JPH1075056A - Method for manufacturing laminated board for printed wiring board - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve bonding characteristics between a copper circuit and a thermosetting resin, acid-resistance and moisture-absorption insulation reliability related to surface treatment, by processing the copper circuit with an acid aqueous solution containing pseudo-acid, copper ion and chelate material of copper ion for roughening, and coating the copper circuit with a silane compound of specific formula, for heating under specific conditions. SOLUTION: A copper circuit formed on a substrate is treated in an acid aqueous solution containing pseudo-acid, copper ion and chelate material of copper ion, for roughening the surface of the copper circuit. A silane compound expressed by the formula is applied to the surface of copper circuit, and the surface is treated by heating treatment at 105-200 deg.C for 5-90 minutes, and then the copper circuit and thermosetting resin are bonded together for manufacturing a laminated board for a printed wiring board. In the formula, R<1> represents a divalent hydrocarbon radical having 1-12 carbon atoms, and R<2> represents a monovalent hydrocarbon radical or hydrogen having 1-12 carbon atoms. Thereby, the surface of copper circuit and the silane compound are bonded rigidly, to obtain a processed surface wherein the bonding characteristics to a thermosetting resin and acid-resistance are superior.

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 laminated board for a printed wiring board, which is used for electric / electronic equipment and the like.

[0002]

2. Description of the Related Art A multilayer printed wiring board used in electric and electronic equipment is formed by etching a copper foil of an inner layer substrate to form a copper circuit, and a surface treatment is applied to the copper circuit to increase the adhesive strength. After that, the substrate for the inner layer and the prepreg manufactured by impregnating the thermosetting resin into the glass cloth are laminated, and further, the copper foil is laminated on the outer layer of the laminate, and the laminate is formed by heating and pressing. Then, a hole is punched in the multilayer laminate, the hole is subjected to through-hole plating for conducting the inner layer and the outer layer copper foil, and then the outer layer copper foil is etched to form an outer layer circuit. It is manufactured by a method of forming a solder resist film on a surface of a portion other than an outer layer circuit connected to an electronic component so that solder does not adhere.

In recent years, the quality required for printed wiring boards has become extremely high with the advancement of the functions of electronic devices. In order to improve the adhesion between the outer layer circuit and the solder resist film, the outer layer circuit is required. In addition, a method of increasing the bonding strength by performing the same surface treatment as in the case of the circuit of the substrate for the inner layer is also being studied.

The above surface treatment is generally performed by a chemical oxidation treatment called a blackening treatment. This blackening treatment is a treatment that is performed on a copper circuit to form fine irregularities on the surface and improve the adhesiveness of the copper circuit, and the surface of the copper circuit is turned into black because it becomes copper oxide. It is.

[0005] The characteristics of the treated film formed by this blackening treatment are, in addition to the adhesiveness, an acid such as a plating solution used in the through-hole plating process, which dissolves the treated film around the hole, and the black color is pink. There is a problem that a phenomenon called haloing may occur, and acid resistance is also an important characteristic.

Therefore, as a countermeasure against the occurrence of the haloing, for example, a copper oxide film is formed on the surface of an inner layer pattern formed on an inner layer substrate by an oxidation treatment as described in JP-A-7-115275. After roughening the surface,
A method of improving acid resistance by removing a portion of copper oxide that is weak to acid while leaving the surface roughened has been studied. Also, a method of roughening a copper foil with a solution containing an acid and hydrogen peroxide without performing an oxidation treatment, formic acid without performing an oxidation treatment,
A method of roughening a copper foil with a solution containing copper ions and a chelating agent for copper ions has been studied.

However, in the method described in Japanese Patent Application Laid-Open No. Hei 7-115275 for removing the copper oxide portion after the oxidation treatment, an oxidation treatment step and a copper oxide removal step are required. Therefore, there is a problem that the equipment becomes complicated, and in the case of the method of roughening the copper foil with a solution containing an acid and hydrogen peroxide, the degree of roughening of the copper foil is low and the adhesiveness is insufficient. There was a problem. Further, in the case of a method of roughening a copper foil with a solution containing a chelating agent of formic acid, copper ions and copper ions, the method is better as compared with the oxidation treatment,
There was a problem that the acid resistance was still insufficient.
Therefore, there is a need for a copper circuit processing method capable of performing a process having excellent adhesiveness and acid resistance strength without performing an oxidation process.

Therefore, the inventors of the present invention have roughened the surface of a copper circuit by treating the copper circuit with an acidic aqueous solution containing formic acid, copper ions and a chelating agent for copper ions, and then converted the silane compound having a specific structure into a copper circuit. A method of applying the composition to the surface and then performing a heat treatment was examined, and it was found that this method could provide a treatment having excellent adhesiveness and acid resistance (Japanese Patent Application No. 8-79951).

However, subsequent studies have revealed that the reliability of the moisture absorption insulation between copper circuits may be reduced in a printed wiring board using a laminate processed by the above method, depending on the processing conditions.

[0010]

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and an object of the present invention is to provide a copper circuit formed on a substrate with formic acid, copper ions and copper ions. After surface treatment with a liquid containing a chelating agent,
A method for manufacturing a laminate for a printed wiring board, which is manufactured by bonding a copper circuit and a thermosetting resin, wherein the copper circuit and the thermosetting resin have excellent adhesiveness and acid resistance, and have high moisture absorption insulation reliability. An object of the present invention is to provide an excellent method for manufacturing a laminate for a printed wiring board.

[0011]

According to a first aspect of the present invention, there is provided a method of manufacturing a laminated board for a printed wiring board, comprising the steps of: subjecting a copper circuit formed on a substrate to a surface treatment; In a method of manufacturing a laminated board for a printed wiring board manufactured by bonding, a surface treatment method comprises treating a copper circuit with an acidic aqueous solution containing formic acid, copper ions and a chelating agent for copper ions to roughen the surface of the copper circuit. After that, a silane compound represented by the following formula (a) is applied to the surface of the copper circuit,
It is a method of performing a heat treatment at a temperature of 200 ° C. for 5 to 90 minutes.

[0012]

Embedded image

According to a second aspect of the present invention, there is provided a method for manufacturing a laminated board for a printed wiring board according to the first aspect, wherein the silane compound represented by the formula (a) is used. And a silane compound represented by the following formula (b).

[0014]

Embedded image

According to a third aspect of the present invention, there is provided a method for manufacturing a laminated board for a printed wiring board according to the first or second aspect, wherein the copper circuit has the above formula (a). The method of applying a silane compound represented by the formula, a solution containing a silane compound represented by the above formula (a),
It is a method of immersing a copper circuit.

According to a fourth aspect of the present invention, there is provided a method of manufacturing a laminated board for a printed wiring board according to the third aspect, wherein the silane compound represented by the formula (a) is used. The copper ion concentration of the contained solution is 15 pp
m or less.

According to a fifth aspect of the present invention, there is provided a method of manufacturing a laminated board for a printed wiring board according to any one of the first to fourth aspects.
The thermosetting resin that adheres to the copper circuit is a thermosetting resin impregnated in a glass cloth.

According to the present invention, the surface of the roughened copper circuit obtained by the treatment with the acidic aqueous solution and the silane compound represented by the above formula (a) are firmly bonded by heat treatment to form a thermoset. A laminate for a printed wiring board having excellent adhesiveness to a water-soluble resin and excellent acid resistance and excellent in moisture absorption insulation reliability can be obtained.

[0019]

BEST MODE FOR CARRYING OUT THE INVENTION In the method of manufacturing a laminate for a printed wiring board according to the present invention, a copper circuit formed on a substrate is treated with an acidic aqueous solution containing formic acid, copper ions and a chelating agent for copper ions to form a copper circuit. After roughening the surface of the circuit, a silane compound represented by the above formula (a) is applied to the surface of the copper circuit, and then subjected to a heat treatment at 105 to 200 ° C. for 5 to 90 minutes, followed by surface treatment. It is manufactured by bonding a circuit and a thermosetting resin.

It is important that the acidic aqueous solution contains formic acid, copper ions and a chelating agent for copper ions. When any of these is not contained, it becomes difficult for the surface of the copper circuit to be uniformly roughened, and the adhesiveness is reduced.

The concentration of formic acid in the acidic aqueous solution is generally desirably 10 to 100 g / l, the concentration of copper ion is desirably 15 to 25 g / l, and a chelating agent for copper ion is preferred. The concentration of
Desirably, it is 0.1 to 10 grams / liter.
Further, the pH is desirably 4 or less, and the liquid temperature during the treatment is desirably about 32 to 43 ° C. The chelating agent is not particularly limited as long as it has a chelating effect by binding to copper ions, for example, ethylenediaminetetraacetic acid, cyclohexanediaminetetraacetic acid,
Examples thereof include 1,10-phenanthroline and 8-hydroxyquinoline. It is considered that the presence of the chelating agent facilitates the dissolution of copper on the surface of the copper circuit, leading to uniform roughening.

The time for treating the inner layer substrate using the above acidic aqueous solution is appropriately determined according to the concentration and temperature of the acidic aqueous solution, and is determined under the condition that the surface roughness of the copper circuit is 2 to 6 μm. Processing is preferred. When the thickness is 2 μm or less, the adhesiveness may decrease.
In some cases, the thickness of the copper circuit is reduced, and the electrical reliability is reduced. In the case where the treatment is performed by spraying the acidic aqueous solution onto the inner layer substrate, the treatment time can be shortened, which is preferable.

The acidic aqueous solution may contain other acids such as acetic acid, and substances such as wetting agents. Before the treatment, if necessary, the surface of the copper foil of the inner layer substrate may be washed by mechanical polishing or chemical polishing such as ammonium persulfate or copper chloride, and then may be treated with an acidic aqueous solution. .

Next, a silane compound represented by the above formula (a) is applied to the surface of the copper circuit,
For 5 to 90 minutes. It is important to carry out both the application of the silane compound and the heat treatment. If neither the application of the silane compound nor the heat treatment is carried out, the acid resistance decreases and the adhesiveness decreases. This is because the surface of the copper circuit and the silane compound are firmly bonded by the application of the silane compound and the heat treatment, and the adhesion to the thermosetting resin is excellent, and the treated surface has excellent acid resistance. Conceivable.

The conditions of this heat treatment are as follows:
Heat treatment is performed at 00 ° C. for about 5 to 90 minutes. Temperature 105
C. or less than 105 ° C.
If it is less than 10 minutes, the adhesion to the thermosetting resin may be reduced, or the acid resistance may be reduced. On the other hand, when the temperature exceeds 200 ° C., the resin of the substrate for the inner layer is denatured, and the electrical characteristics may be deteriorated. Even if the processing is performed for more than 90 minutes, the effect of improving the adhesiveness and the acid resistance is small. Not economic.

The silane compound represented by the above formula (a) is
A compound generally called an epoxy silane coupling agent. When a silane compound represented by the above formula (a) is applied to the surface of a copper circuit and then heated, the adhesiveness and the acid resistance are improved, and the moisture absorption insulation reliability is improved. Is also an excellent laminate.

The silane compound represented by the above formula (a) includes, for example, epoxy silane represented by the above formula (b) such as γ-glycidoxypropyltrimethoxysilane, and γ-glycidoxy. Propyltriethoxysilane and the like. The silane compound represented by the above formula (b) is particularly excellent in adhesiveness and acid resistance, and is preferable.

These silane compounds may be applied directly to the surface of the copper circuit by a method such as spraying, but may be applied by dipping the substrate for the inner layer on which the copper circuit is formed in a solution in which the silane compound is dissolved. In this case, the effect of improving the adhesiveness and the acid resistance is reliably obtained, which is preferable. In addition, it is preferable to use an aqueous solution containing the silane compound in an amount of 5 to 20% by weight as the liquid to be immersed in the solution in which the silane compound is dissolved.

When a copper circuit treated with an acidic aqueous solution is repeatedly immersed in a solution containing the silane compound, the concentration of copper ions in the solution may gradually increase. In this case, when the copper ion concentration in the solution containing the silane compound is 15 ppm or less, the moisture absorption insulation reliability is particularly excellent and is preferable.

After the heat treatment, the copper circuit and the thermosetting resin are bonded to produce a laminate for a printed wiring board. As the thermosetting resin used in the present invention, epoxy resin,
Phenol resin type, polyimide resin type, unsaturated polyester resin type, polyphenylene ether resin type alone,
Modified products, such as mixtures, can be used generally thermosetting resin, silica, calcium carbonate, aluminum hydroxide, inorganic powder filler such as talc, glass fiber, pulp fiber, synthetic fiber, if necessary A fibrous filler such as ceramic fibers can be included. The thermosetting resin is manufactured by impregnating the base material such as glass cloth with the thermosetting resin.In the case of the thermosetting resin impregnated into a resin-impregnated base material generally called a prepreg, the adhesiveness and the acid resistance strength are improved. Although the effect of improving is preferably large, it is not limited to only the thermosetting resin used for the prepreg, and the surface of the inner layer substrate is bonded to a metal foil via a thermosetting resin layer without a base material. The thermosetting resin of the thermosetting resin layer in the case of manufacturing, or a thermosetting resin which adheres to an outer layer circuit such as a solder resist may be used.

The substrate for the inner layer used in the present invention may be a plate having a copper circuit formed on one or both sides using a material that can withstand the temperature of the above-mentioned heat treatment. A sheet in which a copper foil is stretched on one or both sides of a sheet of the sheet, a cloth of inorganic fibers such as glass or an organic fiber such as polyimide, or a substrate such as paper, is adhered with the thermosetting resin, and one or both sides are bonded. Using a plate or the like with copper foil on it, etching the copper foil to form a circuit, or copper plating on the surface of the board without copper foil,
One in which a copper circuit is formed, and the like can be given.

[0032]

【Example】

(Example 1) Copper foil (35 μm in thickness) of 50 × 50 cm, double-sided glass substrate epoxy resin copper-clad laminate [trade name: R-1766 manufactured by Matsushita Electric Works, Ltd.] having a thickness of 0.8 mm excluding copper foil Is etched to JIS C501
2 A circuit having a circuit width of 300 μm, a space between circuits of 150 μm, and a length of 50 mm according to the insulation resistance test pattern of the inner layer of the composite pattern for a multilayer printed circuit board is 2
An inner layer substrate was obtained in which a plurality of patterns each composed of zero and a land pattern having a diameter of 1.5 mm were formed.

As an acidic aqueous solution containing a chelating agent for formic acid and copper ions, copper hydroxide is dissolved in 20 g / l by dissolving copper hydroxide using a processing solution [CZ8100] manufactured by Mec Co., Ltd. Do
An acidic aqueous solution having a pH of 3.5 was prepared.

After the acidic aqueous solution was heated to 38 ° C., the surface of the copper circuit was roughened by spraying for 2 minutes on the inner layer substrate on which the copper circuit was formed. Then, after washing with water, 1 minute in an aqueous solution containing 11% by weight of γ-glycidoxypropyltrimethoxysilane [manufactured by Shin-Etsu Chemical Co., Ltd., trade name: KBM403] as a silane compound represented by the above formula (a). After immersion, heat treatment was performed at 140 ° C. for 30 minutes. In addition, when the copper ion concentration of the aqueous solution containing the silane compound was measured by argon plasma emission spectroscopy, it was 6 ppm.

The surface roughness of the obtained copper circuit was measured with a surface roughness meter [Surfcom, manufactured by Tokyo Seimitsu Co., Ltd.] to a needle diameter of 5 μm.
m, a scanning length of 10 mm, and a scanning speed of 0.3 mm / sec, Rmax (maximum roughness) was measured.
m.

Next, a thickness of 0.15
mm, a glass-based epoxy resin prepreg having a resin amount of 50% [trade name: R-1661, manufactured by Matsushita Electric Works, Ltd.] is laminated on both sides of the inner layer substrate by two sheets, and further, both outer layers of the laminate are laminated. Then, a copper foil having a thickness of 18 μm was laminated thereon, and this laminate was heated and pressed under the conditions of a temperature of 170 ° C., a pressure of 3.9 MPa and a time of 60 minutes to obtain a laminate for a printed wiring board.

Example 2 A laminated board for a printed wiring board was obtained in the same manner as in Example 1 except that it was immersed in an aqueous solution containing a silane compound, and then heat-treated at 105 ° C. for 5 minutes.

Example 3 A laminate for a printed wiring board was obtained in the same manner as in Example 1 except that the aqueous solution containing the silane compound was treated with an aqueous solution having a copper ion concentration of 14 ppm.

Example 4 A laminated board for a printed wiring board was obtained in the same manner as in Example 1 except that the aqueous solution containing the silane compound was treated with an aqueous solution having a copper ion concentration of 18 ppm.

(Comparative Example 1) A laminated board for a printed wiring board was obtained in the same manner as in Example 1 except that it was immersed in an aqueous solution containing a silane compound, and then heat-treated at 80 ° C for 5 minutes.

Comparative Example 2 A laminated board for a printed wiring board was obtained in the same manner as in Example 1 except that it was immersed in an aqueous solution containing a silane compound, and then heat-treated at 80 ° C. for 90 minutes.

Comparative Example 3 A laminated board for a printed wiring board was obtained in the same manner as in Example 1 except that it was immersed in an aqueous solution containing a silane compound, and then heat-treated at 140 ° C. for 1 minute.

Comparative Example 4 The same procedure as in Example 1 was carried out except that an aqueous solution containing 11% by weight of γ-aminopropyltriethoxysilane [trade name: KBE903, manufactured by Shin-Etsu Chemical Co., Ltd.] was used as the silane compound. Thus, a laminate for a printed wiring board was obtained. In this case, an aqueous solution having a copper ion concentration of 6 ppm measured in the same manner as in Example 1 was used.

Comparative Example 5 A laminated board for a printed wiring board was obtained in the same manner as in Example 1 except that heat treatment was performed without immersion in an aqueous solution containing a silane compound.

Comparative Example 6 A laminate for a printed wiring board was obtained in the same manner as in Example 1, except that the laminate was not immersed in an aqueous solution containing a silane compound without being treated with an acidic aqueous solution. In addition, when the surface roughness of the copper circuit treated with the acidic aqueous solution was measured in the same manner as in Example 1, it was 0.3 μm.

(Evaluation and Results) Examples 1-4 and Comparative Example 1
The acid resistance, inner layer copper foil peeling strength and moisture absorption insulation reliability of the laminates obtained in Nos. To 6 were measured.

The acid resistance is determined by using a drill having a diameter of 0.4 mm (trade name: UC30, manufactured by Union Tool Co., Ltd.) at a position where a land pattern having a diameter of 1.5 mm is present on the inner layer substrate, at a rotation speed of 72,000 revolutions / minute. 50 holes were drilled at a feed rate of 19 μm / rotation, then immersed in a 1.2N aqueous hydrochloric acid solution at 20 ° C. for 10 minutes, immediately washed with water, and then the outer layer copper foil and prepreg were cured. The insulating layer was shaved, the copper circuit of the inner layer substrate was exposed, and the maximum length from the wall surface of the hole at the portion where the treated film turned pink was measured with a magnifying glass of 50 times.

The peel strength of the inner layer copper foil is obtained by measuring the adhesive force between the surface treated surface of the copper circuit of the inner layer substrate and the prepreg layer. 1 for copper circuit of inner layer substrate with exposed surface
A line having a width of 0 mm was formed, and the peeling strength of the line in the 90-degree direction was measured at a peeling speed of 50 mm / min.

The moisture absorption insulation reliability is as follows. After exposing a predetermined position of the copper circuit of the inner layer substrate, a PCT (pressure cooker test) process at 110 ° C. is continuously performed while applying a voltage of 48 V, and the insulation resistance is measured. The mean time to failure (MTTF) until was reduced to 10 6 Ω or less was determined.

The results are shown in Tables 1 and 2,
Although each example has the same moisture absorption insulation reliability as Comparative Examples 1 to 3, it was confirmed that the acid resistance and the peel strength of the inner copper foil were excellent. Further, in each example, the acid resistance and the peel strength of the inner layer copper foil were the same as those of Comparative Example 4 in which the silane compound was treated with a silane compound different from the silane compound represented by the above formula (a). It was confirmed that the reliability was excellent. In addition, it was confirmed that each example had better acid resistance than Comparative Example 5 not immersed in an aqueous solution containing a silane compound and Comparative Example 6 not treated with an acidic aqueous solution. That is, it was confirmed that each of the examples was excellent in the adhesiveness and the acid resistance, and also was excellent in the hygroscopic insulation reliability, but each comparative example was inferior in at least one of the adhesiveness, the acid resistance and the hygroscopic insulation reliability.

[0051]

[Table 1]

[0052]

[Table 2]

[0053]

According to the method of manufacturing a laminate for a printed wiring board according to the present invention, a copper circuit formed on a substrate is treated with an acidic aqueous solution containing formic acid, copper ions and a chelating agent for copper ions to form a copper circuit. After roughening the surface of the above, the silane compound represented by the above formula (a) is applied to the surface of the copper circuit, and then heat-treated at 105 to 200 ° C. for 5 to 90 minutes, and then the copper circuit is treated. The surface of the roughened copper circuit obtained by treatment with an acidic aqueous solution and the silane compound are firmly bonded by heat treatment to produce a thermosetting resin by bonding with the thermosetting resin. A laminate for a printed wiring board having excellent adhesiveness to resin, excellent acid resistance, and excellent moisture absorption insulation reliability can be obtained.

Claims (5)

[Claims] 1. A method for manufacturing a laminate for a printed wiring board, which comprises bonding a copper circuit formed on a substrate to a surface, and then bonding the copper circuit to a thermosetting resin. After treating the copper circuit with an acidic aqueous solution containing copper ions and a chelating agent for copper ions to roughen the surface of the copper circuit, a silane compound represented by the following formula (a) is applied to the surface of the copper circuit. And a heat treatment at 105 to 200 [deg.] C. for 5 to 90 minutes. Embedded image 2. The method for producing a laminate for a printed wiring board according to claim 1, wherein the silane compound represented by the formula (a) is a silane compound represented by the following formula (b). . Embedded image 3. A method of applying a silane compound represented by the above formula (a) to a copper circuit is a method of immersing the copper circuit in a solution containing the silane compound represented by the above formula (a). The method for producing a laminate for a printed wiring board according to claim 1 or 2, wherein: 4. The method for producing a laminate for a printed wiring board according to claim 3, wherein the copper ion concentration of the solution containing the silane compound represented by the formula (a) is 15 ppm or less. 5. The printed wiring board according to claim 1, wherein the thermosetting resin that adheres to the copper circuit is a thermosetting resin impregnated in a glass cloth. A method for manufacturing a laminate.