduction reaction, the liquid film formation is likely to occur. However, when the liquid film is formed, the copper element is moved, and the fine unevenness of the copper oxide fine uneven film is destroyed, resulting in a reducing film having no adhesive force.

Therefore, the partial pressure of the hydrazine gas is 50% or less, preferably 20%, of the saturated vapor pressure at the processing temperature.
Below, especially below 5%, and the partial pressure of water vapor is
50% or less, preferably 30% or less, particularly 10% or less of the saturated vapor pressure at the treatment temperature is set to a low value, and vaporization is promoted so that water produced in the reduction reaction does not condense to form a liquid phase. It is preferable to perform air blowing and stirring for this purpose.

The wind speed in this blast stirring is 0.01 m
/ sec or more, preferably 0.1 m / sec or more, and it is particularly preferable that the airflow velocity on the surface of the inner layer plate is in this range or more. Further, particularly when hydrazine is used, since a large amount of non-oxidizing gas is used as a medium, it is particularly preferable to recycle it if necessary and recycle it. In order to
Particularly, it is preferable to use it so that the partial pressure of water vapor in the gas is 10 mmHg or less.

More preferably, the fine concavo-convex film reduced to metallic copper has finer concavo-convex as compared with the copper oxide fine concavo-convex film. Therefore, particularly fine irregularities are likely to be oxidized due to their huge specific surface area, and are likely to be deteriorated in adhesive strength by being transformed into copper oxide during storage.

Therefore, in order to prevent oxidation and facilitate storage, it is preferable to carry out rust prevention treatment. As this method, there is a method of treating with an ordinary rust preventive aqueous solution immediately after taking out and drying, but in the present invention, gradual oxidation without using a liquid (= method of forming an extremely thin and dense oxide film on the surface) ) Is particularly preferred. Gradual oxidation can usually be easily carried out by treating with an oxygen partial pressure of several mmHg and at a temperature of about 120 ° C. or higher. This can be done by allowing a trace amount of oxygen to be mixed in before the temperature drops.

As described above, the inner layer plate which has been subjected to the vapor phase reduction by the apparatus of the present invention is usually used as it is for the multi-layer lamination molding to be a multi-layer shield plate having copper foil on both sides, and then punched and polished. After being subjected to desmear treatment, electroless plating, electrolytic plating, etc., a halo-free multilayer printed wiring board is obtained by forming printed wiring patterns on both surfaces.

[0033]

EXAMPLES Examples will be described below with reference to the accompanying drawings. FIG. 1 is a cross-sectional view of the gas phase reduction apparatus of the present invention, and FIG. 2 is a plan view thereof. Further, FIG. 3 is a cross-sectional view of a gas phase reduction apparatus having a post-treatment portion added. 1, 2, and 3
The reference symbols are, respectively, 1: supply stage, 2: reduction chamber, 3: extraction stage, 4: post-treatment chamber, 11: inlet shielding part, 12: non-oxidizing gas introduction part, 21: gas outlet, 31: outlet. Shielding part, 32: non-oxidizing gas introduction part, 41: simple seal. Note that FIG.
In Nos. 3 to 3, peripheral equipments such as a reducing gas supply device, an inert gas supply device, a circulation reuse treatment device, an exhaust treatment device, and a control device are omitted.

In FIGS. 1 and 2, first, at the start of operation, the reducing chamber (2) is supplied with a non-oxidizing gas and
(2) The inlet / outlet shielding part (11, 12, 31, 32) is completely replaced with non-oxidizing gas. Next, a non-oxidizing gas is introduced from the non-oxidizing gas introducing part (12, 32) of the entrance / exit shielding part (11, 12, 31, 32), and a reducing gas exists in the reducing chamber (2). Of the recycle gas is started and the circulating reuse device, etc. is appropriately operated to reach the predetermined reducing gas concentration and temperature.
(2) → Move the perforated endless belt provided on the take-out base (3) at a predetermined speed.

Form a copper oxide fine uneven film on the supply table (1)
Place the dried inner layer plate, the inner layer plate is the supply table (1) → reduction chamber
(2) The transfer is carried out in the order of the take-out table (3) by the porous endless belt, the predetermined reduction is performed, and the product is taken out to the outside.

Further, FIG. 3 shows a post-processing chamber (4) provided between the outlet shielding part (31) and the unloading table (3) shown in FIGS. In 4), the reduction-treated inner layer plate is configured to positively oxidize a small amount of copper on the uneven surface of fine copper to improve storage stability. It is also possible to prevent excessive oxidation of the copper surface by cooling in the presence of a slight amount of oxygen instead of gradual oxidation.

The main cause of the "pink ring" being confirmed even when the inner layer plate reduced to copper by the vapor phase reduction of the present invention is confirmed is the storage state of the laminated material and the multilayered lamination molding condition. , Drilling conditions, and others.

[0038]

As described above, from the detailed description and the examples, the gas phase reduction apparatus of the present invention is extremely simple and continuously and automatically processes. The gas phase reduction apparatus of the present invention is
It is operated at substantially atmospheric pressure and can be carried out at a relatively low temperature of about 120 ° C, and practically no harmful waste is generated.

Furthermore, the amount of the reducing gas is extremely small, and there is no need to store it as a gas. For example, it is extremely easy to supply the required amount while generating the required amount on the spot by using a commercially available hydrogen generator by decomposing ammonia. Further, in the case of hydrazine, it is possible to operate at a gas partial pressure far below the explosion limit, and it is possible to use conditions under which no explosion or the like will occur even if a leak occurs.

Moreover, the multilayer printed board using the vapor-phase-reduced inner layer board of the present invention has a brown or black copper oxide as the plating solution in the through-hole plating step for electrically connecting the printed wirings of the multilayer board. The occurrence of "halos", which tend to melt and melt and cause defects such as electrical shorts, is greatly reduced or eliminated altogether. As described above, according to the vapor phase batch reducing apparatus for an inner layer board of the present invention, a highly reliable multilayer printed wiring board can be produced with good productivity and pollution-free, and has an extremely high industrial significance. is there.

[0041]

[Brief description of drawings]

FIG. 1 is a cross-sectional view illustrating the transfer of an inner layer plate of a vapor phase reduction apparatus according to the present invention.

FIG. 2 is a plan view for explaining the inner layer plate transfer of the vapor phase reduction apparatus of the present invention.

FIG. 3 is a sectional view for explaining the inner layer plate transfer of the vapor phase reduction apparatus of the present invention.

[Explanation of symbols]

The reference numerals are, respectively, 1: supply stage, 2: reduction chamber, 3: extraction stage, 4: post-treatment chamber, 11: inlet shielding part, 12: non-oxidizing gas introduction part, 21: gas outlet, 31: outlet shielding Part, 32: non-oxidizing gas introduction part, 41: simple seal.

Claims (4)

[Claims] 1. A copper foil surface of an inner layer board for a multilayer printed wiring board on which a printed wiring network is formed is chemically oxidized to form a brown or black copper oxide fine concavo-convex film, and then in a reducing gas atmosphere. A vapor phase reduction apparatus for an inner layer plate, which substantially reduces the copper oxide fine uneven film under normal pressure, comprising a supply base for the inner layer plate.
(1), inlet shielding part (11) with non-oxidizing gas, reducing gas supply device, inert gas supply or processing circulation device, reduction chamber (2) connected with waste gas processing device if desired, non-oxidizing An outlet shielding part (31) with a volatile gas, and an extraction table (3) for the reduced inner layer plate are provided in series, and the inner layer plate is supplied to the supply table (1),
Vapor phase reduction device for inner layer plate, which is provided with a reduction chamber (2) and a transfer means (5) for sequentially transferring to the extraction table (3) 2. The vapor phase reduction apparatus for an inner layer plate according to claim 1, wherein said transfer means (5) is a net driven by rolls or a perforated endless belt. 3. The inlet and outlet shields (11, 31) are each composed of a front and rear gap, which is larger than the thickness of the inner layer plate, and an inert gas supply part to the gap at substantially the center thereof. The vapor phase reduction apparatus for an inner layer plate according to claim 1. 4. Between the shielding part (31) and the extraction table (3),
The vapor phase reduction apparatus for an inner layer plate according to claim 1, further comprising a post-treatment chamber (4).