JPH06204660A - Manufacture of multilayer printed wiring board - Google Patents

Abstract

PURPOSE:To provide the manufacture of multilayer printed wiring board capable of giving excellent adhesion to a wiring board and of preventing the worsening of heat resistance. CONSTITUTION:A permanent resist 4 is formed on an insulating substrate 3 and an inner layer board 1 having a conductor pattern 2 is prepared by applying chemical copper plating. Degreasing treatment, acid treatment and silane coupling agent treatment are performed in this order for the surface of the conductor pattern 2 on the inner layer board 1. A prepreg 5 and the inner layer board 1 are adhered by thermocompression bonding by laminated forming process thereafter. According to this method using no soft etching treatment, no cracking occurs in the wiring board even at the time of exposing to a high temperature.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a multilayer printed wiring board, and more particularly to a method for manufacturing a multilayer printed wiring board in which an inner layer pattern is formed by a full additive method.

[0002]

2. Description of the Related Art In a conventional method for manufacturing a multilayer printed wiring board, an inner layer pattern is manufactured by a subtractive method. In recent years, some methods for manufacturing a multilayer printed wiring board in which an inner layer pattern is formed by the full additive method have been proposed.

In a conventional method of manufacturing a multilayer printed wiring board in which an inner layer pattern is formed by the full additive method, as shown in FIG. 2, first, an inner layer board 11 having a conductor pattern 12 serving as an inner layer is manufactured. This conductor pattern 12
Is a permanent resist 14 such as by chemical copper plating.
Is formed in the non-formed part. After that, the inner layer plate 11 is laminated and pressure-bonded through the prepreg 15 and the like,
It becomes a multilayer printed wiring board. Then, in the conventional manufacturing method, a step of roughening the surface of the conductor pattern 12 is performed before the lamination molding. Then, the bonding force between the conductor pattern 12 and the prepreg 15 is improved by this step.

The roughening step of the surface of the conductor pattern 12
More specifically, it includes the following processes. That is, the steps are degreasing treatment with alkali, water washing, soft etching treatment, water washing, acid treatment for removing an oxide film, water washing, blackening treatment with high temperature and strong alkali, water washing and drying. And
Through these steps, a needle-shaped crystal layer of copper oxide is newly formed on the copper layer on the surface of the pattern.
The needle-shaped crystal layer functions as a physical anchor when the prepreg 15 and the like are laminated and pressure-bonded.

[0005]

However, the inner layer pattern formed by the full additive method is characterized in that the interface in contact with the permanent resist 14 is easily etched when the surface of the conductor pattern 12 is soft-etched by the soft etching process. Yes (see Figure 2).

When the side wall of the conductor pattern 12 is soft-etched in this manner, a gap S may be formed between the side wall of the conductor pattern 12 and the permanent resist 14. The gap S may not be completely filled with the resin impregnated in the prepreg 15 at the time of stacking and pressure bonding the prepreg 15 and the like, and a void may occur inside the multilayer printed wiring board.

When such a multilayer printed wiring board encounters a high temperature, a crack C is generated from the hollow portion (see FIG. 3), and delamination or the like occurs in the insulating layer or between the conductor and the insulating layer. It tends to occur.

The present invention has been made in view of the above circumstances, and an object thereof is to provide a method for manufacturing a multilayer printed wiring board capable of preventing deterioration of heat resistance without impairing adhesion. is there.

[0009]

In order to solve the above problems, in the first invention, in a method for manufacturing a multilayer printed wiring board in which an inner layer pattern is formed by a full additive method, the inner layer pattern surface is degreased. The gist of the present invention is to carry out the lamination molding after sequentially performing the treatment, the acid treatment and the blackening treatment.

In the second invention, in the method for manufacturing a multilayer printed wiring board in which the inner layer pattern is formed by the full additive method, the inner layer pattern surface is degreased,
After sequentially performing acid treatment and silane coupling agent treatment,
It is the gist to perform laminate molding. Here, the silane coupling agent refers to a chemical agent used to improve the binding force between an inorganic substance such as a metal and an organic substance such as a resin at the interface.

[0011]

In the first and second aspects of the invention, since the conventional soft etching process is not carried out, no gap is formed on the side wall of the conductor pattern, and as a result, the wiring board encounters a high temperature after the lamination molding. Even at times, the destruction of the wiring board can be avoided.

When the conventional inner layer pattern is formed by the subtractive method, the copper surface made of copper foil or electrolytic copper becomes very smooth. Therefore, when a wiring board is manufactured without performing the soft etching process as in the present invention, sufficient adhesion between the inner layer pattern and the insulating layer cannot be secured only by the anchor formed by the subsequent blackening process.

On the other hand, when the inner layer pattern is formed by the additive method, the copper surface formed of chemical copper has a very porous crystal structure. Therefore, even if the wiring board is manufactured without soft etching as in the present invention, the anchor formed by the subsequent blackening treatment forms sufficient adhesion between the inner layer pattern and the insulating layer. Will be secured.

Further, according to the treatment of the silane coupling agent of the second invention, a chemical bonding effect can be obtained, and therefore sufficient adhesion can be secured to the wiring board as well.

[0015]

EXAMPLES Examples 1 and 2 and Comparative Examples 1 and 2 embodying the present invention will be described in detail below with reference to the drawings. These manufacturing methods mainly include a manufacturing process of the inner layer plate, a process of treating the surface of the conductor pattern, and a lamination molding process. In each manufacturing method, the surface roughening step of the conductor pattern is slightly different. Example 1 As shown in FIG. 1, first, an inner layer plate 1 having an inner layer conductor pattern 2 was manufactured by the following procedure of the full additive method. That is, an adhesive was applied to a predetermined portion of the insulating substrate 3 to roughen the adhesive layer. Then, a catalyst nucleus for electroless plating was provided on the surface of the adhesive layer. After laminating a film for plating resist on it, a permanent resist 4 was formed on the portion other than the portion where the plating layer was to be formed based on a method such as exposure, development and heat treatment. After that, a portion of the permanent resist 4 not formed is subjected to chemical copper plating to form a conductor pattern 2. The conductor pattern 2 thus obtained has an extremely porous crystal structure. The insulating substrate 3 used in Example 1 is made of glass epoxy (FR-4 grade). In addition, the permanent resist 4 is "Nopco Cure F701-
40 "(trade name, manufactured by San Nopco Ltd.).

Next, the step of roughening the surface of the conductor pattern 2 will be described. First, as the degreasing treatment, the inner layer plate 1
Was immersed in an alkaline aqueous solution "Alchelate" (trade name, manufactured by Shipley Far East Co., Ltd.) to remove oil and fat adhering to the surface of the conductor pattern 2. The processing conditions are 50 ° C. and 5 minutes.

After the inner layer plate 1 was washed with water to remove the alkaline aqueous solution, a treatment for removing the copper oxide film formed on the surface of the conductor pattern 2 was performed. At this time, 10
Vol% sulfuric acid was selected as the treatment liquid, and the inner layer plate 1 was immersed in the treatment liquid adjusted to 25 ° C. for 2 minutes.

The inner layer plate 1 was washed with water to remove sulfuric acid, and then the surface of the conductor pattern 2 was blackened.
In the present Example 1, a mixed aqueous solution of a strong alkali (pH = 13) containing trisodium phosphate, sodium sulfite and sodium hydroxide was adjusted to about 90 ° C. as the treatment liquid, and the inner layer plate 1 was immersed in the treatment liquid. did. By this blackening treatment, a needle-shaped crystal layer of copper oxide was newly deposited and formed on the copper on the surface of the conductor pattern 2. This needle-shaped crystal layer functions as a physical anchor for increasing the bonding force between the resin and copper when the resin-impregnated prepreg 5 is laminated on a substrate such as glass cloth.

Further, the inner layer plate 1 was washed with water to remove the blackening treatment solution, and then the inner layer plate 1 was dried at 110 ° C. for 60 minutes. Then, in the subsequent layer forming step, the inner layer plate 1
The prepreg 5 was superposed on and the press pressure of 20 kgf / cm ² was applied, so that the inner layer plate 1 and the prepreg 5 were thermocompression bonded.

The multilayer printed wiring board manufactured through the above steps is boiled for 2 hours, and then soldered at 260 ° C. for 30 hours.
A test of immersing for a second and then observing the cross section was conducted. As a result, no gap was observed on the side wall of the conductor pattern 2 and delamination was not confirmed. Further, since there was no peeling between the conductor pattern 2 of the inner layer and the insulating layer, it was suggested that this wiring board is also excellent in the adhesiveness of each layer. [Example 2] In Example 2 as well, an inner layer plate having a conductor pattern of the inner layer was first manufactured in accordance with the procedure of the full additive method. The materials and methods are in accordance with the steps of Example 1 above. However, in the second embodiment, the first embodiment
The process for treating the surface of the conductor pattern is different from that of, and various treatments described below are applied to the inner layer plate.

First, as a degreasing treatment, the inner layer plate was immersed in an alkaline aqueous solution to remove the oil and fat adhering to the surface of the conductor pattern. Next, the inner layer plate was washed with water to remove the alkaline aqueous solution, and then immersed in 10% sulfuric acid in order to remove the copper oxide film formed on the surface of the conductor pattern. In the degreasing treatment and the film removing treatment, the treatment temperature and the treatment time are the same as those in the first embodiment. Then, the inner layer plate was washed with water to remove sulfuric acid, and then treated with a silane coupling agent. The chemical agent plays a role of chemically binding the two and 5 at the interface between the conductor pattern, which is an inorganic material, and the adhesive of the prepreg, which is an organic material.

In Example 2, γ-glycidoxypropyltrimethoxysilane (manufactured by Shin-Etsu Silicone, trade name: “KBM403”) was selected as the silane coupling agent, and 0.5% by weight of the substance was added to water. Was dissolved at a ratio of. Then, the inner layer plate was immersed in this aqueous solution at room temperature for about 2 minutes. Further, the inner layer plate was washed with water to remove the aqueous solution, and then the inner layer plate was dried at 110 ° C. for 60 minutes.

Then, the same lamination molding process as in Example 1 was performed to thermocompress the inner layer plate and the prepreg. For the multilayer printed wiring board manufactured through the above steps,
When a similar test was conducted, no particular abnormality was found. From this result, it was demonstrated that the wiring board of Example 2 was also excellent in heat resistance as in Example 1. Further, it was suggested that the wiring board of Example 2 was also excellent in the adhesiveness of each layer because no peeling occurred between the conductor pattern of the inner layer and the insulating layer.

According to the manufacturing method of the second embodiment, there is an advantage that a large-scale device or the like required for the blackening process is unnecessary. Therefore, the manufacturing cost can be reduced, which is extremely preferable. [Comparative Examples 1 and 2] In Comparative Example 1, soft etching treatment was further performed in the surface roughening step for the conductor pattern performed in Example 1.

That is, after degreasing and washing with water, the inner layer plate was dipped in a soft etching solution containing sulfuric acid and hydrogen peroxide solution. The processing conditions were 40 ° C. and 90 seconds. Then, after washing with water to remove the soft etchant,
The procedure after the acid treatment was carried out.

In Comparative Example 2, after the inner layer plate was subjected to only the degreasing treatment and the acid treatment as in Example 1, the inner layer plate was washed with water without performing the blackening treatment or the silane coupling treatment. And dried. Then, according to the lamination molding process of Example 1, the prepreg and the inner layer plate were thermocompression bonded.

Comparative Example 1 manufactured through the above steps
A test of immersing the multilayer printed wiring board No. 2 in solder at 260 ° C. for 30 seconds and then observing a cross section was conducted. As a result, in the wiring board of Comparative Example 1, there is a case where a gap is generated between the side wall of the conductor pattern of the inner layer and the permanent resist,
Further, there were some cracks formed from the gaps. On the other hand, in the wiring board of Comparative Example 2, it was confirmed that the inner layer conductor pattern was peeled at the interface in contact with the prepreg. That is, these results also show the superiority of the manufacturing methods of Examples 1 and 2 above.

The present invention is not limited to the first and second embodiments, but can be modified as follows. For example, (a) the blackening treatment liquid, in addition to the treatment agent (black oxide chemical treatment liquid), copper acetate,
A mixed aqueous solution containing copper sulfate, barium sulfide and ammonium chloride (Brown Oxide chemical treatment liquid) or the like can be used.

(B) As the silane coupling agent, in addition to the above-mentioned γ-glycidoxypropyltrimethoxysilane, β- (3,4epoxycyclohexyl) ethyltrimethoxysilane (manufactured by Shin-Etsu Silicone, trade name: “KBM
-303 "), N-β- (aminoethyl) γ-aminopropyltrimethoxysilane (manufactured by Shin-Etsu Silicone, trade name:" KBM-603 "), N-phenyl-γ-aminopropyltrimethoxysilane (manufactured by Shin-Etsu Silicone) , Product name: “KBM-573”) and the like can be used.

(C) After the blackening treatment as in Example 1 to form the anchor, the silane coupling agent may be further treated. This is because according to this method, it is possible to provide the wiring board with excellent adhesion as compared with the case where the wiring boards are treated alone.

(D) The pressure at the time of thermocompression bonding the prepreg and the inner layer plate in the layer forming step is not limited to that in the first embodiment.

[0032]

As described in detail above, according to the method for manufacturing a multilayer printed wiring board of the present invention, the excellent adhesiveness of the multilayer printed wiring board formed by the full additive method is not impaired and the heat resistance is improved. It has an excellent effect that it is possible to prevent the deterioration of

[Brief description of drawings]

FIG. 1 is an enlarged cross-sectional view of a main part for explaining a method for manufacturing a multilayer printed wiring board according to a first embodiment.

FIG. 2 is an enlarged sectional view of an essential part for explaining a defect in a conventional method for manufacturing a multilayer printed wiring board.

FIG. 3 is an enlarged sectional view of an essential part for explaining a defect in the conventional method for manufacturing a multilayer printed wiring board.

[Explanation of symbols]

 2 Inner layer pattern.

Claims (2)

[Claims] 1. A method for manufacturing a multilayer printed wiring board in which an inner layer pattern is formed by a full additive method, wherein degreasing treatment, acid treatment and blackening treatment are sequentially performed on the surface of the inner layer pattern, and then lamination molding is performed. A method for manufacturing a multilayer printed wiring board, comprising: 2. In a method for manufacturing a multilayer printed wiring board in which an inner layer pattern is formed by a full additive method, a degreasing treatment, an acid treatment and a silane coupling agent treatment are sequentially performed on the inner layer pattern surface and then laminated molding is performed. A method for manufacturing a multilayer printed wiring board, which is characterized in that it is performed.