JP3185516B2 - Method for manufacturing multilayer wiring board - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a multilayer wiring board having a plurality of inner circuit boards laminated via an adhesive insulating layer, and more particularly to a copper foil provided on an inner circuit board. A simple multi-layer wiring board that can prevent poor adhesion between a wiring layer made of a metal and the above-mentioned adhesive insulating layer, and in which an appropriate treating agent applied during the manufacturing process hardly remains at the interface between the above-mentioned wiring layer and the adhesive insulating layer. And a method for producing the same.

[0002]

2. Description of the Related Art A multilayer wiring board of this type is, for example, shown in FIG.
19 are manufactured through the steps shown in FIG. The outline will be described below. As shown in FIG. 13, a plurality of inner-layer circuit boards a having a wiring layer made of copper foil are laminated together with an outer-layer copper foil a1 via an adhesive insulating layer (prepreg) b. FIG. 1
After drilling (drilling) a through hole c as shown in FIG. 4, chemical plating of the through hole is performed to cover the inner wall surface of the through hole c with copper plating, and a plating layer d as shown in FIG. Is formed on the surface of the laminate and the inner wall surface of the through hole c.

Then, a photoresist layer e is formed in a pattern on the surface of the chemical copper plating layer d except for a part around the through hole c and a wiring layer forming portion (see FIG. 16). e, a copper electroplating layer f and a solder plating layer g are sequentially formed on portions exposed from e.
Then, after removing the photoresist layer e, using the copper electrolytic plating layer f and the solder plating layer g as a mask, the chemical copper plating layer d and the like are removed by etching as shown in FIG. Further, a method is employed in which a solder resist layer h is formed on these surfaces to manufacture a multilayer wiring board i as shown in FIG.

When the plurality of inner circuit boards a are laminated via an adhesive insulating layer (prepreg) b, the wiring layers provided on the inner circuit boards a are made of copper foil having a smooth surface. Therefore, the adhesive strength with the adhesive insulating layer b was insufficient, and there was a disadvantage that the wiring layer and the adhesive insulating layer b were easily separated with time.

For this reason, in the prior art, FIG.
As shown in (B), the surface of the wiring layer j made of copper foil is coated with, for example, sodium hydroxide (NaOH) at 15 to 25 g /
The surface is treated with an aqueous solution of about 1 l of alkaline sodium chlorite to form an oxide film k of black needle-like crystals of CuO, and the adhesive insulating layer b is formed by interposing the needle-like crystal oxide film k. (Blackening treatment) for improving the adhesive strength with the adhesive.

[0006] By adopting such a method, there is an advantage that the adhesive strength between the wiring layer j and the adhesive insulating layer b can be improved as a whole, but on the other hand, it is made of CuO. Although the oxide film k has resistance to an alkaline solution, it is relatively easily dissolved in an acid. In the case of treatment with a palladium / tin aqueous solution, as shown in FIG. 21 (A), the laminated surface exposed from the inner wall surface of the through hole c comes into contact with this acidic palladium / tin aqueous solution, and the oxide film k at the contact portion is exposed. As shown in FIG. 21B, the metal copper of the wiring layer j is exposed by melting, and a pink ring r is formed along the periphery of the through hole c as shown in FIG. When Phenomenon that is had to occur.

Further, in addition to the above-described hydrochloric acid acidic palladium / tin aqueous solution treatment, when forming a copper electrolytic plating layer f at a portion exposed from the photoresist layer e, an alkaline copper pyrophosphate solution and an acidic copper pyrophosphate solution are added to the plating solution. The copper sulfate solution of the former is known, but the former copper pyrophosphate solution causes a problem of waste liquid treatment, and therefore the latter copper sulfate solution tends to be frequently used. Therefore, the electrolytic plating using the acidic copper sulfate solution may dissolve the oxide film k and further enlarge the pink ring.

The width (L) of the pink ring generated by the treatment with the hydrochloric acid acidic palladium / tin aqueous solution or the electrolytic plating treatment using the copper sulfate solution increases as the diameter of the through hole c decreases. For example, a through hole with a diameter of 0.8 mm has a tendency to be 100 μm or less, while a through hole with a diameter of 0.4 mm or less has a tendency to be about 200 to 400 μm.

When such a phenomenon occurs, a void s is formed at the interface between the wiring layer j on the inner wall surface of the through hole c and the adhesive insulating layer b, as shown in FIG. Therefore, there is a problem that the reliability of the multilayer wiring board is reduced because the processing liquid during the manufacturing process is easily left in the voids s due to a decrease in the thickness of the multilayer wiring board.

The conditions of the blackening treatment with an alkaline oxidizing solution such as the above-mentioned aqueous solution of alkaline sodium chlorite are appropriately adjusted, so that the acid-resistant CuO having acicular crystals can be obtained together with the needle-like crystals.
_Although a method of preventing such adverse effects by forming an oxide film containing 2O on the surface of the wiring layer has been considered, sufficient results have not yet been obtained.

Under such technical background, Japanese Patent Laid-Open No.
In JP-A-8898, a part of a copper oxide film formed by the above-described blackening treatment is subjected to a dissolving treatment with 1/30 to 1/10 normal sulfuric acid to modify the surface state of the above-mentioned oxide film. A method for avoiding the haloing phenomenon described above is disclosed.

[0012]

According to this method, the above-described haloing phenomenon can be surely suppressed, so that a poor adhesion between the wiring layer and the adhesive insulating layer can be prevented, and the above-mentioned wiring can be prevented. Since an acid treatment agent or the like hardly remains at the interface between the layer and the adhesive insulating layer, there is an advantage that the reliability as a multilayer wiring board can be improved.

However, when a plurality of circuit boards are continuously treated using the same bath containing a 1/30 to 1/10 normal sulfuric acid treatment solution, the treatment is carried out as the amount of CuO dissolved in the bath increases. The pH of the solution fluctuates, and accordingly, the degree of modification of the surface of the oxide film on the circuit board is reduced, so that there is a problem that the reliability as the multilayer wiring board tends to vary.

It is possible to make the degree of modification of the surface of the oxide film uniform by frequently replacing the sulfuric acid treatment solution in the bath with a new treatment solution. There is a problem that the processing cost becomes higher as well as worsening.

The present invention has been made in view of such a problem, and an object of the present invention is to suppress the above-mentioned haloing phenomenon and thereby to reduce the wiring layer made of copper foil provided on the inner layer circuit board. Provided is a simple method for manufacturing a multilayer wiring board, which can prevent poor adhesion to an adhesive insulating layer and can prevent an appropriate treating agent applied during a manufacturing process from remaining at an interface between the wiring layer and the adhesive insulating layer. It is in.

[0016]

That is, according to the first aspect of the present invention, the wiring layer of the inner layer circuit board having a wiring layer made of copper foil is subjected to a surface treatment, and a plurality of the surface-treated inner layers are provided. Assuming a method for manufacturing a multilayer wiring board by laminating circuit boards for use with an adhesive insulating layer interposed therebetween, the above-mentioned surface treatment is performed by a blackening treatment with an alkaline oxidizing solution and subsequent phosphoric acid and disodium hydrogen phosphate or An acid treatment in which a buffer solution having a pH of 0 to 3 containing trisodium phosphate is immersed in a treatment bath.

In the above technical means, the blackening treatment means that the surface of the wiring layer is oxidized with an alkaline oxidizing solution to produce black needle-like crystals composed of CuO, and fine particles based on the needle-like crystals are formed. This means a surface roughening treatment for generating unevenness, and a well-known blackening treatment liquid such as the above-mentioned aqueous solution of alkaline sodium chlorite can be applied to this treatment. Further, the subsequent acid treatment means that the treated surface is moderated.
It means a treatment for dissolving and removing the needle-like crystals of CuO by treating with an impingement liquid, and further finely roughening the surface from which the CuO has been removed. The wiring layer immediately after the acid treatment exhibits a red color (the color of Cu or Cu ₂ O), but when it is heated and dried or dried at room temperature, the wiring layer turns into a gray color close to black.
However, the needle-like crystals were not observed on the surface of the wiring layer after such discoloration, and extremely fine irregularities immediately after the acid treatment were maintained.

When the adhesive insulating layer is superimposed on the wiring layer having such fine irregularities and heated and pressed, the adhesive insulating layer is deformed and adhered along the fine irregularities, and has an adhesive strength. Is improved. Therefore, in the subsequent treatment with an acidic treatment solution (for example, an aqueous solution of palladium tin containing hydrochloric acid before the chemical copper plating treatment or an acidic copper sulfate solution during the electrolytic plating treatment), the above-mentioned acid treatment solution is combined with the wiring layer. It hardly penetrates into the adhesive insulating layer, and the above-described occurrence of haloing and reduction in adhesive strength are prevented.

Incidentally, the above-mentioned acid treatment includes phosphoric acid and hydrogen phosphate.
PH 0 containing sodium or trisodium phosphate
3 buffers are applied. That is, when a strong acid having a pH of less than 0 is applied, the surface is smoothed without forming the above-mentioned fine irregularities, so that it is impossible to improve the adhesive strength between the wiring layer and the adhesive insulating layer. On the other hand, it is possible to apply a weak acid exceeding pH 3, but it takes a long time to dissolve and remove CuO and to form fine irregularities, resulting in extremely low treatment efficiency. Therefore, p
It is necessary to apply the above buffers H0-3.

Further, the buffer of the pH0~3 because the stability of the pH compared to the sulfuric acid treatment solution of the illustrated 1 / 30-1 / 10 defined in the prior art is good, the buffer <br / Even if a plurality of circuit boards are continuously processed using the same bath containing>, there is an advantage that the fluctuation of pH is small. Examples of the buffer having a pH of 0 to 3 include a buffer obtained by adding an appropriate amount of disodium hydrogen phosphate or trisodium phosphate to a phosphoric acid aqueous solution. In addition, the degree of dissociation of the acid solution changes depending on the temperature, and its pH also changes depending on the temperature. Therefore, in adjusting the pH, it is necessary to pay attention to the temperature conditions when performing the acid treatment. Note that the acid treatment of the wiring layer can be performed at a temperature of about room temperature to about 80 ° C.
The acid treatment is preferably performed until the reaction between the buffer solution and the wiring layer reaches an equilibrium state, and is usually about 15 seconds to 5 minutes. Further, since phosphoric acid has a higher degree of dissociation than citric acid described below, it has an advantage that the acid treatment can be performed at a lower treatment liquid temperature than the invention according to claims 4 to 6 using a citric acid treatment liquid. I have.

Next, when the surface of the wiring layer is subjected to the acid treatment, it is advantageous to use a treatment liquid having less pH fluctuation during the acid treatment. That is, during the acid treatment, when the applied treatment liquid fatigues with time and its pH becomes 3 or more, the Cu
Since it takes a long time to dissolve and remove O and form fine irregularities, and if the treatment time is short, it is difficult to form fine irregularities, which causes a problem that reliability as a multilayer wiring board is reduced. is there. The invention according to claim 2 is the treatment liquid
The present invention relates to an invention in which a buffer solution is specified .

That is, the invention according to claim 2 is based on the method for manufacturing a multilayer wiring board according to the invention described in claim 1,
The buffer is composed of an aqueous solution containing phosphoric acid and trisodium phosphate.

[0023] according According to buffer according to claim 1 or 2 for the use of the inventive, large amounts of the inner layer circuit board in the factory for even a small variation in pH by processing a large number of internal layer circuit board at a time Can be stably processed, and the degree of processing does not vary depending on the portion of the processed inner layer circuit board. Further, since the pH of the buffer is stable, the management of the buffer is also difficult. It has the advantage of being easy.

Incidentally, the phosphate concentration of the above buffer solution is 3% by weight to 1% as understood from the results of the confirmation test described below.
In the case of 2% by weight, it is possible to achieve both the pH stability of the processing solution and the reduction of the processing cost. The invention according to claim 3 has been made based on such test results.

That is, the third aspect of the present invention provides
Assuming that the method for manufacturing a multilayer wiring board according to the invention described in 1 or 2, the phosphoric acid concentration of the buffer is 3% by weight to 12% by weight.
It is characterized by being.

Next, the invention according to claims 4 to 6 is a multilayer wiring in which a citrate treatment solution is used in place of a buffer solution of pH 0 to 3 containing phosphoric acid and disodium hydrogen phosphate or trisodium phosphate. The present invention relates to a method for manufacturing a plate.

That is, according to a fourth aspect of the present invention, the wiring layer of the inner layer circuit board having the wiring layer made of copper foil is surface-treated, and the plurality of surface-treated inner layer circuit boards are bonded. The surface treatment is performed by a blackening treatment with an alkaline oxidizing treatment solution, followed by a treatment bath containing a citric acid treatment solution having a pH of 0 to 3; And acid treatment immersed in the inside .

[0028] In the invention according to claim 4 , pH 0
As the citric acid treatment solution 3, an aqueous solution of citric acid or a buffer solution obtained by adding an appropriate amount of disodium hydrogen phosphate or potassium citrate to an aqueous solution of citric acid can be used. Also,
It is also possible to apply a buffer solution in which (citrate + potassium dihydrogen phosphate + boric acid + diethyl parbituric acid) or an appropriate amount of (boric acid + citrate) is added to an aqueous solution of trisodium phosphate.

The citric acid treatment solution applied to the invention according to claim 4 is 1/3 as in the invention according to claim 1.
Since the pH stability is better than that of the sulfuric acid-treated solution of 0 to 1/10 normal, even if a plurality of circuit boards are continuously treated using the same bath containing the citric acid-treated solution, This has the advantage that the fluctuation of is small.

Further, the inventions according to claims 5 and 6 relate to the inventions made for the same purpose as the inventions according to claims 1 and 3 .

That is, the invention according to claim 5 is the same as the claim 1.
Assuming a method for manufacturing a multilayer wiring board according to the invention described in 4 ,
The citric acid treatment solution is constituted by a buffer solution, and the invention according to claim 6 relates to the method for manufacturing a multilayer wiring board according to claim 4 or 5. Assuming that the citric acid concentration of the citric acid treatment solution is 1.5% by weight
-10% by weight.

The treatment solution composed of the citric acid or the buffer solution is fatigued with time due to the acid treatment, but can be reused by electrolyzing the exhausted treatment solution, thereby economically. It has advantageous advantages.

The process of manufacturing the multilayer wiring board after laminating the inner-layer circuit boards subjected to the series of processes is optional. For example, the multilayer wiring board may be manufactured through the same process as the above-described conventional method. Other steps may be performed.

The circuit board for the inner layer to be applied may be one having a wiring layer only on one side thereof or one having a wiring layer on both sides thereof.

[0035]

According to the first and second aspects of the present invention, the surface treatment of the wiring layer is performed by blackening treatment with an alkaline oxidizing solution, followed by phosphoric acid and disodium hydrogen phosphate or phosphorous.
And an acid treatment of immersing in a treatment bath containing a buffer solution of pH 0 to 3 containing trisodium acid, so that fine irregularities are formed on the surface of the wiring layer, and the adhesive insulating layer for the wiring layer is formed. Can be improved in adhesive strength. Therefore,
During the manufacturing process of the multilayer wiring board, even if an appropriate acid treatment such as a treatment with a hydrochloric acid acidic palladium / tin aqueous solution or an electrolytic plating treatment using a copper sulfate solution is applied, the treatment liquid is used to form the wiring layer and the adhesive insulating layer. This makes it difficult to penetrate into the space, so that the above-described haloing phenomenon can be suppressed as much as possible.

Also, phosphoric acid and disodium hydrogen phosphate or
The pH of the buffer solution containing 0 to 3 containing trisodium phosphate is higher than that of the sulfuric acid treatment solution applied in the prior art.
Because of its good stability, it is possible to continuously process a plurality of circuit boards using the same bath containing this buffer solution, and the dissociation degree of phosphoric acid is lower than that of citric acid described below. Since it is high, acid treatment can be performed at a low temperature of the processing solution.

[0037]

Further, according to the invention according to claim 3, said
Since the phosphate concentration of the buffer solution is set to 3% by weight to 12% by weight, it is possible to achieve both pH stability of the processing solution and reduction of the processing cost.

According to the fourth aspect of the present invention, the surface treatment for the wiring layer includes a blackening treatment with an alkaline oxidizing treatment solution and a subsequent citric acid treatment solution having a pH of 0 to 3.
And an acid treatment immersed in the treated bath, so that fine irregularities are formed on the surface of the wiring layer, and as in the invention according to claim 1, the adhesion strength of the adhesive insulating layer to the wiring layer is improved. Can be achieved. Therefore, even if an appropriate acid treatment such as treatment with hydrochloric acid acidic palladium / tin aqueous solution or electrolytic plating treatment using a copper sulfate solution is applied during the production process of the multilayer wiring board, the treatment liquid is not adhesively insulated from the wiring layer. Since it becomes difficult to penetrate between the layers, the above-described haloing phenomenon can be suppressed as much as possible.

Since the citric acid-treated solution has better pH stability than the sulfuric acid-treated solution, it is possible to continuously treat a plurality of circuit boards using the same bath containing the phosphating solution. It becomes possible.

According to the fifth aspect of the present invention, the citric acid treatment solution is constituted by a buffer solution for maintaining the pH of the solution at a substantially constant value, and a large amount of the circuit board for the inner layer is formed by the same treatment solution once. Therefore, the treatment liquid management in the acid treatment can be more simplified than in the method according to the fourth aspect of the present invention, even if the treatment is carried out at a low temperature.

Further, according to the invention of claim 6 , since the concentration of phosphoric acid in the citric acid treatment liquid is set to 1.5% by weight to 10% by weight, the pH stability of the treatment liquid and the reduction of the treatment cost are reduced. Can be achieved together.

[0043]

Next, the following confirmation tests were carried out to confirm the treatment characteristics of a phosphating solution (including both a phosphoric acid solution and a buffer containing phosphoric acid and trisodium phosphate ). . "Phosphoric acid concentration and pH" First, phosphoric acid [85%, manufactured by Kanto Chemical Co., Ltd.] was added to 100 cc of water, and the pH change was confirmed. The result is shown in FIG. [PH Stability of Phosphoric Acid (1)] Next, referring to the above results, the following six treatment liquids (a to f) were prepared so that the pH of the aqueous solution became approximately 1.8. a. Phosphoric acid 0.36% pH = 1.78 b. 3.4% phosphoric acid + 33.0 g of trisodium phosphate
/L...pH=1.70 c. 5.95% phosphoric acid + 74.5% trisodium phosphate
g / l pH = 1.67 d. 8.50% phosphoric acid + 110 g of trisodium phosphate
/L...pH=1.62 e. Phosphoric acid 17.0% + Trisodium phosphate 293g
/L...pH=1.82 f. Citric acid 40 g / l pH = 1.49 These 6 kinds of treatment liquids (aqueous solution: 40 ° C.)
N-NaOH was added and the pH change was examined. The result is shown in FIG.

From the graph shown in FIG. 9, it was confirmed that the phosphate buffer at a certain concentration or more had better pH stability than citric acid (f). [PH Stability of Phosphoric Acid (2)] Next, the optimum concentration of the phosphating solution in consideration of the balance between the pH stability and the bathing cost was determined. The pH value suitable for haloless treatment was already confirmed to be 2.3 or less from the experimental results using the citric acid treatment solution.
The range of H1.8 to 2.3 was enlarged and plotted again.
The result is shown in FIG. The results of differentiating the regression formulas for these (the processing liquids a to f) are shown below. It should be noted that a smaller value means that the pH is less likely to fluctuate.

A. Y ′ = 1.648 × 10 ⁻¹ b. Y ′ = 3.118 × 10 ⁻² c. Y ′ = 1.919 × 10 ⁻² d. Y ′ = 1.313 × 10 ⁻² e. Y ′ = 1.021 × 10 ⁻² f. Y ′ = 1.018 × 10 ⁻¹ “pH Stability of Phosphoric Acid (3)” Therefore, a graph was prepared with the phosphoric acid concentration of the phosphating solution as the horizontal axis, and the change in the differential value was examined. The result is shown in FIG.

Then, from the graph shown in FIG.
Almost pH from 10% phosphoric acid concentration of phosphating solution
Is not improved. As a result, it is most efficient to use a phosphoric acid concentration of around 10% (that is, both pH stability and processing cost can be reduced). In this sample, phosphoric acid is 8.50% +
It was confirmed that the treatment liquid of trisodium phosphate 110 g / l (d) had the most efficient composition. "Dissolution amount of CuO and pH stability of each processing solution" Next, copper oxide powder was added to the following four processing solutions to artificially fatigue the processing solutions to investigate the precipitation time of the complex. That is, CuO powder was added to 1000 cc of the treatment liquid, and the change in pH and the occurrence of precipitates were examined. It should be noted that from the test results, it is possible to confirm how many wiring boards can be processed continuously (the number of sheets that can be processed) without changing the processing liquid in the same bath.

(1) Sulfuric acid-treated solution: 0.1% by volume (liquid temperature: room temperature) (2) Tartaric acid-treated solution: 14.409 g / l tartaric acid (liquid temperature: 65 ° C.) + Sodium tartrate 0.3451 g / l ( 3) citric acid treatment solution: citric acid 41.187g / l (solution temperature _{... 65 ℃) + Na 2 HPO} 4 0.5678g / l (4) phosphating solution: 8.50% phosphoric acid (solution temperature ... 40 ° C. ) + Trisodium phosphate 110 g / l (d above) The results are shown in FIG. 12 and Table 1 below.

[0048]

[Table 1] From this result, it can be confirmed that the phosphating solution and the citric acid treating solution have a larger amount of dissolved CuO and better pH stability than the sulfuric acid treating solution and the tartaric acid treating solution. "Processable number" The processable number of each processing liquid was calculated from these results.

It should be noted that 510 corresponding to a relatively large wiring board
A single-sided solid copper foil having a size of mm × 609 mm is formed with CuO by blackening treatment, and the amount of CuO dissolved from the treated double-sided solid copper foil is converted to Cu (C
u: molecular weight 63.5, CuO: molecular weight 79.5), it becomes 2.678 g, and when converted to the amount of CuO, 2.67: 63.5 = x: 79.5, x = 3.34 g. Become.

The capacity of the processing bath is set to 100 (liter). (1) Number of treatable sulfuric acid-treated solutions From the graph of FIG. 12 showing the relationship between the amount of dissolved CuO and the pH, the pH exceeded 3 when the amount of dissolved CuO was about 0.85 (g / l). Can be confirmed.

In a 100 (liter) treatment bath, 85 g of CuO exceeds pH 3, so that the number of sheets that can be treated is 85 ÷ 3.34 = 25.4 sheets.

Therefore, when a sulfuric acid treatment solution is applied, 25%
It is understood that since it is necessary to exchange the processing liquid for each sheet, the processing liquid management becomes complicated. (2) Number of treatable tartaric acid treatment solutions From the graph of FIG. 12 showing the relationship between the amount of dissolved CuO and the pH, precipitation occurs when the amount of dissolved CuO is about 0.5 (g / l), and the subsequent treatment is not performed. It can be confirmed that it becomes difficult. In a 100 (liter) treatment bath, CuO is 50
Since the subsequent processing becomes difficult in g, the number of sheets that can be processed is 50 / 3.34 = 15.

Therefore, it is understood that the treatment liquid management becomes complicated as in the case where the sulfuric acid treatment liquid is applied. (3) Number of treatable citric acid treatment solutions From the graph of FIG. 12 showing the relationship between the amount of dissolved CuO and the pH, precipitation occurs when the amount of dissolved CuO is approximately 1.5 (g / l), and the subsequent treatment is performed. It can be confirmed that it becomes difficult. In a 100 (liter) treatment bath, CuO is 1
Since subsequent processing becomes difficult with 50 g, the number of sheets that can be processed is 150 ÷ 3.34 = 44.9 sheets.

Therefore, it is understood that the management of the treatment liquid is simpler than the case where the sulfuric acid treatment liquid or the like is applied. (4) Number of treatable phosphoric acid treatment liquids From the graph of FIG. 12 showing the relationship between the amount of dissolved CuO and the pH, precipitation occurs when the amount of dissolved CuO is approximately 4.5 (g / l), and subsequent treatment is performed. It can be confirmed that it becomes difficult. In a 100 (liter) treatment bath, CuO is 4
Since the subsequent processing becomes difficult with 50 g, the number of sheets that can be processed is 450 ÷ 3.34 = 134.7 sheets.

Therefore, it is understood that the treatment liquid management becomes simpler than when a sulfuric acid treatment liquid or the like is applied.

In these tests, a double-sided solid copper foil wiring board was used. However, the actual processing was performed by patterning the copper foil (the patterning processing indicated that the residual ratio of copper was about 40%). ), The actual number of sheets that can be processed is about 2.5 times that number.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. Example 1 First, a glass-epoxy copper-clad laminate (340 mm ×
510 mm × 0.3 mm), and this copper foil is coated with Neutral Clean 68 (trademark, manufactured by Shipley).
First, a degreasing treatment is performed at 60 ° C. using a 5% solution, and
After washing with water, a soft etching treatment is performed for 60 seconds using a treatment solution containing 15% of Etch 746 (trademark, manufactured by Shipley) and 10% of H ₂ O _2, and then washed with water. The solid acid (44 g / l) as a component was pickled and washed with water.

The circuit board for the inner layer pretreated as described above was immersed in the following blackening solution to blacken the wiring layer.

Composition of blackening treatment liquid: NaOH 21 g / l NaClO ₂ 43 g / l Na ₃ PO ₄ .12H ₂ O 17 g / l Treatment liquid temperature: 95 ° C. Processing time: 4.5 minutes The surface was blackish which was considered to be needle-like crystals of CuO. Next, the black inner layer circuit board was immersed in a citric acid treatment solution described below to acid-treat the surface of the wiring layer.

Composition of citric acid treatment liquid: citric acid 41.187 g / l Na ₂ HPO ₄ 0.5678 g / l citric acid treatment liquid pH: about 2.0 treatment liquid temperature: 65 ° C. treatment time: 2.5 minutes The surface of the wiring layer thus treated with acid is red (Cu or Cu
₂ O showed color), but was washed with water and turns gray close to black was dried by heating. The surface of this wiring layer was photographed with a scanning electron microscope.

This photograph is shown in FIGS. FIG. 2 is a scanning electron microscope photograph at a magnification of 2000 times, and FIG. 3 is a scanning electron microscope photograph at a magnification of 20000 times.

From comparison with a scanning electron micrograph (see FIGS. 4 and 5) of Comparative Example 1 described below, relatively large needle-like crystals are observed in Comparative Example 1 immediately after the blackening treatment. On the other hand, in Example 1 in which the acid treatment was performed after the blackening treatment, such needle-like crystals were not found, and it was confirmed that finer irregularities were generated than the needle-like crystals.

Next, after drying the acid-treated inner layer circuit board, a plurality of inner layer circuit boards are polymerized together with the outer layer copper foil by heating and pressing through an adhesive insulating layer, and these are laminated. did.

Then, in the same manner as before, this laminate is drilled to form a through hole having a diameter of 0.35 mm. Then, the inner wall of the through hole is treated with a hydrochloric acid acidic palladium / tin aqueous solution and chemically copper plated. Then, a conventional treatment such as water washing and pickling was performed, and a photoresist layer similar to the conventional one was formed. Thereafter, electrolytic copper plating was performed under the following conditions.

Composition of plating solution: CuSO ₄ .5H ₂ O 60 to 70 g / l H ₂ SO ₄ 200 to 210 g / l Plating temperature: normal temperature Current density: about 1.8 A / dm ² Plating thickness: about 15 μm As in the prior art, a multilayer wiring board was manufactured through a solder plating process, a photoresist layer stripping process, an etching process, a solder / resist layer forming process, and the like.

When the width L of the pink ring generated in the wiring layer 1 of the multilayer wiring board thus obtained was measured as shown in FIG. 1, the width L was 0 μm, and no pink ring was confirmed.

On the other hand, the copper foil of the inner layer circuit board is sequentially immersed in the above-mentioned blackening treatment solution and citric acid treatment solution without patterning the copper foil, and the copper foil is subjected to a surface treatment. A plurality of these circuit boards for an inner layer were polymerized by heating and pressing through an adhesive insulating layer to produce a laminate different from the multilayer wiring board. The peel strength (adhesive strength) between the surface-treated copper foil and the adhesive insulating layer of these laminates was measured to be 0.91 kg / cm.
Therefore, it has been confirmed that the multilayer wiring board according to Example 1 has a sufficient adhesive strength between the wiring layer and the adhesive insulating layer.

Next, after immersing the laminate in a molten solder bath and pulling it up, the adhesive strength between the wiring layer and the adhesive insulating layer was measured.
g / cm, and it was also confirmed that there was no deterioration in adhesive strength due to soldering. Comparative Example The same treatment as in Example 1 was performed except that the above-mentioned acid treatment was not performed.

Then, the surface of the wiring layer after the blackening treatment was photographed with a scanning electron microscope. The micrographs are shown in FIGS. FIG. 4 is a scanning electron micrograph at 2000 × magnification and FIG. 5 is a 2000 × magnification scanning electron micrograph.

Next, a plurality of inner-layer circuit boards were laminated together with an outer-layer copper foil via an adhesive insulating layer in the same manner as in Example 1.
Drilled to form a through hole with a diameter of 0.35 mm, treated with hydrochloric acid acidic palladium / tin aqueous solution, chemically copper plated, electrolytic copper plated, further solder plated, photoresist layer peeled, A multilayer wiring board was manufactured through an etching process, a solder / resist layer forming process, and the like.

As shown in FIG. 1, the width L of the pink ring formed on the wiring layer 1 of the multilayer wiring board thus obtained was measured and found to be 220 μm.

On the other hand, in the same manner as in Example 1, the copper foil of the inner layer circuit board was immersed in the above-mentioned blackening treatment solution without patterning the copper foil, and the copper foil was subjected to a surface treatment and dried. A plurality of these circuit boards for an inner layer were polymerized by heating and pressing through an adhesive insulating layer to produce a laminate different from the multilayer wiring board. The peel strength (adhesive strength) between the surface-treated copper foil and the adhesive insulating layer of these laminates was measured to be 0.15 kg / cm.

Next, after immersing the laminate in a molten solder bath and pulling it up, the adhesive strength between the wiring layer and the adhesive insulating layer was measured.
cm. Example 2 A blackening process was performed under the same conditions as in Example 1.

Next, the black inner layer circuit board was immersed in the following phosphating solution to acid-treat the wiring layer.

Composition of phosphating solution: phosphoric acid (phosphoric acid concentration: 8.50% by weight) Trisodium phosphate 110 g / l pH of phosphating solution: approximately 1.62 Temperature of treating solution: 40 ° C. Treatment time: 2 The surface of the wiring layer thus treated with acid is red (Cu or C
u ₂ O), but after being washed with water and dried by heating, the color changed to gray close to black. The surface of this wiring layer was photographed with a scanning electron microscope. This photograph is shown in FIGS. FIG. 6 is a scanning electron microscope photograph at a magnification of 2000 times, and FIG. 7 is a photograph at a magnification of 20000 times. 6 and FIG.
It was confirmed from the photograph that the fine unevenness similar to that of Example 1 was provided.

Next, in the same manner as in Example 1, a plurality of circuit boards for the inner layer were laminated together with the copper foil for the outer layer via an adhesive insulating layer.
Drilled to form a through hole with a diameter of 0.35 mm, treated with hydrochloric acid acidic palladium / tin aqueous solution, chemically copper plated, electrolytic copper plated, further solder plated, photoresist layer peeled, A multilayer wiring board was manufactured through an etching process, a solder / resist layer forming process, and the like.

When the width L of the pink ring generated in the wiring layer 1 of the multilayer wiring board thus obtained was measured as shown in FIG. 1, the width L was 0 μm as in the first embodiment.
m.

On the other hand, in the same manner as in Example 1, the copper foil was surface-treated by sequentially immersing the copper foil in the blackening treatment solution and the phosphoric acid treatment solution without patterning the copper foil for the inner layer circuit board, and After drying, a plurality of these inner-layer circuit boards were polymerized by heating and pressing through an adhesive insulating layer to produce a laminate different from the multilayer wiring board. The peel strength (adhesive strength) between the surface-treated copper foil and the adhesive insulating layer of these laminates was measured.
A good result of 90 kg / cm is shown, confirming that the multilayer wiring board according to Example 2 has sufficient adhesive strength between the wiring layer and the adhesive insulating layer.

After immersing the laminate in a molten solder bath and pulling it up, the adhesive strength between the wiring layer and the adhesive insulating layer was measured.
g / cm, and it was also confirmed that there was no deterioration in adhesive strength due to soldering. Example 3 A blackening process was performed under the same conditions as in Example 1.

Next, this black inner layer circuit board was immersed in the following citric acid treatment solution to acid-treat the wiring layer.

Composition of citric acid treatment liquid: citric acid 41.187 g / l Na ₂ HPO ₄ 1.1358 g / l citric acid treatment liquid pH: about 2.30 treatment liquid temperature: 65 ° C. treatment time: 2.5 minutes The surface of the wiring layer thus treated with acid is red (Cu or C
u ₂ O), but after being washed with water and dried by heating, the color changed to gray close to black. When the surface of the wiring layer was photographed with a scanning electron microscope, it was confirmed that the wiring layer had fine irregularities similar to the photographs of FIGS.

Next, a plurality of inner-layer circuit boards were laminated together with an outer-layer copper foil via an adhesive insulating layer in the same manner as in Example 1.
Drilled to form a through hole with a diameter of 0.35 mm, treated with hydrochloric acid acidic palladium / tin aqueous solution, chemically copper plated, electrolytic copper plated, further solder plated, photoresist layer peeled, A multilayer wiring board was manufactured through an etching process, a solder / resist layer forming process, and the like.

The width L of the pink ring generated in the wiring layer 1 of the multilayer wiring board thus obtained was measured as shown in FIG.
m.

On the other hand, in the same manner as in Example 1, the copper foil was subjected to the surface treatment by sequentially immersing the copper foil in the blackening treatment solution and the citric acid treatment solution without patterning the copper foil for the inner layer circuit board, and After drying, a plurality of these inner-layer circuit boards were polymerized by heating and pressing through an adhesive insulating layer to produce a laminate different from the multilayer wiring board. When the peel strength (adhesive strength) between the surface-treated copper foil and the adhesive insulating layer of these laminates was measured, a good result of 0.93 kg / cm was shown. In a multilayer wiring board, it has been confirmed that the adhesive strength between the wiring layer and the adhesive insulating layer is sufficient.

After immersing the laminate in a molten solder bath and pulling it up, the adhesive strength between the wiring layer and the adhesive insulating layer was measured.
g / cm, and it was also confirmed that there was no deterioration in adhesive strength due to soldering.

[0086]

Effects of the Invention According to the invention according to claim 21 to, fine irregularities on the configured surface of the wiring layer of copper foil is formed can be improved adhesive strength of the adhesive insulating layer for the wiring layer. Therefore, even if an appropriate acid treatment such as treatment with hydrochloric acid acidic palladium / tin aqueous solution or electrolytic plating treatment using a copper sulfate solution is applied during the production process of the multilayer wiring board, the treatment liquid is not adhesively insulated from the wiring layer. It becomes difficult to penetrate between the wiring layer and the adhesive insulating layer, so that the above-mentioned haloing phenomenon can be suppressed as much as possible, and the poor adhesion between the wiring layer and the adhesive insulating layer can be prevented and the interface between the wiring layer and the adhesive insulating layer can be prevented The acid treatment agent and the like hardly remain, and the reliability as a multilayer wiring board can be remarkably improved.

Further, phosphoric acid and disodium hydrogen phosphate or
The pH of the buffer solution containing 0 to 3 containing trisodium phosphate is higher than that of the sulfuric acid treatment solution applied in the prior art.
Because of its good stability, it is possible to continuously process a plurality of circuit boards using the same bath containing this buffer solution, and the dissociation degree of phosphoric acid is lower than that of citric acid described below. Since it is high, acid treatment can be performed at a low temperature of the processing solution. Therefore, there is an effect that the acid treatment can be simplified as compared with the prior art using the sulfuric acid treatment liquid.

[0088]

[0089] Further, according to the invention according to claim 3, said
Since the phosphoric acid concentration of the buffer solution is set to 3% by weight to 12% by weight, it has an effect that both pH stability of the processing solution and reduction of the processing cost can be achieved.

On the other hand, according to the invention of claim 4 , similarly to the invention of claim 1, it becomes possible to suppress the haloing phenomenon as much as possible, and to prevent poor adhesion between the wiring layer and the adhesive insulating layer. As a result, the acid treatment agent or the like hardly remains at the interface between the wiring layer and the adhesive insulating layer, so that the reliability as a multilayer wiring board can be significantly improved.

The citric acid treatment solution is composed of phosphoric acid and phosphoric acid aqueous solution.
PH containing disodium or trisodium phosphate
Similar to the buffer solutions 0 to 3, the pH stability is better than the sulfuric acid treatment solution used in the prior art, so that a plurality of circuit boards are continuously connected using the same bath containing the citrate treatment solution. Can be processed. Therefore, it has the effect of simplifying the acid treatment as compared with the prior art.

Further, according to the fifth aspect of the present invention, the citric acid treatment solution is constituted by a buffer solution for maintaining the pH of the solution at a substantially constant value, and a large amount of the inner layer circuit board is formed by the same treatment solution once. Thus, since the fluctuation of pH is small even if the treatment is carried out, there is an effect that the treatment liquid management in the acid treatment can be more easily performed as compared with the method according to claim 4 .

According to the invention of claim 6 , the citric acid treatment solution has a citric acid concentration of 1.5% by weight to 10% by weight.
Therefore, similarly to the invention according to claim 3 , there is an effect that both the pH stability of the processing solution and the reduction of the processing cost can be achieved.

[Brief description of the drawings]

FIG. 1 is a partially enlarged perspective view of a multilayer wiring board according to an embodiment.

FIG. 2 is a 2000 × scanning electron microscope photograph showing the surface shape of a wiring layer after blackening treatment and acid treatment according to Example 1.

FIG. 3 is a scanning electron micrograph (magnification: 20,000) showing a surface shape of a wiring layer after blackening treatment and acid treatment according to Example 1.

FIG. 4 is a 2000 × scanning electron microscope photograph showing the surface shape of a wiring layer after a blackening process according to a comparative example.

FIG. 5 is a scanning electron micrograph (magnification: 20,000) showing a surface shape of a wiring layer after blackening processing according to a comparative example.

FIG. 6 is a scanning electron micrograph (× 2000) showing the surface shape of a wiring layer after blackening treatment and acid treatment according to Example 2.

FIG. 7 is a scanning electron micrograph (magnification: 20,000) showing the surface shape of a wiring layer after blackening treatment and acid treatment according to Example 2.

FIG. 8 is a graph showing the relationship between the dropping amount (ml) of phosphoric acid (85%) and pH determined by a confirmation test.

FIG. 9 shows the results of 1 in each processing solution obtained by the confirmation test
The graph which shows the relationship between the amount (ml) of N-NaOH dripping, and pH.

FIG. 10 is a partially enlarged view of the graph of FIG. 9;

FIG. 11 is a graph showing a relationship between a phosphoric acid concentration in a phosphating solution and a differential value obtained by a confirmation test.

FIG. 12 is a graph showing the relationship between the amount of CuO dissolved (g / l) and pH in each processing solution obtained by the confirmation test.

FIG. 13 is a perspective view of a conventional multilayer wiring board during a manufacturing process.

FIG. 14 is a perspective view of a conventional multilayer wiring board during a manufacturing process.

FIG. 15 is a perspective view of a conventional multilayer wiring board during a manufacturing process.

FIG. 16 is a perspective view of a conventional multilayer wiring board during a manufacturing process.

FIG. 17 is a perspective view of a conventional multilayer wiring board during a manufacturing process.

FIG. 18 is a perspective view of a conventional multilayer wiring board during a manufacturing process.

FIG. 19 is a schematic perspective view of a manufactured conventional multilayer wiring board.

FIGS. 20A and 20B are explanatory views of a conventional process for blackening the surface of a wiring layer.

FIGS. 21A and 21B are partially enlarged cross-sectional views of a conventional multilayer wiring board after through holes are formed.

FIG. 22 is a partially enlarged perspective view of a conventional multilayer wiring board after through holes are formed.

FIG. 23 is a partial cross-sectional view taken along the line WW of FIG. 22;

[Explanation of symbols]

 1 Wiring layer

Continuation of front page (56) References JP-A-2-306955 (JP, A) JP-A-4-247691 (JP, A) JP-B-58-2476 (JP, B2) (58) Fields investigated (Int) .Cl. ⁷ , DB name) H05K 3/10-3/46

Claims (6)

(57) [Claims] An inner circuit board having a wiring layer made of copper foil is subjected to a surface treatment, and a plurality of the surface treated inner circuit boards are laminated via an adhesive insulating layer. In the method for producing a multilayer wiring board, the surface treatment is performed by a blackening treatment with an alkaline oxidizing solution, followed by phosphoric acid and disodium hydrogen phosphate or phosphorus.
A method for producing a multilayer wiring board, comprising: immersing in a treatment bath containing a buffer solution having a pH of 0 to 3 containing trisodium acid . Wherein said buffer is a method for manufacturing a multilayer wiring board according to claim 1, characterized in that it is constituted by an aqueous solution containing trisodium phosphate and phosphoric acid. 3. The buffer solution according to claim 1, wherein the phosphate concentration is 3% by weight to 12%.
3. The method for producing a multilayer wiring board according to claim 1, wherein the content is% by weight. 4. 4. A surface treatment of the wiring layer of an inner layer circuit board having a wiring layer made of a copper foil, and laminating a plurality of the surface treated inner layer circuit boards via an adhesive insulating layer. In the method for manufacturing a multilayer wiring board, the surface treatment includes a blackening treatment with an alkaline oxidation treatment solution and a subsequent acid treatment immersion in a treatment bath containing a citric acid treatment solution having a pH of 0 to 3. A method for producing a multilayer wiring board. 5. The method for producing a multilayer wiring board according to claim 4, wherein said citric acid treatment solution is a buffer solution. 6. The citric acid treatment solution having a citric acid concentration of 1.
5. The composition according to claim 4, wherein the content is 5% by weight to 10% by weight.
Or the method for producing a multilayer wiring board according to 5.