JPH0485989A - Manufacture of multilayer printed board - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention is a method for manufacturing a multilayer printed wiring board, which is characterized by vapor phase reduction treatment of the copper foil surface of the printed wiring board serving as an intermediate layer (inner layer). Preferably, the surface shape of the oxidized film on the surface of the copper foil is not substantially changed to form a metallic copper surface, and a "halo" or " This substantially eliminates the pink ring j phenomenon.

[Conventional technology and its problems]

In a multilayer printed board, a method of improving the multilayer adhesion of an inner layer board on which a printed wiring network is formed as an intermediate layer is to use a copper foil that has been textured on both sides in advance; After forming the copper foil, there are two known methods: (1) forming a copper oxide film on the surface of the copper foil using an oxidation treatment aqueous solution, and (2) treating the copper foil surface with a silane coupling agent or an organic titanate coupling agent. Conventionally, from the viewpoint of adhesion and economy, after forming a printed wiring network for the inner layer on a copper-clad laminate with a glossy surface, it is treated with an oxidizing alkaline aqueous solution to form a brown or black copper oxide film. is used.

However, this copper oxide film, especially cupric oxide, is easily dissolved in acidic aqueous solutions such as hydrochloric acid and sulfuric acid. For this reason, when making small holes in a laminated multilayer board and performing a through-hole plating process, electroless plating, or subsequent electrolytic plating process,
A so-called "halo" or "pink ring" occurs when copper oxide is sequentially dissolved by acidic liquid from the copper oxide film exposed on the hole wall, which is a defect that causes a decrease in the reliability of printed wiring boards such as insulation. was there.

As a method to prevent the halo or pink ring that occurs when this brown or black copper oxide film is used, recently, the copper oxide film on the surface of the copper foil obtained in steps A method of changing to a copper oxide film or a copper film (Japanese Unexamined Patent Publication No. 153797/1983, etc.) has been disclosed. These methods can achieve adhesion strength at a level that can be put to practical use, but they require a new liquid phase reduction treatment process, and the adhesive strength is lower than that of brown or black copper oxide films, so they are not practical. In order to obtain adhesive strength that can withstand corrosion, the reducing conditions must be extremely strict. Furthermore, "Hello"
There were variations in the effectiveness of preventing the occurrence of , and a new problem occurred in the treatment of waste liquid of the aqueous reducing agent solution.

[Means to solve the problem]

The present inventors have found that by reducing a copper oxide film that has been oxidized to brown or black, not only is there no variation in the prevention effect of "r halo", but also there is no or small decrease in adhesive strength, and
We worked hard to find a method for wastewater treatment that would not create new problems.

As a result, the present inventor proposed that the gas phase reduction method be a research topic. However, all conventional printed wiring board manufacturing processes involve processes using water or organic solvent solutions. In the field of printed wiring boards, there are no examples of using reducing gases, and it is well known that these gases are easily combustible and may cause explosions in some cases. Therefore, it was extremely difficult to decide to conduct research and development on this subject, which deals with such gases.

However, fortunately, as a result of small-scale preliminary research, it was confirmed that this gas phase reduction method has the potential to exhibit extremely excellent performance, and based on this, research and development efforts for its practical application were conducted. , we have completed the present invention.

That is, in the method of manufacturing a multilayer printed wiring board, the present invention involves chemically oxidizing the copper foil surface of an inner layer board on which a printed wiring network used as an intermediate layer is formed to form a brown or black copper oxide surface, and then reducing the copper foil surface to form a brown or black copper oxide surface. A method for manufacturing a multilayer printed wiring board characterized by using an inner layer board treated in an atmosphere containing a toxic gas, and characterized in that the reducing gas is hydrogen, carbon monoxide, or a mixed gas thereof. This is a method for manufacturing a multilayer printed wiring board.

The present invention also provides a method for manufacturing a multilayer printed wiring board, in which the copper foil surface of an inner layer board on which a printed wiring network is formed as an intermediate layer is chemically oxidized to form a brown or black copper oxide surface, thereby producing a multilayered laminated board. This is a method for producing a multilayer printed wiring board characterized in that after forming, through-hole drilling is performed in an atmosphere containing a reducing gas before electroless plating, and the reducing gas is hydrogen, This is a method for manufacturing a multilayer printed wiring board characterized in that carbon monoxide or a mixed gas thereof is used.

The configuration of the present invention will be explained below.

The multilayer printed wiring board of the present invention is an inner layer board on which an inner layer printed wiring network used for the above-mentioned intermediate layer is formed, and after chemically oxidizing the copper foil surface to form a black or brown copper oxide surface, In addition to using a plate that has been dried and treated in a reducing gas atmosphere under the phase, or using a multilayer plate obtained by multilayer lamination molding with holes and then reducing it in the gas phase, Inner laminates used for molding, prepregs used for multilayer adhesion, prepregs for forming outer layers, laminated materials such as copper foil or single-sided copper-clad laminates, and methods of laminated molding are based on conventionally known concepts. Any of these can be used, and is not particularly limited.

Such laminated materials include E glass, S glass, D glass,
Various glass woven fabrics such as quartz glass, inorganic woven materials such as alumina paper; fully aromatic acid polyamide, polyimide, fluororesin, polyphenylene sulfide, polyether ether ketone, polyether imide, liquid crystal polyester resin, and other super heat-resistant materials woven fabrics made of polyimide, fluororesin, polyphenylene sulfide, polyetheretherketone, polyetherimide, liquid crystal polyester resin, and other super heat-resistant resins; films or sheets made of the above inorganic fibers and super heat-resistant resins A woven fabric using a composite yarn using fibers produced by the manufacturer; using a woven fabric such as an appropriate combination of the above as a reinforcing base material, it can be used as a reinforcing base material to produce bisphenol A type, noholac type, halogenated bisphenol A type, or halogenated novolac type. , and other trifunctional or higher polyfunctional epoxy compounds; cyanate resins such as cyanate resins, cyanate ester-epoxy resins, cyanate ester-maleimide-epoxy resins; cyanate ester resins such as bismaleimide; Maleimide resins whose main components are polyfunctional maleimides and polyfunctional amines such as bis(4-aminophenyl)methane; furthermore, heat-resistant thermoplastic resins and compositions of thermoplastic resins and thermosetting resins. prepreg made of resin, etc., copper foil such as electrolytic copper foil or rolled copper foil, double-sided or single-sided copper-clad laminate made by laminating and molding copper foil and prepreg, and one-sided or double-sided copper-clad laminate. An example of this is an inner layer printed wiring board (inner layer board) in which an inner layer printed wiring network is formed. Examples of the lamination molding method include conventional hot plate press, hot plate vacuum press, autoclave molding, and continuous press.

The method of forming a brown or black copper oxide film on the inner layer plate of the present invention is known. Usually, after polishing and cleaning the copper foil surface of the inner layer plate, pre-etching (softening) is performed with an aqueous solution such as copper chloride or ammonium persulfate. etching, chemical polishing)
After that, it is treated with an alkaline oxidizing aqueous solution. Here, the alkaline oxidizing aqueous solution and treatment conditions are specifically exemplified below, but are not limited thereto, and known methods can be used.

■, Sodium hydroxide (NaOH (15g/1)
) / Sodium hypochlorite (NaC1 (L (31g #
))/sodium phosphate (15g#'), 70-1
00°C, 0.5-10 minutes.

■, Copper sulfate (50g, Q')/sodium chloride (20
0g#! ), 40-80°C for 13-15 minutes.

■, Acetic acid (20g#') / Ammonium chloride (20g
#') / Copper acetate (10g #), 30-80°C11
~10 minutes.

■, Copper acetate (10g#)/Copper sulfate (24g/l)/
Barium sulfide (24g#t!)/Ammonium chloride (
24g#! ), 40-50°C, 1-10 minutes.

■, Copper sulfate (25g#!) / Nickel sulfate (25g#!)
')/Potassium chlorate (25g#'), 70-9
0℃, 1-10 minutes.

■ Potassium persulfate (20g/V)/sodium hydroxide 50g#) at 50-80°C for 11-3 minutes.

Among the above-mentioned methods for forming brown or black copper oxide films, the specific methods that have been put into practical use are those that are suitable for forming the obtained oxidized film itself in a multilayered layered manner, or those that are suitable for forming these into a liquid phase. These conditions are suitable for reduction treatment. However, since the present invention uses these after being subjected to gas phase reduction treatment, the one with the best adhesive strength as an oxidized film or a product obtained by reducing it in a liquid phase is necessarily the best after reduction treatment. It's not a thing.

In other words, although the copper surface before and after the reduction treatment of the present invention appears to have a slightly narrow uneven pattern in micrographs and SEM photographs, it is virtually impossible to distinguish between them within the range of observation. There is no substantial change other than shrinkage caused by the loss of oxygen from copper oxide. Therefore, although the external shape of the oxidized film is substantially maintained, the crystal itself shrinks and the degree of unevenness is reduced, and the copper forming the unevenness is stronger than copper oxide. has been significantly improved. Therefore,
As an oxidized film, it has a higher degree of unevenness than conventional films.
Even in cases where the adhesive is somewhat weak and easily causes contamination, the present invention can be applied as a treatment method that further improves the adhesive strength.

After washing and cleaning the inner layer plate treated with brown or black as described above, use the inner layer plate subjected to the gas phase reduction treatment of the present invention, or after multilayer lamination molding, holes are made to remove at least the vicinity of the holes. The copper oxide film is reduced so that the r halo J is extremely reduced or substantially absent.

In the inner layer plate or the multilayer plate of the present invention, the reducing gas presence atmosphere in which the multilayer plate is reduced includes reducing gases such as hydrogen and carbon oxide, and other reducing compounds that can be gasified.
This is a gas phase atmosphere diluted with a non-oxidizing gas as appropriate.

First, the method of supplying these reducing gases is not particularly limited; for example, the method of supplying the gas described in (1) above in a cylinder, the method of supplying gas by electrolysis or catalytic pyrolysis, and other methods. can be mentioned.

In particular, the field in which the present invention is implemented is a field that is unfamiliar with handling gases, as described above, and when safety is taken into account, the less combustible or explosive gas is used, the better. Particularly preferred is a method in which the required amount is produced and supplied by a thermal decomposition method or the like. Further, the necessary and sufficient amount of reducing gas required in the present invention is, for example, about 18 Nrrf' when the average thickness of the copper oxide treated film is 2 Am and the treated area is 5.000 rrl'. The amount can be more than adequately handled by a very small-scale reducing gas generator.

Here, compounds that can be used to generate reducing gases such as hydrogen and carbon monoxide through catalytic thermal decomposition include:
Lower alcohols such as methanol, ethanol, prononol and butanol; Aldehydes and their derivatives such as formaldehyde, paraformaldehyde and trioxane; Lower carboxylic acids and their esters such as formic acid, formic acid esters and acetic acid; Ammonia, hydrazine; Methylamine, Examples include ethylamine, diethylamine, methylhydrazine, other nitrogen-containing lower amines, hydrazine derivatives, metal hydrides and organometallic compounds such as calcium hydride, boron hydride, and methylboron, and these are particularly limited in the use of the present invention. It is something that cannot be done. Among these, lower alcohols, lower carboxylic acids, ammonia and the like are preferred from the viewpoint of ease of handling, safety, presence or absence of waste, price, etc.

Naturally, it is also possible to supply a gas of a reducing compound.

Next, the reduction treatment temperature is usually in the range of 130°C to 300°C, preferably 140°C to 240°C, especially 150 to 190°C.
℃, especially the upper limit temperature is selected from a temperature range that takes into consideration the dimensional stability of the inner layer plate or multilayer plate to be treated, and the treatment time is from 1 minute to 24 minutes, preferably from 10 minutes to 12 hours. , is selected as appropriate.

The reduction treatment temperature and time are selected based on the desired reduction state of the copper on the oxidized copper foil surface, ranging from a completely reduced state (matte copper foil color = light brown) to a large, intermediate state of reduction. It is possible to select between the states in which the cupric oxide of the portion is reduced to cuprous oxide (=cuprous oxide, brown to gray state). This reduction state is selected when using a treatment method such as black oxide treatment that is currently in practical use, with emphasis on adhesive strength, and when 110- or pink ring phenomenon may occur to some extent. It tends to be preferable to select conditions that stop the reduction in the state of cuprous oxide, and in order to avoid the 110- or pink ring phenomenon, the state is reduced to copper. Note that these are based on the oxidation treatment method that is currently in practical use, and as mentioned above, when using a copper oxide film with a higher degree of unevenness, it is necessary to completely reduce it to copper and improve it. There is a basis for the fact that it is possible to develop a certain adhesive force.

As described above, the inner layer plate subjected to the vapor phase reduction treatment of the present invention is used as it is in multilayer lamination molding to form a multilayer shield plate with copper foil on both sides, and then subjected to drilling, polishing, desmear treatment,
After electroless plating, electrolytic plating, etc., a multilayer printed wiring board is formed by forming printed wiring patterns on both surfaces. In addition, a multilayer printed wiring board in which the gas phase reduction treatment of the present invention is performed after the hole forming process is similarly carried out through the subsequent printed wiring pattern forming process.

Here, when applying the reduction treatment of the present invention to the inner layer plate,
The conditions are substantially the same as the drying conditions except that the atmosphere is a reducing gas atmosphere. From this, in the present invention, when the copper foil surface of the inner layer plate is oxidized and then subsequently subjected to reduction treatment, the oxidation treatment step is followed by an essential step that also serves as a drying step. From that point of view, it is an extremely rational process.

In addition, in the gas phase reduction treatment of the present invention, there are no problems with waste liquid treatment as in liquid phase reduction treatment, and for example, when using a toxic gas such as -carbon oxide, there is no problem with the waste liquid treatment from the reduction treatment equipment. Guide the waste gas to the catalytic combustion device,
It is only necessary to convert unreacted reducing gas into carbon dioxide or water depending on the raw material gas.

Note that the reduction treatment method for the inner layer plate, which is one of the manufacturing methods of the present invention, is usually... -Liquid phase oxidation treatment for multilayer adhesive-
This step is the step of multilayer lamination molding. Also,
The main equipment of the reduction treatment equipment that implements this process is the reduction treatment chamber and the reducing gas supply device, and its auxiliary equipment includes the waste gas treatment device, the supply of the inner layer plate to the reduction treatment chamber, and the It consists of a take-out device, a control device to control these, etc.

In particular, since the department that implements the present invention is a department that is not used to handling reducing gases, there is no risk of fire or explosion due to leakage of reducing gas or mixing of oxygen into the reducing gas atmosphere. It is essential to use a device for this purpose, and it is desirable to use a combination of vacuum suction and inert gas replacement to separate the air from the outside air, or to use other means.

〔Example〕

The present invention will be explained below with reference to Examples.

Example 1 Thickness: 0.8 mm, copper foil thickness: 70. After removing about half of both sides of the double-sided copper-clad glass epoxy laminate using a known etching method, the copper foil surface was subjected to black oxidation treatment using a conventionally known NaOH method.
(15g/f!)/Sodium hypochlorite (31g
/l)/9 with an aqueous solution of sodium phosphate (15g/f)
The treatment was carried out at 0° C. for 5 minutes and washed with water to obtain a black oxidized inner layer plate.

The black oxidized inner layer plate was placed in a dryer capable of vacuum suction, and after drying at normal pressure at a temperature of 130 ° C. for 10 minutes, the inside of the dryer was vacuumed and suctioned while increasing the reduction treatment temperature listed in Table 1. After nitrogen gas was introduced and vacuum suction was performed again, hydrogen gas was introduced to perform reduction treatment. Thereafter, the inside of the dryer was vacuumed and nitrogen gas was introduced, and then the reduced inner layer plate was taken out from the dryer.

This reduction treatment temperature, time, hue change of the black oxidation treatment film,
In addition, the reduction state at that time was tested and analyzed. These results are listed in Table 1.

In addition, using the inner layer plates in various reduction states obtained above, three sheets of glass epoxy prepreg (resin content 52%, thickness 0.1 mm) were layered on both sides, and then electrolytic copper foil with a thickness of 18 mm was layered at a temperature of 175°C. After lamination molding was carried out for 2 hours at a pressure of 40 kg/car to form a 4-layer board, it was cooled.

The adhesion strength of copper foil was measured for some of these.

In addition, for the rest, hole diameter 0.4 mmφ, 80,000 r, p
.

1.000 pieces under m2.20p/rotation condition, 2.54
Drill holes at intervals of mm, immerse the drilled 4-layer board in a 4N HCI aqueous solution for 5 minutes, and observe the halo around the hole where the inner layer is located for an arbitrary 1/4 of the holes (125 pieces). The length of the largest one was also measured.

The results are shown in Table 1.

Table 1 Example 2 After removing about half of both sides of a double-sided copper-clad glass epoxy laminate with a thickness of 0.8 mm and a copper foil thickness of 70 m using a known etching method, the black oxidation treatment of the copper foil surface was performed using NaOH (15 g/I). Treated with an aqueous solution of sodium hypochlorite (31g#')/sodium phosphate (15g/f) at 90°C for 5 minutes, washed with water to form a black oxidized inner layer plate, and heated at 130°C at normal pressure. The inner layer plate was obtained by drying at ℃ for 30 minutes.

In addition, using the inner layer plate obtained above, three sheets of glass epoxy prepreg (resin content 52%, thickness 0.1 mm) and 18 mm thick electrolytic copper foil were layered on both sides of the inner layer plate at a temperature of 175°C.
A four-layer plate was formed by lamination molding at a pressure of 40 kg/ad for 2 hours, and then cooled.

Using this double-sided copper-clad multilayer board, the hole diameter was 0.4 mmφ and 80,000 r.
, p, m, , 1,000 holes were drilled at intervals of 2.54 mm under the conditions of 20 IA/rotation.

This perforation was measured for the halo using a multilayer shield plate, before and after desmear treatment, after performing vapor phase reduction treatment under the same conditions as in Example 1, and after performing ordinary copper through-hole plating.

As a result, no haloing was found.

In addition, the hue of the inner layer copper foil surface will change when subjected to long-term high-temperature treatment.
It had turned a slightly brownish color.

[Operation and effects of the invention]

From the above detailed description and examples, the multilayer printed board manufactured by the manufacturing method of the present invention is produced by dissolving brown or black copper oxide in the plating solution during the through-hole plating process for establishing electrical continuity between the printed wiring of the multilayer board. The occurrence of "halos," which tend to cause defects such as electrical short circuits, is significantly reduced or completely eliminated.

In addition, the processing time for the inner layer plate does not impose a new burden on the process because it can be done in conjunction with the conventional drying process, and since it is a gas phase process, it is extremely easy to scale up. It is something.

Furthermore, since the reducing gas of the present invention can be obtained by catalytic pyrolysis, there is no need to stock large amounts of combustible or even explosive gas (which is generated by the reduction process). The waste that occurs is also a gas, and unreacted components can be removed extremely easily by catalytic combustion.
Essentially non-polluting.

Furthermore, and most importantly, in the gas-phase reduction treatment of the present invention, the preferred surface roughness of the oxidized surface for adhesion can be determined completely by X-ray analysis, at least when the surface is observed using a microscope or SEM. Even if the surface has been reduced to a certain extent, it has been confirmed that its appearance is essentially the same as the oxidized surface used for adhesion, except that it appears to be slightly thinner. This proves that it is extremely excellent in terms of physical properties such as adhesive strength.

As described above, according to the method for manufacturing a multilayer board of the present invention, a multilayer printed wiring board with excellent reliability can be manufactured with high productivity (and without pollution), and has extremely high industrial significance.

Patent applicant: Mitsubishi Gas Chemical Co., Ltd.

Claims (1)

[Claims] 1. In a method for manufacturing a multilayer printed wiring board, after chemically oxidizing the copper foil surface of an inner layer board on which a printed wiring network used as an intermediate layer is formed to form a brown or black copper oxide surface,
A method for manufacturing a multilayer printed wiring board, characterized by using an inner layer board processed in an atmosphere in the presence of a reducing gas. 2. The method for producing a multilayer printed wiring board according to claim 1, wherein the reducing gas is hydrogen, carbon monoxide, or a mixture thereof. 3 In a method for manufacturing a multilayer printed wiring board, the copper foil surface of the inner layer board on which the printed wiring network is formed as an intermediate layer is chemically oxidized to form a brown or black copper oxide surface, and after multilayer lamination molding, a through-layer is formed. A method for producing a multilayer printed wiring board, which comprises processing in an atmosphere in the presence of a reducing gas between after hole drilling and before electroless plating. 4. The method for producing a multilayer printed wiring board according to claim 3, wherein the reducing gas is hydrogen, carbon monoxide, or a mixture thereof.