JPH04334093A - Manufacture of multilayered wiring board - Google Patents

Abstract

PURPOSE:To obtain the manufacturing method of a multilayered wiring board wherein imperfect bonding of a wiring layer and an adhesive insulating layer of a circuit board for an inner layer can be prevented, and treatment agent in the course of manufacturing is hard to be left on the interface of the above layers. CONSTITUTION:When a multilayered wiring board is manufactured by forming an oxide film 2 composed of CuO and Cu2O on the surface by oxidizing a wiring layer 1 of a circuit board for an inner layer which circuit board has the wiring layer 1 of a copper foil, and by laminating a plurality of said circuit boards via adhesive insulating layers, oxidizing is performed under the condition that the ratio Cu2O/CuO in the oxide film becomes higher than or equal to 80%. When the percentage of Cu2O having large acid resistance is increased, the acid resistance of the oxide film 2 is also increased, so that the oxide film 2 of the wiring layer 1 is hard to be dissolved, when oxidizing is suitably performed in the course of manufacturing a multilayered wiring board. Thereby haloing phenomenon wherein metal copper of the wiring layer 2 is partially exposed can be restrained.

Description

[Detailed description of the invention]

0001

[Field of Industrial Application] The present invention relates to a multilayer wiring board comprising a plurality of inner layer circuit boards laminated with adhesive insulating layers interposed therebetween, and a method for manufacturing the same. A multilayer wiring board capable of preventing poor adhesion between a foil wiring layer and the adhesive insulating layer, and in which an appropriate treatment agent applied during the manufacturing process is difficult to remain at the interface between the wiring layer and the adhesive insulating layer, and the same. Regarding the manufacturing method.

0002

[Prior Art] This type of multilayer wiring board is, for example, shown in FIGS.
It is manufactured through various steps as shown in FIG. To explain the outline below, as shown in FIG. 4, a plurality of inner layer circuit boards a having wiring layers formed of copper foil are laminated together with an outer layer copper foil a1 via an adhesive insulating layer (prepreg) b. After integrating the parts and drilling a through hole c as shown in FIG. 5 using an appropriate drilling means,
In order to cover the inner wall surface of the through hole c with copper foil, a through hole plating process with copper is performed to form a plating layer d as shown in FIG. 6 on the surface of the laminate and the inner wall surface of the through hole c, respectively.

Next, a photoresist layer e is formed in a pattern on the surface of this plating layer d, excluding a part around the through hole c and the wiring layer formation area (see FIG. 7), and a photoresist layer e is formed from this photoresist layer e. After forming a copper/solder plating layer f on the exposed portion (see FIG. 8) and removing the photoresist layer e, the copper/solder plating layer f is used as a mask to remove the plating as shown in FIG. A method is adopted in which layers d and the like are removed by etching, and a solder resist layer g is further formed on these surfaces to produce a multilayer wiring board h as shown in FIG.

By the way, when the plurality of inner layer circuit boards a are laminated via adhesive insulating layers (prepreg) b, the wiring layer provided on the inner layer circuit board a is made of copper foil with a smooth surface. As a result, the adhesive strength with the adhesive insulating layer b is insufficient, resulting in a drawback that the wiring layer and the adhesive insulating layer b tend to separate over time.

For this reason, in the past, (A) in FIG.
~ As shown in (B), the surface of the wiring layer i made of copper foil is
For example, 15-25g of sodium hydroxide (NaOH)
An acicular crystal oxide film j consisting of CuO and Cu2O is formed by oxidation treatment with an alkaline sodium chlorite aqueous solution dissolved at a concentration of about /l, and the surface of the wiring layer i is roughened to form an adhesive insulator. A method has been adopted to improve the adhesive strength with layer b.

[0006]

[Problem to be solved by the invention] By adopting such a method, the overall adhesive strength between the wiring layer i and the adhesive insulating layer b can be improved; Although the film j is resistant to alkaline solutions, it is relatively easily dissolved in acids, so it is exposed from the inner wall surface of the through hole c during the manufacturing process of the multilayer wiring board, as shown in FIG. 12(A). When the laminated surface comes into contact with an acidic treatment agent (for example, during the above-mentioned through-hole plating treatment, when the layer is treated with an acidic palladium/tin aqueous solution of hydrochloric acid to impart catalytic properties to chemical copper plating)
As shown in FIG. 12(B), the oxide film j at the contact portion is dissolved by acid to expose the metal copper of the wiring layer i, and the pink ring r is connected to the through hole c as shown in FIG.
A phenomenon called "haloing", which is formed along the periphery of the disk, sometimes occurs.

When this phenomenon occurs, a gap s is formed at the interface between the wiring layer i on the inner wall surface of the through hole c and the adhesive insulating layer b, as shown in FIG. There is a problem that deterioration occurs and the treatment agent tends to peel over time, and the processing agent tends to remain in the voids s, resulting in a problem that the reliability as a multilayer wiring board is significantly lowered.

Against this technical background, the inventors of the present invention have conducted intensive research on a method for imparting acid resistance to the oxide film j, and have found that the reason why the oxide film j does not exhibit acid resistance in the conventional method is due to the presence of acid. This is because a large amount of CuO, which is easily dissolved, exists in the oxide film j, and it is possible to impart acid resistance to the oxide film j by lowering the ratio of CuO and increasing the ratio of Cu2O, which has relatively acid resistance. Heading This is what led to the completion of the present invention.

Incidentally, Cu2 in the oxide film in the conventional method
Ratio of O to CuO (Cu2O/CuO×100
) is about 30 to 40%, and the amount of haloing (indicated by the width of the ring indicated by the distance L from the periphery of the through hole c with a diameter of 0.35 mm in Fig. 13) is on average. 130 to 150 μm or more and several hundred μm
Sometimes it became.

[0010] Therefore, an object of the present invention is to improve the adhesion between the copper foil wiring layer provided on the inner layer circuit board and the adhesive insulating layer by reducing the amount of haloing generated to 100 μm or less. It is an object of the present invention to provide a multilayer wiring board which can prevent defects and which prevents a suitable treatment agent applied during the manufacturing process from remaining on the interface between the wiring layer and the adhesive insulating layer, and a method for manufacturing the same.

[0011]

[Means for Solving the Problems] In other words, the invention according to claim 1 is such that an inner layer circuit board having a wiring layer made of copper foil on the surface of which an oxide film of CuO and Cu2O is formed is connected via an adhesive insulating layer. The present invention is based on a multilayer wiring board formed by laminating a plurality of layers, and is characterized in that the ratio of Cu2O/CuO in the oxide film is set to 80% or more. , assumes a multilayer wiring board consisting of a plurality of inner layer circuit boards laminated with adhesive insulating layers interposed therebetween, each having a wiring layer made of copper foil with an oxide film of CuO and Cu2O formed on the surface. Cu2O/CuO
The ratio of 80% or more and the thickness of the oxide film is 0.4 μm ~
It is characterized by being set to 0.8 μm.

Further, the invention according to claim 3 is characterized in that the wiring layer of the inner layer circuit board having the wiring layer formed of copper foil is oxidized to form an oxide film consisting of CuO and Cu2O on the surface thereof. , and based on the method of manufacturing a multilayer wiring board by laminating a plurality of these oxidized inner layer circuit boards with adhesive insulating layers interposed therebetween, Cu2O in the oxide film is
The invention is characterized in that the oxidation treatment is performed under conditions such that the ratio of /CuO is 80% or more.On the other hand, the invention according to claim 4 provides an inner layer circuit board having a wiring layer formed of copper foil. The wiring layer is oxidized and CuO is deposited on its surface.
The method is based on the method of manufacturing a multilayer wiring board by forming an oxide film consisting of The oxidation treatment is performed under conditions such that the ratio of Cu2O/CuO is 80% or more and the thickness of the oxide film is 0.4 μm to 0.8 μm.

As the treatment liquid for oxidizing the wiring layer in such technical means, alkaline sodium chlorite aqueous solution, alkaline potassium persulfate aqueous solution, etc. can be used as is, as in the past, and the treatment method Similarly to the conventional method, the inner layer circuit board, which has been previously degreased, is immersed in the above-mentioned treatment liquid.

In this case, Cu2O/
The processing temperature was set from the conventional 90-95°C to a lower 70-85°C so that the CuO ratio was 80% or more, and the processing time was set from the conventional 4 minutes 30 seconds to a shorter time. It is desirable to do so. Moreover, it can be easily achieved by setting the alkaline concentration of the alkaline sodium chlorite aqueous solution or alkaline potassium persulfate aqueous solution higher than conventional ones.

[0015] The reason why the Cu2O/CuO ratio becomes 80% or more when oxidation treatment is carried out under these conditions is not yet fully elucidated, but when the above conditions are set, "Cu2O→ CuO” reaction is suppressed and CuO
We speculate that this is due to a decrease in the ratio of

[0016] Furthermore, an oxide film having a higher proportion of Cu2O may be formed by a two-step process. That is,
A first oxidation treatment is performed using an alkaline oxidation treatment solution such as an alkaline sodium chlorite aqueous solution or an alkaline potassium persulfate aqueous solution to form an oxide film of Cu2O and CuO on the surface of the copper foil. In this case, Cu2O crystals tend to grow from the surface of the oxide film to the inside, whereas CuO crystals tend to grow from the inside of the oxide film to the surface.
The surface side of the oxide film tends to be covered with CuO crystals, and many Cu2O crystals exist inside the oxide film. Therefore,
By etching the surface of this oxide film to remove a large amount of CuO crystals present on the surface side, the ratio of Cu2O in the oxide film can be increased. Next, by performing a second oxidation treatment using an alkaline oxidation treatment liquid whose alkaline concentration is higher than that of the first alkaline oxidation treatment liquid, it becomes possible to further increase the ratio of Cu2O in the oxide film. It goes without saying that both the first oxidation treatment and the second oxidation treatment may be performed using an alkaline oxidation treatment solution with a high alkali concentration. In addition, the etching conditions for the oxide film formed in the first oxidation treatment include acidic solutions that can dissolve this oxide film, such as oxoacids such as dilute sulfuric acid, basic acids such as dilute hydrochloric acid, hydrohalic acid, and ammonia. Water etc. can be applied. In addition, the processing time for this etching is such that the thickness of the oxide film is approximately 0.2 μm, preferably 0.1 μm.
For example, about ten to 30 seconds until about 5 to 0.20 μm remains.

Next, there is no particular restriction on the thickness of the oxide film, and it can be set to an appropriate value of about 1.0 μm, as in the prior art. However, as the film thickness increases, the exposed area at the end of the film also increases, making it more susceptible to side etching when it comes into contact with an acidic treatment agent, so it is preferable to set the film thinner. The inventions according to claims 2 and 4 have been made from such a viewpoint, and the thickness of the oxide film is set to 0.4 μm to 0.8 μm.
By setting the thickness to a certain level, it is less susceptible to the side etching and has the advantage of further suppressing the haloing phenomenon.

[0018] The manufacturing process of the multilayer wiring board after laminating the inner layer circuit boards that have been subjected to the oxidation treatment described above is optional, and for example, it may be manufactured through the same process as the conventional method described above. Other steps may also be performed. Further, the inner layer circuit board to which the present invention is applied may be one having a wiring layer only on one side or one having wiring layers on both sides.

[0019]

[Operation] According to the invention according to claim 1, the ratio of Cu2O/CuO in the oxide film formed on the surface of the wiring layer is set to 80% or more. According to the above, since the wiring layer is oxidized under conditions such that the ratio of Cu2O/CuO in the oxide film is 80% or more, the acid resistance of the oxide film increases as the proportion of Cu2O, which has high acid resistance, increases. As the properties are improved, the oxide film of the wiring layer becomes difficult to dissolve even if acid treatment is performed appropriately during the manufacturing process of the multilayer wiring board, and the haloing phenomenon in which the metallic copper of the wiring layer is partially exposed is suppressed. becomes possible.

On the other hand, according to the invention according to claim 2, Cu2O/C in the oxide film formed on the surface of the wiring layer
The ratio of uO is 80% and the thickness of the oxide film is 0.4 μm ~
According to the invention according to claim 4, the ratio of Cu2O/CuO in the oxide film is 80% or more and the thickness of the oxide film is smaller than that in the conventional method. Since the oxidation treatment is performed under the conditions of 0.4 μm to 0.8 μm, the acid resistance of the oxide film is improved, and the thickness of the oxide film is also thin, making it difficult for side etching to occur.
Even if appropriate acid treatment is performed during the manufacturing process of the multilayer wiring board, the oxide film of the wiring layer becomes more difficult to dissolve, and the haloing phenomenon in which the metallic copper of the wiring layer is partially exposed can be more reliably suppressed. It becomes possible.

[0021]

Embodiments Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

[Example 1] First, a glass/epoxy copper laminate (340 mm x 51
0 mm x 1.6 mm), the copper foil was patterned by photo-etching in the same manner as before to manufacture an inner layer circuit board.

Next, the copper foil wiring layers formed on both sides of the inner layer circuit board were degreased using a 25% solution of Neutral Clean 68 (trademark, manufactured by Shipley) at 60°C. , and after washing with water, etch
746 (trademark, manufactured by Shipley) at 15% and H2O
A soft etching process was performed for 60 seconds using a treatment solution containing 10% of 2, followed by washing with water, followed by pickling using a solid acid containing sulfuric acid as a main component (44 g/l) and washing with water.

The wiring layer of the inner layer circuit board pretreated in this way is oxidized under the following conditions to form wiring layer 1 as shown in FIG.
An oxide film 2 made of Cu2O and CuO was formed on the surface.

Composition of oxidation treatment liquid: Na3 PO4 ・12H
2 O 17g/l
NaOH
31g/l
NaClO2
43g/l Treatment liquid temperature: 85℃ Treatment time: 4
In addition, in Fig. 1, 21 is an oxide film whose main component is CuO.
Further, 22 indicates an oxide film containing Cu2O as a main component.

Furthermore, the thickness of the oxide film 2 was found to be 1.0 μm by Auger spectroscopy.
The uO ratio was confirmed to be 80% using a thin film X-ray diffraction apparatus.

Next, after drying the inner layer circuit board on which the oxide film 2 has been formed, the plurality of inner layer circuit boards are polymerized together with the outer layer copper foil via an adhesive insulating layer, and heated and pressed. A multilayer wiring board was manufactured.

Then, as in the conventional case, this multilayer wiring board was drilled to form a through hole with a diameter of 0.35 mm, and after performing pickling etc. as in the conventional case, through hole plating treatment (no electrolytic copper plating/panel plating)
20μ on the inner wall surface of the through hole and the surface of the multilayer wiring board.
Form a copper plating layer of m thick, and then perform conventional treatments such as water washing and pickling, as well as conventional photoresist layer formation treatment, 20 μm electrolytic copper plating treatment, etching treatment, solder resist layer formation treatment, etc. Through this process, a multilayer wiring board was manufactured.

When the amount of haloing generated in the multilayer wiring board obtained in this way was measured, as shown in FIG. 2, the value of the width L of the pink ring was about 80 μm, which was extremely reduced compared to the conventional method. By applying the present invention, it was confirmed that there is a need for a multilayer wiring board in which the adhesive strength between the wiring layer and the adhesive insulating layer is strong and the appropriate treatment agent does not easily remain at the interface between the wiring layer and the adhesive insulating layer. did it.

[Example 2] This was substantially the same as Example 1 except that the oxidation treatment was carried out under the conditions shown below.

Composition of oxidation treatment liquid: Na3 PO4 ・12H
2 O 17g/l
NaOH
31g/l
NaClO2
43g/l Treatment liquid temperature: 80℃ Treatment time: 4
Furthermore, the film thickness of the oxide film 2 was determined to be 0 by Auger spectroscopy.
．． It was confirmed that the thickness was 6 μm, and the Cu2O/CuO ratio was 140% using a thin film X-ray diffraction apparatus.

When the amount of haloing generated in the multilayer wiring board obtained in this way was measured, the value of the width L of the pink ring was approximately 70 μm or less, which was extremely reduced compared to the conventional method. It was confirmed that this was better than Example 1.

[Example 3] This was substantially the same as Example 1 except that the oxidation treatment was performed in two stages under the following conditions.

(First stage) Composition of oxidation treatment solution: Na3 PO4 ・12H
2 O 17g/l
NaOH
21g/l
NaClO2
43g/l Processing liquid temperature: 90°C Processing time: 4
After performing oxidation treatment under the above conditions for 30 seconds, the surface of the wiring layer 1 is coated with a thickness 1 consisting of Cu2O and CuO, as shown in FIG. 3(A).
．． An oxide film 2 of 0 μm was formed and washed with water.

Next, this oxidized inner layer circuit board is immersed in a 10% H2 SO4 aqueous solution for 20 to 30 seconds, and as shown in FIG. 3(B), the thickness of the oxide film 2 is 0.2
It was etched to a thickness of μm and washed with water.

Next, a second stage oxidation treatment was performed under the conditions shown below to form an oxide film 20 as shown in FIG. 3(C), and the film was washed with water.

(Second stage) Composition of oxidation treatment solution: Na3 PO4 ・12H
2 O 17g/l
NaOH
31g/l
NaClO2
43g/l Treatment liquid temperature: 80℃ Treatment time: 4
Furthermore, it was confirmed that the thickness of the oxide film 20 was 0.6 μm by Auger spectroscopy, and that the Cu2O/CuO ratio was 150% by an X-ray diffraction apparatus for thin films.

When the amount of haloing generated in the multilayer wiring board thus obtained was measured, it was confirmed that the value of the width L of the pink ring was about 60 μm or less, which was as good as in Example 2. did it.

[Comparative Example] This was substantially the same as Example 1 except that the oxidation treatment was carried out under the conditions shown below.

Composition of oxidation treatment liquid: Na3 PO4 ・12H
2 O 17g/l
NaOH
21g/l
NaClO2
43g/l Treatment liquid temperature: 95℃ Treatment time: 4
30 seconds It was confirmed that the thickness of the oxide film 2 was 1.0 μm by Auger spectroscopy, and the Cu2O/CuO ratio was 33% by an X-ray diffraction apparatus for thin films.

When the amount of haloing generated in the multilayer wiring board according to this comparative example was measured, the value of the width L of the pink ring was about 140 μm, which was extremely inferior to the multilayer wiring boards of Examples 1 to 3. I was able to confirm that there was.

[0042]

According to the invention according to claims 1 and 3, the acid resistance of the oxide film is improved as the proportion of Cu2O, which has high acid resistance, increases, so that acid treatment can be performed as appropriate during the manufacturing process of the multilayer wiring board. Even if it is applied, the oxide film of the wiring layer is difficult to dissolve, making it possible to suppress the haloing phenomenon in which the metal copper of the wiring layer is partially exposed.

On the other hand, according to the inventions according to claims 2 and 4, the acid resistance of the oxide film is improved and the thickness of the oxide film is also thin so that side etching is difficult to occur. Even if the treatment is performed, the oxide film of the wiring layer becomes more difficult to dissolve, and it becomes possible to more reliably suppress the haloing phenomenon in which the metal copper of the wiring layer is partially exposed.

Therefore, poor adhesion between the wiring layer and the adhesive insulating layer can be prevented, and the acid treatment agent and the like are less likely to remain at the interface between the wiring layer and the adhesive insulating layer, improving reliability as a multilayer wiring board. It has the effect of significantly improving the

[Brief explanation of the drawing]

FIG. 1 is a partially enlarged sectional view of an inner layer circuit board according to an embodiment.

FIG. 2 is a partially enlarged perspective view of the multilayer wiring board according to the example.

FIGS. 3(A) to 3(C) are process explanatory diagrams of forming an oxide film through two oxidation treatments.

FIG. 4 is a perspective view of a conventional multilayer wiring board in the middle of a manufacturing process.

FIG. 5 is a perspective view of a conventional multilayer wiring board in the middle of a manufacturing process.

FIG. 6 is a perspective view of a conventional multilayer wiring board in the middle of a manufacturing process.

FIG. 7 is a perspective view of a conventional multilayer wiring board in the middle of a manufacturing process.

FIG. 8 is a perspective view of a conventional multilayer wiring board in the middle of a manufacturing process.

FIG. 9 is a perspective view of a conventional multilayer wiring board in the middle of a manufacturing process.

FIG. 10 is a schematic perspective view of a manufactured conventional multilayer wiring board.

FIGS. 11A and 11B are explanatory diagrams of a conventional process of oxidizing the surface of a wiring layer.

12A and 12B are partially enlarged sectional views of a conventional multilayer wiring board after forming through holes.

FIG. 13 is a partially enlarged perspective view of a conventional multilayer wiring board after forming through holes.

FIG. 14 is a partial sectional view taken along the line W-W in FIG. 13;

[Explanation of symbols]

1. Wiring layer 2 Oxide film

Claims (4)

[Claims] 1. A multilayer wiring board in which a plurality of inner layer circuit boards each having a wiring layer made of copper foil with an oxide film of CuO and Cu2O formed on the surface thereof are laminated with an adhesive insulating layer interposed therebetween, wherein the oxide film is The ratio of Cu2O/CuO inside is 8
A multilayer wiring board characterized in that the wiring board is set to 0% or more. 2. A multilayer wiring board comprising a plurality of inner layer circuit boards laminated with an adhesive insulating layer interposed therebetween, each having a wiring layer made of copper foil on the surface of which an oxide film of CuO and Cu2O is formed. The ratio of Cu2O/CuO inside is 8
If it is 0% or more, the thickness of the oxide film is 0.4 μm to 0.8 μm.
A multilayer wiring board characterized by being set to. 3. The wiring layer of the inner layer circuit board having the wiring layer formed of copper foil is oxidized and the surface thereof is coated with carbon.
In a method of manufacturing a multilayer wiring board by forming an oxide film consisting of uO and Cu2O and laminating a plurality of these oxidized inner layer circuit boards via an adhesive insulating layer, A method for manufacturing a multilayer wiring board, characterized in that the oxidation treatment is performed under conditions such that the ratio of Cu2O/CuO is 80% or more. 4. The wiring layer of the inner layer circuit board having the wiring layer formed of copper foil is oxidized and the surface thereof is coated with carbon.
In a method of manufacturing a multilayer wiring board by forming an oxide film consisting of uO and Cu2O and laminating a plurality of these oxidized inner layer circuit boards via an adhesive insulating layer, A method for manufacturing a multilayer wiring board, characterized in that the oxidation treatment is performed under conditions such that the ratio of Cu2O/CuO is 80% or more and the thickness of the oxide film is 0.4 μm to 0.8 μm.